Laser annealing system

Abstract

This application discloses a laser annealing system, comprising: a laser for generating a laser beam and focusing it onto a predetermined area of ​​a wafer to form a spot on the wafer surface; a camera for acquiring an image of the spot; a spot analysis system communicatively connected to the camera for analyzing the image of the spot to obtain temperature information of the spot; and a controller communicatively connected to both the laser and the spot analysis system, configured to adjust the energy of the laser beam based on the temperature information of the spot. This avoids the problem of excessively high actual temperature on the wafer surface due to laser overcompensation, thereby improving the annealing quality.

Description

Technical Field

[0001] This application relates to the semiconductor field, and more specifically to a laser annealing system. Background Technology

[0002] In the semiconductor fabrication process, one of the steps involves annealing the wafer using laser annealing to activate the doped ions.

[0003] In the relevant laser annealing system, a closed-loop temperature control method is adopted. The temperature sampling area of ​​the temperature sensor is aligned with the center of the laser spot to collect the optical signal of the temperature sampling area, and the detection temperature at the center of the laser spot is determined based on the collected optical signal. Then, based on the detection temperature, the energy of the laser beam output by the laser is adjusted to achieve closed-loop temperature control.

[0004] However, in related technologies, the actual temperature on the wafer surface can be too high, which reduces the annealing quality. Summary of the Invention

[0005] This application is made to address the aforementioned problems. According to one aspect of this application, a laser annealing system is provided, comprising:

[0006] A laser is used to generate a laser beam and focus the laser beam onto a predetermined area of ​​a wafer to form a spot on the wafer surface;

[0007] A camera device used to capture images of light spots;

[0008] A spot analysis system that communicates with a camera device is used to analyze the image of the spot to obtain the temperature information of the spot;

[0009] A controller that is communicatively connected to both the laser and the spot analysis system is configured to adjust the energy of the laser beam based on the temperature information of the spot.

[0010] In some embodiments of this application, the spot analysis system is used to calculate the gray value of the spot and obtain the temperature information of the spot based on the gray value.

[0011] In some embodiments of this application, the spot analysis system is used to: obtain the temperature information of the spot based on the gray value of the spot and the gray value-temperature correspondence;

[0012] The grayscale value-temperature correspondence was obtained through prior testing.

[0013] In some embodiments of this application, the spot analysis system is used to: determine the target grayscale value range based on the target temperature value, a preset error range, and the grayscale value-temperature correspondence.

[0014] In some embodiments of this application, when the grayscale value of the light spot is within the target grayscale value range, the temperature information of the light spot is determined to be normal; and / or,

[0015] When the gray value of the light spot is outside the target gray value range, the temperature information of the light spot is determined to be an abnormal light spot temperature.

[0016] In some embodiments of this application, the controller is configured to adjust the energy of the laser beam when the temperature information of the light spot indicates that the light spot temperature is abnormal, so that the gray value of the light spot is within the target gray value range.

[0017] In some embodiments of this application, the target temperature value is determined based on the target resistance value and the resistance-temperature correspondence; wherein the resistance-temperature correspondence is obtained through prior testing.

[0018] In some embodiments of this application, the laser annealing system further includes:

[0019] A temperature measuring device is used to align the sampling area with a preset area on the wafer surface to collect the light signal of the sampling area and determine the sampling temperature of the light spot as a first temperature based on the light signal.

[0020] The controller is also used to adjust the energy of the laser beam based on the first temperature.

[0021] In some embodiments of this application, the temperature information of the light spot includes: the temperature obtained by analyzing the image of the light spot is a second temperature;

[0022] The controller is configured as follows:

[0023] When the absolute difference between the second temperature and the first temperature is less than or equal to a preset threshold, the energy of the laser beam is adjusted based on the first temperature, the second temperature, or the average of the first temperature and the second temperature; and / or,

[0024] When the absolute difference between the second temperature and the first temperature is greater than a preset threshold, an alarm message is issued or the energy of the laser beam is adjusted based on the second temperature.

[0025] In some embodiments of this application, the controller is also configured to:

[0026] After issuing an alarm message, obtain the resistance value of the wafer;

[0027] Based on the resistance value and the correspondence between resistance value and temperature, the actual annealing temperature is obtained, and the status of the temperature measuring device is determined based on the actual annealing temperature and the first temperature.

[0028] Based on the correspondence between the actual annealing temperature and the gray value-temperature, the actual gray value is obtained, and the status of the camera device is determined based on the actual gray value and the gray value calculated by the spot analysis system.

[0029] According to the laser annealing system provided in this application embodiment, an image of the laser spot is acquired using a camera device, and the image of the laser spot is analyzed using a laser spot analysis system to obtain the temperature information of the laser spot. The controller adjusts the energy of the laser beam based on the temperature information of the laser spot. Since the camera device acquires the entire image of the laser spot, changes in the temperature of the laser spot will be reflected in the changes in the image of the laser spot. By obtaining the temperature information of the laser spot based on the image of the laser spot, the problem of inaccurate temperature detection caused by the temperature sampling area deviating from the center of the laser spot can be avoided. Accurate temperature information of the laser spot can be obtained, thereby improving the accuracy of laser beam energy adjustment and avoiding the problem of excessively high actual temperature on the wafer surface due to laser overcompensation, thus improving the annealing quality. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the structure of a laser annealing system according to an embodiment of this application;

[0032] Figure 2 This is a schematic diagram illustrating the grayscale value-temperature correspondence and the resistance value-temperature correspondence in an embodiment of this application;

[0033] Figure 3 This is a schematic diagram of the structure of a laser annealing system according to another embodiment of this application;

[0034] Figure 4 This is a schematic block diagram illustrating the workflow of a laser annealing system according to an embodiment of this application;

[0035] Figure 5 This is an alignment diagram showing the preset area to be annealed, the light spot, and the sampling area in an undisplaced state, as illustrated in an embodiment of this application.

[0036] Figure 6 This is an alignment diagram illustrating the pre-set area to be annealed, the light spot, and the sampling area in a deviated state, as shown in an embodiment of this application.

[0037] Figure label:

[0038] 10-Laser 11-Laser Beam

[0039] 12-spot 20-wafer

[0040] 21-Preset area 31-Camera device

[0041] 32-Spot Analysis System 40-Controller

[0042] 50 - Temperature measuring device; 51 - Sampling area Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this application more apparent, exemplary embodiments according to this application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments of this application. It should be understood that this application is not limited to the exemplary embodiments described herein. Based on the embodiments of this application described herein, all other embodiments obtained by those skilled in the art without inventive effort should fall within the protection scope of this application.

[0044] The following description provides numerous specific details to offer a more thorough understanding of this application. However, it will be apparent to those skilled in the art that this application can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described to avoid confusion with this application.

[0045] It should be understood that this application can be implemented in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of this application to those skilled in the art.

[0046] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, confirm the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0047] To fully understand this application, a detailed structure will be presented in the following description to illustrate the technical solution proposed in this application. Optional embodiments of this application are described in detail below; however, in addition to these detailed descriptions, this application may have other implementation methods.

[0048] In related laser annealing systems, a closed-loop temperature control method is employed, with the temperature sensor's sampling area located at the center of the laser spot. When the laser beam irradiates the wafer surface, the temperature sensor aligns its sampling area with the center of the laser spot to collect the optical signal from that area and determines the detected temperature at the center of the laser spot based on the collected signal. Then, based on the detected temperature, the energy of the laser beam output from the laser is adjusted to achieve closed-loop temperature control. Specifically, when the optical signal collected by the temperature sensor fluctuates, it is fed back to the laser's temperature control system. The temperature control system calculates the energy that needs to be compensated or deducted based on the change in the optical signal collected by the temperature sensor, generates a corresponding control command, and sends the control command to the laser to adjust the laser beam energy, thus achieving closed-loop temperature control.

[0049] The temperature at the center of the laser spot is often the highest, and the central region also tends to radiate the most light information. In related technologies, when the temperature sampling area of ​​the temperature sensor deviates from the center of the laser spot, the amount of light signal collected by the temperature sensor from the sampling area decreases, resulting in a lower detected temperature. However, the actual light signal at the center of the laser spot does not decrease, meaning the actual temperature at the center of the laser spot does not decrease. Consequently, the detected temperature by the temperature sensor is lower than the actual temperature at the center of the laser spot, rendering the temperature sensor's detection inaccurate. When adjusting the laser beam energy based on the detected temperature, the decrease in detected temperature triggers a compensation command to the laser, increasing the laser beam energy. After adjusting the laser beam energy based on the detected temperature, the actual temperature at the center of the laser spot increases, leading to overcompensation of the laser and an excessively high actual temperature on the wafer surface, thus reducing annealing quality. Moreover, this problem cannot be detected in a timely manner by existing technologies. It is often only discovered when anomalies occur during final electrical testing of the wafer, requiring tracing and analysis of the cause of the anomaly. This can easily lead to significant changes in the performance of a large number of products.

[0050] To address at least some of the technical problems in the aforementioned related technologies, this application proposes the following embodiments.

[0051] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0052] First, let me introduce the laser annealing system illustrated in this application, referring to... Figure 1 and Figure 5 The laser annealing system includes:

[0053] Laser 10 is used to generate a laser beam 11 and focus the laser beam 11 onto a preset area 21 of wafer 20 to form a spot 12 on the surface of wafer 20.

[0054] Camera device 31 is used to capture images of light spot 12;

[0055] A spot analysis system 32 is communicatively connected to the camera device 31. The spot analysis system 32 is used to analyze the image of the spot 12 to obtain the temperature information of the spot 12.

[0056] A controller 40 is communicatively connected to both the laser 10 and the spot analysis system 32. The controller 40 is configured to adjust the energy of the laser beam 11 based on the temperature information of the spot 12.

[0057] The above embodiments have the following beneficial effects: by using a camera device 31 to acquire an image of the light spot 12, and using a light spot analysis system 32 to analyze the image of the light spot 12 to obtain the temperature information of the light spot 12, the controller 40 adjusts the energy of the laser beam 11 based on the temperature information of the light spot 12. Since the camera device 31 acquires the entire image of the light spot 12, changes in the temperature of the light spot 12 will be reflected in changes in the image of the light spot 12. By obtaining the temperature information of the light spot 12 based on the image of the light spot 12, the problem of inaccurate temperature detection caused by the temperature sampling area 51 deviating from the center of the light spot 12 can be avoided. Accurate temperature information of the light spot 12 can be obtained, thereby improving the accuracy of the energy adjustment of the laser beam 11 and avoiding the problem of the actual temperature of the wafer surface being too high due to overcompensation of the laser 10, thereby improving the annealing quality.

[0058] The following is a detailed description of each structure.

[0059] When configuring laser 10, laser 10 can be any laser capable of emitting a laser beam 11 for annealing. For example, laser 10 can be a CO2 laser, and the wavelength of the laser beam 11 can be around 10.6 μm. (See reference...) Figure 1 The laser beam 11 generated by the laser 10 is focused on a preset area 21 of the wafer 20 to form a light spot 12 on the surface of the wafer 20. Specifically, the laser beam 11 can be focused on the surface of the wafer 20 or at a certain depth position of the wafer 20, so as to form a light spot 12 on the surface of the wafer 20.

[0060] For example, refer to Figure 1 Structures such as doped regions can be formed on wafer 20 so that the ions implanted in the doped regions can be activated after annealing.

[0061] The aforementioned camera device 31 is used to acquire images of the light spot 12. The camera device 31 can be, for example, but not limited to, a specially designed camera. During the acquisition of the image of the light spot 12, the camera device 31 can include the light spot 12 within its image acquisition area, thus ensuring that the image captured by the camera device 31 contains the image of the light spot 12. Subsequently, the image captured by the camera device 31 can be processed using methods such as, but not limited to, recognition algorithms, to obtain the image of the light spot 12.

[0062] refer to Figure 1 The spot analysis system 32 is communicatively connected to the camera device 31 to receive the image of the spot 12 collected by the camera device 31 and analyze the image of the spot 12 to obtain the temperature information of the spot 12.

[0063] It should be noted that the spot analysis system 32 can be integrated into the controller 40, and the spot analysis system 32 is a functional module of the controller 40. Of course, the spot analysis system 32 can also be integrated into other logic operation modules outside of the controller 40.

[0064] There are various ways to analyze the image of the light spot 12 by the light spot analysis system 32 to obtain the temperature information of the light spot 12. Some methods are described below as examples.

[0065] For example, the spot analysis system 32 is used to calculate the gray value of the spot 12 and obtain the temperature information of the spot 12 based on the gray value of the spot 12.

[0066] The above embodiments have the following beneficial effects: By utilizing the characteristic that the temperature of the light spot 12 changes when the grayscale value of the image changes, that is, by utilizing the strong correlation between the grayscale value of the image of the light spot 12 and the temperature of the light spot 12, the temperature information of the light spot 12 can be obtained by calculating the grayscale value of the light spot 12 and based on the grayscale value of the light spot 12, thus obtaining accurate temperature information of the light spot 12. Furthermore, it simplifies the difficulty of performing temperature analysis on the image of the light spot 12.

[0067] There are various methods for calculating the grayscale value of spot 12. For example, in some embodiments, only the grayscale value of the central region of spot 12 can be calculated, and the temperature information of spot 12 in this case only represents the temperature information of the central region of spot 12. In other embodiments, the grayscale value of all regions of spot 12 can also be calculated, and the temperature information of spot 12 in this case represents the temperature information of the entire area of ​​spot 12.

[0068] Of course, in other embodiments, a neural network analysis model based on the image of the light spot 12 can also be established, and the image of the light spot 12 can be input into the neural network analysis model to directly obtain the temperature information of the light spot 12.

[0069] For example, the spot analysis system 32 is used to: obtain the temperature information of spot 12 based on the gray value of spot 12 and the gray value-temperature correspondence; wherein the gray value-temperature correspondence is obtained by pre-testing.

[0070] The above embodiments have the following beneficial effects: by obtaining the gray value-temperature correspondence through pre-testing, the temperature information of the light spot 12 can be directly measured based on the gray value of the light spot 12, so as to adjust the energy of the laser beam 11 based on accurate temperature information, thereby improving the accuracy of energy adjustment and providing annealing effect.

[0071] For example, based on the gray value of spot 12 and the gray value-temperature correspondence, the temperature information of spot 12 can be obtained as follows: the sampling temperature of spot 12 is the second temperature, so as to obtain a determined temperature value.

[0072] To obtain the specific grayscale value-temperature correspondence, a temperature experiment can be used. (Reference) Figure 2 This allows us to obtain the grayscale values ​​of light spot 12 at multiple temperature values, and then fit the obtained experimental data to obtain the grayscale value-temperature correspondence. (Reference) Figure 2 The grayscale value-temperature correspondence can be represented as y = 1.1068x - 981.14, with a coefficient of determination R. 2 = 0.9984. In this formula, the dependent variable y represents the grayscale value of the image of spot 12, the independent variable x represents the temperature, and the coefficient of determination R... 2 A value greater than 0.99 indicates that the difference between the observed value and the model value is very small, and the fit is very high. After calculating the gray value of spot 12, the gray value-temperature correspondence can be substituted to obtain the sampling temperature of spot 12 as the second temperature.

[0073] Of course, in other embodiments, the method of obtaining the temperature information of spot 12 by performing temperature analysis based on the gray value of spot 12 can also be other methods.

[0074] For example, the spot analysis system 32 is used to: determine the target gray value range based on the target temperature value, the preset error range, and the correspondence between gray value and resistance value.

[0075] The above embodiments have the following beneficial effects: By setting a large or small preset error range, a target gray value range can be obtained based on the target gray value, and the temperature information of the light spot 12 can be determined based on the gray value of the light spot 12 and the target gray value range. Thus, by controlling the size of the preset error range, the gray value of the light spot 12 can be controlled to reach the accuracy of the target gray value, so as to control the annealing temperature of the wafer 20 to be kept within the range of the target temperature value or near the target temperature value, thereby achieving controllable error.

[0076] For example, the preset error range can be a positive value. The difference between the target gray value and the preset error range can be used as the lower limit of the target gray value range, and the sum of the target gray value and the preset error range can be used as the upper limit of the target gray value range, thereby simplifying the determination of the target gray value range.

[0077] For example, when the gray value of spot 12 is within the target gray value range, it means that the difference between the gray value of spot 12 and the target gray value is not large, and the gray value of spot 12 is close to the target gray value. After annealing the wafer 20 with the current energy of laser beam 11, the annealing temperature of wafer 20 can be made close to the target temperature value, and the error is within an acceptable range. It can be determined that the temperature information of spot 12 is normal, and the energy of laser beam 11 does not need to be adjusted. It is sufficient to maintain the current energy of laser beam 11 for output.

[0078] For example, when the gray value of spot 12 is outside the target gray value range, it indicates that the difference between the gray value of spot 12 and the target gray value is large. After annealing the wafer 20 with the current energy of the laser beam 11, the difference between the annealing temperature of the wafer 20 and the target temperature value is large, and the error exceeds the acceptable range. It can be determined that the temperature information of spot 12 is abnormal, so that the energy of the laser beam 11 can be adjusted in the future to improve the annealing accuracy.

[0079] For example, the controller 40 is configured to adjust the energy of the laser beam 11 when the temperature information of the spot 12 indicates that the spot temperature is abnormal, so that the gray value of the spot 12 is within the target gray value range.

[0080] The above embodiments have the following beneficial effects: if the temperature information of the light spot 12 is abnormal, the gray value of the light spot 12 can be adjusted by adjusting the energy of the laser beam 11 so that the gray value of the light spot 12 is within the target gray value range, and the gray value of the light spot 12 is close to the target gray value, thereby enabling the annealing temperature of the wafer 20 to be close to the target temperature value and improving the annealing quality.

[0081] There are several ways to determine the target temperature value. One method is described below as an example.

[0082] For example, the target temperature value is determined based on the target resistance value and the resistance-temperature correspondence; wherein the resistance-temperature correspondence is obtained through prior testing. By determining the target temperature value based on the target resistance value and the resistance-temperature correspondence, the determined target temperature value is made more accurate, resulting in a more accurate target annealing temperature. Therefore, when the actual annealing temperature of wafer 20 by the laser is close to the target annealing temperature, it can be ensured that the resistance value of wafer 20 after annealing is close to the target resistance value, thus improving the annealing quality.

[0083] There are several methods to obtain the resistance-temperature relationship. For example, a temperature experiment can also be used to obtain this relationship. (Reference) Figure 2 The relationship between resistance and temperature can be expressed as y = -0.3378x + 469.52, with a coefficient of determination R. 2 = 0.9997. In this formula, the dependent variable y represents the resistance value of the wafer after 20mm annealing, the independent variable x represents the temperature, and the coefficient of determination R... 2 A value greater than 0.99 indicates that the difference between the observed values ​​and the model values ​​is very small, and the fit is very high.

[0084] An example is described below. First, experiments are conducted to obtain the correspondence between resistance value and temperature, and the correspondence between grayscale value and resistance value, which serve as the basis for characterizing the true temperature of spot 12 based on its grayscale value. Next, the target resistance value is obtained according to process requirements, and the target temperature value is determined based on the target resistance value and the resistance-temperature correspondence. Based on a preset error range, the upper limit A2 and lower limit A1 of the target grayscale value range are obtained. Then, during the annealing process of wafer 20, the camera device 31 acquires images of spot 12 in real time, and the spot analysis system 32 calculates the grayscale value A of the image of spot 12 in real time, determining whether the grayscale value A of spot 12 is within the range [A1, A2]. If the grayscale value of spot 12 is within the target grayscale value range, the temperature information of spot 12 is determined to be normal. If the grayscale value of spot 12 is outside the target grayscale value range, the temperature information of spot 12 is determined to be abnormal, indicating that the true temperature may be drifting. Subsequently, if the temperature information of spot 12 indicates an abnormal spot temperature, the energy of the laser beam 11 of laser 10 can be adjusted. The adjustment method can be a compensation command to increase the energy of laser beam 11, or a reduction command to decrease the energy of laser beam 11, to ensure that the gray value of spot 12 is within the target gray value range.

[0085] For example, refer to Figure 3 , Figure 4 and Figure 5The laser annealing system may further include: a temperature measuring device 50, which is used to align the sampling area 51 with the preset area 21 of the wafer 20 to collect the optical signal of the sampling area 51 and determine the sampling temperature of the spot 12 as a first temperature based on the optical signal; and the controller 40 is also used to adjust the energy of the laser beam 11 based on the first temperature.

[0086] It should be noted that the reference Figure 5 When the sampling area 51 is aligned with the preset area 21 of the wafer 20 without deviation, and the laser beam 11 of the laser 10 is focused on the preset area 21 aligned with the wafer 20 without deviation, the reference... Figure 5 The sampling area 51 mentioned above can coincide with the central area of ​​the light spot 12. (See reference...) Figure 6 However, when the laser beam 11 of the laser 10 is focused on the preset area 21 aligned with the wafer 20 and there is no deviation, if the sampling area 51 deviates from the preset area 21 of the wafer 20, the area of ​​the sampling area 51 overlapping with the center area of ​​the light spot 12 will become smaller, causing the light signal collected by the temperature measuring device 50 from the sampling area 51 to be attenuated, which in turn causes the temperature measured by the temperature measuring device 50 to be lower than the center area of ​​the light spot 12.

[0087] The above embodiments have the following beneficial effects: In addition to obtaining the temperature information of the light spot 12 by temperature analysis based on the image of the light spot 12, a temperature measuring device 50 based on optical signals is also provided. The sampling area 51 of the temperature measuring device 50 is controlled to be aligned with the preset area 21 of the wafer 20 to collect the optical signal of the sampling area 51, and the sampling temperature of the light spot 12 is determined as the first temperature based on the optical signal. Thus, the controller 40 can adjust the energy of the laser beam 11 based on the temperature information of the light spot 12 and the first temperature. Since the first temperature and the temperature information of the light spot 12 are temperature information measured based on different characteristics of the light spot 12, if the result measured by one temperature measuring method is inaccurate, the result measured by another temperature measuring method can be used for auxiliary verification and monitoring to quickly find out if there is a problem with the temperature measurement result, ensuring that the problem can be detected immediately and avoiding further losses.

[0088] For details, please refer to Figure 5 When the sampling area 51 of the temperature measuring device 50 deviates from the preset area 21 of the wafer 20, the first temperature measured by the temperature measuring device 50 will have a large deviation from the actual temperature of the central area in the light spot 12. For example, referencing Figure 6If the sampling area 51 of the temperature measuring device 50 deviates from the preset area 21 of the wafer 20, the first temperature measured by the temperature measuring device 50 will be lower than the actual temperature of the central area of ​​the laser spot 12. This is because the laser spot 12 of the laser beam 11 follows a Gaussian distribution, with the highest temperature in the central area and lower temperatures in the edge areas. When the sampling area 51 of the temperature measuring device 50 deviates from the central area of ​​the laser spot 12, the light signal radiated into the temperature measuring device 50 from the sampling area 51 will attenuate, resulting in the first temperature measured by the temperature measuring device 50 actually being the temperature of the edge area of ​​the laser spot 12, which is lower than the actual temperature of the central area of ​​the laser spot 12.

[0089] The accuracy of the temperature information of the light spot 12 is not affected by whether the sampling area 51 of the temperature measuring device 50 deviates from the preset area 21 of the wafer 20. This prevents inconsistencies between the temperature information of the light spot 12 and the initial temperature, allowing for timely detection of inaccurate temperature readings from the temperature measuring device 50. This ensures immediate problem detection and prevents further losses. It also avoids the problem of excessively high surface temperatures on the wafer 20 due to the laser beam 11 energy increasing because the sampling area 51 of the temperature measuring device 50 deviates from the preset area 21. Timely detection of this problem effectively reduces its impact. For example, the energy of the laser beam 11 can be adjusted to prevent the same problem from occurring on the next wafer 20. Furthermore, the energy of the laser beam 11 can be directly adjusted for the current wafer 20 to ensure that the temperature of the light spot 12 remains within the appropriate temperature range.

[0090] refer to Figure 5 When the sampling area 51 of the temperature measuring device 50 deviates from the preset area 21 of the wafer 20, the gray value of the light spot 12 does not change, and there is a strong correlation between the gray value of the light spot 12 and the resistance value of the wafer 20. Similarly, there is a strong correlation between the resistance value of the wafer 20 and the laser annealing temperature. In this embodiment, the gray value of the light spot 12 is incorporated into the temperature control system of the laser 10 to monitor and assist in correcting the first temperature measured by the temperature measuring device 50. Specifically, by adjusting the energy of the laser beam 11 based on the temperature information of the light spot 12 and the first temperature, it is possible to avoid adjusting the energy of the laser beam 11 when the temperature measurement result of a single temperature measuring method is abnormal, thus preventing over-compensation of the laser energy. This improves the accuracy of the laser beam 11 energy adjustment and avoids the problem of the actual temperature of the wafer surface being too high due to over-compensation of the laser 10, thereby improving the annealing quality.

[0091] For example, the temperature information of the light spot 12 may include the sampling temperature of the light spot 12 as a second temperature; at this time, the controller 40 is configured to adjust the energy of the laser beam 11 based on the first temperature and / or the second temperature when the absolute difference between the second temperature and the first temperature is less than or equal to a preset threshold. If the absolute difference between the second temperature and the first temperature is less than or equal to the preset threshold, it means that the results measured by different temperature measurement methods are not significantly different or are equal, indicating that the temperature measurement results of the two different temperature measurement methods are correct, and the energy of the laser beam 11 can be adjusted based on any one or two of them to improve the annealing quality.

[0092] For example, adjusting the energy of the laser beam 11 based on a first temperature and / or a second temperature may include adjusting the energy of the laser beam 11 based on the first temperature, the second temperature, or the average of the first temperature and the second temperature.

[0093] For example, adjusting the energy of the laser beam 11 based on a first temperature and / or a second temperature may include: adjusting the energy of the laser beam 11 based on the first temperature. Temperature measured based on optical signals is often more accurate and sensitive, so the energy of the laser beam 11 can be adjusted based on the first temperature measured by the optical signal to improve the annealing quality.

[0094] For example, adjusting the energy of the laser beam 11 based on a first temperature and / or a second temperature may include adjusting the energy of the laser beam 11 based on the average value of the first temperature and the second temperature. By adjusting the energy of the laser beam 11 based on the average value of the first temperature and the second temperature, the error between the results measured by different testing methods and the actual temperature can be reduced, thereby enabling the energy of the laser beam 11 to be adjusted based on a more accurate temperature value to improve the annealing quality.

[0095] Of course, in other embodiments, adjusting the energy of the laser beam 11 based on the first temperature and / or the second temperature may include adjusting the energy of the laser beam 11 based on the second temperature. Since the grayscale temperature measurement method is not affected by whether the light spot 12 deviates from the preset area 21, a more accurate sampling temperature can be measured, thereby adjusting the energy of the laser beam 11 based on a more accurate temperature value to improve the annealing quality.

[0096] For example, refer to Figure 4The controller 40 is configured to issue an alarm message or adjust the energy of the laser beam 11 based on the second temperature when the absolute difference between the second temperature and the first temperature exceeds a preset threshold. If the absolute difference between the second temperature and the first temperature exceeds the preset threshold, it indicates a significant difference in the results obtained by different temperature measurement methods, suggesting a problem with at least one of the measurement methods. In this case, an alarm message can be issued promptly to remind personnel to conduct an inspection. For example, simultaneously issuing the alarm message can control the laser 10 to stop working or the currently polished wafer 20 to stop working after scanning and annealing, preventing further product impact. The type of alarm message can include a pop-up display, an alarm sound, or an alarm light.

[0097] For example, controller 40 can also be configured as follows:

[0098] After issuing the alarm message, obtain the resistance value of wafer 20;

[0099] Based on the resistance value and the correspondence between resistance value and temperature, the actual annealing temperature is obtained, and based on the actual annealing temperature and the first temperature, the state of the temperature measuring device 50 is determined.

[0100] Based on the correspondence between the actual annealing temperature and the gray value-temperature, the actual gray value is obtained, and the state of the camera device 31 is determined based on the actual gray value and the gray value calculated by the spot analysis system 32.

[0101] The above embodiments have the following beneficial effects: When the absolute value of the difference between the first temperature and the second temperature is greater than a preset threshold, it indicates that at least one of the temperature measurement methods has a problem. In this case, at least one of the temperature measuring device 50 and the camera device 31 may be malfunctioning. Specifically, the temperature measuring device 50 may be malfunctioning, the camera device 31 may be malfunctioning, or both the temperature measuring device 50 and the camera device 31 may be malfunctioning. Manual intervention can be performed to analyze the problem and pinpoint its location.

[0102] Specifically, the following methods can be used:

[0103] The resistance-temperature correspondence and the grayscale-temperature correspondence can be obtained in advance. Then, based on the obtained grayscale-temperature correspondence and resistance-temperature correspondence, the grayscale-resistance correspondence can be indirectly obtained.

[0104] Specifically, the grayscale value-temperature correspondence can be obtained through temperature experiments. (Reference) Figure 2 This allows us to obtain the grayscale values ​​of light spot 12 at multiple temperature values, and then fit the obtained experimental data to obtain the grayscale value-temperature correspondence. (Reference) Figure 2The grayscale value-temperature correspondence can be represented as y = 1.1068x - 981.14, with a coefficient of determination R. 2 = 0.9984. In this formula, the dependent variable y represents the grayscale value of the image of spot 12, the independent variable x represents the temperature, and the coefficient of determination R... 2 A value greater than 0.99 indicates that the difference between the observed values ​​and the model values ​​is very small, and the fit is very high.

[0105] The specific relationship between resistance value and temperature can also be obtained through temperature experiments. (Reference) Figure 2 The relationship between resistance and temperature can be expressed as y = -0.3378x + 469.52, with a coefficient of determination R. 2 = 0.9997. In this formula, the dependent variable y represents the resistance value of the wafer after 20mm annealing, the independent variable x represents the temperature, and the coefficient of determination R... 2 A value greater than 0.99 indicates that the difference between the observed values ​​and the model values ​​is very small, and the fit is very high.

[0106] Next, an undoped or otherwise unprocessed wafer 20 (hereinafter also referred to as a control wafer) is provided, and the same ion implantation is performed on the control wafer. Then, the above-mentioned laser annealing system is used for annealing. After annealing is completed, the resistance value of the wafer 20 is measured.

[0107] Next, based on the resistance value and the resistance-temperature correspondence, the actual annealing temperature is obtained. Then, based on the actual annealing temperature and the first temperature, the state of the temperature measuring device 50 is determined to determine if there is a problem with the temperature measuring device 50. The specific method is as follows: Based on the measured resistance value and the previously tested resistance-temperature correspondence, the actual annealing temperature for annealing the wafer is deduced. The actual annealing temperature is compared with the first temperature measured by the temperature measuring device 50 during the annealing process. If the first temperature is close to the actual annealing temperature, the temperature measuring device 50 is functioning correctly; if the first temperature differs significantly from the actual annealing temperature—for example, the difference may exceed a first preset threshold—the temperature measuring device 50 is faulty.

[0108] Then, based on the actual annealing temperature and the grayscale value-temperature correspondence, the actual grayscale value is obtained. Based on the actual grayscale value and the grayscale value calculated by the spot analysis system 32, the state of the camera device 31 is determined to determine if there is a problem with the camera device 31. The specific method is as follows: Based on the previously tested resistance-temperature correspondence and grayscale value-temperature correspondence, the grayscale value-resistance correspondence is obtained. Based on the measured resistance value and the grayscale value-resistance correspondence, the actual grayscale value of the spot 12 during the annealing of the wafer is deduced. Then, the actual grayscale value is compared with the grayscale value calculated by the spot analysis system 32. If the actual grayscale value is close to the grayscale value calculated by the spot analysis system 32, it indicates that the camera device 31 is working properly. If the actual grayscale value differs significantly from the grayscale value calculated by the spot analysis system 32, for example, if the difference is greater than a second preset threshold, it indicates that there is a problem with the camera device 31.

[0109] This application has been described through the above embodiments. However, it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit this application to the scope of the described embodiments. Furthermore, those skilled in the art will understand that this application is not limited to the above embodiments, and many more variations and modifications can be made based on the teachings of this application, all of which fall within the scope of protection claimed in this application. The scope of protection of this application is defined by the appended claims and their equivalents.

Claims

1. A laser anneal system, comprising: include: A laser for generating a laser beam and focusing the laser beam onto a predetermined area of ​​a wafer to form a spot on the surface of the wafer; A camera device is used to capture images of the light spot; A spot analysis system communicatively connected to the camera device, the spot analysis system being used to analyze the image of the spot to obtain the temperature information of the spot; A controller, which is communicatively connected to both the laser and the spot analysis system, is configured to adjust the energy of the laser beam based on the temperature information of the spot.

2. The laser annealing system as described in claim 1, characterized in that, The spot analysis system is used to calculate the gray value of the spot and obtain the temperature information of the spot based on the gray value.

3. The laser annealing system as described in claim 2, characterized in that, The light spot analysis system is used to: obtain the temperature information of the light spot based on the gray value of the light spot and the gray value-temperature correspondence; The grayscale value-temperature correspondence was obtained through prior testing.

4. The laser annealing system as described in claim 3, characterized in that, The spot analysis system is used to: determine the target grayscale value range based on the target temperature value, the preset error range, and the grayscale value-temperature correspondence.

5. The laser annealing system as described in claim 4, characterized in that, When the grayscale value of the light spot is within the target grayscale value range, the temperature information of the light spot is determined to be normal; and / or, When the gray value of the light spot is outside the target gray value range, the temperature information of the light spot is determined to be an abnormal light spot temperature.

6. The laser annealing system as described in claim 5, characterized in that, The controller is configured to adjust the energy of the laser beam when the temperature information of the light spot indicates that the light spot temperature is abnormal, so that the gray value of the light spot is within the target gray value range.

7. The laser annealing system as described in claim 4, characterized in that, The target temperature value is determined based on the target resistance value and the resistance-temperature correspondence; The resistance value-temperature relationship was obtained through prior testing.

8. The laser annealing system according to any one of claims 1 to 7, characterized in that, Also includes: A temperature measuring device is used to align a sampling area with a preset area on the surface of the wafer to collect the light signal of the sampling area and determine the sampling temperature of the light spot as a first temperature based on the light signal. Furthermore, the controller is also used to adjust the energy of the laser beam based on the first temperature.

9. The laser annealing system as described in claim 8, characterized in that, The temperature information of the light spot includes: the temperature obtained by analyzing the image of the light spot is a second temperature; The controller is configured to: When the absolute difference between the second temperature and the first temperature is less than or equal to a preset threshold, the energy of the laser beam is adjusted based on the first temperature, the second temperature, or the average of the first temperature and the second temperature; and / or, An alarm is issued when the absolute difference between the second temperature and the first temperature is greater than a preset threshold.

10. The laser annealing system as described in claim 9, characterized in that, The controller is also configured to: After issuing the alarm message, the resistance value of the wafer is obtained; Based on the resistance value and the resistance value-temperature correspondence, the actual annealing temperature is obtained, and based on the actual annealing temperature and the first temperature, the state of the temperature measuring device is determined. Based on the actual annealing temperature and the correspondence between grayscale value and temperature, the actual grayscale value is obtained. The value is calculated based on the actual gray value and the gray value obtained by the spot analysis system. Determine the status of the camera device.

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