CN116040574A

CN116040574A - Manufacturing method of MEMS infrared light source

Info

Publication number: CN116040574A
Application number: CN202211326807.5A
Authority: CN
Inventors: 刘军林; 吕全江; 侯海港; 刘桂武; 乔冠军; 郝俊操; 夏松敏; 陈杰
Original assignee: Weijidian Technology Suzhou Co ltd
Current assignee: Weijidian Technology Suzhou Co ltd
Priority date: 2022-10-25
Filing date: 2022-10-25
Publication date: 2023-05-02

Abstract

The invention belongs to the technical field of photoelectricity, and particularly relates to a manufacturing method of an MEMS infrared light source. The manufacturing method is used for manufacturing the MEMS infrared light source with the special cavity and the reflecting layer between the substrate and the supporting layer. The method comprises the following steps: (1) mask processing of a substrate; (2) corrosion window preparation; (3) anisotropic etching; (4) preparation of a reflecting layer; (5) primary polishing; (6) sacrificial layer preparation; (7) secondary polishing; (8) preparation of a supporting layer; (9) preparing a heating electrode layer; (10) preparing a heating electrode pad; (11) preparing an infrared emission layer; (12) removing window preparation; (13) sacrificial layer removal. The technological principle is as follows: etching the pits, filling the pits with the sacrificial layer, generating each functional layer on the plane, and finally forming a removing window for communicating the pits to remove the sacrificial layer, thereby completing the manufacture of the product. The product produced by the invention can solve the problems of low photoelectric conversion efficiency, low product yield and the like of the traditional MEMS infrared light source.

Description

Manufacturing method of MEMS infrared light source

Technical Field

The invention belongs to the technical field of photoelectricity, and particularly relates to a manufacturing method of an MEMS infrared light source.

Background

Infrared sensing technology has been widely used in the fields of atmospheric quality detection, temperature monitoring, industrial process control, space monitoring, information communication, medicine, military, etc. Infrared light sources are important elements of infrared sensing technology, and commonly used light emission wavelengths are 3-5 microns and 8-14 microns. The traditional heat radiation infrared light source such as an incandescent lamp has low electro-optic conversion efficiency and poor modulation characteristic; the infrared diode with the wavelength of 3-5 microns has low luminous efficiency and low output power, so that the application of the infrared diode is limited; the quantum cascade infrared laser can emit high-intensity narrow-band infrared laser, but has low efficiency and high manufacturing cost. The MEMS infrared light source manufactured by utilizing the micro-electromechanical system (MEMS) technology is a novel heat radiation infrared light source, has the characteristics of high electro-optic conversion efficiency, small volume, low energy consumption and the like, simultaneously has a spectrum which easily covers a range of 2-20 micrometers, has a fast modulation frequency, and has been widely applied to the infrared sensing field and becomes a trend technology of the infrared light source.

The MEMS infrared light source with the conventional structure comprises a substrate, wherein a supporting layer is arranged on the substrate, the supporting layer is connected with the substrate by adopting a four-side solid supporting structure, and a heating electrode layer is arranged on the supporting layer. Joule heat is generated by energizing the heat-generating electrode layer, so that the heat-generating electrode layer is heated to a specific temperature (determined according to the required infrared emission wavelength and radiation amount), and infrared radiation is generated. The MEMS infrared light source mainly dissipates heat through heat conduction and infrared radiation. The heat conduction is that the heating electrode layer conducts heat through the substrate, and the heat transfer is reduced as much as possible, so that the electro-optical conversion efficiency of the MEMS infrared light source is improved and the heating power consumption is reduced. Infrared radiation is the core of MEMS infrared light source operation and needs to be enhanced. Therefore, it is necessary to greatly reduce the heat conduction of the heat generating electrode layer, and the substrate under the heat generating electrode layer is usually hollowed out to reduce the heat conduction of the substrate. The infrared radiation can be enhanced by selecting a material with high emissivity to manufacture the heating electrode layer or adding an infrared emission layer with higher infrared emissivity on the surface of the heating electrode layer.

Infrared radiation of the MEMS infrared light source mainly exits from two directions: one is to radiate outwards from above the heating electrode layer, and the part of infrared radiation is a part which can be utilized by the infrared sensor and needs to be reinforced; the other is that the radiation is emitted from the heating electrode layer to the hollowed part of the substrate through the supporting layer, and the infrared radiation is absorbed by packaging materials, the substrate and the like after the MEMS infrared light source is packaged, so that the infrared radiation cannot be effectively utilized, and the energy waste is reduced or even eliminated as much as possible.

The existing MEMS infrared light source greatly reduces the heat conduction of the MEMS infrared light source through a substrate hollowing technology, improves the electro-optical conversion efficiency of the MEMS infrared light source and reduces the heating power consumption, and the infrared emission capacity is improved by introducing a material or microstructure with high infrared emission rate above the heating electrode layer, so that the heating power consumption of the MEMS infrared light source is reduced, and meanwhile, the selection of the heating electrode layer is well known. However, most of the existing MEMS infrared light sources have not effectively solved the problem of utilizing infrared energy radiated from the heating electrode layer to the hollowed-out portion of the substrate through the supporting layer, so that huge waste of the infrared energy is caused, and heating power consumption of the MEMS infrared light sources is increased.

In order to inhibit energy loss caused by radiation diffused from the bottom of the heating electrode layer, some technicians propose an improvement scheme of adding a reflecting layer (such as chinese patent application publication No. CN114249292 a) on the bottom of the supporting layer of the MEMS infrared light source. According to the scheme, the infrared rays radiated to the hollowed part of the substrate by the heating electrode layer through the supporting layer are reflected back through the reflecting layer, and then are radiated upwards through the heating electrode layer. However, this type of solution solves the infrared radiation loss and causes new technical problems. For example, close attachment of the reflective layer to the support layer increases the heat capacity of the entire infrared light emitting film layer, thereby increasing the heat loss of the MEMS light source. Meanwhile, due to the fact that the reflecting layer and the supporting layer are attached, the risk of falling off of the reflecting layer, which is easily caused by the difference of thermal expansion coefficients, in the switching stage of the light source is increased, and the service life of the light source is shortened.

Disclosure of Invention

In order to solve the problems of low photoelectric conversion efficiency, low product yield and the like in the existing MEMS infrared light source, the invention provides a manufacturing method of the MEMS infrared light source, which can produce a novel MEMS infrared light source for overcoming the defects of the traditional light source.

The invention is realized by adopting the following technical scheme:

the manufacturing method of the MEMS infrared light source is used for manufacturing a substrate, a supporting layer, a heating electrode layer and an infrared emission layer; and a cavity with a special shape is arranged between the substrate and the supporting layer, and MEMS infrared light sources with reflecting layers with specific shapes are distributed in the cavity.

The manufacturing method comprises the following process steps:

(1) Mask processing of a substrate:

providing a substrate, and depositing a preset amount of mask layer material on the surface to be processed of the substrate to form a required corrosion mask layer.

(2) Preparing a corrosion window:

and removing part of the mask layer on the surface to be processed by utilizing a photoetching technology according to the preset window size and shape so as to form an etching window on the substrate. The exposed area below the etch window is the area of the substrate where etching is desired.

(3) Anisotropic etching:

and carrying out chemical corrosion on the substrate through an anisotropic corrosion process to form a pit which is concave towards the inside of the substrate and gradually reduces in caliber in a corrosion window area in the substrate.

(4) Preparing a reflecting layer:

and depositing a preset amount of reflecting layer material in the pits on the surface of the substrate by adopting a physical vapor deposition process to form the required reflecting layer.

(5) Primary polishing:

and polishing the surface to be processed of the substrate to remove the surface plating layer of other areas except the pits on the surface of the substrate, wherein the surface plating layer comprises a corrosion mask layer material and a reflection layer material.

(6) Sacrificial layer preparation:

the pits in the substrate are filled with a sacrificial layer material that can be selectively removed by any means.

(7) Secondary polishing:

and carrying out secondary polishing treatment on the surface to be processed of the substrate filled with the sacrificial layer material so that the sacrificial layer material in the pits is kept flush with the surrounding substrate surface.

(8) Preparing a supporting layer:

and generating a required supporting layer on the surface of the side, containing the sacrificial layer, of the substrate, wherein the supporting layer completely covers the substrate and the sacrificial layer below.

(9) Preparing a heating electrode layer:

and preparing a required heating electrode layer on the surface of the supporting layer, wherein the heating electrode layer is positioned above the pits in the corresponding substrate. The concave pit is completely covered on the left and right sides of the heating electrode layer, the front and rear sides are positioned in the area opposite to the inner side of the concave pit, and the concave pit is not covered.

(10) Preparing a heating electrode pad:

Two strip-shaped heating electrode pads which are parallel to each other and not exceeding the distribution area of the heating electrode layer are prepared above the heating electrode layer. Wherein, the distribution area of the two heating electrode bonding pads is separated from or circumscribed with the enclosing area of the upper opening of the pit.

(11) Preparing an infrared emission layer:

and preparing a required infrared emission layer above the heating electrode layer on the inner side of the heating electrode pad. The infrared emission layer is positioned in the connecting area of the four end points of the heating electrode pad.

(12) Removing window preparation:

etching the supporting layer material by photoetching technology, and selecting a specific area to process at least one penetrating removal window on the basis of not damaging the upper heating electrode layer and the infrared emission layer so as to expose the sacrificial layer material in the pit below.

(13) Sacrificial layer removal:

according to the specificity of the selected sacrificial materials, adopting a specific technical means to selectively remove all the sacrificial layer materials filled in the pits so as to form a required cavity structure; thus preparing the required MEMS infrared light source.

As a further improvement of the present invention, in the step (1), the substrate material is selected from silicon, and a (100) crystal plane of the silicon is taken as a surface to be processed. The mask layer is made of any one of silicon oxide, silicon nitride, cr, au, pt and NiCr alloy.

As a further improvement of the present invention, in the step (3), TMAH aqueous solution, KOH aqueous solution, naOH aqueous solution, mixed aqueous solution of ethylenediamine and catechol, NH ₄ Any one of the OH aqueous solutions is used as an anisotropic etching solution; the depth of the etching is controlled to be 1-50 μm.

As a further improvement of the present invention, in the step (4), the reflective layer is a single metal plating layer made of one material of Ag, au, cu, al. Or the reflecting layer is deposited layer by adopting various materials in Ag, au, cu, al to prepare the composite metal coating. Or preparing a dielectric film Bragg plating layer as a required reflecting layer.

As a further improvement of the invention, in the step (6), the material of the sacrificial layer is selected from SiO ₂ One of phosphosilicate glass, silica gel, polyimide, SU-8, polydimethylsiloxane (PDMS), gelatin, polyethylene glycol, parylene, and benzocyclobutene.

Correspondingly, in the step (13), a solvent or a solution capable of directionally corroding the sacrificial layer material is adopted as a selective corrosive liquid for carrying out immersion treatment, the corrosive liquid is diffused into the cavity through the removing window, and the sacrificial layer material in the cavity is completely removed. The product is also cleaned and dried after the sacrificial layer is removed.

As a further improvement of the present invention, the polishing treatment in step (5) adopts a wet etching or chemical mechanical polishing method; in the step (7), polishing treatment is performed by a dry etching or chemical mechanical polishing method.

As a further improvement of the invention, the supporting layer in the step (8) is generated by adopting a physical vapor deposition or chemical vapor deposition process; the generated supporting layer is a single plating layer formed by silicon oxide or silicon nitride, or a multi-layer composite plating layer formed by depositing silicon oxide or silicon nitride layer by layer according to a preset sequence.

As a further improvement of the present invention, in the step (9), the heat-generating electrode layer is generated by physical vapor deposition or chemical vapor deposition process; the material of the heating electrode layer is selected from Pt, mo, niCr alloy, polysilicon and SiC, cu, W, hfB ₂ PtSi and SnO ₂ Any one of the following.

In order to improve the interfacial adhesion strength between the support layer and the heating electrode layer, in a more optimized scheme of the invention, a transition layer made of a specific material can be deposited on the surface of the support layer; and then the required heating electrode layer is generated again. The transition layer is selected from any one of Ti, cr and Ni according to the materials of the heating electrode layer and the supporting layer.

As a further improvement of the present invention, in the step (10), the heat-generating electrode pad is electrically connected to the heat-generating electrode layer, and the material for preparing the heat-generating electrode pad is selected from any one of AlSi alloy, au, al, niCr alloy, and NiV alloy.

As a further improvement of the present invention, the desired infrared emission layer is prepared in step (11) by a material of high infrared emissivity. The thickness of the prepared infrared emission layer is 50-1000nm. Wherein the material with high infrared emissivity comprises NiCr alloy, tiN, tiAlN, amorphous carbon, siC, niCrO compound and ZrO ₂ 、HfO ₂ 、La _1-x Ca _x CrO ₃ (0.ltoreq.x.ltoreq.0.5) and any one or more of the carbon nanotubes.

In particular. In the optimized scheme of the invention, the emission surface of the processed infrared emission layer is in a rough surface structure.

As a further improvement of the invention, when the prepared infrared emission layer has conductivity, a step for preparing the isolation layer is added between the steps (9) and (10). And after preparing the isolation layer, the step of preparing the heating electrode pad of the step (10) needs to remove the isolation layer of a partial area for setting the heating electrode pad by a photoetching stripping method so that the heating electrode pad is electrically connected with the heating electrode layer below; and in the step (11), the infrared emission layer is positioned on the upper surface of the isolation layer.

Specifically, the isolation layer is formed by adopting a physical vapor deposition or chemical vapor deposition process, and the material is one or a combination of any more of silicon oxide, silicon nitride and aluminum oxide.

As a further improvement of the invention, a step of preparing a protective layer is added between the step (11) and the step (12), and the prepared protective layer completely covers the upper surfaces of the infrared emission layer, the infrared electrode layer and the supporting layer.

The protective layer is formed by adopting physical vapor deposition or chemical vapor deposition process, and the material is selected from any one or a combination of more of silicon oxide, silicon nitride, aluminum oxide and hafnium oxide.

The technical scheme provided by the invention has the following beneficial effects:

the preparation method provided by the invention can be used for producing a special substrate, a supporting layer, a heating electrode layer and an infrared emission layer; and a cavity with a special shape is arranged between the substrate and the supporting layer, and MEMS infrared light sources with reflecting layers with specific shapes are distributed in the cavity. The MEMS light source with the special structure has high processing difficulty, and corresponding products are difficult to manufacture by adopting the conventional lamination processing technology; the invention particularly develops a manufacturing process special for producing the new product.

The MEMS infrared light source manufactured by the process improves the structure of the substrate of the traditional light source, a pit with a special shape is formed above the substrate, a cavity below the heating electrode layer and the infrared emission layer is formed between the pit and the supporting layer, and a complete reflection layer is formed on the wall surface of the pit. The MEMS infrared light source with the special structure can simultaneously inhibit ineffective heat conduction of the device and energy consumption generated by ineffective infrared radiation, reduce the heat capacity of the device and further greatly improve the photoelectric conversion efficiency of the device.

In addition, the MEMS infrared light source with the special structure provided by the invention also has strong thermal stability and structural strength; the lifetime and various weather resistance of the device are also enhanced. Compared with the traditional device, the device has very outstanding performance advantages, and is suitable for large-scale commercial popularization.

Drawings

Fig. 1 is a schematic diagram of a longitudinal section structure of a MEMS infrared light source prepared by a substrate hollowing technology in the background art.

Fig. 2 is a schematic diagram of a longitudinal section structure of a MEMS infrared light source with a reflective layer disposed at the bottom of a hollowed-out substrate in the background art.

Fig. 3 is a schematic diagram of the overall structure of the MEMS infrared light source provided in embodiment 1 of the present invention.

Fig. 4 is a schematic structural view of a substrate containing pits of the MEMS infrared light source provided in embodiment 1 of the present invention.

Fig. 5 is a schematic cross-sectional view of the MEMS infrared light source according to embodiment 1 of the present invention.

Fig. 6 is a layered exploded view of a specific structure of the MEMS infrared light source provided in embodiment 1 of the present invention.

Fig. 7 is a schematic cross-sectional view of a MEMS infrared light source including a transition layer according to embodiment 1 of the present invention.

Fig. 8 is a schematic cross-sectional view of a MEMS infrared light source with an isolation layer according to embodiment 1 of the present invention.

Fig. 9 is a schematic cross-sectional view of the MEMS infrared light source with a protective layer according to embodiment 1 of the present invention.

Fig. 10 is a method for manufacturing the MEMS infrared light source in embodiment 1 provided in embodiment 2 of the present invention.

FIG. 11 is a schematic cross-sectional structure of the MEMS infrared light source of FIG. 5 from a side view, from which a sacrificial window inside the support layer can be seen in longitudinal section.

FIG. 12 is a schematic diagram of the product junction obtained after the end of the "mask processing of substrate" step in example 2.

FIG. 13 is a schematic diagram of the product junction obtained after the end of the "etching window preparation" step in example 2.

FIG. 14 is a schematic diagram of the product junction obtained after the "anisotropic etching" step in example 2 was completed.

FIG. 15 is a schematic diagram of the product junction obtained after the completion of the "reflective layer preparation" step in example 2.

FIG. 16 is a schematic diagram of the product junction obtained after the end of the "one-shot polishing" step in example 2.

FIG. 17 is a schematic diagram of the product junction obtained after the end of the "sacrificial layer preparation" step in example 2.

FIG. 18 is a schematic diagram of the product junction obtained after the end of the "secondary polishing" step in example 2.

FIG. 19 is a schematic diagram of the product junction obtained after the completion of the "support layer preparation" step in example 2.

FIG. 20 is a schematic diagram of the product junction obtained after the completion of the "preparation of heat-generating electrode layer" step in example 2.

FIG. 21 is a schematic diagram of the product junction obtained after the completion of the "separator preparation" step in example 2.

Fig. 22 is a schematic diagram of the product junction obtained after the completion of the "heat-generating electrode pad preparation" step in example 2.

FIG. 23 is a schematic diagram of the product junction obtained after the completion of the "preparation of infrared emission layer" step in example 2.

FIG. 24 is a schematic diagram of the product junction obtained after the end of the "protective layer preparation" step in example 2.

FIG. 25 is a schematic diagram of the product junction obtained after the end of the sacrificial window preparation step in example 2.

FIG. 26 is a schematic diagram of the product junction obtained after the end of the sacrificial layer removal step in example 2.

Marked in the figure as:

100. pit; 101. a substrate; 201. masking; 301. a reflective layer; 401. a sacrificial layer; 501. a support layer; 601. a heat-generating electrode layer; 701. an isolation layer; 801. a heat-generating electrode pad; 901. an infrared emission layer; 1001. a protective layer; 1002. a sacrificial window; 5011. and a transition layer.

Detailed Description

The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

Example 1

Fig. 1 and 2 are schematic views of longitudinal cross-sectional structures of MEMS infrared light sources in two prior art solutions mentioned in the background. Both of these two solutions are the same as the conventional infrared light source, and include a substrate 101, a supporting layer 501, a heat-generating electrode layer 601, an isolation layer 701, an infrared emission layer 901, and a heat-generating electrode pad 801. Devices of this stacked structure can be fabricated by a process of sequentially generating different functional layers on the substrate 101. The substrate 101 is a base for forming each functional layer above, and has effects of stably attaching each layer, providing a good supporting effect, and the like. The supporting layer 501 is an intermediate layer between the substrate 101 and the heat-generating electrode layer 601, and has a good supporting effect, and particularly when the substrate 101 is subjected to special etching, the supporting layer 501 can have a good supporting effect on each functional layer above, and the load due to the compressive stress of each part above can be uniformly dispersed.

The heating electrode layer 601 is connected with the heating electrode bonding pad 801, the heating electrode bonding pad 801 is used for connecting a lead wire to supply power to the heating electrode, the heating electrode layer 601 is a functional layer capable of converting electric energy into self internal energy, and the heating electrode layer 601 can rapidly heat in a conductive state; and infrared radiation is generated outwardly. The infrared emitting layer 901 is a functional layer made of a material with ultra-high infrared emissivity, and the functional layer emits the received internal energy in the form of infrared radiation at a high temperature.

Since the main function of the heat-generating electrode layer 601 is to generate infrared radiation and heat the infrared emission layer 901 directly contacting the upper side by means of heat conduction, the infrared emission layer 901 can maintain an emission state. But since the support layer 501 and the bottom surface of the infrared electrode layer are also in direct contact, the heat generated by heating the electrode layer is also conducted to the support layer 501 and to the portion of the substrate 101. For the MEMS infrared light source, the energy consumption of the heat conducted to the supporting layer 501 and the substrate 101 is not converted into effective infrared radiation, and the ineffective power consumption (a type of loss) of the device can significantly reduce the photoelectric conversion efficiency of the MEMS light source. On the other hand, the infrared radiation generated by the infrared emission layer 901 radiates both upward and downward, and the upward radiation is effective radiation emitted, while the downward radiation cannot be modulated and applied effectively, and is ineffective radiation (two-type loss), and the generated ineffective radiation is another important cause for reducing the photoelectric conversion efficiency of the device.

The technical scheme provided in fig. 1 mainly comprises the steps of hollowing out the bottom of a substrate 101 corresponding to an infrared emission layer 901 on the basis of a multilayer stacked MEMS infrared light source, reducing the contact surface between the hollowed substrate 101 and a supporting layer 501, and greatly reducing the volume and the mass of the substrate 101; and further, the energy loss generated by heat conduction during the operation of the device can be effectively reduced, namely, the loss of the device is reduced. Meanwhile, since the hollowed-out portion is located on the bottom surface of the substrate 101, the processing and forming of each functional layer above are not affected. But it should be noted that: since the substrate 101 plays a supporting role in the device processing process, the substrate 101 must be hollowed out by photolithography, etching, and the like after all the functional layers are formed.

The technical scheme of fig. 2 is a further improvement on the scheme of fig. 1 proposed by the inventor. The improvement is mainly that a reflecting layer 301 is added on the hollowed-out part of the bottom surface of the substrate 101; the reflective layer 301 is made of a material having a high reflectivity to infrared radiation. Thus, the reflective layer 301 can reflect downward infrared radiation generated by the upper infrared emitting layer 901 back, converting some of the ineffective radiation into effective radiation. Thereby reducing the second class loss of the device. The solution of fig. 2 has some drawbacks while reducing the second class loss of the device. The details of the disadvantages of the solution of fig. 2 will be specifically described when the advantages of the improved solution provided by the present embodiment are described later.

Specifically, the embodiment further provides a novel MEMS infrared light source with improved photoelectric conversion efficiency based on the technical schemes corresponding to fig. 1 and 2. The overall structure of the light source provided in this embodiment is shown in fig. 3, and the MEMS infrared light source includes a substrate 101, a supporting layer 501, a heating electrode layer 601, and an infrared emission layer 901 stacked in sequence from bottom to top; and two heat-generating electrode pads 801 electrically connected to the heat-generating electrode layer 601. It should be emphasized that the text and picture portions of fig. 3 and the following description of the present embodiment are mainly exemplified in the form of rectangular light sources. However, the shape of the light source is not a limiting feature of the embodiment, and the embodiment is not limited to any one shape. The MEMS infrared light source with improved photoelectric conversion efficiency can adopt a rectangular light source, a round light source, an oval shape, a strip shape and any other irregular shape.

The main difference between the technical scheme provided by the embodiment and the existing scheme is that: as shown in fig. 4, the upper surface of the substrate 101 of the MEMS infrared light source of the present embodiment is provided with a concave pit 100, and the pit 100 includes a horizontal bottom surface and a sloping side wall. The substrate 101 is in a four-sided solid support structure and is connected with the upper supporting layer 501, and a cavity structure is formed between the two. As can be seen in fig. 5, in the MEMS infrared light source provided in this example, the surrounding area of the upper opening of the pit 100 is covered with the infrared emission layer 901. I.e. the distribution area of the upper opening of the pit 100 can completely cover the upper infrared emission layer 901, it is understood that the entire infrared emission layer 901 in the light source of the present embodiment is "suspended" above the pit 100.

Referring to fig. 6, in the substrate 101 of the MEMS infrared light source provided in this embodiment, the enclosing area of the upper opening of the pit 100 is located at the inner sides of the two heat-generating electrode pads 801, and the distribution area of the upper opening enclosing area of the pit 100 along the extending direction of at least one end of the heat-generating electrode pads 801 exceeds the length range of the heat-generating electrode pads 801. In popular terms, taking a rectangular light source as an example, the length of the pit 100 in the extending direction parallel to the heat generating electrode pad 801 is longer than the upper infrared emission layer 901 (and the heat generating electrode layer 601). And the width of the pit 100 in the direction perpendicular to the extension direction of the heat generating electrode pad 801 is shorter than that of the underlying infrared emitting layer 901 (and the heat generating electrode layer 601). When the light source takes other shapes, this limitation should be satisfied, namely: the dimple 100 must be "sandwiched" between two heat-generating electrode pads 801, but slightly longer than the heat-generating electrode pads 801.

Meanwhile, as shown in fig. 5, the area of the supporting layer 501 of the MEMS infrared light source provided in the present embodiment is larger than the upper opening of the pit 100 and the heat generating electrode layer 601. And as shown in fig. 3 and 6, at least one sacrificial window 1002 is provided through the support layer 501, the sacrificial window 1002 being in communication with the recess 100 in the underlying substrate 101. The distribution position of the sacrificial window 1002 is tangential to or separated from the distribution position of the heat-generating electrode layer 601. Specifically, the support layer 501 completely "covers" the pits 100 on the substrate 101. And the heat-generating electrode layer 601 is covered just above the support layer 501 just opposite the pit 100. Meanwhile, a sacrificial window 1002 communicating with the pit 100 below is provided in the support layer 501, and the sacrificial window 1002 must be distributed at a position on the support layer 501 that is not blocked by the heat-generating electrode layer 601 and the infrared emission layer 901.

In the MEMS infrared light source provided in this embodiment, the bottom surface and the side wall of the pit 100 of the substrate 101 are provided with the complete reflective layer 301, and the reflective layer 301 is made of a material having a high reflectivity for infrared rays in the wavelength range of 2-14 micrometers.

The working principle and performance advantages of the MEMS light source product are described in detail below in conjunction with the above technical features of the MEMS light source provided in this embodiment.

First, the light source provided in this embodiment has a "hollowed-out" structure similar to the scheme of fig. 2, i.e., the pit 100 in this case. Therefore, the substrate 101 of the present embodiment can also have the effect of reducing the heat capacity of the MEMS infrared light source and reducing the heat conduction of the heat-generating electrode layer 601 to the substrate 101 portion. Thereby reducing one type of loss of the device. However, the pit 100 of the present embodiment is different from the "hollowed-out" manner of the substrate 101 in fig. 2. In particular, the pit 100 in this case is located above the substrate 101, which results in a cavity between the substrate 101 and the support layer 501. The functions of the hollow cavity structure of the implementation comprise the following two points: 1. the cavity can effectively block the downward heat conduction path of the combined body formed by the heating electrode layer 601 and the supporting layer 501, and has the effect of reducing heat radiation again. 2. The gaseous medium in the cavity is also equivalent to a thermal insulation quilt formed by a layer of heat bad conductor, so that heat is prevented from being transferred to the substrate 101 and dissipated from a larger surface of the substrate 101.

Next, in this case, the pit 100 has a small shape with a large upper opening and a small lower opening, and as shown in fig. 4 to 6, the longitudinal section of the pit 100 is substantially in the shape of a "canal". The desired reflective layer 301 is created in view of the walls and bottom of the pit 100. Such sloped pit 100 walls thus include at least the following advantages:

(1) The reflective layer 301 material is primarily created by a sputtering or evaporation process. The sloped walls of the pit 100 may facilitate better deposition of the reflective layer 301 material. The dispersion effect and the continuity of the reflective layer 301 in the pits 100 are improved, resulting in a uniform and complete reflective layer 301. The reflection effect of the reflective layer 301 on infrared radiation is enhanced.

(2) The horizontal bottom surface of pit 100 corresponds to a planar mirror that can completely reflect the bottom-facing radiation of the upper infrared emitting layer 901 onto the upper infrared emitting layer 901.

(3) Just above the sloped wall surface of the pit 100 is the pressed surface of the supporting layer 501, and is also the bearing fulcrum of the heat-generating electrode pad 801. In the scheme, the slope wall surface as shown in fig. 5 is equivalent to a trapezoid 'embankment' with a small upper bottom and a large lower bottom, and good pressure resistance and impact resistance effects are achieved. The MEMS infrared light source device has stronger anti-seismic and pressure-resistant performances; the service life of the product is prolonged.

(4) The pit 100 is formed by a process such as anisotropic etching or photolithography. The special shaped pit 100 is also just suitable for the chemical corrosion and the laser etching process characteristics, and is very easy to process; the production cost of the product can be reduced.

In addition, in the technical scheme of providing the MEMS infrared light source, the distribution area of the pit 100 (i.e. the distribution area of the reflective layer 301) is just "shrunk" inside the two heat-generating electrode pads 801, which makes the heat-generating electrode pads 801 just overlap the slope of the pit 100, so as to maintain a good supporting effect. The infrared emission layer 901 between the heat-generating electrode pads 801 can be completely suspended above the pit 100, so that all bottom radiation of the infrared emission layer 901 can reach the emission layer in the pit 100, thereby improving the reflectivity of the bottom radiation and maximally inhibiting the power of the second class loss.

A special emphasis is required: in the technical solution provided in this embodiment, the substrate 101 has a cavity formed by the pit 100 between the substrate and the supporting layer 501; the reflective layer 301 provided on the cavity wall has the following advantages: since the reflective layer 301 is isolated from the cavity in the middle of the heating region of the MEMS light source, when the MEMS is frequently turned on and off, the temperature of the reflective layer 301 is relatively low and stable, so that the thermal expansion between the substrate 101 and the reflective layer 301 is not obvious, and the reflective layer 301 is not obviously deformed or separated. That is, in the solution of this embodiment, the heat resistance of the reflective layer 301 is better, the reflective layer 301 is not easy to be damaged even if the device is used for a long time, the service life of the device is longer, and the optimal photoelectric conversion performance of the device can be maintained to the greatest extent.

For the prior art in fig. 2, when the MEMS infrared light source is frequently turned on and off, the reflective layer 301 is in direct contact with the supporting layer 501 (corresponding to direct contact with the heat generating region of the MEMS), at this time, the temperature change of the reflective layer 301 during use is severe, and the substrate 101 and the reflective layer 301 may be thermally expanded to different extents, so that the adhesion effect of the interface therebetween is poor, and the reflective layer 301 may be damaged when severe. Since the reflective layer 301 is located under the substrate 101 in fig. 2, once the reflective layer 301 is broken, it may cause the reflective layer 301 to partially fall off, and the uniformity and integrity of the reflective layer 301 to be destroyed, losing the reflection of the infrared radiation. And thus the photoelectric conversion efficiency of the MEMS infrared light source is reduced.

Meanwhile, one of the important effects of the processes such as cavity and substrate 101 emptying is to reduce the heat capacity of the device, so as to improve the photoelectric conversion efficiency of the device. (note: heat capacity refers to the ability of an object to absorb and store heat energy; the higher the heat capacity, the lower the temperature rise amplitude of absorbing the same heat energy, the heat capacity is related to the volume/mass of the object, the type of material, and other properties.) while the reflective layer 301 of the present case is located under the cavity and is not in contact with the support layer 501, so there is little effect on the heat capacity of the device. Whereas in the solution of fig. 2 the reflective layer 301 is in direct contact with the support layer 501, the reflective layer 301 increases the heat capacity of the device. This is disadvantageous for improving the photoelectric conversion efficiency of the device.

Finally, the primary purpose of the sacrificial window 1002 with a special shape and location reserved on the support layer 501 in this embodiment is to facilitate the processing of the product. As is well known, the various functional layers above the substrate 101 are actually a micro-or nano-scale plating or film. These functional layers cannot be grown directly on the upper surface of the substrate 101 with the pits 100; otherwise, each functional layer is provided with pits and cannot be in a plane state. Thus, the pit 100 can be processed only after the formation of the respective functional layers. However, it is not technically feasible to create a pit 100 in the "center" of the device by etching after the functional layer is formed.

In order to solve the problem, the invention designs a special production process which is specially used for producing the MEMS infrared light source with the special structure provided by the embodiment. One key technical means of the processing technology provided in this embodiment is to use a material with a certain specificity, which can be selectively removed by a specific method, as the sacrificial layer 401, fill the sacrificial layer 401 in the processed pit 100 in advance, and remove the material of the sacrificial layer 401 from the pit 100 after each functional layer above the pit 100 is formed. The reserved sacrificial window 1002 on the support layer 501 is used to remove the material of the sacrificial layer 401 in the pit 100.

In particular, the sacrificial window 1002 of the present embodiment is designed to communicate with both the recess 100 in the underlying substrate 101, facilitating removal of the sacrificial layer 401 material in the recess 100. But also needs to be tangent to or separated from the distribution position of the heating electrode layer 601; and further, the integrity of the upper functional layers is not damaged, and the functions of the upper functional layers are not influenced. While also avoiding blocking or obscuring the sacrificial window 1002 by the overlying functional layers.

In practical applications, at least one of the sacrificial windows 1002 may be formed by any shape of through-hole, such as circular hole, bar, etc. In the most preferred embodiment, the sacrificial windows 1002 should be symmetrically positioned on the support layer 501 on either side of the heat-generating electrode layer 601. This ensures that the support layer 501 is balanced by stress strain, improving production yields and service life. To be popularized, the best scheme of the MEMS infrared light source provided by the embodiment also maintains good structural symmetry in the design of the whole structure (including each functional layer). So as to improve the structural strength, stress resistance and various performances of the device.

In the MEMS infrared light source provided in this embodiment, the depth of the cavity structure is 1-50. The cavity of the device can exert the best technical effect under the depth range condition. When the cavity depth is lower than the preferable range, the substrate 101 is almost equivalent to the pit-free region 100, and the support layer 501 and the substrate 101 are very close to each other, so that the above technical effect cannot be exerted. When the cavity depth is greater than the preferred interval, the difficulty of processing is increased when the cavity depth is too large, and the reflection effect of the reflective layer 301 on infrared radiation is deteriorated.

In this embodiment, the reflective layer 301 may be a metal plating film prepared from any one of Ag, au, cu, al. Or a dielectric film bragg reflective layer 301 may be employed. Or a multi-layer composite film formed by stacking any plurality of single metal coating films according to a specified sequence. Ag. Au, cu, al are all materials with high infrared reflectivity. The dielectric film Bragg emission layer is a common laminated optical film which is formed by dielectric materials with high and low refractive indexes according to a certain sequence, can generate strong reflection for infrared rays with specific wavelength or broad spectrum infrared rays through the design of the film layer, and can also be used as a reflection film in the embodiment.

Considering that the cost of different materials is different, the cost of the Ag and Au reflecting layer 301 is much higher than that of Cu and Al; in practical applications, different materials may be layered on the substrate 101 as needed to form the composite reflective layer 301 film. For example, cu is used as a base of the reflective layer 301, and a thin Au plating layer is formed on the upper surface to form the desired reflective layer 301. The composite reflecting layer 301 not only can maintain higher infrared radiation reflectivity, but also can achieve better technical effects in the aspects of the production cost of the MEMS infrared light source and the comprehensive performances of material strength, toughness, wear resistance and the like.

The substrate 101 material in this embodiment includes silicon and other materials that can be used as the infrared light source substrate 101, such as quartz, glass, sapphire, and the like. When silicon is used as a material of the substrate 101, a silicon (100) surface is generally used as a working surface for forming the pit 100 and each functional layer, and the pit 100 shape of an inverted trapezoid (large opening and small bottom surface) can be realized by anisotropic etching of silicon very easily.

In this embodiment, the support layer 501 is made of a single material composed of silicon oxide or silicon nitride or a multi-layer composite material composed of two materials which are arranged alternately in an overlapping manner. Silicon oxide and silicon nitride are inorganic nonmetallic materials with high strength, large hardness, poor thermal conductivity, insulation, high temperature resistance and corrosion resistance; is very suitable for being used as a material of the supporting layer 501 in the MEMS light source.

The infrared emission layer 901 in the MEMS light source of this embodiment is made of a material with high infrared emissivity, and has a thickness of 50-1000nm. Wherein the material with high infrared emissivity comprises any one or a mixture of a plurality of NiCr alloy, tiN, tiAlN, amorphous carbon, siC, niCrO compound, zrO2, hfO2, la1-xCaxCrO3 (x is more than or equal to 0 and less than or equal to 0.5) and carbon nano tubes.

In particular, the emission surface of the infrared emission layer 901 in this embodiment is a rough surface structure. The rough surface structure improves the infrared emission capability of the MEMS infrared light source.

In this embodiment, the heating electrode layer 601 is made of any one of Pt, mo, niCr alloy, polysilicon, siC, cu, W, hfB2, ptSi, and SnO 2; all the materials are existing materials for manufacturing the resistance heating unit, and the heating electrode layer 601 prepared by the materials can convert electric energy into internal energy for heating more efficiently after being electrified.

As shown in fig. 7, in a more optimized technical solution of the present invention, a transition layer 5011 for improving the adhesion of the interface between the heat-generating electrode layer 601 and the supporting layer 501 may be further added. The transition layer 5011 is selected from any one of Ti, cr, and Ni according to the materials of the heat generating electrode layer 601 and the support layer 501. For example, when the heating electrode layer 601 is made of Pt material and the supporting layer 501 is made of SiO2 material, an ultrathin Cr coating layer can be added on the upper surface of the supporting layer 501 in the manufacturing process, so that the interfacial adhesion strength of the two layers is significantly improved. The heating electrode layer 601 and the supporting layer 501 are prevented from being displaced in the use process, and the comprehensive performance of the product is improved.

In this embodiment, two heat-generating electrode pads 801 are parallel to each other and electrically connected to the upper surface of the heat-generating electrode layer 601; an infrared emission layer 901 is located between two heat-generating electrode pads 801. The heat-generating electrode pad 801 is made of any one of AlSi alloy, au, al, niCr alloy, and NiV alloy. The main function of the heat-generating electrode pad 801 is to introduce electron migration of directional transmission on the heat-generating electrode layer 601, thereby causing the heat-generating electrode layer 601 to generate heat. Therefore, the material of the heat generating electrode pad 801 in this embodiment is a material with high conductivity, high thermal stability, and high solderability.

As shown in fig. 8, in a more optimized solution of the present embodiment, the heat-generating electrode layer 601 and the infrared emission layer 901 are further provided with an isolation layer 701 for blocking the electric conduction effect therebetween. The material of the isolation layer 701 is one or a combination of any more of silicon oxide, silicon nitride and aluminum oxide.

The isolation layer 701 is generally used only when the material of the infrared emission layer 901 is also conductive, and if the infrared emission layer 901 is produced using an insulating material such as ZrO2, hfO2, la1-xCaxCrO3 (0.ltoreq.x.ltoreq.0.5), or the like, the isolation layer 701 does not need to be provided between the heat generating electrode layer 601 and the infrared emission layer 901. The isolation layer 701 operates as follows: when the infrared emission layer 901 is made of a conductive material, if the infrared emission layer is not electrically isolated from the heating electrode layer 601, then current will also pass through the infrared emission layer 901, which will cause a change in the resistance of the heating electrode layer 601, and under the condition that the applied voltage is the same, the temperature obtained by the MEMS light source will deviate from the design value greatly, and the working requirement cannot be satisfied. The above problems can be solved by providing an insulating isolation layer 701 therebetween.

As shown in fig. 9, in a more optimized solution of the present embodiment, the infrared light source is further provided with a protective layer 1001, and the protective layer 1001 covers the area of the MEMS infrared light source upper surface except for the heat generating electrode pad 801. The protection layer 1001 plays a role in protecting the internal structure, and in this embodiment, according to the performance requirement on the device, the protection layer 1001 is mainly made of a material with stronger infrared radiation transmittance and higher strength and hardness; the material with stronger corrosion resistance and heat resistance is prepared. Specifically, the material of the protective layer 1001 selected in this embodiment includes any one or a combination of plural kinds of silicon oxide, silicon nitride, aluminum oxide, hafnium oxide.

Example 2

The present embodiment further provides a manufacturing method dedicated to the production of the MEMS infrared light source of embodiment 1 having the improved photoelectric conversion efficiency of the special structure. The manufacturing process designed by the embodiment adopts the following steps according to the core structural characteristics of the device: the pit 100 is etched, the pit 100 is filled up by the material of the sacrificial layer 401, each functional layer is generated on the plane, and finally, after the functional layer is completely processed, the sacrificial layer 401 in the pit 100 is replaced by the sacrificial window 1002 which is communicated with the pit 100, so that the product manufacturing is completed. In particular, the process provides for the selective removal of the sacrificial layer 401 by disposing a sacrificial window 1002 on the support layer 501 proximate to the pit 100 in the substrate 101.

Scheme one

As shown in fig. 10, for a substrate 101, a support layer 501, a heat-generating electrode layer 601, and an infrared emission layer 901 only; and a cavity with a special shape is arranged between the substrate 101 and the supporting layer 501, and the cavity is internally distributed with MEMS infrared light sources of the reflecting layer 301 with a special shape. The manufacturing method provided by the embodiment comprises the following process steps:

(1) Mask processing of a substrate:

a substrate 101 is provided, and a predetermined amount of mask 201 layer material is deposited on the surface to be processed of the substrate 101 to form a desired mask 201 layer.

In particular, the substrate 101 material of the present embodiment may be selected from various types of materials existing. Among them, the preferred material of the substrate 101 is silicon, and a silicon (100) crystal plane is taken as a surface to be processed. The material of the mask 201 layer is selected from any one of silicon oxide, silicon nitride, cr, au, pt, and NiCr alloy.

(2) Preparing a corrosion window:

a portion of the mask 201 layer on the surface to be processed is removed by photolithography techniques to form an etch window in the substrate 101, in accordance with a predetermined window size and shape. The etching window is designed in a targeted manner according to the shape of the upper opening of the pit 100 of the designed MEMS infrared light source, and the area exposed below the etching window is the area of the substrate 101 to be etched.

(3) Anisotropic etching:

the substrate 101 is chemically etched by an anisotropic etching process to form a pit 100 in the substrate 101, which is recessed into the substrate 101 and has a gradually decreasing diameter, in an etching window region.

In this example, any one of TMAH aqueous solution, KOH aqueous solution, naOH aqueous solution, ethylenediamine and catechol mixed aqueous solution, and NH4OH aqueous solution was used as the desired anisotropic etching liquid for the silicon substrate 101. During the etching process, it is necessary to control the etching process so that the depth of etching is controlled to be 1 to 50.

(4) Preparing a reflecting layer:

a physical vapor deposition process is used to deposit a predetermined amount of reflective layer 301 material in the pits 100 on the surface of the substrate 101 to form the desired reflective layer 301. The reflective layer 301 is a single metal coating made of one material of Ag, au, cu, al. Or the reflective layer 301 is deposited layer by layer using a variety of materials in Ag, au, cu, al to form a composite metal coating. Or a dielectric film bragg plating layer is prepared as the desired reflective layer 301.

(5) Primary polishing:

the surface to be processed of the substrate 101 is polished to remove the surface plating layer of the surface of the substrate 101 in the areas other than the pits 100, including the etching mask 201 layer material and the reflective layer 301 material. The polishing treatment adopts wet etching or chemical mechanical polishing. When wet etching is used, the etching mask 201 layer is removed and the reflective layer 301 material is stripped off above it by selective etching of the etching mask 201 layer and other structures (reflective layer 301 and substrate 101), thus leaving the reflective layer 301 in the pit 100 and exposing the upper surface of the substrate 101 in areas outside the pit 100. When chemical mechanical polishing is used, the material of the reflective layer 301 and the material of the etching mask 201 layer in the area outside the pit 100 are removed, and the upper surface of the substrate 101 in the area outside the pit 100 is exposed, while the reflective layer 301 in the pit 100 is maintained.

(6) Sacrificial layer preparation:

the recesses 100 in the substrate 101 are filled with a sacrificial layer 401 material that can be selectively removed by any means. The material of the sacrificial layer 401 is selected from one of SiO2, phosphosilicate glass, silica gel, polyimide, SU-8, polydimethylsiloxane (PDMS), gelatin, polyethylene glycol, parylene and benzocyclobutene.

(7) Secondary polishing:

the surface to be processed of the substrate 101 filled with the material of the sacrificial layer 401 is subjected to a secondary polishing treatment so that the material of the sacrificial layer 401 in the pit 100 is kept flush with the surrounding surface of the substrate 101. The polishing treatment adopts a dry etching method or a chemical mechanical polishing method.

(8) Preparing a supporting layer:

the surface of the substrate 101 on the side containing the sacrificial layer 401 is provided with a support layer 501 which is required for generation, and the support layer 501 completely covers the substrate 101 and the sacrificial layer 401 below. The support layer 501 is formed by physical vapor deposition or chemical vapor deposition; the support layer 501 is formed by a single plating layer made of silicon oxide or silicon nitride, or a multi-layer composite plating layer made of silicon oxide or silicon nitride deposited layer by layer according to a preset sequence.

(9) Preparing a heating electrode layer:

a desired heat-generating electrode layer 601 is prepared on the surface of the support layer 501, the heat-generating electrode layer 601 being located at a position corresponding to the upper side of the pit 100 in the substrate 101. The heat-generating electrode layer 601 entirely covers the pit 100 on both left and right sides, and the pit 100 is uncovered in regions of both front and rear sides located inside the opposite pit 100. The heat-generating electrode layer 601 is generated by physical vapor deposition or chemical vapor deposition process; the material of the heat-generating electrode layer 601 is selected from any one of Pt, mo, niCr alloy, polysilicon, siC, cu, W, hfB2, ptSi, and SnO 2.

In order to improve the interfacial adhesion between the support layer 501 and the heat-generating electrode layer 601, in a more optimal embodiment, a transition layer 5011 made of a specific material may be deposited on the surface of the support layer 501; and then the desired heat-generating electrode layer 601 is regenerated. The transition layer 5011 is selected from any one of Ti, cr, and Ni according to the materials of the heat generating electrode layer 601 and the support layer 501.

(10) Preparing a heating electrode pad:

two mutually parallel long-strip-shaped heating electrode pads 801 which do not exceed the distribution area of the heating electrode layer 601 are prepared above the heating electrode layer 601. Wherein, the distribution area of the two heating electrode pads 801 is separated from or circumscribed with the surrounding area of the upper opening of the pit 100.

The heat-generating electrode pad 801 is electrically connected to the heat-generating electrode layer 601, and a material for preparing the heat-generating electrode pad 801 is selected from any one of AlSi alloy, au, al, niCr alloy, and NiV alloy.

(11) Preparing an infrared emission layer:

a desired infrared emission layer 901 is prepared above the heat-generating electrode layer 601 inside the heat-generating electrode pad 801. The infrared emission layer 901 is located in the wiring area of the four terminals of the heat generating electrode pad 801.

The desired infrared emissive layer 901 is prepared from a material of high infrared emissivity. The thickness of the prepared infrared emission layer 901 is 50-1000nm. Wherein the material with high infrared emissivity comprises any one or a mixture of a plurality of NiCr alloy, tiN, tiAlN, amorphous carbon, siC, niCrO compound, zrO2, hfO2, la1-xCaxCrO3 (x is more than or equal to 0 and less than or equal to 0.5) and carbon nano tubes.

In particular, in other more preferred embodiments, the emission surface of the processed infrared emission layer 901 is roughened.

(12) Sacrificial window preparation:

the material of the supporting layer 501 is etched by a photolithography technique, and on the basis of not damaging the upper heating electrode layer 601 and the infrared emission layer 901, at least one through sacrificial window is machined in a specific area, so as to expose the material of the sacrificial layer 401 in the pit 100 below. Fig. 11 is a schematic cross-sectional structure of the MEMS infrared light source of fig. 5 along two side views, so that the relative positional relationship between the sacrificial window and the supporting layer 501 and the pit 100 can be more intuitively seen.

(13) Sacrificial layer 401 removal:

according to the specificity of the selected sacrificial material, adopting a specific technical means to selectively remove all the materials of the sacrificial layer 401 filled in the pit 100 so as to form a required cavity structure; thus preparing the required MEMS infrared light source.

The solvent or solution capable of directionally corroding the material of the sacrificial layer 401 is used as selective corrosive liquid for immersion treatment, the corrosive liquid is diffused into the cavity through the sacrificial window, and the material of the sacrificial layer 401 in the cavity is completely removed. The product is also cleaned and dried after the sacrificial layer 401 is removed.

The final MEMS infrared light source comprises a substrate 101, a supporting layer 501, a heating electrode layer 601 and an infrared emission layer 901; and a cavity with a special shape is arranged between the substrate 101 and the supporting layer 501, and a reflecting layer 301 with a special shape is distributed in the cavity.

Scheme II

On the basis of the first embodiment, when the prepared infrared emission layer 901 has conductivity, a step of preparing the isolation layer 701 is added between the steps (9) and (10). And after the isolation layer 701 is prepared, the heat-generating electrode pad 801 preparing step of step (10) requires that the isolation layer 701 for setting a partial region of the heat-generating electrode pad 801 is first removed by a photolithographic lift-off method so that the heat-generating electrode pad 801 is electrically connected with the underlying heat-generating electrode layer 601; and in step (11), the infrared emission layer 901 is located on the upper surface of the isolation layer 701.

Specifically, the isolation layer 701 is formed by physical vapor deposition or chemical vapor deposition, and the material is one or a combination of any more of silicon oxide, silicon nitride and aluminum oxide.

The MEMS light source fabricated at this time has an overall structure including the substrate 101, the supporting layer 501, the heat-generating electrode layer 601, the infrared emitting layer 901, and the heat-generating electrode pad 801 from bottom to top. Wherein a cavity is arranged at the interface of the substrate 101 and the supporting layer 501, and a complete reflecting layer 301 is arranged on the inner wall of the cavity near the substrate 101.

Scheme III

On the basis of the second scheme, in order to improve weather resistance such as corrosion resistance of the product, a step of preparing the protective layer 1001 is added between the step (11) and the step (12), and the prepared protective layer 1001 completely covers the upper surfaces of the infrared emission layer 901, the infrared electrode layer and the supporting layer 501. And the sacrificial window opened in step (12) effectively removes both the protective layer 1001 and the support layer 501 at the same time, since the protective layer 1001 also covers over the support layer 501 where the sacrificial window region is opened.

In this embodiment, the protective layer 1001 is formed by physical vapor deposition or chemical vapor deposition, and the material is selected from any one or a combination of more of silicon oxide, silicon nitride, aluminum oxide, and hafnium oxide.

What needs to be specifically stated is: in the manufacturing method provided in this embodiment, the protective layer 1001 is not only the outer protective layer 1001 of the whole MEMS light source product produced. And also as an outer cladding layer covering the heat-generating electrode layer 601, the insulating layer 701 and the infrared emission layer 901 when the substrate 101 is removed by the selective etchant in step (13). At this time, the selective solvent can only enter the pit 100 of the substrate 101 from the sacrificial window. When the etchant is selected, a solvent which can etch the sacrificial layer 401 but does not affect the materials of the support layer 501, the substrate 101, the reflective layer 301, and the protective layer 1001 may be selected.

In order to more clearly demonstrate the manufacturing process provided in this embodiment, the following describes the complete manufacturing process of the complete product including the substrate 101, the supporting layer 501, the heat-generating electrode layer 601, the isolation layer 701, the infrared emission layer 901, the heat-generating electrode pad 801, and the protective layer 1001 in combination with a series of continuous diagrams from fig. 12 to 26. Figures 13-26 show the morphology of the semifinished product or product obtained after completion of the various manufacturing process steps.

1. Mask processing of a substrate

After the mask 201 on the substrate 101 is formed, the mask 201 is shown on the upper layer of the substrate 101, as generally shown in fig. 12.

2. Corrosion window preparation

The etch window was successfully prepared and the mask 201 included a notch therein, as generally shown in fig. 13.

3. Anisotropic etching

After the anisotropic etching, the substrate 101 is not affected at the mask 201, the exposed substrate 101 is etched, and since the anisotropic etching is adopted, the etched pit 100 is in a state of being large in upper opening and small in lower opening as in fig. 14.

4. Preparation of reflective layer

Since the reflective layer 301 is prepared by a sputtering or evaporation deposition process in this embodiment, the reflective layer 301 material is deposited on both the upper surface of the substrate 101 and the mask 201 in fig. 15.

5. One-time polishing

The purpose of the primary polishing is to remove the mask 201 material and reflective layer 301 material on the surface of the substrate 101 except at the pits 100. The state as in fig. 16 is reached.

6. Sacrificial layer preparation

The sacrificial layer 401 is filled directly into the pit 100, and in order to ensure that the sacrificial layer 401 is completely filled, the sacrificial layer 401 is typically "overflowed" to some extent, as shown in fig. 17.

7. Secondary polishing

The objective of the secondary polishing is to remove the overflowed sacrificial layer 401, re-exposing the substrate 101 outside the pits 100; the effect of fig. 18 is achieved so that a point can be worn off properly during polishing, ensuring that the material of the sacrificial layer 401 in the recess 100 remains flush with the surrounding substrate 101 surface.

8. Preparation of support layer

In fig. 19, it can be seen that a complete support layer 501 is grown over the sacrificial layer 401 and the substrate 101.

9. Preparation of heating electrode layer

As can be seen in fig. 20, a heat-generating electrode layer 601 is formed above the support layer 501, the heat-generating electrode layer 601 being shorter than the support layer 501. Meanwhile, at the current viewing angle, the lengths of the left and right sides of the electrode layer are longer than those of the pit 100, but at the viewing angles of the front and rear sides corresponding to the drawing, in order to reserve the sacrificial window, the heat-generating electrode layer 601 is rather slightly shorter than the pit 100.

10. Preparation of isolation layer

In this embodiment, a complete isolation layer 701 is disposed above the heat-generating electrode layer 601, and as shown in fig. 21, the isolation layer 701 is as large as the heat-generating electrode layer 601.

11. Preparation of heating electrode bonding pad

In this embodiment, the heat generating electrode pad 801 is prepared on the isolation layer 701, as can be seen in fig. 22, and the isolation layer 701 at the heat generating electrode pad 801 is removed, so that the heat generating electrode pad 801 is directly electrically connected to the underlying heat generating electrode layer 601. Note that the heat generating electrode pad 801 is actually elongated, which is not visible from the perspective of fig. 22.

12. Preparation of infrared emission layer

As can be seen from fig. 23, the present embodiment prepares an infrared emission layer 901 on an isolation layer 701 between two heat generating electrode pads 801.

13. Preparation of protective layer

As shown in fig. 24, the infrared emission layer 901 is located at the uppermost layer of the device, and the protective layer 1001 is formed in a shape of a multi-layered cake which is shrunk step by step due to the inconsistent sizes of the layers, so that the infrared emission layer 901, the isolation layer 701, the heat-generating electrode layer 601 and the supporting layer 501 are covered by the protective layer 1001.

14. Sacrificial window preparation

In this embodiment, the feature regions of the protection layer 1001 and the support layer 501 are perforated, and the pit 100 below is connected to expose the sacrificial layer 401. The sacrificial window is not visible at the corresponding viewing angles of fig. 12-24, and a schematic view of a specific sacrificial window can be seen from the top view of fig. 25.

15. Sacrificial layer removal

With the sacrificial window 1002, the sacrificial layer 401 material within the pit 100 can be completely removed using a specific solvent, resulting in the final MEMS infrared light source product of fig. 26.

The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.

Claims

1. A manufacturing method of an MEMS infrared light source is characterized in that: the method is used for manufacturing an MEMS infrared light source which is arranged between a substrate and a supporting layer and comprises a special cavity and a reflecting layer; the manufacturing method comprises the following steps:

(1) Mask processing of a substrate:

providing a substrate, and depositing a preset amount of mask layer material on a surface to be processed of the substrate to form a required corrosion mask layer;

(2) Preparing a corrosion window:

removing part of the mask layer on the surface to be processed by utilizing a photoetching technology according to the preset window size and shape so as to form a corrosion window on the substrate; the exposed area below the corrosion window is a substrate area needing corrosion;

(3) Anisotropic etching:

carrying out chemical corrosion on the substrate through an anisotropic corrosion process to form a pit which is concave towards the inside of the substrate and gradually reduces in caliber in the corrosion window area of the substrate;

(4) Preparing a reflecting layer:

depositing a preset amount of reflecting layer materials in the pits on the surface of the substrate by adopting a physical vapor deposition process to form a required reflecting layer;

(5) Primary polishing:

polishing the surface to be processed of the substrate, and removing surface plating layers of other areas except pits on the surface of the substrate, wherein the surface plating layers comprise etching mask layer materials and reflecting layer materials;

(6) Sacrificial layer preparation:

filling the pits in the substrate with a sacrificial layer material that is selectively removable by any means;

(7) Secondary polishing:

performing secondary polishing treatment on the surface to be processed of the substrate filled with the sacrificial layer material so that the sacrificial layer material in the pits is kept flush with the surrounding substrate surface;

(8) Preparing a supporting layer:

generating a required supporting layer on the surface of one side of the substrate containing the sacrificial layer, wherein the supporting layer completely covers the substrate and the sacrificial layer below;

(9) Preparing a heating electrode layer:

preparing a required heating electrode layer on the surface of the supporting layer, wherein the heating electrode layer is positioned above the pit in the corresponding substrate; the left side and the right side of the heating electrode layer completely cover the pits, the front side and the rear side are positioned in the areas opposite to the inner sides of the pits, and the pits are not covered;

(10) Preparing a heating electrode pad:

preparing two strip-shaped heating electrode pads which are parallel to each other and not more than the distribution area of the heating electrode layer above the heating electrode layer; wherein, the distribution areas of the two heating electrode bonding pads are separated from or circumscribed with the enclosing area of the upper opening of the pit;

(11) Preparing an infrared emission layer:

preparing a required infrared emission layer above the heating electrode layer on the inner side of the heating electrode bonding pad; the infrared emission layer is positioned in the connecting area of the four end points of the heating electrode bonding pad;

(12) Removing window preparation:

etching the supporting layer material by a photoetching technology, and selecting a specific area to process at least one penetrating removal window on the basis of not damaging the heating electrode layer and the infrared emission layer above so as to expose the sacrificial layer material in the pit below;

(13) Sacrificial layer removal:

2. The method of manufacturing a MEMS infrared light source of claim 1, wherein: in the step (1), the substrate material is silicon, and a crystal face of the silicon (100) is taken as a face to be processed; the mask layer is made of any one of silicon oxide, silicon nitride, cr, au, pt and NiCr alloy;

In the step (3), TMAH aqueous solution, KOH aqueous solution, naOH aqueous solution, mixed aqueous solution of ethylenediamine and catechol and NH are adopted ₄ Any one of the OH aqueous solutions is used as an anisotropic etching solution; the depth of the etching is controlled to be 1-50 μm.

3. The method of manufacturing a MEMS infrared light source of claim 1, wherein: in the step (4), the reflecting layer is a single metal coating made of one material in Ag, au, cu, al or a composite metal coating made of multiple materials by layer deposition; or preparing a dielectric film Bragg plating layer as a required reflecting layer.

4. The method of manufacturing a MEMS infrared light source of claim 1, wherein: in the step (6), the material of the sacrificial layer is selected from SiO ₂ One of phosphosilicate glass, silica gel, polyimide, SU-8, polydimethylsiloxane (PDMS), gelatin, polyethylene glycol, parylene, benzocyclobutene;

in the step (13), a solvent or a solution capable of directionally corroding the sacrificial layer material is adopted as a selective corrosive liquid for carrying out dipping treatment, the corrosive liquid is diffused into the cavity through the removing window, and the sacrificial layer material in the cavity is completely removed; the product is also cleaned and dried after the sacrificial layer is removed.

5. The method of manufacturing a MEMS infrared light source of claim 1, wherein: the polishing treatment in the step (5) adopts a wet etching or chemical mechanical polishing method; in the step (7), polishing treatment is performed by a dry etching or chemical mechanical polishing method.

6. The method of manufacturing a MEMS infrared light source of claim 1, wherein: in the step (8), the supporting layer is generated by adopting a physical vapor deposition or chemical vapor deposition process; the generated supporting layer is a single plating layer formed by silicon oxide or silicon nitride, or a multi-layer composite plating layer formed by depositing silicon oxide or silicon nitride layer by layer according to a preset sequence.

7. The method of manufacturing a MEMS infrared light source of claim 1, wherein: in the step (9), the heating electrode layer is generated by physical vapor deposition or chemical vapor deposition process; the material of the heating electrode layer is selected from Pt, mo, niCr alloy, polysilicon and SiC, cu, W, hfB ₂ PtSi and SnO ₂ Any one of them;

and/or

Firstly, depositing a transition layer made of a specific material on the surface of the supporting layer; then generating a required heating electrode layer; the transition layer is selected from any one of Ti, cr and Ni according to the materials of the heating electrode layer and the supporting layer.

8. The method of manufacturing a MEMS infrared light source of claim 1, wherein: in the step (10), the heating electrode pad is electrically connected with the heating electrode layer, and the material for preparing the heating electrode pad is selected from any one of AlSi alloy, au, al, niCr alloy and NiV alloy;

preparing a required infrared emission layer by a material with high infrared emissivity in the step (11); the thickness of the prepared infrared emission layer is 50-1000nm; wherein the material with high infrared emissivity comprises NiCr alloy, tiN, tiAlN, amorphous carbon, siC, niCrO compound and ZrO ₂ 、HfO ₂ 、La _1-x Ca _x CrO ₃ (0.ltoreq.x.ltoreq.0.5) and any one or more of the carbon nanotubes;

and/or

The processed emission surface of the infrared emission layer is of a rough surface structure.

9. The method of manufacturing a MEMS infrared light source of claim 1, wherein: when the prepared infrared emission layer has conductivity, adding a step for preparing an isolation layer between the steps (9) and (10); and after preparing the isolation layer, the step of preparing the heating electrode pad of the step (10) needs to remove the isolation layer of a partial area for setting the heating electrode pad by a photoetching stripping method so that the heating electrode pad is electrically connected with the heating electrode layer below; and in the step (11), the infrared emission layer is positioned on the upper surface of the isolation layer;

The isolation layer is formed by adopting a physical vapor deposition or chemical vapor deposition process, and the material is one or a combination of any more of silicon oxide, silicon nitride and aluminum oxide.

10. The method of manufacturing a MEMS infrared light source of claim 1, wherein: a step of preparing a protective layer is added between the step (11) and the step (12), and the prepared protective layer completely covers the upper surfaces of the infrared emission layer, the infrared electrode layer and the supporting layer;

the protective layer is formed by adopting a physical vapor deposition or chemical vapor deposition process, and the material is selected from any one or a combination of a plurality of silicon oxide, silicon nitride, aluminum oxide and hafnium oxide.