GB2448881A - Polyimide thin film self-assembly - Google Patents

Polyimide thin film self-assembly Download PDF

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Publication number
GB2448881A
GB2448881A GB0708349A GB0708349A GB2448881A GB 2448881 A GB2448881 A GB 2448881A GB 0708349 A GB0708349 A GB 0708349A GB 0708349 A GB0708349 A GB 0708349A GB 2448881 A GB2448881 A GB 2448881A
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Prior art keywords
thin film
polyimide thin
self
micro
assembly process
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GB0708349D0 (en
Inventor
Alex Horng
I-Yu Huang
Chih-Hung Wang
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Sunonwealth Electric Machine Industry Co Ltd
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Sunonwealth Electric Machine Industry Co Ltd
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Priority to GB0708349A priority Critical patent/GB2448881A/en
Publication of GB0708349D0 publication Critical patent/GB0708349D0/en
Publication of GB2448881A publication Critical patent/GB2448881A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/10—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a discontinuous layer, i.e. formed of separate pieces of material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
    • B81C1/00007—Assembling automatically hinged components, i.e. self-assembly processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
    • B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
    • B81C1/00134—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems comprising flexible or deformable structures
    • B81C1/0019—Flexible or deformable structures not provided for in groups B81C1/00142 - B81C1/00182
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
    • B81C1/00436—Shaping materials, i.e. techniques for structuring the substrate or the layers on the substrate
    • B81C1/00444—Surface micromachining, i.e. structuring layers on the substrate
    • B81C1/00468—Releasing structures
    • B81C1/00476—Releasing structures removing a sacrificial layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
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    • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
    • B81C1/00436—Shaping materials, i.e. techniques for structuring the substrate or the layers on the substrate
    • B81C1/00523—Etching material
    • B81C1/00531—Dry etching
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
    • B81C1/00436—Shaping materials, i.e. techniques for structuring the substrate or the layers on the substrate
    • B81C1/00523—Etching material
    • B81C1/00539—Wet etching
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/0029—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/004—Details
    • H01G9/04—Electrodes or formation of dielectric layers thereon
    • H01G9/048—Electrodes or formation of dielectric layers thereon characterised by their structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
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    • H01G9/20—Light-sensitive devices
    • H01G9/2045—Light-sensitive devices comprising a semiconductor electrode comprising elements of the fourth group of the Periodic System (C, Si, Ge, Sn, Pb) with or without impurities, e.g. doping materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/20—Light-sensitive devices
    • H01G9/2095—Light-sensitive devices comprising a flexible sustrate
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/21—Temperature-sensitive devices
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    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/30—Properties of the layers or laminate having particular thermal properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/51—Elastic
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    • B32B2310/04—Treatment by energy or chemical effects using liquids, gas or steam
    • B32B2310/0409—Treatment by energy or chemical effects using liquids, gas or steam using liquids
    • B32B2310/0418—Treatment by energy or chemical effects using liquids, gas or steam using liquids other than water
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
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    • B32B2310/14—Corona, ionisation, electrical discharge, plasma treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2315/00—Other materials containing non-metallic inorganic compounds not provided for in groups B32B2311/00 - B32B2313/04
    • B32B2315/08—Glass
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2386/00—Specific polymers obtained by polycondensation or polyaddition not provided for in a single one of index codes B32B2363/00 - B32B2383/00
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2457/00—Electrical equipment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2551/00—Optical elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2603/00—Vanes, blades, propellers, rotors with blades
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B2201/00—Specific applications of microelectromechanical systems
    • B81B2201/01—Switches
    • B81B2201/012—Switches characterised by the shape
    • B81B2201/014—Switches characterised by the shape having a cantilever fixed on one side connected to one or more dimples
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B2201/00—Specific applications of microelectromechanical systems
    • B81B2201/03—Microengines and actuators
    • B81B2201/032—Bimorph and unimorph actuators, e.g. piezo and thermo
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B2201/00—Specific applications of microelectromechanical systems
    • B81B2201/03—Microengines and actuators
    • B81B2201/038—Microengines and actuators not provided for in B81B2201/031 - B81B2201/037
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
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    • B81B2201/04—Optical MEMS
    • B81B2201/045—Optical switches
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C2201/00—Manufacture or treatment of microstructural devices or systems
    • B81C2201/01—Manufacture or treatment of microstructural devices or systems in or on a substrate
    • B81C2201/0101—Shaping material; Structuring the bulk substrate or layers on the substrate; Film patterning
    • B81C2201/0128—Processes for removing material
    • B81C2201/013—Etching
    • B81C2201/0132—Dry etching, i.e. plasma etching, barrel etching, reactive ion etching [RIE], sputter etching or ion milling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C2201/00—Manufacture or treatment of microstructural devices or systems
    • B81C2201/01—Manufacture or treatment of microstructural devices or systems in or on a substrate
    • B81C2201/0101—Shaping material; Structuring the bulk substrate or layers on the substrate; Film patterning
    • B81C2201/0128—Processes for removing material
    • B81C2201/013—Etching
    • B81C2201/0133—Wet etching
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C2201/00—Manufacture or treatment of microstructural devices or systems
    • B81C2201/01—Manufacture or treatment of microstructural devices or systems in or on a substrate
    • B81C2201/0174—Manufacture or treatment of microstructural devices or systems in or on a substrate for making multi-layered devices, film deposition or growing
    • B81C2201/0176—Chemical vapour Deposition
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/542—Dye sensitized solar cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
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  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Micromachines (AREA)

Abstract

A component is produced by: (1) depositing a sacrificial layer 20 and a microstructure layer 30 on a silicon substrate 10; (2) etching the microstructure layer 30; (3) coating the microstructure layer 30 with a photosensitive polyimide thin film 40; etching the polyimide film 40 to produce an elastic joint 41; (5) wet etching the sacrificial layer 20; and then (6) heating the joint 41 to lift the microstructure layer 30. Preferably the elastic joint 41 is defined using photolithography. Preferably the microstructure 30 and sacrificial 20 layers comprise chemical vapour deposited (CVD) polycrystalline silicon 30 and phosphosilicate glass 20. The method produces miniature devices including micro-fans, scratch drive actuators, micro-optical bench chips, micro-optical switches, micro-inductors and micro-capacitors.

Description

A POLYIMTDE THIN FILM SELF-ASSEMBLY PROCESS
100011 The invention presents a polyimide thin film self-assembly process, which utilizes an integrated miniaturized planar technology with s simple, fast and economical characteristics.
100021 The development and application of miniaturization technology is a major trend of modern science, and self-assembly technology, in particular, it is a rudimentary method of the microscopic world in recent years.
3] Referring to a micro rotary fan manufactured by microelectromechanical systems (MEMS) technology, as shown in Figure 1, a portion between the Scratch Drive Actuator (SDA) of the micro rotary fan and the micro blades structure must be implemented by a self-assembly technology and multi-user MEMS processes (MUMPs).
100041 The so-called self-assembly technology means that the microstructure will self-align after the completion of the final release process.
As shown in Figures 2 to 4, conventional self-assembly technology has the following three tyies.
I 0005J Type 1 uses residual stress from the manufacturing process to generate the deformation resulting in the displacement of microstructure as shown in Figure 2, which illustrates a 3D micro-optic switch developed by Lucent Technology.
6] Type 2 uses surface acoustic wave generated by ultrasonic wave to move the microstructure to a preset position by vibration as shown, in Figure 3.
7] Type 3 uses a solder ball, photoresist or other polymer to form an elastic joint on a micro-hinge. A molten state of the elastic joint will be present under high temperature reflow process so as to generate a surface tension force pulling up the microstructure as shown in Figure 4.
100081 However, type 1 and type 2 of the traditional self-assembly technologies are only applicable to static application or a fixed microstructure, but not suitable for dynamic or rotating microstructure such as the micro-fan application.
[0009J In regard to type 3 self-assembly tecknology, there are a host of materials suitable for elastic joint fabrication. Different materials feature respective disadvantages. Take the solder ball as an example: [00101 Lead contamination: the solder ball is composed of tin and lead (63SnI37Pb). During the reflow process, facilities and environment will be contaminated by lead.
[0011J High cost: most of the surface micromachined microstructures are usually constructed by polycrystalline silicon (Poly-Si), where a layer of gold pad must be coated as an interconnection between the solder ball and Poly-Si. This additional process will inevitably result in production difficulty and increased cost.
100121 Poor precision: to calculate the raised angle or displacement of microstructure, the dimension of solder ball must be accurately controlled.
However, traditional solder ball usually has a volume deviation up to 25%, which makes the precision of the raised angle or displacement uncontrollable.
[0013J Manual processing: so far, attaching the solder ball on the gold pad still uses manual alignment processing.
100141 Miniaturizing infeasibility: currently, the smallest diameter of solder ball is no less than 100 jim, which limits the minimum size of the solder-based devices.
5] Taking the elastic joint formed by photoresist as another
example:
10016] The manufacturing process of the elastic joint formed by photoresist is not as complicated as that of the solder ball, and the cost thereof is also lower. However, the release of the microstructure must be processed by dry or wet etching.
[0017J The dry etching utilizes liquid carbon dioxide to release the microstructure and replace the water molecule so as to avoid the stick effect of the microstructure. However, the super critical CO2 dry release equipment used for the method is quite expensive, and thus the cost of this process is relatively high.
100181 The wet etching requires no additional manufacturing equipment, making it a solution with less cost. However, after etching the sacrificial layer with the solution of diluted hydrofluoric acid (HF) or buffered oxide etch (BOE) further apply the isopropyl alcohol (IPA) to quickly vaporize the water molecules. The IPA is characterized by dissolving the photoresist so that it will damage the photoresist-based elastic joint fabricated originally.
[0019j In sum, considering production cost, process integration and miniaturization capability, a new manufacturing process is urgently required to resolve various shortcomings arising from the elastic joint formed by the solder ball or the photoresist.
[0020J In view of this, the invention provides a polyimide-based thin film self-assembly technology, including five process steps described as follows: (I) depositing a sacrificial layer and a low-stress microstructure layer on a silicon substrate; (2) patterning and etching the low-stress microstructure layer to provide a stationary part and a movable part of the microstructure; (3) coating a photosensitive polyimide thin film as elastic joint of the microstructure layer and defining its shape using a photolithography technique; (4) releasing the sacrificial layer beneath the movable part of microstructure layer by wet etching; (5) lastly reflowing polyimide to result in the contraction of the elastic joint further to rotate and lift the movable part in completion of the self-assembly of the microstructure.
As the invention can be extensively applied to a myriad of miniaturizing industries, it carl at least mitigate the drawbacks of the prior art and satisfy the requirements of low cost, simple manufacturing process and miniaturization.
1] The invention will now be described, by way of example, with reference to the accompanying drawings in which: 100221 Figure 1 is a micrograph of a known micro rotary fan manufactured by microel ectrornechanical systems (M1EMS) technology; [0023] Figure 2 is a rnicrograph of a known 3D micro-optic switch developed by Lucent Technology; [0024] Figure 3 is schematic diagram of cross-sections of a known microstructure using surface acoustic wave generated by ultrasonic wave to move the microstructure to a preset position by vibration; 100251 Figure 4 is a micrograph of using a solder ball, photoresist or other polymer to form an elastic joint on a known micro-hinge [0026] Figure 5 is a micrograph of a photolithography process to define the shape of a polyirnide elastic joint according to the present invention;
] Figure 6 is a micrograph of a reflow process of the present invention; [0028] Figure 7 is a schematic diagram showing the manufacturing processes of the present invention; and 100291 Figure 8 is a diagram showing the relationship between the reflow temperature of polyimide and raised angle of the microstructure layer of the present invention.
0] The invention relates to a polyimide thin film self-assembly process, which utilizes a photosensitive polyimide thin film as material for an elastic joint. During a reflow process, a molten state of the polyimide-based elastic joint is demonstrated under high temperature (380 C 405 C) and a surface tension force is generated to pull up the mi crostructure.
(0031] As shown in Figure 7, the manufacturing processes of the present invention include: 100321 process I: depositing an phosphosilicate glass (PSG) on a silicon substrate 10 as a sacrificial layer 20 by means of a Plasma Enhanced Chemical Vapor Deposition (PECVD) system and further depositing low-stress Poly-Si on the sacrificial layer 20 as the microstructure layer 30 by means of a Low Pressure Chemical Vapor Deposition (LPC\TD) system; [0033J process 2: carrying out a first photolithography process and etching a microstructure layer 30 to define an entire contour by using an Inductively Coupled Plasma (ICP) etching system; [0034] process 3: using a spin coater to deposit a photosensitive polyimide thin film 40 on the microstructure layer 30; (0035] process 4: carrying out a second photolithography process to define a shape of the polyimide elastic joint 41, as shown in Figure 5; 100361 process 5: immersing the wafer in the BOE to carry out a wet etching of the pre-defined portion of the sacrificial layer 20 to release the microstructure layer; and [0037] process 6: carrying out a reflow process of polyimide thin film by using a high temperature oven, resulting in a molten state of the elastic joint 41 at high temperatures of 3 80 C 405 C. The heated polyimide elastic joint 41 generates a contracted deformation to rotate and lift the pre-defined portion of the Poly-Si microstructure layer 30 as shown in Figure 6.
8] First of all, compare the pros and cons of the polyimide elastic joint formed by the present invention and the solder ball respectively.
(0039] The present invention has no lead pollution.
[00401 The present invention requires no additional gold pad coated for the connection interface so as to address a simple and inexpensive manufacturing process.
1] The invention can conduct the alignment with rather high precision by virtue of the photolithography technique so as to provide a better precision.
100421 The invention can perform an integrated miniaturized planar self-assembly processing.
3] The miniaturized size of the present invention has no limitation.
[00441 Furthermore, compare the pros and cons of the polyimide elastic joint formed by the present invention and photoresist.
5] Although photosensitive polyimide and photoresist are categorized as polymer materials, polyimide has a greater surface tension force which raised a larger angle of the same microstructure layer.
Consequently, the present invention is free of the concern that the elastic joint is damaged by being dissolved in IPA.
6] As the photosensitive polyimide thin film is better in is withstanding the organic solution, it can be developed to an inexpensive wet etching process. Therefore, the fabrication cost of the invention is relatively low.
7] In summary, the invention can simplify the manufacturing process, lower the cost and completely solve the shortcomings arising from the elastic joint formed by the solder ball or photoresist.
100481 Moreover, as shown in Figure 8, time and temperature will directly affect the raised angle of the pre-defined raised portion of the Poly-Si microstructure layer 30. As a result, by controlling the time and reflow temperature of the polyimide, the raised angle of the pre-defined raised portion of the microstructure layer 30 can be accurately controlled.
9] The actual results based on an experiment with the photosensitive polyimide thin film with a thickness 20 xm are shown as follows.
[0050J The patterned microstructure layer 30 cannot be lifted up when the temperature of the reflow process is below 330 C; 100511 The raised phenomenon will gradually appear when the reflow temperature of polyimide reaches 380 C and more; [0052] Tn accordance with the experimental results, the raised angle at 405 C reflow temperature is larger than at 380 C, but the yield at 405 C is only half of that at 380 C or even less. This is due to the fact that the photosensitive polyimide thin film will excessively contract at 405 C (or higher) causing the width of polyimide smaller than the gap between the movable part and the stationary part of Poly-Si microstructure layer 30, causing malfunction of the polyimide elastic joint 41.
[0053J In our experience, the optimized reflow temperature of the polyimide-based elastic joint is 380 C.
[0054J By means of the above fabrication processes, the present invention at least mitigates the myriad of shortcomings arising from the solder ball or photoresist elastic joint and can be extensively applied to the self-assembly technology in various miniaturizing industry. Accordingly, the present invention is not only new and inventive but also has industry utility.

Claims (12)

1. A polyimide thin film self-assembly process, comprising steps of: a. depositing a sacrificial layer on a silicon substrate and depositing a low stress microstructure layer on the said sacrificial layer; b. patterning and etching a microstructure form on the said sacrificial layer; c. coating a polyimide thin film on the said microstructure layer; d. patterning and etching an elastic joint form on the said polyimide thin film; e. carrying out a wet etching process to etch and release a pre-defined portion of the said sacrificial layer; and f. carrying out a reflow process to result in a contraction of the said elastic joint to rotate and lift a pre-defined portion of the said microstructure layer.
2. The polyimide thin film self-assembly process of claim 1, wherein the said low-stress sacrificial layer is a phosphosilicate glass (PSG).
3. The polyimide thin film self-assembly process of claim 1, wherein the said microstructure layer is polycrystalline silicon (Poly-Si).
4. The polyimide thin film self-assembly process of claim 1 applied to a self-assembly of a micro rotary fan.
5. The polyimide thin film self-assembly process of claim I applied to a self-assembly of a scratch drive actuator.
6. The polyimide thin film self-assembly process of claim I applied to a self-assembly of a micro-optical bench chip.
7. The polyimide thin film self-assembly process of claim 1 applied to a self-assembly of a micro-optical switch.
8. The polyimide thin film self-assembly process of claim I applied to a self-assembly of a micro-passive device.
9. The polyimide thin film self-assembly process of claim 8, wherein the said micro-passive device is a micro-inductor.
10. The polyimide thin film self-assembly process of claim 8, wherein the said micro-passive device is a micro-capacitor.
11. A polyimide thin film self-assembly process substantially as described herein with reference to and as shown in any of Figures 5 to 10 of the accompanying drawings.
Amended claims have been filed as follows.
1. A polyimide thin film self-assembly process, comprising: a. providing a support substrate; b. depositing a PECVD phosphosilicate glass (PSG) sacrificial layer on top of said support substrate; c. depositing an undoped LPCVD polysilicon microstructure layer on top of said PECVD PSG sacrificial layer; d. coating a high surface tension force polyimide thin film on top of said low stress LPCVD polysilicon microstructure layer; e patterning and etching an elastic joint form on said high surface tension force polyimide thin film; f. carrying out a wet etching process to etch and release a pre-defined portion of said PECVD PSG sacrificial layer; and g. carrying out a reflow process to result in a contracted deformation of said high surface tension force polymide elastic joint to rotate and lift a pre-defined portion of said low stress LPCVD polysilicon microstructure layer.
* 2. The polyimide thin film self-assembly process of claim I applied to a self-assembly of a micro rotary fan. ****
3. The polyimide thin film self-assembly process of claim I applied to a self-assembly of a scratch drive actuator.
4. The polyimide thin film self-assembly process of claim I applied to a self-assembly of a micro-optical bench chip.
5. The polyimide thin film self-assembly process of claim I applied to a self-assembly of a micro-optical switch.
6. The polyimide thin film self-assembly process of claim I applied to a self-assembly of a micro-passive device.
7. The polyimide thin film self-assembly process of claim 8, wherein the said micro-passive device is a micro-inductor.
8. The polyimide thin film self-assembly process of claim 8, wherein the said micro-passive device is a micro-capacitor.
9. The polyimide thin film self-assembly process of claim I, wherein said high surface tension force polyimide thin film is 20 im thick.
10. The polyimide thin film self-assembly process of claim I or 9, wherein the reflow process of said high surface tension force polyimide thin film is carried out in a nitrogen filled oven and cured at 380 to 405 degrees Celsius.
11. The polyirnide thin film self-assembly process of claim 10, wherein the reflow process of said high surface tension force polyimide thin film is carried out at 380 degrees Celsius.
12. A polyimide thin film self-assembly process substantially as described herein with reference to and as shown in any of Figures 5 to 10 of the accompanying drawings. * ** * S * * ** **5* * * **.. S. ** * S * * *
S *.u *
S S*.. *S S * . * S *
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105036055A (en) * 2015-06-09 2015-11-11 陈曦 Shape-controllable three dimensional self-assembled micro-mechanical structure

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070039919A1 (en) * 2005-08-17 2007-02-22 Sunonwealth Electric Machine Industry Co., Ltd. Polymide thin film self-assembly process
US20070040229A1 (en) * 2005-08-17 2007-02-22 Sunonwealth Electric Machine Industry Co., Ltd. Self-assembly microstructure with polymide thin-film elastic joint

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070039919A1 (en) * 2005-08-17 2007-02-22 Sunonwealth Electric Machine Industry Co., Ltd. Polymide thin film self-assembly process
US20070040229A1 (en) * 2005-08-17 2007-02-22 Sunonwealth Electric Machine Industry Co., Ltd. Self-assembly microstructure with polymide thin-film elastic joint

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105036055A (en) * 2015-06-09 2015-11-11 陈曦 Shape-controllable three dimensional self-assembled micro-mechanical structure

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