AVS 52nd International Symposium
    Manufacturing Science and Technology Wednesday Sessions
       Session MS-WeA

Paper MS-WeA3
Temperature and Film Thickness Sensor for Substrates with Multi-layered Thin Films using Optical Fiber type Low-coherence Interferometry

Wednesday, November 2, 2005, 2:40 pm, Room 207

Session: Metrology & Process Control for Advanced Manufacturing
Presenter: T. Ohta, Wakayama University, Japan
Authors: T. Ohta, Wakayama University, Japan
K. Takeda, Nagoya University, Japan
M. Ito, Wakayama University, Japan
C. Koshimizu, Tokyo Electron AT LTD., Japan
Correspondent: Click to Email
The temperature control of substrates is very significant to fabricate much finer and deeper patterns in ultra-fine processing technologies such as plasma processes. So we have developed a temperature sensor for measuring the temperature of each layer of multi-layered substrates, such as Silicon On Insulator (SOI), using a low-coherence interferometer and a Michelson interferometer. This system consisted of Super Luminescent Diodes (SLD:1550nm and 1310nm), a Laser Diode (LD:850nm), a scanning mirror, optical fibers, etc. We measured the temperature of multi-layered substrates of Si/SiO@sub 2@/Si=300µm/500µm/300µm, and as a result, we have found that this system has the resolution of 1 °C. However, this system had difficulty in measuring the temperatures of substrates with thin film layers, which have the optical pass length less than the coherent length of a low-coherent light source. To solve this problem, we have proposed a novel measurement for measuring the thickness of the thin film layer as well as the temperature of substrates. The thickness of the thin film was measured from the ratio of interference intensity of SLDs and the measured value corresponded with theoretical value within 2 micron of thickness. By estimating the film thickness the effect of interference overlapping was reduced, thus improving the error rate of temperature measurement.