WO2023203733A1

WO2023203733A1 - Laser irradiation apparatus, laser irradiation method, and method for manufacturing semiconductor device

Info

Publication number: WO2023203733A1
Application number: PCT/JP2022/018491
Authority: WO
Inventors: 博也田中; 芳広山口; 直之小林
Original assignee: Ｊｓｗアクティナシステム株式会社
Priority date: 2022-04-21
Filing date: 2022-04-21
Publication date: 2023-10-26

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

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

The present invention relates to a laser irradiation apparatus, a laser irradiation method, and a semiconductor device manufacturing method.

Patent Document 1 discloses a laser annealing device using an excimer laser. In Patent Document 1, a conveying unit conveys the substrate while the floating unit levitates the substrate. Then, a line-shaped laser beam is irradiated onto the substrate being transported.

JP2018-64048

Since such excimer laser light sources are expensive, it is difficult to reduce the cost of parts of the device. Therefore, it is desirable to use a light source other than an excimer laser light source. Semiconductor lasers are inexpensive, but are continuous wave (CW) lasers. If the CW laser light is pulsed by a modulator, the output will be reduced. Therefore, many light sources are required, making it difficult to reduce costs.

Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

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

According to one embodiment, the laser irradiation method includes the steps of (A1) generating laser light with a wavelength of 250 nm or more and 500 nm or less using a semiconductor laser light source; (A3) 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 rotation stage when viewed from above; We are prepared.

According to one embodiment, a method for manufacturing a semiconductor device includes (S1) using a semiconductor laser light source to generate laser light with a wavelength of 250 nm or more and 500 nm or less, and (S2) using an optical system unit to generate the laser light. (S3) moving the optical system unit so as to change the irradiation position of the laser beam in a direction different from the rotational direction of the rotation stage when viewed from above; , is equipped with.

According to the embodiment, a highly productive laser irradiation apparatus, laser irradiation method, and semiconductor device manufacturing method can be provided.

1 is a side view schematically showing a laser irradiation device according to a first embodiment; FIG. 1 is a top view schematically showing a laser irradiation device according to a first embodiment; FIG. FIG. 3 is a schematic diagram showing a spatial distribution of beams and an overlapping portion of laser light. FIG. 3 is a side view schematically showing a laser irradiation device according to a second embodiment. FIG. 3 is a top view schematically showing a laser irradiation device according to a second embodiment. FIG. 7 is a side view schematically showing a laser irradiation device according to a third embodiment. FIG. 7 is a top view schematically showing a laser irradiation device according to a third embodiment. 1 is a cross-sectional view showing the configuration of a semiconductor device manufactured by a laser irradiation process.

Embodiment 1
The laser irradiation apparatus according to the present embodiment performs annealing treatment by irradiating an object to be processed (also referred to as a workpiece) with a laser beam. A laser irradiation device performs activation processing on a semiconductor layer provided on a substrate by heating the substrate with laser light. The object to be processed is a semiconductor substrate for forming a semiconductor device. The semiconductor substrate is a silicon wafer or a compound semiconductor wafer.

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. In other words, the object to be processed 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 injection layer) into which impurities are implanted. The semiconductor layer can be activated by the laser irradiation device irradiating the semiconductor layer with laser light. Furthermore, 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.

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

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

The configuration of the laser irradiation device according to this embodiment will be explained using FIGS. 1 and 2. FIG. 1 is a side view schematically showing the configuration of a laser irradiation device 1. As shown in FIG. FIG. 2 is a top view schematically showing the configuration of the laser irradiation device 1. As shown in FIG.

Note that in the figures shown below, an XYZ three-dimensional orthogonal coordinate system is appropriately shown for the sake of simplifying the explanation. The Z direction is a vertical direction, and is a direction perpendicular to the main surface of the object 16 to be processed. The X direction is the direction in which the optical system unit 30 moves. By moving the optical system unit 30, the irradiation position of the laser beam 15 changes in the X direction. The Y direction is a direction perpendicular to the Z direction and the X direction.

As shown in FIGS. 1 and 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 pedestal 60, a rotation It includes a motor 61, a measuring device 70, and the like. Note that FIG. 1 shows a state in which the optical system unit 30 has been moved above the chamber 10, and FIG. 2 shows a state in which the optical system unit 30 has been retracted from above the chamber 10.

The pedestal 60 supports the chamber 10, the optical system stage 40, and the like. The chamber 10 is fixed on a pedestal 60. The chamber 10 accommodates the object to be processed 16, the stage 11, and the like. The stage 11 is connected to a rotary motor 61. The rotary motor 61 is fixed to the pedestal 60. Rotary motor 61 rotates stage 11 around rotation axis AX. The rotation axis AX is parallel to the Z direction.

A suction plate 12 that suctions the object to be processed 16 is fixed on the stage 11. The suction plate 12 includes, for example, a vacuum chuck or an electrostatic chuck, and suctions and holds the object 16 to be processed. The object to be processed 16 is transferred into the chamber 10 and placed on the suction plate 12 . The rotary motor 61 rotates the stage 11 with the suction plate 12 suctioning and holding the object 16 to be processed. As a result, the irradiation position of the laser beam 15 on the object to be processed 16 changes.

As shown in FIG. 2, four suction plates 12 are attached to the stage 11. Therefore, four objects 16 to be processed are placed on the stage 11. By arranging a plurality of objects 16 to be processed on the stage 11, throughput is improved. The plurality of objects to be processed 16 are arranged rotationally symmetrically about 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. The plurality of objects 16 to be processed can be irradiated with laser light almost equally.

Note that in FIG. 2, the four objects 16 to be processed 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 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 16 to be processed.

The object to be processed 16 is a substantially circular semiconductor wafer. Note that an orientation flat, a notch, etc. may be formed in the semiconductor wafer. The object to be processed 16 includes 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 at the laser wavelength.

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

A window 14 is provided on the top surface of the chamber 10. The window portion 14 is made of a transparent material such as glass or resin. The laser beam 15 is transmitted through the window portion 14 . The window portion 14 is formed into a rectangular shape whose longitudinal direction is in the X direction when viewed from above. That is, the window portion 14 is formed along the moving direction of the optical system stage 40, which will be described later. Further, the window portion 14 is arranged along the radial direction orthogonal to the rotation direction of the stage 11.

The optical system stage 40 supports the optical system unit 30. As shown in FIG. 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 a pedestal 60 via a guide mechanism 43. The guide mechanism 43 includes a linear guide 43a and a slider 43b. The linear guide 43a has a guide rail, a guide groove, etc. extending along the X direction. The slider 43b slides in the X direction along the linear guide 43a. The linear guide 43a is fixed to the frame 60. The slider 43b is fixed to the optical system stage 40. The linear guide 43a slidably holds the slider 43b.

Furthermore, a linear motion mechanism 41 is provided between the optical system stage 40 and the pedestal 60. The linear motion mechanism 41 includes an actuator such as a linear motor. The optical system stage 40 moves in the X direction as the linear motion mechanism 41 expands and contracts. That is, the optical system stage 40 is guided by the guide mechanism 43 and moves along the X direction. By moving the optical system stage 40, the position of the optical system unit 30 changes in the X direction.

In this way, the linear motion mechanism 41 drives the optical system stage 40, so that the optical system unit 30 moves in the X direction. Therefore, the linear motion mechanism 41 and the guide mechanism 43 serve as a moving mechanism for moving 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 a known method can be used. For example, the moving mechanism may include a ball screw, a cylinder, or the like.

Additionally, a rack 38 for holding the laser light source 35 is provided separately from the pedestal 60. The laser light source 35 is fixed to a rack 38. The laser light source 35 generates laser light 15 for annealing the object 16 to be processed. The laser light source 35 is a BLD (Blue Laser Diode) that generates blue laser light with a center wavelength of 450 nm. That is, the laser light source 35 is a blue semiconductor laser light source. Here, the laser beam 15 is a continuous wave (CW) laser beam. Of course, the laser irradiation device 1 may modulate the laser beam 15 into pulsed laser beam using a modulator or the like.

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

Laser light from the laser light source 35 enters the optical system unit 30 via the optical fiber 36. As shown in FIG. 1, the optical system unit 30 includes a housing 310, a lens 301, a lens 302, and a beam shaping section 307. Lens 301, lens 302, and beam shaping section 307 are fixed to housing 310. Of course, the optical system unit 30 may be provided with optical elements other than the lens 301, the lens 302, and the beam shaping section 307.

The laser light from the optical fiber 36 enters the beam shaping section 307. A beam shaping section 307 shapes the spot shape of the laser beam 15. For example, the beam shaping section 307 has a beam shaping mechanism such as a slit. Alternatively, when a plurality of optical fibers 36 are used, the beam may be shaped by the arrangement of the output ends of the optical fibers 36.

The laser beam 15 may be a Gaussian beam or a top flat beam. In the Gaussian beam, the spatial intensity distribution of the laser beam 15 on the object to be processed 16 is a Gaussian distribution. In the top flat beam, the spatial intensity distribution of the laser beam 15 on the object to be processed 16 is a top flat distribution. The beam shaping section 307 may include a beam homogenizer for making the spatial intensity distribution uniform. For example, the beam shaping section 307 may include a beam homogenizer for achieving a top flat distribution. The beam homogenizer has an optical element such as a fly's eye lens.

For example, the beam shaping unit 307 forms a top flat beam with a flat distribution along the X direction on the object to be processed 16. Further, the beam spot shape on the object to be processed 16 may be a line beam having a longitudinal direction and a transverse direction. In this case, the spot shape on the object to be processed 16 can have the X direction as the longitudinal direction and the Y direction as the lateral direction. For example, the spot size in the longitudinal direction can be about 1 mm, and the spot size in the X direction can be 0.2 mm. The beam shaping unit 307 can 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 section 307 may shape a top flat beam with a uniform intensity distribution in the Y direction. Note that the beam spot shape and its spatial distribution on the object to be processed 16 will be described later.

The laser beam shaped by the beam shaping section 307 enters the lens 301. Laser light 15 focused by lens 301 enters lens 302 . The optical axes of the

lenses

301 and 302 are parallel to the Z direction. The object to be processed 16 is irradiated with laser light 15 from the lens 302 . The lens 302 focuses the laser beam 15 onto the object to be processed 16 . Therefore, the laser beam 15 from the optical system unit 30 becomes a focused beam and is irradiated onto the object 16 to be processed. Lens 302 may be a cylindrical lens. By doing so, the laser beam 15 can be made into a line beam that forms a line on the object 16 to be processed.

The lens 302 focuses the laser beam 15 onto the object to be processed 16 . In FIG. 1, the optical system unit 30 is placed directly above the window section 14. Laser light 15 from optical system unit 30 enters object to be processed 16 via window 14 . The optical system unit 30 moves along the window section 14. The optical system unit 30 irradiates the object to be processed 16 with laser light 15 from above. The semiconductor layer 16b of the object to be processed 16 is annealed, and an activation process can be performed on the semiconductor layer 16b.

The stage 11 is a rotation stage having a rotation motor 61. The stage 11 rotates around a rotation axis AX that is parallel to the Z axis. While the stage 11 is rotating, the optical system unit 30 moves in the X direction. When viewed from above, the direction in which the optical system unit 30 moves and the direction in which the stage 11 rotates intersect. Specifically, the moving direction of the optical system unit 30 is parallel to the radial direction of the stage 11. The radial direction is a direction perpendicular to the rotation direction. By doing so, it is possible to irradiate the laser beam to any position on the object 16 to be processed.

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

For example, as the stage 11 rotates, the position of the laser beam 15 changes in the circumferential direction. As the optical system unit 30 moves, the position of the laser beam 15 changes in the radial direction. In FIG. 2, the trajectory on which the laser beam 15 is irradiated on the stage 11 is shown as an irradiation trajectory T1.

In FIG. 2, both 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 the laser beam 15a, and the end of the irradiation position in the +X direction corresponds to the laser beam 15b. The

laser beams

15a and 15b enter the object 16 through the window 14.

The optical system unit 30 moves the irradiation position of the laser beam 15 from the position indicated by the laser beam 15a to the position indicated by the laser beam 15b. The irradiation position of the laser beam 15a is at one end of the object to be processed 16 on the side farthest from the rotation axis AX, and the irradiation position of the laser beam 15b is at the other end of the object to be processed 16 on the side closest to the rotation axis AX. Become. That is, the optical system unit 30 moves so that the irradiation position of the laser beam 15 changes from one end of the object to be processed 16 to the other end in the radial direction. The movement range of the optical system unit 30 corresponds to the diameter of the object 16 to be processed. Thereby, the entire object to be processed 16 can be irradiated with the laser beam 15.

For example, while the stage 11 is rotating at a constant rotation speed, the optical system unit 30 moves in the X direction. The optical system unit 30 moves from the outer peripheral end 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 in the −X direction continuously or stepwise. As a result, the locus of the laser beam 15 on the stage 11 becomes spiral. Therefore, the plurality of objects 16 to be processed can be uniformly irradiated with laser light. Furthermore, while the object to be processed 16 is rotating, the optical system unit 30 may reciprocate in the +X direction and the −X direction.

Further, a measuring instrument 70 is provided on the +X side of the chamber 10. The measuring device 70 has a photodetector such as a photodiode, and measures the beam profile of the laser beam 15. That is, the measuring instrument 70 measures the spatial distribution of the laser beam 15 in a cross section perpendicular to the optical axis, that is, in the XY plane. For example, the measuring instrument 70 has a plurality of pixels (photodetecting elements) arranged in a row or an 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. Thereby, the measuring instrument 70 can measure a beam profile equivalent to the beam profile on the object 16 to be processed.

The measuring device 70 has a plurality of pixels arranged along the X direction. Therefore, based on the measurement results of the measuring device 70, the uniformity of the laser beam spot in the longitudinal direction can be evaluated. In other words, the uniformity of the top flat distribution can be evaluated and a stable process becomes possible. The measuring instrument 70 is placed outside the stage 11. Therefore, the measuring instrument 70 can measure the beam profile of the laser beam 15 before or after the laser irradiation process.

In this embodiment, a blue semiconductor laser diode (BLD) is used as the laser light source 35. Equipment costs can be suppressed. BLD has low photon cost. Furthermore, it is possible to eliminate the need for a wavelength conversion element or the like. This allows the process to be performed with high energy efficiency. Moreover, since BLD has a long life, maintenance costs can be suppressed, and the laser irradiation device 1 with high productivity can be realized.

The laser beam 15 from the BLD has low coherence. By using BLD, it becomes easy to generate a top-flat beam having a top-flat distribution. When generating a top flat beam, the beam homogenizer used in the beam shaping section 307 can be used. A beam homogenizer uses a lens array or diffracted photons to split or superimpose beams to obtain a desired spatial distribution. Since the coherence is low, no interference fringes occur in the beam homogenizer. BLD laser light does not generate speckles (interference fringes) even when guided through the optical fiber 36. Therefore, since laser light can be uniformly irradiated, a stable laser irradiation process can be realized. Therefore, it is possible to realize the laser irradiation device 1 with high productivity.

By the beam shaping unit 307 converting the laser beam into a top flat beam, the number of times the laser beams are overlapped can be reduced. As a result, throughput can be improved, so productivity can be improved. This point will be explained using FIG. 3. FIG. 3 is a schematic diagram for explaining the overlapping portion of the laser light in the top flat beam and the Gaussian beam.

In FIG. 3, the spot of the laser beam on the first rotation of the stage 11 is shown as a spot 15-1, and the spot of the laser light on the second rotation of the stage 11 is shown as a spot 15-2. Spot 15-2 has moved further to the −X side than spot 15-1. Further, the spots 15-1 and 15-2 on the object to be processed 16 are in the form of a line whose longitudinal direction is the X direction and whose transverse direction is the Y direction.

In the top flat beam, the region X1 where the laser light intensity I is uniform is long. Therefore, the proportion of overlapping portions between the first round and the second round can be reduced. The length F1 of the overlapping portion can be shortened. In other words, since the moving distance of the stage 11 during one rotation can be increased, the moving speed of the optical system unit 30 can be increased.

On the other hand, in the Gaussian beam, the region X2 where the laser light intensity I is uniform is short. Therefore, the proportion of overlap between the first round and the second round becomes large. It is necessary to increase the length F2 of the overlapped portion. In other words, since the moving distance of the stage 11 during one rotation becomes short, it is difficult to increase the moving speed of the optical system unit 30.

Therefore, by using the top flat beam, even when almost the entire surface of the object to be processed 16 is irradiated with laser light, the number of times the beam spots are overlapped can be reduced. Thereby, the rotation speed and the movement speed can be increased, so that throughput can be improved and productivity can be improved.

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 the radius of rotation. Assuming that the rotation speed is constant, the irradiation time per unit length in the circumferential direction changes depending on the rotation radius. Therefore, it is preferable to change the moving speed of the optical system unit 30 depending on the position of the optical system unit 30 in the X direction. In other words, it is preferable that the smaller the radius of rotation, 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 beam 15a, and the moving speed of the optical system unit 30 is the slowest at the irradiation position of the laser beam 15b. By doing so, the amount of laser light irradiation per unit area can be made uniform.

A case will be described in which the optical system unit 30 continuously moves in the X direction while the stage 11 is rotating at a constant rotational speed (number of rotations). In this case, the moving speed of the optical system unit 30 is made faster as it approaches the rotation axis AX. Specifically, the distance (rotation radius) from the rotation axis AX to the irradiation position is made to have a linear relationship with the moving speed. By doing so, the entire object to be processed 16 can be uniformly irradiated with laser light.

Alternatively, the rotation speed of the stage 11 may be changed while the moving speed of the optical system unit 30 is kept constant. In other words, the smaller the rotation radius, the faster the rotation speed may be.

An example of rotation speed and movement speed will be explained. Here, a description will be given assuming that the object to be processed 16 is a semiconductor wafer with a diameter of 300 mm, and the radius of rotation changes within a range of 450 mm to 750 mm. That is, at the irradiation position of the laser beam 15a in FIG. 2, the radius of rotation is 450 mm, and at the position of the laser beam 15b, the radius of rotation is 750 mm. Further, the moving distance in the X direction in one round of the stage 11 is assumed to be 0.2 mm.

When the moving speed of the optical system unit 30 in the X direction is 20 m/sec, when the rotation radius is 750 mm, the rotation speed can be set to 4.24 rps, and when the rotation radius is 450 mm, the rotation speed can be set to 7.07 rps.

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

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

Blue wavelength light has a moderate penetration depth into silicon wafers. A laser light source 35 generates laser light with a wavelength of 250 nm or more and 500 nm or less. By using laser light with a center wavelength of 250 nm to 500 nm, the semiconductor layer can be appropriately activated. By using laser light that penetrates deep into the semiconductor layer 16b, a deeper region can be activated. Furthermore, in this wavelength range, a continuous wave semiconductor laser light source can be used, so the device configuration can be simplified and costs can be reduced.

For example, a laser beam with a wavelength of 450 nm has a penetration depth of 0.24 μm into a silicon film. Therefore, absorption of laser light in the semiconductor layer 16b can be suppressed, so that the laser light reaches a deep region of the semiconductor layer 16b. Therefore, it is suitable for manufacturing a semiconductor device in which a PN junction is formed in a deep region. For example, the laser irradiation device 1 is suitable for activating power semiconductor devices such as vertical MOSFETs and IGBTs. The laser irradiation apparatus 1 is suitable for activation processing of a semiconductor device in which a PN junction is formed in a deep region of a semiconductor substrate. Semiconductor devices can be manufactured with high productivity. By using a semiconductor laser light source as the laser light source 35, it is possible to achieve a longer life than a solid-state laser.

In this embodiment, the laser light source 35 is fixed to a rack 38 that is different from the pedestal 60. Therefore, the laser light source 35 can be easily replaced and maintained. Alternatively, a modulator may be used to convert the laser light into pulsed light. Then, the object to be processed 16 may be irradiated with laser light at a timing when the object to be processed 16 is located directly under the window portion 14 . Thereby, it is possible to prevent the stage 11 from being irradiated with laser light at a time when the object to be processed 16 is not directly under the window section 14.

Additionally, a measuring instrument 70 measures the profile of the laser beam. Thereby, the object to be processed 16 can be irradiated with laser light having a uniform spatial distribution. Since the object to be processed 16 can be stably irradiated with laser light, productivity can be improved.

Embodiment 2
A laser irradiation device 1 according to a second embodiment will be explained using FIGS. 4 and 5. FIG. 4 is a side view schematically showing the configuration of the laser irradiation device 1. As shown in FIG. FIG. 5 is a top view schematically showing the configuration of the laser irradiation device 1. As shown in FIG. The second embodiment differs from the first embodiment in the arrangement of the laser light source 35. 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 that in Embodiment 1, so the description will be omitted as appropriate.

A 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. That is, the laser light source 35 is moved in the X direction by the movement of the linear motion mechanism 41. Even with such a configuration, the same effects as in the first embodiment can be obtained. Furthermore, the length of the optical fiber 36 can be shortened. Therefore, light loss in the optical fiber 36 can be reduced.

Embodiment 3
A laser irradiation device 1 according to a third embodiment will be explained using FIGS. 6 and 7. FIG. 6 is a side view schematically showing the configuration of the laser irradiation device 1. As shown in FIG. FIG. 7 is a top view schematically showing the configuration of the laser irradiation device 1. As shown in FIG. In the third embodiment, the optical fiber 36 is not provided between the laser light source 35 and the optical system unit 30. Furthermore, the configuration of the optical system in the optical system unit 30 is different from the first and second embodiments. The basic configuration other than these is the same as that of Embodiments 1 and 2, so the description will be omitted as appropriate.

A laser light source 35 is fixed to an optical system stage 40 as in the second embodiment. Further, in the optical system unit 30, a mirror 303 is arranged between the lens 301 and the lens 302. The laser light source 35 moves in the X direction together with the optical system unit 30. That is, the laser light source 35 moves in the X direction together with the lens 301, mirror 303, lens 302, etc. The laser light source 35 causes the laser light 15 to travel in the -X direction and enter the lens 301.

The optical axis of the lens 301 is parallel to the X direction. The lens 301 converts the laser beam 15 into a parallel light beam. The laser beam 15 from the lens 301 is reflected by the mirror 303 and travels in the -Z direction. Laser light 15 from mirror 303 enters lens 302 . The lens 302 focuses the laser beam 15 onto the object to be processed 16 . By doing so, the same effects as in the first and second embodiments can be obtained. Unlike the first and second embodiments, an optical fiber 36 is not provided between the laser light source 35 and the lens 301. Since the optical fiber 36 is not used, light loss can be suppressed.

Note that the beam shaping section 307 shown in Embodiments 1 and 2 may be provided between the lens 301 and the laser light source 35. Further, in Embodiments 1 to 3, the beam shaping section 307 may be arranged at a position other than the stage before the lens 301. In other words, the position of the beam shaping section 307 is not particularly limited.

In the second and third embodiments, the laser light source 35 has been described as being fixed to the optical system stage 40, but the laser light source 35 may be fixed to the pedestal 60. That is, the laser light source 35 does not have to move in the X direction together with the optical system unit 30. In this case, in the third embodiment, it is preferable that the lens 301 converts the laser beam 15 into a parallel beam.

The laser irradiation method using the laser irradiation apparatus 1 described in Embodiments 1 to 3 includes, for example, the following steps 1 to 3.
(Step 1) A step of generating laser light with a wavelength of 250 nm or more and 500 nm or less using a semiconductor laser light source.
(Step 2) A step of guiding the laser beam to a semiconductor substrate on a rotating stage by an optical system unit.
(Step 3) Moving the optical system unit so as to change the irradiation position of the laser beam in a direction different from the rotational direction of the rotation stage when viewed from above.

The laser irradiation method according to this embodiment can be applied to a method for manufacturing semiconductor devices. Thereby, semiconductor devices can be manufactured with high productivity.

(semiconductor device)
An example of a semiconductor device manufactured by the manufacturing method according to this embodiment will be described below. FIG. 8 is a cross-sectional view showing the stacked structure of the semiconductor device 600. Semiconductor device 600 is a vertical MOSFET. Specifically, the semiconductor device 600 is a planar MOSFET, and the back side of the semiconductor substrate 605 is the drain, and the front side is the source and gate. The semiconductor substrate 605 is a silicon substrate.

In the semiconductor device 600, an n ⁺ layer 601, an n ^- layer 602, a p layer 603, and an n ⁺ layer 604 are formed in order from the back side of a semiconductor substrate 605. Furthermore, a gate electrode 610 and a source electrode 620 are formed on the surface of the semiconductor substrate 605. The gate electrode 610 and the source electrode 620 are thin films of metal such as copper or aluminum. The semiconductor substrate 605 corresponds to the object to be processed 16 or the substrate 16a described above.

Impurities are implanted into the n ⁺ layer 601, the n ⁻ layer 602, the p layer 603, and the n ⁺ layer 604. For example, boron is implanted into the p layer 603 as a dopant. Phosphorous is implanted as a dopant into the n ⁺ layer 601, the n ⁻ layer 602, and the n ⁺ layer 604. The n ⁺ layer 601, the n ⁻ layer 602, the p layer 603, or the n ⁺ layer 604 corresponds to the semiconductor layer 16b.

When the laser irradiation device 1 irradiates the semiconductor substrate 605 with laser light, one or more of the n ⁺ layer 601, the n ⁻ layer 602, the p layer 603, and the n ⁺ layer 604 can be activated. Laser light 15 is irradiated from the upper surface of semiconductor substrate 605 . By doing so, the n ⁺ layer 601, the n ⁻ layer 602, the p layer 603, or the n ⁺ layer 604 can be activated. Note that the order of the laser beam irradiation steps is not particularly limited.

Further, the method according to the present embodiment is an irradiation method for activating a semiconductor layer of a semiconductor device, and includes a step of generating a laser beam with a wavelength of 250 nm or more and a wavelength of 500 nm or less, and using an optical system unit to generate the laser beam. and a step of changing a relative irradiation position of the laser beam to the semiconductor substrate. With this method, the semiconductor layer can be activated appropriately. This laser irradiation method is suitable for a method of manufacturing semiconductor devices. That is, the laser irradiation method is applied to an activation step in a semiconductor device manufacturing method.

Part or all of Embodiments 1 to 3 can be used in appropriate combination. Note that the present invention is not limited to the above embodiments, and can be modified as appropriate without departing from the spirit.

1 Laser irradiation device 10 Chamber 11 Stage 12 Adsorption plate 14 Window 15 Laser light 16 Object to be processed 16a Substrate 16b Semiconductor layer 30 Optical system unit 32 Optical connector 35 Laser light source 36 Optical fiber 40 Optical system stage 41 Linear motion mechanism 43 Guide mechanism 43a Linear guide 43b Slider 60 Mount 70 Measuring instrument 301 Lens 302 Lens 303 Mirror 307 Beam shaping section 310 Housing 600 Semiconductor device 601 N ⁺ layer 602 N ^- layer 603 P layer 604 N ⁺ layer 610 Gate electrode 620 Source electrode 605 Semiconductor board

Claims

a semiconductor laser light source that generates laser light with a wavelength of 250 nm or more and 500 nm or less;
a rotation stage that rotates the semiconductor substrate;
an optical system unit that guides the laser beam to the semiconductor substrate on the rotation stage;
A laser irradiation device comprising: a moving mechanism that moves the optical system unit so as to change the irradiation position of the laser beam in a direction different from the rotational direction of the rotation stage when viewed from above.
The laser irradiation device according to claim 1, further comprising a beam shaping section that shapes the laser beam so that the laser beam has a top-flat distribution on the semiconductor substrate.
The laser beam is shaped so that the laser beam on the semiconductor substrate has a spot shape whose width direction is the rotation direction of the rotary stage and whose length direction is a radial direction perpendicular to the rotation direction. The laser irradiation device according to item 2.
The moving mechanism moves the optical system unit along a radial direction perpendicular to the rotation direction of the rotation stage,
The laser irradiation device according to any one of claims 1 to 3, wherein the moving speed of the optical system unit becomes faster as the optical system unit approaches the rotation axis of the rotation stage.
The laser irradiation device according to any one of claims 1 to 3, further comprising an optical fiber that guides laser light from the semiconductor laser light source to the optical system unit.
The laser irradiation device according to any one of claims 1 to 3, wherein the plurality of semiconductor substrates are arranged symmetrically with respect to the rotation axis of the rotation stage.
The laser irradiation device according to any one of claims 1 to 3, further comprising a measuring instrument for measuring the profile of the laser beam provided outside the rotation stage.
(A1) generating laser light with a wavelength of 250 nm or more and 500 nm or less using a semiconductor laser light source;
(A2) guiding the laser beam to a semiconductor substrate on a rotating stage by an optical system unit;
(A3) A laser irradiation method comprising the step of moving the optical system unit so as to change the irradiation position of the laser beam in a direction different from the rotational direction of the rotation stage when viewed from above.
The laser irradiation method according to claim 8, wherein the beam shaping section shapes the laser beam so that the laser beam has a top-flat distribution on the semiconductor substrate.
The laser beam is shaped so that the laser beam on the semiconductor substrate has a spot shape whose width direction is the rotation direction of the rotary stage and whose length direction is a radial direction perpendicular to the rotation direction. The laser irradiation method according to item 9.
In step (A3), the optical system unit is moved along a radial direction perpendicular to the rotation direction of the rotation stage,
The laser irradiation method according to any one of claims 8 to 10, wherein the moving speed of the optical system unit increases as it approaches the rotation axis of the rotation stage.
The laser irradiation method according to any one of claims 8 to 10, wherein the laser light from the semiconductor laser light source is guided to the optical system unit via an optical fiber.
The laser irradiation method according to any one of claims 8 to 10, wherein the plurality of semiconductor substrates are arranged symmetrically with respect to the rotation axis of the rotation stage.
The laser irradiation method according to any one of claims 8 to 10, wherein a measuring instrument measures the profile of the laser beam outside the rotation stage.
(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 beam to a semiconductor substrate on a rotating stage by an optical system unit;
(S3) A method for manufacturing a semiconductor device, comprising the step of moving the optical system unit so as to change the irradiation position of the laser beam in a direction different from the rotational direction of the rotation stage when viewed from above.
16. The method for manufacturing a semiconductor device according to claim 15, wherein the beam shaping section shapes the laser beam so that the laser beam has a top-flat distribution on the semiconductor substrate.
The laser beam is shaped so that the laser beam on the semiconductor substrate has a spot shape whose width direction is the rotation direction of the rotary stage and whose length direction is a radial direction perpendicular to the rotation direction. 17. A method for manufacturing a semiconductor device according to item 16.
In the step (S3), the optical system unit is moved along a radial direction perpendicular to the rotation direction of the rotation stage,
18. The method for manufacturing a semiconductor device according to claim 15, wherein the moving speed of the optical system unit increases as the optical system unit approaches the rotation axis of the rotation stage.
The method for manufacturing a semiconductor device according to any one of claims 15 to 17, wherein the laser light from the semiconductor laser light source is guided to the optical system unit via an optical fiber.
The method for manufacturing a semiconductor device according to any one of claims 15 to 17, wherein the plurality of semiconductor substrates are arranged symmetrically with respect to the rotation axis of the rotation stage.
The method for manufacturing a semiconductor device according to any one of claims 15 to 17, wherein a measuring instrument measures the profile of the laser beam outside the rotation stage.