Patent ID: 8962492
Filing Date: 2015-02-24
Classification: H01L

Abstract:
1. A method to thin an initial silicon-on-insulator (SOI) substrate that includes a silicon oxide layer buried between a silicon carrier substrate and a silicon surface layer, the method comprising: conducting a thermal oxidation treatment of the initial SOI substrate to cause oxidation of part of the silicon surface layer and form a thermal oxide thereon; conducting a first cycle that comprises etching followed directly by cleaning of the silicon surface layer after the thermal oxidation treatment, wherein the etching of the first cycle comprises fully removing the thermal oxide from the silicon surface layer to thin the silicon surface layer and lift off all unstable parts of the initial substrate at edges thereof to form a thinned substrate; and conducting a second cycle, directly after the cleaning of the first cycle, the second cycle comprising etching followed directly by cleaning of the silicon surface layer, wherein the etching of the second cycle comprises removing from the surface of the thinned substrate, polluting particles formed during the first etching cycle and which have deposited thereupon, in order to obtain a final SOI substrate having a thinned surface layer which forms an active layer of the SOI substrate, wherein each of the cleaning of the first cycle and the cleaning of the second cycle comprises immersing the SOI substrate in water, then in a first solution comprising ammonium hydroxide, hydrogen peroxide and deionized water, and then in a second solution comprising hydrochloric acid, hydrogen peroxide and deionized water.