The effects on the PR ashing rate

uniformity and

H/V

ratio were researched in process of ECCP dry etch model when the gas flow rate and pressure changed. The results show that PR ashing rate and the value of

H/V

would enlarge with the increasing pressure in a certain range. At the same time the uniformity also gradually changed for the better. The ashing rate would first increase and then decrease when the SF

6

flow rate increased. But in this time the value of

H/V

had one contrary law. The PR ashing rate did not change significantly but the value of uniformity became smaller gradually when increased the O

2

flow rate only. When the flow rate of SF

6

and O

2

increased but had one constant low proportion

the etching rate of PR increased first and then decreased

the uniformity and

H/V

ratio had one opposite change.