Method for manufacturing semiconductor device

Abstract

To provide a method for manufacturing a semiconductor device, the method configured to discharge nitrogen gas generated when an altered layer is formed, while appropriately forming the altered layer.SOLUTION: A method for manufacturing a semiconductor device comprises: preparing a processed wafer 30 that is composed of GaN and has a plurality of chip formation regions RA; forming one surface side element constituting portion for the plurality of chip formation regions RA; irradiating an inside of the processed wafer 30 with a laser beam L from the other surface 30b side of the processed wafer 30 to form an altered layer 60; and dividing the processed wafer 30 using the altered layer 60 as a boundary by setting a state where a first holding member 50 is arranged on one surface side of the processed wafer 30 and a second holding member 90 is arranged on the other surface 30b side and by holding the first holding member 50 and the second holding member 90 to apply a force on the processed wafer 30. Nitrogen gas generated when the altered layer 60 is formed is discharged after the altered layer 60 is formed and before the wafer is divided.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a semiconductor device, including a method for dividing a processed wafer made of gallium nitride (hereinafter also simply referred to as GaN). [Background technology]

[0002] A method for manufacturing a semiconductor device by dividing a processed wafer made of GaN has been proposed (see, for example, Patent Document 1). Specifically, in this manufacturing method, a processed wafer made of GaN is prepared, and then a laser beam is irradiated to form an affected layer. In this manufacturing method, holding jigs are arranged to sandwich the processed wafer, and tensile stress or the like is applied to the holding jigs in the thickness direction of the processed wafer, thereby dividing the processed wafer using the affected layer as the starting point for division.

[0003] In this manufacturing method, when forming the altered layer, the processed wafer is placed in a vacuum chamber having a window, and the altered layer is formed by irradiating it with laser light through the window. In this manufacturing method, the nitrogen gas generated when forming the altered layer exceeds the pressure inside the vacuum chamber, so the nitrogen gas is exhausted into the vacuum chamber by the pressure difference. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-183600 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the process of forming the affected layer, the window may bend due to the pressure difference between the pressure inside the vacuum chamber and the pressure outside, which may cause the focal point of the laser beam to shift, making it impossible to form the affected layer at the desired position.

[0006] Therefore, in the above manufacturing method, for example, it is conceivable to increase the thickness of the window to prevent the window from bending due to the pressure difference between the pressure inside the vacuum chamber and the external pressure. However, when forming an altered layer on a processed wafer made of GaN, it is necessary to adjust the focal point at the area where the altered layer is to be formed to generate multiphoton absorption. To generate multiphoton absorption, it is preferable to use an objective lens with a high numerical aperture (i.e., a high NA), and it is preferable to arrange the objective lens and the altered layer formation area close to each other, for example, so that the distance between the objective lens and the altered layer formation area is 10 mm or less. Therefore, if an attempt is made to form a thick window in the above manufacturing method, it is actually difficult to ensure the distance between the objective lens and the altered layer formation area.

[0007] An object of the present disclosure is to provide a method for manufacturing a semiconductor device that appropriately forms an altered layer while discharging nitrogen gas generated during the formation of the altered layer. [Means for solving the problem]

[0008] According to one aspect of the present disclosure, a method for manufacturing a semiconductor device having a semiconductor element formed thereon includes: preparing a processed wafer (30) made of GaN, having one side (30a) and another side (30b) opposite the one side, and having multiple chip formation areas (RA) on the one side; forming one-side element components of the semiconductor element in the multiple chip formation areas; irradiating laser light (L) into the inside of the processed wafer from the other side of the processed wafer to form an altered layer (60) inside the processed wafer along the surface direction of the processed wafer; placing a first holding member (50) on one side of the processed wafer and a second holding member (90) on the other side of the processed wafer; and dividing the processed wafer at the altered layer as a boundary by holding the first holding member and the second holding member and applying force to the processed wafer; and discharging nitrogen gas generated when forming the altered layer after forming the altered layer but before dividing.

[0009] According to this, after the formation of the affected layer, nitrogen gas is discharged before dividing the processed wafer. Therefore, when the first and second holding members are placed on the processed wafer, gaps between the first and second holding members and the processed wafer can be suppressed compared to when nitrogen gas is not discharged. Therefore, when the first and second holding members are gripped and the processed wafer is divided at the affected layer as a boundary, the processed wafer can be easily divided appropriately.

[0010] Furthermore, this manufacturing method does not require placing the processed wafer in a vacuum chamber with a window when forming the altered layer, nor does it require irradiating the processed wafer with laser light through a window. This prevents the laser light from shifting its focal point when irradiating the laser light, allowing the altered layer to be formed appropriately. This also makes it easier to properly divide the processed wafer.

[0011] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and the specific components described in the embodiments described below. [Brief explanation of the drawings]

[0012] [Figure 1A] 1A to 1C are cross-sectional views showing a manufacturing process of a semiconductor device. [Figure 1B] 1B is a cross-sectional view showing a manufacturing process of the semiconductor device subsequent to FIG. 1A. [Figure 1C] 1C is a cross-sectional view showing a manufacturing process of the semiconductor device subsequent to FIG. 1B. [Figure 1D] 1D is a cross-sectional view showing a manufacturing process of the semiconductor device subsequent to FIG. 1C. [Figure 1E] 1D. FIG. [Figure 1F] 1F is a cross-sectional view showing a manufacturing process of the semiconductor device subsequent to FIG. 1E. [Figure 1G] 1F. FIG. [Figure 1H] 1C is a cross-sectional view showing the manufacturing process of the semiconductor device subsequent to FIG. 1G. [Figure 1I] 1C is a cross-sectional view showing the manufacturing process of the semiconductor device subsequent to FIG. 1H. [Figure 1J] 1I. FIG. [Figure 1K] 1J; FIG. [Figure 1L] 1K is a cross-sectional view showing a manufacturing process of the semiconductor device subsequent to FIG. [Figure 1M] 1B is a cross-sectional view showing the manufacturing process of the semiconductor device subsequent to FIG. 1L. [Figure 2A] 1G. FIG. [Figure 2B] 2B is a schematic diagram showing the manufacturing process of the semiconductor device following FIG. 2A. FIG. [Figure 3A] 5A to 5C are cross-sectional views illustrating a manufacturing process of a semiconductor device according to a second embodiment. [Figure 3B] 3C is a cross-sectional view showing the manufacturing process of the semiconductor device subsequent to FIG. 3B. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the following embodiments, identical or equivalent parts will be denoted by the same reference numerals.

[0014] (First embodiment) A method for manufacturing the semiconductor device of the first embodiment will be described with reference to the drawings.

[0015] First, as shown in Fig. 1A, a GaN wafer 10 having one surface 10a and the other surface 10b and in the form of a bulk wafer is prepared as a base substrate. For example, the GaN wafer 10 is doped with silicon, oxygen, germanium, etc., and has an impurity concentration of 5 x 10 17 ~5×10 19 cm -3 The following is used.

[0016] The thickness of the GaN wafer 10 is optional, but for example, a wafer with a thickness of approximately 400 μm is prepared. The GaN wafer 10 of this embodiment has one surface 10a as a gallium surface and the other surface 10b as a nitrogen surface. After the manufacturing process of the semiconductor device 1 described below is performed, this GaN wafer 10 is prepared by reusing a recycled wafer 80 shown in FIG. 1M, which will be described later. Since the other surface 10b of the GaN wafer 10 is irradiated with laser light L as described later, it is preferable that the other surface 10b be ground or polished as necessary to prevent the incidence of the laser light L from being obstructed.

[0017] 1B, an epitaxial film 20 made of GaN and having a thickness of approximately 10 to 100 μm is formed on one surface 10a of the GaN wafer 10, and a processed wafer 30 is prepared in which multiple device formation regions RA are defined by dicing lines DL. Hereinafter, the surface of the processed wafer 30 facing the epitaxial film 20 will be referred to as one surface 30a of the processed wafer 30, and the surface of the processed wafer 30 facing the GaN wafer 10 will be referred to as the other surface 30b of the processed wafer 30. Each device formation region RA is formed on the one surface 30a of the processed wafer 30.

[0018] Although the details are omitted, the epitaxial film 20 of this embodiment is formed by growing n + type epitaxial layer, n - The epitaxial layers are formed in order. + The epitaxial layer of the mold is doped with, for example, silicon, oxygen, germanium, etc., and the impurity concentration is 5×10 17 ~1×10 19 cm -3 It is said to be about. - The epitaxial layer of the mold is doped with silicon or the like, and the impurity concentration is 1×10 16 ~1×10 17 cm -3 In this embodiment, each device formation area RA surrounded by the dicing lines DL has a rectangular shape in plan view.

[0019] Next, as shown in FIG. 1C , a front-side process, which is a typical semiconductor manufacturing process performed on the first surface 10a, is performed. Specifically, the front-side process includes ion implantation, annealing, vapor deposition, wet processes, and the like, as appropriate, to form the first-side component parts of the semiconductor device in each device formation region RA, such as diffusion layers 41, gate electrodes 42, surface electrodes (not shown), wiring patterns, and passivation films. The semiconductor devices employed here may have a variety of configurations, including power devices such as vertical MOS transistors, optical semiconductor devices such as light-emitting diodes, and semiconductor lasers. Thereafter, if necessary, a surface protection film composed of a resist or the like is formed on the first surface 30a of the processed wafer 30.

[0020] Next, as shown in FIG. 1D, a first holding member 50 is placed on one surface 30a of the processed wafer 30. For example, a dicing tape having a base material 51 and an adhesive 52 is used as the first holding member 50. The base material 51 is made of a material that is resistant to warping during the manufacturing process, such as glass, a silicon substrate, or ceramics. The adhesive 52 is made of a material whose adhesive strength can be changed, such as a material whose adhesive strength changes depending on temperature or light. In this case, the adhesive 52 is made of, for example, an ultraviolet-curing resin, wax, or double-sided tape.

[0021] 1E, laser light L is applied from the other surface 30b of the processed wafer 30 to form an affected layer 60 along the surface direction of the processed wafer 30 at a position at a predetermined depth D from the one surface 30a of the processed wafer 30. In other words, an affected layer 60 is formed that extends in a direction intersecting the thickness direction of the processed wafer 30.

[0022] Specifically, a laser device (not shown) is prepared, which includes a laser light source that emits laser light L, a dichroic mirror arranged to change the optical axis of the laser light, a focusing lens for focusing the laser light, and a displaceable stage. When forming the affected layer 60, the position of the stage, etc. is adjusted so that the focusing point of the laser light L is scanned relatively along the surface direction of the processed wafer 30. As a result, the affected layer 60 is formed on the processed wafer 30 along the surface direction. More specifically, by irradiating the laser light L, nitrogen gas is generated and the affected layer 60 in which gallium is precipitated is formed.

[0023] In this case, in this embodiment, it is not necessary to place the processed wafer 30 in a vacuum chamber having a window, and it is also not necessary to irradiate the processed wafer 30 with the laser light L through a window. Therefore, it is possible to prevent the focal point of the laser light L from shifting, and it is possible to appropriately form the affected layer 60. Note that when the affected layer 60 is formed, as will be described in detail later, there is a possibility that a bulge will be formed on one surface 30a of the processed wafer 30 due to nitrogen gas remaining inside the affected layer 60 (i.e., inside the processed wafer 30).

[0024] The predetermined depth D when forming the affected layer 60 is set depending on the ease of handling of the semiconductor device 1, the target on-resistance, etc., which will be described later, and is, for example, about 10 to 200 μm. The location where the affected layer 60 is formed varies depending on the thickness of the epitaxial film 20, and the affected layer 60 is formed either inside the epitaxial film 20, at the boundary between the epitaxial film 20 and the GaN wafer 10, or inside the GaN wafer 10. Note that FIG. 1E shows an example in which the affected layer 60 is formed at the boundary between the epitaxial film 20 and the GaN wafer 10.

[0025] Furthermore, although not particularly limited, in this embodiment, the laser light L used to form the affected layer 60 is solid-state laser light, and a green laser with a wavelength of 532 nm is used. The processing point output, pulse width, etc. of the laser light L are adjusted as appropriate so as to form the affected layer 60. Note that although an example in which a green laser is used as the laser light L has been described here, the laser light L may also be a YAG (yttrium, aluminum, garnet) laser with a wavelength of 1064 nm, a carbon dioxide laser with a wavelength of 10.6 μm, or the like.

[0026] In the following description, the portion of the processed wafer 30 on the one surface 30a side of the deteriorated layer 60 will be referred to as a semiconductor wafer 70, and the portion of the processed wafer 30 on the other surface 30b side of the deteriorated layer 60 will be referred to as a recycled wafer 80.

[0027] 1F, in this embodiment, the first holding member 50 is peeled off. For example, when peeling off the first holding member 50, the adhesive strength of the adhesive 52 that is attached to the processed wafer 30 of the first holding member 50 is reduced, for example, by UV irradiation if the adhesive 52 is made of a UV resin adhesive.

[0028] Thereafter, as shown in FIG. 1G, the processed wafer 30 is placed in a vacuum chamber 210 that is connected to a vacuum pump 200 and can be evacuated, and a step of discharging the nitrogen gas is performed.

[0029] Specifically, as shown in FIG. 2A , when the altered layer 60 is formed, nitrogen gas remains inside the processed wafer 30, forming bubbles 31, which can form bulges 32 on the first surface 30a of the processed wafer 30. For this reason, in this embodiment, the processed wafer 30 is placed in a vacuum chamber 210, and the vacuum chamber 210 is evacuated. As a result, the nitrogen gas, which is at normal pressure, is higher than the pressure inside the vacuum chamber 210, and the nitrogen gas is discharged into the vacuum chamber 210. Therefore, as shown in FIG. 2B , the bulges 32 of the processed wafer 30 become smaller as the bubbles 31 become smaller. Note that FIG. 2B illustrates a state in which the bulges 32 have disappeared.

[0030] At this time, by heating the processed wafer 30 to 40°C or higher, which is above the melting point of gallium, the gallium present in the altered layer 60 is liquefied, making it easier to create a path for the nitrogen gas to travel and to make it easier to discharge the nitrogen gas.

[0031] As described above, the affected layer 60 is formed on the one surface 30a of the processed wafer 30, so the bulge 32 is likely to form on the one surface 30a. However, even if the bulge 32 is formed on the other surface 30b of the processed wafer 30, the bulge 32 on the other surface 30b also becomes smaller as the bubbles 31 become smaller.

[0032] 1H, the first holding member 50 is again placed on one side 30a of the processed wafer 30, and the second holding member 90 is placed on the other side 30b of the processed wafer 30. The second holding member 90 is, for example, composed of a dicing tape having a base material 91 and an adhesive 92, similar to the first holding member 50, but may have a different configuration from the first holding member 50. Then, the first holding member 50 and the second holding member 90 are gripped and a tensile force or the like is applied in the thickness direction of the processed wafer 30, thereby dividing the processed wafer 30 into a semiconductor wafer 70 and a recycled wafer 80, with the affected layer 60 as the boundary (i.e., the starting point of branching).

[0033] 1G is performed without discharging the nitrogen gas from the affected layer 60, the first holding member 50 is positioned with a large bulge 32 on the one surface 30a of the processed wafer 30. In this case, the periphery of the bulge 32 on the one surface 30a of the processed wafer 30 may not be bonded to the first holding member 50 by the bulge 32. If the processed wafer 30 is divided in this state at the affected layer 60 as shown in FIG. 1H, the tensile force is not properly applied to the portion not bonded to the first holding member 50. As a result, the processed wafer 30 cannot be properly divided at the affected layer 60.

[0034] However, in this embodiment, the nitrogen gas in the affected layer 60 is discharged before dividing the processed wafer 30, thereby reducing the bulge 32 on the one surface 30a of the processed wafer 30. This makes it less likely that any portion of the one surface 30a of the processed wafer 30 will be left unheld by the first holding member 50, making it easier to divide the processed wafer 30 appropriately.

[0035] In the following description, the divided surface of the semiconductor wafer 70 will be referred to as the other surface 70b, and the surface opposite to the other surface 70b will be referred to as the first surface 70a. Also, in the description of the recycled wafer 80, the divided surface will be referred to as the first surface 80a.

[0036] Thereafter, as shown in FIG. 1I, the remaining semiconductor manufacturing process involves a back surface process for forming a back surface electrode 43 and the like on the other surface 70b of the semiconductor wafer 70.

[0037] Before performing the backside process for the backside electrode 43, etc., a step of planarizing the other surface 70b of the semiconductor wafer 70 by a CMP (short for chemical mechanical polishing) method or the like may be performed as needed. FIG. 1I shows the planarized other surface 70b of the semiconductor wafer 70. Furthermore, after performing the step of forming the backside electrode 43, a heat treatment such as laser annealing may be performed as needed to establish ohmic contact between the backside electrode 43 and the other surface 70b of the semiconductor wafer 70.

[0038] 1J, a third holding member 100 is placed on the other surface 70b of the semiconductor wafer 70, that is, on the side of the back electrode 43. The third holding member 100 is, for example, made of a dicing tape having a base material 101 and an adhesive 102, similar to the first holding member 50, but may have a different configuration from the first holding member 50.

[0039] Thereafter, as shown in FIG. 1K, the first holding member 50 attached to the one surface 70a of the semiconductor wafer 70 is peeled off.

[0040] 1L, grooves 110 are formed along dicing lines DL using a dicing saw, laser dicing, or the like, and the semiconductor wafer 70 is diced into individual device units to form the semiconductor devices 1. At this time, it is preferable to adjust the dicing depth so that the third holding member 100 remains connected without being cut while the semiconductor wafer 70 is divided into device units.

[0041] Subsequent steps for the semiconductor device 1 are not shown, but for example, the following steps are performed. That is, the third holding member 100 is expanded, and the spacing between each semiconductor device 1 is increased at the diced-cut portions. Thereafter, the adhesive strength of the adhesive 102 is weakened by heat treatment or light irradiation, and the semiconductor device 1 is picked up. In this way, the semiconductor device 1 is manufactured.

[0042] 1M, recycled wafer 80 constructed in the step of FIG. 1H is subjected to a CMP method or the like using a polishing apparatus 120 or the like to flatten one surface 80a. Then, flattened recycled wafer 80 is used as GaN wafer 10, and the steps from FIG. 1A onward are performed again. In this way, GaN wafer 10 can be used multiple times to construct semiconductor device 1.

[0043] According to the present embodiment described above, after the affected layer 60 is formed, a step of discharging nitrogen gas is performed before dividing the processed wafer 30. Therefore, when the first holding member 50 and the second holding member 90 are placed on the processed wafer 30, it is possible to prevent gaps from forming between the first holding member 50 and the second holding member 90 and the processed wafer 30, compared to when the step of discharging nitrogen gas is not performed. Therefore, when the first holding member 50 and the second holding member 90 are gripped and the processed wafer 30 is divided starting from the affected layer 60, it is possible to facilitate appropriate division of the processed wafer 30.

[0044] Furthermore, in this embodiment, when forming the affected layer 60, it is not necessary to place the processed wafer 30 in a vacuum chamber or the like having a window, and it is also not necessary to irradiate the processed wafer 30 with the laser light L passing through a window. Therefore, when irradiating the laser light L, it is possible to prevent the focal point of the laser light L from shifting, and it is possible to appropriately form the affected layer 60. This makes it easier to appropriately divide the processed wafer 30.

[0045] (1) In this embodiment, when nitrogen gas is exhausted, the processed wafer 30 is placed in the vacuum chamber 210, thereby exhausting the nitrogen gas to the outside. Therefore, the nitrogen gas can be exhausted to the outside with a simple configuration.

[0046] (2) In this embodiment, when discharging nitrogen gas, the processed wafer 30 is heated to 40°C or higher, which is above the melting point of gallium. This liquefies the gallium present in the altered layer 60, making it easier to create a path for the nitrogen gas to travel, and facilitating the discharge of the nitrogen gas.

[0047] (Second embodiment) A second embodiment will be described. This embodiment is different from the first embodiment in that the method of discharging nitrogen gas is changed. As the rest is the same as the first embodiment, a description thereof will be omitted here.

[0048] In this embodiment, as shown in FIG. 3A, after the process up to the step in FIG. 1F is performed, the processed wafer 30 is sandwiched between a pair of jigs 230 in the thickness direction. In this embodiment, auxiliary members 220 are placed on one surface 30a and the other surface 30b of the processed wafer 30, and the processed wafer 30 is sandwiched between the pair of jigs 230 in the thickness direction via the auxiliary members 220. The auxiliary members 220 are made of, for example, a rigid plate such as a metal. Then, the jigs 230 press the processed wafer 30 in the thickness direction, thereby discharging the nitrogen gas to the outside.

[0049] As a result, as shown in Fig. 3B, the bubbles 31 become smaller and the bulging portions 32 of the processed wafer 30 become smaller. Note that Fig. 3B illustrates a state in which the bulging portions 32 have disappeared.

[0050] Also in this embodiment, when discharging nitrogen gas, the processed wafer 30 is heated to 40°C or higher, which is above the melting point of gallium, making it easier to create a path for the nitrogen gas to travel and to discharge the nitrogen gas.

[0051] Thereafter, the steps from FIG. 1H onwards are carried out to manufacture the semiconductor device 1 in the same manner as in the first embodiment.

[0052] In the present embodiment described above, the step of discharging nitrogen gas is performed after the altered layer 60 is formed and before the processed wafer 30 is divided. Therefore, the same effects as those of the first embodiment can be obtained.

[0053] (1) In this embodiment, when discharging nitrogen gas, the nitrogen gas is discharged to the outside by pressing the processed wafer 30 in the thickness direction using the jig 230. Therefore, nitrogen gas can be discharged to the outside with a simple configuration.

[0054] (Other embodiments) Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

[0055] For example, in each of the above embodiments, an example has been described in which the grooves 110 are formed along the dicing lines DL after dividing the processed wafer 30, but the grooves 110 may be formed before dividing the processed wafer 30. More specifically, the grooves 110 may be formed before forming the affected layer 60, and the affected layer 60 may be formed so as to intersect with the grooves 110. In this way, nitrogen gas in the affected layer 60 can be discharged from the grooves 110 as well, making it even easier to discharge the nitrogen gas.

[0056] Furthermore, in each of the above embodiments, the nitrogen gas exhaust step does not need to be performed while the processed wafer 30 is heated to the melting point of gallium or higher.

[0057] Furthermore, in each of the above embodiments, an example has been described in which the first holding member 50 is peeled off from the processed wafer 30 in the step of FIG. 1F before the step of discharging the nitrogen gas. However, the step of discharging the nitrogen gas may be performed without performing the step of FIG. 1F and with the first holding member 50 remaining on the processed wafer 30. In this case, however, in the first embodiment, after the step of discharging the nitrogen gas is performed, an area that is not bonded to the first holding member 50 may be generated around the portion where the bulge 32 was formed. For this reason, in the first embodiment, if the step of discharging the nitrogen gas is performed with the first holding member 50 remaining on the processed wafer 30, it is preferable to ensure that the periphery of the portion where the bulge 32 was formed is also bonded to the first holding member 50 by pressing or the like.

[0058] In each of the above embodiments, in the step of FIG. 1I, the back surface electrode 43 may be formed without polishing the other surface 70b of the semiconductor wafer 70. For example, when forming an optical semiconductor element or the like as the semiconductor element, forming a concave-convex structure on the other surface of the semiconductor device 1 to be manufactured makes it possible to effectively extract light from the other surface. Immediately after dividing the processed wafer 30, the altered layer 60 remains on the other surface 70b of the semiconductor wafer 70, resulting in the formation of minute concave-convex portions. Therefore, when forming an optical semiconductor element, the concave-convex portions of the altered layer 60 may be utilized without polishing the other surface 70b of the semiconductor wafer 70.

[0059] 1B, the epitaxial film 20 may also be formed on the other surface 10b of the GaN wafer 10. This makes it easier to leave a predetermined thickness or more as a recycled wafer 80 even when an altered layer 60 is formed in the GaN wafer 10, thereby increasing the number of times the wafer can be reused.

[0060] The above embodiments may also be combined, i.e., the first embodiment and the second embodiment may be combined, and the processed wafer 30 may be placed in the vacuum chamber 210 and pressed in the thickness direction by the jig 230. [Explanation of symbols]

[0061] 30 processed wafers 30a one side 30b Other side 60 Degenerated Layer 70 semiconductor wafers 80 recycled wafers

Claims

1. A method for manufacturing a semiconductor device in which a semiconductor element is formed, comprising: A processed wafer (30) is prepared, the processed wafer (30) is made of gallium nitride, has one surface (30a) and another surface (30b) opposite to the one surface, and has a plurality of chip forming areas (RA) on the one surface side; forming one-surface-side element components of the semiconductor element in the plurality of chip formation regions; By irradiating the inside of the processed wafer with laser light (L) from the other surface side of the processed wafer, an affected layer (60) is formed inside the processed wafer along the surface direction of the processed wafer; a first holding member (50) is disposed on one side of the processed wafer and a second holding member (90) is disposed on the other side of the processed wafer, and the first holding member and the second holding member are gripped to apply force to the processed wafer, thereby dividing the processed wafer at the affected layer as a boundary; A method for manufacturing a semiconductor device, comprising the steps of: after forming the altered layer and before dividing the layer, discharging nitrogen gas generated when the altered layer is formed.

2. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the nitrogen gas is discharged by placing the processed wafer in a vacuum chamber.

3. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the nitrogen gas is discharged by pressing the processed wafer in a thickness direction.

4. 4. The method for manufacturing a semiconductor device according to claim 2, wherein the nitrogen gas is discharged while the processed wafer is heated to a temperature equal to or higher than the melting point of gallium.

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