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

Abstract

An object of the present invention is 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 of an end face of a semiconductor crystal ingot or a wafer surface, and a grinding wheel for use in said grinding method. [Solution] In the grinding method for Si wafer 100, a plastic deformation region 100A is formed on the surface of wafer 100 by a temperature rise caused by friction between grinding wheel 53 and wafer 100, using the grinding wheel 53 and the pressing force applied to wafer 100 against grinding wheel 53 via spindle 51. At the same time, functional polishing is performed on the surface of plastic deformation region 100A by incorporating functional additives into grinding wheel 53, while the plastic deformation region 100A is ground with grinding wheel 53.

Description

[Technical field]

[0001] The present invention relates to a method for grinding semiconductor crystals, which grinds the end face of a semiconductor crystal ingot ground into a cylindrical shape or the surface of a wafer cut into slices 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 has been known in which the inventor of the present application has developed a method in which a plastic deformation region is formed on the platen (grinding table) side surface of the wafer by 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] Here, the inventors of the present application conducted intensive research into the plastic deformation region in more detail and discovered that higher grinding accuracy can be achieved by more precisely controlling the plastic deformation mechanism.

[0005] The present invention is based on such findings, 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 of an end face of a semiconductor crystal ingot or a wafer surface, and a grinding wheel for use in said grinding method. [Means for solving the problem]

[0006] The first invention relates to a method for grinding a semiconductor crystal, which grinds an end face of a semiconductor crystal ingot ground into a cylindrical shape or a surface of a wafer cut into a slice from the semiconductor crystal ingot, A grinding wheel is provided on a grinding machine for grinding, and a pressing force is applied to the semiconductor crystal ingot or the wafer via a support base, so that a plastic deformation region is formed on the end face of the semiconductor crystal ingot on the grinding machine side or on the surface of the wafer on the grinding machine side due to a temperature rise caused by friction between the grinding wheel and the end face. The surface of the plastic deformation region is subjected to functional polishing by adding a functional additive to the grindstone, while grinding the plastic deformation region with the grindstone. As a method for grinding semiconductor crystals, The method is characterized in that the plastic deformation region is ground with the grindstone while removing an oxide film formed on the surface of the plastic deformation region with the grindstone by making the grindstone contain cerium oxide.

[0007] According to the semiconductor crystal grinding method of the first invention, as a result of intensive research into a more detailed analysis of the plastic deformation region, 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 and grinding of the plastically deformed region, a surface treatment is performed by adding a functional additive to a grinding stone, and the plastically deformed region is then ground.

[0009] In this way, according to the semiconductor crystal grinding method of the first aspect of the invention, the plastic deformation mechanism can be controlled more precisely and in detail, thereby achieving higher grinding accuracy.

[0011] Also, No. 1 According to the semiconductor crystal grinding method of the present invention, as a result of intensive research into 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.

[0012] Based on this knowledge, in order to integrate the removal of the oxide film from the semiconductor crystal and the grinding of the plastic deformation region as functional polishing, cerium oxide is added to the grinding wheel as a functional additive, and the plastic deformation region is ground.

[0013] Thus, the 1 According to the semiconductor crystal grinding method of the present invention, the plastic deformation mechanism can be controlled more precisely and in more detail, thereby achieving higher grinding accuracy.

[0014] No. 2 The semiconductor crystal grinding method of the present invention is 1 In the invention, The present invention is characterized in that, within the plastic deformation region, a plastic brittle intermediate layer present on the side opposite the grinding machine 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.

[0015] No. 2 According to the invention's method for grinding semiconductor crystals, 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 of the plastic deformation region to the grinding machine side (the crystal 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.

[0016] Based on this knowledge, when grinding the plastic deformation region by using a grinding wheel containing cerium oxide so as to integrate the removal of the oxide film of the semiconductor crystal and the grinding of the plastic deformation region, only the surface of the plastic deformation region is ground (the plastic brittle intermediate layer is not ground).

[0017] In this way, 2 According to the semiconductor crystal grinding method of the present invention, the plastic deformation mechanism can be controlled more precisely and in more detail, thereby achieving higher grinding accuracy.

[0018] No. 3 The grinding wheel of the present invention is or secondA grinding wheel for use in any one of the semiconductor crystal grinding methods of the present invention, comprising: It is characterized by containing cerium oxide in the material composition by more than 0% and not more than 10%.

[0019] No. 3 According to the grinding wheel of the invention, by containing cerium oxide in the material composition at a content of more than 0% and not more than 10%, it is possible to actually perform the removal of the oxide film and the grinding of the plastic deformation area as one integrated process.

[0020] Thus, the 3 According to the grinding wheel of the invention, the plastic deformation mechanism can be controlled more precisely and in detail, thereby making it possible to actually achieve higher grinding accuracy. [Brief description of the drawings]

[0021] [Figure 1] 1 is a flowchart showing the entire manufacturing process of a Si wafer (semiconductor crystal wafer) according to the present embodiment. [Diagram 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 in FIG. 1. [Diagram 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 in FIG. 1. [Figure 4] 2A to 2C are schematic diagrams showing a processed state in a first-side processing step and a second-side processing step in the manufacturing method of the Si wafer in FIG. 1. [Figure 5A] Schematic diagram showing the processed state in a first-side processing step and a second-side processing step in a conventional Si wafer manufacturing method. [Figure 5B] 2A to 2C are schematic diagrams showing a processed state in a first-side processing step and a second-side processing step in the manufacturing method of the Si wafer in FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] As shown in FIG. 1, in this embodiment, the manufacturing method for a Si wafer, which is a semiconductor crystal wafer, is a method for obtaining a Si wafer by removing waviness from one side of a wafer sliced ​​from a Si ingot ground into a cylindrical shape, and includes a groove processing step (STEP 100 / FIG. 1), a cutting step (STEP 110 / FIG. 1), a first side processing step (STEP 120 / FIG. 1), and a second side processing step (STEP 130 / FIG. 1).

[0023] The processing in the first surface processing step in STEP 120 and the second surface processing step in STEP 130, i.e., mechanical polishing (high-precision grinding), corresponds to the semiconductor crystal wafer grinding method of the present invention (the grinding and grinding steps 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 by the applicant of the present application, so detailed description will be omitted here and only an outline will be provided below.

[0024] 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.

[0025] Then, in the groove processing step of STEP 100, a plurality of grooves are formed around the entire side surface of the Si ingot.

[0026] Specifically, in the groove machining process of STEP 100, groove machining drum grinding wheels, each having a convex portion corresponding to the groove formed on its side, are rotated on mutually parallel rotation axes while being pressed against a Si ingot to form a groove.

[0027] It is preferable to perform a damage-free mirror finish on the Si ingot (especially the grooves) obtained in the groove processing step by a chemical processing method.

[0028] 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, to obtain Si wafers 100.

[0029] 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 rotating them, cutting the Si ingot into slices.

[0030] Next, as shown in FIG. 2, in the first surface processing step of 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).

[0031] 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.

[0032] 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 provided radially on the platen 52. More specifically, the stick-shaped grindstones 53 are fixed in a recess (not shown) formed in the platen 52 such that the lower side of the stick-shaped grindstones 53 partially fits into the recess (not shown).

[0033] The grindstone 53 is, for example, a diamond grindstone suitable for grinding Si wafers, and contains cerium oxide in the material composition at a rate of more than 0% and not more than 10% in order to remove an oxide film, which will be described later.

[0034] First, one surface 110 is set as the upper surface and adsorbed and supported by a vacuum porous chuck 54, which is an adsorption plate of a spindle 51, which is a support stand that supports a wafer, and the other surface 120 is set as the lower surface and is ground by a grindstone 53.

[0035] At this time, the spindle 51 and the platen 52 are rotated by a drive device (not shown), and the spindle 51 is pressed against the platen 52 by a compressor (not shown) or the like, thereby subjecting the other surface 120 to grinding.

[0036] After the grinding process, the grindstone 53 may be dressed using a dresser or the like.

[0037] Furthermore, the mechanical polishing apparatus 50 may have functional water supply pipes so that a plurality of types of functional water can be used during processing, if necessary.

[0038] Next, in the second surface processing step of STEP 130, the other surface 120 that has been subjected to the high-precision grinding process in the first surface processing step is used as the upper surface, and the one surface 110 is subjected to the same high-precision grinding process as in the first surface processing step.

[0039] That is, the other surface 120 is attached to a vacuum porous chuck 54 which is an attachment plate of the spindle 51 with the other surface 120 serving as an upper surface, and the one surface 110 is ground with the grindstone 53 with the one surface 110 serving as a lower surface.

[0040] In this case as well, dressing may be performed by pressing a dresser or the like against the grindstone 53, if necessary.

[0041] 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, particularly as shown in FIG. 4, a plastic deformation region 100A is formed on the surface of the wafer 100 due to a temperature rise caused by friction between the grindstone 53 and the grindstone 53 and the pressing force of the wafer 100 pressed against the grindstone 53 via the spindle 51, and the plastic deformation region 100A is ground with the grindstone 53 while removing the oxide film 100B formed on the surface of the plastic deformation region 100A with the grindstone 53 by incorporating cerium oxide into the grindstone 53.

[0042] At this time, within the plastic deformation region 100A, there is a plastic brittle intermediate layer 100C present on the opposite side to 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.

[0043] According to the above-described 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 against the platen 52), the grinding wheel 53 reaches the plastic deformation region 100A, and only the surface of the plastic deformation region 100A is ground.

[0044] 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.

[0045] That is, in the plastic deformation region 100A of the wafer 100 from which the oxide film 100B has been removed, the grinding efficiency is significantly improved by the grindstone 53, unlike surface polishing in a state without plastic deformation, and a mirror finish with high flatness can be achieved in one go. That is, the complicated manufacturing process, such as multiple lappings (first to fourth), can be significantly simplified.

[0046] 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.

[0047] Thus, according to the grinding method for a Si wafer, which is a semiconductor crystal wafer, of the present embodiment, it is possible to actually provide a grinding method for a semiconductor crystal wafer that can achieve higher grinding accuracy by more precisely and in detail managing the plastic deformation, which has been conventionally abhorred, as a plastic deformation mechanism of the wafer surface.

[0048] 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.

[0049] Furthermore, in this embodiment, the case has been described in which cutting is performed in the cutting step after the grooves are formed in the groove processing step, but the groove processing step may be omitted as appropriate.

[0050] In addition, in this embodiment, the grinding wheel 53 containing cerium oxide 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 the shape is suitable for the purpose of grinding the end surface of the wafer 100 or ingot.

[0051] Furthermore, in this embodiment, the removal of the oxide film using cerium oxide as a functional additive is described as an example of functional polishing of the surface of the plastic deformation region, but the functional polishing (surface treatment) and the functional additive used therein are not limited to this. For example, in order to perform CMP (chemical mechanical polishing) as functional polishing in an integrated manner with grinding, potassium permanganate (potassium permanganate-based slurry) or the like may be contained in the grindstone 53 as a functional additive (in addition to or instead of cerium oxide). [Explanation of symbols]

[0052] 50...mechanical polishing device (ultra-high synthesis high precision grinding device), 51...spindle (support base), 52...platen (grinding table), 53...grinding stone, 54...vacuum porous chuck (suction plate), 100...Si wafer (semiconductor crystal wafer), 110...one side, 120...other side.

Claims

1. A method for grinding a semiconductor crystal, which grinds an end face of a semiconductor crystal ingot ground into a cylindrical shape or a surface of a wafer cut into a slice from the semiconductor crystal ingot, comprising: A grinding wheel is provided on a grinding machine for grinding, and a pressing force is applied to the semiconductor crystal ingot or the wafer via a support base, so that a plastic deformation region is formed on the end face of the semiconductor crystal ingot on the grinding machine side or on the surface of the wafer on the grinding machine side due to a temperature rise caused by friction between the grinding wheel and the end face. A grinding method for a semiconductor crystal, comprising the steps of: grinding the plastic deformation region with a grindstone while functionally polishing the surface of the plastic deformation region by making the grindstone contain a functional additive; A method for grinding a semiconductor crystal, comprising the steps of: grinding the plastic deformation region with a grindstone while removing an oxide film formed on the surface of the plastic deformation region with the grindstone by containing cerium oxide in the grindstone.

2. 2. The method for grinding a semiconductor crystal according to claim 1, A method for grinding a semiconductor crystal, characterized in that a plastic brittle intermediate layer present on the opposite side of the grinding machine in 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. A grinding wheel for use in the method for grinding semiconductor crystals according to claim 1 or 2, A grinding wheel comprising cerium oxide in an amount of from 0% to 10% in its material composition.

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