Coend-Point Detection to Replace CO Detection
Original Publication Date: 1988-Feb-01
Included in the Prior Art Database: 2005-Feb-14
A method has been suggested for enhancing the emission signal when etching semiconductor wafers with low pattern factor chips. The proposal suggests breaking down the CO, given off as a reaction product of the etching process, into CO2 which can then easily be detected in the UV region. In a conventional measurement scheme, the emission of CO is used for determining the extent of the reaction ion etch (RIE). Where the pattern density represents less than 5% of the total wafer surface, the amount of CO evolved is minimal. Some species in the system may have strong absorption bands not within the 2.0 n resolution limits of the monochromator in the measuring equipment, for instance, Ar peaks at 486.5 n which is only 1.5 nm from CO's 485 n peak. This effectively makes the CO and Ar peaks indistinguishable.