Laser annealing device, laser annealing method, and laser annealing program

Abstract

The laser annealing apparatus executes: a surface melting step in which a semiconductor wafer is irradiated with laser pulses (LP) oscillated by a pulse laser device, and the surface of the semiconductor wafer is heated to a melting point or higher by means of a plurality of laser pulses (LP) to melt the semiconductor wafer; and an activation step in which the semiconductor wafer continues to be irradiated with the laser pulses (LP) from the surface melting step, and the dopant added below the surface of the semiconductor wafer is activated by raising the temperature below the surface of the semiconductor wafer to a predetermined activation temperature or higher by means of the plurality of laser pulses (LP) and maintaining the temperature for at least a predetermined period of time. In the activation step, the temperature of a region up to 10 [mu] m below the surface of the semiconductor wafer is raised to 1000 DEG C or more and maintained for at least 10 [mu] s.

Description

Technical Field

[0001] The present invention relates to a laser annealing device and the like. Background Art

[0002] Patent Document 1 discloses a laser annealing technology for irradiating a semiconductor wafer with laser light oscillated by a laser device. In this technology, which aims to form an extremely shallow pn junction, the dopant added just below the surface of the semiconductor wafer is activated by irradiating the semiconductor wafer with a laser light intensity that does not melt the semiconductor wafer. In addition, the crystal damage of the semiconductor wafer is repaired by the subsequent "low-temperature rapid thermal annealing".

[0003] Previous technical literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application No. 2003-528462

[0006] Patent Document 2: Japanese Patent Application Publication No. 2013-258288 Summary of the invention

[0007] Technical issues to be solved by the invention

[0008] In laser annealing, unlike Patent Document 1, damage caused by ion implantation of dopants is usually repaired by melting the surface of the semiconductor wafer. Thus, laser annealing has two different functions: repairing damage by melting the surface of the semiconductor wafer and activating the dopants implanted into the semiconductor wafer. As disclosed in Patent Document 2, in order to effectively achieve surface melting and activation below the surface, multiple different types of lasers are required, and multiple different laser devices are usually required.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a laser annealing device or the like which can effectively achieve surface melting of a semiconductor wafer and activation of the area below the surface of the semiconductor wafer by a single pulse laser device.

[0010] Means for solving technical problems

[0011] In order to solve the above-mentioned problems, a laser annealing device in one embodiment of the present invention performs the following steps: a surface melting step, in which a semiconductor wafer is irradiated with laser pulses oscillated by a pulsed laser device, and the surface of the semiconductor wafer is heated to above the melting point by multiple laser pulses to melt it; and an activation step, in which the semiconductor wafer is continuously irradiated with laser pulses starting from the surface melting step, and the temperature below the surface of the semiconductor wafer is heated to above a specified activation temperature by multiple laser pulses and maintained for at least a specified time, thereby activating the dopant added to the surface below the semiconductor wafer.

[0012] In this embodiment, through the continuous surface melting step and activation step, a single pulse laser device continuously irradiates the semiconductor wafer with laser pulses, thereby simultaneously performing surface melting and activation below the surface. In the activation step, the laser pulses intermittently and continuously irradiate the surface of the semiconductor wafer melted in the surface melting step, but the surface of the semiconductor wafer can be prevented from becoming overheated during the activation step by heat dissipation from the surface during the non-pulse period when the laser pulses are not irradiated. In addition, the surface melting step and the activation step may overlap in time.

[0013] Another embodiment of the present invention is a laser annealing method. The method includes: a surface melting step, irradiating a semiconductor wafer with laser pulses oscillated by a pulsed laser device, and heating the surface of the semiconductor wafer to above the melting point by multiple laser pulses to melt the semiconductor wafer; and an activation step, continuing to irradiate the semiconductor wafer with laser pulses from the surface melting step, and heating the lower surface of the semiconductor wafer to above a predetermined activation temperature by multiple laser pulses and maintaining the temperature for at least a predetermined time, thereby activating the dopant added to the lower surface of the semiconductor wafer.

[0014] In addition, any combination of the above constituent elements or any form of converting these elements into methods, devices, systems, storage media, computer programs, etc. are also included in the present invention.

[0015] Effects of the Invention

[0016] According to the present invention, the surface melting of the semiconductor wafer and the activation below the surface of the semiconductor wafer can be effectively achieved by using a pulse laser device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a perspective view schematically showing the structure of a laser annealing apparatus.

[0018] Figure 2 The structure of the main part of the fiber laser device (ie, the optical fiber) and the principle of generating and amplifying laser pulses in the optical fiber are schematically shown in FIG.

[0019] Figure 3 Schematically showing the structure of a pulse laser device as a fiber laser device.

[0020] Figure 4 FIG. 2 schematically shows the temporal change in the surface temperature of a semiconductor wafer when irradiated with various laser beams. DETAILED DESCRIPTION

[0021] Hereinafter, the method for implementing the present invention (hereinafter, also referred to as an embodiment) is described in detail with reference to the accompanying drawings. In the following description and / or accompanying drawings, the same or equivalent constituent elements, parts and processes are marked with the same symbols, and repeated descriptions are omitted. In each of the accompanying drawings, in order to simplify the description, the scale and shape of each part are appropriately set, and unless otherwise specifically stated, they are not interpreted as limiting. The embodiments are examples and do not limit the scope of the present invention in any way. All the features or combinations thereof described in the embodiments are not necessarily the essence of the present invention.

[0022] Figure 1 1 is a perspective view schematically showing the structure of a laser annealing apparatus 1 according to an embodiment of the present invention. The laser annealing apparatus 1 is an apparatus for irradiating a semiconductor wafer 3 with laser pulses oscillated by a pulse laser apparatus 2 to perform an annealing process (heating process).

[0023] The semiconductor wafer 3 fixedly mounted on the wafer bed 31 can be moved integrally with the wafer bed 31 in the x direction in the figure through the workbench device 4 described later. In addition, the laser pulse (laser) oscillated by the pulse laser device 2 can be scanned in the y direction orthogonal to the x direction through the Galvano scanner 14 described later. The laser pulse (laser) scanned in the y direction by the Galvano scanner 14 is reflected by the reflector 16 described later and incident on the semiconductor wafer 3 in the z direction orthogonal to the x direction and the y direction.

[0024] Hereinafter, directions related to the structure and / or function of the laser annealing device 1 are described based on a three-dimensional orthogonal coordinate system using mutually orthogonal XYZ axes as coordinate axes. The driving direction of the semiconductor wafer 3 (i.e., the x direction) is parallel to the X-axis direction (X direction), the scanning direction of the laser pulse (laser) (i.e., the y direction) is parallel to the Y-axis direction (Y direction), and the incident direction of the laser pulse (laser) to the semiconductor wafer 3 (i.e., the z direction) is parallel to the Z-axis direction (Z direction). Hereinafter, for convenience, the x direction and the X direction are also referred to as the longitudinal direction, the y direction and the Y direction are also referred to as the lateral direction, and the z direction and the Z direction are also referred to as the height direction.

[0025] The pulse laser device 2 is a laser device that oscillates laser pulses at a frequency of 100kHz or more. In order to fully obtain the later-described functions and effects of the laser annealing device 1 involved in this embodiment, the frequency of the laser pulses oscillated by the pulse laser device 2 is, for example, between 100kHz and 10MHz, preferably between 500kHz and 5MHz, and more preferably between 700kHz and 3MHz. In this embodiment, an example in which the frequency of the laser pulses oscillated by the pulse laser device 2 is 800kHz is described.

[0026] The pulse laser device 2 according to the present embodiment is constituted by, for example, a fiber laser device that oscillates laser pulses using an optical fiber. Figure 2 Schematically shows the structure of the main part of the fiber laser device (i.e., the optical fiber 20) and the principle of generation and amplification of the laser pulse LP in the optical fiber 20. The optical fiber 20 includes a core 201 in the center, a first clad 202 provided around the core 201, and a second clad 203 provided around the first clad 202. The refractive index of the core 201 is higher than that of the first clad 202, and the refractive index of the first clad 202 is higher than that of the second clad 203. That is, the refractive index of the optical fiber 20 is higher as it approaches the center (core 201) and is lower as it approaches the peripheral portion (second clad 203).

[0027] The excitation light EL generated by a light emitting element such as a laser diode is emitted from one end of the optical fiber 20 (for example Figure 2 The excitation light EL is totally reflected by the boundary surface between the first cladding 202 and the second cladding 203 and propagates inside the core 201 and the first cladding 202. Each time the excitation light EL passes through the core 201, it excites the rare earth element such as Yb added to the core 201, thereby generating stimulated emission light that becomes the source of the laser pulse LP (laser). The stimulated emission light generated in the core 201 is totally reflected by the boundary surface between the core 201 and the first cladding 202 and propagates inside the core 201. As described later, total reflection mirrors such as FBG (Fiber Bragg Grating) or output mirrors are formed at both ends of the core 201, and the stimulated emission light repeatedly reflected between these reflectors is amplified while traveling back and forth inside the core 201, thereby forming a laser pulse LP (laser). The laser pulse LP is emitted from a portion of the core 201 formed at one end (e.g. Figure 2 The output mirror (at the right end in FIG. 1 ) outputs the optical fiber 20 to the outside.

[0028] Figure 3 The diagram schematically shows a method for Figure 2 The structure of the pulse laser device 2 of the optical fiber laser device of the optical fiber 20 shown in the figure. The pulse laser device 2 includes an excitation light supply unit 21, a laser generating unit 22, and a laser supply unit 23. The excitation light supply unit 21 includes a light emitting element 211 such as one or more laser diodes that emit light that becomes a source of excitation light EL, and an optical coupling unit 212 that couples the respective lights to form the excitation light EL when a plurality of light emitting elements 211 are provided. The excitation light supply unit 21 supplies the excitation light EL generated by the light emitted by the light emitting element 211 to the laser generating unit 22.

[0029] The laser generating unit 22 has an input terminal ( Figure 3The optical fiber 20 for receiving the excitation light EL (left end in FIG. 1 ) and the input mirror 221 and the output mirror 222 formed at both ends thereof. The input mirror 221 and the output mirror 222 are both formed of FBG, for example, and are formed at both ends of the core 201. Preferably, the reflectivity of the input mirror 221 provided on the input side (excitation light supply unit 21 side) is higher than the reflectivity of the output mirror 222 provided on the output side (laser supply unit 23 side). In particular, the input mirror 221 is preferably configured as a total reflection mirror that totally reflects the stimulated emission light inside the core 201, which will be the source of the laser pulse LP (laser), to the output side. The output mirror 222 reflects a portion of the stimulated emission light inside the core 201 to the input side, and outputs the remaining portion to the laser supply unit 23.

[0030] The laser supply unit 23 includes an optical fiber 231 for introducing the laser pulse LP (laser light) generated by the laser generation unit 22 to the output point OP of the pulse laser device 2. Alternatively, the output point of the laser generation unit 22 may be used as the output point OP of the pulse laser device 2, in which case the laser supply unit 23 is not required.

[0031] exist Figure 1 , the laser pulse LP is emitted in the X direction from the output point OP of the pulse laser device 2. The laser annealing device 1 for introducing the laser pulse LP into the semiconductor wafer 3 to be irradiated includes a beam expander 11, a reflector 12, a beam shaping optical element 13, a Galvano scanner 14, an fθ lens 15, and a reflector 16.

[0032] The beam expander 11 adjusts the laser pulse LP (laser) emitted from the output point OP of the pulse laser device 2 to a specified size (diameter). For example, when the cross section of the laser pulse LP (laser) emitted from the output point OP of the pulse laser device 2 is a roughly circular shape with a diameter D0, the beam expander 11 converts the cross section of the laser pulse LP (laser) into a roughly circular shape with a specified diameter D1 (usually enlarged). The beam expander 11 is composed of a plurality of lenses 111, 112, and 113. Usually, the lens 111 is a convex lens, the lens 112 is a concave lens, and the lens 113 is a convex lens. However, as long as the intended function and / or effect of adjusting the size of the laser pulse LP can be obtained, the number or type of lenses and other optical elements constituting the beam expander 11 is arbitrary. For example, the beam expander 11 may also be composed of two or more convex lenses and one or more concave lenses arranged in any order, or may be composed of only three or more convex lenses.

[0033] The reflecting mirror 12 reflects the laser pulse LP whose size has been adjusted by the beam expander 11 , and changes its traveling direction from the X direction to the Y direction.

[0034] The beam shaping optical element 13 shapes the laser pulse LP whose size is adjusted by the beam expander 11 to adjust its shape and / or intensity distribution. For example, the cross section of the laser pulse LP whose size is adjusted by the beam expander 11 has an approximately circular shape and an intensity distribution following a Gaussian distribution or a normal distribution, but is shaped into an approximately rectangular shape and an approximately uniform intensity distribution by the beam shaping optical element 13. Such a beam shaping optical element 13 is constituted by, for example, a diffractive optical element (DOE: Diffractive Optical Element).

[0035] The Galvano scanner 14 is a laser pulse scanning unit that scans the laser pulse LP shaped by the beam shaping optical element 13 in the y direction (Y direction). The Galvano scanner 14 includes a Galvano mirror 141 that can reflect the laser pulse LP and a motor 142 that drives the Galvano mirror 141 to rotate around the Z axis. By adjusting the rotation position or rotation angle of the Galvano mirror 141 around the Z axis by the motor 142, the laser pulse LP incident on the Galvano mirror 141 is reflected to an arbitrary y direction position.

[0036] In addition, the laser pulse scanning unit that scans the laser pulse LP along the y direction is not limited to the Galvano scanner 14, and may be composed of a polygonal mirror scanner or a MEMS (MicroElectro Mechanical Systems) mirror that has a polygonal mirror that can be driven to rotate. In addition, the scanning direction of the laser pulse LP based on the laser pulse scanning unit such as the Galvano scanner 14 is not limited to the y direction (Y direction), and may be a direction that intersects the y direction (Y direction) such as the x direction (X direction), or may be both the x direction (X direction) and the y direction (Y direction). In the case where the laser pulse scanning unit such as the Galvano scanner 14 can scan the laser pulse LP in the xy plane (in the XY plane) (that is, in the surface of the semiconductor wafer 3) as in the latter case, the workbench device 4 that drives the semiconductor wafer 3 and the wafer bed 31 to move along the x direction (X direction) may not be provided.

[0037] The fθ lens 15 focuses the laser pulse LP scanned along the y direction (Y direction) by the Galvano scanner 14 onto the semiconductor wafer 3 to be annealed. The reflector 16 disposed between the fθ lens 15 and the semiconductor wafer 3 reflects the laser pulse LP in the X direction from the fθ lens 15 so that it is irradiated onto the semiconductor wafer 3 along the Z direction (z direction). The laser pulse LP focused onto the semiconductor wafer 3 by the fθ lens 15 and the reflector 16 moves along the Y direction within the surface of the semiconductor wafer 3 by scanning in the y direction by the Galvano scanner 14. The size of the laser pulse LP focused onto the semiconductor wafer 3 can be arbitrarily designed, but is preferably set to between 0.10 mm square and 0.15 mm square, and more preferably between 0.12 mm square and 0.13 mm square. Furthermore, the scanning speed in the Y direction of the laser pulse LP on the surface of the semiconductor wafer 3 (and / or the driving speed in the X direction of the semiconductor wafer 3 based on the workbench device 4) can also be designed arbitrarily, but for example, it is preferably set to between 100 cm / s and 500 cm / s, and further preferably set to between 250 cm / s and 350 cm / s.

[0038] Furthermore, by using the workbench device 4 to drive the semiconductor wafer 3 and the wafer bed 31 to move along the x direction (X direction), the laser pulse LP moves relatively along the X direction within the surface of the semiconductor wafer 3. In this way, by combining the scanning of the laser pulse LP in the y direction based on the Galvano scanner 14 and the movement of the semiconductor wafer 3 in the x direction based on the workbench device 4, the laser pulse LP can be scanned in the xy plane (in the XY plane) (that is, in the surface of the semiconductor wafer 3). In addition, the moving direction of the semiconductor wafer 3 based on the workbench device 4 is not limited to the x direction (X direction), but can also be a direction intersecting with the x direction (X direction) such as the y direction (Y direction), and can also be two directions of the x direction (X direction) and the y direction (Y direction). In the case where the workbench device 4 can drive the semiconductor wafer 3 to move relatively with respect to the laser pulse LP in the xy plane (in the XY plane) as in the latter case, a laser pulse scanning unit such as the Galvano scanner 14 that scans the laser pulse LP along the y direction (Y direction) etc. can be omitted.

[0039] Figure 4The figure shows the time-dependent change of the surface temperature of the semiconductor wafer 3 when irradiated with various lasers. The solid line represents the surface temperature when irradiated with a high-frequency (800kHz in the example in the figure) laser pulse LP oscillated by a fiber laser device, which is the pulse laser device 2 involved in this embodiment. The dotted line represents the surface temperature when irradiated with a laser pulse of high peak power (usually hundreds of kW) and low frequency (usually between 2kHz and tens of kHz) oscillated by a conventional pulse oscillation laser device. The single-point dashed line represents the surface temperature when irradiated with a low peak power (usually several kW) and low frequency laser oscillated by a conventional diode laser device. In addition, peak power refers to the value obtained by dividing the pulse energy by the pulse width.

[0040] The high peak power and low frequency laser pulse oscillated by the conventional pulse oscillation laser device represented by the dotted line is used for the following purpose: to repair the damage caused by the ion implantation of the dopant by melting the surface of the semiconductor wafer 3. In the case where the semiconductor wafer 3 is formed of ordinary silicon, its surface is melted by heating it to above its melting point (1410°C). In the example in the figure, the surface temperature of the semiconductor wafer 3 instantly rises to above 1500°C by the high peak power laser pulse oscillated by the conventional pulse oscillation laser device represented by the dotted line, so that the surface of the semiconductor wafer 3 formed of silicon with a melting point of 1410°C is melted and the damage is repaired. However, since the conventional laser pulse is of low frequency, the surface temperature of the semiconductor wafer 3 will drop sharply immediately after the laser pulse irradiation. Therefore, the inside or below the surface of the semiconductor wafer 3 injected with the dopant will not be sufficiently heated, and the dopant will not be activated.

[0041] Therefore, for the purpose of activating the dopant injected into the semiconductor wafer 3, a low peak power and low frequency laser oscillated by a conventional diode laser device represented by a single dot-dashed line is used. This laser has a low peak power, so it cannot heat the surface of the semiconductor wafer 3 above the melting point, but it can continuously heat the inside of the semiconductor wafer 3 or below the surface, thereby activating the injected dopant. Thus, usually, in order to melt the surface of the semiconductor wafer 3, a pulsed oscillation laser device (dashed line) is used, and in order to activate below the surface of the semiconductor wafer 3, a diode laser device (single dot-dashed line) is used. Different laser devices need to be prepared for annealing for different purposes, which will lead to large-scale or high-cost laser annealing devices.

[0042] In contrast, according to the high-frequency laser pulses LP involved in the present embodiment represented by the solid line, the surface melting of the semiconductor wafer 3 and the activation of the lower surface of the semiconductor wafer 3 can be effectively achieved by one pulse laser device 2 (fiber laser device, etc.). Specifically, the pulse laser device 2 involved in the present embodiment performs the following steps: a surface melting step (during the "surface melting" period in the figure), in which the surface of the semiconductor wafer 3 is heated to above the melting point by a plurality of laser pulses LP to melt it; and an activation step (during the "activation" period in the figure), in which the laser pulses LP are continuously irradiated to the semiconductor wafer 3 from the surface melting step, and the lower surface of the semiconductor wafer 3 is heated to above a predetermined activation temperature by a plurality of laser pulses LP and maintained for at least a predetermined time, thereby activating the dopant added to the lower surface of the semiconductor wafer 3.

[0043] In the surface melting step, the surface temperature of the semiconductor wafer 3 rises to above the melting point (1410°C) by intermittently irradiating multiple laser pulses LP at a high frequency (800kHz in the example in the figure). Therefore, the surface of the semiconductor wafer 3 is melted, and damage caused by ion implantation of dopants, etc. is repaired. In addition, as shown in the figure, although each laser pulse LP does not have sufficient power to heat the surface of the semiconductor wafer 3 to above the melting point, heat is accumulated on the semiconductor wafer 3 by irradiating at a high frequency, and as a result, its surface temperature rises to above the melting point. The surface melting step starts at the moment when the surface temperature of the semiconductor wafer 3 rises to above the melting point, and ends at the moment when the surface temperature of the semiconductor wafer 3 drops below the melting point.

[0044] As described above, the laser pulse LP is scanned along the Y direction (y direction) on the semiconductor wafer 3 by the Galvano scanner 14 as the laser pulse scanning section, but the time required for the laser pulse LP having a width along the Y direction to pass through a point on the semiconductor wafer 3 is substantially the same as the time of the surface melting step. Strictly speaking, there is a slight time difference because there is a time from when the laser pulse LP starts to contact a feature on the semiconductor wafer 3 until the surface temperature reaches the melting point and a time from when the laser pulse LP passes through a point on the semiconductor wafer 3 until the surface temperature drops below the melting point.

[0045] In the activation step, by continuously irradiating the semiconductor wafer 3 with laser pulses LP from the surface melting step, the temperature of the inside or below the surface of the semiconductor wafer 3 injected with dopants is raised to a predetermined activation temperature or above, and the dopant is activated. The activation temperature may vary depending on the type of dopant or the material of the semiconductor wafer 3 (silicon, silicon carbide, gallium nitride, etc.), but the most common silicon semiconductor wafer 3 injected with boron and other acceptors (P-type dopants) is generally about 1000°C. In addition, in order to fully activate the dopant added to the inside or below the surface of the semiconductor wafer 3, it is necessary to maintain the temperature of the area above the activation temperature for a predetermined time. The predetermined time may vary depending on the type or amount of the dopant and the material of the semiconductor wafer 3, but is generally about 10μs. In this way, in the activation step, the usual goal is to raise the temperature of the inside or below the surface of the semiconductor wafer 3 injected with dopants (usually the area up to 10μm below the surface of the semiconductor wafer 3) to above 1000°C and maintain it for at least 10μs.

[0046] The activation step starts when the temperature of the activation region below the surface of the semiconductor wafer 3 into which the dopant is injected rises to above the activation temperature, and ends when the temperature of the activation region drops below the activation temperature. Figure 4 It does not represent the temperature of the activation zone below the surface, so the start time and end time of the activation step represent approximate values. Usually, as shown in the figure, the activation step is shorter than the surface melting step. And, the start time of the activation step is usually later than the start time of the surface melting step. Moreover, the end time of the activation step is substantially the same as the end time of the surface melting step. However, strictly speaking, the temperature of the activation zone in the semiconductor wafer 3 involved in the activation step is not easy to drop than the temperature of the surface of the semiconductor wafer 3 involved in the surface melting step, so it can be considered that the end time of the activation step (the activation zone is cooled to below the activation temperature) is slightly later than the end time of the surface melting step (the surface is cooled to below the melting point).

[0047] In addition, when the amount of doping added to the activation region is greater than usual or when the activation region is deeper than 10 μm, the activation step can be set to be longer than 10 μs. Specifically, the activation step can be extended by slowing down the scanning speed in the Y direction (y direction) of the laser pulse LP based on the Galvano scanner 14 as the laser pulse scanning unit. Alternatively, the same effect can be obtained by setting the oscillation frequency of the laser pulse LP based on the pulse laser device 2 to be higher than 800 kHz. If the activation step is extended, the surface melting step will inevitably be extended, but the surface of the semiconductor wafer 3 can be prevented from becoming overheated by heat dissipation from the surface of the semiconductor wafer 3 during the non-pulse period when the intermittent laser pulse LP is not irradiated, etc. (in the example in the figure, the surface temperature is controlled to be below 2000°C). In this way, according to this embodiment, the surface melting step can be well performed without relying on the length of the activation step.

[0048] According to the present embodiment, by continuously performing the surface melting step and the activation step, the semiconductor wafer 3 is continuously irradiated with laser pulses LP by one pulse laser device 2 , thereby simultaneously performing surface melting and activation below the surface.

[0049] The present invention has been described above based on the embodiments. It is obvious to those skilled in the art that various modifications may be made to the combinations of the constituent elements or processes in the exemplified embodiments, and such modifications are also included in the scope of the present invention.

[0050] In addition, the structure, function and function of each device or method described in the embodiment can be realized by hardware resources or software resources, or the cooperation of hardware resources and software resources. As hardware resources, for example, a processor, ROM, RAM, and various integrated circuits can be used. As software resources, for example, programs such as an operating system and an application program can be used.

[0051] Industrial Applicability

[0052] The present invention relates to a laser annealing device and the like.

[0053] Explanation of symbols

[0054] 1-laser annealing device, 2-pulse laser device, 3-semiconductor wafer, 4-workbench device, 11-beam expander, 13-beam shaping optical element, 14-Galvano scanner, 20-optical fiber, 22-laser generating unit, LP-laser pulse.

Claims

1. A laser annealing device, characterized in that: Follow these steps: a surface melting step of irradiating the semiconductor wafer with laser pulses oscillated by a pulsed laser device, and heating the surface of the semiconductor wafer to above the melting point by a plurality of the laser pulses to melt the semiconductor wafer; and An activation step, starting from the surface melting step, continues to irradiate the semiconductor wafer with the laser pulses, and through multiple laser pulses, the temperature below the surface of the semiconductor wafer is raised to above a specified activation temperature and maintained for at least a specified time, thereby activating the dopant added below the surface of the semiconductor wafer.

2. The laser annealing device according to claim 1, characterized in that: The pulse laser device oscillates the laser pulses at a frequency of 100 kHz or more.

3. The laser annealing device according to claim 1, characterized in that: The pulse laser device is a fiber laser device that oscillates the laser pulses through an optical fiber.

4. The laser annealing device according to any one of claims 1 to 3, characterized in that: In the activation step, the temperature of a region 10 μm below the surface of the semiconductor wafer is raised to 1000° C. or higher and maintained at that temperature for at least 10 μs.

5. A laser annealing method, characterized in that: The steps include: a surface melting step of irradiating the semiconductor wafer with laser pulses oscillated by a pulsed laser device, and heating the surface of the semiconductor wafer to above the melting point by a plurality of the laser pulses to melt the semiconductor wafer; and An activation step, starting from the surface melting step, continues to irradiate the semiconductor wafer with the laser pulses, and through multiple laser pulses, the temperature below the surface of the semiconductor wafer is raised to above a specified activation temperature and maintained for at least a specified time, thereby activating the dopant added below the surface of the semiconductor wafer.

6. A laser annealing program, which causes a computer to execute the following steps: a surface melting step of irradiating the semiconductor wafer with laser pulses oscillated by a pulsed laser device, and heating the surface of the semiconductor wafer to above the melting point by a plurality of the laser pulses to melt the semiconductor wafer; and An activation step, starting from the surface melting step, continues to irradiate the semiconductor wafer with the laser pulses, and through multiple laser pulses, the temperature below the surface of the semiconductor wafer is raised to above a specified activation temperature and maintained for at least a specified time, thereby activating the dopant added below the surface of the semiconductor wafer.

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