AVS 46th International Symposium
    Plasma Science and Technology Division Monday Sessions
       Session PS-MoA

Paper PS-MoA10
Oxide Etch Studies in an Inductively Coupled GEC Reference Cell C@sub 2@F@sub 6@ Discharge using Diode Laser Spectroscopy

Monday, October 25, 1999, 5:00 pm, Room 609

Session: Plasma Diagnostics I
Presenter: W.L. Perry, University of New Mexico
Authors: W.L. Perry, University of New Mexico
H.M. Anderson, University of New Mexico
Correspondent: Click to Email
An inductively coupled GEC Reference Cell has been modified to allow etching of patterned oxide wafers under conditions typical of commercial high density plasma reactors. This study reports on the oxide and photoresist characteristics of the tool as a function of reactor source power, bias power, pressure and heated silicon ring temperature. Diode laser absorption spectroscopy (DLAS), optical emission spectroscopy (OES) and Langmuir probe measurements were made at the same time. These measurements are used to construct response surface models of the tool's plasma chemistry behavior versus oxide and photoresist etch rate behavior. The oxide and photoresist etch rate behavior was found to also be profoundly influenced by the temperature of the cooling wafer chuck, so this became a fifth variable in the study. In a C@sub 2@F@sub 6@ discharge, CF and CF@sub 2@ radical concentrations measured by DLAS were also found to be highly dependent on wafer chuck temperature. In a 6 mTorr C@sub 2@F@sub 6@ discharge at 350 W source power and 75 W bias power, typical CF and CF@sub 2@ concentrations were in the range of 1x10@super12@ cm@super -3@ and 3x10@super 13@ cm@super -3@ range. However, if the wafer temperature is allowed to rise toward 100 C, the CF@sub 2@ concentration increases dramatically apparently due to greater photoresist interaction with the plasma. If the wafer is properly cooled, the oxide and photoresist etch rates appear to be dominated by bias power and at low bias power, net deposition of fluorocarbon polymer prevails over net etching. However, with increased wafer temperature, both power and bias exert a strong influence on film etch rates and etching occurs at even zero applied bias power. The data is expected to provide an important database for models of oxide etching in inductively coupled plasma tools. This project was funded by SEMATECH.