CN112678765A - Preparation method of MEMS pressure-sensitive film based on concentrated boron doping - Google Patents
Preparation method of MEMS pressure-sensitive film based on concentrated boron doping Download PDFInfo
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- CN112678765A CN112678765A CN202011444277.5A CN202011444277A CN112678765A CN 112678765 A CN112678765 A CN 112678765A CN 202011444277 A CN202011444277 A CN 202011444277A CN 112678765 A CN112678765 A CN 112678765A
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- silicon wafer
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- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 title claims abstract description 21
- 229910052796 boron Inorganic materials 0.000 title claims abstract description 21
- 238000002360 preparation method Methods 0.000 title claims abstract description 14
- 238000000034 method Methods 0.000 claims abstract description 22
- 230000008569 process Effects 0.000 claims abstract description 16
- 239000005388 borosilicate glass Substances 0.000 claims abstract description 12
- 238000004519 manufacturing process Methods 0.000 claims abstract description 8
- 238000005260 corrosion Methods 0.000 claims abstract description 7
- 230000007797 corrosion Effects 0.000 claims abstract description 7
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 75
- 229910052710 silicon Inorganic materials 0.000 claims description 75
- 239000010703 silicon Substances 0.000 claims description 75
- 239000007788 liquid Substances 0.000 claims description 27
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 24
- 238000004140 cleaning Methods 0.000 claims description 16
- 239000008367 deionised water Substances 0.000 claims description 12
- 229910021641 deionized water Inorganic materials 0.000 claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 12
- 238000009792 diffusion process Methods 0.000 claims description 10
- 238000005530 etching Methods 0.000 claims description 9
- 230000003647 oxidation Effects 0.000 claims description 9
- 238000007254 oxidation reaction Methods 0.000 claims description 9
- CFOAUMXQOCBWNJ-UHFFFAOYSA-N [B].[Si] Chemical compound [B].[Si] CFOAUMXQOCBWNJ-UHFFFAOYSA-N 0.000 claims description 5
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 4
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 4
- 238000001312 dry etching Methods 0.000 claims description 4
- 229910017604 nitric acid Inorganic materials 0.000 claims description 4
- 238000001259 photo etching Methods 0.000 claims description 4
- 238000012545 processing Methods 0.000 claims description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 4
- 238000004026 adhesive bonding Methods 0.000 claims description 3
- 238000001039 wet etching Methods 0.000 claims description 3
- 239000000243 solution Substances 0.000 claims 5
- 239000011259 mixed solution Substances 0.000 claims 2
- 238000005259 measurement Methods 0.000 abstract description 9
- 239000011521 glass Substances 0.000 abstract description 3
- 239000010408 film Substances 0.000 description 40
- 229920002120 photoresistant polymer Polymers 0.000 description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 4
- 238000004528 spin coating Methods 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- 229910052582 BN Inorganic materials 0.000 description 1
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000009987 spinning Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
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Abstract
The invention discloses a preparation method of an MEMS pressure-sensitive film based on concentrated boron doping, which can accurately control the thickness of the film by adopting an automatic stop corrosion process in the concentrated boron doping technology and can prepare a micron-sized film, thereby improving the repeatability of capacitance measurement and effectively ensuring the actual production and preparation of a vacuum gauge; meanwhile, the borosilicate glass removing scheme is adopted, so that the borosilicate glass generated on the surface of the film can be effectively removed, the influence of stray capacitance caused by the borosilicate glass is eliminated, and meanwhile, the subsequent bonding process quality of the film and the glass can be powerfully ensured.
Description
Technical Field
The invention belongs to the technical field of micro-electromechanical systems and vacuum measurement, and particularly relates to a preparation method of an MEMS pressure-sensitive film based on concentrated boron doping.
Background
The novel capacitance film vacuum gauge manufactured based on the Micro-Electro-Mechanical System (MEMS) technology has the advantages of small size, light weight, low power consumption, compatibility of a manufacturing process and a CMOS, convenience in batch production and the like, and can better meet the vacuum measurement requirement under special conditions. As an important component of MEMS capacitive thin film vacuum gauges, the design and fabrication of the pressure sensing thin film has a critical impact on the overall performance of the gauge. Meanwhile, the overall performance of the sensor depends on the mechanical property of the film to a great extent, and the change of a pressure-deflection curve after the film is stressed is shown.
The conventional MEMS pressure-sensing film adopts common monocrystalline silicon and a lightly doped P-type film, the resistivity of the film is relatively high, and for an MEMS capacitance film vacuum gauge, the capacitance measurement can generate relatively large errors due to the fact that the rated capacitance of MEMS equipment is about several picofarads and the capacitance variation is several femtofarads or even smaller; in addition, since the thickness of the MEMS pressure sensitive film is usually very small, generally several microns, to meet the measurement requirement, it is difficult to precisely prepare a film with a thickness of several microns by using a common etching process.
Disclosure of Invention
In view of this, the invention provides a method for preparing a MEMS pressure-sensitive film based on a concentrated boron doping, which can accurately prepare a pressure-sensitive film with a certain thickness.
The invention provides a preparation method of an MEMS pressure-sensitive film based on concentrated boron doping, which comprises the following steps: cleaning a silicon wafer and then carrying out double-sided oxidation, wherein the double-sided oxidation process enables the front side and the back side of the silicon wafer to form oxide layers; etching the front side of the silicon wafer to form a concave surface on the front side of the silicon wafer; cleaning the silicon wafer; processing the silicon wafer in a concentrated boron diffusion mode to form a boron-silicon diffusion layer in the concave surface of the front surface of the silicon wafer; removing borosilicate glass from the front side of the silicon wafer; gluing and photoetching the back of the silicon wafer; and carrying out self-stop corrosion treatment on the silicon wafer to obtain the MEMS pressure-sensitive film.
Furthermore, the silicon wafer is cleaned by adopting a cleaning solution.
Further, the cleaning solution comprises No. 1 solution, No. 2 solution and No. 3 solution; the process for cleaning the silicon wafer comprises the following steps: sequentially cleaning the silicon wafer for 20 minutes by adopting No. 3 liquid, No. 1 liquid and No. 2 liquid;
wherein the No. 1 liquid is a mixed liquid formed by ammonia water, hydrogen peroxide and deionized water according to the proportion of 1:1: 5; the No. 2 liquid is a mixed liquid formed by nitric acid, hydrogen peroxide and deionized water according to the proportion of 1:1: 5; the No. 3 liquid is a mixed liquid formed by concentrated sulfuric acid, hydrogen peroxide and deionized water according to the proportion of 1:1: 5.
Further, the double-sided oxidation process enables oxide layers to be formed on the front side and the back side of the silicon wafer, wherein the thickness of the oxide layers is 1 μm.
Further, the etching on the front surface of the silicon wafer to form a concave surface on the front surface of the silicon wafer comprises the following steps: and processing the front surface of the silicon wafer by adopting dry etching to form a concave surface with the depth of 4 mu m.
Further, the thickness of the boron-silicon diffusion layer is 5 μm.
Further, the process of performing self-stop etching treatment on the silicon wafer comprises the following steps: and putting the silicon wafer into a wet etching device for etching.
Has the advantages that:
1. according to the invention, the thickness of the film can be accurately controlled by adopting the self-stop corrosion process in the concentrated boron doping technology, and the micron-sized film can be prepared, so that the repeatability of capacitance measurement is improved, and the actual production and preparation of the vacuum gauge are effectively ensured; meanwhile, the borosilicate glass removing scheme is adopted, so that the borosilicate glass generated on the surface of the film can be effectively removed, the influence of stray capacitance caused by the borosilicate glass is eliminated, and meanwhile, the subsequent bonding process quality of the film and the glass can be powerfully ensured.
2. The invention can form a pressure-sensitive film with the thickness of 5 mu m, ensure that the resistivity of the film is less than 4 multiplied by 10 < -4 >, improve the tensile strength of the film by more than 20 percent and further realize the measurement of the absolute vacuum degree of the MEMS capacitance film vacuum gauge in the range of 1-1000 Pa.
Drawings
Fig. 1 is a process flow chart of a method for preparing a MEMS pressure-sensitive film based on a heavy boron doping according to the present invention.
FIG. 2 is a cross-sectional view of a MEMS pressure-sensitive film structure formed by the method for preparing the MEMS pressure-sensitive film based on the concentrated boron doping provided by the invention.
FIG. 3 is a top view of a MEMS pressure-sensitive film formed by the method for preparing the MEMS pressure-sensitive film based on the concentrated boron doping provided by the invention.
The device comprises a vacuum reference cavity 1, a pressure sensing film 2, a fixed electrode lead-out groove 3, a silicon-based 4, a measuring end air inlet 5 and a film electrode lead-out groove 6.
Detailed Description
The invention is described in detail below by way of example with reference to the accompanying drawings.
The invention provides a preparation method of an MEMS pressure-sensitive film based on concentrated boron doping, the manufacturing process is shown in figure 1, and the preparation method specifically comprises the following steps:
The cleaning solution comprises No. 1 liquid, No. 2 liquid and No. 3 liquid, wherein the No. 1 liquid is a mixed liquid of ammonia water, hydrogen peroxide and deionized water, and the ratio is ammonia water: hydrogen peroxide: deionized water 1:1: 5; the No. 2 liquid is a mixed liquid of nitric acid, hydrogen peroxide and deionized water, and the proportion is that nitric acid: hydrogen peroxide: deionized water 1:1: 5; the No. 3 liquid is a mixed liquid of concentrated sulfuric acid, hydrogen peroxide and deionized water, and the proportion is that the concentrated sulfuric acid: hydrogen peroxide: deionized water 1:1: 5.
Then, the silicon wafer is sequentially washed for 20 minutes by using the No. 3 liquid, the No. 1 liquid and the No. 2 liquid in sequence.
And 2, performing double-sided oxidation on the silicon wafer, wherein the silicon wafer subjected to double-sided oxidation is numbered as shown in figure 1, and oxidation layers with certain thickness are generated on the front surface and the back surface of the silicon wafer.
For example, dry oxygen is used to oxidize the front and back surfaces of a silicon wafer until an oxide layer with a thickness of 1 μm is grown. Wherein, the oxide layer on the back of the silicon wafer can be used as a resistance layer for the diffusion of the concentrated boron.
And 3, spin-coating photoresist on the front surface of the silicon wafer, photoetching the front surface graph of the pressure-sensitive film 2, and marking the processed silicon wafer as shown by the number (c) in figure 1.
And 4, carrying out dry etching on the front side of the silicon wafer processed in the step 3, wherein the processed silicon wafer is shown as a number (r) in the figure 1.
Specifically, under the protection of the photoresist spin-coated in the step 3, the front surface of the silicon wafer is etched by adopting plasma to form a concave surface with the depth of 4 microns.
And 5, cleaning the silicon wafer treated in the step 4 to obtain the silicon wafer with the number of (v) shown in figure 1.
And 6, treating the silicon wafer cleaned in the step 5 in a concentrated boron diffusion mode, wherein the treated silicon wafer is shown as the number (sixty percent) in the figure 1.
The specific process is that the cleaned silicon wafer and the boron nitride source wafer are placed into a boron diffusion furnace for treatment according to a certain arrangement mode, and a boron-silicon diffusion layer with the thickness of 5 mu m is formed on the concave surface of the front surface of the silicon wafer after treatment.
And 7, removing borosilicate glass from the silicon wafer formed in the step 6, wherein the processed silicon wafer is shown as a number (c) in fig. 1.
And carrying out borosilicate glass removal treatment on the silicon wafer, then spin-coating photoresist on the front side of the silicon wafer, then removing an oxide layer on the back side of the silicon wafer by using hydrofluoric acid solution, and finally washing off the photoresist on the front side of the silicon wafer.
And 8, gluing and photoetching the back of the silicon wafer formed in the step 7, wherein the processed silicon wafer is shown as a number (b) in figure 1, a photoresist is coated on the back of the silicon wafer in a spinning mode, and then a graph is photoetched.
And 9, performing self-stop corrosion treatment on the silicon wafer formed in the step 8, namely putting the silicon wafer with the photoetched pattern into a wet etching device, and stopping corrosion when the silicon wafer is corroded to a concentrated boron-doped silicon layer, wherein the self-stop corrosion is performed.
In this example, the thickness of the oxide 8 and the glue 9 cooperate with the etch depth of the dry etch 10 to determine the etch depth of the wafer. And (3) performing dry etching 10 to etch a 4-micron groove on the silicon wafer, and bonding the groove with the upper glass substrate to form a vacuum cavity 1. In the borosilicate glass removing step 13, hydrofluoric acid solution is required to be prepared to remove the borosilicate glass on the surface of the silicon wafer, and the front surface of the silicon wafer is polished by adopting a chemical mechanical polishing method, so that the smoothness of the front surface of the silicon wafer is ensured.
The MEMS pressure-sensitive film based on the concentrated boron doping technology can enable the film resistivity to be smaller than 4 multiplied by 10 < -4 >, and greatly improve the mechanical property of the film, so that a vacuum gauge can meet the measurement of the absolute vacuum degree within the range of 1-1000 Pa, and the measurement accuracy, sensitivity and linearity of the vacuum gauge are improved. Meanwhile, the concentrated boron doping process has the advantages of simplicity in operation, high repeatability and compatibility with an Integrated Circuit (IC), and objective conditions are provided for integrated mass production of the MEMS capacitance film vacuum gauge.
The film prepared by the preparation method of the MEMS pressure-sensitive film based on the concentrated boron doping provided by the invention can adopt an MEMS pressure-sensitive film structure shown in figure 2, and the top view of the film is shown in figure 3.
In summary, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. A preparation method of an MEMS pressure-sensitive film based on concentrated boron doping is characterized by comprising the following steps: cleaning a silicon wafer and then carrying out double-sided oxidation, wherein the double-sided oxidation process enables the front side and the back side of the silicon wafer to form oxide layers; etching the front side of the silicon wafer to form a concave surface on the front side of the silicon wafer; cleaning the silicon wafer; processing the silicon wafer in a concentrated boron diffusion mode to form a boron-silicon diffusion layer in the concave surface of the front surface of the silicon wafer; removing borosilicate glass from the front side of the silicon wafer; gluing and photoetching the back of the silicon wafer; and carrying out self-stop corrosion treatment on the silicon wafer to obtain the MEMS pressure-sensitive film.
2. The production method according to claim 1, wherein the silicon wafer is cleaned by using a cleaning solution.
3. The method according to claim 2, wherein the cleaning solution comprises solution 1, solution 2 and solution 3; the process for cleaning the silicon wafer comprises the following steps: sequentially cleaning the silicon wafer for 20 minutes by adopting No. 3 liquid, No. 1 liquid and No. 2 liquid;
wherein the No. 1 liquid is ammonia water, hydrogen peroxide and deionized water according to the proportion of 1:1:5, mixing the components to form a mixed solution; the No. 2 liquid is prepared by mixing nitric acid, hydrogen peroxide and deionized water according to the weight ratio of 1:1:5, mixing the components to form a mixed solution; the No. 3 liquid is concentrated sulfuric acid, hydrogen peroxide and deionized water according to the weight ratio of 1:1:5, and mixing the components.
4. The preparation method according to claim 1, wherein the double-sided oxidation process forms an oxide layer on both the front and back sides of the silicon wafer, wherein the thickness of the oxide layer is 1 μm.
5. The preparation method of claim 1, wherein the etching on the front surface of the silicon wafer to form a concave surface on the front surface of the silicon wafer comprises the following steps: and processing the front surface of the silicon wafer by adopting dry etching to form a concave surface with the depth of 4 mu m.
6. The production method according to claim 1, wherein the thickness of the boron-silicon diffusion layer is 5 μm.
7. The preparation method according to claim 1, wherein the self-stop etching process of the silicon wafer comprises: and putting the silicon wafer into a wet etching device for etching.
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| CN202011444277.5A CN112678765A (en) | 2020-12-11 | 2020-12-11 | Preparation method of MEMS pressure-sensitive film based on concentrated boron doping |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102818662A (en) * | 2012-08-30 | 2012-12-12 | 无锡永阳电子科技有限公司 | Pressure chip of silicon sensor and self-stop etching process for pressure chip |
| CN103335753A (en) * | 2013-06-05 | 2013-10-02 | 厦门大学 | An ultramicro pressure sensor chip with a silicon-glass base-beam film structure and a manufacturing method |
| WO2014048213A1 (en) * | 2012-09-28 | 2014-04-03 | 无锡华润上华半导体有限公司 | Method for preparing silicon film |
| CN104807869A (en) * | 2015-05-18 | 2015-07-29 | 哈尔滨理工大学 | Two-dimensional nanomaterial-based biosensor and manufacturing and integration method thereof |
| CN108117041A (en) * | 2017-12-22 | 2018-06-05 | 中国科学院半导体研究所 | The preparation method of movable micro-nano structure based on dense boron-doping silicon |
-
2020
- 2020-12-11 CN CN202011444277.5A patent/CN112678765A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102818662A (en) * | 2012-08-30 | 2012-12-12 | 无锡永阳电子科技有限公司 | Pressure chip of silicon sensor and self-stop etching process for pressure chip |
| WO2014048213A1 (en) * | 2012-09-28 | 2014-04-03 | 无锡华润上华半导体有限公司 | Method for preparing silicon film |
| CN103335753A (en) * | 2013-06-05 | 2013-10-02 | 厦门大学 | An ultramicro pressure sensor chip with a silicon-glass base-beam film structure and a manufacturing method |
| CN104807869A (en) * | 2015-05-18 | 2015-07-29 | 哈尔滨理工大学 | Two-dimensional nanomaterial-based biosensor and manufacturing and integration method thereof |
| CN108117041A (en) * | 2017-12-22 | 2018-06-05 | 中国科学院半导体研究所 | The preparation method of movable micro-nano structure based on dense boron-doping silicon |
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| 柯鑫: "基于Au-Si共晶键合的高灵敏MEMS电容薄膜真空规设计", 真空与低温 * |
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