AVS 45th International Symposium
    Plasma Science and Technology Division Monday Sessions
       Session PS2-MoA

Paper PS2-MoA1
Density Measurements of Cf@sub x@ in a GEC Reference Cell by Infrared Absorption

Monday, November 2, 1998, 2:00 pm, Room 318/319/320

Session: Diagnostics I
Presenter: I.C. Abraham, University of Wisconsin, Madison
Authors: I.C. Abraham, University of Wisconsin, Madison
R.C. Woods, University of Wisconsin, Madison
G.A. Hebner, Sandia National Laboratories
Correspondent: Click to Email
Tunable diode laser absorption measurements in the region around 1250 cm@super -1@ were used to determine line integrated CF, CF@sub 2@, and CF@sub 3@ densities in a GEC reference cell, modified for inductively coupled plasma operation. A quartz ring was also installed around the source region to stabilize and confine the plasma and to make the plasma chemistry more like that in industrial etch tools. The experimental layout involved a two pass arrangement, with the path including both the plasma and the space outside the glow region, in a plane just above the wafer surface. Two gas chemistries, C@sub 2@F@sub 6@ and CHF@sub 3@, and two wafer surfaces, bare silicon and blanket photoresist, were investigated. A range of pressure and power conditions, from 5 to 20 mTorr and from 100 to 300 W, respectively, was employed. The concentration of undissociated C@sub 2@F@sub 6@ in the C@sub 2@F@sub 6@ plasma was also measured. An intense spectrum of COF@sub 2@ can be detected in an O@sub 2@ cleaning plasma. The time evolution of CF, CF@sub 2@, and CF@sub 3@ in a C@sub 2@F@sub 6@ plasma was monitored, starting from a clean chamber and continuing for much longer than an etch cycle. The data should provide important benchmarks for models of oxide etching in inductively coupled plasma tools. This project was funded by SEMATECH under contract no. 38010430.