Slope Tailoring for Boron-Doped Polysilicon Using ARGON Implantation in the SFET PROCESS
Original Publication Date: 1985-Dec-01
Included in the Prior Art Database: 2005-Feb-19
Superior slope and etch bias process control results may be achieved through the proper concentration of boron at the surface of boron-doped polysilicon films used in the SFET (silicon field-effect transistor) process. When it is desirable to have via window slopes etched in polysilicon films to be linear, slope tailoring techniques are implemented. The basic concept of slope control for a wet-etched in situ boron-doped polysilicon film (one doped as it is being deposited by low pressure chemical vapor deposition (LPCVD)) is to increase the etch rate near the film surface relative to the underlying bulk by means of a low energy argon implant. The implant will damage the top polysilicon film, thereby causing the upper region to etch at a faster rate than the underlying undamaged polysilicon.