高分子蝕刻保護層於單晶矽懸浮結構之製程平台開發

Abstract

本論文根源於單晶矽微加工技術之特點，提出以感應耦合電漿離子蝕刻（Inductively Coupled Plasma Reactive Ion Etching , ICP-RIE）之體型微加工製程技術，以高分子作為蝕刻保護層來製作單晶矽懸浮結構製程平台技術（Polymer Passivation Layer for Suspended structures Etching , PoPLSE），除黃光製程外，其餘製程均整合在ICP-RIE機台中完成，低溫製程、製程簡化、使用機台少及製程快速，為此製程平台之特點。 PoPLSE製程平台研究分為非等向性蝕刻及等向性蝕刻兩部分，在非等向性蝕刻的部分，詳細探討ICP-RIE各項參數對蝕刻的影響，考量蝕刻之垂直度、深寬比、粗糙度、側向蝕刻及蝕刻速率等規格，針對不同需求，開發不同應用之最佳化製程參數，深寬比達30且垂直度89 ±1˚之高深寬比蝕刻製程、側壁粗糙度8nm（Ra）之鏡面蝕刻製程及結構線寬56 nm深度943 nm之奈米尺寸結構蝕刻。在等向性蝕刻的部分，探討高分子之保護效果，在不同結構開口尺寸下，高分子薄膜沈積、底部高分子薄膜去除及等向性蝕刻之各項參數關係，成功製作出結構厚度30 μm及60 μm、結構線寬/開口為5 μm及10 μm之懸浮梳狀結構，證明此製程平台之可行性。除等厚度懸浮結構外，非等厚度懸浮結構及次微米尺寸懸浮結構也以相同概念製作成功，並應用於微光開關及微加速度計的開發。最後，提出一創新補償結構設計輔助尖角及凹角結構之電漿離子蝕刻，製作側向單晶矽閃耀型微光柵，應用非等向性蝕刻技術及懸浮製程技術，成功做出在結構厚度70μm之微光柵結構。

In recent year, MEMS products have been widely used in various industries, especially in the 3C manufactures. The rapid and stable fabrication platform technology of the process plays a very important role in industrial development. This paper presents a rapid bulk micromachining process named Polymer Passivation Layer for Suspended structures Etching (PoPLSE) by using polymer as protecting passivation layer at both anisotropic and isotropic etching steps. The proposed method can fabricate suspended single-crystal-silicon (SCS) structures in Inductively Coupled Plasma Reactive Ion Etching (ICP-RIE) chamber directly, which would simplify the fabrication process and save fabrication time. In anisotropic silicon etching, the basic parameters have been systematical studied in the paper. For the different etching specifications, such as verticality, aspect-ratio, roughness, lateral etching and etching rate, etc., the optimum recipe of high-aspect-ratio etching process, smooth etching process and nano-scale etching process parameters have been developed for different applications. The current study systematically investigates critical fabrication parameters to verify feasibility of the proposed PoPLSE fabrication platform method, and discusses the polymer passivation time and removal time of polymer at the base of substrate at different opening gaps of 5, 10, 30, and 50 μm and different depths of 30 and 50 μm to establish suitable recipes for fabricating suspended structures. The suitable recipes for comb-drive microstructures with 30μm or 60μm in depth and 5μm or 10μm line width at different opening sizes are experimentally identified. It is also shown that the proposed method can fabricate not only the suspended microstructures with the same thickness, but also suspended microstructures with different thickness, as well as in sub-micro scale. Finally, an innovative compensative structure assisted ICP-RIE etching to fabricate SCS blaze-type micro-grating have been proposed. The micro-grating have successfully fabricated using anisotropic etch and suspended structure technology.