The Use of Optical Emission Spectroscopy to Solve Manufacturing Scaling
Keywords: ICP, OES, Hydrogen, Photovoltaic, HgCdTe
Inductively coupled plasmas (ICP) are the high density plasmas of choice for the processing of HgCdTe and related compounds. Real time examination of the ICP plasmas used to process HgCdTe would be desirable. In this preliminary study, the feasablity of using optical emission spectroscopy (OES) with ICP plasma for the processing of HgCdTe will be examined. We will examine the utility of OES as a real time diagnostic tool for HgCdTe device fabrication. In this preliminary study it has been found that mercury and cadmium can be detected but are dependent on several factors: sample area, material x- value, etch rate, sample temperature, photoresist area, and plasma power. Further we found a strong correlation between the amount of hydrogen detected by OES with samples that have photoresist verses samples without photoresist while processing with hydrogen based plasmas. Hydrogen emission intensity decreases dramatically in samples with photoresist and is converse to the theory that photoresist adds hydrogen to the plasma effluent. It appears that hydrogen is complexing with photoresist and reducing the global amount of hydrogen during a process. Further this phenomena may help explain macroloading issues where additional photoresist area slowed HgCdTe, CdTe, and photoreisist etch rates.