Method and apparatus for determining multi-pulse laser annealing process parameters

Abstract

This invention provides a method and apparatus for determining process parameters of multi-pulse laser annealing, belonging to the field of semiconductor manufacturing technology. The method includes: determining a timing output signal function based on the pulse width and the delay time between adjacent laser pulses; determining an energy density spatial distribution function based on the spatial energy distribution of a single-pulse laser, the laser scanning speed, and the timing output signal function; constructing a laser heat source model and performing numerical simulation based on the energy density spatial distribution function and the optical characteristic parameters of the device to be annealed to obtain the transient temperature field distribution of the device; and determining the target process parameters based on the transient temperature field distribution. This invention establishes a timing output signal function and an energy density spatial distribution function, and then constructs an accurate laser heat source model for numerical simulation, thereby predicting the transient temperature field distribution during laser scanning, accurately obtaining laser parameters that meet the specific device process requirements, and reducing experimental costs.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a method and apparatus for determining the process parameters of multi-pulse laser annealing. Background Technology

[0002] Laser annealing is a non-contact, high-precision heating method that can induce recrystallization in amorphous silicon and repair internal defects in materials. It is an important step in semiconductor manufacturing processes.

[0003] Currently, actual laser annealing machines are typically used for engineering testing. This involves conducting multiple experiments to verify whether the annealing process meets the process requirements, and determining the impact of changes in laser annealing process parameters on the device's temperature field based on the experimental results.

[0004] However, this method of engineering testing using actual laser annealing equipment cannot detect temperature changes on the material's surface and internal structure. For multi-pulse lasers, the adjustable range of laser process parameters is too complex, resulting in high experimental costs to meet process requirements and making it difficult to accurately obtain laser parameters that meet the specific device's process requirements. Summary of the Invention

[0005] This invention provides a method and apparatus for determining multi-pulse laser annealing process parameters, which solves the problems of existing technologies that cannot detect internal temperature changes of materials when using actual laser annealing machines for engineering testing, and the high cost and difficulty in accurately obtaining laser parameters that meet the specific device process requirements due to the complexity of multi-pulse laser parameters. This invention enables accurate prediction of the transient temperature field distribution of the device during laser scanning based on numerical simulation, thereby determining the laser parameters that meet the specific device process requirements at low cost and with high accuracy without the need for complex engineering tests.

[0006] This invention provides a method for determining the process parameters of multi-pulse laser annealing, comprising the following steps: The timing output signal function is determined based on the pulse width and the delay time between adjacent laser pulses. Based on the spatial energy distribution of the single-pulse laser at the beam waist, the laser scanning speed, and the timing output signal function, the spatial distribution function of energy density is determined. Based on the energy density spatial distribution function and the optical characteristic parameters of the device to be annealed, a laser heat source model is constructed, and numerical simulation is performed based on the laser heat source model to obtain the transient temperature field distribution of the device to be annealed during the laser scanning process. Based on the transient temperature field distribution and the preset process standards, the target process parameters are determined.

[0007] According to a method for determining multi-pulse laser annealing process parameters provided by the present invention, the step of determining a timing output signal function based on the pulse width and the delay time between adjacent laser pulses includes: Based on the pulse width, a normalization function characterizing the intensity of a single-pulse laser is constructed; Based on the delay time between adjacent laser pulses, calculate the time offset of each single laser pulse in the multi-pulse laser beam relative to the first single laser pulse. Based on the time offset and the normalization function, the delay signal function corresponding to each single-pulse laser is determined, and the timing output signal function is determined based on each of the delay signal functions.

[0008] According to a method for determining multi-pulse laser annealing process parameters provided by the present invention, the step of determining the energy density spatial distribution function based on the spatial energy distribution of a single-pulse laser at the beam waist, the laser scanning speed, and the timing output signal function includes: Obtain the peak energy density and static spatial energy distribution function of a single-pulse laser at the beam waist; Based on the laser scanning speed and time variables, determine the dynamic displacement parameters; Based on the dynamic displacement parameters and the static spatial energy distribution function, the dynamic spatial energy distribution function is determined; The energy density spatial distribution function is determined based on the peak energy density, the dynamic spatial energy distribution function, and the time-series output signal function.

[0009] According to a method for determining multi-pulse laser annealing process parameters provided by the present invention, if the single-pulse laser is a Gaussian beam, the step of obtaining the peak energy density and static spatial energy distribution function of the single-pulse laser at the beam waist includes: The peak energy density is determined based on the effective radius of the waist of the Gaussian beam and the single-pulse energy. The static spatial energy distribution function is constructed based on the Gaussian function model; The step of determining the energy density spatial distribution function based on the peak energy density, the dynamic spatial energy distribution function, and the time-series output signal function includes: The dynamic displacement parameter is determined based on the laser scanning speed and the timing output signal function; The position coordinates of the Gaussian function model are updated based on the dynamic displacement parameters, and the energy density spatial distribution function is determined by combining the updated position coordinates with the peak energy density.

[0010] According to a method for determining multi-pulse laser annealing process parameters provided by the present invention, if the single-pulse laser is a flat-top beam, the step of obtaining the peak energy density and static spatial energy distribution function of the single-pulse laser at the beam waist includes: The peak energy density is determined based on the rectangular spot size of the flat-top beam and the single-pulse energy. The static spatial energy distribution function is constructed based on a piecewise linear function model; The step of determining the energy density spatial distribution function based on the peak energy density, the dynamic spatial energy distribution function, and the time-series output signal function includes: The dynamic displacement parameter is determined based on the laser scanning speed and the time variable; The position coordinates of the piecewise linear function model are updated based on the dynamic displacement parameters, and the energy density spatial distribution function is determined by combining the peak energy density.

[0011] According to the present invention, a method for determining multi-pulse laser annealing process parameters, wherein constructing a laser heat source model based on the energy density spatial distribution function and the optical characteristic parameters of the device to be annealed includes: Obtain the material type, reflectivity, transmittance, and absorption coefficient of the device to be annealed; If the material type is transparent or translucent, a volume heat source model is constructed based on the reflectivity, transmittance, absorption coefficient, and energy density spatial distribution function; if the material type is non-transparent, a surface heat source model is constructed based on the reflectivity and energy density spatial distribution function. The volume heat source model or the surface heat source model is determined as the laser heat source model.

[0012] According to a method for determining multi-pulse laser annealing process parameters provided by the present invention, the step of determining the target process parameters based on the transient temperature field distribution and preset process standards includes: Extract the highest temperature of the target film layer and the highest temperature of the underlying material in the device to be annealed from the transient temperature field distribution; If the highest temperature of the target film is greater than or equal to the first phase transition temperature, and the highest temperature of the underlying material is less than the second phase transition temperature, then the combination of parameters used to generate the transient temperature field distribution—pulse width, delay time, energy density of the single-pulse laser, and laser scanning speed—is determined as the target process parameters.

[0013] The present invention also provides a device for determining the process parameters of multi-pulse laser annealing, comprising the following modules: The timing model construction module is used to determine the timing output signal function based on the pulse width and the delay time between adjacent laser pulses; The spatial distribution determination module is used to determine the energy density spatial distribution function based on the spatial energy distribution of the single-pulse laser at the beam waist, the laser scanning speed, and the timing output signal function. The temperature field simulation module is used to construct a laser heat source model based on the energy density spatial distribution function and the optical characteristic parameters of the device to be annealed, and to perform numerical simulation based on the laser heat source model to obtain the transient temperature field distribution of the device to be annealed during the laser scanning process. The process parameter determination module is used to determine the target process parameters based on the transient temperature field distribution and the preset process standards.

[0014] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for determining the multi-pulse laser annealing process parameters as described above.

[0015] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for determining the multi-pulse laser annealing process parameters as described above.

[0016] The present invention also provides a computer program product, including a computer program, which, when executed by a processor, implements the method for determining the multi-pulse laser annealing process parameters as described above.

[0017] The method and apparatus for determining multi-pulse laser annealing process parameters provided by this invention establishes a timing output signal function and an energy density spatial distribution function, and then constructs an accurate laser heat source model for numerical simulation. This enables the prediction of transient temperature field distribution during laser scanning, accurately obtains laser parameters that meet the specific device process requirements, and reduces experimental costs. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating the method for determining the process parameters of multi-pulse laser annealing provided by the present invention.

[0020] Figure 2This is a flowchart illustrating the determination of the timing output signal function provided by the present invention.

[0021] Figure 3 This is one of the timing output signal relationship diagrams of multiple pulsed laser beams provided by the present invention.

[0022] Figure 4 This is the second of the timing output signal relationship diagrams of multiple pulsed laser beams provided by the present invention.

[0023] Figure 5 This is the third of the timing output signal relationship diagrams of multiple pulsed laser beams provided by the present invention.

[0024] Figure 6 This is a schematic diagram of the process for determining the spatial distribution function of energy density provided by the present invention.

[0025] Figure 7 This is a schematic diagram of the spatial distribution of Gaussian beam energy provided by the present invention.

[0026] Figure 8 This is a schematic diagram of the spatial distribution of the flat-top beam energy provided by the present invention.

[0027] Figure 9 This is a schematic diagram of the energy spatial distribution of the Gaussian beam and the flat-top beam provided by the present invention.

[0028] Figure 10 This is a schematic diagram of the process for constructing a laser heat source model provided by the present invention.

[0029] Figure 11 This is a schematic diagram of the process for determining target process parameters provided by the present invention.

[0030] Figure 12 This is a schematic diagram of the device structure provided by the present invention.

[0031] Figure 13 This is a schematic diagram of the temperature field under different combinations of delay times provided by the present invention based on the case structure.

[0032] Figure 14 This is a transmission scanning electron microscope image of polycrystalline silicon recrystallized from amorphous silicon in combination 2 provided by the present invention after laser annealing.

[0033] Figure 15 This is a schematic diagram of the temperature field under different energy density combinations provided by the present invention based on the case structure.

[0034] Figure 16 This is a transmission scanning electron microscope image of polycrystalline silicon recrystallized from amorphous silicon of combination 6 provided by the present invention after laser annealing.

[0035] Figure 17This is a schematic diagram of the device for determining the process parameters of multi-pulse laser annealing provided by the present invention.

[0036] Figure 18 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0038] It should be noted that, in the description of this invention, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0039] The terms "first," "second," etc., used in this invention are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more.

[0040] To facilitate a full understanding of the technical solution of this application, the following content is hereby introduced: With the optimization of semiconductor device performance, laser annealing technology has also developed rapidly. Laser annealing is a non-contact, high-precision heating method that completes wafer annealing only in a very small heat-affected zone. Laser annealing can induce recrystallization in amorphous silicon, repair internal material defects, and is used for the laser annealing crystallization preparation of high-quality polycrystalline silicon thin films. It is also used for annealing requirements such as ultra-shallow junction doping activation and recrystallization of source, drain, and gate in Complementary Metal Oxide Semiconductor (CMOS) devices.

[0041] Various laser annealing methods are employed based on process requirements. However, when using short-pulse-width lasers for high-temperature annealing, the temperature changes on the material surface and internally cannot be detected, often requiring multiple experiments to verify whether the annealing process meets the process requirements. Furthermore, for the annealing requirements of new device processes, determining the impact of laser annealing process parameter variations on the device's temperature field through experiments is complex and costly. This is especially true for multi-pulse lasers, where the variable range of laser process parameters is extremely complex, further increasing experimental costs.

[0042] If the temperature field distribution law of laser annealing can be accurately predicted, and the experiment can be guided by theory, with feedback from the experiment to the theoretical data model, this will have significant practical implications for achieving high-quality laser annealing of devices. Therefore, this application theoretically derives the calculation formulas for the spatial distribution of energy density and the timing output signals of multiple pulsed lasers in the numerical simulation of the temperature field, so as to realize the adaptive adjustment of laser process parameters during the temperature field simulation and reduce experimental costs.

[0043] The following is combined with Figures 1-18 This invention describes the method and apparatus for determining the process parameters of multi-pulse laser annealing.

[0044] Figure 1 This is a flowchart illustrating the method for determining the process parameters of multi-pulse laser annealing provided by the present invention, as shown below. Figure 1 As shown, the execution subject of the method for determining the multi-pulse laser annealing process parameters provided by the present invention can be an industrial control computer, a server, a cloud computing platform, or a computer capable of executing the method of the present invention, etc. Unless otherwise specified, the following embodiments will be described using an industrial control computer as an example.

[0045] As an optional embodiment, the method for determining the parameters of this multi-pulse laser annealing process mainly includes, but is not limited to, the following steps: Step 110: Determine the timing output signal function based on the pulse width and the delay time between adjacent laser pulses.

[0046] Pulse width refers to the duration of a single laser pulse and is one of the important parameters of laser operating characteristics. For example, in specific implementations, the pulse width can be on the order of microseconds (µs) or nanoseconds (ns), such as 1µs to 2µs, or even shorter 1ns to hundreds of ns, which can be determined according to the selection of different lasers.

[0047] The delay time between adjacent laser pulses refers to the time interval between the preceding and following pulses when multiple laser pulses act on the same location sequentially. For example, in the case of multiple laser pulses working together, the start time of each laser pulse may be different, and the delay time can be any value in the range of 0 to 1µs, or even 0, meaning that multiple lasers are emitted simultaneously.

[0048] The timing output signal function refers to a mathematical expression describing the change of laser pulse intensity over time, used to characterize the superposition and distribution of multi-pulse laser beams in the time dimension. For example, this timing output signal function can be a normalized function based on a Gaussian distribution, a rectangular distribution, or other specific waveform distributions, reflecting the relative intensity of each pulse at different times.

[0049] Step 120: Determine the spatial distribution function of energy density based on the spatial energy distribution of the single-pulse laser at the beam waist, the laser scanning speed, and the timing output signal function.

[0050] A single-pulse laser refers to an independent laser pulse emitted by a single laser, which can be a laser with wavelengths such as 355 nanometers (nm), 527 nm, or 532 nm. For example, a multi-pulse laser annealing system can contain multiple single-pulse lasers emitted simultaneously or in a specific timing sequence.

[0051] The spatial energy distribution at the beam waist refers to the distribution of energy density across the cross-section of the laser beam at its narrowest point (i.e., the focal plane). For example, for different types of lasers, this spatial energy distribution can be a Gaussian distribution with strong energy at the center and weak energy at the edges, or it can be a flat-top distribution after shaping, i.e., a rectangular or linear distribution with uniform energy density within the beam area.

[0052] Laser scanning speed refers to the rate at which the laser spot moves relative to the surface of the part to be annealed. For example, in a scanning annealing process, the laser beam scans the material surface at a specific speed along a certain direction, and this laser scanning speed determines the length of time a unit area is irradiated by the laser.

[0053] The energy density spatial distribution function is a mathematical model that describes the dynamic distribution of laser energy in three-dimensional space and time. For example, this energy density spatial distribution function integrates the spatial shape of a single-pulse laser (Gaussian or flat-top), the pulse intensity that varies with time (time-series signal), and the movement of the laser beam (scanning speed), and can calculate the instantaneous laser energy density value at any time and any position.

[0054] Step 130: Based on the energy density spatial distribution function and the optical characteristic parameters of the device to be annealed, construct a laser heat source model, and perform numerical simulation based on the laser heat source model to obtain the transient temperature field distribution of the device to be annealed during the laser scanning process.

[0055] The device to be annealed refers to a wafer, thin film, or other semiconductor device containing amorphous silicon and underlying materials, and is the object of the laser annealing process. For example, the device to be annealed can be a stacked structure containing a silicon (Si) substrate, a metal film (such as tungsten W, copper Cu, silver Ag, aluminum Al, etc.), silicon dioxide (SiO2), silicon nitride (Si3N4), and an amorphous silicon thin film.

[0056] The optical properties of a device to be annealed refer to optical physical quantities such as reflectivity, transmittance, and absorption coefficient of each layer of material in the device. For example, different materials have different absorption capabilities for lasers of a specific wavelength; transparent materials absorb less and transmit more, while non-transparent materials may mainly absorb laser energy at their surface.

[0057] A laser heat source model is a mathematical model that describes the process of laser energy being converted into heat energy inside a device to be annealed, based on the energy density spatial distribution function and optical characteristic parameters. For example, for transparent or semi-transparent materials, a volume heat source model can be constructed based on the Beer-Lambert law; for non-transparent materials, a surface heat source model can be constructed to calculate the heat generated per unit volume or unit area.

[0058] Numerical simulation refers to using computers to simulate the physical processes such as heat conduction and phase transition of a device to be annealed during laser heating. For example, by using finite element analysis (FEA) or other numerical calculation methods, a laser heat source is applied to a two-dimensional or three-dimensional geometric model of the device to be annealed, and the heat conduction equation is solved.

[0059] The transient temperature field distribution during laser scanning refers to the dynamic distribution of temperature changes over time and space at various points on the surface and inside of the device to be annealed within the extremely short duration of the laser pulse and the scanning movement. For example, numerical simulations can obtain the temperature curves of various materials such as amorphous silicon and the underlying metal film in the depth and horizontal directions at different times, thereby determining the thermal state and phase transition of each material layer.

[0060] Step 140: Determine the target process parameters based on the transient temperature field distribution and preset process standards.

[0061] Preset process standards refer to the quality requirements of laser annealing processes, which are usually expressed as indicators such as material temperature, phase transformation degree, and internal damage. For example, the target film layer (such as amorphous silicon) in the device to be annealed must reach the first phase transformation temperature (melting temperature) to achieve sufficient melting and recrystallization, while the maximum temperature of the underlying sensitive material (such as the metal layer) must be lower than the second phase transformation temperature (such as the melting point) to avoid thermal damage.

[0062] The target process parameters refer to the combination of laser processing parameters that, after numerical simulation verification, can meet the aforementioned preset process standards. For example, this parameter combination may include specific pulse widths, delay times between adjacent laser pulses, energy density of a single laser pulse, and laser scanning speed, etc., which are process settings that can be directly applied in actual production.

[0063] Considering that the transient temperature inside the material is difficult to measure directly during actual laser annealing, and that the combination of multi-pulse parameters is complex and the trial-and-error cost is high, this invention constructs an accurate simulation model that includes timing output signals and the spatial distribution of energy density. This model can accurately predict the temperature change trend of each layer inside the device under different parameters, thus eliminating the need to rely on a large number of expensive physical experiments. It can efficiently screen out the target process parameters that can both ensure the annealing effect and protect the structural integrity of the device.

[0064] The method for determining multi-pulse laser annealing process parameters provided by this invention establishes a timing output signal function and an energy density spatial distribution function, and then constructs an accurate laser heat source model for numerical simulation. This enables the prediction of transient temperature field distribution during laser scanning, accurately obtains laser parameters that meet the specific device process requirements, and reduces experimental costs.

[0065] Figure 2 This is a flowchart illustrating the determination of the timing output signal function provided by the present invention, as shown below. Figure 2 As shown, as another optional embodiment provided by the present invention, the timing output signal function is determined based on the pulse width and the delay time between adjacent laser pulses, including but not limited to the following steps: Step 210: Based on the pulse width, construct a normalization function to characterize the intensity of a single-pulse laser.

[0066] The normalization function characterizing the intensity of a single-pulse laser is a mathematical expression that describes the change in energy of a single laser pulse over time and normalizes its amplitude. For example, this normalization function can be a Gaussian function, a rectangular function, or other forms, with an integral or peak value of 1, reflecting the concentration and distribution of pulse energy along the time axis.

[0067] Step 220: Calculate the time offset of each single pulse laser in the multi-pulse laser beam relative to the first single pulse laser, based on the delay time between adjacent pulse lasers.

[0068] The time offset refers to the delay time of each subsequent laser pulse relative to the emission time of the first laser pulse. For example, if the first pulse is taken as the reference time 0, and the second pulse is emitted with a delay of t1, then the time offset of the second pulse is t1; if the third pulse is delayed by t2 relative to the second pulse, then the time offset of the third pulse relative to the first pulse is t1+t2.

[0069] Specifically, for a multi-pulse system containing m lasers, the time offset of the i-th laser is the sum of the delay times of the preceding i-1 adjacent pulses. For example, the time offset of the first laser is 0, and the time offset of the second laser is... The time offset of the third laser is + This continues until the m-th laser.

[0070] Step 230: Based on the time offset and the normalization function, determine the delay signal function corresponding to each single-pulse laser, and determine the timing output signal function based on each delay signal function.

[0071] The delay signal function corresponding to each single-pulse laser refers to the function expression obtained by shifting the original normalized function along the time axis by a corresponding time offset. For example, if the normalized function is f(t), the time offset of the second laser beam relative to the first laser beam... For example, its corresponding delay signal function is f(t- ), indicating that the pulsed laser at t= It reaches its peak or begins to take effect at a certain time.

[0072] Specifically, the timing output signal function is the set or superposition of the delay signal functions corresponding to all single-pulse lasers, used to describe the total intensity distribution of the entire multi-pulse laser beam at any given time. For example, the final timing output signal function... It can be represented as a piecewise function or vector form, where each term corresponds to the intensity change of a laser pulse within a specific time period, covering the entire process from the start of the first pulse to the end of the last pulse.

[0073] As an optional embodiment, the timing output signal function can be as shown in formula (1): (1) in, This represents the time-series output signal function, used to describe the intensity distribution variation of multi-pulse laser over time. It represents an exponential function with the natural constant e as the base; t represents the pulse laser beam movement time; , , ..., These represent the pulse widths of the 1st to mth laser beams, respectively. Indicates the standard deviation correction parameter; , , ..., These represent the scanning period or effective time period corresponding to each pulse laser beam, and the domain interval of the piecewise function is defined. This indicates the time delay between the first laser beam and the second laser beam. This represents the delay time between the (m-1)th laser beam and the mth laser beam, where m represents the total number of lasers or the total number of pulsed laser beams.

[0074] Specifically, in formula (1), the first row represents the time period of the first pulse. The intensity distribution within the range; the second row indicates the intensity distribution of the second pulse within the delay. Afterwards, during the time period The intensity distribution within the time period; the last line indicates the intensity distribution of the m-th pulse after accumulating the previous delay time. Intensity distribution within.

[0075] The method for determining the process parameters of multi-pulse laser annealing provided by this invention simplifies the complex time-series superposition process into the translation and combination of multiple single-pulse signals on the time axis by constructing a normalization function and calculating the time offset. This accurately describes the overall output intensity of multiple pulsed lasers at any time and provides a precise time reference for the subsequent dynamic calculation of energy density.

[0076] Figure 3 This is one of the timing output signal relationship diagrams of multiple pulsed laser beams provided by the present invention, such as... Figure 3 As shown, the vertical axis represents laser power, and the horizontal axis represents pulse output time and scanning cycle. Figure 3 The diagram shows the pulse timing sequence of m lasers (NO.1 to NO.m) emitted sequentially. , , ..., These represent the pulse widths of the 1st to the mth laser beams, respectively; they can be the same or different. This indicates the time delay between the first laser beam and the second laser beam. This indicates the time delay between the second and third laser beams, and so on. This represents the time delay between the (m-1)th laser beam and the mth laser beam.

[0077] like Figure 3 As shown, this embodiment illustrates the case where the delay time between each pulse in a multi-pulse laser beam is the same, i.e. = =…= Each pulse is evenly distributed along the time axis. The above laser parameters can be adjusted according to specific process requirements, and the calculation method adopts the above formula (1).

[0078] Figure 4 This is the second time-series output signal relationship diagram of multiple pulsed laser beams provided by the present invention, as shown in the figure. Figure 4 As shown, it illustrates four typical cases (ad) where the delay times between pulses in a multi-pulse laser beam are not equal (i.e., unequal spacing). The vertical axis represents laser power, and the horizontal axis represents pulse output time and scan period. to These represent the pulse widths of the 1st to the mth laser beams, respectively.

[0079] like Figure 4 As shown in (a), the short delay time between each pulse results in partial temporal overlap between adjacent pulses; as Figure 4 As shown in (b), there is a large delay time between each pulse, which makes each pulse completely separated in time and with a large interval. Figure 4 (c) and Figure 4 (d) in the diagram illustrates a mixed case with varying delay times, for example, ... Figure 4 As shown in (c), the first two pulses have a larger interval, while the subsequent pulses have a smaller interval. Figure 4 (d) in the middle shows a distribution with a larger interval in the middle and a smaller interval at both ends.

[0080] Within the limits allowed by the laser hardware, the delay time , , ..., The delay time can be arbitrarily adjusted among multiple pulsed laser beams to form combinations of unequal intervals. For example, Figure 4 The various timing signal output methods shown in (a)-(d) imply that unequal delay times lead to different output timings. Therefore, for this arbitrarily adjustable delay time, the delay time can be flexibly adjusted according to how to meet the device process requirements, thereby precisely controlling the influence on the device surface and the temperature at different melting depths. Through numerical calculation, laser parameters that meet the device process requirements can be found quickly and at a low cost. This embodiment is also applicable to the calculation method in formula (1).

[0081] Figure 5 This is the third of the timing output signal relationship diagrams for multiple pulsed laser beams provided by this invention, as shown in the figure. Figure 5 As shown in the figure, this embodiment illustrates the special case where the delay time between multiple pulsed laser beams is equal to zero. Figure 5 The vertical axis represents laser power, and the horizontal axis represents pulse output time and scan period. This represents the pulse width. In this case, assume the delay time between the 1st and mth laser beams. = =…= =0 means that the m lasers NO.1, NO.2, NO.3 to NO.m emit laser beams simultaneously at the same time.

[0082] like Figure 5 As shown, at this time, the timing output signals of each laser beam are perfectly aligned and superimposed on the time axis, synthesizing a single pulse with a common pulse width ( The high peak power pulse can concentrate high-density laser energy into the surface of the device to be annealed in a very short time to meet the specific annealing process requirements that require instantaneous and rapid heating. This embodiment is also applicable to the calculation method in formula (1). Therefore, formula (1) is applicable to timing pulse signal outputs with different pulse widths and different delay times, and has a wide range of applications.

[0083] Figure 6 This is a flowchart illustrating the process of determining the spatial distribution function of energy density provided by the present invention, as shown below. Figure 6 As shown, as another optional embodiment provided by the present invention, the spatial distribution function of energy density is determined based on the spatial energy distribution of the single-pulse laser at the beam waist, the laser scanning speed, and the timing output signal function, including but not limited to the following steps: Step 610: Obtain the peak energy density and static spatial energy distribution function of the single-pulse laser at the beam waist.

[0084] The peak energy density of a single-pulse laser at the beam waist refers to the energy density value at the point where the energy distribution is highest when a single-pulse laser is focused onto the beam waist plane. For example, this peak energy density is usually proportional to the single-pulse energy of the laser, the pulse repetition frequency, and the spot area of ​​the beam waist plane, reflecting the degree of concentration of laser energy per unit area.

[0085] The static spatial energy distribution function refers to the distribution pattern of the laser beam energy density in the spatial coordinate plane at a specific moment when the laser beam is stationary relative to the irradiated object. For example, this static spatial energy distribution function can be a Gaussian distribution function describing the characteristics of a Gaussian beam with strong energy at the center and weak energy at the edges, or it can be a rectangular or trapezoidal distribution function describing the uniform energy distribution of a flat-top beam. Its shape depends on the beam quality and shaping method of the selected laser.

[0086] The above information can be obtained through the laser's factory specifications or actual measurement data. For example, the peak energy density can be calculated based on the known laser power, repetition frequency, and spot size, and a corresponding static distribution mathematical model can be constructed according to the beam type.

[0087] Step 620: Determine the dynamic displacement parameters based on the laser scanning speed and time variables.

[0088] The time variable refers to the duration of the laser scanning process, typically with the start of the scan as the zero point. For example, when a pulsed laser beam moves and scans along a specific direction, this time variable records the exact moment the laser acts on the material surface.

[0089] The dynamic displacement parameter refers to the displacement distance of the laser beam center relative to its initial position over time. For example, when the laser beam moves along the X-axis at a constant scanning speed, this dynamic displacement parameter is the product of the scanning speed and the time variable, representing the real-time position of the spot on the scanning path.

[0090] Step 630: Determine the dynamic spatial energy distribution function based on the dynamic displacement parameter and the static spatial energy distribution function.

[0091] The dynamic spatial energy distribution function refers to the expression for spatial energy distribution after incorporating dynamic displacement parameters, used to describe the spatial energy distribution state of a moving laser beam at any given time. For example, by replacing the spatial coordinate variables in the static spatial energy distribution function with a coordinate expression that includes dynamic displacement parameters, a dynamic function reflecting the translational characteristics of the laser spot over time can be obtained.

[0092] Step 640: Determine the energy density spatial distribution function based on the peak energy density, the dynamic spatial energy distribution function, and the time-series output signal function.

[0093] The energy density spatial distribution function refers to a complete mathematical model that comprehensively considers the changes in laser intensity over time (time-series signal), the movement of the laser spot in space (dynamic displacement), and the energy distribution pattern of the laser spot itself (static distribution). For example, this energy density spatial distribution function is usually expressed as the product of the peak energy density, the dynamic spatial energy distribution function, and the time-series output signal function, and can accurately calculate the instantaneous laser energy density at any time and any spatial location within the scanning cycle.

[0094] The method for determining the process parameters of multi-pulse laser annealing provided by this invention combines the position movement of the laser spot during the scanning process with the static energy distribution by introducing a dynamic displacement parameter, and superimposes the time-series output signal. This enables the construction of an energy density spatial distribution function that comprehensively reflects the dual changes of laser energy with time and space, thereby providing a reliable mathematical model basis for accurately simulating the transient temperature field distribution during the moving scanning process.

[0095] In another embodiment of the present invention, if the single-pulse laser is a Gaussian beam, obtaining the peak energy density and static spatial energy distribution function of the single-pulse laser at the beam waist includes: determining the peak energy density based on the effective radius of the beam waist of the Gaussian beam and the single-pulse energy; and constructing the static spatial energy distribution function based on the Gaussian function model.

[0096] The effective waist radius of a Gaussian beam refers to the proportion by which the intensity of the Gaussian beam on the focusing plane decreases to the central peak intensity (usually 1 / e). 2 The radial distance at which the beam waist is located. For example, on the waist plane, the effective radius of the Gaussian beam waist is usually denoted as... .

[0097] Single pulse energy refers to the total energy carried by a single laser pulse. For example, single pulse energy can be calculated from laser power and repetition frequency.

[0098] The Gaussian function model refers to an exponential function based on the natural logarithm base e, used to describe the normal distribution of energy within a light spot, which is high in the middle and low around the edges.

[0099] Specifically, the relationship between the peak energy density of the Gaussian beam and the laser power can be expressed as shown in formula (2): (2) in, For peak energy density, For laser power, Let be the area of ​​the beam spot on the waist plane, where , The effective radius of the waist of the Gaussian beam. P1 is the repetition frequency of the laser beam, and P1 / f1 is the single pulse energy.

[0100] Based on peak energy density, dynamic spatial energy distribution function, and time-series output signal function, the energy density spatial distribution function is determined, including: determining dynamic displacement parameters based on laser scanning speed and time-series output signal function; updating the position coordinates of the Gaussian function model based on dynamic displacement parameters, and combining the updated position coordinates and peak energy density to determine the energy density spatial distribution function.

[0101] Specifically, in the scanning direction (width direction), the spatial distribution function of laser energy density is distributed in the form of a Gaussian function, as shown in formula (3): (3) in, Let be the spatial distribution function of the energy density of the Gaussian beam. The peak energy density of a single pulse in the waist plane. This represents an exponential function with base e. The coordinates of the points on the material surface in the scanning direction. For laser scanning speed, For timing output signal functions, The effective radius of the waist of the Gaussian beam is given.

[0102] The method for determining the process parameters of multi-pulse laser annealing provided by this invention, by introducing the peak energy density calculation formula of the Gaussian beam and the Gaussian distribution model after dynamic displacement correction, can accurately simulate the energy injection situation of the Gaussian laser beam with normal distribution in the scanning direction as it moves over time, providing key energy distribution input parameters for accurately predicting the temperature field of multi-pulse annealing based on Gaussian beams.

[0103] Figure 7 This is a schematic diagram of the spatial distribution of Gaussian beam energy provided by the present invention, as shown below. Figure 7 The image shows the shape of the laser beam spot and its energy density distribution characteristics at the focal point of a pulsed laser. From... Figure 7 As can be seen in the three-dimensional view on the left, the effective spot shape is circular. In the two-dimensional spatial distribution, the vertical axis represents the peak energy density of the laser, and the horizontal axis represents the width direction (scanning direction) and length direction of the spot, respectively. Specifically, in the width direction, the laser energy density distribution exhibits a typical Gaussian distribution curve centered on the peak, showing strong intensity at the center and weak intensity at the edges; similarly, in the length direction, the laser energy density distribution also adopts a Gaussian distribution. This double Gaussian distribution characteristic on the two-dimensional plane indicates that the energy is highly concentrated at the center of the spot and decays exponentially outwards. This static distribution can be combined with the scanning motion using formula (3) to calculate the dynamic laser energy density distribution trend.

[0104] In another embodiment of the present invention, if the single-pulse laser is a flat-top beam, the peak energy density and static spatial energy distribution function of the single-pulse laser at the beam waist are obtained, including: determining the peak energy density based on the rectangular spot size of the flat-top beam and the single-pulse energy; and constructing the static spatial energy distribution function based on a piecewise linear function model.

[0105] The rectangular spot size of a flat-top beam refers to the geometric parameters of the rectangular region with uniform energy distribution that the laser spot exhibits on the focusing plane (beam waist) after beam shaping. For example, this size can be expressed as W×L, where W is the side length in the width direction (corresponding to the scanning direction) and L is the side length in the length direction.

[0106] A piecewise linear function model refers to a mathematical model that describes the energy density distribution of a light spot piecewise using multiple linear equations. For example, for an ideal flat-top beam, its energy distribution resembles a trapezoidal or rectangular wave, with constant energy in the middle region and a rapid decrease at the edges. This flat-top characteristic can be accurately approximated by a piecewise function.

[0107] Specifically, the relationship between the peak energy density of the flat-top beam and the laser power can be expressed as shown in formula (4): (4) in, For peak energy density, For laser power, Let be the area of ​​the rectangular light spot in the waisted plane, where W is the side length in the width direction, and L is the side length in the length direction. P2 is the repetition frequency of the laser beam, and P2 / f2 is the energy of a single pulse.

[0108] Based on peak energy density, dynamic spatial energy distribution function, and time-series output signal function, the energy density spatial distribution function is determined, including: determining dynamic displacement parameters based on laser scanning speed and time variables; updating the position coordinates of the piecewise linear function model based on the dynamic displacement parameters; and combining the peak energy density to determine the energy density spatial distribution function.

[0109] Specifically, in order to achieve consistency between the simulation and the actual spatial distribution of energy density of flat-top beam laser, this invention provides a universal spatial distribution function of energy density for flat-top beam dynamic laser. This spatial distribution function is distributed in the form of an approximately trapezoidal piecewise function (scanning direction, i.e., width direction), as shown in formula (5): (5) in, Let be the spatial distribution function of the energy density of the flat-top beam. The peak energy density of a single pulse in the waist plane is given by x (in formula (5), the segments are denoted as x1, x2, ..., x). m ( ) represents the coordinates of a point on the material surface in the scanning direction, indicating the actual spatial position of the laser beam; v is the laser scanning speed; and t is the pulse laser beam movement time. and These are the coefficients (slope and intercept) of each piecewise linear function, used to describe the rising edge, flat-top region, and falling edge of the trapezoidal distribution; arrive This represents the segmented position range of the flat-top beam on the coordinate axis.

[0110] The method for determining the process parameters of multi-pulse laser annealing provided by this invention introduces the peak energy density calculation formula and piecewise linear function model of the flat-top beam, which can accurately mathematically describe the rectangular or trapezoidal flat-top beam with uniform energy distribution characteristics. Combined with the dynamic update of the scanning motion, it realizes a high-fidelity simulation of the energy injection process when the flat-top laser beam moves on the material surface, providing a reliable calculation basis for predicting the large-area uniform annealing effect and temperature field distribution based on the flat-top beam.

[0111] Figure 8 This is a schematic diagram of the spatial distribution of the flat-top beam energy provided by the present invention, as shown below. Figure 8 The image shows the shape of the laser beam spot and its energy density distribution characteristics at the focal point of a pulsed laser. From... Figure 8 As can be seen in the three-dimensional view on the left, the laser spot is square or rectangular in shape, and the energy distribution exhibits a flat-topped, plateau-like structure. In the two-dimensional spatial distribution, the vertical axis represents the peak laser energy density, and the horizontal axis represents the width (scanning direction) and length of the laser spot, respectively.

[0112] Specifically, in the width direction, the laser energy density distribution exhibits a flat-top distribution, meaning that the energy density in most of the central area is close and remains uniform, while the energy density at both ends decreases rapidly. Similarly, in the length direction, the laser energy density distribution also adopts a flat-top distribution. This bidirectional flat-top distribution characteristic on a two-dimensional plane indicates that the laser energy is uniformly covered within the spot area, which is beneficial for achieving a large-area uniform annealing effect. Combining with formula (5), this approximately trapezoidal energy density distribution can be accurately described by a piecewise linear function, thereby realistically restoring the energy injection characteristics of the flat-top beam in numerical simulation.

[0113] Figure 9 This is a schematic diagram of the energy spatial distribution of the Gaussian beam and the flat-top beam provided by the present invention, as shown below. Figure 9 As shown, this embodiment demonstrates a hybrid laser beam energy distribution mode that combines Gaussian and flat-top distributions. The three-dimensional view reveals that the energy distribution of the beam exhibits different geometric characteristics in different directions. In the two-dimensional spatial distribution, the vertical axis represents the peak laser energy density, and the horizontal axis represents the width (scanning direction) and length of the beam, respectively.

[0114] Specifically, in the short axis direction, the laser energy density adopts a Gaussian distribution, exhibiting a bell-shaped curve with a high center and low sides, which conforms to the focusing characteristics of a natural Gaussian beam; while in the long axis direction, the laser energy density exhibits a flat-top distribution (or rectangular / trapezoidal distribution), showing that the energy in the middle area is uniform and close, while the energy in the edge area decays rapidly. This distribution pattern combines the advantages of Gaussian distribution in energy focusing and flat-top distribution in uniform energy coverage. By applying the calculation methods in formulas (3) and (5) respectively, this anisotropic composite energy density spatial distribution function can be constructed, thereby achieving rapid heating in the scanning direction while maintaining uniform energy injection over a large area in the stepping direction, meeting the specific requirements of anisotropic annealing processes.

[0115] Figure 10 This is a schematic diagram of the process for constructing a laser heat source model provided by the present invention, as shown below. Figure 10 As shown, as another optional embodiment provided by the present invention, a laser thermal source model is constructed based on the energy density spatial distribution function and the optical characteristic parameters of the device to be annealed, including but not limited to the following steps: Step 1010: Obtain the material type, reflectivity, transmittance, and absorption coefficient of the device to be annealed.

[0116] The material type of the device to be annealed refers to the classification of the various film layers that constitute the device structure and their optical properties. For example, the material can be a transparent material (such as silicon dioxide SiO2), a semi-transparent material (such as silicon nitride Si3N4, amorphous silicon), or a non-transparent material (such as tungsten W, aluminum Al, etc.).

[0117] Reflectivity refers to the proportion of incident laser energy reflected back by a material's surface. For example, the value of reflectivity typically ranges from 0 to 1, depending on the material's refractive index and the laser wavelength.

[0118] Transmittance refers to the proportion of energy remaining after a laser beam penetrates a material to the incident energy. For example, for completely opaque materials, transmittance is typically close to 0.

[0119] The absorption coefficient is a physical quantity that describes the degree of energy attenuation when light propagates in a medium, reflecting the material's ability to absorb light energy and convert it into heat energy.

[0120] Step 1020: If the material type is transparent or semi-transparent, a volume heat source model is constructed based on reflectivity, transmittance, absorption coefficient, and energy density spatial distribution function; if the material type is non-transparent, a surface heat source model is constructed based on reflectivity and energy density spatial distribution function.

[0121] Transparent or translucent materials refer to materials that have a certain ability to transmit laser light of a specific wavelength, allowing laser energy to penetrate deep into the material and be absorbed within a certain depth range. Examples include amorphous silicon thin films and silicon dioxide layers.

[0122] The volumetric heat source model refers to a distribution model that describes the attenuation of laser energy along the depth direction within a material and its conversion into heat energy. For example, for transparent and translucent materials, the spatial energy density distribution of the laser beam within the material also needs to consider the Beer-Lambert law, as shown in formula (6): (6) in, For laser energy density, The peak energy density of a single pulse in the waist plane. The absorption coefficient of the material. The thickness (or depth coordinate) of the material.

[0123] Furthermore, the heat source expressions for transparent and translucent materials are shown in formula (7): (7) in, The heat production rate per unit volume. The energy density spatial distribution function (specifically, it can be the aforementioned) or ), The pulse width. Let be the thickness (or depth coordinate) of the material, R, T, and a be the reflectivity, transmittance, and absorption coefficient, respectively, and g(t) be the time-series output signal function.

[0124] The surface heat source model describes a model in which laser energy is mainly concentrated on the surface of a material and absorbed, thus being converted into heat energy. It is suitable for materials that lasers cannot penetrate. For example, for non-transparent materials such as metal layers, the heat source expression is shown in formula (8): (8) in, The heat production rate per unit volume. The energy density spatial distribution function (specifically, it can be the aforementioned) or ), R is the pulse width, R is the reflectivity, and g(t) is the timing output signal function.

[0125] Step 1030: Determine the volume heat source model or surface heat source model as the laser heat source model.

[0126] Specifically, based on the properties of each layer of material in the device to be annealed, a corresponding bulk heat source model or surface heat source model is selected to construct the overall heat source distribution. For example, in the simulation of a multilayer structure containing transparent amorphous silicon and an underlying metal, a bulk heat source model is applied to the amorphous silicon, and a surface heat source model is applied to the underlying metal, thereby combining them to form a complete laser heat source model for subsequent numerical simulation calculations.

[0127] The method for determining the process parameters of multi-pulse laser annealing provided by this invention can accurately distinguish the exponential decay absorption characteristics of laser energy inside transparent and semi-transparent materials from the direct absorption characteristics on the surface of non-transparent materials by constructing volume heat source models and surface heat source models for materials with different transparency. This enables high-precision thermal simulation of the heating process of multilayer heterostructures in the device to be annealed.

[0128] Figure 11 This is a schematic diagram of the process for determining target process parameters provided by the present invention, such as... Figure 11 As shown, as another optional embodiment provided by the present invention, the target process parameters are determined based on the transient temperature field distribution and preset process standards, including but not limited to the following steps: Step 1110: Extract the highest temperature of the target film layer and the highest temperature of the underlying material in the device to be annealed from the transient temperature field distribution.

[0129] The target film layer refers to the functional material layer that needs to undergo physical or chemical changes (such as crystallization or activation) during the laser annealing process. For example, in semiconductor manufacturing, the target film layer usually refers to an amorphous silicon thin film, which needs to be transformed into polycrystalline silicon (poly-Si) through heating, melting, and recrystallization.

[0130] The underlying material refers to the material layer located beneath the target film layer, which serves a supporting or electrical connection function and needs to maintain structural integrity during annealing. For example, the underlying material can be a metal interconnect layer such as tungsten (W) or copper (Cu), or a temperature-sensitive dielectric layer.

[0131] Considering that in the actual multi-pulse laser annealing process, laser energy can penetrate the target film layer or be transferred to the underlying material through heat conduction, and if the temperature of the underlying material is too high, it will cause device failure, this invention extracts the highest temperature data of each layer of material through numerical simulation, which can quantitatively evaluate the thermal influence range of laser energy in the depth direction and provide a direct basis for judging the process window.

[0132] Step 1120: If the highest temperature of the target film is greater than or equal to the first phase transition temperature, and the highest temperature of the underlying material is less than the second phase transition temperature, then the combination of parameters used to generate the transient temperature field distribution, including pulse width, delay time, energy density of the single-pulse laser, and laser scanning speed, is determined as the target process parameters.

[0133] Specifically, the first phase transition temperature refers to the critical temperature at which the target film layer undergoes the required phase transition (such as melting), while the second phase transition temperature refers to the critical temperature at which the underlying material undergoes a destructive phase transition (such as melting or decomposition). For example, for amorphous silicon a-Si (which has no fixed phase transition temperature and depends on the fabrication process), this case uses a phase transition temperature of 1150℃ as an example. In the laser annealing process, the temperature of the target film layer is required to reach the phase transition temperature to achieve a certain depth of melting and recrystallization. However, in order to prevent thermal damage to each film layer, based on the thermophysical properties of each film layer material, the simulation calculation must ensure that the temperature does not reach its thermal damage threshold.

[0134] The method for determining the multi-pulse laser annealing process parameters provided by this invention can accurately determine whether the multi-pulse laser parameters meet the requirements for effective annealing of the target layer by comparing the highest temperature distribution of the target film during the simulation process, based on the material phase transformation characteristics, thereby quickly selecting the optimal laser energy injection and timing control scheme.

[0135] It should be noted that the calculation formulas and methods involved in this invention can be widely used in the numerical calculation of the temperature field of materials in devices irradiated by multiple pulsed lasers. In practical devices requiring annealing processes, the laser pulse wavelength in this invention can be selected from various options. As an optional embodiment, the laser wavelength can be 355nm, 527nm, 532nm, 808nm, or 1062nm, and is not limited to these wavelengths. The laser annealing spot can be a rectangular flat-topped square spot, or a Gaussian spot or a line spot. For the selection of laser parameters, the energy density range of multiple pulses can be adjusted separately, for example, 0-10 J / cm². 2 Adjust the laser pulse width, for example, 1-2µs; adjust the delay time between each pulse, for example, 0-1µs. Based on the above parameters, and by utilizing the different forms of pulsed laser timing signal output and the different spatial distribution forms of laser energy, the temperature field change trend obtained through numerical calculation can predict the pulsed laser parameters of multiple laser combinations to meet the laser annealing requirements and process effects of device manufacturing processes.

[0136] As an optional embodiment, in the following combination Figures 12 to 16 In the specific implementation case described, multiple sets of different laser parameters are selected based on the multi-pulse laser intensity distribution and the timing output signal. Considering the actual laser energy, yield, and market maturity, in this specific embodiment, four pulsed lasers with a green light source having a pulsed laser wavelength of 532nm are preferentially selected, with square spot sizes ranging from 5mm×5mm to 100mm×100mm, and employing... Figure 8 The energy distribution is shown. The pulse widths are respectively... , , , , the selected range is 0 - 0.2 µs; the single-pulse energy densities are ED1, ED2, ED3, and ED4 respectively, and the selected range is 0~1 J / cm 2 ; the delay time between the two laser beams is dey1, dey2, dey3, and the selected range is 0 - 1 µs.

[0137] Figure 12 is a schematic diagram of the case device structure provided by the present invention. As Figure 12 shown, it shows the stacked structure of the typical device to be annealed used in the present invention. The device to be annealed includes, from bottom to top in sequence: a silicon-based bottom layer (Si), a metal film layer (such as metal tungsten W) deposited on the Si substrate, an intermediate film layer deposited on the metal film layer, and a target film layer (such as amorphous silicon a-Si) deposited on the intermediate film layer.

[0138] Optionally, the intermediate film layer may include a single or multiple dielectric layers. For example, specifically, it may include a silicon dioxide film layer (SiO2) deposited on the metal film layer, and a silicon nitride film layer (Si3N4) deposited on the SiO2 film layer. In a specific embodiment, the thickness parameters of each layer can be set as follows: the thickness of the metal W film is 20 nm, the thickness of the SiO2 film is 70 nm, the thickness of the Si3N4 film is 50 nm, and the thickness of the top amorphous silicon a-Si thin film is 180 nm. The top amorphous silicon is the target film layer for laser annealing and needs to be heated and melted for recrystallization.

[0139] Since the combination of multi-pulse laser parameters is complex and variable (including parameters such as laser energy density, delay time, pulse width, etc.), the present invention only calculates some laser parameter combinations. The main purpose is to perform simulation calculations on the structural model case through laser parameters to see which parameter combination method is more conducive to the recrystallization of amorphous silicon.

[0140] Figure 13 is a schematic diagram of the temperature field under different delay time combination simulation conditions provided by the present invention according to the case structure. As Figure 13 shown, in this embodiment, it is set that the single-pulse energy density of each laser beam is equal (ED1 = ED2 = ED3 = ED4), and the delay time parameters between the two laser beams are set in the form of different change combinations. As Figure 13 shown in (a) of Figure 13 , the method of using the same and non-zero delay time between the two laser beams (dey1 = dey2 = dey3 ≠ 0) is used as combination 1; as Figure 13 shown in (b) of Figure 13As shown in (d) therein, the method of first decreasing and then increasing the delay time between two laser beams (dey1 > dey2 < dey3) is adopted as combination 4; as Figure 13 As shown in (e) therein, the method of first increasing and then decreasing the delay time between two laser beams (dey1 <dey2>(dey3), as combination 5, was used for comparative testing.

[0141] like Figure 13 As shown, the curve illustrates the temperature variation at the center point of the device under four-pulse laser irradiation with radial position (material thickness). Under this energy density condition, the first pulsed laser acts as a preheating agent. When the second pulsed laser is applied, the amorphous silicon surface begins to melt, and the surface temperature plateaus. As time increases, the temperature begins to rise. After the pulse ends, the material surface begins to cool, plateauing again at the solidification point. Subsequently, the temperature drops rapidly, and the molten amorphous silicon on the surface recrystallizes.

[0142] During this process, the temperature inside the amorphous silicon continues to increase due to thermal conduction, but the temperature deep within the amorphous silicon does not yet reach its melting point. Since amorphous silicon (a-Si) melts and then cools and crystallizes into polycrystalline silicon (poly-Si) during the initial pulsed laser treatment, the actual heating target of subsequent pulses becomes polycrystalline silicon. Therefore, the curve simultaneously marks the melting temperature of amorphous silicon (approximately 1150℃) and the melting temperature of polycrystalline silicon (approximately 1412℃) as reference lines. When the third and fourth pulsed lasers are applied, the temperature change of the device material exhibits various states. For example, the temperature of polycrystalline silicon rises to its melting point, and the temperature of the unmelted amorphous silicon continues to rise after being heated due to thermal conduction, showing plateau periods during temperature rise and temperature fall. Other combinations show phenomena such as polycrystalline silicon heating up but not reaching its melting point. Under the above five different combinations of conditions, the recrystallization phenomenon of amorphous silicon exhibits different temperature change trends.

[0143] In combination 1 (dey1=dey2=dey3≠0), with the same delay time, the 180nm thick amorphous silicon almost completely melts only after the fourth pulse laser action ends. Furthermore, the temperatures of Si3N4 (phase transition point >1600℃), SiO2 (phase transition point >950℃), and W layer (phase transition point >3410℃) in the film do not reach their damage thresholds. If the single pulse energy density is adjusted in this combination, the final temperature result can be predicted. In combination 2 (dey1>dey2>dey3), due to the gradually decreasing delay time, heat continues to accumulate at a high level. When the fourth pulsed laser is applied, the amorphous silicon completely melts, reaching a temperature of approximately 1305℃, without damaging other underlying materials. Theoretically, we can lower the laser energy density threshold to achieve the transformation process of the amorphous silicon film with a lower energy density. Experiments using this laser parameter combination show that this condition can achieve the melting and recrystallization of amorphous silicon, such as... Figure 14 The image shown is a transmission scanning electron microscope image after multi-pulse laser annealing, demonstrating the process of transforming amorphous silicon films into polycrystalline silicon.

[0144] Combination 3 (dey1 < dey2 < dey3). Since the delay time gradually increases, the temperature decreases more, and the heat accumulation is slow. After the fourth pulsed laser acts, the amorphous silicon with a thickness of 180 nm cannot be completely melted inside, indicating that this combination method is not conducive to the transformation process of the amorphous silicon film layer. If the single-pulse energy is increased to achieve the melting and recrystallization of amorphous silicon, it will cause waste of laser energy.

[0145] Combination 4 (dey1 > dey2 < dey3). Since the delay time between the second pulsed laser and the third pulsed laser is shorter, the heat accumulation between them increases significantly. After the third pulsed laser acts, all the amorphous silicon is melted, and the surface temperature is lower than the previous three groups. This combination is more suitable for the annealing process technology with lower surface temperature requirements; Combination 5 (dey1 <dey2>(dey3) Because the second and third pulsed lasers have the longest delay times, the temperature decreases significantly, and heat accumulation is reduced. However, when the delay times of the third and fourth pulsed lasers are shorter than those of the second and third pulsed lasers, heat accumulation increases rapidly. When the fourth pulsed laser is applied, the 180nm thick amorphous silicon completely melts. Figure 13 As can be seen in (e), this combination of conditions exhibits the uniformity of internal heat conduction characteristic of combination 1, as well as the low surface temperature characteristic of combination 4. Based on the above combined simulation conditions, it was found that the length of the delay time between pulsed laser beams in the selection of laser parameters has a crucial impact on the melting and recrystallization of amorphous silicon.

[0146] Figure 14 This is a transmission scanning electron microscope (SEM) image of the amorphous silicon of combination 2 provided by the present invention recrystallized into polycrystalline silicon after laser annealing, as shown in the image. Figure 14 As shown, the cross-sectional morphology of each film layer in the device after multi-pulse laser annealing can be clearly observed, among which the film layer marked with "Poly-Si" is the target film layer after phase transition. Figure 14 In the image, the entire film region marked "Poly-Si" exhibits distinct irregular light and dark contrasts and grain boundary textures. This indicates that the originally amorphous silicon has been fully melted and recrystallized under the action of the laser heat source, successfully transforming into polycrystalline silicon (Poly-Si). When using parameter configuration 2 (i.e., the delay time gradually decreases, dey1>dey2>dey3), the heat between pulses can continuously accumulate at a high level, causing the 180nm thick amorphous silicon to reach approximately 1305℃ and completely melt without causing thermal damage to the underlying insulating or metallic materials. Figure 14 The fully crystalline morphology and well-preserved multilayer structure of the amorphous silicon verified the extremely high accuracy of the numerical simulation model in predicting the depth and trend of the temperature field. Actual electron micrographs confirmed that the calculation method based on time-series and energy density simulation can accurately predict and select high-quality laser parameter windows conducive to the complete recrystallization of amorphous silicon, thus effectively avoiding the high costs associated with blind physical trial and error.

[0147] Figure 15 This is a schematic diagram of the temperature field under simulation conditions of different energy density combinations provided by the present invention based on the example structure. For example... Figure 15 As shown, in this embodiment, the delay time of every two laser pulses is set to be equal (dey1=dey2=dey3). The energy density of each laser pulse is set to different combinations. Due to the complexity of the combinations, only some representative results are selected for analysis and explanation. Combination 6 uses a gradually decreasing energy density of each laser pulse (ED1>ED2>ED3>ED4). Figure 15 In (a), it is the transient temperature curve of the highest temperature of each layer material in the device changing with time. Due to the relatively large energy density of the first laser beam, amorphous silicon phase transformation and melting occur on the surface. Then, the laser energy density gradually decreases, and the heat accumulation reduces. However, after the fourth pulse ends, the amorphous silicon can achieve a completely melted and recrystallized state. For this laser parameter combination, experiments are carried out and it is found that this condition can achieve the melting and recrystallization of amorphous silicon. As Figure 16 shown is the transmission scanning electron microscope photo after multi-pulse laser annealing, Figure 16 which shows that the size of the polycrystalline silicon grains after annealing is smaller than that of combination 2, and the process of transforming the amorphous silicon film layer into polycrystalline silicon is realized.

[0148] Adopting the method of gradually increasing the energy density of each laser beam (ED1 < ED2 < ED3 < ED4), as combination 7, Figure 15 In (b), it is the transient temperature curve of the highest temperature of each layer material in the device changing with time. Due to the gradually increasing laser energy density, the heat accumulation is gradually obvious. After the fourth pulse ends, the amorphous silicon can achieve a completely melted and recrystallized state. However, compared with combination 6, its energy density can also be reduced, and the transformation process of the amorphous silicon film layer can be realized with a lower energy density. Based on the above simulation calculations, under the condition that the delay time of each pulsed laser remains unchanged, the temperature change of heat accumulation can be predicted by changing the size of the energy density alone.

[0149] Since there are too many changes in the laser parameter combination, it is extremely difficult to find a suitable laser annealing process window through experiments. Therefore, it is very necessary to understand the changing trend of the temperature field distribution of the device structure with the laser parameter combination through simulation calculations in order to find a suitable laser parameter window.

[0150] Figure 16 is the transmission scanning electron microscope photo of the recrystallization of the amorphous silicon of combination 6 provided by the present invention into polycrystalline silicon after laser annealing. As Figure 16 shown, in Figure 16 the cross-sectional morphology of the multi-film layer of the device after multi-pulse laser annealing treatment can be clearly observed. The area marked with the English letter "Poly-Si" is the target film layer after phase change. In Figure 16 the entire film layer where the "Poly-Si" mark is located shows obvious grain boundary textures, and clearly indicates the overall thickness of the target film layer.

[0151] This intuitively demonstrates that, with parameter configuration 6 (i.e., equal delay times for each adjacent laser pulse, but gradually decreasing single-pulse energy density, ED1>ED2>ED3>ED4), the surface melts first due to the higher energy density of the first pulse. Although the energy density of subsequent pulses gradually decreases, leading to less heat accumulation, the amorphous silicon still achieves complete melting and recrystallization from the surface inwards after the fourth pulse, successfully transforming into polycrystalline silicon. Furthermore, combined with the aforementioned experimental analysis, it can be seen that, compared to the morphology of configuration 2, Figure 16 The polycrystalline silicon particles formed after intermediate annealing are relatively smaller in size, but the process goal of transforming amorphous silicon films into polycrystalline silicon is still successfully achieved. Figure 16 The actual electron microscope images further verified that, under the condition of constant delay time, the numerical simulation model can accurately predict the influence of decreasing energy density on the heat accumulation trend and the final crystal morphology, providing a highly reliable theoretical basis for efficiently finding and optimizing the laser parameter window.

[0152] Figure 17 This is a schematic diagram of the device for determining the multi-pulse laser annealing process parameters provided by the present invention, as shown below. Figure 17 As shown, it mainly includes, but is not limited to: The timing model construction module 1710 is used to determine the timing output signal function based on the pulse width and the delay time between adjacent laser pulses.

[0153] The spatial distribution determination module 1720 is used to determine the spatial distribution function of energy density based on the spatial energy distribution of the single-pulse laser at the beam waist, the laser scanning speed, and the timing output signal function.

[0154] The temperature field simulation module 1730 is used to construct a laser heat source model based on the energy density spatial distribution function and the optical characteristic parameters of the device to be annealed, and to perform numerical simulation based on the laser heat source model to obtain the transient temperature field distribution of the device to be annealed during the laser scanning process.

[0155] The process parameter determination module 1740 is used to determine the target process parameters based on the transient temperature field distribution and preset process standards.

[0156] It should be noted that the device for determining the multi-pulse laser annealing process parameters provided by the present invention can execute the method for determining the multi-pulse laser annealing process parameters described in any of the above embodiments during specific operation, and will not be elaborated on in this embodiment.

[0157] The device for determining multi-pulse laser annealing process parameters provided by the present invention establishes a timing output signal function and an energy density spatial distribution function, and then constructs an accurate laser heat source model for numerical simulation. This enables the prediction of transient temperature field distribution during laser scanning, accurately obtains laser parameters that meet the specific device process requirements, and reduces experimental costs.

[0158] Figure 18 This is a schematic diagram of the structure of the electronic device provided by the present invention, such as... Figure 18 As shown, the electronic device may include: a processor 1810, a communication interface 1820, a memory 1830, and a communication bus 1840. The processor 1810, communication interface 1820, and memory 1830 communicate with each other via the communication bus 1840. The processor 1810 can call logic instructions in the memory 1830 to execute a method for determining multi-pulse laser annealing process parameters. This method includes: determining a timing output signal function based on the pulse width and the delay time between adjacent laser pulses; determining an energy density spatial distribution function based on the spatial energy distribution of a single-pulse laser at the beam waist, the laser scanning speed, and the timing output signal function; constructing a laser heat source model based on the energy density spatial distribution function and the optical characteristic parameters of the device to be annealed; performing numerical simulation based on the laser heat source model to obtain the transient temperature field distribution of the device to be annealed during the laser scanning process; and determining the target process parameters based on the transient temperature field distribution and preset process standards.

[0159] Furthermore, the logical instructions in the aforementioned memory 1830 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, essentially, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0160] On the other hand, the present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the method for determining the multi-pulse laser annealing process parameters provided by the above methods. The method includes: determining a timing output signal function based on the pulse width and the delay time between adjacent laser pulses; determining an energy density spatial distribution function based on the spatial energy distribution of a single-pulse laser at the beam waist, the laser scanning speed, and the timing output signal function; constructing a laser heat source model based on the energy density spatial distribution function and the optical characteristic parameters of the device to be annealed; performing numerical simulation based on the laser heat source model to obtain the transient temperature field distribution of the device to be annealed during the laser scanning process; and determining the target process parameters based on the transient temperature field distribution and the preset process standard.

[0161] In another aspect, the present invention also provides a non-transitory computer-readable storage medium storing a computer program thereon. When executed by a processor, the computer program implements a method for determining the multi-pulse laser annealing process parameters provided by the methods described above. The method includes: determining a timing output signal function based on the pulse width and the delay time between adjacent laser pulses; determining an energy density spatial distribution function based on the spatial energy distribution of a single-pulse laser at the beam waist, the laser scanning speed, and the timing output signal function; constructing a laser heat source model based on the energy density spatial distribution function and the optical characteristic parameters of the device to be annealed; performing numerical simulation based on the laser heat source model to obtain the transient temperature field distribution of the device to be annealed during the laser scanning process; and determining the target process parameters based on the transient temperature field distribution and a preset process standard.

[0162] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0163] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0164] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining the process parameters of multi-pulse laser annealing, characterized in that, include: The timing output signal function is determined based on the pulse width and the delay time between adjacent laser pulses. Based on the spatial energy distribution of the single-pulse laser at the beam waist, the laser scanning speed, and the timing output signal function, the spatial distribution function of energy density is determined. Based on the energy density spatial distribution function and the optical characteristic parameters of the device to be annealed, a laser heat source model is constructed, and numerical simulation is performed based on the laser heat source model to obtain the transient temperature field distribution of the device to be annealed during the laser scanning process. Based on the transient temperature field distribution and the preset process standards, the target process parameters are determined.

2. The method for determining the process parameters of multi-pulse laser annealing according to claim 1, characterized in that, The determination of the timing output signal function based on the pulse width and the delay time between adjacent laser pulses includes: Based on the pulse width, a normalization function characterizing the intensity of a single-pulse laser is constructed; Based on the delay time between adjacent laser pulses, calculate the time offset of each single laser pulse in the multi-pulse laser beam relative to the first single laser pulse. Based on the time offset and the normalization function, the delay signal function corresponding to each single-pulse laser is determined, and the timing output signal function is determined based on each of the delay signal functions.

3. The method for determining the process parameters of multi-pulse laser annealing according to claim 2, characterized in that, The determination of the energy density spatial distribution function based on the spatial energy distribution of the single-pulse laser at the beam waist, the laser scanning speed, and the timing output signal function includes: Obtain the peak energy density and static spatial energy distribution function of a single-pulse laser at the beam waist; Based on the laser scanning speed and time variables, determine the dynamic displacement parameters; Based on the dynamic displacement parameters and the static spatial energy distribution function, the dynamic spatial energy distribution function is determined; The energy density spatial distribution function is determined based on the peak energy density, the dynamic spatial energy distribution function, and the time-series output signal function.

4. The method for determining the process parameters of multi-pulse laser annealing according to claim 3, characterized in that, If the single-pulse laser is a Gaussian beam, obtaining the peak energy density and static spatial energy distribution function of the single-pulse laser at the beam waist includes: The peak energy density is determined based on the effective radius of the waist of the Gaussian beam and the single-pulse energy. The static spatial energy distribution function is constructed based on the Gaussian function model; The step of determining the energy density spatial distribution function based on the peak energy density, the dynamic spatial energy distribution function, and the time-series output signal function includes: The dynamic displacement parameter is determined based on the laser scanning speed and the timing output signal function; The position coordinates of the Gaussian function model are updated based on the dynamic displacement parameters, and the energy density spatial distribution function is determined by combining the updated position coordinates with the peak energy density.

5. The method for determining the process parameters of multi-pulse laser annealing according to claim 3, characterized in that, If the single-pulse laser is a flat-top beam, obtaining the peak energy density and static spatial energy distribution function of the single-pulse laser at the beam waist includes: The peak energy density is determined based on the rectangular spot size of the flat-top beam and the single-pulse energy. The static spatial energy distribution function is constructed based on a piecewise linear function model; The step of determining the energy density spatial distribution function based on the peak energy density, the dynamic spatial energy distribution function, and the time-series output signal function includes: The dynamic displacement parameter is determined based on the laser scanning speed and the time variable; The position coordinates of the piecewise linear function model are updated based on the dynamic displacement parameters, and the energy density spatial distribution function is determined by combining the peak energy density.

6. The method for determining the process parameters of multi-pulse laser annealing according to any one of claims 4 or 5, characterized in that, The laser thermal source model is constructed based on the energy density spatial distribution function and the optical characteristic parameters of the device to be annealed, including: Obtain the material type, reflectivity, transmittance, and absorption coefficient of the device to be annealed; If the material type is transparent or translucent, a volume heat source model is constructed based on the reflectivity, transmittance, absorption coefficient, and energy density spatial distribution function; if the material type is non-transparent, a surface heat source model is constructed based on the reflectivity and energy density spatial distribution function. The volume heat source model or the surface heat source model is determined as the laser heat source model.

7. The method for determining the process parameters of multi-pulse laser annealing according to claim 1, characterized in that, The determination of target process parameters based on the transient temperature field distribution and preset process standards includes: Extract the highest temperature of the target film layer and the highest temperature of the underlying material in the device to be annealed from the transient temperature field distribution; If the highest temperature of the target film is greater than or equal to the first phase transition temperature, and the highest temperature of the underlying material is less than the second phase transition temperature, then the combination of parameters used to generate the transient temperature field distribution—pulse width, delay time, energy density of the single-pulse laser, and laser scanning speed—is determined as the target process parameters.

8. A device for determining the process parameters of multi-pulse laser annealing, characterized in that, include: The timing model construction module is used to determine the timing output signal function based on the pulse width and the delay time between adjacent laser pulses; The spatial distribution determination module is used to determine the energy density spatial distribution function based on the spatial energy distribution of the single-pulse laser at the beam waist, the laser scanning speed, and the timing output signal function. The temperature field simulation module is used to construct a laser heat source model based on the energy density spatial distribution function and the optical characteristic parameters of the device to be annealed, and to perform numerical simulation based on the laser heat source model to obtain the transient temperature field distribution of the device to be annealed during the laser scanning process. The process parameter determination module is used to determine the target process parameters based on the transient temperature field distribution and the preset process standards.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the method for determining the multi-pulse laser annealing process parameters as described in any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the method for determining the multi-pulse laser annealing process parameters as described in any one of claims 1 to 7.

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