Laser annealing method and device

Abstract

The invention relates to the field of semiconductor chip manufacturing, and provides a laser annealing method and device.According to the scheme, laser is provided, and the laser can form a strip-shaped or linear irradiation area extending in the first direction on a substrate; laser is used for carrying out overlapped stepping pulse irradiation on the substrate in the second direction so as to carry out laser annealing on the substrate, the second direction is perpendicular to the first direction, and the step length between different periods of the substrate in the second direction is reduced, so that when laser beam energy is used for carrying out multiple times of laser irradiation on the substrate in a certain period, the laser annealing time is shortened; the overlapped part of the laser beam energy irradiated on the substrate is adjusted, so that the low-energy part of the laser beam is converted into high energy on the substrate, the crystallization effect of the laser beam on the substrate is kept consistent with the crystallization effect of the high-energy part of the laser beam, the crystallization height on the substrate is uniform, the production process effect of a chip is improved, and the production cost is reduced. And the process window is widened.

Description

Technical Field

[0001] The present application relates to the field of semiconductor chip manufacturing, and in particular to a laser annealing method and device. Background Art

[0002] In the process of chip or panel production, laser annealing (also known as LaserAnneal) of the substrate (such as wafer) to crystallize amorphous silicon (ASI) is an important process. In the laser annealing process, in order to make the crystallization degree of ASI uniform enough, the laser beam energy of the laser needs to be transferred to the substrate uniformly enough. However, the laser beam energy distribution (also known as Beam Profile) generated by the existing laser is not uniform, resulting in different laser beam energies at different positions on the substrate when the substrate is laser irradiated, and the change in the degree of crystallization is more obvious at the lower energy position on the substrate than at the higher energy position (that is, the size of the grains at the low energy position is much larger than the size of the grains at the high energy position), resulting in uneven crystallization on the final substrate and a narrowing of the process window (also known as process window).

[0003] In summary, there is an urgent need for a laser annealing solution that can make the crystals on the substrate sufficiently uniform. Summary of the invention

[0004] The present application provides a laser annealing method and device to solve the problem of uneven crystallization caused by uneven laser irradiation of a substrate with laser beam energy.

[0005] A first aspect of the present application provides a laser annealing method, the method comprising:

[0006] Providing a laser, wherein the laser can form a stripe-shaped or line-shaped irradiation area extending along a first direction on the substrate;

[0007] The substrate is irradiated with overlapping step pulses along a second direction using a laser to perform laser annealing on the substrate, wherein the second direction is perpendicular to the first direction; wherein:

[0008] The irradiation area has a preset width w along the second direction, and the irradiation area includes a first area, a middle area, and a second area arranged in the second direction, the laser has a uniform energy distribution in the middle area, and the laser has an energy distribution that attenuates in the first area and the second area in a direction away from the middle area;

[0009] Using laser to perform overlapping step pulse irradiation on the substrate along the second direction, including relatively moving the irradiation area and the substrate with a preset step length: the preset step length in a cycle is a first step length m; one step is included between two adjacent cycles, and the preset step length between two adjacent cycles is a second step length; the second step length is smaller than the first step length, and the second step length is greater than the width of any one of the first area and the second area in the second direction;

[0010] There exists a positive integer N such that w=N×m, the cycle includes X times of the pulse irradiation, and X is an integer multiple of N.

[0011] In some embodiments of the present application, X=N.

[0012] In some embodiments of the present application, the first region and the second region have a first width and a second width along the second direction, and a difference between the first step length and the second step length is greater than or equal to the sum of the first width and the second width.

[0013] In some embodiments of the present application, the irradiation area and the substrate are relatively moved with a preset step length, including:

[0014] During the period, the substrate moves uniformly at a first speed;

[0015] Between adjacent cycles, an average speed of the substrate is a second speed, which is less than the first speed.

[0016] In some embodiments of the present application, the substrate includes amorphous silicon.

[0017] A second aspect of the present application provides a laser annealing device, the device comprising:

[0018] A stage for placing a substrate;

[0019] A laser, used to generate laser light, wherein the laser light can form a stripe-shaped or linear irradiation area extending along a first direction on a substrate, wherein the irradiation area has a preset width along a second direction, wherein the irradiation area includes a first area, a middle area, and a second area arranged in the second direction, wherein the laser light has a uniform energy distribution in the middle area, and wherein the laser light has an energy distribution that attenuates in the first area and the second area in a direction away from the middle area;

[0020] A controller, the stage and the laser are both connected to the controller, the controller can control the laser to generate pulsed laser, and the controller can control the stage to move along the second direction, so as to use the laser to perform overlapping step-by-step pulse irradiation on the substrate along the second direction, and perform laser annealing on the substrate;

[0021] Using laser to perform overlapping step pulse irradiation on the substrate along the second direction, including relatively moving the irradiation area and the substrate with a preset step length: the preset step length in a cycle is the first step length; one step is included between two adjacent cycles, and the preset step length between two adjacent cycles is the second step length; the second step length is smaller than the first step length, and the second step length is larger than the width of any one of the first area and the second area in the second direction;

[0022] There exists a positive integer N such that w=N×m, a cycle includes X pulse irradiations, and X is an integer multiple of N.

[0023] In some embodiments of the present application, the first region and the second region have a first width and a second width along the second direction, and a difference between the first step length and the second step length is greater than or equal to the sum of the first width and the second width.

[0024] In some embodiments of the present application, the irradiation area and the substrate are relatively moved with a preset step size, including a controller capable of controlling the variable speed movement of the stage so that within a cycle, the substrate moves at a uniform speed at a first speed, and between adjacent cycles, the average speed of the substrate is a second speed, and the second speed is less than the first speed.

[0025] In some embodiments of the present application, X=N.

[0026] In some embodiments of the present application, the controller is capable of adjusting at least one of a preset step length, a preset width, a first width, and a second width.

[0027] This application has the following beneficial effects:

[0028] The solution of the present application is: providing a laser, the laser can form a strip or line irradiation area extending along a first direction on a substrate; using the laser to perform overlapping step-by-step pulse irradiation on the substrate along a second direction to perform laser annealing on the substrate, the second direction is perpendicular to the first direction, and the step length between different periods of the substrate along the second direction is reduced, so that when the laser beam energy performs multiple laser irradiations on the substrate within a certain period, the overlapping part of the laser beam energy irradiated on the substrate is adjusted, thereby converting the low-energy part of the laser beam into high energy on the substrate, so that its crystallization on the substrate is consistent with the crystallization effect of the high-energy part of the laser beam, achieving highly uniform crystallization on the substrate, thereby improving the production process effect of the chip and widening the process window. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings herein are incorporated into the specification and constitute a part of the specification. These drawings illustrate embodiments consistent with the present application and are used together with the specification to illustrate the technical solution of the present application.

[0030] Figure 1 It is a schematic diagram of the relationship between the two crystallization mechanisms and the laser annealing energy provided in this application;

[0031] Figure 2 It is a schematic diagram of a first example of a laser annealing solution of the prior art provided by the present application;

[0032] Figure 3 is a second exemplary schematic diagram of a laser annealing solution of the prior art provided by the present application;

[0033] Figure 4 This is a schematic diagram of laser energy distribution of the laser annealing scheme of the prior art provided by the present application;

[0034] Figure 5 It is a schematic diagram of laser annealing energy of the laser annealing scheme of the prior art provided by the present application;

[0035] Figure 6 It is a schematic diagram of the total energy of laser annealing in the laser annealing scheme of the prior art provided by the present application;

[0036] Figure 7 It is a schematic flow chart of the first embodiment of the laser annealing method provided by the present application;

[0037] Figure 8 This is a schematic diagram of laser annealing energy in the second embodiment of the laser annealing solution provided by the present application;

[0038] Fig. 9 This is a schematic diagram of laser annealing energy in the third embodiment of the laser annealing solution provided by the present application;

[0039] Fig.10 It is a schematic diagram of the framework of an embodiment of the laser annealing device provided in the present application. DETAILED DESCRIPTION

[0040] The scheme of the embodiment of the present application is described in detail below in conjunction with the drawings of the specification.

[0041] In the following description, for the purpose of explanation rather than limitation, specific details such as specific system structures, interfaces, and technologies are provided to facilitate a thorough understanding of the present application.

[0042] The term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the objects associated before and after are in an "or" relationship. In addition, "many" in this article means two or more than two. In addition, the term "at least one" in this article means any combination of at least two of any one or more of a plurality of, for example, including at least one of A, B, and C, can mean including any one or more elements selected from the set consisting of A, B, and C.

[0043] As described in the background technology, the energy distribution of the laser beam (also called BeamProfile) generated by the existing laser is not uniform, resulting in different laser beam energies received by different positions on the substrate when the substrate is irradiated with the laser. The change in the degree of crystallization is more obvious at positions with lower energy than at positions with higher energy on the substrate (that is, the size of the grains at low energy locations is much larger than the size of the grains at high energy locations), resulting in uneven crystallization on the final substrate and a narrowing of the process window (also called process window).

[0044] The reasons why the existing laser annealing method leads to uneven crystallization on the substrate are explained below in combination with the laser annealing crystallization principle and related drawings.

[0045] In the laser annealing of amorphous silicon, there are two main mechanisms for the crystallization principle: heterogeneous nucleation temperature point (also known as solid phase crystallization temperature point) and spontaneous nucleation temperature point. Among them, the heterogeneous nucleation temperature point is easier to crystallize at impurities or defects, so the required temperature is lower; the spontaneous nucleation temperature point does not depend on impurities or defects, so the temperature requirement is higher, that is, the spontaneous nucleation temperature point is higher than the heterogeneous nucleation temperature point. Among them, crystallization occurs at the spontaneous nucleation temperature point and the heterogeneous nucleation temperature point, and small grains can be formed. In the process of gradually rising from the heterogeneous nucleation temperature point to the spontaneous nucleation temperature point, as the temperature increases, the grain size after crystallization first increases and then decreases, that is, crystallization at the intermediate temperature point between the spontaneous nucleation temperature point and the heterogeneous nucleation temperature point will form large grains, and their grain size is larger than the grains formed by crystallization at the spontaneous nucleation temperature point and the heterogeneous nucleation temperature point.

[0046] Generally, the temperature of laser annealing is selected above the spontaneous nucleation temperature. When the temperature becomes lower, the crystallization mechanism changes, spontaneous nucleation will be greatly reduced, and at the intermediate temperature between the spontaneous nucleation temperature and the heterogeneous nucleation temperature, the grain size loses its constraint and changes suddenly (becomes larger); when the temperature becomes higher, the crystallization mechanism does not change, and the grain size does not change suddenly. For example, Figure 1 FIG. 1 shows an example of the energy distribution in the laser irradiation area during the laser pulse irradiation annealing process for the simultaneous formation of spontaneous nucleation temperature points and heterogeneous nucleation temperature points in amorphous silicon. Figure 1-4It can be seen that the laser pulse can form a strip or line irradiation area extending along the first direction on the surface of amorphous silicon, and its energy distribution along the second direction is trapezoidal or approximately trapezoidal (the second direction is perpendicular to the first direction), including a high-energy uniform portion (middle zone) located in the middle, and energy attenuation portions (first zone, second zone) located on both sides. When the substrate is laser annealed, the amorphous silicon is heated by the laser in the high-energy uniform portion, and the temperature is at the spontaneous nucleation temperature point. The amorphous silicon is heated by the laser in the lower energy portion of the energy attenuation portion, and the temperature is at the heterogeneous nucleation temperature point. At the spontaneous nucleation temperature point and the heterogeneous nucleation temperature point, amorphous silicon crystallization will form uniform small grains of uniform size on the substrate. However, when the amorphous silicon is heated by the laser in the medium energy portion of the energy attenuation portion, and the temperature is at the middle temperature point between the spontaneous nucleation temperature point and the heterogeneous nucleation temperature point, large grains are easily formed.

[0047] like Figures 2 to 5 The following is a schematic diagram of an example of a laser annealing method in the prior art, wherein the laser annealing method includes:

[0048] Provide a light source (for example, see Figure 2 As shown by the arrow (1) in FIG. 1 ), the light source can emit laser light, and the laser light can be applied to a substrate (e.g., a wafer, for example, as shown in FIG. 1 ). Figure 2 The first direction is formed on the surface of the substrate (as shown by the arrow (2) in FIG. 1 ) (the first direction is exemplified by referring to FIG. Figure 2 The strip or line irradiation area extending from the irradiation area (as shown by the arrow (4) in FIG. Figure 2 As shown by the arrow (3) in Figure 3 As shown by the arrow (6) in the figure, the laser forms an isosceles trapezoidal energy distribution in the irradiated area, which are respectively the first zone (the first zone example is shown in FIG. Figure 3 As shown by the arrow (1) in the figure), the middle area (the middle area example is shown in FIG. Figure 3 As shown by the arrow (3) in FIG. 1 ) and the second zone (the second zone is shown in FIG. Figure 3 As shown by the arrow (2) in FIG. 1 ), the energy distribution in the middle region is uniform, and the first region and the second region have energy distributions that decay in a direction away from the middle region (for example, see FIG. Figure 4 The substrate is irradiated with overlapping step pulses along the second direction using a laser (for an example of overlapping step pulse irradiation, refer to FIG. Figure 5 As shown), the irradiation area and the substrate are relatively moved at a constant preset step length m.

[0049] In the prior art, it is approximately considered that the energy of the laser irradiation in the second direction is uniform. In this prior art example, the width of the irradiation area in the second direction is w, and w is an integer multiple of the preset step length m, so that the energy of the laser irradiation on the entire substrate surface is uniformly distributed. However, after the laser annealing method, due to the existence of the first area and the second area, the total energy distribution of the energy corresponding to the laser in each area on the substrate is as follows: Figure 6 As shown, from Figure 5 , 6 It can be seen that the energy density in the p region on the substrate is significantly greater than the energy density in the q region on the substrate (the p region is irradiated by the laser of the high energy uniform part 4 times, and the q region is irradiated by the laser 5 times, but including 3 times of laser irradiation of the high energy uniform part and 2 times of laser irradiation of the energy attenuation part, the total irradiation energy is lower than that of the p region). In the amorphous silicon annealing crystallization process, the energy of the p region is configured to make the amorphous silicon reach the spontaneous nucleation temperature point to form small grains in the irradiation area corresponding to the p region, while the energy of the q region will make the amorphous silicon reach the intermediate temperature point between the spontaneous nucleation temperature point and the heterogeneous nucleation temperature point, thereby forming large grains in the irradiation area corresponding to the q region. As a result, the uniformity of crystallization is reduced.

[0050] The inventor has found through research that the current method to solve the uneven crystallization on the substrate is that each laser generator manufacturer continuously improves the uniformity of the laser energy distribution in the irradiated area, but the optical path system cannot make the laser energy distribution perfect. It can only reduce the low energy part (i.e., the first area and the second area) as much as possible to make the laser energy distribution closer to a rectangle, and cannot completely eliminate the low energy part of the laser energy distribution. As long as there is a low energy part in the laser energy distribution, the laser will overlap and step pulse on the substrate, and uneven crystallization will occur.

[0051] At the same time, since the width of the low-energy part in the second direction is very narrow, it is difficult to accurately achieve the overlap of the first zone and the second zone between two pulses in a row of step-by-step pulse scanning without adjusting the laser energy distribution (for example, adjusting the width of the first zone and the second zone). Adjusting the laser energy distribution requires adjusting the optical path system of the laser, which is difficult and costly, and the adjustment range is limited. When the step length of each step is reduced and the laser pulse energy is reduced to eliminate the q area, the number of laser irradiations will increase and the production efficiency will be reduced. The matching between the laser pulse energy and the step length will increase the difficulty of process control, and the q area cannot be completely eliminated. Moreover, since the laser irradiation energy adjustment range of the laser is limited, the adjustment of the laser pulse energy may increase the equipment cost.

[0052] In order to solve the above problems, the present application proposes a new laser annealing scheme. In the scheme of the present application, the step length between different periods (one period includes multiple steps) of the substrate along the second direction is reduced, so that when the laser beam energy irradiates the substrate multiple times within a certain period, the overlapping (also called Over l ap) part of the laser beam energy irradiated on the substrate is adjusted, thereby reducing or eliminating the q region and improving the uniformity of laser annealing crystallization; at the same time, the impact on the p region is small, so there is no need to adjust the energy of the laser pulse; further, since the step length is adjusted every other period, the number of laser irradiations is not significantly increased, and the impact on production efficiency is relatively low.

[0053] According to one embodiment of the present application, the present application provides a laser annealing method, such as Figure 7 As shown, the method includes:

[0054] S1. Provide a laser, wherein the laser can form a stripe or line irradiation area extending along a first direction on the substrate;

[0055] S2. Use laser to perform overlapping step pulse irradiation on the substrate along a second direction to perform laser annealing on the substrate, where the second direction is perpendicular to the first direction.

[0056] Specifically, the irradiation area has a preset width along the second direction, the irradiation area includes a first area, a middle area and a second area arranged in the second direction, the laser has a uniform energy distribution in the middle area, and the laser has an energy distribution that attenuates in the first area and the second area in a direction away from the middle area;

[0057] Using laser to perform overlapping step pulse irradiation on the substrate along the second direction, including relatively moving the irradiation area and the substrate with a preset step length: the preset step length in a cycle is the first step length; one step is included between two adjacent cycles, and the preset step length between two adjacent cycles is the second step length; the second step length is smaller than the first step length, and the second step length is larger than the width of any one of the first area and the second area in the second direction;

[0058] There exists a positive integer N such that w=N×m, a cycle includes X times of the pulse irradiation, and X is an integer multiple of N.

[0059] The preset step length corresponds to the step pulse irradiation one by one, that is, the irradiation area and the substrate are relatively moved once according to the preset step length, and the laser irradiates the substrate once. It can be understood that multiple steps are performed within a cycle, and the preset step length of each step is the first step length; between adjacent cycles, one step can be performed, and the preset step length is the second step length.

[0060] The above embodiment of the present application divides the movement of the substrate during the crystallization process into multiple cycles based on the number of irradiation steps of the laser energy on the substrate along the second direction, and sets the second step length of the movement between the cycles to be smaller than the first step length of the movement within the cycle. This method adjusts the overlapping (also called Over l ap) part of the laser beam energy irradiated on the substrate. Since the second step length is smaller than the first step length, the irradiation area of ​​the second cycle and other cycles after the second cycle are all close to the first cycle, thereby reducing or even eliminating the q region, that is, reducing the low energy region and improving the uniformity of laser annealing.

[0061] It can be understood that each cycle includes X laser pulse irradiations. Since X is an integer multiple of N and w is N times of m, when the preset step length is always m, the X+1th to X+Nth laser irradiations must form a q region, i.e., a lower energy region, one by one with the X-N+1th to Xth laser irradiations in the previous X laser irradiations. The present application makes the second step length smaller than the first step length, so that the laser irradiation in the next cycle overlaps with the laser irradiation in the previous cycle, thereby reducing or eliminating the q region. At the same time, by controlling the second step length to be larger than any of the widths of the first and second regions, the p region is prevented from being reduced to 0, resulting in an excessively high annealing temperature, and the increase in process difficulty and cost caused by the laser energy adjustment is also avoided. Furthermore, since the first step length of the step within the cycle remains unchanged, the increase in the number of step lengths caused by the step length adjustment is reduced, and the laser pulse energy adjustment caused by the step length adjustment is avoided, thereby reducing the process difficulty and production cost.

[0062] In a preferred embodiment, still referring to Figure 4 As shown, the first region and the second region have a first width a and a second width b along the second direction, and the difference between the first step length and the second step length is greater than or equal to the sum of the first width a and the second width b. Since the width of the q region is the sum of the first width a and the second width b, when the second step length is reduced by at least (a+b) relative to the first step length, the q region can be completely eliminated, thereby making the laser annealing uniform. It can be understood that when the first width and the second width are narrow, making the difference between the first step length and the second step length greater than the sum of the first width and the second width can reduce the difficulty of controlling the preset step length.

[0063] In a preferred embodiment, X = N. Thus, each laser pulse in a subsequent cycle can overlap with the corresponding pulse in a previous cycle, thereby reducing or eliminating each q region and improving the uniformity of laser annealing.

[0064] In a preferred embodiment, the difference between the first step length and the second step length is greater than or equal to the sum of the first width a and the second width b, and X=N, thereby achieving elimination of each q region and improving the uniformity of laser annealing.

[0065] The following will combine Figure 2-4 , 8-9, illustrate the best implementation method of the present application and its technical effects.

[0066] In step S1, the method of providing laser is as follows Figure 2-4 As shown, it is the same as the prior art.

[0067] Specifically, combined Figure 4 It can be seen that the laser pulse can form a strip or line irradiation area extending along the first direction on the amorphous silicon surface, and its energy distribution along the second direction is trapezoidal or approximately trapezoidal, including a high-energy uniform portion (middle area) located in the middle, and energy attenuation portions (first area, second area) located on both sides. In the second direction, the preset width of the irradiation area is w, the width of the first area is a, and the width of the second area is b. In this embodiment, in the irradiation area, the energy distribution of the laser along the second direction is an isosceles trapezoid, that is, a=b.

[0068] In this embodiment, the substrate includes amorphous silicon, and the laser annealing method is used to anneal the amorphous silicon so as to crystallize the amorphous silicon and form polycrystalline silicon.

[0069] Figure 5 In the prior art shown, between the first period and the second period, the first laser pulse of the first period is adjacent to the first laser pulse of the second period at the end thereof to form a q region, and the second to fourth pulses are the same.

[0070] In step S2 of this embodiment, Figure 8 In the illustrated embodiment, the first step length is m, w=4m, a=b; in one cycle, 4 step pulses are executed, that is, X=N=4, and between adjacent cycles, the second step length is m-2a.

[0071] The second step length between the first cycle and the second cycle is m-2a, so that the left end of each laser pulse in the first cycle overlaps with the right end of a corresponding laser pulse in the second cycle. Specifically, the left end of each laser pulse in the first cycle overlaps with the middle area of ​​a corresponding laser pulse in the second cycle, thereby eliminating the q region with low laser irradiation density and improving the uniformity of laser annealing.

[0072] This embodiment ( Figure 8 ) shows a technical solution, compared with the prior art ( Figure 5 ) can eliminate all q regions, keep the total laser irradiation energy on the remaining p regions unchanged, and at the same time form an r region with a laser irradiation energy higher than that of the p region.

[0073] In this embodiment, after shortening the preset step length between cycles, the width of the portion of the original p region where the laser irradiation energy is uniform along the second direction is reduced, and the total laser irradiation energy in the region where the left end of the first laser pulse of the first cycle overlaps with the middle region of the first laser pulse of the second cycle is increased to be greater than the total laser irradiation energy of the original p region, forming an r region. Based on the foregoing, it can be seen that since the laser irradiation energy of the original p region is usually configured to be slightly higher than the spontaneous nucleation temperature point, after eliminating the q region in this embodiment, an r region with a temperature higher than the p region is also formed, but increasing the temperature will not cause the uniformity of the crystal grain size to decrease. In addition, since the widths of the first and second regions are narrower, the width of the p region is reduced to a smaller extent, and the region where the left end of the first laser pulse of the first cycle overlaps with the middle region of the first laser pulse of the second cycle is also smaller, which has less impact on the temperature in the overall laser annealing. In this way, the uniformity of laser annealing can be improved while avoiding the adjustment of the laser pulse energy, reducing the process cost and process difficulty.

[0074] See also Fig. 9 In the embodiment shown, the first step length is m, w=4m, a=b; in one cycle, 4 step pulses are executed, and between adjacent cycles, the second step length is a, and the p region (the p region is Fig. 9 The width of the thick dashed line is 0, which leads to the excessively high laser annealing temperature of the substrate (e.g. Fig. 9 The temperature in the middle s region is too high), so it is necessary to make m>a and m>b.

[0075] In some embodiments, the substrate moves at a constant speed and the laser is pulsed for irradiation. Since the laser pulse irradiation time is short each time, it is approximately considered that the substrate is stationary during the laser irradiation, thus forming overlapping step-by-step pulse irradiation. The second step length can be made smaller than the first step length by adjusting the interval between laser pulse irradiations.

[0076] The above-mentioned embodiments of the present application can reduce the difficulty of controlling the relative movement between the substrate and the irradiation area, and realize precise control and repeatability of the laser irradiation position each time, thereby ensuring the consistency of overlap between adjacent irradiation areas and the uniformity of the entire processed surface, and improving the uniformity of crystallization on the substrate.

[0077] In some embodiments, the substrate moves in a pulsed manner. During laser pulse irradiation, the substrate and the irradiation area are relatively still. After the laser is turned off, the substrate moves according to a preset step length. After one movement is completed, the laser is turned on and the irradiation area and the substrate are relatively still. The above actions are repeated to form overlapping step-by-step pulse irradiation.

[0078] The above-mentioned embodiments of the present application can precisely pause and adjust the position after each laser irradiation, ensuring that each irradiation point receives sufficient and consistent energy input, while the overlap between adjacent irradiation areas is more precisely controllable, effectively avoiding the dynamic errors that may be caused by continuous movement, ensuring the consistency and repeatability of the processing, thereby improving the uniformity of crystallization on the substrate. In addition, the pulsed movement allows self-correction after each movement, enhancing the flexibility and adaptability of the processing process.

[0079] In some embodiments, the laser is pulsed and the substrate moves at a variable speed. Since the laser pulse has a short irradiation time each time, it is approximately considered that the substrate is stationary during the laser irradiation, thus forming an overlapping step-by-step pulse irradiation. The second step length can be made smaller than the first step length by adjusting the movement speed of the substrate, for example: the substrate maintains a uniform motion within each cycle, and the substrate movement speed decreases between each cycle. Specifically, the irradiation area and the substrate are relatively moved with a preset step length, including variable speed motion, that is, within a cycle, the substrate moves at a uniform speed at a first speed, and between adjacent cycles, the average speed of the substrate is a second speed, and the second speed is less than the first speed. Optionally, the substrate moves continuously.

[0080] The above-mentioned embodiments of the present application can reduce the difficulty of controlling the light source, reduce the difficulty of controlling the relative movement between the substrate and the irradiation area, and at the same time reduce the impact of the change of motion-stationary state on the substrate during the relative movement between the substrate and the irradiation area.

[0081] But not limited to this, in some embodiments, the substrate remains stationary and the irradiation area of ​​the laser pulse moves, for example, the light source moves at a uniform speed, at a variable speed, or in a pulsed manner, and similarly to the above, overlapping step-by-step pulse irradiation can be achieved.

[0082] The present application does not specifically limit the mode of relative movement between the substrate and the irradiation area, as long as the laser can perform overlapping step-by-step pulse irradiation of the substrate along the second direction, and the second step length is smaller than the first step length, and the second step length is larger than the width of any one of the first area and the second area in the second direction.

[0083] In addition, according to one embodiment of the present application, the present application provides a laser annealing device, such as Fig.10 As shown, the device comprises:

[0084] A stage for placing a substrate;

[0085] A laser, used to generate laser light, wherein the laser light can form a stripe-shaped or linear irradiation area extending along a first direction on a substrate, wherein the irradiation area has a preset width along a second direction, wherein the irradiation area includes a first area, a middle area, and a second area arranged in the second direction, wherein the laser light has a uniform energy distribution in the middle area, and wherein the laser light has an energy distribution that attenuates in the first area and the second area in a direction away from the middle area;

[0086] A controller, the stage and the laser are both connected to the controller, the controller can control the laser to generate pulsed laser, and the controller can control the stage to move along the second direction, so as to use the laser to perform overlapping step-by-step pulse irradiation on the substrate along the second direction, and perform laser annealing on the substrate;

[0087] Using laser to perform overlapping step pulse irradiation on the substrate along the second direction, including relatively moving the irradiation area and the substrate with a preset step length: the preset step length in a cycle is the first step length; one step is included between two adjacent cycles, and the preset step length between two adjacent cycles is the second step length; the second step length is smaller than the first step length, and the second step length is larger than the width of any one of the first area and the second area in the second direction;

[0088] There exists a positive integer N such that w=N×m, a cycle includes X pulse irradiations, and X is an integer multiple of N.

[0089] The above-mentioned embodiments of the present application realize precise coordinated control of the carrier and the laser through a controller, thereby realizing the aforementioned method, which will not be repeated here.

[0090] The controller can control at least one of the switching frequency of laser irradiation and the movement of the stage to achieve relative movement of the irradiation area and the substrate with a preset step size. For example, the various embodiments described above have the same technical effects and will not be repeated here.

[0091] It can be understood that, compared with controlling the energy distribution of laser light emitted by the laser, or controlling the pulse frequency of the laser, it is relatively simple to control the movement of the stage. Therefore, in a preferred embodiment, the controller can control the stage to perform the variable speed movement described above, so as to achieve relative movement of the irradiation area and the substrate with a preset step length. Specifically, the controller can control the variable speed movement of the stage so that within a cycle, the substrate moves at a uniform speed of a first speed, and between adjacent cycles, the average speed of the substrate is a second speed, and the second speed is less than the first speed.

[0092] According to one embodiment of the present application, the controller can adjust at least one of the preset step length, the preset width, the first width and the second width. For example, the controller adjusts the preset step length according to the first width, the second width and the preset width of the laser emitted by the laser to implement the above method.

[0093] According to a preferred embodiment of the present application, the laser annealing device can control X=N, and / or the difference between the first step length and the second step length is greater than or equal to the sum of the first width and the second width.

[0094] In summary, compared with the existing method of using laser to perform overlapping step-by-step pulse irradiation on the substrate along the second direction, and using a constant step size to relatively move the irradiation area and the substrate, the present application reduces the step size between different periods of the substrate along the second direction. This allows the laser beam energy to adjust the overlapping part of the laser beam energy irradiated on the substrate when the substrate is irradiated with the laser multiple times within a certain period, thereby converting the low-energy part of the laser beam into high energy on the substrate, so that its crystallization on the substrate is consistent with the crystallization effect of the high-energy part of the laser beam, achieving highly uniform crystallization on the substrate, thereby improving the production process effect of the chip and widening the process window.

Claims

1. A laser annealing method, characterized in that: The method comprises: Providing a laser, wherein the laser can form a stripe-shaped or line-shaped irradiation area extending along a first direction on the substrate; The laser is used to perform overlapping step pulse irradiation on the substrate along a second direction to perform laser annealing on the substrate, wherein the second direction is perpendicular to the first direction; wherein: The irradiation area has a preset width w along the second direction, the irradiation area includes a first area, a middle area and a second area arranged in the second direction, the laser has a uniform energy distribution in the middle area, and the laser has an energy distribution that attenuates in the first area and the second area in a direction away from the middle area; The step-by-step pulse irradiation of the substrate along the second direction by using the laser in an overlapping manner comprises relatively moving the irradiation area and the substrate with a preset step length: the preset step length is a first step length m within a cycle; one step is included between two adjacent cycles, and the preset step length between two adjacent cycles is a second step length; the second step length is smaller than the first step length, and the second step length is larger than the width of any one of the first area and the second area in the second direction; There exists a positive integer N such that w=N×m, the cycle includes X times of the pulse irradiation, and X is an integer multiple of N.

2. The laser annealing method according to claim 1, characterized in that: X=N.

3. The laser annealing method according to claim 1 or 2, characterized in that: The first region and the second region have a first width and a second width along the second direction, and a difference between the first step length and the second step length is greater than or equal to the sum of the first width and the second width.

4. The laser annealing method according to claim 1, characterized in that: The step of relatively moving the irradiation area and the substrate at a preset step length comprises: During the period, the substrate moves at a uniform speed at a first speed; Between adjacent periods, an average speed of the substrate is a second speed, and the second speed is less than the first speed.

5. The laser annealing method according to claim 1, characterized in that: The substrate includes amorphous silicon.

6. A laser annealing device, characterized in that: The device comprises: A stage for placing a substrate; A laser, used to generate laser light, wherein the laser light can form a stripe-shaped or linear irradiation area extending along a first direction on a substrate, wherein the irradiation area has a preset width along a second direction, wherein the irradiation area includes a first area, a middle area, and a second area arranged in the second direction, wherein the laser light has a uniform energy distribution in the middle area, and wherein the laser light has an energy distribution that is attenuated in the first area and the second area in a direction away from the middle area; A controller, the stage and the laser are both connected to the controller, the controller can control the laser to generate pulsed laser, and the controller can control the stage to move along the second direction, so as to use the laser to perform overlapping step-by-step pulse irradiation on the substrate along the second direction, so as to perform laser annealing on the substrate; The step-by-step pulse irradiation of the substrate along the second direction by using the laser in an overlapping manner comprises relatively moving the irradiation area and the substrate with a preset step length: the preset step length is a first step length within a cycle; one step is included between two adjacent cycles, and the preset step length between two adjacent cycles is a second step length; the second step length is smaller than the first step length, and the second step length is larger than the width of any one of the first area and the second area in the second direction; There exists a positive integer N such that w=N×m, the cycle includes X times of the pulse irradiation, and X is an integer multiple of N.

7. The laser annealing device according to claim 6, characterized in that: The first region and the second region have a first width and a second width along the second direction, and a difference between the first step length and the second step length is greater than or equal to the sum of the first width and the second width.

8. The laser annealing device according to claim 7, characterized in that: The relative movement of the irradiation area and the substrate at a preset step length includes the controller being able to control the variable speed movement of the stage so that within the cycle, the substrate moves at a uniform speed of a first speed, and between adjacent cycles, the average speed of the substrate is a second speed, and the second speed is less than the first speed.

9. The laser annealing device according to claim 8, characterized in that: X=N.

10. The laser annealing device according to claim 6, characterized in that: The controller is capable of adjusting at least one of the preset step length, the preset width, the first width, and the second width.

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