Silicon-on-Insulator (SOI) Wafers

A wafer technology known as silicon-on-insulator, or SOI, represents the future of microprocessor design.

In SOI-based chip design, a transistor’s silicon junction area is placed on top of an electrical insulator, typically silicon oxide. By thus eliminating the junction capacitance between the transistor and the silicon substrate itself, the transistor is able to operate much more quickly. Moreover, it can operate with as little as one-third the power requirements of a typical transistor on a standard silicon wafer.

SOI chip production is the fastest-growing area of silicon wafer manufacturing, because faster, lower-power transistors are essential to the multitude of handheld and/or wireless devices that have become pervasive consumer products. In short, the next wave of the digital revolution will be built on the back of the SOI chip, and Natcore’s technology promises to help make SOI chips more affordable. The following illustration shows a schematic cross section of a typical SOI wafer.

There are a variety of ways to produce the top, or device, layer, but all processes require a pre-oxidized layer ranging in thickness from a few tenths of a micron to a few microns. (1.0 micron = 1,000 nanometers.) The substrate is a standard silicon wafer several hundred times the thickness of the buried oxide layer. The finished SOI wafer can be processed using standard wafer-fab equipment.

Production of the crucial oxide layer can be accomplished using Natcore’s proprietary film-growth technology, with substantial capital and operating cost savings.

Although the present volume of the SOI wafer market does not represent an important source of revenues for Natcore, the application is straightforward, and worth the effort to position us to enter it as soon as practicable. Semiconductor device market analysis firms unanimously predict that SOI wafers will eventually supplant ordinary silicon wafers in the long term. Were that to occur, SOI wafers would eventually represent a potential hundred-million-dollar-per-year market for Natcore.