Laser annealing apparatus, laser annealing method, and storage medium

Abstract

To provide a laser annealing apparatus and the like capable of reducing variations in quality of annealing processing across a laser irradiation region.SOLUTION: A laser annealing apparatus that emits laser pulses LP to irradiation regions 3A, 3B on a semiconductor wafer 3 for annealing processing includes: a laser scanning unit 6 that scans the laser pulses LP across the irradiation regions 3A, 3B; and an irradiation interval adjustment unit 62 that sets an interval between adjacent irradiation positions of the laser pulses LP on peripheral parts of the irradiation regions 3A, 3B to be smaller than the interval between adjacent irradiation positions of the laser pulses LP on non-peripheral parts of the irradiation regions 3A, 3B. The laser annealing apparatus further includes an irradiation region overlap control unit 63 that emits the laser pulses LP to a first irradiation region 3A and a second irradiation region 3B which are adjacent to each other, and makes the peripheral part of the first irradiation region 3A overlap with the peripheral part of the second irradiation region 3B at boundaries of the first irradiation region 3A and the second irradiation region 3B.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a laser annealing apparatus and the like. [Background technology]

[0002] Patent Document 1 discloses a laser annealing device that performs annealing by sequentially irradiating an irradiation area of ​​a workpiece such as a semiconductor wafer with laser pulses. The laser pulses are two-dimensionally scanned over the entire irradiation area by an appropriate laser scanning mechanism.

[0003] The main purpose of the annealing process is to activate dopants implanted in a semiconductor wafer. Activation at any point in the irradiated region may be affected not only by the laser pulse irradiated at that point, but also by the laser pulse irradiated at an adjacent point. For example, the heat from the laser pulse irradiated at a certain point may be transmitted to an adjacent point, promoting the activation of dopants at the adjacent point. Laser annealing may also be performed on semiconductor wafers made of silicon carbide (SiC) to make them ohmic. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-67642 A Summary of the Invention [Problem to be solved by the invention]

[0005] When the influence from such adjacent positions cannot be ignored, the degree of temperature rise may differ between the peripheral and non-peripheral parts of the irradiation area. For example, in the non-peripheral part (e.g., the center part of the semiconductor wafer), the laser pulse is irradiated to all adjacent positions around any position irradiated with the laser pulse (i.e., the entire circumference of each irradiation position is surrounded by other irradiation positions), whereas in the peripheral part, the laser pulse is not irradiated to some of the adjacent positions around the positions on the edge of the irradiation area or the positions inscribed in the edge (i.e., some of the adjacent positions are outside the irradiation area). In this way, the influence from the adjacent positions is weak in the peripheral part of the irradiation area (or heat escapes to the adjacent positions not irradiated with the laser pulse), so the degree of temperature rise is small, while the influence from the adjacent positions is strong in the non-peripheral part of the irradiation area, so the degree of temperature rise may be large. This means that the quality of the annealing process may vary across the irradiation area.

[0006] The present disclosure has been made in consideration of these circumstances, and aims to provide a laser annealing apparatus and the like that can reduce variation in the quality of the annealing process across a laser irradiation area. [Means for solving the problem]

[0007] In order to solve the above problems, a laser annealing device according to one aspect of the present disclosure is a laser annealing device that irradiates a laser onto an irradiation area on a workpiece for annealing processing, and includes a laser scanning unit that scans the laser across the irradiation area, and an irradiation interval adjustment unit that makes the interval between adjacent irradiation positions of the laser on the periphery of the irradiation area smaller than the interval between adjacent irradiation positions of the laser on the non-periphery of the irradiation area.

[0008] In this embodiment, the interval between the laser irradiation positions in the peripheral portion of the irradiation region is set smaller than the interval between the laser irradiation positions in the non-peripheral portion of the irradiation region. In this manner, in the peripheral portion where the interval between the laser irradiation positions is small, the influence of the adjacent positions close to each other on the annealing process is strengthened, and the above-mentioned problem that the degree of the annealing process is low in the peripheral portion can be effectively solved.

[0009] Another aspect of the present disclosure is also a laser annealing apparatus that irradiates a laser onto an irradiation region on a workpiece for annealing, and includes a laser scanning unit that scans the laser across a first irradiation region and a second irradiation region adjacent to each other as the irradiation region, and an irradiation region overlap control unit that overlaps a peripheral portion of the first irradiation region and a peripheral portion of the second irradiation region at a boundary between the first irradiation region and the second irradiation region.

[0010] According to this aspect, in a laser annealing apparatus that irradiates a laser onto each of a plurality of irradiation regions, the peripheral portions of each irradiation region, where the degree of annealing tends to be low, are overlapped, thereby reducing the variation in the quality of the annealing across the plurality of irradiation regions.

[0011] Yet another aspect of the present disclosure is a laser annealing method for irradiating a laser onto an irradiation region of a workpiece for annealing, the method including scanning the laser over the irradiation region and making a distance between adjacent irradiation positions of the laser on a peripheral portion of the irradiation region smaller than a distance between adjacent irradiation positions of the laser on a non-peripheral portion of the irradiation region.

[0012] Yet another aspect of the present disclosure is a storage medium that stores a laser annealing program for irradiating an irradiation area of ​​a workpiece with a laser for annealing, the laser annealing program causing a computer to execute the following steps: scanning the irradiation area with the laser; and making a distance between adjacent irradiation positions of the laser in a peripheral portion of the irradiation area smaller than a distance between adjacent irradiation positions of the laser in a non-peripheral portion of the irradiation area.

[0013] Any combination of the above components, or any conversion of these components into a method, device, system, recording medium, computer program, or the like, is also encompassed by the present disclosure. Effect of the Invention

[0014] According to the present disclosure, it is possible to reduce the variation in the quality of the annealing process across the laser irradiation area. [Brief description of the drawings]

[0015] [Figure 1] 1 shows a schematic configuration of a laser annealing apparatus. [Diagram 2] FIG. 2 is a schematic functional block diagram of a laser scanning control unit and the like. [Diagram 3] 2 shows a schematic diagram of four irradiation areas set on the surface of a semiconductor wafer. [Figure 4] 3A and 3B are schematic diagrams illustrating examples of a first scan and a second scan of a laser pulse by a laser scanning unit. [Diagram 5] 4A to 4C are schematic diagrams illustrating an example of adjustment of the irradiation interval of laser pulses by an irradiation interval adjustment unit. [Figure 6] 4A to 4C are schematic diagrams illustrating an example of adjustment of the irradiation interval of laser pulses by an irradiation interval adjustment unit. [Figure 7] 13A and 13B show schematic diagrams of a first irradiation area and a second irradiation area overlapping under the control of an irradiation area overlap control unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] In the following, a form for carrying out the present disclosure (hereinafter also referred to as an embodiment) will be described in detail with reference to the drawings. In the description and / or drawings, identical or equivalent components, members, processes, etc. will be given the same reference numerals, and duplicated descriptions will be omitted. The scale and shape of each part shown in the drawings are set for convenience in order to simplify the description, and are not to be interpreted as being limiting unless otherwise specified. The embodiment is an example, and does not limit the scope of the present disclosure in any way. All features and their combinations presented in the embodiment are not necessarily essential to the present disclosure. The embodiment is presented for convenience, decomposed into components for each function and / or each functional group that realizes it. However, one component in the embodiment may actually be realized by a combination of multiple components as separate entities, and multiple components in the embodiment may actually be realized by one component as an integrated entity.

[0017] 1 is a schematic diagram showing the configuration of a laser annealing apparatus 1 according to an embodiment of the present disclosure. The laser annealing apparatus 1 is an apparatus that performs an annealing process (heating process) by irradiating a laser (e.g., a laser pulse LP) oscillated by a laser device 2 to a semiconductor wafer 3 (placed on a wafer table 31 fixed to a stage device 4 described later) as an object to be processed. The laser annealing apparatus 1 in the illustrated example is significantly simplified from an actual one, and many components that are not mentioned in the description of this embodiment (e.g., components for measuring the laser and the semiconductor wafer 3, components for transporting the semiconductor wafer 3, and components for stopping the laser irradiation in an emergency) are omitted.

[0018] In addition, the illustrated configuration is merely an example, and the present disclosure may be applied to a laser annealing device of any other configuration. For example, in the illustrated example, the control system is composed of a laser control unit 51, a trigger pulse control unit 52, a personal computer (PC) 53, a scanner control unit 54, a stage control unit 55, etc., but as long as the laser annealing device 1 and the laser device 2 can appropriately perform an annealing process on the semiconductor wafer 3, a control system of any other configuration may be provided. In the illustrated example, an energy adjustment mechanism 11, a transmission optical system 12, a mask 13, an irradiation optical system 14, a galvano scanner 15, an fθ lens 16, etc. are provided along the laser path, but as long as the laser from the laser device 2 is appropriately irradiated on the semiconductor wafer 3, any other components may be provided between the laser device 2 and the semiconductor wafer 3, and the arrangement of these components is also arbitrary.

[0019] In the following, directions related to the configuration and / or operation of the laser annealing apparatus 1 will be described based on a three-dimensional orthogonal coordinate system with mutually orthogonal XYZ axes as coordinate axes. In the following, for convenience, it is assumed that the X and Y directions are horizontal directions (i.e., the XY plane is a horizontal plane) and the Z direction is a vertical direction. As will be described later, the semiconductor wafer 3 is driven relatively to the laser from the laser apparatus 2 within the XY plane under the control of the scanner control unit 54 and / or the stage control unit 55.

[0020] For example, the semiconductor wafer 3 is driven in the X direction together with the moving table 41 in the stage device 4 driven in the X direction by the stage control unit 55 (the X direction in this case is also referred to as the driving direction), and the laser from the laser device 2 is scanned in the Y direction by the galvano scanner 15 controlled by the scanner control unit 54 (the Y direction in this case is also referred to as the scanning direction). The semiconductor wafer 3 is driven in the Z direction together with the lift table 42 in the stage device 4 driven in the Z direction by the stage control unit 55 (the Z direction in this case is also referred to as the lift direction). This Z direction is also the incident direction in which the laser is incident on the semiconductor wafer 3. Hereinafter, for convenience, the X direction is also referred to as the vertical direction, the Y direction is also referred to as the horizontal direction, and the Z direction is also referred to as the height direction.

[0021] The laser device 2 is a pulse laser device that oscillates a laser pulse LP at a frequency of, for example, 100 kHz or more under the control of the laser control unit 51. In order to fully obtain the action and effect of the laser annealing device 1 according to this embodiment, the frequency of the laser pulse LP oscillated by the laser device 2 is, for example, between 100 kHz and 10 MHz, preferably between 500 kHz and 5 MHz, and more preferably between 700 kHz and 3 MHz. In the example of this embodiment, unless otherwise specified, the frequency of the laser pulse LP oscillated by the laser device 2 is 1 MHz. The laser device 2 according to this embodiment may be configured, for example, by a fiber laser device that oscillates a laser pulse LP by an optical fiber.

[0022] A laser pulse LP is emitted, for example, in the X direction from a laser device 2. In a laser annealing device 1 that guides this laser pulse LP to a semiconductor wafer 3 that is an irradiation target (workpiece), an energy adjustment mechanism 11, a transmission optical system 12, a mask 13, an irradiation optical system 14, a galvano scanner 15, and an fθ lens 16 are provided in this order along a path of the laser pulse LP (schematically shown by a dashed dotted line).

[0023] The energy adjustment mechanism 11 adjusts the energy and energy density of the laser pulse LP emitted from the laser device 2 to values ​​suitable for the desired annealing process.

[0024] The transmission optical system 12 is an optical system that transmits the laser pulse LP. The transmission optical system 12 is composed of any optical elements such as lenses, mirrors, prisms, filters, and diffraction gratings, and may be responsible not only for transmitting the laser pulse LP, but also for adjusting the size (diameter) of the laser pulse LP, shaping the laser pulse LP, and adjusting the intensity distribution of the laser pulse LP. The adjustment of the size (diameter) of the laser pulse LP and the shaping of the laser pulse LP may be performed by a mask 13 having a size (diameter) and / or shape suitable for the intended annealing process. The irradiation optical system 14 is composed of any optical elements such as lenses, mirrors, prisms, filters, and diffraction gratings, and adjusts the laser pulse LP to a mode (e.g., size (diameter), shape, intensity distribution) suitable for irradiation of the semiconductor wafer 3.

[0025] The galvanometer scanner 15 is a laser scanning unit that scans the laser pulse LP adjusted by the irradiation optical system 14 and the like along the Y direction. The galvanometer scanner 15 includes a galvanometer mirror 151 as a drivable optical element that reflects the incident laser pulse LP and directs it to a desired scanning position in the Y direction, and a motor (not shown) that drives the galvanometer mirror 151 to a desired attitude or angle. The attitude or angle of the galvanometer mirror 151 is adjusted by the motor, so that the laser pulse LP incident on the galvanometer mirror 151 is reflected to a desired position in the Y direction.

[0026] The laser scanning unit that directs the incident laser pulse LP to a desired scanning position in the Y direction is not limited to the galvano scanner 15, but may be configured with optical elements such as a polygon mirror scanner having a rotatable polygon mirror (optical element) or a drivable MEMS (Micro Electro Mechanical Systems) mirror. The scanning direction of the laser pulse LP by the laser scanning unit such as the galvano scanner 15 is also not limited to the Y direction, but may be a direction intersecting the Y direction such as the X direction, or may be two directions, the X direction and the Y direction. As in the latter case, when the laser scanning unit such as the galvano scanner 15 can scan the laser pulse LP over the XY plane, i.e., the surface of the semiconductor wafer 3, it is not necessary to provide a stage device 4 (moving table 41) that drives the semiconductor wafer 3 and the wafer table 31 in the X direction or the like. In this case, the galvano scanner 15 and the like configure a laser scanning unit in two directions, the X direction and the Y direction.

[0027] The fθ lens 16 focuses the laser pulse LP scanned in the Y direction by the galvano scanner 15 on the semiconductor wafer 3 to be annealed. The laser pulse LP from the fθ lens 16 is incident on the semiconductor wafer 3 in the Z direction. The laser pulse LP focused on the semiconductor wafer 3 by the fθ lens 16 in this way moves in the Y direction on the surface of the semiconductor wafer 3 by scanning in the Y direction by the galvano scanner 15. The size of the laser pulse LP focused on the semiconductor wafer 3 can be designed arbitrarily, but is preferably between 0.10 mm square and 0.15 mm square, for example, and more preferably between 0.12 mm square and 0.13 mm square. In addition, the scanning speed of the laser pulse LP in the Y direction on the surface of the semiconductor wafer 3 (and / or the driving speed of the semiconductor wafer 3 in the X direction by the stage device 4 (moving table 41)) can also be designed arbitrarily, but is preferably between 100 cm / s and 500 cm / s, for example, and more preferably between 250 cm / s and 350 cm / s.

[0028] The moving table 41 in the stage device 4 is a driving device that drives the semiconductor wafer 3 and the wafer table 31 relative to the laser pulse LP in the X direction. The moving table 41 moves the laser pulse LP relatively in the X direction on the surface of the semiconductor wafer 3.

[0029] As described above, by combining scanning of the laser pulse LP in the Y direction by the galvano scanner 15 as a Y direction laser scanning unit and driving of the semiconductor wafer 3 in the X direction by the moving table 41 as an X direction laser scanning unit, the laser pulse LP can be scanned over the XY plane, i.e., the surface of the semiconductor wafer 3. The driving direction of the semiconductor wafer 3 by the moving table 41 is not limited to the X direction, but may be a direction intersecting the X direction such as the Y direction, or may be two directions, the X direction and the Y direction. As in the latter case, when the moving table 41 can drive the semiconductor wafer 3 relatively to the laser pulse LP over the XY plane, the galvano scanner 15 for scanning the laser pulse LP in the Y direction or the like may not be provided. In this case, the moving table 41 constitutes a laser scanning unit in two directions, the X direction and the Y direction.

[0030] The laser annealing apparatus 1 and the laser apparatus 2 as described above are controlled by a control system including a laser control unit 51, a trigger pulse control unit 52, a personal computer 53, a scanner control unit 54, and a stage control unit 55.

[0031] The laser control unit 51 controls the laser pulse LP oscillated by the laser device 2 based on various control parameters. Examples of the control parameters include the energy of the laser pulse LP, the energy density of the laser pulse LP, the repetition frequency of the laser pulse LP, the duration (pulse width) of the laser pulse LP, the peak intensity of the laser pulse LP, the profile (e.g., intensity distribution) of the laser pulse LP, the delay time (time difference) when the laser pulse LP is irradiated to the same place by a plurality of laser devices 2 (not shown), and the overlap rate (the rate at which irradiation marks overlap) between adjacent rows (or adjacent columns) when the laser pulse LP is scanned back and forth.

[0032] The trigger pulse control unit 52 generates a trigger pulse synchronized with the laser pulse LP oscillated by the laser device 2, based on a synchronization signal provided from the laser control unit 51. For example, the frequency of the trigger pulse generated by the trigger pulse control unit 52 is 1 / N (N is any natural number) or N times the repetition frequency or oscillation frequency of the laser pulse LP.

[0033] The scanner control unit 54 controls the galvano scanner 15 (scanner control) based on the trigger pulse processed by the personal computer 53 as necessary. Similarly, the stage control unit 55 controls the moving table 41 in the stage device 4 (stage control) based on the trigger pulse processed by the personal computer 53 as necessary. In this way, based on the trigger pulse synchronized with the laser pulse LP, the scanner control unit 54 can appropriately execute Y-direction scanning of the laser pulse LP by the galvano scanner 15, and the stage control unit 55 can appropriately execute X-direction driving of the semiconductor wafer 3 by the moving table 41. The personal computer 53 may be used for adjustment in the scanner control unit 54 and / or the stage control unit 55 (hereinafter collectively referred to as the laser scanning control unit 56) described below.

[0034] FIG. 2 is a schematic functional block diagram of the laser scanning control unit 56 and the like according to this embodiment. The laser scanning control unit 56 includes an irradiation area setting unit 61, an irradiation interval adjustment unit 62, and an irradiation area overlap control unit 63. As long as the laser scanning control unit 56 can achieve at least a part of the actions and / or effects described below, some of these functional blocks may be omitted. These functional blocks may be realized by the cooperation of hardware resources such as a central processing unit of a computer, a memory, an input device, an output device, and peripheral devices connected to the computer, and software executed using them. Regardless of the type of computer or the installation location, each of the above functional blocks may be realized by the hardware resources of a single computer, or may be realized by combining hardware resources distributed among multiple computers.

[0035] The laser scanning control unit 56 controls the first scanning of the laser pulse LP along the Y direction as the first scanning direction by the laser scanning unit 6, and the second scanning of the laser pulse LP along the X direction as the second scanning direction. As in the example of FIG. 1, when the galvano scanner 15 functions as a first scanning unit that executes the first scanning of the laser pulse LP along the Y direction, the scanner control unit 54, which is a part of the laser scanning control unit 56, functions as a first scanning control unit that controls the first scanning unit 15, and when the moving table 41 functions as a second scanning unit that executes the second scanning of the laser pulse LP along the X direction (driving the semiconductor wafer 3 along the X direction), the stage control unit 55, which is a part of the laser scanning control unit 56, functions as a second scanning control unit that controls the second scanning unit 41. In the following, unless otherwise specified, the description will be given along this example.

[0036] However, as described above, when the galvano scanner 15 functions as a first scanning unit and a second scanning unit that perform the first scanning and the second scanning of the laser pulse LP along both the Y direction and the X direction, the laser scan control unit 56 may be substantially configured only by the scanner control unit 54 that controls the galvano scanner 15. Similarly, when the moving table 41 functions as a first scanning unit and a second scanning unit that perform the first scanning and the second scanning of the laser pulse LP along both the Y direction and the X direction, the laser scan control unit 56 may be substantially configured only by the stage control unit 55 that controls the moving table 41.

[0037] The irradiation area setting unit 61 sets one or more irradiation areas on the semiconductor wafer 3 as the workpiece. Here, the irradiation area means an area on the semiconductor wafer 3 to be irradiated with the laser pulse LP through a series or one XY scan (planar scan) by the galvano scanner 15 and the moving table 41. If there is no problem in terms of the performance of the laser device 2 and the laser scanning unit 6, it is preferable that the irradiation area setting unit 61 sets the entire surface (whole surface) of the semiconductor wafer 3 to be processed as the irradiation area. On the other hand, if the entire surface of the semiconductor wafer 3 cannot be covered by one XY scan, the irradiation area setting unit 61 divides the surface of the semiconductor wafer 3 to be processed into a plurality of irradiation areas. For example, as shown in FIG. 3, the irradiation area setting unit 61 divides the surface of the semiconductor wafer 3 into four equal parts, i.e., four irradiation areas 3A, 3B, 3C, and 3D. Each of these irradiation areas 3A to 3D is covered by a series or one XY scan by the galvano scanner 15 and the moving table 41. FIG. 2 exemplarily and typically shows a first irradiation area 3A and a second irradiation area 3B.

[0038] For each of the above-described irradiation regions on the semiconductor wafer 3, the laser scanning unit 6 sequentially irradiates different irradiation positions in each irradiation region with the laser pulse LP while scanning the irradiation region in the XY directions under the control of the laser scan control unit 56. As described above, in the example of this embodiment, the galvano scanner 15 as the first scanning unit executes the first scan of the laser pulse LP along the Y direction, and the moving table 41 as the second scanning unit executes the second scan of the laser pulse LP along the X direction.

[0039] FIG. 4 shows a schematic example of the first and second scans of the laser pulse LP by the laser scanning unit 6. A number of circles aligned in the X and Y directions in this figure show a schematic area (hereinafter, for convenience, also referred to as an irradiation mark) annealed by the laser pulse LP that is continuously irradiated while sequentially changing the irradiation position in the irradiation area IR set by the irradiation area setting unit 61 (i.e., while being scanned). In this example, the galvano scanner 15 as the first scanning unit performs a first scan in which the laser pulse LP is linearly scanned between both ends (upper and lower ends in FIG. 4, both not shown) of the irradiation area IR along the Y direction. In addition, the moving table 41 as the second scanning unit performs a second scan in which the laser pulse LP is scanned along the X direction (a second scanning direction intersecting or perpendicular to the Y direction as the first scanning direction) to shift the position of the subsequent first scan.

[0040] In the illustrated example, Y scanning by the galvano scanner 15 is started in the first leftmost column that constitutes the periphery of the irradiation area IR (the left edge or side in FIG. 4) or is closest to the periphery of the irradiation area IR. Specifically, a laser pulse LP is scanned in the +Y direction by the galvano scanner 15 from the lower end (not shown) of the irradiation area IR to the upper end (not shown). At this time, one laser pulse LP is irradiated every time the galvano scanner 15 performs a first scan of a basic distance (or unit distance) d0 in the +Y direction. As a result, irradiation marks are aligned in the Y direction at intervals of d0.

[0041] When the laser pulse LP is scanned by the galvano scanner 15 up to the upper end (not shown) of the irradiation region IR, an X-scan is performed by the moving table 41. Specifically, at the upper end (not shown) of the irradiation region IR, the laser pulse LP is scanned in the +X direction by the moving table 41. In the illustrated example, the distance of this X-scan or the second scan is substantially the same as the basic distance d0 in the above-mentioned Y-scan.

[0042] Next, Y-scanning is performed by the galvano scanner 15 in the second row from the periphery of the irradiation area IR (the second row from the left in FIG. 4). Specifically, the laser pulse LP is scanned in the -Y direction by the galvano scanner 15 from the upper end (not shown) of the irradiation area IR to the lower end (not shown). At this time, one laser pulse LP is irradiated every time the galvano scanner 15 performs the first scan in the -Y direction for a basic distance d0. As a result, the irradiation marks are aligned in the Y direction at intervals of d0.

[0043] When the laser pulse LP is scanned by the galvano scanner 15 up to the lower end (not shown) of the irradiation region IR, an X-scan is performed by the moving table 41. Specifically, at the lower end (not shown) of the irradiation region IR, the laser pulse LP is scanned in the +X direction by the moving table 41. In the illustrated example, the distance of this X-scan or second scan is substantially the same as the basic distance d0 in the above-mentioned Y-scan.

[0044] By alternately performing the first scan along the ±Y direction and the second scan along the +X direction as described above, the entire irradiation region IR is irradiated with the laser pulse LP and subjected to an annealing process.

[0045] In the illustrated example, the Y-direction distance between two adjacent or consecutive irradiation positions in the Y-scanning by the galvano scanner 15 is constant at d0. Similarly, the X-direction distance between two adjacent or consecutive irradiation positions in the X-scanning by the moving table 41 is also constant at d0. Here, the distance d0 between any two irradiation positions adjacent in the Y-direction or X-direction may correspond to or match the intended size (e.g., diameter) of the irradiation mark caused by each laser pulse LP.

[0046] As shown in Fig. 4, the irradiation marks in the first row constituting the peripheral part of the irradiation area IR are smaller than the irradiation marks in the second and subsequent rows constituting the non-peripheral part of the irradiation area IR, and do not reach the expected size. This is because the size of the irradiation mark at a certain irradiation position is affected not only by the laser pulse LP irradiated to that irradiation position, but also by the laser pulse LP irradiated to the adjacent irradiation position. For example, the irradiation mark in the first row also grows due to the transfer of heat from the laser pulse LP irradiated to the irradiation position in the second row to the right of it.

[0047] When such influence from adjacent positions cannot be ignored, the degree of annealing (e.g., the degree of temperature rise, the degree of activation of dopants implanted in the semiconductor wafer 3, the degree of ohmicization of the semiconductor wafer 3 made of SiC or the like, and the size of the irradiation mark) differs between the peripheral portion (e.g., the first row in FIG. 4) and the non-peripheral portion (e.g., the second row and thereafter in FIG. 4) of the irradiation region IR. For example, in the non-peripheral portion (e.g., the center of the semiconductor wafer 3) in the second row and thereafter, the laser pulse LP is irradiated to all adjacent positions around any irradiation position (i.e., the entire circumference of each irradiation position is surrounded by other irradiation positions), whereas in the peripheral portion of the first row, the laser pulse LP is irradiated to adjacent positions in the second row on the right side, while the laser pulse LP is not irradiated to adjacent positions outside the irradiation region IR on the left side.

[0048] In this way, the degree of annealing is low in the peripheral portion of the irradiation region IR because the influence from adjacent positions is weak (or heat escapes to adjacent positions not irradiated with the laser pulse LP), and the irradiation mark does not grow to a sufficient size as shown in FIG. 4. This means that the quality of the annealing varies between the peripheral portion and non-peripheral portion of the irradiation region IR, or the quality of the annealing decreases in the peripheral portion of the irradiation region IR. Although not shown, the same problem also occurs at the upper end (upper adjacent position is outside the irradiation region IR), lower end (lower adjacent position is outside the irradiation region IR), and right end (right adjacent position is outside the irradiation region IR) of the irradiation region IR (not shown).

[0049] In order to solve such problems, the laser scanning control unit 56 according to this embodiment includes an irradiation interval adjustment unit 62. The irradiation interval adjustment unit 62 makes the interval between adjacent irradiation positions of the laser pulse LP in the peripheral portion of the irradiation region IR smaller than the interval between adjacent irradiation positions of the laser pulse LP in the non-peripheral portion of the irradiation region IR. For example, the irradiation interval adjustment unit 62 makes at least the interval between the irradiation positions in the second scanning direction (X direction) in the peripheral portion smaller than the interval between the irradiation positions in the second scanning direction (X direction) in the non-peripheral portion.

[0050] Specifically, as shown in Fig. 5, the irradiation interval adjustment unit 62 makes the interval d1 between the irradiation positions in the first row (peripheral portion) of the irradiation area IR and the adjacent irradiation positions in the second row smaller than the interval d0 between the irradiation positions in the second row and thereafter (non-peripheral portion) of the irradiation area IR. More specifically, the irradiation interval adjustment unit 62 makes at least the interval d1 between the irradiation positions in the second scanning direction (X direction) for the first row (peripheral portion) smaller than the interval d0 (for example, the interval between the second row and the third row) between the irradiation positions in the second scanning direction (X direction) for only the second row and thereafter (non-peripheral portion). Such adjustment of the interval between the irradiation positions is realized by reducing the scanning amount or driving amount by the moving table 41 as the second scanning unit from the basic distance d0 to the adjustment distance d1 only for the first time for the transition from the first row to the second row.

[0051] In this manner, in this embodiment, the interval between the laser irradiation positions in the peripheral portion of the irradiation region IR is set smaller than the interval between the laser irradiation positions in the non-peripheral portion of the irradiation region IR. In the peripheral portion where the interval (d1) between the laser irradiation positions is small, the influence of the adjacent positions close to each other on the annealing process is strengthened, so that the above-mentioned problem that the degree of the annealing process is low in the peripheral portion can be effectively solved.

[0052] As shown in Fig. 6, the irradiation interval adjustment unit 62 may adjust the interval between the irradiation positions in the first scanning direction (Y direction) for the peripheral portion (first row) in addition to or instead of adjusting the interval between the irradiation positions in the second scanning direction (X direction) for the peripheral portion (first row). Specifically, the irradiation interval adjustment unit 62 makes the interval d2 between the irradiation positions adjacent in the Y direction in the first row (peripheral portion) of the irradiation area IR smaller than the interval d0 between the irradiation positions adjacent in the Y direction in the second row and subsequent rows (non-peripheral portion) of the irradiation area IR. Such an adjustment of the interval between the irradiation positions is realized by reducing the unit scan amount per laser pulse LP by the galvano scanner 15 as the first scanning unit from the basic distance d0 to the adjustment distance d2 only in the first row. In the peripheral area where the distance (d2) between the laser irradiation positions is small, the influence on the annealing process from nearby adjacent positions (which themselves exist in the peripheral area) is strengthened, so that the above-mentioned problem of the degree of annealing process being low in the peripheral area can be effectively solved.

[0053] In addition to or instead of adjusting the irradiation interval mainly for the peripheral part of the irradiation area IR as shown in FIG. 5 or FIG. 6, the irradiation interval over the entire irradiation area IR (i.e., including not only the peripheral part but also the non-peripheral part) may be adjusted according to the size of the irradiation area IR itself. For example, the smaller or narrower the irradiation area IR, the smaller the interval between adjacent irradiation positions of the laser pulse LP is preferably adjusted by the irradiation interval adjustment unit 62. When the irradiation area IR is small, the number of times the laser pulse LP is irradiated is reduced, so that the heat accumulation in the entire irradiation area IR is reduced, and there is a possibility that the annealing process does not proceed properly. Therefore, by reducing the overall irradiation interval in the irradiation area IR by the irradiation interval adjustment unit 62, the number of times the laser pulse LP is irradiated is increased, and the desired annealing process can be realized.

[0054] The above-described adjustment of the irradiation interval by the irradiation interval adjustment unit 62 may be performed manually through the personal computer 53 that can be operated by a user such as an administrator of the laser annealing apparatus 1. Specifically, the irradiation interval adjustment unit 62 adjusts the interval of the irradiation positions in the second scanning direction (X direction) and / or the first scanning direction (Y direction) regarding the periphery of the irradiation region IR based on irradiation interval adjustment information provided from the personal computer 53 in response to the user's operation.

[0055] When manually adjusting the irradiation interval in this way, a measuring device 7 may be used to measure various characteristics of the semiconductor wafer 3 after the annealing process has actually been performed using the laser pulse LP based on the irradiation interval before and / or after the adjustment. The measurement results by such a measuring device 7 are provided to the personal computer 53 and are presented or displayed to the user via a monitor or the like. This allows the user to check, for example, in approximately real time, whether the irradiation interval set by the user achieves the desired characteristics of the semiconductor wafer 3. If this irradiation interval does not achieve the desired characteristics of the semiconductor wafer 3, the user can operate the personal computer 53 to appropriately update the irradiation interval.

[0056] Instead of the above-described manual adjustment via the user and the personal computer 53, the irradiation interval adjustment unit 62 may autonomously (or automatically) set the adjustment value of the irradiation interval based on the measurement results from the measurement device 7. Such an irradiation interval adjustment unit 62 autonomously sets an appropriate irradiation interval so that the desired characteristics of the semiconductor wafer 3 (measured by the measurement device 7) are realized.

[0057] The characteristics of the semiconductor wafer 3 (after the annealing process) measured by the measuring device 7 are arbitrary, but an example is the sheet resistance at each irradiation position (particularly, the peripheral portion of the irradiation area IR) of the semiconductor wafer 3. The irradiation interval adjustment unit 62, which automatically adjusts the irradiation interval, can set an optimal irradiation interval for the peripheral portion of the irradiation area IR by comprehensively referring to these measurement results.

[0058] The irradiation area overlap control unit 63 controls the overlapping of a plurality of irradiation areas (for example, irradiation areas 3A to 3D in FIG. 3) when the irradiation area setting unit 61 sets them. For example, the irradiation area overlap control unit 63 overlaps the peripheral part of the first irradiation area 3A (the right edge in FIG. 3) and the peripheral part of the second irradiation area 3B (the left edge in FIG. 3) at the boundary between the first irradiation area 3A and the second irradiation area 3B that are adjacent to each other in FIG. 3.

[0059] 7 is a schematic diagram showing the first irradiation region 3A (the region on the left side in FIG. 7) and the second irradiation region 3B (the region on the right side in FIG. 7) overlapping under the control of the irradiation region overlap control unit 63. The laser scanning unit 6 (the galvano scanner 15 and the moving table 41) scans the laser pulse LP over the first irradiation region 3A and the second irradiation region 3B adjacent to each other. Here, as shown in the schematic diagram, the irradiation marks in the first irradiation region 3A and the second irradiation region 3B adjacent to each other in the X direction (the left-right direction in FIG. 7) are preferably aligned along the X direction, which is the adjacent direction (i.e., the row of irradiation marks aligned in the X direction in the first irradiation region 3A and the row of irradiation marks aligned in the X direction in the second irradiation region 3B are preferably aligned on a straight line in the X direction).

[0060] In the example of this figure, the same laser scanning as in the example of FIG. 5 is performed for each of the first irradiation area 3A and the second irradiation area 3B. Specifically, for the first irradiation area 3A, the irradiation interval in the X direction for the last row (rightmost row) constituting the peripheral part is reduced from the basic distance d0 to the adjusted distance d1 by the irradiation interval adjustment unit 62. Also, for the second irradiation area 3B, the irradiation interval in the X direction for the first row (leftmost row) constituting the peripheral part is reduced from the basic distance d0 to the adjusted distance d1 by the irradiation interval adjustment unit 62. Note that the irradiation interval in the X direction for the last row of the first irradiation area 3A may not be adjusted and may remain at the basic distance d0, and the irradiation interval in the X direction for the first row of the second irradiation area 3B may not be adjusted and may remain at the basic distance d0.

[0061] The irradiation area overlap control unit 63 overlaps the peripheral portion of the first irradiation area 3A and the peripheral portion of the second irradiation area 3B at the boundary between the first irradiation area 3A and the second irradiation area 3B. In the illustrated example, the peripheral portion of the first irradiation area 3A and the peripheral portion of the second irradiation area 3B are overlapped by the overlap amount OL by the irradiation area overlap control unit 63. The size of the overlap amount OL is arbitrary, but it is preferable that it is smaller than the basic distance d0 in the first irradiation area 3A and / or the second irradiation area 3B, and it is more preferable that it is smaller than the adjustment distance d1 in the first irradiation area 3A and / or the second irradiation area 3B. In addition, as a result of such overlap, as in the illustrated example, the irradiation mark in the last row (periphery) of the first irradiation area 3A and the irradiation mark in the first row (periphery) of the second irradiation area 3B may or may not overlap.

[0062] According to this embodiment, in the laser annealing apparatus 1 that irradiates a laser pulse LP to each of a plurality of irradiation regions (e.g., the first irradiation region 3A and the second irradiation region 3B) set on the semiconductor wafer 3 by the irradiation region setting unit 61, by overlapping peripheral portions (e.g., the final row in the first irradiation region 3A and the first row in the second irradiation region 3B) in each irradiation region where the degree of annealing tends to be low, the annealing process can be progressed to a desired degree in such peripheral portions as well.

[0063] The above-described adjustment of the overlap amount OL by the irradiation area overlap control unit 63 may be performed manually through the personal computer 53 that can be operated by a user such as an administrator of the laser annealing apparatus 1, similar to the adjustment of the irradiation interval by the above-described irradiation interval adjustment unit 62. Specifically, the irradiation area overlap control unit 63 adjusts the overlap amount OL between the first irradiation area 3A and the second irradiation area 3B based on overlap amount adjustment information provided from the personal computer 53 in response to a user's operation.

[0064] When manually adjusting the overlap amount OL, a measuring device 7 may be used to measure various characteristics of the semiconductor wafer 3 (particularly, the overlapping portion or boundary portion of the first irradiation area 3A and the second irradiation area 3B) after the annealing process has actually been performed based on the overlap amount OL before and / or after the adjustment. The measurement results by such a measuring device 7 are provided to the personal computer 53 and are presented or displayed to the user through a monitor or the like. This allows the user to check, for example, in approximately real time, whether the overlap amount OL that he or she has set realizes the intended characteristics of the semiconductor wafer 3. If the overlap amount OL does not realize the intended characteristics of the semiconductor wafer 3, the user can operate the personal computer 53 to appropriately update the overlap amount OL.

[0065] Instead of the above-described manual adjustment via the user and the personal computer 53, the irradiation area overlap control unit 63 may autonomously (or automatically) set an adjustment value for the overlap amount OL based on the measurement results from the measurement device 7. Such an irradiation area overlap control unit 63 autonomously sets an appropriate overlap amount OL so that the desired characteristics of the semiconductor wafer 3 (such as the sheet resistance measured by the measurement device 7) are realized.

[0066] The present disclosure has been described above based on the embodiments. Various modifications are possible to the combinations of the components and processes in the exemplary embodiments, and it will be obvious to those skilled in the art that such modifications are included within the scope of the present disclosure.

[0067] In the above embodiment, the scanning of the laser pulse LP in the irradiation region IR is realized by a combination of X-scanning and Y-scanning, both of which are linear scanning (also represented as raster scanning), but it may be realized in any other manner. For example, the laser pulse LP may be scanned spirally mainly along the circumferential direction of the circular irradiation region IR. In this case, for example, the irradiation interval of the laser pulse LP in the peripheral portion or outer periphery of the circular irradiation region IR is adjusted by the irradiation interval adjustment unit 62.

[0068] The configuration, action, and function of each device and method described in the embodiments can be realized by hardware resources or software resources, or by the cooperation of hardware resources and software resources. For example, a processor, ROM, RAM, and various integrated circuits can be used as hardware resources. For example, programs such as an operating system and applications can be used as software resources. [Explanation of symbols]

[0069] 1 laser annealing apparatus, 2 laser apparatus, 3 semiconductor wafer, 3A first irradiation area, 3B second irradiation area, 4 stage apparatus, 6 laser scanning unit, 7 measuring apparatus, 15 galvanometer scanner, 41 moving table, 53 personal computer, 54 scanner control unit, 55 stage control unit, 56 laser scanning control unit, 61 irradiation area setting unit, 62 irradiation interval adjustment unit, 63 irradiation area overlap control unit, LP laser pulse.

Claims

1. A laser annealing apparatus that irradiates a laser onto an irradiation area of ​​a workpiece for annealing, comprising: a laser scanning unit that scans the laser over the irradiation region; an irradiation interval adjustment unit that makes an interval between adjacent irradiation positions of the laser in a peripheral portion of the irradiation region smaller than an interval between adjacent irradiation positions of the laser in a non-peripheral portion of the irradiation region; A laser annealing apparatus comprising:

2. the laser scanning unit executes a first scan in which the laser is linearly scanned between both ends of the irradiation region along a first scanning direction, and a second scan in which the laser is scanned along a second scanning direction intersecting the first scanning direction to shift a position of the subsequent first scan, the irradiation interval adjustment unit makes at least the interval in the second scanning direction in the peripheral portion smaller than the interval in the second scanning direction in the non-peripheral portion; 2. The laser annealing apparatus according to claim 1.

3. The laser annealing apparatus irradiates a laser beam onto a first irradiation region and a second irradiation region adjacent to each other as the irradiation region, an irradiation area overlap control unit that overlaps a peripheral portion of the first irradiation area and a peripheral portion of the second irradiation area at a boundary portion between the first irradiation area and the second irradiation area; 3. The laser annealing apparatus according to claim 1 or 2.

4. 3. The laser annealing apparatus according to claim 1, wherein the irradiation interval adjustment unit adjusts the interval between adjacent irradiation positions of the laser to be smaller as the irradiation region becomes smaller.

5. 3. The laser annealing apparatus according to claim 1, wherein the laser scanning unit sequentially irradiates different irradiation positions in the irradiation region with laser pulses as the laser.

6. A laser annealing apparatus that irradiates a laser onto an irradiation area of ​​a workpiece for annealing, comprising: a laser scanning unit configured to scan the laser over a first irradiation region and a second irradiation region adjacent to each other as the irradiation region; an irradiation area overlap control unit that overlaps a peripheral portion of the first irradiation area and a peripheral portion of the second irradiation area at a boundary portion between the first irradiation area and the second irradiation area; A laser annealing apparatus comprising:

7. A laser annealing method for irradiating an irradiation area of ​​a workpiece with a laser for annealing, comprising the steps of: scanning the laser across the illumination area; Making the interval between adjacent irradiation positions of the laser in a peripheral portion of the irradiation region smaller than the interval between adjacent irradiation positions of the laser in a non-peripheral portion of the irradiation region; The laser annealing method includes:

8. A laser annealing program for irradiating a laser onto an irradiation area of ​​a workpiece for annealing, comprising: scanning the laser across the illumination area; Making the interval between adjacent irradiation positions of the laser in a peripheral portion of the irradiation region smaller than the interval between adjacent irradiation positions of the laser in a non-peripheral portion of the irradiation region; A storage medium storing a laser annealing program for causing a computer to execute the above.

Images