Method of manufacturing a semiconductor device

Abstract

To solve a problem that a manufacturing method of a semiconductor device which suppresses variation of an electric property of a device structure is necessary.SOLUTION: A manufacturing method of a semiconductor device includes: a laser radiation process for radiating laser light to a plane 3 extending in a prescribed depth of a semiconductor substrate 1 where the semiconductor substrate has a first principal surface 1a and a second principal surface 1b, a device structure 10 having a channel CH is formed in the first principal surface side, and the laser light is radiated to a prescribed depth of the semiconductor substrate from the second principal surface; and a peeling process for peeling off a device layer in which the device structure is formed from the semiconductor substrate along a plane to which the laser light is radiated. In the laser radiation process, in the plane extending in the prescribed depth of a semiconductor substrate, the laser light is radiated so that a laser power density in a region corresponding to a lower part of the channel of the device structure is lower than the other region.SELECTED DRAWING: Figure 1

Description

Technical Field

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

[0002] After forming a device structure on one main surface side of a semiconductor substrate, a technology has been developed to peel off a device layer on which the device structure is formed from the semiconductor substrate. By using this technology, the semiconductor substrate after the device layer is peeled off can be reused, so that the manufacturing cost of the semiconductor device can be reduced. Patent Document 1 discloses a technology of forming a modified layer inside the semiconductor substrate by irradiating a surface extending a predetermined depth of the semiconductor substrate with a laser, and peeling off the device layer from the semiconductor substrate along the surface on which the modified layer is formed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the study by the present inventors, it has been found that a part of the laser not absorbed at the focusing point reaches the device structure and varies the electrical characteristics of the device structure. In particular, when the laser reaches the channel of the device structure, it has been found that fluctuations in leakage current and a shift in threshold voltage occur. There is a need for a method for manufacturing a semiconductor device that suppresses such fluctuations in the electrical characteristics of the device structure.

Means for Solving the Problems

[0005] The manufacturing method of the semiconductor device disclosed in this specification is a laser irradiation step of irradiating a surface (3) extending to a predetermined depth of a semiconductor substrate (1), wherein the semiconductor substrate has a first main surface (1a) and a second main surface (1b), and a device structure (10) having a channel (CH) is formed on the first main surface side, and the laser is irradiated from the second main surface to the predetermined depth of the semiconductor substrate, and a peeling step of peeling the device layer (2) in which the device structure is formed from the semiconductor substrate along the surface irradiated with the laser. In the laser irradiation step, the laser is irradiated so that the power density of the laser in a region corresponding to below the channel of the device structure is lower than that in other regions on the surface extending to the predetermined depth of the semiconductor substrate.

[0006] Here, the "surface extending to a predetermined depth of the semiconductor substrate" is a surface extending in a direction orthogonal to the thickness direction of the semiconductor substrate and having a predetermined thickness in consideration of the spread of the laser beam spot. The "region corresponding to below the channel of the device structure" is a region including at least a part of the region overlapping the channel of the device structure when the semiconductor substrate is viewed in plan. The "laser power density" is the light intensity of the laser per unit area on the surface extending to the predetermined depth of the semiconductor substrate when the semiconductor substrate is viewed in plan. Also, in this manufacturing method, the laser power density in the region corresponding to below the channel of the device structure may be lower than that in other regions, and may include the case where it is substantially zero.

[0007] According to this manufacturing method, the power density of the laser irradiated to the region corresponding to below the channel of the device structure is low. Therefore, below the channel of the device structure, the light intensity of the laser that was not absorbed at the beam spot also becomes small, so that it is suppressed that a part of the laser that was not absorbed at the beam spot reaches the channel of the device structure. As a result, fluctuations in the electrical characteristics of the device structure are suppressed.

Brief Description of the Drawings

[0008]

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Embodiments for Carrying Out the Invention

[0009] The manufacturing method of the semiconductor device disclosed in this specification can include a laser irradiation step and a peeling step. In the laser irradiation step, a laser is irradiated onto a surface extending to a predetermined depth of a semiconductor substrate. The semiconductor substrate is not particularly limited, and may be a compound semiconductor. The semiconductor substrate may be, for example, a nitride semiconductor containing gallium nitride, silicon carbide, or gallium oxide. Since the manufacturing method of the semiconductor device disclosed in this specification can reuse the semiconductor substrate, it is particularly useful when applied to the expensive compound semiconductor substrate. The semiconductor substrate has a first main surface and a second main surface, and a device structure having a channel is formed on the first main surface side. The type of the device structure is not particularly limited, and may be, for example, a switching element structure. The type of the switching element structure may be, for example, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or an IGBT (Insulated Gate Bipolar Transistor). In the laser irradiation step, the laser is irradiated from the second main surface where the device structure is not formed to the predetermined depth of the semiconductor substrate. In the peeling step, a device layer having the device structure formed thereon is peeled from the semiconductor substrate along the surface irradiated with the laser. In the laser irradiation step, on the surface extending to the predetermined depth of the semiconductor substrate, the laser is irradiated so that the power density of the laser in a region corresponding to below the channel is lower than that in other regions.

[0010] In one method of the above manufacturing method, the laser irradiation step includes a step of creating laser irradiation coordinate data including a plurality of irradiation position coordinates for specifying a position where the semiconductor substrate is irradiated with a laser in a two-dimensional coordinate system that defines the in-plane position of the semiconductor substrate; a step of creating channel coordinate data including one or a plurality of channel position coordinates for specifying the position of the channel of the device structure in the two-dimensional coordinate system; a step of classifying the plurality of irradiation position coordinates included in the laser irradiation coordinate data into one or a plurality of first irradiation position coordinates not included in the one or a plurality of channel position coordinates and one or a plurality of second irradiation position coordinates included in the one or a plurality of channel position coordinates; a step of irradiating the semiconductor substrate at the predetermined depth corresponding to the one or a plurality of first irradiation position coordinates with the laser, and not irradiating the semiconductor substrate at the predetermined depth corresponding to the one or a plurality of second irradiation position coordinates with the laser or irradiating the semiconductor substrate at the predetermined depth corresponding to the one or a plurality of second irradiation position coordinates with the laser with an irradiation energy smaller than the irradiation energy at the one or a plurality of first irradiation position coordinates. According to this manufacturing method, by controlling the irradiation of the laser based on the first irradiation position coordinates and the second irradiation position coordinates, it is possible to make the power density of the laser in the region corresponding to below the channel of the device structure lower than that in other regions on the surface extending the predetermined depth of the semiconductor substrate.

[0011] In another method of the above manufacturing method, the laser irradiation step may include a step of disposing a laser light-shielding film that shields the laser in a region corresponding to below the channel of the device structure, and a step of irradiating the laser to the predetermined depth of the semiconductor substrate through the laser light-shielding film. Here, "disposing the laser light-shielding film" means that the laser light-shielding film only needs to exist in a region corresponding to below the channel of the device structure, and is not particularly limited. For example, when the laser light-shielding film is disposed to be formed on the second main surface of the semiconductor substrate or inside the semiconductor substrate, when the laser light-shielding film is disposed to be placed on the second main surface of the semiconductor substrate, and when the laser light-shielding film is disposed with a space separated from the second main surface of the semiconductor substrate, are included. According to this manufacturing method, by the laser light-shielding film shielding the laser, the power density of the laser in the region corresponding to below the channel can be made lower than that in other regions on the surface extending the predetermined depth of the semiconductor substrate.

[0012] The step of disposing the laser light-shielding film may include a step of forming the laser light-shielding film on the entire second main surface of the semiconductor substrate, and a step of removing a part of the laser light-shielding film so that a region corresponding to below the channel of the device structure remains. According to this manufacturing method, the laser light-shielding film can be formed on the second main surface of the semiconductor substrate.

[0013] The step of disposing the laser light-shielding film may include a step of forming the laser light-shielding film on the entire surface of the base substrate, a step of removing a part of the laser light-shielding film so that the laser light-shielding film in a region corresponding to the formation position of the channel of the device structure remains, and a step of forming an epitaxial layer on the surface of the base substrate to form the semiconductor substrate. The "region corresponding to the formation position of the channel of the device structure" is a region that becomes a region corresponding to below the channel of the device structure when the device structure is formed on the semiconductor substrate. According to this manufacturing method, the laser light-shielding film can be formed inside the semiconductor substrate.

[0014] In another method of the above manufacturing method, the laser irradiation step includes a step of forming a mask over the entire second main surface of the semiconductor substrate, a step of removing a part of the mask so that a region corresponding to below the channel opens, a step of damaging the second main surface of the semiconductor substrate exposed from the mask to form the damage region, a step of removing the mask after forming the damage region, and a step of irradiating the laser to the predetermined depth of the semiconductor substrate through the damage region. The surface roughness of the damage region is increased. Therefore, the transmission amount of the laser passing through the damage region by reflection and / or scattering is greatly attenuated. According to this manufacturing method, by blocking the laser with the damage region, the power density of the laser in the region corresponding to below the channel can be made lower than that in other regions on the surface extending the predetermined depth of the semiconductor substrate.

Example

[0015] Hereinafter, with reference to the drawings, the laser irradiation step, the peeling step, and the dicing step in the manufacturing method of the semiconductor device will be described. Then, some examples of the laser irradiation step disclosed in this specification will be described in detail. Note that for various other steps other than the laser irradiation step, the peeling step, and the dicing step, for example, the step of forming a device structure, known manufacturing techniques can be used.

[0016] FIG. 1 shows the flow of the laser irradiation step (step S1), the peeling step (step S2), and the dicing step (step S3). The manufacturing method of the semiconductor device disclosed in this specification manufactures a plurality of semiconductor devices (also referred to as chips) by performing these steps on the semiconductor substrate 1 shown in FIG. 2.

[0017] As shown in FIG. 2, the semiconductor substrate 1 has an upper surface 1a and a lower surface 1b that each extend in a plane and are parallel to each other. These upper surface 1a and lower surface 1b are also referred to as main surfaces. The semiconductor substrate 1 is not particularly limited, but in this example is a gallium nitride substrate. A surface 3 that extends to a predetermined depth of the semiconductor substrate 1 is, as will be described later, the surface irradiated with a laser, that is, the surface where a plurality of laser beam focus points converge. In this specification, the portion of the semiconductor substrate 1 above the surface 3 irradiated with the laser, that is, the portion peeled off from the semiconductor substrate 1 is referred to as the device layer 2. A device structure having a channel is formed in the device layer 2 of the semiconductor substrate 1.

[0018] FIG. 3 shows a unit cell of the device structure 10 formed in the device layer 2 of the semiconductor substrate 1. The device structure 10 is not particularly limited, but in this example is a vertical MOSFET. The device structure 10 has an n + -type drain region 12, an n-type drift region 14, a p-type body region 16, and an n + -type source region 18, and a planar insulating gate 19. The drain region 12 is provided at a position exposed to the lower surface 1b of the semiconductor substrate 1. The drift region 14 is provided between the drain region 12 and the body region 16. A part of the drift region 14 disposed at a position exposed to the upper surface 1a of the semiconductor substrate 1 is referred to as a JFET region 14a. The body region 16 is provided at a position exposed to the upper surface 1a of the semiconductor substrate 1 and is disposed so as to separate the drift region 14 and the source region 18. A part of the body region 16 located between the JFET region 14a of the drift region 14 and the source region 18 is referred to as a channel CH. The source region 18 is provided at a position exposed to the upper surface 1a of the semiconductor substrate 1. The insulating gate 19 is provided so as to cover a part of the upper surface 1a of the semiconductor substrate 1 and is disposed so as to face the channel CH of the body region 16. Thereby, the electron density of the inversion layer generated in the channel CH of the body region 16 is controlled according to the voltage applied to the insulating gate 19, and the on / off of the device structure is controlled. Thus, the channel is defined as a region where the carrier density is controlled by the gate.

[0019] As shown in FIG. 4, in the laser irradiation step (step S1 in FIG. 1), a laser is irradiated onto a surface 3 extending to a predetermined depth of the semiconductor substrate 1. The laser is irradiated so as to be focused at a predetermined depth of the semiconductor substrate 1 from the lower surface 1b of the semiconductor substrate 1 where no device structure is formed. The laser is a laser in a wavelength range that is transmissive to the semiconductor substrate (in this example, a gallium nitride substrate). At the position of the focus point, the crystal (in this example, a single crystal of gallium nitride) constituting the semiconductor substrate 1 is heated and decomposed. As a result, at the position of the focus point, a modified layer composed of a deposition layer or the like of the constituent atoms of the crystal constituting the semiconductor substrate 1 (in this example, a deposition layer or the like of gallium) is formed. The strength of the modified layer is lower than that of the crystal constituting the semiconductor substrate 1. Therefore, the strength of the modified layer becomes lower than that of the surrounding crystals.

[0020] In the laser irradiation step, on the surface 3 extending to a predetermined depth of the semiconductor substrate 1, the laser is irradiated so that the power density of the laser in a region corresponding to below the channel CH (see FIG. 3) of the device structure 10 is lower than that in other regions. Specifically, when the semiconductor substrate 1 is viewed in plan view, the laser is irradiated so that the power density of the laser in at least a part of the region overlapping with the channel CH of the device structure 10, preferably, the entire region including the entire region overlapping with the channel CH of the device structure 10 is lower than that in other regions. Some examples of the laser irradiation step for forming such a power density distribution will be described later. Due to such a power density distribution, below the channel CH of the device structure 10, the light intensity of the laser that was not absorbed at the focus point becomes small, so that a part of the unabsorbed laser is suppressed from reaching the channel CH of the device structure 10. As a result, fluctuations in the electrical characteristics of the device structure 10 are suppressed.

[0021] As shown in FIG. 5, in the peeling step (step S2 in FIG. 1), the device layer 2 on which the device structure 10 is formed is peeled from the semiconductor substrate 1 along the surface 3 irradiated with the laser. Since the intensity of the surface 3 irradiated with the laser is reduced by the formation of the altered layer, the device layer 2 is peeled well from the semiconductor substrate 1. Note that the semiconductor substrate 1 after the device layer 2 is peeled is reused for manufacturing a semiconductor device. For example, after performing polishing, etching, etc. on the peeled surface of the semiconductor substrate 1, a device layer can be formed on the peeled surface by using an epitaxial crystal growth technique, and a device structure can be formed in the formed device layer.

[0022] As shown in FIG. 6, in the dicing step (step S3 in FIG. 1), after performing a polishing step, an electrode formation step, etc. on the device layer 2 peeled from the semiconductor substrate 1, a plurality of devices (also referred to as dice) are cut out from the device layer 2, and the semiconductor device is completed.

[0023] Hereinafter, a specific example of the above-described laser irradiation step will be described.

[0024] (First laser irradiation step) Referring to FIGS. 7 to 10, the first laser irradiation step will be described. As shown in FIG. 8, in the first laser irradiation step, first, laser irradiation coordinate data including a plurality of irradiation position coordinates 22 is created (step S11 in FIG. 7). The plurality of irradiation position coordinates 22 are coordinates that specify the positions at which the semiconductor substrate 1 is irradiated with the laser in a two-dimensional coordinate system that defines the in-plane position of the semiconductor substrate 1. One pulse of laser is irradiated to one irradiation position coordinate 22. The plurality of irradiation position coordinates 22 are not particularly limited, but in this example, they are set in a matrix pattern arranged periodically at equal intervals in the vertical and horizontal directions.

[0025] Next, as shown in FIG. 9, in a two-dimensional coordinate system, channel coordinate data including one or more channel position coordinates 24 is created (step S12 in FIG. 7). The one or more channel position coordinates 24 are coordinates that specify the position of the channel (see channel CH in FIG. 3) of the device structure formed on the upper surface of the semiconductor substrate 1. In this example, a plurality of channel position coordinates 24 are set in a matrix pattern arranged periodically at equal intervals vertically and horizontally. Since the channel of the device structure has a range, each of the plurality of channel position coordinates 24 is set so as to be able to specify the range. The plurality of channel position coordinates 24 may be set using mask data for photolithography for forming the device structure. Alternatively, the plurality of channel position coordinates 24 may be set from the position of the channel identified from the image obtained after forming the device structure on the upper surface of the semiconductor substrate 1 and acquiring the image of the upper surface of the semiconductor substrate 1.

[0026] Next, as shown in FIG. 10, the plurality of irradiation position coordinates 22 included in the laser irradiation coordinate data are classified into a plurality of first irradiation position coordinates 22a and a plurality of second irradiation position coordinates 22b (step S13 in FIG. 7). The plurality of first irradiation position coordinates 22a are coordinates that are not included in any of the plurality of channel position coordinates 24 among the plurality of irradiation position coordinates 22. The plurality of second irradiation position coordinates 22b are coordinates that are included in any of the plurality of channel position coordinates 24 among the plurality of irradiation position coordinates 22.

[0027] In the first laser irradiation step, a laser is irradiated into the semiconductor substrate 1 based on the plurality of first irradiation position coordinates 22a and the plurality of second irradiation position coordinates 22b created in this way (step S14 in FIG. 7). Specifically, the laser is irradiated to a predetermined depth of the semiconductor substrate 1 corresponding to the plurality of irradiation position coordinates 22 divided into the plurality of first irradiation position coordinates 22a, and the laser is not irradiated to a predetermined depth of the semiconductor substrate 1 corresponding to the plurality of irradiation position coordinates 22 divided into the plurality of second irradiation position coordinates 22b. As a result, on the surface extending the predetermined depth of the semiconductor substrate 1, the laser is irradiated so that the power density of the laser in the region corresponding to below the channel of the device structure is lower than that of other regions. As a result, it is possible to suppress a part of the laser that has not been absorbed at the focus point of the predetermined depth of the semiconductor substrate 1 from reaching the channel of the device structure.

[0028] Note that the laser may be irradiated to a predetermined depth of the semiconductor substrate 1 corresponding to the plurality of irradiation position coordinates 22 divided into the plurality of second irradiation position coordinates 22b with an irradiation energy smaller than the irradiation energy in the plurality of irradiation position coordinates 22 divided into the plurality of first irradiation position coordinates 22a. Even in this case, since the laser is irradiated so that the power density of the laser in the region corresponding to below the channel of the device structure is lower than that of other regions, it is possible to suppress a part of the unabsorbed laser at the focus point from reaching the channel of the device structure. In this example, the device layer can be peeled off well in the peeling step. The control of the irradiation energy of the laser is not particularly limited, but may be performed by controlling an attenuator or a spatial light modulator (SLM) of a reflective liquid crystal (LCOS: Liquid Crystal on Silicon).

[0029] (Second laser irradiation step) Referring to FIGS. 11 to 14, the second laser irradiation process will be described. In the cross-sectional views of FIGS. 12 to 14, the unit cells of the device structure 10 formed on the upper surface 1a side of the semiconductor substrate 1 are shown in a simplified manner. As shown in FIG. 12, in the second laser irradiation process, first, a laser light-shielding film 32 is formed on the entire lower surface 1b of the semiconductor substrate 1 (step S21 in FIG. 11). The laser light-shielding film 32 is a film that reflects laser light or is opaque to laser light. The laser light-shielding film 32 is not particularly limited, and for example, it may be an Al film or an Au film having a thickness of about 1 μm, or it may be a black matrix used in a color filter of a liquid crystal panel.

[0030] Next, as shown in FIG. 13, using an etching technique, a part of the laser light-shielding film 32 is removed so that the region corresponding to the lower part of the channel of the device structure 10 in the laser light-shielding film 32 remains (step S22 in FIG. 11). Specifically, when the semiconductor substrate 1 is viewed in plan, the laser light-shielding film 32 remains so as to include at least a part of the region overlapping the channel of the device structure 10, preferably all of the region overlapping the channel of the device structure 10.

[0031] Next, as shown in FIG. 14, a laser is irradiated from the lower surface 1b of the semiconductor substrate 1 to a predetermined depth of the semiconductor substrate 1 (step S23 in FIG. 11). The laser is irradiated to a predetermined depth of the semiconductor substrate 1 through the laser light-shielding film 32. Since the laser light-shielding film 32 blocks the laser, the laser is irradiated so that the power density of the laser in the region corresponding to the lower part of the channel of the device structure 10 is lower than that in other regions on the surface extending to the predetermined depth of the semiconductor substrate 1. As a result, it is possible to suppress a part of the laser (shown by a broken line) that has not been absorbed at the focal point at the predetermined depth of the semiconductor substrate 1 from reaching the channel of the device structure 10.

[0032] (Third laser irradiation process) Referring to FIGS. 15 to 20, the third laser irradiation process will be described. The third laser irradiation process is characterized in that a laser light-shielding film is formed in the semiconductor substrate prior to forming the device structure. As shown in FIG. 16, in the third laser irradiation process, first, a laser light-shielding film 42 is formed over the entire surface of the underlying substrate 100 (step S31 in FIG. 15). The material of the laser light-shielding film 42 may be the same as that of the laser light-shielding film 32 in the second laser light-shielding process.

[0033] Next, as shown in FIG. 17, using an etching technique, a part of the laser light-shielding film 42 is removed so that the laser light-shielding film 42 remains in a region corresponding to the formation position of the channel of the device structure to be formed later (step S32 in FIG. 15).

[0034] Next, as shown in FIG. 18, using an epitaxial technique, an epitaxial layer 110 is formed over the surface of the underlying substrate 100 to form a semiconductor substrate 1 (step S33 in FIG. 15). In this way, the laser light-shielding film 42 is formed by being embedded inside the semiconductor substrate 1.

[0035] Next, as shown in FIG. 19, a device structure 10 is formed on the upper surface 1a side of the semiconductor substrate 1 (step S34 in FIG. 15). The laser light-shielding film 42 embedded inside the semiconductor substrate 1 is arranged so as to include at least a part, preferably all, of the region overlapping with the channel of the device structure 10 when the semiconductor substrate 1 is viewed in plan.

[0036] Next, as shown in FIG. 20, a laser is irradiated from the lower surface 1b of the semiconductor substrate 1 to a predetermined depth of the semiconductor substrate 1 (step S35 in FIG. 15). The laser is irradiated to a predetermined depth of the semiconductor substrate 1 through the laser light-shielding film 42. By the laser light-shielding film 42 blocking the laser, the laser is irradiated so that the power density of the laser in the region corresponding to below the channel of the device structure 10 is lower than that of other regions on the surface extending the predetermined depth of the semiconductor substrate 1. As a result, a part of the laser (shown by a broken line) that was not absorbed at the focal point at the predetermined depth of the semiconductor substrate 1 is suppressed from reaching the channel of the device structure 10.

[0037] (Fourth laser irradiation step) Referring to FIGS. 21 to 26, the fourth laser irradiation step will be described. As shown in FIG. 22, in the fourth laser irradiation step, first, a mask 52 is formed on the entire lower surface 1b of the semiconductor substrate 1 (step S41 in FIG. 21). The mask 52 is not particularly limited, and may be, for example, a photoresist.

[0038] Next, as shown in FIG. 23, using an etching technique, a part of the mask 52 is removed so that the region corresponding to below the channel of the device structure 10 in the mask 52 opens (step S42 in FIG. 21). Specifically, when the semiconductor substrate 1 is viewed in plan, at least a part of the region overlapping the channel of the device structure 10, preferably, the entire region overlapping the channel of the device structure 10 remains so that it opens.

[0039] Next, as shown in FIG. 24, damage is applied to the lower surface 1b of the semiconductor substrate 1 exposed from the mask 52 to form a damage region 54 (step S43 in FIG. 21). The process for forming the damage region 54 is not particularly limited, and may be a wet etching process, a dry etching process of plasma irradiation, or an inert ion implantation process such as nitrogen ions or argon ions. The damage region 54 is a region where the surface roughness has increased after these processes.

[0040] Next, as shown in FIG. 25, the mask 52 is removed using an etching technique (step S44 in FIG. 21).

[0041] Next, as shown in FIG. 26, a laser is irradiated from the lower surface 1b of the semiconductor substrate 1 to a predetermined depth of the semiconductor substrate 1 (step S45 in FIG. 21). The laser is irradiated to a predetermined depth of the semiconductor substrate 1 through the damage region 54. Due to the damage region 54 blocking the laser by reflection and / or scattering, the laser is irradiated such that the power density of the laser in the region corresponding to below the channel of the device structure 10 is lower than that in other regions on the surface extending the predetermined depth of the semiconductor substrate 1. As a result, it is suppressed that a part of the laser (indicated by a broken line) that was not absorbed at the focal point at the predetermined depth of the semiconductor substrate 1 reaches the channel of the device structure 10.

[0042] Although the embodiments have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Also, the technology illustrated in this specification or the drawings achieves a plurality of purposes simultaneously, and has technical utility by achieving one of those purposes itself.

Description of Reference Numerals

[0043] 1: Semiconductor substrate, 2: Device layer, 10: Device structure, 22: Irradiation position coordinates, 22a: First irradiation position coordinates, 22b: Second irradiation position coordinates, 24: Channel position coordinates, 32, 42: Laser light-shielding film, 52: Mask, 54: Damage region, 100: Lower base substrate, 110: Epitaxial layer

Claims

1. A method for manufacturing a semiconductor device, comprising: a laser irradiation step of irradiating a surface (3) extending to a predetermined depth of a semiconductor substrate (1) with a laser in a wavelength range that is transmissive to the semiconductor substrate, wherein the semiconductor substrate has a first main surface (1a) and a second main surface (1b), and a device structure (10) having a channel (CH) is formed on the first main surface side, and the laser is irradiated so as to be focused at the predetermined depth of the semiconductor substrate from the second main surface; a peeling step of peeling a device layer (2) in which the device structure is formed from the semiconductor substrate along the surface irradiated with the laser; In the laser irradiation step, the laser is irradiated so that the power density of the laser in a region corresponding to below the channel of the device structure is lower than that in other regions on the surface extending to the predetermined depth of the semiconductor substrate. A method for manufacturing a semiconductor device.

2. The laser irradiation step includes: a step of creating laser irradiation coordinate data including a plurality of irradiation position coordinates (22) for specifying a position at which the laser is irradiated to the semiconductor substrate in a two-dimensional coordinate system defining an in-plane position of the semiconductor substrate; a step of creating channel coordinate data including one or more channel position coordinates (24) for specifying the position of the channel of the device structure in the two-dimensional coordinate system; a step of dividing the plurality of irradiation position coordinates included in the laser irradiation coordinate data into one or more first irradiation position coordinates (22a) not included in the one or more channel position coordinates and one or more second irradiation position coordinates (22b) included in the one or more channel position coordinates; irradiating the laser at the predetermined depth of the semiconductor substrate corresponding to the one or more first irradiation position coordinates, and not irradiating the laser at the predetermined depth of the semiconductor substrate corresponding to the one or more second irradiation position coordinates or irradiating the laser with irradiation energy smaller than the irradiation energy at the one or more first irradiation position coordinates. The method for manufacturing a semiconductor device according to Claim 1.

3. The laser irradiation step includes: a step of disposing a laser light-shielding film (32, 42) for shielding the laser in a region corresponding to below the channel of the device structure; A method of manufacturing a semiconductor device according to claim 1, comprising a step of irradiating the laser to the predetermined depth of the semiconductor substrate through the laser light-shielding film.

4. The step of disposing the laser light-shielding film includes: a step of forming the laser light-shielding film (32) over the entire second main surface of the semiconductor substrate; a step of removing a part of the laser light-shielding film so that a region corresponding to below the channel of the device structure remains, a method of manufacturing a semiconductor device according to claim 3.

5. The step of disposing the laser light-shielding film includes: a step of forming the laser light-shielding film (42) over the entire surface of the base substrate (100); a step of removing a part of the laser light-shielding film so that the laser light-shielding film in a region corresponding to the formation position of the channel of the device structure remains; a step of forming an epitaxial layer (110) over the surface of the base substrate to form the semiconductor substrate, a method of manufacturing a semiconductor device according to claim 3.

6. The laser irradiation step includes: a step of forming a mask (52) over the entire second main surface of the semiconductor substrate; a step of removing a part of the mask so that a region corresponding to below the channel of the device structure is open; a step of damaging the second main surface of the semiconductor substrate exposed from the mask to form a damage region (54); a step of removing the mask after forming the damage region; a step of irradiating the laser to the predetermined depth of the semiconductor substrate through the damage region, a method of manufacturing a semiconductor device according to claim 1.

7. The semiconductor substrate is a compound semiconductor, a method of manufacturing a semiconductor device according to any one of claims 1 to 6.

8. A method of manufacturing a semiconductor device, comprising: a laser irradiation step of irradiating a laser to a surface (3) extending to a predetermined depth of a semiconductor substrate (1), the semiconductor substrate having a first main surface (1a) and a second main surface (1b), and a device structure (10) having a channel (CH) being formed on the first main surface side, the laser being irradiated from the second main surface to the predetermined depth of the semiconductor substrate; a peeling step of peeling the device layer (2) in which the device structure is formed from the semiconductor substrate along the surface irradiated with the laser. In the laser irradiation step, the laser is irradiated such that the power density of the laser in a region corresponding to below the channel of the device structure is lower than that in other regions on the surface of the semiconductor substrate extending to the predetermined depth. The laser irradiation step includes a step of creating laser irradiation coordinate data including a plurality of irradiation position coordinates (22) for specifying a position at which the laser is irradiated onto the semiconductor substrate in a two-dimensional coordinate system defining an in-plane position of the semiconductor substrate. includes a step of creating channel coordinate data including one or more channel position coordinates (24) for specifying a position of the channel of the device structure in the two-dimensional coordinate system. includes a step of classifying the plurality of irradiation position coordinates included in the laser irradiation coordinate data into one or more first irradiation position coordinates (22a) not included in the one or more channel position coordinates and one or more second irradiation position coordinates (22b) included in the one or more channel position coordinates. A method of manufacturing a semiconductor device, comprising: irradiating the laser at the predetermined depth of the semiconductor substrate corresponding to the one or more first irradiation position coordinates; and not irradiating the laser at the predetermined depth of the semiconductor substrate corresponding to the one or more second irradiation position coordinates or irradiating the laser with an irradiation energy smaller than the irradiation energy at the one or more first irradiation position coordinates.

9. A method of manufacturing a semiconductor device, comprising: a laser irradiation step of irradiating a laser onto a surface (3) of a semiconductor substrate (1) extending to a predetermined depth, the semiconductor substrate having a first main surface (1a) and a second main surface (1b), and a device structure (10) having a channel (CH) being formed on the first main surface side, the laser being irradiated from the second main surface to the predetermined depth of the semiconductor substrate; a peeling step of peeling the device layer (2) in which the device structure is formed from the semiconductor substrate along the surface irradiated with the laser; In the laser irradiation step, the laser is irradiated such that the power density of the laser in a region corresponding to below the channel of the device structure is lower than that in other regions on the surface of the semiconductor substrate extending to the predetermined depth. The laser irradiation step includes a step of disposing a laser light-shielding film (32, 42) for shielding the laser in a region corresponding to below the channel of the device structure. A step of irradiating the laser to the predetermined depth of the semiconductor substrate through the laser light-shielding film, and The step of disposing the laser light-shielding film is A step of forming the laser light-shielding film (42) over the entire surface of the base substrate (100), and A step of removing a part of the laser light-shielding film so that the laser light-shielding film in a region corresponding to the formation position of the channel of the device structure remains, and A step of forming an epitaxial layer (110) over the surface of the base substrate to form the semiconductor substrate, A method of manufacturing a semiconductor device.

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