Preparation method of transition metal oxide film and metal-dielectric layer-metal structure compounded infrared temperature detector

Abstract

The invention discloses a preparation method of a transition metal oxide thin film and metal-dielectric layer-metal structure composite infrared temperature detector, which comprises the steps of preparation of a transition metal oxide thin film, preparation of an interdigital electrode, preparation of a dielectric layer and preparation of a metal array layer, wherein the metal array structure is prepared on the surface of the dielectric layer in a way of combining photoetching with magnetron sputtering, and is used as a second metal layer of the metal-dielectric layer-metal infrared absorption structure. According to the infrared temperature detector obtained through the method, the transition metal oxide thin film and the metal-dielectric layer-metal structure are compounded, the transition metal oxide thin film serves as a temperature sensing and measuring layer of the detector, and the metal-dielectric layer-metal structure serves as an infrared response layer. The prepared infrared temperature detector has high black body infrared response rate. The method is low in process difficulty and controllable in cost. The existing process problems are solved.

Description

Technical Field

[0001] The invention relates to the field of preparation of semiconductor films and devices, and in particular to a method for preparing a transition metal oxide film and a metal-dielectric-metal (MIM) infrared temperature detector. Background Art

[0002] The absorption layer material of the infrared temperature detection device absorbs the radiated infrared energy, converts it into heat and transmits it to the temperature sensitive material layer, finally realizing infrared temperature measurement. Commonly used temperature sensitive materials include thermopile type, mainly polycrystalline silicon material; pyroelectric type, such as lithium borate, lithium niobate, lithium tantalate, barium strontium titanate, etc.; thermistor type, such as vanadium oxide (VOx), amorphous silicon (a-Si), etc. Among the above materials, polycrystalline silicon material has low mechanical strength; lithium borate and vanadium oxide are harmful to the human body, and the process will inevitably cause harm to the human body and the environment; lithium niobate, lithium tantalate, etc. are difficult to prepare and have high costs; amorphous silicon infrared temperature detectors have temperature drift and life problems, which affect their use. Spinel transition metal oxides, such as Mn-Co-Ni-O and other multi-metal oxides, are excellent negative temperature coefficient (NTC) temperature sensing and temperature measurement materials in the field of temperature measurement. They have high resistance temperature coefficient (T chromium), excellent temperature measurement sensitivity and stability, and good compatibility with silicon-based processes, and are expected to be used in the field of infrared temperature detection.

[0003] Commonly used absorption layer materials such as mercury cadmium telluride (HgCdTe) and indium antimonide (InSb) have high infrared absorption rates, and the preparation process is difficult and expensive, making them unsuitable for mass production. In addition, the infrared absorption of the device can be improved through structural design, such as metal-dielectric-metal (MIM) structure, etc. However, the current research on MIM structure is mostly carried out through theoretical simulation calculations, and the preparation process is still a technical difficulty. With the gradual maturity of micro-nano processing technology, the composite of MIM structure and NTC thermistor material has unique advantages, such as good compatibility with silicon-based processes, good stability, human / environmental friendliness, low process difficulty, low cost, etc., and it will have important application prospects for the preparation of infrared temperature detectors. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing an infrared temperature detector composited with a transition metal oxide film and a metal-dielectric layer-metal structure, the method comprising the steps of preparing a transition metal oxide film, preparing an interdigital electrode, preparing a dielectric layer and completing a metal array layer, wherein the metal array structure is prepared on the surface of the dielectric layer by photolithography combined with magnetron sputtering, and is used as the second metal layer of the metal-dielectric layer-metal infrared absorption structure. The infrared temperature detector obtained by the method described in the present invention realizes the composite of a transition metal oxide negative temperature coefficient (NTC) film and a MIM structure, the transition metal oxide NTC film is used as the temperature sensing and measuring layer of the detector, and the metal-dielectric layer-metal structure is used as the infrared response layer, and the prepared infrared temperature detector obtains a high black body infrared response rate. The present invention solves the existing process problems and has controllable costs.

[0005] The method for preparing an infrared temperature detector composited with a transition metal oxide film and a metal-dielectric layer-metal structure described in the present invention is carried out according to the following steps:

[0006] Preparation of transition metal oxide thin films:

[0007] a. First, a silicon-based substrate oxide silicon wafer, a silicon carbide wafer or a silicon nitride wafer is placed in acetone, anhydrous ethanol and deionized water for ultrasonic cleaning for 15 minutes respectively, and then the silicon-based substrate is purged with high-purity nitrogen to dry it, and then an oxygen plasma power of 10-150W is used for 1-20 minutes to remove organic residues on the surface of the silicon-based substrate, and spinel La-Mn-O, La-Zr-O, Mn-Co-Ni-O, Mn-Co-Fe-Zn-O or Mn-Co-Fe-Ni-O multi-transition metal oxide is deposited on the silicon-based substrate by a magnetron sputtering method, with a thickness of 0.1-1μm, and then high-temperature annealing is performed, the annealing temperature is 750℃, the annealing time is 30 minutes, and the annealing atmosphere is oxygen or air, wherein the surface roughness of the silicon-based substrate is ≤1nm, and the grain size is <100nm;

[0008] Preparation of interdigitated electrodes:

[0009] b. Arranging interdigital electrodes of one or two layers of gold, silver, copper, platinum, chromium on the surface of the transition metal oxide film in step a by photolithography combined with magnetron sputtering, wherein the interdigital electrodes have a line width and line spacing of 2-100 μm and a film thickness of 0.01-1 μm;

[0010] Preparation of dielectric layer:

[0011] c. Depositing Si3N4, SiO2, Al2O3, and AlN layers as dielectric layers on the surface of the electrode layer in step b by chemical vapor deposition, with a thickness of 0.1-1 μm, and patterning the dielectric layer by a two-step process of photolithography-etching to expose the welding points of the electrode layer, wherein the etching is reactive ion etching or inductively coupled plasma etching;

[0012] Preparation of metal array layer:

[0013] d. Prepare a metal titanium, chromium, gold, silver or platinum array on the surface of the dielectric layer in step c by photolithography combined with magnetron sputtering. The structure shape is circular, square, ring or cross structure, the size is 0.1-10μm, the period is 0.1-20μm, and the thickness is 0.01-1μm, so as to obtain an infrared temperature detector composed of a transition metal oxide film and a metal-dielectric layer-metal structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a process flow chart of the present invention;

[0015] Figure 2 This is a SEM picture of the detection device prepared in Example 1 of the present invention, wherein a is the top view and b is the cross-sectional view;

[0016] Figure 3 The electrical performance curve of the detection device prepared in Example 1 of the present invention, wherein a is a current-voltage curve, and b is a resistance-temperature (RT) curve and a temperature coefficient of resistance (TCR) curve;

[0017] Figure 4 The blackbody infrared detection rate and response time spectrum of the infrared temperature detection devices prepared in Example 1 of the present invention and Comparative Example 6 in the 8-14 μm band. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0019] Example 1

[0020] Preparation of transition metal oxide thin films:

[0021] a. First, the silicon oxide substrate was placed in acetone, anhydrous ethanol and deionized water for ultrasonic cleaning for 15 minutes respectively, and then the silicon wafer was purged with high-purity nitrogen to make it dry. Subsequently, the organic residue on the surface of the substrate was removed by oxygen plasma with a power of 10W for 1 minute, and spinel Mn-Co-Fe-Zn-O transition metal oxide was deposited on the substrate by magnetron sputtering with a thickness of 0.2μm. Then, high-temperature annealing was performed at a temperature of 750℃ for 30 minutes in an oxygen atmosphere.

[0022] Preparation of interdigitated electrodes:

[0023] b. Arranging the interdigital electrodes on the surface of the Mn-Co-Fe-Zn-O transition metal oxide film in step a by photolithography combined with magnetron sputtering is a platinum electrode, the interdigital electrode line width and line spacing are 10 μm, and the film thickness is 0.1 μm;

[0024] Preparation of dielectric layer:

[0025] c. Depositing a Si3N4 layer as a dielectric layer on the surface of the platinum electrode layer in step b by chemical vapor deposition, with a thickness of 500 nm, and patterning the dielectric layer by photolithography-etching to expose the welding points of the electrode layer;

[0026] Preparation of metal array layer:

[0027] d. Prepare a metal titanium array on the surface of the Si3N4 dielectric layer in step c by photolithography combined with magnetron sputtering. The structure is a square structure with a size of 0.1 μm, a period of 0.1 μm, and a thickness of 300 nm, thereby obtaining an infrared temperature detector composed of a transition metal oxide film and a metal-dielectric layer-metal structure.

[0028] An infrared temperature detector with a titanium array structure on the surface is prepared. Figure 2 The SEM test results show that the electrical properties are Figure 3 As shown, the infrared detection performance is as follows Figure 4 shown.

[0029] Example 2

[0030] Preparation of transition metal oxide thin films:

[0031] a. First, the silicon carbide wafer substrate was placed in acetone, anhydrous ethanol and deionized water for ultrasonic cleaning for 15 minutes respectively, and then the silicon-based substrate was purged with high-purity nitrogen to make it dry. Subsequently, the organic residue on the surface of the substrate was removed by oxygen plasma with a power of 100W for 15 minutes, and spinel La-Mn-O transition metal oxide was deposited on the substrate by magnetron sputtering with a thickness of 1μm, and then high-temperature annealing was performed at a temperature of 750℃ for 30 minutes in an oxygen atmosphere;

[0032] Preparation of interdigitated electrodes:

[0033] b. Arranging the interdigital electrodes as platinum electrodes on the surface of the La-Mn-O transition metal oxide film in step a by photolithography combined with magnetron sputtering, with the interdigital electrode line width and line spacing being 50 μm and the film thickness being 1 μm;

[0034] Preparation of dielectric layer:

[0035] c. Depositing an AlN layer as a dielectric layer on the surface of the platinum electrode layer in step b by chemical vapor deposition, with a thickness of 500 nm, and patterning the dielectric layer by photolithography-etching to expose the welding points of the electrode layer;

[0036] Preparation of metal array layer:

[0037] d. Prepare a metal silver array on the surface of the AlN dielectric layer in step c by photolithography combined with magnetron sputtering. The structure is a cross structure with a size of 10 μm, a period of 20 μm, and a thickness of 300 nm. It is an infrared temperature detector composed of a transition metal oxide film and a metal-dielectric layer-metal structure.

[0038] Example 3

[0039] Preparation of transition metal oxide thin films:

[0040] a. First, the silicon nitride wafer substrate is placed in acetone, anhydrous ethanol and deionized water for ultrasonic cleaning for 15 minutes respectively, and then the silicon-based substrate is purged with high-purity nitrogen to make it dry. Subsequently, the organic residue on the surface of the substrate is removed by oxygen plasma with a power of 150W for 20 minutes, and spinel La-Zr-O transition metal oxide is deposited on the substrate by magnetron sputtering with a thickness of 0.1μm. Then, high-temperature annealing is performed at a temperature of 750℃ for 30 minutes in an oxygen atmosphere;

[0041] Preparation of interdigitated electrodes:

[0042] b. Arranging the interdigital electrodes as chromium / gold stacks on the surface of the La-Zr-O transition metal oxide film in step a by photolithography combined with magnetron sputtering, with the interdigital electrode line width and line spacing being 100 μm and the film thickness being 1 μm;

[0043] Preparation of dielectric layer:

[0044] c. Depositing a Si3N4 layer as a dielectric layer on the surface of the chromium / gold stacked electrode layer in step b by chemical vapor deposition, with a thickness of 500 nm, and patterning the dielectric layer by photolithography-etching to expose the welding points of the electrode layer;

[0045] Preparation of metal array layer:

[0046] d. Prepare a metal platinum array on the surface of the Si3N4 dielectric layer in step c by photolithography combined with magnetron sputtering. The structure is square in shape, 10 μm in size, 20 μm in period, and 300 nm in thickness, thus obtaining an infrared temperature detector composed of a transition metal oxide film and a metal-dielectric layer-metal structure.

[0047] Example 4

[0048] Preparation of transition metal oxide thin films:

[0049] a. First, the oxidized silicon wafer was placed in acetone, anhydrous ethanol and deionized water for ultrasonic cleaning for 15 minutes respectively, and then the silicon-based substrate was purged with high-purity nitrogen to make it dry. Subsequently, the organic residue on the surface of the substrate was removed by oxygen plasma with a power of 120W for 6 minutes, and spinel Mn-Co-Ni-O multi-element transition metal oxide was deposited on the substrate by magnetron sputtering with a thickness of 0.5μm. Then, high-temperature annealing was performed at a temperature of 750℃ for 30 minutes in an oxygen atmosphere.

[0050] Preparation of interdigitated electrodes:

[0051] b. Arranging the interdigital electrodes of gold on the surface of the Mn-Co-Ni-O transition metal oxide film in step a by photolithography combined with magnetron sputtering, with the interdigital electrode line width and line spacing of 5 μm and the film thickness of 0.5 μm;

[0052] Preparation of dielectric layer:

[0053] c. Depositing a SiO2 layer as a dielectric layer on the surface of the gold electrode layer in step b by chemical vapor deposition, with a thickness of 500 nm, and patterning the dielectric layer by photolithography-etching to expose the welding points of the electrode layer;

[0054] Preparation of metal array layer:

[0055] d. Prepare a metal titanium array on the surface of the SiO2 dielectric layer in step c by photolithography combined with magnetron sputtering. The structure is a circular structure with a size of 0.5 μm, a period of 5 μm, and a thickness of 300 nm, thereby obtaining an infrared temperature detector composed of a transition metal oxide film and a metal-dielectric layer-metal structure.

[0056] Example 5

[0057] Preparation of transition metal oxide thin films:

[0058] a. First, the silicon nitride wafer was placed in acetone, anhydrous ethanol and deionized water for ultrasonic cleaning for 15 minutes respectively, and then the silicon-based substrate was purged with high-purity nitrogen to make it dry. Subsequently, the organic residue on the surface of the substrate was removed by oxygen plasma with a power of 90W for 12 minutes, and spinel Mn-Co-Fe-Ni-O multi-element transition metal oxide was deposited on the substrate by magnetron sputtering with a thickness of 0.5μm. Then, high-temperature annealing was performed at a temperature of 750℃ for 30 minutes in air atmosphere.

[0059] Preparation of interdigitated electrodes:

[0060] b. Arranging copper interdigital electrodes on the surface of the Mn-Co-Fe-Ni-O transition metal oxide film in step a by photolithography combined with magnetron sputtering, with the interdigital electrode line width and line spacing being 40 μm and the film thickness being 0.2 μm;

[0061] Preparation of dielectric layer:

[0062] c. Depositing an Al2O3 layer as a dielectric layer on the surface of the copper electrode layer in step b by chemical vapor deposition, with a thickness of 500 nm, and patterning the dielectric layer by photolithography-etching to expose the welding points of the electrode layer;

[0063] Preparation of metal array layer:

[0064] d. Prepare a metal chromium array on the surface of the Al2O3 dielectric layer in step c by photolithography combined with magnetron sputtering. The structure is a square structure with a size of 10 μm, a period of 20 μm, and a thickness of 300 nm, thereby obtaining an infrared temperature detector composed of a transition metal oxide film and a metal-dielectric layer-metal structure.

[0065] Example 6

[0066] Comparative Example 1

[0067] Preparation of transition metal oxide thin films:

[0068] a. First, the silicon oxide substrate was placed in acetone, anhydrous ethanol and deionized water for ultrasonic cleaning for 15 minutes respectively, and then the silicon wafer was purged with high-purity nitrogen to make it dry. Subsequently, the organic residue on the surface of the substrate was removed by oxygen plasma with a power of 10W for 1 minute, and spinel Mn-Co-Fe-Zn-O transition metal oxide was deposited on the substrate by magnetron sputtering with a thickness of 0.2μm. Then, high-temperature annealing was performed at a temperature of 750℃ for 30 minutes in an oxygen atmosphere.

[0069] Preparation of interdigitated electrodes:

[0070] b. Arranging the interdigital electrodes on the surface of the Mn-Co-Fe-Zn-O transition metal oxide film in step a by photolithography combined with magnetron sputtering is a platinum electrode, the interdigital electrode line width and line spacing are 10 μm, and the film thickness is 0.1 μm;

[0071] Preparation of dielectric layer:

[0072] c. A Si3N4 layer is deposited on the surface of the platinum electrode layer in step b by chemical vapor deposition method, with a thickness of 500 nm. The dielectric layer is patterned by photolithography-etching to expose the welding points of the electrode layer, thereby obtaining a transition metal oxide thin film infrared temperature detector with no titanium array structure on the surface.

[0073] Example 7

[0074] Characterization Test 1

[0075] Any infrared temperature detector prepared in Examples 1-5 was tested for electrical performance. Figure 3 As shown in the figure, the IV linearity of the Mn-Co-Fe-Zn-O material is excellent and the ohmic contact is good. As the temperature increases, the device resistance decreases exponentially, showing a good negative temperature coefficient (NTC) characteristic. In addition, its resistance temperature coefficient |T Cr | at 300K is as high as 4.04% K. -1 , has good temperature sensitivity;

[0076] Characterization Test 2

[0077] Any infrared temperature detector prepared in Examples 1-5 is subjected to a blackbody infrared response rate test: Figure 4 It can be seen that the blackbody response rate of the detector unit with the titanium array structure at a modulation frequency of 1-10Hz is significantly improved compared with that of the detector unit without the titanium array structure in Example 6, reflecting the enhancement of the photothermal conversion efficiency of the overall device by the metal-dielectric layer-metal (MIM) structure; among them, the blackbody response rate of the metal-dielectric layer-metal (MIM) structure infrared detector reached 67.9V / W at a frequency of 5Hz; on the other hand, the response time of the two infrared detectors was about 52ms, and the titanium array structure did not cause any loss in the response speed of the device.

[0078] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an infrared temperature detector composed of a transition metal oxide film and a metal-dielectric layer-metal structure, characterized in that Follow these steps: Preparation of transition metal oxide thin films: a. First, a silicon-based substrate oxide silicon wafer, a silicon carbide wafer or a silicon nitride wafer is placed in acetone, anhydrous ethanol and deionized water for ultrasonic cleaning for 15 minutes respectively, and then the silicon-based substrate is purged with high-purity nitrogen to dry it, and then an oxygen plasma power of 10-150 W is used for 1-20 minutes to remove organic residues on the surface of the silicon-based substrate, and spinel La-Mn-O, La-Zr-O, Mn-Co-Ni-O, Mn-Co-Fe-Zn-O or Mn-Co-Fe-Ni-O multi-transition metal oxides are deposited on the silicon-based substrate by magnetron sputtering method, with a thickness of 0.1-1μm, and then high-temperature annealing is performed, the annealing temperature is 750℃, the annealing time is 30 minutes, and the annealing atmosphere is oxygen or air, wherein the surface roughness of the silicon-based substrate is ≤1 nm, and the grain size is <100 nm; Preparation of interdigitated electrodes: b. Arranging interdigital electrodes of one or two layers of gold, silver, copper, platinum, chromium on the surface of the transition metal oxide film in step a by photolithography combined with magnetron sputtering, wherein the interdigital electrodes have a line width and line spacing of 2-100 μm and a film thickness of 0.01-1 μm; Preparation of dielectric layer: c. Depositing Si3N4, SiO2, Al2O3, and AlN layers as dielectric layers on the surface of the electrode layer in step b by chemical vapor deposition, with a thickness of 0.1-1 μm, and patterning the dielectric layer by a two-step process of photolithography-etching to expose the welding points of the electrode layer, wherein the etching is reactive ion etching or inductively coupled plasma etching; Preparation of metal array layer: d. Prepare a metal titanium, chromium, gold, silver or platinum array on the surface of the dielectric layer in step c by photolithography combined with magnetron sputtering. The structure shape is circular, square, ring or cross structure, the size is 0.1-10μm, the period is 0.1-20μm, and the thickness is 0.01-1μm, so as to obtain an infrared temperature detector composed of a transition metal oxide film and a metal-dielectric layer-metal structure.

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