以I-line相位移光罩微影成像技術作次微米T型閘的研究

Abstract

利用I-line步進機加上相位移光罩(Phase Shift Mask)去達成次微米寬度T型閘,對製造砷化鎵微波元件來說是非常有吸引力的,因為投資成本低及且有高的產能◦這篇論文將提述如何使用相位移光罩去形小於0.2μm的T型閘以供砷化鎵微波元件製作之應用◦ 8%半透光型的相位移光罩被選用在此實驗,並定義出獨立且狹窄的溝狀圖案◦ 此實驗在做微影之前,先把2000Å的氮化矽沉積在矽晶片上◦之後利用相位移光罩去定義圖案,並隨之以RIE方式蝕刻氮化矽◦由於相位移光罩的關係,可以得到小於0.25μm的蝕刻圖案◦隨後再沉積600Å 及900Å的氮化矽,之後在無任何罩幕下蝕刻回去,如此即可形成小於0.2μm的蝕刻圖案◦第二層光阻經過曝光顯影後,便可有T型結構◦把金屬蒸鍍上去再去光阻,小於0.2μm之T型閘即可形成◦在本研究中,0.12μm之T型閘即以此方式完成◦ 此種製程較傳統電子束微影成像技術, 具有高產能,低成本的良好特性◦可供砷化鎵微波元件大量製造微影技術使用◦

Submicron T-gate formation with I-line using phase shift mask (PSM) technique has become very attractive due to its low capital investment and high throughput for GaAs MMIC technology. In this thesis a novel submicron less 0.2μm T-gate technology using phase shift mask technique is report. The 8% half-tone PSM was selected for the definition of the isolated narrow space. Before lithography, 2000Å nitride film was deposited on the wafer. After I-line PSM exposure and RIE etch of the silicon nitride film, 0.25μm or less opening was formed on the nitride film. To further reduce the dimension of the opening, the wafer was then deposited addition 600Å and 900Å nitride and etched back using RIE without any mask. 0.2μm or less opening was formed on the wafer after the dry etch. The wafer was then coated with another layer of photoresist to form lift-off structure. This novel process is a high throughput T-gate I-line PSM process compared to conventional E-beam lithography technology for GaAs MMIC production.