Method of making a silicon nitride film that is transmissive to ultraviolet light

Abstract

A method for producing an ultraviolet light (UV) transmissive silicon nitride layer in a plasma enhanced chemical vapor deposition (PECVD) reactor is presented. The UV transmissive film is produced by reducing, in comparison to a standard silicon nitride process, a flow rate of the silane and ammonia gas precursors to the PECVD reactor, and significantly increasing a flow rate of nitrogen gas to the reactor. The process reduces the concentration of Si—H bonds in the silicon nitride film to provide UV transmissivity. Further, the amount of nitrogen in the film is greater than in a standard PECVD silicon nitride film, and as a percentage constitutes a greater part of the film than silicon. The film has excellent step coverage and a low number of pinhole defects. The film may be used as a passivation layer in a UV erasable memory integrated circuit.

Dependencies are inferred from the claim text.