以UV-LIGA技術製作平面波導光干涉式感測器之研究

Abstract

本論文主要目的為建立UV-LIGA相關高解析度光刻與微加工技術，配合光學模擬，設計製作平面光波導光干涉式感測器(Mach-Zehnder Interferometer，MZI)，並架設光學量測平台用以驗證此感測器之幾何與材料參數之可行性。根據此微加工技術能量，未來 可利用模造製程量產塑膠MZI生物晶片。 進行高解析度光刻時，我們遇到無法解析1μm線寬的問題。本研究除了提出光的繞射效應說明其中可能的機制外，也利用濾鏡濾波方式，留下穿透度高的波段進行曝光，減少光阻的最大繞射誤差。本研究利用田口方法找出最佳化製程參數，成功製作出解析度1μm，深寬比6的Y-branch tip微結構，光波導微溝槽也能符合6μm × 6μm ± 0.5μm的設計值。 在MZI感測性質方面，係利用不同濃度的氯化鈉水溶液進行感測，初步證實MZI感測器可偵測到濃度10-6 g/L的溶液。最後利用上述MZI結構進行電鑄模造製程，在塑膠上複製出MZI結構。

The aim of this paper is to develop a UV-LIGA technique which includes high-resolution UV photolithography and microfabrication to fabricate planar waveguide Mach-Zehnder interferometric sensor (MZI) which designed by optical simulation method. The study also set up an optical bench to verify the geometric and material parameters of the sensor. Combing the microfabrication technique, electroforming, and molding process, it’s possible to fabricate polymer MZI biochips in the future. During the high-resolution photolithography process, the resolution of 1μm tip structure can not be achieved. This study presents an explanation to explain the mechanism of the problem based on diffraction effect. A solution to filtrate the UV light source with filter is suggested, and using the remaining high-penetration light to photolithograph to come to decreasing the maximum diffraction error. After further optimizing the process parameters by Taguchi method, a Y-branch tip structure can be successfully fabricated. This process had 1μm resolution and the aspect ratio was 6, and the cross section of waveguide trench can fulfill the design value of 6μm × 6μm ± 0.5μm. Several sodium chloride water solution of different concentrations were used to test the sensitivity of the MZI sensor. Preliminary result proved that the sensor can detect 10-6 g/L water solution. Finally, the study presented that the polymer MZI structure can be duplicated successfully by electroforming and molding process.