Affected layer forming apparatus and semiconductor device manufacturing method

Abstract

To provide an alteration layer in the whole target region.SOLUTION: An alteration layer formation device includes a laser irradiation device (40), an imaging device (50), and a controller (60). The controller executes the steps of: irradiating a target region of a compound semiconductor substrate (12) with a laser (L) by a laser irradiation device to form an alteration layer (14) in the compound semiconductor substrate of the target region; taking an image of the compound semiconductor substrate in the target region by the imaging device and specifying an alteration layer no formation region (16), which is a region of the target region where the alteration layer is not formed, on the basis of the image; and a step of irradiating the alteration layer no formation region of the compound semiconductor substrate with a laser by the laser irradiation device to form the alteration layer in the compound semiconductor substrate in the alteration layer no formation region.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to an affected layer forming apparatus and a method for manufacturing a semiconductor device.

[0002] In the method for manufacturing a semiconductor device disclosed in Patent Document 1, a compound semiconductor substrate is irradiated with a laser to form an altered layer inside the compound semiconductor substrate. The altered layer is formed so as to extend along the surface of the compound semiconductor substrate. By forming the altered layer in this manner, the compound semiconductor substrate can be processed. For example, thinner compound semiconductor substrates can be obtained by dividing the compound semiconductor substrate along the altered layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-102520 Summary of the Invention [Problem to be solved by the invention]

[0004] When forming an altered layer inside a compound semiconductor substrate, it may not be possible to form the altered layer over the entire target area. For example, an equipment malfunction in a laser irradiation device may prevent the altered layer from being formed in part of the target area. Furthermore, the laser may be blocked by foreign matter or a rough surface on the surface of the compound semiconductor substrate, preventing the altered layer from being formed in part of the target area. If the altered layer cannot be formed over the entire target area, the compound semiconductor substrate cannot be properly processed. For example, when dividing a compound semiconductor substrate along the altered layer, it may not be possible to properly divide the compound semiconductor substrate in areas where the altered layer cannot be formed. This specification proposes a technology for forming an altered layer over the entire target area more reliably than conventional techniques. [Means for solving the problem]

[0005] The affected layer forming apparatus disclosed in this specification includes a laser irradiation device, an imaging device, and a control device. The control device executes a first affected layer forming step, a damaged layer unformed region specifying step, and a second damaged layer forming step. In the first affected layer forming step, the control device forms an affected layer inside the compound semiconductor substrate in the target region by irradiating a laser beam into the target region of the compound semiconductor substrate using the laser irradiation device. In the damaged layer unformed region specifying step, the control device captures an image of the compound semiconductor substrate in the target region using the imaging device and specifies an affected layer unformed region in the target region based on the image. In the second damaged layer forming step, the control device forms the affected layer inside the compound semiconductor substrate in the damaged layer unformed region by irradiating a laser beam into the damaged layer unformed region of the compound semiconductor substrate using the laser irradiation device.

[0006] In this altered layer forming apparatus, a degraded layer unformed area specifying step is performed after the first degraded layer forming step. In the degraded layer unformed area specifying step, a degraded layer unformed area in which no degraded layer has been formed is specified within the target area. Therefore, if an abnormality in the first degraded layer forming area prevents a degraded layer from being formed in part of the target area, the degraded layer unformed area is specified in the degraded layer unformed area specifying step. In the second degraded layer forming step performed after the degraded layer unformed area specifying step, a laser is irradiated into the degraded layer unformed area, thereby forming a degraded layer inside the compound semiconductor substrate in the degraded layer unformed area. Therefore, with this altered layer forming apparatus, it is possible to form a degraded layer more reliably throughout the entire target area than conventional methods.

[0007] The semiconductor device manufacturing method disclosed herein manufactures a semiconductor device using a damaged layer forming apparatus. The damaged layer forming apparatus includes a laser irradiation device and an imaging device. The manufacturing method includes a first damaged layer forming step, a damaged layer unformed region specifying step, and a second damaged layer forming step. In the first damaged layer forming step, a damaged layer is formed inside the compound semiconductor substrate in the target region by irradiating a laser beam into the target region of the compound semiconductor substrate using the laser irradiation device. In the damaged layer unformed region specifying step, an image of the compound semiconductor substrate in the target region is captured using the imaging device, and a damaged layer unformed region in the target region is specified based on the image. In the second damaged layer forming step, the damaged layer is formed inside the compound semiconductor substrate in the damaged layer unformed region by irradiating a laser beam into the damaged layer unformed region of the compound semiconductor substrate using the laser irradiation device.

[0008] In this manufacturing method, if a degraded layer is not formed in part of the target area due to some abnormality in the first degraded-layer-forming region, the degraded-layer-free region is identified in the degraded-layer-free region identifying step. Then, a degraded layer is formed in the degraded-layer-free region in the second degraded-layer forming step. Therefore, this manufacturing method makes it possible to form a degraded layer over the entire target area more reliably than conventional methods. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a configuration diagram of the affected layer forming apparatus of the first embodiment. [Figure 2] FIG. [Figure 3] 3 is a flowchart showing a method for manufacturing a semiconductor device according to the first embodiment. [Figure 4] FIG. 2 shows an image of the GaN substrate 12 taken by the camera 50. [Figure 5] FIG. 10 is an explanatory diagram of a step of specifying an area where an altered layer is not formed. [Figure 6] FIG. 10 is an explanatory diagram of a step of specifying an area where an altered layer is not formed. [Figure 7] FIG. 10 is an explanatory diagram of a step of specifying an area where an altered layer is not formed. [Figure 8] FIG. [Figure 9] 10A to 10C are diagrams showing peeling defects in a substrate dividing step. [Figure 10] 10A to 10C are diagrams showing peeling defects in a substrate dividing step. [Figure 11] FIG. 10 is a configuration diagram of a modified layer forming apparatus according to a second embodiment. [Figure 12] FIG. 10 is a configuration diagram of a modified layer forming apparatus according to a third embodiment. [Figure 13] FIG. 10 is a configuration diagram of a modified layer forming apparatus according to a fourth embodiment. [Figure 14] 10 is a flowchart showing a method for manufacturing a semiconductor device according to a fourth embodiment. [Figure 15] FIG. 10 is a configuration diagram of a modified layer forming apparatus according to a fifth embodiment. [Figure 16] 10 is a flowchart showing a method for manufacturing a semiconductor device according to a sixth embodiment. [Figure 17] 13 is a flowchart showing a method for manufacturing a semiconductor device according to a seventh embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] In the modified layer forming apparatus disclosed in the present specification as an example, the compound semiconductor substrate may be made of a gallium compound.

[0011] The affected layer forming apparatus according to the present invention may further include a substrate dividing device. In this case, the control device may further perform a step of dividing the compound semiconductor substrate along the affected layer by the substrate dividing device after forming the affected layer inside the compound semiconductor substrate in the affected-layer-free region.

[0012] According to this configuration, the compound semiconductor substrate can be divided into thinner plates.

[0013] In an example of the affected layer forming apparatus disclosed in the present specification, the step of identifying the affected layer-free region may include identifying a coordinate range of the affected layer-free region in a state where a coordinate system is set based on a first feature point in the appearance of the compound semiconductor substrate. In this case, the step of forming the affected layer inside the compound semiconductor substrate within the affected layer-free region may include irradiating a laser within the coordinate range in a state where a coordinate system is set based on a second feature point in the appearance of the compound semiconductor substrate.

[0014] The first and second feature points may be feature points in the outer shape of the compound semiconductor substrate (e.g., orientation flat, notch, etc.) or feature points on the surface of the compound semiconductor substrate (e.g., alignment mark, etc.). The second feature point may be the same feature point as the first feature point, or may be a feature point different from the first feature point.

[0015] According to this configuration, the laser can be accurately irradiated into the region where no affected layer is formed.

[0016] An example of a method for manufacturing a semiconductor device disclosed in the present specification may further include a step of cleaning the compound semiconductor substrate after the step of identifying the affected layer-free region and before the step of forming the affected layer inside the compound semiconductor substrate in the affected layer-free region.

[0017] According to this configuration, when a region where an altered layer is not formed is formed due to foreign matter adhering to the surface of the compound semiconductor substrate, the foreign matter can be removed by cleaning before the laser is irradiated onto the region where an altered layer is not formed, thereby more reliably forming an altered layer inside the compound semiconductor substrate in the region where an altered layer is not formed.

[0018] An example of a method for manufacturing a semiconductor device disclosed in this specification may further include a step of planarizing a surface of the compound semiconductor substrate after the step of identifying the affected layer unformed region and before the step of forming the affected layer inside the compound semiconductor substrate in the affected layer unformed region.

[0019] According to this configuration, when a rough surface portion (i.e., a portion with a high surface roughness) exists on the surface of the compound semiconductor substrate, which causes an affected layer-free region, the rough surface portion can be removed by the planarization process, and then the affected layer-free region can be irradiated with a laser. Therefore, an affected layer can be more reliably formed inside the compound semiconductor substrate in the affected layer-free region. [Example]

[0020] 1 forms an affected layer 14 on a gallium nitride substrate 12 (hereinafter referred to as GaN substrate 12). The affected layer forming apparatus 10 includes a substrate transfer device 20, a stage 30, a laser light source 40, a camera 50, and a control device 60.

[0021] The substrate transfer device 20 transfers the GaN substrate 12 into and out of the altered layer forming apparatus 10. The substrate transfer device 20 places the GaN substrate 12, which has been transferred into the altered layer forming apparatus 10, on the stage 30. FIG. 2 shows the GaN substrate 12. As shown in FIG. 2, the GaN substrate 12 has orientation flats 12a and 12b. The substrate transfer device 20 has a built-in coarse alignment device. The coarse alignment device detects external feature points (e.g., orientation flats 12a and 12b) of the GaN substrate 12 before placing the GaN substrate 12 on the stage 30. The substrate transfer device 20 adjusts the position and angle (the angle around the center of the GaN substrate 12) of the GaN substrate 12 based on the detected feature points, and then places the GaN substrate 12 on the stage 30.

[0022] The stage 30 is movable in the x, y, and z directions. The x direction is a direction parallel to the top surface of the stage 30. The y direction is a direction parallel to the top surface of the stage 30 and perpendicular to the x direction. The z direction is a direction perpendicular to the top surface of the stage 30.

[0023] The laser light source 40 is disposed above the stage 30. The laser light source 40 emits a laser beam L. A half mirror 42 and a condenser lens 44 are provided directly above the stage 30 as an optical system for the laser beam L. The laser light source 40 emits the laser beam L toward the lower surface of the half mirror 42. The laser beam L is reflected by the lower surface of the half mirror 42. The laser beam L reflected by the half mirror 42 passes through the condenser lens 44 and is irradiated onto the GaN substrate 12 on the stage 30. The condenser lens 44 condenses the laser beam L so that the focal point of the laser beam L is formed inside the GaN substrate 12.

[0024] Camera 50 is disposed above stage 30. In addition, mirror 52 is disposed directly above half mirror 42 as part of the optical system of camera 50. Light that passes through half mirror 42 and is reflected by mirror 52 enters camera 50. Camera 50 captures an image of GaN substrate 12 placed on stage 30 via mirror 52 and half mirror 42. Although not shown, affected layer forming apparatus 10 may also have an illumination device that irradiates light onto upper surface 12c of GaN substrate 12 when camera 50 is capturing an image.

[0025] The control device 60 is electrically connected to the substrate transport device 20, the stage 30, the laser light source 40, and the camera 50. The control device 60 controls the substrate transport device 20, the stage 30, the laser light source 40, and the camera 50.

[0026] Next, a description will be given of a manufacturing method of the semiconductor device of Example 1. Fig. 3 shows the manufacturing method of Example 1. The manufacturing method of Example 1 includes a substrate carrying-in step, a precision alignment step, an affected layer forming step, an affected layer unformed region specifying step, an affected layer reforming step, and a substrate dividing step.

[0027] (Board loading process) In the substrate loading step, control device 60 causes substrate transfer device 20 to transfer GaN substrate 12 onto stage 30. GaN substrate 12 is composed of a single crystal of GaN. In the substrate loading step, substrate transfer device 20 adjusts the position and angle of GaN substrate 12 using a coarse alignment device, and then places GaN substrate 12 on stage 30. Therefore, GaN substrate 12 is placed on stage 30 with relatively high positional accuracy and angular accuracy.

[0028] (Precise alignment process) Next, the control device 60 performs a fine alignment process. In the fine alignment process, the control device 60 uses a camera (e.g., camera 50 or a fine alignment camera not shown) to capture an image of the GaN substrate 12 on the stage 30 and detects the positions of the orientation flats 12a and 12b of the GaN substrate 12. The control device 60 then calculates the position of the origin O based on the positions of the orientation flats 12a and 12b. For example, as shown in FIG. 2, the control device 60 calculates the intersection of the extensions of the orientation flats 12a and 12b as the origin O. The control device 60 stores the position of the origin O. In each subsequent process, the control device 60 controls the position on the GaN substrate 12 based on an xy coordinate system consisting of a coordinate indicating the position in the x direction relative to the origin O (hereinafter referred to as the x coordinate) and a coordinate indicating the position in the y direction relative to the origin O (hereinafter referred to as the y coordinate). Furthermore, in the fine alignment step, the control device 60 adjusts the position of the stage 30 in the z direction so that the focal point of the laser L is formed at a predetermined depth inside the GaN substrate 12.

[0029] (Deteriorated layer formation process) Next, the control device 60 performs the affected layer formation process. In the affected layer formation process, the control device 60 activates the laser light source 40. The laser light L emitted from the laser light source 40 is reflected by the half mirror 42, passes through the condenser lens 44, and is irradiated onto the GaN substrate 12 on the stage 30. The condenser lens 44 forms a focus of the laser light L inside the GaN substrate 12 (i.e., within the thickness of the GaN substrate 12). At the position of the focus of the laser light L, the GaN substrate 12 is heated and decomposed. As a result, an affected layer 14 is formed inside the GaN substrate 12 (more specifically, at the position of the focus of the laser light L). The affected layer 14 is a layer having a structure different from that of the original GaN single crystal. The affected layer 14 is composed of, for example, a gallium precipitate layer. The strength of the affected layer 14 is lower than that of the GaN single crystal. In the affected layer formation process, the control device 60 irradiates the GaN substrate 12 with the laser while moving the stage 30 in the x and y directions. As a result, the control device 60 irradiates the laser onto the entire area of ​​the GaN substrate 12 in the x and y directions. Therefore, the affected layer 14 is formed over the entire area of ​​the GaN substrate 12 in the x and y directions. In this embodiment, the target area for forming the affected layer 14 is the entire area of ​​the GaN substrate 12 in the x and y directions.

[0030] In the affected layer forming step, affected layer 14 may not be formed in some regions of GaN substrate 12 due to factors such as equipment malfunction, foreign matter adhering to upper surface 12c of GaN substrate 12, or rough surfaces present on upper surface 12c of GaN substrate 12. Hereinafter, the region in which affected layer 14 is formed when GaN substrate 12 is viewed from above will be referred to as affected layer formed region 15, and the region in which affected layer 14 is not formed when GaN substrate 12 is viewed from above will be referred to as affected layer unformed region 16.

[0031] (Process for identifying areas where an altered layer has not yet been formed) Next, the control device 60 performs an affected-layer-free region identifying step. In the affected-layer-free region identifying step, the control device 60 uses the camera 50 to capture an image of the GaN substrate 12. More specifically, the control device 60 captures an image of the entire GaN substrate 12 in the x and y directions from the upper surface 12c side of the GaN substrate 12. FIG. 4 shows an example of an image of the GaN substrate 12 captured in the affected-layer-free region identifying step. As shown in FIG. 4, in the image captured by the camera 50, the affected-layer-free region 16 appears as a whitish region compared to the affected-layer-free region 15. The control device 60 identifies the affected-layer-free region 15 and the affected-layer-free region 16 based on the captured image. FIGS. 5 to 7 are enlarged images of the affected-layer-free region 15 and the affected-layer-free region 16. FIG. 5 is an image captured by the camera 50. In FIG. 5, the gray region is the affected-layer-free region 15, and the white region is the affected-layer-free region 16. The control device 60 calculates an image by binarizing the brightness value of each pixel of the image captured by the camera 50 using a value between white and gray as a threshold. For example, the control device 60 calculates the image of FIG. 6 by binarizing the image of FIG. 5. Next, the control device 60 performs noise removal processing on the binarized image. For example, the control device 60 performs noise removal processing on the image of FIG. 5 to calculate the image shown in FIG. 6 (i.e., an image in which minute white and black areas have been removed and the boundaries between the white and black areas have been smoothed). In the image after noise removal processing, the control device 60 identifies the black area as the affected-layer-formed area 15 and the white area as the affected-layer-free area 16. The control device 60 calculates a coordinate range 16r of the affected-layer-free area 16 based on the image after noise removal processing. The coordinate range 16r of the affected-layer-free area 16 is a coordinate range represented by the xy coordinate system set in the fine alignment process. The control device 60 stores the calculated coordinate range 16r.

[0032] 3, the control device 60 determines whether or not a degraded layer-free region 16 exists after the degraded layer-free region specifying step. If a degraded layer-free region is specified in the degraded layer-free region specifying step, the control device 60 performs a degraded layer reforming step. On the other hand, if a degraded layer-free region is not specified in the degraded layer-free region specifying step, the control device 60 performs a substrate dividing step.

[0033] (Deteriorated layer reforming process) If an affected-layer-free region 16 is present, the control device 60 performs a damaged-layer reforming step. In the damaged-layer reforming step, the control device 60 irradiates a laser beam L within a coordinate range 16r of the affected-layer-free region 16 identified in the affected-layer-free region identifying step. More specifically, the control device 60 first moves the GaN substrate 12 using the stage 30 so that the irradiation position of the laser beam L (i.e., the position where the focus is formed) is located within the coordinate range 16r. Next, the control device 60 activates the laser light source 40 to irradiate the laser beam L within the coordinate range 16r (i.e., within the affected-layer-free region 16). This forms an affected layer 14 within the affected-layer-free region 16. The control device 60 irradiates the GaN substrate 12 with the laser beam while moving the stage 30 in the x and y directions. This allows the control device 60 to form an affected layer 14 throughout the entire coordinate range 16r. That is, the control device 60 forms the affected layer 14 over the entire area (i.e., the entire area in the x and y directions) of the affected layer unformed region 16. Note that, if there are multiple affected layer unformed regions 16, the control device 60 forms the affected layer 14 over the entire area of ​​each of the affected layer unformed regions 16.

[0034] The control device 60 performs the affected layer unformed region specifying step again after the affected layer reforming step. The control device 60 repeatedly performs the affected layer reforming step and the affected layer unformed region specifying step until the affected layer unformed region 16 disappears. As a result, the affected layer 14 is formed over the entire area of ​​the GaN substrate 12 in the x and y directions.

[0035] (Substrate division process) When the affected-layer-free region 16 is gone, the control device 60 causes the substrate transfer device 20 to transport the GaN substrate 12 out of the affected-layer forming apparatus 10. Then, a substrate dividing process is performed. In the substrate dividing process, the GaN substrate 12 is divided along the affected layer 14, as shown in FIG. 8 . That is, in the substrate dividing process, a force is applied to the portion 12e on the upper surface 12c side of the GaN substrate 12 in a direction away from the portion 12f on the lower surface 12d side of the GaN substrate 12. As described above, the strength of the affected layer 14 is lower than that of a GaN single crystal. Therefore, when a force is applied to the portion 12e in a direction away from the portion 12f, the portion 12e is peeled off from the portion 12f along the affected layer 14. That is, the GaN substrate 12 is divided along the affected layer 14. Then, various processes, such as surface polishing and electrode formation, are performed on the portion 12e to manufacture a semiconductor device. This manufacturing method allows for the manufacture of a thin semiconductor device. Furthermore, by smoothing the split surface of portion 12f and epitaxially growing a GaN layer on the smoothed split surface, portion 12f can be restored to the original thickness of GaN substrate 12. Thereafter, portion 12f can be reused as GaN substrate 12 to manufacture a semiconductor device.

[0036] If the substrate dividing step is performed while affected layer-free region 16 remains in GaN substrate 12, problems may arise such as portion 12e not being separated from portion 12f within affected layer-free region 16 as shown in Fig. 9, or GaN substrate 12 being divided at a position within affected layer-free region 16 that differs from the depth of affected layer 14 as shown in Fig. 10. In contrast, if affected layer 14 is formed over the entire area of ​​GaN substrate 12 as shown in Fig. 8, portion 12e can be properly separated from portion 12f. [Example]

[0037] FIG. 11 shows an affected layer forming apparatus of Example 2. In Example 1, the optical system of the camera 50 and the optical system of the laser light source 40 were partially shared, but in Example 2, the camera 50 is provided independently from the optical system of the laser light source 40. As shown in FIG. 11, in Example 2, the camera 50 is disposed to the side of the condenser lens 44. In Example 2, the camera 50 directly captures an image of the GaN substrate 12. As in Example 1, the affected layer forming apparatus of Example 2 can also perform the substrate loading step, fine alignment step, affected layer forming step, affected layer non-formed region specifying step, and affected layer reforming step. [Example]

[0038] 12 shows a modified layer forming apparatus of Example 3. In Example 3, the camera 50 is disposed at a position away from the optical system of the laser light source 40. Also, in Example 3, the stage 30 can move between a position directly below the condenser lens 44 and a position directly below the camera 50. In the modified layer forming apparatus of Example 3, the control device 60 performs the substrate carrying-in step, the fine alignment step, and the modified layer forming step in the same manner as in Example 1, with the stage 30 disposed directly below the condenser lens 44.

[0039] In Example 3, at the start of the affected layer free region specifying step, the control device 60 moves the GaN substrate 12 by the stage 30 to directly below the camera 50. Thereafter, the control device 60 causes the camera 50 to capture an image of the GaN substrate 12 and specifies the coordinate range 16r of the affected layer free region 16.

[0040] In Example 3, at the start of the affected layer reforming step, control device 60 causes stage 30 to move GaN substrate 12 to directly below condenser lens 44. Thereafter, control device 60 performs the affected layer reforming step in the same manner as in Example 1. After the affected layer reforming step, the substrate dividing step is performed in the same manner as in Example 1.

[0041] In Example 3, the fine alignment step may be performed again when the stage 30 is moved (i.e., at the start of the affected layer unformed region specifying step and at the start of the affected layer reforming step). In this case, in the affected layer reforming step, the origin O (i.e., the xy coordinate system) is set in the same way as in the affected layer unformed region specifying step, so that the affected layer 14 can be accurately formed in the affected layer unformed region 16. [Example]

[0042] FIG. 13 shows a modified layer forming apparatus of Example 4. In the modified layer forming apparatus of Example 4, a stage 30a for laser processing and a stage 30b for photography are provided independently. A laser optical system including a laser light source 40, a half mirror 42, a condenser lens 44, etc. is disposed above stage 30a. A camera 50 is provided on stage 30b. Each of stages 30a and 30b is movable in the x, y, and z directions. Substrate transfer device 20 transfers GaN substrates 12 into and out of the modified layer forming apparatus, as well as between stage 30a and stage 30b.

[0043] FIG. 14 shows a manufacturing method of Example 4. In Example 4, in a substrate loading step, the control device 60 transfers the GaN substrate 12 onto the stage 30a using the substrate transfer device 20. Next, the control device 60 performs a first fine alignment step. The first fine alignment step is performed in the same manner as the fine alignment step of Example 1. That is, the control device 60 photographs the GaN substrate 12 on the stage 30a using an alignment camera (not shown) and detects the positions of the orientation flats 12a and 12b of the GaN substrate 12. Furthermore, the control device 60 calculates the position of the origin O based on the positions of the orientation flats 12a and 12b. Next, the control device 60 forms an affected layer 14 on the GaN substrate 12 in the same manner as the affected layer forming step of Example 1. That is, the control device 60 irradiates the GaN substrate 12 on the stage 30a with a laser L to form an affected layer 14 over the entire area of ​​the GaN substrate 12 in the x and y directions.

[0044] Next, the control device 60 performs a first substrate transfer step. In the first substrate transfer step, the control device 60 causes the substrate transfer device 20 to transfer the GaN substrate 12 from stage 30a to stage 30b. After performing coarse alignment, the substrate transfer device 20 places the GaN substrate 12 on stage 30b. Next, the control device 60 performs a second fine alignment step on the stage 30b. The second fine alignment step is performed in the same manner as the fine alignment step of Example 1. That is, the control device 60 photographs the GaN substrate 12 on stage 30b using the camera 50 or an alignment camera (not shown) and detects the positions of the orientation flats 12a and 12b of the GaN substrate 12. Furthermore, the control device 60 calculates the position of the origin O based on the positions of the orientation flats 12a and 12b. That is, the control device 60 sets an x-y coordinate system.

[0045] Next, the control device 60 performs the affected layer not formed region specifying step in the same manner as in Example 1. That is, the control device 60 captures an image of the GaN substrate 12 with the camera 50, and specifies the affected layer not formed region 15 and the affected layer not formed region 16 based on the captured image. The coordinate range 16r of the affected layer not formed region 16 is a coordinate range represented by the xy coordinate system set in the second fine alignment step. The control device 60 stores the calculated coordinate range 16r.

[0046] If an affected layer-free region 16 is present, the control device 60 performs a second substrate transfer process. In the second substrate transfer process, the control device 60 causes the substrate transfer device 20 to transfer the GaN substrate 12 from stage 30b to stage 30a. After performing coarse alignment, the substrate transfer device 20 places the GaN substrate 12 on stage 30a. Next, the control device 60 performs a third fine alignment process on the stage 30a. The third fine alignment process is performed in the same manner as the fine alignment process of Example 1. That is, the control device 60 photographs the GaN substrate 12 on stage 30a using an alignment camera (not shown) and detects the positions of the orientation flats 12a and 12b of the GaN substrate 12. Furthermore, the control device 60 calculates the position of the origin O based on the positions of the orientation flats 12a and 12b. In the third fine alignment process, the origin O is set at the same position as in the second fine alignment process. That is, in the third fine alignment step, the same xy coordinate system as in the second fine alignment step is set.

[0047] Next, the control device 60 forms the affected layer 14 in the affected-layer-free region 16 in the same manner as in the affected-layer reforming step of Example 1. That is, the control device 60 irradiates the GaN substrate 12 with the laser L to form the affected layer 14 throughout the coordinate range 16r identified in the affected-layer-free region identifying step.

[0048] The control device 60 repeatedly executes the affected layer unformed region specifying step and the affected layer reforming step until there are no affected layer unformed regions 16. When there are no affected layer unformed regions 16, the control device 60 removes the GaN substrate 12 from the affected layer forming device. Thereafter, the substrate dividing step is carried out in the same manner as in Example 1, and semiconductor devices are manufactured using the divided GaN substrates 12.

[0049] In the second and third fine alignment steps, the xy coordinate systems are set based on the orientation flats 12a and 12b. However, in the second and third fine alignment steps, a common xy coordinate system may be set based on different characteristic points of the GaN substrate 12. [Example]

[0050] 15 shows a degraded layer forming apparatus of Example 5. The degraded layer forming apparatus of Example 5 is obtained by adding a substrate dividing device 70 to the degraded layer forming apparatus of Example 1. Except for the addition of the substrate dividing device 70, the degraded layer forming apparatus of Example 5 is the same as the degraded layer forming apparatus of Example 1.

[0051] In the affected layer forming apparatus of Example 5, the control device 60 performs the substrate loading step, fine alignment step, affected layer forming step, affected layer-free region specifying step, and affected layer reforming step in the same manner as in Example 1. In the substrate dividing step, the control device 60 divides the GaN substrate 12 using the substrate dividing device 70. The substrate dividing device 70 has a first support part that supports the upper surface 12c of the GaN substrate 12 by suction, adhesion, or the like, and a second support part that supports the lower surface 12d of the GaN substrate 12 by suction, adhesion, or the like. The control device 60 divides the GaN substrate 12 by moving the first support part in a direction away from the second support part, as shown in FIG. 8 . In this manner, the affected layer forming apparatus of Example 5 can perform the processes up to the substrate dividing step. [Example]

[0052] As described above, in the affected layer forming step, the laser L may be blocked by foreign matter adhering to the upper surface of the GaN substrate 12, resulting in the generation of an affected layer unformed region 16. As shown in Fig. 16, in the manufacturing method of Example 6, a cleaning step is performed after the affected layer unformed region specifying step and before the affected layer reforming step in order to remove the foreign matter. The manufacturing method of Example 6 can be performed using any of the affected layer forming apparatuses of Examples 1 to 5.

[0053] In the manufacturing method of Example 6, when an affected-layer-free region 16 is identified in the affected-layer-free region identifying step, the control device 60 causes the substrate transfer device 20 to remove the GaN substrate 12 from the affected-layer forming apparatus. Thereafter, a cleaning step is performed to clean the surface of the GaN substrate 12. In the cleaning step, foreign matter is removed from the surface of the GaN substrate 12. After the cleaning step is performed, the substrate transfer device 20 loads the GaN substrate 12 into the affected-layer forming apparatus, and the affected-layer reforming step is performed. Because the foreign matter has been removed from the surface of the GaN substrate 12, an affected layer 14 can be appropriately formed in the affected-layer-free region 16 in the affected-layer reforming step. [Example]

[0054] As described above, in the affected layer forming step, the laser beam L is scattered by a rough surface portion on the upper surface of the GaN substrate 12, which may result in the generation of an affected layer unformed region 16. As shown in Fig. 17, in the manufacturing method of Example 7, a planarization step is performed after the affected layer unformed region specifying step and before the affected layer reforming step in order to remove the rough surface portion. The manufacturing method of Example 7 can be performed using any of the affected layer forming apparatuses of Examples 1 to 5.

[0055] In the manufacturing method of Example 7, when an affected-layer-free region 16 is identified in the affected-layer-free region identifying step, the control device 60 causes the substrate transfer device 20 to remove the GaN substrate 12 from the affected-layer forming device. A planarization step is then performed to planarize the surface of the GaN substrate 12 by polishing, etching, or the like. In the planarization step, the roughened surface portion is removed from the surface of the GaN substrate 12. After the planarization step, the substrate transfer device 20 loads the GaN substrate 12 into the affected-layer forming device, where the affected-layer reformation step is performed. Since the roughened surface portion has been removed from the surface of the GaN substrate 12, an affected layer 14 can be appropriately formed in the affected-layer-free region 16 in the affected-layer reformation step.

[0056] When the affected layer-free region 16 is identified in the affected layer-free region identifying step, both the cleaning step of the sixth embodiment and the planarizing step of the seventh embodiment may be performed.

[0057] In the above-described embodiment, the affected layer-free region specifying step was performed after the affected layer forming step. However, the affected layer-free region specifying step may be performed while the affected layer forming step is being performed. That is, the affected layer-free region may be specified by taking an image of the region after laser irradiation while the affected layer forming step is being performed.

[0058] In the above-described embodiment, the entire area of ​​the GaN substrate 12 in the x and y directions was the target area for forming the affected layer 14. However, the target area for forming the affected layer 14 may be only a part of the GaN substrate 12 in the x and y directions.

[0059] In the above-described examples, the processing target was a GaN substrate. Because a GaN substrate is optically transparent, it is easy to distinguish between the affected layer formation region 15 and the affected layer unformed region 16 from the image captured by the camera 50. However, the processing target may be a compound semiconductor substrate other than a GaN substrate. The compound semiconductor substrate to be processed does not have to be optically transparent. Even if the compound semiconductor substrate is not optically transparent, there may be a difference in appearance between the affected layer formation region 15 and the affected layer unformed region 16, so it is possible to distinguish between the affected layer formation region 15 and the affected layer unformed region 16 from the image captured by the camera 50.

[0060] The laser light source 40 of the embodiment is an example of a laser irradiation device, and the camera 50 of the embodiment is an example of a photographing device.

[0061] 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 variations of the specific examples exemplified above. The technical elements described in this specification or 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. Furthermore, the technology exemplified in this specification or drawings simultaneously achieves multiple objectives, and achieving one of these objectives itself has technical utility. [Explanation of symbols]

[0062] 10: Affected layer forming device, 12: Gallium nitride substrate, 14: Affected layer, 15: Affected layer formed area, 16: Affected layer not formed area, 30: Stage, 40: Laser light source, 50: Camera

Claims

1. A manufacturing method for manufacturing a semiconductor device using an altered layer forming apparatus, comprising: The affected layer forming device includes: a laser irradiation device; A photographing device, and The manufacturing method comprises: forming an affected layer inside the compound semiconductor substrate in the target area by irradiating the compound semiconductor substrate with a laser beam using the laser irradiation device; taking an image of the compound semiconductor substrate in the target area with the imaging device, and identifying an affected layer-free area in the target area based on the image; forming the affected layer inside the affected layer-free region of the compound semiconductor substrate by irradiating the affected layer-free region of the compound semiconductor substrate with a laser beam using the laser irradiation device; a step of cleaning the compound semiconductor substrate after the step of identifying the affected layer-free region and before the step of forming the affected layer inside the compound semiconductor substrate in the affected layer-free region; having Manufacturing method.

2. A manufacturing method for manufacturing a semiconductor device using an altered layer forming apparatus, comprising: The affected layer forming device includes: a laser irradiation device; A photographing device, and The manufacturing method comprises: forming an affected layer inside the compound semiconductor substrate in the target area by irradiating the compound semiconductor substrate with a laser beam using the laser irradiation device; taking an image of the compound semiconductor substrate in the target area with the imaging device, and identifying an affected layer-free area in the target area based on the image; forming the affected layer inside the affected layer-free region of the compound semiconductor substrate by irradiating the affected layer-free region of the compound semiconductor substrate with a laser beam using the laser irradiation device; a step of planarizing a surface of the compound semiconductor substrate after the step of identifying the affected layer unformed region and before the step of forming the affected layer inside the compound semiconductor substrate in the affected layer unformed region; having Manufacturing method.

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