AVS 50th International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS-WeP

Paper PS-WeP1
Experiemental Study of Real-Time Feedback Control of Ion Energy and Ion flux in Poly-Si Etch Process Using High Density Cl@sub 2@ Plasmas

Wednesday, November 5, 2003, 11:00 am, Room Hall A-C

Session: Poster Session
Presenter: K.C. Leou, National Tsing Hua University, ROC
Authors: K.C. Leou, National Tsing Hua University, ROC
C.H. Chang, National Tsing Hua University, ROC
C. Lin, National Tsing Hua University, ROC
Correspondent: Click to Email
In this study, we have demonstrated experimentally the real-time closed-loop control of both ion density and ion energy in a chlorine inductively coupled plasma etcher. To measure positive ion density, the trace rare gases-optical emission spectroscopy (TRG-OES) is used to measure the chlorine positive ion density. An rf voltage probe is adopted to measure the RMS rf voltage on the electrostatic chuck which is linearly dependent on sheath voltage. One actuator is a 13.56 MHz rf generator to drive the inductive coil seated on a ceramic window. The second actuator is also a 13.56 MHz rf generator to power the electrostatic chuck. The closed-loop controller is designed to compensates process drift, process disturbance, and pilot wafer effect and to minimize steady state error of plasma parameters. This controller has been used to control the etch process of unpatterned polysilicon. The experimental results showed that the closed-loop control had a better repeatability of plasma parameters compared with open-loop control. The closed-loop control can eliminate the process disturbance resulting from reflected power. In addition, experimental results also demonstrated that closed-loop control has a better reproducibility in etch rate as compared with open-loop control. Experiment results on SiO@sub 2@ etch show that real-time feedback control of both ion energy and flux also enhance the process stability of etch selectivity (Poly-Si to Oxide) in addition to the etch rate of poly-Si. @FootnoteText@ Work supported by the NSC of the R.O.C., grant No. NSC 90-2622-E-007-004.