Wafer positive and negative ion coordination co-doping method and wafer

Abstract

The invention provides a wafer positive and negative ion coordination co-doping method and a wafer. The method comprises the following steps: S1, providing a gallium arsenide substrate; s2, preparing a doped target material comprising positive and negative ions with coordination numbers on the surface of the gallium arsenide substrate; s3, packaging the gallium arsenide substrate connected with the doped target material; and S4, synchronously diffusing the positive and negative ions in the doped target material into the gallium arsenide substrate. According to the invention, the doping target material is used for doping the substrate in a specific mode, so that the substrate is endowed with a transition restriction characteristic of a new energy level, and the carrier lifetime of the material is prolonged. Meanwhile, on the basis of the charge compensation effect, the increase of extra free carriers of the gallium arsenide substrate caused by doping can be avoided, in addition, the problems that in a traditional doping mode, doping is not uniform, the positive and negative ion doping concentration difference is large, and the property is unstable are solved, and the performance of the gallium arsenide substrate is improved. Therefore, the method has the advantages of simplicity in operation, high universality, high controllability, uniform and stable performance, capability of considering the resistivity of gallium arsenide and the life product of a carrier and the like.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a wafer positive and negative ion coordination co-doping method and a wafer. Background Art

[0002] In today's technological development, semiconductor photodetection technology has shown great application potential in many fields with its significant advantages. This technology has a series of excellent characteristics such as zero dark noise, high spatial resolution, high dynamic range, high linearity and the ability to achieve multi-energy images. Especially in the field of high-energy ray imaging, which has extremely demanding performance requirements, it has become the next generation of high-energy ray imaging technology that has attracted much attention.

[0003] High-energy X-ray imaging technology plays a vital role in many fields such as medical treatment, industrial inspection, and safety inspection. In the medical field, high-energy X-ray imaging can help doctors clearly observe the internal tissue structure and pathological conditions of the human body, providing a key basis for the diagnosis and treatment of diseases; in industrial inspection, it can be used to detect defects and damage inside materials to ensure product quality and production safety; in safety inspection, it can quickly and accurately detect hidden dangerous items. Therefore, improving the performance of high-energy X-ray imaging technology is of great significance to promoting the development of these fields.

[0004] As the core component of semiconductor photoelectric detection technology, the performance of semiconductor materials directly affects the working effect of the detector. Due to its unique physical properties, gallium arsenide crystal has become one of the ideal semiconductor materials for manufacturing high-energy ray detectors. It can directly convert high-energy rays into photocurrent signals, providing an efficient and convenient way to detect high-energy rays.

[0005] However, there are many urgent problems to be solved when using gallium arsenide crystals to manufacture high-energy ray detectors. The resistivity and carrier lifetime product of intrinsic gallium arsenide are difficult to meet the requirements of medical detection chips. In high-energy ray detection applications, low dark noise is one of the key factors to ensure the high-precision operation of the detector, and low dark noise requires the material to have a higher resistivity so that it can still maintain a low dark noise signal under high bias working conditions. At the same time, a high carrier lifetime product is crucial to improving the sensitivity and response speed of the detector, which requires the material to have a higher carrier mobility and carrier lifetime.

[0006] At present, a single doping method often cannot take into account the improvement of both resistivity and carrier lifetime product at the same time. In actual operation, when trying to optimize one of the performance indicators, it is often inevitable to damage the other performance. For example, a doping method that increases resistivity may reduce carrier mobility or carrier lifetime, thereby affecting the carrier lifetime product; conversely, a doping method that increases the carrier lifetime product may cause a decrease in resistivity and increase dark noise. This contradictory situation places extremely stringent requirements on the preparation of high-energy ray detection-grade gallium arsenide.

[0007] In order to solve these problems, the industry is currently trying to use saturated vapor pressure for anion and cation doping. However, this method has obvious defects. Due to uneven doping, the properties of gallium arsenide at different locations are unstable, making the performance of the detector inconsistent in different areas, affecting the overall detection effect. Moreover, this uneven doping further exacerbates the difficulty of improving the resistivity and carrier lifetime product, making it difficult for existing technologies to meet the requirements of high-energy ray detectors for gallium arsenide material performance. Summary of the invention

[0008] To this end, the technical problem to be solved by the present invention is to overcome the problem that it is difficult to take into account both resistivity and carrier lifetime product in the gallium arsenide preparation process in the prior art, and to provide a wafer positive and negative ion coordination co-doping method and a wafer.

[0009] In order to solve the above technical problems, the present invention provides a wafer positive and negative ion coordination co-doping method, which comprises: step S1, providing a gallium arsenide substrate; step S2, preparing a doping target material on the surface of the gallium arsenide substrate, wherein the doping target material comprises positive and negative ions with a coordination number; step S3, packaging the gallium arsenide substrate connected with the doping target material; step S4, heating the packaged material at a preset temperature, so that the positive ions and negative ions in the doping target material are synchronously diffused into the gallium arsenide substrate, so as to obtain a wafer co-doped with positive and negative ions.

[0010] In one embodiment of the present invention, in step S1, the gallium arsenide substrate has a thickness of 300 μm to 2000 μm.

[0011] In one embodiment of the present invention, step S2 is specifically: step S21, selecting a coordination compound as a doping source according to the gallium arsenide substrate; step S22, coating the coordination compound on the surface of the gallium arsenide substrate by magnetron sputtering to obtain a doping target material connected to the surface of the gallium arsenide substrate.

[0012] In one embodiment of the present invention, step S3 is specifically as follows: step S31, welding and encapsulating the gallium arsenide substrate connected to the doped target material inside a quartz tube; step S32, adding arsenic element into the quartz tube to maintain the arsenic pressure in the quartz tube stable.

[0013] In one embodiment of the present invention, the addition amount m of the elemental arsenic 砷 > 0.00124·RT / V, where R is the gas constant value, T is the holding temperature, and V is the volume of the quartz tube.

[0014] In one embodiment of the present invention, in step S4: the encapsulated material is placed in an annealing furnace, heated to a preset temperature, and held for a preset time, so that positive ions and negative ions in the doped target diffuse synchronously into the gallium arsenide substrate.

[0015] In one embodiment of the present invention, the preset temperature is 700°C to 1200°C, and the preset time is 1h to 240h.

[0016] In one embodiment of the present invention, the positive ions in the doped target are one of manganese ions, copper ions, cobalt ions, and nickel ions.

[0017] In one embodiment of the present invention, the method for co-doping positive and negative ions of a wafer includes step S5: grinding and polishing the wafer co-doped with positive and negative ions until its surface is smooth, and then performing post-treatment processing.

[0018] The present invention also provides a wafer prepared by using the above method for co-doping positive and negative ions of a wafer.

[0019] The above technical solution of the present invention has the following advantages compared with the prior art:

[0020] For the method for co-doping positive and negative ions of a wafer and the wafer of the present invention, by doping the substrate in a specific manner using a doped target, the transition forbidden characteristic of a new energy level is imparted to the substrate. This characteristic can effectively reduce the recombination probability of excited electrons and holes, thereby improving the carrier lifetime of the material. At the same time, the doping energy levels introduced by the positive and negative ions in the present invention have a certain coordination number. Through charge compensation, it is possible to avoid an increase in additional free carriers in the gallium arsenide substrate caused by doping, thereby taking into account the improvement of both the resistivity and the carrier lifetime product of gallium arsenide. In addition, the present invention adopts a doping method of coating and diffusion, fundamentally solving the problems of uneven doping, large differences in positive and negative ion doping concentrations, and unstable properties existing in traditional doping methods. Compared with the current conventional wafers, the present application has the advantages of simple operation, strong universality, strong controllability, uniform and stable quality, and can take into account the resistivity and carrier lifetime product of gallium arsenide, and has a broad application prospect in this industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to make the content of the present invention easier to be clearly understood, the present invention will be further described in detail below according to specific embodiments of the present invention in conjunction with the drawings.

[0022] Figure 1 It is a flowchart of the method for co-doping of positive and negative ions coordinated on a wafer in a preferred embodiment of the present invention;

[0023] Figure 2 It is an energy spectrum diagram of a gallium arsenide single crystal wafer in another embodiment of the present invention;

[0024] Figure 3 is Figure 2 The optoelectronic decay analysis diagram of the shown gallium arsenide single crystal wafer. Detailed implementation manners

[0025] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the exemplified embodiments are not intended to limit the present invention.

[0026] Embodiment 1

[0027] Refer to Figure 1 As shown, this embodiment provides a method for co-doping of positive and negative ions coordinated on a wafer, which includes:

[0028] Step S1: Provide a gallium arsenide substrate. Further, in this embodiment, the thickness of the gallium arsenide substrate is 579 μm. In different embodiments, the thickness of the gallium arsenide substrate can be configured to be 300 μm to 2000 μm according to actual usage requirements, and the present invention does not make specific limitations thereto.

[0029] Step S2: Prepare a doping target on the surface of the gallium arsenide substrate, and the doping target includes positive and negative ions with coordination numbers. Further, in this embodiment, step S2 is specifically:

[0030] Step S21: Select a coordination compound as the doping source based on the gallium arsenide substrate. Specifically, in this embodiment, MnTe is selected as the doping source, thereby introducing positive and negative ions with a certain coordination number. Based on this, on the one hand, it can form two new energy levels in the gallium arsenide bandgap. Through the transition forbidden characteristics of the new energy levels, the recombination of excited electrons and holes can be effectively reduced. Specifically, in this embodiment, the d-d orbital transition of Mn is forbidden. After the carriers are trapped in the new energy levels, due to the transition forbidden characteristics, it can effectively reduce the recombination of excited electrons and holes, thereby achieving the purpose of improving the carrier lifetime of the material. On the other hand, in conventional materials, the increase in extra free carriers is one of the main reasons for the significant reduction in the material resistance. In the present invention, the doping energy levels introduced by the positive and negative ions have a certain coordination number, and thus the increase in extra free carriers in gallium arsenide caused by doping can be avoided through charge compensation, thereby taking into account both the increase in the resistivity of gallium arsenide and the increase in the carrier lifetime product. In addition, this application can also effectively adjust the resistivity of gallium arsenide by regulating the density of the new energy levels (regulating the doping element concentration), and then obtain semi-insulating gallium arsenide by controlling the optimal doping concentration.

[0031] Further, in different embodiments, the doping source can also be configured as CoTe(Se, S), CuTe(Se, S), NiTe(Se, S), etc.

[0032] Step S22: Deposit the coordination compound on the surface of the gallium arsenide substrate by magnetron sputtering to obtain a doping target connected to the surface of the gallium arsenide substrate. In this embodiment, the target atoms or molecules are uniformly sputtered and deposited, so that the coordination compound can form a uniform coating on the substrate, thereby ensuring the doping effect and the uniform distribution of the substrate properties. Moreover, the sputtered particles have high energy and strong interaction with the substrate, and the coating is tightly combined with the substrate, which can prevent problems such as peeling and flaking during subsequent processing or use, and improve the stability and reliability. At the same time, the magnetron sputtering process has good controllability. Operators can precisely control the coating thickness by adjusting the sputtering time, power, gas flow rate, etc., to meet the requirements of different devices for the doping concentration and depth. They can also flexibly control the coating element ratio by adjusting the target composition or introducing different gases, and optimize the doping target composition as needed. In addition, magnetron sputtering is carried out at a relatively low temperature, which can avoid the adverse effects of high temperature on the characteristics of the gallium arsenide substrate and the coordination compound, and prevent substrate lattice damage and impurity diffusion.

[0033] Step S3: Package the gallium arsenide substrate connected with the doping target to facilitate the subsequent sputtering deposition and ion diffusion of the doping target. Further, in this embodiment, step S3 is specifically:

[0034] Step S31: Weld and package the gallium arsenide substrate connected with the doping target inside a quartz tube;

[0035] Step S32, adding arsenic element to the quartz tube to maintain the arsenic pressure in the quartz tube stable, wherein the amount of arsenic element added is m 砷 >0.00124·RT / V, where R is the gas constant value, T is the holding temperature, and V is the volume of the quartz tube.

[0036] It should be noted that GaAs is prone to decomposition reaction at high temperature to produce gallium (Ga) and arsenic (As). If the arsenic pressure in the quartz tube is too low, the decomposition reaction will proceed forward, resulting in the quality of the GaAs material being reduced or even damaged. By adding arsenic to maintain a stable arsenic pressure, the decomposition of GaAs can be suppressed, ensuring the stability of the structure and performance of the GaAs material, thereby allowing the gallium and arsenic atoms to combine in the expected proportion and manner, thereby growing high-quality GaAs crystals.

[0037] Step S4, heating the packaged material at a preset temperature to allow the positive ions and negative ions in the doping target material to diffuse synchronously into the gallium arsenide substrate to obtain a wafer co-doped with positive and negative ions.

[0038] Further, in step S4: the packaged material is placed in an annealing furnace, heated to a preset temperature, and kept warm for a preset time, so that the positive ions and negative ions in the doped target material are synchronously diffused into the gallium arsenide substrate. In this embodiment, the preset temperature is 1000°C, and the preset time is 20 hours, thereby obtaining a gallium arsenide single crystal wafer co-doped with manganese and tellurium coordination. In different implementations, the preset temperature can be configured to 700°C to 1200°C according to actual use requirements, and the preset time can be configured to 1 hour to 240 hours according to actual use requirements, and the present invention does not impose specific restrictions on this.

[0039] This embodiment also includes step S5: grinding and polishing the wafer co-doped with positive and negative ions until its surface is smooth and then performing post-processing.

[0040] See also Figure 2 As shown, this embodiment performs composition analysis on the prepared positive and negative ion coordinated co-doped wafers. Figure 2 It can be seen that the Mn and Te doping levels inside the prepared wafer are at similar levels, which can meet the charge compensation effect on the gallium arsenide material.

[0041] In order to verify the resistivity of the wafer co-doped with positive and negative ions, this embodiment detects the current at different voltages, as shown in Table 1.

[0042] Table 1. Current statistics of wafers co-doped with positive and negative ions at different voltages

[0043]

[0044] As can be seen from the above table, for the gallium arsenide material in this application, at a high voltage of 100V, the dark current is only 1428 / 1470nA, and its resistivity reaches about 10 8 Ω·cm, which can prove that it has a high resistivity.

[0045] See Figure 3 As shown, in this embodiment, the photoelectric attenuation of the gallium arsenide single crystal wafer is analyzed. From Figure 3 it can be seen that the carrier lifetime of the gallium arsenide material is as high as 17.604 μs, which is much higher than the theoretical value of the carrier lifetime of intrinsic gallium arsenide (10 -2 ~10 -1 μs), which can prove that it has a high carrier lifetime.

[0046] Embodiment 2

[0047] This embodiment provides another method for co-doping positive and negative ions in a wafer. The main steps and principles are the same as those in Embodiment 1, and will not be elaborated here. In this embodiment, the positive ion in the doping target is a copper ion, the thickness of the gallium arsenide substrate is 300 μm, the preset temperature is 700 °C, and the preset time is 1 h. In different embodiments, the positive ion in the doping target can be configured as one of transition metal ions such as manganese ions, copper ions, cobalt ions, and nickel ions. The present invention does not make specific limitations on this.

[0048] Embodiment 3

[0049] This embodiment provides a wafer prepared by using the method for co-doping positive and negative ions in a wafer described in Embodiment 1.

[0050] In summary, for the method for co-doping positive and negative ions in a wafer and the wafer described in the present invention, by doping the substrate in a specific manner using a doping target, the substrate is given the transition forbidden characteristic of new energy levels. This characteristic can effectively reduce the recombination probability of excited electrons and holes, and thus improve the carrier lifetime of the material. At the same time, the doping energy levels introduced by the positive and negative ions in the present invention have a certain coordination number. Through the charge compensation effect, it is possible to avoid the increase of additional free carriers in the gallium arsenide substrate caused by doping, and thus take into account the improvement of the product of the resistivity and carrier lifetime of gallium arsenide. In addition, the present invention uses a doping method of coating diffusion, which fundamentally solves the problems of uneven doping, large difference in positive and negative ion doping concentrations, and unstable properties existing in the traditional doping method. Compared with the current conventional wafers, this application has the advantages of simple operation, strong universality, strong controllability, uniform and stable quality, and can take into account the product of the resistivity and carrier lifetime of gallium arsenide, and has a broad application prospect in this industry.

[0051] Obviously, the above embodiments are merely examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. A wafer positive and negative ion coordination co-doping method, characterized in that: include: Step S1, providing a gallium arsenide substrate; Step S2, preparing a doping target material on the surface of the gallium arsenide substrate, wherein the doping target material includes positive and negative ions with coordination numbers; Step S3, packaging the gallium arsenide substrate connected to the doped target material; Step S4, heating the packaged material at a preset temperature to allow the positive ions and negative ions in the doping target material to diffuse synchronously into the gallium arsenide substrate to obtain a wafer co-doped with positive and negative ions.

2. The wafer positive and negative ion coordination co-doping method according to claim 1, characterized in that: In step S1, the gallium arsenide substrate has a thickness of 300 μm to 2000 μm.

3. The wafer positive and negative ion coordination co-doping method according to claim 1, characterized in that: Step S2 is specifically as follows: Step S21, selecting a coordination compound as a doping source according to the gallium arsenide substrate; Step S22: coating the coordination compound on the surface of the gallium arsenide substrate by magnetron sputtering to obtain a doping target material connected to the surface of the gallium arsenide substrate.

4. The wafer positive and negative ion coordination co-doping method according to claim 1, characterized in that: Step S3 is specifically as follows: Step S31, welding and packaging the gallium arsenide substrate connected to the doped target material inside a quartz tube; Step S32: adding arsenic element into the quartz tube to maintain the arsenic pressure in the quartz tube stable.

5. The wafer positive and negative ion coordination co-doping method according to claim 4, characterized in that: The amount of arsenic added is m 砷 >0.00124·RT / V, where R is the gas constant value, T is the holding temperature, and V is the volume of the quartz tube.

6. The wafer positive and negative ion coordination co-doping method according to claim 1, characterized in that: In step S4: placing the packaged material in an annealing furnace, heating it to a preset temperature, and then keeping the temperature for a preset time, so that the positive ions and negative ions in the doped target material are synchronously diffused into the gallium arsenide substrate.

7. The wafer positive and negative ion coordination co-doping method according to claim 6, characterized in that: The preset temperature is 700° C. to 1200° C., and the preset time is 1 hour to 240 hours.

8. The wafer positive and negative ion coordination co-doping method according to claim 1, characterized in that: The positive ions in the doped target material are one of manganese ions, copper ions, cobalt ions and nickel ions.

9. The wafer positive and negative ion coordination co-doping method according to claim 1, characterized in that: The wafer positive and negative ion coordination co-doping method comprises step S5: grinding and polishing the positive and negative ion coordination co-doped wafer until its surface is smooth and then performing post-processing.

10. A wafer, characterized in that: The wafer is prepared by the positive and negative ion coordination co-doping method described in any one of claims 1 to 9.

Images