Anion-cation co-doped heat-sensitive material, preparation method thereof and micro-bolometer

Abstract

The invention provides an anion-cation co-doped heat-sensitive material and a preparation method thereof.The method comprises the following steps that S1, metal vanadium particles and cation-doped metal M particles are melted and forged, and an alloy target material is obtained; s2, the alloy target material is subjected to reactive sputtering under the mixed atmosphere of inert gas and nitric oxide, and an intermediate material is obtained; and S3, carrying out annealing heat treatment on the intermediate material in a nitrogen oxide-containing atmosphere to obtain the anion-cation co-doped heat-sensitive material. The activation energy of the heat-sensitive material is changed through cation doping, the resistance temperature coefficient of the heat-sensitive material is improved, the thermoelectric conversion capacity of the heat-sensitive material is enhanced, the response rate of the micro-bolometer is improved, meanwhile disturbance possibly caused by redundant electrons brought by cation doping is compensated through anion doping, 1 / f noise of the heat-sensitive material is reduced, and the heat-sensitive material can be applied to the micro-bolometer. And the NETD of the micro-bolometer is optimized.

Description

Technical Field

[0001] The invention belongs to the technical field of microbolometer detectors, and in particular relates to an anion-cation co-doped thermosensitive material and a preparation method thereof, and a microbolometer. Background Art

[0002] Thermosensitive film deposition technology is one of the core technologies for preparing microbolometers. Its growth quality directly affects the performance parameters of the bolometer, so the performance and preparation methods of thermosensitive films are also widely developed. Common magnetron sputtering and ion beam deposition methods are both high-energy argon (Ar) ion flow bombarding the target material to sputter out surface atoms, which then react with oxygen (O2) to obtain a vanadium oxide film of a specific component or a cation-doped vanadium oxide film.

[0003] As a metal oxide, vanadium oxide films with specific components may form oxygen vacancies during the deposition process due to the overflow of oxygen atoms. In addition, specific high-valent cation doped vanadium oxide films can change the activation energy of d electron orbits, thereby improving their temperature coefficient of resistance (TCR) near room temperature. However, due to the formation of donor energy levels due to the generation of substitutional impurities, the positive center has a weaker binding effect on excess valence electrons, which are easily freed from the binding and become conductive electrons to move freely, which will enhance the conductivity of the thermosensitive film. However, since the donor energy level can be used as a trap center to capture / emit carriers, these processes may cause the increase of 1 / f noise of the thermosensitive film and are not conducive to the resolution of small signals by the microbolometer detector. Traditional metal packaging can avoid the above problems as much as possible because the semiconductor cooler can ensure that the device works at a fixed temperature, but the wafer-level or pixel-level packaging that is being developed does not have a working module to ensure the temperature, which puts higher requirements on the thermal conversion ability and stability of the thermosensitive film itself. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing an anion-cation co-doped thermosensitive material, which can at least solve some of the defects existing in the prior art.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] A method for preparing an anion-cation co-doped thermosensitive material comprises the following steps:

[0007] S1, melting and forging metal vanadium particles and cation-doped metal M particles to obtain an alloy target;

[0008] S2, subjecting the alloy target to reactive sputtering in a mixed atmosphere of an inert gas and nitrogen oxides to obtain an intermediate material;

[0009] S3. In a nitrogen oxide-containing atmosphere, the intermediate material is subjected to annealing heat treatment to obtain an anion-cation co-doped thermosensitive material.

[0010] Furthermore, in step S1, the mass ratio of the metal vanadium particles to the cation-doped metal particles is greater than 9:1.

[0011] Furthermore, in step S1, the cation-doped metal M particles are one of chromium, molybdenum and tungsten.

[0012] Furthermore, in step S2, the main components of the intermediate material satisfy M x V 1-x O y N 1-y , wherein M is a cation doping metal element, V is a vanadium element, O is an oxygen element, N is a nitrogen element, x satisfies 0<x≤0.3, and y satisfies 0<y≤0.1.

[0013] Furthermore, in step S2, the reactive sputtering temperature is 30-200° C. and the time is 10-60 min.

[0014] Furthermore, in step S2, the inert gas is argon, and the nitrogen oxide is nitric oxide.

[0015] Furthermore, in step S2, the flow ratio of argon gas to nitric oxide is 10:(0.8-1.2).

[0016] Furthermore, in step S3, the annealing heat treatment temperature is 300-400° C. and the time is 10-60 min.

[0017] In addition, the present invention also provides an anion-cation co-doped thermosensitive material, which is prepared by the above-mentioned method for preparing anion-cation co-doped thermosensitive material.

[0018] The present invention also provides a microbolometer, comprising a thermosensitive film, wherein the thermosensitive film is the above-mentioned anion-cation co-doped thermosensitive material.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention changes the activation energy of the thermosensitive material through cation doping, improves its resistance temperature coefficient, enhances the thermoelectric conversion capability of the thermosensitive material, and improves the response rate of the microbolometer. At the same time, anion doping is used to compensate for the disturbance that may be caused by the excess electrons brought by cation doping, thereby reducing the 1 / f noise of the thermosensitive material and optimizing the NETD (noise equivalent temperature difference) of the microbolometer.

[0021] The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1It is a flow chart of the preparation method of the anion-cation co-doped thermosensitive material of the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] This embodiment provides a thermosensitive material co-doped with an anion and a cation, and a method for preparing the thermosensitive material co-doped with an anion and a cation. Figure 1 As shown, the specific steps include:

[0025] S1. Melt and forge metal vanadium particles and cation-doped metal M particles at high temperature to obtain an alloy target.

[0026] The cation-doped metal M particles may be any one of pure metal chromium (Cr), molybdenum (Mo), and tungsten (W) particles, and the purity of the metal vanadium particles and the cation-doped metal M particles is not less than 99%.

[0027] During the high-temperature melt forging process, the mass ratio of metal vanadium particles to cation-doped metal particles is greater than 9:1. Preferably, the mass percentage of metal vanadium particles is 90-100wt%, and the mass percentage of cation-doped metal particles is 0-10wt%. The cation-doped metal M is used as a cation doping material source. The vanadium oxide material obtained by doping with special metals can change the activation energy Ea, thereby increasing the TCR of the obtained thermosensitive material.

[0028] Specifically, the high temperature melt forging process is to melt, pour, mold, ingot, powder, shape, high temperature, and sinter the metal vanadium particles and the cation-doped metal M particles according to the designed ratio to obtain the alloy target material, wherein the melting, pouring, mold, ingot, powder, shaping, high temperature, and sintering processes are all prior art, and the specific process is not repeated here. Among them, the high temperature melt forging temperature is greater than the melting point of the metal vanadium and the cation-doped metal M to ensure that the metal vanadium particles and the cation-doped metal M particles are fully melted and mixed evenly.

[0029] S2. Install the alloy target material at the target position of the physical vapor deposition chamber, and transfer the substrate on which the heat-sensitive material is to be deposited into the vacuum chamber, and perform reactive sputtering in a mixed atmosphere of an inert gas and nitrogen oxides to obtain an intermediate material.

[0030] Specifically, the reactive sputtering temperature is 30-200°C and the time is 10-60min. During this process, the inert gas is dissociated and then bombards the alloy target under the action of a high-energy electric field to obtain a high-energy plasma containing both the matrix element and the cationic doping element M. Specifically, the inert gas can be but is not limited to argon, helium, neon, etc., preferably argon; nitrogen oxide is used as a reaction gas, which has both oxidation and N doping functions, and reacts with the high-energy plasma to obtain an intermediate material.

[0031] In this embodiment, nitrogen oxide is used as the anion doping material source because nitrogen atoms are close in size to oxygen atoms and their atomic nuclei are smaller in size and have stronger electron binding ability. When nitrogen atoms partially replace oxygen atoms to combine with cations, they can form a more stable valence bond with them. At the same time, they will form acceptor energy levels that can provide holes, which will offset the donor energy levels that can provide electrons, forming a compensation effect, avoiding excessive carrier emission and capture during device operation to form disturbances and thus making it impossible to reduce 1 / f noise, and the electrical properties of the thermosensitive material can be adjusted and optimized by designing the concentrations of the two.

[0032] Experiments have shown that among nitrogen oxides used as anion doping material sources, nitric oxide is more likely to dissociate into plasma under high pressure and then participate in thin film deposition than other nitrogen oxides. If other nitrogen oxides are used, the effect of N entering the film will be compromised, or more energy will be required to dissociate. Therefore, in this embodiment, nitric oxide is preferably nitric oxide.

[0033] Optionally, when argon is used as the inert gas and nitric oxide is used as nitric oxide for reactive sputtering, the flow ratio of argon to nitric oxide is 10:(0.8-1.2). For different doping contents, the flow ratio of the gas can be adjusted according to demand.

[0034] After this reactive sputtering process, the main components of the intermediate material obtained meet M x V 1-x O y N 1-y , where M is a cation doping metal element, V is a vanadium element, O is an oxygen element, and N is a nitrogen element. The values ​​of x and y depend on the degree of incorporation of the doping element into the matrix film. If the limit is exceeded, segregation may occur, resulting in a mixed film with different components in different regions. On the other hand, it depends on the performance effect obtained after the incorporation ratio. In this embodiment, x satisfies 0<x≤0.3, and y satisfies 0<y≤0.1.

[0035] S3. In a nitrogen oxide-containing atmosphere, the intermediate material is subjected to annealing heat treatment to obtain an anion-cation co-doped thermosensitive material.

[0036] Specifically, the annealing heat treatment temperature is 300-400°C and the time is 10-60 minutes. Under this high temperature condition, the nitrogen-containing oxide is used as the atmosphere to timely replenish the oxygen or nitrogen element overflowing from the intermediate material at high temperature. In this embodiment, the nitrogen-containing oxide is preferably nitric oxide.

[0037] The thermosensitive material prepared by the above method has a higher TCR because the activation energy Ea is changed by doping special metals. At the same time, the compensation effect of anions ensures the stability of carrier concentration and transmission under the working state of the device, thereby reducing 1 / f noise. At the same time, the square resistance of the thermosensitive material can be adjusted by adjusting the ratio of different types of doping elements (i.e., anion and cation doping).

[0038] In this embodiment, the anion-cation co-doped thermosensitive material is specifically an anion-cation co-doped thermosensitive film.

[0039] In addition, the present embodiment further provides a microbolometer, including a thermosensitive film, wherein the thermosensitive film is the above-mentioned anion-cation co-doped thermosensitive material. Since the thermosensitive film used in the microbolometer of the present embodiment has a high temperature coefficient of resistance, good thermal stability, and low 1 / f noise, it is beneficial for the microbolometer to distinguish tiny signals and can be applied to wafer-level or pixel-level packaging.

[0040] In summary, the anion-cation co-doped thermosensitive material provided by the present invention changes the activation energy of the thermosensitive material through cation doping, improves its resistance temperature coefficient, enhances the thermoelectric conversion capability of the thermosensitive material, and improves the response rate of the microbolometer. At the same time, anion doping compensates for the disturbance that may be caused by the excess electrons brought by cation doping, reduces the 1 / f noise of the thermosensitive material, and optimizes the NETD of the microbolometer.

[0041] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing anion-cation co-doped thermosensitive material, characterized in that: The steps include: S1, melting and forging metal vanadium particles and cation-doped metal M particles to obtain an alloy target; S2, subjecting the alloy target to reactive sputtering in a mixed atmosphere of an inert gas and nitrogen oxides to obtain an intermediate material; S3. In a nitrogen oxide-containing atmosphere, the intermediate material is subjected to annealing heat treatment to obtain an anion-cation co-doped thermosensitive material.

2. The method for preparing anion-cation co-doped thermosensitive material according to claim 1, characterized in that: In the step S1, the mass ratio of the metal vanadium particles to the cation-doped metal particles is greater than 9:

1.

3. The method for preparing the anion-cation co-doped thermosensitive material according to claim 1, characterized in that: In the step S1, the cation-doped metal M particles are one of chromium, molybdenum and tungsten.

4. The method for preparing the anion-cation co-doped thermosensitive material according to claim 3, characterized in that: In step S2, the main components of the intermediate material satisfy M x V 1-x O y N 1-y , wherein M is a cation doping metal element, V is a vanadium element, O is an oxygen element, N is a nitrogen element, x satisfies 0<x≤0.3, and y satisfies 0<y≤0.

1.

5. The method for preparing anion-cation co-doped thermosensitive material according to claim 1, characterized in that: In the step S2, the reactive sputtering temperature is 30-200° C. and the time is 10-60 min.

6. The method for preparing anion-cation co-doped thermosensitive material according to claim 1, characterized in that: In the step S2, the inert gas is argon, and the nitrogen oxide is nitric oxide.

7. The method for preparing anion-cation co-doped thermosensitive material according to claim 6, characterized in that: In step S2, the flow ratio of argon gas to nitric oxide is 10:(0.8-1.2).

8. The method for preparing anion-cation co-doped thermosensitive material according to claim 1, characterized in that: In step S3, the annealing heat treatment temperature is 300-400° C. and the time is 10-60 min.

9. An anion-cation co-doped thermosensitive material, characterized in that: The method is prepared according to any one of claims 1 to 8.

10. A microbolometer, characterized in that: It comprises a thermosensitive film, and the thermosensitive film is the anion-cation co-doped thermosensitive material according to claim 9.

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