SIMULTANEOUS INSITU MEASUREMENT OF FILM THICKNESS AND TEMPERATURE BY USING MULTIPLE WAVELENGTHS PYROMETRIC INTERFEROMETRY (MWPI)

Film thickness and temperature are two of the most important quantities in semiconductor manufacturing. They play a fundamental role in many standard production techniques like chemical vapor deposition (CVD, LPCVD, PECVD), thermal oxidation and diffusion. They are especially important for more recently developed technologies like molecular beam epitaxy (MBE), metal organic MBE (MOMBE), metal organic CVD (MOCVD), chemical beam epitaxy (CBE), etc. In this paper, an optical in situ method for simultaneous film thickness and temperature measurements-named Multiple Wavelengths Pyrometric Interferometry (MWPI)-is introduced, which is capable of high resolution (up to 0.1 nm for thickness and 0.025 K for temperature) and for real time data evaluation. It can be used for process control as well as in situ quality inspection without time delay or additional handling mechanisms and is suitable for monitoring single films as well as multilayer structures. MWPI is insensitive to vibration, rotation and misalignment of the wafer. Due to its optical basis it is also insensitive to hostile environments like high temperature and/or chemical reactive gases. The physical basis of MWPI is outlined as well as the necessary steps of the evaluation procedure. The simultaneous in situ MWPI film thickness and temperature measurement during the thermal oxidation of Si is presented. The potential technical impact of MWPI on automation, reliability and long term performance of semiconductor manufacturing is discussed.