METHOD OF CLEANING SURFACES OF SAPPHIRE SUBSTRATES Russian patent published in 2010 - IPC H01L21/46 

FIELD: chemistry.

SUBSTANCE: method of cleaning the surface of sapphire substrates after undergoing final smoothing with silica sol solutions involves putting the substrates into metallic holders, ultrasonic cleaning in two steps, at the first step with a 10% solution of vetrolin in deionised water at pH=12-13 and temperature 68-72°C for not less than 8 minutes, and at the second step in deionised water at temperature 68-72°C for not less than 1 minute. The substrates are then taken from the metallic holders into fluoroplastic holders, washed with deionised water, after which cleaning is carried out in two steps in acid etchants. At the first step the substrates are washed in a 12-25% solution of highly pure hydrofluoric acid in deionised water at 18÷22°C for not less than 1 minute. The acid solution is washed off in a current of deionised water. The second cleaning step in acid etchants is carried out in a fluoroplastic bath in concentrated highly pure orthophosphoric acid at 148-152°C for not less than 7 minutes. Further, the acid is washed off with a current of deionised water, after which the substrate is washed.

EFFECT: obtaining a clean hydrophilic surface of substrates without contaminants.

2 cl