METHOD OF RECOVERY OF ETCHING AGENT FOR SILICON Russian patent published in 1994 - IPC

FIELD: manufacture of silicon devices and integrated circuits. SUBSTANCE: in process of treatment of silicon articles in etching agent composed of mixture of hydrofluoric, nitric and ethanoic acids with volumetric relation 1: (6-17): (1-3) there is observed self-suspension of etching due to accumulation of products of reduction of nitric acid. Losses of fast-consumed ingredients of etching agent in this case do not exceed a few per cent. Mixture of equal volumes of hydrogen peroxide and hydrofluoric acid is added to spent etching agent to recover its starting activity. Optimal value of addition for each starting composition of etching agent is found beforehand experimentally. Conducted chemical reactivation enables consumption of reagents to be reduced markedly and multiplicity factor of use of etching agent to be raised up to 8-10 times. EFFECT: reduced losses of process of treatment of silicon articles with etching agent. 4 dwg