A preparation method of a CdZnTe one-dimensional linear array detector based on a thermal sacrifice method

Abstract

The application provides a preparation method of a tellurium-zinc-cadmium one-dimensional linear array detector based on a thermal sacrifice method, which is based on tellurium-zinc-cadmium material, and a tellurium-zinc-cadmium one-dimensional linear array detector capable of X-ray diffraction detection is designed and prepared by using the thermal sacrifice method. Van der Waals contact is constructed on the surface of the tellurium-zinc-cadmium, the optimization of the electric field distribution between the tellurium-zinc-cadmium one-dimensional linear array electrodes is realized, a new solution to the charge crosstalk problem is provided, and excellent detection performance is exhibited. After popularization in the future, the method is expected to provide a powerful detection means for three-dimensional phase analysis and stress analysis of bulk materials.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor radiation detection technology, specifically relating to a method for fabricating a one-dimensional linear array detector of zinc cadmium telluride based on the thermal sacrificial method. Background Technology

[0002] With the continuous development of modern industrial technology, the requirements for precise control and optimization of material properties are increasing, especially in fields such as aerospace, automobile manufacturing, and semiconductor industry, where the stress state of materials directly affects their safety, durability, and reliability. Traditional stress analysis methods, such as strain gauge methods and Hall effect methods, although widely used, often cannot meet the needs of high-precision and in-depth material analysis. X-ray diffraction (XRD) stress analysis, due to its non-destructive, non-contact nature and applicability to a variety of materials, is gradually becoming the mainstream technology in material stress analysis.

[0003] In particular, short-wavelength X-ray diffraction stress analysis, with its higher spatial resolution and penetration capability, can accurately measure the internal stress distribution of materials at the micrometer or even nanometer scale. This gives it a unique advantage in fields such as high-precision materials testing, microelectronic devices, thin film materials, and complex alloys. Compared to traditional long-wavelength X-rays, short-wavelength X-rays provide higher diffraction pattern clarity and effectively avoid errors caused by deep penetration or sample surface roughness, thus achieving high-precision analysis of residual stress within materials.

[0004] However, despite the immense potential of short-wavelength X-ray diffraction stress analyzers in scientific research and industrial applications, the high energy of short-wavelength X-rays results in strong penetration through materials but weak diffraction signals, necessitating highly sensitive detectors. However, the high deposition energy of short-wavelength X-rays can cause severe radiation damage to highly sensitive detection materials. This inherent contradiction between high sensitivity and a wide detection range significantly limits the research and development of related technologies. The industry urgently needs a high-precision short-wavelength X-ray diffraction stress analyzer applicable to a variety of complex material systems to promote its widespread application in high-end manufacturing, materials research and development, quality control, and other fields, and to provide strong support for the development of materials science.

[0005] Reference 1, "Marmotti, M., Haese-Seiller, M. & Kampmann, R. Two-dimensional position-sensitive gaseous detectors for high-resolution neutron and X-ray diffraction. Applied Physics A: Materials Science & Processing 74, s252–s254 (2002)," reports the use of two-dimensional position-sensitive gas detectors for high-resolution X-ray diffraction measurements. The GKSS research center in Germany improved the absorption and energy conversion efficiency of the gas detector for high-energy rays by filling the sensitive region of the gas detector with a mixture of Xe / CO2, thus enabling the detection of high-energy X-rays and demonstrating unique advantages in residual stress analysis of samples. However, limited by the detection mode of the gas detector itself, only 10,000 s⁻¹ could ultimately be achieved. -1 The count rate tolerance limit is limited, and there are also restrictions on the thickness of the sample to be detected and the size of the beam, resulting in low overall detection efficiency.

[0006] Reference 2, "Rack, A., Scheel, M. & Danilewsky, AN Real-time direct and diffraction X-ray imaging of irregular silicon wafer breakage. IUCrJ 3, 108–114 (2016)," reports stress detection and imaging using high-energy X-ray diffraction with scintillator materials. By coupling a CsI:Na scintillator fluorescent screen, an X-ray intensifier, and a high-speed CMOS camera, the strain evolution of the entire Si sample during laser perforation was fully recorded. However, due to the possible afterglow phenomenon of the scintillator itself and the influence of indirect detection signal loss, ghost images and a large amount of noise often appear during the imaging process, or an additional X-ray intensifier is required to assist imaging, resulting in poor analysis of X-ray diffraction.

[0007] Reference 3, "Osadchii, SM; Petukhov, AA; Dunin, VB. (2019). Silicon Detectors with a Differential Discriminator for Use in X-Ray Diffractometers. Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques, 13(4), 690–694," reports superior test results compared to NaI(Tl) scintillators in X-ray diffractometers using Si-PIN detectors, demonstrating the potential of semiconductor detectors in X-ray diffraction analysis. However, due to the inherent radiation cutoff capability of Si, filters are required to achieve optimal test results, and the energy of the X-ray tube needs to be limited, greatly restricting its application in short-wavelength high-energy X-ray diffraction.

[0008] The above literature reports the use of gas, scintillators, and silicon-based semiconductors to detect short-wavelength X-rays, and these methods have played an important role in areas such as material texture and stress detection. However, the overall detection methods still face significant challenges. Gas detectors have a clear count rate limit; scintillators, as indirect detectors, have limited signal transmission efficiency, resulting in low detection accuracy; and silicon-based semiconductor detectors have limited radiation cutoff capabilities, which cannot maximize the detection effect of short-wavelength X-ray diffraction analysis.

[0009] Therefore, in order to achieve efficient and accurate stress analysis of bulk materials, there is an urgent need for detectors with high energy resolution, high spatial resolution, and high detection efficiency in the field of short-wavelength X-ray diffraction detection. Summary of the Invention

[0010] The purpose of this invention is to address the shortcomings of existing short-wavelength X-ray diffraction detection technology and to provide a method for fabricating a one-dimensional linear array detector of zinc cadmium telluride based on the thermal sacrificial method.

[0011] The concept of this invention:

[0012] Given the detection limitations of different types of detectors in the background technology, the research team of this invention first identified cadmium zinc telluride (CdZT) as a material with the potential to solve the aforementioned problems based on the requirements. CdZT's high atomic number and large bandgap give it a natural advantage in diffraction and stress analysis fields requiring high-precision detection of short-wavelength high-energy X-rays. As a semiconductor material, it can directly achieve radiation detection, ensuring the authenticity and integrity of the signal during transmission. Specifically, CdZT has an average atomic number of up to 50, more than three times that of silicon, exhibiting excellent radiation cutoff capability, enabling effective detection of high-energy rays, and accurately addressing the current pain points in short-wavelength X-ray diffraction analysis. Furthermore, its large bandgap exceeding 1.5 eV allows it to withstand strong radiation without irradiation damage.

[0013] To achieve efficient angle-resolved detection, improve spatial and temporal resolution, and simultaneously ensure the simplicity of the detector structure and the feasibility of the electronic readout system, a one-dimensional linear array structure is more conducive to constructing high-performance, high-throughput XRD detection systems for semiconductor materials with high average atomic numbers, such as zinc cadmium telluride. Smaller pixels result in finer angle resolution, which is particularly important for high-resolution diffraction analysis requiring high-precision angle scanning.

[0014] Verification has shown that a one-dimensional linear array detector based on cadmium zinc telluride (CZT) can achieve high spatial resolution while maintaining high energy resolution, meeting the main performance requirements of diffraction analysis and stress analysis. However, the contact characteristics of the metal-semiconductor interface on the CZT surface (i.e., the diffusion of metal atoms from the electrode to the CZT crystal surface, forming interface defects and leakage current channels) present a charge crosstalk problem, interfering with carrier transport and signal conversion processes, thus limiting the application and development of CZT one-dimensional linear array detectors. Therefore, how to solve the numerous technical challenges of charge crosstalk and immature electrode fabrication processes in the practical application of CZT materials in X-ray diffraction detection is the main problem faced by the research team of this invention. To address this problem, the research team considered the following points:

[0015] First, the existing charge crosstalk problem needs to be solved. A better solution is to construct lossless electrodes based on van der Waals contacts to minimize the diffusion of metal electrodes into the semiconductor.

[0016] Secondly, it is necessary to select a suitable van der Waals contact fabrication method to meet the fabrication requirements of one-dimensional linear array detectors. This is because the fabrication process of one-dimensional linear array detectors needs to meet the requirements of array scalability and product stability. Therefore, dry transfer and wet transfer fabrication methods should be excluded first, as both of these methods are difficult to scale up for production.

[0017] Finally, the thermal sacrificial method was chosen. However, when preparing the non-destructive electrode, the continuous distribution area of ​​the electrode cannot be too large because the gas generated by the decomposition of the sacrificial layer needs to be discharged. In other words, it needs to be very narrow in the length or width direction to ensure the discharge of gas.

[0018] Based on the above inventive concept, and to achieve the above objectives, the technical solution provided by this invention is as follows:

[0019] A method for fabricating a one-dimensional linear array detector of cadmium zinc telluride based on thermal sacrifice, characterized by the following steps:

[0020] 1) Preparation of cadmium zinc telluride single crystals

[0021] Since common X-ray diffraction tests should be able to detect a certain range of the sample surface, rather than a single point, the sensitive area of ​​the detector should be able to completely receive the diffraction signals from the entire irradiated area to reflect all information of the irradiated surface. Furthermore, considering the influence of various factors such as high X-ray energy, X-ray source collimation, scattering, and the size of the sample surface, the prepared cadmium zinc telluride single crystal must meet the following requirements:

[0022] ①Cadmium zinc telluride single crystals are intact, without grain boundaries or pores;

[0023] ②The thickness of the zinc cadmium telluride single crystal is ≥0.5mm, the surface waviness is ≥10mm, and the maximum height of the surface undulation difference is ≤100nm;

[0024] For those skilled in the art, it is generally accepted that the intensity attenuation of X-rays in materials follows the formula below:

[0025]

[0026] in, The intensity of the incident ray. The remaining intensity is when the penetration distance is x. To detect the linear attenuation coefficient of a material for X-rays, This represents the penetration distance of the radiation. For cadmium zinc telluride, its linear attenuation coefficient is... According to the formula, for common short-wavelength X-rays, only a cadmium zinc telluride crystal with a thickness of about 200 micrometers is needed to achieve complete absorption of the rays. However, considering that the soft and brittle nature of cadmium zinc telluride itself will bring difficulties in processing and application, the crystal thickness is required to be ≥0.5mm to avoid the material from breaking due to being too thin. There are no special requirements for the length and width of the crystal, as long as they meet the application requirements of the specific scenario and can meet the requirements of complete reception of diffraction signals.

[0027] As the receiving end of electromagnetic waves, the flatness of the zinc cadmium telluride surface should also be required to avoid interference from the crystal surface with the final test results. Therefore, the surface waviness of zinc cadmium telluride is required to be ≥10mm and the maximum height of surface undulation is ≤100nm.

[0028] Although the above requirements can be achieved using mature processing techniques, they are essential for realizing the final effect of this invention.

[0029] ③ Due to the high-energy characteristics of short-wavelength X-rays, they may cause radiation damage to the sample under test. Low-dose radiation signals place higher demands on the detector's signal detection capability. Therefore, to achieve accurate signal detection, this invention sets requirements on the electrical properties of the detector crystal, specifically, the resistivity of the cadmium zinc telluride single crystal must be ≥5×10⁻⁶. 9 Ω·cm, electron mobility lifetime product ≥1×10 -3 cm 2 / V;

[0030] 2) Preparation of thermal sacrificial layer

[0031] The reagent used to prepare the thermal sacrificial layer (which acts as a buffer layer to avoid direct damage to the crystal surface during electrode preparation) is uniformly spin-coated onto the surface of the zinc cadmium telluride single crystal prepared in step 1) and then cured. This step does not specify the type, composition, viscosity, spin-coating speed, or curing method of the thermal sacrificial reagent, but the cured thermal sacrificial layer must meet the following requirements:

[0032] ① To ensure a stable bond between the electrode and the cadmium zinc telluride substrate during the thermal sacrificial process, the following restrictions are imposed on the surface morphology of the thermal sacrificial layer: To avoid macroscopic defects such as bubbles, wrinkles, and cracks in the subsequent electrode due to surface unevenness, the maximum height of the undulation difference on the surface of the cured thermal sacrificial layer is ≤200nm, and the surface waviness is ≥5mm; Since an excessively thick thermal sacrificial layer will cause the decomposition process to proceed too slowly or incompletely, the overall thickness of the thermal sacrificial layer is ≤30μm; At the same time, to avoid contact between the metal electrode and the crystal surface, the thermal sacrificial layer should completely cover the crystal surface;

[0033] Since this invention requires a relatively thin heat-sacrificing layer and does not pursue customized screen-printed patterns, the surface heat-sacrificing layer can be prepared using a self-selective coating method combined with post-baking to ensure controllable surface smoothness and minimal thickness variation. Using this self-selective coating combined with post-baking process, the aforementioned requirements for surface waviness can also be fully met. The following suggestions are given for controlling surface unevenness: a. During the heating and drying process, slowly raise the temperature in a nitrogen, vacuum, or organic atmosphere to suppress the release of irregular stress; b. Prefer inherently smooth, small-molecule film-forming materials to avoid high-frequency fluctuations caused by particle aggregation; c. Perform the annealing process in stages to avoid localized collapse or bulging caused by instantaneous stress release. Based on these suggestions, those skilled in the art can fully achieve the aforementioned requirements with the support of existing mature processing technologies.

[0034] ②Since zinc cadmium itself has a certain tolerance to high temperature conditions, the temperature conditions for the thermal decomposition of the heat sacrificial layer can be appropriately relaxed. However, due to the sensitivity of the surface state, especially above 250℃, zinc cadmium itself will undergo changes in properties, and the sensitivity of the surface state to the external environment will increase significantly. Therefore, there are special requirements for the composition of the gas produced by decomposition. The cured heat sacrificial layer should have a decomposition temperature of 120℃ ≤ 500℃, and no reducing gases such as H2, CH4, and CO should be produced during the decomposition process. If the decomposition temperature is ≥ 500℃, it will not be considered as a heat sacrificial layer in this preparation method.

[0035] ③ The heating decomposition time of the thermal sacrificial layer is less than 1 hour;

[0036] Due to the potential for low-temperature annealing of zinc cadmium telluride under high-temperature conditions, the entire thermal sacrificial layer decomposition process should be completed within 1 hour to avoid affecting the performance and quality of the crystal during subsequent electrode fabrication.

[0037] 3) Fabrication of one-dimensional linear array electrodes

[0038] A one-dimensional linear array electrode is fabricated on the thermally sacrificial layer prepared in step 2), and a protective ring is fabricated around the one-dimensional linear array electrode. The protective ring is mainly set to further optimize the electric field distribution and alleviate the charge crosstalk effect between the one-dimensional linear array electrodes. The protective ring forms a closed ring structure along the outer edge of the linear array electrode array. The protective ring maintains a preset distance from the outermost readout electrode and is connected to the ground potential (or a bias potential lower than that of the readout electrode) to absorb the charge from the edge region and the surface leakage current, thereby suppressing the charge crosstalk between adjacent strip electrodes. Through this structural design, the electric field distribution can be effectively improved, the capacitive coupling effect can be reduced, and the energy spectral resolution and imaging accuracy of the detector can be improved.

[0039] For the electrode materials used, specific equipment parameters during electrode fabrication are not required. However, to ensure successful electrode fabrication and excellent electrical performance, the following requirements must be met:

[0040] ① To avoid the electrodes themselves hindering the transport of electrical signals, and to mitigate the influence of potential barriers on signals in electrical contacts, the electrode material conductivity should be >10. 6 S / M, the work function of the electrode material is ≥5eV, ensuring good ohmic contact between the electrode and cadmium zinc telluride;

[0041] ② To ensure that the one-dimensional linear array detector has an excellent detection angle, 50μm≤electrode width≤200μm. At the same time, to ensure that the gas generated by decomposition can be completely discharged without bubbling, 50μm≤electrode spacing≤electrode width; the electrode width refers to the width of each electrode in the one-dimensional linear array electrode.

[0042] This invention does not have specific requirements for electrode length and electrode thickness; it is sufficient to meet common electrode thickness requirements, i.e., generally 10nm ≤ electrode thickness ≤ 200nm.

[0043] The protective ring material is the same as the electrode material, and its specific structural requirements are as follows:

[0044] a. The protective ring is continuously distributed around the periphery of the entire one-dimensional linear array electrode region as a fully enclosed structure, and its outer edge is preferably close to the edge of the cadmium zinc telluride crystal.

[0045] b. The guard ring, as a ring-shaped distribution, has a certain width, which is greater than or equal to the electrode width, to avoid the reduction in the sensitive volume of the detector due to the power supply effect; its width refers to the width of each side of the guard ring.

[0046] c. The guard ring and the electrode are not in direct contact, but are kept apart, and the minimum distance between them is greater than or equal to the electrode width;

[0047] Since the guard ring is essentially an electrode and needs to be connected to the circuit, the height of the guard ring should be consistent with the thickness of the electrode.

[0048] 4) Heating to decompose the thermal sacrificial layer

[0049] Heating is used to decompose the sacrificial layer in order to fabricate a one-dimensional array electrode on the cadmium telluride surface. No special requirements are placed on the heating rate, holding time, or heating method during the heating process, but the following requirements must be met:

[0050] ① To avoid oxidation of zinc cadmium telluride itself during the thermal sacrifice process, which would lead to performance deterioration, the oxygen content in the heating atmosphere of the material should be ≤500ppm throughout the heating process, and no other oxidizing or reducing gases should participate in the heating process. It is best to use an inert gas to guide the decomposed gas.

[0051] ② Because the gases generated by thermal decomposition have a blowing effect on the electrode, in order to avoid problems such as folding and bubbling of the electrode during the thermal sacrificial process, the decomposition rate of the thermal sacrificial layer during the entire heating process is ≤0.5μm / min (the decomposition rate is generally related to the molecular weight of the crosslinking agent of the organic sacrificial layer, the heating rate, and the heating mode, etc. The decomposition rate here generally refers to the entire thermal sacrificial layer, that is, the average decomposition rate of the entire decomposition process. The decomposition rate can be calculated from the thickness of the thermal sacrificial layer and the decomposition time). This ensures that the electrode can be completely attached to the surface of the zinc cadmium telluride crystal.

[0052] 5) Complete the encapsulation to obtain the detector.

[0053] The above parameters generally exhibit linear and favorable characteristics, meaning that bias towards a certain direction can lead to infinite performance optimization. However, due to limitations of current technical features, they cannot reach their maximum value, or they may have different maximum values ​​based on existing technical solutions. However, this does not affect the specific implementation of the present invention.

[0054] Further, in step 2), after the reagent used to prepare the heat-sacrificing layer is dropped onto the surface of the zinc-cadmium telluride single crystal prepared in step 1), a spin coater is used to achieve uniform coverage of the reagent on the zinc-cadmium telluride surface. Finally, the heat-sacrificing reagent is cured by chemical reagents, ultraviolet light or heating evaporation.

[0055] Furthermore, in step 2), the cured heat sacrificial layer must meet the following requirements: 120℃≤decomposition temperature of heat sacrificial layer≤250℃.

[0056] Furthermore, in step 3), a one-dimensional linear array electrode is prepared on the surface of the thermal sacrificial layer using thermal evaporation or magnetron sputtering. When the electrode width is small, the electrode preparation method using photolithography + thermal evaporation / magnetron sputtering has higher precision. When the electrode width is close to 200 μm, the electrode preparation can be completed directly using high-precision thermal evaporation equipment or magnetron sputtering equipment.

[0057] Further, step 5) specifically involves:

[0058] On the back side of the surface where the one-dimensional linear array electrodes are located, a surface electrode is fabricated using magnetron sputtering, and the device is packaged according to common packaging methods in the industry to obtain the detector.

[0059] Meanwhile, the present invention provides a one-dimensional linear array detector of cadmium zinc telluride prepared by the above method based on the thermal sacrifice method, and a short-wavelength X-ray diffraction stress analyzer containing the detector.

[0060] The advantages of this invention are:

[0061] 1. This invention can significantly improve the detection efficiency of high-energy rays. The 1mm thick zinc zinc cadmium telluride detector prepared based on this method can achieve a detection efficiency of 97.4% for short-wavelength X-rays of 60keV, while the existing Si detector has a detection efficiency of less than 10% for the same rays. The higher detection efficiency can significantly improve the accuracy and reliability of the detection results, reduce signal loss and distortion, and thus ensure accurate and reliable diffraction data.

[0062] 2. This invention can significantly improve the energy detection range in diffraction phase analysis and stress analysis. The one-dimensional linear array detector of zinc cadmium telluride constructed based on this method has a detectable energy range of up to 5-80 keV, which is currently the linear array detector with the largest energy detection range. It can detect X-rays of different energies used for samples of different thicknesses, greatly expanding the detection range of high-energy diffraction and stress analysis.

[0063] 3. This invention can significantly improve the tolerance range of radiation count rate in diffraction phase analysis and stress analysis. The one-dimensional linear array detector of cadmium zinc telluride constructed based on this method has a single-channel count rate ≥70kcps, and its count tolerance far exceeds that of existing detectors, recording more radiation signals in a shorter time and significantly improving data acquisition efficiency.

[0064] 4. The one-dimensional linear array detector of cadmium zinc telluride (CZN) prepared by this invention can significantly alleviate charge crosstalk between electrodes. The thermal sacrificial method for constructing CZN surface electrodes effectively avoids the mechanical damage to the CZN surface caused by traditional methods such as evaporation and magnetron sputtering. There is no longer a significant intermediate layer at the interface between CZN and the electrode, the electric field distribution is optimized, and charge crosstalk between adjacent electrodes is significantly reduced. Furthermore, the one-dimensional linear array electrode constructed based on this method exhibits better scalability and stability. Attached Figure Description

[0065] Figure 1 This is a schematic diagram illustrating the fabrication principle of the cadmium zinc telluride one-dimensional linear array detector involved in the method of the present invention.

[0066] Figure 2 This is a physical image of the one-dimensional linear array electrode of the cadmium zinc telluride detector prepared in Example 1 of the present invention;

[0067] Figure 3This is a comparison of the current test results between adjacent electrodes of the one-dimensional linear array detector of zinc cadmium telluride prepared in Example 1 of the present invention with the test results of samples prepared by the traditional photolithography method;

[0068] Figure 4 This is a comparison between the single-electrode energy spectrum test results of the one-dimensional linear array detector of zinc cadmium telluride prepared in Example 1 of the present invention and the test results of samples prepared by traditional photolithography.

[0069] Figure 5 This is a comparison of the current test results between adjacent electrodes of the one-dimensional linear array detector of zinc cadmium telluride prepared in Example 2 of the present invention with the test results of samples prepared by the traditional photolithography method;

[0070] Figure 6 This is a comparison between the single-electrode energy spectrum test results of the one-dimensional linear array detector of zinc cadmium telluride prepared in Example 2 of the present invention and the test results of samples prepared by traditional photolithography. Detailed Implementation

[0071] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0072] This invention, based on cadmium zinc telluride (CZT) material, utilizes the thermal sacrificial method to design and fabricate a one-dimensional linear array detector for X-ray diffraction. By constructing van der Waals contacts on the CZT surface, the electric field distribution between the electrodes of the one-dimensional linear array is optimized, providing a new solution to the charge crosstalk problem and exhibiting excellent detection performance. Future widespread application is expected to provide a powerful detection method for three-dimensional phase analysis and stress analysis of bulk materials.

[0073] Example 1

[0074] like Figure 1 As shown, the fabrication method of a one-dimensional linear array detector of cadmium zinc telluride based on the thermal sacrificial method includes the following steps:

[0075] Step 1: Prepare tellurium zinc cadmium materials

[0076] Select a complete cadmium zinc telluride single crystal ingot, cut it to obtain a size of 50×50×2mm. 3 The resistivity of the cadmium zinc telluride wafer was measured to be 8.8 × 10⁻⁶. 10 Its electron mobility is 1.8 × 10 Ω·cm. -3 cm 2 / V, and then mechanical polishing, chemical polishing and chamfering are performed in sequence to make its surface waviness ≥10mm and the maximum height of surface undulation ≤100nm, which meets the requirements of device fabrication;

[0077] Step 2: Prepare a thermal sacrificial layer on the cadmium zinc telluride surface

[0078] Polypropylene carbonate (PPC) was dissolved in anisole to prepare a 12% PPC precursor solution.

[0079] Then, the PPC precursor solution was spin-coated onto the cadmium zinc telluride surface using a spin coater at a speed of 5500 r / min to form a uniform thin film. Afterward, it was heated to 120℃ on a hot plate and held for 5 minutes to allow the solvent in the precursor solution to completely evaporate, forming a solid PPC thermal sacrificial layer. AFM test results showed that under these preparation parameters, the thickness of the thermal sacrificial layer was 18 μm, the surface waviness was ≥5 mm, the maximum height of the surface undulation was ≤200 nm, and the decomposition temperature of the thermal sacrificial layer was 250℃, which met the thermal decomposition requirements.

[0080] Step 3: Fabricate a one-dimensional linear array electrode structure on the thermally sacrificial layer

[0081] One-dimensional linear array electrodes were fabricated on a cadmium zinc telluride surface using magnetron sputtering. A flexible mask was used to control the electrode size to 50 μm × 49 mm (width × length), with a 50 μm spacing between the electrodes. A protective ring structure, 50 μm wide, was designed around the periphery of the one-dimensional linear array electrode region, and the protective ring was also 50 μm wide and spaced 50 μm from the electrodes. Figure 2 As shown.

[0082] Step 4: Remove the thermal sacrificial layer between the electrode and the cadmium zinc telluride crystal by heating.

[0083] The sample was heated to 250°C and held for 45 minutes in a glove box (oxygen content ≤500ppm, no other oxidizing or reducing gases) using a hot stage to achieve complete removal of the thermal sacrificial layer.

[0084] Step 5: Fabricate the back electrode and complete the device packaging.

[0085] On the back side of the surface where the one-dimensional linear array electrodes are located, surface electrodes are fabricated using magnetron sputtering, and the device is packaged using conductive graphite adhesive and wires according to common packaging methods in the industry, in preparation for the next step of device testing.

[0086] Step 6: Perform crosstalk current test on adjacent one-dimensional linear array electrodes of the device.

[0087] After the device is flip-chip packaged, electrical tests are performed on the adjacent electrodes using a readout system. The results are as follows: Figure 3 As shown, the current between the coplanar electrodes of the sample prepared by the thermal sacrificial method is significantly suppressed.

[0088] Step 7: Analyze the single-channel energy dispersive spectroscopy (EDS) results of the device.

[0089] use 241The prepared sample was tested using an Am@59.5keV radioactive source with energy resolution, such as... Figure 4 As shown, a one-dimensional linear array detector constructed based on the method of this invention is designed for... 241 The energy resolution of Am@59.5keV is significantly improved compared to the energy resolution of devices fabricated in the same batch using traditional photolithography, indicating the great potential of the zinc zinc cadmium device constructed by this method for short-wavelength X-rays and ensuring that the fabricated device has good energy resolution for high-energy rays.

[0090] Example 2

[0091] A method for fabricating a one-dimensional linear array detector of cadmium zinc telluride based on the thermal sacrificial method includes the following steps:

[0092] Step 1: Prepare tellurium zinc cadmium materials

[0093] A complete cadmium zinc telluride single crystal ingot was selected, cut, and obtained as a 25×25×1.5mm piece. 3 The resistivity of the cadmium zinc telluride wafer was measured to be 9.3 × 10⁻⁶. 10 Its electron mobility is 1.6 × 10 Ω·cm. -3 cm 2 / V, and then mechanical polishing, chemical polishing and chamfering are performed in sequence to make its surface waviness ≥10mm and the maximum height of surface undulation ≤100nm, which meets the requirements of device fabrication;

[0094] Step 2: Prepare a thermal sacrificial layer on the cadmium zinc telluride surface

[0095] Polypropylene carbonate (PPC) was dissolved in anisole to prepare a 5% PPC precursor solution.

[0096] Then, the PPC precursor solution was spin-coated onto the cadmium zinc telluride surface using a spin coater at a speed of 6000 r / min to form a uniform thin film. Afterward, the surface was heated to 75°C and held for 5 minutes to allow the solvent in the precursor solution to completely evaporate, forming a solid PPC thermal sacrificial layer. AFM test results showed that under these preparation parameters, the thickness of the thermal sacrificial layer was 5 μm, the surface waviness was ≥5 mm, the maximum height of the surface undulation was ≤200 nm, and the decomposition temperature of the thermal sacrificial layer was 250°C, which met the thermal decomposition requirements.

[0097] Step 3: Fabricate a one-dimensional linear array electrode structure on the thermally sacrificial layer

[0098] One-dimensional linear array electrodes were fabricated on the surface of zinc cadmium telluride using measurement and control sputtering. The size of the electrodes was controlled to be 100 μm × 24 mm (width × length) using a flexible mask, and the spacing between the electrodes was 80 μm. At the same time, a protective ring structure was designed around the one-dimensional linear array electrode area. The width of the protective ring was 80 μm, and the protective ring was also spaced 80 μm from the electrodes.

[0099] Step 4: Remove the thermal sacrificial layer between the electrode and the cadmium zinc telluride crystal by heating.

[0100] The sample was heated to 250°C and held for 10 minutes in a glove box (oxygen content ≤500ppm, no other oxidizing or reducing gases) using a hot stage to achieve complete removal of the thermal sacrificial layer.

[0101] Step 5: Fabricate the back electrode and complete the device packaging.

[0102] On the back side of the surface where the one-dimensional linear array electrodes are located, surface electrodes are fabricated using magnetron sputtering, and the device is packaged using conductive graphite adhesive and wires according to common packaging methods in the industry, in preparation for the next step of device testing.

[0103] Step 6: Perform crosstalk current test on adjacent one-dimensional linear array electrodes of the device.

[0104] After the device is flip-chip packaged, electrical tests are performed on the adjacent electrodes using a readout system. The results are as follows: Figure 5 As shown, the current between the coplanar electrodes of the sample prepared by the thermal sacrificial method is significantly suppressed.

[0105] use 241 The prepared sample was tested using an Am@59.5keV radioactive source with energy resolution, such as... Figure 6 As shown, the one-dimensional linear array detector constructed based on this method is designed for... 241 The energy resolution of Am@59.5keV is significantly improved compared to the energy resolution of devices fabricated in the same batch using traditional photolithography, indicating the great potential of the zinc zinc cadmium device constructed by this method for short-wavelength X-rays and ensuring that the fabricated device has good energy resolution for high-energy rays.

[0106] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the scope of the technology disclosed in the present invention, and such modifications or substitutions should all be covered within the scope of protection of the present invention.

Claims

1. A method for fabricating a one-dimensional linear array detector of cadmium zinc telluride based on the thermal sacrificial method, characterized in that, Includes the following steps: 1) Preparation of cadmium zinc telluride single crystals The prepared cadmium zinc telluride single crystals must meet the following requirements: ①Cadmium zinc telluride single crystals are intact, without grain boundaries or pores; ②The thickness of the zinc cadmium telluride single crystal is ≥0.5mm, the surface waviness is ≥10mm, and the maximum height of the surface undulation difference is ≤100nm; ③ The resistivity of cadmium zinc telluride single crystal is ≥5×10⁻⁶. 9 Ω·cm, electron mobility lifetime product ≥1×10 -3 cm 2 / V; 2) Preparation of thermal sacrificial layer The reagents used to prepare the heat-sacrificing layer are uniformly spin-coated onto the surface of the cadmium zinc telluride single crystal prepared in step 1) and cured. The cured heat-sacrificing layer must meet the following requirements: ①The thickness of the heat sacrificial layer is ≤30μm, the surface waviness is ≥5mm, and the maximum height of the surface undulation difference is ≤200nm; ②120℃≤decomposition temperature of the thermal sacrificial layer≤500℃, and no reducing gas can be produced during the decomposition process; ③ The heating decomposition time of the thermal sacrificial layer is less than 1 hour; 3) Fabrication of one-dimensional linear array electrodes According to the following requirements, a one-dimensional linear array electrode is fabricated on the thermal sacrificial layer prepared in step 2), and a protective ring is fabricated around the one-dimensional linear array electrode: ① Electrode material conductivity > 10 6 S / M, work function of electrode material ≥5eV; ②50μm≤electrode width≤200μm, and 50μm≤electrode spacing≤electrode width; The protective ring material is the same as the electrode material, and its specific structural requirements are as follows: a. The guard ring is continuously distributed around the periphery of the one-dimensional linear array electrode region as a fully enclosed structure; b. The guard ring is distributed in a ring shape, and its width is greater than or equal to the electrode width; c. The guard ring and the electrode are not in direct contact, and the minimum distance between them is greater than or equal to the electrode width; 4) Heating to decompose the thermal sacrificial layer The heating process must meet the following requirements: ① The oxygen content in the heating atmosphere is ≤500ppm, and no other oxidizing or reducing gases participate in the heating process; ②The decomposition rate of the thermal sacrificial layer during the entire heating process is ≤0.5μm / min; 5) Complete the encapsulation to obtain the detector.

2. The method for fabricating a one-dimensional linear array detector of cadmium zinc telluride based on the thermal sacrifice method according to claim 1, characterized in that: In step 2), the reagent used to prepare the heat-sacrificing layer is dropped onto the surface of the zinc cadmium telluride single crystal prepared in step 1), and a spin coater is used to achieve uniform coverage of the reagent on the zinc cadmium telluride surface. Finally, the heat-sacrificing reagent is cured by chemical reagents, ultraviolet light or heating evaporation.

3. The method for fabricating a one-dimensional linear array detector of cadmium zinc telluride based on the thermal sacrificial method according to claim 1 or 2, characterized in that: In step 2), the cured heat sacrificial layer must meet the following requirements: 120℃≤decomposition temperature of heat sacrificial layer≤250℃.

4. The method for fabricating a one-dimensional linear array detector of cadmium zinc telluride based on the thermal sacrifice method according to claim 3, characterized in that: In step 3), a one-dimensional linear array electrode is prepared on the surface of the thermal sacrificial layer using thermal evaporation or magnetron sputtering.

5. The method for fabricating a one-dimensional linear array detector of cadmium zinc telluride based on the thermal sacrifice method according to claim 4, characterized in that, Step 5) specifically involves: On the back side of the surface where the one-dimensional linear array electrodes are located, a surface electrode is fabricated using magnetron sputtering, and the device is packaged to obtain a detector.

6. A one-dimensional linear array detector for cadmium zinc telluride based on the thermal sacrifice method, characterized in that: It is prepared by any one of the methods described in claims 1-5.

7. A short-wavelength X-ray diffraction stress analyzer, characterized in that: Including the cadmium zinc telluride one-dimensional linear array detector based on the thermal sacrifice method as described in claim 6.

Images