| 摘要 |
<p>An in-line detector system (200) and method for real-time detection of impurity concentration in a flowing gas stream. In a specific aspect, the system may comprise an in-line monitoring system for determining the calibrated concentration of an impurity species in a flowing gas stream, in a low concentration range below a predetermined concentration value, and in a high concentration range above said predetermined concentration value. A sensor coupling (214) interconnects a purifier (208) with sensing means (412) for monitoring the impurity level of the gas stream. A switcher valve (230) is interposed in a flow loop between the purifier (208) and the sensor (412) for selectively directing purified or unpurified gas from the gas stream to the impurity sensing means. The system may utilize hygrometric sensors in the case of water as a critical impurity, or surface acoustical wave (SAW) devices coated with suitable impurity-affinity coatings. The system has particular utility in monitoring low impurity concentration levels (e.g., from about 0.1 ppm to about 100 ppm) in gas streams employed in vapor-phase processes such as chemical vapor deposition in the manufacture of semiconductor devices.</p> |
