Patent ID: 6933240

Claim:
A method of patterning a layer of silicon, which comprises the following steps: forming a resist mask on the layer of silicon; and etching the layer of silicon selectively with respect to the resist mask using an etching gas containing HBr as a substantially only chemically active etching substance; wherein the step of etching the layer of silicon comprises: etching openings with inclined sidewalls into the layer of silicon; etching the layer of silicon with a plasma-etching process with inductively coupled plasma and, in addition to electric power inductively coupled into the plasma, feeding in electric bias power, and thereby increasing an inclination of the sidewalls by at least one of reducing the inductively coupled electric power and increasing the bias power, such that the openings etched into the layer of silicon have a smaller cross section at a lower end thereof than at an upper end thereof; and: setting the inductively coupled electric power to less than 500 W and/or setting the electric bias power fed in to greater than 50 W; setting a flow rate of HBr during etching of the layer of silicon to between 170 and 210 sccm; and setting a pressure to between 11 and 15 mTorr.