IMPROVEMENT TO THE ANISOTROPIC CHEMICAL ETCHING PROCESS OF SILICON OXIDE IN THE MANUFACTURE OF MOS TRANSISTOR FLASH EPROM DEVICES

摘要

This invention relates to an improvement to an anisotropicchemical etching process for silicon oxide and to a manufacturingprocess for silicon FAMOS transistor Flash EPROM memory devicesincluding said improvement, said silicon oxide chemical etchingprocess having an etching direction and being characterised in that thefollowing steps are performed: - a preliminary deposition of a layer of silicon nitride on thesilicon oxide; - a first anisotropic chemical etching or break-through stage,along said etching direction, aimed at removing the nitride layer fromthe silicon oxide surfaces orthogonal to said etching direction; - a second anisotropic chemical etching stage along saidetching direction, aimed at removing the silicon oxide surfacesorthogonal to said etching direction.