Abstract: A process for fabricating volatile and nonvolatile field effect devices on a common semiconductor wafer, and a unique composite structure for a nonvolatile memory device fabricated according to the process. A distinct feature of the process is the elimination of nitride from beneath any poly I layers while selectively retaining sandwiched and coextensive segments of nitride and poly II layers for the memory devices. In one form, the method commences with a wafer treated according to the general localized oxidation of silicon process, followed by a blanket enhancement implant and selectively masked depletion implants. The succeeding contact etch step is followed by a deposition of a poly I layer, a resistor forming implant and a patterned etch of the poly I layer. Thereafter, a first isolation oxide is grown, selective implants are performed to center the memory window, the memory area is etched, and the memory area is covered by a regrowth of a very thin memory oxide.

Abstract: A method of conditioning a nitride surface by treating it with ionized oxygen is disclosed. The nitride surface is placed in a vacuum and treated with the ionized oxygen for a period of time sufficient to condition the nitride for subsequent processing steps. The ionized oxygen treatment is performed substantially at ambient temperature. The conditioning method is included in a process for improving the adhesion characteristics of a photoresist film to a silicon nitride surface. A liquid solution of hexamethyldisilazane is applied to the conditioned nitride surface. Thereafter, a photoresist is applied, exposed through a photographic mask and developed in a known manner for the purpose of forming a photoresist masking film pattern. The photoresist film pattern typically serves as a mask during an etching process in which areas not covered by photoresist are removed by a suitable etching solution.

Abstract: An improvement of the prior art method of processing large scale integrated (LSI) semiconductors is disclosed, wherein an etching procedure, which was previously performed as the final processing step, is now done at an earlier stage to preclude damage to the surface of the wafer on which the active devices are formed. In the prior art method of fabricating an active device on a semiconductor wafer, an undesirable layer of field oxide manifests itself on the reverse side when the field oxide is grown on the obverse or principal side of the wafer. The prior processing philosophy was to allow the oxide layer to remain on the wafer until after the processing was completed and, as a final step, the undesired oxide coating was removed. This was done by carefully placing the wafer in a pool of etchant so that only the reverse side is etched.