Heat treatment method, heat treatment apparatus, and semiconductor device manufacturing method

Abstract

A heat treatment device according to the present embodiment comprising: an optical system (30) having a laser light source (21) that generates continuous oscillation laser light (L1), and an optical scanner (32) that scans the laser light (L1) along a first direction, the optical system (30) guiding the laser light (L1) to a substrate (100); an optical system drive unit (40) that moves the optical system (30) to change the irradiation position of the laser light (L1) with respect to the substrate (100); and a stage (10) that moves the irradiation position of the laser light (L1). The irradiation position with respect to the substrate is moved in a second direction and a third direction by driving of the stage (10) and the optical system (30).

Description

[Technical Field]

[0001] The present disclosure relates to a heat treatment method, a heat treatment apparatus, and a method for manufacturing a semiconductor device. [Background technology]

[0002] Patent Document 1 discloses an excimer laser annealing device for forming a polycrystalline silicon thin film. In Patent Document 1, a projection lens focuses laser light onto a substrate so that the laser light forms a linear irradiation area. This crystallizes the amorphous silicon film on the glass substrate to form a polysilicon film.

[0003] In Patent Document 1, a pulsed laser light source is used to heat-treat only the surface layer of a semiconductor thin film. Pulsed laser light has a higher pulse peak value per pulse than CW laser light. Irradiation with short-pulse laser light with a pulse width of a few nanoseconds crystallizes the amorphous silicon layer on the glass substrate. By using pulsed laser light, only the surface of the silicon film can be heated. This prevents the glass substrate from exceeding its heat resistance temperature. Furthermore, damage to the polyimide film or Cu film that underlies the silicon film can be prevented. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2018-64048 Summary of the Invention

[0005] Such high-power pulsed laser light sources are expensive, making it difficult to reduce the cost of the equipment's components. Meanwhile, annealing using a heat treatment furnace or lamp annealing requires long heating times. Therefore, it becomes impossible to heat the silicon film above the heat resistance temperature of the glass substrate. Alternatively, there is a risk of damage to the underlying film, such as a polyimide film or Cu film.

[0006] On the other hand, semiconductor lasers are inexpensive, but they are continuous wave (CW) lasers. When CW laser light is pulsed using a modulator, the output power drops. This requires many light sources, making it difficult to reduce costs. Furthermore, when CW laser light is irradiated onto a substrate without modulation, the heating time becomes long. This can result in damage to the underlying film on the substrate.

[0007] Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

[0008] The heat treatment method for a semiconductor device according to this embodiment includes the steps of: (A) generating a continuous wave laser beam; (B) scanning an irradiation position of the laser beam on a substrate held on a drive stage along a first direction using an optical scanner provided in an optical system; (C) moving one of the optical system or the drive stage to move the irradiation position of the laser beam along a second direction intersecting the first direction in a planar view; and (D) moving the other of the optical system or the drive stage to move the irradiation position of the laser beam along a third direction intersecting the second direction in a planar view.

[0009] The heat treatment apparatus for a semiconductor device according to this embodiment includes a laser light source that generates continuous wave laser light, an optical system having an optical scanner that scans the laser light along a first direction and that guides the laser light to a substrate, an optical system drive unit that moves the optical system so as to change the irradiation position of the laser light on the substrate, and a drive stage that holds the substrate and moves the irradiation position of the laser light, wherein by driving either the optical system drive unit or the drive stage, the irradiation position of the laser light changes along a second direction that intersects with the first direction in the planar view, and by driving the other of the optical system drive unit or the drive stage, the irradiation position of the laser light changes along a third direction that intersects with the second direction in the planar view.

[0010] The method for manufacturing a semiconductor device according to this embodiment includes the steps of: (SA) generating continuous wave laser light; (SB) scanning the irradiation position of the laser light on a substrate held on a drive stage along a first direction using an optical scanner provided in an optical system; (SC) moving the irradiation position of the laser light on the substrate along a second direction that intersects with the first direction in a planar view by moving one of the optical system or the drive stage; and (SD) moving the irradiation position of the laser light on the substrate along a third direction that intersects with the second direction in a planar view by moving the other of the optical system or the drive stage.

[0011] According to the embodiment, it is possible to provide a heat treatment apparatus, a heat treatment method, and a method for manufacturing a semiconductor device that can perform appropriate heat treatment. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing a heat treatment apparatus according to an embodiment of the present invention; [Figure 2] 1 is a cross-sectional view schematically showing a heat treatment apparatus according to an embodiment. [Figure 3] FIG. 10 is a diagram showing a change in the irradiation position on the substrate. [Figure 4] 5A to 5C are schematic diagrams for explaining a procedure for irradiating laser light. [Figure 5] 1 is an SEM image showing a crystallized polysilicon film. [Figure 6] FIG. 1 is a diagram showing an EBSD image obtained by analyzing the crystals of a polysilicon film. [Figure 7] 1 is an SEM image showing a crystallized polysilicon film. [Figure 8] FIG. 1 is a cross-sectional view showing a simplified configuration of an organic EL display. [Figure 9] 1A to 1C are cross-sectional views showing steps in a manufacturing method of a semiconductor device according to an embodiment of the present invention. [Figure 10] 1A to 1C are cross-sectional views showing steps in a manufacturing method of a semiconductor device according to an embodiment of the present invention. [Figure 11] FIG. 10 is a diagram showing a change in the irradiation position on the substrate. DETAILED DESCRIPTION OF THE INVENTION

[0013] The heat treatment method and heat treatment apparatus for a semiconductor device according to this embodiment perform heat treatment by, for example, irradiating a substrate with a laser. In this embodiment, the heat treatment apparatus is a laser annealing apparatus for forming a low temperature polysilicon (LTPS) film. That is, an amorphous silicon film is heated by irradiating it with laser light, and a polysilicon film is formed.

[0014] Of course, the heat treatment apparatus according to this embodiment is not limited to a laser annealing apparatus. For example, it can also be applied to a heat treatment apparatus that activates a semiconductor film by irradiating it with laser light. Hereinafter, the heat treatment apparatus, heat treatment method, and manufacturing method according to this embodiment will be described with reference to the drawings.

[0015] The configuration of a heat treatment apparatus according to this embodiment will be described with reference to Figures 1 and 2. Figure 1 is a schematic diagram showing the configuration of heat treatment apparatus 1. Figure 2 is a side view showing the configuration of heat treatment apparatus 1.

[0016] 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, and the xy plane is a plane parallel to the main surface of the substrate 100. The x direction is the scanning direction of the optical scanner 32. The y direction is a direction perpendicular to the x direction and is the movement direction of the optical system 30. Fig. 1 is a schematic diagram showing the configuration in the XY plane, and Fig. 2 is a schematic diagram showing the configuration in the YZ plane.

[0017] 1 and 2, the heat treatment apparatus 1 includes a stage 10, a laser light source 21, an AO (acousto-optic) element 23, an optical fiber 24, an optical system 30, an optical system driver 40, and a controller 50. The optical system 30 includes a lens 31, an optical scanner 32, and an fθ lens 33, and propagates laser light L1 to the substrate 100. For example, the lens 31, the optical scanner 32, and the fθ lens 33 are installed in a housing of the optical system 30. Of course, the optical system 30 may include optical elements other than the lens 31, the optical scanner 32, and the fθ lens 33.

[0018] The substrate 100 to be irradiated with the laser light L1 is placed on a stage 10. The stage 10 is a drive stage that moves the substrate 100. The stage 10 movably holds the substrate 100. When the stage 10 is driven with the substrate 100 placed on it, the substrate 100 moves. As shown in FIG. 1, the stage 10 moves the substrate 100 along direction B. The direction B is, for example, parallel to the X direction. As a result, the irradiation position of the laser light L1 on the substrate 100 changes in the X direction. The stage 10 may be a suction stage that suction-holds the substrate 100.

[0019] The laser light source 21 generates continuous wave (CW) laser light L1. The laser light source 21 is a semiconductor laser that generates CW light. The laser wavelength may be 500 nm or less. The laser wavelength may also be 460 nm or less. Here, a laser diode with a laser wavelength of 450 nm, 380 nm, or 360 nm can be used as the laser light source 21.

[0020] The laser light L1 is incident on the optical fiber 24 via the AO element 23. The optical fiber 24 guides the laser light L1 to the optical system 30. Specifically, the incident end of the optical fiber 24 faces the AO element 23, and the exit end faces the optical system 30. The exit end of the optical fiber 24 is attached to the optical system 30. Therefore, the laser light L1 is incident on the optical system 30 via the optical fiber 24. The optical fiber 24 is fixed to the optical system 30 in a bent state. The optical system 30 is disposed above the substrate 100.

[0021] The AO element 23 modulates the laser light L1. The AO element 23 is, for example, an AO modulator or an AO polarizer. The AO element 23 changes the deflection angle of the laser light L1 in response to a control signal from the controller 50. Specifically, the controller 50 can control the AO element 23 to prevent the laser light L1 from entering the optical fiber 24. For example, the controller 50 outputs a control signal to the AO element 23 in response to the scanning direction and scanning position of the optical scanner 32. In response to the control signal from the controller 50, the AO element 23 controls the deflection angle of the laser light L1.

[0022] The controller 50 controls the AO element 23 to switch between irradiation and non-irradiation of the laser light L1. For example, when the laser light L1 is to be irradiated onto the substrate 100, the controller 50 controls the deflection angle of the laser light L1 so that the laser light L1 from the AO element 23 enters the optical fiber 24. When the laser light L1 enters the optical fiber 24, the laser light L1 propagates through the optical system 30 and is guided to the substrate 100. On the other hand, when the laser light L1 is not to be irradiated onto the substrate 100, the controller 50 controls the deflection angle of the laser light L1 so that the laser light L1 from the AO element 23 does not enter the optical fiber 24. When the laser light L1 deviates from the optical fiber 24, the laser light L1 does not enter the optical system 30 and is therefore not irradiated onto the substrate 100.

[0023] The AO element 23 functions as an optical element that switches between irradiation and non-irradiation of the laser beam L1. That is, the controller 50 controls the AO element 23 so that irradiation and non-irradiation of the laser beam L1 occur alternately. The AO element 23 changes the deflection angle in response to a control signal from the controller 50. The optical shutter that switches between irradiation and non-irradiation of the laser beam L1 is not limited to the AO element 23, and other optical elements or a mechanical shutter may also be used.

[0024] The optical system driving unit 40 has a motor and a driving mechanism for driving the optical system 30. The optical system driving unit 40 has a gantry stage that movably holds the optical system 30. The optical system driving unit 40 moves the optical system 30 along the C direction in FIG. 2. The C direction is parallel to the Y direction.

[0025] The optical fiber 24 is connected to the optical system 30 with sufficient flexibility. The position of the output end of the optical fiber 24 changes as the optical system 30 moves. Even when the optical system 30 moves, the laser light L1 can be appropriately incident on the optical system 30. In other words, even when the position of the optical system 30 moves, the laser light L1 propagates along the optical axis within the optical system 30. Specifically, the optical system 30 moves with the output end of the optical fiber 24 positioned on the optical axis of the lens 31.

[0026] The laser light L1 incident on the optical system 30 is sequentially incident on the lens 31, the optical scanner 32, and the fθ lens 33. The lens 31 focuses the laser light L1 toward the optical scanner 32. The optical scanner 32 reflects the laser light L1 toward the fθ lens 33.

[0027] The optical scanner 32 is, for example, a galvanometer mirror, and deflects the laser light L1. The optical scanner 32 changes the deflection angle of the laser light L1, thereby changing the irradiation position of the laser light L1 on the substrate 100. The laser light L1 is scanned in the direction of arrow A in FIG.

[0028] Specifically, the optical scanner 32 is operated by a drive motor that rotates around the Y axis. The optical scanner 32 scans the laser light L1 along the X direction on the substrate 100. That is, as the optical scanner 32 scans the laser light L1, the irradiation position of the laser light L1 moves in the X direction on the substrate 100. Furthermore, the optical scanner 32 is not limited to a galvanometer mirror, and may be a polygon mirror, an acousto-optical element, or the like.

[0029] The fθ lens 33 refracts the laser light L1 reflected by the optical scanner 32. By disposing the fθ lens 33 directly above the substrate 100, the focal plane of the laser light L1 can be made to coincide with the main surface of the substrate 100. In other words, the focal position of the laser light L1 in the Z direction is at a constant height regardless of the deflection angle of the optical scanner 32. This makes it possible to keep the irradiation power density of the laser light L1 on the substrate 100 constant.

[0030] The spot shape of the laser light L1 irradiated onto the substrate 100 may be circular or rectangular. The intensity distribution of the laser light L1 in the beam cross section may be a Gaussian distribution. Alternatively, the laser light L1 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 light L1 is rectangular and the intensity distribution is a top-flat distribution.

[0031] 1, the optical fiber 24 guides the laser light L1 to the optical system 30, but other configurations and optical elements may be used. For example, the laser light source 21 may be fixed inside the optical system 30 unit.

[0032] As described above, the optical scanner 32 scans the laser light L1 along the X direction. The stage 10 moves the substrate 100 along the direction of arrow B in FIG. 1. Therefore, the irradiation position of the laser light L1 on the substrate 100 moves in the X direction. Furthermore, the optical system driver 40 moves the optical system 30 along the direction of arrow C in FIG. 2. When the optical system driver 40 moves the optical system 30, the irradiation position of the laser light L1 on the substrate 100 changes in the Y direction. Therefore, it is possible to freely change the irradiation position of the laser light on the substrate 100 within the XY plane.

[0033] Changes in the irradiation position of the laser light L1 will be described below with reference to Fig. 3. Fig. 3 is an XY plan view showing changes in the irradiation position of the laser light L1 on the substrate 100. Note that although the substrate 100 is circular in Fig. 3, it may be rectangular. Also, although the beam spot of the laser light L1 is circular, it may be rectangular.

[0034] The scanning direction of the optical scanner 32 is the direction of arrow A. Here, arrow A is parallel to the X direction. The optical scanner 32 moves the irradiation position of the laser light L1 along the +X direction. The movement direction of the optical system 30 by the optical system driver 40 is the direction of arrow C. In the XY plane view, arrow C is a direction that intersects with arrow A. For example, arrow C is a direction parallel to the Y direction. In other words, arrows A and B are perpendicular directions.

[0035] The movement direction of the substrate 100 by the stage 10 is the direction of arrow B. In the XY plane view, arrow B is a direction that intersects with arrow C. For example, arrow B is a direction parallel to the X direction. In other words, arrow B is a direction that is perpendicular to arrow C and parallel to arrow A. The movement direction of the stage 10 and the scanning direction of the optical scanner 32 are opposite directions.

[0036] The controller 50 controls the stage 10, the optical scanner 32, the optical system driver 40, and the AO element 23. The stage 10 and the optical system driver 40 operate in response to control signals from the controller 50. The stage 10 moves the substrate 100 to an XY position in response to the control signal. The optical system driver 40 controls the XY position of the optical system 30 relative to the substrate 100 in response to the control signal.

[0037] Furthermore, the controller 50 controls the scanning speed and scanning direction of the optical scanner 32. The optical scanner 32 scans with the laser light L1 in response to a control signal from the controller 50. The controller 50 controls the AO element 23 in response to the scanning direction and scanning position of the optical scanner 32. The AO element 23 deflects the laser light L1 to switch between irradiation and non-irradiation. The controller 50 controls the irradiation position of the laser light L1 on the substrate 100. The laser light L1 can be irradiated onto almost the entire surface of the substrate 100. A polysilicon film can be formed by crystallizing an amorphous silicon film provided on the substrate 100.

[0038] The controller 50 outputs a control signal synchronized with the control signal of the optical scanner 32 to the optical system 30, the stage 10, and the AO element 23. In this way, the irradiation position of the laser light L1 can be appropriately controlled.

[0039] Furthermore, the scanning speed of the optical scanner 32 is faster than the movement speed of the optical system driver 40 and the movement speed of the stage 10. Because the scanning speed of the optical scanner 32 is high, the substrate heating time (heat treatment time) can be shortened. Here, the substrate heating time is the irradiation time during which the laser light is continuously irradiated onto any one point on the substrate 100. In other words, the irradiation time is the time during which one point on the substrate 100 is scanned from one end of the beam spot to the other. The irradiation time at any point on the substrate 100 when irradiated with CW laser light can be calculated using the following formula (1). (Irradiation time) = (Beam size) / (Scanning speed) (1)

[0040] In this embodiment, the irradiation time is set to 100 μsec or less to prevent damage to the substrate 100 or the base film. That is, it is preferable to set the beam size and scanning speed in the X direction so that the irradiation time is 100 μsec or less. For example, when the beam size of the laser light L1 on the substrate 100 is 100 μm, it is preferable to set the scanning speed to 1 m / sec or more. When the beam size of the laser light L1 on the substrate 100 is 600 μm, it is preferable to set the scanning speed to 6 m / sec or more. In this embodiment, the beam size is set to 100 μm and the scanning speed is set to 6 m / sec, resulting in an irradiation time of 16.7 μsec.

[0041] The irradiation method according to this embodiment will be described with reference to Fig. 4. Fig. 4 is a diagram schematically showing a change in the irradiation position of the laser light L1 on the substrate 100. The laser light is irradiated onto the substrate 100 in the order of steps S1 to S8 in Fig. 4. Here, as shown in step S1 in Fig. 4, the spot shape of the laser light L1 is rectangular.

[0042] The optical scanner 32 scans the laser light L1 from the irradiation position shown in step S1 along the direction of arrow A shown in step S2. As a result, a linear irradiated line I11 is formed on the substrate 100. In step S2 of FIG. 4, one irradiated line I11 is formed. Specifically, the laser light L1 is scanned from the scanning end on the -X side to the scanning end on the +X side of the scanning range of the optical scanner 32, thereby forming the irradiated line I11. The width (size in the Y direction) of the irradiated line I11 corresponds to the spot size of the laser light L1. The length (size in the X direction) of the irradiated line I11 corresponds to the scanning range (scanning width) of the optical scanner 32.

[0043] The optical system driver 40 moves the optical system 30 in the direction of arrow B. Here, the scanning speed of the optical scanner 32 is sufficiently faster than the moving speed of the optical system 30, so the irradiated line I11 is shown as a rectangle in FIG. 4. If the optical scanner 32 scans while the optical system 30 is moving, the shape of the irradiated line I11 on the substrate 100 will be a parallelogram. The optical scanner 32 scans the laser light L1 in the X direction at a constant speed. The laser light L1 can be uniformly irradiated onto the substrate 100. A uniform polysilicon film can be formed.

[0044] By repeatedly performing beam scanning of the optical scanner 32 while the optical system 30 is moving, a plurality of irradiated lines I11 to I13 are formed as in step S3. Here, the optical system 30 moves at a constant speed while the optical scanner 32 is scanning. Therefore, the laser light L1 is irradiated in the order of the irradiated line I11, the irradiated line I12, and the irradiated line I13. The irradiated line I12 may overlap with the irradiated line I11 and the irradiated line I13. The irradiated line I12 is the same size as the irradiated line I11 and the irradiated line I13.

[0045] In this embodiment, the movement of the optical system 30 and the scanning of the optical scanner 32 are performed simultaneously. That is, while the optical system driver 40 is moving the optical system 30, the optical scanner 32 scans with the laser light L1. For example, while the optical system driver 40 is moving the optical system 30 in the +Y direction at a constant speed, the optical scanner 32 scans with the laser light L1. Of course, the scanning of the optical scanner 32 and the movement of the optical system 30 may be performed alternately. That is, after the optical scanner 32 has completed scanning one line, the optical system 30 may move at a predetermined feed pitch.

[0046] When the optical system driver 40 moves the optical system 30 from the movement end on the -Y side of the substrate 100 to the movement end on the +Y side, an irradiated area R1 is formed, as shown in step S4. The irradiated area R1 is a rectangle that includes multiple irradiated lines. The size of the irradiated area R1 in the X direction corresponds to the scanning width of the optical scanner 32. The size of the irradiated area R1 in the Y direction corresponds to the movement distance of the optical system 30 in the Y direction.

[0047] Here, the scanning speed of the optical scanner 32 is sufficiently faster than the movement speed of the optical system 30, so the irradiated area R1 is shown as a rectangle in FIG. 4. If the optical scanner 32 is scanned while the optical system 30 is moving, the irradiated area R1 will strictly be a parallelogram. Note that the stage 10 does not move the substrate 100 between steps S1 and S4. In other words, the position of the stage 10 is fixed until the irradiated area R1 is formed.

[0048] When the optical system 30 reaches the limit of movement on the -Y side, the stage 10 moves the substrate 100 in the direction of arrow B. Here, the stage 10 moves the substrate 100 in the -X direction. Therefore, the irradiation position on the substrate 100 moves in the +X direction. Note that while the stage 10 is moving, the AO element 23 does not irradiate the laser light L1. In other words, the controller 50 changes the deflection angle of the AO element 23 to prevent the laser light L1 from entering the optical fiber 24. Furthermore, while the stage 10 is moving, the optical system driver 40 moves the optical system 30 to the limit of movement on the +Y side.

[0049] The stage 10 moves in the -X direction by a distance corresponding to the scanning width of the optical scanner 32. After driving of the stage 10 is completed, the laser light L1 is irradiated onto the substrate 100 again, as shown in step S5. That is, the controller 50 changes the deflection angle of the AO element 23 and causes the laser light to enter the optical fiber 24. In the Y direction, the irradiation position in step S5 coincides with the irradiation position in step S1. In the X direction, the irradiation position in step S5 is shifted from the irradiation position in step S1 by a distance corresponding to the scanning width.

[0050] Then, scanning by the optical scanner 32 begins. As shown in step S6, the optical scanner 32 scans the laser light L1 in the +X direction. As a result, an irradiated line I21 is formed. After the stage 10 is moved, the same processes as in steps S2 to S4 above are performed. That is, by the scanning of the optical scanner 32 and the movement of the optical system 30, the laser light L1 is irradiated onto the substrate 100.

[0051] Since step S6 corresponds to step S2, in step S6, one new irradiated line I21 is formed on the substrate 100. That is, in step S6, the irradiated line I21 is formed in addition to the irradiated area R1 formed in step S4. The irradiated line I21 has the same size as the irradiated line I11.

[0052] Because step S7 corresponds to step S3, in step S7, three irradiated lines I21, I22, and I23 are formed on the substrate 100. That is, in step S7, irradiated lines I21, I22, and I23 are formed in addition to the irradiated area R1 formed in step S4. The irradiated lines I21, I22, and I23 are all the same size.

[0053] When the optical system 30 reaches the limit of movement on the -Y side, step S8 is reached. Because step S8 corresponds to step S4, an irradiated area R2 is formed on the substrate 100. That is, in step S8, an irradiated area R2 is formed in addition to the irradiated area R1 formed in step S4. The irradiated area R2 is a rectangle including multiple irradiated lines. The irradiated area R2 is the same size as the irradiated area R1. In the Y direction, the position of the irradiated area R2 coincides with the position of the irradiated area R1. In the X direction, the position of the irradiated area R2 is shifted from the position of the irradiated area R1.

[0054] By repeating the above process, the laser light L1 can be irradiated onto almost the entire surface of the substrate 100. That is, by repeating the processes of steps S5 to S8, rectangular irradiated areas are formed in sequence. By sequentially moving the stage 10, the laser light L1 is irradiated from one end of the substrate 100 to the other end in the X direction.

[0055] The movement speed of the optical system 30 driven by the optical system driver 40 is faster than the movement speed of the substrate 100 driven by the stage 10. The movement direction of the optical system 30 is set to be a direction intersecting the scanning direction of the optical scanner 32. The movement direction of the substrate 100 is set to be a direction intersecting the movement direction of the optical system 30. Specifically, as shown in FIG. 3 , the movement direction of the substrate 100 and the scanning direction of the optical scanner 32 are parallel to the X direction, and the movement direction of the optical system 30 is perpendicular to the X direction.

[0056] Therefore, after a rectangular irradiated area R1 is formed on the substrate 100, the next irradiated lines I21, I22, and I23 are formed in sequence on the other end of the scanning range. In this way, the laser light L1 can be appropriately irradiated onto the substrate, and a uniform polysilicon film can be formed.

[0057] It is assumed that the optical scanner 32 is a galvanometer mirror that moves the laser light L1 back and forth in the X direction. In this case, the galvanometer mirror alternately scans in the +X direction (hereinafter also referred to as the forward direction) and the -X direction (hereinafter also referred to as the reverse direction). That is, the optical scanner 32 scans the laser light L1 so that it reciprocates in the forward direction and the reverse direction. Therefore, at both ends (hereinafter referred to as the scanning ends) of the scanning range of the optical scanner 32, the drive motor decelerates the galvanometer mirror and then accelerates it in the opposite direction. At the scanning ends, the laser light L1 is irradiated onto the substrate 100 until the galvanometer mirror is decelerated and then accelerated. The irradiation time of the laser light at the scanning ends is longer than that at the center of the scanning range.

[0058] Therefore, in this embodiment, the controller 50 controls the AO element 23 so that the laser light L1 is not irradiated onto the substrate 100 at the scanning end where the galvanometer mirror accelerates and decelerates. Specifically, the AO element 23 switches the deflection angle of the laser light L1, so that the laser light L1 is not irradiated onto the substrate 100 at the scanning end. In other words, at the timing when the galvanometer mirror accelerates and decelerates, the AO element 23 deflects the laser light L1 so that it does not enter the optical fiber 24. This makes it possible to make the distribution of the irradiation time constant within the surface of the substrate 100, thereby enabling uniform crystallization.

[0059] Furthermore, adjacent irradiated lines may be scanned in the same direction or in opposite directions by the optical scanner 32. For example, if the irradiated line I11 is formed by scanning in the forward direction (+X direction), the irradiated line I12 may be formed by scanning in the reverse direction (-X direction). In this case, the odd-numbered irradiated lines are formed by scanning in the forward direction, and the even-numbered irradiated lines are formed by scanning in the reverse direction. This allows the laser light L1 to be irradiated onto almost the entire surface of the substrate 100 in a short period of time. Because the laser light L1 is irradiated onto the substrate 100 by reciprocating scanning, the AO element 23 prevents the laser light L1 from entering the optical fiber 24 only at the scanning end.

[0060] Alternatively, adjacent irradiated lines may be formed in the same scanning direction. For example, if irradiated line I11 is formed by forward scanning, irradiated line I12 may be formed by forward scanning. In this case, all irradiated lines are formed by forward scanning. Since laser light L1 is irradiated onto the substrate 100 during forward scanning, the AO element 23 prevents laser light L1 from entering the optical fiber 24 not only at the scanning end but also during reverse scanning. While the optical scanner 32 operates in the forward direction from one end of the scanning range to the other, the laser light L1 is irradiated onto the substrate 100. While the optical scanner 32 operates in the reverse direction from the other end of the scanning range to the other end, the AO element 23 prevents laser light L1 from being irradiated. Furthermore, while laser light L1 is not being irradiated, the movement of the optical system 30 by the optical system driver 40 may be stopped.

[0061] This makes it possible to suppress differences in irradiation conditions depending on the position in the X direction. For example, at any position in the X direction, the time interval between the scanning of the first line and the scanning of the second line is set as the scanning time interval. By irradiating the laser light only with forward scanning, it is possible to make the scanning time interval the same at the center and the scanning end of the scanning range.

[0062] Also, adjacent irradiated lines may be partially overlapped. That is, the -Y end of the irradiated line I11 is positioned on the -Y side of the +Y end of the irradiated line I12. Specifically, the movement speed of the optical system 30 may be set so that the irradiated line I11 and the irradiated line I12 shown in FIG. 4 partially overlap. In this case, the overlapping portion that has already crystallized when the irradiated line I11 is formed is further overwritten when the irradiated line I12 is formed. This improves the properties of the polysilicon film.

[0063] For example, if the laser light L1 has a Gaussian distribution, the laser light intensity is high at the center of the spot of the laser light L1. Alternatively, the laser light intensity decreases as the distance from the center of the spot increases. The irradiation amount varies depending on the position in the Y direction within the irradiated line. Therefore, the movement speed of the optical system 30 is set so that adjacent irradiated lines partially overlap in the Y direction. This results in the laser light scanning twice at locations far from the center of the spot in the Y direction. For example, if the intensity of the laser light L1 at the center of the spot with a Gaussian distribution is 100%, the overlap should be up to a position where the intensity is 60%. The irradiated areas R1 and R2 may also overlap in the X direction.

[0064] Figure 5 shows an SEM (Scanning Electron Microscope) image of a polysilicon film formed by laser irradiation. Figure 5 also shows a schematic representation of the Y-direction position of the irradiated line corresponding to the SEM image. Figure 6 shows an EBSD (Electron Backscatter Diffraction) image obtained by analyzing the crystals of the polysilicon film. Specifically, the distribution of crystal orientation is shown by color. In other words, XY positions with the same crystal orientation are displayed in the same color. As shown in Figures 5 and 6, crystals can be formed that grow along the Y direction.

[0065] The amount of movement of the optical system 30 corresponding to the scanning time (one scan time) from one end to the other end of the optical scanner 32 is defined as the feed pitch p. By making the feed pitch p smaller than the crystal growth length r / 2, a polysilicon film that grows in one direction can be formed as shown in FIG.

[0066] Figure 7 is an SEM photograph showing the state in which the crystallized film formed in the first shot has been overwritten in the second shot. In the first shot, the crystals grow along the Y direction, but by being overwritten in the second shot, the crystal growth direction changes.

[0067] Device configuration example 1 The configuration of Device Configuration Example 1 will be described below. In Device Configuration Example 1, a semiconductor laser manufactured by LaserLine is used as the laser light source 21. The output of the laser light source 21 is 1000 W, and the laser wavelength (typical value) is 450 nm. The laser wavelength may be in the range of 400 to 500 nm. The diameter of the optical fiber 24 is 600 μm.

[0068] The beam shape on the substrate 100 is a rectangle of 600 μm×600 μm. The scanning speed v of the beam by the optical scanner 32 is 6 m / sec. The scanning range (scan length) d of the optical scanner 32 is 10 mm.

[0069] The step movement width dx of the stage 10 is set to a scanning range d=10 mm or less. The movement speed Vopt of the optical system 30 is set to 164 mm / sec by the optical system driver 40. Vopt is calculated using the following equation (2). Vopt=a / {d / v+(2*t)} (2)

[0070] The laser light L1 is irradiated onto the substrate 100 not only when the scanning direction of the optical scanner 32 is in the forward direction but also when the scanning direction is in the reverse direction.

[0071] Device configuration example 2 The configuration of Device Configuration Example 2 will be described below. In Device Configuration Example 2, the output of the laser light source 21 is 100 W, and the laser wavelength (typical value) is 450 nm. The laser wavelength may be in the range of 400 to 500 nm. The diameter of the optical fiber 24 is 100 μm.

[0072] The beam shape on the substrate 100 is a rectangle of 100 μm×100 μm. The scanning speed v of the beam by the optical scanner 32 is set to 6 m / sec. The scanning range (scan length) d of the optical scanner 32 is set to 10 mm.

[0073] The step movement width dx of the stage 10 is set to a scanning range d=10 mm or less. From the above formula (2), the optical system driving unit 40 moves the optical system 30 at a speed Vopt of 27 mm / sec.

[0074] (OLED display) The semiconductor device having the polysilicon film is suitable for a TFT (Thin Film Transistor) array substrate for an organic EL (ElectroLuminescence) display. That is, the polysilicon film is used as a semiconductor layer having a source region, a channel region, and a drain region of the TFT.

[0075] The following describes a configuration in which the semiconductor device according to this embodiment is applied to an organic EL display. Fig. 8 is a cross-sectional view showing a simplified pixel circuit of an organic EL display. The organic EL display 300 shown in Fig. 8 is an active matrix display device in which a TFT is arranged in each pixel PX.

[0076] The organic EL display 300 includes a substrate 310, a TFT layer 311, an organic layer 312, a color filter layer 313, and a sealing substrate 314. FIG. 8 shows a top-emission organic EL display in which the sealing substrate 314 side is the viewing side. Note that the following description shows one example of the configuration of an organic EL display, and the present embodiment is not limited to the configuration described below. For example, the semiconductor device according to the present embodiment may be used in a bottom-emission organic EL display.

[0077] The substrate 310 is a glass substrate or a metal substrate. A TFT layer 311 is provided on the substrate 310. The TFT layer 311 has a TFT 311a arranged in each pixel PX. The TFT layer 311 further has wiring (not shown) connected to the TFT 311a. The TFT 311a and the wiring constitute a pixel circuit.

[0078] An organic layer 312 is provided on the TFT layer 311. The organic layer 312 has an organic EL light emitting element 312a arranged for each pixel PX. Furthermore, the organic layer 312 is provided with partition walls 312b between the pixels PX to separate the organic EL light emitting elements 312a.

[0079] A color filter layer 313 is provided on the organic layer 312. The color filter layer 313 is provided with a color filter 313a for color display. That is, a resin layer colored in R (red), G (green), or B (blue) is provided in each pixel PX as the color filter 313a.

[0080] A sealing substrate 314 is provided on the color filter layer 313. The sealing substrate 314 is a transparent substrate such as a glass substrate, and is provided to prevent the organic EL light emitting elements of the organic layer 312 from deteriorating.

[0081] The current flowing through the organic EL element 312a of the organic layer 312 varies depending on the display signal supplied to the pixel circuit. Therefore, by supplying a display signal corresponding to the display image to each pixel PX, the amount of light emitted by each pixel PX can be controlled. This allows the desired image to be displayed.

[0082] In an active matrix display device such as an organic EL display, one pixel PX is provided with one or more TFTs (for example, a switching TFT or a driving TFT). The TFT of each pixel PX is provided with a semiconductor layer having a source region, a channel region, and a drain region. The polysilicon film according to this embodiment is suitable for the semiconductor layer of the TFT. That is, by using the polysilicon film manufactured by the above manufacturing method as the semiconductor layer of the TFT array substrate, it is possible to suppress in-plane variations in TFT characteristics. Therefore, it is possible to manufacture display devices with excellent display characteristics with high productivity.

[0083] (Method of manufacturing a semiconductor device) The method for manufacturing a semiconductor device using the heat treatment apparatus according to this embodiment is suitable for manufacturing a TFT array substrate. The method for manufacturing a semiconductor device having TFTs will be described with reference to Figs. 9 and 10. Figs. 9 and 10 are cross-sectional views showing the manufacturing process of a semiconductor device. In the following description, a method for manufacturing a semiconductor device having an inverted staggered TFT will be described. Figs. 9 and 10 show the step of forming a polysilicon film in the semiconductor manufacturing method. Note that, as known techniques can be used for the other manufacturing steps, their description will be omitted.

[0084] As shown in Fig. 9, a gate electrode 402 is formed on a glass substrate 401. A gate insulating film 403 is formed on the gate electrode 402. An amorphous silicon film 404 is formed on the gate insulating film 403. The amorphous silicon film 404 is disposed so as to overlap the gate electrode 402 with the gate insulating film 403 interposed therebetween. For example, the gate insulating film 403 and the amorphous silicon film 404 are successively formed by a CVD (Chemical Vapor Deposition) method.

[0085] Then, by irradiating the amorphous silicon film 404 with laser light L1, a polysilicon film 405 is formed as shown in Fig. 10. That is, the amorphous silicon film 404 is crystallized by the heat treatment apparatus 1 shown in Fig. 1 etc. As a result, a polysilicon film 405 made of crystallized silicon is formed on the gate insulating film 403. The polysilicon film 405 corresponds to the polysilicon film described above.

[0086] Furthermore, in the above description, the heat treatment apparatus according to this embodiment has been described as irradiating an amorphous silicon film with laser light to form a polysilicon film, but it may also be irradiating an amorphous silicon film with laser light to form a microcrystalline silicon film. Furthermore, the laser light is not limited to a semiconductor laser. The method according to this embodiment can also be applied to methods for crystallizing thin films other than silicon films. That is, the method according to this embodiment can be applied to any heat treatment apparatus that irradiates an amorphous film with laser light to form a crystallized film. The apparatus according to this embodiment can appropriately modify a substrate with a crystallized film.

[0087] The present invention is also applicable to a heat treatment apparatus for activating a semiconductor film on a silicon wafer, that is, the heat treatment apparatus 1 can activate the semiconductor film by irradiating the semiconductor film with laser light L1.

[0088] Variations A heat treatment method according to a modified example will be described with reference to Fig. 11. Fig. 11 is an XY plan view showing changes in the irradiation position of laser light L1 on substrate 100. In this modified example, the movement direction of stage 10 (arrow B) and the movement direction of optical system 30 (arrow C) are different from those in the configuration of Fig. 3.

[0089] 11, as in FIG. 3, the scanning direction of the optical scanner 32 is the direction of arrow A. Here, arrow A is parallel to the X direction. The optical scanner 32 moves the irradiation position of the laser light L1 along the +X direction. The movement direction of the optical system 30 by the optical system driver 40 is the direction of arrow C. In the XY plane view, arrow C is parallel to arrow A. For example, arrow C is parallel to the X direction. The movement direction of the stage 10 and the scanning direction of the optical scanner 32 are opposite directions. The irradiation position of the laser light L1 on the substrate 100 moves in the X direction by moving the optical system 30.

[0090] The direction of movement of the substrate 100 by the stage 10 is the direction of arrow B. In the XY plane view, arrow B is a direction that intersects with arrow C. For example, arrow B is a direction parallel to the Y direction. In other words, arrow B is a direction perpendicular to arrow A and perpendicular to arrow C. As the stage 10 moves, the irradiation position of the laser light L1 on the substrate 100 moves in the Y direction.

[0091] The optical scanner 32 changes the irradiation position of the laser light L1 in a first direction. By driving one of the optical system driver 40 and the stage 10, the irradiation position of the laser light L1 on the substrate 100 is changed relatively in a second direction. By driving the other of the optical system driver 40 and the stage 10, the irradiation position of the laser light L1 on the substrate 100 is changed relatively in a third direction. When viewed from above, the first direction and the second direction intersect. When viewed from above, the second direction and the third direction intersect. With this configuration, the same effect as above can be obtained.

[0092] The controller 50 may be configured with hardware such as a control circuit, or may be implemented with software such as a program executed by a processor. Some or all of the processing of the controller 50 described above may be performed by a computer program. The above-mentioned program includes a set of instructions (or software code) that, when loaded into a computer, causes the computer to perform one or more functions described in the embodiments. The program may be stored in a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable media or tangible storage media include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technology, CD-ROM, digital versatile disc (DVD), Blu-ray® disc or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage device. The program may also be transmitted on a transitory computer-readable medium or communication medium. By way of example and not limitation, transitory computer-readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals.

[0093] The present invention is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the invention.

[0094] This application claims priority based on Japanese Patent Application No. 2021-106779, filed on June 28, 2021, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0095] 1. Heat treatment equipment 10 stages 21 Laser light source 23 AO element 24 Optical Fiber 30 Optical system 31 Lens 32 Optical Scanner 33 fθ lens 40 Optical system drive unit 50 Controllers 100 boards 300 OLED display 310 Substrate 311 TFT layer 311a TFT 312 Organic layer 312a Organic EL light emitting device 312b Bulkhead 313 Color filter layer 313a Color filter (CF) 314 Sealing substrate 401 Glass substrate 402 gate electrode 403 Gate insulating film 404 Amorphous silicon film 405 Polysilicon film PX pixels

Claims

1. (A) generating a continuous wave laser beam and irradiating it into an optical system having a lens and an optical scanner provided on a substrate; (B) scanning the irradiation position of the laser light on the substrate held by a drive stage along a first direction by the optical scanner provided in the optical system; (C) moving the irradiation position of the laser light along a second direction intersecting the first direction in a plan view by moving one of the optical system or the drive stage; (D) A heat treatment method for a semiconductor device, comprising a step of moving the other of the optical system or the drive stage to move the irradiation position of the laser light along a third direction that intersects with the second direction in a planar view.

2. In the step (C), the optical system is moved, so that the irradiation position of the laser light is moved along the second direction; 2. The method of claim 1, wherein in step (D), the driving stage is moved to move the irradiation position of the laser light along the third direction.

3. In the step (C), the driving stage is moved, so that the irradiation position of the laser light is moved along the second direction; 2. The method of claim 1, wherein in step (D), the optical system is moved to move the irradiation position of the laser light along the third direction.

4. 4. The method for heat treatment of a semiconductor device according to claim 1, wherein the scanning speed of the optical scanner is faster than the moving speed of the optical system.

5. 5. The method for heat treatment of a semiconductor device according to claim 1, wherein the optical system is moved during scanning by the optical scanner.

6. the first direction and the third direction are parallel to each other in a plan view, After the optical system moves relatively from one end to the other end of the substrate, the driving stage moves the irradiation position in a third direction; 6. The heat treatment method for a semiconductor device according to claim 1, wherein after the driving of the driving stage is completed, the optical scanner scans the laser light, thereby irradiating the laser light onto the substrate again.

7. 7. The method for heat treatment of a semiconductor device according to claim 1, wherein the laser light is not irradiated onto the substrate at the scanning end of the optical scanner.

8. the optical scanner reciprocates in a forward direction from one end of a scanning range to the other end and in a reverse direction from the other end to the one end, the laser light is irradiated onto the substrate while the optical scanner is operating in the forward direction; While the optical scanner is operating in the reverse direction, the laser light is blocked, the laser light is incident on the optical system via an optical fiber, 8. The heat treatment method for a semiconductor device according to claim 1, wherein a deflector deflects the laser light incident on the optical fiber, thereby switching between irradiation and blocking of the laser light.

9. a laser light source that generates continuous wave laser light; an optical system provided on a substrate, the optical system including a lens and an optical scanner that scans the laser light along a first direction, and that guides the laser light to the substrate; an optical system driving unit that moves the optical system so that the irradiation position of the laser light on the substrate changes; a drive stage that holds the substrate and moves the irradiation position of the laser light, driving one of the optical system driving unit and the driving stage to change the irradiation position of the laser light along a second direction intersecting with a first direction in a plan view; The heat treatment apparatus for semiconductor devices, wherein the irradiation position of the laser light is changed along a third direction intersecting the second direction in the plan view by driving the other of the optical system driving unit or the driving stage.

10. the optical system driving unit is driven to move the irradiation position of the laser light along the second direction, 10. The heat treatment apparatus for semiconductor devices according to claim 9, wherein the irradiation position of the laser light is moved along the third direction by driving the driving stage.

11. the optical system driving unit is driven to move the irradiation position of the laser light along the third direction, 10. The heat treatment apparatus for semiconductor devices according to claim 9, wherein the irradiation position of the laser light is moved along the second direction by driving the driving stage.

12. 12. The heat treatment apparatus for semiconductor devices according to claim 9, wherein the scanning speed of said optical scanner is faster than the moving speed of said optical system.

13. 13. The heat treatment apparatus for a semiconductor device according to claim 9, wherein the optical system is moved during scanning by the optical scanner.

14. the first direction and the third direction are parallel to each other in a plan view, After the optical system moves relatively from one end to the other end of the substrate, the driving stage moves the irradiation position in a third direction; 14. The heat treatment apparatus for a semiconductor device according to claim 9, wherein after driving of the driving stage is completed, the optical scanner scans the laser light, thereby irradiating the laser light again onto the substrate.

15. 15. The heat treatment apparatus for a semiconductor device according to claim 9, wherein the laser light is not irradiated onto the substrate at the scanning end of the optical scanner.

16. the optical scanner reciprocates in a forward direction from one end of a scanning range to the other end and in a reverse direction from the other end to the one end, the laser light is irradiated onto the substrate while the optical scanner is operating in the forward direction; the laser beam is blocked while the optical scanner is operating in the reverse direction; the laser light is incident on the optical system via an optical fiber, 16. The heat treatment apparatus for a semiconductor device according to claim 9, wherein a deflector deflects the laser light incident on the optical fiber, thereby switching between irradiation and blocking of the laser light.

17. (SA) generating continuous wave laser light and irradiating it into an optical system having a lens and an optical scanner provided on a substrate; (SB) a step in which the optical scanner provided in the optical system scans the irradiation position of the laser light on the substrate held by a drive stage along a first direction; (SC) moving one of the optical system and the driving stage to move the irradiation position of the laser light on the substrate along a second direction intersecting the first direction in a plan view; (SD) A method for manufacturing a semiconductor device, comprising a step of moving the other of the optical system or the drive stage to move the irradiation position of the laser light on the substrate along a third direction that intersects the second direction in a planar view.

18. In the step (SC), the optical system is moved, so that the irradiation position of the laser light is moved along the second direction; 18. The method for manufacturing a semiconductor device according to claim 17, wherein in the step (SD), the driving stage is moved, thereby moving the irradiation position of the laser light along the third direction.

19. In the step (SC), the driving stage is moved to move the irradiation position of the laser light along the second direction, 18. The method for manufacturing a semiconductor device according to claim 17, wherein in the step (SD), the optical system is moved to move the irradiation position of the laser light along the third direction.

20. 20. The method for manufacturing a semiconductor device according to claim 17, wherein the scanning speed of the optical scanner is faster than the moving speed of the optical system.

21. 21. The method for manufacturing a semiconductor device according to claim 17, wherein the optical system is moved during scanning by the optical scanner.

22. the first direction and the third direction are parallel to each other in a plan view, After the optical system moves relatively from one end to the other end of the substrate, the driving stage moves the irradiation position in a third direction; 22. The method for manufacturing a semiconductor device according to claim 17, wherein after driving of the driving stage is completed, the optical scanner scans the laser light, thereby irradiating the laser light onto the substrate again.

23. 23. The method for manufacturing a semiconductor device according to claim 17, wherein the laser light is not irradiated onto the substrate at the scanning end of the optical scanner.

24. the optical scanner reciprocates in a forward direction from one end of a scanning range to the other end and in a reverse direction from the other end to the one end, the laser light is irradiated onto the substrate while the optical scanner is operating in the forward direction; the laser beam is blocked while the optical scanner is operating in the reverse direction; the laser light is incident on the optical system via an optical fiber, 24. The method for manufacturing a semiconductor device according to claim 17, wherein a deflector deflects the laser light incident on the optical fiber, thereby switching between irradiation and blocking of the laser light.

25. When the substrate is irradiated with the laser light, the amorphous film on the substrate is crystallized to form a crystallized film. The method for manufacturing a semiconductor device according to any one of claims 17 to 24.

26. 25. The method for manufacturing a semiconductor device according to claim 17, wherein a semiconductor film on the substrate is activated by irradiating the substrate with the laser light.

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