JP2891068B2 - Wafer polishing method and polishing apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing method and a polishing apparatus for a wafer, and more particularly to a polishing method and a polishing apparatus suitable for application to a planarization processing technique for improving the flatness of a semiconductor device. .

[0002]

2. Description of the Related Art As semiconductor devices become more highly integrated and larger in scale, the area occupied by wiring in a chip increases.
Pattern miniaturization and multilayer wiring are becoming increasingly important. Therefore, the flatness of a wafer made of a semiconductor single crystal as a raw material is required to have higher accuracy, and at the same time, in order to apply lithography or etching to finer high-density wiring, it is necessary to use an underlying base. The insulating film must be sufficiently planarized in advance. Conventionally, wafer polishing has been developed in order to equalize the thickness of the entire surface of the wafer, and to preferentially remove a thick portion of the wafer. However, recently, in the process of manufacturing a semiconductor device, the above-mentioned polishing is used as one of means for planarizing a projection portion of a silicon oxide film generated corresponding to wiring on a wafer or the like, in order to improve flatness of the semiconductor device. The adoption of the method has begun to be considered. However, here, it is desired that an oxide film formed with a uniform thickness on a wafer surface having a thickness variation can be processed while maintaining the uniformity of the film thickness.

[0003] In other words, the amount of polishing from the surface of a thick portion and a thin portion of a wafer (hereinafter, referred to as a wafer W) in the process of manufacturing a semiconductor device having a sectional shape shown in FIG. The need for a polishing technique for polishing a wafer W having a sectional shape shown in FIG. 6, that is, a so-called surface-based polishing technique, has been increasing. This polishing technique is, specifically, an oxide film 63 (interlayer insulating film) on a wafer 61 shown in FIG.
And the oxide film projections 64 are removed, and the thickness of the oxide film 63 is kept uniform.
Various polishing apparatuses have been proposed, such as the apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2000-125, "wafer mirror polishing apparatus" (FIG. 18) and the apparatus shown in FIG. In FIG. 4, reference numeral 62 denotes a wiring.

[0004] The apparatus described in the above-mentioned publication "Wafer Mirror Polishing Apparatus" uses a flexible elastic film 71 on a plane holding a wafer W, as shown in FIG.
1 is attached to the ring-shaped body 72 with uniform tension, and a fluid supply for supplying a fluid for adjusting the pressing pressure of the wafer W to the surface of the elastic film 71 opposite to the surface holding the wafer W is provided. The configuration is such that a means 73 is provided. Note that 7
Reference numeral 4 denotes a rotating shaft, 75 denotes an annular guide plate (template) adhered to the lower surface of the elastic film 71, and 76 denotes a polishing platen. In this polishing apparatus, a uniform polishing pressure distribution is formed since the elastic film 71 sealing the ring-shaped body 72 is rich in flexibility, so that the peripheral sag A as shown in FIG. The generation of the polishing wafer W accompanying
It is described that a polishing wafer W having a cross-sectional shape shown in (b) can be obtained.

On the other hand, in the polishing apparatus shown in FIG. 20, a soft mounting pad 82 and an annular template 83 are provided in this order on a lower surface of a wafer holding plate 81 made of a hard material, and a soft polishing cloth 85 is provided on an upper surface of a polishing platen 84. It is provided.

[0006]

Incidentally, the removal amount of the surface layer in the wafer polishing strongly depends on the polishing pressure. Therefore, in the surface-based polishing technique, FIG.
As shown in (a), the distribution D of the polishing pressure on the surface of the wafer W is made uniform (uniformly distributed load), and the region where the polishing pressure is applied is set to the rear surface of the wafer W (the surface opposite to the polishing surface).
Is very important. Note that FIG.
9A, reference numeral 91 denotes a wafer holding plate, and 92 denotes a polishing cloth.

However, in the polishing apparatus described in the above publication,
Since the elastic film 71 has a uniform thickness and is glued to the body 72 with a uniform tension, the gap H between the lower surface of the outer peripheral end of the elastic film 71 and the upper surface of the polishing platen 76 is formed as shown in FIG. Is smaller than the predetermined range, the polishing pressure becomes excessive at the outer peripheral portion of the wafer as shown in FIG.
As shown in FIG. 23B, the peripheral sag A is likely to occur on the wafer W being polished, and when the interval H is larger than a predetermined range, the polishing pressure is too small at the outer peripheral portion of the wafer as shown in FIG. As a result, as shown in FIG. 23 (b), there is a problem that the projection B is likely to be generated around the wafer W being polished. As a countermeasure, it is not always easy to adjust the interval H accurately.

On the other hand, the polishing apparatus shown in FIG. 20 has an advantage that the structure for holding the wafer is simplified, but is susceptible to variations in the characteristics (thickness, elasticity, and deterioration characteristics) of the mounting pad 82, and the polishing pressure is high. There was a disadvantage that it was difficult to make the uniformity. For this reason, FIG.
There is a problem that a peripheral sag A as shown in FIG. 23B and a peripheral protrusion B as shown in FIG.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a polishing method and a polishing apparatus capable of easily performing a surface-based polishing without causing peripheral sagging and peripheral projection of a wafer. Is to provide.

[0010]

According to a first aspect of the present invention, there is provided a method for polishing a wafer, wherein the wafer is held with its back surface in contact with a wafer holding plate, and a pressurized fluid is supplied to the back side of the wafer holding plate. The method of polishing a wafer by pressing the wafer against a polishing platen is characterized in that the pressure region on the back surface of the wafer holding plate during wafer polishing matches the region where the wafer holding plate faces the back surface of the wafer .

[0011] The method for polishing a wafer according to claim 2 is characterized in that:
2. The wafer holding plate according to claim 1, wherein the wafer holding plate is a wafer holding plate.
The holding area is made of a rigid plate made of a hard thin plate.
(C) a state in which the outer peripheral end is matched with the outer peripheral end of the flexible plate body
By holding the wafer on the wafer holding plate with
The pressurized area on the back of the wafer holding plate during wafer polishing
-Match the area where the wafer holding plate faces the back of the wafer
It is characterized by the following.

According to a third aspect of the present invention, in the wafer polishing apparatus, the wafer is polished and fixed by supplying a pressurized fluid to the rear side of the wafer holding plate while holding the wafer with its rear surface in contact with the wafer holding plate. In an apparatus for polishing by pressing against a plate, the wafer holding region is made of a thin plate of a hard material, and a wafer holding plate provided with flexibility is fixed to an opening of a housing via an elastic annular member. The opening is sealed, and the inside of the housing is connected to a supply source of a pressurized fluid.

According to a fourth aspect of the present invention, in the wafer polishing apparatus according to the third aspect, a central portion of the wafer holding plate is the wafer holding region, and an inner peripheral end of the annular member is provided at an outer peripheral end of the holding region. The positions of these end portions are matched and fixed, the flexibility of the outer peripheral side portion of the wafer holding plate in the wafer holding region is made higher than the wafer holding region as a movable region, and the outer peripheral end of the wafer holding plate is further fixed. It is characterized by being fixed to the housing.

[0014]

In the wafer polishing method according to the first and second aspects and the wafer polishing apparatus according to the third aspect, the wafer is held on a wafer holding plate, and compressed air having an appropriate pressure is supplied from a pressurized fluid supply source. When the wafer is supplied, the wafer is pressed against the polishing platen at a predetermined pressure due to the displacement of the wafer holding plate due to pressurization, so that the polishing can be performed in a usual manner. That is, in the polishing method according to claims 1 and 2,
The pressurized area on the back of the wafer holding plate during wafer polishing
The holding plate matches the area facing the back of the wafer.
And uniform polishing pressure distribution across the back of the wafer
The area under the polishing pressure is widened outside the back of the wafer
Without polishing, the wafer can be polished. In particular, in the polishing apparatus according to the third aspect, since the annular member is made to be elastic, the wafer holding plate can be freely displaced integrally with the annular member in accordance with the fluid pressure. That is, in the wafer holding plate, the wafer holding region is formed of a thin plate made of hard rubber or the like to be a flexible holding plate, so that the region where the polishing pressure is applied under a uniform polishing pressure distribution over the entire back surface of the wafer is applied. Without spreading outside the back of the wafer,
Moreover, the wafer holding plate bends in a form adapted to the global irregularities of the wafer (absorbs the warpage of the wafer),
The wafer can be polished.

In the wafer polishing apparatus according to the fourth aspect, the annular member and the wafer holding plate are integrally displaced.
In this case, since the wafer holding plate is configured as specified, the central portion of the wafer holding plate serves as a wafer holding / pressing region. At the same time, since the portion of the wafer holding plate on the outer peripheral side from the suction / pressing area becomes the movable area, it is difficult to avoid several μm.
Poor assembling accuracy of the polishing machine on the order of m to several tens of μm, poor processing accuracy of parts, thermal and mechanical deformation due to use, etc. are absorbed, and the wafer is held at a predetermined position against the abrasive friction force. Can be polished.

[0016]

Next, the present invention will be described more specifically with reference to embodiments shown in the drawings. Example 1 FIG. 1 is a sectional view of a main part of a wafer polisher, FIG. 2 is a plan view of a wafer holding plate (hereinafter, referred to as a holding plate), and FIG. 3 is a sectional view thereof. In this embodiment, the holding plate is a wafer suction plate formed with a large number of vacuum suction holes, and as shown in FIG.
Is provided so as to face the polishing platen 31 and to be able to move up and down to constitute a wafer polishing apparatus. In the suction / rotation device 11,
At the tip of the rotating shaft 14 where the flow paths 12 and 13 are formed,
A cylindrical housing 16 having one end opened and an annular projection 15 provided on the inner peripheral surface is fixedly attached, so that the rotating shaft 14 can be forcibly rotated and can be moved up and down. The flow paths 12 and 13 are connected to a vacuum pump and a compressor (neither is shown) via a pipe and an on-off valve, respectively.

The annular projection 15 of the housing 16 is a stretchable annular member, a tray-like sheet made of a highly elastic material having a circular hole opened in the center, for example, a rubber sheet 17.
Is fixed by screwing a ring-shaped mounting member 18, and the fixing portion is sealed with a rubber sheet 17.
The diameter of the circular hole matches the diameter of the wafer W to be polished.

The holding plate 19 is made of, for example, a circular thin plate of a hard material such as a hard plastic material, a hard rubber, or a metal, and is provided with flexibility. As shown in FIGS. Is a circular wafer holding region 20, and the flexibility of the outer ring-shaped portion is
The movable area 21 is formed by increasing the height. The difference in flexibility between the wafer holding region 20 and the movable region 21 is achieved by, for example, reducing the thickness of the movable region 21 or providing a through hole in the movable region 21 as described later. In FIGS. 1 and 2, reference numeral m denotes a boundary line between the wafer holding region 20 and the movable region 21, and n denotes a boundary line between the movable region 21 and a fixed portion of the housing 16 outside the movable region 21.

In the wafer holding area 20 of the holding plate 19,
As shown in FIG. 2, a plurality of vacuum suction holes (hereinafter, referred to as suction holes) 22 are formed. In this case, one is formed at the center of the holding plate 19 and a plurality of holes are formed on concentric circles around the center. I do. In addition, as shown in FIG.
3 is bonded to the back surface of the holding plate 19, that is, the surface opposite to the wafer suction surface, by including the thin, small-width, soft rod-shaped rubber 24 (or rod-shaped soft resin) including the suction hole 22c at the center. All the suction holes 22 are sealed with the suction holes 22c at the center, and all the other suction holes 2c are sealed.
2, and a hollow connector 25 (see FIGS. 1 and 3) is protruded from the suction hole 22c at the center. As shown in FIG. 1, a hollow connector 26 is protruded from an open end of the flow path 12 provided on the rotating shaft 14, and a flexible hose 27 such as a rubber hose is attached between the connector 26 and the connector 25. . Further, the outer peripheral end of the holding plate 19 is fixed to the distal end of the housing 16 by screwing or the like, and the outer peripheral end of the holding plate 19 in the wafer holding region 20 is bonded to the lower end of the rubber sheet 17 as an annular member. A closed chamber 29 is formed in the housing 16.

To easily assemble the structure shown in FIG.
Preferably, the housing 16 is divided vertically. For example, in a case where the structure is divided into two parts so as to be fittable with each other at a portion indicated by a dashed line L in FIG. 1 and fastened with bolts, the holding plate 19 is fixed to the lower half of the housing 16 in advance in a predetermined manner. The flexible hose 27 is attached to the connector 25, and the flexible hose 27 is connected to the connector 26.
Then, the lower half part is fastened to the upper half part, so that assembly can be performed easily and quickly.

The holding plate 19 is composed of a wafer holding area 20 and a movable area 21 having a higher flexibility (this will be described in each embodiment described later), and the outer peripheral end of the wafer holding area 20 is made of rubber. Fixing to the sheet 17, holding plate 1
9 is fixed to the front end of the housing 16 because the assembly accuracy of the polishing machine on the order of several μm to several tens μm is poor.
It is an object of the present invention to perform surface reference polishing while holding a wafer W at a predetermined position against a component processing accuracy defect, thermal / mechanical deformation due to use, and the like, and resisting abrasion frictional force.

A rubber sheet 17 is used as the tray-shaped sheet.
Alternatively, a plastic sheet formed in a bellows shape can be used. In any case, any material having a property of freely expanding and contracting in accordance with the fluid pressure in the housing 16 may be used. As a material forming the holding plate 19, a material having mechanical strength, flexibility, elasticity, and heat resistance is used. As a plastic material, a thermosetting resin, a heat-resistant thermoplastic resin, Alternatively, in addition to those obtained by reinforcing these resins with glass fibers or synthetic fibers, laminated products reinforced with fibers, paper, or the like may be used.
Further, a hard rubber thin plate or a corrosion-resistant metal thin plate can be used instead of the plastic holding plate. On the other hand, it is preferable that the polishing cloth 32 provided on the polishing platen 31 does not easily undergo plastic deformation by the pressing force of the holding plate 19, and a polishing cloth made of a urethane foam having a closed cell structure, a polyester nonwoven fabric A known cloth such as a polishing cloth impregnated with polyurethane can be used.

Next, the operation of the above polishing apparatus will be described with reference to FIG.
This will be described with reference to FIGS. First, the vacuum pump is actuated, and air is sucked in through the flow path 12, thereby producing a wafer W having a cross-sectional structure shown in FIG. 4 (in this figure, exaggerating the global unevenness of the wafer for convenience of explanation). (Shown) is held by suction on the holding plate 19. In this case, it is important to match the outer peripheral edge of the wafer W with the outer peripheral edge of the wafer holding region 20 of the holding plate 19. Then, by the operation of the compressor, compressed air at a predetermined pressure is supplied into the closed chamber 29 through the flow path 13, and the rubber sheet 17 and the holding plate 1 are supplied.
The wafer W is pressed against the polishing cloth 32 by displacing the wafer 9 integrally, and polishing is performed by a normal method.

In this case, since the rod-shaped rubber 24 is used as a member for connecting the suction holes 22 of the holding plate 19 to each other, the flexibility of the wafer holding region 20 in the holding plate 19 is not impaired, and 19 and vacuum channel 1
Since a flexible hose 27 is provided as a member for communicating with the holding member 2 and the holding plate 19 is attached to the rubber sheet 17, the holding plate 19 is freely displaced in accordance with the pressure of the compressed air supplied through the flow path 13. be able to. Further, since the holding plate 19 is attached to the front end of the housing 16, the wafer W is opposed to the frictional force acting on the polished surface of the wafer W.
Can be held in place. For this reason, as shown in FIG. 5, the entire surface of the oxide film 63 on the surface of the wafer W is brought into contact with the surface of the polishing pad 32 by the pressure from the surface of the holding plate 19, and the holding plate 19 extends over the entire back surface of the wafer W. Under a uniform polishing pressure distribution, the region to which the polishing pressure is applied does not spread outside the rear surface of the wafer.
Polishing is performed by bending the wafer 9 into a form adapted to the global unevenness of the wafer W. As a result, as shown in FIG. 6, the oxide film projection 64 (FIG. 4) corresponding to the portion where the wiring 62 is disposed is preferentially polished, and the entire wafer is polished without causing sagging around the periphery and projections due to insufficient polishing around the periphery. Polishing can be performed with a constant amount, and a wafer W having a uniform thickness of the oxide film 63 can be obtained.

Next, another embodiment in which the flexibility of the movable region 21 of the holding plate 19 is made higher than that of the wafer holding region 20 in the wafer polishing apparatus of the present invention will be described with reference to the following embodiments. Embodiment 2 In this embodiment, the holding plate is made of the same material, and as shown in FIG.
Is made thinner than the wafer holding region 20. The preferred thickness of the holding plate 19 depends on the polishing pressure of the wafer, the elastic modulus of the material constituting the holding plate, and the like. However, under normal polishing conditions, when the hard plastic thin plate is used, the wafer holding region 20 has a thickness of 0.5 mm. ~ 5.0mm
And the movable area is preferably set to 0.3 to 3.0 mm.
When a holding plate made of a hard rubber thin plate is used, the wafer holding area is set to 1.0 to 8.0 mm, and the movable area is set to 0.1 to 8.0 mm.
It is good to be 5-4.0 mm. When a metal thin plate is used, the wafer holding area is set to 0.1 to 1.0.
mm, and the movable area is desirably 0.01 to 0.05 mm.

Embodiments 3 and 4 In the embodiment 3, as shown in FIG.
The movable area 21 is formed by arranging a large number of through-holes 28 having an elliptical shape, a circular shape, a fan shape, or the like in the thin plate having the same thickness. Instead of the through hole 28, a number of concave portions having the same shape as the through hole may be formed, and the concave portion may form a thin portion. Alternatively, the concave portion may be formed in a ring shape and almost the entire movable region 21 is thinned. It can also be a part. In the fourth embodiment, as shown in FIG. 9, the holding plate 19 is made of a different material, the wafer holding region 20 is formed of a hard plastic thin plate, and the material of the movable region 21 is a rubber sheet containing synthetic fibers. Or as a synthetic fiber woven or knitted fabric.

Embodiment 5 In Embodiment 5, the outer peripheral end of the holding plate 19 is fixed to the housing 16 via a soft rubber layer 42 as shown in FIG.

Next, an example of the structure of the vacuum circuit of the holding plate 19 will be described. Embodiment 6 In this embodiment, as shown in FIG. 11, the suction holes 22 are formed on the wafer holding surface side of the holding plate 19 to the middle of the holding plate 19 in the thickness direction, and the center of the holding plate 19 and its periphery. Form many. A spiral groove 43 is formed on the back side of the holding plate 19, and the suction holes 22 communicate with the groove 43. Also,
The groove 43 is sealed with a spiral rod 44 made of soft rubber or soft resin. Further, the connector 25 is provided at the center of the groove 43.
By connecting a flexible hose (not shown) to the connector 25, all the suction holes 22 are connected to a vacuum source via the flexible hose.

Embodiment 7 In this embodiment, as shown in FIG. 12, the suction holes 22 of the holding plate 19 are formed as through holes, and the portion where the suction holes 22 are provided on the back surface of the holding plate 19 is sponge 45 (or elastic fiber). , The sponge 45 is covered with a soft rubber cover 46, and a vent hole 47 formed in the center of the cover 46 is connected to the connector 25 and the flexible hose 27.
Through a vacuum source.

Embodiment 8 In this embodiment, as shown in FIG. 13, the holding hole 19 of the holding plate 19 is formed as a through hole, and a soft rubber plate 49 having a spiral through hole 48 formed therein is used as a holding plate. A soft rubber lid 51 having the suction hole 22 communicated with the spiral through hole 48 by being superimposed on the back surface of the cover 19 and further having a vent hole 50 formed at the center.
Is superimposed on the plate body 49 to communicate the ventilation hole 50 with the spiral through hole 48, and the ventilation hole 50 is connected to a vacuum generation source via the connector 25 and the flexible hose 27.

Embodiment 9 In this embodiment, as shown in FIG. 14, a spiral groove 43 is formed on the surface of the holding plate 19 and a through hole 52 is formed at the center of the groove so as to communicate with each other. The hole 52 is connected to the connector 25.
And a vacuum source via a flexible hose 27.

Embodiment 10 In this embodiment, as shown in FIG. 15, the suction holes 22 are formed in the holding plate 19 as through holes. Soft rubber lid 53
In this case, a spiral groove 43 and a through hole 52 are formed at the center of the groove so as to communicate with each other. And lid 5
The suction hole 22 is communicated with the spiral groove 43 by superposing 3 on the back surface of the holding plate 19, and the through hole 52 is connected to a vacuum source via the connector 25 and the flexible hose 27.

Embodiment 11 In this embodiment, as shown in FIG. 16, the suction holes 22 of the holding plate 19 are formed as through holes, and these suction holes are communicated with a manifold 54 made of soft rubber or soft resin. The manifold 54 is connected to a vacuum source via a flexible hose (not shown).

In each of the above-described embodiments, a single wafer type polishing apparatus for holding and polishing one wafer W on the holding plate 19 is used. However, as another preferred embodiment, as shown in FIG. A plurality of ring-shaped mounting members 18 and a plurality of rubber sheets 17 are provided on each of the housings 16, and a holding plate 19 is mounted on the distal end portion of the housing 16 and all the rubber sheets 17. In this polishing apparatus, the holding plate 19
, A plurality of wafers W can be held at the same time and polishing can be performed in a batch system. In this case as well, a closed chamber 29 is formed in the housing 16.

As the wafer holding plate, a backing pad fixing type holding plate (non-wax method) can be applied instead of the vacuum suction type holding plate 19 in the above embodiment. In this case, an annular template is fixed to the outer periphery of the lower surface of the wafer holding plate.

[0036]

As is apparent from the above description, the wafer polishing method according to the first and second aspects and the wafer polishing apparatus according to the third aspect maintain the wafer during polishing.
The pressurized area on the back of the holding plate, the wafer holding plate is the back of the wafer
The main point is to match the area facing the wafer, and the wafer holding area is formed of a thin plate made of a hard plastic material or the like to be a flexible holding plate, so that a uniform polishing pressure distribution over the entire back surface of the wafer. The wafer can be polished while the region under the polishing pressure does not spread outside the rear surface of the wafer, and the wafer holding plate bends into a form adapted to the global unevenness of the wafer. For this reason, planarization processing in the process of manufacturing a semiconductor device can be performed accurately, and an oxide film (interlayer insulating film) having a high uniformity of the film thickness can be maintained. This has the effect of improving yield and reliability. In the wafer polishing apparatus according to the fourth aspect, since the portion on the outer peripheral side from the wafer holding area is the movable area, inferior assembly accuracy of the polishing machine of several μm to several tens μm, which is difficult to avoid, is absorbed. Since the wafer can be polished while holding the wafer at a predetermined position against the polishing frictional force, the precision of planarization can be further improved, and an extremely reliable device can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a main part of a first embodiment of the present invention.

FIG. 2 is a plan view of a wafer holding plate according to the first embodiment.

FIG. 3 is a cross-sectional view of a wafer holding plate according to the first embodiment.

FIG. 4 is a sectional view of a wafer before polishing.

FIG. 5 is an operation explanatory sectional view of the first embodiment.

FIG. 6 is a cross-sectional view of the wafer after polishing.

FIG. 7 is a sectional view showing a main part of the second embodiment.

FIG. 8 is a schematic plan view of a wafer holding plate in a third embodiment.

FIG. 9 is a cross-sectional view illustrating a main part of a fourth embodiment.

FIG. 10 is a sectional view showing a main part of a fifth embodiment.

FIG. 11 is a sectional view of a wafer holding plate in a sixth embodiment.

FIG. 12 is a sectional view of a wafer holding plate in a seventh embodiment.

FIG. 13 is a sectional view of a wafer holding plate according to an eighth embodiment.

FIG. 14 is a sectional view of a wafer holding plate in the ninth embodiment.

FIG. 15 is a sectional view of a wafer holding plate in the tenth embodiment.

FIG. 16 is a partial sectional view of a wafer holding plate according to an eleventh embodiment.

FIG. 17 is a cross-sectional view showing a main part of an embodiment of an apparatus capable of holding a plurality of wafers W and performing polishing in a batch manner.

FIG. 18 is a sectional view of a conventional example.

19 is an operation explanatory view of the conventional example of FIG. 18;

FIG. 20 is a schematic sectional view of another conventional example.

FIGS. 21A and 21B show a preferable polishing state, wherein FIG. 21A is an explanatory diagram of a polishing pressure distribution, and FIG. 21B is a cross-sectional view of a polished wafer.

FIG. 22 shows an example of an unfavorable polishing state.
(A) is an explanatory view of a polishing pressure distribution, and (b) is a cross-sectional view of a polished wafer.

FIG. 23 shows another example of an unfavorable polishing state.
(A) is an explanatory view of a polishing pressure distribution, and (b) is a cross-sectional view of a polished wafer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Suction / rotation apparatus 12, 13 Flow path 14 Rotation shaft 15 Annular projection 16 Housing 17 Ring member (rubber sheet) 18 Mounting member 19, 81, 91 Holding plate 20 Wafer holding area 21 Movable area 22 Suction hole 23 Long groove 24 Rod shape Rubber 25, 26 Connector 27 Flexible hose 28 Through hole 29 Sealed chamber 31 Polishing surface plate 32 Polishing cloth 42 Soft rubber layer 43 Spiral groove 44 Spiral rod 45 Sponge 46 Cover 47 Air vent 48 Spiral through hole 49 Plate Body 50 Vent Hole 51 Lid Body 52 Through Hole 53 Lid Body 54 Manifold 61 Wafer 62 Wiring 63 Oxide Film 64 Oxide Film Protrusion 71 Elastic Film 72 Body 73 Fluid Supply Means 74 Rotation Axis 75 Guide Plate (Template) 76 Polishing Constant Board 82 Mounting pad 83 Template 84 Polishing constant 85 distribution m of the polishing pad 92 polishing cloth A near sag B protrusion D polishing pressure, n boundary W (in the process of manufacturing the semiconductor device) wafer

────────────────────────────────────────────────── ─── Continuing on the front page (72) Fumio Suzuki Inventor 150 Odakura Osaikura, Nishigo-mura, Nishishirakawa-gun, Fukushima Prefecture Shin-Etsu Semiconductor Co., Ltd. Semiconductor Shirakawa Research Laboratories (56) References JP-A-2-98927 (JP, A) JP-A-5-69310 (JP, A) JP-A-6-15563 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B24B 37/04 B24B 37/00 H01L 21/304 622

Claims (12)

(57) [Claims] 1. A method of polishing a wafer by holding a wafer with its back surface in contact with a wafer holding plate and supplying a pressurized fluid to the back side of the wafer holding plate to bring the wafer into pressure contact with a polishing platen. A method of polishing a wafer, wherein a pressure region on the back surface of the wafer holding plate during wafer polishing is matched with a region where the wafer holding plate faces the back surface of the wafer. 2. A wafer holding plate as the wafer holding plate.
Using a flexible plate whose area is made of a hard thin plate,
In a state where the outer peripheral end is matched with the outer peripheral end of the flexible plate body
By holding the wafer on the wafer holding plate, the wafer
The pressurized area on the back of the wafer holding plate during wafer polishing
Make sure that the holding plate matches the area facing the back of the wafer.
2. The method for polishing a wafer according to claim 1, wherein: 3. An apparatus for polishing a wafer by holding the wafer with its back surface in contact with a wafer holding plate and supplying a pressurized fluid to the back surface of the wafer holding plate to bring the wafer into pressure contact with a polishing platen. The wafer holding area is made of a thin plate of a hard material, and a flexible wafer holding plate is fixed to an opening of the housing via an elastic annular member to seal the opening, and the inside of the housing is closed. A wafer polishing apparatus, wherein the wafer is polished to a pressurized fluid supply source. 4. A wafer holding region is defined as a central portion of the wafer holding plate, and an inner peripheral end portion of the annular member is fixed to an outer peripheral end portion of the wafer holding region so that the positions of these end portions coincide with each other. 4. The movable plate according to claim 3, wherein the outer peripheral portion of the holding plate has a flexibility higher than that of the wafer holding region than the wafer holding region to form a movable region, and an outer peripheral end of the wafer holding plate is fixed to the housing. The described wafer polishing apparatus. 5. The entire wafer holding plate is made of the same material, and the movable region is made thinner by making the thickness of the wafer holding plate thinner than the wafer holding region or by providing a concave portion in the wafer holding plate. 5. The wafer polishing apparatus according to claim 4, wherein the wafer polishing apparatus is formed by: 6. The wafer holding plate according to claim 4, wherein the whole of the wafer holding plate is made of a material having the same and uniform thickness, and the movable region is formed by providing a through hole in the wafer holding plate. Wafer polishing equipment. 7. The wafer polishing apparatus according to claim 4, wherein an outer peripheral end of said wafer holding plate is fixed to a housing via a soft rubber layer. 8. The wafer according to claim 3, wherein the wafer holding plate is a suction plate having a plurality of vacuum suction holes, and the vacuum suction holes are connected to a vacuum source via a flexible hose. Polishing equipment. 9. A soft rubber having a plurality of vacuum suction holes formed in the wafer holding plate as through holes and formed around the center of the wafer holding plate, and a long groove formed on one surface on the back surface of the wafer holding plate. 9. The wafer according to claim 8, wherein a rod body made of a soft resin is fixed, all the suction holes are communicated with each other, and the suction hole at the center is connected to a vacuum generating source via a flexible hose. Polishing equipment. 10. A vacuum suction hole of the wafer holding plate is formed as a through hole, and a portion where the vacuum suction hole is provided on the back surface of the wafer holding plate is covered with a sponge or an aggregate of elastic fibers. Covered with a rubber lid,
9. The wafer polishing apparatus according to claim 8, wherein a ventilation hole provided at a central portion of the lid is connected to a vacuum generation source via a flexible hose. 11. A vacuum suction hole of the wafer holding plate is formed as a through hole, and a soft rubber plate having a spiral through hole is superimposed on the back surface of the wafer holding plate, and the vacuum suction hole is swirled. A flexible rubber lid having a ventilation hole formed in the center is overlapped on the plate body, and the ventilation hole is communicated with the spiral through hole, and the ventilation hole is flexible. 9. The wafer polishing apparatus according to claim 8, wherein the apparatus is connected to a vacuum source via a hose. 12. The wafer holding area a plurality formed in the wafer holding plate, claim the wafer holding region, respectively, characterized in that fixed to the housing through the individual elastic annular member 3 to 11 The wafer polishing apparatus according to any one of the above.