Method for calibration of a spectroscopic sensor

摘要

A novel method for calibration of a spectroscopic sensor is provided. In the method, a spectroscopic system is provided. The system includes a measurement cell having one or more walls which at least partially enclose a sample region. The cell further includes a light entry port and a light exit port. The light entry port and the light exit port can be the same port or separate ports. Each of the ports contains a light transmissive window through which a light beam passes along an internal light path inside the measurement cell. The system further has an optical chamber which contains a light source for generating the light beam which passes through the light entry port into the cell, and a detector for measuring the light beam exiting the cell through the light exit port. The light beam passes along an external light path inside the optical chamber. In addition, a gas inlet is connected to the optical chamber. A calibration gas stream is introduced into the optical chamber. The calibration gas stream contains a calibrating gas species and a carrier gas. The calibrating gas species is present in the calibration gas stream in a known concentration. A spectroscopy measurement of the calibration gas stream is then performed. The method finds particular applicability in the calibration of an in-line spectroscopic sensor useful in the detection of molecules of interest in a semiconductor processing tool.