Abstract:
Autodoping from a diffused region in a substrate during growth of an epitaxial layer is prevented by growing a thin epitaxial layer over the entire surface of the substrate and then removing the epitaxial layer except for the portion over the diffused region. A second epitaxial layer is then grown over the surface of the substrate and the first epitaxial layer. The first epitaxial layer caps the diffused region to prevent autodoping into the second epitaxial layer during growth thereof over the surface of the substrate not having the diffused region therein.
Abstract:
Autodoping is minimized during the growth of an epitaxial layer on a semiconductor substrate by contacting the substrate with a gaseous reaction mixture at a low pressure, substantially below atmospheric to deposit at least the initial capping layer. The reaction mixture contains a relatively minor portion of a semiconductor compound along with a carrier gas. Subsequently, a second gaseous reaction mixture containing a greater portion of a compound of a semiconductor material may be used to complete the deposition of the epitaxial layer. This is done merely to reduce the total growth cycle.
Abstract:
A process which utilizes an anodized porous silicon technique to form dielectric isolation on one side of a semiconductor device is described. Regions of silicon semiconductor are fully isolated from one another by this technique. The starting wafer typically is predominantly P with a P+ layer thereon. A P or N layer over the P+ layer is formed thereover such as by epitaxial growth. The surface of the silicon is oxidized and a photoresist layer applied thereto. Openings are formed in the photoresist. Openings are formed in the silicon dioxide using the photoresist as a mask and appropriate etching techniques. The openings in the silicon dioxide define the regions to be etched by reactive ion etching. Reactive ion etching is accomplished at least down to the P+ region. The structure is then subjected to the anodic etching technique which preferentially attacks the P+ layer to form porous silicon throughout the P+ layer. The structure is then placed in a thermal oxidation ambient until the porous silicon layer has been fully oxidized to silicon dioxide. The openings through the surface layer are filled up with oxide to fully isolate the P or N surface layer.