Thin silicon micro-mold supported by reinforcing structure and manufacturing method of thin silicon micro-mold
By introducing rigid reinforced structures into thin silicon micro molds, the problem of warping and cracking of thin silicon micro molds during processing is solved, its mechanical strength and flatness are improved, high-precision microstructure forming is achieved, and its expansion is achieved Application scope.
Patent Information
- Application Number
- CN202411222832.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-02
- Publication Date
- 2024-12-13
AI Technical Summary
In the prior art, thin silicon micro molds are prone to warping and breaking during processing, resulting in poor molding accuracy and consistency. When the thickness is less than 100 microns, it is difficult to effectively pattern and etch, which affects the molding quality of the microstructure. .
By introducing rigid reinforcement structures such as wafer bonding technology, double-sided etching of single-chip silicon wafers or using silicon substrates on insulators, thin silicon micro-molds with reinforcements ensure their mechanical strength and surface flatness, thus at high Maintain good processing performance in the precision manufacturing environment.
It significantly improves the mechanical strength and surface flatness of thin silicon micro molds, enhances the accuracy and yield of microstructure forming, broadens its application range in multi-layer microstructure forming, and solves the fragility and difficulty in stacking of thin silicon wafers. question.
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Abstract
Description
Technical Field
[0001] The present invention relates to a patterned thin silicon micro mold and a design and manufacturing method thereof with enhanced flatness and stability, and a technology for using the thin silicon micro mold to manufacture a micro structure or as a micro structure itself. Background Art
[0002] Molding refers to the manufacturing process of shaping liquid or flexible materials using a rigid frame called a mold. The mold is usually a block with a hollow pattern. The liquid or flexible material hardens or solidifies inside the mold to form the same shape as the mold. Traditional molding types include powder metallurgy plus sintering, compression, extrusion, injection molding, lamination, spin casting and thermoforming. Micromolding refers to the method and process of producing micron and nanometer-scale component structures. With the reduction in size, complex geometric features and the need for high aspect ratios, it has become particularly important to use silicon micromachining technology to manufacture micro molds. Micro molds have micron and nanometer-scale hollow patterns, so they can also be used as micro optical components themselves.
[0003] US Patents US7124994 and US6861339 (published by Morales in 2006) disclose a method for manufacturing an electroplated silicon micromold by depositing a conductive thin metal layer on a silicon substrate having a channel or shape that penetrates the silicon wafer. The method produces a microstructure by depositing a conductive surface as an electroplating seed layer on the silicon wafer surface before patterning it, and the channel and shape define the microstructure to be formed by electroplating. After the electroplating is completed, the silicon mold is removed (for example, by etching) to obtain a microstructure and / or component made of the electroplated metal. However, the method involves etching through industry standard silicon wafers, which are typically 300 microns or thicker. Etching through such a thick silicon wafer is a difficult and time-consuming process, especially for small lateral features. Moreover, the deposited metal may not be fully compatible with the etching chemicals used for silicon micromachining. In addition, since the metal seed layer is deposited on the silicon micromold, electroplating can only be performed on the seed layer, so the method cannot be used to electroplate the microstructure directly onto another object (such as a separate wafer).
[0004] U.S. Pat. No. 6,242,163 B1 (published by Stampfl et al. in 2001) discloses a method for manufacturing micro ceramic and metal parts using a multilayer silicon mold stack, each silicon wafer has a specific pattern, a pattern layer is formed by etching, and then the silicon wafers are aligned and bonded together using a wafer bonder. This method is suitable for standard silicon wafers with a thickness of up to 300 microns, but when the thickness drops below 300 microns, especially below tens of microns, the silicon wafer becomes very soft and fragile, and the patterning and etching process cannot be performed using standard photolithography technology. For example, when spin coating photoresist on a thin silicon wafer, the thin silicon wafer will break due to the need to apply a vacuum to fix it on the wafer block. Even if a pattern that runs through the silicon wafer is successfully generated on a thin silicon wafer, it is difficult to further stack multiple thin silicon wafers in uniform contact on the surface due to the low rigidity of the thin silicon wafer. The lack of rigidity of a thin silicon mold with a thickness of less than 100 microns can easily lead to problems in the bonding process, such as the generation of gap areas during bonding, raised areas caused by uneven surface contact, and possible cracks or other physical damage. Summary of the invention
[0005] The present invention provides a thin silicon micro-mold device and a manufacturing method with a rigid reinforcement, which can significantly improve the mechanical strength and surface flatness of the thin silicon micro-mold, thereby improving the accuracy and yield of the microstructure molding process, broadening its application range in multi-layer microstructure molding, and overcoming the technical difficulties in existing thin silicon wafer processing.
[0006] The thin silicon micro mold manufacturing method involved in the present invention greatly improves the mechanical stability and processing feasibility of the thin silicon wafer by introducing a rigid reinforcement structure. The thin silicon wafers in the prior art are prone to warping, cracking and other problems during micro-machining due to their small thickness, which affects the molding accuracy and consistency of the final microstructure. The reinforcement structure provided by the present invention can effectively reduce the deformation of the thin silicon wafer during the processing process, ensuring that the thin silicon micro mold has good processing performance in a manufacturing environment with high precision requirements.
[0007] The present invention connects a thin silicon micro mold with a thick, rigid reinforcement member, so that the thin silicon wafer can maintain good mechanical strength and surface flatness while reducing the thickness. For example, in one manufacturing method, the etched silicon wafer is combined with a thick supporting substrate through wafer bonding technology, and then the silicon wafer is thinned to form a mold pattern. Thereafter, photolithography and etching are performed on the other side of the thin silicon wafer to form a rigid reinforcement structure.
[0008] In another manufacturing method, instead of using wafer bonding technology, a thin silicon micro-mold with reinforcements is manufactured by double-sided etching of a single silicon wafer. Both sides of the silicon wafer are photolithographically patterned to form a surface pattern, then one side is etched to form the reinforcement, and the other side is etched to obtain a mold pattern that runs through the silicon wafer.
[0009] In another manufacturing method, a silicon-on-insulator (SOI) substrate is used. First, both sides of the SOI substrate are photolithographically processed in sequence, then a mold opening is etched on one side to form a reinforcement, and then a mold pattern is etched on the other side; wherein the buried oxide layer of the SOI substrate serves as an etching stop layer to limit the etching depth.
[0010] In another manufacturing method, a thin silicon wafer with a pattern is attached to a thick and rigid frame to generate a stable thin silicon micro mold. The mold pattern is first formed on the thin silicon wafer by photolithography and etching, and then the reinforcement is attached to the thin silicon edge using a variety of connection methods, such as mechanical clamping or tape bonding. This method is suitable for silicon wafers thicker than 100 microns.
[0011] The thin silicon micro mold assembly of the present invention can be used to produce micro structures. For example, the micro mold assembly can be a network of mechanically connected square patterns, and then the metal column array is electroplated onto the functional receiving substrate. If the functional receiving substrate is not conductive, a metal seed layer needs to be coated. After the electroplating is completed, the thin silicon micro mold is removed by an etching process. The thin silicon micro mold of the present invention can also be a hexagonal micro window array, used as an optical window, filter or diffraction grating.
[0012] The thin silicon micro-mold of the present invention can also be applied to the manufacture of complex three-dimensional microstructures by multi-layer stacking, in which patterns throughout the silicon wafer are stacked to form free space areas, and then filled with materials to form microstructures with various geometric designs. During the stacking process, the thin silicon micro-mold layers can maintain good flat contact with each other through the support of each micro-mold reinforcement to ensure accurate molding of the microstructure. For example, when making high-precision optical devices, multi-layer stacking of thin silicon micro-molds can be used to generate complex optical surface contours to optimize optical performance.
[0013] The thin silicon micro mold manufacturing method of the present invention is suitable for the molding of high-precision microstructures. By introducing a rigid reinforcement structure, the present invention solves the technical problems of existing thin silicon micro molds such as fragility, insufficient mechanical strength, difficulty in processing, and inability to stack, improves the mechanical strength, processing performance and manufacturing yield of the thin silicon micro mold and its stacking, and can conveniently perform electroplating molding of the micro structure on a receiving substrate, so that it has broad application prospects in microelectronic devices, optical devices and other application fields requiring high precision and high flatness. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0015] Figure 1 It is a cross-sectional view of a layered silicon micro mold disclosed in U.S. Pat. No. 6,242,163 B1 (prior art), where silicon wafers 12, 14 and 16 are stacked together to generate mold 10;
[0016] Figure 2 For US Patent US6242163B1 (prior art) Figure 1 A cross-sectional view of a microstructure produced in the mold shown, with each silicon mold layer 12, 14 and 16 contributing a three-dimensional portion to the final microstructure;
[0017] Figure 3 Schematic diagram of a five-micron-thick silicon wafer. Without a rigid reinforcement ring, the thin silicon wafer bends and curls into a thin silicon roll due to the different surface stresses on both sides, highlighting the importance of applying rigid reinforcements to obtain thin silicon wafers with high flatness.
[0018] Figure 4 A schematic diagram of a thin silicon wafer suspended by a rigid reinforcement ring, wherein the rigid reinforcement ring is used to enhance the flatness and stability of the thin silicon wafer;
[0019] Figure 5 It is a cross-sectional view of a silicon micro mold of U.S. Pat. No. 7,124,994 (prior art);
[0020] Figure 6 is a cross-sectional view of a thin silicon micromold of the present invention, which is encapsulated and suspended by a thick, rigid and strong reinforcement structure;
[0021] Figure 7 and Figure 8 It is a cross-sectional view of the key processing steps of manufacturing the thin silicon mold and its reinforcement of the present invention, which adopts silicon wafer bonding technology;
[0022] Fig. 9 It is a cross-sectional view of the main processing steps of manufacturing the thin silicon micro-mold and its reinforcement of the present invention, which is carried out by double-sided etching of a single silicon wafer;
[0023] Fig.10 A cross-sectional view of the main processing steps for manufacturing a thin silicon micro-mold or micro-optical component and its reinforcement according to the present invention, by double-sided etching of a silicon-on-insulator (SOI) wafer;
[0024] Fig.11A cross-sectional view of the main processing steps for manufacturing a thin silicon micro mold and its reinforcement of the present invention, by connecting an independent thin silicon slice to a thick rigid frame (made of metal, ceramic, plastic, glass, silicon, etc.);
[0025] Fig.12 is a cross-sectional view of a thin silicon micromold of the present invention, which is connected to a receiving substrate by mechanical clamping;
[0026] Fig.13 is a cross-sectional view of two mold assemblies of the present invention;
[0027] Fig.14 For the present invention Figure 7 An example of a geometric pattern of cells in a medium that can be used as a micro-optical window or for further electroplating;
[0028] Fig.15 is a cross-sectional view of forming an array of electroplated micro-pillars on a receiving substrate by using a free-standing thin silicon micro-mold of the present invention;
[0029] Fig.16 A conceptual isometric view of a micro-pillar array structure formed on a receiving substrate by a free-standing thin silicon micro-mold of the present invention;
[0030] Fig.17 This is a microscope image of a micro-optical chip of the present invention, which is formed by patterning and through-etching a 20-micron-thick single-crystal silicon film to form a hexagonal micro-window array;
[0031] Fig.18 A cross-sectional view of a suspended thin silicon micro mold of the present invention in contact with a functional substrate having an electroplated seed metal layer;
[0032] Fig.19 A cross-sectional view of the suspended thin silicon micro mold in contact with a functional substrate after electroplating is completed according to the present invention;
[0033] Fig. 20 It is a cross-sectional view of the functional substrate after removing the suspended thin silicon micro-mold of the present invention, and the micro-pillar structure stands on the electroplating surface;
[0034] Fig.21 A cross-sectional view of a stack of thin silicon micro molds of the present invention, each mold having a pattern and reinforcement structure extending through the silicon wafer, which can be used to produce complex three-dimensional micro structures;
[0035] Fig. 22 is a cross-sectional view of an electroplating assembly of the present invention, the electroplating assembly comprising a receiving substrate with a seed metal coating and Fig.21 Multiple layers of thin silicon micro-molds, each layer having reinforcements for structural enhancement, and stacked together by clamping and / or connecting components;
[0036] Fig.23 For the present invention, by using Fig.23 A magnified cross-sectional view of a thin silicon micro-mold stack and microstructures generated by electroplating or other material filling techniques.
[0037] Reference numerals: silicon wafer 12, silicon wafer 14, silicon wafer 16, mold 10, micro mold 30, gold backing layer 34, wall surface 33, bottom surface 32, thin silicon micro mold 3000, patterned thin silicon layer 3100, reinforcement 3001, reinforcement 3005, unetched portion 3010, etched groove portion 3050, silicon wafer 201, silicon wafer 210, adhesive 211, micro mold layer 202, thin film layer 221, pattern 242, pattern 245, mold opening 240, micro structure 260, SOI substrate 261, SOI substrate first silicon layer 264, SOI substrate second silicon layer 262, silicon oxide layer 263, adhesive Composite layer 271, receiving substrate 400, component 500, component 510, component 520, gap 3011, solid material 3051, micro-pillar 3305, metal seed layer 3205, electroplated component 3200, pattern 612, pattern 622, pattern 632, reinforcement structure 615, reinforcement structure 625, reinforcement structure 635, thin silicon micro mold layer 610, thin silicon micro mold layer 620, thin silicon micro mold layer 630, electroplated component 660, connecting component 670, free space 613, free space 623, free space 633, element 652, element 654, element 656, element 657. DETAILED DESCRIPTION
[0038] In order to provide an overall understanding of the present invention, some illustrative embodiments and manufacturing methods will now be described, including a set of methods for manufacturing a thin silicon micromold with a rigid support reinforcement, a method for connecting the thin silicon micromold to a target receiving substrate, a method for stacking thin silicon micromolds, and a method for generating a microstructure on a receiving substrate using the assembly. It will be understood by those skilled in the art that the thin silicon micromold supported and suspended by a rigid reinforcement, a mold assembly consisting of multiple layers of thin silicon micromolds, a method for connecting the suspended thin silicon micromold or a stack thereof to a target substrate, and a method for generating a microstructure on a target substrate can be appropriately adjusted and modified according to the application involved, and the devices and methods described herein can also be used for other suitable applications, and any other additions and modifications do not depart from the scope of the present invention.
[0039] As described in the background art, silicon micro molds in the prior art are usually made using standard silicon wafers with a thickness of about 300 microns or more. Commercial silicon wafers with a thickness as low as 10 microns can be used to make silicon micro molds with a thickness as low as 10 microns, but due to the fragility of thin silicon wafers, it is difficult to perform photolithographic patterning and etching on them. For silicon wafers of conventional thickness, multiple silicon micro mold silicon wafers can be stacked, but if thin silicon wafers are used, the stacking operation will be very difficult because they lack sufficient rigidity and cannot provide good surface contact.
[0040] like Figure 1 As shown, it is a cross-sectional view of a layered silicon micro mold stack according to US Pat. No. 6,242,163B1, where silicon wafers 12, 14, and 16 are stacked to form a mold 10. Each silicon wafer is Figure 2 Part of the final 3D microstructure. Figure 2 As shown, silicon wafers 12, 14 and 16 correspond to three silicon layers, respectively. Although Stampfl ('163) used silicon wafers to make micro molds, the prior invention did not disclose a reinforcement integrated with the thin silicon micro mold to enhance its mechanical stability and keep its surface flat. If silicon wafers 12, 14 or 16 are thinned to 200 microns or thinner, the silicon wafer mold will begin to become fragile, and the thinner the silicon layer, the more fragile it is, and the more difficult it is to bond or stack together.
[0041] In addition, when the silicon mold is ultra-thin, the internal stress of the material (if any) may cause the thin wafer to warp and destroy the flatness of the silicon wafer, which is a necessary feature for the thin silicon wafer to function as a mold properly. This problem is particularly prominent when the silicon wafer is as thin as tens of microns to a few microns. Figure 3 As shown in the figure, the ultra-thin silicon wafer without a reinforcement member loses its flatness and its surface profile becomes curved. When the thickness of the silicon wafer or mold is reduced to less than 10 microns, its residual stress or other surface stress (for example, stress caused by the different surface roughness on both sides) may cause the silicon wafer to deform significantly. In some extreme cases, the silicon wafer can curl up to form a thin silicon wafer roll. Figure 3 In the case of a thin silicon wafer, the wafer is only 5 microns thick. However, if a rigid reinforcement structure is used to encapsulate the thin silicon wafer, the thin silicon wafer can be suspended with good flatness. Figure 4 As shown, according to the present invention, a thin silicon wafer with a diameter of 50 mm and a thickness of 5 μm is connected to a rigid silicon ring structure along its edge. Since the thin silicon wafer is stretched by the rigid frame, it no longer shows obvious silicon wafer bending, curling or deformation. Therefore, the reinforcement suspension method effectively maintains the flatness of the thin silicon wafer, making it suitable for manufacturing the thin silicon micro mold in the present invention.
[0042] refer to Figure 5, which is a cross-sectional view of the silicon micro mold disclosed in U.S. Patent No. 7,124,994. The micro mold 30 is made of industry-standard silicon wafers. After through-hole etching, the underlying gold backing layer 34 is exposed, leaving a plurality of etched channels on the silicon wafer substrate, which include a wall surface 33 and a bottom surface 32, the bottom surface being a part of the backing layer 34, to form a silicon micro mold 30. The method uses industry-standard silicon wafers that are typically thicker than 300 microns, which are strong enough to withstand physical and chemical treatments during micromachining. However, if industry-standard silicon wafers are not used, but thin and / or ultra-thin silicon wafers are used, the problems encountered by the silicon micro mold disclosed in U.S. Patent No. 6,242,163B1 arise. The method uses a conductive surface as a plating seed layer to generate a microstructure, which is deposited before etching the surface of the silicon wafer. The problem with this method is that the metal in the deposited metal layer may not be fully compatible with the deep reactive etching chemicals used for silicon micromachining. And because the metal seed layer is coated on the silicon micromold, electroplating can only generate microstructures on the seed layer and cannot be used in applications that require electroplating the microstructures directly onto other objects (such as a separate receiving substrate surface).
[0043] Therefore, the present invention provides a structurally enhanced thin silicon micro mold by combining the thin silicon micro mold with a thicker, rigid and stable reinforcement structure. By encapsulating and suspending the thin silicon layer in a rigid frame, the thin silicon micro mold can not only be quickly manufactured with high yield, but also has good flatness, and can be easily used and stacked, and single or multi-layer micro structures can be molded on a separate receiving substrate by connecting, plating and removing the micro mold.
[0044] like Figure 6 , which is a cross-sectional view of the thin silicon micro mold of the present invention, the thin silicon micro mold 3000 includes a patterned thin silicon layer 3100, connected with rigid reinforcements 3001 and 3005. Among them, reinforcement 3001 represents a structure connected around the edge of the thin silicon micro mold, and reinforcement 3005 represents a structure connected away from the edge area, either of which or a combination of the two can be used to ensure the stability and surface flatness of the thin silicon micro mold. The micro pattern on the thin silicon layer 3100 includes an unetched portion 3010 and an etched groove portion 3050. The entire thin silicon micro mold can be regarded as a patterned thin silicon wafer encapsulated and / or suspended by a thick, rigid and stable reinforcement structure.
[0045] Figure 7 and Figure 8 The fabrication of thin silicon micro-molds connected to rigid reinforcements by wafer bonding and thinning techniques is demonstrated. Fig. 9 A method for integrally manufacturing a thin silicon micromold with reinforcement members on a single silicon wafer is disclosed. Fig.10 A method for fabricating thin silicon micromolds with reinforcements by double-sided etching of silicon-on-insulator (SOI) wafers is demonstrated. Fig.11 We demonstrate a method for fabricating thin silicon micromolds with reinforcements by directly attaching independent thin silicon slices to a thick rigid frame (made of metal, ceramic, plastic, glass, silicon, etc.).
[0046] like Figure 7 and Figure 8 The cross-section view shows the key processing steps for fabricating a thin silicon micromold attached to a reinforcement using wafer bonding and thinning techniques, including:
[0047] S1, etching to a desired depth on one side of the silicon wafer 201 to form a groove 3050;
[0048] S2, bonding the etched silicon wafer 201 to another silicon wafer 210 through an adhesive 211;
[0049] S3, thinning the etched silicon wafer into a thin silicon micro mold layer 202;
[0050] S4, etching a mold opening 240 penetrating the silicon wafer on the silicon wafer 210, and the thin film layer 221 is used as an etching stop layer;
[0051] S5 , removing the adhesive material from the patterned grooves, and finally obtaining the thin silicon micro mold 3000 , including the etched thin silicon micro mold layer 202 connected with the rigid reinforcement 3005 .
[0052] Fig. 9 The main processing steps for manufacturing a thin silicon micromold 3000 with reinforcement by double-sided etching of a single silicon wafer are shown, including:
[0053] S1. Photolithography is performed on both sides of the industry standard silicon wafer 201 to generate a developed photoresist pattern 242 on one side and a photoresist pattern 245 on the other side. The silicon wafer is initially etched by deep reactive ion etching (DRIE) technology to obtain a mold opening 240 and a stiffener 3005, and the etching depth determines the thickness of the stiffener T_stiffener.
[0054] S2. Then, a second silicon etching is performed from the other side of the silicon wafer to obtain a micro-mold pattern of etched grooves 3050 that penetrate the silicon wafer and are separated by unetched parts 3010. This etching step determines the thickness T_mold of the thin silicon micro-mold. Usually, the thickness of a thin silicon micro-mold is in the range of 300 microns to 200 microns, the thickness of a very thin one is in the range of 200 microns to 50 microns, and the thickness of an ultra-thin one is in the range of 50 microns to 1 micron or thinner. Since this step performs the second etching on a suspended silicon layer, the thickness of the silicon layer should be greater than 10 microns, otherwise the layer will be too thin to withstand the deep reactive ion etching (DRIE) process. In order to manufacture an ultra-thin silicon micro-mold with a thickness of less than 10 microns, it is recommended to use the following method: Figure 7 and Figure 8 Wafer bonding and thinning techniques as described in .
[0055] Fig.10 A method for fabricating a thin silicon micro-mold, micro-window or other micro-optical component 260 using a silicon-on-insulator (SOI) substrate is shown, the method using a standard SOI substrate 261 comprising a first silicon layer 264 and a second thicker silicon layer 262 connected by an intermediate silicon oxide layer 263, comprising the following steps:
[0056] S1 . Apply standard photolithography process to both sides of the SOI substrate 261 in sequence, photolithograph and develop the pattern 242 on the first silicon layer 264 , and photolithograph and develop the pattern 245 on the second silicon layer 262 .
[0057] S2. Etch the silicon wafer by deep reactive ion etching to obtain the mold opening 240 and the stiffener 3005, wherein the oxide layer 263 is used as an etch stop layer. If necessary, an additional layer (not shown) can be applied on the other side of the silicon oxide layer to balance the stress of the silicon oxide layer. The etching depth is equal to the thickness of the second silicon layer, i.e., the thickness of the stiffener T_stiffener. Then, a second deep reactive ion etching is performed on the first silicon layer to obtain a micro mold pattern, which includes trenches 3050 that penetrate the silicon wafer separated by unetched portions 3010. In the case where the oxide layer 263 is used as an etch stop layer, the etching depth, i.e., the thickness of the first silicon layer, is used to determine the thickness T_mold of the thin silicon micro mold.
[0058] Fig.11 The main processing steps for manufacturing a thin silicon micro mold 3000 with a reinforced structure by connecting a thin silicon sheet to a thick and rigid frame (made of metal, ceramic, plastic, glass, silicon, etc.) are shown, including:
[0059] S1. Select a sufficiently thick thin silicon layer (e.g., 100 to 200 microns thick) for standard photolithography and deep reactive ion etching to form a micro-mold pattern that penetrates the silicon wafer, including a groove 3050 that penetrates the silicon wafer separated by an unetched portion 3010. This step does not require an etch stop layer, and the thickness of the thin silicon micro-mold is the same as the thickness of the silicon wafer. Since the thickness is greater than 100 microns, the silicon wafer can be processed by standard micromachining technology. The silicon wafer after deep reactive ion etching can withstand further operations, but care should be taken to avoid damaging it.
[0060] S2. Connect a hollow, thick and rigid reinforcement 3005 to the thin silicon edge to generate a thin silicon micro mold. The reinforcement 3005 can be made of a variety of materials, including silicon, ceramics, metals, glass, plastics, etc.
[0061] S3. Use a variety of adhesives, such as wax, epoxy resin, polymer, etc., as an adhesive layer 271 to connect two thick and rigid parts together, such as by mechanical clamping or tape. When using this method, the thickness of the thin silicon wafer should be greater than 100 microns, but a thicker silicon layer will adversely affect the aspect ratio of the mold pattern.
[0062] The above four manufacturing methods can all produce a thin silicon micro mold with a suitable reinforcement structure. According to the present invention, the thin silicon micro mold with a reinforcement structure has high mechanical strength and is convenient for microstructure molding. For example, in order to manufacture a microstructure on a receiving substrate, the micro mold can be conveniently connected to the substrate for electroplating. Fig.12 As shown, mechanical clamping is one of the most straightforward options, where a receiving substrate 400 is connected to a thin silicon micromold 3000 to form a stable assembly 500 for electroplating or filling with liquid or flexible materials. Fig.13 Two ways of assembling the micro mold assembly are shown, assembly 510 uses a more complex clamp assembly, while assembly 520 uses an adhesive to join the two parts. Ready for micro molding processes such as electroplating.
[0063] More specifically, Figure 6 and Figure 14-17 It is demonstrated how to produce microstructures using the micro-mold assembly of the present invention. Figure 6 In the embodiment, the suspended thin silicon micro mold 3000 has a plurality of reinforcements 3005 and 3001. The reinforcement 3001 indicates that the reinforcement structure can be arranged in the area outside the edge of the component, making the thin silicon micro mold more mechanically stable. The present technology is particularly suitable for the replication of unit devices, such as Fig.14 As shown, the patterned thin silicon layer 3100 can be a unit cell, wherein the unetched portion 3010 is a mechanically connected square pattern network, which can ensure that the unetched portion 3010 is still supported when released and suspended, and the etched portion 3050 is a groove that penetrates the silicon wafer. The unit cell 3100 is separated by a reinforcement 3001 to make it stable to ensure the electroplating yield. Fig.15 Demonstrated by using Fig.14 FIG. 4 is a cross-sectional view of an electroplated micro-pillar array formed on a receiving substrate 400 with a design pattern, wherein after electroplating, the unetched portion 3010 is reversed into a void 3011 , and the etched groove 3050 is reversed into a solid material 3051 . Fig.16 A conceptual isometric view of an array of micro-pillars 3305 formed on a receiving substrate 400 using the thin silicon micro-mold of the present invention is shown. Fig.17 A photo of a microwindow chip taken under a microscope is shown, which contains a hexagonal microwindow array that can be used as an optical window, filter or diffraction grating, with suspended thin silicon areas for further deposition of optical coatings. More specifically, in Fig.17In the embodiment, the thickness of the silicon layer is as thin as 20 microns, the diameter of the hexagonal window is less than 10 microns, and the width of the silicon layer sidewall is less than 4 microns.
[0064] More specifically, Figure 6 and Figure 18-20 An embodiment is shown in which a metal (e.g., Cu, Ni, Cr, Au, etc.) pillar array is electroplated onto a functional receiving substrate 400 using a thin silicon micro mold 3000. The functional receiving substrate 400 can be any smart material, including but not limited to piezoelectric materials, electrostrictive materials, electro-optical materials, thermoelectric materials, etc.
[0065] like Figure 6 As shown, the thin silicon micro mold 3000 has a double-layer silicon structure, wherein the thinner silicon layer is used to form the thin silicon mold layer, and the thicker silicon layer is used to form the reinforcement members 3005 and 3001 .
[0066] like Fig.18 As shown, the flat surfaces of the thin silicon micro mold 3000 and the functional receiving substrate 400 face each other and are in close contact to form an electroplated component 3200. If the functional receiving substrate 400 is not conductive, a metal seed layer 3205 is first coated before it contacts the thin silicon micro mold 3000. Mechanical clamping, tape, adhesive, and wafer bonding methods can be selected to connect the two objects, depending on how to efficiently join the electroplated component 3200.
[0067] like Fig.19 As shown, after the electroplating is completed, the suspended thin silicon micro mold 3000 is in contact with the functional receiving substrate 400, and the metal micro column 3305 array has been electroplated onto the functional receiving substrate 400.
[0068] like Fig. 20 As shown, the suspended thin silicon micro mold is removed, leaving an array of metal micro pillars 3305 on the electroplated surface. Since the reinforcement is also made of silicon in this electroplated embodiment, it can be removed together with the thin silicon micro mold by a one-step etching process. Etching to remove silicon is a mature technology, and KOH etching can usually be used.
[0069] Due to the stability of the thin silicon micro-molds connected to the reinforcement structure, multiple single-layer thin silicon micro-molds can be stacked together to generate micro-molded components that can be used to manufacture complex three-dimensional structures. Fig.21 As shown, different from the conventional silicon mold stacking method in US Pat. No. 6,242,163B1, each layer of thin silicon micro mold of the present invention has a built-in reinforcement during manufacturing, so each layer of stacked thin silicon micro mold has a built-in reinforcement structure. Fig. 22A cross-sectional view of a stack of three layers of thin silicon micro molds of the present invention is shown, each layer of thin silicon micro mold having a unique pattern 612, 622 and 632 that penetrates the silicon wafer, and respective reinforcement structures 615, 625, 635, and thin silicon micro mold layers 610, 620 and 630 are stacked together to produce a complex three-dimensional microstructure.
[0070] Fig. 22 is a cross-sectional view of an electroplating assembly 660 comprising a receiving substrate 400 (having a metal seed layer 3205) and stacked thin silicon micro-molds, each layer of micro-molds having structurally enhanced reinforcements and stacked together by mechanical clamping and / or connection assembly 670.
[0071] Fig.23 Demonstrated by using Fig.21 612, 622, and 632 become free space regions 613, 623, and 633, respectively, after etching away silicon. The resulting microstructures can have a variety of geometric and dimensional designs, such as shaped elements 652, 654, 656, and 657.
[0072] Although specific features of the present invention are shown in some drawings and not in others, this is for convenience only, as each feature may be combined with any or all other features according to the present invention. The words "comprises," "comprising," "having," and "and" as used herein should be interpreted broadly and comprehensively without limitation to any physical interconnection. Furthermore, any embodiment disclosed in this application should not be construed as the only possible implementation.
Claims
1. A thin silicon micro mold for molding microstructures or itself as a microstructure, It is characterized in that include: a thin silicon mold layer; a rigid reinforcement for supporting the thin silicon mold layer; The thin silicon mold layer has a thickness of less than 300 microns, is thin when the thickness ranges from 300 microns to 200 microns, is very thin when the thickness ranges from 200 microns to 50 microns, and is ultra-thin when the thickness ranges from 50 microns to 1 micron or less; The thin silicon mold layer has a top surface and a bottom surface that are substantially flat and parallel to each other, and at least one pattern is etched from the top surface to the bottom surface, and the pattern includes one or more etched grooves, tunnels, channels or other shapes; The rigid reinforcement encapsulates and suspends the thin silicon mold layer.
2. The thin silicon micro mold according to claim 1, Features: The reinforcement member is made of metal material; And / or, the reinforcement member is made of a composite material.
3. The thin silicon micro mold according to claim 1, It is characterized in that The reinforcing member is a silicon reinforcing member, and: the silicon reinforcing member and the thin silicon mold layer are integrally made of a single silicon substrate; Or the silicon reinforcement is made of one silicon layer of a silicon-on-insulator (SOI) substrate, and the thin silicon mold layer is made of another silicon layer of the SOI substrate; or the silicon reinforcement is made of an industry-standard silicon substrate.
4. The thin silicon micro mold according to claim 1, Features: The reinforcing member includes a portion connected to the thin silicon mold layer and at least one portion not in contact with the thin silicon mold layer; The reinforcing member is connected to the thin silicon mold layer along its edge; the reinforcing member is connected to the thin silicon mold layer at a position deviating from the edge of the thin silicon mold layer.
5. A method for manufacturing a thin silicon micro mold, It is characterized in that The following steps are involved: S1, providing a thin silicon mold layer, the thickness of which is less than 300 microns; S2, provide a thick reinforcement base plate, which is rigid and mechanically stable; S3, patterning the thin silicon mold layer to obtain grooves, channels, tunnels, openings, vias or shapes; S4, patterning the reinforcement to obtain grooves, channels, tunnels, openings, vias or shapes; S5. Forming the thin silicon mold layer on the thick reinforcement member.
6. The method for manufacturing a thin silicon micro mold according to claim 5, wherein S1 and S2 use the same silicon substrate, Features: The same silicon substrate is first patterned from one side to form grooves and shapes with a depth equal to the target thickness of the thick reinforcement, and then patterned from the other side to form grooves and shapes with a depth equal to the thickness of the thin silicon mold layer.
7. The method for manufacturing a thin silicon micro mold according to claim 5, wherein S1 and S2 use the same silicon-on-insulator (SOI) substrate, Features: The same silicon-on-insulator (SOI) substrate is patterned using its buried oxide layer as an etch stop layer to form grooves and shapes with a depth of the target thickness of the thick reinforcement on its first silicon layer, and to form grooves and shapes with a depth of the thickness of the thin silicon mold layer on its second silicon layer; the buried oxide layer is then removed.
8. The method for manufacturing a thin silicon micro mold according to claim 5, wherein S1 and S2 use two independent substrates respectively, Features: The thin silicon mold layer is a silicon substrate; the thick reinforcement substrate is a silicon or non-silicon substrate; The first of the two separate silicon substrates is patterned from one side thereof to form grooves and shapes having a thickness no less than a target thickness of the thin silicon mold layer, and the second silicon substrate has a thickness equal to a target thickness of the thick reinforcement; The step of forming the thin silicon mold layer on the thick reinforcement includes: a bonding step of facing and bonding the patterned surface of the first silicon substrate to one side of the second silicon substrate, a grinding step of grinding from the unpatterned side of the first silicon substrate to expose the grooves and shapes, a patterning step of patterning the second silicon substrate to form the grooves and shapes penetrating the silicon wafer with a depth equal to the thickness of the thick reinforcement, and a subsequent step of removing the adhesive.
9. A method for manufacturing a microstructure, It is characterized in that The following steps are involved: S1. providing a thin silicon micro mold, which includes a thin silicon mold layer connected to a thick reinforcement member; S2, providing a receiving substrate; S3, forming at least one of the thin silicon micro molds on the receiving substrate; S4, filling the thin silicon micro mold with component material; S5. Demolding the silicon mold.
10. A method for manufacturing a microstructure according to claim 9, Features: The material of the receiving substrate is conductive or non-conductive; The receiving substrate includes a conductive support surface; The component material includes metal, liquid material or flexible material; Methods of filling the thin silicon micromold include electroplating.
11. A method for manufacturing a microstructure according to claim 9, It is characterized in that in, Step S3 includes the following method: mechanically clamping the thin silicon micro-mold to the receiving substrate; and / or, adhering the thin silicon micro mold and the receiving substrate together with adhesive tape; and / or, bonding the thin silicon micro-mold to the receiving substrate; and / or, adhering the thin silicon micromold to the receiving substrate.
12. A method for manufacturing a microstructure having a complex three-dimensional structure, It is characterized in that The following steps are involved: S1, stacking a plurality of thin silicon micro molds with built-in reinforcement members, fixing each layer by a connecting component, to form a thin silicon micro mold assembly; S2, providing a receiving substrate; S3, forming at least one of the thin silicon micro-mold components on the receiving substrate; S4, filling the thin silicon micro-mold assembly with component materials; S5. Demolding the silicon mold assembly.