Method for inhibiting boat shaking stripes of liquid phase epitaxy tellurium-cadmium-mercury material

Abstract

The invention discloses a method for inhibiting boat shaking stripes of a liquid phase epitaxy tellurium-cadmium-mercury material, and relates to a semiconductor film preparation and liquid phase epitaxy technology, and the method comprises the following steps: arranging a sensor with required precision on a pull rod of a graphite boat in advance; before a graphite boat and a pull rod are put into liquid phase epitaxy for use, pre-detection is carried out, tension data of the pull rod and the graphite boat are recorded, and the pre-detection comprises the steps that after the liquid phase epitaxy equipment is heated to the working temperature, a pull rod motor is started to pull the graphite boat through the pull rod at a preset low speed; the sensor is used for recording the tension change in the boat pulling process so as to construct a tension curve; and according to the obtained tension curve, based on a static resistance reference criterion and a dynamic resistance reference criterion, judging the boat-shaking stripe risk so as to determine whether the boat-shaking stripe risk exists or not. According to the method, the material quality problems such as growth stripes of the tellurium-cadmium-mercury thin film material caused by boat shaking can be effectively avoided, and the qualified rate of products is increased.

Description

Technical Field

[0001] This application relates to the fields of semiconductor thin film preparation and liquid phase epitaxy, and in particular to a method for suppressing striations in liquid phase epitaxial mercury cadmium telluride materials. Background Technology

[0002] Mercury cadmium telluride (MDT) is an important infrared photosensitive material and plays an indispensable role in the infrared field. Its unique feature lies in its ability to flexibly control the bandgap by changing the cadmium composition, thereby covering the entire infrared band. There are various methods for growing MDT, mainly including molecular beam epitaxy (MBE), metal-organic vapor phase epitaxy (MOVPE), and liquid phase epitaxy (LPE).

[0003] Among these methods, liquid phase epitaxy (LPE) was the first technology to be successfully used to prepare mercury cadmium telluride epitaxial materials. Moreover, the mercury cadmium telluride materials prepared by LPE have shown significant advantages in key aspects such as photoresponse performance, preparation cost, and growth of doped materials. It is currently the main technology for preparing mercury cadmium telluride materials for infrared focal plane detectors, and its maturity strongly supports the industrial production process of mercury cadmium telluride epitaxy.

[0004] Horizontal liquid phase epitaxy (LPE) is a type of liquid phase epitaxy. In LPE growth systems, the graphite boat is a commonly used key component, typically consisting of a base, a slider, a mother liquor tank, and a top cover. When the mercury cadmium telluride (HCdT) film reaches the predetermined thickness, the slider moves under high temperature to separate the growth film from the mother liquor. However, this process is susceptible to vibration due to various factors.

[0005] On the one hand, the movement of the slider is achieved by a motor-driven rod that moves the slider. However, the motor may become unstable during operation due to improper parameter settings or aging and wear caused by prolonged use, leading to system vibration and affecting the smoothness of the slider's movement. On the other hand, the graphite boat itself also has factors that can easily cause vibration due to dimensional tolerances and the matching of various components. In addition, the thermal expansion characteristics of graphite are also a key influencing factor. Under high-temperature environments, graphite undergoes thermal expansion, which can potentially cause subtle changes in the internal structure of the graphite boat, making the original spatial dimensions no longer suitable and increasing the resistance when pulling the slider. More seriously, this change in resistance can sometimes cause the slider to jam. Under the continuous traction of the rod, jamming further disrupts the continuity of the slider's movement, causing obvious vibration and ultimately leading to material quality problems such as growth streaks. Summary of the Invention

[0006] This application provides a method for suppressing boat-shaking streaks in liquid-phase epitaxial mercury cadmium telluride materials. Before the graphite boat and pull rod are put into liquid-phase epitaxy, the system is pre-tested, the tension data of the pull rod and graphite boat are recorded, and the graphite boat is determined to be in a normal or abnormal boat-shaking state according to the judgment logic.

[0007] This application provides a method for suppressing boat-shaped streaks in liquid-phase epitaxial mercury cadmium telluride materials, including: A sensor of the required accuracy is pre-installed on the pull rod of the graphite boat to measure the pulling force during the process of pulling the boat based on the sensor; Before the graphite boat and tie rod are used in liquid phase epitaxy, a pre-test is performed, and the tension data of the tie rod and graphite boat are recorded. The pre-test includes: After heating the liquid phase epitaxy equipment to the operating temperature, start the lever motor to pull the graphite boat through the lever at a preset low speed; The sensor is used to record the changes in tension during the boat-pulling process in order to construct a tension curve; Based on the obtained tension curve, the risk of boat jitter stripes is judged according to the static resistance benchmark criterion and the dynamic resistance benchmark criterion to determine whether the risk of boat jitter stripes exists. The static resistance benchmark criterion is used to compare the initial static resistance data of the collected graphite boat slider in a stationary state with the set initial static resistance benchmark threshold. The dynamic resistance benchmark criterion is used to monitor friction fluctuations based on the tension curve.

[0008] Optionally, the measurement resolution of the sensor is ≤0.1N.

[0009] Optionally, the graphite boat is pulled by the lever at a preset low speed, wherein the preset low speed is 2 mm / s or less.

[0010] Optionally, the specific process of making a judgment based on the static resistance benchmark criterion includes: Heat the liquid phase epitaxy equipment to the preset operating temperature and hold it at that temperature for a specified time; Under the condition that the equipment temperature is stable at the target temperature ±2℃, the initial static resistance of the graphite boat slider when it is stationary is collected by the sensor installed at the connection between the graphite boat and the tie rod. The initial static resistance benchmark threshold is set to ≤2N; If the detected initial static resistance is greater than 2N, it is directly determined to be an abnormality in the graphite boat matching.

[0011] Optionally, after determining that the graphite boat is mismatched, the following steps are also taken: using a three-dimensional measuring instrument with the required accuracy to detect the flatness of the contact surface of the graphite boat slide and the base and the assembly gap, and grinding them until the flatness deviation is ≤0.05mm and the initial static resistance is ≤2N, and then a dynamic pulling test is performed.

[0012] Optionally, the specific process of making a judgment based on the dynamic resistance benchmark criterion includes: After the static resistance criterion test is completed and passed, the pull rod motor is started to pull the graphite boat at a preset low speed. Record the required tension data for the specified duration, and perform the following judgment based on the recorded tension data: If the tensile force fluctuation range is ≤1N over the corresponding time period, it is considered to be risk-free. If the tensile force fluctuation range is 1N-3N over the corresponding time period, it is judged as low risk; If the tensile force fluctuation range is >3N over the corresponding time period, it is judged as high risk.

[0013] Optionally, if the risk is deemed low, the following may also be included: adjusting the parameters of the pull rod motor, reducing the motor starting speed by 10%-15% and the output torque by 8%-10% to reduce the pulling impact force.

[0014] Optionally, in cases deemed high-risk, this may also include adjusting motor parameters or modifying the graphite boat structure to reduce the abrupt change in friction.

[0015] This application embodiment introduces a high-precision tension sensor at the connection between the graphite boat and the tie rod. Before the graphite boat and tie rod are officially put into use in liquid phase epitaxy, the system is pre-tested, the tension data of the tie rod and graphite boat are recorded, and the judgment logic determines whether the graphite boat is in a normal or abnormal pulling condition.

[0016] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a schematic diagram of the graphite boat structure in the embodiments of this application; Figure 2 This is a schematic diagram of the installation of the tension sensor in an embodiment of this application; Figure 3 This is a schematic diagram of the graphite boat-pull rod connection state in the embodiments of this application; Figure 4 This is a schematic diagram of the tension curve under normal boat-pulling conditions in the embodiments of this application; Figure 5 This is a schematic diagram of the tension curve under abnormal boat-pulling conditions in an embodiment of this application. Detailed Implementation

[0018] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0019] Surface morphology is a crucial indicator of epitaxial material quality. Boat-like striations in liquid-phase epitaxial mercury cadmium telluride (HCdT) materials severely impact material quality and yield. Currently, there are no methods or solutions for pre-emptive detection of boat-like striations in horizontal liquid-phase epitaxy; often, investigation is only conducted post-incidentally after a large number of defective products have been produced. This delayed approach significantly affects production efficiency and product yield.

[0020] This application provides a method for suppressing boat-shaking streaks in liquid-phase epitaxial mercury cadmium telluride (HCDM) materials. This application pre-installs a sensor of required precision on the pull rod of the graphite boat to measure the pulling force during the boat-pulling process based on the sensor. For example... Figure 1-3 As shown, the equipment preparation work involves selecting a suitable graphite boat 1 and a pull rod, and installing a high-precision, high-temperature resistant tension sensor 3 between the front pull rod 201 and the rear pull rod 202. The rear pull rod 202 is connected to the pull rod motor, and the front pull rod 201 is connected to the slide bar 101 of the graphite boat 1. The graphite boat 1 includes a mother liquor tank 102, a top cover 103, and a graphite base 104. Careful inspection is performed to ensure reliable connections, while also ensuring the sensor is in normal working condition so that it can accurately collect tension data. In some embodiments, the measurement resolution of the sensor is ≤0.1N.

[0021] The method of this application includes the following steps: Before the graphite boat and tie rod are used in liquid phase epitaxy, a pre-test is performed, and the tension data of the tie rod and graphite boat are recorded. The pre-test includes: After the liquid phase epitaxy equipment is heated to the operating temperature, the pull rod motor is started to pull the graphite boat through the pull rod at a preset low speed. In some embodiments, the graphite boat is pulled through the pull rod at a preset low speed, wherein the preset low speed is 2 mm / s or less.

[0022] The sensor is used to record the changes in tension during the boat-pulling process in order to construct a tension curve.

[0023] In a specific example, the pre-detection involves heating the liquid phase epitaxy equipment to the operating temperature, then starting the pull rod motor to pull the graphite boat at a preset low speed (e.g., 2 mm / s), at which point the tension sensor simultaneously begins recording the tension data.

[0024] like Figure 4 As shown, the normal boat-pulling situation is from rest to uniform speed pulling. When the sliding structure is pulled from rest, the pulling force curve will initially rise. This is because static friction must be overcome at this point, which is usually greater than sliding friction. After the object begins to slide, the pulling force will drop to a stable value, which corresponds to the sliding friction. Subsequently, as the boat continues to pull at a uniform speed, the curve remains relatively horizontal, and the pulling force sensor output signal stabilizes.

[0025] like Figure 5 As shown, the abnormal boat-pulling situation occurs when the roughness of the contact surface changes during sliding, such as transitioning from a smooth surface to a rough surface. Due to increased friction, the tension curve will rise sharply. If the sliding structure is subjected to other external disturbances, such as vibration changes, the tension curve will fluctuate.

[0026] Based on the obtained tension curve, the risk of boat jitter stripes is judged according to the static resistance benchmark criterion and the dynamic resistance benchmark criterion to determine whether the risk of boat jitter stripes exists. The static resistance benchmark criterion is used to compare the initial static resistance data of the collected graphite boat slider in a stationary state with the set initial static resistance benchmark threshold. The dynamic resistance benchmark criterion is used to monitor friction fluctuations based on the tension curve.

[0027] The determination logic in this application's embodiments is mainly divided into static resistance benchmark criteria and dynamic resistance benchmark criteria. The static resistance benchmark criteria are used to investigate jamming problems in the graphite boat caused by high-temperature deformation or abnormal component matching before dynamic pulling tests, thus mitigating the risk of boat shaking at the source. In some embodiments of this application, the specific process of making a judgment based on the static resistance benchmark criteria includes: The liquid phase epitaxy equipment is heated to a preset operating temperature and held at that temperature for a specified time, such as 500°C and held for 30 minutes.

[0028] With the equipment temperature stable at ±2℃ of the target temperature, the initial static resistance of the graphite boat slider when it is stationary is collected by a sensor (measurement resolution ≤0.1N) installed at the connection between the graphite boat and the tie rod.

[0029] The initial static resistance benchmark threshold is set to ≤2N; If the detected initial static resistance is greater than 2N, it is directly determined to be an abnormality in the graphite boat matching, which means there is a risk of the boat getting stuck and shaking when starting to pull.

[0030] In some embodiments of this application, after determining that the graphite boat is mismatched, the method further includes: using a three-dimensional measuring instrument with the required accuracy (measurement accuracy ≤ 0.01 mm) to detect the flatness of the contact surface and the assembly gap of the graphite boat slide and the base, and grinding and processing until the flatness deviation is ≤ 0.05 mm and the initial static resistance is retested to ≤ 2 N, and then a dynamic pull test is performed. If the detected initial static resistance is ≤ 2 N, it is determined that "the initial structure of the graphite boat is qualified" and meets the conditions for entering the dynamic pull test.

[0031] The dynamic resistance criterion is used to monitor friction fluctuations during dynamic pulling by analyzing the characteristics of the pulling curve, thereby reducing the risk of boat shaking caused by external disturbances. In some embodiments of this application, the specific process of making a judgment based on the dynamic resistance criterion includes: After the static resistance criterion test is completed and passed, the pull rod motor is started to pull the graphite boat at a preset low speed. Record the required tension data for the specified duration, and perform the following judgment based on the recorded tension data: If the tensile force fluctuation is ≤1N over the corresponding time period, it is considered risk-free and no adjustment is required.

[0032] If the tensile force fluctuation range is 1N-3N over the corresponding time period, it is judged as low risk; If the tensile force fluctuation is greater than 3N within the corresponding time period, it is considered high risk. In some cases, the required time period may be, for example, 10 seconds, which can be achieved by using a tensile sensor to sample tensile force data for 10 seconds at a sampling frequency of 100 Hz.

[0033] In some embodiments of this application, when the risk is determined to be low, the method further includes: adjusting the parameters of the pull rod motor, reducing the motor starting speed by 10%-15% and the output torque by 8%-10% to reduce the pulling impact force, and then re-performing the dynamic resistance test until it meets the risk-free determination criteria.

[0034] In some embodiments of this application, when the risk is deemed high, the method further includes: adjusting motor parameters or modifying the graphite boat structure to reduce the abrupt change in friction.

[0035] This application also provides implementation examples of a method for suppressing boat-shaped streaks in liquid-phase epitaxial mercury cadmium telluride materials, including: (1) Equipment preparation. Select a suitable graphite boat 1 and tie rod, and install the high-precision high-temperature resistant tension sensor 3 between the front tie rod 201 and the rear tie rod 202. The rear tie rod is connected to the tie rod motor. Carefully check and ensure that the connection is reliable, and at the same time ensure that the sensor is in normal working condition so that it can accurately collect tension data.

[0036] (2) Execution of Static Resistance Criterion and Graphite Boat Adjustment. The assembled graphite boat, tie rod, and sensor were installed into the reaction chamber of the liquid phase epitaxy equipment. After closing the chamber, the heating system was started, and the temperature was raised to the preset working temperature (500℃ in this case) according to the requirements of the mercury cadmium telluride epitaxial growth process. After reaching 500℃, the temperature was maintained for 30 minutes, and the temperature uniformity deviation was confirmed to be ≤±2℃ through the equipment temperature control system. The tension sensor data acquisition system was started to collect the initial static resistance data of the graphite boat slider 101 in a stationary state. The acquisition time was 10 seconds, and the average value of the data within 10 seconds was taken as the final static resistance value. The initial test result in this case was 2.6N, which exceeded the threshold of "≤2N", and was judged as "graphite boat mismatch". Therefore, the graphite boat needs to be repaired and retested. The graphite boat was removed, and a high-precision three-dimensional measuring instrument was used to check the flatness of the contact surface between the slider 101 and the graphite base 104, as well as the assembly gap. The inspection revealed localized protrusions on the lower surface of the slider, with a large flatness value. The protruding parts of the slider were ground, and the three-dimensional measuring instrument was used to retest during the grinding process until the flatness deviation of the slider contact surface was ≤0.05mm. The repaired graphite boat was reinstalled into the equipment, and the heating (500℃), heat preservation (30 minutes), and static resistance testing steps were repeated. The retested static resistance value was 1.8N, meeting the benchmark threshold of "≤2N," and the graphite boat was deemed to have "passed the initial structure test," allowing it to proceed to the subsequent dynamic pulling test.

[0037] (3) Execution and parameter adjustment of dynamic resistance benchmark. Based on the qualified static test results, the pull rod motor was started and driven to pull the graphite boat according to the preset parameters (pulling speed 2 mm / s, consistent with the sliding speed of the slide bar during the epitaxial growth of mercury cadmium telluride). At the same time, the tension sensor was started to collect tension data at a sampling frequency of 100 Hz for 10 seconds to form a complete dynamic tension curve. The initial dynamic test result in this case was: the tension fluctuation amplitude within 10 seconds was 2.2N, which was in the "1-3N" range and was judged as "low risk". The low risk adjustment measures were implemented: the output torque was reduced by 10% (from the original 5N·m to 4.5N·m) by adjusting the motor parameters to reduce the impact force on the slide bar at the moment of start-up; after adjustment, the dynamic pulling test was re-executed. At this time, the tension fluctuation amplitude within 10 seconds dropped to 0.8N, which met the risk-free judgment standard of "≤1N".

[0038] (4) Material growth. After completing and passing the static and dynamic resistance tests, the material was grown in liquid phase using conventional processes, and a high-quality semiconductor material epitaxial layer without boat stripes was finally obtained.

[0039] This application embodiment introduces a high-precision tension sensor at the connection between the graphite boat and the pull rod. Before the graphite boat and pull rod are officially put into liquid phase epitaxy, the system is pre-tested, and the tension data of the pull rod and graphite boat are recorded. A judgment logic is used to determine whether the graphite boat is in a normal or abnormal pulling condition. By pre-determining the risk of boat shaking, material quality problems such as growth streaks in mercury cadmium telluride thin films caused by boat shaking can be effectively avoided, improving the product yield.

[0040] It should be noted that, in the embodiments of this application, the terms "comprising," "including," or any other variations thereof are intended to cover 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 limitations, 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 that element.

[0041] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0042] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, 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 is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0043] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims. All of these forms are within the protection scope of this application.

Claims

1. A method for suppressing boat-shaped streaks in liquid-phase epitaxial mercury cadmium telluride materials, characterized in that, include: A sensor of the required accuracy is pre-installed on the pull rod of the graphite boat to measure the pulling force during the process of pulling the boat based on the sensor; Before the graphite boat and tie rod are used in liquid phase epitaxy, a pre-test is performed, and the tension data of the tie rod and graphite boat are recorded. The pre-test includes: After heating the liquid phase epitaxy equipment to the operating temperature, start the lever motor to pull the graphite boat through the lever at a preset low speed; The sensor is used to record the changes in tension during the boat-pulling process in order to construct a tension curve; Based on the obtained tension curve, the risk of boat jitter stripes is judged according to the static resistance benchmark criterion and the dynamic resistance benchmark criterion to determine whether the risk of boat jitter stripes exists. The static resistance benchmark criterion is used to compare the initial static resistance data of the collected graphite boat slider in a stationary state with the set initial static resistance benchmark threshold. The dynamic resistance benchmark criterion is used to monitor friction fluctuations based on the tension curve.

2. The method for suppressing boat-shaped streaks in liquid-phase epitaxial mercury cadmium telluride materials as described in claim 1, characterized in that, The sensor has a measurement resolution of ≤0.1N.

3. The method for suppressing boat-shaped streaks in liquid-phase epitaxial mercury cadmium telluride materials as described in claim 1, characterized in that, The graphite boat is pulled by the lever at a preset low speed, wherein the preset low speed is 2 mm / s or less.

4. The method for suppressing boat-shaped streaks in liquid-phase epitaxial mercury cadmium telluride materials as described in claim 1, characterized in that, The specific process for making a judgment based on the static resistance benchmark criterion includes: Heat the liquid phase epitaxy equipment to the preset operating temperature and hold it at that temperature for a specified time; Under the condition that the equipment temperature is stable at the target temperature ±2℃, the initial static resistance of the graphite boat slider when it is stationary is collected by the sensor installed at the connection between the graphite boat and the tie rod. The initial static resistance benchmark threshold is set to ≤2N; If the detected initial static resistance is greater than 2N, it is directly determined to be an abnormality in the graphite boat matching.

5. The method for suppressing boat-shaped streaks in liquid-phase epitaxial mercury cadmium telluride materials as described in claim 4, characterized in that, After determining the abnormality in the graphite boat matching, the following steps are also taken: using a three-dimensional measuring instrument with the required accuracy to detect the flatness of the contact surface of the graphite boat slide and the bottom support and the assembly gap, and grinding and processing until the flatness deviation is ≤0.05mm and the initial static resistance is ≤2N, and then a dynamic pulling test is carried out.

6. The method for suppressing boat-shaped streaks in liquid-phase epitaxial mercury cadmium telluride materials as described in claim 5, characterized in that, The specific process of making a judgment based on the dynamic resistance benchmark criterion includes: After the static resistance criterion test is completed and passed, the pull rod motor is started to pull the graphite boat at a preset low speed. Record the required tension data for the specified duration, and perform the following judgment based on the recorded tension data: If the tensile force fluctuation range is ≤1N over the corresponding time period, it is considered to be risk-free. If the tensile force fluctuation range is 1N-3N over the corresponding time period, it is judged as low risk; If the tensile force fluctuation range is >3N over the corresponding time period, it is judged as high risk.

7. The method for suppressing boat-shaped streaks in liquid-phase epitaxial mercury cadmium telluride materials as described in claim 6, characterized in that, In cases deemed low-risk, the following measures are also taken: adjusting the parameters of the pull rod motor, reducing the motor starting speed by 10%-15% and the output torque by 8%-10% to reduce the pulling impact.

8. The method for suppressing boat-shaped streaks in liquid-phase epitaxial mercury cadmium telluride materials as described in claim 6, characterized in that, In cases deemed high-risk, adjustments may be made to motor parameters or the graphite boat structure to reduce the magnitude of sudden changes in friction.

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