Insulator substrate with a thin mono-crystalline semiconductive layer and method of fabrication

Claim 3

The method specified in claim 1, wherein the electrostatic bonding is carried out while heating the semiconductive wafer-insulating substrate sandwich to a temperature of from about 300*-350*C while applying a relatively high potential between the members.

Claim 4

The method specified in claim 1, wherein the heated sandwich has the more positive potential terminal applied to the semiconductive wafer side of the sandwich, with the other potential terminal connected to the exposed insulating substrate surface, with the potential being gradually increased to a value of about 1000 volts while the current is maintained below about 5 microamps.

Claim 5

The method specified in claim 1, wherein the insulating substrate is selected from borosilicate glass, spinel, sapphire and quartz.

Claim 6

The method specified in claim 1, wherein the electrochemical etching is carried out in an acidic solution with the electrostatically bonded wafer composite serving as the anode which is closed spaced from a noble metal planar cathode, with the etching proceeding until the highly doped semiconductive wafer is removed as indicated by a significant reduction in the etching current.

Claim 7

The method specified in claim 1, wherein the insulating substrate is a glass having a softening point temperature less than the epitaxial growth temperature.

Claim 8

The method specified in claim 1, wherein the semiconductive material is preferably selected from silicon, germanium and gallium arsenide.

Claim 11

An insulating substrate with a thin epitaxially grown mono-crystalline semiconductive layer on one side thereof, which layer is less than about 2 micrometers thick, the combination of which is useful as a starting substrate in fabricating microelectronic devices, which combination is prepared by the process comprising: a. epitaxially depositing a thin mono-crystalline layer of lightly doped semiconductive material having a high charge mobility on one side of a highly doped silicon wafer; b. electrostatically bonding the silicon wafer to an insulating substrate with the epitaxial silicon mated with thE insulating substrate; c. electrochemically etching the highly doped silicon wafer away to expose the thin epitaxially grown mono-crystalline silicon layer upon the insulating substrate.

Claim 12

An insulating substrate with a thin epitaxially grown mono-crystalline semiconductive layer on one side thereof, which layer is less than about 2 micrometers thick, the combination of which is useful as a starting substrate in fabricating microelectronic devices, which combination is prepared by the process comprising: a. epitaxially depositing a thin mono-crystalline layer of lightly doped semiconductive material having a high charge mobility on one side of a highly doped silicon wafer; b. electrostatically bonding the silicon wafer to an insulating substrate with the epitaxial silicon mated with thE insulating substrate; c. electrochemically etching the highly doped silicon wafer away to expose the thin epitaxially grown mono-crystalline silicon layer upon the insulating substrate.