Method for manufacturing silicon escapement wheel

Abstract

The invention discloses a method for preparing a silicon escapement wheel, and belongs to the technical field of micro-nano machining. The method provided by the invention comprises the following steps: providing a thin silicon wafer with a target thickness, and etching one surface of the thin silicon wafer to form a plurality of blind holes; preparing a soft mask on the surface of one side, deviating from the blind hole, of the thin silicon wafer; etching one side of the soft mask on the thin silicon wafer so as to etch through the bottom of the blind hole to form a cantilever beam structure of the silicon escapement wheel; and taking down the silicon escapement wheel from the blind hole to obtain the free silicon escapement wheel. According to the method, the cantilever beam structure is formed, parts can be collected more easily, the problem of high-precision equipment needed by the bonding and glue filling process is solved, large-batch silicon escapement wheels can be simply prepared, meanwhile, the problem of side wall inclination angle caused by the fact that deep etching is needed at a time is solved, high quality of the side wall of the silicon escapement wheel is achieved, and the production efficiency is improved. And a solution is provided for preparing large-batch and high-yield silicon escapement wheel devices.

Description

Technical Field

[0001] This application relates to a method for fabricating a silicon escapement wheel, belonging to the field of micro-nano fabrication technology. Background Technology

[0002] Compared with traditional metal escape wheels (such as steel, brass, nickel alloys, etc.), silicon escape wheels have achieved significant breakthroughs in performance, stability, and maintenance costs due to their material properties and processing advantages. They have become a key upgrade direction, especially in high-end watchmaking and precision instruments. The core advantages of silicon escape wheels are: (1) More stable physical properties and strong resistance to environmental interference. The inherent properties of silicon fundamentally solve the problem of "environmental sensitivity" of metal escape wheels. They perform better in complex scenarios such as temperature, humidity, and magnetic fields: extremely low coefficient of thermal expansion, strong temperature adaptability; natural antimagnetism, no need for antimagnetic coating; strong corrosion resistance, no fear of humidity and chemical corrosion; (2) Lower friction loss and higher energy transmission efficiency. As the "core of energy transmission", the friction loss of the escape wheel directly affects the power endurance and stability of precision equipment. Silicon has a natural advantage in this dimension: low coefficient of friction + high surface hardness, reducing wear; no need for lubricating oil, avoiding the hidden danger of "sludge pollution"; (3) Lightweight design, improving dynamic response speed. The low density of silicon Far lower than metal, it can achieve a "lightweight + high strength" structural design and optimize dynamic performance: reduce rotational inertia and improve energy utilization; support hollow / complex topology structure to further reduce weight; (4) higher processing precision, better consistency and standardization. Silicon relies on MEMS (micro-electromechanical systems) processes (such as photolithography, deep reactive ion etching DRIE) for processing, and the precision is far superior to traditional metal processing (such as milling, grinding): micron-level tolerance, better meshing precision; wafer-level mass production, higher consistency; (5) better long-term cost and high cost-effectiveness throughout the entire life cycle. Although the initial processing cost (equipment, clean room) of silicon escape wheel is higher than that of metal wheel, the cost throughout the entire life cycle is lower: reduce maintenance and replacement costs; adapt to automated assembly and reduce labor costs.

[0003] The advantage of silicon escapements lies in the synergistic breakthrough of "material properties + micro-nano technology"—it solves the inherent pain points of metal escapements, such as "susceptibility to magnetism, temperature changes, wear, and maintenance," while simultaneously improving the dynamic performance and reliability of precision equipment through lightweight and high-precision design. Currently, silicon escapements have expanded from high-end watchmaking to aerospace (micro inertial navigation), medical devices (precision pumps and valves), and consumer electronics (micro motors), becoming an important development direction for "high-precision transmission structures." However, the fabrication technology of silicon escapements still faces challenges such as complex and difficult bonding processes, challenging thinning processes, and potential risks in resist removal processes. To address these issues, researchers are working to improve the precision of photolithography etching equipment, increase the detection capabilities of etching equipment, and develop new fabrication processes. For reliability and stability, they are also implementing strict quality control and real-time monitoring. Summary of the Invention

[0004] To address the challenges of bonding and thinning processes in existing silicon escapement wheel fabrication technologies, this application provides a technical solution for fabricating silicon escapements. First, photolithography is performed on the back side of the silicon wafer to create a blind hole larger than the pattern on the front side. Then, photolithography is performed on the front side to overlay the escapement wheel pattern, followed by etching to obtain the entire escapement wheel cantilever beam structure. Subsequently, atomic layer deposition of metal is performed on the wafer to enhance the mechanical strength of the escapement wheel components. Finally, the escapement wheel components are removed.

[0005] The technical solution adopted in this application is as follows: According to a first aspect of this application, a method for manufacturing a silicon escapement wheel is provided, comprising: A thin silicon wafer of the target thickness is provided, and a plurality of blind holes are etched on one side of the thin silicon wafer; A soft mask is prepared on the surface of the thin silicon wafer opposite to the blind via. Etching is performed on one side of the soft mask on the thin silicon wafer to etch through the bottom of the blind hole to form a cantilever beam structure of the silicon escapement wheel; The silicon escape wheel is removed from the blind hole to obtain a free silicon escape wheel.

[0006] Optionally, the diameter of the blind hole is larger than the diameter of the free silicon escape wheel.

[0007] Optionally, the depth of the blind hole is 50~400 μm.

[0008] Optionally, before removing the silicon escape wheel from the blind hole, the method further includes: Metal is deposited onto the thin silicon wafer to form a metal layer to cover the cantilever beam structure of the silicon escapement wheel.

[0009] Optionally, the thickness of the metal layer is 5~30 μm.

[0010] Optionally, the material of the metal layer is selected from at least one of Al, Ni, Cu, Pt, and Ti.

[0011] Optionally, the etching of a plurality of blind vias on one side of the thin silicon wafer includes: Photoresist is coated on one side of the thin silicon wafer; The photoresist is selectively exposed and developed to form blind hole pattern windows; Dry etching is performed on one side of the blind hole pattern window of the thin silicon wafer to form several blind holes on the surface of the thin silicon wafer, and excess photoresist is removed.

[0012] Optionally, fabricating a soft mask on the surface of the thin silicon wafer opposite to the blind via includes: Photoresist is applied to the side of the thin silicon wafer opposite to the blind hole; After selective exposure and development of the photoresist, a soft mask with an escapement wheel pattern is obtained.

[0013] Optionally, etching one side of the soft mask on the thin silicon wafer includes: The thin silicon wafer area at the bottom of the blind hole is etched under the cover of the soft mask, with an etching depth of 80~200 μm. After etching, the soft mask is removed.

[0014] Optionally, the thin silicon wafer is obtained by thinning a silicon wafer or silicon wafer.

[0015] The beneficial effects of this application include: (1) This application first etches a blind hole on the back side that is larger than the escape wheel pattern on the front side, and forms a cantilever beam structure during the dry etching process, which is more conducive to collecting parts and also facilitates cleaning, atomic layer deposition and other processes.

[0016] (2) This application utilizes a pre-etching scheme to solve the problem of high-precision equipment required for bonding and filling processes, enabling the simple preparation of large quantities of silicon escape wheels. It also avoids the sidewall tilting problem caused by the need for a deep etching thickness at one time, thus achieving high quality of the silicon escape wheel sidewall.

[0017] (3) The preparation method of this application does not introduce resin or other substances, which increases the cleanliness of the device and avoids the impact of residues on the device performance due to incomplete cleaning, thus realizing the mass production of silicon escapement wheels. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a wafer fabrication process for dry etching to prepare large-size blind holes on the back side, as described in this application. Figure 2 This is a process flow diagram of a method for dry etching to prepare a silicon escape wheel cantilever beam structure according to this application; Figure 3 This is a schematic diagram of the process from cantilever beam structure to fabrication of a complete silicon escapement device in this application; Figure 4 This is a schematic diagram of the process for preparing a silicon escapement using the silicon wafer thinning method described in this application. Detailed Implementation

[0019] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0020] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0021] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.

[0022] In existing technologies for fabricating silicon escape wheels, the silicon wafer thinning method involves etching an escape wheel structure on one side of a single-crystal silicon wafer using photolithography and deep reactive ion etching. The escape wheel structure on one side of the single-crystal silicon wafer is then bonded to a hard material layer using a cured resin. The side of the single-crystal silicon wafer facing away from the escape wheel structure is then thinned to expose the escape wheel structure. Finally, the cured resin is removed to obtain a free silicon escape wheel component. However, this technology also faces some technical challenges and limitations. The main problems include: (1) the complexity and difficulty of the bonding process. When bonding the escape wheel structure on one side of the single-crystal silicon wafer to a hard material layer using a cured resin, it is necessary to precisely control parameters such as the amount of resin applied, the curing temperature, and the time. If the resin coating is uneven or the curing conditions are not suitable, the bonding strength may be insufficient. In subsequent processes, the silicon escape wheel is easy to separate from the hard material layer, affecting the product quality. During the bonding process, bubbles or impurities may be generated. These defects will affect the bonding quality between the silicon escape wheel and the hard material layer, and thus affect the performance and stability of the silicon escape wheel. (2) The thinning process is difficult: When thinning the bonded sheet, it is very difficult to accurately control the thickness and uniformity of the thinning. Excessive thinning may lead to insufficient support of the silicon escape wheel structure, affecting its mechanical properties. Uneven thinning will cause the silicon escape wheel to generate uneven stress distribution during vibration, affecting its timekeeping accuracy. In addition, if the filling process is uneven, it will lead to unbalanced force during thinning, which may cause the device to fly out or crack during the thinning process, which is not conducive to the maintenance of the thinning machine. (3) Potential risks of the de-curing process: When removing the cured resin, the organic solvent or plasma treatment method used may corrode the silicon escape wheel, reducing the mechanical strength and reliability of the silicon escape wheel. Furthermore, after obtaining the free silicon escapement wheel parts, the post-processing of individual parts (such as cleaning, thermal oxidation, and metal deposition) is also a challenge. For example, during the cleaning process, the transfer between cleaning liquids always results in the loss of some silicon escapement wheel parts. Given the complexity of the cleaning process, the final yield may not be very high. If coating is required on the silicon escapement wheel, it always necessitates two processes on both sides, increasing equipment costs and making it more difficult to control the sidewalls.

[0023] To address at least one of the aforementioned technical problems, this application provides a fabrication method for silicon escapement wheels. First, photolithography is performed on the back side of the silicon wafer to create a blind hole larger than the pattern on the front side. Then, photolithography is performed on the front side to overlay the escapement wheel pattern, followed by etching to obtain a complete silicon escapement wheel cantilever beam structure. Subsequently, atomic layer deposition of metal is performed on the wafer to enhance the mechanical strength of the silicon escapement wheel component. Finally, the silicon escapement wheel component is removed, providing a solution for the mass production of high-yield silicon escapement wheel devices.

[0024] According to one embodiment of this application, a method for preparing a silicon escapement wheel includes: A thin silicon wafer of the target thickness is provided, and a plurality of blind holes are etched on one side of the thin silicon wafer; A soft mask is prepared on the surface of the thin silicon wafer opposite to the blind via. Etching is performed on one side of the soft mask on the thin silicon wafer to etch through the bottom of the blind hole to form a cantilever beam structure of the silicon escapement wheel; The silicon escape wheel is removed from the blind hole to obtain a free silicon escape wheel.

[0025] In one embodiment, providing a thin silicon wafer of the target thickness includes cleaning, drying, and baking the thin silicon wafer.

[0026] In one embodiment, providing the target thickness of the thin silicon wafer further includes polishing at least one side of the thin silicon wafer.

[0027] In one embodiment, the diameter of the blind aperture is larger than the diameter of the free silicon escape wheel. Only when the diameter of the blind aperture is larger than the escape wheel pattern can the escape wheel outline be etched around the bottom region of the blind aperture during front etching, separating the edge of the silicon escape wheel from the silicon wafer body and connecting it only through the unetched bottom center region (i.e., the root of the cantilever beam). The diameter of the blind aperture is larger than the diameter of the free silicon escape wheel so that at least one silicon escape wheel cantilever beam structure can be fabricated within the blind aperture, which also facilitates the collection of silicon escape wheel devices and reduces losses.

[0028] In one embodiment, the depth of the blind hole is 50~400 μm. This depth directly determines the thickness of the "beam" formed by the subsequent front etching to create the escapement wheel structure. This thickness range ensures that the final silicon escapement wheel has a suitable thickness, thereby possessing sufficient mechanical strength (such as bending resistance and fatigue resistance) to meet the usage requirements of watch silicon escapement wheels. If the depth is too shallow, the part will be too thin and fragile; if it is too deep, it will easily cause the sidewalls to tilt, affecting the sensitivity and overall size of the mechanism. The depth of the blind hole is preferably 200~300 μm.

[0029] In one embodiment, before removing the silicon escape wheel from the blind hole, the method further includes: A metal layer is deposited on the thin silicon wafer to form a metal layer that covers the cantilever beam structure of the silicon escapement wheel. The deposited metal layer significantly increases the hardness, wear resistance, and overall structural strength of the silicon escapement wheel, extending its service life. This directly solves the problem that the adhesive removal process in the prior art may weaken the strength of the parts. In addition, the fabrication process of this application is carried out on a whole thin silicon wafer, and the coating of tens of thousands of silicon escapement wheels can be completed in one go, which is extremely efficient. At the same time, since the parts are not yet free and have a cantilever beam structure, the metal deposition can uniformly cover all surfaces (front, back, and sidewalls), perfectly solving the problem in the prior art that requires two operations on the free parts to complete double-sided coating, reducing equipment costs and process complexity, and ensuring the coating quality of the sidewalls.

[0030] In one embodiment, the thickness of the metal layer is 5-30 μm. This thickness is used to provide sufficient mechanical reinforcement while being well controlled through precise deposition techniques to avoid excessively altering the geometry of the silicon escapement design, thus ensuring its functionality. The preferred thickness of the metal layer is 8-10 μm.

[0031] In one embodiment, the metal layer is selected from at least one of Al, Ni, Cu, Pt, and Ti. These metals all possess good mechanical properties (hardness, toughness), adhesion to the silicon substrate, and mature microfabrication deposition processes. For example, Ni is highly wear-resistant, Ti has good adhesion, Al and Cu are lightweight and have good electrical conductivity (if other functions are required), and Pt has excellent chemical stability. A variety of material choices are provided to meet different application requirements, with Ni and Al being preferred materials for the metal layer.

[0032] In one embodiment, the etching of a plurality of blind vias on one side of the thin silicon wafer includes: Photoresist is coated on one side of the thin silicon wafer; The photoresist is selectively exposed and developed to form blind hole pattern windows; Dry etching is performed on one side of the blind via pattern window on the thin silicon wafer to form several blind vias on the surface of the thin silicon wafer, removing excess photoresist. This application uses standard photolithography and dry etching processes, meaning that this step is compatible with existing, mature semiconductor production lines, and the process is stable, highly controllable, and highly repeatable. Dry etching (such as DRIE) can obtain blind vias with steep sidewalls and precise morphology, laying a good foundation for subsequent steps.

[0033] The thickness of the photoresist coating is 6 μm to 20 μm, preferably 10 μm to 14 μm; Exposure dose at 160 mJ / cm 2 ~500 mJ / cm 2Preferably 200 mJ / cm 2 ~250 mJ / cm 2 ; After development, the film is hardened at 90℃ to complete the blind hole pattern photolithography step.

[0034] In one embodiment, fabricating a soft mask on the surface of the thin silicon wafer opposite to the blind via includes: Photoresist is applied to the side of the thin silicon wafer opposite to the blind hole; Selective exposure and development of the photoresist yields a soft mask with an escapement wheel pattern. Using photoresist as a "soft mask" is a simple and low-cost process. The key is that this step requires overlaying the pattern with the blind aperture pattern on the back side to ensure that the escapement wheel pattern on the front side is within the blind aperture area. Successful overlay is a prerequisite for realizing the cantilever beam structure and demonstrates the precision of the process. The thickness of the photoresist coating is 6 μm to 15 μm, preferably 8 μm to 12 μm; The exposed pattern is an escapement wheel, and the exposure dose is 160 mJ / cm². 2 ~500 mJ / cm 2 Preferably 200 mJ / cm 2 ~250mJ / cm 2 ; After development, the film is hardened at 90℃ to complete the photolithography step of the escapement wheel pattern.

[0035] In one embodiment, etching one side of the soft mask on the thin silicon wafer includes: Under the cover of the soft mask, the thin silicon wafer area at the bottom of the blind via is etched to a depth of 80-200 μm. After etching, the soft mask is removed. The etching depth of 80-200 μm, combined with the depth of the blind via on the back (50-400 μm), determines the actual thickness of the escapement wheel. This range is a typical thickness optimization value for watch escapement wheels. Furthermore, this step only needs to etch through the remaining silicon thickness at the bottom of the blind via, rather than the entire silicon wafer thickness, avoiding the difficulties of deep silicon etching, improving etching quality (sidewall perpendicularity) and efficiency, and reducing the risk of equipment wear and process fluctuations that may result from long-term etching.

[0036] In one embodiment, the thin silicon wafer is obtained by thinning a silicon wafer or silicon wafer. Obtaining a thin silicon wafer of the target thickness is a mature process route. That is, first use silicon wafers or silicon wafers of standard thickness, and then process them to the required thickness through thinning techniques such as grinding and polishing. The high feasibility of the process allows the method of this application to be well integrated with the existing silicon wafer processing industry chain.

[0037] In one embodiment, the method for fabricating a silicon escapement wheel includes the following steps: Step 1: Cleaning. Take one double-polished silicon wafer and ultrasonically clean it successively in acetone, isopropanol and deionized water, then dry it with nitrogen and bake it. Step 2: Backside photolithography etching. For example... Figure 1 As shown, one side of the silicon wafer is coated with PR photoresist, followed by exposure. The exposure pattern consists of circular holes slightly larger than the silicon escapement wheel. Development is then performed, followed by hardening at 90°C to complete the photolithography step. Next, deep reactive ion etching (DRIE) is performed, followed by photoresist removal to obtain a silicon wafer with blind vias etched on the back side.

[0038] Step 3: Front-side photolithography. (e.g.) Figure 2 As shown, PR photoresist is coated on the other side of the silicon wafer, followed by exposure. The exposed pattern is an escapement wheel, which is connected to the silicon wafer as a whole by a partial cantilever beam structure. Then, development is performed, and finally hardening is carried out at 90°C to complete the photolithography step of the silicon escapement wheel.

[0039] Step 4: Etching. For example... Figure 2 As shown, the escape wheel pattern is etched using deep reactive ion etching (DRIE), and the resist is removed after etching to obtain the cantilever beam structure of the silicon escape wheel.

[0040] Step 5: Atomic layer deposition. For example... Figure 3 As shown, atomic layer deposition (ALD) is performed on silicon escapement wheel wafers to enhance the structural strength of the silicon escapement wheel.

[0041] Step 6: Remove the component. Use tweezers or other tools to remove the silicon escape wheel from the silicon wafer to obtain a free silicon escape wheel device, thus completing the fabrication.

[0042] Example 1 Step 1: Cleaning. Take one double-polished silicon wafer and ultrasonically clean it successively in acetone, isopropanol and deionized water, then dry it with nitrogen and bake it. Step 2: Backside photolithography etching. A PR photoresist layer with a thickness of 12 μm is applied to one side of the silicon wafer. Exposure is then performed, with the exposure pattern consisting of circular holes slightly larger than the silicon escapement wheel, at a dose of 200 mJ / cm². 2 Following development, a hardening process is performed at 90°C to complete the photolithography step. Next, deep reactive ion etching (DRIE) is performed to a depth of 250 μm. Afterward, resist removal is completed, yielding a silicon wafer with blind vias etched on the back side.

[0043] Step 3: Front-side photolithography. A PR photoresist layer with a thickness of 10 μm is coated on the other side of the silicon wafer. Exposure is then performed, with the pattern being an escapement wheel connected to the silicon wafer via a partially cantilever beam structure. The exposure dose is 220 mJ / cm².2 The process then involves development, followed by hardening at 90°C to complete the photolithography steps for the silicon escapement wheel.

[0044] Step 4: Etching. The escape wheel pattern is etched using deep reactive ion etching (DRIE) to a depth that penetrates the silicon wafer. After etching, the resist is removed to obtain the cantilever beam structure of the silicon escape wheel.

[0045] Step 5: Atomic Layer Deposition. Atomic layer deposition (ALD) is performed on the silicon escapement wheel wafer. The composition is Al, and the thickness is 2 nm. This enhances the structural strength of the escapement wheel, completing the fabrication of the silicon escapement wheel.

[0046] Step 6: Remove the component. Use tweezers or similar tools to remove the silicon escape wheel from the silicon wafer, obtaining a free silicon escape wheel device.

[0047] Comparative Example 1: Preparation of escapement wheel using silicon wafer filler thinning method This comparative example uses a typical silicon wafer filler thinning method to fabricate a silicon escapement wheel as an example. The steps are as follows: Figure 4 As shown, it includes: Step 1: Cleaning. Take two ordinary silicon wafers and ultrasonically clean them successively in acetone, isopropanol and deionized water, then dry them with nitrogen and bake them. Step 2: Photolithography. A PR photoresist is coated onto the clean silicon wafer surface to a thickness of 5 μm. Exposure is then performed at a dose of 240 mJ / cm². 2 Then development is performed to complete the photolithography step of the silicon escapement wheel.

[0048] Step 3: Etching. Dry etching is performed on the photomask to a depth of 150 μm. After etching, the resist is removed to achieve the patterning of the silicon escapement wheel.

[0049] Step 4: Epoxy Bonding. A layer of epoxy resin is first spin-coated onto the etched wafer surface to fill the gaps in the pattern and ensure the flatness of the wafer surface. Bonding then occurs, with the epoxy-coated side bonded to the polished surface of another silicon wafer.

[0050] Step 5: Thinning. Thin the back side coated with epoxy resin until the front pattern is visible, then stop thinning.

[0051] Step 6: Release the part. The bonded sheet is heated and soaked in NMP (N-methylpyrrolidone), which dissolves the epoxy resin between the gaps in the escape wheel pattern, resulting in the released free silicon escape wheel part.

[0052] In summary, compared to the comparative silicon wafer thinning method using adhesive filling, the embodiments of this application achieve fundamental improvements in process flow, structural integrity, and mass production feasibility. The comparative method relies on a complex path of "bonding-thinning-removal," where the adhesive bonding step is prone to air bubbles or weak bonding. The overall thinning process requires extremely high thickness uniformity; unevenness can lead to component ejection or wafer cracking. Furthermore, using NMP heating for adhesive removal carries the risk of corroding the silicon structure. The technical solution of this application completely eliminates the bonding and adhesive removal steps, simplifying the process to a standard micromachining flow through a direct route of "backside pre-etched blind vias - frontside etching." This fundamentally eliminates defects introduced by resin and the risk of solvent corrosion, resulting in a shorter process chain and greater controllability. Regarding structural forming quality, in the comparative method, a typical silicon wafer thinning method using adhesive filling, the silicon escapement wheel is temporarily fixed by fragile epoxy resin, making it susceptible to damage during the adhesive removal process. The core innovation of this application lies in forming a "cantilever beam structure," ensuring that the component is reliably supported by the silicon body until final removal. This key advantage enables atomic layer deposition enhancement (ALD) to be performed efficiently and uniformly across the entire wafer, completing metal coating on all component surfaces in a single operation, significantly enhancing mechanical strength and wear resistance. In contrast, the comparative method struggles to achieve uniform batch coating on free components, resulting in low yield and consistency. For mass production, the comparative method suffers from high loss rates during the cleaning and transfer of free components, and requires high precision and costly bonding and thinning equipment. This application, however, achieves true wafer-level batch manufacturing. Pre-etched blind vias decompose the deep silicon etching task, avoiding the sidewall tilting problem of single-stage deep etching, improving pattern accuracy, achieving high component collection efficiency and extremely low loss, while significantly reducing equipment investment and maintenance costs. In summary, this application demonstrates decisive technological advantages over traditional methods in simplifying processes, improving component quality, ensuring high yield, and reducing manufacturing costs.

[0053] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing a silicon escapement wheel, characterized in that, include: A thin silicon wafer of the target thickness is provided, and a plurality of blind holes are etched on one side of the thin silicon wafer; A soft mask is prepared on the surface of the thin silicon wafer opposite to the blind via. Etching is performed on one side of the soft mask on the thin silicon wafer to etch through the bottom of the blind hole to form a cantilever beam structure of the silicon escapement wheel; The silicon escape wheel is removed from the blind hole to obtain a free silicon escape wheel.

2. The method for preparing a silicon escapement wheel according to claim 1, characterized in that, The diameter of the blind hole is larger than the diameter of the free silicon escape wheel.

3. The method for preparing a silicon escapement wheel according to claim 1, characterized in that, The depth of the blind hole is 50~400um.

4. The method for preparing a silicon escapement wheel according to claim 1, characterized in that, Before removing the silicon escape wheel from the blind hole, the procedure further includes: Metal is deposited onto the thin silicon wafer to form a metal layer to cover the cantilever beam structure of the silicon escapement wheel.

5. The method for preparing a silicon escapement wheel according to claim 4, characterized in that, The thickness of the metal layer is 5~30um.

6. The method for preparing a silicon escapement wheel according to claim 4, characterized in that, The metal layer is made of at least one of Al, Ni, Cu, Pt, and Ti.

7. The method for preparing a silicon escapement wheel according to claim 1, characterized in that, The etching process to form several blind holes on one side of the thin silicon wafer includes: Photoresist is coated on one side of the thin silicon wafer; The photoresist is selectively exposed and developed to form blind hole pattern windows; Dry etching is performed on one side of the blind hole pattern window of the thin silicon wafer to form several blind holes on the surface of the thin silicon wafer, and excess photoresist is removed.

8. The method for preparing a silicon escapement wheel according to claim 1, characterized in that, The process of fabricating a soft mask on the surface of the thin silicon wafer opposite to the blind via includes: Photoresist is applied to the side of the thin silicon wafer opposite to the blind hole; After selective exposure and development of the photoresist, a soft mask with an escapement wheel pattern is obtained.

9. The method for preparing a silicon escapement wheel according to claim 1, characterized in that, The etching of one side of the soft mask on the thin silicon wafer includes: The thin silicon wafer area at the bottom of the blind hole is etched under the cover of the soft mask, with an etching depth of 80~200um. After etching, the soft mask is removed.

10. The method for preparing a silicon escapement wheel according to claim 1, characterized in that, The thin silicon wafer is obtained by thinning a silicon wafer or silicon wafer.

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