Method for the determination of the angular dependence during dry etching

Abstract

Process simulation is going to play an ever increasing role in the development, process optimization, and production of integrated circuit devices, yielding shorter development times and reduced costs as compared to traditional development methods. One of the most notorious problems one faces in topography simulations in particular is the determination of the erosion/growth rates of materials exposed to a variety of complex physicochemical processes. The latter evolve continually to satisfy the needs of the ever advancing microelectronic industry, while our understanding about these processes is often incomplete and insufficient for their description. Existing theoretical models, which are often semiempirical, include a set of fitting parameters which are generally unknown and their determination in most cases involves guesswork. Another much more pragmatical approach to the problem is to measure these etch/growth rates directly in situ in the production equipment and feed the data into a topography simulator. In this article we present a simple and general method for measuring the angular dependence of the etch rate of a variety of materials using specially patterned silicon wafers. With anisotropic wet etching of silicon wafers it is possible to create structures defined by specific crystallographic planes, thus producing a variety of planar orientations on one and the same wafer. The structures can be oxidized and coated with the material of interest and processed under standard operating conditions. The method will be presented together with angular dependence data from typical dry etching processes. The results will be used as an input to the topography simulation program DINESE.