Micro-heating plate with composite structure and manufacturing method thereof

Abstract

The present invention discloses a micro-heating plate with a composite structure and a manufacturing method thereof. The manufacturing method comprises: forming a cavity structure on the second surface of a first substrate; sequentially growing a heat-insulating layer and a first insulating layer on the surface of a second substrate; bonding the first insulating layer to the first surface of the first substrate, with the first surface and the second surface facing each other, and then removing the second substrate; sequentially forming a heating layer, a second insulating layer and a testing layer on the heat-insulating layer. The first and second substrates can be quartz substrates and single crystal silicon substrates, respectively. The micro-heating plate with a composite structure provided by the present invention has a simple and firm structure, high reliability, good stability, and especially high-efficiency heating performance. At the same time, its preparation process is simple and easy to operate, and can be quickly implemented using MEMS technology, which is suitable for large-scale production.

Description

Technical Field

[0001] The invention relates to a micro-heating plate and a manufacturing method thereof, in particular to a micro-heating plate with a composite structure and a manufacturing method thereof, and belongs to the technical field of semiconductor micro-nano processing. Background Art

[0002] At present, there are mainly several types of gas sensors, such as semiconductor, electrochemical, and catalytic combustion. Among them, semiconductor gas sensors are the most practical type of gas sensors. They have the advantages of low cost, simple manufacturing, high sensitivity, fast response speed, long life, low sensitivity to humidity, and simple circuit. The current mature semiconductor gas sensors are based on micro-heating plates, on which sensitive materials are coated to make the sensitive materials work at a certain temperature, which can achieve good operation of semiconductor gas sensors.

[0003] At present, the commonly used micro-heating plates are mainly based on ceramic substrates or silicon substrates. Ceramic substrates are mainly used for heating traditional high-temperature sensitive materials. They are relatively large in size and are mostly used in traditional gas sensors. Silicon-based micro-heating plates are mainly based on suspended structures, with cavities opened on the back, and composite layers formed with silicon nitride and silicon oxide on the surface for insulation and heat insulation. Since the United States first proposed the MEMS micro-heating plate, many researchers at home and abroad have conducted a lot of research on it. For example, some literature reports on micro-heating plate research based on SOI silicon as a substrate. However, the current MEMS silicon-based micro-heating plates still have the disadvantages of low yield, difficulty in resisting high temperatures, and easy damage to the supporting film. Specifically, the existing MEMS silicon-based micro-heating plates generally use the back to form a cavity, and use silicon nitride, silicon oxide, etc. on the surface to form a supporting layer and a heat-insulating layer, and then form a heating structure on it. However, on the one hand, silicon itself is a good conductor of heat, and heat loss during operation will affect work efficiency. On the other hand, when etching the silicon back cavity, the surface silicon oxide and silicon nitride films are often damaged, affecting the device yield. Summary of the invention

[0004] The main purpose of the present invention is to provide a micro-heating plate with a composite structure, which has a simple manufacturing process, can work at high temperatures and has a long service life, thereby overcoming the shortcomings of the prior art.

[0005] Another object of the present invention is to provide a method for manufacturing the micro-heating plate of the composite structure.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0007] An embodiment of the present invention provides a micro-heating plate with a composite structure, which includes a first substrate and a first insulating layer, a heat insulation layer, a heating layer, a second insulating layer and a testing layer arranged in sequence on a first surface of the first substrate, a second surface of the first substrate forms a cavity structure, and the second surface is arranged opposite to the first surface.

[0008] The embodiment of the present invention further provides a method for manufacturing a micro-heating plate of a composite structure, which comprises:

[0009] Processing a second surface of a first substrate to form a cavity structure;

[0010] A heat insulation layer and a first insulating layer are sequentially grown on a surface of a second substrate;

[0011] Bonding the first insulating layer to the first surface of the first substrate, the first surface being opposite to the second surface, and then removing the second substrate;

[0012] A heating layer, a second insulating layer and a testing layer are sequentially formed on the thermal insulation layer.

[0013] In some embodiments, the aforementioned first substrate is a quartz substrate, especially a high-purity quartz substrate.

[0014] In some embodiments, the second substrate is a single crystal silicon substrate (ie, a silicon wafer).

[0015] The embodiment of the present invention also provides the application of the micro-heating plate of the composite structure in the preparation of a micro-heating sensor.

[0016] Compared with the prior art, the composite micro-heating plate provided by the present invention has a simple and firm structure, high reliability, good stability, and especially high-efficiency heating performance. Meanwhile, its preparation process is simple and easy to operate, and can be quickly implemented using MEMS technology, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of a micro-heating plate of a composite structure in a typical embodiment of the present invention;

[0018] Figure 2 is a process flow chart of preparing a micro-heating plate with a composite structure in a typical embodiment of the present invention;

[0019] Figure 3 It is a schematic diagram of the preparation process of a micro-heating plate with a composite structure in a typical embodiment of the present invention. DETAILED DESCRIPTION

[0020] As mentioned above, in view of the many defects of the prior art, the inventor of this case has proposed the technical solution of the present invention after long-term research and extensive practice. The technical solution, its implementation process and principle will be further explained as follows.

[0021] An aspect of an embodiment of the present invention provides a method for manufacturing a composite micro-heating plate, comprising:

[0022] Processing a second surface of a first substrate to form a cavity structure;

[0023] A heat insulation layer and a first insulating layer are sequentially grown on a surface of a second substrate;

[0024] Bonding the first insulating layer to the first surface of the first substrate, the first surface being opposite to the second surface, and then removing the second substrate;

[0025] A heating layer, a second insulating layer and a testing layer are sequentially formed on the thermal insulation layer.

[0026] The test layer includes a test electrode. The test electrode may have a patterned structure.

[0027] In some embodiments, the manufacturing method specifically includes: using a three-dimensional hot pressing process to form a cavity structure on the second surface of the first substrate. The three-dimensional hot pressing process can avoid the damage caused by conventional wet compounding or dry etching processes to the heating of the front side of the substrate or the test electrode, and can significantly improve its yield.

[0028] In some embodiments, the manufacturing method specifically includes: thoroughly cleaning the second substrate, the cleaning method includes any one or more combinations of acid cleaning, alkali cleaning, organic solvent cleaning, and deionized water cleaning, followed by vacuum drying or drying in a nitrogen atmosphere, and then sequentially growing a thermal insulation layer and a first insulating layer on the surface of the second substrate.

[0029] In some embodiments, the manufacturing method specifically includes: bonding the first insulating layer to the first surface of the first substrate using an anodic bonding process. Using this bonding process, the two substrates can be more firmly combined to ensure the mechanical strength of the device.

[0030] In some embodiments, the manufacturing method specifically includes: removing the second substrate by a thinning process to expose the thermal insulation layer, and then etching the first substrate to allow the cavity structure to penetrate the first substrate axially. Such an operation can make the overall layer of the device thinner and better control the thermal effect of the heating plate.

[0031] In some embodiments, the manufacturing method specifically includes: using a CVD method to grow and form at least one of the thermal insulation layer, the first insulating layer, and the second insulating layer.

[0032] In some embodiments, the manufacturing method specifically includes: using a PVD method to grow and form at least one of the heating layer and the testing layer.

[0033] In some specific embodiments, the preparation method may include the following steps:

[0034] (1) Using a three-dimensional hot pressing process, a cavity structure (also called a back cavity) is formed on the back of a first substrate (e.g., a high-purity quartz substrate). The cavity structure may be circular, square, etc., and the length, width, and height of the cavity may be about 100um-5000um. Preferably, in this step, the cavity structure does not completely penetrate the first substrate in the axial direction, that is, the constituent material of the first substrate remains at the bottom of the cavity structure. In this way, the heat diffusion of the heating plate can be controlled, so that the heating plate has a good heating effect.

[0035] (2) The second substrate (eg, a single crystal silicon substrate) is thoroughly cleaned, including acid cleaning, alkali cleaning, organic solvent cleaning, and deionized water cleaning, and then fully dried in a vacuum oven or nitrogen drying.

[0036] (3) A heat insulating layer (eg, a silicon nitride layer) and a first insulating layer (eg, a silicon oxide layer) are grown on one surface of the second substrate using a CVD method.

[0037] (4) Bonding the surface of the first insulating layer to the front side of the first substrate using an anodic bonding process.

[0038] (5) The remaining second substrate is removed through a thinning process to expose the thermal insulation layer.

[0039] (6) Remove the excess substrate material (such as quartz) on the back cavity of the first substrate by dry etching to expose the first insulating layer. This can make the overall layer of the device thinner and better control the thermal effect of the heating plate.

[0040] (7) A heating layer is deposited on the surface of the insulation layer using PVD.

[0041] (8) Depositing a second insulating layer on the surface of the heating layer by CVD.

[0042] (9) Depositing a test layer on the surface of the second insulating layer by PVD.

[0043] Another aspect of an embodiment of the present invention provides a composite structure micro-heating plate including a first substrate and a first insulating layer, a heat insulation layer, a heating layer, a second insulating layer and a testing layer sequentially arranged on a first surface of the first substrate, wherein a cavity structure is formed on the second surface of the first substrate, and the second surface is arranged opposite to the first surface.

[0044] Furthermore, the first substrate includes a quartz substrate.

[0045] Furthermore, the second substrate includes a single crystal silicon substrate.

[0046] Furthermore, the material of the first insulating layer and the second insulating layer includes silicon oxide, for example, may be a silicon oxide layer.

[0047] Furthermore, the material of the thermal insulation layer includes silicon nitride, for example, may be a silicon nitride layer.

[0048] Furthermore, the material of the heating layer includes metal, for example, it can be a metal structure layer formed by any one of Pt, Mo, W or a combination of two or more thereof or an alloy thereof.

[0049] Furthermore, the material of the test layer includes metal, for example, it may be a metal structure layer formed by Au and / or Ag or an alloy thereof.

[0050] In some embodiments, the first substrate is bonded to the first insulating layer by an anodic bonding process.

[0051] Preferably, the thickness of the first insulating layer and the second insulating layer is 100 nm-5000 nm.

[0052] Preferably, the thickness of the thermal insulation layer is 100nm-5000nm.

[0053] Preferably, the thickness of the heating layer is 100nm-1000nm.

[0054] Preferably, the thickness of the test layer is 100nm-1000nm.

[0055] More preferably, the cavity structure penetrates the first substrate along the axial direction.

[0056] Preferably, the length, width and height of the cavity structure are 100 μm-5000 μm.

[0057] By adopting the aforementioned structural parameter settings, the various structural layers in the heating plate can be well combined together, resulting in a good heating effect, and the yield of the overall device can be controlled at a high level.

[0058] Another aspect of the embodiments of the present invention further provides the use of the micro-heating plate of the composite structure in preparing a micro-heating sensor. For example, the embodiments of the present invention provide a device, the device comprising the micro-heating plate of the composite structure, preferably, the device may comprise a micro-heating sensor.

[0059] The composite micro-heating plate provided by the present invention has a simple structure, is firm, has high reliability, good stability, and has efficient heating performance. Meanwhile, its preparation process is simple and easy to operate, can be rapidly implemented using MEMS technology, and is suitable for industrial production.

[0060] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and typical cases.

[0061] See also Figure 1 As shown, in a typical embodiment of the present invention, a composite micro-heating plate comprises a first substrate 1 and a first insulating layer 2, a heat insulating layer 3, a heating layer 4, a second insulating layer 5 and a testing layer 6 arranged in sequence on the first surface of the first substrate, a second surface of the first substrate is formed with a cavity structure 7, and the second surface is arranged opposite to the first surface. Preferably, the cavity structure penetrates the first substrate along the axial direction.

[0062] Furthermore, the first substrate may be a high-purity quartz substrate.

[0063] Furthermore, the second substrate may be a silicon wafer, that is, a single crystal silicon substrate.

[0064] Furthermore, the first insulating layer and the second insulating layer may both be silicon oxide layers.

[0065] Furthermore, the thermal insulation layer may be a silicon nitride layer.

[0066] Furthermore, the heating layer may be formed of any one of Pt, Mo, W or a combination of two or more thereof or an alloy thereof.

[0067] Further, the test layer may be formed of Au and / or Ag or alloys thereof.

[0068] Furthermore, the first substrate and the first insulating layer may be bonded by an anodic bonding process.

[0069] Furthermore, the thickness of the first insulating layer and the second insulating layer may be 100 nm-5000 nm.

[0070] Furthermore, the thickness of the thermal insulation layer is 100nm-5000nm.

[0071] Furthermore, the thickness of the heating layer is 100nm-1000nm.

[0072] Furthermore, the thickness of the test layer is 100nm-1000nm.

[0073] Furthermore, the length, width and height of the cavity structure are 100 μm-5000 μm.

[0074] The micro-heating plate of this embodiment can be manufactured using MEMS technology. For example, a method for manufacturing the micro-heating plate can be found in Figure 2 , Figure 3 The production method specifically comprises the following steps:

[0075] (1) A high-purity quartz substrate 1 and a single-crystal silicon substrate 8 are prepared, wherein the thickness of the quartz substrate can be about 200-500 um, and the thickness of the single-crystal silicon substrate can be about 200-500 um.

[0076] (2) The single crystal silicon substrate is thoroughly cleaned, including: a. boiling with concentrated sulfuric acid at 85°C for 15 minutes; b. soaking with 50 wt% potassium hydroxide solution for 10 minutes; c. sonicating with acetone solution for 15 minutes and deionized water solution for 15 minutes; and then drying in a vacuum oven or nitrogen drying (drying at 120°C for about 1 hour).

[0077] (3) A silicon nitride layer 3 as a heat insulating layer and a silicon oxide layer 2 as an insulating layer are grown by CVD on one surface of the single crystal silicon substrate 8. The thickness of the silicon nitride layer 3 and the silicon oxide layer 2 can be 100 nm to 5000 nm respectively.

[0078] (4) Using a three-dimensional hot pressing process, the hot pressing temperature is controlled at 500-800min and the pressure is controlled at 20-100kg to form a cavity structure 7' (also called back cavity) on the back of the quartz substrate 1. The cavity structure 7' can be circular, square, etc., and the length, width and height can be about 100μm-5000μm. In this step, the cavity structure does not completely penetrate the first substrate in the axial direction, that is, there is still some material of the first substrate remaining at the bottom of the cavity structure, with a thickness of about 20-50um.

[0079] (5) Using an anodic bonding process, controlling the bonding temperature at 200-500 degrees and the pressure at 10-200 MPa, the surface of the first insulating layer is bonded to the front side of the first substrate.

[0080] (6) The remaining single crystal silicon substrate 8 is removed by a thinning process to expose the silicon nitride layer 3.

[0081] (7) The excess substrate material on the back cavity of the quartz substrate is removed by dry etching process to form a cavity structure 7 and expose the silicon oxide layer 2.

[0082] (8) Pt, Mo, W or other metals or their alloys are deposited on the surface of the silicon nitride layer 3 by PVD to form a heating layer 4. The thickness of the heating layer can be 100nm-1000nm.

[0083] (9) Silicon oxide or the like is deposited on the surface of the heating layer 4 by CVD to form an insulating layer 5. The thickness of the insulating layer can be 100 nm to 5000 nm.

[0084] (10) A metal such as Au, Ag or their alloy is deposited on the surface of the insulating layer 5 by PVD to form a test layer 6. The thickness of the test layer can be 100 nm-1000 nm.

[0085] The process conditions of CVD, PVD, dry etching, etc. used in the aforementioned manufacturing method may be known in the industry.

[0086] In the manufacturing method provided in this embodiment, a certain thickness of oxide layer and nitride layer are pre-formed on the bonding surface of the silicon wafer as a support, and a cavity structure is pre-made on the back of the quartz substrate, and then the silicon wafer is combined with a high-purity quartz substrate to form a complex of silicon and quartz, and then a micro-heating plate with the quartz substrate as a support structure can be formed to achieve high-efficiency heating performance. The manufacturing method is simple and easy to operate, can be quickly implemented using MEMS technology, and is suitable for large-scale production. Moreover, the micro-heating plate of the composite structure formed is simple and firm in structure, high in heating efficiency, high in reliability, and good in working stability.

[0087] The technical contents and technical features of the present invention have been disclosed as above. However, those skilled in the art may still make various substitutions and modifications based on the teachings and disclosures of the present invention without departing from the spirit of the present invention. Therefore, the protection scope of the present invention should not be limited to the contents disclosed in the embodiments, but should include various substitutions and modifications that do not depart from the present invention and are covered by the claims of this patent application.

Claims

1. A method for manufacturing a composite micro-heating plate, characterized in that: include: A cavity structure is formed on the second surface of a quartz substrate by using a three-dimensional hot pressing process; A heat insulation layer and a first insulating layer are sequentially grown on a surface of a single crystal silicon substrate; The first insulating layer is bonded to the first surface of the quartz substrate by an anodic bonding process, the first surface and the second surface are opposite to each other, and then the single crystal silicon substrate is removed by a thinning process to expose the heat insulation layer, and then the quartz substrate is etched to make the cavity structure penetrate the quartz substrate along the axial direction; forming a heating layer, a second insulating layer and a testing layer in sequence on the thermal insulation layer; The heat insulation layer, the first insulating layer and the second insulating layer are grown by adopting the CVD method.

2. The method according to claim 1, characterized in that: Specifically include: The single crystal silicon substrate is thoroughly cleaned, and the cleaning method includes any one or more combinations of acid cleaning, alkali cleaning, organic solvent cleaning, and deionized water cleaning, followed by vacuum drying or drying in a nitrogen atmosphere, and then sequentially growing a thermal insulation layer and a first insulating layer on the surface of the single crystal silicon substrate.

3. The method according to claim 1, characterized in that: Specifically include: At least one of the heating layer and the testing layer is grown by PVD method.

4. The method according to claim 1, characterized in that: The first insulating layer and the second insulating layer are made of silicon oxide.

5. The method according to claim 1, characterized in that: The material of the heat insulation layer includes silicon nitride.

6. The method according to claim 1, characterized in that: The material of the heating layer includes metal, and the metal includes any one of Pt, Mo, and W, or a combination of two or more thereof.

7. The method according to claim 1, characterized in that: The material of the testing layer includes metal, and the metal includes Au and / or Ag.

8. The method according to claim 1, characterized in that: The thickness of the first insulating layer and the second insulating layer is 100nm-5000nm.

9. The method according to claim 1, characterized in that: The thickness of the heat insulation layer is 100nm-5000nm.

10. The manufacturing method according to claim 1, characterized in that: The thickness of the heating layer is 100nm-1000nm.

11. The manufacturing method according to claim 1, characterized in that: The thickness of the test layer is 100nm-1000nm.

12. The manufacturing method according to claim 1, characterized in that: The length, width and height of the cavity structure are 100 μm-5000 μm.

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