| 摘要 |
PURPOSE:To prevent etching residue from generating and to suppress loading effect by employing gas which does not contains carbon in a molecule of gas having small fluorine/carbon ratio and to which gas for readily generating fluorine radical is added. CONSTITUTION:Gas which does not contain carbon in a molecule like NF3, contains fluorine and readily generates fluorine radical is added to gas having small fluorine/carbon ratio like CH3F, and this gas is used as etching gas for etching a silicon nitride film on a silicon oxide film. NF3 is added in the amount of approx. 20-30% to increase the fluorine radical of the etchant of silicon nitride which becomes deficient in a plasma and to accelerate the etching velocity without considerably generating ions to becomes SiO2 etchant.
|
