Chemical vapor deposition of silicon under reduced pressure in hot-wall reactors

Abstract

A detailed mathematical model is discussed for low pressure, hot wall, chemical vapor deposition reactors. Although this model originates from previous studies on low pressure chemical vapor deposition (LPCVD) (Jensen and Graves, 1983), it includes two-dimensional diffusional mass transport between successive wafers, convective and diffusive mass transport in the annulus formed by the edges of the wafers and the reactor wall, and new overall reaction kinetics for the silicon depositing from silane. The system of the resulting coupled reactor equations is solved by finite difference methods. The chemical vapor deposition (CVD) of polysilicon from SiH 4 is studied in detail within the context of the model presented. Experimental data obtained in a LPCVD reactor operating in the electrical engineering department at Purdue University and other data reported in the literature compare very well with the predictions of the model discussed.