CN203259470U - Monolithic integrated miniature infrared gas sensor - Google Patents

Abstract

The utility model provides a miniature infrared gas sensor of monolithic integrated form, include: the upper substrate with the pits and the lower substrate with the pits are combined together, and a hollow air chamber is formed in the middle; an infrared light source is arranged at the concave position of the upper substrate concave pit, the side wall of the upper substrate concave pit is provided with opposite inclined planes, and a reflecting micro mirror is arranged on the opposite inclined planes; one or more grating structures and infrared detectors with the same number as the grating structures are distributed in the concave parts of the lower substrate pits; the position of the infrared light source on the upper substrate, the position of the grating structure on the lower substrate and the distribution position of the infrared detector are matched with the position and the inclination angle of the reflecting micromirror on the inclined plane of the pit of the upper substrate, so that infrared light emitted by the infrared light source is split by the grating structure, narrow-band infrared light in a wave band corresponding to the characteristic infrared absorption peak of the gas to be detected is emitted to the reflecting micromirror, and is reflected by the reflecting micromirror and then is accurately emitted to the infrared detector.

Description

Monolithic integrated miniature infrared gas sensor

technical field

The utility model relates to a sensor, in particular to an infrared gas sensor.

Background technique

With the acceleration of industrialization and the development of the Internet of Things industry, the development of intelligent environmental monitoring systems has become one of the current research hotspots, and gas detectors are the core part of the system. Therefore, it is necessary to develop high-performance and highly integrated gas detectors. become the current top priority. Regarding modular integrated gas detectors, some research institutions have done related research and produced prototype prototypes. For example, in 2008, North University of China designed an absorption spectrum gas infrared sensor and proposed a Device-level integrated design solutions. The infrared dual-path sensitive element and filter are made into a detector head by using MEMS technology, and then the detector head, infrared light source and filter are integrated in the air chamber through micro-encapsulation and micro-integration technology. Cranfield University in the United Kingdom integrates infrared thermal radiation source, narrow-band filter, and pyroelectric sensor into a cylindrical shell, and performs special optical design and treatment on the shell wall to allow more infrared radiation to reach the window of the infrared detector , which greatly improved the sensitivity of the device (up to 3500V/W), and produced a low-cost and high-efficiency carbon dioxide NDIR sensor. The above two solutions are limited to the modular integration of devices, and do not really solve the various errors caused by the module assembly process, or even the failure of devices. Therefore, it is impossible to achieve high reliability and miniaturization of gas detection micro-sensing structure.

With the further innovation of technology, these independent devices are even integrated on the same substrate, making the device smaller in size and higher in integration. In the article "MEMS technology used in the manufacture of infrared devices", JPL laboratory has successfully developed a micro-mechanical electronic tunnel infrared detector. The detector adopts MEMS (micro-electromechanical system) technology to realize the traditional box-type pneumatic infrared detection principle, and makes a tunnel detection structure to replace the original complex optical detection structure, and processes the gas chamber microcavity on the silicon chip with micro-mechanical methods. Infrared radiation is measured by detecting the deformation of the film due to infrared absorption. The method realizes the integrated design of the MEMS tunnel detector and the gas chamber optical path, and lays a certain foundation for the research of integrated and miniaturized gas detection devices. The Wuhan National Optoelectronics Laboratory successfully integrated the thermal radiation infrared light source and the detection structure on the same substrate, and made an infrared CO2 sensor using the tube-shell gas chamber. The disadvantage of this sensor is that it can only be used to detect CO2 gas, and other sensor systems need to be used to detect other gases, so the integration level is relatively poor. Although the integration of infrared detectors and gas chamber structures, infrared light sources and detectors has been achieved, up to now, there has not been a high degree of integration of infrared detectors, infrared light sources, micromirrors and other MEMS structures into a single chip. Integrated miniature gas sensors have been reported. Therefore, the application prospect of researching and developing this kind of integrated micro-nano structure is very promising.

Contents of the invention

The purpose of this utility model is mainly to break through the traditional modular combination and patchwork, and develop a highly integrated miniature infrared gas sensor. An infrared detector array and a grating structure array are set to realize multi-component gas detection. The technical scheme that the utility model adopts is:

A monolithic integrated miniature infrared gas sensor comprising:

An upper substrate with pits, a lower substrate with pits, and a bonding dummy located between the upper substrate and the lower substrate, the upper substrate, the lower substrate, and the bonding dummy are combined together, and the middle form a hollow air chamber;

An infrared light source is arranged in the recess of the pit on the upper substrate, the side walls of the pit on the upper substrate have opposite slopes, and reflective micromirrors are arranged on the opposite slopes; the infrared light source is electrically connected to the electrodes on the surface of the upper substrate;

One or more grating structures are distributed in the depressions of the lower substrate, and infrared detectors corresponding to the number of grating structures; the infrared detectors are electrically connected to the electrodes on the outer surface of the lower substrate;

The position of the infrared light source on the upper substrate, the grating structure on the lower substrate, and the distribution position of the infrared detector are matched with the position and inclination angle of the reflective micromirror on the pit slope of the upper substrate, so that the infrared light emitted by the infrared light source passes through the grating After structural spectroscopic analysis, the narrow-band infrared light corresponding to the characteristic infrared absorption peak of the measured gas is directed to the reflective micromirror, and is accurately incident on the infrared detector after being reflected by the reflective micromirror;

Vent holes for exchanging gas with the outside are opened on the upper substrate, the lower substrate or the bonding dummy.

Further, the infrared light source is electrically connected to the electrodes on the outer surface of the upper substrate through the TSV through hole.

Further, the infrared detector is electrically connected to the electrode on the outer surface of the lower substrate through the TSV through hole.

Further, the infrared light source is packaged in vacuum.

Further, the infrared detector is packaged in vacuum.

Further, the pits of the upper substrate are in the shape of a rectangular truss.

Further, the bonding dummy is composed of single-layer or multi-layer materials, and the materials of the bonding dummy include silicon, silicon oxide, and silicon nitride.

Further, both the infrared light source and the reflective micromirror are manufactured by MEMS technology.

Further, both the infrared detector and the grating structure are manufactured by MEMS technology.

Further, the upper substrate, the lower substrate and the bonding dummy are bonded together by bonding technology.

The principle of the utility model is that the measured gas has a strong absorption effect on infrared light of a specific wavelength, and with the difference in the concentration of the measured gas, the intensity of infrared light reaching the infrared detector will also change, and the output of the infrared detector The electrical signal changes, and the concentration of the gas to be measured can be measured according to the change of the electrical signal. The role of the grating structure is to replace the traditional optical filter. Using the grating spectroscopic technology, by designing a reasonable grating spacing, width, and depth, the wide-band infrared light emitted by the infrared light source becomes a narrow-band window light source, which makes it compatible with the measured gas. The narrow-band infrared light in the band corresponding to the characteristic infrared absorption peak is irradiated to the corresponding reflective micromirror. The reflective micromirror is designed to increase the optical path of infrared rays, which can make the measured gas absorb infrared light more fully. The bonding dummy can make the gas chamber have a suitable height, so that the optical path of gas absorption can also be adjusted. The position of the infrared light source, the position of the grating structure on the lower substrate and the distribution of the infrared detector, and the position and inclination angle of the reflective micromirror must be precisely controlled and cooperated with each other to ensure that the infrared light emitted by the infrared light source passes through the grating structure and then passes through the The multiple reflections of the reflective micromirror happen to be incident on the infrared absorption region of the infrared detector.

In order to realize an infrared sensor capable of detecting multi-component gases, various types of grating structures can be fabricated on the lower substrate, and an infrared detector array corresponding to the position structure can be fabricated on the lower substrate. In the end, the combination of single light source and multiple detectors can be realized, and the combination of multiple light sources and multiple detectors can also be realized. According to the needs of users and the requirements for volume, a highly integrated matching design can be carried out.

Advantage of the utility model:

(1) Using grating spectroscopic technology, innovatively propose a fully monolithic and highly integrated infrared gas device without filters.

(2) Propose an ingenious gas chamber optical path structure, combined with key technologies such as wafer-level low-temperature bonding, and finally realize a miniaturized and integrated gas chamber structure.

(3) Design a variety of grating structures and make detector arrays to realize multi-component gas detection.

Description of drawings

Figure 1 is a schematic diagram of the basic composition and optical path design of a single-component infrared gas sensor.

Figure 2 is a schematic diagram of the basic composition and optical path design of the two-component infrared gas sensor.

Fig. 3 is a schematic diagram of the three-dimensional structure of the second embodiment.

Fig. 4 is a schematic diagram of a grating structure of a two-component infrared gas sensor.

Figure 5 is a schematic diagram of the basic composition and optical path design of a multi-component (more than 3) infrared gas sensor.

Fig. 6 is a schematic diagram of a grating structure of a multi-component infrared gas sensor.

Detailed ways

Below in conjunction with specific accompanying drawing and embodiment the utility model is further described.

Embodiment 1 is a single-component infrared gas sensor.

As shown in FIG. 1 : the infrared gas sensor includes an upper substrate 101 with pits, a lower substrate 108 with pits, and a bonding dummy 103 between the upper substrate 101 and the lower substrate 108 . The upper substrate 101 , the lower substrate 108 and the bonding dummy 103 are bonded together by low-temperature bonding technology, and a hollow air chamber 107 is formed in the middle. The bonding dummy 103 can be made of single-layer or multi-layer materials. In order to realize compatibility with the CMOS process, the bonding dummy 103 can be selected from materials such as silicon, silicon oxide, and silicon nitride. The thickness of the bonding dummy 103 can be Adjust according to the optical path length absorbed by the gas. The pits of the upper substrate 101 are in the shape of a rectangular prism.

A vent hole (not shown in FIG. 1 ) for exchanging gas with the outside is opened on the upper substrate 101 as a passage for the measured gas to enter and exit. The air hole can also be opened on the lower substrate 108 or the bonding dummy 103 .

A MEMS infrared light source 102 is processed in the recess of the pit of the upper substrate 101 , and the sidewall of the pit of the upper substrate 101 has relative slopes with a specific angle, and MEMS reflective micromirrors 1041 and 1042 are processed on the opposite slopes. The infrared light source 102 is a MEMS device, which is processed by surface micromachining technology and body processing technology. The infrared light source 102 is vacuum packaged to reduce heat transfer and heat convection; in addition, a certain distance between the infrared light source 102 and the upper substrate 101 The thermal isolation can reduce the thermal diffusion between the upper substrate 101 and increase the efficiency of infrared radiation. The infrared light source 102 is electrically connected to the electrode 1091 on the surface of the upper substrate through the TSV through hole 1101 , and the infrared light source 102 can be powered through the electrode 1091 . The reflective micromirrors 1041 and 1042 are designed to increase the optical path of infrared rays.

A grating structure 106 and an infrared detector 105 are processed in the depression of the lower substrate 108 . The infrared detector 105 and the grating structure 106 are MEMS devices, which are processed by surface micromachining technology and bulk processing technology, wherein the infrared detector 105 needs to be vacuum packaged to improve the absorption of infrared energy in the infrared absorption area and reduce the effect of heat convection. Improve the sensitivity and precision of the detector. The grating structure 106 is used as a band selection window. According to the characteristic infrared absorption peak of the measured gas, the corresponding grating spacing, width and depth are designed. The material for making the grating structure 106 can be Au, Ag, Al, TiN, etc. The function of the grating structure 106 is to replace the traditional filter, and use the grating spectroscopic technology to make the wide-band infrared light emitted by the infrared light source into a narrow-band window light source by designing a reasonable grating spacing, width, and depth. The infrared detector 105 is electrically connected to the electrode 1092 on the outer surface of the lower substrate through the TSV through hole 1102 , so as to realize electrical signal extraction and power supply to the infrared detector 105 .

The position of the infrared light source 102 on the upper substrate, the position of the distribution of the grating structure 106 and the infrared detector 105 on the lower substrate, and the positions and inclination angles of the reflective micromirrors 1041, 1042 on the pit slope of the upper substrate need to be precisely matched, so that the infrared After the infrared light emitted by the light source 102 is split by the grating structure 106, the narrow-band infrared light corresponding to the characteristic infrared absorption peak of the gas to be measured shoots to the reflective micromirror 1041, and after being reflected by the reflective micromirrors 1041 and 1042, it happens to be incident on the The infrared absorption region of the infrared detector 105 .

Embodiment 2 is a two-component infrared gas sensor.

As shown in Figure 2 and Figure 3: the main difference from Embodiment 1 is that there are two juxtaposed grating structures 1061, 1062 designed under the infrared light source 102, and on the left and right sides of the grating structures 1061, 1062 are infrared detectors 1051 and 1052. The direction of the arrow in FIG. 4 shows the propagation direction of the surface plasmon wave corresponding to each grating.

The optical path design of the two-component infrared gas sensor is shown by the arrow lines in Figure 2,

After the infrared light emitted by the infrared light source 102 is split by the grating structure 1061, the narrow-band infrared light corresponding to the band corresponding to the characteristic infrared absorption peak of the first measured gas is directed to the reflective micromirror 1042, and then reflected by the reflective micromirrors 1042 and 1041 successively. Just incident to the infrared absorption region of the infrared detector 1052.

After the infrared light emitted by the infrared light source 102 is split by the grating structure 1062, the narrow-band infrared light corresponding to the wavelength band corresponding to the characteristic infrared absorption peak of the second measured gas is directed to the reflective micromirror 1041, and then reflected by the reflective micromirrors 1041 and 1042 successively. Just incident to the infrared absorption region of the infrared detector 1051.

By detecting the electrical signals of the two infrared detectors, the concentrations of the two measured gases are analyzed.

All the other designs of embodiment two are the same as embodiment one.

The third embodiment is a multi-component infrared gas sensor.

As shown in Figure 5: the main difference from Embodiment 1 is that there are four grating structures 1063, 1064, 1065, and 1066 designed under the infrared light source 102, which are generally distributed in the shape of a field, forming a grating structure array. The direction of the arrow in FIG. 6 shows the propagation direction of the surface plasmon wave corresponding to each grating. There are infrared detectors 1056 , 1054 , 1055 , and 1053 at the front, rear, left, and right sides of the grating structure array, respectively. The pit on the upper substrate 101 is in the shape of a square prism, and MEMS reflective micromirrors are processed on the slopes of the four side walls of the pit, which are respectively reflective micromirrors 1041 , 1042 , 1043 , and 1044 .

The optical path design of the multi-component infrared gas sensor is shown by the arrow lines in Figure 5,

After the infrared light emitted by the infrared light source 102 is split by the grating structure 1063, the narrow-band infrared light corresponding to the wavelength band corresponding to the characteristic infrared absorption peak of the first measured gas is directed to the reflective micromirror 1042, and then reflected successively by the reflective micromirrors 1042 and 1041, Just incident to the infrared absorption region of the infrared detector 1053.

After the infrared light emitted by the infrared light source 102 is split by the grating structure 1064, the narrow-band infrared light corresponding to the wavelength band corresponding to the characteristic infrared absorption peak of the second measured gas is directed to the reflective micromirror 1043, and then reflected successively by the reflective micromirrors 1043 and 1044, Just incident to the infrared absorption region of the infrared detector 1054.

After the infrared light emitted by the infrared light source 102 is split by the grating structure 1065, the narrow-band infrared light corresponding to the band corresponding to the characteristic infrared absorption peak of the third measured gas is directed to the reflective micromirror 1041, and then reflected by the reflective micromirrors 1041 and 1042 successively. Just incident to the infrared absorption region of the infrared detector 1055.

After the infrared light emitted by the infrared light source 102 is split by the grating structure 1066, the narrow-band infrared light corresponding to the wavelength band corresponding to the characteristic infrared absorption peak of the fourth measured gas is directed to the reflective micromirror 1044, and then reflected by the reflective micromirrors 1044 and 1043 successively. Just incident to the infrared absorption region of the infrared detector 1056.

By detecting the electrical signals of the above four infrared detectors, the concentrations of the four measured gases can be analyzed.

All the other designs of embodiment three are the same as embodiment one.

The above-mentioned embodiments can be used to illustrate the structure and manufacturing process of the present utility model, but the implementation of the present utility model is by no means limited to the above-mentioned embodiments. Various substitutions, changes and modifications are possible without departing from the scope of the invention and the appended claims. Therefore, the protection scope of the present utility model is not limited to the content disclosed in the embodiments and drawings.

Claims (8)

1. a monolithic integrated miniature infrared gas sensor is characterized in that, comprising:

Upper substrate and the lower substrate with pit with pit, and the false sheet of the bonding between upper substrate and lower substrate, the false sheet of upper substrate, lower substrate and bonding combines, the middle air chamber that forms hollow;

The recess of upper substrate pit is provided with infrared light supply, and the sidewall of upper substrate pit has relative inclined-plane, is provided with the reflection micro mirror on relative inclined-plane; Infrared light supply is electrically connected the electrode of upper substrate appearance;

The recess of lower substrate pit is distributed with one or more optical grating constructions, and the infrared eye consistent with optical grating construction quantity; Infrared eye is electrically connected the electrode of lower substrate appearance;

Match in position and the angle of inclination of reflecting micro mirror on the position that optical grating construction on the position of infrared light supply, the lower substrate, infrared eye distribute on the upper substrate and the upper substrate pit inclined-plane, so that after the light splitting of the infrared light that infrared light supply sends process optical grating construction, with the arrowband infrared light directive reflection micro mirror of the corresponding wave band of tested gas characteristic infrared absorption peak, and after the reflection of reflection micro mirror, accurately be incident to infrared eye;

Have air hole with extraneous exchanging gas at upper substrate, lower substrate or the false sheet of bonding.

2. monolithic integrated miniature infrared gas sensor as claimed in claim 1 is characterized in that: described infrared light supply is electrically connected with the electrode of upper substrate appearance by the TSV through hole.

3. monolithic integrated miniature infrared gas sensor as claimed in claim 1 is characterized in that: described infrared eye is electrically connected with the electrode of lower substrate appearance by the TSV through hole.

4. monolithic integrated miniature infrared gas sensor as claimed in claim 1 is characterized in that: described infrared light supply employing Vacuum Package.

5. monolithic integrated miniature infrared gas sensor as claimed in claim 1 is characterized in that: described infrared eye employing Vacuum Package.

6. monolithic integrated miniature infrared gas sensor as claimed in claim 1 is characterized in that: the pit of upper substrate is the truncated rectangular pyramids shape.

7. monolithic integrated miniature infrared gas sensor as claimed in claim 1 is characterized in that: the false sheet of bonding is that the single or multiple lift material forms, and the material of the false sheet of bonding comprises silicon, monox, silicon nitride.

8. monolithic integrated miniature infrared gas sensor as claimed in claim 1 is characterized in that: go up the false sheet of substrate, lower substrate and bonding and be bonded together by bonding techniques.

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