CN113394332B - Preparation method of double-layer suspension infrared thermopile - Google Patents
Preparation method of double-layer suspension infrared thermopile Download PDFInfo
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- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
- H10N10/01—Manufacture or treatment
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
- G01J5/10—Radiation pyrometry, e.g. infrared or optical thermometry using electric radiation detectors
- G01J5/12—Radiation pyrometry, e.g. infrared or optical thermometry using electric radiation detectors using thermoelectric elements, e.g. thermocouples
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
- H10N10/10—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects
- H10N10/17—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects characterised by the structure or configuration of the cell or thermocouple forming the device
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
- G01J5/10—Radiation pyrometry, e.g. infrared or optical thermometry using electric radiation detectors
- G01J5/12—Radiation pyrometry, e.g. infrared or optical thermometry using electric radiation detectors using thermoelectric elements, e.g. thermocouples
- G01J2005/126—Thermoelectric black plate and thermocouple
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Abstract
The invention provides a preparation method of a double-layer suspended infrared thermopile, which comprises the steps of forming an etching window exposing a first sacrificial layer in a thermocouple composite layer through the first sacrificial layer in a substrate, so that a heat insulation cavity with a larger width can be formed through the etching window with a smaller width, the flexibility of the structural layout of the thermopile can be improved, and the space utilization rate of a device can be improved; furthermore, through forming the second sacrificial layer which is positioned below the infrared absorption layer and covers the etching window, the infrared absorption layer and the thermocouple composite layer can be simultaneously released in the last step, and the double-layer suspension infrared thermopile comprising the first layer suspension structure and the second layer suspension structure is formed, so that the process complexity can be effectively reduced, the yield is improved, and the miniaturization and the high performance of the infrared thermopile are favorably realized.
Description
Technical Field
The invention belongs to the technical field of silicon micromechanical sensing, and particularly relates to a preparation method of a double-layer suspension infrared thermopile.
Background
Infrared (IR) sensing arrays have been used in military, industrial, and consumer electronics markets, including night vision, automotive driving, human behavior detection, non-contact thermometry, and the like. For infrared thermal imaging, detectors need to be assembled into a Focal Plane Array (FPA) to capture the shape and motion of the inspected object. Compared with microbolometers and pyroelectric sensors, thermopile sensors are characterized by low power consumption, no flicker noise, and compatibility with CMOS processes, and therefore are low cost and commonly used in low cost fields such as air conditioning wind direction control and fall detection. However, the design of thermopile infrared sensing arrays faces the challenges of large size, slow response speed, and relatively low responsiveness. The existing scheme mainly optimizes the aspects of thermal conductivity, infrared absorption rate and the like of devices so as to improve the performance of the thermopile.
In the aspect of thermal conductivity optimization, a conventional thermopile detector usually deposits polysilicon/metal on a dielectric film to produce a thermocouple pair, and then produces a thermal insulation cavity below the dielectric film to form a suspended support dielectric layer structure, so as to reduce the thermal conductivity of the solid. When the heat insulation cavity is manufactured, if a back release method is adopted, complicated operation steps such as double-sided photoetching are introduced, the heat insulation cavity needs to penetrate through the whole silicon wafer, and the process time is greatly increasedAnd cost; the front-side release method has the advantages that only front-side processing is carried out and the depth of the heat insulation cavity can be manufactured as required, but in the front-side release process, the XeF is more commonly used 2 The problem of poor consistency still exists in dry release, and the hot stack structure layout is limited due to the crystal orientation characteristics of the monocrystalline silicon substrate in a bulk silicon anisotropic wet etching mode, so that the improvement of the performance of a hot stack detector is limited.
In terms of infrared absorption optimization, the first method is to enhance infrared absorption using a porous black material with high absorptivity, such as gold black, carbon black, and a metamaterial, but this method still has disadvantages in terms of process complexity, CMOS production compatibility, and cost, and the second method is to increase the area of an infrared absorption film, which is disadvantageous in terms of device array and miniaturization. Therefore, high performance thermopile detectors often use umbrella-shaped absorber film structures, however, thermopile detectors with umbrella-shaped absorber film structures often require multiple steps to release the structure, which not only increases the process complexity, but also other process steps experienced during the multi-step release process may damage the fragile film, beam structure, reducing the manufacturing yield.
Therefore, the method for preparing the double-layer suspension infrared thermopile is really necessary.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention is directed to a method for preparing a double-layer suspended infrared thermopile, which is used to solve the problems encountered in the prior art when preparing a high-performance and high-quality infrared thermopile.
In order to achieve the above objects and other related objects, the present invention provides a method for preparing a double-layer suspended infrared thermopile, comprising the steps of:
providing a base, wherein the base comprises a substrate and a first sacrificial layer;
forming a thermocouple composite layer on the substrate, wherein the thermocouple composite layer comprises a support medium layer covering the substrate, and a thermocouple material layer, an electric insulation layer and a metal interconnection layer which are positioned on the support medium layer, and the thermocouple material layer is positioned above the first sacrificial layer;
patterning the thermocouple composite layer to form an etching window exposing the first sacrificial layer;
forming a second sacrificial layer covering the thermocouple composite layer and the etching window;
patterning the second sacrificial layer to form a groove exposing the electric insulation layer at a hot junction of the thermocouple;
forming a patterned infrared absorption layer covering the second sacrificial layer and the groove;
and removing the second sacrificial layer by adopting wet etching to form a spacing gap, releasing the infrared absorption layer to form a second layer of suspension structure, removing the first sacrificial layer from the etching window to form a heat insulation cavity, and releasing the thermocouple composite layer to form a first layer of suspension structure.
Optionally, the first sacrificial layer comprises a silicon oxide layer or a metal layer, and the thickness ranges from 0.5 μm to 5 μm.
Optionally, the second sacrificial layer comprises a silicon oxide layer or a metal layer, and the thickness ranges from 0.5 μm to 5 μm.
Optionally, the first sacrificial layer and the second sacrificial layer are removed simultaneously in the last step.
Optionally, the step of forming the thermocouple composite layer on the substrate includes:
forming a supporting medium layer covering the substrate on the substrate;
forming a thermocouple material layer on the supporting medium layer;
forming an electric insulating layer covering the thermocouple material layer on the thermocouple material layer;
patterning the electric insulating layer to form a contact hole exposing the thermocouple material layer;
and forming a patterned metal interconnection layer on the electric insulation layer, wherein the metal interconnection layer is in contact with the thermocouple material layer through the contact hole.
Optionally, the thermocouple material layer is one of an N-type polysilicon layer, a P-type polysilicon layer, or a metal layer, or the thermocouple material layer is a stack of an N-type polysilicon layer, an inter-thermocouple insulating layer, and a P-type polysilicon layer; the metal interconnection layer comprises a single metal layer or a metal lamination layer.
Optionally, the supporting dielectric layer is one or a combination of a silicon nitride layer and a silicon oxide layer, and the thickness range is 0.2 μm to 2 μm.
Optionally, the electrically insulating layer is one or a combination of a silicon nitride layer and a silicon oxide layer, and the thickness is in a range of 0.05 μm to 1 μm.
Optionally, the infrared absorption layer is one or a combination of a silicon nitride layer and a silicon oxide layer, and the thickness range is 0.5 μm to 4 μm.
Optionally, a plurality of the thermocouples are formed, the thermocouples are connected in series to form a thermocouple group, and the infrared absorption layer is an umbrella-shaped infrared absorption layer covering the thermocouple group.
As described above, according to the preparation method of the double-layer suspended infrared thermopile of the present invention, the first sacrificial layer in the substrate and the etching window exposing the first sacrificial layer are formed in the thermocouple composite layer, so that the heat insulation cavity with a larger width can be formed through the etching window with a smaller width, thereby improving the flexibility of the structural layout of the thermopile and increasing the space utilization rate of the device; furthermore, through forming the second sacrificial layer which is positioned below the infrared absorption layer and covers the etching window, the infrared absorption layer and the thermocouple composite layer can be simultaneously released in the last step, and the double-layer suspension infrared thermopile comprising the first layer suspension structure and the second layer suspension structure is formed, so that the process complexity can be effectively reduced, the yield is improved, and the miniaturization and the high performance of the infrared thermopile are favorably realized.
Drawings
FIG. 1 is a schematic diagram of a process flow for forming a double-layer suspended infrared thermopile according to an embodiment of the present invention.
FIG. 2 is a schematic structural diagram of a substrate according to an embodiment of the invention.
FIG. 3 is a schematic structural diagram illustrating a thermocouple composite layer formed on a substrate according to an embodiment of the invention.
Fig. 4 is a schematic structural diagram after forming an etching window in the embodiment of the present invention.
Fig. 5 is a schematic structural diagram illustrating a patterned second sacrificial layer formed in the embodiment of the invention.
Fig. 6 is a schematic structural diagram of a patterned infrared absorption layer formed in the embodiment of the invention.
FIG. 7 is a schematic structural diagram of a double-layer suspended infrared thermopile formed after wet etching in the embodiment of the present invention.
Description of the element reference numerals
100. Substrate
200. Thermocouple composite layer
201. Supporting medium layer
202. Layer of thermocouple material
203. Electrically insulating layer
204. Metal interconnection layer
205. Etching window
301. First sacrificial layer
302. Second sacrificial layer
400. Infrared absorbing layer
501. Heat insulation cavity
502. Spacing gap
601. First layer suspension structure
602. Second layer suspension structure
S1 to S7
Detailed Description
The following embodiments of the present invention are provided by way of specific examples, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
As in the detailed description of the embodiments of the present invention, the cross-sectional views illustrating the device structures are not partially enlarged in general scale for convenience of illustration, and the schematic views are only examples, which should not limit the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.
Spatially relative terms, such as "under," "below," "lower," "below," "over," "upper," and the like, may be used herein for convenience in describing the relationship of one element or feature to another element or feature illustrated in the figures. It will be understood that these terms of spatial relationship are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. Further, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. As used herein, "between 8230%" \8230: "means both end points are included.
In the context of this application, a structure described as having a first feature "on" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed in between the first and second features, such that the first and second features may not be in direct contact.
It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of each component in actual implementation may be changed freely, and the layout of the components may be more complicated.
As shown in fig. 1, this embodiment provides a method for manufacturing a double-layer suspended infrared thermopile, including the following steps:
s1: providing a base, wherein the base comprises a substrate and a first sacrificial layer;
s2: forming a thermocouple composite layer on the substrate, wherein the thermocouple composite layer comprises a support medium layer covering the substrate, and a thermocouple material layer, an electric insulation layer and a metal interconnection layer which are positioned on the support medium layer, and the thermocouple material layer is positioned above the first sacrificial layer;
s3: patterning the thermocouple composite layer to form an etching window exposing the first sacrificial layer;
s4: forming a second sacrificial layer covering the thermocouple composite layer and the etching window;
s5: patterning the second sacrificial layer to form a groove exposing the electric insulation layer at a hot junction of the thermocouple;
s6: forming a patterned infrared absorption layer covering the second sacrificial layer and the groove;
s7: and removing the second sacrificial layer by adopting wet etching to form a spacing gap, releasing the infrared absorption layer to form a second layer of suspension structure, removing the first sacrificial layer from the etching window to form a heat insulation cavity, and releasing the thermocouple composite layer to form a first layer of suspension structure.
According to the preparation method of the double-layer suspended infrared thermopile, the first sacrificial layer in the substrate and the etching window exposing the first sacrificial layer are formed in the thermocouple composite layer, so that the heat insulation cavity with a large width can be formed through the etching window with a small width, the flexibility of the structural layout of the thermopile can be improved, the space utilization rate of a device is improved, and the problem that the structural layout of the thermopile is limited due to the crystal orientation characteristic of a monocrystalline silicon substrate is solved.
The double-layer suspended infrared thermopile prepared in this embodiment is described below with reference to fig. 2 to 7, and specifically as follows:
first, step S1 is performed, referring to fig. 2, a base is provided, and the base includes the substrate 100 and the first sacrificial layer 301.
Specifically, the substrate 100 may be a (100) single crystal silicon substrate, but is not limited thereto, and may also be polysilicon or amorphous silicon, and is not limited herein, in this embodiment, a more general (100) single crystal silicon substrate is preferred, and the (100) single crystal silicon substrate is preferably a single-sided or double-sided polished silicon wafer to provide a flat surface, which is convenient for preparation in a subsequent process. The first sacrificial layer 301 may be a silicon oxide layer or a metal layer, so as to improve an etching selection ratio of the first sacrificial layer 301 to the substrate 100, and facilitate subsequent wet etching removal to form a thermal insulation cavity 501 with a good thermal insulation effect, thereby solving the problem that the thermal stack structure layout is limited due to the crystal orientation characteristics of a monocrystalline silicon substrate, and the performance improvement of a thermal stack detector is limited, improving the flexibility of the structure layout of the thermal stack, and improving the device space utilization rate. Further, the thickness of the first sacrificial layer 301 may range from 0.5 μm to 5 μm, such as 0.5 μm, 1 μm, 2 μm, 5 μm, and the like.
Next, step S2 is performed, referring to fig. 3, a thermocouple composite layer 200 is formed on the substrate, the thermocouple composite layer 200 includes a supporting dielectric layer 201 covering the substrate and the first sacrificial layer 301, and a thermocouple material layer 202, an electrical insulation layer 203 and a metal interconnection layer 204 on the supporting dielectric layer 201, and the thermocouple material layer 202 is located above the first sacrificial layer 301.
As an example, in the present embodiment, there is provided a thermocouple stacked in a vertical direction, that is, the prepared thermocouple material layer 202 and the prepared metal interconnection layer 204 are arranged in a vertical direction, so as to improve space utilization, and facilitate miniaturization of the infrared thermopile. The forming of the thermocouple composite layer 200 on the substrate may include, but is not limited to, the following steps:
forming a supporting dielectric layer 201 covering the substrate on the substrate;
forming a thermocouple material layer 202 on the support dielectric layer 201;
forming an electrical insulation layer 203 on the thermocouple material layer 202 to cover the thermocouple material layer 202;
patterning the electrical insulation layer 203 to form contact holes exposing the thermocouple material layer 202;
a patterned metal interconnect layer 204 is formed on the electrically insulating layer 203, and the metal interconnect layer 204 contacts the thermocouple material layer 202 through the contact holes.
As an example, the thermocouple material layer 202 may be one of an N-type polysilicon layer, a P-type polysilicon layer, or a metal layer, or the thermocouple material layer 202 is a stack of an N-type polysilicon layer, an inter-thermocouple insulating layer, and a P-type polysilicon layer; the metal interconnection layer 204 includes a single metal layer or a metal stack.
Specifically, when the thermocouple material layer 202 is made of a doped polysilicon material, such as an N-type polysilicon layer or a P-type polysilicon layer, or the thermocouple material layer 202 is a metal layer, the metal interconnection layer 204 serves as both a metal electrical connection layer and a thermocouple component material in a thermocouple, so that the number of process steps can be reduced. In this embodiment, the thermocouple material layer 202 is a patterned P-type polysilicon layer with a thickness ranging from 0.2 μm to 2 μm, such as 0.2 μm, 0.5 μm, 1.0 μm, 1.5 μm, 2.0 μm, etc., and the metal interconnection layer 204 is a Cr-Pt-Au composite metal stack, but the material, structure and type of the thermocouple material layer 202 and the metal interconnection layer 204 are not limited thereto.
By way of example, the supporting dielectric layer 201 may be one or a combination of a silicon nitride layer and a silicon oxide layer, and the thickness may range from 0.2 μm to 2 μm, such as 0.2 μm, 1 μm, 1.5 μm, 2 μm, and the like; the electrically insulating layer 203 may be one or a combination of a silicon nitride layer and a silicon oxide layer, and may have a thickness of 0.05 μm to 1 μm, such as 0.05 μm, 0.2 μm, 0.5 μm, 1 μm, and the like. Preferably, the materials of the supporting dielectric layer 201 and the electrical insulating layer 203 do not react with the etching solution used in the subsequent removal of the sacrificial layer, so as to avoid the damage of the etching solution to the supporting dielectric layer 201 and the electrical insulating layer 203.
Next, step S3 is performed, referring to fig. 4, the thermocouple composite layer 200 is patterned to form an etching window 205 exposing the first sacrificial layer 301. The etching window 205 penetrates through the electrical insulation layer 203 and the support dielectric layer 201, so that the etching of the first sacrificial layer 301 by the etching solution is facilitated.
Next, step S4 and step S5 are performed, referring to fig. 5, a second sacrificial layer 302 is formed to cover the thermocouple composite layer 200 and the etching window 205, the second sacrificial layer 302 is patterned, and a trench exposing the electrical insulation layer 203 is formed at a hot junction of the thermocouple.
As an example, the second sacrificial layer 302 may include a silicon oxide layer or a metal layer.
Specifically, the material of the second sacrificial layer 302 is preferably the same as or similar to that of the first sacrificial layer 301, so that when performing subsequent wet etching, the first sacrificial layer 301 and the second sacrificial layer 302 can be removed in the same etching step to form a double-layer suspension structure. In this embodiment, the first sacrificial layer 301 is a silicon oxide layer or a metal layer, and thus the second sacrificial layer 302 may be the same silicon oxide layer or metal layer as the first sacrificial layer 301, so as to release the infrared absorption layer 400 and the thermocouple composite layer 200 at the same time in the last step, and form a double-layer suspended infrared thermopile including a first layer suspended structure 601 and a second layer suspended structure 602, thereby effectively reducing the process complexity, improving the yield, and facilitating the realization of miniaturization and high performance of the infrared thermopile. Of course, the second sacrificial layer 302 and the first sacrificial layer 301 may also be made of different materials, so as to be removed by two-step etching, which is not limited herein.
As an example, the second sacrificial layer 300 may be formed to have a thickness ranging from 0.5 μm to 5 μm, such as 0.5 μm, 1.0 μm, 2.0 μm, 3.0 μm, 4 μm, 5 μm, and the like.
Specifically, the second sacrificial layer 300 in this embodiment can be removed by subsequent wet etching, so that a smaller gap can be formed on the premise of meeting the device requirements, the device size can be reduced, and the cost can be reduced.
Next, step S6 is performed, referring to fig. 6, to form a patterned ir absorbing layer 400 covering the second sacrificial layer 302 and the trench.
By way of example, the infrared absorption layer 400 may be formed as one or a combination of a silicon nitride layer and a silicon oxide layer, and may have a thickness of 0.5 μm to 4 μm, such as 0.5 μm, 1.0 μm, 1.5 μm, 4 μm, and the like.
As an example, a plurality of the thermocouples may be formed, the thermocouples may be connected in series to constitute a thermocouple group, and the infrared absorption layer 400 is an umbrella-shaped infrared absorption layer covering the thermocouple group.
Specifically, in the present embodiment, it is preferable that a plurality of the thermocouples are included and are connected in series to constitute a thermocouple group so as to provide a sufficient number of thermocouples and a sufficiently high voltage to improve sensitivity, and the infrared absorption layer 400 is preferably an umbrella-shaped infrared absorption layer covering the thermocouple group to improve light absorption amount. The number and arrangement of the thermocouples are not limited herein, and may be set as desired.
Next, step S7 is performed, referring to fig. 7, a wet etching is adopted to remove the second sacrificial layer 302 to form a gap 502, release the infrared absorption layer 400 to form a second layer suspension structure 602, remove the first sacrificial layer 301 from the etching window 205 to form a thermal insulation cavity 501, and release the thermocouple composite layer 200 to form a first layer suspension structure 601.
Specifically, when the first sacrificial layer 301 and the second sacrificial layer 302 are made of silicon oxide, the etching solution for wet etching may include silicon oxide etching solutions such as BOE and HF for removing silicon oxide, and when the first sacrificial layer 301 and the second sacrificial layer 302 are made of a metal material such as aluminum, the etching solution for wet etching may be an aluminum etching solution, but is not limited thereto. In this embodiment, the first sacrificial layer 301 and the second sacrificial layer 302 can be removed simultaneously in the last step by the etching solution, so that the process complexity of preparing the double-layer suspended infrared thermopile can be reduced, the yield can be improved, and the realization of miniaturization and high performance of the infrared thermopile can be facilitated.
In summary, according to the preparation method of the double-layer suspended infrared thermopile, the first sacrificial layer in the substrate and the etching window exposing the first sacrificial layer are formed in the thermocouple composite layer, so that the heat insulation cavity with a larger width can be formed through the etching window with a smaller width, the flexibility of the structural layout of the thermopile can be improved, and the space utilization rate of the device can be improved; furthermore, through forming the second sacrificial layer which is positioned below the infrared absorption layer and covers the etching window, the infrared absorption layer and the thermocouple composite layer can be simultaneously released in the last step, and the double-layer suspension infrared thermopile comprising the first layer suspension structure and the second layer suspension structure is formed, so that the process complexity can be effectively reduced, the yield is improved, and the miniaturization and the high performance of the infrared thermopile are favorably realized.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which may be made by those skilled in the art without departing from the spirit and scope of the present invention as defined in the appended claims.
Claims (9)
1. A preparation method of a double-layer suspension infrared thermopile is characterized by comprising the following steps:
providing a base, wherein the base comprises a substrate and a first sacrificial layer;
forming a thermocouple composite layer on the substrate, wherein the thermocouple composite layer comprises a support medium layer covering the substrate, and a thermocouple material layer, an electric insulation layer and a metal interconnection layer which are positioned on the support medium layer, and the thermocouple material layer is positioned above the first sacrificial layer; wherein the step of forming the thermocouple composite layer on the substrate comprises:
forming a supporting dielectric layer covering the substrate on the substrate;
forming a thermocouple material layer on the supporting medium layer;
forming an electric insulating layer covering the thermocouple material layer on the thermocouple material layer;
patterning the electric insulating layer to form a contact hole exposing the thermocouple material layer;
forming a patterned metal interconnection layer on the electric insulation layer, wherein the metal interconnection layer is in contact with the thermocouple material layer through the contact hole;
patterning the thermocouple composite layer to form an etching window exposing the first sacrificial layer;
forming a second sacrificial layer covering the thermocouple composite layer and the etching window;
patterning the second sacrificial layer, and forming a groove exposing the electric insulation layer at a hot junction of the thermocouple;
forming a patterned infrared absorption layer covering the second sacrificial layer and the groove;
and removing the second sacrificial layer by adopting wet etching to form a spacing gap, releasing the infrared absorption layer to form a second layer of suspension structure, removing the first sacrificial layer from the etching window to form a heat insulation cavity, and releasing the thermocouple composite layer to form a first layer of suspension structure.
2. The method for preparing a double-layer suspended infrared thermopile according to claim 1, characterized in that: the first sacrificial layer comprises a silicon oxide layer or a metal layer, and the thickness range is 0.5-5 mu m.
3. The method for preparing a double-layer suspended infrared thermopile according to claim 1, characterized in that: the second sacrificial layer comprises a silicon oxide layer or a metal layer, and the thickness range is 0.5-5 mu m.
4. The method for preparing a double-layer suspended infrared thermopile according to claim 1, characterized in that: and removing the first sacrificial layer and the second sacrificial layer simultaneously in the last step.
5. The method for preparing a double-layer suspended infrared thermopile according to claim 1, characterized in that: the thermocouple material layer is one of an N-type polycrystalline silicon layer, a P-type polycrystalline silicon layer or a metal layer, or the thermocouple material layer is a lamination layer consisting of the N-type polycrystalline silicon layer, an inter-thermocouple insulating layer and the P-type polycrystalline silicon layer; the metal interconnection layer comprises a single metal layer or a metal lamination layer.
6. The method for preparing a double-layer suspended infrared thermopile according to claim 1, characterized in that: the supporting dielectric layer is one or a combination of a silicon nitride layer and a silicon oxide layer, and the thickness range is 0.2-2 mu m.
7. The method for preparing a double-layer suspended infrared thermopile according to claim 1, characterized in that: the electric insulating layer is one or a combination of a silicon nitride layer and a silicon oxide layer, and the thickness range is 0.05-1 mu m.
8. The method for preparing a double-layer suspended infrared thermopile according to claim 1, characterized in that: the infrared absorption layer is one or a combination of a silicon nitride layer and a silicon oxide layer, and the thickness range is 0.5-4 mu m.
9. The method for preparing a double-layer suspended infrared thermopile according to claim 1, characterized in that: and forming a plurality of thermocouples, wherein the thermocouples are connected in series to form a thermocouple group, and the infrared absorption layer is an umbrella-shaped infrared absorption layer covering the thermocouple group.
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| US6335478B1 (en) * | 1999-11-04 | 2002-01-01 | Bruce C. S. Chou | Thermopile infrared sensor, thermopile infrared sensors array, and method of manufacturing the same |
| CN102901567A (en) * | 2011-07-29 | 2013-01-30 | 江苏物联网研究发展中心 | Thermopile infrared detector, array and preparation method of thermopile infrared detector |
| CN110627014A (en) * | 2019-09-19 | 2019-12-31 | 中国科学院上海微系统与信息技术研究所 | Method for manufacturing suspended infrared thermopile on substrate |
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| CN110577188B (en) * | 2019-09-19 | 2022-08-09 | 中国科学院上海微系统与信息技术研究所 | Method for manufacturing suspended infrared thermopile on substrate |
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| US6335478B1 (en) * | 1999-11-04 | 2002-01-01 | Bruce C. S. Chou | Thermopile infrared sensor, thermopile infrared sensors array, and method of manufacturing the same |
| CN102901567A (en) * | 2011-07-29 | 2013-01-30 | 江苏物联网研究发展中心 | Thermopile infrared detector, array and preparation method of thermopile infrared detector |
| CN110627014A (en) * | 2019-09-19 | 2019-12-31 | 中国科学院上海微系统与信息技术研究所 | Method for manufacturing suspended infrared thermopile on substrate |
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