TW442829B - Manufacturing method of corrugated diaphragm - Google Patents

Abstract

The present invention provides a manufacturing method of corrugated diaphragm, which utilizes an isotropic etching process in a back etching manner to form the desired mini-circular corrugated diaphragm on the back of a silicon wafer. In comparison with the conventional corrugation formed by the anisotropic etching process, such as RIE process, the present method has the advantages of simplified process, fast processing, and low cost.

Description

442829 -____ Case number V. Description of the invention (1) 87118977

Correction [Scope of the invention] The present month is about a method for making a corrugated dia film (P ^ ragm), and it is particularly a method of forming a circular shape on a silicon wafer by isotropic etching (mini ~ circular) method of wrinkling a film. [Background of the invention] ▲ From the literature, it is known that when the mechanical structure of a micro-element involves a mechanical element with a large deformation, it is often seen that a pleated film is used as the main core design of the element. Because the pleated film structure has higher mechanical sensitivity than the ordinary flat diaphragm; that is, under the same load, the pleated thin diaphragm will have a large change in deflection, and this is exactly what many micro The necessary features of the component. Therefore, the related technical disclosures for the application of the pleated film can be found on the micro-components of the relevant micro-valves, micro-pumps, micro-pressure sensors, micro-accelerometers, micro-actuators, and the like. The conventionally known wrinkle film is formed by an iso — tropic etching method, and a wrinkle with a circular pattern is formed on a silicon substrate. Equal and concentric circular grooves or rectangular grooves constitute the desired wrinkles. The reason for using anisotropic etching is that the thickness of the wrinkled film is quite thin, generally about one micron ', and the depth of the groove formed is only a few micrometers. So, for example, Reactive Ion Etching , R 〖E) 'technology can achieve the purpose of precise control process. However, because of this, due to the relatively high cost of the process equipment required for R I E, high-energy E equipment may cost tens of millions, and the time required for the last name to engraving the groove depth with money

442829 Amendment _ Case No. 87118977 Λ:-^ V. Description of the Invention (2) 1 0 # m as an example, it may take several hours to tens of hours to start up, plus domestic RIE equipment (SJTU Semiconductor Center) The maximum process capability that can be achieved is also limited to an etching depth of about 2 θ m. This is a big consideration for those who want to engage in research and development of wrinkled thin film elements based on process requirements and overall cost considerations. Obstacle [Summary of the Invention] Therefore, the object of the present invention is to provide a method different from the conventional method for making beryllium pleated film by RIE technology, and to use the isotropic wet tapeworm engraving to form the desired wrinkle, so as to achieve the desired effect. Simple, fast and low cost process. The provided wrinkle thin film process steps according to at least the above-mentioned purposes of the present invention include: providing a silicon substrate; defining a thin film region on a silicon substrate using a first photomask; forming a protective layer on the thin film region; Using isotropic wet etching, a second photomask is used to form a plurality of circular grooves on the film area; and — y removes the protective layer and forms _ wrinkles thin among these multiple grooves' Before the film region is formed, a common edge layer is formed to protect the non-thin film region from forming a -continuous use-anisotropic method substrate, where the region is a mask when the groove is inscribed by the surname and requires a groove; f The protective layer is coated on one side of the silicon substrate formed as an area—to form a groove. After the area of the thin film has not been removed by BOE, the film is first blocked with a side layer, and then HF-ΗNO3-Η. Solution

No. 442829 8711 Correction 77 V. Description of the invention (3) — ^ a The silicon substrate is etched to complete | Ancient Aα 劁 π with concentric circular wrinkled film The following is a description of the following [Examples] First, please refer to " The first is to make the above of the present invention and its: the film version of the invention. The preferred embodiment, in conjunction with the attached drawings; It is easy to understand, the following special mentions--丄: and the advantages can be more clearly illustrated in the base, two Let =: be sensitive and only at a rate of two = depends on the crystal crystallization direction. In other words, the remaining rate will be rt: t Ϊ Ϊ is the most efficient,-general ... 110) > (⑴), so In this example = minus two 'substrate 1G ° After obtaining the dream substrate 10, the initial y θ washing step (Un 111 a 1 c 1 ean 1 ng) must be performed first. The standard RCA cleaning procedure is used to remove particles on the surface of the silicon wafer. Next, referring to "Second Section", an insulating layer 12 is formed on the above-mentioned silicon substrate 10, for example, a layer formed by wet oxidation (we t 〇χ 丨-dation) has a thickness of about 60 angstroms of sand dioxide (Si &) layer. Its main function is to protect the silicon substrate 10 portion where the wrinkled film is not formed when the wrinkled film area is etched later. Next, referring to "Figure 3", the surface of the above-mentioned insulating layer 12 is formed by using a photomask 1 'as shown in "Figure 7" to define a grooved film region 1 4'. Anisotropic etching of potassium hydroxide (KOH) solution etching. In order to etch away the silicon dioxide layer 12 on the thin film region 14, the silicon substrate 10 needs to be immersed in the B0E solution for about seven minutes, and then

44282 9 _ Case No. 87118977-_ month day correction __ V. Description of the invention (4) The KOH surface of the silicon substrate 10 is heated at a temperature of about 60 ° C and a concentration of about 30 wt% KOH for about twenty minutes This can achieve an etching depth of about 6.1 mm. The desired pleated film is formed in the film region 14 of the groove. Then, please refer to "Fig. 4", and again form a protective layer 16 on the etched grooves 14 above. For example, a layer of oxide with a thickness of about 8 0 0 angstroms is also formed by the wet oxidation method. Silicon layer. The main function of the protective layer 6 is to provide an etching mask used as a stripe of the wrinkle plate in the subsequent formation of wrinkles. After that, please refer to "Fig. 5", and a desired wrinkled film will be formed on the aforementioned film region 14. The method used is an isotropic etching method that is completely different from the conventional high energy R I E technology. It is also because of the use of the wet etch technology to form the sensitive pleated film, so the expensive equipment required for the conventional RI E can be eliminated, and the process speed does not need to take more than several hours like RIE. The pattern of the photomask 2 required to form wrinkles in the wet type in this example is shown in FIG. 8 and is a photomask having concentric circular stripes 22. When making a circular wrinkle, the back surface of the silicon substrate 10 (ie, the side without the thin film region 14) needs to be coated firstly with photoresist protection, and then, under the cover of the photomask 2, 'B0E The solution removes the silicon dioxide layer 16 on the thin film region 14 and soaks the entire silicon substrate 10 in the B0E solution for about nine minutes, thereby removing the silicon dioxide layer 16 having a thickness of about 8 0 0 angstroms. And a plurality of circular recesses 162 are formed as shown in the figure. Then ’immerse the silicon substrate 10 in, for example, HF-HN03-H50 solution, and mix and mix with a volume ratio of about 1: 10: 5.

Page 7 442829 __Case No. 87118977_Year, month, day and year__ 5. Description of the invention (5) The liquid 'can produce a large number of grooves 1 8' about 8 mm in about 4 minutes. The desired circular wrinkles are formed in the area 14. However, if the pattern of the mask 2 is changed, wrinkles with different patterns can be defined, for example, a circle with a spiral shape (c ο nv ο 1 uted). Wrinkled. Therefore, according to the shape of the pleated film of the present invention, a desired pro-pleated pattern can be produced by providing the photomask 2 as required. Finally, please refer to "Figure 6". After removing the silicon dioxide 16 in the surface portion of the silicon substrate 10 wrinkles, a diffusion process will be performed. This embodiment uses a planar diffusion device (Boron Ni tr i de, Grade BN-HT 1100 > part No. F40040 'Size 4 " DIA. X 0 -04 ") between \ (1 01) and 〇 2 (25〇 ml) to incorporate boron in silicon to complete the boron ion diffusion process. Operating conditions such as the ambient temperature of 11 ° C, takes about 1.5 hours to produce a boron film 20 about 2.5 # m. In addition, borosilicate glass (BSG) will also be formed in the boron ion diffusion process, so this BSG should be removed. You can use the wet oxidation cake sequence at 90 ° C for about forty minutes, and then immerse it in the βοε solution for about fifty minutes in the step of " b 〇r ο η di lut ion11, which will help to remove BSG thus forms a wrinkled film made of boron. However, in addition to the material of wrinkle film, silicon nitride is the main material. Therefore, depending on the application of the wrinkle film, the desired wrinkle film is formed by the diffusion process of related materials. The finished pleated film obtained by the process of the above embodiment can be taken with the electron microscope photograph of the top view of the film with different magnifications as shown in FIG. 9 and 10, and the film with different magnifications as shown in FIGS. 1 and 12 Electronic display of sectional view

44282 9 a -i: No. 87〗 丨 Shan 77 V. Description of the invention (6) I learned from the micro-mirror photo. When it is formed in practical application of the present invention, “the Shi Xibao is pulled 1”, the side with the thin film region 14 is facing down, and the substrate (bond) is bonded to another substrate, and then the groove 18 is etched away. A desired wrinkle film can be formed by using a portion of the upper substrate 10 and using the shed film 20 as a barrier (etch_stpped) layer. [Effect of the present invention] The present invention uses an isotropic wet etching technique to make a circular wrinkled film. This isotropic wet etching only takes about four minutes in the process cost, and can reach about 10 # m. Etching depth, compared to the traditional anisotropic etching with R ί E, it takes about several hours to several tens of hours to etch the same depth. Obviously, it can be seen that the speed has increased a lot; and, isotropic wet Etching only costs tens of yuan in the cost of the etching solution, that is, the production of the circular sensitive pleated film is completed. Compared with R IE's equipment, tens of millions of funds are needed, and the cost is greatly reduced. Therefore, using the isotropic wet etching technology of the present invention saves time compared to a high-energy device, and can provide a fast and cost-effective way to make a circular wrinkled film. Although the present invention has been defined by a better practice, anyone familiar with this skill and scope can make a little more scope when the attached patent application examples are disclosed above, but they are not intended to be used as a cover. Without deviating from the fine motion and retouching of the present invention, therefore, the ones defined in the March issue of this issue shall prevail.

442829

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Claims (1)

442 82 9 _Case No. 87118977_ Amendment _ VI. Patent Application Scope 1. A method for making a pleated film includes at least the following steps: Provide a silicon substrate; use a first mask on the silicon substrate Define a thin film region; form a protective layer on the thin film region; use isotropic wet etching to form a plurality of circular grooves on the thin film region using a second photomask; and remove the protective layer, and A wrinkle film 02 is formed on the plurality of grooves, and the wrinkle film manufacturing method described in item 1 of the scope of patent application, wherein the thickness of the stone substrate is about 325 · ~ '375 ym. 3. The method for manufacturing a wrinkled film according to item 1 of the scope of patent application, wherein before forming the film region, an insulating layer is formed on the silicon substrate. 4 τ. The method for manufacturing a pleated film as described in item 3 of the scope of the patent application, wherein the insulating layer is a silicon dioxide layer formed by a wet oxidation method. 5. The method for manufacturing a pleated film as described in item 4 of the scope of the patent application, wherein the thickness of the silicon dioxide is about 600 angstroms. 6. The method for manufacturing a wrinkled film as described in item 5 of the scope of the patent application, wherein before forming the full film area, the silicon dioxide layer is removed with a BOE solution, which takes about 7 minutes. 7. The method for manufacturing a wrinkled film according to item 1 of the scope of patent application, wherein the film region is etched to form a groove by using an anisotropic etching method. Page 11 442829 _ Case No. 87118977 _ Month and Day __ VI. Application for patent scope 8, the method for making a wrinkled film as described in item 7 of the patent scope, wherein the groove is etched with a KOH solution for about At 0 minutes, the depth formed is about 6.1 / zm. 9. The method for manufacturing a pleated film as described in item 8 of the scope of patent application, wherein the concentration of the KOH solution is about 30 wt%, and the operating temperature is about 60 t. 10. The method for manufacturing a wrinkled film as described in item 1 of the scope of the patent application, wherein the protective layer is a silicon dioxide layer formed by a wet oxidation method, and is used as a mask when the grooves are engraved by the surname. cover. 11. The method for manufacturing a pleated film as described in item 10 of the scope of the patent application, wherein the thickness of the silicon dioxide layer is about 80,000 angstroms. 12. The method for manufacturing a wrinkled film as described in item 1 of the scope of patent application, wherein before forming the grooves, one side of the substrate without the film area is coated with a layer of photoresist protection. 1 3. The method for manufacturing a pleated film as described in item 1 of the scope of patent application, wherein the formation of the grooves is firstly removing the protective layer with a BOE solution, and then using an HF-Η N _ H2 0 The solution is engraved with money ° 14. The method for making a wrinkled film as described in item 13 of the scope of patent application, wherein the operating time of the BOE solution is about 9 minutes to remove the protective layer 1 of about 8 0 0 angstroms. 5. The method for manufacturing a pleated film as described in item 13 of the scope of the patent application, wherein the volume ratio of the HF-HN03-H20 solution is 1: 1 0: 5, and the operation time is about 4 minutes. 1 0 " m of these four trenches. Page 12 442829 _ Case No. 87118977 _ Month and Day __ VI. Application for a patent range 16 and the method for making a wrinkle film as described in item 1 of the patent application range, wherein the wrinkle film is deposited by ion diffusion Law formation. 17. The method for manufacturing a pleated film as described in item 16 of the scope of patent application, wherein the ion diffusion deposition is a boron ion diffusion process. 18. The method for manufacturing a pleated film as described in item 17 of the scope of the patent application, wherein the operating conditions of the boron ion diffusion process are a planar diffusion device: Boron Nitride 'Grade BN-HT 1100, Part No. F40040 'Size 4 " DIA. X 0 · 04π, with N2 and 02 at a temperature of about 110 ° C, it takes about 1 to 5 hours to form a stone film of about 2.5 mm. Page 13