A laser annealing method and apparatus

Abstract

The application relates to the field of semiconductor chip manufacturing, and provides a laser annealing method and device.The scheme of the application is as follows: laser is provided, the laser can form a strip-shaped or linear irradiation area extending along a first direction on a substrate; the laser is used to perform 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 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 the crystallization of the low-energy part of the laser beam on the substrate is consistent with the crystallization effect of the high-energy part of the laser beam, the crystallization height on the substrate is uniform, and the production process effect of the chip is improved, and the process window is widened.

Description

Technical Field

[0001] This application relates to the field of semiconductor chip manufacturing, and in particular to a laser annealing method and apparatus. Background Technology

[0002] In chip or panel manufacturing, laser annealing (also known as laser annealing) of the substrate (e.g., wafer) to crystallize amorphous silicon (ASI) is a crucial process. During laser annealing, to ensure sufficiently uniform ASI crystallization, the laser beam energy delivered to the substrate must also be sufficiently uniform. However, existing lasers produce uneven laser beam energy distribution (also known as beam profile), resulting in varying laser beam energy received at different locations on the substrate. The variation in crystallization is more pronounced at lower-energy locations compared to higher-energy locations (i.e., the grain size is significantly larger in lower-energy areas than in higher-energy areas), leading to uneven crystallization on the final substrate and a narrowed process window.

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

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

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

[0006] Provide a laser that can form a strip or line irradiation area extending along a first direction on the substrate;

[0007] Laser annealing of a substrate is performed by applying overlapping, step-by-step laser pulses along a second direction, perpendicular to the first direction; wherein:

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

[0009] The method of using a laser to perform overlapping step-pulse irradiation on a substrate along a second direction includes moving the irradiation area and the substrate relative to each other with a preset step size: the preset step size within a cycle is a first step size m; there is a step between two adjacent cycles, and the preset step size between two adjacent cycles is a second step size; the second step size is less than the first step size, and the second step size is greater than the width of either the first region or the second region in the second direction.

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

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

[0012] In some embodiments of this application, the first region and the second region have a first width and a second width along a 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 and the second width.

[0013] In some embodiments of this application, the irradiation area and the substrate are moved relative to each other by a preset step size, including:

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

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

[0016] In some embodiments of this application, the substrate comprises amorphous silicon.

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

[0018] A stage, used to place a substrate;

[0019] A laser is used to generate laser light. The laser light can form a strip or line irradiation area extending along a first direction on a substrate. The irradiation area has a preset width along a second direction. The irradiation area includes a first region, a middle region, and a second region arranged in the second direction. The laser light has a uniform energy distribution in the middle region. The laser light has an energy distribution that attenuates in the first region and the second region in the direction away from the middle region.

[0020] The controller, stage, and laser are all connected to the controller. The controller can control the laser to generate pulsed laser light and can control the stage to move along the second direction so as to use the laser to irradiate the substrate with overlapping step-pulse laser light along the second direction to perform laser annealing on the substrate.

[0021] The method of using a laser to perform overlapping step-pulse irradiation on a substrate along a second direction includes moving the irradiation area and the substrate relative to each other with a preset step size: the preset step size is the first step size within a cycle; there is a step between two adjacent cycles, and the preset step size between two adjacent cycles is the second step size; the second step size is less than the first step size, and the second step size is greater than the width of either the first region or the second region in the second direction.

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

[0023] In some embodiments of this application, the first region and the second region have a first width and a second width along a 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 and the second width.

[0024] In some embodiments of this application, the irradiation area and the substrate are moved relative to each other by a preset step size. The controller can control the stage to move at a variable speed so that the substrate moves at a first speed at a constant speed within a cycle, and the average speed of the substrate between adjacent cycles is a second speed, which is less than the first speed.

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

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

[0027] This application has the following beneficial effects:

[0028] The solution of this application is as follows: a laser is provided, which can form a strip or line irradiation area extending along a first direction on a substrate; the substrate is irradiated with overlapping step-pulse lasers along a second direction to perform laser annealing on the substrate. The second direction is perpendicular to the first direction, and the step size between different cycles along the second direction is reduced. This adjusts the overlapping part of the laser beam energy irradiating the substrate when the laser beam energy is irradiated multiple times within a certain cycle, thereby converting the low-energy part of the laser beam into high energy on the substrate, so that the crystallization on the substrate is consistent with the crystallization effect of the high-energy part of the laser beam, achieving uniform crystallization height on the substrate, thereby improving the chip manufacturing process effect and widening the process window. Attached Figure Description

[0029] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the specification, serve to explain the technical solutions of this application.

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

[0031] Figure 2 This is a schematic diagram of a first example of a laser annealing scheme provided in this application.

[0032] Figure 3 This is a second example schematic diagram of the laser annealing scheme of the prior art provided in this application;

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

[0034] Figure 5 This is a schematic diagram of the laser annealing energy of the prior art laser annealing scheme provided in this application;

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

[0036] Figure 7 This is a schematic flowchart of the first embodiment of the laser annealing method provided in this application;

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

[0038] Figure 9 This is a schematic diagram of the laser annealing energy in the third embodiment of the laser annealing scheme provided in this application;

[0039] Figure 10 This is a schematic diagram of an embodiment of the laser annealing apparatus provided in this application. Detailed Implementation

[0040] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0041] In the following description, specific details such as particular system architectures, interfaces, and technologies are presented for illustrative purposes rather than for limiting purposes, in order to provide a thorough understanding of this application.

[0042] In this document, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " generally indicates that the preceding and following related objects have an "or" relationship. Furthermore, "many" in this document means two or more. Moreover, the term "at least one" in this document means any combination of at least two of any one or more of a plurality of objects. 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 section, the energy distribution (also known as beam profile) of the laser beam generated by existing lasers is not uniform, resulting in different laser beam energies at different locations on the substrate when the substrate is irradiated with laser. The change in crystallinity is more pronounced at locations with lower energy than at locations with higher energy (i.e., the size of the grains in the low-energy areas is much larger than the size of the grains in the high-energy areas), leading to uneven crystallinity on the substrate and a narrowing of the process window.

[0044] The following section, using the principle of laser annealing crystallization and related accompanying figures, explains why existing laser annealing methods result in uneven crystallization on the substrate.

[0045] In the laser annealing of amorphous silicon, there are two main crystallization mechanisms: the heterogeneous nucleation temperature (also known as the solid-state crystallization temperature) and the spontaneous nucleation temperature. The heterogeneous nucleation temperature facilitates crystallization at impurities or defects, thus requiring a lower temperature. The spontaneous nucleation temperature is independent of impurities or defects, therefore requiring a higher temperature; that is, the spontaneous nucleation temperature is higher than the heterogeneous nucleation temperature. Crystallization occurring at both the spontaneous and heterogeneous nucleation temperatures results in small grains. As the temperature gradually rises from the heterogeneous nucleation temperature to the spontaneous nucleation temperature, the grain size initially increases and then decreases. Specifically, crystallization at the intermediate temperature between the spontaneous and heterogeneous nucleation temperatures results in large grains, larger than those formed at either the spontaneous or heterogeneous nucleation temperatures.

[0046] Generally, laser annealing temperatures are chosen above the spontaneous nucleation temperature. As the temperature decreases, the crystallization mechanism changes, and spontaneous nucleation decreases significantly. At the intermediate temperature between the spontaneous and heterogeneous nucleation temperatures, grain size becomes unconstrained and undergoes a sudden change (enlargement). Conversely, as the temperature increases, the crystallization mechanism remains unchanged, and grain size does not change abruptly. For example, ... Figure 1 As shown, it illustrates an example of the energy distribution in the laser-irradiated area during laser pulse annealing, where both spontaneous nucleation temperature points and heterogeneous nucleation temperature points are simultaneously formed in amorphous silicon. Combined with... Figure 1-4It is known that a laser pulse can form a strip-shaped or linear irradiation area extending along a first direction on the surface of amorphous silicon. The 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 part (middle region) in the middle and energy attenuation parts (first region and second region) on both sides. When the substrate is laser annealed, the amorphous silicon is heated by the laser in the high-energy uniform part, and the temperature is at the spontaneous nucleation temperature point. The amorphous silicon is heated by the laser in the lower energy part of the energy attenuation part, 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 on the substrate. However, when the amorphous silicon is heated by the laser in the medium energy part of the energy attenuation part, and the temperature is at the intermediate 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 This illustration shows an example of a prior art laser annealing method, which includes:

[0048] Provide a light source (see example of a light source) Figure 2 As indicated by arrow (1) in the image, the light source can emit laser light, which can then be applied to a substrate (e.g., a wafer, an example of which is shown in the image). Figure 2 As shown by arrow (2) in the image, a first direction is formed along the first direction (see example of the first direction). Figure 2 The strip or line irradiation area extending from the arrow (4) in the image (see example of irradiation area for reference). Figure 2 As shown by arrow (3) and as shown in the image Figure 3 As shown by arrow (6) in the image, the laser forms an isosceles trapezoidal energy distribution in the irradiated area, which are the first region (see example of the first region for details). Figure 3 (As shown by arrow (1) in the middle), the middle area (see example of the middle area) Figure 3 (As shown by arrow (3)) and the second area (see example of the second area as follows) Figure 3 (As shown by arrow (2) in the image), the energy distribution in the middle region is uniform, while the first and second regions have an energy distribution that decays along the direction away from the middle region (see example of energy distribution in the image). Figure 4 (As shown). The substrate is irradiated with overlapping step-pulse lasers along the second direction (see example of overlapping step-pulse irradiation). Figure 5 As shown), the irradiation area and the substrate are moved relative to each other with a constant preset step size m.

[0049] In existing technologies, the energy of laser irradiation in the second direction is approximately considered uniform. In this prior art example, the width of the irradiation area in the second direction is w, where w is an integer multiple of a preset step size m, thereby ensuring a uniform distribution of laser irradiation energy across the entire substrate surface. However, after laser annealing, due to the existence of the first and second regions, the total energy distribution of the laser energy across different regions of the substrate is as follows: Figure 6 As shown, from Figure 5 , 6 As can be seen, the energy density in region p on the substrate is significantly greater than that in region q (region p is irradiated by four high-energy homogenization laser irradiations, while region q is irradiated by five laser irradiations, including three in the high-energy homogenization region and two in the energy attenuation region, resulting in a lower total irradiation energy compared to region p). In the amorphous silicon annealing and crystallization process, the energy in region p is configured to allow the amorphous silicon to reach its spontaneous nucleation temperature, forming small grains in the irradiated region corresponding to region p. In contrast, the energy in region q causes the amorphous silicon to reach an intermediate temperature between the spontaneous nucleation temperature and the heterogeneous nucleation temperature, resulting in large grains in the irradiated region corresponding to region q. This leads to a decrease in crystallization uniformity.

[0050] The inventors discovered that current methods for solving uneven crystallization on substrates involve laser manufacturers continuously improving the uniformity of laser energy distribution in the irradiated area. However, the optical path system cannot achieve a perfect laser energy distribution; it can only minimize low-energy portions (i.e., the first and second regions) to make the laser energy distribution closer to a rectangle, but it cannot completely eliminate the low-energy portions. As long as low-energy portions exist in the laser energy distribution, the overlapping, step-by-step pulsed irradiation of the laser onto the substrate will result in uneven crystallization.

[0051] Meanwhile, because the low-energy portion is very narrow in the second direction, it is difficult to accurately achieve overlap between the first and second regions between two pulses in a single-line step-pulse scan without adjusting the laser energy distribution (e.g., adjusting the width of the first and second regions). Adjusting the laser energy distribution requires adjusting the laser's optical path system, which is difficult, costly, and has limited adjustment range. Reducing the step size of each step and lowering the laser pulse energy to eliminate the q region would increase the number of laser irradiations and reduce production efficiency. Matching the laser pulse energy and step size would increase the difficulty of process control and would not completely eliminate the q region. Furthermore, since the laser irradiation energy adjustment range of the laser is limited, adjusting the laser pulse energy may increase equipment costs.

[0052] To address the aforementioned issues, this application proposes a novel laser annealing scheme. In this scheme, the step size between different cycles (one cycle includes multiple steps) along the second direction of the substrate is reduced. This adjusts the overlapping portion (also known as Overlap) of the laser beam energy on the substrate when the laser beam energy irradiates the substrate multiple times within a certain cycle, 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 relatively small, thus eliminating the need to adjust the laser pulse energy. Furthermore, since the step size is adjusted once every cycle, the number of laser irradiations does not increase significantly, resulting in a low impact on production efficiency.

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

[0054] S1. Provide a laser, which is capable of forming a strip or line irradiation area extending along a first direction on the substrate;

[0055] S2. Laser annealing is performed on the substrate by irradiating it with overlapping step-pulse lasers along a second direction, wherein the second direction is perpendicular to the first direction.

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

[0057] The method of using a laser to perform overlapping step-pulse irradiation on a substrate along a second direction includes moving the irradiation area and the substrate relative to each other with a preset step size: the preset step size is the first step size within a cycle; there is a step between two adjacent cycles, and the preset step size between two adjacent cycles is the second step size; the second step size is less than the first step size, and the second step size is greater than the width of either the first region or the second region in the second direction.

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

[0059] The preset step size and the step-type pulse irradiation are in one-to-one correspondence. That is, if the irradiation area and the substrate are moved relative to each other by the preset step size once, the laser will irradiate the substrate once. It can be understood that multiple steps are performed within a cycle, and the preset step size for each step is the first step size; between adjacent cycles, one step can be performed, and the preset step size is the second step size.

[0060] The embodiments described above in this application divide the movement of the substrate during the crystallization process into multiple cycles based on the number of laser energy irradiation steps along the second direction on the substrate, and set the second step size between cycles to be smaller than the first step size within the cycle. This method adjusts the overlapping portion (also known as Overlap) of the laser beam energy irradiating the substrate. Since the second step size is smaller than the first step size, the irradiated area of ​​the second cycle and other cycles after the second cycle moves closer to the first cycle, thereby reducing or even eliminating the q region, i.e., reducing the low-energy region and improving the uniformity of laser annealing.

[0061] It is understood that each cycle includes X laser pulse irradiations. Since X is an integer multiple of N and w is a multiple of m, when the preset step size is always m, the (X+1)th to (X+N)th laser irradiations will inevitably form a q region (i.e., a low-energy region) with the (X-N+1)th to (X)th laser irradiations in the previous X laser irradiations. This application, by making the second step size smaller than the first step size, allows the laser irradiation in the next cycle to overlap with the laser irradiation in the previous cycle, thereby reducing or eliminating the q region. Simultaneously, by controlling the second step size to be greater than either the width of the first or second region, it avoids the p region shrinking to 0, leading to excessively high annealing temperatures, and also avoids the increased process difficulty and cost caused by laser energy adjustment. Furthermore, since the first step size remains constant within the cycle, it reduces the increase in the number of step size adjustments, and also avoids laser pulse energy adjustments caused by step size adjustments, reducing process difficulty and production costs.

[0062] In a preferred embodiment, reference is still made to, as follows: Figure 4 As shown, the first and second regions have a first width 'a' and a second width 'b' along the second direction. 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 region 'q' is the sum of the first width 'a' and the second width 'b', region 'q' can be completely eliminated when the second step length is reduced by at least (a+b) relative to the first step length, thus ensuring uniform laser annealing. It can be understood that when the first and second widths are narrower, the difference between the first step length and the second step length is greater than the sum of the first and second widths, reducing the difficulty of controlling the preset step length.

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

[0065] The following will combine Figure 2-4 Sections 8-9 describe the best implementation method and its technical effects in this application.

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

[0067] Specifically, in combination Figure 4 It is known that a laser pulse can form a strip-shaped or linear irradiation region extending along a first direction on the surface of amorphous silicon. The energy distribution along the second direction is trapezoidal or approximately trapezoidal, including a high-energy uniform region (middle region) in the middle and energy-attenuating regions (first region and second region) on both sides. In the second direction, the preset width of the irradiation region is w, the width of the first region is a, and the width of the second region is b. In this embodiment, the energy distribution of the laser along the second direction in the irradiation region is an isosceles trapezoid, i.e., a = b.

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

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

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

[0071] The second step size between the first and second cycles is m-2a, such 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 region 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 implementation method ( Figure 8 The technical solution shown is superior to existing technologies. Figure 5 This can eliminate all q regions, keep the total laser irradiation energy in 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 regions.

[0073] In this embodiment, after shortening the preset step size during the cycle, the width of the portion of the original p-region with uniform laser irradiation energy decreases along the second direction. 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 increases, becoming greater than the total laser irradiation energy of the original p-region, forming the r-region. As mentioned earlier, since the laser irradiation energy of the original p-region is usually configured slightly higher than the spontaneous nucleation temperature, this embodiment, after eliminating the q-region, also forms the r-region with a temperature higher than the p-region. However, increasing the temperature does not lead to a decrease in the uniformity of the crystallized grain size. In addition, since the widths of the first and second regions are relatively narrow, the reduction in the width of the p-region is small, and the overlap between the left end of the first laser pulse of the first cycle and the middle region of the first laser pulse of the second cycle is also small, resulting in a smaller impact on the overall temperature during laser annealing. Thus, the uniformity of laser annealing can be improved while avoiding the need to adjust the laser pulse energy, reducing process costs and process difficulty.

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

[0075] In some embodiments, the substrate moves at a constant speed and is irradiated with laser pulses. Since each laser pulse is short, it is approximated that the substrate is stationary during laser irradiation, thus forming overlapping, step-like pulse irradiation. The interval between laser pulse irradiations can be adjusted so that the second step length is smaller than the first step length.

[0076] The above embodiments of this application can reduce the difficulty of controlling the relative movement between the substrate and the irradiation area, achieve precise control and repeatability of the laser irradiation position each time, thereby ensuring the consistency of the 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 remain relatively stationary. After the laser is turned off, the substrate moves according to a preset step size. After one movement is completed, the laser is turned on and the irradiation area and the substrate remain relatively stationary. The above actions are repeated to form overlapping step-pulse irradiation.

[0078] The embodiments described above enable precise short pauses and position adjustments after each laser irradiation, ensuring sufficient and consistent energy input to each irradiation point. Simultaneously, the overlap between adjacent irradiation areas is more precisely controllable, effectively avoiding dynamic errors that may be caused by continuous movement. This guarantees processing consistency and repeatability, thereby improving the uniformity of crystallization on the substrate. Furthermore, pulsed movement allows for self-correction after each movement, enhancing the flexibility and adaptability of the processing.

[0079] In some embodiments, laser pulse irradiation is used, and the substrate moves at a variable speed. Since each laser pulse irradiation is short, it is approximated that the substrate is stationary during laser irradiation, thus forming overlapping, step-like pulse irradiation. The substrate's movement speed can be adjusted so that the second step size is smaller than the first step size. For example, the substrate maintains a constant speed within each cycle, and the substrate's speed decreases between cycles. Specifically, the irradiation area and the substrate are moved relative to each other with a preset step size, including variable-speed movement. That is, within a cycle, the substrate moves at a constant first speed, and between adjacent cycles, the average speed of the substrate is a second speed, which is less than the first speed. Optionally, the substrate moves continuously.

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

[0081] However, this is not the only one. In some embodiments, the substrate remains stationary while the irradiation area of ​​the laser pulse moves, for example, the light source moves at a constant speed, at a variable speed, or in a pulsed manner. Similarly, overlapping step-by-step pulse irradiation can be achieved.

[0082] This application does not specifically limit the manner of relative movement between the substrate and the irradiation area, as long as it can achieve overlapping step-pulse irradiation of the substrate by the laser along the second direction, and the second step length is less than the first step length and the second step length is greater than the width of either the first region or the second region in the second direction.

[0083] Furthermore, according to one embodiment of this application, this application provides a laser annealing apparatus, such as... Figure 10 As shown, the device includes:

[0084] A stage, used to place a substrate;

[0085] A laser is used to generate laser light. The laser light can form a strip or line irradiation area extending along a first direction on a substrate. The irradiation area has a preset width along a second direction. The irradiation area includes a first region, a middle region, and a second region arranged in the second direction. The laser light has a uniform energy distribution in the middle region. The laser light has an energy distribution that attenuates in the first region and the second region in the direction away from the middle region.

[0086] The controller, stage, and laser are all connected to the controller. The controller can control the laser to generate pulsed laser light and can control the stage to move along the second direction so as to use the laser to irradiate the substrate with overlapping step-pulse laser light along the second direction to perform laser annealing on the substrate.

[0087] The method of using a laser to perform overlapping step-pulse irradiation on a substrate along a second direction includes moving the irradiation area and the substrate relative to each other with a preset step size: the preset step size is the first step size within a cycle; there is a step between two adjacent cycles, and the preset step size between two adjacent cycles is the second step size; the second step size is less than the first step size, and the second step size is greater than the width of either the first region or the second region in the second direction.

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

[0089] The embodiments described above in this application achieve precise coordinated control of the stage and the laser through a controller, thereby realizing the aforementioned method, which will not be elaborated further here.

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

[0091] It is understandable that controlling the movement of the stage is simpler than controlling the energy distribution of the laser emitted or the pulse frequency of the laser. Therefore, in a preferred embodiment, the controller can control the stage to perform the variable-speed movement described above, thereby achieving relative movement of the irradiation area and the substrate in preset step sizes. 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, which is less than the first speed.

[0092] According to one embodiment of this application, the controller can adjust at least one of a preset step size, a preset width, a first width, and a second width. For example, the controller adjusts the preset step size based on the first width, the second width, and the preset width of the laser emitted by the laser to achieve the aforementioned method.

[0093] According to a preferred embodiment of this application, the laser annealing apparatus is capable of controlling 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 to existing methods that use lasers to irradiate the substrate along a second direction in overlapping steps, and utilize a constant step size to move the irradiation area and the substrate relative to each other, this application reduces the step size between different cycles along the second direction of the substrate. This allows the laser beam energy to be adjusted when irradiating the substrate multiple times within a certain cycle, thereby converting the low-energy portion of the laser beam into high energy on the substrate. This ensures that the crystallization on the substrate is consistent with the crystallization effect of the high-energy portion of the laser beam, achieving uniform crystallization height on the substrate, thereby improving the chip manufacturing process and widening the process window.

Claims

1. A laser annealing method, characterized in that, The method includes: Provide a laser that is capable of forming a strip or line irradiation area extending along a first direction on a substrate; The substrate is laser-annealed by overlapping, step-by-step pulse irradiation along a second direction, 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. The laser has an energy distribution that attenuates in the first area and the second area along the direction away from the middle area. The first area and the second area have a first width and a second width along the second direction. The method of using the laser to perform overlapping step-pulse irradiation of the substrate along the second direction includes moving the irradiation area and the substrate relative to each other with a preset step size: the preset step size is a first step size m within a period; there is a step between two adjacent periods, and the preset step size between two adjacent periods is a second step size; the second step size is less than the first step size, and the second step size is greater than the width of either the first region or the second region in the second direction, wherein the difference between the first step size and the second step size is greater than or equal to the sum of the first width and the second width; There exists a positive integer N such that w = N × m, and the period includes X pulse irradiations, where X = N.

2. The laser annealing method according to claim 1, characterized in that, The step of moving the irradiation area and the substrate relative to each other by a preset step size includes: During the period, the substrate moves at a constant speed at a first velocity; Between adjacent cycles, the average speed of the substrate is a second speed, which is less than the first speed.

3. The laser annealing method according to claim 1, characterized in that, The substrate comprises amorphous silicon.

4. A laser annealing apparatus, characterized in that, The device includes: A stage, used to place a substrate; A laser for generating laser light, the laser being capable of forming a strip or line irradiation area extending along a first direction on a substrate, the irradiation area having a predetermined width along a second direction, the irradiation area including a first region, a middle region, and a second region arranged along the second direction, the laser having a uniform energy distribution in the middle region, the laser having an energy distribution that attenuates in the first region and the second region along a direction away from the middle region, wherein the first region and the second region have a first width and a second width along the second direction; The controller is connected to both the stage and the laser. The controller can control the laser to generate pulsed laser light and can control the stage to move along the second direction so as to use the laser to irradiate the substrate with overlapping step-pulse laser light along the second direction to perform laser annealing on the substrate. The step-pulse irradiation of the substrate along the second direction using the laser includes moving the irradiation area and the substrate relative to each other with a preset step size: the preset step size is the first step size within a period; there is a step between two adjacent periods, and the preset step size between two adjacent periods is the second step size; the second step size is less than the first step size, and the second step size is greater than the width of either the first area or the second area in the second direction, wherein the difference between the first step size and the second step size is greater than or equal to the sum of the first width and the second width; There exists a positive integer N such that w = N × m, and the period includes X pulse irradiations, where X = N.

5. The laser annealing apparatus according to claim 4, characterized in that, The step of moving the irradiation area and the substrate relative to each other by a preset step size includes the controller being able to control the stage to move at a variable speed, so that the substrate moves at a first speed at a constant speed within the cycle, and the average speed of the substrate between adjacent cycles is a second speed, the second speed being less than the first speed.

6. The laser annealing apparatus according to claim 5, characterized in that, The controller can adjust at least one of the preset step size, the preset width, the first width, and the second width.

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