微轉印技術之開發與應用

Development and application of micro transfer stamping technique

詹秉達(Bin-Da Chan)

指導教授 ： 楊申語

國立臺灣大學/工學院/機械工程學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.01141

摘要

本論文以開發微轉印技術為主軸，研究快速簡單的製程技術製作微結構。此製程主要特色有五：1.製程單純；2.所製作的微結構無殘留層，不須額外去除殘留層步驟，有效降低製程複雜性，並提高可應用材料之多樣性；3.可製作多層微結構；4.製程相容性高，只要是可溶液製程(solution-processable)之材料皆可進行轉印；5.無須額外化學方法即可進行轉印。
本論文主要研究內容包括：金屬黃光顯影蝕刻製程之開發、ITO薄膜蝕刻製程之開發、PDMS模具於轉印製程之應力分析與模擬、單層與雙層微轉印製程之開發以及微轉印製程之應用等部分。
在「金屬黃光顯影蝕刻製程開發方面」，本研究藉著氯化鐵蝕刻液對銅與不鏽鋼進行蝕刻，並建立製程參數。在「ITO薄膜蝕刻」之研究方面，研究結果顯示四個製程因子會對ITO蝕刻結果產生很大的影響，並提出搭配適當的光阻塗佈厚度與曝後烤，可以有效降低ITO薄膜蝕刻後尺寸改變的問題。在「PDMS模具轉印之應力分析」部分，模擬結果顯示垂直方向壓力會致使PDMS模具微結構間間隙產生垂直方向的位移，可能導致轉印殘留層的產生。模擬結果更提出藉著改變PDMS模具厚度可以有效降低間隙垂直位移量，防止殘留層產生。在「單層與雙層轉印製程之開發」方面，本論文證實藉著溫度與壓力適當的調配，光阻墨水可完整轉印至壓克力基材上，且無殘留層產生。搭配自製的對位系統，更可以轉印出雙層微結構，包含堆疊的圓點結構與交錯的光柵結構。同時也對濕式、乾式轉印進行製程探討，以增加製程適用之範圍。在「微轉印製程之應用」方面，本研究驗證轉印製程可直接轉印光阻於銅片上，做為蝕刻擋罩，而不需經過黃光微影製程。另外本研究也轉印參雜過的導電高分子材料，以印證使用轉印技術具有製作有機薄膜電晶體(field-effect transistor, TFT)的能力。

關鍵字

轉印 ； 奈米壓印 ； 多層結構 ； 有機薄膜電晶體 ； 銀膠

並列摘要

The thesis develops a micro transfer stamping technique to fabricate microstructures. There are five advantages of the micro transfer stamping technique： 1. This is a simple process; 2. There is no residual layer, therefore no additional process is needed to remove the residual layer; 3. The process can fabricate muti-layer structure; 4. The process is theoretically suitable for all solution-processable materials; 5. No additional chemical process is needed in the process.
There are five research topics in the thesis, includes development of lithography and etching process for metal materials, development of ITO etching process, stress and strain simulation of PDMS mold in the transfer stamping process, development of single-/ muti- layer transfer stamping process and application of the micro transfer stamping process.
In the “development of lithography and etching process for metal materials” section, FeCl3 is used to etch metals including cooper and stainless steel, and the suitable process parameters are identified. In the “development of ITO etching process” section, optimization of four process factors of the ITO etching quality is carried out. In the section, we propose that with proper PR coating thickness and post expose baking time, the desired dimensions of ITO pattern can be reached. In the “stress and strain simulation of PDMS mold in the transfer stamping process” section, the simulation results show that the “gap” between microstructures of PDMS mold sags as the applied pressure is high enough or the gap length is large. A large sagging distance would lead to residual layer appearance in the transfer stamping process. It is found that increasing PDMS mold thickness can prevent residual layer forming. In the “development of single/ multi-layer transfer stamping process” section, the micro transfer stamping technique can effectively transfer the patterns of the mold onto substrate. With proper pressure and temperature, the PR “ink” can successfully be transferred on the PMMA substrate with no residual layer. The section also proves that the micro transfer stamping technique can transfer dual-layer patterns, including spot stacks and woven patterns. In the “application of the micro transfer stamping process” section, we show the application of micro transfer stamping technique. The single-layer transferred PR patterns can replace lithography process, to be directly used as the etching mask in the metal-etching process. We also prove that the micro-transfer stamping can transfer various materials, including doped conductive polymer, PEDOT:PSS and silver paste. This implies that the process has the potential to fabricate muti-layer organic field effect transistor (TFT).

並列關鍵字

stamping ； printing ； NIL ； muti-layer ； OTFT ； silver paste

參考文獻

[1]張致遠, “創新型微奈米軟模轉印技術之研發與應用”, 國立台灣大學 博士論文 (2006)

[2]Xiao-Mei Zhao, Younan Xia, and George M. Whitesides, “Fabrication of Three-Dimensional Micro-Structures: Microtransfer Molding”, Adv. Mater. 8 (1996) 837-840

[4]Amit Kumar and George M. Whitesides, “Features of gold having micrometer to centimeter dimensions can be formed through a combination of stamping with an elastomeric stamp and an alkanethiol “ink” followed by chemical etching”, Appl. Phys. Lett. 63 (1993) 2002

[5]Yueh-Lin Loo, Robert L. Willett, Kirk W. Baldwin, and John A. Rogers, “Interfacial Chemistries for Nanoscale Transfer Printing”, J. AM. CHEM. SOC. 124 (2002) 7654-7655

[6]Yueh-Lin Loo, Robert L. Willett, Kirk W. Baldwin and John A. Rogers, “Additive, nanoscale patterning of metal films with a stamp and a surface chemistry mediated transfer process: Application in plastic electronics”, Appl. Phys. Lett. 81 (2002) 562