Two stage etching of silicon nitride to form a nitride spacer

A manufacturing method, comprising:

• providing a gate structure over a substrate;
• providing a silicon oxide layer over said gate structure and said substrate;
• providing a silicon nitride layer over said silicon oxide layer;
• applying a main etch, comprising:
• providing a first gas flow including a first ratio of CF4 flow rate to CH2F2 flow rate;
• and
• applying a first quantity of power to said first gas flow to create a first plasma and etching a first portion of said silicon nitride layer with said first plasma at a first process pressure;
• and
• applying an overetch, comprising:
• providing a second gas flow including a second ratio of CF4 flow rate to CH2F2 flow rate greater than said first ratio of CF4 flow rate to CH2F2 flow rate;
• applying a second quantity of power to said second gas flow to create a second plasma, said second quantity of power being greater than said first quantity of power, and etching a second portion of said silicon nitride layer with said second plasma at a second process pressure greater than said first process pressure,
• wherein the etching operations result in formation of silicon nitride spacers.