Abstract: The present invention is predicated upon the fact that an emission trace from a plasma glow used in fabricating integrated circuits contains information about phenoma which cause variations in the fabrication process such as age of the plasma reactor, densities of the wafers exposed to the plasma, chemistry of the plasma, and concentration of the remaining material. In accordance with the present invention, a method for using neural networks to determine plasma etch end-point times in an integrated circuit fabrication process is disclosed. The end-point time is based on in-situ monitoring of the optical emission trace. The back-propagation method is used to train the network. More generally, a neural network can be used to regulate control variables and materials in a manufacturing process to yield an output product with desired quality attributes. An identified process signature which reflects the relation between the quality attribute and the process may be used to train the neural network.

Abstract: In a radio-frequency plasma deposition reactor (10), SiO.sub.2 is deposited from a source (16) of tetraethoxysilane (TEOS). The deposition is made to be anisotropic, that is, to be deposited preferentially on horizontal surfaces, by use in the deposition atmosphere of a constituency such as NH.sub.3 or NF.sub.3 which inhibits SiO.sub.2 deposition, along with a radio-frequency power in excess of 100 watts, which preferentially removes the inhibiting gas from horizontal surfaces through ion impact.

Abstract: A high quality Al.sub.2 O.sub.3 film is deposited by means of plasma enhanced chemical vapor deposition by passing a trialkylaluminum vapor over the surface of a substrate and CO.sub.2 gas as the oxidant in a plasma above the substrate surface. The CO.sub.2 is controlled to prevent particle formation due to gas phase reaction in the plasma as opposed to directly on the substrate surface.

Abstract: A method for determining the optimum time at which a plasma etching operation should be terminated. The optical emission intensity (S.sub.1) of the plasma in a narrow band centered about a predetermined spectral line, indicative of the gas phase concentration of a plasma etch product or reactant species. The optical emission intensity (S.sub.2) of the plasma in a wide band centered about the predetermined spectral line, indicative of a background emission signal is also monitored. The intensity (S.sub.1L) of the spectral line is then determined in accordance with the equation S.sub.1L =S.sub.1 -k (.alpha.S.sub.2 -S.sub.1). The etching process is terminated when the monitored signal intensity (S.sub.1L) or its time derivative reaches a predetermined value.