North American Philips Corporation

Helmut Baumgart

Emil Arnold

Ronald D Pinker

Andre M Martinez

Barbara A Rossi

A silicon-on-insulator material is formed by a method which includes the steps of forming a p-type silicon epitaxial layer, doped with boron and a higher concentration of germanium, on the surface of a semiconductor silicon substrate, forming an additional silicon epitaxial layer on the p-type silicon epitaxial layer, forming an oxide layer on the additional silicon epitaxial layer, forming an oxide layer on another semiconductor silicon substrate, forming a laminate by bringing into contact, at room temperature, the oxide layers thereby bonding together the substrates, etching the silicon substrate provided with the silicon epitaxial layers, with an isotropic etch to remove most of this silicon substrate, exposing the laminate to an anisotropic etch for this silicon substrate until the remainder of this silicon substrate is removed but only a part of the p-type epitaxial layer is removed and then exposing the resultant structure to an additional isotropic etch for the p-type epitaxial layer for a time sufficient only to remove only the remainder of the p-type epitaxial layer.

Process for making strain-compensated bonded silicon-on-insulator

An improved technique for forming silicon-on insulator films for use in integrated circuits. The technique provides an improved encapsulation layer to enable in a reproducible way the zone melt recrystallization of such films. The encapsulation layer consists of a first layer of a doped SiO.sub.2 (silicate glass) on which a further layer of Si.sub.3 N.sub.4 is deposited. The doped SiO.sub.2 forms a fusible glassy material which is rendered semi-liquid and flows at the temperatures used in recrystallization. The softening of the encapsulation material accommodates volume expansion and eliminates the biaxial stresses in the layered structure. The Si.sub.3 N.sub.4 layer adds mechanical strength to the SiO.sub.2 layer and improves the wetting angle.

Method of forming improved encapsulation layer

A monocrystalline layer of silicon is formed on an insulating substrate according to the present invention by use of a semi-insulating layer between the insulator and silicon film. This semi-insulating layer is composed of a mixture of silicon crystallites embedded in a silicon dioxide glass, for example. Such a technique results in a structure which is substantially free of cracking resulting from differences in thermal expansion coefficients between the insulating substrate and the monocrystalline silicon layer.

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Mahopac, NY, United States of America

Helmut Baumgart