EXPRESS: Nondispersive Ultraviolet–Visible Gas Analyzer for Monitoring Molybdenum Chloride and Oxychloride Precursors During Vapor Deposition Processes

Non-dispersive ultraviolet-visible (UV-Vis) gas analyzer designs were evaluated for monitoring molybdenum-containing chloride and oxychloride precursor delivery during microelectronics vapor deposition processes. The performances of three analyzer designs, which differed only in the bandpass filter employed for wavelength selection, were compared for measuring the partial pressure of molybdenum pentachloride, molybdenum oxytetrachloride, and molybdenum dioxydichloride. The analyzer's optical response of a 369 nm center wavelength filter for molybdenum pentachloride was determined by measuring the molybdenum pentachloride absorbance as a function of vapor molar density. The calibrated analyzer was transferred to a process line on a deposition chamber and used to measure the molybdenum pentachloride partial pressure during delivery in a flowing carrier gas. The molybdenum pentachloride minimum detectable density was determined to be 1 × 10