Process for thinning silicon with special application to producing silicon on insulator
AssigneeTexas Instruments Incorporated
InventorsRonald K. Smeltzer, Kenneth E. Bean
Life of this patent
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Abstract
This disclosure relates to methods of producing thin layers of silicon as well as thin layers of silicon on insulating substrates such as silicon dioxide or polycrystalline silicon by forming either an n- layer of single crystal silicon over a p++ layer of single crystal silicon or a p- layer of single crystal silicon over an n++ layer of single crystal silicon and then removing either the n++ or p++ single crystal substrate, as the case may be, by utilizing an etch which will only etch the n++ or p++ region and will stop when the n- or p- region, as the case may be, has been reached.
Claims9
A method of forming thin layers of silicon on an insulating substrate which comprises the steps of
- a. providing a silicon member having a first layer of one conductivity type and a second layer of opposite conductivity type and having a resistivity of at least an order of magnitude greater than said first layer and a concentration of less than about 1.5 .times. 10.sup.19 atoms/cc, and
- b. forming a first oxide layer on said second layer,
- c. forming a layer of polycrystalline silicon on said first oxide layer,
- d. etching said first layer with an etching solution consisting of, by weight, 1 part HF, 3 parts NHO.sub.3 and from about 8 to about 12 parts CH.sub.3 COOH to provide etching away of said first layer, said etching automatically stopping at the junction of said first and second layer, and
- e. forming semiconductor devices in the exposed surface of said second layer.
A method of forming thin layers of silicon on an insulating substrate which comprises the steps of
- a. providing a silicon member having a first layer of one conductivity type and a second layer of opposite conductivity type and having a resistivity of at least an order of magnitude greater than said first layer and a concentration of less than about 7 .times. 10.sup.18 atoms/cc, and
- b. forming a first oxide layer over said second layer,
- c. forming a layer of polycrystalline silicon over said first oxide layer,
- d. etching said first layer with an etching solution consisting of, by weight, 1 part HF, 3 parts HNO.sub.3 and from about 8 to about 12 parts CH.sub.3 COOH to provide etching away of said first layer, said etching automatically stopping at the junction of said first and second layer.
Dependencies are inferred from the claim text.