Selective etching process silicon

Method for recording a silicon layer disposed on a substrate, comprising: anisotropically recording a first groove in the silicon layer; performing a wet etching selectively anisotropic silicon in the first groove, wet etching to expose silicon surfaces to an aqueous composition comprising comprising: a hydroxide of quaternary onium with aromatic content, and a quaternary phosphonium salt of asymmetric tetraalkyl; wherein the wet etching recording planes (110) and (100) of the silicon layer with approximately equal speeds and preferably with respect to the plane (111) to form an enlarged groove having a side wall in the plane ( 111).