Isolation and Interconnect Scheme for Sidewall Contact Structures
Original Publication Date: 1986-Oct-01
Included in the Prior Art Database: 2005-Mar-09
Disclosed is a method of forming a buried oxide insulation under polysilicon in semiconductor devices. Previous processes used to form sidewall contact structures [1,2,3] have used either sidewall masked isolation (SWAMI) or epitaxial refill of a patterned oxide so as to provide a buried isolation layer. Both approaches lead to structures which are not defect-free. Also, the SWAMI process is complicated. In the present fill oxide isolation (FOXI) process, which is both simple and obtains a defect-free structure, a chemical vapor deposition (CVD) nitride layer 1 (Fig. 1) is deposited upon a thermally grown SiO2 layer 2. Layers 1 and 2 are patterned using reactive ion etch (RIE) and a photoresist mask with the pattern further etched using a directional silicon RIE to form a Si pedestal 3.