Method for manufacturing semiconductor device

Abstract

To provide a method for manufacturing a semiconductor device that restrains residual stress caused by formation of cracks in a semiconductor wafer.SOLUTION: A method includes a step of preparing a semiconductor wafer whose crystal axis is inclined with respect to a perpendicular line to a first surface, a step of pressing a pressing member against the first surface in a first direction along an inclined direction of the crystal axis on the first surface with a first load to form a first crack in the semiconductor wafer, the first load extending along the first direction and in a thickness direction of the semiconductor wafer, a step of pressing a pressing member against the first surface with a second load smaller than the first load along a second direction perpendicular to the first direction on the first surface to form a second crack on the semiconductor wafer, the second crack extending along the second direction and in the thickness direction of the semiconductor wafer, and a step of pressing a dividing member against the semiconductor wafer along the first crack and the second crack from a second surface side located on the back side of the first surface to divide the semiconductor wafer along each crack.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The technology disclosed in this specification relates to a method for manufacturing a semiconductor device.

Background Art

[0002] Patent Document 1 discloses a technique for dividing a substrate by a scribing and breaking method. In Patent Document 1, by pressing a pressing member against the surface of the substrate along a first direction, a crack extending along the first direction is formed in the substrate, and then, by pressing the pressing member against the surface of the substrate along a second direction intersecting the first direction, a crack extending along the second direction is formed in the substrate. Then, by pressing a dividing member, the substrate is divided along the formed crack.

[0003] In Patent Document 1, the load for pressing the pressing member against the surface of the substrate when forming the crack along the first direction is larger than the load for pressing the pressing member against the surface of the substrate when forming the crack along the second direction. Thereby, defects (for example, chipping) of the substrate in the vicinity of the intersection of the crack along the first direction and the crack along the second direction can be suppressed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, a scribe and break method may be adopted to divide a semiconductor wafer. The crystal axis of the semiconductor wafer may be inclined with respect to the perpendicular line of its surface. Cracks are likely to be formed inside the semiconductor wafer along the crystal axis in the thickness direction of the semiconductor wafer. When forming a crack along a direction intersecting the inclination direction of the crystal axis, since the formation direction of the crack in the thickness direction of the semiconductor wafer (the direction inclined with respect to the perpendicular line) is inclined with respect to the pressing direction of the pressing member against the surface of the semiconductor wafer (the direction along the perpendicular line), stress is generated inside the semiconductor wafer. That is, the magnitude of the stress generated inside the semiconductor wafer differs depending on the direction in which the crack is formed. As a result, even after the semiconductor wafer is divided, the stress exists as residual stress, and the characteristics of the manufactured semiconductor device deteriorate. This specification proposes a technique for reducing the residual stress caused by crack formation in a semiconductor wafer.

Means for Solving the Problems

[0006] The manufacturing method of the semiconductor device (10) disclosed in this specification includes a step of preparing a semiconductor wafer (2) whose crystal axis is inclined with respect to the perpendicular line of the first surface (2a), and pressing a pressing member (32) against the first surface along a first direction along the inclination direction of the crystal axis on the first surface with a first load, thereby forming a first crack (5a) along the first direction and extending in the thickness direction of the semiconductor wafer in the semiconductor wafer; a step of pressing the pressing member against the first surface along a second direction perpendicular to the first direction on the first surface with a second load smaller than the first load, thereby forming a second crack (5b) along the second direction and extending in the thickness direction of the semiconductor wafer in the semiconductor wafer; and a step of dividing the semiconductor wafer along the first crack and the second crack by pressing a dividing member (33) against the semiconductor wafer along the first crack and the second crack from the side of the second surface (2b) located on the back side of the first surface. Note that the first crack forming step and the second crack forming step may be carried out in any order.

[0007] In this manufacturing method, since the first direction is along the inclination direction of the crystal axis, when the first crack is formed along the first direction, the formation direction of the first crack in the thickness direction of the semiconductor wafer substantially coincides with the pressing direction by the pressing member. Therefore, the stress generated inside the semiconductor wafer due to the formation of the first crack is small. On the other hand, since the second direction is a direction orthogonal to the inclination direction of the crystal axis, when the second crack is formed along the second direction, the formation direction of the second crack in the thickness direction of the semiconductor wafer inclines with respect to the pressing direction by the pressing member. Therefore, the stress generated inside the semiconductor wafer due to the formation of the second crack becomes large. However, in this manufacturing method, the second load of the pressing member when forming the second crack is smaller than the first load of the pressing member when forming the first crack. Therefore, when forming the second crack, the stress caused by the difference between the formation direction of the second crack and the pressing direction of the pressing member is reduced. As a result, the residual stress of the entire semiconductor device after dividing the semiconductor wafer is reduced, and a semiconductor device with high reliability can be manufactured.

Brief Description of the Drawings

[0008]

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Embodiments for Carrying Out the Invention

[0009] In an example of the manufacturing method disclosed in this specification, before the step of forming the first crack and the step of forming the second crack, a step of forming a plurality of the element structures may be further provided such that the plurality of element structures are arranged in a matrix on the second surface of the semiconductor wafer. In the step of forming the first crack and the step of forming the second crack, the first crack and the second crack may be formed along the boundary of the element structure.

[0010] When forming a crack, stress is likely to occur in the vicinity of the surface against which the pressing member is pressed. According to the above configuration, the pressing member is pressed from the first surface side located on the back side thereof, rather than from the second surface side where the element structure is provided. Therefore, even if residual stress exists near the first surface, the influence on the element structure that realizes the function of the semiconductor device can be reduced.

[0011] In an example of the manufacturing method disclosed in this specification, after the step of forming the first crack and the step of forming the second crack and before the step of dividing the semiconductor wafer, a step of forming a metal film on the first surface may be further provided.

[0012] In such a configuration, the metal film formed on the first surface can function as an electrode of the semiconductor device.

[0013] In an example of the manufacturing method disclosed in this specification, the semiconductor wafer may be made of SiC. Also, the crystal axis may be the c-axis.

[0014] (Example) Referring to the drawings, the manufacturing method of the embodiment will be described. FIG. 1 shows a plan view of a semiconductor wafer 2 used in the manufacture of a semiconductor device. The semiconductor wafer 2 has a disc shape. An orientation flat 2f is provided on the outer peripheral surface of the semiconductor wafer 2. A plurality of element regions 3 are arranged in a matrix on the semiconductor wafer 2. In FIG. 1, each element region 3 is schematically shown by a solid line. The element region 3 is a region where an element structure such as a transistor or a diode is formed. For convenience of explanation, the boundary between adjacent element regions 3, which is a line when the semiconductor wafer 2 is later divided into individual element regions 3, is referred to as a division planned line 4. The division planned line 4 is not an actual line marked on the semiconductor wafer 2 but a virtual line. The division planned line 4 may be an actual line or groove drawn on the semiconductor wafer 2 so as to be visible. The semiconductor wafer is composed of SiC. Note that the semiconductor wafer 2 may be composed of other semiconductor materials such as Si or GaN. As shown in FIG. 3 and the like, the semiconductor wafer 2 has a first surface 2a and a second surface 2b located on the back side of the first surface 2a.

[0015] The semiconductor wafer 2 has a hexagonal crystal structure shown in FIG. 2. As shown in FIG. 2, the semiconductor wafer 2 has a plurality of crystal planes. Although not shown, the plane parallel to the paper surface of FIG. 2 is the (0001) plane. In the present embodiment, as shown in FIG. 1, the crystal axis A of SiC (that is, the c-axis) is inclined by about 4° in the x direction with respect to the z direction shown in FIG. 1 (that is, the perpendicular V erected on the second surface 2b of the semiconductor wafer 2). The crystal axis A is not inclined in the y direction with respect to the perpendicular V. That is, the crystal axis A is inclined in the xz plane with respect to the perpendicular V. In other words, in the present embodiment, the (0001) plane (that is, the c-plane) is inclined by about 4° in the x direction with respect to the second surface 2b of the semiconductor wafer 2, the (1-100) plane is a plane parallel to the orientation flat 2f, and the (11-20) plane is inclined by about 4° in the x direction with respect to the plane perpendicular to the orientation flat 2f.

[0016] The manufacturing method of the embodiment includes an element structure forming step, a support plate attaching step, a first crack forming step, a second crack forming step, a metal film forming step, a dicing tape attaching step, a support plate peeling step, a protective member coating step, and a dividing step.

[0017] (Element structure forming step) In the element structure forming step, as shown in FIG. 3, a plurality of element structures 6 are formed on the second surface 2b of the semiconductor wafer 2. The element structure 6 has at least one of an electrode, an insulating film, an n-type region, and a p-type region provided on the second surface 2b side. The element structure 6 includes, for example, a structure for realizing the functions of a semiconductor device, such as a trench or a gate electrode. In this step, the element structures 6 are respectively formed for each element region 3. Therefore, each element structure 6 is formed so as to be arranged in a matrix on the second surface 2b of the semiconductor wafer 2. Further, in this step, while forming the element structure 6, a structure (not shown) having the functions of a transistor or a diode is formed inside the semiconductor wafer 2 of each element region 3. For example, when forming the structure of a MOSFET inside the semiconductor wafer 2, in the region exposed on the second surface 2b, a source region and a body region are formed individually for each element structure 6. On the other hand, in the region exposed on the first surface 2a, a drain region is formed over substantially the entire area of the first surface 2a. That is, the drain region is formed so as to straddle a plurality of element regions 3 at the position exposed on the first surface 2a.

[0018] (Support plate attaching step) In the support plate attaching step, as shown in FIG. 4, a support plate 12 is attached to the second surface 2b of the semiconductor wafer 2. The support plate 12 is attached to the second surface 2b via an adhesive 11. The support plate 12 is made of, for example, glass. The adhesive 11 is, for example, a silicon-based adhesive and has a function of protecting the element structure 6 formed on the second surface 2b of the semiconductor wafer 2 in addition to the function of adhering the semiconductor wafer 2 to the support plate 12. Therefore, here, the adhesive 11 is applied so that the thickness of the adhesive 11 becomes thicker than the thickness of the element structure 6. Thereafter, if necessary, the first surface 2a of the semiconductor wafer 2 is ground by a grinding stone to thin the semiconductor wafer 2. Note that in FIGS. 4 and 5, it should be noted that the semiconductor wafer 2 is drawn with the first surface 2a facing upward.

[0019] (First crack formation step) After thinning the semiconductor wafer 2, a first crack formation step shown in FIG. 5 is performed. In the first crack formation step, a scribing line with a crack 5 is formed inside the semiconductor wafer 2 by pressing a scribing wheel 32 against the first surface 2a of the semiconductor wafer 2 attached to the support plate 12. The scribing wheel 32 is a disk-shaped (annular) member and is pivotally supported by a support device (not shown). In this step, while pressing the scribing wheel 32 against the first surface 2a of the semiconductor wafer 2, it is moved (scanned) along each division planned line 4 extending in the x direction of FIG. 1. When the scribing wheel 32 moves along the division planned line 4, it rolls on the first surface 2a of the semiconductor wafer 2 without slipping, like a tire rolling on a road surface. The peripheral portion of the scribing wheel 32 is sharp, but it does not cut the semiconductor wafer 2 and is only pressed against the first surface 2a. In the first crack formation step, the scribing wheel 32 is pressed against the first surface 2a with a load of about 2.0 N. When the first surface 2a is pressed by the scribing wheel 32, compressive stress is generated in the region of the surface layer of the first surface 2a inside the semiconductor wafer 2. While a scribing line (i.e., a groove) is formed at the pressing portion by the scribing wheel 32, tensile stress is generated inside the semiconductor wafer 2 directly below the region where the compressive stress is generated. The tensile stress is generated in a direction away from the division planned line 4 along the first surface 2a of the semiconductor wafer 2 directly below the region where the compressive stress is generated. Due to this tensile stress, a crack 5 extending along the x direction and in the thickness direction of the semiconductor wafer 2 is formed inside the semiconductor wafer 2. Here, by moving the scribing wheel 32 along the division planned line 4 along the x direction while pressing it against the first surface 2a, the crack 5 is formed along the boundary of the element regions 3 adjacent in the y direction and extending in the thickness direction of the semiconductor wafer 2. The crack 5 is formed near the surface layer of the first surface 2a of the semiconductor wafer 2. The scribing wheel 32 is an example of a "pressing member".

[0020] (Second crack formation step) Next, the second crack formation process is performed. In the second crack formation process, while pressing the scribe wheel 32 against the first surface 2a of the semiconductor wafer 2, it is moved (scanned) along each division planned line 4 extending in the y direction in FIG. 1. This process is the same as the first crack formation process except that the direction in which the scribe wheel 32 is scanned and the load for pressing the scribe wheel 32 against the first surface 2a are about 1.5 N.

[0021] FIG. 6 is a scanning electron microscope image of a cross-section of the semiconductor wafer 2 after the crack 5 is formed by the scribe wheel 32. FIG. 6(a) is a cross-sectional view of the y-z plane near the first surface 2a of the semiconductor wafer 2, and FIG. 6(b) is a cross-sectional view of the x-z plane near the first surface 2a of the semiconductor wafer 2. As shown in FIG. 6, by pressing the scribe wheel 32 along the division planned line 4, it can be seen that cracks 5a and 5b are formed along the boundary of the element region 3 inside the semiconductor wafer 2. Also, the first surface 2a of the semiconductor wafer 2 is observed to have a slightly concave scribe line due to the plastic deformation of the semiconductor wafer 2 by the scribe wheel 32. Further, as shown in FIG. 6(a), in the y-z cross-section, since the crystal axis A of SiC is not inclined with respect to the perpendicular V of the first surface 2a, the first crack 5a is formed to extend in a direction substantially coinciding with the pressing direction of the scribe wheel 32 in the thickness direction of the semiconductor wafer 2. On the other hand, as shown in FIG. 6(b), in the x-z cross-section, since the crystal axis A of SiC is inclined with respect to the perpendicular V of the first surface 2a, the second crack 5b is formed to extend in a direction inclined with respect to the pressing direction of the scribe wheel 32 in the thickness direction of the semiconductor wafer 2.

[0022] (Metal film formation process) Next, a metal film forming process shown in FIG. 7 is performed. In the metal film forming process, a metal film 8 is formed on the first surface 2a of the semiconductor wafer 2. The material constituting the metal film 8 is not particularly limited. For example, it is a multilayer film in which aluminum, nickel, and gold are laminated. The metal film 8 is formed so as to cover substantially the entire area of the first surface 2a. That is, the metal film 8 is formed on the first surface 2a so as to straddle a plurality of element regions 3. The metal film 8 functions as an electrode of the completed semiconductor device.

[0023] (Dicing tape attaching process) Next, a dicing tape attaching process shown in FIG. 8 is performed. In the dicing tape attaching process, a dicing tape 13 is attached to the surface of the metal film 8. The dicing tape 13 is attached so as to cover substantially the entire area of the metal film 8. The dicing tape 13 is fixed to a dicing frame (not shown). Note that it should be noted that from FIG. 8 onward, the semiconductor wafer 2 is drawn with the second surface 2b facing upward again.

[0024] (Support plate peeling process) Next, a support plate peeling process shown in FIG. 9 is performed. In the support plate peeling process, the support plate 12 and the adhesive 11 are peeled from the second surface 2b of the semiconductor wafer 2. Here, for example, by dissolving the adhesive 11 with a solvent, the support plate 12 is peeled from the second surface 2b together with the adhesive 11. As a result, the semiconductor wafer 2 is in a state supported by the dicing tape 13.

[0025] (Protecting member covering process) Next, a protecting member covering process shown in FIG. 10 is performed. In the protecting member covering process, the second surface 2b of the semiconductor wafer 2 is covered with a protecting member 15 by attaching the protecting member 15 so as to straddle the surfaces of the respective element structures 6 in each element region 3 of the semiconductor wafer 2. The material of the protecting member 15 is not particularly limited. For example, a resin or the like can be used. By covering the protecting member 15, the second surface 2b of the semiconductor wafer 2 is protected in subsequent dicing processes and the like.

[0026] (Dicing process) Next, the splitting process shown in FIG. 11 is performed. In the splitting process, the break plate 33 is pressed against the splitting line 4, and the semiconductor wafer 2 is split along the splitting line 4 (along the boundary of the element region 3). Here, first, the semiconductor wafer 2 is placed on two support bases 34. The two support bases 34 are arranged at intervals. When the semiconductor wafer 2 is placed on the support bases 34, the semiconductor wafer 2 is placed such that the interval is located below the position to be split (the position where the break plate 33 is pressed). Thereafter, the break plate 33 is pressed against the semiconductor wafer 2 from the second surface 2b side through the protective member 15. The break plate 33 is a plate-shaped member, and the lower end (the edge pressed against the second surface 2b) portion has a ridgeline shape (sharp blade shape), but it is only pressed without cutting the semiconductor wafer 2.

[0027] Since there is no support base 34 below the break plate 33 (the interval between the two support bases 34 is located), when the break plate 33 is pressed against the second surface 2b, the semiconductor wafer 2 bends so as to enter the interval between the two support bases 34. Here, the crack 5 is formed on the first surface 2a side of the semiconductor wafer 2. Therefore, when the break plate 33 is pressed against the semiconductor wafer 2 from the second surface 2b side, the semiconductor wafer 2 bends about the pressed portion (line) as an axis, and a force is applied to the two element regions 3 adjacent to the splitting position with respect to the crack 5 on the first surface 2a side in a direction to separate them. Also, as described above, a tensile stress is applied around the crack 5. For this reason, when the break plate 33 is pressed against the second surface 2b, the crack 5 extends in the thickness direction of the semiconductor wafer 2, and starting from the crack 5, the semiconductor wafer 2 splits along the crystal plane. Thereby, the semiconductor wafer 2 is divided. Further, since the metal film 8 is formed on the first surface 2a of the semiconductor wafer 2, a force is applied to the metal film 8 in a direction to separate the two element regions 3 adjacent to the splitting position, and the metal film 8 is deformed and divided so as to be separated. Note that instead of the two support bases 34, the entire first surface 2a of the semiconductor wafer 2 may be supported by one elastic support plate (or one or more support bases via one elastic support plate). In this case, although there is an elastic support plate below the break plate 33, when the semiconductor wafer 2 bends, the elastic support plate deforms according to the bending of the semiconductor wafer 2. Therefore, when the break plate 33 is pressed against the second surface 2b, a force is applied to the two element regions 3 adjacent to the splitting position with respect to the crack 5 in a direction to separate them, similar to the case of supporting by the two support bases 34 (when there is no support base 34 below the break plate 33). The break plate 33 is an example of a "splitting member".

[0028] In the dividing step, the step of pressing the above-described break plate 33 against the second surface 2b is repeatedly performed along each dividing planned line 4. As a result, the semiconductor wafer 2 and the metal film 8 can be divided along the boundaries of the respective element regions 3. Thereafter, as shown in FIG. 12, the individualized element regions 3 and the metal film 8 are peeled off from the dicing tape 13. Thereby, a plurality of semiconductor devices 10 having the metal film 8 (electrode) formed on the surface are completed.

[0029] As described above, in the manufacturing method of the present embodiment, since the x direction is along the inclination direction of the crystal axis, when the first crack 5a is formed along the x direction, the formation direction of the first crack 5a in the thickness direction of the semiconductor wafer 2 (that is, the direction in which the crystal axis A in FIG. 6(a) extends) substantially coincides with the pressing direction by the scribe wheel 32 (that is, the direction in which the perpendicular V in FIG. 6(a) extends). Therefore, the stress generated inside the semiconductor wafer 2 due to the formation of the first crack 5a is small. On the other hand, since the y direction is a direction orthogonal to the inclination direction of the crystal axis, when the second crack 5b is formed along the y direction, the formation direction of the second crack 5b in the thickness direction of the semiconductor wafer 2 (that is, the direction in which the crystal axis A in FIG. 6(b) extends) is inclined with respect to the pressing direction by the scribe wheel 32 (that is, the direction in which the perpendicular V in FIG. 6(b) extends). Therefore, the stress generated inside the semiconductor wafer 2 due to the formation of the second crack 5b becomes large. These stresses exist as residual stresses even after the semiconductor wafer 2 is divided. When residual stresses exist, when the manufactured semiconductor device operates repeatedly, a load is likely to be applied in the vicinity of the region where the residual stresses exist, and the reliability of the semiconductor device decreases.

[0030] However, in the manufacturing method of this embodiment, the load (about 1.5 N) of the scribe wheel 32 when forming the second crack 5b is smaller than the load (about 2.0 N) of the scribe wheel 32 when forming the first crack 5a. Therefore, when forming the second crack 5b, the stress caused by the difference between the forming direction of the second crack 5b and the pressing direction of the scribe wheel 32 is reduced. Regions Ra and Rb in FIG. 6 indicate the compressive stress generated inside the semiconductor wafer 2 due to the pressing by the scribe wheel 32. As shown in FIG. 6, by making the load of the scribe wheel 32 in the formation of the second crack 5b smaller than the load of the scribe wheel 32 in the formation of the first crack 5a, the range of region Rb (that is, the magnitude of the compressive stress) can be made substantially equal to the range of region Ra. Thereby, the residual stress of the entire manufactured semiconductor device 10 can be reduced.

[0031] Also, FIG. 13 shows a graph measuring the residual stress of the semiconductor devices of the comparative example (FIG. 13(a)) and the embodiment (FIG. 13(b)). In FIG. 13, the horizontal axis represents the value of the residual stress, and the vertical axis represents the distance from the dividing surface (that is, the surface pressed by the scribe wheel). The residual stress indicates tensile stress as a positive value and compressive stress as a negative value. In the comparative example, the loads of the scribe wheel 32 when forming the first crack 5a and the second crack 5b are substantially equal. As described above, in the x-z cross section, since the crystal axis A is inclined with respect to the pressing direction of the scribe wheel 32, as shown in FIG. 13(a), in the semiconductor device of the comparative example, a large residual stress (about 84 MPa) exists in the vicinity of the dividing surface (that is, the vicinity of the crack). On the other hand, in the semiconductor device 10 of the embodiment, by making the load of the scribe wheel 32 in the formation of the second crack 5b smaller than the load of the scribe wheel 32 in the formation of the first crack 5a, as shown in FIG. 13(b), the residual stress in the x-z cross section can be reduced to a value equivalent to the residual stress (about 55 MPa) in the y-z cross section. Thus, according to the manufacturing method of this embodiment, the residual stress of the entire semiconductor device 10 is reduced, and a highly reliable semiconductor device 10 can be obtained.

[0032] Further, in this embodiment, the element structure 6 is formed on the second surface 2b located on the back side of the first surface 2a, rather than on the first surface 2a side where the scribing wheel 32 is pressed. Therefore, even if residual stress exists on the first surface 2a side, the influence on the element structure 6 that realizes the function of the manufactured semiconductor device 10 can be reduced.

[0033] Note that, in the above-described embodiment, the support plate attachment step, the dicing tape attachment step, and the protective member covering step may not be performed. Further, the metal film formation step may be performed before the first crack formation step and the second crack formation step, or may not be performed. That is, in the technology disclosed in this specification, at least, for a semiconductor wafer in which the crystal axis is inclined with respect to the perpendicular to the surface of the semiconductor wafer, the first crack formation step, the second crack formation step, and the division step may be performed.

[0034] The configuration of the manufacturing method disclosed in this specification is listed below. (Configuration 1) A method for manufacturing a semiconductor device, a step of preparing a semiconductor wafer in which the crystal axis is inclined with respect to the perpendicular to the first surface; a step of forming a first crack extending along the first direction along the inclination direction of the crystal axis on the first surface and extending in the thickness direction of the semiconductor wafer by pressing a pressing member against the first surface with a first load along the first direction; a step of forming a second crack extending along the second direction perpendicular to the first direction on the first surface and extending in the thickness direction of the semiconductor wafer by pressing the pressing member against the first surface with a second load smaller than the first load along the second direction; a step of dividing the semiconductor wafer along the first crack and the second crack by pressing a dividing member against the semiconductor wafer along the first crack and the second crack from the second surface side located on the back side of the first surface; A manufacturing method comprising (Configuration 2) Before the step of forming the first crack and before the step of forming the second crack, a step of forming a plurality of the element structures is further provided such that the plurality of element structures are arranged in a matrix on the second surface of the semiconductor wafer. In the step of forming the first crack and the step of forming the second crack, the first crack and the second crack are formed along the boundary of the element structure. The manufacturing method according to Configuration 1. (Configuration 3) After the step of forming the first crack and the step of forming the second crack and before the step of dividing the semiconductor wafer, a step of forming a metal film on the first surface is further provided. The manufacturing method according to Configuration 1 or 2. (Configuration 4) The semiconductor wafer is made of SiC. The manufacturing method according to any one of Configurations 1 to 3. (Configuration 5) The crystal axis is the c-axis. The manufacturing method according to Configuration 4.

[0035] Although the embodiments have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Also, the technology illustrated in this specification or the drawings achieves a plurality of purposes simultaneously, and has technical utility by achieving one of those purposes itself.

Explanation of Reference Numerals

[0036] 2: Semiconductor wafer, 2a: First surface, 2b: Second surface, 2f: Orientation flat, 3: Element region, 4: Scribing line, 5a: First crack, 5b: Second crack, 6: Element structure, 8: Metal film, 10: Semiconductor device, 32: Scribing wheel, 33: Break plate

Claims

1. A method for manufacturing a semiconductor device (10), comprising: preparing a semiconductor wafer (2) in which a crystal axis (A) is inclined with respect to a perpendicular line of a first surface (2a); forming a first crack (5a) extending along the first direction along the inclination direction of the crystal axis on the first surface by pressing a pressing member (32) against the first surface with a first load on the first surface, the first crack extending along the first direction and in the thickness direction of the semiconductor wafer; forming a second crack (5b) extending along the second direction and in the thickness direction of the semiconductor wafer by pressing the pressing member against the first surface with a second load smaller than the first load along a second direction orthogonal to the first direction on the first surface; dividing the semiconductor wafer along the first crack and the second crack by pressing a dividing member (33) against the semiconductor wafer along the first crack and the second crack from the side of a second surface (2b) located on the back side of the first surface; A manufacturing method comprising the above steps.

2. The method further comprises, before the step of forming the first crack and the step of forming the second crack, a step of forming a plurality of element structures (6) such that the plurality of element structures are arranged in a matrix on the second surface of the semiconductor wafer, In the step of forming the first crack and the step of forming the second crack, the first crack and the second crack are formed along the boundary of the element structure. The manufacturing method according to Claim 1.

3. The manufacturing method according to Claim 1, further comprising, after the step of forming the first crack and the step of forming the second crack and before the step of dividing the semiconductor wafer, a step of forming a metal film (8) on the first surface.

4. The manufacturing method according to Claim 1, wherein the semiconductor wafer is made of SiC.

5. The manufacturing method according to Claim 4, wherein the crystal axis is the c-axis.

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