METHOD FOR THE DETERMINATION OF THE ANGULAR-DEPENDENCE DURING DRY-ETCHING

Process simulation is going to play an ever increasing role in the dev elopment, process optimization, and production of integrated circuit d evices, yielding shorter development times and reduced costs as compar ed to traditional development methods. One of the most notorious probl ems one faces in topography simulations in particular is the determina tion of the erosion/growth rates of materials exposed to a variety of complex physicochemical processes. The latter evolve continually to sa tisfy the needs of the ever advancing microelectronic industry, while our understanding about these processes is often incomplete and insuff icient for their description. Existing theoretical models, which are o ften semiempirical, include a set of fitting parameters which are gene rally 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 a nd feed the data into a topography simulator. In this article we prese nt a simple and general method for measuring the angular dependence of the etch rate of a variety of materials using specially patterned sil icon wafers. With anisotropic wet etching of silicon wafers it is poss ible to create structures defined by specific crystallographic planes, thus producing a variety of planar orientations on one and the same w afer. The structures can be oxidized and coated with the material of i nterest and processed under standard operating conditions. The method will be presented together with angular dependence data from typical d ry etching processes. The results will be used as an input to the topo graphy simulation program DINESE. (C) 1996 American Vacuum Society.