Low-Stress Tungsten Films
Original Publication Date: 1987-Jan-01
Included in the Prior Art Database: 2005-Jan-31
This article describes a technique wherein the high internal stress in sputtered tungsten films is reduced to a very low level, solving many problems associated with high stress. Tungsten films prepared by high-rate magnetron sputtering are considered to be used in VLSI technology for bipolar and FET devices because of low resistivity, and ability to withstand high-temperature processing. However, one problem with this material is the ever-present high stress in these films. The stress level can be adjusted by varying one of the deposition parameters, such as the Ar pressure, during sputtering, as shown in the figure. However, the cross-over pressure varies from day to day depending upon the background pressure and other plasma conditions, and it is not easy to reproduce.