Grinding method for semiconductor crystals and grinding stone used in said grinding method

Abstract

The present invention aims to provide a grinding method for semiconductor crystals that can achieve higher grinding accuracy by more precisely and in detail managing plastic deformation as a plastic deformation mechanism on the end face of a semiconductor crystal ingot or the surface of a wafer, and a grinding wheel for use in said grinding method. [Solution] In the grinding method for a Si wafer 100, a plastic deformation region 100A is formed on the surface of the wafer 100 by a temperature rise caused by friction between the grinding wheel 53 and the grinding force applied to the wafer 100 against the grinding wheel 53 via the spindle 51, and the surface of the plastic deformation region 100A is subjected to functional polishing by adding a functional additive to the grinding wheel 53, while the plastic deformation region 100A is ground with the grinding wheel 53.

Description

[Technical Field]

[0001] The present invention relates to a grinding method for semiconductor crystals, which grinds the end face of a semiconductor crystal ingot ground into a cylindrical shape or the surface of a wafer sliced ​​from the semiconductor crystal ingot, and to a grinding wheel used in the grinding method. [Background technology]

[0002] Conventionally, as a grinding method for this type of semiconductor crystal wafer, as shown in Patent Document 1 below, a method developed by the present inventor forms a plastic deformation region on the surface of the wafer facing the platen (grinding table) due to a temperature rise caused by friction between the platen and the diamond abrasive grains, based on (1) the grain size of the diamond abrasive grains (diamond grinding wheel) used for grinding, (2) the pressing force with which the wafer is pressed against the platen via the spindle, and (3) the speed at which the spindle advances relative to the platen. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7285507 Summary of the Invention [Problem to be solved by the invention]

[0004] As a result of intensive research into the plastic deformation region in more detail, the inventors of the present application have discovered that higher grinding accuracy can be achieved by more precisely controlling the plastic deformation mechanism.

[0005] The present invention is based on this finding, and aims to provide a grinding method for semiconductor crystals that can achieve higher grinding accuracy by more precisely and in detail managing plastic deformation as a plastic deformation mechanism on the end face of a semiconductor crystal ingot or the surface of a wafer, and a grinding wheel for use in said grinding method. [Means for solving the problem]

[0006] The semiconductor crystal grinding method of the first invention is a semiconductor crystal grinding method for grinding an end face of a semiconductor crystal ingot ground into a cylindrical shape or a surface of a wafer sliced ​​from the semiconductor crystal ingot, A grinding wheel is provided on a grinding machine for grinding, and a pressing force is applied to press the semiconductor crystal ingot or the wafer against the grinding wheel via a support base, so that a temperature rise occurs on the end face of the semiconductor crystal ingot facing the grinding machine or the surface of the wafer facing the grinding machine due to friction between the grinding wheel and the grinding wheel, and A grinding method for a semiconductor crystal includes grinding the plastically deformed region with a grindstone while functionally polishing the surface of the plastically deformed region by adding a functional additive to the grindstone, In addition to cerium oxide The method is characterized in that potassium permanganate is added to form an oxide film on the surface of the plastic deformation region, and at the same time, the oxide film is removed with the grinding stone, thereby grinding the plastic deformation region with the grinding stone.

[0007] According to the semiconductor crystal grinding method of the first invention, as a result of intensive research into the plastic deformation region in more detail, it has been discovered that various states can exist on the surface of the plastic deformation region.

[0008] Based on this knowledge, in order to integrate the functional polishing of the plastically deformed region with the grinding process, a surface treatment is carried out by adding a functional additive to the grinding stone, and the plastically deformed region is then ground.

[0009] Thus, according to the semiconductor crystal grinding method of the first aspect of the invention, higher grinding accuracy can be achieved by controlling the plastic deformation mechanism more precisely and in detail.

[0010] Furthermore, according to the semiconductor crystal grinding method of the first invention, as a result of intensive research that analyzed the plastic deformation region in more detail, it was discovered that an oxide film formed by oxidizing the semiconductor crystal is constantly formed on the surface of the plastic deformation region.

[0011] Based on this knowledge, in order to integrate the removal of the oxide film of the semiconductor crystal and the grinding of the plastic deformation region as a functional polishing, potassium permanganate is added to the grinding wheel as a functional additive, which generates an oxide film on the surface of the plastic deformation region, and at the same time, the oxide film is removed with the grinding wheel while the plastic deformation region is ground.

[0012] Thus, according to the semiconductor crystal grinding method of the first aspect of the invention, higher grinding accuracy can be achieved by controlling the plastic deformation mechanism more precisely and in detail.

[0013] The semiconductor crystal grinding method of the second invention is the first invention, The method is characterized in that the plastic brittle intermediate layer present on the opposite side of the grinding machine side of the plastic deformation region is used as a buffer region, and only the surface of the plastic deformation region is ground so as to leave the entire plastic brittle intermediate layer intact.

[0014] According to the second invention of the semiconductor crystal grinding method, as a result of intensive research that analyzed the plastic deformation region in more detail, it was discovered that there is a plastic brittle intermediate layer on the opposite side (crystal side) of the plastic deformation region from the grinding machine side, and that by using this as a buffer region, grinding that does not enter this buffer region leads to high-quality processing that does not cause cracks to propagate into the crystal.

[0015] Based on this knowledge, when grinding the plastically deformed region using a grinding wheel containing potassium permanganate, the generation and removal of the oxide film of the semiconductor crystal and the grinding of the plastically deformed region are integrated, and only the surface of the plastically deformed region is ground (the plastically brittle intermediate layer is not ground).

[0016] Thus, according to the semiconductor crystal grinding method of the second invention, higher grinding accuracy can be achieved by controlling the plastic deformation mechanism more precisely and in detail.

[0017] The grinding stone of the third invention is a grinding stone used in the grinding method of semiconductor crystal of either the first or second invention, The material composition contains more than 0% and 10% or less of potassium permanganate.

[0018] According to the grinding wheel of the third invention, by including potassium permanganate in the material composition in a range of more than 0% and not more than 10%, it is possible to perform the grinding process of the formation and removal of an oxide film and the grinding of the plastic deformation region in one integrated process.

[0019] In this way, with the grinding stone of the third invention, higher grinding accuracy can actually be achieved by controlling the plastic deformation mechanism more precisely and in detail.

[0020] The grinding stone of the fourth invention is the third invention, The material composition is characterized in that it contains either calcium carbonate or calcium hydroxide, or both, in place of the potassium permanganate.

[0021] According to the grinding stone of the fourth invention, by replacing potassium permanganate as part of the material composition with calcium carbonate and / or calcium hydroxide, the pH value of the aqueous solution used as the processing fluid can be controlled to make it alkaline enough for processing.

[0022] In this way, with the grinding wheel of the fourth invention, higher grinding accuracy can actually be achieved by more precisely and in detail managing the plastic deformation mechanism, including the processing conditions. [Brief explanation of the drawings]

[0023] [Figure 1]1 is a flowchart showing the entire manufacturing process of a Si wafer (semiconductor crystal wafer) according to the present embodiment. [Figure 2] 2 is an explanatory diagram showing the contents of a first surface processing step and a second surface processing step in the manufacturing process of the Si wafer of FIG. 1. [Figure 3] 2 is an explanatory diagram showing the contents of a first surface processing step and a second surface processing step in the manufacturing method of the Si wafer of FIG. 1. [Figure 4] 2A to 2C are schematic diagrams showing the processed state in the first surface processing step and the second surface processing step in the Si wafer manufacturing method of FIG. 1. [Figure 5A] Schematic diagrams showing the processed state in the first surface processing step and the second surface processing step in a conventional Si wafer manufacturing method. [Figure 5B] 2A to 2C are schematic diagrams showing the processed state in the first surface processing step and the second surface processing step in the Si wafer manufacturing method of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0024] As shown in FIG. 1, in this embodiment, the method for manufacturing a Si wafer, which is a semiconductor crystal wafer, is a method for obtaining a Si wafer by removing waviness from one surface of a wafer sliced ​​from a Si ingot that has been ground into a cylindrical shape, and includes a groove processing step (STEP 100 / FIG. 1), a cutting step (STEP 110 / FIG. 1), a first surface processing step (STEP 120 / FIG. 1), and a second surface processing step (STEP 130 / FIG. 1).

[0025] The processing steps in STEP 120, the first surface processing step, and STEP 130, the second surface processing step, i.e., mechanical polishing (high-precision grinding), correspond to the semiconductor crystal wafer grinding method of the present invention (the grinding process and grinding process characteristic of the present invention). Meanwhile, the groove processing step in STEP 100 and the cutting step in STEP 110 are described in Patent Nos. 7104909 and 7100864, ​​etc., by the applicant of the present application, so detailed explanations will be omitted here and only an outline will be provided below.

[0026] First, in the groove processing step of STEP 100, a cylindrical Si ingot is prepared by determining the crystal orientation and performing cylindrical grinding on a pre-crystallized Si crystal in the ingot processing step.

[0027] Then, in the groove processing step of STEP 100, a plurality of grooves are formed around the entire side surface of the Si ingot.

[0028] Specifically, in the groove processing step of STEP 100, groove processing drum grinding wheels, each having a convex portion corresponding to the groove formed on its side, are rotated on parallel rotation axes and pressed against a Si ingot to form a groove.

[0029] It is desirable to perform damage-free mirror finishing on the Si ingot (especially the grooves) obtained in the groove processing step using a chemical processing method.

[0030] Next, in the cutting step of STEP 110, the Si ingot is cut into slices by a plurality of wires arranged in the plurality of grooves formed in the groove processing step, thereby obtaining Si wafers 100.

[0031] Specifically, in the cutting process, the wire saw device, which is a cutting processing device, has a wire saw section that aligns multiple wires with the multiple grooves formed in the groove processing process and moves the wires forward while circulating, thereby cutting the Si ingot into slices.

[0032] Next, as shown in FIG. 2, in the first surface processing step 120, one surface 110 of the cut surfaces is used as a support surface, and the other surface 120 is subjected to mechanical polishing (high-precision grinding).

[0033] Specifically, in the first surface processing step, grinding is performed by a mechanical polishing device 50 (ultra-high synthesis, high precision grinding device) that performs mechanical polishing.

[0034] 3, the mechanical polishing device 50 includes a spindle 51 and a platen 52, which is a grinding table, and stick-shaped grindstones 53 are radially arranged on the platen 52. More specifically, the stick-shaped grindstones 53 are fixed in recesses (not shown) formed in the platen 52 so that the lower sides of the stick-shaped grindstones 53 are partially fitted into the recesses.

[0035] The grindstone 53 is, for example, a diamond grindstone suitable for grinding Si wafers, and contains cerium oxide in an amount of from 0% to 10% inclusive as a material composition for removing oxide films (described later). It also contains potassium permanganate in an amount of from 0% to 10% inclusive as a material composition. The total amount of cerium oxide and potassium permanganate in the material composition is from 0% to 20% inclusive, but preferably from 0% to 15% inclusive.

[0036] Furthermore, it is preferable that the grinding wheel 53 contains either calcium carbonate or calcium hydroxide, or both, in place of potassium permanganate as part of its material composition, thereby controlling the pH value of the aqueous solution used as the machining fluid and making it alkaline enough for machining.

[0037] First, one surface 110 is set as the upper surface and supported by adsorption to a vacuum porous chuck 54, which is an adsorption plate of a spindle 51, which is a support stand that supports the wafer, and the other surface 120 is set as the lower surface and is ground by a grinding wheel 53.

[0038] At this time, the spindle 51 and the platen 52 are rotated by a drive unit (not shown), and the spindle 51 is pressed against the platen 52 by a compressor (not shown) or the like, thereby grinding the other surface 120 .

[0039] After the grinding process, the grindstone 53 may be dressed using a dresser or the like.

[0040] Furthermore, the mechanical polishing device 50 may have a functional water supply pipe so that multiple types of functional water can be used during processing, if necessary.

[0041] Next, in the second surface processing step of STEP 130, the other surface 120 that has been subjected to high-precision grinding in the first surface processing step is used as the upper surface, and high-precision grinding similar to that in the first surface processing step is performed on the one surface 110.

[0042] That is, the other surface 120 is placed on the upper surface and attached to a vacuum porous chuck 54 which is an attachment plate of the spindle 51, and the one surface 110 is placed on the lower surface and ground by a grindstone 53.

[0043] In this case, too, dressing may be performed by pressing a dresser or the like against the grindstone 53, if necessary.

[0044] In this embodiment, in the mechanical polishing (high-precision grinding) process of the first surface processing step in STEP 120 and the second surface processing step in STEP 130, as shown in particular in FIG. 4, a plastic deformation region 100A is formed on the surface of the wafer 100 by a temperature rise caused by friction between the grinding wheel 53 and the wafer 100 due to the grinding wheel 53 and the pressing force applied to press the wafer 100 against the grinding wheel 53 via the spindle 51, and by adding potassium permanganate to the grinding wheel 53, an oxide film 100B is generated on the surface of the plastic deformation region 100A, and the generated oxide film 100B is removed by the grinding wheel 53 by adding cerium oxide to the grinding wheel 53, while the plastic deformation region 100A is ground using the grinding wheel 53.

[0045] At this time, within the plastic deformation region 100A, there is a plastic brittle intermediate layer 100C present on the side opposite the platen 52, and this plastic brittle intermediate layer 100C is used as a buffer region, and only the surface of the plastic deformation region 100A is ground with a grinding wheel 53 so as to leave the entire plastic brittle intermediate layer 100C remaining.

[0046] According to the above configuration, as shown in FIG. 5A, in the case of a normal grinding wheel 53' that does not contain cerium oxide, the oxide film 100B cannot be removed and the wafer 100 is not ground. However, as shown in FIG. 5B, in the case of the grinding wheel 53 of this embodiment that contains cerium oxide, the oxide film 100B is removed (as shown by the arrow in the figure relatively due to the wafer 100 being pressed toward the platen 52), and the grinding wheel 53 reaches the plastic deformation region 100A, and only the surface of the plastic deformation region 100A is ground.

[0047] In this way, by using the plastic brittle intermediate layer 100C as a buffer region and performing grinding that does not enter this buffer region, high-quality processing can be achieved that does not cause cracks to propagate into the crystal of the wafer 100.

[0048] That is, in the plastically deformed region 100A of the wafer 100 from which the oxide film 100B has been removed, the grinding efficiency by the grindstone 53 is significantly improved, unlike surface polishing in a state without plastic deformation, and a highly flat mirror finish can be achieved in one go. That is, the complicated manufacturing process, such as multiple lapping steps (first to fourth), can be greatly simplified.

[0049] It is important that the speed at which the spindle 51 advances relative to the grindstone 53 (platen 52) does not exceed the depth of the plastic deformation region 100A.

[0050] Thus, according to the grinding method for Si wafers, which are semiconductor crystal wafers, of this embodiment, it is possible to actually provide a grinding method for semiconductor crystal wafers that can achieve higher grinding accuracy by more precisely and in detail managing plastic deformation, which has been conventionally shunned, as a plastic deformation mechanism on the wafer surface.

[0051] In this embodiment, a method for grinding a Si wafer has been described in which a Si wafer is manufactured from a Si ingot. However, the semiconductor crystal is not limited to Si, and may be gallium phosphate, indium phosphide, silicon carbide (SiC), or other compound semiconductors.

[0052] Furthermore, in this embodiment, the case where the grooves are formed in the groove processing step and then the cutting is performed in the cutting step has been described, but the groove processing step may be omitted as appropriate.

[0053] In addition, in this embodiment, the grinding wheel 53 containing cerium oxide and potassium permanganate (which may partially contain either or both of calcium carbonate and calcium hydroxide) is described as being stick-shaped, but the shape of the grinding wheel 53 is not limited to this, and various shapes such as a cup shape (cup wheel shape) can be adopted as long as they are suitable for the purpose of grinding the end surface of the wafer 100 or ingot.

[0054] Furthermore, in this embodiment, the functional polishing of the surface of the plastic deformation region is described as an example of forming and removing an oxide film using potassium permanganate and cerium oxide as functional additives, and a case where CMP (chemical mechanical polishing) is performed in conjunction with grinding processing, but the functional polishing (surface treatment) and the functional additives used therefor are not limited to this. [Explanation of symbols]

[0055] 50...mechanical polishing device (ultra-high synthesis high precision grinding processing device), 51...spindle (support base), 52...platen (grinding surface plate), 53...grinding stone, 54...vacuum porous chuck (suction plate), 100...Si wafer (semiconductor crystal wafer), 110...one side, 120...other side.

Claims

1. A semiconductor crystal grinding method for grinding an end face of a semiconductor crystal ingot ground into a cylindrical shape or a surface of a wafer sliced ​​from the semiconductor crystal ingot, comprising: A grinding wheel is provided on a grinding machine for grinding, and a pressing force is applied to press the semiconductor crystal ingot or the wafer against the grinding wheel via a support base, so that a temperature rise occurs on the end face of the semiconductor crystal ingot facing the grinding machine or the surface of the wafer facing the grinding machine due to friction between the grinding wheel and the grinding wheel, and A grinding method for a semiconductor crystal includes grinding the plastically deformed region with a grindstone while functionally polishing the surface of the plastically deformed region by adding a functional additive to the grindstone, A method for grinding a semiconductor crystal, characterized in that an oxide film is formed on the surface of the plastic deformation region by adding potassium permanganate in addition to cerium oxide, while simultaneously removing the oxide film with the grindstone, thereby grinding the plastic deformation region with the grindstone.

2. 2. The method for grinding a semiconductor crystal according to claim 1, A method for grinding semiconductor crystals, characterized in that a plastic brittle intermediate layer present on the side opposite the grinding machine side of the plastic deformation region is used as a buffer region, and only the surface of the plastic deformation region is ground so as to leave the entire plastic brittle intermediate layer.

3. 3. A grinding stone for use in the semiconductor crystal grinding method according to claim 1 or 2, A grinding wheel characterized in that the material composition contains more than 0% and 10% or less of potassium permanganate.

4. The grinding stone according to claim 3, A grinding wheel characterized in that the potassium permanganate is replaced as a part of the material composition with calcium carbonate and / or calcium hydroxide.

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