Process to produce ultrathin crystalline silicon nitride on si (111) for advanced gate dielectrics

Abstract

A method of making a semiconductor device and the device. The device, according to a first embodiment, is fabricated by providing a silicon ( ) surface, forming on the surface a dielectric layer of crystalline silicon nitride and forming an electrode layer on the dielectric layer of silicon nitride. The silicon ( ) surface is cleaned and made atomically flat. The dielectric layer if formed of crystalline silicon nitride by placing the surface in an ammonia ambient at a pressure of from about 1×10 to about 1×10 Torr at a temperature of from about 850° C. to about 1000° C. The electrode layer is heavily doped silicon. According to a second embodiment, there is provided a silicon ( ) surface on which is formed a first dielectric layer of crystalline silicon nitride having a thickness of about 2 monolayers. A second dielectric layer compatible with silicon nitride and having a higher dielectric constant than silicon nitride is formed on the first dielectric layer and an electrode layer is formed over the second dielectric layer. A third dielectric layer of silicon nitride having a thickness of about 2 monolayers can be formed between the second dielectric layer and the electrode layer. The second dielectric layer is preferably taken from the class consisting of tantalum pentoxide, titanium dioxide and a perovskite material. Both silicon nitride layers can be formed as in the first embodiment. The electrode layer is preferably heavily doped silicon