Method for manufacturing suspended infrared thermopile on substrate
阅读说明：本技术 一种在衬底上制作悬浮红外热堆的方法 (Method for manufacturing suspended infrared thermopile on substrate ) 是由 李昕欣 周温涵 倪藻 于 2019-09-19 设计创作，主要内容包括：本发明提供一种在衬底上制作悬浮红外热堆的方法,所述方法包括：在衬底中形成侧壁保护层；形成纵向腐蚀引导层和侧向腐蚀引导层；淀积牺牲层；制作热偶层及吸收膜层；淀积热偶保护层,刻蚀形成腐蚀孔,通过腐蚀孔去除侧向腐蚀引导层、纵向腐蚀引导层及衬底,形成隔热空腔；去除热偶保护层,淀积引线绝缘层,刻蚀引线绝缘层形成接触孔,再形成金属引线；去除牺牲层及部分引线绝缘层,获得悬浮红外热堆。本发明采用单面加工工艺,可用于实现微传感器与集成电路的单片集成,有利于小尺寸、低成本、大批量生产。另外,本发明的方法可突破晶向的限制实现更深的隔热空腔的制备,大大提高器件的红外传感性能,并且利用牺牲层增强结构强度,提高生产良率。(The invention provides a method for manufacturing a suspended infrared thermopile on a substrate, which comprises the following steps: forming a sidewall protection layer in a substrate; forming a longitudinal corrosion guide layer and a lateral corrosion guide layer; depositing a sacrificial layer; manufacturing a thermocouple layer and an absorption film layer; depositing a thermocouple protection layer, etching to form an etching hole, and removing the lateral corrosion guide layer, the longitudinal corrosion guide layer and the substrate through the etching hole to form a heat insulation cavity; removing the thermocouple protection layer, depositing a lead insulation layer, etching the lead insulation layer to form a contact hole, and then forming a metal lead; and removing the sacrificial layer and part of the lead insulating layer to obtain the suspended infrared thermopile. The invention adopts a single-side processing technology, can be used for realizing the monolithic integration of the microsensor and the integrated circuit, and is beneficial to the small-size, low-cost and mass production. In addition, the method can break through the limitation of the crystal orientation to realize the preparation of deeper heat insulation cavities, greatly improve the infrared sensing performance of devices, enhance the structural strength by utilizing the sacrificial layer and improve the production yield.)
1. A method of fabricating a suspended infrared thermopile on a substrate, said method comprising at least:
1) providing a substrate, and forming a side wall protection layer in the substrate;
2) forming a longitudinal corrosion guide layer in the substrate surrounded by the side wall protection layer, and forming a lateral corrosion guide layer on the surface of the substrate surrounded by the side wall protection layer;
3) depositing a sacrificial layer on the surface of the structure obtained in the step 2);
4) manufacturing a thermocouple layer and an absorption film layer connected with one end of the thermocouple layer on the sacrificial layer;
5) depositing a thermocouple protection layer covering the sacrificial layer, the thermocouple layer and the absorption film layer, then etching the thermocouple protection layer and the sacrificial layer to form an etch hole exposing the lateral corrosion guiding layer, and removing the substrate surrounded by the lateral corrosion guiding layer, the longitudinal corrosion guiding layer and the side wall protection layer through the etch hole etching to form a heat insulation cavity;
6) removing the thermocouple protection layer, depositing a lead insulation layer covering the sacrificial layer, the thermocouple layer and the absorption film layer, etching the lead insulation layer to form a contact hole exposing the thermocouple layer, and forming a metal lead in the contact hole and on the surface of the lead insulation layer;
7) and removing the sacrificial layer and part of the lead insulating layer above the heat insulation cavity to obtain the suspended infrared thermopile.
2. The method of claim 1 for fabricating a suspended infrared thermopile on a substrate, wherein: the step of forming the sidewall protection layer in step 1) includes:
1-1) forming a first thin layer with a thin middle part and a thick periphery on the surface of the substrate, etching the first thin layer area with the thin middle part to form a first window, etching the first thin layer area with the thick periphery to form a second window, and continuously etching the substrate below to form a first groove body;
1-2) depositing a second thin layer on the surface of the structure obtained in the step 1-1), wherein the second thin layer deposited on the side wall of the first groove body forms the side wall protection layer.
3. The method of claim 2 for fabricating a suspended infrared thermopile on a substrate, wherein: in step 2), the step of forming the longitudinal etching guide layer and the guide layer includes:
2-1) etching the second thin layer in the first window and continuously etching the substrate below to form a second groove body;
2-2) removing the intermediate thin layer of the first thin layer to expose the substrate;
2-3) depositing and forming the longitudinal corrosion guide layer in the second groove body, and depositing and forming the lateral corrosion guide layer on the exposed surface of the substrate.
4. The method of claim 1 for fabricating a suspended infrared thermopile on a substrate, wherein: the substrate comprises a (100) monocrystalline silicon substrate, and the sidewall protection layer comprises one of silicon oxide and silicon nitride.
5. The method of claim 1 for fabricating a suspended infrared thermopile on a substrate, wherein: the longitudinal corrosion guiding layer comprises one of polycrystalline silicon and amorphous silicon, and the lateral corrosion guiding layer comprises one of polycrystalline silicon and amorphous silicon.
6. The method of claim 1 for fabricating a suspended infrared thermopile on a substrate, wherein: the sacrificial layer comprises one of silicon oxide and silicon nitride.
7. The method of claim 1 for fabricating a suspended infrared thermopile on a substrate, wherein: the thermocouple layer comprises one of an N-type polycrystalline silicon strip, a P-type polycrystalline silicon strip and an N-type polycrystalline silicon strip-thermocouple insulating layer-P-type polycrystalline silicon strip stacked structure.
8. The method of claim 1 for fabricating a suspended infrared thermopile on a substrate, wherein: the absorption film layer comprises silicon nitride.
9. The method of claim 1 for fabricating a suspended infrared thermopile on a substrate, wherein: in step 5), the heat insulation cavity passes through XF2And carrying out isotropic etching or alkaline solution anisotropic etching by using gas, and removing the lateral etching guide layer and the substrate below the lateral etching guide layer.
10. The method of making a suspended infrared thermopile on a substrate of claim 1, wherein: the thermocouple protective layer comprises silicon oxide, the lead insulating layer comprises one of silicon oxide and silicon nitride, and the metal lead comprises one or more of Al, Au and Pt.
11. The method of claim 1 for fabricating a suspended infrared thermopile on a substrate, wherein: and 7), removing the sacrificial layer and part of the lead insulating layer above the heat insulation cavity in a gas-phase HF (high frequency) corrosion or HF solution corrosion mode.
Technical Field
The invention belongs to the technical field of silicon micromechanical sensing, and particularly relates to a method for manufacturing a suspended infrared thermopile on a substrate.
Background
With the rapid development of the MEMS technology, the infrared detector manufactured based on the MEMS micromachining technology is widely applied to the thermopile infrared detector with its advantages of small size, low price, etc., and is now widely applied to the fields of non-contact temperature measurement, gas sensing, security, satellite attitude control, infrared imaging, etc. The thermopile infrared detector has obvious advantages compared with other types of infrared detectors, such as being capable of working at room temperature without refrigeration equipment; the device has the characteristic of generating signals by self-excitation, does not need to apply extra bias voltage/current, avoids self-heating effect and simultaneously ensures low power consumption, and can realize direct measurement of infrared signals which tend to be static without adding a chopper; in recent years, the development of thermopile detector arrays further broadens the application range of thermopile infrared detectors, and meanwhile, the thermopile infrared detectors are promoted to develop along the direction of miniaturization, lower cost and higher performance.
The traditional thermopile detector usually deposits polysilicon/metal on a dielectric film to manufacture a thermocouple pair, and then forms a heat insulation cavity below the dielectric film by a method of back silicon anisotropic wet etching to increase the heat resistance. However, the scheme needs double-sided processing, so that the process complexity is increased, and meanwhile, a substrate structure is not arranged below the device, so that the mechanical strength of the device is reduced. In addition, the scheme is limited by the anisotropy of wet etching of the (100) monocrystalline silicon substrate, the size of the device is large, and the thermopile structure needs to be arranged according to the crystal orientation, so that the improvement of the performance of the thermopile detector is limited.
In 1992, shie.j et al fabricated infrared detectors on glass films on silicon substrates by wet etching. However, due to the anisotropic limitation OF wet etching OF silicon, the design OF the device structure must be arranged according to a certain rule, and the optimal performance solution [ Shie J, Weng P.DESIGN CONSIDETIONS OF METAL-FILM BOLOMETER WITH MICRO-MECHANICAL FLOATING MEMBRANE [ J ]. Sensors & initiators A physic, 1992,33(3):183 189.]2006, Calaza.C. et al have used standard CMOS process and TMAH Post-CMOS technology to fabricate the micro-mechanical thermopile infrared detector array for infrared imaging and have succeeded in obtaining the room temperature infrared imaging effect. However, due to the limitation of the anisotropy of the silicon wet etching, the area of a single device is large, the final detector array is 16 × 16, the density is small, the structure is damaged by the wet etching process, and the yield is reduced. [ Calaza C, Viarani N, Pedretti G, ethyl. an uncooled enriched planar array for low-cost applied fabricated with standard CMOS technology [ J ]. Sensors and actors A (Physical),2006,132(1):129 and 138 ].
Therefore, it is a problem to be solved by those skilled in the art to provide a new method for fabricating a suspended infrared thermopile on a substrate.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a method for fabricating a floating ir thermopile on a substrate, which is used to solve the problems of complex process, low mechanical strength, large device size, poor infrared detection performance, etc. of the floating ir thermopile fabricated by the method of the prior art.
To achieve the above and other related objects, the present invention provides a method for fabricating a suspended infrared thermopile on a substrate, the method at least comprising:
1) providing a substrate, and forming a side wall protection layer in the substrate;
2) forming a longitudinal corrosion guide layer in the substrate surrounded by the side wall protection layer, and forming a lateral corrosion guide layer on the surface of the substrate surrounded by the side wall protection layer;
3) depositing a sacrificial layer on the surface of the structure obtained in the step 2);
4) manufacturing a thermocouple layer and an absorption film layer connected with one end of the thermocouple layer on the sacrificial layer;
5) depositing a thermocouple protection layer covering the sacrificial layer, the thermocouple layer and the absorption film layer, then etching the thermocouple protection layer and the sacrificial layer to form an etch hole exposing the lateral corrosion guiding layer, and removing the substrate surrounded by the lateral corrosion guiding layer, the longitudinal corrosion guiding layer and the side wall protection layer through the etch hole etching to form a heat insulation cavity;
6) removing the thermocouple protection layer, depositing a lead insulation layer covering the sacrificial layer, the thermocouple layer and the absorption film layer, etching the lead insulation layer to form a contact hole exposing the thermocouple layer, and forming a metal lead in the contact hole and on the surface of the lead insulation layer;
7) and removing the sacrificial layer and part of the lead insulating layer above the heat insulation cavity to obtain the suspended infrared thermopile.
As an optimized solution of the method for manufacturing a suspended infrared thermopile on a substrate according to the present invention, the step of forming the sidewall protection layer in step 1) includes:
1-1) forming a first thin layer with a thin middle part and a thick periphery on the surface of the substrate, etching the first thin layer area with the thin middle part to form a first window, etching the first thin layer area with the thick periphery to form a second window, and continuously etching the substrate below to form a first groove body;
1-2) depositing a second thin layer on the surface of the structure obtained in the step 1-1), wherein the second thin layer deposited on the side wall of the first groove body forms the side wall protection layer.
As an optimized solution of the method for manufacturing a suspended infrared thermopile on a substrate according to the present invention, in step 2), the steps of forming the longitudinal corrosion guide layer and the guide layer include:
2-1) etching the second thin layer in the first window and continuously etching the substrate below to form a second groove body;
2-2) removing the intermediate thin layer of the first thin layer to expose the substrate;
2-3) depositing and forming the longitudinal corrosion guide layer in the second groove body, and depositing and forming the lateral corrosion guide layer on the exposed surface of the substrate.
As an optimized proposal of the method for manufacturing the suspended infrared thermopile on the substrate, the substrate comprises (100) monocrystalline silicon substrate, and the side wall protective layer comprises one of silicon oxide and silicon nitride.
As an optimized scheme of the method for manufacturing the suspended infrared thermopile on the substrate, the longitudinal corrosion guiding layer comprises one of polycrystalline silicon and amorphous silicon, and the lateral corrosion guiding layer comprises one of polycrystalline silicon and amorphous silicon.
As an optimized solution of the method for fabricating a suspended infrared thermopile on a substrate according to the present invention, the sacrificial layer comprises one of silicon oxide and silicon nitride.
As an optimized scheme of the method for manufacturing the suspended infrared thermopile on the substrate, the thermocouple layer comprises one of an N-type polycrystalline silicon strip, a P-type polycrystalline silicon strip and an N-type polycrystalline silicon strip-thermocouple insulating layer-P-type polycrystalline silicon strip superposed structure.
As an optimized solution of the method for manufacturing a suspended infrared thermopile on a substrate according to the present invention, the absorption film layer comprises silicon nitride.
As an optimized proposal of the method for manufacturing the suspended infrared thermopile on the substrate, in the step 5), the heat insulation cavity passes through XF2And carrying out isotropic etching or alkaline solution anisotropic etching by using gas, and removing the lateral etching guide layer and the substrate below the lateral etching guide layer.
As an optimized solution of the method for manufacturing a suspended infrared thermopile on a substrate according to the present invention, the thermocouple protection layer comprises silicon oxide, the lead insulation layer comprises one of silicon oxide and silicon nitride, and the metal lead comprises one or a combination of Al, Au, and Pt.
As an optimized solution of the method for manufacturing the suspended infrared thermopile on the substrate according to the present invention, in step 7), the sacrificial layer and a portion of the lead insulating layer above the thermal insulation cavity are removed by gas-phase HF etching or HF solution etching.
As described above, the method for manufacturing a suspended infrared thermopile on a substrate of the present invention has the following beneficial effects:
1. the invention utilizes the sacrificial layer to ensure the mechanical strength of the suspension structure when the heat insulation cavity is released, and improves the production yield.
2. The invention avoids back etching of the silicon wafer, realizes single-side processing of the silicon wafer of the infrared thermopile with the suspended beam film structure, has compatible process conditions and steps with a standard CMOS process, can be used for realizing monolithic integration of a microsensor and an integrated circuit, and is beneficial to small-size, low-cost and mass production.
3. The invention creatively utilizes the sacrificial layer and the longitudinal corrosion guide layer to obtain the suspended infrared thermopile with the deep heat insulation cavity on the (100) monocrystalline silicon substrate, breaks through the restriction relation between the device area on the (100) monocrystalline silicon chip and the depth of the heat insulation cavity, obtains the deeper heat insulation cavity while reducing the area of a single device of the infrared thermopile, and the arrangement of the thermopile is not limited by anisotropic corrosion any more, thereby greatly improving the infrared sensing performance of the device.
Drawings
Fig. 1 is a flow chart illustrating a method for fabricating a suspended infrared thermopile on a substrate in an embodiment of the present invention.
Fig. 2-16 are cross-sectional views of structures presented by a method of fabricating a suspended infrared thermopile on a substrate in an embodiment of the present invention.
Fig. 17 is a top view of a device obtained by a method of forming a suspended infrared thermopile on a substrate in accordance with an embodiment of the present invention.
Fig. 18 is a perspective view of a device structure obtained by the method for fabricating a suspended infrared thermopile on a substrate in an embodiment of the present invention.
Fig. 19 is a perspective half-sectional view of a device structure obtained by the method for fabricating a suspended infrared thermopile on a substrate in an embodiment of the present invention.
Description of the element reference numerals
1 substrate
2 side wall protective layer
3 longitudinal corrosion guide layer
4 lateral corrosion guide layer
5 sacrificial layer
6 thermal couple layer
7 absorbing film layer
8 thermocouple protective layer
9 corrosion hole
10 insulating cavity
11 lead insulation layer
12 contact hole
13 metal lead wire
201 first thin layer
2011 first thin layer with thick periphery
2012 first thin layer in the middle
202 first window
203 first groove body
204 second thin layer
205 second tank body
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. 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.
Please refer to the attached drawings. 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 components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.
The embodiment provides a method for manufacturing a suspended infrared thermopile on a substrate, as shown in fig. 1, the method includes the following steps:
step S11 is first performed to provide a substrate in which a sidewall protection layer is formed.
Preferably, the step of forming the sidewall protection layer in the present step includes:
s111, forming a first thin layer with a thin middle part and a thick periphery on the surface of the substrate, etching the first thin layer area with the thin middle part to form a first window, etching the first thin layer area with the thick periphery to form a second window, and continuously etching the substrate below to form a first groove body.
Specifically, as shown in fig. 2 to 4, a silicon substrate 1 is provided, a thin layer 2011 is deposited on the surface of the substrate 1, the middle area is etched to expose the substrate 1, then a thin layer 2012 is deposited continuously, a part of the thin layer 2012 is formed on the surface of the substrate 1, a part of the thin layer 2012 covers the surface of the thin layer 2011, the thin layer 2011 and the thin layer 2012 are preferably made of the same material, the thin layer 2011 and the thin layer 2012 are combined to form a first thin layer 201 which is thin in the middle and thick at the periphery, and a first window 202 and a first groove 203 are etched.
And S112, depositing a second thin layer on the surface of the structure obtained in the step S111, wherein the second thin layer deposited on the side wall of the first groove body forms the side wall protective layer.
Specifically, as shown in fig. 15, a second thin layer 204 is deposited, and the second thin layer 204 covers the first window 202, the first groove 203, and the first thin layer 201. Wherein a second thin layer 204 attached to the inside of the first tank body 203 is used as the sidewall protection layer 2.
As an example, the substrate 1 includes a (100) single crystal silicon substrate, and the sidewall protection layer 2 includes one of silicon oxide and silicon nitride.
Preferably, the substrate 1 can be an N-type or P-type (100) single-side (or double-side) polished monocrystalline silicon wafer. The first and second thin layers 201 and 204 are silicon oxide prepared by Low Pressure Chemical Vapor Deposition (LPCVD). The first window 202 may be formed by etching using a Reactive Ion Etching (RIE) technique using a photoresist as a mask. The first trench 203 may be formed by etching using a Deep reactive ion etching (Deep-RIE) technique using a photoresist as a mask.
Fig. 2 to 16 are cross-sectional views taken along a broken line AA' in fig. 17 and 18. Fig. 17 is a plan view, and fig. 18 is a perspective view. To better illustrate the internal structure of the device, fig. 19 shows a perspective half-sectional view.
Next, step S12 is performed to form a longitudinal corrosion guiding layer in the substrate surrounded by the sidewall protection layer, and form a lateral corrosion guiding layer on the substrate surface surrounded by the sidewall protection layer.
Preferably, the step of forming the longitudinal corrosion guiding layer and the lateral corrosion guiding layer includes:
s121, as shown in fig. 6, etching the second thin layer 204 in the first window 202 and continuously etching the substrate 1 below to form a second slot 205;
s122, as shown in fig. 7, removing the middle thin first thin layer 201 to expose the substrate 1;
s123, as shown in fig. 8, depositing the longitudinal corrosion guiding layer 3 in the second slot 205, and depositing the lateral corrosion guiding layer 4 on the exposed surface of the substrate 1.
It should be noted that, in the step S121, a maskless process is adopted when etching the second thin layer 204 in the first window 202, so that the second thin layer 204 of the remaining part of the surface plane is also thinned, and then the second slot 205 is formed by etching with the remaining first thin layer 201 as a mask, and while forming the second slot 205, the bottom of the first slot 203 is continuously etched, so that the depth is increased, as shown in fig. 6; in step S122, while removing the middle thin first thin layer 201, the surrounding thick first thin layer 201 is also thinned, as shown in fig. 7; in step S123, in the process of depositing and forming the longitudinal corrosion guiding layer 3 and the lateral corrosion guiding layer 4, the first groove 203 is also filled with corrosion guiding materials, as shown in fig. 8, which can flatten the surface of the substrate 1, thereby facilitating the subsequent processes.
The longitudinal etching guiding layer 3 comprises one of polysilicon and amorphous silicon, and the lateral etching guiding layer 4 comprises one of polysilicon and amorphous silicon. In this embodiment, the longitudinal etching guiding layer 3 and the lateral etching guiding layer 4 are both polysilicon.
The longitudinal corrosion guiding layer 3 and the lateral corrosion guiding layer 4 can guide the corrosive liquid or the corrosive gas of the subsequent steps to corrode the substrate in the transverse and longitudinal directions, thereby controlling the width and the depth of the heat insulation cavity 10.
It should be noted that the depth of the longitudinal corrosion guiding layer 3 cannot be greater than the depth of the sidewall protection layer 2, because the longitudinal corrosion guiding layer 3 will advance to both sides while guiding the corrosion solution or the corrosion gas to corrode downwards, and will not stop until meeting the sidewall protection layer 2, if the depth of the longitudinal corrosion guiding layer 3 is deeper than the depth of the sidewall protection layer 2, the corrosion solution or the corrosion gas will break through the barrier of the sidewall protection layer 2, and the corrosion process will become uncontrollable.
Then, step S13 is performed, and as shown in fig. 9, the sacrificial layer 5 is deposited on the surface of the structure obtained in step S12.
As an example, the sacrificial layer 5 includes one of silicon oxide and silicon nitride. In this embodiment, the sacrificial layer 5 is silicon oxide, and the sacrificial layer 5 is prepared by Low Pressure Chemical Vapor Deposition (LPCVD), and has a thickness of 1 μm.
Next, step S14 is performed to fabricate a thermocouple layer and an absorption film layer connected to one end of the thermocouple layer on the sacrificial layer.
As shown in fig. 10, the thermocouple material may be deposited first, and then the RIE process may be used to etch the thermocouple layer 6 into a desired shape using the photoresist as a mask. As an example, the thermocouple layer 6 includes one of an N-type polysilicon stripe, a P-type polysilicon stripe, and an N-type polysilicon stripe-thermocouple insulating layer-P-type polysilicon stripe stacked structure. In this embodiment, the thermocouple layer 6 is phosphorus-doped N-type polysilicon with a thickness of 1 μm.
As shown in fig. 11, the absorber film material may be deposited by LPCVD, and then the absorber film layer 7 may be etched in a desired shape using a photoresist as a mask. As an example, the absorption film layer 7 may be silicon nitride, and the thickness is in a range of 0.5 μm to 2 μm.
And step S15 is executed, a thermocouple protection layer covering the sacrificial layer, the thermocouple layer and the absorption film layer is deposited, then the thermocouple protection layer and the sacrificial layer are etched, an etch hole exposing the lateral corrosion guiding layer is formed, and the substrate surrounded by the lateral corrosion guiding layer, the longitudinal corrosion guiding layer and the side wall protection layer is removed through the etch hole etching, so that an insulating cavity is formed.
As shown in fig. 12, the etching holes 9 can be etched by RIE using photoresist as a mask after depositing the thermocouple protection layer 8.
As an example, the thermocouple protection layer 8 includes silicon oxide. In this example, the thermocouple protection layer 8 is silicon oxide prepared by LPCVD with a thickness of 1 μm.
By way of example, the insulating cavity 10 passes XF2And carrying out isotropic etching or alkaline solution anisotropic etching by using gas, and removing the substrate 1 surrounded by the lateral etching guide layer 4, the longitudinal etching guide layer 3 and the side wall protection layer 2. In this embodiment, the substrate 1 surrounded by the lateral etching guiding layer 4, the longitudinal etching guiding layer 3, and the sidewall protection layer 2 may be removed by using TMAH (tetramethylammonium hydroxide) or KOH (potassium hydroxide) etching solution to form a thermal insulation cavity 10, as shown in fig. 13.
Therefore, the lateral corrosion guide layer 4 and the longitudinal corrosion guide layer 3 can obtain the suspended infrared thermopile with the deep heat insulation cavity 10 on the (100) monocrystalline silicon substrate 1, the restriction relation between the device area on the (100) monocrystalline silicon chip and the depth of the heat insulation cavity is broken, the deeper heat insulation cavity is obtained while the area of a single device of the infrared thermopile is reduced, the arrangement of the thermopile is not limited by anisotropic corrosion, and the infrared sensing performance of the device can be greatly improved.
In addition, the sacrificial layer 5 can ensure the mechanical strength of the suspension structure when the heat insulation cavity (deep groove) is released, and the production yield is improved.
And step S16 is executed, the thermocouple protection layer is removed, a lead insulation layer covering the sacrificial layer, the thermocouple layer and the absorption film layer is deposited, the lead insulation layer is etched to form a contact hole exposing the thermocouple layer, and a metal lead is formed in the contact hole and on the surface of the lead insulation layer.
As shown in fig. 14, the lead insulating layer 11 may be deposited by LPCVD, and then the contact hole 12 may be etched by RIE using a photoresist as a mask.
By way of example, the lead insulating layer 11 includes one of silicon oxide and silicon nitride, and the metal lead 13 includes one or a combination of Al, Au, and Pt. In this embodiment, the lead insulating layer 11 is silicon oxide and has a thickness of 200 nm; the metal lead 13 is Au. The metal lead 13 is formed as shown in fig. 15.
And finally, executing a step S17, removing the sacrificial layer and part of the lead insulating layer above the heat insulation cavity, and obtaining the suspended infrared thermopile.
As shown in fig. 16, the sacrificial layer 5 and a portion of the lead insulation layer 11 above the insulating cavity 10 may be removed by vapor HF etching or HF solution etching. In this embodiment, the sacrificial layer and a portion of the lead insulating layer 11 above the insulating cavity 10 are removed by vapor HF etching.
It should be noted that, while the sacrificial layer and a portion of the lead insulating layer 11 above the insulating cavity 10 are removed, the sidewall protection layer 2 and a portion of the first thin layer 201 may also be removed, as shown in fig. 16.
In summary, the present embodiment provides a method for manufacturing a suspended infrared thermopile on a substrate, which uses a single-sided process, and provides a deeper thermal insulation cavity to increase thermal resistance and improve infrared detection performance while reducing the size of a device, thereby overcoming the problems of the traditional thermopile detector based on a (100) silicon substrate that the size is large, double-sided processing is required, and the infrared detection performance of the device is reduced due to the insufficient depth of the thermal insulation cavity, and meanwhile, the process steps and conditions of the method are compatible with the standard IC process.
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 can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.