Patent ID: 7799691

Claim:
A method comprising: using a plasma for energetic excitation of a reactive etching gas, wherein the reactive etching gas is a constituent of a continuous gas flow, and wherein the plasma is generated with a power between 300 watts and 1200 watts; and anisotropically etching a recess in a silicon substrate with the reactive etching gas, the step of anisotropically etching comprising: deepening the recess in the silicon substrate by at least seventy-five micrometers without interrupting the gas flow of the reactive etching gas, wherein a chemical mixture of the gas flow is substantially constant during the etching of the recess, wherein during the deepening of the recess, a protective layer of silicon dioxide that substantially prevents etching of sidewalls of the recess is produced on the sidewalls, and wherein during etching, the sidewalls remain substantially uniform, wherein a proportion of fluorine-free additional gas in the gas flow is between 30% and 40% by volume, wherein a silicon dioxide etching mask that is different from the protective layer of silicon dioxide produced on the sidewalls is utilized to define a position of the recess.