JP6231334B2 - Thin plate substrate grinding method and grinding apparatus used therefor - Google Patents

Description

  The present invention relates to a thin plate substrate grinding method and a grinding apparatus used therefor. Specifically, the present invention relates to a grinding method for a thin plate substrate having a thickness of 10 to 2000 μm made of any one of silicon, silicon carbide, aluminum nitride, alumina, and sapphire, and a grinding apparatus used therefor.

  A grindstone is a tool formed by solidifying hard particles, that is, abrasive grains with a binder. There are two types of processing using a grindstone: grinding processing and polishing processing. Routine processing is customarily referred to as grinding processing, and finishing processing is referred to as polishing processing. In these processes, the surface of the workpiece, i.e., the surface to be processed, is moved by the abrasive grains by relatively moving the grindstone and the workpiece while the grindstone is pressed against the workpiece, i.e., the workpiece. It is a process to scrape off as.

  For grinding using a grindstone, cylindrical grinding that processes the cylindrical outer peripheral surface of the workpiece, internal grinding that processes the cylindrical inner peripheral surface of the workpiece, and processing the flat surface of the workpiece There is a surface grinder to do. As a grindstone for processing the outer peripheral surface or the inner peripheral surface, a grindstone provided with a cylindrical processed surface is used. In addition, as a grindstone for machining a flat surface, a cylindrical grindstone having a machining surface provided on the outer peripheral surface or a cup-shaped, ring-shaped and disc-shaped grindstone having a machining surface provided on a flat end surface is used. .

  Various proposals have heretofore been made regarding a method for grinding a thin plate substrate. For example, Japanese Patent Application Laid-Open No. 2009-16842 (Patent Document 1) discloses that a semiconductor wafer includes at least one grinding tool and a semiconductor wafer. In a method adapted to remove material on one or both sides by at least one grinding tool while supplying a coolant to the contact area between the coolant flow rate of the at least one grinding tool A method for grinding a semiconductor wafer selected with respect to the height of the grinding teeth is described.

  Japanese Patent Laying-Open No. 2011-3902 (Patent Document 2) discloses a method of simultaneously processing both sides of a semiconductor wafer, wherein the semiconductor wafer is freely movable and is rotated by a rotating device. Achieved by the above method of moving in a cycloid trajectory, wherein the semiconductor wafer is material-removed between two rotating ring-shaped work disks In the method for simultaneous processing of both sides of a semiconductor wafer, each work disk includes a work layer including an abrasive material, and an alkaline medium not including the abrasive material is described as a method of grinding a semiconductor wafer supplied during processing. .

  The inventions described in Patent Documents 1 and 2 are similar to the present invention in that double-side grinding is possible while supplying a coolant. However, a sufficient study has not been made on a refrigerant supply method that enables the shape correction of the thin plate substrate.

JP 2009-16842 A JP-A-2001-3902

  FIG. 1 is a diagram illustrating a thin plate substrate having an ideal shape. Materials such as silicon, silicon carbide, aluminum nitride, alumina, and sapphire are used for the thin substrate 1 that is the basis for the production of semiconductors, IC substrates, LED substrates, etc., and the shape is as shown in FIG. There are many cases.

  FIG. 2 is a diagram illustrating a cross-sectional shape of a thin plate substrate having warpage. In many cases, when looking at the cross section of a thin plate substrate, these materials have warped shapes as shown in 1 'of FIG. 2 due to heat treatment problems, surface roughness problems, and ideological defect problems. It has become. Since this warpage becomes an obstacle in the manufacturing process, for example, exposure processing, epitaxial processing, etc., as shown in FIG. 1, a thin plate substrate having no warpage in cross-sectional shape is preferable.

  Therefore, the present invention solves the problems of the prior art as described above and corrects the cross-sectional shape of the thin plate substrate to a flat ideal shape in order to remove obstacles such as exposure processing and epitaxial processing. An object of the present invention is to provide a thin plate substrate grinding method and a grinding apparatus used therefor.

  The present invention has been made as a result of intensive studies in order to solve the above-described problems, and the gist of the present invention is as follows.

(1) A method for grinding a thin plate substrate having a warped cross-section, and when the grinding plate is ground from both sides of the thin plate substrate by using a grindstone, a coolant is supplied from the entire surface of the grindstone through the open pores of the grindstone. The slurry having a chemical polishing agent, or a mixture thereof is supplied between the thin plate substrate and the grindstone, and hydrostatic pressure is applied to both surfaces of the thin plate substrate to maintain the shape having the warp, while the thin plate substrate having the warp is maintained . A method for grinding a thin plate substrate, wherein shape correction is performed by grinding upper and lower protrusions with a grindstone from both sides .
(2) The method for grinding a thin substrate according to (1), wherein the grindstone is a porous body having an open porosity of 20 to 60% by volume.

(3) A liquid or gas is directly discharged from a back portion of the grinding surface of the grindstone to prevent the thin plate substrate from adhering to the grinding surface, thereby making it easy to take out the thin plate substrate after processing (1) or (2) A method for grinding a thin plate substrate as described in 1.
(4) A thin plate substrate grinding apparatus having a warped cross-sectional shape, and when grinding with a grindstone from both sides of the thin plate substrate, a coolant is applied from the entire surface of the grindstone through the open pores of the grindstone. The slurry having a chemical polishing agent, or a mixture thereof is supplied between the thin plate substrate and the grindstone, and hydrostatic pressure is applied to both surfaces of the thin plate substrate to maintain the shape having the warp, while the thin plate substrate having the warp is maintained . A thin plate substrate grinding apparatus characterized in that shape correction is performed by grinding upper and lower protrusions with a grindstone from both sides .
(5) The grinding stone, Ken consists Kezutogi grains and bond material, and a number of consisting pillar grindstone columns arranged in parallel having an axis L in the depth direction of the grinding surfaces, integral with the abrasive stone columns A grinding wheel matrix to be formed, wherein both the grinding wheel column and the grinding wheel matrix are made of abrasive grains and a binder, and the abrasive grains in the grinding wheel column are made of a material having higher hardness than the abrasive grains of the grinding wheel matrix. The thin plate substrate grinding apparatus according to (4).

<Action>
According to the present invention (1), when grinding with a grindstone from both sides of the plate substrate, a slurry having a coolant, a chemical polishing agent, or the like, from the entire surface of the grindstone through the open pores of the grindstone, or these Shape correction can be performed by supplying the mixture between the thin plate substrate and the grindstone, and grinding while holding the shape having warpage by applying hydrostatic pressure to both surfaces of the thin plate substrate. In conventional double-side grinding, as described in the specification of Japanese Patent Application Laid-Open No. 2009-16842, the cooling liquid or the like generally comes out from the center of the grinding tool and is conveyed to the grinding teeth by centrifugal force. Therefore, the portion where the grindstone and the substrate come into contact with each other usually makes it difficult to supply the cooling medium, and the thin plate substrate has a shape as shown in FIG. On the other hand, the grindstone used in the present invention can supply the cooling medium through the open pores, so that the difference in resistance between the contacted surface and the inner surface of the substrate can be made so small that it can be ignored. Can be supplied. In the present invention, open pores refer to pores through which water passes, as described in, for example, Porous Materials: Process technology and applications (Materials Technology Series).

According to the present invention (2), the grindstone is a porous body having an open porosity of 20 to 60% by volume, and therefore exhibits the following effects.
-By making the grindstone porous, it is possible to control the distance between the grindstone and the grinding surface of the workpiece by directly discharging a coolant such as water.
-Cooling and polishing of the grinding wheel can be performed by directly discharging a coolant such as water from the grinding wheel.

  According to the present invention (3), by discharging liquid or gas directly from the back of the grinding surface of the grindstone, it is possible to prevent the workpiece from adhering to the grinding surface and to easily take out the workpiece after processing. it can.

According to this invention (4), since the said grindstone is attached to both surfaces of a workpiece, double-sided processing is possible and the apparatus used for the grinding method as described in (1) is realizable.

  According to the present invention (5), the grindstone column is composed of abrasive grains and a binder for grinding a workpiece, and has a number of columns arranged in parallel and having an axis L in the depth direction of the surface to be ground. Therefore, even if the abrasive grains exposed on the grinding surface fall off, the abrasive grains buried in the lower layer are exposed, so that the grinding can be continuously performed while maintaining the processing speed.

  The grindstone column and the grindstone matrix are both composed of abrasive grains and a binder, and the abrasive grains in the grindstone column are harder than the grindstone of the grindstone matrix. Since the grindstone matrix sinks from the grindstone column due to the difference in the rate, the abrasive grains of the grindstone column can always be exposed, and a hard and brittle workpiece such as an electronic material can be ground.

Moreover, the grinding apparatus which has the following effect can be provided by using the said grindstone.
・ Vacuum can be drawn from the grinding wheel surface.
・ A mechanism that allows water or other coolant to be removed from the grindstone.
・ The grinding wheel dressing can be omitted.
・ Rough grinding, lapping grinding, and finish polishing can be performed simultaneously.
・ Double-sided processing is possible.
-Prevents clogging of the grindstone and enables continuous processing.
-Prevents the work piece from adhering to the grinding surface and makes it easier to take out the work piece after machining.

  According to the present invention, for example, in order to remove obstacles such as exposure processing and epitaxial processing, the thin plate substrate cross-sectional shape can be corrected to a flat ideal shape, and the thin plate substrate grinding method and the grinding process used therefor It is possible to provide a device, and there are significant industrially useful effects.

It is a figure which illustrates the thin-plate board | substrate of an ideal shape. It is a figure which illustrates the cross-sectional shape of the thin board | substrate which has curvature. It is a figure which illustrates embodiment of the grinding method of the thin-plate board | substrate of this invention. 1 is a plan view illustrating an embodiment of a thin plate substrate grinding apparatus of the present invention. It is sectional drawing which illustrates embodiment of the grinding processing apparatus of the thin-plate board | substrate of this invention. It is the top view and sectional view which illustrate the embodiment of the grindstone used for the present invention. It is a schematic diagram which shows the structure of the grindstone pillar used for this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. FIG. 3 is a diagram illustrating an embodiment of the thin plate substrate grinding method of the present invention.

  As described above, in order to remove obstacles such as exposure processing and epitaxial processing, it is necessary to grind and remove portions 21, 22, and 23 in FIG. Many such materials are hard and difficult to process, and it is necessary to use superabrasive grains such as diamond to improve the processing speed. However, in the normal grinding wheel grinding method, it is necessary to press the grinding stone in order to apply sufficient grinding force to the abrasive grains. Even with the substrate as shown in FIG. After processing, the shape again returns to the shape shown in FIG. 2 by the elastic force. Further, if each side is processed, the surface roughness and surface defects are different between the processed surface and the surface before processing, which may cause warpage and even increase warpage.

  In order to prevent this, a method in which both surfaces are simultaneously processed with floating abrasive grains is generally used, but the processing speed is extremely slow due to processing with floating abrasive grains. The present invention is a processing method in which a substrate is held in a substantially original shape by hydrostatic pressure, and grinding is performed on portions 21, 22, and 23 with a grinding wheel, and both sides can be processed regardless of the processing of the grinding wheel. Because the substrate is held by water pressure, it is possible to process the original shape while maintaining the shape of the original grinding wheel 21, 22, 23. Because it is a grinding wheel, it is possible to process at a speed that is dozens of times faster than floating abrasives (about 20 times for sapphire and aluminum nitride, and about 10 times for silicon).

  FIG. 4 is a plan view illustrating an embodiment of a thin plate substrate grinding apparatus of the present invention. As shown in FIG. 4, the carrier 41 is placed on the grindstone 31. The carrier has a hole portion 42, and the workpiece 30 is put into the hole 42. A grindstone similar to 31 is present on both sides of the carrier. The carrier has gear teeth 43 on the outer periphery thereof, and the carrier rotates by contacting the outer peripheral teeth 44 outside the grindstone and the inner diameter teeth 45 of the grindstone. 44 and 45 and 31 of a grindstone consist of an independent separate member. As a result, the material to be ground rotates on the grindstone by repeating revolution and rotation. Here, the grindstone 31 is a porous grindstone and can be supplied with water.

  FIG. 5 shows a cross-sectional view of the material to be ground shown in FIG. 4 after installation. Although 31 is the grindstone of FIG. 4, 31a and 31b are each upper grindstone and lower grindstone. The grindstone is a porous body, and water is discharged through the open pores, and the workpiece 30 is supported by the water pressure while maintaining the shape. As a result, the portions 21, 22, and 23 described in FIG. 3 can be ground.

  FIG. 6 is a plan view and a cross-sectional view illustrating an embodiment of the grindstone of the present invention, FIG. 6 (a) is a plan view, and FIG. 6 (b) is a cross-sectional view taken along line AA of FIG. 6 (a). . FIG. 7 is a schematic diagram showing the structure of a grindstone column used in the present invention. (a) shows before firing, and (b) shows after firing. After firing, the binder melts and wraps the abrasive grains to bond the abrasive grains together. 6 and 7, 51 is a grindstone column, 52 is a grindstone matrix, 53 is an abrasive grain, 54 is a binder, 55 is an open hole, L is a grindstone column axis, D is a grindstone column diameter, and S is a grindstone column. Indicates the interval.

  The grindstone used in the present invention may be a conventional porous grindstone, but is particularly preferably a grindstone with high performance for double-side grinding, which is a grindstone for grinding a workpiece, and abrasive grains 53 for grinding the workpiece. A grindstone column 51 composed of a plurality of columns, which is made of a binding material 54 and is arranged in parallel with an axis L in the depth direction of the surface to be ground and polished, and a grindstone matrix 52 formed integrally with the grindstone column 51. It is preferable to have. The workpiece to which the present invention is directed refers to a thin substrate having a thickness of 10 to 2000 μm made of any of silicon, silicon carbide, aluminum nitride, alumina, and sapphire.

  The grindstone used in the present invention is composed of abrasive grains 53 and a binder 54 for grinding a workpiece, and a grindstone column 51 comprising a number of columns arranged in parallel with an axis L in the depth direction of the surface to be ground. Therefore, even if the abrasive grains 53 exposed on the grinding surface fall off, the abrasive grains 53 buried in the lower layer are exposed, so that the grinding can be continuously performed while maintaining the processing speed. The bonding material 54 is mixed as shown in FIG. 7, but after firing, a connecting column is formed so that the bonding material 54 melts and wraps the abrasive grains 53. In addition, the cross-sectional shape of the grindstone column 51 is not limited to the column as shown in FIG.

  Further, the diameter D of the grindstone column is 3 to 100 times the average particle diameter of the abrasive grains 53, and the interval S between the adjacent grindstone columns 51 is 10 to 1000 times the diameter D of the grindstone column 1. Is preferred. The diameter D of the grindstone column 51 is 3 to 100 times the average particle diameter of the abrasive grains 3, whereby 3 to 100 abrasive grains are arranged in the cross section of the grindstone column 1, and the interval S between the adjacent grindstone columns 51 is By being 10 to 1000 times the diameter D of the grindstone column 1, it is possible to prevent a reduction in processing speed by reducing the area ratio for grinding and polishing as compared with the conventional case. The arrangement of the grindstone pillars 1 may be an arrangement that forms a geometric pattern including a triangle, a quadrangle, or a polygon as shown in FIG. 6, or may be arranged randomly.

The abrasive grains 53 are made of diamond, and the average particle diameter is 0.1 to 300 μm. However, instead of diamond, cubic boron nitride (CBN) abrasive grains or CBN may be used, a mixture of diamond and CBN may be used, and silicon carbide SiC or GC. , Mullite (3AL ₂ O ₃ -2SiO ₂ ), or molten alumina AL ₂ O _3, that is, WA alone or a mixture thereof may be used. Vitrified bonds are used as the bonding material 54 constituting the grindstone 31, but various bonding materials such as resinoid bonds, metal bonds, and electrodeposition bonds are used as the respective bonding materials 54 in addition to vitrified bonds. Can do. The average grain size of the abrasive grains 53 is an average value of equivalent circle diameters of the same cross-sectional area when the cross section of the abrasive grains 53 is not circular.

  The grindstone column 51 and the grindstone matrix 52 are preferably composed of abrasive grains 53 and a binder 54, and the abrasive grains 53 in the grindstone column 51 are preferably higher in hardness than the abrasive grains 53 of the grindstone matrix. The grindstone column 51 and the grindstone matrix 52 are both composed of abrasive grains 53 and a binder 54, and the grindstone 53 in the grindstone column 51 is made of a material having higher hardness than the abrasive grains 53 of the grindstone matrix 2, so that the grindstone matrix 52 is Wear is greater than that of the grindstone column 51, the grindstone matrix 52 sinks, and the grindstone column 51 protrudes. In addition, since the grindstone matrix 52 sinks from the grindstone column 51 due to the difference in Young's modulus, the abrasive grains can always be exposed, and a hard and brittle workpiece such as an electronic material can be ground. Can do.

  The grindstone column 51 and the grindstone matrix 52 are preferably porous bodies having an open porosity of 20 to 60% by volume. The reason for limiting the lower limit (20%) of the open porosity is that in the porous body below this, the pores 55 are mainly open pores, but the through pores (the pores leading from one side of the grindstone to the opposite surface thereof, the pore diameter and the thickness of the grindstone) Although it varies depending on the thickness, 20% is almost the limit for the open pore diameter of about 1 to 1000 microns with the thickness within the range of the commonly used grinding wheel. The reason for limiting the upper limit (60%) of the open porosity is that the mixed powder of the abrasive grains 53 and the binder 54 is at most about 60%, and then sintering. Therefore, it is always 60% or less, so this is the upper limit. The grindstone column 51 and the grindstone matrix 52 are the porous bodies having an open porosity of 20 to 60% by volume, thereby providing the following effects.

-By making the grinding wheel porous, it is possible to control the distance between the grinding surface of the grinding wheel and the workpiece to be ground and to eliminate unnecessary adhesion of the workpiece to the grinding stone by directly issuing a coolant such as water. To.
・ Cooling of grinding wheel processing can be performed by directly discharging a coolant such as water from the grinding wheel.
Further, a coolant, a slurry having a chemical abrasive, or a mixture thereof can be supplied and supplied between the workpiece and the grindstone through the open pores 55.

  Also, workpieces such as silicon substrates are getting thinner and thinner, but the limitation of single-sided processing is that the difference between the processed surface and the unprocessed surface appears, and the thin one is warped and cannot be used. By processing it on both sides, both sides change in the same way, so warpage can be eliminated.

  However, when both sides are processed with a conventional grinding machine, a coolant such as water is put in, so when the workpiece is taken out by removing the grindstone after machining with the surface tension, it remains attached to the upper and lower or left and right grindstones. End up. There was a problem that it took one more step to peel it off, and if it failed to peel it, the thinned one would break.

  Therefore, the grindstone which is a preferred embodiment of the present invention, when a grindstone is placed up and down or left and right and a workpiece is sandwiched between them, fluid (liquid such as water or gas such as air) is taken out of the grindstone and processed By preventing the object from adhering to the grindstone, facilitating removal of the workpiece, and facilitating removal, it is possible to perform double-side processing.

1 Thin board 1 'thin board (having warpage)
21 Grinding point 22 Grinding point 23 Grinding point 30 Material to be ground (thin plate substrate)
31 grindstone 31a upper grindstone 31b lower grindstone 41 carrier 42 hole 43 gear teeth 44 outer peripheral teeth 45 inner diameter teeth 51 grindstone column 52 grindstone matrix 53 abrasive grains 54 binder 55 open hole L grindstone column axis D grindstone column diameter S Grinding wheel spacing

Claims (5)

A method of grinding a thin plate substrate having a warped cross-sectional shape,
When grinding with a grindstone from both sides of the thin plate substrate, a coolant, a slurry containing a chemical abrasive, or a mixture thereof is passed between the thin plate substrate and the grindstone from the entire surface of the grindstone through the open pores of the grindstone. The shape correction is performed by grinding the upper and lower protruding portions of the warped thin plate substrate with a grindstone from both sides while supplying the pressure between the both sides of the thin plate substrate and holding the warped shape by applying hydrostatic pressure. A method for grinding a thin plate substrate.   The method for grinding a thin plate substrate according to claim 1, wherein the grindstone is a porous body having an open porosity of 20 to 60% by volume.   3. The thin plate according to claim 1, wherein liquid or gas is directly discharged from a back portion of the grinding surface of the grindstone to prevent the thin plate substrate from adhering to the grinding surface and to facilitate removal of the thin plate substrate after processing. Substrate grinding method. A thin plate substrate grinding apparatus having a warped cross-sectional shape, and when grinding using a grindstone from both sides of the thin plate substrate, the coolant, chemical polishing from the entire surface of the grindstone through the open pores of the grindstone A slurry having an agent, or a mixture thereof is supplied between the thin plate substrate and the grindstone, and hydrostatic pressure is applied to both surfaces of the thin plate substrate to maintain the shape having the warp, while the upper and lower protrusions of the thin plate substrate having the warp A thin plate substrate grinding apparatus characterized in that shape correction is performed by grinding a portion with a grindstone from both sides . The wheels, Ken consists Kezutogi grains and bond material, and a number of consisting pillar grindstone columns arranged in parallel having an axis L in the depth direction of the grinding faces are formed integrally with the abrasive stone columns A grindstone matrix, wherein both the grindstone column and the grindstone matrix are made of abrasive grains and a binder, and the abrasive grains in the grindstone column are made of a material having higher hardness than the abrasive grains of the grindstone matrix. 5. The thin plate substrate grinding apparatus according to 4.

Images