Anicon, Inc.

Derrick W Foster

Robert B Herring

Thermal CVD process for forming Si.sub.3 N.sub.4 -type films on substrates by reaction of gaseous NF.sub.3 with gaseous disilane at a temperature in the range of 250.degree.-500.degree. C., at pressures of 0.1-10 Torr. The mole ratio of NF.sub.3 to silane is in the range of 0.5-3.0 and the reaction zone is preferably isothermal (T controlled to within .sup.+ 5.degree. C.). The resulting films have RI's in the range of 1.4 to 3.0. The process parameters can be controlled to dope the film with H and/or F, or to create zones of differing properties within the film. The process does not cause radiation damage, metal migration, stored charge dissipation or high levels of impurities. Control of distance between adjacent wafers and wafer-to-wall spacing combined with laminar gas flow gives excellent film thickness uniformity, on the order of below about .+-.5% across the wafer face, both within (across) wafers and from wafer to wafer (batch uniformity).

Low temperature silicon nitride CVD process

A chemical vapor deposition wafer boat for polysilicon deposition in a vertical CVD apparatus comprises upper and lower, mutually engaging, open ended hemicylinders. Gas flow passageways are present in a diffusion zone of the lower hemicylinder wall, but not in the remainder of the walls of the hemicylinder. Gas flow to the wafers is limited to diffusion flow, and the wafers are protected from particulates forming in the gas stream during the coating operation.

Growing community of inventors

San Jose, CA, United States of America

Derrick W Foster