Laser irradiation apparatus, laser irradiation method, and method for manufacturing semiconductor devices

Abstract

A laser irradiation apparatus according to the present embodiment comprises: a semiconductor laser light source that generates laser light (15) having a wavelength of 250-500 nm; a rotating stage (11) that rotates a semiconductor substrate; an optical system unit (30) that guides the laser light (15) to the semiconductor substrate on the rotating stage; and a moving mechanism that moves the optical system unit (30) so as to change the irradiated position of the laser light (15) in a direction different from a rotating direction of the rotating stage in a top plan view.

Description

[Technical Field]

[0001] The present invention relates to a laser irradiation apparatus, a laser irradiation method, and a method for manufacturing semiconductor devices. [Background technology]

[0002] Patent Document 1 discloses a laser annealing apparatus using an excimer laser. In Patent Document 1, a levitation unit levitates the substrate, while a transport unit transports the substrate. A line of laser light is then irradiated onto the substrate while it is being transported. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2018-64048 [Overview of the project] [Problems that the invention aims to solve]

[0004] Because such excimer laser light sources are expensive, it is difficult to reduce the component costs of the equipment. Therefore, it is desirable to use light sources other than excimer lasers. Semiconductor lasers are inexpensive, but they are continuous wave (CW) lasers. When CW laser light is pulsed with a modulator, the output power decreases. Therefore, many light sources are required, making cost reduction difficult.

[0005] Other challenges and novel features will become apparent from the description and accompanying drawings in this specification.

[0006] According to one embodiment, the laser irradiation device includes a semiconductor laser light source that generates laser light with a wavelength of 250 nm or more and a wavelength of 500 nm or less, a rotating stage that rotates a semiconductor substrate, an optical system unit that guides the laser light to the semiconductor substrate on the rotating stage, and a moving mechanism that moves the optical system unit so as to change the irradiation position of the laser light in a direction different from the rotation direction of the rotating stage when viewed from above.

[0007] According to one embodiment, the laser irradiation method includes (A1) generating laser light with a wavelength of 250 nm or more and a wavelength of 500 nm or less using a semiconductor laser light source, (A2) guiding the laser light to a semiconductor substrate on the rotating stage using an optical system unit, and (A3) moving the optical system unit so as to change the irradiation position of the laser light in a direction different from the rotation direction of the rotating stage when viewed from above.

[0008] According to one embodiment, a method for manufacturing a semiconductor device includes the steps of (S1) generating laser light with a wavelength of 250 nm or more and 500 nm or less using a semiconductor laser light source, (S2) guiding the laser light to a semiconductor substrate on the rotating stage using an optical system unit, and (S3) moving the optical system unit so as to change the irradiation position of the laser light in a direction different from the rotation direction of the rotating stage when viewed from above.

[0009] According to the above embodiment, it is possible to provide a highly productive laser irradiation apparatus, a laser irradiation method, and a method for manufacturing semiconductor devices. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic side view showing a laser irradiation device according to Embodiment 1. [Figure 2] This is a schematic top view showing a laser irradiation device according to Embodiment 1. [Figure 3] This is a schematic diagram showing the spatial distribution of the beam and the overlapping portion of the laser light. [Figure 4] It is a side view schematically showing the laser irradiation apparatus according to Embodiment 2. [Figure 5] It is a top view schematically showing the laser irradiation apparatus according to Embodiment 2. [Figure 6] It is a side view schematically showing the laser irradiation apparatus according to Embodiment 3. [Figure 7] It is a top view schematically showing the laser irradiation apparatus according to Embodiment 3. [Figure 8] It is a cross-sectional view showing the configuration of a semiconductor device manufactured by a laser irradiation process. [[ID=十七]]

Embodiments for Carrying Out the Invention

[0011] Embodiment 1 The laser irradiation apparatus according to this embodiment performs annealing treatment by irradiating a workpiece (also referred to as a work) with laser light. The laser irradiation apparatus performs an activation treatment on a semiconductor layer provided on a substrate by heating the substrate with laser light. The workpiece is a semiconductor substrate for forming a semiconductor device. The semiconductor substrate is a silicon wafer or a compound semiconductor wafer.

[0012] For example, power semiconductor devices such as vertical MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors) are formed on the semiconductor substrate. That is, the workpiece is a semiconductor wafer on which chips of power semiconductor devices are formed. The semiconductor substrate has a semiconductor layer (also referred to as an impurity implantation layer) into which impurities are implanted. By irradiating the semiconductor layer with laser light using the laser irradiation apparatus, the semiconductor layer can be activated. Further, the method according to this embodiment is not limited to power semiconductors. For example, the method according to this embodiment can be applied to the activation of a semiconductor layer of a semiconductor chip such as an image sensor and its manufacturing method.

[0013] Alternatively, the laser irradiation device may be a device for performing dehydrogenation annealing treatment. In the dehydrogenation annealing treatment, dehydrogenation annealing treatment is performed on the film provided on the substrate by heating the substrate with laser light. For example, the object to be processed is a substrate with a film on which a silicon film is formed.

[0014] The laser irradiation device uses a blue semiconductor laser light source as the laser light source. The laser irradiation device performs an annealing treatment for activation by irradiating the object to be processed with blue laser light from the semiconductor laser light source. Note that the laser light is not limited to blue laser light and can be laser light with a wavelength of 250 nm or more and 500 nm or less. The laser irradiation device irradiates the object to be processed with blue laser light from the semiconductor laser light source. Thereby, an activation treatment or a dehydrogenation treatment can be performed. Note that the laser light is not limited to blue laser light and can be laser light with a wavelength of 500 nm or less.

[0015] The configuration of the laser irradiation device according to the present embodiment will be described with reference to FIGS. 1 to 2. FIG. 1 is a side view schematically showing the configuration of the laser irradiation device 1. FIG. 2 is a top view schematically showing the configuration of the laser irradiation device 1.

[0016] In the figures shown below, for the sake of simplicity of explanation, an XYZ three-dimensional orthogonal coordinate system is shown as appropriate. The Z direction is the vertical up-and-down direction and is perpendicular to the main surface of the object to be processed 16. The X direction is the moving direction of the optical system unit 30. By moving the optical system unit 30, the irradiation position of the laser light 15 changes in the X direction. The Y direction is perpendicular to the Z direction and the X direction.

[0017] As shown in FIGS. 1 to 2, the laser irradiation device 1 includes a chamber 10, an optical system unit 30, a laser light source 35, an optical fiber 36, an optical system stage 40, a linear motion mechanism 41, a guide mechanism 43, a gantry 60, a rotation motor 61, a measuring instrument 70, and the like. In FIG. 1, the optical system unit 30 is shown in a state of moving above the chamber 10, and in FIG. 2, the optical system unit 30 is shown in a state of retracting from above the chamber 10.

[0018] The frame 60 supports the chamber 10 and the optical stage 40, etc. The chamber 10 is fixed on the frame 60. The chamber 10 houses the workpiece 16 and the stage 11, etc. The stage 11 is connected to a rotary motor 61. The rotary motor 61 is fixed to the frame 60. The rotary motor 61 rotates the stage 11 around the rotation axis AX. The rotation axis AX is parallel to the Z direction.

[0019] A suction plate 12 for adsorbing the object to be processed 16 is fixed on the stage 11. The suction plate 12 is equipped with, for example, a vacuum chuck or an electrostatic chuck, and holds the object to be processed 16 by suction. The object to be processed 16 is transferred into the chamber 10 and placed on the suction plate 12. With the suction plate 12 holding the object to be processed 16 by suction, the rotary motor 61 rotates the stage 11. This changes the irradiation position of the laser beam 15 on the object to be processed 16.

[0020] As shown in Figure 2, four suction plates 12 are attached to the stage 11. Therefore, four objects to be processed 16 are placed on the stage 11. By arranging multiple objects to be processed 16 on the stage 11, throughput is improved. The multiple objects to be processed 16 are arranged rotationally symmetrically with respect to the rotation axis AX. Specifically, the centers of the four objects to be processed 16 are arranged on a circle centered on the rotation axis AX. Laser light can be irradiated almost uniformly onto the multiple objects to be processed 16.

[0021] In Figure 2, the four objects to be processed 16 are arranged at equal intervals of 90° in the rotational direction (circumferential direction) of the stage 11. Of course, the number of objects to be processed 16 that can be placed on the stage 11 is not limited to four. In other words, the stage 11 only needs to be able to hold one or more objects to be processed 16.

[0022] The object to be processed 16 is substantially a circular semiconductor wafer. The semiconductor wafer may have orientation flats, notches, etc. formed on it. The object to be processed 16 comprises a substrate 16a and a semiconductor layer 16b formed on the substrate 16a. The substrate 16a is a semiconductor substrate such as a silicon wafer or a compound semiconductor wafer (SiC, GaN). Of course, the material of the substrate 16a is not particularly limited. The substrate 16a is opaque to light of the laser wavelength.

[0023] The semiconductor layer 16b is an impurity-implanted layer in which impurities such as phosphorus (P) and boron (B) are implanted. The PN junction can be activated by annealing the semiconductor layer 16b by irradiating it with laser light 15. In other words, the laser irradiation device 1 becomes an annealing device for activating the semiconductor layer 16b. Although only the semiconductor layer 16b is shown in Figure 1, other films and layers may be formed. For example, thin films of copper or aluminum that serve as wiring may be formed. Furthermore, an insulating layer such as a silicon oxide film may be formed on the substrate 16a.

[0024] A window portion 14 is provided on the upper surface of the chamber 10. The window portion 14 is made of a transparent material such as glass or resin. Laser light 15 passes through the window portion 14. When viewed from above, the window portion 14 is formed in a rectangular shape with the X direction as its longitudinal direction. In other words, the window portion 14 is formed along the direction of movement of the optical system stage 40, which will be described later. The window portion 14 is also arranged along the radial direction perpendicular to the rotation direction of the stage 11.

[0025] The optical system stage 40 supports the optical system unit 30. As shown in Figure 1, the optical system stage 40 can hold the optical system unit 30 above the stage 11. Specifically, the optical system stage 40 is attached to the mount 60 via a guide mechanism 43. The guide mechanism 43 comprises a linear guide 43a and a slider 43b. The linear guide 43a has a guide rail or guide groove extending along the X direction. The slider 43b slides along the linear guide 43a in the X direction. The linear guide 43a is fixed to the mount 60. The slider 43b is fixed to the optical system stage 40. The linear guide 43a holds the slider 43b in a slidable manner.

[0026] Furthermore, a linear motion mechanism 41 is provided between the optical system stage 40 and the mount 60. The linear motion mechanism 41 is equipped with an actuator such as a linear motor. As the linear motion mechanism 41 extends and retracts, the optical system stage 40 moves in the X direction. In other words, the optical system stage 40 is guided by the guide mechanism 43 and moves along the X direction. As the optical system stage 40 moves, the position of the optical system unit 30 changes in the X direction.

[0027] In this way, the linear motion mechanism 41 drives the optical system stage 40, causing the optical system unit 30 to move in the X direction. Therefore, the linear motion mechanism 41 and the guide mechanism 43 constitute the moving mechanism for the optical system unit 30. Note that the moving mechanism for moving the optical system unit 30 is not limited to the above configuration, and known methods can be used. For example, the moving mechanism may include a ball screw or a cylinder.

[0028] In addition, a rack 38 is provided separately from the frame 60 to hold the laser light source 35. The laser light source 35 is fixed to the rack 38. The laser light source 35 generates laser light 15 for annealing the workpiece 16. The laser light source 35 is a BLD (Blue Laser Diode) that generates blue laser light with a central wavelength of 450 nm. In other words, the laser light source 35 is a blue semiconductor laser light source. Here, the laser light 15 is a continuous wave (CW) laser light. Of course, the laser irradiation device 1 may also modulate the laser light 15 into pulsed laser light using a modulator or the like.

[0029] The laser light source 35 is coupled to the optical fiber 36. The laser light 15 is guided to the optical system unit 30 via the optical fiber 36. Specifically, one end of the optical fiber 36 is connected to the laser light source 35 via an optical connector 32. The other end of the optical fiber 36 is connected to the optical system unit 30 via the optical connector 32. The optical connector 32 is mounted on the top surface of the optical system unit 30. Therefore, the laser light 15 emitted from the optical connector 32 travels in the -Z direction.

[0030] Laser light from the laser light source 35 enters the optical system unit 30 via the optical fiber 36. As shown in Figure 1, the optical system unit 30 comprises a housing 310, a lens 301, a lens 302, and a beam shaping unit 307. Lenses 301, 302, and the beam shaping unit 307 are fixed to the housing 310. Of course, the optical system unit 30 may also be provided with optical elements other than lenses 301, 302, and the beam shaping unit 307.

[0031] The laser light from the optical fiber 36 enters the beam shaping unit 307. The beam shaping unit 307 shapes the spot shape of the laser light 15. For example, the beam shaping unit 307 has a beam shaping mechanism such as a slit. Alternatively, if multiple optical fibers 36 are used, the beam may be shaped by the arrangement of the exit ends of the optical fibers 36.

[0032] The laser beam 15 may be a Gaussian beam or a top-flat beam. In the case of a Gaussian beam, the spatial intensity distribution of the laser beam 15 in the workpiece 16 is a Gaussian distribution. In the case of a top-flat beam, the spatial intensity distribution of the laser beam 15 in the workpiece 16 is a top-flat distribution. The beam shaping unit 307 may have a beam homogenizer to make the spatial intensity distribution uniform. For example, the beam shaping unit 307 may have a beam homogenizer to create a top-flat distribution. The beam homogenizer has optical elements such as a fly-eye lens.

[0033] For example, the beam shaping unit 307 forms a top-flat beam in the workpiece 16 with a flat distribution along the X direction. Alternatively, the spot shape of the beam in the workpiece 16 may be a line beam having a longitudinal direction and a transverse direction. In this case, the spot shape in the workpiece 16 can have the X direction as the longitudinal direction and the Y direction as the transverse direction. For example, the size of the spot in the longitudinal direction may be about 1 mm, and the size of the spot in the X direction may be 0.2 mm. The beam shaping unit 307 can then shape the beam so that it becomes a top-flat beam with a uniform intensity distribution in the X direction. Of course, the beam shaping unit 307 may also form a top-flat beam with a uniform intensity distribution in the Y direction. The spot shape of the beam in the workpiece 16 and its spatial distribution will be described later.

[0034] The laser beam shaped in the beam shaping unit 307 enters the lens 301. The laser beam 15 focused by the lens 301 enters the lens 302. The optical axes of lenses 301 and 302 are parallel to the Z direction. The laser beam 15 from lens 302 is irradiated onto the workpiece 16. Lens 302 focuses the laser beam 15 onto the workpiece 16. Therefore, the laser beam 15 from the optical system unit 30 becomes a focused beam and irradiates the workpiece 16. Lens 302 may be a cylindrical lens. In this way, the laser beam 15 can be made into a line beam that forms a line shape on the workpiece 16.

[0035] The lens 302 focuses the laser beam 15 onto the object to be processed 16. In Figure 1, the optical system unit 30 is positioned directly above the window 14. The laser beam 15 from the optical system unit 30 enters the object to be processed 16 through the window 14. The optical system unit 30 moves along the window 14. The optical system unit 30 irradiates the object to be processed 16 with the laser beam 15 from above. The semiconductor layer 16b of the object to be processed 16 is annealed, and the semiconductor layer 16b can be subjected to activation treatment.

[0036] Stage 11 is a rotary stage equipped with a rotary motor 61. Stage 11 rotates around a rotation axis AX parallel to the Z-axis. While Stage 11 rotates, the optical system unit 30 moves in the X direction. In a top view, the direction of movement of the optical system unit 30 and the direction of rotation of Stage 11 intersect. Specifically, the direction of movement of the optical system unit 30 is parallel to the radial direction of Stage 11. The radial direction is perpendicular to the direction of rotation. In this way, laser light can be irradiated to any position on the object to be processed 16.

[0037] By rotating the workpiece 16 using the stage 11, the entire workpiece 16 can be irradiated with laser light 15 in a short time. Therefore, the workpiece 16 can be irradiated with laser light at a high throughput, thereby improving productivity.

[0038] For example, the rotation of stage 11 changes the position of the laser beam 15 in the circumferential direction. The movement of optical system unit 30 changes the position of the laser beam 15 in the radial direction. In Figure 2, the trajectory of the laser beam 15 irradiated onto stage 11 is shown as irradiation trajectory T1.

[0039] In Figure 2, the ends of the irradiation position of the laser beam 15 in the X direction are shown as laser beams 15a and 15b. The end of the irradiation position in the -X direction corresponds to laser beam 15a, and the end of the irradiation position in the +X direction corresponds to laser beam 15b. The laser beams 15a and 15b are incident on the workpiece 16 through the window portion 14.

[0040] The optical system unit 30 moves the irradiation position of the laser beam 15 from the position indicated by laser beam 15a to the position indicated by laser beam 15b. The irradiation position of laser beam 15a is at one end of the workpiece 16 furthest from the rotation axis AX, and the irradiation position of laser beam 15b is at the other end of the workpiece 16 closest to the rotation axis AX. In other words, the optical system unit 30 moves so that the irradiation position of the laser beam 15 changes radially from one end to the other of the workpiece 16. The range of movement of the optical system unit 30 corresponds to the diameter of the workpiece 16. This makes it possible to irradiate the entire workpiece 16 with laser beam 15.

[0041] For example, while the stage 11 is rotating at a constant rotational speed, the optical system unit 30 moves in the X direction. The optical system unit 30 moves from the outer edge of the stage 11 toward the rotation axis AX. In the Y direction, the irradiation position of the laser beam 15 coincides with the position of the rotation axis AX. While the stage 11 is rotating, the optical system unit 30 moves continuously or stepwise in the -X direction. This causes the trajectory of the laser beam 15 on the stage 11 to become spiral-shaped. Therefore, the laser beam can be irradiated evenly onto multiple workpieces 16. Alternatively, while the workpieces 16 are rotating, the optical system unit 30 may move back and forth in the +X and -X directions.

[0042] Furthermore, a measuring instrument 70 is provided on the +X side of the chamber 10. The measuring instrument 70 has a photodetector such as a photodiode and measures the beam profile of the laser light 15. In other words, the measuring instrument 70 measures the spatial distribution of the laser light 15 in a cross section perpendicular to the optical axis, i.e., in the XY plane. For example, the measuring instrument 70 has a plurality of pixels (photodetectors) arranged in a row or array. It is preferable that the light-receiving surface of the measuring instrument 70 be at the same height as the object to be processed 16. This allows the measuring instrument 70 to measure a beam profile equivalent to the beam profile on the object to be processed 16.

[0043] The measuring instrument 70 has multiple pixels arranged along the X direction. Therefore, the uniformity of the laser light spot in the longitudinal direction can be evaluated based on the measurement results of the measuring instrument 70. In other words, the uniformity of the top flat distribution can be evaluated, enabling a stable process. The measuring instrument 70 is located outside the stage 11. Therefore, the measuring instrument 70 can measure the beam profile of the laser light 15 before or after the laser irradiation process.

[0044] In this embodiment, a blue semiconductor laser diode (BLD) is used as the laser light source 35. This allows for reduced equipment costs. BLDs have low photon costs. Furthermore, wavelength conversion elements and other components can be eliminated. This enables processing with high energy efficiency. In addition, since BLDs have a long lifespan, maintenance costs can be reduced, and a highly productive laser irradiation device 1 can be realized.

[0045] The laser light 15 from the BLD has low coherence. Using the BLD makes it easy to generate a top-flat beam with a top-flat distribution. When generating a top-flat beam, the beam homogenizer used in the beam shaping unit 307 can be used. In the beam homogenizer, the desired spatial distribution can be obtained by splitting or superimposing the beam using a lens array or diffracting photons. Due to the low coherence, no interference fringes are generated in the beam homogenizer. Even when the laser light from the BLD is guided through the optical fiber 36, no speckles (interference fringes) are generated. Therefore, the laser light can be irradiated uniformly, enabling a stable laser irradiation process. Thus, a highly productive laser irradiation apparatus 1 can be realized.

[0046] The beam shaping unit 307 reduces the number of laser beam superpositions by transforming the laser beam into a top-flat beam. This improves throughput and thus productivity. This point will be explained using Figure 3. Figure 3 is a schematic diagram illustrating the overlapping portion of the laser beam between the top-flat beam and the Gaussian beam.

[0047] In Figure 3, the laser beam spot during the first pass of stage 11 is shown as spot 15-1, and the spot during the second pass of stage 11 is shown as spot 15-2. Spot 15-2 has moved to the -X side compared to spot 15-1. Also, spots 15-1 and 15-2 on the workpiece 16 are in the shape of a line with the X direction as the longitudinal direction and the Y direction as the short direction.

[0048] In a top-flat beam, the region X1 where the laser light intensity I is uniform is long. Therefore, the proportion of overlap between the first and second rotations can be reduced. The length F1 of the overlapping portion can be shortened. In other words, the travel distance during one rotation of the stage 11 can be increased, and thus the travel speed of the optical system unit 30 can be increased.

[0049] On the other hand, with a Gaussian beam, the region X2 where the laser light intensity I is uniform is short. Therefore, the proportion of overlap between the first and second rotations becomes large. It is necessary to increase the length F2 of the overlapping region. In other words, since the distance traveled during one rotation of the stage 11 becomes short, it is difficult to increase the movement speed of the optical system unit 30.

[0050] Therefore, by using a top flat beam, even when irradiating almost the entire surface of the workpiece 16 with laser light, the number of times the beam spot overlaps can be reduced. This allows for higher rotation and movement speeds, thereby improving throughput and productivity.

[0051] Furthermore, on the stage 11, the closer the radial position is to the rotation axis AX, the shorter the circumference becomes. The distance from the rotation axis AX to the irradiation position is defined as the radius of rotation. Assuming a constant rotation speed, the irradiation time per unit length in the circumferential direction changes according to the radius of rotation. Therefore, it is preferable to change the movement speed of the optical system unit 30 according to its position in the X direction. In other words, it is preferable to increase the movement speed in the X direction as the radius of rotation decreases. For example, the movement speed of the optical system unit 30 is fastest at the irradiation position of laser beam 15a, and slowest at the irradiation position of laser beam 15b. By doing so, the amount of laser beam irradiated per unit area can be made uniform.

[0052] This section describes the case where the optical system unit 30 moves continuously in the X direction while the stage 11 rotates at a constant rotational speed (number of rotations). In this case, the movement speed of the optical system unit 30 is increased as it approaches the rotation axis AX. Specifically, the distance from the rotation axis AX to the irradiation position (radius of rotation) is made to have a linear relationship with the movement speed. By doing so, the entire workpiece 16 can be uniformly irradiated with laser light.

[0053] Alternatively, the movement speed of the optical unit 30 may be kept constant, and the rotation speed of the stage 11 may be varied. In other words, the smaller the radius of rotation, the faster the rotation speed may be.

[0054] Let's explain an example of rotational speed and movement speed. Here, we will assume that the workpiece 16 is a semiconductor wafer with a diameter of 300 mm, and that the rotational radius varies in the range of 450 mm to 750 mm. That is, at the irradiation position of the laser beam 15a in Figure 2, the rotational radius is 450 mm, and at the position of the laser beam 15b, the rotational radius is 750 mm. Also, the movement distance in the X direction for one rotation of the stage 11 is assumed to be 0.2 mm.

[0055] When the movement speed of the optical system unit 30 in the X direction is 20 m / sec, the rotation speed can be set to 4.24 rps for a rotation radius of 750 mm, and to 7.07 rps for a rotation radius of 450 mm.

[0056] When the movement speed of the optical system unit 30 in the X direction is 10 m / sec, the rotation speed can be set to 2.12 rps when the rotation radius is 750 mm, and to 3.54 rps when the rotation radius is 450 mm.

[0057] If the movement speed of the optical unit 30 in the X direction is 5 m / sec, the rotation speed can be set to 1.06 rps when the rotation radius is 750 mm, and to 1.77 rps when the rotation radius is 450 mm. Of course, the rotation speed and movement speed are not limited to the above examples.

[0058] Blue wavelength light has an appropriate penetration depth into silicon wafers. The laser light source 35 generates laser light with a wavelength of 250 nm to 500 nm. By using laser light with a central wavelength of 250 nm to 500 nm, the semiconductor layer can be appropriately activated. By using laser light with a deeper penetration depth into the semiconductor layer 16b, activation can be performed even to deeper regions. Furthermore, since a continuous-oscillation semiconductor laser light source can be used in this wavelength range, the equipment configuration can be simplified and costs can be reduced.

[0059] For example, a laser beam with a wavelength of 450 nm penetrates a silicon film to a depth of 0.24 μm. Therefore, absorption of the laser beam by the semiconductor layer 16b can be suppressed, allowing the laser beam to reach deeper regions of the semiconductor layer 16b. This makes it suitable for manufacturing semiconductor devices in which PN junctions are formed in deep regions. For example, the laser irradiation device 1 is suitable for activating power semiconductor devices such as vertical MOSFETs and IGBTs. The laser irradiation device 1 is suitable for activation treatment of semiconductor devices in which PN junctions are formed in deep regions of the semiconductor substrate. Semiconductor devices can be manufactured with high productivity. By using a semiconductor laser light source as the laser light source 35, the lifespan can be extended compared to solid-state lasers.

[0060] In this embodiment, the laser light source 35 is fixed to a rack 38 separate from the frame 60. Therefore, the laser light source 35 can be easily replaced and maintained. Alternatively, a modulator may be used to make the laser light pulsed. Furthermore, the laser light may be directed onto the workpiece 16 when it is directly below the window 14. This prevents the laser light from being directed onto the stage 11 when the workpiece 16 is not directly below the window 14.

[0061] Furthermore, the measuring instrument 70 measures the profile of the laser beam. This allows the workpiece 16 to be irradiated with laser beam with a uniform spatial distribution. Because the workpiece 16 can be irradiated with laser beam stably, productivity can be improved.

[0062] Embodiment 2 The laser irradiation device 1 according to Embodiment 2 will be described with reference to Figures 4 and 5. Figure 4 is a schematic side view showing the configuration of the laser irradiation device 1. Figure 5 is a schematic top view showing the configuration of the laser irradiation device 1. In Embodiment 2, the arrangement of the laser light source 35 differs from that of Embodiment 1. Specifically, the laser light source 35 is fixed to the optical system stage 40. The basic configuration other than the arrangement of the laser light source 35 is the same as in Embodiment 1, so its explanation will be omitted as appropriate.

[0063] The laser light source 35 is installed on the optical system stage 40. Therefore, the laser light source 35 moves in the X direction together with the optical system stage 40. In other words, the laser light source 35 moves in the X direction by the operation of the linear motion mechanism 41. Even with this configuration, the same effects as in Embodiment 1 can be obtained. Furthermore, the length of the optical fiber 36 can be shortened. Therefore, the loss of light in the optical fiber 36 can be reduced.

[0064] Embodiment 3 The laser irradiation device 1 according to Embodiment 3 will be described with reference to Figures 6 and 7. Figure 6 is a schematic side view showing the configuration of the laser irradiation device 1. Figure 7 is a schematic top view showing the configuration of the laser irradiation device 1. In Embodiment 3, an optical fiber 36 is not provided between the laser light source 35 and the optical system unit 30. Also, the configuration of the optical system in the optical system unit 30 differs from that of Embodiments 1 and 2. The other basic configurations are the same as in Embodiments 1 and 2, so their explanation will be omitted as appropriate.

[0065] The laser light source 35 is fixed to the optical system stage 40, similar to the second embodiment. In addition, a mirror 303 is positioned between lens 301 and lens 302 in the optical system unit 30. The laser light source 35 moves in the X direction together with the optical system unit 30. That is, the laser light source 35, along with lens 301, mirror 303, lens 302, etc., moves in the X direction. The laser light source 35 propagates the laser beam 15 in the -X direction and is incident on lens 301.

[0066] The optical axis of lens 301 is parallel to the X direction. Lens 301 makes the laser beam 15 a parallel beam. The laser beam 15 from lens 301 is reflected by mirror 303 and travels in the -Z direction. The laser beam 15 from mirror 303 is incident on lens 302. Lens 302 focuses the laser beam 15 onto the object to be processed 16. In this way, the same effects as in embodiments 1 and 2 can be obtained. Unlike embodiments 1 and 2, there is no optical fiber 36 between the laser light source 35 and lens 301. Because optical fiber 36 is not used, light loss can be suppressed.

[0067] Furthermore, a beam shaping unit 307, as shown in Embodiments 1 and 2, may be provided between the lens 301 and the laser light source 35. Also, in Embodiments 1 to 3, the beam shaping unit 307 may be located in a position other than before the lens 301. In other words, the position of the beam shaping unit 307 is not particularly limited.

[0068] In embodiments 2 and 3, the laser light source 35 was described as being fixed to the optical system stage 40, but the laser light source 35 may also be fixed to the stand 60. In other words, the laser light source 35 does not need to move in the X direction together with the optical system unit 30. In this case, in embodiment 3, it is preferable to make the laser light 15 a parallel beam using the lens 301.

[0069] The laser irradiation method using the laser irradiation device 1 described in Embodiments 1 to 3 includes, for example, the following steps 1 to 3. (Step 1) A step in which a semiconductor laser light source is used to generate laser light with a wavelength of 250 nm or more and a wavelength of 500 nm or less. (Step 2) The optical system unit guides the laser light onto the semiconductor substrate on the rotating stage. (Step 3) A step of moving the optical system unit so that the irradiation position of the laser light is changed to a direction different from the rotation direction of the rotating stage when viewed from above.

[0070] The laser irradiation method according to this embodiment is applicable to a method for manufacturing a semiconductor device. Thereby, a semiconductor device can be manufactured with high productivity.

[0071] (Semiconductor device) Hereinafter, an example of a semiconductor device manufactured by the manufacturing method according to this embodiment will be described. FIG. 8 is a cross-sectional view showing the stacked structure of the semiconductor device 6**0. The semiconductor device 6**0 is a vertical MOSFET. Specifically, the semiconductor device 6**0 is a planar MOSFET, with the back side of the semiconductor substrate 6**5 being the drain and the front side being the source and the gate. The semiconductor substrate 6**5 is a silicon substrate.

[0072] In the semiconductor device 6**0, an n + layer 6**1, an n - layer 6**2, a p layer 6**3, and an n + layer 6**4 are formed in this order from the back side of the semiconductor substrate 6**5. Further, a gate electrode 6**10 and a source electrode 6**20 are formed on the surface of the semiconductor substrate 6**5. The gate electrode 6**10 and the source electrode 6**20 are metal thin films such as copper or aluminum. The semiconductor substrate 6**5 corresponds to the object to be processed 16 or the substrate 16a described above.

[0073] The n + layer 6**1, the n - layer 6**2, the p layer 6**3, and the n + layer 6**4 are implanted with impurities. For example, boron is implanted as a dopant in the p layer 6**3. Phosphorus is implanted as a dopant in the n + layer 6**1, the n - layer 6**2, and the n + layer 6**4. The n + layer 6**1, the n - layer 6**2, the p layer 6**3, or the n + layer 6**4 corresponds to the semiconductor layer 16b.

[0074] By irradiating the semiconductor substrate 6**5 with laser light from the laser irradiation device 1, the n + layer 6**1, the n - layer 6**2, the p layer 6**3, and the n+ One or more layers of layer 604 can be activated. Laser light 15 is irradiated from the upper surface of the semiconductor substrate 605. In this way, n + Layer 601, n - Layer 602, p-layer 603, or n + Layer 604 can be activated. The order of the laser irradiation steps is not particularly limited.

[0075] Furthermore, the method according to this embodiment is an irradiation method for activating a semiconductor layer of a semiconductor device, comprising the steps of: generating laser light with a wavelength of 250 nm or more and 500 nm or less; guiding the laser light to a semiconductor substrate using an optical system unit; and changing the relative irradiation position of the laser light with respect to the semiconductor substrate. This method can appropriately activate the semiconductor layer. This laser irradiation method is suitable for semiconductor device manufacturing methods. In other words, the laser irradiation method is applied to the activation process in semiconductor device manufacturing methods.

[0076] Some or all of Embodiments 1 to 3 can be used in combination as appropriate. Furthermore, the present invention is not limited to the above embodiments, and can be modified as appropriate without departing from the spirit of the invention. [Explanation of symbols]

[0077] 1. Laser irradiation device 10 Chambers 11 stages 12 Adsorption plate 14 Window section 15 Laser light 16. Object to be processed 16a substrate 16b Semiconductor layer 30 Optical Units 32 Optical Connectors 35 Laser light source 36 Optical Fibers 40 Optical Stages 41 Linear motion mechanism 43 Guide mechanism 43a Linear guide 43b Slider 60 mounting bases 70 Measuring Instruments 301 Lens 302 Lens 303 Mirror 307 Beam Shaping Section 310 cabinets 600 Semiconductor Devices 601 n + layer 602 n - layer 603 p layer 604 n + layer 610 Guard Station 620 source electrodes 605 Semiconductor substrate

Claims

1. A semiconductor laser light source, which is a continuous-oscillation blue semiconductor laser diode that generates laser light with a wavelength of 250 nm or more and a wavelength of 500 nm or less, A rotating stage that rotates multiple semiconductor substrates, A chamber housing the semiconductor substrate and the rotating stage, An optical system unit that guides the laser light to the semiconductor substrate on the rotating stage, A window portion provided on the upper surface of the chamber, through which the laser light is transmitted, A moving mechanism for moving the optical system unit so as to change the irradiation position of the laser beam in a direction different from the rotation direction of the rotating stage when viewed from above, The system includes a beam shaping unit that shapes the laser beam so that it has a top-flat distribution on the semiconductor substrate. The laser beam on the semiconductor substrate is shaped such that it forms a spot shape with the rotation direction of the rotating stage being the short-side direction and the radial direction perpendicular to the rotation direction being the long-side direction. The moving mechanism moves the optical system unit along a radial direction perpendicular to the rotation direction of the rotating stage. The window portion is formed in a rectangular shape with the radial direction as the longitudinal direction, Multiple semiconductor substrates are arranged symmetrically with respect to the rotation axis of the rotating stage. A laser irradiation device is provided with a measuring instrument having a plurality of pixels arranged radially outside the chamber for measuring the profile of the laser light.

2. The laser irradiation device according to claim 1, wherein the movement speed of the optical system unit increases as it gets closer to the rotation axis of the rotating stage.

3. The laser irradiation apparatus according to claim 1 or 2, further comprising an optical fiber for guiding laser light from the semiconductor laser light source to the optical system unit.

4. (A1) A step of generating laser light with a wavelength of 250 nm or more and a wavelength of 500 nm or less using a semiconductor laser light source which is a continuous-oscillating blue semiconductor laser diode, (A2) A step of guiding the laser light to a semiconductor substrate on a rotating stage using an optical system unit, (A3) The moving mechanism moves the optical system unit so as to change the irradiation position of the laser beam in a direction different from the rotation direction of the rotating stage when viewed from above, Multiple semiconductor substrates and the rotating stage are housed in a chamber. The upper surface of the chamber is provided with a window that transmits the laser light, The laser beam is shaped on the semiconductor substrate so that it has a top-flat distribution. The laser beam on the semiconductor substrate is shaped such that it forms a spot shape with the rotation direction of the rotating stage being the short-side direction and the radial direction perpendicular to the rotation direction being the long-side direction. The moving mechanism moves the optical system unit along a radial direction perpendicular to the rotation direction of the rotating stage. The window portion is formed in a rectangular shape with the radial direction as the longitudinal direction, On the rotating stage, a plurality of semiconductor substrates are arranged symmetrically with respect to the rotation axis of the rotating stage. A laser irradiation method comprising a measuring instrument having a plurality of pixels arranged radially outside the chamber for measuring the profile of the laser light.

5. The laser irradiation method according to claim 4, wherein in step (A3), the movement speed of the optical system unit increases as it approaches the rotation axis of the rotating stage.

6. The laser irradiation method according to claim 4 or 5, wherein the laser light from the semiconductor laser light source is guided to the optical system unit via an optical fiber.

7. (S1) A step of generating laser light with a wavelength of 250 nm or more and a wavelength of 500 nm or less using a semiconductor laser light source which is a continuous-oscillating blue semiconductor laser diode, (S2) A step of guiding the laser light to a semiconductor substrate on a rotating stage using an optical system unit, (S3) The moving mechanism moves the optical system unit so that, in a top view, the irradiation position of the laser beam is changed to a direction different from the rotation direction of the rotating stage, Multiple semiconductor substrates and the rotating stage are housed in a chamber. The upper surface of the chamber is provided with a window that transmits the laser light, The laser beam is shaped on the semiconductor substrate so that it has a top-flat distribution. The laser beam on the semiconductor substrate is shaped such that it forms a spot shape with the rotation direction of the rotating stage being the short-side direction and the radial direction perpendicular to the rotation direction being the long-side direction. The moving mechanism moves the optical system unit along a radial direction perpendicular to the rotation direction of the rotating stage. The window portion is formed in a rectangular shape with the radial direction as the longitudinal direction, On the rotating stage, a plurality of semiconductor substrates are arranged symmetrically with respect to the rotation axis of the rotating stage. A method for manufacturing a semiconductor device, comprising a measuring instrument having a plurality of pixels arranged radially outside the chamber for measuring the profile of the laser light.

8. The method for manufacturing a semiconductor device according to claim 7, wherein in step (S3), the movement speed of the optical system unit increases as it approaches the rotation axis of the rotating stage.

9. The method for manufacturing a semiconductor device according to claim 7 or 8, wherein the laser light from the semiconductor laser light source is guided to the optical system unit via an optical fiber.

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