Date of Award
Master of Science in Engineering Management - (M.S.)
Industrial and Manufacturing Engineering
George Hanna Abdou
Robert Boris Marcus
The present trend in the semiconductor industry is towards submicron devices. An inevitable process technique in achieving this is by reactive ion etching of the polysilicon gate. During RIE, the gate oxide may get damaged due to several causes. One of the main causes of the damage is the non-uniformity of the plasma. It is reported that these plasma inconsistencies are mainly due to electrode design and that they create spatial plasma potential fluctuation. These fluctuations are reported to be in the range of 10-20 Volts. By providing an in-situ monitoring of the wafers, the reliability of the device could be established. The purpose of this sensor is to detect the spatial fluctuations. It works on the principle of electrostatic forces. It is made of polysilicon (gate material) and consists of two cantilevers separated by 2μm constituting a parallel plate capacitor configuration. The design, simulation and fabrication of the sensor was carried out. The test results demonstrated that sensors with beam lengths 150μm, 200μm and 250μm deflect by 2μm at externally applied voltages of 65, 56, and 50 volts respectively. Optimized beam dimensions that would deflect by 1.2µm at an applied voltage of 20 Volts is estimated from the experimental results and has the following dimensions: length of the cantilever = 200μm, width = 2μm, the thickness = 1.6μm, and the space between the cantilevers is = 1.2μm.
Ganesh, Subramanian, "Design, simulation and fabrication of a mems in-situ contactless sensor to detect plasma induced damage during reactive ion etching" (1997). Theses. 1004.