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.

Total dielectric isolation utilizing a combination of reactive ion etching, anodic etching, and thermal oxidation

A method for forming a non-epitaxial bipolar integrated circuit comprising first forming in a silicon substrate of one-type of conductivity, recessed silicon dioxide regions extending into the substrate and laterally enclosing at least one silicon substrate region of said one-type conductivity. Then, forming by ion implantation the first region of opposite-type conductivity which is fully enclosed laterally by said recessed silicon dioxide. This region is formed by directing a beam of ions of opposite-type conductivity impurity at said enclosed silicon region at such energy and dosage levels that the opposite conductivity-type impurity introduced into the substrate in said region will have a concentration peak at a point below the surface of this first region. Then, a region of said one-type conductivity is formed which extends from the surface into said first opposite-type conductivity region to a point between said concentration peak and said surface. Next, a second region of said opposite-type conductivity is formed which extends from the surface part way into said region of one-type conductivity. Preferably, the ion beam energy level is at least one MeV, and said concentration peak is at least one micron below the surface. It is further preferable that the energy and dosage levels of the beam of ions are selected so that the opposite-type conductivity impurity has a more gradual distribution gradient between the peak and the surface than between the peak and the junction of the first region with the substrate.

Method for forming a non-epitaxial bipolar integrated circuit

A process for forming holes with precisely controlled dimension and position in monocrystalline silicon wafers wherein the holes are fabricated with vertical sides. In the preferred process, both sides of the silicon body are masked, opposite registered openings made in the masking layers, an impurity introduced through the openings into the body forming low resistivity regions, the body anodically etched through the openings until a porous silicon region is formed completely through the body, and subsequently removing the resultant porous silicon region with a silicon etchant.

Process for forming apertures in silicon bodies

A method for forming monocrystalline silicon carbide on a silicon substrate by converting a portion of the monocrystalline silicon substrate into a porous silicon substance by anodic treatment carried out in an aqueous solution of hydrofluoric acid, heating the resultant substrate to a temperature in the range of 1050° C to 1250° C in an atmosphere that includes a hydrocarbon gas for a time sufficient to react the porous silicon and the gas, thereby forming a layer of monocrystalline silicon carbide on the silicon substrate.

Process for forming monocrystalline silicon carbide on silicon substrates

A semiconductor fabrication method for producing dielectrically isolated silicon regions wherein high conductivity regions surrounding device regions to be electrically isolated are produced in a silicon body, the high conductivity regions anodically etched in a solution to selectively produce regions of porous silicon, the body exposed to an oxidizing environment while heated to an elevated temperature to oxidize the resultant porous silicon regions.

Method of fabricating semiconductor device embodying dielectric isolation

A semiconductor device and a method of producing the same. The semiconductor device comprises a silicon single crystal including a porous substance formed so as to advance from surface area toward inside area of said silicon single crystal. The porous substance is produced on the silicon single crystal by utilizing said crystal and a conductive metal material which is not soluble to hydrofluoric acid as electrodes, applying a positive direct current voltage to the silicon single crystal and a negative direct current voltage to the other metal electrode, and carrying out an electrolysis in an aqueous solution of the hydrofluoric acid.

Sakai Tetsushi

Papers

Semiconductor device and method of producing the same

Halbleitervorrichtung mit einem isolierenden Bereich und Verfahren zu ihrer Herstellung