Silane etching process

A process for etching a substrate, comprising:

• placing s aid substrate within a plasma reactor chamber;
• admitting into said chamber a processing gas comprising a hydrogen-free fluorocarbon gas and a silane gas in a ratio of flow rates between said fluorocarbon gas and said silane gas lying within a range of between 2 and 5;
• and
• exciting said processing gas within said plasma reactor chamber into a plasma to etch said substrate.

A process of etching an oxide layer, comprising the steps of:

• positioning a substrate having an silicon oxide layer formed thereon within a plasma reactor chamber;
• flowing into said chamber an etching gas comprising silane, silicon tetrafluoride, and a fluorocarbon;
• and
• exciting said etching gas into a plasma to thereby etch said substrate.

A process of optimized etching of an oxide layer, comprising the steps of:

• positioning a series of substrates having an silicon oxide layer formed thereon within a plasma reactor chamber;
• for each of said substrates flowing into said chamber an etching gas formed at least in part by a respective combination of a first flow rate of silane and a second flow rate of a fluorocarbon, said combinations of first and second flow rates differing between said substrates;
• exciting said etching gas into a plasma to thereby etch said each substrate;
• measuring for each of said substrates a respective oxide etching rate and a selectivity of etching silicon oxide over polysilicon;
• determining a preferred range of ratios of first and second flow rates from said measured oxide etching rates and said measured selectivities;
• and
• determining a minimum flow rate of one of said first and second flow rates from said measured selectivities.