US 5,632,855 AGranted

Thermal oxide etch technique

AssigneeAdvanced Micro Devices, Inc.

InventorsStephen A. Jones, Shyam G. Garg

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Abstract

A process is provided for etching thermally grown oxide. The process involves various steps and specific etch processing parameters used within a parallel electrode reactor. There are pre-stabilizing steps, followed by an etch step, which is then followed by post-stabilizing steps. The post-stabilizing steps may further include a particle removal or byproduct flush step in addition to the post-stabilizing steps. The process parameters are chosen to remove thermal oxide within contact regions at a uniform rate. The resulting thermal oxide is substantially uniform with less than 3.0% variance in thickness across the contact regions and across like areas of the entire wafer surface. The unique combination of pre-stabilize, etch, post-stabilize steps and process parameters chosen for each step thereby provides an improved etch uniformity of thermal oxide films within fine-line areas.

Claims17

Dependent claims

A method for removing thermally grown oxide, comprising the steps of:

providing a silicon-based material having thermally grown oxide formed thereon;
placing the oxide-coated silicon-based material in a gap between a pair of electrodes arranged within a parallel electrode reactor;
pressurizing an ambient gas mixture of Ar, CF.sub.4 and CHF.sub.3 inserted into said reactor to a pressure less than 300 mTorr while maintaining said gap to less than 1.0 cm for a first time period, said first time period being a first pre-stabilizing step;
inserting helium across said silicon-based material to a pressure approximately 12.0 Torr for a second time period, said second time period being a second pre-stabilizing step;
applying approximately 250 watts to one of said electrodes for a third time period, while maintaining the parameters of said first and second pre-stabilizing steps, to remove said thermally grown oxide;
increasing the pressure within said reactor to approximately 3000 mTorr while terminating the flow rates of CF.sub.4 and CHF.sub.3 for a fourth time period, said fourth time period being a first post-stabilizing step;
increasing said gap while maintaining the parameters of said first post-stabilizing step for a fifth time period, said fifth time period being a second post-stabilizing step;
and
expelling additional etch products from said reactor while maintaining the parameters of said second post-stabilizing step for a sixth time period, said sixth time period being a particle-removal step.

6 more elements

Dependencies are inferred from the claim text.