Method for angular sputter yield extraction for high-density plasma chemical vapor deposition simulators

Abstract

High-density plasma chemical vapor deposition (HDP CVD) is a deposition method of current interest for gap fill of intermetal and interlevel dielectrics in semiconductor circuits. In HDP CVD processes the silicon dioxide film is often sputter etched as it is being deposited. The resputtering of the deposited film is a crucial process component in determining the final surface topography. Hence, it is imperative that the process simulators take this effect into consideration. In this work, we propose a method to extract the angle-dependent sputter yield for the HDP CVD process. This method constitutes the usage of our test structure. The extracted angular yield distribution is, then, used to simulate the final silicon dioxide profile. The distribution validity is determined by comparison of the simulated profile against the experimental profile. SPEEDIE (Stanford profile emulator for etching and deposition in integrated circuit engineering), a deposition and etching simulation program, was used as the simulator while experiments were performed on a HDP CVD system. A reasonably, good agreement was obtained between simulated and experimental profiles, indicating an accurate angular yield extraction. The extracted angular yield curve was compared with other such curves from literature for different ion energies. This comparison showed a trend of increase in the angle at which maximum yield occurs as the ion energy increased.