Multi-channel lead zirconate titanate pyroelectric detector and preparation method thereof
By integrating optical metasurface structures in pyroelectric detectors, the problem of lack of spectral selectivity in traditional thermal infrared detectors is solved, and the spectral selectivity and multi-channel functions of the detector are realized, which improves the responsiveness and sensitivity.
Patent Information
- Application Number
- CN202411964335.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2025-04-08
AI Technical Summary
Traditional thermal infrared detectors lack spectral selectivity and rely on discrete filters, resulting in large size, high cost and inability to meet the needs of complex application scenarios.
By integrating an optical metasurface structure in a pyroelectric detector, the metasurface layer is used to form local surface plasmon resonance within a specific frequency range, achieving wavelength selection function, replacing traditional filters.
The spectral selectivity of the detector is realized, the volume and complexity are reduced, the absorption of specific wavelengths or bands is enhanced, the responsiveness of the detector is improved, and the testing of multiple gases in a single scenario can be achieved.
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Figure CN119789758A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of pyroelectric sensing, and in particular relates to a multi-channel lead zirconate titanate pyroelectric detector and a preparation method thereof. Background Art
[0002] Infrared detectors are widely used in daily production and life, and can be applied to military, aviation, control system detection, medical diagnosis and other aspects. Among them, photon detectors need to be cooled to obtain a high signal-to-noise ratio, which increases the size and cost of photon detectors and limits their application scenarios. In contrast, thermal detectors are simple to manufacture, have high stability, can work without refrigeration equipment, and have an extremely wide response band, but traditional thermal infrared detectors lack spectral selectivity and need to rely on discrete filters for narrowband filtering. Therefore, giving the detector a spectral selectivity characteristic is of great significance to breaking through the bottleneck of the integration of traditional thermal infrared detector systems.
[0003] Existing technologies solve the problem of lack of spectral selectivity of thermal infrared detectors mainly through the following methods: Spectrally selective infrared thermal detectors based on artificial microstructures can reduce the thermal conductivity of the detector by using artificial microstructures, suppress unnecessary thermal radiation through the spectrum, and reduce thermal capacitance, thereby improving the performance of thermal detectors. This method can avoid additional filters, achieve spectral selectivity, simplify the manufacturing process and reduce costs.
[0004] MEMS infrared narrowband thermal light sources based on micro-nano structures can improve infrared thermal radiation emission by adding micro-nano structures on the surface of the light source, such as nano-silicon structures, photonic crystals, gratings, and metasurfaces. These structures can enhance the radiation of specific wavelengths by using effects such as surface plasmon resonance and quasi-continuum bound states, thereby providing spectral selectivity.
[0005] Metamaterial absorbers with integrated optical antennas: Metamaterial absorbers based on optical antennas are integrated into detector pixels, which enables mid-infrared detectors to have pixel-level spectral selectivity, i.e., narrowband detection capabilities. Metamaterial absorbers are composed of metal optical antenna arrays that can selectively absorb light of a specific spectrum, acting as absorptive filter units.
[0006] Traditional detectors achieve spectral selection by installing discrete optical elements such as filters on top of the detector, which causes problems such as difficulty in detector assembly, large size and high cost. In addition, most current detectors are single-channel detectors, which can only test a single gas in a single scenario and cannot meet the needs of more complex application scenarios, hindering the further development of detectors. Summary of the invention
[0007] In view of the defects of the prior art, the present invention provides a multi-channel lead zirconate titanate pyroelectric detector and a preparation method thereof, which aims to solve the problem of traditional pyroelectric detectors' dependence on discrete optical elements such as filters and reduce the size and complexity of the detector.
[0008] According to a first aspect of the present invention, a lead zirconate titanate pyroelectric detector is provided, and its specific structure is as follows: from bottom to top, there are a substrate and a detection layer; the substrate has a cavity running through it from top to bottom; the detection layer includes, from bottom to top, a lower electrode, a lead zirconate titanate layer, an upper electrode, a dielectric layer and a supersurface layer; the lead zirconate titanate layer is located in the middle area of the lower electrode, and the edges around the lower electrode are not covered by the lead zirconate titanate layer; the upper electrode is covered on the lead zirconate titanate layer; the middle area of the upper electrode is covered by the dielectric layer, and the edges around the upper electrode are not covered by the dielectric layer; the supersurface layer is covered on the dielectric layer; the orthographic projection of the supersurface layer on the substrate is located in the cavity.
[0009] Preferably, a detection layer is disposed on each cavity; adjacent detection layers are not in contact with each other.
[0010] Preferably, the material of the substrate is silicon;
[0011] Preferably, the material of the dielectric layer is selected from one or more of silicon dioxide, silicon, and germanium;
[0012] Preferably, the material of the super surface layer is selected from gold, silver, aluminum or copper;
[0013] Preferably, the material of the lower electrode is platinum;
[0014] Preferably, the material of the upper electrode is selected from gold, silver, copper or aluminum.
[0015] Preferably, the thickness of the dielectric layer is 10 nm to 10 μm; the thickness of the lead zirconate titanate layer is 0.1 μm to 10 μm; and the thickness of the super surface layer is 10 nm to 10 μm.
[0016] Preferably, the supersurface layer is a periodically arranged electromagnetic antenna array.
[0017] Preferably, the center spacing between adjacent electromagnetic antennas of the electromagnetic antenna array is 10 nm to 15 μm.
[0018] Preferably, the electromagnetic antenna is a disc-shaped antenna or a cross-shaped antenna.
[0019] Preferably, the radius of the disc-shaped antenna is 10 nm to 10 μm; the rod length of the cross-shaped antenna is 10 nm to 10 μm, and the rod width of the cross-shaped antenna is 10 nm to 10 μm.
[0020] According to a first aspect of the present invention, there is provided a method for preparing the lead zirconate titanate pyroelectric detector, comprising the following steps:
[0021] S1. Select a lead zirconate titanate wafer, wherein the lead zirconate titanate wafer consists of three layers, namely, a substrate, a lower electrode, and a lead zirconate titanate layer from bottom to top; and grow a mask layer on the lower surface of the lead zirconate titanate wafer;
[0022] S2, using photolithography and etching processes to etch the edges of the lead zirconate titanate layer to expose the lower electrode and retain the lead zirconate titanate layer in the middle area of the lower electrode;
[0023] S3, growing an upper electrode on the lead zirconate titanate layer by photolithography and electron beam evaporation process;
[0024] S4, growing a dielectric layer on the upper electrode and the exposed lower electrode by a chemical vapor deposition process or an electron beam evaporation process, so that the dielectric layer covers the upper electrode and the exposed lower electrode;
[0025] S5, etching the dielectric layer by photolithography and inductively coupled plasma etching process, leaving only the dielectric layer on the middle area of the upper electrode, and exposing the edges around the upper electrode;
[0026] S6, using photolithography and electron beam evaporation processes to plate a layer of super surface layer metal material on the dielectric layer obtained in step S5, and then using a dissolution stripping process to obtain a super surface layer;
[0027] S7, performing photolithography and etching on the mask layer to expose the substrate, and ensuring that the orthographic projection of the super surface layer on the substrate is located within the exposed substrate;
[0028] S8, etching the substrate leaked out in step S7 to obtain a cavity penetrating from top to bottom on the substrate, thereby obtaining the lead zirconate titanate pyroelectric detector.
[0029] Preferably, in step S1, the material of the mask layer is selected from silicon nitride, silicon oxide, photoresist, gold, chromium, silver, copper, tantalum or aluminum.
[0030] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:
[0031] 1. The present invention integrates an optical metasurface structure with a thermal detector, wherein the optical antenna forms a localized surface plasmon resonance under the excitation of electromagnetic waves. This electromagnetic resonance occurs only within a specific frequency range, thus playing a role in wavelength selection and being functionally equivalent to an optical filter. This solves the problem of traditional pyroelectric detectors' dependence on discrete optical elements such as optical filters, and reduces the size and complexity of the detector. At the same time, the present invention can achieve response to spectra of different bands by adjusting the size and shape of the metasurface layer.
[0032] 2. The present invention arranges a plurality of cavities at intervals, and forms a plurality of cavities in the same chip area in the form of an array arrangement. Different metasurface layer patterns correspond to each cavity, which respond to electromagnetic waves of different frequencies, so that one channel responds to a spectrum, thereby forming a multi-channel detector that responds to different electromagnetic wave frequency domains, and realizing the testing of multiple gases in a single scenario; at the same time, antennas of different structures and sizes can be integrated on the detector at one time, with good consistency and easy batch preparation.
[0033] 3. The present invention adopts a silicon substrate as a cavity structure, which reduces the thermal conduction of the detector, so that the heat converted from electromagnetic radiation acts more on the lead zirconate titanate pyroelectric conversion, while reducing the heat conduction between adjacent channels, so that the detector has better sensitivity and responsiveness; the present invention adopts a lead zirconate titanate layer to absorb electromagnetic radiation in a preset band and convert it into an electrical signal; the upper electrode and the lower electrode of the present invention are used to form an external circuit, detect the pyroelectric current in the circuit and output an electrical signal; the upper electrode of the present invention also has the function of a metal reflective layer.
[0034] 4. The present invention integrates the optical metasurface structure with the thermal detector. The preparation method is simple, the integration is high and the response is rapid. Antennas of different structures and sizes can be integrated into the detector surface at one time to form a multi-channel detector, which reduces the volume and complexity of the detector. At the same time, the absorption of the detector to specific wavelengths or bands is enhanced, thereby improving the technical effect of the detector's responsiveness. BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Figure 1 This is a schematic diagram of the structure of the lead zirconate titanate pyroelectric detector chip of the present invention.
[0036] Figure 2 This is a schematic diagram of the structure of the multi-channel lead zirconate titanate pyroelectric detector chip of the present invention.
[0037] Figure 3 This is a schematic diagram of the cavity backside structure of the multi-channel lead zirconate titanate pyroelectric detector chip substrate of the present invention.
[0038] Figure 4 This is a schematic diagram of the super surface layer of the cross-shaped antenna of the lead zirconate titanate pyroelectric detector chip of the present invention.
[0039] Figure 5 This is the infrared absorption spectrum of Example 1 of the present invention.
[0040] Figure 6 This is the infrared absorption spectrum of Example 2 of the present invention.
[0041] Figure 7 This is the infrared absorption spectrum of Example 3 of the present invention.
[0042] In the figure, 1, substrate; 2, lower electrode; 3, lead zirconate titanate layer; 4, upper electrode; 5, dielectric layer; 6, supersurface layer; 7, cavity. DETAILED DESCRIPTION
[0043] In order to make the purpose, technical solutions 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 intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
[0044] Example 1
[0045] A lead zirconate titanate pyroelectric detector, each structural unit of which comprises a silicon substrate 1, a lower electrode 2, a lead zirconate titanate layer 3, an upper electrode 4, a dielectric layer 5 and a cross-shaped antenna super surface layer 6 arranged from bottom to top. Figure 4 As shown. Among them, the rod length a of the cross gold antenna is 4.3μm, the rod width b is 1μm, the center distance c of adjacent antennas is 4.7μm, and the thickness is 100nm; the thickness of the dielectric layer germanium is 150nm; the thickness of the metal reflective layer is 100nm. Through numerical simulation, the absorption spectrum of the structure in the infrared band is obtained, which is Figure 5 It can be seen that the absorption peak wavelength of this structure is located at 10.35 μm.
[0046] Example 2
[0047] A lead zirconate titanate pyroelectric detector, wherein each structural unit of the lead zirconate titanate pyroelectric detector comprises a silicon substrate 1, a lower electrode 2, a lead zirconate titanate layer 3, an upper electrode 4, a dielectric layer 5 and a cross-shaped antenna super surface layer 6 arranged from bottom to top. Figure 4 As shown. Among them, the rod length a of the cross gold antenna is 3.8μm, the rod width b is 0.9μm, the center distance c of adjacent antennas is 4.6μm, and the thickness is 100nm; the thickness of the dielectric layer germanium is 150nm; the thickness of the metal reflective layer is 100nm. Through numerical simulation, the absorption spectrum of the structure in the infrared band is obtained, which is Figure 6 It can be seen that the absorption peak wavelength of this structure is located at 9.16 μm.
[0048] Example 3
[0049] A lead zirconate titanate pyroelectric detector, wherein each structural unit of the lead zirconate titanate pyroelectric detector comprises a silicon substrate 1, a lower electrode 2, a lead zirconate titanate layer 3, an upper electrode 4, a dielectric layer 5 and a cross-shaped antenna super surface layer 6 arranged from bottom to top. Figure 4 As shown. The length of the cross gold antenna is 4.2μm, the width is 0.9μm, the center distance c between adjacent antennas is 4.8μm, and the thickness is 100nm; the thickness of the dielectric layer germanium is 150nm; the thickness of the metal reflective layer is 100nm. Through numerical simulation, the absorption spectrum of the structure in the infrared band is obtained, which is Figure 7 It can be seen that the absorption peak wavelength of this structure is located at 9.55 μm.
[0050] Example 4
[0051] The preparation method of a lead zirconate titanate pyroelectric detector proposed in this embodiment comprises the following steps:
[0052] S1: Select a lead zirconate titanate wafer, wherein the lead zirconate titanate wafer consists of three layers, a bottom layer is a substrate, a middle layer is a lower electrode, and a top layer is a lead zirconate titanate layer, wherein the lead zirconate titanate layer has a thickness of 2 μm, and grow silicon nitride on the back side using a plasma enhanced chemical vapor deposition process, wherein the silicon nitride has a thickness of 500 nm, to obtain a first semi-finished product;
[0053] S2: performing photolithography on the front side of the first semi-finished product, and then etching the upper surface of the lead zirconate titanate wafer using a reactive ion etching process or an inductively coupled plasma etching process to expose the lower electrode platinum, thereby obtaining a second semi-finished product;
[0054] S3: using photolithography and electron beam evaporation processes on the front side of the second semi-finished product, a 100 nm thick gold layer is grown on the lead zirconate titanate layer to obtain a third semi-finished product;
[0055] S4: growing a 150 nm thick germanium layer on the front side of the third semi-finished product by using a plasma enhanced chemical vapor deposition process or an electron beam evaporation process to obtain a fourth semi-finished product;
[0056] S5: etching the front surface of the fourth semi-finished product using photolithography and inductively coupled plasma etching processes to expose the upper electrode gold and the lower electrode platinum, thereby obtaining a fifth semi-finished product;
[0057] S6: using an electron beam exposure process and an electron beam evaporation process on the front side of the fifth semi-finished product to grow a 100 nm thick gold layer to obtain a disk gold antenna, thereby obtaining a sixth semi-finished product;
[0058] S7: performing photolithography and inductively coupled plasma etching on the silicon nitride layer on the back side of the sixth semi-finished product to obtain a wet-etched mask to obtain a seventh semi-finished product;
[0059] S8: wet etching and releasing the silicon substrate on the back side of the seventh semi-finished product, thereby obtaining a lead zirconate titanate pyroelectric detector.
[0060] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is 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 lead zirconate titanate pyroelectric detector, characterized in that: The specific structure is as follows: from bottom to top, a substrate (1) and a detection layer are provided; the substrate (1) has a cavity (7) penetrating from top to bottom; the detection layer comprises, from bottom to top, a lower electrode (2), a lead zirconate titanate layer (3), an upper electrode (4), a dielectric layer (5) and a supersurface layer (6); the lead zirconate titanate layer (3) is located in the middle area of the lower electrode (2), and the edges around the lower electrode (2) are not covered by the lead zirconate titanate layer (3); the lead zirconate titanate layer (3) completely covers the upper electrode (4); the middle area of the upper electrode (4) covers the dielectric layer (5), and the edges around the upper electrode (4) are not covered by the dielectric layer (5); the supersurface layer (6) is covered on the dielectric layer (5); the orthographic projection of the supersurface layer (6) on the substrate (1) is located in the cavity (7).
2. The lead zirconate titanate pyroelectric detector according to claim 1, characterized in that: The substrate (1) is provided with cavities (7) arranged at intervals, and a detection layer is correspondingly arranged on each cavity (7); and adjacent detection layers are not in contact with each other.
3. The lead zirconate titanate pyroelectric detector according to claim 1, characterized in that: The material of the substrate (1) is silicon; The material of the dielectric layer (5) is selected from one or more of silicon dioxide, silicon, and germanium; The material of the super surface layer (6) is selected from gold, silver, aluminum or copper; The material of the lower electrode (2) is platinum; The material of the upper electrode (4) is gold, silver, copper or aluminum.
4. The lead zirconate titanate pyroelectric detector according to claim 1, characterized in that: The thickness of the dielectric layer (5) is 10 nm to 10 μm; the thickness of the lead zirconate titanate layer (3) is 0.1 μm to 10 μm; and the thickness of the super surface layer (6) is 10 nm to 10 μm.
5. The lead zirconate titanate pyroelectric detector according to claim 1, characterized in that: The super surface layer (6) is a periodically arranged electromagnetic antenna array.
6. The lead zirconate titanate pyroelectric detector according to claim 5, characterized in that: The center distance between adjacent electromagnetic antennas of the electromagnetic antenna array is 10 nm to 15 μm.
7. The lead zirconate titanate pyroelectric detector according to claim 6, characterized in that: The electromagnetic antenna is a disk-shaped antenna or a cross-shaped antenna.
8. The lead zirconate titanate pyroelectric detector according to claim 7, characterized in that: The radius of the disc-shaped antenna is 10 nm to 10 μm; the rod length of the cross-shaped antenna is 10 nm to 10 μm, and the rod width of the cross-shaped antenna is 10 nm to 10 μm.
9. The method for preparing a lead zirconate titanate pyroelectric detector according to any one of claims 1 to 8, characterized in that: The steps include: S1. Select a lead zirconate titanate wafer, wherein the lead zirconate titanate wafer consists of three layers, namely, a substrate, a lower electrode, and a lead zirconate titanate layer from bottom to top; and grow a mask layer on the lower surface of the lead zirconate titanate wafer; S2, using photolithography and etching processes to etch the edges of the lead zirconate titanate layer to expose the lower electrode and retain the lead zirconate titanate layer in the middle area of the lower electrode; S3, growing an upper electrode on the lead zirconate titanate layer by photolithography and electron beam evaporation process; S4, growing a dielectric layer on the upper electrode and the exposed lower electrode by a chemical vapor deposition process or an electron beam evaporation process, so that the dielectric layer covers the upper electrode and the exposed lower electrode; S5, etching the dielectric layer by photolithography and inductively coupled plasma etching process, leaving only the dielectric layer on the middle area of the upper electrode, and exposing the edges around the upper electrode; S6, using photolithography and electron beam evaporation processes to plate a layer of super surface layer metal material on the dielectric layer obtained in step S5, and then using a dissolution stripping process to obtain a super surface layer; S7, performing photolithography and etching on the mask layer to expose the substrate, and ensuring that the orthographic projection of the super surface layer on the substrate is located within the exposed substrate; S8, etching the substrate leaked out in step S7 to obtain a cavity penetrating from top to bottom on the substrate, thereby obtaining the lead zirconate titanate pyroelectric detector.
10. The method for preparing a lead zirconate titanate pyroelectric detector according to claim 9, characterized in that: In step S1, the material of the mask layer is selected from silicon nitride, silicon oxide, photoresist, gold, chromium, silver, copper, tantalum or aluminum.