Monitoring the performance of moisture purifiers for process gases.

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Problem Statement

Moisture purifiers are a big aid in keeping moisture levels under control inside a process chamber. They are provided by manufacturers with certain life expectancies, which vary depending on the moisture content of the gas being purified. As a result, it is difficult to determine which gases have a high moisture content and which moisture purifier is becoming saturated.

IRGAS Applicability

The IRGAS Turnkey Gas Analysis Solution is based upon FTIR Spectroscopy, Short and/or Long Path Gas Cells, and Quantitative Software, SPGAS. FTIR spectroscopy is capable of detecting and measuring all infrared active gas and vapor species; not included are the monatomic and homopolar diatomics. A Short or Long Path Gas Cell can be selected with the appropriate pathlength to match the detection limit required. The SPGAS Quantitative Gas Analysis Software provides ppb sensitivity and fast time response, along with internal gas calibrations.

IRGAS System Description

IRGAS-100, consisting of: ABB Bomem WorkIR FTIR with DTGS Detector; Ultra-High Purity N2 Instrument Purge, Heated 4Runner 6.5-meter Gas Cell with Arcoated ZnSe windows; CICP f/5 Optical Couplers; SPGAS and SpectraStream Software.

Solution Achieved

The IRGAS System detected moisture in the low PPB concentration range. The operator was able to follow the moisture content inside the reactor at all times, helping to identify that the source of high moisture was the HCl gas supply and that the HCl moisture purifier was becoming saturated. It can be seen in the table and chart (back side of this page) that the HCl gas stream had high moisture content and that the HCl purifier was reducing the moisture level; but it was yielding poor performance since it was nearly saturated. The IRGAS System provided an incredible amount of savings in time and money by reducing the total downtime of the reactor, the number of wafer samples sent to the lab, and the requirements of specialized, highly trained human resources.