Highly selective oxygen free silicon nitride etch

摘要

A method for selectively etching silicon nitride with respect to silicon oxide is provided. An oxygen free silicon nitride etch gas comprising H2 and either CF4 or CXHYFZ (X≧1, Y≧1, Z≧1) is provided. An RF power is provided to form the etch gas into a plasma, wherein the silicon nitride is exposed to the plasma.

主权项

1. A method for selectively etching silicon nitride with respect to silicon oxide, comprising
providing an oxygen free silicon nitride etch gas comprising H2 and either CF4 or CXHYFZ (X≧1, Y≧1, Z≧1); and providing an RF power to form the etch gas into a plasma, wherein the silicon nitride is exposed to the plasma, wherein the RF power is pulsed, wherein the RF pulsing has a duty cycle between 25% to 75% inclusive, wherein during a phase of the duty cycle when RF power is not provided polymer is deposited and when RF power is provided polymer is removed and the silicon nitride is selectively etched with respect to silicon oxide and wherein the etch selectivity of silicon nitride to silicon oxide is greater than 20:1.