| 摘要 |
A method of etching a layer (28) preferably polysilicon on a substrate (14) comprises the steps of placing the substrate on a support (75) in a process chamber (50). The substrate (45) is exposed to an energized process gas comprising a bromine-containing gas preferably HBr, Br2 or CH3Br, a chlorine-containing gas preferably C12 or HC1, an inorganic fluorinated gas preferably NF3, CF4 or SF6, and an oxygen gas optionally diluted with He. The volumetric flow ratio of the gas constituents is selected so that the energized process gas etches regions (28a, b) having different concentrations of dopant in the polysilicon layer (28) at substantially the same etching rate. Optionally, the gas composition is also tailored to simultaneously clean off etch residue from the internal surfaces of a process chamber (50) during etching of the substrate (45). |
