Glass-to-Metal Seals

Abstract

Stoller and coworkers at RCA have described a novel technique for forming glass-to-metal seals using a silicon nitride interface layer. Their method consists of depositing silicon nitride from the vapor phase onto any metal that will withstand the deposition temperature, about 700°C, in a reducing atmosphere. The adhesion of submicron-thick silicon nitride films to all metals tested appears to be excellent, and the silicon nitride was found to be readily “wet” by a wide variety of common glasses and frits. An important property of silicon nitride, one that renders it useful for this purpose, is its impermeability to oxygen and metal ions. This property is also utilized in the diffusion barrier applications against oxygen, alkali metals and semiconductor dopants (see Diffusion Mask Section). Good seals were effected with the metals: molybdenum, copper, tantalum, Kovar, and gold and a variety of ceramic frits (Corning Pyroceram #45, Owens-Illinois #CV-102, Owens-Illinois #SG67, Corning #7570).