Patent ID: 7109123

Claim:
A method of etching a Si target object, which is a Si substrate or a Si layer formed on a substrate, by using a plasma, said method comprising the steps of: placing the Si target object, coated with a mask, in a processing vessel; supplying a mixed etching gas into the processing vessel, the etching gas containing fluorosulfur or fluorocarbon gas, O 2 gas and fluorosilicon gas; and applying a first RF voltage having a first frequency of 40 MHz or above to a first electrode to couple RF power from the first electrode to a second electrode in the processing vessel, thereby generating a plasma from the etching gases, wherein said method etches parts of the Si substrate or the Si layer to form holes with diameters of about 3 μm or below and depths of about 15 μm or below, or to form grooves with widths of about 3 μm or below and depths of about 15 μm or below; and the mixed etching gas is supplied into the processing vessel with flow rate ratios between those of fluorosulfur or fluorocarbon gas, O 2 gas and fluorosilicon gas being in the range of 1/(0.6 to 0.67)/(0.33 to 2.33).