JP2003285262A - Duplex polishing apparatus and duplex polishing method for wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a duplex polishing apparatus and a duplex polishing method for wafer, by which the shape of the wafer can be accurately controlled by accurately controlling the shape of a surface plate even if aged deterioration of polishing ability of abrasive cloth, etc., are caused by its life limit, loading, etc., and the wafer can be stably polished even when a plurality of batches of the wafers have been repeatedly polished. <P>SOLUTION: The duplex polishing apparatus includes at least a carrier plate having wafer holding bores, an upper surface plate and a lower surface plate having a grinding cloth stuck thereon, and a slurry supplying means. The duplex polishing apparatus simultaneously polishes both front and back surfaces of the wafers by holding the wafers in the wafer holding bores and moving the carrier plate between the upper surface plate and the lower surface plate while supplying slurry. The duplex polishing apparatus is characterized in that a load fulcrum portion of the upper surface plate has a shape adjusting means. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus and a polishing method capable of stably maintaining the quality of a wafer which changes with time when polishing a wafer using a double-side polishing apparatus, and more particularly, The present invention relates to a double-sided polishing apparatus and a double-sided polishing method for a wafer, which controls a wafer shape by controlling at least an upper surface plate of a double-sided polishing apparatus that simultaneously polishes both front and back surfaces of a wafer.

[0002]

2. Description of the Related Art A conventional method for producing a wafer will be described by taking a method for producing a silicon wafer as an example. First, a silicon single crystal ingot is grown by the Czochralski method (CZ method) or the like, and the obtained silicon single crystal is obtained. After slicing the ingot to produce a silicon wafer, each of the steps of chamfering, lapping, and etching is sequentially performed on the silicon wafer, and then at least a polishing step of mirror-finishing one main surface of the wafer is performed.

In this wafer polishing step, for example, when polishing both surfaces of a silicon wafer, a double-side polishing machine may be used. As this double-sided polishing device, a so-called 4-way double-sided polishing device having a planetary gear structure in which a carrier plate for holding a wafer is disposed between a central sun gear and an outer peripheral internal gear is usually used. There is.

This 4-way double-sided polishing machine inserts and holds a silicon wafer into a plurality of carrier plates having wafer holding holes, and supplies the polishing slurry from above the held silicon wafer while the wafer is being held. By pressing the upper surface plate and the lower surface plate with the polishing cloth attached to the opposite surface against the front and back surfaces of each wafer and rotating them in the relative direction, at the same time, the carrier plate is rotated and revolved by the sun gear and the internal gear. Both sides of the wafer can be polished simultaneously.

As a double-sided polishing apparatus of another form, for example, a double-sided polishing apparatus as disclosed in Japanese Patent Application Laid-Open No. 10-202511 is known. FIG. 4 shows a schematic cross-sectional explanatory view of the double-side polishing apparatus. This double-sided polishing device 41 has a carrier plate 46 having a plurality of wafer holding holes for holding a silicon wafer 44, and a polishing cloth 45 which is arranged in the up-down direction of the carrier plate 46 and simultaneously polishes both front and back surfaces of the silicon wafer 44. Upper surface plate 42 and lower surface plate 4 attached to the opposite surface of the wafer
3, carrier movement means (not shown) for moving the carrier plate 46 sandwiched by the upper surface plate 42 and the lower surface plate 43 in a plane parallel to the surface thereof. The upper surface plate 42 includes a cylinder 47 for applying a rotation and polishing load, a housing 48 for transmitting the load to the upper surface plate 42, and a fixing means 49 such as a bolt for fixing the housing 48 and the upper surface plate 42. is set up. On the other hand, the lower surface plate 43 is provided with a cylinder 47 that gives rotation from a motor and a speed reducer (not shown) to the lower surface plate 43, and a thrust bearing 50 that supports the load of the surface plate.

In such a double-side polishing apparatus 41, the carrier plate 46 sandwiched between the upper surface plate 42 and the lower surface plate 43 passes through the carrier holder 51 by the carrier moving means (not shown) and makes a circular motion without rotation. That is, the carrier plate 46 is allowed to perform a kind of swinging motion in which the carrier plate 46 rotates while maintaining a state of being eccentric for a predetermined distance from the rotation axes of the upper surface plate 42 and the lower surface plate 43 without rotating. Further, at this time, since the silicon wafer 44 is rotatably held in the wafer holding hole of the carrier plate 46, the upper surface plate and the lower surface plate are rotated about the rotation axis at different rotation speeds and directions. As a result, it is possible to rotate (rotate) the surface plate having a high rotation speed in the rotation direction.

Therefore, when the silicon wafer is polished on both sides, the silicon wafer is inserted and held in each wafer holding hole of the carrier plate, and the slurry containing the abrasive grains is supplied to the silicon wafer while the upper surface plate and the lower surface plate are supplied. By rotating the wafers at different rotation speeds and directions to rotate the wafer itself in the holding holes, and by causing the carrier plate to perform a circular motion without rotation,
Both front and back surfaces of a silicon wafer can be polished simultaneously and uniformly. The double-sided polishing machine having such a configuration can easily perform double-sided polishing even on a large-diameter wafer,
With the recent increase in the diameter of wafers, they have come to be widely used.

However, a plurality of batches of wafers are repeatedly polished by using the 4-way double-sided polishing apparatus or the double-sided polishing apparatus for polishing the wafer by causing the carrier plate to perform circular motion without rotation as described above. In this case, the life of the polishing cloth attached to the upper and lower stools, clogging, etc. affect the polishing ability of the polishing cloth, etc. over time. Therefore, when a plurality of batches of wafers are polished without replacing the polishing cloth, the shape of the wafers to be polished changes with time as the number of polishing batches increases, and the wafer shapes differ from batch to batch. There was a problem that the stable quality of could not be maintained.

In order to solve such a problem, conventionally,
Wafers are polished by controlling changes in the shape of the wafer over time by changing various polishing conditions according to changes over time such as the polishing ability of the polishing cloth. For example, there is a method in which the shape of the surface plate is deformed by changing conditions such as the temperature of the surface plate to control the shape of the wafer.

Normally, it is considered that the surface plate used in the double-sided polishing machine or the like is one in which the shape of the surface plate is not deformed when the wafer is polished, but such a shape is not deformed when the wafer is polished. When a surface plate is used, it becomes difficult to match the surface plate and the wafer when various polishing conditions are changed, and it becomes impossible to control the shape of the wafer against changes with time such as the polishing ability of the polishing cloth. In order to avoid such difficulty of controlling the wafer shape, generally, the surface plate is made of a material that is deformed to some extent,
In particular, a material that deforms due to temperature change is used, and the wafer shape can be controlled by flowing cooling water or the like into the surface plate to change the temperature of the surface plate and deform the surface plate shape.

However, even if an attempt is made to control the wafer shape by flowing cooling water or the like into the surface plate to change the temperature of the surface plate as described above, conventional double-sided polishing responds to the deformation of the surface plate with respect to the temperature change of the surface plate. (The linearity with respect to the temperature change of the surface plate) is poor, and the shape of the surface plate cannot be controlled accurately. Especially when the polishing conditions etc. are greatly changed during wafer polishing, it is only possible to control the temperature inside the surface plate. There is a problem that the surface plate cannot be controlled to have a desired shape. Further, when repeatedly polishing a plurality of batches of wafers, the responsiveness of the surface plate deformation is poor, so that it becomes difficult to control the surface plate shape as desired as the number of batches of the wafer increases, and the wafer shape is batch by batch. It could not be controlled stably and with high precision. In particular, when a large-diameter wafer such as a 300 mm diameter is repeatedly polished in a plurality of batches, the wafer tends to have a medium convex shape, and GBIR (Glob
Deterioration of the wafer shape such as deterioration of flatness such as al back ideal range) was remarkably observed. In other words, it was not possible to sufficiently control the wafer shape which changes with time simply by controlling the temperature in the surface plate as in the conventional case.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and the present invention is directed to the change with time of polishing ability and the like due to the life and clogging of the polishing cloth. By controlling the surface plate shape with high accuracy, the wafer shape can be controlled with high accuracy, and even if the wafer is repeatedly polished in multiple batches, it can be stably polished with high accuracy. The purpose is to provide a method.

[0013]

In order to achieve the above object, according to the present invention, at least a carrier plate having a wafer holding hole, an upper surface plate and a lower surface plate to which a polishing cloth is attached, and a slurry supplying means. Holding the wafer in the wafer holding hole, while supplying the slurry, in the double-sided polishing apparatus for simultaneously polishing the front and back surfaces of the wafer by moving the carrier plate between the upper and lower surface plate, the above-mentioned A double-sided polishing apparatus for a wafer is provided, which has shape adjusting means at a load fulcrum portion of the board.

As described above, in the double-sided polishing apparatus having at least the carrier plate, the upper platen, the lower platen, and the slurry supplying means, the carrier plate is moved between the upper and lower platens to polish the front and back surfaces of the wafer, If it is a double-sided polishing device having a shape adjusting means at the load fulcrum part of the upper surface plate,
Since the shape of the upper surface plate can be forcibly deformed by the shape adjusting means, it is necessary to properly control the shape of the surface plate according to changes with time such as the polishing ability of the polishing cloth when polishing the wafer. You can As a result, the wafer shape can be precisely stabilized and polished, and even when repeatedly polishing a plurality of batches of wafers, the wafer shape can be easily controlled for each batch without deteriorating the shape of the wafer. It becomes a device that can perform polishing.

At this time, it is preferable that the movement of the carrier plate is a circular movement that is not accompanied by rotation of the carrier plate. In this way, the movement of the carrier plate is a circular movement without rotation of the carrier plate, that is, the carrier plate does not rotate and maintains a state of being eccentric for a predetermined distance from the rotation axes of the upper surface plate and the lower surface plate. If it is a swinging motion that swivels, all points on the carrier plate will draw a locus of a small circle of the same size, so that polishing is performed uniformly over the entire front and back polishing surfaces of the wafer. be able to.

At this time, the PCD of the upper platen load fulcrum which is the diameter of the circle when the load fulcrum of the upper platen is connected by a circle.
And the PCD of the center of the holding hole of the carrier plate, which is the diameter of the circle when the centers of the holding holes of the carrier plate are connected by a circle, are made to coincide (claim 3).

As described above, the PCD (Pit) of the upper platen load fulcrum which is the diameter of the circle when the load fulcrum of the upper platen is connected by a circle.
ch Double Diameter) and a double-sided polishing machine in which the PCD of the center of the holding hole of the carrier plate, which is the diameter of the circle when the centers of the respective holding holes of the carrier plate are connected by a circle, are matched. It is possible to further improve the responsiveness of the surface plate deformation to the adjustment and the adjustment of the slurry supply amount, and to easily and accurately control the surface plate shape.

Further, according to the present invention, at least a plurality of carrier plates having wafer holding holes, a sun gear and an internal gear for rotating and revolving the carrier plates, an upper platen and a lower plate to which a polishing cloth is attached. A plate, and a slurry supply means, holding the wafer in the wafer holding hole, while supplying the slurry, by rotating and revolving a plurality of carrier plates between the upper and lower surface plate, the front and back surfaces of the wafer A double-sided polishing apparatus for polishing simultaneously is provided with a shape adjusting means at a load fulcrum portion of the upper platen (claim 4).

Thus, at least the carrier plate, the sun gear, the internal gear, the upper surface plate, the lower surface plate, and the slurry supply means are provided, and the plurality of carrier plates are rotated and revolved between the upper and lower surface plates. In a double-sided polishing device for polishing both front and back surfaces of a wafer, if the double-sided polishing device has shape adjusting means at the load fulcrum part of the upper surface plate,
Since the shape of the upper surface plate can be forcibly deformed by the shape adjusting means, it is necessary to properly control the shape of the surface plate according to changes with time such as the polishing ability of the polishing cloth when polishing the wafer. You can As a result, the wafer shape can be precisely stabilized and polished, and even when repeatedly polishing a plurality of batches of wafers, the wafer shape can be easily controlled for each batch without deteriorating the shape of the wafer. It becomes a device that can perform polishing.

At this time, the PCD of the upper surface plate load fulcrum, which is the diameter of the circle when the load fulcrums of the upper surface plate are connected by a circle, and the circle when the centers of the plurality of carrier plates are connected by a circle. It is preferable that the PCD at the center of the carrier plate, which is the diameter, is matched.

Thus, the PCD of the upper surface plate load fulcrum, which is the diameter of the circle when the load fulcrums of the upper surface plate are connected by a circle, and the circle when the centers of the plurality of carrier plates are connected by a circle. With a double-sided polishing device that matches the PCD of the diameter of the carrier plate, it is possible to further improve the responsiveness of the platen deformation to the adjustment of the shape adjusting means and the adjustment of the slurry supply amount, and the accuracy can be easily increased. The surface plate shape can be controlled well.

Further, it is preferable that the shape adjusting means is a micrometer. In this way, if the shape adjusting means is a micrometer, by adjusting the micrometer, the upper surface plate can be mechanically pressed by a desired size and forcedly deformed. Can be accurately deformed.

Further, it is preferable that the material of the platen is stainless steel. Thus, if the surface plate is made of stainless steel, the surface plate can be appropriately deformed, so that the surface plate can be easily deformed by the shape adjusting means or the like.

In the double-sided wafer polishing method according to the present invention, the wafer is held in the wafer holding holes formed in the carrier plate, and while the slurry is supplied, the upper surface plate and the lower surface plate to which the polishing cloth is adhered are attached. In a double-sided polishing method in which the front and back surfaces of the wafer are simultaneously polished by moving the carrier plate between them, the double-sided polishing of the wafer is characterized in that the supply amount of the slurry is adjusted and the surface plate shape is controlled and polished. Method (claim 8).

In the double-sided polishing method for simultaneously polishing both front and back surfaces of a wafer as described above, the temperature of the polishing surface can be controlled by adjusting the slurry supply amount and polishing, and the surface plate shape can be excellently responsive. Can be controlled.
Thereby, stable polishing can be performed without deteriorating the wafer shape.

At this time, it is preferable that the movement of the carrier plate is a circular movement that does not involve the rotation of the carrier plate. Thus, by making the movement of the carrier plate a circular movement that does not involve the rotation of the carrier plate, it is possible to uniformly polish the entire front and back polishing surfaces of the wafer held by the carrier plate.

Furthermore, according to the present invention, the wafers are held on a plurality of carrier plates having holding holes for holding the wafers, and while the slurry is being supplied, the upper surface plate and the lower surface plate to which the polishing cloth is attached are attached. In the double-sided polishing method in which the plurality of carrier plates are rotated and revolved by a sun gear and an internal gear, and both the front and back surfaces of the wafer are simultaneously polished, the supply amount of the slurry is adjusted to control the surface plate shape. A double-sided polishing method for a wafer is provided, which comprises polishing while polishing (claim 10).

In the double-sided polishing method for simultaneously polishing the front and back surfaces of a wafer as described above, the temperature of the polishing surface can be controlled by polishing by adjusting the supply amount of slurry, and the surface plate shape can be excellently responsive. Can be controlled.
Thereby, stable polishing can be performed without deteriorating the wafer shape.

At this time, it is preferable that the supply amount of the slurry is adjusted according to the usage time of the polishing cloth (claim 11). In this way, by adjusting the supply amount of the slurry according to the usage time of the polishing cloth, it is possible to accurately control the shape of the platen in accordance with the change with time of the polishing ability of the polishing cloth. For example, the slurry supply amount may be adjusted so that the slurry supply amount decreases as the polishing cloth is used for a longer period of time. By adjusting the slurry supply amount in this manner, a plurality of batches of wafers are adjusted. Even when polishing is repeatedly performed, stable polishing can be performed without deteriorating the wafer shape.

Further, in the method for polishing both sides of a wafer according to the present invention, the wafer is held in the wafer holding holes formed in the carrier plate, and while supplying the slurry, the upper surface plate and the lower surface plate to which the polishing cloth is attached are attached. In a double-sided polishing method in which the front and back surfaces of the wafer are simultaneously polished by moving the carrier plate between them, a shape adjusting means is provided at the load fulcrum portion of the upper surface plate, and the surface adjusting shape is adjusted by adjusting the shape adjusting means. A double-sided polishing method for a wafer, which is characterized by polishing while controlling (claim 12).

In the double-sided polishing method for simultaneously polishing both the front and back surfaces of a wafer as described above, a shape adjusting means is provided at the load fulcrum portion of the upper surface plate, and the surface shape is controlled by adjusting the shape adjusting means. By polishing, the shape of the upper surface plate can be forcibly deformed by the shape adjusting means, so that the shape of the surface plate can be changed in accordance with changes with time such as the polishing ability of the polishing cloth when polishing the wafer. It can be controlled appropriately. As a result, the wafer shape can be stably stabilized with high accuracy, and even when a plurality of batches of wafers are repeatedly polished, the wafer shape can be controlled accurately without deteriorating the shape of the wafer and stable polishing can be performed. be able to.

At this time, it is preferable that the movement of the carrier plate is a circular movement that is not accompanied by rotation of the carrier plate. Thus, by making the movement of the carrier plate a circular movement that does not involve the rotation of the carrier plate, it is possible to uniformly polish the entire front and back polishing surfaces of the wafer held by the carrier plate.

Further, according to the present invention, the wafers are held on a plurality of carrier plates having holding holes for holding the wafers, and while the slurry is being supplied, the upper surface plate and the lower surface plate to which the polishing cloth is attached are attached. In the double-sided polishing method in which the plurality of carrier plates are rotated and revolved with a sun gear and an internal gear, and both the front and back surfaces of the wafer are simultaneously polished, a shape adjusting means is provided in the load fulcrum portion of the upper surface plate. There is provided a double-sided polishing method for a wafer, which comprises polishing while controlling the shape of a surface plate by adjusting the shape adjusting means (claim 14).

In the double-sided polishing method for simultaneously polishing the front and back surfaces of a wafer as described above, a shape adjusting means is provided at the load fulcrum portion of the upper surface plate, and polishing is performed while controlling the shape of the surface plate by adjusting the shape adjusting means. By doing so, the shape of the upper platen can be forcibly deformed by the shape adjusting means, so that the shape of the platen can be appropriately adjusted according to changes with time such as the polishing ability of the polishing cloth when polishing the wafer. Can be controlled. As a result, the wafer shape can be stably stabilized with high accuracy, and even when a plurality of batches of wafers are repeatedly polished, the wafer shape can be controlled accurately without deteriorating the shape of the wafer and stable polishing can be performed. be able to.

At this time, it is preferable that the amount of the slurry to be supplied is adjusted to control the shape of the platen to perform polishing. As described above, by providing the shape adjusting means at the load fulcrum portion of the upper surface plate and further adjusting the supply amount of the slurry to be supplied in this way, the surface plate shape can be controlled with higher accuracy. It is possible to reliably prevent the deterioration of the shape.

Further, at this time, the PCD of the upper platen load fulcrum which is the diameter of the circle when the load fulcrum of the upper platen is connected by a circle.
And the PCD of the wafer center, which is the diameter of the circle when the centers of the wafers held on the carrier plate are connected by a circle
Alternatively, it is preferable that the center of the carrier plates, which is the diameter of the circle when the centers of the plurality of carrier plates are connected by a circle, is aligned with the center of the carrier plate for polishing.

In the above-mentioned double-sided polishing method, the PCD of the upper platen load fulcrum, which is the diameter of the circle when the load fulcrums of the upper platen are connected by a circle, and the center of the wafer held on the carrier plate are circled. PCD at the center of the wafer, which is the diameter of the circle when joined, or P at the center of the carrier plate, which is the diameter of the circle when the centers of the plurality of carrier plates are joined by a circle
By polishing the CD so as to match it, it is possible to control the surface plate shape by adjusting the amount of the slurry supplied and adjusting the shape adjusting means such as a micrometer with excellent responsiveness. As a result, the surface plate shape can be accurately controlled against changes over time in the wafer shape, and even when repeatedly polishing a plurality of batches of wafers, the shape of the wafer can be accurately controlled and stable polishing can be performed. You can

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below, but the present invention is not limited thereto. When a wafer is polished using a conventionally used double-sided polishing machine such as that shown in FIG. 4, the response of the plate deformation is poor only by controlling the plate temperature. It could not be controlled well, and the wafer shape could not be controlled stably and with high precision.

Therefore, in order to solve the above problems, the present inventor adjusted the amount of slurry supplied during polishing as a method of controlling the shape of the surface plate in addition to controlling the temperature of the surface plate. To control the shape of the platen by controlling the shape of the platen by controlling the shape of the platen by adjusting the shape adjusting means at the load fulcrum of the upper platen and adjusting the shape adjusting means. The invention was completed.

First, an example of a double-sided wafer polishing apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional explanatory view of a double-side polishing apparatus according to the present invention. This double-sided polishing apparatus 1 includes a carrier plate 6 having a wafer holding hole, an upper surface plate 2 and a lower surface plate 3 to which a polishing cloth 5 is attached,
And a slurry supply means 16 for supplying the slurry. The wafer 4 is inserted into and held in the wafer holding hole of the carrier plate 6, and is sandwiched between the upper surface plate 2 and the lower surface plate 3 from above and below to provide the slurry supply means. By rotating the upper surface plate 2 and the lower surface plate 3 about a rotation axis perpendicular to the wafer 4 while supplying the slurry from 16, the front and back surfaces of the wafer 4 can be simultaneously polished.

The upper surface plate 2 has a cylinder 7 for applying a rotation and polishing load, a housing 8 for transmitting the load to the upper surface plate 2, and a fixing means 9 such as a bolt for fixing the housing 8 and the upper surface plate 2. Is installed, and the upper surface plate 2
Temperature control means (not shown) for controlling the temperature of the surface plate
It is equipped with. The temperature control means is not particularly limited, but cooling water and hot water can be supplied to the pipes arranged in the surface plate.

The upper surface plate 2 is held in the housing 8 by fixing means 9 such as bolts, and when the wafer is polished, a predetermined load is applied to the upper surface plate 2 to perform the polishing. Therefore, the load fulcrum of the upper surface plate 2 is at the fixing means 9 which is a joint portion between the upper surface plate 2 and the housing 8.

The double-side polishing apparatus 1 of the present invention has a load fulcrum portion near the fixing means 9 which is a load fulcrum of the upper surface plate 2, for example, FIG.
As shown in FIG. 3, the shape adjusting means 15 is installed at two points on the outer peripheral side and the center side of the fixing means 9, and the installed shape adjusting means 15
By adjusting, the upper surface plate 2 can be mechanically pressed to forcibly deform its shape. As described above, the double-sided polishing apparatus of the present invention adjusts the shape adjusting means 15 according to the change with time of the polishing ability of the polishing cloth 5 when polishing the wafer to force the shape of the upper surface plate 2. Since it can be controlled with high precision, the double-sided polishing apparatus can polish the wafer with high precision and stability.

At this time, the shape adjusting means 15 is not particularly limited, but is preferably a micrometer, for example. Thus, if the shape adjusting means is a micrometer, by accurately adjusting the micrometer, the upper surface plate can be mechanically pressed by a desired size to be forcedly deformed. Can be accurately deformed into a desired shape.

On the other hand, the lower platen 3 has a cylinder 7 for giving rotation from a motor and a speed reducer (not shown) to the lower platen.
A thrust bearing 10 for supporting the load of the surface plate is installed, and a temperature adjusting means (not shown) for controlling the temperature of the surface plate is provided in the lower surface plate as in the upper surface plate.

The material of the upper surface plate 2 and the lower surface plate 3 is preferably stainless steel (SUS). As described above, when the surface plate is made of stainless steel (SUS), the surface plate can be appropriately deformed, so that the surface plate can be easily deformed by the shape adjusting means or the like. Further, the kind and material of the polishing cloth 5 that is attached to the lower surface of the upper surface plate 2 and the upper surface of the lower surface plate 3 to make the front and back surfaces of the wafer mirror-like are not particularly limited, but for example,
It is possible to use a hard urethane foam pad which is a general polishing cloth, a soft non-woven cloth pad obtained by impregnating and curing a non-woven cloth with a urethane resin, and the like. For example, Suba600 manufactured by Rodel Co. is used as the soft non-woven fabric. In addition, a polishing cloth having two or more layers obtained by foaming urethane resin on a base cloth made of a non-woven fabric can be used.

Further, the slurry supply means 16 is constituted by providing a slurry supply hole on the upper surface plate through a rotary joint (not shown). For example, the amount of slurry supplied is changed by an electromagnetic valve or the like (not shown). be able to.
Further, a plurality of slurry supplying means can be formed, and for example, even if the carrier plate is rocked, the slurry is always supplied to the surface of the wafer in an annular region of a predetermined width in which the wafer is always present. It is preferably arranged.

Further, the carrier plate 6 has, for example, five wafer holding holes formed in a disc-shaped plate, and the wafer 4 can be rotatably held in the wafer holding holes. The material of the carrier plate 6 is not particularly limited, but it is preferable to use, for example, glass epoxy.

The carrier plate 6 is held at its outer peripheral portion by the annular portion 11 (b) of the carrier holder 11, and within the plane (horizontal plane) parallel to the carrier plate surface without the carrier plate itself rotating. It can be moved circularly. In addition, the annular portion 11 (b) of the carrier holder 11
A plurality of bearing portions 11 (a) protruding outward are arranged on the outer periphery of the bearing. Each bearing part 11 of this carrier holder
(A) shows an eccentric shaft 1 of an eccentric arm 12 having a small-diameter disk shape.
2 (a) is inserted and attached, and a rotating shaft 12 (b) is vertically provided at the center of each lower surface of the eccentric arm 12.
Further, sprockets 13 are fixed to the tips of the rotary shafts 12 (b), and a timing chain 14 is horizontally laid between the sprockets 13 in series. The sprocket 13 and the timing chain 14 constitute a synchronizing means for rotating the plurality of eccentric arms 12 in synchronization.

Then, a circular motion motor (not shown) connected to one of the sprockets 13 is actuated to rotate one of the sprockets 13, and the timing chain 14 is rotated through the sprockets 13. By rotating the timing chain, a plurality of eccentric arms 1
2 synchronously rotate in the horizontal plane about the rotation axis 12 (b). As a result, the carrier holder 11 connected to each eccentric arm 12 and the carrier plate 6 held by the carrier holder 11 are placed in the horizontal plane parallel to the carrier plate, and the eccentric shaft 1 of the eccentric arm 12 is
It is possible to perform a circular motion that eccentrically rotates from the rotation shafts of the upper and lower surface plates 2 and 3 at the same interval as the distance between 2 (a) and the rotation shaft 12 (b).

As described above, by causing the carrier plate 6 to make a circular motion without rotation, all points on the carrier plate 6 draw a locus of a small circle of the same size, whereby the carrier plate 6 is made. The wafer 4 held by can be uniformly polished over the entire front and back polishing surfaces.

In such a double-side polishing apparatus 1, the PCD (Pitch circle circle) of the upper platen load fulcrum which is the diameter of the circle when the load fulcrums of the upper platen 2 are connected by a circle.
It is preferable to match the (meter) with the PCD of the center of the holding hole of the carrier plate, which is the diameter of the circle when the centers of the holding holes of the carrier plate 6 are connected by a circle.

More specifically, as described above, the load fulcrum of the upper platen 2 of the double-sided polishing apparatus 1 is the fixing means 9 which is the joint between the upper platen 2 and the housing 8. Therefore, the PCD of the upper surface plate load fulcrum can be represented by the diameter of a circle (hereinafter, sometimes referred to as a pitch circle) when the center of the fixing means 9 which is the load fulcrum of the upper surface plate is connected by a circle. . Further, the PCD at the center of the holding hole of the carrier plate 6 means the center of the wafer holding hole formed in the carrier plate 6 (which is held by the carrier plate 6 in the case of the double-side polishing machine having one carrier plate 6 as described above). Wafer 4
Can be represented by the diameter of the pitch circle when they are connected by a circle.

The PCD of these upper surface plate load fulcrums
And the PCD at the center of the holding hole of the carrier plate are matched to improve the response (particularly linearity) of the platen deformation to the adjustment of the supply amount of the polishing slurry and the adjustment of the shape adjusting means when polishing the wafer. As a result, a double-sided polishing apparatus capable of controlling the shape of a wafer to be polished with high accuracy and performing stable polishing can be provided.

The PCD at the load fulcrum of the upper platen and the PCD at the center of the holding hole of the carrier plate can be matched by adjusting the upper platen and the carrier plate at the design stage of the double-side polishing machine. Also, regarding the existing double-sided polishing machine, by adjusting the position of the wafer holding hole at the stage of manufacturing the carrier plate, the PCD of the upper surface plate load fulcrum and the PCD of the center of the holding hole of the carrier plate are adjusted.
Can be matched, which is convenient.

At this time, it is important to match the PCD of the upper surface plate load fulcrum with the PCD of the center of the holding hole of the carrier plate, and it is preferable that these pitch circles are at the same position during polishing. However, as described above, when the carrier plate 6 of the double-sided polishing apparatus 1 makes a circular motion that eccentrically rotates from the rotation axis of the upper and lower surface plate, the diameter of the pitch circle formed at the upper surface plate load fulcrum and the carrier plate Although the diameter of the pitch circle formed at the center of the holding hole is the same, the position of the pitch circle at the center of the holding hole of the carrier plate 6 changes with time during polishing, so the pitch circle at the platen load fulcrum and the carrier are always maintained. It is not possible to match the pitch circles at the center of the plate holding holes. Therefore, in such a case, the pitch circle of the upper platen load fulcrum and the average position of the small circle trajectory of the center of the wafer holding hole of the carrier plate (wafer center of the wafer held on the carrier plate) are circled. It suffices to match the circles when they are tied, and matching the PCDs in the present invention includes matching the diameters and matching the positions of such pitch circles.

Further, in the above, the PC of the upper surface plate load fulcrum
Matching D and PCD of the center of the holding hole of the carrier plate (wafer center of the wafer held on the carrier plate) means that the tolerance is 5 mm including the diameter and the position of the pitch circle.
Match them within. Upper surface plate load fulcrum P
It is more preferable that the CD and the PCD at the center of the holding hole of the carrier plate are completely aligned with each other, but in reality, some tolerance naturally occurs, and when the eccentricity during polishing is taken into consideration, the tolerance is within 5 mm. As a result, it is possible to sufficiently improve the responsiveness of the surface plate deformation to changes in the polishing conditions. That is, matching the PCD in the present invention includes the case where there is such a slight tolerance.

Next, a method for simultaneously polishing both front and back surfaces of a wafer by using the double-side polishing apparatus 1 shown in FIG. 1 will be described.
First, the wafer 4 is inserted and held in the carrier plate 6 in which the wafer holding holes are formed, and then the carrier plate 6
The wafer 4 held by is sandwiched between the upper surface plate 2 and the lower surface plate 3 to which the polishing cloth 5 is attached by using an elevating device (not shown) that moves the upper and lower surface plates 2 and 3 forward and backward in the rotation axis direction. Then, while supplying the slurry from the slurry supply means 16, the upper surface plate 2 is rotated in the horizontal plane via the cylinder 7 from the upper rotation motor (not shown), and the cylinder 7 is moved from the lower rotation motor (not shown). The lower platen 3 is rotated in the horizontal plane via the above. At this time, since the wafer 4 is rotatably held in the wafer holding hole of the carrier plate 6, by adjusting the rotation speeds of the upper surface plate 2 and the lower surface plate 3, a wafer having a high rotation speed can be used. It can be rotated (rotated) in the direction of rotation. At the same time when the upper and lower surface plates 2 and 3 are rotated, the carrier plate 6 is moved by the carrier holder 11 to which the eccentric arm 12 is attached in a circular motion that does not involve rotation of the carrier plate. Thereby, both front and back surfaces of the wafer 4 can be simultaneously and uniformly polished.

At this time, the rotational speeds of the upper surface plate 2 and the lower surface plate 3 are not limited, and the rotational directions and the pressing forces of the upper surface plate 2 and the lower surface plate 3 on the wafer 4 are not limited. The upper surface plate and the lower surface plate are preferably pressed against both front and back surfaces of the silicon wafer by a pressure method using a fluid or the like, and are mainly pressed by a housing portion arranged on the upper surface plate. Usually, the pressing force of the upper and lower surface plates against the wafer is 100 to 300 g / cm ² . At this time, the polishing amount and polishing rate on both the front and back surfaces of the wafer are not limited.

As described above, when the front and back surfaces of the wafer are simultaneously polished, the temperature of the polishing surface can be controlled by adjusting the supply amount of the slurry supplied from the slurry supplying means 16, and thereby the temperature of the polishing surface can be controlled. The wafer can be polished while controlling the plate shape with excellent responsiveness.

The amount of slurry supplied from the slurry supply means is not limited because it varies depending on conditions such as the size of the carrier plate, but is usually 2.0 to 6.0 liters / minute. At this time, the temperature of the polishing surface during polishing can be controlled by adjusting the supply amount of the slurry, and the surface plate shape can be controlled with excellent responsiveness. Thereby, stable polishing can be performed without deteriorating the wafer shape. At that time, the type of slurry used is not limited, but for example, when polishing a silicon wafer, a pH containing colloidal silica is used.
An alkali solution of 9 to 11 can be adopted.

At this time, it is preferable to adjust the supply amount of the slurry according to the usage time of the polishing cloth, and thereby the shape of the platen can be accurately controlled according to the change with time of the polishing capacity of the polishing cloth. You can The slurry supply amount may be adjusted, for example, as the polishing cloth is used for a longer period of time, so that the slurry supply amount decreases with time so that the wafer shape does not deviate from the control target value range. The ratio is appropriately set depending on the polishing apparatus and polishing conditions. For example, by adjusting the supply amount of the slurry so that it decreases by about 0.2 liters / minute every time 5 batches of wafers are polished, the surface plate shape is adjusted so as to cancel the change of the wafer shape as the polishing progresses. Can be deformed, and polishing can be performed while easily controlling the wafer shape. Thereby, even when polishing a plurality of batches of wafers, it is possible to suppress changes in the wafer shape over time, and it is possible to control the wafer shape accurately and stably perform polishing without deteriorating the shape of the wafer. .

When the front and back surfaces of the wafer are simultaneously polished as described above, a shape adjusting means is provided at the load fulcrum portion of the upper surface plate, and the shape adjusting means is adjusted to perform polishing while controlling the surface shape of the surface plate. By doing so, the shape of the upper surface plate can be forcibly deformed by the shape adjusting means, so that the surface plate shape can be appropriately controlled according to the change of the wafer shape over time.

For example, as shown in FIG. 2A, the micrometers exemplified above as the shape adjusting means 15 are installed at two points on the outer peripheral side and the center side of the fixing means 9 which are the load supporting points of the upper surface plate 2. Then, among the two micrometers installed at each of these load fulcrums, the micrometer on the outer peripheral side of the fixing means 9 is loosened upward, and the micrometer on the center side is adjusted downward so that As shown in FIG. 2B, the shape of the upper surface plate 2 can be controlled so as to be convex downward. On the contrary, by pressing the micrometer on the outer peripheral side of the fixing means 9 downward and loosening the micrometer on the central side upward,
As shown in (c), the shape of the upper surface plate 2 can be controlled so as to be convex upward.

At this time, the adjustment amount of the micrometer is determined by clarifying the relationship between the polishing conditions such as the polishing temperature and the change of the wafer shape in advance.
By appropriately adjusting the micrometer based on the relationship between the polishing conditions and the wafer shape, the surface plate shape can be deformed so as to cancel the change in the wafer shape as the polishing progresses, and the wafer shape can be easily formed. Polishing can be performed under controlled conditions. As a result, even when a plurality of batches of wafers are polished, changes in the wafer shape over time can be suppressed, and the wafer shape can be controlled accurately without deteriorating the wafer shape and stable polishing can be performed.

Further, at this time, the PCD of the upper surface plate load fulcrum which is the diameter of the circle when the load fulcrum of the upper surface plate is connected by a circle,
It is preferable to polish the wafer by matching the PCD at the center of the wafer, which is the diameter of the circle when the centers of the wafers held on the carrier plate are connected by a circle. In this way, by matching the PCD of the upper platen load fulcrum and the PCD of the wafer center, the response of the platen plate shape control by adjusting the slurry supply amount and the platen plate shape control by adjusting the shape adjusting means. The property can be further improved and the surface plate shape can be controlled with high accuracy. Therefore,
It is possible to precisely control the surface plate shape so as to offset the change of the wafer shape with the progress of polishing over time, so polishing should be performed while easily controlling the wafer shape. You can Therefore, even when a plurality of batches of wafers are repeatedly polished, the wafer shape can be maintained with high accuracy and stable polishing can be performed.

Hereinafter, in order to evaluate the response of the surface plate deformation due to the change (adjustment) of the slurry supply amount and the response of the surface plate deformation due to the adjustment of the shape adjusting means, the slurry supply amount was changed or the shape was changed. The results of experiments on the responsiveness (especially linearity) of the wafer shape by adjusting the adjusting means and polishing are shown.

The double-sided polishing apparatus shown in FIG. 1 was used as the double-sided polishing apparatus for the wafer. In this double-sided polishing machine, for example, the PCD of the upper surface plate load fulcrum was 600 mm and the PCD of the center of the holding hole of the carrier plate was 600 mm. Also, when the carrier plate moves in a circular motion without rotation, the average position of the pitch circle formed at the center of the holding hole of the carrier plate and the position of the pitch circle formed at the upper surface plate load fulcrum are made to match. . Further, as the shape adjusting means 15, micrometers are installed at two points on the outer peripheral side and the center side of the fixing means 9 which is the load fulcrum of the upper surface plate 2, so that the surface plate shape can be forcibly deformed. .

Using this double-sided polishing apparatus, first, a carrier plate (carrier plate having five holding holes)
Each wafer holding hole is rotatably 300m in diameter
Five silicon wafers of m (1 batch) were inserted. Each wafer was pressed at 200 g / cm ² by the upper and lower surface plates to which the soft non-woven fabric (polishing pad) was attached.

Then, while pressing the upper and lower polishing pads against the front and back surfaces of the wafer, slurry is supplied from the upper surface plate side to rotate the upper and lower surface plates, and the timing chain is rotated by a circular motion motor. The carrier plate was circularly moved without rotation (circular motion of about 10 cm in diameter) to polish both front and back surfaces of the wafer. In addition,
The slurry used here was prepared by dispersing polishing abrasive grains made of colloidal silica having a particle size of 0.05 μm in an alkaline solution having a pH of 10.5.

(Responsiveness of Surface Plate Deformation Due to Change (Adjustment) of Slurry Supply Amount) In order to evaluate the response of surface plate deformation due to a change (adjustment) of slurry supply amount, the slurry supply amount is divided into 5 steps at equal intervals. Then, the responsiveness of the wafer shape to the change in the slurry supply amount was examined. actually,
The slurry supply amount of the experimental condition 1 is set to 3.0 liters / minute, and the supply amount is changed (increased) by 0.2 liters / minute from the experimental condition 2 to the experimental condition 5 to cope with the change of the slurry supply amount. The change in wafer shape (change in surface plate shape) was confirmed. At this time, the other conditions were set to the same conditions as much as possible, and the experiment was carried out using a polishing cloth having a similar usage time.

In this case, the responsiveness of the surface plate deformation may be evaluated by directly observing the change of the surface plate shape, but in reality, the shape of the polishing wafer is important. Therefore, in this experiment, the unevenness of the wafer after polishing was measured as a parameter representing the wafer shape, and by confirming the thickness of the central portion and the outer peripheral portion, the response of the wafer shape to the change in the slurry supply amount was evaluated. went. At the time of measurement, the shape of experimental condition 3 was used as a reference, and if it was convex, it was set to the positive side, and if it was concave, the side was set to the negative side, and the change was relatively evaluated.

(Responsiveness of Surface Plate Deformation by Adjusting Shape Adjusting Means) In order to evaluate the responsiveness of surface plate deformation by adjusting the shape adjusting means, a micrometer on the outer peripheral side installed near the housing of the upper surface plate. Polishing was performed by adjusting the micrometer on the center side and the micrometer on the center side up and down to change the surface plate shape under five conditions.

That is, with reference to the condition of experimental condition 3 (one in which the heights of the outer peripheral side micrometer and the central side micrometer are the same), the outer peripheral side micrometer is loosened upward to the experimental condition 2 The experimental condition 1 was that the micrometer on the center side was pressed downward. On the contrary, based on the experimental condition 3, the condition in which the micrometer on the center side was loosened upward was the experimental condition 4, and the condition in which the micrometer on the outer peripheral side was pressed downward was the experimental condition 5. That is, the experimental conditions 1 and 2 are set so that the shape of the upper surface plate has a downward convex shape as shown in FIG. 2B.
Then, control was performed so that the wafer had an upward convex shape as shown in FIG. 2C, and changes in the wafer shape due to the adjustment of the shape adjusting means were confirmed.

At this time, the other conditions were set to the same conditions as much as possible, and in particular, the experiments were carried out using polishing cloths having the same usage time. In addition, as a parameter representing the wafer shape, the unevenness of the wafer after polishing was measured and the responsiveness of the wafer shape to the adjustment of the shape adjusting means was evaluated in the same manner as above.

FIG. 5 shows the result of measuring the responsiveness of the wafer shape due to the change of the slurry supply amount, and FIG. 6 shows the result of measuring the responsiveness of the wafer shape by adjusting the shape adjusting means.
Shown in. These measurement results are obtained by plotting average values of 5 sheets (1 batch) for each experimental condition. When the slurry supply amount was changed, the linearity was good (correlation coefficient 0.998) as shown in FIG. 5, and the responsiveness of the wafer shape to the change in the slurry supply amount (that is, the response of the platen deformation). You can see that the sex) is good. Similarly, when the shape adjusting means is adjusted, the linearity is good (correlation coefficient 0.995) as shown in FIG. 6, and the responsiveness of the wafer shape to changes in the shape adjusting means (that is, surface plate deformation). Responsiveness)
It turns out that is good.

From the above experimental results, it can be seen that the responsiveness of the surface plate deformation due to the adjustment of the slurry supply amount and the shape adjusting means is very good. As a result, for example, the responsiveness (linearity) of the wafer shape shown in FIG. 5 or FIG. 6 is offset so as to cancel the change in the wafer shape caused by repeated polishing using the same polishing cloth. By adjusting the slurry supply amount or the shape adjusting means in consideration, it is possible to perform highly accurate and stable polishing without deteriorating the wafer shape.

Further, as described above, the amount of slurry supplied and the shape adjusting means can be adjusted separately to accurately control the shape of the platen. By adjusting the amount and the shape adjusting means in combination, and also adjusting the surface plate temperature by the temperature adjusting means in the surface plate, the surface plate shape can be controlled more accurately and easily. . As a result, the wafer shape can be controlled with higher accuracy and stable polishing can be performed. Further, even if a plurality of batches of wafers are repeatedly polished, the shape of each batch of wafers can be maintained with extremely high accuracy, and stable polishing can be performed.

Further, the control of the surface plate shape by adjusting the supply amount of these slurries and the shape adjusting means may be adjusted for each polishing batch or during polishing.
Usually, the wafer shape can be sufficiently controlled by adjusting each polishing batch. For example, after polishing a few batches of wafers, the wafer shape is examined, and the surface plate shape is controlled by adjusting the slurry supply amount and / or adjusting the shape adjusting means according to the change over time of the wafer shape, You may make it polish the next batch.

Next, a double-side polishing apparatus which is another embodiment of the present invention will be described. FIG. 3 shows a schematic cross-sectional explanatory view of a 4-way double-sided polishing apparatus according to the present invention. This 4-way double-sided polishing device 21 includes a plurality of carrier plates 26 having wafer holding holes, a sun gear 31 for rotating and revolving the carrier plates, an internal gear 32, and an upper surface plate 22 to which a polishing cloth 25 is attached. And lower surface plate 2
3 and the slurry supply means 34, the wafer 24 is inserted and held in the wafer holding holes of the plurality of carrier plates 26, and the carrier plate 26 is fixed to the upper platen 22 and the lower plate to which the polishing cloth 25 is attached. The carrier plate 26 is sandwiched by the board 23 from above and below, and while the slurry is supplied from the slurry supply means 34, the carrier plate 26 is rotated and revolved by the sun gear 31 and the internal gear 32.
By rotating the upper surface plate 22 and the lower surface plate 23 around a rotation axis perpendicular to the wafer, both front and back surfaces of the wafer 24 can be simultaneously polished.

At this time, the upper surface plate 22 is provided with a cylinder 27 for applying a rotation and polishing load, a housing 28 for transmitting the load to the upper surface plate, and a bolt for fixing the housing 28 and the upper surface plate 22. Means 29 are installed, and the upper surface plate 22 is further provided with temperature adjusting means (not shown) for controlling the temperature of the surface plate.

The load fulcrum of the upper surface plate 22 is the upper surface plate 22.
And a fixing means 29 which is a joint portion of the housing 28. The double-sided polishing apparatus 21 of the present invention has shape adjusting means at the load fulcrum portion near the fixing means 29 which is the load fulcrum of the upper surface plate 22, for example, two points on the outer peripheral side and the central side of the fixing means 29 as shown in FIG. 33 is installed, and the installed shape adjusting means 33
By adjusting, the upper surface plate 22 can be mechanically pressed and its shape can be forcibly deformed. As described above, the double-sided polishing apparatus of the present invention adjusts the shape adjusting means 33 according to the change with time of the polishing ability of the polishing cloth 25 and the like to polish the wafer to force the shape of the upper platen 22. Since the wafer can be controlled with high accuracy, the double-sided polishing apparatus can polish the wafer with high accuracy and stability.

At this time, the shape adjusting means 33 is not particularly limited, but is preferably a micrometer, for example. If the shape adjusting means is a micrometer as described above, by accurately adjusting the micrometer, the upper surface plate can be mechanically pressed to a desired size and forcibly deformed. It can be accurately deformed into a desired shape.

On the other hand, the lower platen 23 is provided with a cylinder 2 for giving rotation from a motor and a speed reducer (not shown) to the lower platen.
7. A thrust bearing 30 for supporting the load of the surface plate is installed, and the lower surface plate 23 is provided with temperature adjusting means (not shown) for controlling the temperature of the surface plate.

The material of the upper surface plate 22 and the lower surface plate 23 is preferably stainless steel (SUS),
Thereby, the surface plate can be easily deformed by the shape adjusting means or the like. The polishing cloth 25 attached to the lower surface of the upper surface plate 22 and the upper surface of the lower surface plate 23 is not particularly limited, but similar to the above, a hard foam urethane pad or a non-woven fabric which is a general polishing cloth is used. A soft non-woven fabric pad impregnated and cured with a urethane resin can be used.

Further, the slurry supply means 34 is constituted by providing a slurry supply hole on the upper surface plate through a rotary joint (not shown). For example, the supply amount of the slurry is changed by an electromagnetic valve or the like not shown. be able to.
Further, it is preferable that a plurality of slurry supplying means can be formed and the slurry is arranged so that the slurry is constantly supplied to the surface of the wafer.

In such a double-side polishing apparatus 21, the PCD of the upper platen load fulcrum, which is the diameter of the circle when the load fulcrums of the upper platen 22 are connected by a circle, and a plurality of carrier plates 26.
It is preferable to match the PCD at the center of the carrier plate, which is the diameter of the circle when the centers are connected by a circle.

More specifically, as described above, the load fulcrum of the upper platen 22 of the double-sided polishing device 21 is the fixing means 29 which is the joint between the upper platen 22 and the housing 28.
Therefore, the PCD of the upper surface plate load fulcrum can be represented by the diameter of the circle when the center of the fixing means 29, which is the load fulcrum of the upper surface plate, is connected by a circle. Further, a plurality of wafer holding holes are formed in the carrier plate 26 of such a double-side polishing machine 21, and a wafer holding hole having an average diameter of a circle when the centers of the holding holes of the carrier plate are connected by a circle. It is difficult to match the center PCD with the PCD of the upper platen load fulcrum. Therefore, in the case of such a double-sided polishing device 21, the PCD at the center of the carrier plate, which is the diameter of the circle when the centers of the plurality of carrier plates 26 are connected by a circle, is made to coincide with the PCD of the upper surface plate load fulcrum. To do. This makes it possible to improve the responsiveness (especially linearity) of the surface plate deformation to the adjustment of the supply amount of the polishing slurry and the adjustment of the shape adjusting means when polishing the wafer. It is possible to provide a double-sided polishing apparatus that can control with high accuracy and perform polishing stably.

At this time, it is desirable that the PCD at the load fulcrum of the upper surface plate and the PCD at the center of the carrier plate are completely in agreement, but the tolerance is 5 mm as described above.
It suffices if they match within the range, thereby improving the responsiveness of the surface plate deformation to the adjustment of polishing conditions.
The present invention also includes cases where there are some such tolerances.

Next, a method for simultaneously polishing both front and back surfaces of a wafer by using the 4-way double-sided polishing apparatus shown in FIG. 3 will be described. First, the wafer 24 is inserted into and held by a plurality of carrier plates 26 having wafer holding holes formed therein, and then the wafer 24 held by the carrier plates 26.
Is sandwiched between the upper surface plate 22 and the lower surface plate 23 to which the polishing cloth 25 is attached by using an elevating device (not shown) that moves the upper and lower surface plates 22 and 23 back and forth in the rotation axis direction. After that, while supplying the slurry from the slurry supply means 34, the upper surface plate 22 is rotated in the horizontal plane via the cylinder 27 from the upper rotation motor (not shown), and the cylinder 27 is moved from the lower rotation motor (not shown). The lower stool 23 is rotated in the horizontal plane through. At the same time, by rotating and revolving the plurality of carrier plates 26 by the sun gear 31 and the internal gear 32, both front and back surfaces of the wafer can be uniformly polished.

At this time, the rotational speeds of the upper and lower surface plates, the respective rotation directions, the pressing force of the upper and lower surface plates against the wafer, etc. are not limited, and the conventional conditions are used. It can be polished.

When the front and back surfaces of the wafer are simultaneously polished, the temperature of the polishing surface can be controlled by adjusting the supply amount of the slurry supplied from the slurry supply means 34, whereby the surface plate shape can be controlled. It is possible to polish the wafer while controlling the temperature with excellent responsiveness, and to perform stable polishing without deteriorating the shape of the wafer. At that time, the type of slurry used is not limited as described above.

At this time, it is preferable to adjust the supply amount of the slurry according to the usage time of the polishing cloth, and thereby the shape of the platen can be accurately controlled in accordance with the change with time of the polishing capacity of the polishing cloth. You can For example, the supply amount of the slurry may be adjusted so that the supply amount of the slurry decreases with time as the polishing cloth is used for a long time, and the ratio is appropriately set depending on the polishing apparatus and polishing conditions. In this way, by adjusting the supply amount of the slurry according to the use time of the polishing cloth, the surface plate shape can be deformed so as to offset the change in the wafer shape due to the progress of polishing, and the wafer shape can be changed. Polishing can be performed with easy control. Further, even when polishing a plurality of batches of wafers, it is possible to suppress the change of the wafer shape over time, and it is possible to perform stable polishing by accurately controlling the wafer shape without deteriorating the shape of the wafer. .

On the other hand, when simultaneously polishing both front and back surfaces of the wafer as described above, the shape adjusting means 33 is provided at the load fulcrum portion of the upper surface plate 22, and the shape adjusting means 33 is adjusted to control the shape of the surface plate. While polishing the wafer. As a result, the shape of the upper surface plate can be forcibly deformed by the shape adjusting means as shown in FIGS. 2B and 2C, and the polishing conditions such as the polishing temperature and the wafer shape can be preliminarily changed. By clarifying the relationship with the change and adjusting the micrometer appropriately based on that relationship, the surface plate shape can be deformed so as to cancel the change in the wafer shape as the polishing progresses. Polishing can be performed while controlling the shape easily. Further, even when polishing a plurality of batches of wafers, changes in the shape of the wafer over time can be suppressed, and stable polishing can be performed with high precision control without deteriorating the shape of the wafer.

Further, at this time, the PCD of the upper surface plate load fulcrum which is the diameter of the circle when the load fulcrums of the upper surface plate 22 are connected by a circle.
It is preferable to polish the wafer by matching the PCD of the center of the carrier plate, which is the diameter of the circle when the centers of the plurality of carrier plates are connected by a circle, with each other. In this way, the PCD of the upper platen load fulcrum and the PCD of the carrier plate center
By matching with, it is possible to improve the responsiveness of the control of the surface plate shape by adjusting the slurry supply amount and the control of the surface plate shape by adjusting the shape adjusting means, and control the surface plate shape with high accuracy. can do. Therefore, it becomes possible to precisely control the surface plate shape so as to offset the change over time in the wafer shape as the polishing progresses. It can be performed. Thereby,
Even when a plurality of batches of wafers are repeatedly polished, the wafer shape can be maintained with high accuracy and stable polishing can be performed.

At this time, change (adjustment) of the slurry supply amount
The responsiveness of the surface plate deformation due to and the responsiveness of the surface plate deformation due to the adjustment of the shape adjusting means are very good as in the above-mentioned double-sided polishing apparatus 1. Therefore, for example, in order to cancel the change in the wafer shape caused by the continuous polishing using the same polishing cloth, the responsiveness (linearity) of the wafer shape is taken into consideration and the slurry supply amount or shape By adjusting the adjusting means, it is possible to perform highly accurate and stable polishing without deteriorating the wafer shape.

Further, by adjusting the supply amount of the slurry and the shape adjusting means in combination, and also adjusting the platen temperature by the temperature adjusting means in the platen, it is possible to easily and accurately determine the temperature. The board shape can be controlled.
As a result, even if a plurality of batches of wafers are repeatedly polished, the shape of each batch of wafers can be maintained with extremely high precision, and stable polishing can be performed.

Incidentally, the control of the surface plate shape by adjusting the supply amount of these slurries and the shape adjusting means may be adjusted for each polishing batch or during polishing, as described above. good.

[0099]

EXAMPLES The present invention will be described more specifically below by showing Examples and Comparative Examples, but the present invention is not limited to these. (Example 1) As a double-sided polishing apparatus for a wafer, as shown in FIG. 1, the PCD of the upper platen load fulcrum is 600 mm, and the PCD of the center of the holding hole of the carrier plate (the center of the wafer held by the carrier plate) is 600 mm. Yes, during polishing, the average position of the pitch circle made at the center of the holding hole of the carrier plate and the position of the pitch circle made at the upper platen load fulcrum are matched.The carrier plate moves in a circular motion without rotation. A silicon wafer for 20 batches was repeatedly polished while controlling the shape of the platen by adjusting the slurry supply amount using a double-sided polishing machine.

First, five (one batch) silicon wafers having a diameter of 300 mm were rotatably inserted into the respective wafer holding holes of the carrier plate (carrier plate having five holding holes). Each wafer has a top and bottom surface plate on which soft non-woven fabric (polishing pad) is attached, 200 g /
It was pressed with a pressing force of cm ² to rotate the upper platen and the lower platen around the rotation axis, and the carrier plate was caused to perform circular motion without rotation to perform polishing.
The slurry used was an alkaline solution having a pH of 10.5 and abrasive grains made of colloidal silica having a particle size of 0.05 μm dispersed therein, and the slurry was supplied at an initial slurry supply rate of 4.0 liters / minute.

During polishing of 20 batches of wafers, the polishing cloth was not replaced, and the slurry supply rate was decreased by 0.2 liter / minute for every 5 batches of polishing, while the change in the wafer shape was corrected to be repeated. Polished.

After polishing, the shape of the obtained wafer was evaluated by GBIR. GBIR (Global B
ack Ideal Range) has one reference plane in the wafer plane and is defined as the width of maximum and minimum position displacement with respect to this reference plane, which is the conventional specification of TTV (total thickness deviation). It is equivalent. In this measurement, an electrostatic capacity type flatness measuring device (AFS3220) manufactured by ADE was used for evaluation. At that time, the GBIR of the first batch was used as a reference, and the relative change was plotted. The result is shown in FIG. 7.

(Comparative Example 1) For comparison, using the same double-sided polishing apparatus for wafers as in Example 1, 20 batches of silicon wafers were continuously treated by keeping the slurry supply amount constant without adjusting. And polished. Other polishing conditions were the same as in Example 1 (especially, polishing cloths having the same usage time were used). The shape of the wafer obtained after polishing was evaluated by GBIR, and the relative change was plotted on the basis of GBIR of the first batch.
The result is shown in FIG.

As shown in FIG. 7, in Example 1, the wafer shape can be controlled within a certain range by adjusting the supply amount of the slurry, and even if a plurality of batches of wafers are polished, the wafer shape can be controlled. Could be maintained within the range of the management target value (management upper limit value). However,
In Comparative Example 1, as the number of polishing batches increased (as the frequency of use of the polishing cloth increased), the wafer shape deteriorated,
When the number of polishing batches exceeded 10, it fell outside the range of the control target value (control upper limit value).

(Example 2 and Comparative Example 2) Next, the same double-sided polishing apparatus as in Example 1 was used as a double-sided polishing apparatus for wafers, and the temperature was controlled at 25 ° C. in the piping in the surface plate, which is a temperature control means. Water was supplied to polish a batch of silicon wafers having a diameter of 300 mm, and then hot water was flown through the temperature control means in the surface plate to change the temperature to 40 ° C. to polish the next batch of silicon wafers. At that time, a wafer obtained by adjusting the shape adjusting means by a micrometer according to the temperature change of the surface plate and forcibly deforming the shape of the upper surface plate into the state of FIG. The wafer shapes of Example 2) and the wafer obtained by polishing without using the shape adjusting means (Comparative Example 2) were compared.

As a result, when the temperature of the platen was changed, the shape of the wafer of Example 2 which was polished by adjusting the shape adjusting means was the same as that of the first batch wafer polished at the temperature of the platen of 25 ° C. It was almost the same shape as. By adjusting the shape adjusting means provided on the upper surface plate in this way, the wafer shape could be controlled and polished even when the polishing conditions such as the surface plate temperature changed significantly. On the other hand, the shape of the wafer of Comparative Example 2 which was polished without using the shape adjusting means was an extremely convex convex shape.

(Example 3 and Comparative Example 3) As a double-sided polishing apparatus for wafers, as shown in FIG. 3, a 4-way double-sided system having a PCD of 800 mm for the upper platen load fulcrum and a PCD of 800 mm for the center of the carrier plate is used. Using a polishing apparatus, 20 batches were prepared for Example 3 in which the slurry supply amount was adjusted to control the surface plate shape while polishing, and Comparative Example 3 in which the slurry supply amount was kept constant for polishing. The wafer was repeatedly polished.

First, a total of 15 (one batch) silicon wafers having a diameter of 300 mm were inserted into the three wafer holding holes formed in each of the five carrier plates.
Each wafer was polished by being pressed with a pressing force of 200 g / cm ² by the upper and lower surface plates to which a soft non-woven fabric (polishing pad) was attached. The slurry was prepared by dispersing polishing abrasive particles made of colloidal silica having a particle size of 0.05 μm in an alkaline solution having a pH of 10.5, and the initial slurry supply rate was 5.0 liters / minute. In addition, during polishing of 20 batches of wafers, the polishing cloth was not replaced, and in Example 3, 0.2 liter /
The polishing was repeatedly performed while the change in the wafer shape was corrected by gradually decreasing the slurry supply amount, and in Comparative Example 3, the polishing amount was maintained constant without adjusting the slurry supply amount. The other polishing conditions were the same in both Example 3 and Comparative Example 3.

Regarding the shape of the wafer obtained after polishing,
GBIR was evaluated in both Example 3 and Comparative Example 3, and the relative change was plotted based on GBIR of the first batch. The result is shown in FIG.

As shown in FIG. 8, in Example 3, the wafer shape can be controlled within a certain range by adjusting the supply amount of the slurry, and even if a plurality of batches of wafers are polished, the wafer shape can be controlled. Could be maintained within the range of the management target value (management upper limit value). However,
In Comparative Example 3, as the number of polishing batches increased (as the frequency of use of the polishing cloth increased), the wafer shape deteriorated,
When the number of polishing batches exceeded 10, it fell outside the range of the control target value (control upper limit value).

Example 4 and Comparative Example 4 Next, the same double-sided polishing apparatus as in Example 3 and Comparative Example 3 was used as a double-sided polishing apparatus for wafers, and the temperature of the temperature control means in the surface plate was set to 25 ° C.
The silicon wafer having a diameter of 300 mm was polished for one batch by controlling the temperature to 1, and the temperature of the temperature control means in the platen was changed to 40 ° C. to polish the next batch of silicon wafers. At that time, the shape adjusting means by the micrometer is adjusted according to the temperature change in the surface plate to forcefully shape the shape of the upper surface plate.
Regarding the wafer obtained by deforming to the state of (b) and polishing (Example 4) and the wafer obtained by polishing without using the shape adjusting means (Comparative Example 4), those wafer shapes Were compared.

As a result, when the temperature of the platen was changed, the shape of the wafer of Example 4 which was polished by adjusting the shape adjusting means was the same as that of the first batch of wafers polished at the temperature of the platen of 25 ° C. It was almost the same shape as. By adjusting the shape adjusting means provided on the upper surface plate in this way, the wafer shape could be controlled and polished even when the polishing conditions such as the surface plate temperature changed significantly. On the other hand, the shape of the wafer of Comparative Example 4, which was polished without using the shape adjusting means, was an extremely convex shape of the wafer.

The present invention is not limited to the above embodiment. The above-described embodiment is merely an example, and it has substantially the same configuration as the technical idea described in the scope of claims of the present invention, and has the same operational effect.
Anything is included in the technical scope of the present invention.

For example, in the above-described embodiment, as an example of the double-sided polishing apparatus of the present invention, the movement of the carrier plate makes a circular movement without rotation of the carrier plate, but the present invention is not limited to this. It is not limited to this, and may be a double-side polishing apparatus that performs any movement of the carrier plate that can uniformly polish the wafer.

[0115]

As described above, according to the present invention,
By adjusting the amount of slurry supplied when polishing a wafer, and by providing shape adjustment means at the load fulcrum part of the upper surface plate and adjusting the shape adjustment means, the surface plate shape is excellent. It can be controlled with responsiveness. As a result, it is possible to stabilize and stabilize the wafer shape, and even when polishing multiple batches of wafers repeatedly, the wafer shape for each batch can be controlled with high accuracy without deteriorating the shape of the wafer. Therefore, stable polishing can be performed.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional explanatory view showing an example of a double-sided polishing apparatus according to the present invention.

FIG. 2 is a schematic explanatory view showing a deformation of an upper surface plate by adjustment of a shape adjusting means.

FIG. 3 is a schematic cross-sectional explanatory view showing an example of a double-sided polishing apparatus (of a 4-way method) according to another embodiment of the present invention.

FIG. 4 is a schematic cross-sectional explanatory view showing an example of a conventional double-sided polishing apparatus.

FIG. 5 is a graph showing the responsiveness of the wafer shape to changes in the slurry supply amount.

FIG. 6 is a graph showing the responsiveness of the wafer shape by adjusting the shape adjusting means.

FIG. 7 is a graph for evaluating the controllability of the wafer shape when repeatedly polishing a plurality of batches of wafers in Example 1 and Comparative Example 1.

FIG. 8 is a graph showing the controllability of the wafer shape when a plurality of batches of wafers are repeatedly polished in Example 3 and Comparative Example 3.

[Explanation of symbols]

1 ... Double-side polishing machine, 2 ... Upper surface plate, 3 ... Lower surface plate, 4 ...
Wafer, 5 ... Polishing cloth, 6 ... Carrier plate, 7
... Cylinder, 8 ... Housing, 9 ... Fixing means, 1
0 ... Thrust bearing, 11 ... Carrier holder, 11
(A) ... Bearing part, 11 (b) ... Annular part, 12 ... Eccentric arm, 12 (a) ... Eccentric shaft, 12 (b) ... Rotating shaft,
13 ... Sprocket, 14 ... Timing chain, 1
5 ... Shape adjusting means, 16 ... Slurry supplying means, 21 ...
4-way double-side polishing machine, 22 ... Upper surface plate, 23
... Lower surface plate, 24 ... Wafer, 25 ... Abrasive cloth, 26 ...
Carrier plate, 27 ... Cylinder, 28 ... Housing, 29 ... Fixing means, 30 ... Thrust bearing, 3
DESCRIPTION OF SYMBOLS 1 ... Sun gear, 32 ... Internal gear, 33 ... Shape adjusting means, 34 ... Slurry supplying means.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshiyuki Hayashi             Gunma Prefecture Gunma-gun Gunma-cho 762 Ashimon             Conductor Industry Co., Ltd. F-term (reference) 3C058 AA07 AB04 BA02 BA07 BA11                       BB03 BC01 CB01 DA17

Claims (16)

[Claims] 1. A carrier plate having at least a wafer holding hole, an upper platen and a lower platen to which a polishing cloth is attached, and a slurry supply means, and the wafer is held in the wafer holding hole to hold a slurry. While supplying, in a double-sided polishing apparatus that simultaneously moves the carrier plate between the upper and lower surface plates to polish the front and back surfaces of the wafer at the same time, the load supporting point portion of the upper surface plate has a shape adjusting means. Double side polishing machine. 2. The double-side polishing apparatus for a wafer according to claim 1, wherein the movement of the carrier plate is a circular movement that does not accompany the rotation of the carrier plate. 3. The PCD of the upper platen load fulcrum, which is the diameter of the circle when the load fulcrums of the upper platen are connected by a circle, and the circle when the center of each holding hole of the carrier plate is connected by a circle. The double-sided polishing apparatus for a wafer according to claim 1 or 2, wherein the diameter of the carrier plate is matched with the PCD at the center of the holding hole of the carrier plate. 4. At least a plurality of carrier plates having wafer holding holes, a sun gear and an internal gear for rotating and revolving the carrier plates, an upper surface plate and a lower surface plate having a polishing cloth attached thereto, and a slurry supply means. Holding a wafer in the wafer holding hole, while rotating and revolving a plurality of carrier plates between the upper and lower surface plate while supplying the slurry, a double-side polishing apparatus for simultaneously polishing both front and back surfaces of the wafer 2. The double-sided polishing apparatus for a wafer according to, wherein the load fulcrum portion of the upper platen has shape adjusting means. 5. The PCD of the upper platen load fulcrum, which is the diameter of the circle when the load fulcrums of the upper platen are connected by a circle, and the diameter of the circle when the centers of the plurality of carrier plates are connected by a circle. 5. The double-sided polishing apparatus for a wafer according to claim 4, wherein the PCD at the center of the carrier plate is matched. 6. The double-sided polishing apparatus for a wafer according to claim 1, wherein the shape adjusting means is a micrometer. 7. The double-sided polishing apparatus for a wafer according to claim 1, wherein the surface plate is made of stainless steel. 8. A wafer is held in a wafer holding hole formed in a carrier plate, and while supplying a slurry,
In a double-sided polishing method in which the front and back surfaces of the wafer are simultaneously polished by moving the carrier plate between an upper surface plate and a lower surface plate to which a polishing cloth is attached, the surface plate shape is controlled by adjusting the supply amount of the slurry. A double-sided polishing method for a wafer, which is characterized by polishing while simultaneously performing. 9. The double-sided polishing method for a wafer according to claim 8, wherein the movement of the carrier plate is a circular movement without rotation of the carrier plate. 10. A plurality of carrier plates holding wafers on a plurality of carrier plates having holding holes for holding wafers and supplying slurry to the plurality of carriers between an upper surface plate and a lower surface plate to which a polishing cloth is attached. In a double-sided polishing method in which the plate is rotated and revolved with a sun gear and an internal gear, and the front and back surfaces of the wafer are simultaneously polished,
A double-sided polishing method for a wafer, which comprises polishing while controlling a shape of a surface plate by adjusting a supply amount of the slurry. 11. The double-sided polishing method for a wafer according to claim 8, wherein the supply amount of the slurry is adjusted according to the usage time of the polishing cloth. 12. The wafer is held by holding a wafer in a wafer holding hole formed in a carrier plate and moving the carrier plate between an upper surface plate and a lower surface plate to which a polishing cloth is attached while supplying the slurry. In the double-sided polishing method for simultaneously polishing both the front and back sides, the wafer is characterized in that shape adjusting means is provided at the load fulcrum portion of the upper surface plate and the surface shape is controlled by adjusting the shape adjusting means to perform polishing. Double-sided polishing method. 13. The method for polishing both sides of a wafer according to claim 12, wherein the movement of the carrier plate is a circular movement without rotation of the carrier plate. 14. A plurality of carrier plates holding wafers on a plurality of carrier plates having holding holes for holding wafers and supplying slurry to the plurality of carriers between an upper surface plate and a lower surface plate to which a polishing cloth is attached. In a double-sided polishing method in which the plate is rotated and revolved with a sun gear and an internal gear, and the front and back surfaces of the wafer are simultaneously polished,
A double-sided polishing method for a wafer, characterized in that shape adjusting means is provided at a load fulcrum portion of the upper surface plate, and the shape adjusting means is adjusted to control the shape of the surface plate for polishing. 15. The double-sided polishing method for a wafer according to claim 12, wherein the polishing is performed while controlling the shape of the platen by adjusting the supply amount of the slurry to be supplied. . 16. The PCD of the upper platen load fulcrum, which is the diameter of the circle when the load fulcrums of the upper platen are connected by a circle, and the center of the wafer held by the carrier plate, are connected by a circle. 9. A wafer center PCD having a diameter of a circle or a carrier plate center PCD having a diameter of a circle when the centers of the plurality of carrier plates are connected by a circle are matched and polished. The double-sided polishing method for a wafer according to claim 15.