The "ISLANDS" method - A manufacturable porous silicon SOI technology

The formation of high-quality, dielectrically isolated single-crystal silicon films permits the fabrication of integrated circuits that exhibit higher tolerance to alpha-induced soft errors, better latch-up immunity, and faster switching speeds resulting from reductions in parasitic capacitances and higher packing densities. Full Isolation by Oxidized Porous Silicon (FIPOS) has long been thought to be a desirable Silicon-On-Insulator (SOI) technology for both material and device reasons, but limitations inherent in the process of forming and oxidizing the porous layer have inhibited its widespread use and have created serious doubts about manufacturability. This paper describes the development and characterization of the Isolation by Self-Limiting Anodization of an N+ Epitaxially Defined Sublayer (ISLANDS)* method. This new technique for dielectrically isolating epitaxial quality silicon films uses a specially formed anodizable structure of N/N+/N- silicon together with computer-controlled processing to provide the flexibility and control needed for implementing porous silicon technology into a manufacturing environment. Data from discrete MOS transistors fabricated in isolated islands is discussed.