Wafer Manufacturing Method

Abstract

To provide a wafer manufacturing method with higher manufacturing efficiency than before.SOLUTION: A wafer manufacturing method for obtaining a wafer (1) from an ingot (2) includes the following procedures, steps, or processes: irradiating a surface (21) on one end side in a height direction of the ingot (2) with a laser beam having transmissivity to form a peeling layer (25) at a depth corresponding to the thickness of the wafer (1) from the surface (21); peeling a wafer precursor (26) being a portion between the surface (21) of the ingot (2) and the peeling layer (25) from the ingot (2) by using the peeling layer (25); and flattening a principal surface (32) of a plate-like peeled body (30) obtained by peeling the wafer precursor (26) from the ingot (2) in an electrochemical mechanical manner to obtain the wafer (1).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wafer manufacturing method. [Background technology]

[0002] The wafer production method described in Patent Document 1 includes a separation layer forming step, a separation step, and a flat surface shaping step. The separation layer forming step is a step of forming a separation layer by irradiating the ingot with a pulsed laser beam having a wavelength that is transparent to the ingot, with the focal point positioned at a depth corresponding to the thickness of the wafer to be produced from the flat surface of the ingot. The wafer separation step is a step of separating the wafer to be produced from the ingot starting from the separation layer. Here, when the wafer to be produced is separated from the ingot, the separated surface becomes uneven. For this reason, the flat surface shaping step is a step of grinding the top surface of the ingot from which the wafer has been separated to form a flat surface so that the focal point is positioned at an appropriate position when the laser beam to produce the next wafer is irradiated. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6935224 Summary of the Invention [Problem to be solved by the invention]

[0004] Compared to conventional wafer manufacturing methods, it is possible to improve manufacturing efficiency by reducing the number of steps and processing costs. Specifically, for example, the surface of a wafer produced from an ingot is polished to a mirror finish. Here, the polishing processing cost can vary depending on the wafer slicing method, polishing method, the number of times the holder is attached and detached, etc. The present invention has been made in consideration of the circumstances exemplified above. That is, the present invention provides, for example, a wafer manufacturing method with higher manufacturing efficiency than conventional methods. [Means for solving the problem]

[0005] The wafer manufacturing method according to claim 1 includes: The c-axis (Lc) and C-plane (Pc) of a SiC single crystal are perpendicular to each other. A method for obtaining wafers (1) from an ingot (2), comprising the following steps, processes or treatments: A laser beam having transparency to the surface (21) on one end side in the height direction of the ingot is applied. From the C side (Pc) By irradiating the surface, a peeling layer (25) is formed at a depth corresponding to the thickness of the wafer, A wafer precursor (26) that is a portion between the surface and the exfoliation layer is peeled off from the ingot at the exfoliation layer; A plate-shaped peeled body (30) obtained by peeling the wafer precursor from the ingot. The peeled body is held by a holder (64) at a non-peeled surface (31) that is the backside of the peeled surface (32) with the peeled surface (32) facing a predetermined direction, and a first planarization, which is a first-stage electrochemical mechanical planarization, and a second planarization, which is a subsequent second-stage electrochemical mechanical planarization, are carried out while maintaining the posture of the peeled body from the start of the first planarization to the end of the second planarization, thereby forming the peeled surface. The wafer is obtained by electrochemical mechanical planarization.

[0006] In this wafer manufacturing method, first, the surface of the ingot is irradiated with the laser beam having transparency to form the delamination layer from the surface to a depth corresponding to the thickness of the wafer. Next, the wafer precursor, which is the portion between the surface and the delamination layer, is delaminate from the ingot at the delamination layer. Next, the main surface of the plate-shaped delamination body obtained by delaminating the wafer precursor from the ingot is electrochemically and mechanically planarized to obtain the wafer.

[0007] where The separation layer is formed by irradiating the laser beam onto the surface corresponding to the non-separated surface (i.e., from the C-face side). Therefore, in the separated body immediately after separation, the non-separated surface retains a mirror finish due to the previous formation of the separation layer to such an extent that the laser beam can penetrate to the inside of the ingot. Therefore, there is little need to polish or grind the non-separated surface. Therefore, the separated body is held by the holder at the non-separated surface, and there is no need to reverse the position of the separated body between the first flattening and the second flattening. Therefore, the process of attaching and detaching the separated body to and from the holder and reversing its position can be reduced. Furthermore, The front of the peeled body to be processed by electrochemical mechanical planarization. PeelingThe surface is a sliced surface obtained by so-called laser slicing, and has smaller irregularities than a sliced surface obtained by so-called wire slicing. Furthermore, electrochemical mechanical planarization methods (i.e., ECMG and ECMP) are less likely to form a damaged layer containing microcracks and residual stress on the processed surface than other surface planarization methods (e.g., general grinding and CMP). Therefore, the wafer manufacturing method described above makes it possible to reduce the planarization processing cost as much as possible. Therefore, it is possible to provide a wafer manufacturing method with higher manufacturing efficiency than conventional methods. ECMG stands for Electro-Chemical Mechanical Grinding. ECMP stands for Electro-Chemical Mechanical Polishing. CMP stands for Chemical Mechanical Polishing.

[0008] In addition, in each section of the application documents, each element may be assigned a reference symbol in parentheses. In this case, the reference symbol merely indicates an example of the correspondence between the element and the specific configuration described in the embodiment described below. Therefore, the present invention is not limited in any way by the description of the reference symbol. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a side view showing a schematic configuration of a wafer, an ingot, and a peeled body in a wafer manufacturing method according to an embodiment of the present invention. [Figure 2] 1A to 1C are process diagrams illustrating an outline of a wafer manufacturing method according to an embodiment of the present invention. [Figure 3] FIG. 3 is a side view showing an outline of the release layer forming step shown in FIG. 2. [Figure 4] FIG. 4 is a plan view of the ingot that has undergone the peeling layer forming step shown in FIG. 3. [Figure 5] FIG. 3 is a side view showing an outline of the peeling step shown in FIG. 2. [Figure 6] FIG. 3 is a side view showing an outline of the ECMG process or ECMP process shown in FIG. 2. [Figure 7]3 is a schematic diagram showing how an ingot and a peeled body are handled in the wafer manufacturing method shown in FIG. 2. FIG. [Figure 8] 8 is a schematic diagram showing how an ingot and a peeled body are handled in a case where a part of the wafer manufacturing method shown in FIGS. 2 and 7 is modified. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Embodiment) Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that various modifications applicable to one embodiment may be hindered from being understood if they are introduced in the middle of a series of explanations relating to the embodiment. Therefore, the modifications will not be introduced in the middle of a series of explanations relating to the embodiment, but will be explained together after the series of explanations.

[0011] (Wafer and ingot structure) Referring to FIG. 1, a wafer 1 manufactured by the wafer manufacturing method according to this embodiment constitutes a SiC substrate made of single-crystal SiC and is formed in the shape of a thin, generally circular plate in plan view. An ingot 2 is formed in a generally cylindrical shape. The wafer 1 has a pair of main surfaces, a wafer C-face 11 and a wafer Si-face 12. The "main surface" is a surface perpendicular to the thickness direction of a plate-like object and may also be referred to as a "plate surface." Alternatively, the "main surface" is a surface perpendicular to the height direction of a columnar object such as the ingot 2 and may also be referred to as a "top surface" or "bottom surface." The ingot 2 has an ingot C-face 21, which is its top surface, and an ingot Si-face 22, which is its back surface.

[0012] In this embodiment, the wafer 1 is formed so that the wafer C-plane 11 is inclined at an off angle θ with respect to the (0001) plane Pc. Similarly, the ingot 2 is formed so that the ingot C-plane 21 is inclined at an off angle θ with respect to the (0001) plane Pc. The (0001) plane Pc is a crystal plane that is orthogonal to the c-axis Lc and is referred to as the "C-plane" in the strict sense of crystallography. The c-axis Lc is a crystal axis indicated by a direction index of

[0001] . That is, the wafer 1 and the ingot 2 have a c-axis Lc and a (0001) plane Pc that are orthogonal to each other. Furthermore, the wafer 1 and the ingot 2 are formed so that the c-axis Lc is inclined at an off angle θ exceeding 0 degrees in the off-angle direction Dθ with respect to the central axis L that is orthogonal to the main surface. The off angle θ is the angle between the central axis L and the c-axis Lc, and is, for example, approximately 1 to 4 degrees. The off-angle direction Dθ is the direction of movement of a point on the central axis L when the central axis L is rotated toward the c-axis Lc around the intersection of the central axis L and the c-axis Lc, or the direction obtained by mapping such a movement direction onto an imaginary plane perpendicular to the central axis L. Hereinafter, one end of the ingot 2 in the off-angle direction Dθ, i.e., the upstream end, will be referred to as a first end 23, and the other end, i.e., the downstream end, will be referred to as a second end 24.

[0013] For ease of explanation, a left-handed XYZ coordinate system is set as shown in FIG. 1. In this left-handed XYZ coordinate system, the off-angle direction Dθ and the positive X-axis direction are assumed to be the same or approximately the same. The Y-axis is assumed to be parallel to the major surfaces of wafer 1 and ingot 2. The thickness direction of wafer 1 and the height direction of ingot 2 are assumed to be parallel to the Z-axis. In addition, the direction in which wafer C-face 11 and ingot C-face 21 face is assumed to be the positive Z-axis direction.

[0014] (Outline of wafer manufacturing method) The wafer manufacturing method according to this embodiment is a method for obtaining a wafer 1 from an ingot 2, and includes the following steps. (1) Peeling layer formation process: A laser beam having a predetermined degree of transmittance for the ingot 2 is irradiated onto the ingot C-face 21, which is the main surface at one end in the height direction of the ingot 2, to form a peeling layer 25 from the ingot C-face 21 to a depth corresponding to the thickness of the wafer 1. Here, the "predetermined degree of transmittance" refers to a degree of transmittance that allows a focal point BP to be formed inside the ingot 2 at a depth corresponding to the thickness of the wafer 1. (2) Separation step: The wafer precursor 26, which is the portion between the ingot C-face 21 and the separation layer 25, is separated from the ingot 2 at the separation layer 25. Here, the plate-like object obtained by peeling the wafer precursor 26 from the ingot 2 is sometimes referred to as a "wafer" in common sense. However, to distinguish it from the final wafer 1 after production, which has an epi-ready mirror-finished main surface, this plate-like object will be referred to as a "peeled body 30" hereinafter. The peeled body 30 has a pair of main surfaces: a non-peeled surface 31 and a peeled surface 32. The non-peeled surface 31 is a surface that did not constitute the peeled layer 25 before the peeling process and corresponds to the ingot C-face 21 before the peeling layer forming process and the peeling process. The peeled surface 32 is a surface that constituted the peeled layer 25 before the peeling process and has rough unevenness (i.e., to the extent that grinding or polishing is required) due to the peeled layer 25 and the peeling process. (3) Wafer planarization process: At least the peeled surface 32 of the non-peeled surface 31 and the peeled surface 32, which are the main surfaces of the peeled body 30, is electrochemically and mechanically planarized to obtain the final wafer 1 after manufacture. (4) Ingot planarization step: After the wafer precursor 26 is peeled off, the top surface of the newly produced ingot 2 is planarized, that is, mirror-finished, so that it can be subjected to the peeling layer formation step again.

[0015] 2 is a process diagram showing a specific example of a wafer manufacturing method according to this embodiment. As shown in FIG. 2, a peeled body 30 peeled from an ingot 2 through a peeling layer forming step and a peeling step is finished into an epi-ready wafer 1 through the following steps. Rough grinding of the peeled surface 32 that will become the wafer Si surface 12 Edge grinding Laser marking ECMG grinding of the peeled surface 32 that will become the wafer Si surface 12 ECMP polishing of the separation surface 32 that will become the wafer Si surface 12 Cleaning Furthermore, the ingot 2 remaining after the peeled body 30 has been peeled off from the ingot 2 through the peeling layer forming step and the peeling step can be subjected to the peeling layer forming step again through the following steps. Rough grinding of ingot C surface 21 Finish grinding of ingot C surface 21 Cleaning Each step will be described in detail below with reference to other figures in addition to FIGS.

[0016] (Release layer formation process) 3 and 4 show an outline of the release layer forming process and a release layer forming apparatus 40 used in this process. Release layer forming apparatus 40 includes a chuck table 41, a focusing device 42, and a scanning device 43. The left-handed XYZ coordinate system shown in FIGS. 3 and 4 is displayed so as to match the left-handed XYZ coordinate system shown in FIG.

[0017] The chuck table 41 is configured to hold the ingot 2 on the side of the ingot Si surface 22, which is its bottom surface. Specifically, for example, the chuck table 41 includes a suction mechanism that suctions the ingot Si surface 22 by air pressure or the like. The focusing device 42 is configured to focus a laser beam B emitted by a pulsed laser oscillator (not shown) and irradiate the ingot 2, which is the workpiece, from the side of the ingot C surface 21, which is the top surface. In this embodiment, the peeling layer forming device 40 is configured to irradiate the ingot 2 with the laser beam B having an intensity distribution such that the intensity is higher at the outer periphery than at the center in the beam diameter direction. The "beam diameter direction" is a direction extending radially from the optical axis of the focusing device 42. In other words, the "beam diameter direction" is the direction in which a half-ray extends when a half-ray is drawn on an imaginary plane perpendicular to the optical axis of the focusing device 42, starting from the intersection of the optical axis and the imaginary plane. In other words, the "beam diameter direction" is the radial direction of a circle drawn on a virtual plane perpendicular to the optical axis of the focusing device 42, with the intersection of the virtual plane and the optical axis as the center. Specifically, the peeling layer forming device 40 is configured to irradiate the ingot 2 with a laser beam B having a beam shape that is annular, i.e., hollow, in front of the focusing point BP and focused into a point shape at the focusing point BP. The scanning device 43 is configured to be able to move the focusing point BP of the laser beam B relative to the ingot 2 at least in the in-plane direction, i.e., the XY direction in the figure. The "in-plane direction" is a direction parallel to the ingot C-plane 21, which is the top surface of the ingot 2.

[0018] In this embodiment, the separation layer forming apparatus 40 moves the focusing device 42 relative to the ingot 2 in a scanning direction Ds parallel to the off-angle direction Dθ to scan the ingot 2 with the laser beam B, thereby forming scan lines Ls, which are linear irradiation marks, along the off-angle direction Dθ. After forming at least one scan line Ls through one scan, i.e., one relative movement, the separation layer forming apparatus 40 moves the focusing device 42 relative to the ingot 2 by a predetermined amount in the line feed direction Df. The separation layer forming apparatus 40 then again moves the focusing device 42 relative to the ingot 2 in the scanning direction Ds (i.e., the same or opposite direction as the previous scan) to scan the ingot 2 with the laser beam B, thereby forming the scan line Ls. The line feed direction Df is a direction orthogonal to the off-angle direction Dθ and to the height direction of the ingot 2. In this manner, the separation layer forming apparatus 40 scans the ingot 2 with the laser beam B over substantially the entire width in the line feed direction Df, thereby forming a plurality of scan lines Ls along the line feed direction Df. As a result, a plurality of scanning lines Ls are provided along the line feed direction Df to form a peeling layer 25. Furthermore, a wafer precursor 26, which will become the wafer 1 in the future, is formed on the ingot C-plane 21 side of the peeling layer 25.

[0019] (peeling process) 5 shows an outline of the peeling process and a peeling device 50 used in the process. The left-handed XYZ coordinate system shown in FIG. 5 is displayed so as to match the left-handed XYZ coordinate system shown in FIG.

[0020] The delamination apparatus 50 is configured to apply a load in one direction to a first end 23, which is one end of the ingot 2 in an in-plane direction parallel to the ingot C-plane 21, i.e., in the off-angle direction Dθ, to delaminate the wafer precursor 26 from the ingot 2 at the delamination layer 25. Specifically, in this embodiment, the delamination apparatus 50 includes a support table 51, a delamination pad 52, and a drive member 53.

[0021] The support table 51 is configured to support the ingot 2 from below. Specifically, the support table 51 has a number of suction holes (not shown) opening in its upper surface, which is a support and suction surface 51a, and is configured to suction-hold the ingot Si surface 22 onto the support and suction surface 51a by air pressure. The support table 51 has a first table end 51b and a second table end 51c, which are opposite ends in the off-angle direction Dθ. The second table end 51c, which is the end on one side in the off-angle direction Dθ (i.e., the left side in the figure), has a table base end surface 51d. The table base end surface 51d is formed as an inclined surface that rises toward the off-angle direction Dθ. That is, as shown in FIG. 5, the support table 51 is formed in a trapezoidal shape in a side view, with the lower base longer than the upper base.

[0022] The stripping pad 52 is provided above the support table 51 and is movable toward and away from the support table 51. The stripping pad 52 has a number of suction holes (not shown) opening in its bottom surface, which is a pad suction surface 52a, and is configured to adsorb the ingot C-face 21 to the pad suction surface 52a by air pressure. The stripping pad 52 has a first pad end 52b and a second pad end 52c, which are opposite ends in the off-angle direction Dθ. The second pad end 52c, which is the end on one side (i.e., the left side in the figure) in the off-angle direction Dθ, has a pad end surface 52d. The pad end surface 52d is formed as an inclined surface that descends toward the off-angle direction Dθ. That is, as shown in FIG. 5, the stripping pad 52 is formed in a trapezoidal shape with its lower base shorter than its upper base in a side view. The pad end surface 52d is provided at a position corresponding to (i.e., directly above) the table base end surface 51d. The state in which the ingot C surface 21 is fixed to the peeling pad 52 by suction and the ingot Si surface 22 is fixed to the support table 51 by suction, and the ingot 2 is sandwiched between the support table 51 and the peeling pad 52 is hereinafter referred to as the "clamped state."

[0023] The driving member 53 is configured to apply an external force to at least one of the support table 51 and the stripping pad 52 in a sandwiched state to move the support table 51 and the stripping pad 52 relative to each other along the height direction of the ingot 2. Specifically, the driving member 53 has a first driving end surface 53a and a second driving end surface 53b. The first driving end surface 53a is formed as an inclined surface that descends toward the off-angle direction Dθ. That is, the first driving end surface 53a is arranged parallel to the pad end surface 52d. The second driving end surface 53b is formed as an inclined surface that ascends toward the off-angle direction Dθ. That is, the second driving end surface 53b is arranged parallel to the table base end surface 51d. Furthermore, the driving member 53 is configured so that, in a sandwiched state, the first driving end surface 53a abuts against the pad end surface 52d and the second driving end surface 53b abuts against the table base end surface 51d. 5, the driving member 53 has a shape obtained by rotating a trapezoid, in which the bottom base is longer than the top base, clockwise by 90 degrees in a side view. The driving member 53 is configured to be driven by a driving means (not shown) upward along the height direction of the ingot 2 and / or in an off-angle direction Dθ, which is a direction toward the ingot 2. In other words, the driving member 53 is configured to apply a moment to the ingot 2, with the second pad end 52c as the force point FP and the first end 23 as the fulcrum PP and the point of application WP, by being driven upward and / or in the off-angle direction Dθ.

[0024] The peeling process for peeling the wafer precursor 26 from the ingot 2 includes a table fixing process, a clamping process, and a peeling force application process. The table fixing process is a process of fixing the ingot 2 to the support table 51 by adsorbing the ingot Si surface 22 to the support adsorption surface 51a. The clamping process is a process of fixing the ingot 2 to the peeling pad 52 by adsorbing the ingot C surface 21 to the pad adsorption surface 52a, thereby forming a clamped state. The peeling force application process is a process of applying a static or dynamic load to the second pad end 52c, which is an end of the peeling pad 52 on one side in the off-angle direction Dθ, with the force point FP serving as the force point FP, so that a moment with the first end 23 as the fulcrum PP acts on the ingot 2. Specifically, the peeling force application process is a process of pressing the second pad end 52c upward along the height direction of the ingot 2 by driving the driving member 53 upward and / or in the off-angle direction Dθ in the clamped state. As a result, the wafer precursor 26, which is a part of the ingot 2, can be peeled off from the ingot 2 with the peeling layer 25 as the interface.

[0025] (flattening process) FIG. 6 shows an outline of an electrochemical mechanical planarization process (i.e., ECMG and ECMP) and a surface processing apparatus 60 used in such a process. That is, the surface processing apparatus 60 has a configuration as an ECMP apparatus or an ECMG apparatus. The surface processing apparatus 60 is configured to perform a polishing or grinding process using anodization on a workpiece, which is a workpiece surface Pw, that is a main surface of a peeled body 30 to be formed into a single-crystal SiC wafer 1. The workpiece surface Pw is at least the peeled surface 32 shown in FIG. 1. Specifically, the surface processing apparatus 60 includes a container 61, a surface processing pad 62, a pad-side electrode 63, a wafer support chuck 64, a drive unit 65, and a power supply unit 66.

[0026] In this embodiment, the container 61 is configured to accommodate the peeled body 30 while immersed in an electrolytic solution EL that does not contain an etchant component. The etchant component is a component (e.g., hydrofluoric acid, etc.) that constitutes a dissolving solution capable of dissolving an oxide film (i.e., a SiC oxide film) formed on the workpiece surface Pw by anodization. The electrolytic solution EL is, for example, an aqueous solution of sodium chloride, potassium chloride, sodium nitrate, etc.

[0027] The surface processing pad 62 is a grinding stone layer and contains an abrasive material with a predetermined hardness. Specifically, when used in the ECMG process, the surface processing pad 62 contains an abrasive material with a Mohs hardness higher than that of single crystal SiC. On the other hand, when used in the ECMP process, the surface processing pad 62 contains an abrasive material with a Mohs hardness intermediate between that of single crystal SiC and its oxide film. The surface processing pad 62 is disposed opposite the processing surface Pw of the stripping body 30 in the presence of the electrolyte EL. The pad-side electrode 63 is a plate-like member made of a good conductor such as metal, and is formed of, for example, a copper plate. The pad-side electrode 63 is bonded to the back surface of the surface processing pad 62 (i.e., the back surface of the surface facing the stripping body 30).

[0028] The wafer support chuck 64 is configured to attract the back surface of the peeler 30 (i.e., the back surface of the workpiece surface Pw) and thereby hold the peeler 30 in an orientation in which the workpiece surface Pw faces the surface processing pad 62. The drive device 65 is configured to relatively move the wafer support chuck 64 and the assembly of the surface processing pad 62 and the pad-side electrode 63 at least in the in-plane direction (i.e., the direction along the workpiece surface Pw). The power supply device 66 is configured to apply a voltage in the presence of the electrolytic solution EL, with the peeler 30 side (the workpiece) as the anode and the surface processing pad 62 side as the cathode, thereby passing a current for anodizing the workpiece surface Pw, which is the target of processing by the surface processing pad 62.

[0029] The surface processing device 60 is configured to rotate the surface processing pad 62 and / or the wafer support chuck 64 around a predetermined rotation axis that is parallel to the thickness direction of the surface processing pad 62. The surface processing device 60 is also configured to move the surface processing pad 62 and the wafer support chuck 64 relatively in an in-plane direction that is perpendicular to the rotation axis. The surface processing device 60 is configured to selectively polish or grind away an oxide film that has formed on the processing surface Pw by anodization while performing the above-mentioned rotation drive and relative movement.

[0030] FIG. 7 shows a schematic flow of the planarization process of the peeled body 30. Hereinafter, the planarization process of the peeled body 30 will be described in detail mainly with reference to FIGS. 1, 2, and 7. For the sake of simplicity, FIG. 7 shows only a simplified illustration of the surface processing device 60 used in the ECMG process and the ECMP process, the edge grinding device 70 used in the edge grinding process, and the transport device 80 for transporting the peeled body 30, which is the workpiece. The surface processing device 60 used in the ECMG process and the surface processing device 60 used in the ECMP process may be provided in parallel or may be a common device.

[0031] In this embodiment, the separation surface 32, which is to become the wafer Si surface 12, is subjected to two-stage electrochemical mechanical planarization. Specifically, first, grinding is performed by the ECMG process as the first stage of electrochemical mechanical planarization, which is the first planarization. Next, polishing is performed by the ECMP process as the second stage of electrochemical mechanical planarization, which is the second planarization.

[0032] In the peeled body 30 immediately after the peeling step, the non-peeled surface 31 retains a mirror finish equivalent to that of the ingot C-face 21, which allows the laser beam B to penetrate to the interior of the ingot 2 in the previous peeling layer formation step. Therefore, the non-peeled surface 31 can be used as is as the epi-ready wafer C-face 11. In contrast, the peeled surface 32, which corresponds to the wafer Si-face 12, has rough irregularities resulting from the formation of the peeling layer 25 and the peeling step. For this reason, the peeled surface 32 is roughly ground prior to the ECMG step or ECMP step.

[0033] Furthermore, the peeled body 30 immediately after rough grinding has sharp edges. The "edges" refer to the outer edges of the non-peeled surface 31 and the peeled surface 32 in the in-plane direction, i.e., the wafer radial direction. If the peeled body 30 in this state is subjected to the ECMG process or the ECMP process, cracks or chips may occur at the edges. Therefore, in this embodiment, the edges of the peeled body 30 are ground prior to the ECMG process or the ECMP process.

[0034] The peeled surface 32 of the peeled body 30 that has undergone rough grinding and edge grinding is ground by the ECMG process and then mirror-finished by the ECMP process. Specifically, for example, the peeled surface 32 is roughly ground using a grinding wheel carrying 400-2000 grit diamond abrasive grains. Next, the peeled surface 32 is ground using 10,000-30,000 grit diamond abrasive grains in the ECMG process, which is a first-stage electrochemical mechanical planarization. Subsequently, the peeled surface 32 is polished using ceria abrasive grains in the ECMP process, which is a second-stage electrochemical mechanical planarization. Alternatively, for example, the peeled surface 32 is roughly ground using a grinding wheel carrying 400-800 grit diamond abrasive grains. Next, the peeled surface 32 is ground using 8,000-30,000 grit diamond abrasive grains in the ECMG process, which is a first-stage electrochemical mechanical planarization. The release surface 32 is then polished using a ceria abrasive in a second stage electrochemical mechanical planarization (ECP) process.

[0035] As described above, in this embodiment, the peeling layer forming step is performed by irradiating the laser beam B onto the ingot C face 21 (i.e., from the (0001) plane Pc side). Therefore, the non-peeling surface 31 resulting from the ingot C face 21 does not need to be ground or polished unless minor scratches are generated due to chucking or detaching the peeling body 30. In addition, a laser mark for managing and identifying the wafer 1 is formed on the wafer C face 11.

[0036] Therefore, as shown in FIG. 7 , the orientation of the separation body 30 can be maintained with the non-separation surface 31 facing upward in the figure between the ECMG process (first planarization) and the ECMP process (second planarization). That is, there is no need to invert the orientation of the separation body 30 from the rough grinding through the ECMG process to the ECMP process. Therefore, when electrochemically and mechanically planarizing the separation surface 32, which is the main surface of the separation body 30 on the side of the release layer 25, the separation body 30 can be maintained in a state where the separation surface 32 faces a predetermined direction (i.e., downward in FIG. 7 ) and the non-separation surface 31, which is the back surface of the separation body 30, is held. Specifically, the separation body 30 can be maintained in a held state by the wafer support chuck 64, which is a holder that holds the separation body 30, at least from the start of the ECMG process (first planarization) to the end of the ECMP process (second planarization).

[0037] In contrast, Fig. 8 shows an example of "Si-face side irradiation" in which the peeling layer 25 is formed on the ingot Si-face 22 side, as opposed to "C-face side irradiation" in which the peeling layer 25 is formed on the ingot C-face 21 side as shown in Fig. 7. Note that in Figs. 7 and 8, the ingot C-face 21 is indicated by diagonal hatching. Also, the main surface of the peeled body 30 that will become the wafer C-face 11 is indicated by a thick line.

[0038] As shown in Figure 8, in the case of Si-side irradiation, the separation surface 32 corresponding to the wafer C-side 11 has rough irregularities due to the formation of the separation layer 25 and the separation process. Therefore, the separation surface 32 is roughly ground prior to the ECMG and ECMP processes. The separation body 30 is then inverted so that the separation surface 32 faces upward in the figure for laser marking. Next, after laser marking, the separation body 30 is again inverted so that the separation surface 32 faces downward in the figure for grinding by the ECMG process on the separation surface 32 that will become the wafer C-side 11. Here, there is a concern that fine scratches will occur on the non-separated surface 31 that will become the wafer Si-side 12 due to the ingot Si-side 22, caused by chucking and detaching the separation body 30. Therefore, the separation body 30 is further inverted for mirror finishing of the non-separated surface 31 by the ECMP process. As described above in detail, the C-face side irradiation shown in FIG. 7 and the Si-face side irradiation shown in FIG. 8 are significantly different in the manner in which the posture of the peeled body 30 changes after rough grinding and in the grinding or polishing process that accompanies this.

[0039] The ingot C-face 21, which is the new surface of the ingot 2 formed by peeling the wafer precursor 26 at the peeling layer 25, can be mirror-finished by rough grinding and finish grinding, and then cleaned, so that it can be subjected to the peeling layer formation process again. That is, by irradiating the mirror-finished surface of the ingot C-face 21 with a laser beam B, it is possible to form the peeling layer 25 again. Rough grinding can be performed using a grinding wheel carrying diamond abrasive grains of 400 to 2000. Finish grinding, i.e., polishing, can be performed using a grinding wheel carrying diamond abrasive grains of 10,000 to 30,000. Note that, if the height of the ingot 2 is low, the ECMG process can also be used for the finish grinding.

[0040] (effect) The effects achieved by the method for manufacturing the wafer 1 according to this embodiment will be described below.

[0041] (1) In the manufacturing method according to this embodiment, first, a transparent laser beam B is irradiated onto the main surface of the ingot 2, thereby forming a delamination layer 25 from the main surface of the ingot 2 to a depth corresponding to the thickness of the wafer 1. Next, a wafer precursor 26, which is the portion between the main surface of the ingot 2 on the side irradiated with the laser beam B and the delamination layer 25, is delaminated from the ingot 2 at the delamination layer 25. Next, at least a delamination surface 32 of a pair of main surfaces of a plate-shaped delamination body 30 obtained by delaminating the wafer precursor 26 from the ingot 2 is electrochemically and mechanically planarized to obtain the wafer 1.

[0042] Here, the peeled surface 32 of the peeled body 30, which is the target of electrochemical mechanical planarization, is a surface sliced by so-called laser slicing, and has smaller irregularities than a surface sliced by so-called wire slicing. Furthermore, electrochemical mechanical planarization methods (i.e., ECMG and ECMP) are less likely to form a damaged layer containing microcracks, residual stress, etc., on the processed surface than other surface planarization methods (e.g., general grinding and CMP). Therefore, according to this embodiment, it is possible to reduce the planarization processing cost as much as possible. Therefore, according to this embodiment, it is possible to provide a wafer manufacturing method with higher manufacturing efficiency than conventional methods.

[0043] (2) In this embodiment, the electrochemical mechanical planarization of the peeled surface 32 is performed after the peeled surface 32 is ground. This allows the process time in the ECMG process and the ECMP process to be shortened as much as possible. Therefore, this embodiment can provide a wafer manufacturing method with higher manufacturing efficiency than conventional methods.

[0044] (3) In this embodiment, the ingot 2 is a single-crystal SiC ingot having a c-axis Lc and a C-plane (i.e., the (0001) plane Pc) that are orthogonal to each other. The c-axis Lc is provided with the central axis L tilted at an off-angle θ greater than 0 degrees in the off-angle direction Dθ. The peeling layer formation step is performed by scanning the laser beam B along the off-angle direction Dθ to form a plurality of scan lines Ls, which are linear irradiation marks, along a line feed direction Df that is orthogonal to the off-angle direction Dθ and orthogonal to the height direction of the ingot 2.

[0045] In the method described in Patent Document 1, the laser scanning direction is perpendicular to the direction in which the off-angle θ is formed (i.e., the off-angle direction Dθ in FIGS. 1 and 3). This results in unstable cleavage and increased material loss. In contrast, according to this embodiment, by scanning the laser beam B along the off-angle direction Dθ, cleavage can be stabilized and material loss can be effectively reduced. Furthermore, the process times in the ECMG process and ECMP process can be shortened as much as possible. Therefore, this embodiment can provide a wafer manufacturing method with higher manufacturing efficiency than conventional methods.

[0046] (4) In this embodiment, the laser beam B irradiated onto the ingot 2 in the separation layer formation process has an intensity distribution in which the intensity is higher at the outer peripheral portion than at the center in the beam diameter direction. Therefore, the modified layer formed by the separation of SiC into Si and C, and the cracks propagating from the modified layer, are stably formed at a depth corresponding to the position of the focal point BP. That is, the variation in the depth of the modified layer and the cracks (i.e., their positions in the height direction of the ingot 2) can be minimized. In other words, the thickness of the separation layer 25 formed by the modified layer and the cracks propagating from the modified layer can be effectively reduced. Therefore, it is possible to minimize the unevenness of the ingot C-face 21, which is the new upper surface of the ingot 2 after separation at the separation layer 25, and the separation surface 32 of the separation body 30. This effectively reduces the processing costs involved in grinding and polishing after the separation process. Therefore, this embodiment can provide a wafer manufacturing method with higher manufacturing efficiency than conventional methods.

[0047] (5) In this embodiment, the delamination process is performed by applying a load in one direction to the first end 23 of the ingot 2 in an in-plane direction parallel to the top surface of the ingot 2 (i.e., the ingot C-plane 21 in the example of FIG. 5 ). Then, a moment acts on the ingot 2 with the first end 23 as the fulcrum PP and the point of application WP. By concentrating the load on one end of the delamination layer 25 in the in-plane direction, the applied load can be reduced while stably causing fracture to progress across the entire surface of the delamination layer 25. Furthermore, by stably setting the fracture occurrence location, it is possible to reduce the surface roughness after delamination. This effectively reduces the defect rate in the delamination process and the processing cost in grinding and polishing after the delamination process. In particular, by setting the first end 23, which is the starting point of crack initiation, to one end in the off-angle direction Dθ, more specifically, to one end on the “high” side of the C-plane (i.e., the (0001) plane Pc), cleavage is further stabilized. Therefore, this embodiment makes it possible to provide a wafer manufacturing method with higher manufacturing efficiency than conventional methods.

[0048] (6) In this embodiment, the ingot 2 is a single-crystal SiC ingot having a c-axis Lc and a C-plane (i.e., the (0001) plane Pc) that are orthogonal to each other. The peeling layer formation process is performed by irradiating the C-plane side, i.e., by irradiating the ingot C-plane 21 with the laser beam B. As a result, as is clear from a comparison between the example of FIG. 7 and the example of FIG. 8, the processes of chucking and detaching the peeling body 30 and inverting its position can be eliminated. Therefore, the processing costs for grinding and polishing, which are required for the chucking and detaching and inverting the position, can be effectively reduced. Therefore, this embodiment makes it possible to provide a wafer manufacturing method with higher manufacturing efficiency than conventional methods.

[0049] (7) In this embodiment, the separation surface 32 is planarized by a first planarization step (ECMG step), which is a first-stage electrochemical mechanical planarization step, and a second planarization step (ECMP step), which is a second-stage electrochemical mechanical planarization step. The orientation of the separation body 30 is maintained between the ECMG step and the ECMP step. This means that there is no need to reverse the orientation of the separation body 30 between the ECMG step and the ECMP step. This eliminates the need for the steps of chucking and unchucking the separation body 30 and reversing its orientation. Therefore, this embodiment provides a wafer manufacturing method with higher manufacturing efficiency than conventional methods.

[0050] (8) In this embodiment, the separation body 30 can be maintained in a held state by the wafer support chuck 64, which is a holder that holds the separation body 30, from the start of the ECMG process to the end of the ECMP process. This reduces the number of steps for attaching and detaching the separation body 30 from the chuck. Therefore, this embodiment can provide a wafer manufacturing method with higher manufacturing efficiency than conventional methods.

[0051] (9) In this embodiment, when electrochemically and mechanically planarizing the peeled surface 32, the peeled body 30 is maintained in a state where the peeled surface 32 faces a predetermined direction (i.e., downward in FIG. 7 ) and is held by the non-peeled surface 31, which is the backside of the peeled surface 32. That is, from the start of the ECMG process to the end of the ECMP process, the wafer support chuck 64 continues to hold the peeled body 30 with the non-peeled surface 31 attached to it and the peeled surface 32 exposed downward in the drawing so that it can be planarized. This unifies the processing standard, thereby effectively reducing the processing amount required for planarizing the peeled surface 32. Therefore, this embodiment makes it possible to provide a wafer manufacturing method with higher manufacturing efficiency than conventional methods.

[0052] (10) In the method described in Patent Document 1, the upper surface of the ingot 2 is ground to form a flat surface using a grinding wheel. Therefore, a damaged layer containing microcracks, residual stress, and the like is likely to form on the upper surface of the ingot 2 flattened by grinding. Removing such a damaged layer by polishing increases the processing allowance in the flat surface shaping process. Meanwhile, slowing down the processing speed to suppress the formation of the damaged layer reduces manufacturing efficiency.

[0053] In contrast, in this embodiment, the new upper surface of the ingot 2 (i.e., the ingot C-face 21 in FIG. 1 ) formed by the peeled layer 25 after the wafer precursor 26 is peeled off is planarized as follows: First, it is ground using a grindstone carrying 400-2000 grit diamond abrasive grains. Then, it is polished using a grindstone carrying 10000-30000 grit diamond abrasive grains. Then, the new upper surface of the ingot 2, which has been polished to an epi-ready mirror finish, is irradiated with a laser beam B, thereby re-forming the peeled layer 25. In particular, when C-face irradiation is used, the surface state of the ingot C-face 21 can be made into an epi-ready mirror finish before irradiation with the laser beam B, and can be maintained until polishing of the peeled surface 32 is completed, i.e., until the wafer 1 is completed. This shortens the manufacturing process, thereby providing a wafer manufacturing method with higher manufacturing efficiency than conventional methods.

[0054] (11) In this embodiment, the delaminated surface 32 is planarized as follows. First, it is ground using a grindstone carrying 400-2000 grit diamond abrasive grains. Next, a first-stage electrochemical mechanical planarization (ECMG process) is performed using 10,000-30,000 grit diamond abrasive grains. Subsequently, a second-stage electrochemical mechanical planarization (ECMP process) is performed using ceria abrasive grains. Alternatively, the delaminated surface 32 is roughly ground using a grindstone carrying 400-800 grit diamond abrasive grains. Next, the delaminated surface 32 is ground using the first-stage electrochemical mechanical planarization (ECMG process) using 8,000-30,000 grit diamond abrasive grains. Subsequently, the delaminated surface 32 is polished using the second-stage electrochemical mechanical planarization (ECMP process). This allows for a wafer 1 with a good surface condition to be obtained, and provides a wafer manufacturing method with higher manufacturing efficiency than conventional methods.

[0055] (12) In this embodiment, the electrochemical mechanical planarization of the main surfaces of the peeled body 30, i.e., the non-peeled surface 31 and / or the peeled surface 32, is performed after the edge grinding process of the peeled body 30. This effectively prevents cracks and chips from occurring at the edge, improving yield.

[0056] (Variation) The present invention is not limited to the above-described embodiment. Therefore, the above-described embodiment can be modified as appropriate. Representative modifications will be described below. In the following description of the modifications, differences from the above-described embodiment will be mainly described. Furthermore, the same reference numerals are used for parts that are identical or equivalent to each other in the above-described embodiment and the modifications. Therefore, in the following description of the modifications, the description of the above-described embodiment can be used as appropriate for components that have the same reference numerals as the above-described embodiment, unless there is a technical contradiction or special additional explanation.

[0057] The present invention is not limited to the specific configurations shown in the above embodiments. That is, for example, there are no particular limitations on the outer diameter or planar shape (for example, the presence or absence of a so-called orientation flat) of the wafer 1, i.e., the ingot 2.

[0058] There is no particular limitation on the magnitude of the off-angle θ. Furthermore, in the above-described embodiment, the wafer C-plane 11 and the ingot C-plane 21 do not coincide with the C-plane in the strict crystallographic sense, i.e., the (0001) plane Pc. However, even in such cases, the term "C-plane" is generally accepted, and therefore the term "C-plane" is used. However, the present invention is not limited to such an embodiment. In other words, the wafer C-plane 11 and the ingot C-plane 21 may coincide with the C-plane in the strict crystallographic sense, i.e., the (0001) plane Pc. In other words, the off-angle θ may be 0 degrees.

[0059] Depending on the irradiation conditions and scanning conditions of the laser beam B, the delaminated surface 32 may have a surface condition and edge condition that allows it to be satisfactorily ground or polished even if it is subjected to the ECMG process as is. For this reason, the rough grinding process and edge grinding process of the delaminated surface 32 shown in Figures 2, 7, and 8 may be omitted. The same applies to the rough grinding of the top surface of the ingot 2 after the delamination process.

[0060] The separation layer forming apparatus 40 shown in FIG. 3 is a simplified schematic diagram for easily explaining the outline of the separation layer forming process according to the present invention. Therefore, the specific configuration of the separation layer forming apparatus 40 actually implemented in industrial applications does not necessarily match the exemplary configuration shown in FIG. 3. Specifically, for example, the chuck table 41 may be configured to hold the ingot 2 using a method other than a pneumatic suction mechanism. The chuck table 41 may also be configured to be movable relative to the focusing device 42 at least in the in-plane direction, i.e., the XY directions in the figure. Alternatively, the scanning device 43 may be configured to move the focal point BP of the laser beam B relative to the ingot 2 in the XYZ directions in the figure. The specific configuration of the separation layer forming apparatus 40 actually implemented in industrial applications may be modified as appropriate from the exemplary configuration shown in FIG. 3. The same applies to the separation device 50 shown in FIG. 5, the surface processing device 60 shown in FIG. 6, and the edge grinding device 70 shown in FIGS. 7 and 8. Specifically, for example, in the peeling device 50 shown in FIG. 5, the support table 51 may be configured to adsorb the ingot Si surface 22 onto the support adsorption surface 51a using a method other than an air pressure adsorption mechanism (for example, wax, adhesive, etc.).

[0061] The processing conditions for the ECMG process and the ECMP process are not particularly limited. For example, the electrolyte EL may contain an etchant component. That is, the surface processing device 60 and the surface planarization method that can be performed thereby may polish or grind the processing surface Pw by selectively removing the oxide film formed by anodic oxidation using both the etchant and the surface processing pad 62.

[0062] The electrochemical mechanical planarization process of the present invention is not limited to two steps. Specifically, for example, an ECMG process can be used as the rough grinding process. That is, three or more steps of the electrochemical mechanical planarization process may be performed. Alternatively, the electrochemical mechanical planarization process may be a single step. Thus, as long as the electrochemical mechanical planarization process is performed at least once to planarize the separation body 30 into the wafer 1, any other planarization process used in combination is included in the present invention.

[0063] 7, the peeling body 30 after the peeling step but before the rough grinding of the peeled surface 32 may be held by the wafer support chuck 64 before the rough grinding or before the edge grinding. That is, the rough grinding or the edge grinding may be performed while the peeling body 30 is held by the wafer support chuck 64 that holds the peeling body 30 for the electrochemical mechanical planarization step. In addition, appropriate modifications may be made to the transfer device 80 shown in FIGS. 7 and 8.

[0064] It goes without saying that the elements constituting the above-described embodiments are not necessarily essential unless expressly stated as essential or clearly considered essential in principle. Furthermore, when numerical values such as the number, amount, range, etc. of components are mentioned, the present invention is not limited to those specific numerical values unless expressly stated as essential or clearly limited to specific numerical values in principle. Similarly, when the shape, direction, positional relationship, etc. of components are mentioned, the present invention is not limited to those shapes, directions, positional relationship, etc. unless expressly stated as essential or clearly limited to specific shapes, directions, positional relationship, etc. in principle.

[0065] The modified examples are not limited to the above examples. For example, other than those exemplified above, multiple embodiments may be combined with each other as long as there is no technical contradiction. Similarly, multiple modified examples may be combined with each other as long as there is no technical contradiction.

[0066] As is clear from the above detailed description, the present disclosure includes the following: <1> ~ <12> These aspects may be combined with each other in any way unless there is a technical disadvantage or contradiction. <1> The wafer manufacturing method for obtaining wafers (1) from an ingot (2) includes the following steps, processes, or procedures: a laser beam having transparency is irradiated onto a surface (21) of the ingot at one end in the height direction, thereby forming a peeling layer (25) from the surface to a depth corresponding to the thickness of the wafer; A wafer precursor (26) that is a portion between the surface and the exfoliation layer is peeled off from the ingot at the exfoliation layer; The wafer is obtained by electrochemically and mechanically planarizing the main surface (32) of a plate-shaped peeled body (30) obtained by peeling the wafer precursor from the ingot. <2> The electrochemical mechanical planarization of the main surface is performed after the main surface of the peeled body is ground. <3> The ingot is a single-crystal SiC ingot having a c-axis (Lc) and a C-plane (Pc) perpendicular to each other, the c-axis is inclined at an off angle (θ) exceeding 0 degrees in an off-angle direction (Dθ) with respect to a central axis (L) perpendicular to the surface, The peeling layer is formed by forming a plurality of scan lines (Ls), which are linear irradiation marks formed by scanning the laser beam along the off-angle direction, along a line feed direction (Df) that is perpendicular to the off-angle direction and perpendicular to the height direction of the ingot. <4> The laser beam has an intensity distribution in which the intensity is higher at the outer periphery than at the center in the beam diameter direction. <5> The wafer precursor is peeled off from the ingot at the peeling layer by applying a load in one direction to one end (23) of the ingot in an in-plane direction parallel to the surface. <6> The ingot is a single-crystal SiC ingot having a c-axis (Lc) and a C-plane (Pc) perpendicular to each other, The peeling layer is formed by irradiating the laser beam from the C-plane (Pc) side. <7> Electrochemical mechanical planarizing the major surface includes a first planarization, which is a first-stage electrochemical mechanical planarization, followed by a second planarization, which is a second-stage electrochemical mechanical planarization; The orientation of the peeling body is maintained between the first flattening and the second flattening. <8> From the start of the first flattening to the end of the second flattening, the holding state by the holder (64) that holds the peeled body is maintained. <9> When the main surface is electrochemically and mechanically planarized, the peeled body obtained by peeling the wafer precursor from the ingot is maintained in a state in which the peeled surface (32), which is the main surface on the peeling layer side, is facing in a predetermined direction and is held by the non-peeled surface (31), which is the back surface of the peeled surface. <10> The new surface of the ingot formed by the peeled layer after peeling off the wafer precursor is ground with a grindstone carrying diamond abrasive grains of 400 to 2000 and polished with a grindstone carrying diamond abrasive grains of 10000 to 30000; The release layer is formed by irradiating the laser beam onto the surface that has been polished to a mirror finish. <11> The main surface is ground with a grindstone carrying diamond abrasive grains of 400 to 2000, and then a first planarization, which is a first-stage electrochemical mechanical planarization, is performed using diamond abrasive grains of 10000 to 30000, and a second planarization, which is a second-stage electrochemical mechanical planarization, is performed using ceria abrasive grains. Alternatively, the main surface is ground with a grindstone carrying diamond abrasive grains of 400 to 800, and then a first planarization, which is a first-stage electrochemical mechanical planarization, is performed using diamond abrasive grains of 8000 to 30000, and a second planarization, which is a second-stage electrochemical mechanical planarization, is performed using ceria abrasive grains. <12> The electrochemical mechanical planarization of the main surface is performed after the edge grinding of the peeled body. [Explanation of symbols]

[0067] 1 wafer 2 ingots 21 Ingot C-face (surface) 25 Peeling layer 26 wafer precursors 30 Peeling body 32 Peeling surface (main surface) L center axis Lc c-axis PC (0001) side

Claims

1. A wafer manufacturing method for obtaining a wafer (1) from an ingot (2) of a SiC single crystal having a c-axis (Lc) and a C-plane (Pc) that are perpendicular to each other, comprising: A laser beam having transparency to a surface (21) at one end in the height direction of the ingot is irradiated from the C-plane (Pc) side, thereby forming a peeling layer (25) from the surface to a depth corresponding to the thickness of the wafer; A wafer precursor (26) between the surface and the exfoliation layer is peeled off from the ingot at the exfoliation layer; a first planarization, which is a first-stage electrochemical mechanical planarization, and a second planarization, which is a subsequent second-stage electrochemical mechanical planarization, are performed while maintaining the orientation of the peeled body from the start of the first planarization to the end of the second planarization, thereby obtaining the wafer. Wafer manufacturing method.

2. The electrochemical mechanical planarization of the main surface is performed after the main surface of the peeled body is ground. The wafer manufacturing method according to claim 1 .

3. The wafer precursor is peeled off from the ingot at the peeling layer by applying a load in one direction to one end (23) of the ingot in an in-plane direction parallel to the surface. The wafer manufacturing method according to claim 1 .

4. The new surface of the ingot formed by the peeling layer after peeling off the wafer precursor is ground with a grindstone carrying diamond abrasive grains of 400 to 2000 and polished with a grindstone carrying diamond abrasive grains of 10000 to 30000; The release layer is formed by irradiating the laser beam onto the surface that has been polished to a mirror finish. The wafer manufacturing method according to claim 1 .

5. The main surface is ground with a grindstone carrying diamond abrasive grains of No. 400 to No. 2000, and the first planarization, which is a first-stage electrochemical mechanical planarization, is performed using diamond abrasive grains of No. 10000 to No. 30000, and the second planarization, which is a second-stage electrochemical mechanical planarization, is performed using ceria abrasive grains. The wafer manufacturing method according to claim 1 .

6. The main surface is ground with a grindstone carrying diamond abrasive grains of No. 400 to No. 800, and the first planarization, which is a first-stage electrochemical mechanical planarization, is performed using diamond abrasive grains of No. 8000 to No. 30000, and the second planarization, which is a second-stage electrochemical mechanical planarization, is performed using ceria abrasive grains. The wafer manufacturing method according to claim 1 .

7. The electrochemical mechanical planarization of the main surface is performed after the edge grinding of the peeled body. The wafer manufacturing method according to claim 1 .

Images