The application of thin films of material is useful in a variety of commercial processes. The application of thin layers of silicon nitride, for example, is used in the manufacture of integrated circuits to provide a thin, conformable layer of high quality dielectric. In these applications the nitride is typically applied onto heterogeneous substrates such as patterned metal on silicon. The largest metal components in these applications typically have areas no larger than a few tens of square microns.
More recently in the fabrication of flat panel displays, silicon nitride layers have been applied to larger area heterogeneous substrates such as patterned chromium on glass. In this application patterned metal components having areas of square millimeters or more are desired, but the silicon nitride films deposited on these heterogeneous surfaces are non-homogeneous in significant respects. For example the etch rate of the deposited silicon nitride varies widely from location to location, making the design and fabrication of displays difficult and expensive. Similar inhomogeneities are observed in the application of other thin films such as silicon oxide (SiO.sub.x) and amorphous silicon (a--Si) when they are deposited on heated heterogeneous substrates in a reduced pressure ambient.
Accordingly, there is a need for an improved method of applying homogeneous layers onto heterogeneous substrates.