Semiconductor manufacturing device and method for manufacturing the same

Abstract

To provide a new technology that suppresses deformation of semiconductor substrates in processes utilizing laser irradiation during semiconductor device manufacturing.SOLUTION: A semiconductor manufacturing device an irradiation unit that irradiates a semiconductor substrate with a laser so that a focal point is formed within the semiconductor substrate and that moves the focus along a specific plane spreading laterally within the semiconductor substrate, and a pressing unit that presses the irradiated area in the thickness direction of the semiconductor substrate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a method for processing a semiconductor substrate. In Patent Document 1, a modified layer is formed inside the semiconductor substrate by irradiating the semiconductor substrate with a laser that is focused inside the semiconductor substrate. The modified layer is formed so as to spread along the surface of the semiconductor substrate. By forming such a modified layer, the semiconductor substrate can be processed. For example, by dividing the semiconductor substrate along the modified layer, thinner semiconductor substrates can be obtained.

[0003] When forming a modified layer inside a semiconductor substrate, the crystalline structure is destroyed by laser irradiation, and the atoms that make up the semiconductor are vaporized. The pressure of the generated gas can cause cracks in unintended directions inside the semiconductor substrate. In Patent Document 1, the semiconductor substrate is heated after the modified layer is formed, thereby melting the modified layer and discharging the gas generated inside the semiconductor substrate together with the melted modified layer from the end face of the semiconductor substrate to the outside. [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] In the technology of Patent Document 1, the generated gas is discharged using its pressure, but depending on the size of the semiconductor substrate, the gas may not move sufficiently laterally and may remain inside the semiconductor substrate. As a result, the semiconductor substrate may be deformed. This specification provides a new technology that suppresses deformation of the semiconductor substrate in a technology that uses laser irradiation when manufacturing a semiconductor device. [Means for solving the problem]

[0006] The semiconductor device manufacturing apparatus disclosed in this specification includes an irradiation unit that irradiates a semiconductor substrate with a laser so that a focal point is formed inside the semiconductor substrate, the irradiation unit moving the focal point along a specific plane that extends laterally within the semiconductor substrate, and a pressing unit that presses the irradiation range irradiated with the laser in the thickness direction of the semiconductor substrate.

[0007] In this manufacturing apparatus, a modified layer is formed inside the semiconductor substrate by irradiating the semiconductor substrate with a laser from the irradiation unit. The focal point of the laser is moved along a specific surface within the semiconductor substrate, so the modified layer is formed along the specific surface. At this time, gas is generated inside the modified layer. Then, the semiconductor substrate is pressed in the thickness direction of the semiconductor substrate by the pressing unit within the irradiation area. The modified layer has lower mechanical strength than other semiconductor regions. Therefore, when the pressing unit presses the semiconductor substrate, the gas moves laterally along the modified layer (i.e., the specific surface). This allows the gas generated inside the semiconductor substrate to move along the modified layer. Therefore, in this manufacturing apparatus, the gas generated inside the modified layer can be suitably discharged to the outside of the semiconductor substrate. Therefore, this manufacturing apparatus can suppress deformation of the semiconductor substrate.

[0008] This specification also discloses a method for manufacturing a semiconductor device, comprising the steps of: irradiating a semiconductor substrate with a laser so as to form a focal point within the semiconductor substrate, and moving the focal point along a specific plane extending laterally within the semiconductor substrate; pressing the laser-irradiated area in a thickness direction of the semiconductor substrate; and dividing the semiconductor substrate along the specific plane.

[0009] In this manufacturing method, a modified layer is formed inside the semiconductor substrate by irradiating the semiconductor substrate with a laser. The laser focus is moved along a specific plane within the semiconductor substrate, so the modified layer is formed along the specific plane. At this time, gas is generated inside the modified layer. Next, the laser-irradiated area is pressed in the thickness direction of the semiconductor substrate. The modified layer has lower mechanical strength than other semiconductor regions. Therefore, when the semiconductor substrate is pressed, the gas moves laterally along the modified layer (i.e., the specific plane). This allows the gas generated inside the semiconductor substrate to move along the modified layer. Then, the semiconductor substrate is divided. As described above, this manufacturing method can efficiently discharge the gas generated inside the modified layer to the outside of the semiconductor substrate. Therefore, this manufacturing method can suppress deformation of the semiconductor substrate and manufacture semiconductor devices with a high yield. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a manufacturing apparatus according to an embodiment. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. 10 is an explanatory diagram of an embodiment in which a laser irradiation step and a pressing step are performed simultaneously. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] FIG. 10 is a diagram for explaining a manufacturing apparatus according to a modified example. [Figure 10] FIG. 10 is a diagram for explaining a manufacturing apparatus according to another modified example. [Figure 11] FIG. 10 is a diagram for explaining a manufacturing apparatus according to another modified example. [Figure 12] FIG. 10 is a diagram for explaining a manufacturing apparatus according to another modified example. DETAILED DESCRIPTION OF THE INVENTION

[0011] In the example manufacturing apparatus disclosed in the present specification, the pressing unit may press the irradiation area while the irradiation unit irradiates the semiconductor substrate with the laser.

[0012] Gas is generated inside the semiconductor substrate, causing an increase in the internal pressure of the semiconductor substrate. With this configuration, by pressing the irradiation area while irradiating with a laser, it is possible to move the gas laterally before the gas expands in an unintended direction (for example, the thickness direction of the semiconductor substrate), and also to shorten the manufacturing time of the semiconductor device.

[0013] In the example manufacturing apparatus disclosed in this specification, the pressing unit may press the irradiation area while changing the position of the pressing area.

[0014] According to this configuration, the semiconductor substrate is pressed while the position of the pressing range is changed, so that the generated gas can be moved laterally in a sequential manner.

[0015] In the example manufacturing apparatus disclosed in the present specification, the pressing unit may be a roller. The roller may roll on the surface of the semiconductor substrate to press the irradiation area.

[0016] According to this configuration, the gas can be moved laterally with a simple configuration.

[0017] In the example manufacturing apparatus disclosed in the present specification, the semiconductor substrate may be made of a III-V group semiconductor or gallium oxide.

[0018] (Example) 1 shows a manufacturing apparatus 50 of this embodiment. The manufacturing apparatus 50 is an apparatus for forming a modified layer 14 inside a semiconductor substrate 2. The manufacturing apparatus 50 includes an irradiation unit 52, a support unit 54, and a pressing unit 56.

[0019] The irradiation unit 52 includes a light source that irradiates a laser. The laser emitted from the light source is configured to form a focal point S1 inside the semiconductor substrate 2. By transmitting the laser emitted from the light source through an objective lens 58, the laser can be condensed and the position of the focal point can be adjusted.

[0020] The support part 54 fixes the semiconductor substrate 2 to the manufacturing equipment 50. As will be described later, the support part 54 in this embodiment is a dicing tape 30 and a dicing ring 32. The dicing tape 30 is attached to the semiconductor substrate 2, and the dicing ring 32 fixes the semiconductor substrate 2 to the manufacturing equipment 50, whereby the semiconductor substrate 2 is supported by the manufacturing equipment 50.

[0021] The pressing unit 56 presses the semiconductor substrate 2 in the thickness direction. In this embodiment, the pressing unit 56 is made up of two cylindrical rollers 57. The rollers 57 have a rotation axis parallel to the surface of the semiconductor substrate 2, and are configured to press the semiconductor substrate 2 in its thickness direction by rolling on the surface of the semiconductor substrate 2. The semiconductor substrate 2 is sandwiched between the two rollers 57, which are arranged vertically with a gap between them, and the semiconductor substrate 2 is pressed in its thickness direction.

[0022] Next, a method for manufacturing a semiconductor device using the above-described manufacturing apparatus 50 will be described. FIG. 2 is a plan view of a semiconductor substrate 2 on which a plurality of element structures 6 are arranged in a matrix. Each element structure 6 is formed on the first surface 2a of the semiconductor substrate 2. Each element structure 6 includes a structure for realizing the function of the semiconductor device, such as a trench or a gate electrode. Inside the semiconductor substrate 2, structures having the functions of a transistor or a diode are formed at positions corresponding to each element structure 6. The semiconductor substrate 2 is made of GaN. Note that the semiconductor substrate 2 may also be made of other optically transparent semiconductors (e.g., III-V semiconductors such as AlN and GaAs, Ga2O3, etc.). As shown in FIG. 3 and other figures, the semiconductor substrate 2 has a second surface 2b located on the back side of the first surface 2a.

[0023] The manufacturing method of the embodiment includes a laser irradiation step, a pressing step, and a dividing step.

[0024] (Laser irradiation process) As shown in FIG. 3, first, a dicing tape 30 is attached to the first surface 2a of the semiconductor substrate 2, and the semiconductor substrate 2 is fixed to the manufacturing apparatus 50 by a dicing ring 32. Next, a laser irradiation process is performed to form a modified layer 14 inside the semiconductor substrate 2. In the laser irradiation process, as shown in FIG. 3, a laser 110 is irradiated onto the semiconductor substrate 2 from the second surface 2b side. The laser 110 is irradiated so as to form a focal point S1 within a predetermined depth range inside the semiconductor substrate 2. At the position of the focal point S1, GaN is heated and decomposed, and nitrogen gas is generated. As a result, a void portion 15 filled with nitrogen gas is formed at the position of the focal point S1, and a modified layer 14 composed of a gallium precipitate layer or the like is formed around the focal point S1. The modified layer 14 has a lower strength than the original GaN single crystal. Therefore, the modified layer 14 has a lower strength than the surrounding GaN single crystal. Here, the laser 110 is intermittently irradiated while moving the irradiation position of the laser 110 in a direction parallel to the first surface 2a and the second surface 2b of the semiconductor substrate 2 (left and right direction in FIG. 3 ). As a result, a modified layer 14 is formed within a predetermined depth range within the semiconductor substrate 2 along a specific plane (a plane parallel to the first surface 2a) extending laterally, and voids 15 are formed discretely within the modified layer 14. In this process, the irradiation position of the laser 110 is scanned as indicated by arrow 120 in FIG. 4 to form the modified layer 14 so as to extend over the entire semiconductor substrate 2. In FIG. 4 , the area irradiated with the laser 110 is indicated by hatching. As described above, when GaN is decomposed by irradiating the semiconductor substrate 2 with the laser 110 (i.e., when the modified layer 14 is formed), nitrogen gas is generated and voids 15 are formed. The voids 15 are formed within the semiconductor substrate 2 so as to be distributed at intervals. The semiconductor region around the focal position of the laser 110 is modified by the heat of the laser 110, so that in the cross section shown in Fig. 3, voids 15 are distributed discretely, while the semiconductor region located between adjacent voids 15 becomes a modified layer 14. That is, in this process, the modified layer 14 is formed along a specific plane, and the voids 15 are formed inside the modified layer 14.Hereinafter, the portion of the semiconductor substrate 2 closer to the first surface 2a than the modified layer 14 will be referred to as a first portion 8a, and the portion closer to the second surface 2b than the modified layer 14 will be referred to as a second portion 8b.

[0025] (Pressing process) Next, a pressing step is performed. In the pressing step, as shown in FIG. 5, rollers 57 press the semiconductor substrate 2 in the thickness direction by sandwiching it from the first surface 2a side and the second surface 2b side. The rollers 57 have a rotation axis parallel to the first surface 2a. The rollers 57 roll on the first surface 2a and the second surface 2b from the edge of the semiconductor substrate 2 along the direction of arrow 122, thereby pressing the irradiation area irradiated with the laser 110 while changing the position of the pressing area. As described above, the mechanical strength of the modified layer 14 is lower than the mechanical strength of the surrounding semiconductor region. Therefore, when the semiconductor substrate 2 is compressed by rolling the rollers 57, the partition walls between the multiple voids 15 (i.e., the partition walls formed by the modified layer 14) are broken, and the multiple voids 15 are connected to each other. As a result, adjacent voids 15 are sequentially connected to each other in the horizontal direction, as shown in FIG. 5. Therefore, the nitrogen gas in each void portion 15 is pushed by the roller 57 and moves in the rolling direction of the roller 57. Therefore, by pressing the entire area of ​​the semiconductor substrate 2 with the roller 57, the nitrogen gas generated inside the modified layer 14 can be discharged to the outside from the end face of the semiconductor substrate 2. The pressing step may be performed simultaneously with the laser irradiation step, as shown in FIG. 6. The pressing step can be performed simultaneously with the laser irradiation step by pressing the irradiation area irradiated with the laser 110 (i.e., the area where the modified layer 14 has already been formed) with the roller 57 while irradiating the laser 110.

[0026] (splitting process) Next, as shown in FIG. 7 , the semiconductor substrate 2 is divided along the modified layer 14. Here, the semiconductor substrate 2 is divided along the modified layer 14 by applying a force to the first portion 8a in a direction away from the second portion 8b while applying an external impact to the semiconductor substrate 2. That is, the first portion 8a is separated from the second portion 8b. As described above, the strength of the modified layer 14 is lower than that of the GaN single crystal. Therefore, when a force is applied in a direction to separate the first portion 8a and the second portion 8b, the first portion 8a is easily peeled from the second portion 8b in the modified layer 14. In particular, since the void portion 15 is connected laterally by the pressing step, the first portion 8a can be more easily peeled from the second portion 8b. Note that the steps after the dividing step may be performed by the manufacturing apparatus 50 or by an apparatus separate from the manufacturing apparatus 50.

[0027] 8, the lower surface of the first portion 8a (i.e., the dividing surface) is polished and cleaned as necessary. Then, using a known method such as dicing with a laser or blade, the first portion 8a is divided into individual pieces so that each piece includes an element structure 6. This completes a plurality of semiconductor devices 10.

[0028] The second portions 8b may be subsequently reused in the manufacture of semiconductor devices. For example, the split surfaces of the second portions 8b may be polished, etched, or the like, and then a GaN layer may be epitaxially grown on the split surfaces, thereby increasing the thickness of the second portions 8b to their original thickness. The second portions 8b with increased thickness may be reused to manufacture semiconductor devices.

[0029] As described above, in the manufacturing apparatus 50 and manufacturing method of this embodiment, the semiconductor substrate 2 is irradiated with the laser 110 to form a modified layer 14 inside the semiconductor substrate 2. The focal point S1 of the laser 110 is moved along a specific plane within the semiconductor substrate 2, so the modified layer 14 is formed along the specific plane. At this time, voids 15 containing nitrogen gas are formed inside the modified layer 14. Next, the area irradiated with the laser 110 is pressed in the thickness direction of the semiconductor substrate 2. The modified layer 14 has lower mechanical strength than other semiconductor regions. Therefore, when the semiconductor substrate 2 is pressed with the roller 57, the partition walls between the voids 15 are broken, thereby connecting the voids 15 to each other. This allows the nitrogen gas in each void 15 to move along the modified layer 14 in the rolling direction of the roller 57. As described above, in the manufacturing apparatus 50 and manufacturing method, the multiple voids 15 formed inside the modified layer 14 are sequentially connected to each other, allowing the generated nitrogen gas to be discharged to the outside of the semiconductor substrate 2. Therefore, deformation of the semiconductor substrate 2 can be suppressed.

[0030] Furthermore, in the above-described embodiment, the internal pressure of the semiconductor substrate 2 increases due to the generation of nitrogen gas inside the semiconductor substrate 2. In the above-described embodiment, when the laser irradiation step and the pressing step are performed simultaneously, pressing the irradiated area with the roller 57 while irradiating the semiconductor substrate 2 with the laser 110 makes it possible to move the nitrogen gas laterally before it spreads in an unintended direction inside the semiconductor substrate 2 (for example, the thickness direction of the semiconductor substrate 2), and also makes it possible to shorten the manufacturing time of the semiconductor device 10.

[0031] Furthermore, in the above-described embodiment, the roller 57 presses the irradiation area of ​​the laser 110 while changing the position of the pressing area, so that the generated nitrogen gas can be moved laterally in succession.

[0032] Furthermore, in the above-described embodiment, the pressing portion 56 is configured by the roller 57, so that the nitrogen gas can be moved laterally with a simple configuration.

[0033] 9, the support unit 54 may be configured by the stage 36. Furthermore, the pressing unit 56 does not have to include the rollers 57 for pressing the semiconductor substrate 2 from the first surface 2a side. By pressing the semiconductor substrate 2 from the second surface 2b side with the rollers, the semiconductor substrate 2 sandwiched between the rollers 57 and the stage 36 can be pressed in its thickness direction.

[0034] In the above-described embodiment, the cross section of the roller 57 may be a rectangle with rounded corners, as shown in Fig. 10. In this configuration, the contact area between the roller 57 and the first surface 2a and the second surface 2b of the semiconductor substrate 2 is increased, so that the nitrogen gas can be more effectively moved in the rolling direction of the roller 57.

[0035] 11, the laser 110 may be irradiated from a direction inclined with respect to the direction perpendicular to the first surface 2a of the semiconductor substrate 2. In this configuration, the position of the focal point S1 of the laser 110 and the pressing position of the roller 57 can be brought close to each other, so that the irradiation area immediately after the modified layer 14 is formed can be pressed by the roller 57. In other words, the nitrogen gas can be moved laterally immediately after it is generated.

[0036] In the above-described embodiment, the pressing unit 56 is configured by the roller 57. However, the pressing unit 56 may be configured to be capable of pressing the semiconductor substrate 2 in its thickness direction, and may, for example, repeatedly perform the process of pressing the semiconductor substrate 2 in its thickness direction at multiple locations. Furthermore, the pressing unit 56 may perform the process of pressing the entire semiconductor substrate 2 at once after the laser irradiation step has been performed.

[0037] Furthermore, the scanning direction of the laser 110 is not limited to the direction indicated by the arrow 120 in FIG. 4, and for example, the laser 110 may be scanned from the periphery of the semiconductor substrate 2 along the circumferential direction toward the center of the semiconductor substrate 2, as indicated by the arrow 124 in FIG.

[0038] In the above-described embodiment, the element structure 6 is formed on the semiconductor substrate 2, but the element structure 6 does not have to be formed on the semiconductor substrate 2.

[0039] The configurations of the semiconductor device manufacturing apparatus and manufacturing method disclosed in this specification are listed below. (Configuration 1) A semiconductor device manufacturing apparatus, an irradiation unit that irradiates a semiconductor substrate with a laser so that a focal point is formed inside the semiconductor substrate, the irradiation unit moving the focal point along a specific plane that extends laterally within the semiconductor substrate; a pressing unit that presses the laser-irradiated area in the thickness direction of the semiconductor substrate; A manufacturing apparatus comprising: (Configuration 2) 2. The manufacturing apparatus according to claim 1, wherein the pressing unit presses the irradiation area while the irradiation unit irradiates the semiconductor substrate with the laser. (Configuration 3) 3. The manufacturing apparatus according to claim 1, wherein the pressing unit presses the irradiation area while changing the position of the pressing area. (Configuration 4) the pressing portion is a roller, 4. The manufacturing apparatus according to any one of configurations 1 to 3, wherein the roller rolls on the surface of the semiconductor substrate to press the irradiation area. (Configuration 5) 5. The manufacturing apparatus according to any one of configurations 1 to 4, wherein the semiconductor substrate is made of a III-V group semiconductor or gallium oxide. (Configuration 6) A method for manufacturing a semiconductor device, comprising: a step of irradiating a semiconductor substrate with a laser so that a focal point is formed inside the semiconductor substrate, the step of moving the focal point along a specific plane extending laterally within the semiconductor substrate; pressing the laser irradiated area in a thickness direction of the semiconductor substrate; dividing the semiconductor substrate along the specific plane; A manufacturing method comprising: (Configuration 7) 7. The manufacturing method according to configuration 6, wherein the step of irradiating the semiconductor substrate with the laser and the step of pressing the irradiated area are carried out simultaneously. (Configuration 8) 8. The manufacturing method according to claim 6 or 7, wherein in the step of pressing the irradiation area, the irradiation area is pressed while changing the position of the pressing area. (Configuration 9) 9. The manufacturing method according to any one of configurations 6 to 8, wherein in the step of pressing the irradiated area, a roller rolls on the surface of the semiconductor substrate to press the irradiated area. (Configuration 10) 10. The manufacturing method according to any one of aspects 6 to 9, wherein the semiconductor substrate is made of a III-V group semiconductor or gallium oxide.

[0040] Although specific examples of the present invention 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 those objectives itself has technical utility. [Explanation of symbols]

[0041] 2: Semiconductor substrate 2a: 1st surface 2b: 2nd surface 6: Element structure 10: Semiconductor device 14: Modified layer 15: Nitrogen gas 50: Manufacturing equipment 52: Irradiation unit 54: Support part 56: Pressing part 58: Objective lens 110: Laser

Claims

1. A manufacturing apparatus (50) for a semiconductor device (10), an irradiation unit (52) that irradiates a semiconductor substrate (2) with a laser (110) so that a focal point (S1) is formed inside the semiconductor substrate (2), and the irradiation unit moves the focal point along a specific plane that extends laterally within the semiconductor substrate; a pressing section (56) that presses the laser-irradiated area in the thickness direction of the semiconductor substrate; A manufacturing apparatus comprising:

2. The manufacturing apparatus according to claim 1 , wherein the pressing unit presses the irradiation area while the irradiation unit is irradiating the semiconductor substrate with the laser.

3. The manufacturing apparatus according to claim 1 , wherein the pressing unit presses the irradiation area while changing the position of the pressing area.

4. The pressing part is a roller (57), The manufacturing apparatus according to claim 1 , wherein the roller presses the irradiation area by rolling on the surface of the semiconductor substrate.

5. 5. The manufacturing apparatus according to claim 1, wherein the semiconductor substrate is made of a III-V group semiconductor or gallium oxide.

6. A method for manufacturing a semiconductor device (10), comprising: A step of irradiating a semiconductor substrate (2) with a laser (110) so that a focal point (S1) is formed inside the semiconductor substrate (2), the step of moving the focal point along a specific plane extending laterally within the semiconductor substrate; pressing the laser irradiated area in a thickness direction of the semiconductor substrate; dividing the semiconductor substrate along the specific plane; A manufacturing method comprising:

7. The manufacturing method according to claim 6 , wherein the step of irradiating the semiconductor substrate with the laser and the step of pressing the irradiated area are carried out simultaneously.

8. The manufacturing method according to claim 6 , wherein in the step of pressing the irradiation area, the irradiation area is pressed while changing the position of the pressing area.

9. The manufacturing method according to claim 6, wherein in the step of pressing the irradiated area, a roller (57) rolls on the surface of the semiconductor substrate to press the irradiated area.

10. 10. The manufacturing method according to claim 6, wherein the semiconductor substrate is made of a III-V group semiconductor or gallium oxide.

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