Laser irradiation apparatus, laser irradiation method, and semiconductor device manufacturing method

Abstract

A laser irradiation device according to an embodiment of the present invention is provided with: a laser light source (35) that generates a UV pulse laser; a rotary table (11) that rotates the semiconductor substrate; an optical system unit (30) that shapes the laser light such that the laser light is distributed flat on the semiconductor substrate (16a) and guides the laser light toward the semiconductor substrate (16a) on the rotary table; and a movement mechanism that moves the optical system unit (30) so that the irradiation position of the laser light (15) is changed in a direction different from the rotation direction of the rotary table in plan view.

Description

Technical Field

[0001] The present invention relates to a laser irradiation device, a laser irradiation method, and a method for manufacturing a semiconductor device. Background Art

[0002] Patent Document 1 discloses a laser annealing apparatus using an excimer laser. In Patent Document 1, a conveying unit conveys a substrate while a floating unit floats the substrate, and a linear laser is irradiated onto the conveyed substrate.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-64048 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In such an apparatus, it is desirable to irradiate the laser more uniformly. In addition, by performing the laser irradiation process in a short time, productivity can be improved.

[0008] Other objects and new features will become apparent from the description of this specification and the accompanying drawings.

[0009] Means for solving problems

[0010] According to one embodiment, a laser irradiation device irradiates a metal film formed on a silicon carbide semiconductor film with a laser, and comprises: a laser light source that generates a UV pulse laser; a rotating table that rotates a semiconductor substrate having the metal film; an optical system unit that guides the laser toward the semiconductor substrate on the rotating table; and a moving mechanism that moves the optical system unit so that the irradiation position of the laser is changed in a direction different from the rotation direction of the rotating table in a top view.

[0011] According to one embodiment, a laser irradiation method irradiates a metal film formed on a silicon carbide semiconductor film with laser light in order to form an alloy film, and comprises: (A1) a step of generating a UV pulse laser using a UV pulse laser light source; (A2) a step of guiding the laser toward a semiconductor substrate on a rotating worktable using an optical system unit; and (A3) a step of moving the optical system unit so that the irradiation position of the laser is changed in a direction different from the rotation direction of the rotating worktable in a top view.

[0012] According to one embodiment, a method for manufacturing a semiconductor device that forms an alloy film on a semiconductor substrate by irradiating a metal film formed on a silicon carbide semiconductor film with laser light comprises: (S1) a step of generating a UV pulse laser using a laser light source; (S2) a step of guiding the laser toward a semiconductor substrate on a rotating worktable using an optical system unit; and (S3) a step of moving the optical system unit so that the irradiation position of the laser is changed in a direction different from the rotation direction of the rotating worktable in a top view.

[0013] Effects of the Invention

[0014] According to the above-described one embodiment, a laser irradiation apparatus, a laser irradiation method, and a method for manufacturing a semiconductor device with high productivity can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a side view schematically showing the laser irradiation device according to the embodiment.

[0016] Figure 2 It is a top view schematically showing the laser irradiation device according to the embodiment.

[0017] Figure 3 It is a schematic diagram showing the spatial distribution of light beams and the overlapping parts of lasers.

[0018] Figure 4 is a diagram showing a beam profile of a flat-top distribution.

[0019] Figure 5 It is a schematic diagram showing a configuration example of an optical system.

[0020] Figure 6 This is a diagram for explaining control for synchronizing the laser irradiation timing with the substrate position.

[0021] Figure 7 The diagram shows the manufacturing process of a semiconductor device.

[0022] Figure 8 The diagram shows the manufacturing process of a semiconductor device. DETAILED DESCRIPTION

[0023] The laser irradiation device involved in this embodiment performs annealing by irradiating a laser to a processed object (also called a workpiece). The laser irradiation device heats the substrate using a laser to alloy a metal film provided on the substrate with SiC (silicon carbide) to form an alloy film. For example, the metal film is a Ni film or a Ti film. The processed object becomes a semiconductor substrate for forming a semiconductor device. The semiconductor substrate is a silicon wafer or a compound semiconductor wafer.

[0024] For example, power semiconductor devices such as vertical MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) and IGBT (Insulated Gate Bipolar Transistor) are formed on a semiconductor substrate. That is, the processed body is a semiconductor wafer that forms a chip of a power semiconductor device. The semiconductor substrate has a SiC film. Alternatively, the semiconductor substrate can be a SiC substrate. In addition, a metal film such as a Ni film and a Ti film is stacked on the SiC. The metal film is formed to be in contact with the SiC. In addition, the metal film is heated by irradiating the metal film with a laser. Thus, an alloy film that becomes a back electrode or the like is formed. In this embodiment, in order to form an alloy film, a laser is irradiated on the metal film formed on the SiC.

[0025] The laser irradiation device uses a solid laser light source as a laser light source. The laser light source, for example, generates a UV (UltraViolet) laser with a wavelength of 355nm. The laser irradiation device performs an annealing process by irradiating a pulsed laser to the object to be processed. For example, a nonlinear optical crystal is used to generate the third harmonic of a YAG laser with a wavelength of 1064nm. In addition, the laser is not limited to a UV laser with a wavelength of 355nm, and for example, the fourth harmonic with a wavelength of 266nm may also be used. In addition, it is preferred to set the pulse width to 10 to 100nsec, but it is not limited to this range.

[0026] use Figure 1-2 , the structure of the laser irradiation device involved in this embodiment is described. Figure 1 It is a side view schematically showing the structure of the laser irradiation device 1 . Figure 2 It is a plan view schematically showing the structure of the laser irradiation device 1 .

[0027] In addition, in the following figures, in order to simplify the description, an XYZ three-dimensional orthogonal coordinate system is appropriately shown. The Z direction is a vertical up-down direction, and is a direction orthogonal 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 15 changes along the X direction. The Y direction is a direction orthogonal to the Z direction and the X direction.

[0028] like Figure 1-2 As shown, the laser irradiation device 1 includes a chamber 10, an optical system unit 30, a laser light source 35, an optical system stage 40, a linear motion mechanism 41, a guide mechanism 43, a stand 60, a rotary motor 61, and a measuring device 70. Figure 1 , the optical system unit 30 is shown to be moved to the upper part of the chamber 10. Figure 2 , a state in which the optical system unit 30 has been retracted from above the chamber 10 is shown.

[0029] The gantry 60 supports the chamber 10 and the optical system stage 40, etc. The chamber 10 is fixed on the gantry 60. The chamber 10 accommodates the object to be processed 16 and the stage 11, etc. The stage 11 is connected to the rotary motor 61. The rotary motor 61 is fixed to the gantry 60. The rotary motor 61 rotates the stage 11 around the rotation axis AX. The rotation axis AX is parallel to the Z direction.

[0030] A suction plate 12 for sucking the object 16 to be processed is fixed on the workbench 11. The suction plate 12 has, for example, a vacuum suction cup or an electrostatic suction cup, and sucks and holds the object 16 to be processed. The object 16 to be processed is transferred into the chamber 10 and placed on the suction plate 12. While the suction plate 12 sucks and holds the object 16 to be processed, the rotary motor 61 rotates the workbench 11. As a result, the irradiation position of the laser 15 on the object 16 to be processed changes.

[0031] like Figure 2 As shown, four adsorption plates 12 are installed on the workbench 11. Therefore, four pieces of processed objects 16 are placed on the workbench 11. By arranging a plurality of processed objects 16 on the workbench 11, the throughput is improved. The plurality of processed objects 16 are arranged to be rotationally symmetrical about the rotation axis AX. Specifically, the centers of the four processed objects 16 are arranged on a circle centered on the rotation axis AX. The plurality of processed objects 16 can be irradiated with laser light approximately evenly.

[0032] In addition, Figure 2 In the rotation direction (circumferential direction) of the workbench 11, four pieces of the workpiece 16 are arranged at equal intervals of 90 degrees. Of course, the number of the workpiece 16 placed on the workbench 11 is not limited to 4. That is, the workbench 11 can hold one or more pieces of the workpiece 16.

[0033] The object to be processed 16 is actually a circular semiconductor wafer. In addition, an orientation plane, a groove, etc. may be formed on the semiconductor wafer. The object to be processed 16 has a substrate 16a and a metal film 16b formed on the substrate 16a. The substrate 16a is a substrate of a silicon wafer, a compound semiconductor wafer (SiC, GaN), etc. Of course, the material of the substrate 16a is not particularly limited.

[0034] The metal film 16b is a conductive film formed of nickel or titanium. By irradiating the metal film 16b with the laser 15 and performing an annealing process, an alloy film can be formed. The laser irradiation device 1 melts SiC and the metal film to form an alloy. Figure 1Only the metal film 16b is shown in the figure, but other films or layers may be formed. For example, a thin film of copper or aluminum may be formed as wiring, etc. Furthermore, an insulating layer such as a silicon oxide film may be formed on the substrate 16a.

[0035] A window 14 is provided on the upper surface of the chamber 10. The window 14 is formed of a transparent material such as glass or resin. The laser 15 is transmitted through the window 14. In a plan view, the window 14 is formed in a rectangular shape with the X direction as the long side direction. That is, the window 14 is formed along the moving direction of the optical system workbench 40 described below. In addition, the window 14 is arranged along a radial direction orthogonal to the rotation direction of the workbench 11.

[0036] The optical system table 40 supports the optical system unit 30. Figure 1 As shown, the optical system stage 40 can hold the optical system unit 30 above the stage 11. Specifically, the optical system stage 40 is mounted on the stage 60 via a guide mechanism 43. The guide mechanism 43 includes a linear guide 43a and a slider 43b. The linear guide 43a includes a guide rail, a guide groove, etc. extending in the X direction. The slider 43b slides along the linear guide 43a in the X direction. The linear guide 43a is fixed to the stage 60. The slider 43b is fixed to the optical system stage 40. The linear guide 43a holds the slider 43b slidably.

[0037] Furthermore, a linear motion mechanism 41 is provided between the optical system stage 40 and the stage 60. The linear motion mechanism 41 has an actuator such as a linear motor. The linear motion mechanism 41 is extended and retracted, thereby the optical system stage 40 moves in the X direction. That is, the optical system stage 40 is guided by the guide mechanism 43 and moves in the X direction. As the optical system stage 40 moves, the position of the optical system unit 30 in the X direction changes.

[0038] In this way, the linear motion mechanism 41 drives the optical system stage 40, thereby the optical system unit 30 moves in the X direction. Therefore, the linear motion mechanism 41 and the guide mechanism 43 become a moving mechanism for moving the optical system unit 30. In addition, the moving mechanism for moving the optical system unit 30 is not limited to the above-mentioned structure, and a known method can be used. For example, the moving mechanism can include a ball screw, a cylinder, etc.

[0039] In addition, a support 38 for holding the laser light source 35 is provided outside the stand 60. The laser light source 35 is fixed to the support 38. The laser light source 35 generates laser light 15 for annealing the workpiece 16. The laser light source 35 is a solid laser light source, for example, a UV pulse laser with a central wavelength of 355 nm. The pulse width of the UV pulse laser is preferably set to 10 to 100 nsec.

[0040] The laser light source 35 emits laser light toward the optical system unit 30 . The optical axis of the laser light from the laser light source 35 is parallel to the X axis. The laser light travels in the −X direction and enters the optical system unit 30 .

[0041] like Figure 1 As shown in FIG. 1 , the optical system unit 30 includes a housing 310, a lens 301, a lens 302, a reflector 303, and a beam shaping unit 307. The lens 301, the lens 302, the reflector 303, and the beam shaping unit 307 are fixed to the housing 310. Of course, optical elements other than the lens 301, the lens 302, the reflector 303, and the beam shaping unit 307 may be provided in the optical system unit 30.

[0042] The laser light from the laser light source 35 enters the reflector 303 of the optical system unit 30. The reflector 303 reflects the laser light in the -X direction. The laser light reflected by the reflector 303 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 and a beam homogenizer.

[0043] The laser beam 15 may be a Gaussian beam or a flat-top beam. For a Gaussian beam, the spatial intensity distribution of the laser beam 15 at the object 16 to be processed is a Gaussian distribution. For a flat-top beam, the spatial intensity distribution of the laser beam 15 at the object 16 to be processed is a flat-top distribution. The beam shaping unit 307 may have a beam homogenizer for making the spatial intensity distribution uniform. For example, the beam shaping unit 307 may have a beam homogenizer for making the spatial intensity distribution flat-top. The beam homogenizer has an optical element such as a fly-eye lens.

[0044] For example, the beam shaping unit 307 forms a flat top beam with a flat distribution along the X direction at the processed object 16. In addition, the spot shape of the light beam at the processed object 16 can be a line beam with a long side direction and a short side direction. In this case, the spot shape at the processed object 16 can take the X direction as the long side direction and the Y direction as the short side direction. For example, the size of the light spot in the long side direction is about 1 mm, and the size of the light spot in the X direction can be set to 0.2 mm. In addition, the beam shaping unit 307 can shape the light beam into a flat top beam with uniform intensity distribution in the X direction. Of course, the beam shaping unit 307 can also shape a flat top beam with uniform intensity distribution in the Y direction. In addition, the spot shape of the light beam at the processed object 16 and its spatial distribution are described below.

[0045] The laser beam shaped by the beam shaping unit 307 is incident on the lens 301. The laser beam 15 focused by the lens 301 is incident on the lens 302. The optical axes of the lenses 301 and 302 are parallel to the Z direction. The laser beam 15 from the lens 302 is irradiated onto the object 16 to be processed. The lens 302 converges the laser beam 15 onto the object 16 to be processed. Therefore, the laser beam 15 from the optical system unit 30 becomes a convergent beam and is irradiated onto the object 16 to be processed. The lens 302 may also be a cylindrical lens. In this way, the laser beam 15 can be made into a linear beam at the object 16 to be processed.

[0046] The lens 302 focuses the laser beam 15 onto the object 16 to be processed. Figure 1 In the embodiment, the optical system unit 30 is arranged just above the window 14. The laser light 15 from the optical system unit 30 is incident on 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 light 15 from above. The metal film 16b of the object to be processed 16 is annealed.

[0047] The workbench 11 is a rotating workbench having a rotating motor 61. The workbench 11 rotates around a rotation axis AX parallel to the Z axis. During the rotation of the workbench 11, the optical system unit 30 moves in the X direction. In a top view, the moving direction of the optical system unit 30 and the rotation direction of the workbench 11 are intersecting directions. Specifically, the moving direction of the optical system unit 30 is parallel to the radial direction of the workbench 11. The radial direction is a direction orthogonal to the rotation direction. In this way, the laser can be irradiated to any position of the object to be processed 16.

[0048] By rotating the object 16 using the stage 11, the entire object 16 can be irradiated with the laser beam 15 in a short time. Therefore, the object 16 can be irradiated with the laser beam at a high throughput, so that the productivity can be improved.

[0049] For example, the position of the laser 15 changes in the circumferential direction by the rotation of the table 11. The position of the laser 15 changes in the radial direction by the movement of the optical system unit 30. Figure 2 In FIG. 1 , the trajectory of irradiating the stage 11 with the laser light 15 is shown as an irradiation trajectory T1 .

[0050] exist Figure 2 , both ends of the irradiation position of the laser 15 in the X direction are shown as lasers 15a and 15b. The end of the irradiation position in the -X direction corresponds to the laser 15a, and the end of the irradiation position in the +X direction corresponds to the laser 15b. The lasers 15a and 15b are incident on the object 16 to be processed through the window 14.

[0051] The optical system unit 30 moves the irradiation position of the laser 15 from the position indicated by the laser 15a to the position indicated by the laser 15b. The irradiation position of the laser 15a becomes the end of the object 16 farthest from the rotation axis AX side, and the irradiation position of the laser 15b becomes the other end of the object 16 closest to the rotation axis AX side. That is, the optical system unit 30 moves so that the irradiation position of the laser 15 changes from one end to the other end of the object 16 in the radial direction. The moving range of the optical system unit 30 corresponds to the diameter of the object 16. In this way, the entire object 16 can be irradiated with the laser 15.

[0052] For example, while the workbench 11 is rotated at a fixed rotation speed, the optical system unit 30 moves in the X direction. The optical system unit 30 moves from the outer peripheral end side of the workbench 11 toward the rotation axis AX. In the Y direction, the irradiation position of the laser 15 coincides with the position of the rotation axis AX. During the rotation of the workbench 11, the optical system unit 30 moves continuously or stepwise in the -X direction. As a result, the trajectory of the laser 15 at the workbench 11 becomes a spiral shape. Therefore, the laser can be uniformly irradiated to a plurality of processed objects 16. In addition, during the rotation of the processed object 16, the optical system unit 30 can also move back and forth between the +X direction and the -X direction.

[0053] Furthermore, a measuring device 70 is provided on the +X side of the chamber 10. The measuring device 70 has a light detector such as a photodiode, and measures the beam profile of the laser 15. That is, the measuring device 70 measures the spatial distribution of the laser 15 on the cross section orthogonal to the optical axis, that is, on the XY plane. For example, the measuring device 70 has a plurality of pixels (light detection elements) arranged in a row or array. It is preferred that the light receiving surface of the measuring device 70 and the object to be processed 16 are at the same height. Thus, the measuring device 70 can measure a beam profile that is equivalent to the beam profile on the object to be processed 16.

[0054] The measuring device 70 has a plurality of pixels arranged in the X direction. Therefore, the uniformity of the laser spot in the long side direction can be evaluated based on the measurement result of the measuring device 70. That is, the uniformity of the flat top distribution can be evaluated, and a stable process can be achieved. The measuring device 70 is arranged outside the workbench 11. Therefore, the measuring device 70 can measure the beam profile of the laser 15 before or after the laser irradiation process.

[0055] In this embodiment, UV solid laser is used as the laser light source 35. A high irradiation intensity can be obtained. Therefore, a laser irradiation device 1 with high productivity can be realized. That is, an alloy film can be formed on the entire surface of the substrate 16a in a short time.

[0056] The beam shaping unit 307 makes the laser beam into a flat top beam, thereby reducing the number of laser overlaps. This can increase throughput and thus productivity. Figure 3 Provide explanation. Figure 3 This is a schematic diagram for explaining the overlapping portion of laser light under a flat-top beam and a Gaussian beam.

[0057] exist Figure 3 In FIG. 1 , the spot of the laser light in the first circle of the workbench 11 is shown as spot 15-1, and the spot of the laser light in the second circle of the workbench 11 is shown as spot 15-2. Spot 15-2 is moved toward the −X side compared to spot 15-1. Spots 15-1 and 15-2 at the object to be processed 16 are linear with the X direction as the long side direction and the Y direction as the short side direction.

[0058] In the flat-top beam, the region X1 where the laser intensity I is uniform is long. Therefore, the ratio of the overlapping portion between the first circle and the second circle can be reduced. The length F1 of the overlapping portion can be shortened. In other words, the moving distance during one rotation of the worktable 11 can be lengthened, so the moving speed of the optical system unit 30 can be increased.

[0059] On the other hand, in a Gaussian beam, the region X2 where the laser intensity I is uniform is short. Therefore, the ratio of the overlapping portion between the first circle and the second circle becomes larger. It is necessary to make the length F2 of the overlapping portion longer. In other words, the moving distance during one rotation of the workbench 11 becomes shorter, so it is difficult to increase the moving speed of the optical system unit 30.

[0060] Therefore, by using a flat-top beam, the number of overlapping beam spots can be reduced even when the laser beam is irradiated onto substantially the entire surface of the object to be processed 16. This increases the rotation speed and the moving speed, thereby increasing throughput and productivity.

[0061] In addition, on the workbench 11, the closer the radial position is to the rotation axis AX, the shorter the circumference. The distance from the rotation axis AX to the irradiation position is set as the rotation radius. If the rotation speed is set to be fixed, the irradiation time per unit length in the circumferential direction changes correspondingly to the rotation radius. Therefore, it is preferred to change the moving speed of the optical system unit 30 corresponding to the X-direction position of the optical system unit 30. That is, the smaller the rotation radius, the faster the moving speed in the X-direction. For example, the moving speed of the optical system unit 30 is the fastest at the irradiation position of the laser 15a, and the moving speed of the optical system unit 30 is the slowest at the irradiation position of the laser 15b. In this way, the irradiation amount of the laser per unit area can be made uniform.

[0062] The case where the optical system unit 30 continuously moves in the X direction while the worktable 11 rotates at a fixed rotation speed (rotation speed) is described. In this case, the closer to the rotation axis AX, the faster the moving speed of the optical system unit 30. Specifically, the distance (rotation radius) from the rotation axis AX to the irradiation position and the moving speed are set to have a linear relationship. In this way, the entire object 16 can be irradiated with laser light uniformly.

[0063] Alternatively, the moving speed of the optical system unit 30 may be fixed, and the rotation speed of the stage 11 may be changed. That is, the smaller the rotation radius, the faster the rotation speed.

[0064] An example of the rotation speed and the moving speed is described below. Here, it is assumed that the object to be processed 16 is a semiconductor wafer with a diameter of 300 mm, and the rotation radius varies within the range of 450 mm to 750 mm. Figure 2 The rotation radius at the irradiation position of the laser 15a is 450 mm, and the rotation radius at the position of the laser 15b is 750 mm. In addition, the moving distance of the worktable 11 in the X direction during one rotation is set to 0.2 mm.

[0065] When the moving 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 the rotation speed can be set to 7.07 rps for a rotation radius of 450 mm.

[0066] When the moving 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 for a rotation radius of 750 mm, and the rotation speed can be set to 3.54 rps for a rotation radius of 450 mm.

[0067] When the moving speed of the optical system unit 30 in the X direction is 5 m / sec, the rotation speed can be set to 1.06 rps for a rotation radius of 750 mm, and the rotation speed can be set to 1.77 rps for a rotation radius of 450 mm. Of course, the rotation speed and the moving speed are not limited to the above examples.

[0068] In the present embodiment, the laser light source 35 is fixed to a bracket 38 different from the stand 60. Therefore, the laser light source 35 can be easily replaced and maintained. It is also possible to irradiate the pulse laser to the object 16 at a timing when the object 16 is present directly below the window 14. Thus, it is possible to prevent the laser from being irradiated to the workbench 11 at a timing when the object 16 is not present directly below the window 14.

[0069] In addition, the measuring device 70 measures the profile of the laser light. Thus, the object to be processed 16 can be irradiated with laser light having a uniform spatial distribution. The object to be processed 16 can be irradiated with laser light stably, so that productivity can be improved.

[0070] The laser irradiation method using the laser irradiation device 1 irradiates a metal film formed on a SiC film with laser light in order to form an alloy film. The laser irradiation method includes, for example, the following steps 1 to 3.

[0071] (Step 1) A step of generating UV pulse laser using a laser light source.

[0072] (Step 2) A step of guiding the laser light toward the semiconductor substrate on the rotating table using an optical system unit.

[0073] (Step 3) A step of moving the optical system unit so that the irradiation position of the laser light is changed in a direction different from the rotation direction of the rotary table in a plan view.

[0074] The laser irradiation method according to the present embodiment can be applied to a method for manufacturing a semiconductor device, thereby making it possible to manufacture a semiconductor device with high productivity.

[0075] use Figure 4 , the flat-top distribution of the laser is explained. Figure 4 is a graph showing the beam profile of a flat-top distribution. Figure 4 In the figure, the horizontal axis represents position [mm] and the vertical axis represents beam intensity [%]. The horizontal axis is set to 0, and the vertical axis is normalized by setting the average intensity in the range of ±a from the beam center to 100%.

[0076] As mentioned above, the average intensity in the range of -a to +a is 100%. Figure 4 In the example, a is 0.05 mm. The width of 88% intensity is defined as the beam width of the flat-top distribution. Here, the beam width is 0.22 mm (-0.11 mm to +0.11 mm). This beam width can be compared to the full width at half maximum (at Figure 4 The beam with more than 50% is defined as a flat-top beam. Figure 4 , the beam width is 88% of the full width at half maximum (=0.22 / 0.25). In addition, the value of a is not less than 25% of the full width at half maximum.

[0077] Next, use Figure 5 An example of an optical system will be described. Figure 5The optical system 300 schematically shows an example of the structure of the optical system. The optical system 300 includes an AO modulator 321, a beam splitter 322, a reflector 323, a reflector 324, a beam splitter 325, and a beam dump 329. At least a part of each component of the optical system 300 may be mounted on Figure 1 and Figure 2 The optical system unit 30 may be mounted on the optical system unit 30, or may not be mounted on the optical system unit 30. That is, each optical element of the optical system 300 may be provided in the optical system unit 30, or may be provided in the preceding stage of the optical system unit 30.

[0078] The laser light 15 from the laser light source 35 is incident on the AO modulator 321. The AO (Acousto Optics) modulator 321 functions as a switch for switching on and off the laser irradiation to the object to be processed 16. The control unit 328 has a power supply for generating a control voltage to be applied to the AO modulator 321. The control unit 328 supplies the control voltage to the AO modulator 321. When the voltage of the AO modulator 321 changes, the laser light 15 is deflected.

[0079] For example, when the control unit 328 applies a control voltage to the AO modulator 321, the laser light 15 is deflected in the direction of the beam dump 329. The beam dump 329 absorbs the laser light from the AO modulator 321. That is, the laser light deflected by the AO modulator 321 passes through the outside of the beam splitter 322. In this case, the laser light is not irradiated to the object 16 to be processed.

[0080] If the control unit 328 does not apply a control voltage to the AO modulator 321, the laser 15 is incident on the beam splitter 322. In this case, the laser is irradiated onto the object to be processed 16. The control unit 328 controls the voltage to switch the on and off of the laser irradiation based on the AO modulator 321. When the control voltage is ON, the laser irradiation is turned on, and when the control voltage is OFF, the laser irradiation is turned off. Of course, it can also be the other way around. In addition, the control unit 328 can also supply different voltages to the AO modulator 321 depending on whether the laser irradiation is turned on and off. The voltage for switching the on and off of the laser irradiation is not particularly limited. In addition, the switch is not limited to the AO modulator 321, and an electronic shutter such as an EO (Electro Optics) modulator or a liquid crystal element can also be used.

[0081] The control unit 328 and the AO modulator 321 are provided to synchronize the opening and closing of the laser irradiation with the rotation position of the worktable. In this way, the laser can be irradiated only to the object to be processed 16. In other words, it is possible to prevent the laser from being irradiated to a position on the worktable 11 where the object to be processed 16 is not placed. This control will be described later.

[0082] The beam splitter 322 , the mirror 323 , the mirror 324 , and the beam splitter 325 function as a pulse stretcher for extending the pulse width. Alternatively, the pulse stretcher may be disposed in the preceding stage of the AO modulator 321 .

[0083] The beam splitter 322 functions as a branching unit that splits the laser beam 15 into two beams SL1 and SL2. The beam splitter 322 is, for example, a polarization beam splitter or a half mirror. The component of the laser beam 15 that passes through the beam splitter 322 becomes the beam SL1, and the component reflected by the beam splitter 322 becomes the beam SL2.

[0084] One light beam SL1 split by the laser beam directly enters the beam splitter 325. The other light beam SL2 split by the laser beam is reflected by the reflection mirrors 323 and 324 and enters the beam splitter 325.

[0085] Therefore, the optical path length of the light beam SL2 is longer than that of the light beam SL1. The pulse of the light beam SL2 arrives at the beam splitter 325 later than the pulse of the light beam SL1. In this way, a delay corresponding to the optical path length difference is given between the light beam SL2 and the light beam SL1. That is, the light beam SL2 is delayed compared with the light beam SL1.

[0086] The beam splitter 325 functions as a combining unit for combining the two light beams SL1 and SL2. The beam splitter 325 is, for example, a polarization beam splitter or a half mirror. The light beam combined by the beam splitter 325 is referred to as a combined light beam CL. The beam splitter 325 combines the light beams SL1 and SL2 so that they are coaxial.

[0087] like Figure 5 As shown, the pulse width before entering the beam splitter 322 is set to t. The pulse widths of the light beams SL1 and SL2 generated by the beam splitter 322 are t, respectively. The light beam SL2 is longer than the light beam SL1 in terms of the optical path length, and therefore enters the beam splitter 325 later than the light beam SL1. Therefore, the pulse width of the synthesized light beam CL is longer by the amount of the delay time. The optical path length is set so that the pulse of the light beam SL1 partially overlaps the pulse of the light beam SL2. Here, the optical path length is adjusted so that the pulse width of the synthesized light beam CL becomes 2t. That is, the pulse width is adjusted by changing the positions of the reflectors 323 and 324.

[0088] Then, the synthesized light beam CL is irradiated onto the object to be processed 16. In addition, the optical system 300 can also be provided at the front stage of the optical system unit 30. In this case, the synthesized light beam CL with a prolonged pulse width is incident on the object to be processed 16. Figure 1 The reflecting mirror 303. In addition, at least one of the pulse stretcher and the AO modulator can be omitted.

[0089] Next, use Figure 5 and Figure 6The following describes a configuration of the control unit 328 for synchronizing the on / off of laser irradiation with the rotational position of the stage. Figure 6 1 is a diagram schematically showing the structure of the workbench 11. Specifically, a top view of the workbench 11 is shown. Figure 6 The timing of the pulses is shown in .

[0090] In addition, Figure 6 In FIG. 1 , six objects to be processed 16 are arranged on the table 11 . The six objects to be processed 16 are arranged at equal intervals in the circumferential direction. The centers of the six objects to be processed 16 are arranged on a radius R with the rotation center of the table 11 as the center.

[0091] A sensor 11a for detecting the rotational position of the table 11 is provided on the outer peripheral side of the table 11. The sensor 11a is, for example, an encoder, and transmits a detection signal indicating the rotational position (rotational angle) to the Figure 5 The control unit 328 outputs.

[0092] like Figure 5 As shown, the AO modulator 321 can switch the laser irradiation on and off. The control unit 328 controls the AO modulator 321 based on the detection signal from the sensor 11a. That is, at the rotational position where the optical axis of the optical system unit 30 coincides with the object to be processed 16, the control unit 328 turns off the voltage of the AO modulator 321. As a result, the laser 15 is incident on the beam splitter 322. Therefore, the laser is irradiated to the object to be processed 16. That is, the laser irradiation is turned on at the following position, which is the rotational position where the object to be processed 16 exists on the optical axis.

[0093] At a rotational position where the optical axis of the optical system unit 30 does not coincide with the object to be processed 16, the control unit 328 turns on the voltage of the AO modulator 321. As a result, the laser light 15 is deflected in the direction of the beam dump 329. That is, the laser irradiation is turned off at the following position, which is a rotational position where the object to be processed 16 does not exist on the optical axis. Therefore, it is possible to prevent the laser light 15 from being absorbed by the worktable 11.

[0094] exist Figure 6 The pulse width is 30 nsec. In addition, the repetition frequency of the pulse is 10 kHz. And, at the timing between the two pulses, the AO modulator 321 is switched on and off. At the rotational position where the optical axis of the optical system unit 30 does not coincide with the object to be processed 16, the laser irradiation is turned off. At the rotational position where the optical axis of the optical system unit 30 coincides with the object to be processed 16, the laser irradiation is turned on. The AO modulator 321 switches the laser irradiation on and off corresponding to the rotational position detected by the sensor 11a.

[0095] (Semiconductor devices)

[0096] Next, use Figure 7 , Figure 8 A method for manufacturing a semiconductor device using the laser irradiation device according to this embodiment will be described. Figure 7 , Figure 8 6 is a cross-sectional view schematically showing the structure of a semiconductor device 600. The semiconductor device 600 is a power semiconductor device such as a vertical MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or an IGBT (Insulated Gate Bipolar Transistor). Figure 1 , Figure 2 Corresponding to the processed object 16.

[0097] like Figure 7 As shown, the semiconductor device 600 is configured so that the back side of the semiconductor substrate 601 is at the top. A SiC film 602 is formed on the back side of the semiconductor substrate 601. The SiC film 602 is formed by CVD (Chemical Vapor Deposition) or the like. Furthermore, a metal film 603 is formed on the SiC film 602. The metal film 603 is formed of nickel or titanium. The metal film 603 is formed by sputtering or the like, for example. The semiconductor substrate 601 and the metal film 603 correspond to Figure 1 , Figure 2 In addition, other conductive layers, insulating layers, semiconductor layers, etc. may be formed on the semiconductor substrate 601.

[0098] The laser irradiation device 1 irradiates the metal film 603 with the laser beam 15. As a result, the metal film 603 is annealed. Therefore, the metal film 603 and the SiC film 602 are melted to form an alloy film 604 (see Figure 8 ).like Figure 8 As shown, an alloy film 604 is formed at the interface between the metal film 603 and the SiC film 602. The alloy film 604 is a titanium silicide film or a nickel silicide film. For example, the alloy film 604 becomes the back electrode of the semiconductor device 600.

[0099] In addition, the method involved in this embodiment is an irradiation method for forming an alloy film on a semiconductor device, comprising: a step of generating a pulsed laser of ultraviolet light; a step of using an optical system unit to shape the laser so that the laser becomes a flat-top distribution on the semiconductor substrate having the metal film, and guiding the laser to the semiconductor substrate on the rotating table; and a step of moving the optical system unit so that the irradiation position of the laser changes in a direction different from the rotation direction of the rotating table in a top view. By this method, an alloy film can be appropriately formed. This laser irradiation method is suitable for a method for manufacturing a semiconductor device. That is, the laser irradiation method is suitable for an activation process in a method for manufacturing a semiconductor device.

[0100] In addition, the present invention is not limited to the above-mentioned embodiment, and can be appropriately modified within a range not departing from the gist.

[0101] Description of Reference Numerals

[0102] 1 Laser irradiation device

[0103] 10 Chamber

[0104] 11 Workbench

[0105] 12 Adsorption board

[0106] 14 Window

[0107] 15 Laser

[0108] 16 Processed Object

[0109] 16a base plate

[0110] 16b Metal film

[0111] 30 Optical system unit

[0112] 35 Laser light source

[0113] 40 Optical system workbench

[0114] 41 Linear motion mechanism

[0115] 43 Guidance Agency

[0116] 43a Linear guide

[0117] 43b Slider

[0118] 60 racks

[0119] 70 Measuring device

[0120] 301 Lens

[0121] 302 Lens

[0122] 303 Reflector

[0123] 307 Beam Shaping Department

[0124] 310 frame

[0125] 321 AO Modulator

[0126] 322 Beam Splitter

[0127] 323 Reflector

[0128] 324 Reflector

[0129] 325 Beam Splitter

[0130] 328 Control Department

[0131] 329 Beam Dump

[0132] 600 Semiconductor Devices

[0133] 601 Semiconductor Substrate

[0134] 602 SiC film

[0135] 603 metal film.

Claims

1. A laser irradiation device, characterized in that: A laser is irradiated onto a metal film formed on a silicon carbide semiconductor film, wherein the laser irradiation device comprises: A laser light source that generates UV pulsed laser light; a rotating table that rotates the semiconductor substrate having the metal film; an optical system unit that guides the laser light toward the semiconductor substrate on the rotating table; and A moving mechanism moves the optical system unit so that the irradiation position of the laser beam is changed in a direction different from the rotation direction of the rotary table in a plan view.

2. The laser irradiation device according to claim 1, characterized in that: The laser light is shaped so as to have a flat top distribution on the semiconductor substrate.

3. The laser irradiation device according to claim 1 or 2, characterized in that: The laser light is shaped so that the laser light on the semiconductor substrate has a spot shape having a short side direction in the rotation direction of the rotary table and a long side direction in a radial direction perpendicular to the rotation direction.

4. The laser irradiation device according to claim 1 or 2, characterized in that: The moving mechanism moves the optical system unit in a radial direction orthogonal to the rotation direction of the rotary table. The closer to the rotation axis of the rotary table, the faster the moving speed of the optical system unit.

5. The laser irradiation device according to claim 1 or 2, characterized in that: The plurality of semiconductor substrates are arranged symmetrically with respect to the rotation axis of the rotation table.

6. The laser irradiation device according to claim 1 or 2, characterized in that: A measuring device for measuring the profile of the laser light is provided outside the rotary table.

7. The laser irradiation device according to claim 1 or 2, characterized in that: The pulse width of the UV pulse laser is 10 to 100 nsec.

8. The laser irradiation device according to claim 7, characterized in that: have: a branching unit that splits the UV pulse laser into two beams; and a combining unit for combining the two light beams separated by the branching unit, By providing a delay corresponding to the optical path length difference between the two light beams, the pulse width is set to 10 to 100 nsec.

9. The laser irradiation device according to claim 1 or 2, characterized in that: have: a switch that switches on and off the laser irradiation to the semiconductor substrate; a sensor that detects a rotational position of the rotary table; and A control unit controls the switch in accordance with the detection result of the sensor so that the UV pulse laser is irradiated to the semiconductor substrate.

10. A laser irradiation method, characterized in that: A laser is irradiated onto a metal film formed on a silicon carbide semiconductor film, the laser irradiation method comprising: (A1) a step of generating UV pulse laser using a UV pulse laser light source; (A2) a step of guiding the laser light toward the semiconductor substrate on the rotating table using an optical system unit; and (A3) A step of moving the optical system unit so that the irradiation position of the laser light is changed in a direction different from the rotation direction of the rotary table in a plan view.

11. The laser irradiation method according to claim 10, characterized in that: The optical system unit is used to shape the laser light so that the laser light has a flat top distribution on the semiconductor substrate having the metal film.

12. The laser irradiation method according to claim 10 or 11, characterized in that: The laser light is shaped so that the laser light on the semiconductor substrate has a spot shape having a short side direction in the rotation direction of the rotary table and a long side direction in a radial direction perpendicular to the rotation direction.

13. The laser irradiation method according to claim 10 or 11, characterized in that: In step (A3), the optical system unit is moved in a radial direction orthogonal to the rotation direction of the rotary table. The closer to the rotation axis of the rotary table, the faster the moving speed of the optical system unit.

14. The laser irradiation method according to claim 10 or 11, characterized in that: The plurality of semiconductor substrates are arranged symmetrically with respect to the rotation axis of the rotation table.

15. The laser irradiation method according to claim 10 or 11, characterized in that: On the outside of the rotary table, a measuring device measures the profile of the laser.

16. The laser irradiation method according to claim 10 or 11, characterized in that: The pulse width of the UV pulse laser is 10 to 100 nsec.

17. The laser irradiation method according to claim 16, characterized in that: The UV pulse laser is split into two beams, Combining the two beams, By providing a delay corresponding to the optical path length difference between the two light beams, the pulse width of the synthesized UV pulse laser light is set to 10 to 100 nsec.

18. The laser irradiation method according to claim 10 or 11, characterized in that: have: a switch that switches on and off the laser irradiation to the semiconductor substrate; a sensor that detects a rotational position of the rotary table; and A control unit controls the switch in accordance with the detection result of the sensor so that the UV pulse laser is irradiated to the semiconductor substrate.

19. A method for manufacturing a semiconductor device, characterized in that: A method for manufacturing a semiconductor device comprising irradiating a metal film formed on a silicon carbide semiconductor film with laser light, wherein: (S1) a step of generating UV pulse laser using a laser light source; (S2) a step of guiding the laser toward the semiconductor substrate on the rotating table using an optical system unit; and (S3) A step of moving the optical system unit so that the irradiation position of the laser light is changed in a direction different from the rotation direction of the rotary table in a plan view.

20. The method for manufacturing a semiconductor device according to claim 19, wherein: The optical system unit is used to shape the laser light so that the laser light has a flat top distribution on the semiconductor substrate having the metal film.

21. The method for manufacturing a semiconductor device according to claim 19 or 20, characterized in that: The laser light is shaped so that the laser light on the semiconductor substrate has a spot shape having a short side direction in the rotation direction of the rotary table and a long side direction in a radial direction perpendicular to the rotation direction.

22. The method for manufacturing a semiconductor device according to claim 19 or 20, characterized in that: In step (S3), the optical system unit is moved in a radial direction orthogonal to the rotation direction of the rotary table. The closer to the rotation axis of the rotary table, the faster the moving speed of the optical system unit.

23. The method for manufacturing a semiconductor device according to claim 19 or 20, characterized in that: The plurality of semiconductor substrates are arranged symmetrically with respect to the rotation axis of the rotation table.

24. The method for manufacturing a semiconductor device according to claim 19 or 20, characterized in that: On the outside of the rotary table, a measuring device measures the profile of the laser.

25. The method for manufacturing a semiconductor device according to claim 19 or 20, characterized in that: The pulse width of the UV pulse laser is 10 to 100 nsec.

26. The method for manufacturing a semiconductor device according to claim 25, wherein: The UV pulse laser is split into two beams, Combining the two beams, By providing a delay corresponding to the optical path length difference between the two light beams, the pulse width of the synthesized UV pulse laser light is set to 10 to 100 nsec.

27. The method for manufacturing a semiconductor device according to claim 19 or 20, characterized in that: have: a switch that switches on and off the laser irradiation to the semiconductor substrate; a sensor that detects a rotational position of the rotary table; and A control unit controls the switch in accordance with the detection result of the sensor so that the UV pulse laser is irradiated to the semiconductor substrate.

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