Processing method of large-size cadmium zinc telluride

Abstract

The invention relates to the field of tellurium-zinc-cadmium processing, and discloses a large-size tellurium-zinc-cadmium processing method which comprises the following steps: cutting a tellurium-zinc-cadmium single crystal ingot into wafers by using a linear cutting technology; screening available areas and dividing the available areas into square sheets with target sizes; the tellurium-zinc-cadmium wafer is slowly heated to 500 DEG C at the heating rate of 50 DEG C / h, and the main purpose is to increase the adhesive force between the pyrolytic boron nitride coating and the tellurium-zinc-cadmium; spraying a pyrolytic boron nitride coating with the thickness of 0.15-0.2 mm on the A surface of the tellurium-zinc-cadmium substrate; and after spraying is finished, the temperature is slowly reduced to 20 DEG C at the cooling rate of 30 DEG C / h, and cracking or pyrolytic boron nitride coating falling caused by sudden drop is prevented. According to the method, the temperature is slowly increased to 500 DEG C, the adhesive force between the pyrolytic boron nitride coating and the tellurium-zinc-cadmium is enhanced, the stability and durability of the coating are improved, the temperature increasing process is conducted in the vacuum environment, the oxidation reaction at the interface of the pyrolytic boron nitride coating and the tellurium-zinc-cadmium is reduced, and therefore the service life is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of cadmium zinc telluride processing, in particular to a large-size cadmium zinc telluride processing method. Background Art

[0002] Cadmium zinc telluride crystal is a new type of ternary compound semiconductor. Due to its excellent properties, such as high resistivity and large bandgap (which varies with the content of doped zinc), it is widely used in the fields of X-ray and gamma-ray detection, infrared detectors, medical imaging, etc. With the advancement of technology and the growth of market demand, the demand for large-size, high-performance cadmium zinc telluride wafers is increasing. Therefore, a large-size cadmium zinc telluride wafer processing method that can significantly improve the yield is particularly important.

[0003] In the prior art, the CdZnTe wafers are prone to edge collapse during processing, resulting in a low yield rate. This not only increases production costs, but also affects production efficiency. In addition, during the heating and cooling process, due to the influence of thermal stress, the CdZnTe wafers are prone to cracks or the pyrolytic boron nitride coating falls off, which further reduces the yield rate.

[0004] Although traditional processing methods can meet production needs to a certain extent, they still have many shortcomings, such as low yield rate, serious edge collapse, low processing efficiency, etc. These problems not only affect product quality, but also limit the improvement of production efficiency and the reduction of costs. Summary of the invention

[0005] The purpose of the present invention is to provide a large-size cadmium zinc telluride processing method to solve the problems of low yield, serious edge collapse and low processing efficiency.

[0006] In order to achieve the above-mentioned invention object, the present invention adopts the following technical scheme: a large-size cadmium zinc telluride processing method, comprising the following steps:

[0007] S1: Cutting the CdZnTe single crystal ingot into wafers using wire cutting technology;

[0008] S2: Screen the available area and divide it into target size squares;

[0009] S3: slowly heating the CdZnTe wafer to 500°C at a heating rate of 50°C / h, the main purpose of which is to increase the adhesion between the pyrolytic boron nitride coating and the CdZnTe;

[0010] S4: spraying a 0.15-0.2 mm thick pyrolytic boron nitride coating on the A surface of the CdZnTe substrate;

[0011] S5: After spraying, slowly cool down to 20℃ at a cooling rate of 30℃ / h to prevent sudden drop in temperature from causing cracks or shedding of the pyrolytic boron nitride coating;

[0012] S6: Use mechanical grinding to remove about 0.05 mm of the pyrolytic boron nitride coating to make the surface roughness PV ≤ 2 μm;

[0013] S7: grinding, rough polishing, fine polishing and chemical polishing are performed on the B surface in sequence;

[0014] S8: Finally, packaging.

[0015] Preferably, in step S3, the process of slowly heating the temperature to 500°C at a heating rate of 50°C / h further includes being performed in a vacuum environment to reduce oxidation reaction at the interface between the pyrolytic boron nitride coating and the cadmium zinc telluride.

[0016] Preferably, the pyrolytic boron nitride coating in step S4 is deposited by radio frequency magnetron sputtering technology, and the sputtering power is controlled between 1.5 kW and 2.5 kW to ensure uniformity and adhesion of the coating.

[0017] Preferably, during the RF magnetron sputtering process, high purity argon is used as the working gas, and its flow rate is maintained in the range of 50 sccm to 70 sccm to optimize the quality of the pyrolytic boron nitride coating.

[0018] Preferably, the mechanical grinding process involved in step S6 uses a precision CNC surface grinder, and the grinding pressure is controlled between 5N and 10N to avoid damage to the cadmium zinc telluride wafer.

[0019] Preferably, the precision CNC surface grinder is equipped with an online detection system to monitor the quality of the grinding surface in real time to ensure that the surface roughness PV value reaches the requirement of ≤2μm.

[0020] Preferably, the chemical polishing treatment in step S7 uses an alkaline polishing solution, which consists of sodium hydroxide, silicate and surfactant, and the pH value is adjusted to 10.5 to 11.5 to improve the polishing efficiency and selectivity.

[0021] Preferably, before chemical polishing, step S7 further includes a pretreatment process, that is, using an ultrasonic cleaner to clean the B surface in an ethanol medium to remove organic pollutants and particulate matter on the surface and improve the effect of chemical polishing.

[0022] Compared with the prior art, a large-size cadmium zinc telluride processing method using the above technical solution has the following beneficial effects:

[0023] 1. By slowly heating up to 500°C, the adhesion between the pyrolytic boron nitride coating and the cadmium zinc telluride is enhanced, and the stability and durability of the coating are improved. The heating process is carried out in a vacuum environment, which helps to reduce the oxidation reaction at the interface between the pyrolytic boron nitride coating and the cadmium zinc telluride, thereby maintaining the performance of the material and extending its service life. The pyrolytic boron nitride coating is deposited using radio frequency magnetron sputtering technology, and a uniform coating with good adhesion can be obtained by precisely controlling the sputtering power and working gas flow. By optimizing the processing steps and parameter control, the processing yield is increased from 83% to 96.6%, significantly improving production efficiency and product quality;

[0024] 2. Use precision CNC surface grinders during mechanical grinding and strictly control the grinding pressure to avoid damage to fragile CdZnTe wafers. The use of online detection systems can monitor the quality of the ground surface in real time to ensure that the required surface roughness requirements are met, which helps to improve product consistency and reliability. Chemical polishing uses an alkaline polishing liquid with a specific composition to improve polishing efficiency and selectivity, removing only the materials that need to be removed without damaging the underlying materials. Before chemical polishing, use an ultrasonic cleaner to clean the B surface in an ethanol medium, which can effectively remove organic pollutants and particulate matter on the surface, providing a better foundation for chemical polishing;

[0025] 3. Precise control of the entire processing process, including temperature, pressure, chemical composition, etc., helps to optimize the surface quality of CdZnTe wafers and improve their performance and reliability. Through these fine processing steps, defects in the material, such as cracks and holes, can be reduced, thereby improving the mechanical strength and electrical properties of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a step diagram of the large-size cadmium zinc telluride processing method of the embodiment. DETAILED DESCRIPTION

[0027] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0028] like Figure 1 As shown, a large-size cadmium zinc telluride processing method includes the following steps:

[0029] S1: Cutting the CdZnTe single crystal ingot into wafers using wire cutting technology;

[0030] S2: Screen the available area and divide it into target size squares;

[0031] S3: slowly heating the CdZnTe wafer to 500°C at a heating rate of 50°C / h, the main purpose of which is to increase the adhesion between the pyrolytic boron nitride coating and the CdZnTe;

[0032] S4: spraying a 0.15-0.2 mm thick pyrolytic boron nitride coating on the A surface of the CdZnTe substrate;

[0033] S5: After spraying, slowly cool down to 20℃ at a cooling rate of 30℃ / h to prevent sudden drop in temperature from causing cracks or shedding of the pyrolytic boron nitride coating;

[0034] S6: Use mechanical grinding to remove about 0.05 mm of the pyrolytic boron nitride coating to make the surface roughness PV ≤ 2 μm;

[0035] S7: grinding, rough polishing, fine polishing and chemical polishing are performed on the B surface in sequence;

[0036] S8: Finally, packaging.

[0037] Wherein in step S3, the process of slowly heating the temperature to 500°C at a heating rate of 50°C / h further includes being performed in a vacuum environment to reduce an oxidation reaction at the interface between the pyrolytic boron nitride coating and the cadmium zinc telluride;

[0038] The pyrolytic boron nitride coating in step S4 is deposited by radio frequency magnetron sputtering technology, and the sputtering power is controlled between 1.5 kW and 2.5 kW to ensure uniformity and adhesion of the coating;

[0039] During the RF magnetron sputtering process, high-purity argon is used as the working gas, and its flow rate is maintained in the range of 50 sccm to 70 sccm to optimize the quality of the pyrolytic boron nitride coating;

[0040] The mechanical grinding process involved in step S6 uses a precision CNC surface grinder, and the grinding pressure is controlled between 5N and 10N to avoid damage to the CdZnTe wafer;

[0041] The precision CNC surface grinder is equipped with an online detection system to monitor the quality of the grinding surface in real time to ensure that the surface roughness PV value reaches the requirement of ≤2μm;

[0042] The chemical polishing treatment in step S7 uses an alkaline polishing solution, which is composed of sodium hydroxide, silicate and surfactant, and the pH value is adjusted to 10.5 to 11.5 to improve polishing efficiency and selectivity;

[0043] Before chemical polishing, step S7 also includes a pretreatment process, that is, using an ultrasonic cleaner to clean the B surface in an ethanol medium to remove organic pollutants and particles on the surface and improve the effect of chemical polishing.

[0044] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A large-size cadmium zinc telluride processing method, characterized in that: The following steps are involved: S1: Cutting the CdZnTe single crystal ingot into wafers using wire cutting technology; S2: Screen the available area and divide it into target size squares; S3: slowly heating the CdZnTe wafer to 500°C at a heating rate of 50°C / h, the main purpose of which is to increase the adhesion between the pyrolytic boron nitride coating and the CdZnTe; S4: spraying a 0.15-0.2 mm thick pyrolytic boron nitride coating on the A surface of the CdZnTe substrate; S5: After spraying, slowly cool down to 20℃ at a cooling rate of 30℃ / h to prevent sudden drop in temperature from causing cracks or shedding of the pyrolytic boron nitride coating; S6: Use mechanical grinding to remove about 0.05 mm of the pyrolytic boron nitride coating to make the surface roughness PV ≤ 2 μm; S7: grinding, rough polishing, fine polishing and chemical polishing are performed on the B surface in sequence; S8: Finally, packaging.

2. A large-size CdZnTe processing method according to claim 1, characterized in that: Wherein in step S3, the process of slowly heating the temperature to 500°C at a heating rate of 50°C / h is further performed in a vacuum environment to reduce the oxidation reaction at the interface between the pyrolytic boron nitride coating and the cadmium zinc telluride.

3. The large-size CdZnTe processing method according to claim 1, characterized in that: The pyrolytic boron nitride coating in step S4 is deposited by radio frequency magnetron sputtering technology, and the sputtering power is controlled between 1.5 kW and 2.5 kW to ensure the uniformity and adhesion of the coating.

4. The large-size CdZnTe processing method according to claim 3, characterized in that: During the RF magnetron sputtering process, high-purity argon is used as the working gas, and its flow rate is maintained in the range of 50 sccm to 70 sccm to optimize the quality of the pyrolytic boron nitride coating.

5. The large-size CdZnTe processing method according to claim 1, characterized in that: The mechanical grinding process involved in step S6 uses a precision CNC surface grinder, and the grinding pressure is controlled between 5N and 10N to avoid damage to the CdZnTe wafer.

6. The large-size CdZnTe processing method according to claim 1, characterized in that: The precision CNC surface grinder is equipped with an online detection system to monitor the quality of the grinding surface in real time to ensure that the surface roughness PV value meets the requirement of ≤2μm.

7. The large-size CdZnTe processing method according to claim 1, characterized in that: The chemical polishing treatment in step S7 uses an alkaline polishing solution, which is composed of sodium hydroxide, silicate and surfactant, and the pH value is adjusted to 10.5 to 11.5 to improve the polishing efficiency and selectivity.

8. The large-size CdZnTe processing method according to claim 1, characterized in that: Before chemical polishing, step S7 also includes a pretreatment process, that is, using an ultrasonic cleaner to clean the B surface in an ethanol medium to remove organic pollutants and particles on the surface and improve the effect of chemical polishing.

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