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Minitype capacitance type gas sensor and preparation method thereof

A technology of gas sensor and microcapacitance, which is applied in fluid pressure measurement, ion implantation plating, coating and other directions using capacitance changes, and can solve the problems of small adsorption area, unfavorable gas contact, long response time, etc.

Inactive Publication Date: 2010-09-08
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The gas to be measured enters the sensor through the pores on the upper electrode plate and is fully adsorbed by the medium-sensitive material, which takes a long time, so the response time of the entire capacitive gas sensor is long, such as the response time to DMMP t 90 Up to 138s, which has a great impact on applications that require fast detection and response, such as the detection of explosive gases and poisonous gases
Moreover, due to the limited area of ​​the pores, the adsorption area exposed by the dielectric film is very small, which is not conducive to full contact with the gas.

Method used

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  • Minitype capacitance type gas sensor and preparation method thereof
  • Minitype capacitance type gas sensor and preparation method thereof
  • Minitype capacitance type gas sensor and preparation method thereof

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preparation example Construction

[0038] The preparation method includes the following steps:

[0039] ①Prepare the bottom electrode film on the silicon substrate and pattern it to form the bottom electrode plate;

[0040] ②Silicon nitride or silicon oxynitride film is prepared on the bottom electrode plate by chemical vapor deposition method, and the film is etched to form pillars. The shape of the pillars at the peripheral edges may be inconsistent with the pillars at the center, and the size may also be larger than that at the center;

[0041] ③The thickness of spin-coated glass is consistent with the height of the pillar;

[0042] ④Prepare doped polysilicon on the sacrificial glass layer by chemical vapor deposition as the upper electrode plate to form a plate capacitor;

[0043] ⑤Use HF acid to remove the sacrificial glass layer, release the cavity structure, and form a flat capacitor with a cavity structure;

[0044] ⑥The dipping method is adopted to coat the dielectric film on the support of the flat capacitor wit...

Embodiment 1

[0049] Such as image 3 As shown, the shape of the sensor is circular and the pillar is square. The gas sensor of this structure includes a lower electrode plate 2, an upper electrode plate 3, a pillar 7, a dielectric sensitive film 4, an air hole 5 arranged on the side wall, and a side wall 6 with openings. A metal aluminum film with a thickness of 500 nm is deposited on the silicon substrate 1 through an evaporation process, and the film is patterned by photolithography to form a circle with a diameter of 1 mm as the bottom electrode plate 2 of the flat capacitor. The sidewalls 6 and pillars 7 are made of silicon nitride, and the film thickness is 2um. They are prepared by a plasma enhanced chemical vapor deposition (PECVD) process and formed by dry etching image 3 The pattern shown. The side walls 6 are fan-shaped pillars separated from each other with a duty ratio of 1:1. The center angles of the fan-shaped pillars and the air holes 5 are both 4.5°; the inner pillar 7 is a...

Embodiment 2

[0051] The shape of the sensor in this example is round, and the pillar is also round, such as Figure 4 Shown. Compared with Example 1, the lower electrode plate 2, the side walls 6, the dielectric sensitive film 4 and the upper electrode plate 3 of the sensor are the same, except that the dielectric layer pillar 7 is designed to be circular. The circular pillars 7 have a height of 2um, a diameter of 50um, and have a horizontal interval of 150um and a vertical interval of 50um, and they are staggered on the bottom electrode plate 2.

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Abstract

The invention discloses a minitype capacitance type gas sensor, which comprises an upper electrode flat plate, a lower electrode flat plate, a plurality of struts and medium films, wherein the struts are arranged between the upper electrode flat plate and the lower electrode flat plate, so that a cavity is formed between the upper electrode flat plate and the lower electrode flat plate; and the medium films are coated on the struts and the inner surfaces of an upper electrode and a lower electrode. The minitype capacitance type gas sensor is characterized in that: (1) the medium films on adjacent struts are not in contact to each other and a reserved cavity structure forms a gas diffusion channel; and (2) an air hole is not formed on the upper electrode flat plate and side walls between the upper electrode flat plate and the lower electrode flat plate are open, so that gas enters from the side walls. The minitype capacitance type gas sensor can detect various gases to be detected with extremely-low density and has the characteristics of quick response, high sensitivity and wide detection object.

Description

Technical field [0001] The invention relates to the technical field of gas sensors, in particular to a capacitive gas sensor and a preparation method thereof. Background technique [0002] There are many types of gas sensors, and capacitive gas sensors are one of them. It sets a dielectric layer between the positive and negative electrodes, and measures the gas concentration by measuring the capacitance change caused by the absorption of the gas to be measured by the dielectric layer. It has the characteristics of high sensitivity, small size, low noise, and many types of gases to be detected. [0003] American Seacoast Company has done a lot of research on miniature capacitive gas sensors. figure 1 A miniature gas sensor with a flat capacitor structure developed for the company. A cavity is formed between the upper and lower electrode plates through the MEMS process, and then the cavity is filled with a polymer medium. Its characteristic is that the upper electrode plate is provid...

Claims

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Application Information

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IPC IPC(8): G01L9/12C23C14/06
Inventor 杜晓松蒋亚东靖红军
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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