Patent ID: 6488863
Filing Date: 2002-12-03
Classification: H01L

Abstract:
A method of plasma-etching a target substrate in a plasma etching apparatus, the target substrate having a surface with a first layer consisting essentially of silicon nitride and a second layer consisting essentially of silicon or silicon oxide, the method comprising the steps of:a) setting parameters of the etching apparatus; b) placing the target substrate in a process chamber of the etching apparatus; c) supplying a process gas into the process chamber, while exhausting the process chamber; d) turning the process gas into plasma by electric discharge, while keeping the process chamber at a first pressure; and e) etching the first layer preferentially to the second layer with the plasma, wherein, in order to effect a balance between etching selectivity of the first layer relative to the second layer, and etching planar uniformity, defined by a difference between sizes to be processed at a center and a periphery of the target substrate, the step a) of setting parameters of the etching apparatus is performed in accordance with the following (i) to (iv): (i) the first pressure is set at a value of from 50 mTorr to 100 mTorr, (ii) the process gas comprises a mixture gas of CH2F2 gas and O2 gas mixed at a first mixture ratio (CH2F2/O2) of higher than 0.2 in volume ratio, (iii) the etching selectivity is set at a value 3.5 or more and the planar uniformity is set at a value within Â±7.0%, and (iv) the first pressure and the first mixture ratio are used as parameters of said parameters for the selectivity and the planar uniformity, by which the etching apparatus is set, and the step of setting parameters of the etching apparatus comprises a step of setting the first pressure higher and the first mixture ratio lower, as the set value of the selectivity is higher, and a step of setting the first pressure higher and the first mixture ratio higher, as the set value of the planar uniformity is more strict.