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

Abstract

According to the present embodiment, a laser irradiation device (1) for activating a semiconductor layer of a semiconductor device comprises: a laser light source (35) that generates laser light (15) with a wavelength of 250 nm to 500 nm; an optical system unit (30) that guides the laser light to the semiconductor substrate; and a drive mechanism that changes the relative irradiation position of the laser light relative to the semiconductor substrate.

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a laser annealing device using an excimer laser. In Patent Document 1, a levitation unit levitates a substrate, and a transport unit transports the substrate. A linear laser beam is irradiated onto the substrate during transportation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2018-64048 Summary of the Invention [Problem to be solved by the invention]

[0004] Such excimer laser light sources are expensive, making it difficult to reduce the cost of parts for the device. Therefore, it is desirable to use a light source other than an excimer laser light source. Semiconductor lasers are inexpensive, but they are continuous wave (CW) lasers. When CW laser light is pulsed using a modulator, the output decreases. Therefore, many light sources are required, making it difficult to reduce costs.

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

[0006] According to one embodiment, the laser irradiation device is a laser irradiation device for activating a semiconductor layer of a semiconductor device, and includes a semiconductor laser light source that generates laser light having a wavelength of 250 nm or more and 500 nm or less, an optical system unit that guides the laser light to a semiconductor substrate, and a drive mechanism that changes the relative irradiation position of the laser light with respect to the semiconductor substrate.

[0007] According to one embodiment, the laser irradiation device is a laser irradiation device that irradiates laser light onto a semiconductor substrate on which a plurality of chip regions are formed, and includes a laser light source that generates laser light, an optical system unit that guides the laser light onto the semiconductor substrate so that the longitudinal size of the spot shape of the laser light on the semiconductor substrate is larger than the size of the chip regions, and a drive mechanism that changes the relative irradiation position of the laser light with respect to the semiconductor substrate.

[0008] According to one embodiment, a laser irradiation method is a laser irradiation method for activating a semiconductor layer of a semiconductor device, and includes the steps of: (A1) generating laser light having a wavelength of 250 nm or more and 500 nm or less; (A2) guiding the laser light to a semiconductor substrate by an optical system unit; and (A3) changing the relative irradiation position of the laser light with respect to the semiconductor substrate.

[0009] According to one embodiment, a laser irradiation method is a laser irradiation method for irradiating a semiconductor substrate having a plurality of chip regions formed thereon with laser light, and includes the steps of: (B1) generating laser light; (B2) guiding the laser light to the semiconductor substrate so that the longitudinal size of the spot shape of the laser light on the semiconductor substrate is larger than the size of the chip regions; and (B3) changing the relative irradiation position of the laser light with respect to the semiconductor substrate.

[0010] According to one embodiment, the manufacturing method includes an irradiation step (S1) of irradiating a semiconductor substrate with laser light to activate a semiconductor layer of a semiconductor device, and the irradiation step (S1) includes the steps of (SA1) generating laser light having a wavelength of 250 nm or more and 500 nm or less, (SA2) guiding the laser light to the semiconductor substrate by an optical system unit, and (SA3) changing the relative irradiation position of the laser light with respect to the semiconductor substrate.

[0011] According to one embodiment, the manufacturing method includes (T1) an irradiation step of irradiating a semiconductor substrate having a plurality of chip regions formed thereon with laser light, and the (T1) irradiation step includes (TB1) a step of generating laser light, (TB2) a step of guiding the laser light to the semiconductor substrate so that the longitudinal size of the spot shape of the laser light on the semiconductor substrate is larger than the size of the chip regions, and (TB3) a step of changing the relative irradiation position of the laser light with respect to the semiconductor substrate.

[0012] According to the embodiment, it is possible to provide a highly productive laser irradiation apparatus, a laser irradiation method, and a method for manufacturing a semiconductor device. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a top view schematically showing a laser irradiation device according to a first embodiment. [Figure 2] 1 is an XZ cross-sectional view schematically showing a laser irradiation device according to a first embodiment. [Figure 3] 1 is a YZ cross-sectional view schematically showing a laser irradiation device according to a first embodiment. [Figure 4] FIG. 10 is a top view for explaining the spot shape on the object to be processed. [Figure 5] FIG. 10 is a top view for explaining the spot shape on the object to be processed. [Figure 6] FIG. 10 is an XZ cross-sectional view schematically showing a laser irradiation device according to a second embodiment. [Figure 7] FIG. 10 is a YZ cross-sectional view schematically showing a laser irradiation device according to a second embodiment. [Figure 8] FIG. 10 is a top view for explaining the spot shape on the object to be processed. [Figure 9] 10 is a graph showing a profile of impurity concentration after laser irradiation. [Figure 10] 1 is a cross-sectional view showing an example of the configuration of a semiconductor device manufactured by a manufacturing method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Embodiment 1 The laser irradiation apparatus according to this embodiment performs an annealing process by irradiating a workpiece (also referred to as a work) with laser light. The laser irradiation apparatus heats the substrate with laser light to perform an activation process on a semiconductor layer provided on the substrate. The workpiece is a semiconductor substrate for forming semiconductor chips. The semiconductor substrate is a silicon wafer or a compound semiconductor wafer.

[0015] 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 the power semiconductor devices are formed. The semiconductor substrate has a semiconductor layer into which impurities are implanted (also called an impurity implanted layer). The semiconductor layer can be activated by irradiating the semiconductor layer with laser light using a laser irradiation device. Furthermore, the method according to the present embodiment is not limited to power semiconductors. For example, the method according to the present embodiment can be applied to the activation of the semiconductor layer of semiconductor chips such as image sensors and the manufacturing method thereof.

[0016] The laser irradiation device uses a blue semiconductor laser light source as a laser light source. The laser irradiation device performs annealing for activation by irradiating the object to be treated with blue laser light from the semiconductor laser light source. Note that the laser light is not limited to blue laser light, and can be laser light with a wavelength of 250 nm or more and 500 nm or less.

[0017] The configuration of the laser irradiation device according to this embodiment will be described with reference to Fig. 1 to Fig. 3. Fig. 1 is a top view schematically showing the configuration of the laser irradiation device 1. Fig. 2 is an XZ sectional view schematically showing the configuration of the laser irradiation device 1. Fig. 3 is a YZ sectional view schematically showing the configuration of the laser irradiation device 1.

[0018] 1 to 3, the laser irradiation device 1 includes a levitation unit 10, a transport unit 11, an optical system unit 30, a Y-drive mechanism 32, and a stage 40. The levitation unit 10 and the transport unit 11 constitute a transport device.

[0019] In the following figures, an XYZ three-dimensional Cartesian coordinate system is shown where appropriate for ease of explanation. The Z direction is the vertical direction, perpendicular to the main surface of the workpiece 16. The X direction is the transport direction of the workpiece 16. The Y direction is the movement direction of the optical system unit 30. The workpiece 16 being transported in the X direction is irradiated with the laser light 15. Furthermore, the optical system unit 30 moves in the Y direction. Therefore, the irradiation position of the laser light on the workpiece 16 can be changed in the X direction and the Y direction. This allows the laser light to be irradiated onto almost the entire surface of the workpiece 16.

[0020] As shown in Fig. 2, the levitation unit 10 is configured to eject gas from the surface of the levitation unit 10. The levitation unit 10 levitates the object 16 to be processed using its upper surface. The gas ejected from the surface of the levitation unit 10 is sprayed onto the lower surface of the object 16 to cause the object 16 to levitate. When the object 16 to be processed is transported, the levitation unit 10 adjusts the amount of levitation so that the object 16 does not come into contact with other mechanisms (not shown) arranged above the object 16 to be processed.

[0021] The levitation unit 10 is made of a porous material. For example, the levitation unit 10 is made of a ceramic material such as porous alumina or porous SiC. Here, the levitation unit 10 is a porous material plate with a thickness of 10 mm. The levitation unit 10 is connected to an air supply port (not shown). Therefore, gas from a gas supply means (not shown) such as a gas cylinder is ejected from the upper surface of the levitation unit 10.

[0022] The transport unit 11 transports the floating workpiece 16 in the transport direction. As shown in FIG. 1, the transport unit 11 includes a holding mechanism 12 and a moving mechanism 13. The holding mechanism 12 holds the workpiece 16. For example, the holding mechanism 12 can be configured using a vacuum suction mechanism. The vacuum suction mechanism is made of a metal material such as an aluminum alloy. Alternatively, the holding mechanism 12 may be made of a resin material such as PEEK (polyether ether ketone). The upper surface of the holding mechanism 12 has suction grooves, suction holes, etc. formed thereon. The holding mechanism 12 may also be made of a porous material.

[0023] The holding mechanism 12 (vacuum suction mechanism) is connected to an exhaust port (not shown), which is connected to an ejector, a vacuum pump, etc. Therefore, a negative pressure for sucking gas acts on the holding mechanism 12, and the object 16 to be processed can be held by using the holding mechanism 12.

[0024] The holding mechanism 12 holds the object 16 by sucking the surface (lower surface) of the object 16 opposite to the surface (upper surface) irradiated with the laser light 15, that is, the surface of the object 16 facing the levitation unit 10. The holding mechanism 12 also holds the end of the object 16 in the +Y direction.

[0025] The moving mechanism 13 provided in the transport unit 11 is connected to the holding mechanism 12. The moving mechanism 13 is configured to be able to move the holding mechanism 12 in the transport direction. The transport unit 11 (holding mechanism 12 and moving mechanism 13) is provided on the end side of the levitation unit 10 in the +Y direction, and the object 16 is transported by the moving mechanism 13 moving in the transport direction while the holding mechanism 12 holds the object 16.

[0026] 1, for example, the moving mechanism 13 is configured to slide the end of the levitation unit 10 in the +Y direction along the transport direction. When the moving mechanism 13 slides the end of the levitation unit 10 along the transport direction, the object 16 to be processed is transported along the transport direction.

[0027] The transport speed of the object 16 can be controlled by controlling the movement speed of the movement mechanism 13. The movement mechanism 13 includes, for example, an actuator such as a motor, a linear guide mechanism, an air bearing, and the like (not shown).

[0028] The workpiece 16 is a substantially circular semiconductor wafer. The semiconductor wafer may have an orientation flat, a notch, or the like formed thereon. The workpiece 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 of the laser wavelength.

[0029] The semiconductor layer 16b is an impurity-injected layer into which impurities such as phosphorus (P) or boron (B) are injected. The PN junction can be activated by irradiating the semiconductor layer 16b with laser light 15 and performing an annealing process. In other words, the laser irradiation device 1 serves as an annealing device for activating the semiconductor layer 16b. Although only the semiconductor layer 16b is shown in the figure, other films or layers may be formed. For example, a thin film of copper or aluminum that will serve as wiring may be formed. Furthermore, an insulating layer such as a silicon oxide film may be formed on the substrate 16a.

[0030] A stage 40 is disposed above the levitation unit 10. The stage 40 movably holds the optical system unit 30. The optical system unit 30 guides laser light from a laser light source 35 to the object 16 to be processed. The optical system unit 30 is disposed on the -X side of the stage 40. Therefore, the optical system unit 30 is disposed directly above the object 16 to be processed. Therefore, the laser light 15 from the optical system unit 30 is irradiated onto the object 16 to be processed from above.

[0031] Stage 40 serves as a guide mechanism that guides movement of optical system unit 30 in the Y direction. For example, stage 40 is provided with guide rails, guide grooves, etc. Stage 40 is also provided with Y drive mechanism 32. Stage 40 is a gantry stage that is provided along the Y direction in the space above levitation unit 10. Y drive mechanism 32 drives optical system unit 30 in the Y direction.

[0032] The optical system unit 30 moves along the stage 40. As the optical system unit 30 moves in the Y direction, the irradiation position of the laser light 15 changes in the Y direction. On the +Y side and the -Y side, the stage 40 is positioned so as to extend beyond the levitation unit 10. Therefore, in the Y direction, the optical system unit 30 can irradiate the laser light to any position on the object 16 to be processed.

[0033] Next, an example of a laser light source and its optical system will be described. The laser light source 35 generates laser light for annealing the workpiece 16. The laser light source 35 is a blue laser diode (BLD) that generates blue laser light with a center wavelength of 450 nm. In other words, the laser light source 35 is a blue semiconductor laser light source. Here, the laser light is a continuous wave (CW) laser light. Of course, the laser irradiation device 1 may modulate the laser light into pulsed laser light using a modulator or the like.

[0034] The laser light source 35 is coupled to an optical fiber 36. The laser light from the laser light source 35 enters the optical system unit 30 via the optical fiber 36. As shown in Fig. 2, the optical system unit 30 includes a lens 301, a mirror 302, a lens 303, and a beam shaping unit 307. Of course, the optical system unit 30 may include optical elements other than the lens 301, the mirror 302, the lens 303, and the beam shaping unit 307.

[0035] The laser light from the optical fiber 36 enters the beam shaping unit 307. The beam shaping unit 307 shapes the spot shape of the laser light. For example, the beam shaping unit 307 has a beam shaping mechanism such as a slit. Alternatively, when multiple optical fibers 36 are used, the beam may be shaped by arranging the exit ends of the optical fibers 36. The beam shaping unit 307 shapes the beam so that the cross-sectional shape of the beam (spot shape) in a direction perpendicular to the optical axis becomes rectangular. For example, the spot shape is a rectangle with a longitudinal size of 10 to 14 mm and a lateral size of 0.5 mm. By using a beam homogenizer or the like in the beam shaping unit 307, the laser light intensity can be made to have a flat-top distribution. The beam spot shape on the treatment object 16 will be described later.

[0036] The laser light shaped by the beam shaping unit 307 enters the lens 301. The laser light condensed by the lens 301 enters the mirror 302. The mirror 302 reflects the laser light toward the object 16 to be processed. Specifically, the mirror 302 reflects the laser light downward. The laser light reflected by the mirror 302 enters the lens 303.

[0037] The laser light 15 from the lens 303 is irradiated onto the object 16 to be processed. The lens 303 focuses the laser light 15 onto the object 16 to be processed. Therefore, the laser light 15 from the optical system unit 30 becomes a focused beam and is irradiated onto the object 16 to be processed. The lens 303 may be a cylindrical lens. In this way, the laser light 15 can be made into a line beam that is linear on the object 16 to be processed.

[0038] The optical system unit 30 irradiates the object 16 from above with the laser light 15. The semiconductor layer 16b of the object 16 is annealed, and activation processing can be performed on the semiconductor layer 16b.

[0039] The spot shape on the object to be processed 16 will be explained with reference to FIG. 4. FIG. 4 is a top view schematically showing the object to be processed 16 and the spot shape of the laser light 15. A plurality of chip regions C are formed on the object to be processed 16. Power semiconductor chips are formed in the chip regions C. The chip regions C are arranged in a matrix along the X and Y directions. When viewed from above, each chip region C has a rectangular shape. The chip regions C are regions where semiconductor circuits are formed.

[0040] The area between two adjacent chip areas C becomes a scribe line S. The semiconductor wafer is cut along the scribe line S to separate semiconductor chips. Here, the scribe line S between the chip areas C is parallel to the X direction or the Y direction. In other words, the scribe line S is formed in a grid pattern. The semiconductor wafer is cut in the X direction and the Y direction to separate semiconductor chips.

[0041] Here, the spot shape of the laser light 15 is formed into a line shape with the X direction as the longitudinal direction and the Y direction as the lateral direction. That is, on the object to be processed 16, the laser light 15 is a line beam extending in the X direction. For example, the spot size of the laser light 15 is a rectangle measuring 14 mm in the X direction and 0.5 mm in the Y direction. Furthermore, the laser light 15 is a CW light with an output of 2 kW.

[0042] The size of the spot shape of the laser beam 15 in the longitudinal direction (X direction) is larger than the size of the chip regions C. The beam shaping unit 307 of the optical system unit 30 shapes the laser beam so that the size of the laser beam in the longitudinal direction on the workpiece 16 is larger than the size of the chip regions C. The +X side end of the spot shape of the laser beam 15 is located on the +X side of the chip regions C, and the -X side end is located on the -X side of the chip regions C. In other words, the ends of the laser spot are located on the scribe lines S. Therefore, by moving the optical system unit 30 in the Y direction with the Y drive mechanism 32, the entire chip regions C for one row are irradiated with the laser beam. In other words, by moving the optical system unit 30 in the Y direction, the laser beam 15 can scan one row of the chip regions C.

[0043] Furthermore, the transport unit 11 moves the workpiece 16 in the X direction. As a result, the irradiation position of the laser light 15 changes in the X direction. For example, when the transport unit 11 moves the workpiece 16 by one row in the X direction from the state shown in FIG. 4, the state becomes as shown in FIG. 5. Then, the Y drive mechanism 32 moves the optical system unit 30 in the Y direction, so that the laser light is irradiated onto the chip areas C in the second row. By repeating this process, all of the chip areas C are irradiated with the laser light.

[0044] 5, the scanning directions of the first and second rows of chip areas C are the same, but they may be opposite. For example, when the irradiation position of the laser light in the first row of chip areas C moves in the -Y direction, the irradiation position of the laser light in the second row of chip areas C may move in the +Y direction.

[0045] In this way, the irradiation position of the laser beam 15 on the object 16 to be processed changes in the X and Y directions. This allows the laser beam 15 to be raster scanned or zigzag scanned. The laser beam 15 can be irradiated onto almost the entire surface of the object 16 to be processed.

[0046] The laser light intensity at the irradiation spot of the laser light 15 has a flat-top distribution or a Gaussian distribution. For example, by making the laser light intensity have a flat-top distribution, it is possible to irradiate the chip region C with laser light of uniform intensity. This allows the semiconductor layer to be appropriately activated, and productivity to be improved.

[0047] The beam shaping unit 307 shapes the beam so that it has a flat-top distribution. For example, it is preferable that the laser light intensity has a flat-top distribution in any one direction in the object 16 to be processed. Furthermore, it is preferable that the laser light intensity has a flat-top distribution in both the X and Y directions.

[0048] The optical system unit 30 moves in the short direction of the laser light 15 on the workpiece 16. In other words, while the optical system unit 30 is moving in the Y direction, the workpiece 16 is irradiated with CW laser light with the Y direction as its short direction. This makes it possible to shorten the irradiation time (heating time) during which the laser light is continuously irradiated to one point on the workpiece 16. The movement speed of the optical system unit 30 in the Y direction is, for example, 1 m / sec. If the spot size in the Y direction is 0.5 mm, the heating time is 0.5 msec. This makes it possible to prevent localized heating of the base film, etc. This makes it possible to perform a stable annealing process and improve productivity.

[0049] The irradiation time per location can be adjusted by setting the movement speed according to the spot shape of the laser light on the workpiece 16. It is preferable that the irradiation time per location on the workpiece 16 is 100 μsec or less. In other words, the movement speed of the optical system unit 30 is set so that the irradiation time per location on the workpiece 16 is 100 μsec or less. This prevents localized heating, allowing for appropriate annealing.

[0050] Furthermore, the laser light is irradiated so that the edge of the irradiation spot of the laser light in the X direction becomes the scribe line S. In other words, the laser light is irradiated so that the edge position of the irradiation spot in the X direction does not coincide with the chip region C. In this way, it is possible to reduce unevenness in irradiation intensity in the X direction in one chip region C. Therefore, it is possible to irradiate the entire chip region in the X direction with uniform laser light. This can improve productivity.

[0051] In the above description, the spot size of the laser light in the X direction is a size that can irradiate one row of chip areas, but it may be a size that can irradiate two or more rows of chip areas C at once. In other words, the spot size of the laser light in the X direction may be more than twice the size of the chip areas C. In this case, too, it is preferable that the edge position of the irradiation spot of the laser light in the X direction is on the scribe line S.

[0052] In this embodiment, the laser light source 35 generates laser light having a wavelength of 250 nm or more and 500 nm or less. By using laser light with a central wavelength of 250 nm to 500 nm, the semiconductor layer can be appropriately activated. By using laser light with a deep penetration depth into the semiconductor layer 16b, deeper regions can be activated. Furthermore, in this wavelength range, a continuous wave semiconductor laser light source can be used, which simplifies the device configuration and reduces costs.

[0053] For example, the penetration depth of a laser beam with a wavelength of 450 nm into a silicon film is 0.24 μm. Therefore, absorption of the laser beam in the semiconductor layer 16b can be suppressed, and the laser beam reaches a deep region of the semiconductor layer 16b. This makes it suitable for manufacturing semiconductor devices in which a PN junction is formed in a deep region. For example, the laser irradiation apparatus 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 semiconductor devices in which a PN junction is formed in a deep region of a semiconductor substrate. Semiconductor devices can be manufactured with high productivity.

[0054] By using the levitation unit 10, the object 16 to be processed can be prevented from being fixed at the position irradiated with the laser light. In other words, the levitation unit 10 can hold the object 16 to prevent the object 16 from being fixed at the position irradiated with the laser light. In this way, stress generated in the object 16 to be processed due to local thermal expansion or the like can be alleviated.

[0055] Embodiment 2 The laser irradiation device according to the second embodiment will be described with reference to Figs. 6 to 8. Fig. 6 is an XZ plan view showing the configuration of the laser irradiation device 1. Fig. 7 is a YZ plan view showing the configuration of the laser irradiation device 1. Fig. 8 is a diagram showing the object to be processed 16 and the spot shape of the laser light 15. Note that the basic configuration of the laser irradiation device 1 is the same as in the first embodiment, so the description will be omitted as appropriate and the drawings will be simplified. For example, the light source is a laser light source with a wavelength of 250 nm or more and 500 nm or less, as in the first embodiment.

[0056] In this embodiment, the object 16 to be processed is placed on a drive stage 20. The drive stage 20 holds the object 16 to be processed so that it can move in the X and Y directions. For example, the drive stage 20 has a motor, a guide mechanism, etc. for moving the drive stage 20 in the X and Y directions. When the drive stage 20 moves, the object 16 to be processed on the drive stage 20 moves. Therefore, the irradiation position of the laser light 15 on the object 16 to be processed can be changed.

[0057] The driving stage 20 may be an adsorption stage that adsorbs and holds the object 16. For example, the driving stage 20 may be a vacuum chuck stage or an electrostatic chuck stage.

[0058] Laser light from the laser light source 35 enters the optical system unit 30 via an optical fiber 36. The laser light from the optical fiber enters the lens 301, the optical scanner 308, and the fθ lens 309 in that order. The lens 301 focuses the laser light toward the optical scanner 308. The optical scanner 308 reflects the laser light toward the fθ lens 309.

[0059] The optical scanner 308 is, for example, a galvanometer mirror, and deflects the laser beam 15. The optical scanner 308 changes the deflection angle of the laser beam 15, thereby changing the irradiation position of the laser beam 15 on the object 16 to be processed. The laser beam L1 is scanned in the X direction.

[0060] Specifically, the optical scanner 308 is operated by a drive motor that rotates around the Y axis. The optical scanner 308 scans the laser beam 15 along the X direction on the object 16 to be processed. In other words, as the optical scanner 308 scans the laser beam 15, the irradiation position of the laser beam 15 moves in the X direction on the object 16 to be processed. Furthermore, the optical scanner 308 is not limited to a galvanometer mirror, and may be a polygon mirror, an acousto-optical element, or the like.

[0061] The fθ lens 309 refracts the laser beam 15 reflected by the optical scanner 308. By placing the fθ lens 309 directly above the object 16 to be processed, the focal plane of the laser beam 15 can be made to coincide with the main surface of the object 16 to be processed. In other words, the focal position of the laser beam 15 in the Z direction is at a constant height regardless of the deflection angle of the optical scanner 308. This makes it possible to make the irradiation power density of the laser beam 15 on the object 16 to be processed constant.

[0062] The spot shape of the laser beam L1 irradiated onto the workpiece 16 may be circular or rectangular. The intensity distribution of the laser beam 15 in the beam cross section may be a Gaussian distribution. Alternatively, the laser beam 15 may be given a top-flat shape (top-hat shape) by a modulator or the like. For more uniform irradiation, it is preferable that the spot shape of the laser beam L1 is rectangular and the intensity distribution is a top-flat distribution.

[0063] For example, the spot shape of the laser light on the object to be processed 16 is a square of 0.5 mm x 0.5 mm. Furthermore, an optical scanner 308 scans the laser light 15 in the X direction. Furthermore, a Y drive mechanism 32 drives the optical system unit 30 in the Y direction. This allows the irradiation position of the laser light to be moved at high speed in the X and Y directions.

[0064] The scanning speed of the optical scanner 308 is faster than the moving speed of the laser light irradiation position by the Y drive mechanism 32 and the drive stage 20. By using the optical scanner 308, it is possible to shorten the irradiation time (heating time) at any one point on the workpiece 16. This enables a stable process and improves productivity.

[0065] The irradiation time per location can be adjusted by setting the scanning speed according to the spot shape of the laser light on the workpiece 16. It is preferable that the irradiation time per location on the workpiece 16 is 100 μsec or less. In other words, the scanning speed is set so that the irradiation time per location on the workpiece 16 is 100 μsec or less. This prevents localized heating, allowing for appropriate annealing.

[0066] For example, the scanning direction of the optical scanner 308 is the X direction, and the movement direction of the optical system unit 30 is the Y direction. The movement direction of the drive stage 20 can be the X direction. This allows two-dimensional scanning, making it possible to anneal almost the entire surface of the workpiece 16. Of course, the scanning direction of the optical scanner 308, the movement direction of the optical system unit 30, and the movement direction of the drive stage 20 are not particularly limited.

[0067] In the first and second embodiments, a blue laser diode is provided as the laser light source 35, but the laser light source 35 is not limited to this. Specifically, the laser light source 35 preferably generates laser light with a wavelength of 250 nm or more and 500 nm or less. Of course, the laser wavelength may be outside the above range.

[0068] The drive stage 20 may hold the workpiece 16 so that it is not fixed at the laser beam irradiation position. For example, in the second embodiment, the drive stage 20 may be a non-suction stage that does not hold the workpiece 16 by suction. If the drive stage 20 is a suction stage, the drive stage 20 may be configured to be able to partially suction the workpiece 16. For example, the suction region of the suction stage for the workpiece 16 may be divided into multiple regions, and suction may be controlled on and off. In this way, the drive stage 20 can suction the workpiece 16 at a location other than the laser beam irradiation position without suction at the laser beam irradiation position. This allows the drive stage 20 to hold the workpiece 16 so that it is not fixed at the laser beam irradiation position. This can alleviate stress generated in the workpiece 16 due to local thermal expansion, etc.

[0069] It should be noted that the first and second embodiments can be used in appropriate combination. For example, in the first embodiment, the levitation unit 10 and the transport unit 11 can be replaced with the drive stage 20. Alternatively, in the second embodiment, the drive stage 20 can be replaced with the levitation unit 10 and the transport unit 11. The optical scanner 304 can also be used in the first embodiment. The means for changing the irradiation position of the laser light can be one or more of the drive stage 20, the transport unit 11, the Y drive mechanism 32 of the optical system unit, and the optical scanner 304.

[0070] Example FIG. 9 is a graph showing the impurity concentration profile after the above laser irradiation. Here, boron (B) and phosphorus (P) ions are implanted into a silicon wafer having a thickness of 150 μm as the workpiece 16. FIG. 9 shows the SIMS (Secondary Ion Mass Spectrometry) profiles of boron and phosphorus, respectively. Furthermore, FIG. 9 shows the profile obtained by SRP (Spreading Resistance Profiling). In FIG. 9, the horizontal axis represents thickness and the vertical axis represents impurity concentration. The results are shown when a line beam is irradiated as in the first embodiment. Here, the beam size on the workpiece 16 is 10 mm × 0.5 mm.

[0071] The power density of the laser light 15 on the object 16 to be processed is 40 kW / cm2, and the laser power is 2 kW. The energy density is 60 J / cm2, the irradiation time is 1.5 msec, and the movement speed of the optical system unit 30 is 333 mm / sec. The activation rate of boron is 61%, and the activation rate of phosphorus is 107%. Therefore, the laser irradiation method according to this embodiment can appropriately activate the impurity layer.

[0072] (Semiconductor Devices) An example of a semiconductor device manufactured by the manufacturing method according to this embodiment will be described below. Fig. 10 is a cross-sectional view showing the layered structure of a semiconductor device 600. The semiconductor device 600 is a vertical MOSFET. Specifically, the semiconductor device 600 is a planar MOSFET, with the back side of a semiconductor substrate 605 serving as the drain and the front side serving as the source and gate. The semiconductor substrate 605 is a silicon substrate.

[0073] The semiconductor device 600 has n + Layer 601, n - layer 602, p layer 603, n +A layer 604 is formed on the surface of the 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 made of thin metal films such as copper or aluminum. The semiconductor substrate 605 corresponds to the object to be processed 16 or the substrate 16a.

[0074] n + Layer 601, n - layer 602, p layer 603, n + The layer 604 is doped with impurities. The p-layer 603 is doped with boron, for example. + Layer 601, n - layer 602, n + Layer 604 is implanted with phosphorus as a dopant. + Layer 601, n - layer 602, p layer 603, or n + The layer 604 corresponds to the semiconductor layer 16b.

[0075] The laser irradiation device 1 irradiates the semiconductor substrate 605 with laser light, thereby forming n + Layer 601, n - layer 602, p layer 603, n + One or more layers of the layer 604 can be activated. The upper surface of the semiconductor substrate 605 is irradiated with laser light 15. By doing so, n + Layer 601, n - layer 602, p layer 603, or n + This can activate the layer 604. The order of the laser light irradiation steps is not particularly limited.

[0076] Furthermore, a method according to the present embodiment is an irradiation method for activating a semiconductor layer of a semiconductor device, and includes the steps of generating laser light having a wavelength of 250 nm or more and 500 nm or less, guiding the laser light to a semiconductor substrate using an optical system unit, and changing the relative irradiation position of the laser light with respect to the semiconductor substrate. This method allows for appropriate activation of the semiconductor layer. This laser irradiation method is suitable for semiconductor device manufacturing methods. In other words, the laser irradiation method is applied to an activation step in semiconductor device manufacturing methods.

[0077] The laser irradiation method according to this embodiment is a laser irradiation method for irradiating a semiconductor substrate having a plurality of chip regions with laser light, and includes the steps of: generating laser light; guiding the laser light to the semiconductor substrate so that the longitudinal size of the spot shape of the laser light on the semiconductor substrate is larger than the size of the chip regions; and (B3) changing the relative irradiation position of the laser light with respect to the semiconductor substrate. This method enables appropriate laser light irradiation. This laser irradiation method is suitable for semiconductor device manufacturing methods. In other words, the laser irradiation method is applied to an activation step in semiconductor device manufacturing methods.

[0078] It is possible to use a combination of some or all of the first and second embodiments as appropriate. Note that the present invention is not limited to the above-described embodiments, and can be modified as appropriate within the scope of the invention. [Explanation of symbols]

[0079] 1. Laser irradiation device 10 Levitation Unit 11 Transport unit 12 Retention mechanism 13 Moving mechanism 15 Laser light 16 Object to be treated 16a board 16b Semiconductor layer 20 Drive Stage 30 Optical system unit 32 Y drive mechanism 301 Lens 302 Mirror 303 Lens 40 stages

Claims

1. A laser irradiation apparatus for activating a semiconductor layer of a semiconductor device, comprising: a laser light source that generates laser light having a wavelength of 250 nm or more and 500 nm or less; a levitation unit that levitates the semiconductor substrate; a transport unit that holds an edge of the semiconductor substrate floating above the floating unit and transports the semiconductor substrate in a first direction; an optical system unit that guides the laser light to the semiconductor substrate; a drive stage that is disposed so as to protrude from the floating unit and that movably holds the optical system unit disposed on the floating unit; a driving mechanism that moves the optical system unit along the driving stage so as to change the relative irradiation position of the laser light with respect to the semiconductor substrate; Equipped with The laser irradiation device, wherein the drive mechanism moves the optical system unit in a second direction different from the first direction when viewed from above.

2. The semiconductor substrate is provided with a plurality of chip regions that become the semiconductor devices, the spot shape of the laser light on the semiconductor substrate is a rectangle having a longitudinal direction and a lateral direction, 2. The laser irradiation device according to claim 1, wherein the optical system unit shapes the laser light so that the size of the laser light in the longitudinal direction on the semiconductor substrate is larger than the size of the chip region.

3. 2. The laser irradiation device according to claim 1, wherein the optical system unit is provided with an optical scanner that scans the laser light.

4. A laser irradiation apparatus that irradiates a semiconductor substrate on which a plurality of chip regions are formed with laser light, a laser light source that generates laser light; a levitation unit that levitates the semiconductor substrate; a transport unit that holds an edge of the semiconductor substrate floating above the floating unit and transports the semiconductor substrate in a first direction; an optical system unit that guides the laser light to the semiconductor substrate so that the longitudinal size of the laser light on the semiconductor substrate is larger than the size of the chip region; a drive stage that is disposed so as to protrude from the floating unit and that movably holds the optical system unit disposed on the floating unit; a driving mechanism that moves the optical system unit along the driving stage so as to change the relative irradiation position of the laser light with respect to the semiconductor substrate, The laser irradiation device, wherein the drive mechanism moves the optical system unit in a second direction different from the longitudinal direction when viewed from above.

5. 5. The laser irradiation device according to claim 4, wherein a semiconductor chip is formed in the chip region.

6. 6. The laser irradiation device according to claim 4, wherein the laser light source generates laser light having a wavelength of 250 nm or more and 500 nm or less.

7. the laser light irradiated onto the semiconductor substrate is a pulsed laser light, 7. The laser irradiation device according to claim 1, wherein the irradiation time per one location on the semiconductor substrate is 100 μsec or less.

8. 8. The laser irradiation device according to claim 1, wherein the semiconductor substrate is held so that the semiconductor substrate is not fixed at the position where the laser light is irradiated.

9. 9. The laser irradiation device according to claim 1, wherein the intensity distribution of the laser light in any one direction on the semiconductor substrate is a flat-top distribution.

10. A laser irradiation device according to any one of claims 1 to 9, wherein the intensity distribution of the laser light on the semiconductor substrate is a flat-top distribution in a direction in which the irradiation position of the laser light changes and in an orthogonal direction perpendicular to the direction of change.

11. A laser irradiation device described in any one of claims 1 to 10, wherein the laser light source is a continuous-wave blue semiconductor laser light source.

12. A laser irradiation device described in any one of claims 1 to 11, wherein the laser light from the laser light source is incident on the optical system unit via an optical fiber.

13. 1. A laser irradiation method for activating a semiconductor layer of a semiconductor device, comprising: (A1) generating a laser beam having a wavelength of 250 nm or more and 500 nm or less; (A2) guiding the laser light to a semiconductor substrate by an optical system unit; (A3) changing the relative irradiation position of the laser light with respect to the semiconductor substrate; Levitating the semiconductor substrate by a levitation unit; a transport unit holding an edge of the semiconductor substrate floating on the floating unit and transporting the semiconductor substrate in a first direction; a drive stage disposed so as to protrude from the floating unit, movably holding the optical system unit disposed on the floating unit; a driving mechanism that moves the optical system unit disposed on the floating unit along the driving stage so that the optical system unit moves in a second direction different from the first direction when viewed from above; Laser irradiation method.

14. The semiconductor substrate is provided with a plurality of chip regions that become the semiconductor devices, the spot shape of the laser light on the semiconductor substrate is a rectangle having a longitudinal direction and a lateral direction, 14. The laser irradiation method according to claim 13, wherein the optical system unit shapes the laser light so that the size of the laser light in the longitudinal direction on the semiconductor substrate is larger than the size of the chip region.

15. The laser irradiation method according to claim 13, wherein the laser light is scanned by an optical scanner provided in the optical system unit.

16. A laser irradiation method for irradiating a semiconductor substrate on which a plurality of chip regions are formed with laser light, comprising: (B1) generating a laser beam; (B2) a step in which an optical system unit guides the laser light to the semiconductor substrate so that the longitudinal size of the laser light on the semiconductor substrate is larger than the size of the chip region; (B3) changing the relative irradiation position of the laser light with respect to the semiconductor substrate, Levitating the semiconductor substrate by a levitation unit; a transport unit holding an edge of the semiconductor substrate floating on the floating unit and transporting the semiconductor substrate in a first direction; a drive stage disposed so as to protrude from the floating unit, movably holding the optical system unit disposed on the floating unit; a driving mechanism that moves the optical system unit disposed on the floating unit along the driving stage so that the optical system unit moves in a second direction different from the longitudinal direction in a top view; Laser irradiation method.

17. The laser irradiation method according to claim 16, wherein a semiconductor chip is formed in the chip region.

18. 18. The laser irradiation method according to claim 16, wherein the wavelength of the laser light is 250 nm or more and 500 nm or less.

19. the laser light irradiated onto the semiconductor substrate is a pulsed laser light, 19. The laser irradiation method according to claim 13, wherein the irradiation time per one location on the semiconductor substrate is 100 μsec or less.

20. The laser irradiation method according to any one of claims 13 to 19, wherein the semiconductor substrate is held so that the semiconductor substrate is not fixed at the position irradiated with the laser light.

21. The laser irradiation method according to any one of claims 13 to 20, wherein the intensity distribution of the laser light in any one direction on the semiconductor substrate is a flat-top distribution.

22. The laser irradiation method according to any one of claims 13 to 21, wherein the intensity distribution of the laser light on the semiconductor substrate is a flat-top distribution in a direction in which the irradiation position of the laser light changes and in an orthogonal direction perpendicular to the direction of change.

23. A laser irradiation method according to any one of claims 13 to 22, wherein the laser light is generated by a continuous-wave blue semiconductor laser light source.

24. A laser irradiation method according to any one of claims 13 to 23, wherein the laser light from a laser light source is incident on the optical system unit via an optical fiber.

25. (S1) An irradiation step of irradiating a semiconductor substrate with laser light to activate a semiconductor layer of a power semiconductor device, The (S1) irradiation step includes: (SA1) generating a laser beam having a wavelength of 250 nm or more and 500 nm or less; (SA2) guiding the laser light to a semiconductor substrate by an optical system unit; (SA3) changing the relative irradiation position of the laser light with respect to the semiconductor substrate, Levitating the semiconductor substrate by a levitation unit; a transport unit holding an edge of the semiconductor substrate floating on the floating unit and transporting the semiconductor substrate in a first direction; a drive stage disposed so as to protrude from the floating unit, movably holding the optical system unit disposed on the floating unit; a driving mechanism that moves the optical system unit disposed on the floating unit along the driving stage so that the optical system unit moves in a second direction different from the first direction when viewed from above; A method for manufacturing semiconductor devices.

26. The semiconductor substrate is provided with a plurality of chip regions that become the semiconductor devices, the spot shape of the laser light on the semiconductor substrate is a rectangle having a longitudinal direction and a lateral direction, 26. The method for manufacturing a semiconductor device according to claim 25, wherein the optical system unit shapes the laser light so that the longitudinal size of the spot shape of the laser light on the semiconductor substrate is larger than the size of the chip region.

27. 27. The method for manufacturing a semiconductor device according to claim 25, wherein the laser light is scanned by an optical scanner provided in the optical system unit.

28. (T1) an irradiation step of irradiating a semiconductor substrate having a plurality of chip regions formed thereon with laser light; The (T1) irradiation step is (TB1) generating a laser beam; (TB2) a step in which an optical system unit guides the laser light to the semiconductor substrate so that the longitudinal size of the spot shape of the laser light on the semiconductor substrate becomes larger than the size of the chip region; (TB3) changing the relative irradiation position of the laser light with respect to the semiconductor substrate, Levitating the semiconductor substrate by a levitation unit; a transport unit holding an edge of the semiconductor substrate floating on the floating unit and transporting the semiconductor substrate in a first direction; a drive stage disposed so as to protrude from the floating unit, movably holding the optical system unit disposed on the floating unit; a driving mechanism that moves the optical system unit disposed on the floating unit along the driving stage so that the optical system unit moves in a second direction different from the longitudinal direction in a top view; A method for manufacturing semiconductor devices.

29. The method for manufacturing a semiconductor device according to claim 28, wherein a semiconductor chip is formed in the chip region.

30. 30. The method for manufacturing a semiconductor device according to claim 28 or 29, wherein the wavelength of the laser light is 250 nm or more and 500 nm or less.

31. the laser light irradiated onto the semiconductor substrate is a pulsed laser light, The method for manufacturing a semiconductor device according to any one of claims 25 to 30, wherein the irradiation time per location on the semiconductor substrate is 100 µsec or less.

32. The method for manufacturing a semiconductor device according to any one of claims 25 to 31, wherein the semiconductor substrate is held so that the semiconductor substrate is not fixed at the position irradiated with the laser light.

33. 33. The method for manufacturing a semiconductor device according to claim 25, wherein the intensity distribution of the laser light in any one direction on the semiconductor substrate is a top-flat distribution.

34. The method for manufacturing a semiconductor device according to any one of claims 25 to 33, wherein the intensity distribution of the laser light on the semiconductor substrate is a top-flat distribution in a direction in which the irradiation position of the laser light changes and in an orthogonal direction perpendicular to the direction of change.

35. A method for manufacturing a semiconductor device according to any one of claims 25 to 34, wherein the laser light is generated by a continuous wave blue semiconductor laser light source.

36. A method for manufacturing a semiconductor device described in any one of claims 25 to 35, wherein the laser light from a laser light source is incident on the optical system unit via an optical fiber.

Images