Prevention method of a notching caused by surface charging in silicon reactive ion etching

Abstract

This paper proposes a method to prevent silicon from a notching in a reactive ion etching (RIE) process by introducing a self-aligned metal interlayer to a silicon/glass bonded fixture. A metal interlayer prevents a charge buildup at the bottom of a silicon trench, therefore silicon structures do not suffer from charge-induced local damage. A self-aligning process of Ti/Au interlayer is accomplished by a lift-off process using a photoresist etch mask as a sacrificial layer. Titanium is a diffusion barrier of gold to silicon and gold is preferred due to its chemical stability in a pre-cleaning step. The effectiveness of the proposed method is verified by applying it to the fabrication of a simple trench and comb electrode. The applicability of the proposed methodology is examined by fabricating an optical knife edge device.

Tactical grade MEMS vibrating ring gyroscope with high shock reliability

“…However, when a dielectric substrate layer such as a glass wafer is used, the notching phenomenon occurs at the interface between two layers, causing structural imperfections [16,17]. To realize the precise structures of the proposed VRG, a fabrication process was developed to prevent the notching effect using an SOPG (silicon-on-aluminum patterned glass) wafer.…”

“…Post-shock measurement Tactical-grade requirement [6] Resonant frequency (kHz) 16.93 -Q-factor 61,113 -Scale factor accuracy (ppm) 49 10 to 1000 Bias instability (°/h) 0.83 0.1 to 10 Angular random walk (°/h 1/2 ) 0.083 0.5 to 0.05…”

Failure Analysis and Process Improvement for Through Silicon Via Interconnects

“…The results are shown in Figure 2. While Kim described a method to prevent silicon from notching by introducing self-aligned metal interlayer to prevent charge buildup [10]. It also shows that copper is plated on the side wall uniformly and even plated at the bottom.…”

Key Processes of Silicon-On-Glass MEMS Fabrication Technology for Gyroscope Application

“…The dependencies of pressure and different slurry dilution ratios on silicon removal rate are also explored to solve the surface damages that are induced by breakthrough and stress concentration. Numerous factors affect the DRIE experimental results [ 14 , 15 , 16 ]. Thus, the main parameters including the flowrate of SF6, C4F8, oxygen, coil power, and platen power are adjusted to reduce the lag effect.…”