Accession Number : ADD014967

Title :   Method for Producing Substoichiometric Silicon Nitride of Preselected Proportions.

Descriptive Note : Patent, Filed 30 Sep 87, patented 14 May 91,

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s) : Hubler, Graham K ; Donovan, Edward P ; Van Vechten, Deborah

Report Date : 14 May 1991

Pagination or Media Count : 8

Abstract : This patent discloses an apparatus and method for producing films of silicon nitride whose index of refraction varies continuously with film depth by preselected amounts between n = 3.9 and n = 1.99. This is done by producing an amorphous film of silicon nitride, Si(1-x) N(x), of pre-selected stoichiometry between x = 0 and and x = 0.57. In a vacuum-chamber, a target substrate is exposed to vaporized silicon while being simultaneously bombarded with an ion beam of relatively high kinetic energy, ionized, nitrogen particles. The nitrogen embeds in the silicon film deposited on the substrate to form amorphous silicon nitride, the stoichiometry of which depends on the intensity of the ion beam. Instruments measure during the deposition the relative rate of arrival at the target for silicon and nitrogen, and, with pre-generated calibration data for the apparatus, enable an operator to selectively control the film's stoichiometry by controlling the ion beam's intensity response to the measured rate of silicon deposition.

Descriptors :   AMORPHOUS MATERIALS, DEPOSITION, DEPTH, FILMS, HIGH ENERGY, INSTRUMENTATION, INTENSITY, ION BEAMS, KINETIC ENERGY, MEASUREMENT, NITROGEN, PARTICLES, PATENTS, RATES, REFRACTIVE INDEX, RESPONSE, SELECTION, SILICON, SILICON NITRIDES, STOICHIOMETRY, SUBSTRATES, TARGETS

Subject Categories : Solid State Physics
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE