| CPC C23C 16/045 (2013.01) [C23C 16/345 (2013.01); C23C 16/56 (2013.01)] | 20 Claims |

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1. A method of forming a pattern structure including a silicon nitride, the method comprising:
a step of providing, into a substrate processing apparatus, a substrate having one surface on which a pattern structure including a recess region in which an opening periphery portion and a bottom portion are made of a first silicon nitride is formed;
step (a1) a deposition step of depositing a second silicon nitride on the first silicon nitride so that a deposition thickness on the bottom portion has a smaller value than a deposition thickness on the opening periphery portion;
step (b1) an etching step of etching the second silicon nitride on the opening periphery portion by the thickness deposited in step (a1), etching and removing the second silicon nitride deposited in step (a1) on the bottom portion, and etching the first silicon nitride provided below the second silicon nitride; and
a step of performing steps (a1) and (b1) in one cycle n times (n is a natural number equal to or larger than 1) until the first silicon nitride constituting the bottom portion is removed.
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