JP2010094806A - Surface polishing method, surface polishing device and surface polishing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out mirror finishing without a polishing flaw even on a large-area silicon wafer or the like; to improve the flatness of a working surface 16 by applying uniform pressure on the whole large-area working surface 16 for polishing. <P>SOLUTION: As slurry 26 mixed with diamond abrasive grains 24 is pressed onto one surface 18 toward the other surface 20 of a porous plate 12 having a large number of continuous pores 22 opening from the one surface 18 to the other surface 20, the other surface 20 is pressed against the working surface 16 of a polished material 14 so that the other surface 20 and the working surface 16 are rubbed together, thereby polishing the polished material 14. A lot of the diamond abrasive grains 24 are trapped in the openings 28 of the continuous pores 22 on the other surface 20 of the porous plate 12, thereby exhibiting a favorable and stable polishing function. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a surface polishing method, a surface polishing apparatus, and a surface polishing plate used for polishing for mirror surface processing of a silicon wafer or the like.

  In order to perform high-precision processing using a diamond grindstone for mirror processing of silicon wafers, improvements have been made to each part of the apparatus. (See Patent Document 1) (See Patent Document 2).

Japanese Patent Laid-Open No. 9-168947 JP-A-5-129259

The above existing technology has the following problems to be solved.
1. When a polishing process is performed by pressing a narrow block-shaped grindstone on the working surface of the silicon wafer, polishing marks called feed marks remain on the working surface of the silicon wafer.
2. When a thin and hard large-area substrate is polished by pressing a narrow grindstone on the working surface, the silicon wafer substrate is likely to be damaged due to fluctuations in pressure applied to each part of the working surface. When the area of the working surface becomes large, the flatness of the working surface becomes insufficient.
3. The flatness of the working surface greatly affects the mechanical properties of the silicon wafer substrate. However, in order to improve the flatness, a long polishing operation is required, which reduces productivity.
In order to solve the above problems, an object of the present invention is to provide the following surface polishing method and the like.
1. Even a large-area silicon wafer can be mirror-finished without polishing marks.
2. It is possible to polish by applying a uniform pressure to the entire wide working surface.
3. The flatness of the working surface can be increased in a short time, and productivity is improved.
4). Long-term stable polishing performance can be maintained.

  The surface polishing plate of the present invention is a liquid having a viscosity that does not naturally flow down from the other surface of the porous plate at room temperature to a porous plate having a large number of open cells leading from one surface to the other surface. A surface polishing plate impregnated with a mixture of abrasive grains.

  Preferably, the liquid is a liquid that is softened by heat generated during the polishing process to increase fluidity.

  Preferably, the surface polishing plate further includes a holding container that is disposed on the one surface side of the porous plate and stores a liquid mixed with the abrasive grains.

  Preferably, the abrasive grains are diamond abrasive grains, and the diamond abrasive grains are mixed in the porous plate.

  The surface polishing method of the present invention is a liquid having a viscosity that does not naturally flow down by gravity from the other surface of the porous plate to the porous plate having a large number of open cells leading from one surface to the other surface at room temperature. The other surface of the surface polishing plate impregnated with a mixture of abrasive grains is pressed against the working surface of the material to be polished, and the other surface and the working surface are slid together to form the material to be polished. Is a surface polishing method for polishing or grinding.

  The surface polishing apparatus of the present invention is a liquid having a viscosity that does not naturally flow down by gravity from the other surface of the porous plate to the porous plate having a large number of open cells leading from one surface to the other surface. The other surface of the surface polishing plate impregnated with a mixture of abrasive grains is pressed against the working surface of the material to be polished, and the other surface and the working surface are slid together to form the material to be polished. It is the surface polishing apparatus provided with the mechanism which grind | polishes or grinds.

  Preferably, the surface polishing apparatus includes supply means for supplying the liquid mixed with the abrasive grains on the one surface of the surface polishing plate.

  Preferably, the surface polishing plate further includes a holding container that is disposed on the one surface side of the porous plate and contains a liquid mixed with the abrasive grains, and the holding container is connected to the mechanism. The connecting part is provided.

The following configurations are also means for solving the above problems.
<Configuration 1>
A porous plate having a large number of open cells leading from one surface to the other surface is formed with a slurry flow mixed with abrasive grains from the one surface toward the other surface, and the other surface is polished. A surface polishing method characterized by polishing the material to be polished by pressing against the working surface of the material and sliding the other surface and the working surface together.

  The porous plate is, for example, a plate having a porous structure such as a foam metal plate. It has open cells for passing the slurry instead of closed cells. When the polishing process is performed while supplying the slurry mixed with abrasive grains from one surface of the porous plate toward the other surface, the abrasive grains exhibit a good and stable polishing function.

<Configuration 2>
In the surface polishing method according to Configuration 1, the bubble opening located at a portion of the other surface in contact with the working surface of the material to be polished contains a particle having a particle size larger than that of the abrasive grains. Surface polishing method.

  When the opening of the bubbles is larger than the grain size of the abrasive grains and exists on the working surface of the material to be polished, the polishing process proceeds while the abrasive grains freely roll in that portion. Compared with the case where the abrasive grains are fixed to the working surface, the processing efficiency is improved, and the working surface is finished well.

<Configuration 3>
In the surface polishing method according to Configuration 1 or 2, the open cell includes one having an opening larger than the particle size of the abrasive grains flowing together with the slurry and having a bent portion for trapping the same. A surface polishing method characterized by the above.

  When the open cell has a bent portion, the abrasive grains are trapped in any open cell of the porous plate. When the other surface is pressed against the work surface of the material to be polished and the polishing process is continued, the abrasive grains trapped in each part of the open cell appear one after another at the open part of the open cell on the other surface. Exhibits an excellent polishing function.

<Configuration 4>
A porous plate having a large number of open cells leading from one surface to the other surface, and a side wall covering and enclosing the entire surface of the one surface, containing a predetermined amount of slurry mixed with abrasive grains, A slurry supply unit that forms a slurry flow mixed with abrasive grains from one surface to the other surface and the other surface of the porous plate are held almost horizontally, and the other surface of the porous plate is polished A surface polishing apparatus comprising: a driving mechanism that presses against a working surface of a material and slides the other surface and the working surface together to polish the material to be polished.

  A side wall that covers and surrounds the entire surface of one surface of the porous plate is provided, the slurry mixed with abrasive grains is accommodated therein, and the slurry is supplied to the porous plate. Thereby, said surface polishing method is realizable.

<Configuration 5>
A porous plate having a large number of open cells leading from one surface to the other surface, and a container covering and enclosing the entire surface of the one surface, containing a predetermined amount of slurry mixed with abrasive grains, A slurry supply unit that forms a slurry flow mixed with abrasive grains from one surface to the other surface and the other surface of the porous plate are held almost vertically, and the other surface of the porous plate is polished A surface polishing apparatus comprising: a driving mechanism that presses against a working surface of a material and slides the other surface and the working surface together to polish the material to be polished.

  Polishing is performed with the other surface of the porous plate held substantially vertically. Since the slurry flows vertically, new slurry can be continuously supplied and polished.

<Configuration 6>
A porous plate having a large number of open cells leading from one surface to the other surface is impregnated with a non-fluid liquid at room temperature mixed with abrasive grains, and disposed on one surface side of the porous plate A processing agent enclosing portion containing a non-flowable liquid mixed with the abrasive grains at room temperature, covering the other surface, and the other surface of the porous plate serving as the working surface of the material to be polished A surface polishing apparatus comprising: a driving mechanism that presses against the second surface and slides the other surface and the working surface together to polish the material to be polished.

  The abrasive grains are held in the open cells of the porous plate by a non-fluid liquid at room temperature. On the working surface, abrasive grains move around in the bubbles, and efficient polishing can be performed. If the porous plate is impregnated with the treatment agent in advance, the abrasive grains are uniformly dispersed in the open cells of the porous plate.

<Configuration 7>
A surface polishing plate characterized by impregnating a porous plate having a large number of open cells from one surface to the other surface with a non-fluid liquid at room temperature mixed with abrasive grains.

<Configuration 8>
A porous plate having a large number of open cells leading from one surface to the other surface is impregnated with a non-fluid liquid at room temperature mixed with abrasive grains, and placed on one surface side of the porous plate A surface polishing plate comprising: a treatment agent enclosure portion containing a non-fluid liquid at room temperature mixed with abrasive grains by closing a surface other than one surface.

1 is a longitudinal sectional view showing a surface polishing apparatus of Example 1. FIG. 2 is a cross-sectional view of a main part of a porous plate 12. FIG. It is a side view of the apparatus of Example 3. It is a longitudinal cross-sectional view of the apparatus of Example 4. 6 is a perspective view of a surface polishing plate of Example 4. FIG.

  Hereinafter, embodiments of the present invention will be described in detail for each example.

1 is a longitudinal sectional view showing a surface polishing apparatus of Example 1. FIG.
The apparatus shown in the figure uses a silicon wafer as an example of the material 14 to be polished. In order to polish this, a porous plate 12 is used. The workpiece 14 is fixed horizontally by a work chuck 41. The porous plate 12 is supported so as to be pressed against the working surface 16 of the material 14 to be polished. In order to form a flow of the slurry 26 from one surface 18 of the porous plate 12 toward the other surface 20, a slurry supply unit 51 is provided. In the following examples, all are expressed as polishing, but it goes without saying that grinding is also possible with this apparatus.

  The slurry supply unit 51 includes a slurry tank 45 having a side wall that covers the entire surface of the one surface 18 of the porous plate 12 and surrounds it. The porous plate 12 is fixed integrally to the grindstone holder 43 in advance, and is fixed to the lower surface of the slurry tank 45 by screws 44. Thus, the slurry supply unit 51 stores a predetermined amount of the slurry 26 mixed with the diamond abrasive grains 24 in the space surrounded by the slurry tank 45. A cap 47 for internal inspection and slurry replenishment is provided on the upper surface of the slurry tank 45, and an intake hole 48 for introducing outside air is provided at the center thereof.

  In the embodiment, diamond abrasive grains are used for polishing or grinding. However, other powders such as ceria, silica, and alumina can be used alone or in combination. A rotary drive shaft 49 is fixed to the slurry tank 45 and is driven to rotate in the direction indicated by the arrow 54 by the drive mechanism 53. As a result, the other surface 20 of the porous plate 12 is held almost horizontally, the other surface 20 of the porous plate 12 is pressed against the working surface 16 of the material to be polished 14, and the other surface 20 of the porous plate 12. And the work surface 16 of the material to be polished 14 are slid together to polish the material to be polished 14.

FIG. 2 is a cross-sectional view of the main part of the porous plate 12.
The porous plate 12 has a large number of open cells 22 that lead from one surface 18 (FIG. 1) to the other surface 20. One surface 18 of the porous plate 12 is open upward, and is supplied with a slurry 26 mixed with diamond abrasive grains 24. The slurry 26 moves downward in the porous plate 12 by gravity. The slurry is preferably a paste that does not flow out rapidly when operated at a high speed, rather than a low-viscosity liquid such as water. For example, it is preferable to have a viscosity that does not naturally flow down from the other surface of the porous plate 12 at room temperature. This viscosity may be selected in consideration of the relative physical properties of the slurry 26 and the porous plate 12.

  The porous plate 12 is, for example, a porous plate such as a foam metal plate. Not the closed cells but the open cells 22 for allowing the slurry 26 to pass therethrough. For the material of the porous plate 12, stainless steel, copper or ceramic material is suitable. Further, a plastic material such as phenol resin or polyurethane may be suitable depending on the mechanical characteristics of the material 14 to be polished. Natural materials such as charcoal can also be used. It is also possible to use a porous ceramic mixed with diamond abrasive grains 24 from the beginning.

  As shown in FIG. 2, diamond abrasive grains 24 are respectively provided in appropriate amounts in the bubble openings 28 located on the other surface 20 of the porous plate 12 in contact with the working surface 16 of the material 14 to be polished. Exists. When the diameter of the bubble opening 28 existing on the working surface 16 of the material to be polished is larger than the particle diameter of the diamond abrasive grains 24, the polishing process proceeds while the diamond abrasive grains 24 freely roll in that portion. As the polishing process proceeds, the other surface 20 of the porous plate 12 is worn down, and the diamond abrasive grains 24 are also pushed away by the slurry 26 and discharged. However, since new diamond abrasive grains 24 are newly supplied by the new slurry, an appropriate amount of diamond abrasive grains 24 is always present on the working surface 16 of the material to be polished.

  The porous plate 12 as described above can be easily manufactured with a large size and a lower price than a grindstone mixed with diamond abrasive grains 24. Therefore, it is possible to form a wider working surface than in the prior art, and to polish by applying a uniform pressure to the entire working surface. At the same time, even a large-area silicon wafer or the like can be mirror-finished without polishing marks. Moreover, since the diamond abrasive grains 24 are polished while freely rolling, the flatness of the working surface can be increased in a short time, and the productivity is improved. Furthermore, since the diamond abrasive grains 24 are successively supplied by the slurry, stable polishing performance can be maintained for a long time.

  For example, when a conventional grindstone having diamond abrasive grains 24 fixed thereto is used, it is necessary to continue the polishing process for a long time while changing the direction of the grindstone in order to bring the diamond abrasive grains 24 into contact with the entire working surface 16. On the other hand, as in this embodiment, when the diamond abrasive grains 24 are confined in the opening portions of the bubbles and the diamond abrasive grains are freely rolled at the portions, the polishing process proceeds in a short time. Touch the entire surface. Therefore, the polishing rate can be sufficiently improved. In addition, as compared with the case where the fixed diamond abrasive grains 24 are strongly pressed against the working surface, the diamond abrasive grains 24 roll while being in contact with the working surface 16 at an appropriate pressure, so that the polishing process proceeds. it can.

  The diamond abrasive grains 24 can be rolled even if the slurry mixed with the diamond abrasive grains 24 is poured into the working surface 16 and polished while being pressed by a grindstone. However, the positions of the diamond abrasive grains 24 are gradually shifted, and it is difficult to uniformly polish the entire working surface 16. Further, the proportion of the diamond abrasive grains 24 contributing to polishing is small, and most of them are washed away out of the working surface. In this embodiment, the diamond abrasive grains 24 are confined inside the bubble openings 28 and the polishing process is performed while restricting the movement, so that the diamond abrasive grains 24 can be uniformly dispersed over the entire working surface 16. . The proportion of diamond abrasive grains 24 that do not contribute to polishing is extremely small.

  The above method is suitable for mirror processing of a substrate made of a silicon wafer, gallium arsenide, or the like. Further, for example, the ceria slurry 26 (manufactured by Hitachi Chemical Co., Ltd., HS-8005 / HS-8102GP) can be subjected to an oxide removal process simultaneously by a chemical etching function. The pressure for supplying the slurry 26 is such a pressure that the slurry 26 flows slowly from one surface 18 of the porous plate 12 toward the other surface 20, and the pressure by gravity is sufficient. A pressurizing device is not necessary.

  According to the above apparatus, the diamond slurry 26 exudes from the porous plate 12 and the silicon wafer surface is polished with fine diamond, and at the same time, chemical etching is performed by the slurry 26 to remove oxide on the silicon wafer surface. . That is, chemical etching and mechanical etching are performed simultaneously. In addition to the silicon wafer, GaAs, InP, or the like is suitable as an object to be polished.

  Moreover, according to the above apparatus, the porous board 12 of a large area is employable compared with a silicon wafer. Specifically, the porous plate 12 having a radius of about 300 mm can be easily manufactured at a low cost. Therefore, even a large-area silicon wafer or the like can be mirror-finished without polishing marks. At the same time, polishing can be performed by applying a uniform pressure to the entire wide working surface 16. Furthermore, the flatness of the working surface 16 can be increased. In addition, the effective area is large, and this also shortens the polishing time. Therefore, there is an effect that the whole can be polished at a higher speed than conventional.

  The open cells 22 preferably include those having an opening larger than the particle diameter of the diamond abrasive grains 24 flowing together with the slurry 26 and having a bent portion 30 for trapping the diamond abrasive grains 24. When the bent portion 30 is present in the open cell 22, the diamond abrasive grains 24 are trapped in any open cell 22 of the porous plate 12. Therefore, it does not fall on the working surface 16 at a stretch. Further, when the polishing process is continued by pressing the other surface of the porous plate 12 against the working surface of the material to be polished, the diamond abrasive grains trapped in each part in the open cell are successively opened to the open cell on the other surface. Appears in the area and exhibits a good and stable polishing function.

  The bent portion 30 may be anywhere. The shape, quantity, etc. of the bent portion 30 can be freely selected according to the manufacturing conditions of the porous plate 12. Normally, the bent portions 30 are uniformly dispersed inside the porous plate 12, so that the diamond abrasive grains 24 are also dispersed and trapped inside the porous plate 12, thereby exhibiting a uniform polishing function as a whole.

FIG. 3 is a side view of the apparatus according to the third embodiment.
This apparatus is a vertical version of the apparatus shown in FIG. It is preferable that new slurry 26 is constantly supplied to the working surface 16 of the workpiece 14. Therefore, the polishing process is performed with the other surface 20 of the porous plate 12 held substantially vertically. A slurry tube 32 is attached to the upper part of the slurry tank 45 to continuously supply the slurry 26. After passing through the porous plate 12, the slurry 26 flows down vertically along the working surface 16. Accordingly, the new slurry 26 can be continuously supplied and polished. In addition, about another part, since it is the same structure as the apparatus of FIG. 1, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

4 is a longitudinal sectional view of the apparatus of Example 4.
As shown in the figure, this apparatus includes a processing agent enclosure 60 and a drive mechanism 66. The treatment agent enclosure 60 includes a porous plate 12 having a large number of open cells 22 extending from one surface 18 to the other surface 20. This porous plate 12 is impregnated with a non-flowable liquid 62 mixed with diamond abrasive grains 24 at room temperature. Furthermore, a holding container 61 that is disposed on one surface 18 side of the porous plate 12 and contains a non-flowable liquid 62 mixed with the diamond abrasive grains 24 at a room temperature with the surfaces other than the one surface 18 closed. Is provided.

  Various oils and fats that have no chemical influence on the material to be polished 14 can be used for the liquid 62 that is non-flowable at room temperature. Thereby, the effect demonstrated using FIG. 2 etc. can be exhibited. The holding container 61 may be appropriately provided with a vent hole.

  In addition to petroleum-based materials such as petroleum jelly and grease, vegetable oil or the like can be used for the liquid 62. As a method of impregnating the liquid 62, a vacuum impregnation method can be employed. The diamond abrasive grains 24 are mixed in the liquid 62 that has been heated to improve the fluidity while stirring, and the porous plate 12 is impregnated at once in a vacuum atmosphere. Further, it is preferable that the liquid 62 is softened by heat generated during the polishing process, and the fluidity is slightly increased. As a result, the non-flowable liquid 62 containing the diamond abrasive grains 24 accommodated in the holding container 61 is thermally expanded and flows, and is pushed out to the working surface 16 through the porous plate 12. Further, if calcium carbonate or the like is mixed in the liquid, a chemical polishing function can be exhibited. That is, a slurry having a high viscosity at room temperature can be used.

  A driving shaft 63 is fixed to the holding container 61 of FIG. 4, and the driving shaft 63 is connected to the motor rotating shaft via a motor chuck 65. Thus, the driving mechanism 53 presses the other surface 20 of the porous plate 12 against the working surface 16 of the workpiece 14 and slides the other surface 20 and the working surface 16 to polish the workpiece 14. To do. The diamond abrasive grains 24 are held in the open cells 22 of the porous plate 12 by the non-flowable liquid 62 at room temperature. On the working surface 16, the diamond abrasive grains 24 move around in the bubbles, so that efficient polishing can be performed. If the porous plate 12 is impregnated with the treatment agent in advance, the diamond abrasive grains 24 are uniformly dispersed in the open cells 22 of the porous plate 12.

FIG. 5 is a perspective view of a surface polishing plate of Example 4.
The porous plate 12 may be produced in large quantities in advance, and when worn, it may be used by removing it from the holding container 61 and replacing it with a new one. FIG. 5 (a) shows a replacement porous plate 12, which may be packaged and sold in a plastic case or the like. Also, as shown in FIG. 5B, an assembly in which the holding container 61 and the porous plate 12 are integrated is prepared as an assembly, and when the porous plate 12 is worn, the entire assembly is removed from the motor chuck 65. It should be used as a new one. (C) is one in which the holding container 61 is made of a thin metal or plastic and integrated with the holding container 61. This can be sold and replaced with a conventional pad. According to the fourth embodiment, since it is not necessary to arrange a mechanism for flowing the slurry on the back surface of the porous plate 12, the configuration of the apparatus can be simplified.

  Along with the higher integration and higher performance of semiconductor elements, CMP (Chemical Mechanical Polishing) has become an indispensable technology in multilayer wiring processes such as planarization of interlayer insulating films, metal plug formation, and buried wiring formation. According to each of the above embodiments, the function of the polishing pad can be greatly improved. In addition, high-quality surface polishing can greatly improve the fragility of a wafer such as GaAs.

DESCRIPTION OF SYMBOLS 10 Surface polishing apparatus 12 Porous board 14 To-be-polished material 16 Working surface 18 One side 20 The other side 22 Open cell 24 Diamond abrasive grain 26 Slurry 28 Opening 30 Bending part 32 Slurry tube 41 Work chuck 43 Grinding stone holder 44 Screw 45 Slurry Tank 47 Cap 48 Air intake hole 49 Rotation drive shaft 51 Slurry supply unit 53 Drive mechanism 60 Processing material enclosure 61 Holding container 62 Non-fluid liquid 63 Drive shaft 65 Motor chuck 66 Drive mechanism

Claims (8)

  A porous plate having a large number of open cells leading from one side to the other side is a liquid having a viscosity that does not naturally flow down by gravity from the other side of the porous plate at room temperature. Surface polishing plate impregnated with something.   The surface polishing plate according to claim 1, wherein the liquid is a liquid that is softened by heat generated during the polishing process to increase fluidity.   The surface polishing plate according to claim 1, further comprising a holding container that is disposed on the one surface side of the porous plate and stores a liquid mixed with the abrasive grains.   The surface polishing plate according to any one of claims 1 to 3, wherein the abrasive grains are diamond abrasive grains, and the diamond abrasive grains are mixed in the porous plate.   A porous plate having a large number of open cells leading from one side to the other side is a liquid having a viscosity that does not naturally flow down by gravity from the other side of the porous plate at room temperature. Surface polishing for polishing or grinding the material to be polished by pressing the other surface of the surface polishing plate impregnated with the surface against the working surface of the material to be polished and sliding the other surface and the working surface together Method.   A porous plate having a large number of open cells leading from one side to the other side is a liquid having a viscosity that does not naturally flow down by gravity from the other side of the porous plate at room temperature. There is provided a mechanism for polishing or grinding the material to be polished by pressing the other surface of the surface polishing plate impregnated with the surface against the working surface of the material to be polished and sliding the other surface and the working surface together. Surface polishing equipment.   The surface polishing apparatus according to claim 6, further comprising a supply unit that supplies the liquid mixed with the abrasive grains to the one surface of the surface polishing plate. The surface polishing plate further includes a holding container that is disposed on the one surface side of the porous plate and contains a liquid mixed with the abrasive grains,
The surface polishing apparatus according to claim 6, wherein the holding container includes a connecting portion that is connected to the mechanism.

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