AVS 45th International Symposium
    Plasma Science and Technology Division Tuesday Sessions
       Session PS2-TuM

Paper PS2-TuM9
Studies of High Density Oxide Etch Mechanisms with a Physically-based Profile Simulator

Tuesday, November 3, 1998, 11:00 am, Room 318/319/320

Session: Oxide Etching
Presenter: V. Vahedi, Lam Research Corporation
Authors: V. Vahedi, Lam Research Corporation
D.J. Cooperberg, Lam Research Corporation
J.M. Cook, Lam Research Corporation
L. Marquez, Lam Research Corporation
E. Hudson, Lam Research Corporation
J. Winniczek, Lam Research Corporation
Correspondent: Click to Email
Dielectric etching accounts for about forty-five percent of the etch steps in a semiconductor fabrication process, and with emerging device integration technologies this percentage will soon increase. In contrast to other etch processes, highly selective dielectric etching using high density fluorocarbon plasmas results in simultaneous etching and deposition. In order to implement dielectric etching successfully in a production environment, it is critical to understand how to balance the etching and deposition components. The required balance will be a strong function of the properties of the microstructures being produced as well as the aspect ratio of the features. While there are many proposed mechanisms to explain the dependence of this balance on aspect ratio, it is not clear which mechanisms are the dominant ones under a given set of process conditions. We are using our semi-empirical profile simulator to investigate the relative importance of various mechanisms leading to aspect ratio dependent etching (ARDE) in dielectric etching. Our dielectric etch model includes ion-enhanced etching, physical sputtering and polymer deposition as well as realistic ion energy distribution functions. We will present the results of our polymer deposition experiments which were performed to determine polymer sticking coefficients and study the role of ion-assisted deposition in sub 0.5µm features. We will also present results from sputtering experiments which were designed to measure carefully the angular and energy dependence of sputter yield of photoresist and oxide. The rest of the parameters were set using our calibration scheme which leads to optimal agreement between simulation and digitized SEM data. We will also present typical profiles under various process conditions.