Processing Research on Chemically Vapor Deposited Silicon Nitride
Abstract
The feasibility of preparing free standing plate and hemispherical domes of crystalline silicon nitride by the chemical vapor deposition (CVD) technique has been established as a result of processing research conducted on this program. Physical property characterizations of a wide range of deposits have established the CVD form of silicon nitride as a candidate electromagnetic (EM) window material for advanced, high-performance tactical missile systems. The EM absorption coefficients of CVD silicon nitride in the UV-IR and radar transmittance passbands are far superior to the more conventional silicon nitride modifications (i.e. HPSN and RSSN). At the current stage of process development, the flexure strength is comparable to RSSN exhibiting similar strength retention properties at elevated temperatures. Average room temperature flexure strength levels of 317 MN/sq m (46,000 psi) were achieved by codeposition with minor amounts of aluminum chloride during this program (Phase 3); this level represents a 150 percent increase in strength compared to levels achieved during the initial Phase 1 program. With a better understood deposition model now in hand, as a result of the Phase 3 program, a high probability exists in future process optimization studies for achieving additional improvements in the mechanical and optical properties of CVD alpha-silicon nitride.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1981
- Accession Number
- ADA109204
Entities
People
- J. D'andrea
- J. J. Gebhardt
- R. A. Tanzilli
Organizations
- General Electric