Patent ID: 8273259

Claim:
A method of determining a crossover temperature of a type of organic material in an ashing system, comprising: (a) heating a test sample of a type of organic material at a test temperature in an ashing chamber; (b) flowing ashing gas to a remote plasma generator; (c) generating activated ashing species in said ashing gas using said remote plasma generator; (d) flowing activated ashing gas containing said activated ashing species into said ashing chamber at a test flow rate; (e) ashing a portion of said test sample in said ashing chamber at said test temperature and at said test flow rate using said activated ashing species; (f) measuring an ashing time used to ash said portion of said test sample; (g) measuring an amount of said portion of said test sample that was ashed; and (h) calculating a measured ashing rate corresponding to said test temperature and said test flow rate based on said ashing time used to ash said amount of said portion of said test sample that was ashed; (i) repeating (a) through (h) using at least one test sample of said type of organic material at a plurality of different combinations of test temperatures and test flow rates to calculate a plurality of measured ashing rates; and (j) determining a crossover temperature of said type of organic material in said ashing system by comparing said measured ashing rates, wherein said crossover temperature is characterized in that below said crossover temperature, a decrease in test flow rate results in an increase of measured ashing rate, and above said crossover temperature, an increase in test flow rate results in an increase of measured ashing rate.