IN SITU SELECTIVITY AND THICKNESS MONITORING BASED ON QUADRUPOLE MASS SPECTROSCOPY DURING SELECTIVE SILICON EPITAXY

摘要

This paper reports the first time that a novel~* in situ sensing methodology has been used for thickness monitoring and selectivity loss detection with silicon epitaxy. Ionized molecular hydrogen (H_~2+) signals collected in realtime using a quadrupole mass spectrometer (QMS) sensor were analyzed using modern signal processing techniques. These techniques facilitated the determination of selective film thickness from the time-integrated hydrogen (H_2~+) signal. Silane (SiH_4) was deliberately utilized without a chlorine source to provide both nonselective and selective depositions. For the runs exhibiting a selectivity loss, an inflection point in the H_2~+ signal was consistently observed and used for selectivity-loss detection. The authors expect the methodology presented in this paper to be readily transferable to other process chemistries, including dichlorosilane and disilane-chlorine chemistries. For the selective process runs, a strong correlation (R~2 ≥ 0.97) was demonstrated between selective film thickness and time-integrated H_2~+ signal intensity.