Three-dimensional modeling and simulation of the Bosch process with the level set method

A new approach for three-dimensional (3-D) simulation of the Bosch process with arbitrarily complex mask shape is presented. Its profile evolution algorithm is based on the 3-D narrow band level set method which is memory and computation efficient and also allows easy handling of topographic changes. A series of simulations and experiments have been conducted to verify the accuracy of the simulation system. After model parameter extraction from experiments, this simulator can be used to simulate several phenomena in the Bosch process, such as the formation and adjustment of sidewall scallops, the lag and pattern transfer effects and the profile control of trench etching. The simulation results are in good agreement with experimental results and the proposed simulation system demonstrates to be high accurate and efficient.

I. Introduction

Nowadays in semiconductor devices and MEMS fabrication, deep reactive ion etching (DRIE) is a new and powerful tool for the etching of extremely deep trenches with nearly vertical sidewalls. The most popular silicon DRIE technique is a patented process developed by Robert Bosch GmbH [1], also known as the Bosch process. The Bosch process consists of multiple cycles of alternating etching and deposition steps in an ICP-RIE system, advancing the trenches formed in small increments until the expected aspect ratio is reached. Each phase lasts several seconds. The deposited polymer serves to protect the sidewall during etching step, which leads the trench bottom to be selectively etched to extend the aspect ratio.