JP5919592B1 - Polishing equipment - Google Patents

Abstract

[PROBLEMS] To prevent wasteful disposal of a large amount of slurry, to prevent contamination of the apparatus due to slurry scattering, to prevent deterioration of the surface roughness of the sample by circulating chips and the like, and to adsorb and fix the sample. Provided is a high-speed polishing tool that solves the drawbacks such as slurry permeating into the chuck due to vacuum suction by the vacuum chuck and fouling the chuck surface or clogging the vacuum piping.
A vacuum tool formed on a rocking table is formed by forming a spiral groove on the surface of a polishing pad 5 affixed to the surface of a polishing tool and rotating a small tool having a slurry circulation channel in the polishing tool. In a polishing apparatus for polishing a fixed sample, the diameter is such that the periphery of the sample is surrounded and the thickness is the same as or slightly thinner than the sample, and the outer periphery of the polishing tool 1 does not protrude even if the polishing tool 1 swings on the sample. By providing the annular plate 14 with which the polishing tool 1 protrudes, it is possible to prevent the slurry from being consumed in large quantities and from being scattered.
[Selection] Figure 4

Description

  The present invention relates to a polishing apparatus for flatly processing a silicon substrate, a glass substrate, silicon carbide, gallium nitride, sapphire substrate, and the like.

  High flatness is required for silicon substrates, silicon carbide, gallium nitride, sapphire substrates, and the like in order to increase the density, speed, and power consumption of semiconductors and optical devices. In particular, other substrates than the silicon substrate are hard and strong in chemical resistance, and require a very long processing time.

  A polishing technique called CMP (Chemical Mechanical Polishing or Planarization) is drawing attention as a technique for planarizing these substrates (wafers). CMP is a technique for removing a surface layer of a wafer by using a chemical action in combination with physical polishing. Specifically, using an abrasive called slurry in which abrasive grains (silica, alumina, cerium oxide, etc.) are dispersed in a soluble solvent of an abrasive such as acid, alkali, or oxidizer, suitable polishing is performed. Polishing is advanced by pressing the wafer surface with a cloth (pad) and rubbing it with relative motion.

  This polishing technique still has many problems. Above all, as a measure to solve the problems such as large consumption of slurry and pad and increase in size of the apparatus accompanying the wafer diameter expansion, the wafer surface is swung with a pad smaller than the wafer described in Non-Patent Document 1 below. A small-diameter pad method for polishing while being proposed has been proposed. In this method, since polishing is performed with a small pad, the apparatus can be reduced in size based on the wafer diameter, and there is an advantage that high-speed and high-pressure polishing is facilitated.

1 to 3 show an example of a polishing apparatus using a conventional small-diameter pad system.
As shown in FIG. 1, a conventional polishing apparatus using a small-diameter pad system rotates a small polishing tool 1 with a polishing pad 5 in the direction of arrow a while pressing it against a sample 2 as an object to be polished. Process. The sample 2 is held by a chuck 3 such as a vacuum porous chuck or a vacuum pin chuck, and may be rotated backward in the direction of the arrow b in order to increase the relative speed. The chuck is mounted on the base portion 4a on the swing table 4 and linearly swings in the direction of the arrow 6. In this apparatus, it is also possible to stop the oscillation and process the sample by fixing the polishing tool at an arbitrary position.

  In order to use this polishing apparatus at high speed, a spiral groove 7 for collecting the slurry shown in FIG. 2 and a grid for uniformly supplying the slurry into the pad surface are provided on the surface of the small-diameter polishing pad 5 affixed on the small polishing tool 1. A composite groove comprising grooves 8 is formed, and a flow path 10 for circulating the slurry shown in FIG. 3 is provided in the polishing tool 1. The slurry 9 supplied from the center of the polishing tool 1 is provided on the outer periphery of the polishing tool 1 through a circulation channel 10 provided radially from the center of the polishing tool 1 toward the outer periphery by centrifugal force generated by the rotation of the polishing tool 1. The slurry 2 is supplied from the slurry supply hole 11 to the contact surface 12 between the sample 2 and the polishing pad 5. Since the polishing tool 1 is rotating, the slurry is collected at the center of the polishing tool 1 by the spiral groove 7 formed on the surface of the polishing pad 5. The recovered slurry returns to the circulation channel 10 through the inflow hole 13 at the center of the polishing tool 1. As a result, 30% or more of the slurry circulates and slurry consumption can be suppressed. Arrows indicate the direction of slurry flow.

Journal of Precision Engineering, Vol. 68, No. 3 (2002) pp. 461-465 Proceedings of the 2013 Annual Meeting of the Japan Society for Precision Engineering, pp. 237 −238

  In the polishing apparatus shown in FIG. 1, the slurry can be collected at the center of the polishing tool 1 by the spiral groove 7 shown in FIG. 2, and the slurry can be circulated by the circulating flow path in the polishing tool 1 shown in FIG. 3. Therefore, the amount of slurry to be used can be reduced to 1/3 to 1/5, compared with a polishing pad consisting of only ordinary lattice grooves. Furthermore, when processing using a polishing pad without grooves in the range of the outer periphery of the polishing pad 5 mm, scattering of the slurry is suppressed and at the same time the processing amount is improved by 5 to 10%, but when a normal hard pad is used, Since the discharge of chips becomes worse, the surface roughness deteriorates.

  These slurries can be reduced as long as the polishing tool does not protrude from the sample. However, if the polishing tool protrudes from the sample, the slurry is scattered by the high-speed rotation of the polishing tool, and the slurry cannot be recovered by the spiral groove. The slurry consumption increases. On the other hand, the protrusion of the polishing tool is indispensable for the flattening of the sample in the method using the small-diameter pad. Therefore, a large amount of slurry is consumed at the same time as the protrusion. Further, since a vacuum chuck is used for fixing the sample, the slurry is sucked into the chuck or the vacuum pipe, which causes the surface of the chuck to become dirty or the pipe to be clogged.

  The present invention has been made in view of the above-described conventional problems. The object of the present invention is to surround the outer periphery of the sample so that the outer periphery of the tool does not protrude from the sample even if the polishing tool swings. An annular plate that is substantially equal to the thickness of the sample is provided to suppress slurry consumption even when the polishing tool protrudes from the sample.

  In the present invention, a suction device or a delivery device that forcibly sucks and feeds the slurry is provided to reduce the consumption of the slurry, prevent scattering, and promote circulation.

  In addition, it is possible to remove chips and agglomerated slurry by providing a filter in the circulation channel or suction pipe.

  Furthermore, another object of the present invention is to provide a polishing apparatus that does not cause slurry suction into the chuck by using a water film chuck described in Non-Patent Document 2 below for fixing a sample.

  In order to achieve the above object, as shown in the first embodiment of FIGS. 4 (a) and 4 (b), the present invention surrounds the chuck plate 3 to which the sample 2 is fixed and the periphery of the sample, and has a thickness of Fixed to the chuck plate 3 that is the same as or slightly thinner than the sample and has an outer diameter that does not protrude from the outer periphery of the small tool even when the small polishing tool 1 linearly swings over the sample within the range of the double arrow 15. It is composed of an annular plate 14.

  Furthermore, in the polishing tool 1 shown in the tool detail view of FIG. 5, a filter 16 is provided in a flow path passing through the tool center of the circulation flow path 10 through which the slurry circulates. The slurry recovered in the slurry inflow hole 13 by the spiral groove 7 formed on the pad surface shown in FIG. 2 passes through the filter 16 and passes through the circulation channel 10 together with the slurry supplied from the tool center. The sample is supplied again to the sample surface.

  As shown in the tool detailed view of FIG. 6, the slurry recovered in the slurry inflow hole 13 is sucked into the slurry installed in the center of the tool by a suction device (not shown) connected to the slurry suction pipe 18. 17 flows through the filter 16 and is collected in a slurry collection box (not shown). The recovered slurry is combined with a new slurry, passed through a slurry supply pipe 19 by a slurry delivery device (not shown), and sent into a pipe installed at the center of the tool as a supply slurry 9, and the circulation flow path 10 is It is characterized in that it is supplied again to the sample surface.

  In the first embodiment, the case where there is one sample 2 is shown. However, in the second embodiment shown in FIGS. 7A and 7B, seven samples 2 are dense with respect to the center of the chuck. Be placed. The chuck plate 3 and the polishing tool 1 are rotated in opposite directions as indicated by arrows in order to increase the amount of processing, and the polishing tool linearly swings within a swing range 15 indicated by double arrows that do not protrude from the annular plate 14. Be made. The sample 2 is fixed on a flat chuck plate 3 whose surface is polished to a mirror surface by a water film having a thickness of 1 μm or less. A disc having seven holes slightly larger than the sample diameter and having a height equal to or slightly thinner than the sample diameter is inserted into the chuck plate 3 so that these samples can be inserted. It is characterized in that it is affixed with a water film of 1 μm or less, or a silicone resin, acrylic or synthetic rubber adhesive tape or double-sided adhesive tape 20 having a higher shear strength.

  The annular plate 14 has a thickness equal to the thickness of the sample, or several tens of μm to 0. A thin one having a thickness of about 1 mm and a hole diameter 0.1 to 2 mm larger than the sample is used. The material is made of a ceramic material that is harder to process than the sample, or a metal, and an inorganic or organic resin material that hardly damages the sample.

  The annular plate 14 may be made of a resin material that is easily deformed so that the plate thickness is slightly thicker than that of the object to be polished and is sandwiched between the tool and the base so that the thickness becomes equal to that of the object to be polished.

  In the polishing apparatus according to the present invention, an annular plate having a thickness approximately equal to or slightly thinner than the sample thickness is provided around the sample, and the polishing tool is swung without protruding from the annular plate. Consumption can be greatly reduced. In addition, since the thickness of the annular plate is equal to or slightly thinner than the sample, the clearance between the sample and the annular plate is reduced, so that the slurry scattered by centrifugal force can be extremely reduced, and the contamination of the device due to scattering can be eliminated. .

  By providing a filter in the circulation channel that circulates the slurry provided in the polishing tool and the suction piping that sucks the slurry, it is possible to remove chips and agglomerated slurry due to polishing, improving the surface roughness of the sample it can.

  On the other hand, by using a water film chuck instead of the conventionally used vacuum chuck, slurry entering from the gap between the annular plate and the sample is not sucked into the chuck, and the chuck surface can be kept clean at all times. Therefore, when the thin plate is polished, it has an effect of preventing generation of polishing dimples caused by dust being sandwiched between the sample and the chuck surface.

(A), (b) is the schematic diagram and front sectional view which show one Example of the grinding | polishing apparatus which is performing rocking grinding | polishing using the conventional small grinding | polishing tool. It is the figure of the grinding | polishing tool which stuck the grinding | polishing pad which has the conventional spiral groove | channel and a lattice groove | channel. It is a schematic diagram of a slurry flow in a polishing tool having a conventional circulation channel that flows radially from the center toward the outer periphery and returns to the center of the tool. (A), (b) is the top view and front sectional view which show one Example of the grinding | polishing apparatus which concerns on the 1st Embodiment of this invention. 1 is a detailed view of a polishing tool including a slurry flow according to a first embodiment of the present invention. It is the figure which added slurry suction piping and supply piping to the detailed view of the polish tool containing the slurry flow concerning a 1st embodiment of the present invention. (A), (b) is the top view and front sectional view which show one Example of the grinding | polishing apparatus which concerns on the 2nd Embodiment of this invention.

4 to 6 show a first embodiment of the present invention.
FIGS. 4A and 4B are a plan view and a BB ′ cross-sectional view showing the first embodiment of the freezing pin chuck device according to the present invention.
As shown in the figure, an annular plate 14 having a thickness approximately equal to or thinner than that of the sample 2 is fixed on the chuck plate 3, and a polishing pad 5 having a diameter of 1/2 to 2/3 of the sample is formed. The sample is polished while rotating and swinging the affixed polishing tool 1. The swing range is the range indicated by the double arrow 15 and does not protrude from the annular plate 14.

  In this polishing tool, the circulation channel 10 for circulating the slurry shown in FIG. 5 is provided. Therefore, the slurry 9 supplied from the center of the polishing tool is separated from the center of the polishing tool by the centrifugal force generated by the rotation of the polishing tool. It flows in the direction of the arrow toward the outer periphery and is supplied from the slurry supply hole 11 to the contact surface 12 of the sample 2 and the polishing pad 5. The supplied slurry is collected at the center of the polishing tool by the spiral groove 7 formed on the surface of the polishing pad shown in FIG. 2, and returns to the circulation channel 10 through the slurry inflow hole 13. Since the filter 16 is provided in the flow path at the center of the polishing tool, chips and the like are removed, and the surface roughness of the surface of the sample 2 is not deteriorated.

  As shown in FIG. 4, when the polishing tool protrudes from the sample, the slurry supplied to the sample and the pad surface from the slurry supply hole 11 passes through the gap between the annular plate and the polishing tool by the polishing tool centrifugal force. However, since the clearance is small, the amount is small, and most of the slurry is collected at the center of the polishing tool by the spiral groove shown in FIG. 2 formed on the pad surface. Further, when processing is performed using a spiral polishing pad with a polishing pad having no groove in a range of 5 mm in the outer periphery of the pad, the consumption of slurry is further reduced, the processing speed is improved, and the scattering of the slurry can be prevented.

  On the other hand, in addition to the structure of FIG. 5, the amount of slurry recovered by sucking the slurry collected in the slurry inflow hole 13 at the center of the tool as shown in FIG. 6 into a suction pipe connected to a suction device (not shown). Since the slurry flowing out from the gap can be further reduced, the amount of slurry consumption can be reduced to the limit.

  At the same time, the circulation of the slurry is promoted by appropriately increasing the amount of the slurry to be circulated by applying an internal pressure to the slurry flowing from the supply pipe 19, and an energy-saving high-speed and high-pressure polishing without pad burning can be realized.

  At this time, it is necessary to control the internal pressure to be applied in accordance with the suction pressure and the tool rotation speed while suppressing the slurry leaking from the gap from increasing. The discharge pipe 18 is provided with a filter 16 to remove chips, agglomerated slurry, and the like, so that the surface roughness of the sample does not deteriorate. This filter is adapted to the abrasive grain size and does not obstruct the passage of the slurry as much as possible.

FIGS. 7A and 7B are a plan view and a BB ′ cross-sectional view showing a second embodiment of the polishing apparatus according to the present invention.
FIG. 7 shows an example of the annular plate 14 when a large number of samples are polished simultaneously. The sample is densely arranged and is pressed and polished while moving relative to each other with the polishing tool 1. An annular plate 14 having a sample 2 and a large number of fitting holes 14a slightly larger than the sample diameter and having a height equal to or slightly thinner than the thickness of the sample is formed on the chuck plate 3 with a water film (FIG. (Not shown).

  When the slurry is supplied from the center of the polishing tool and polishing is started, the slurry enters the gap between the fitting hole 14 a opened in the annular plate 14 and the sample 2. However, unlike the case where a vacuum chuck is used, the slurry is not sucked into the chuck or the vacuum pipe, and remains in the gap. If a solution in which the slurry does not dissolve in this gap is filled in advance, the slurry can be prevented from entering the gap. If the lateral force of the sample cannot be supported by the water film 20, use a silicone resin, acrylic, synthetic rubber adhesive tape, double-sided adhesive tape, or the like having higher shear strength instead of the water film. It may be pasted. In this embodiment, the sample is fixed with a water film, but a conventional fixing method such as water filling may be used.

In the above embodiment, seven fitting holes are provided in the annular plate, but this number may be provided in accordance with the number of samples. Moreover, you may utilize what has a hole of free shapes, such as a rectangle, a hexagon, and a rhombus according to the shape of a sample.
Similarly, in the first and second embodiments, the circular chuck plate 3 is provided. However, a rectangular or elliptic chuck plate may be provided. Moreover, in the said Example, although the filter was provided in the suction piping side of a slurry, you may provide in the delivery piping side.

  In the above embodiment, an example of linear rocking has been described. However, any rocking such as arc rocking can be applied, and it is sufficient that the rocking range of the polishing tool does not protrude from the annular plate. Although the sample is shown as being a thin plate, it can also be applied to a thick plate, a block, or the like. In that case, the sample may be simply placed in the annular plate. Further, in the above embodiment, the case where the sample and the tool rotate with each other has been described, but the present invention may be applied to an apparatus in which only the tool rotates.

  DESCRIPTION OF SYMBOLS 1 ... Polishing tool, 2 ... Sample, 3 ... Chuck, 4 ... Swing table, 5 ... Polishing pad, 6 ... Swing direction, 7 ... Spiral groove, 8 ... Lattice groove, 9 ... Supply slurry, 10 ... Circulation flow path 11 ... Slurry supply hole, 12 ... Contact surface between sample and polishing pad, 13 ... Slurry inflow hole, 14 ... Annular plate, 15 ... Swing range, 16 ... Filter, 17 ... Suction slurry, 18 ... Slurry suction pipe, 19 ... Slurry supply piping

Claims (6)

In a polishing apparatus for polishing by rotating a polishing tool having a polishing pad opposite to the surface of the polishing object in order to remove unevenness on the surface of the polishing object by polishing and flatten or smooth the surface,
An annular plate having a thickness equal to or thinner than that of the object to be polished is provided so as to surround the periphery of the object to be polished, and the outer periphery of the polishing pad of the polishing tool is the outer periphery of the annular plate during the polishing process. So that it does not protrude from the surface,
The polishing pad of the polishing tool facing the object to be polished is provided with the polishing pad formed with a spiral groove for collecting slurry, the polishing tool has a slurry circulation channel, and connected to the circulation channel, A polishing apparatus provided with a suction device for forcibly sucking a processing liquid . The polishing apparatus according to claim 1, wherein
The polishing apparatus according to claim 1, wherein the annular plate has a shape that is thinner than the polishing object by several tens of μm to 0.1 mm. The polishing apparatus according to claim 1 or 2 ,
A polishing apparatus, comprising: a delivery device that forcibly feeds the processing liquid sucked by the suction device to the slurry circulation passage of the polishing tool. The polishing apparatus according to claim 1 or 3 ,
A polishing apparatus, wherein a filter is provided in the circulation channel and the suction pipe of the suction device. The polishing apparatus according to any one of claims 1 to 4 ,
A polishing apparatus, wherein the polishing object is fixed on a mounting table of the polishing object by a water film chuck. The polishing apparatus according to any one of claims 1 to 5 ,
The annular plate is formed with a plurality of fitting holes in which a plurality of the objects to be polished are fitted and held, and polishing is performed so that the outer periphery of the polishing pad of the polishing tool does not protrude from the outer periphery of the annular plate. A polishing apparatus characterized in that a plurality of polishing objects are polished by being operated.