AVS 45th International Symposium
    Plasma Science and Technology Division Monday Sessions
       Session PS-MoP

Paper PS-MoP5
A Comparison of Oxide Damage in MOS Capacitors in Plasma Cleaning Applications

Monday, November 2, 1998, 5:30 pm, Room Hall A

Session: Plasma Science and Technology Poster Session
Presenter: Q. Wang, Keithley Instruments
Authors: X.M. Tang, College of William and Mary
Q. Wang, Keithley Instruments
D.M. Manos, College of William and Mary
Correspondent: Click to Email
This paper reports a study of a comparison of damage produced by three different sources for photoresist dry-cleaning and removal. The sources include a CW 1kW, 13.6 MHz TCP plasma source, a pulsed TCP source capable of operation at variable frequency and duty cycle, and a source creating a directed stream of energetic (1-10 eV) neutral oxygen atoms. By judicious choice of conditions among these three sources, it is possible to identify the relative contributions to gate oxide damage from ions, electrons, neutrals, and photons. Damage from contamination by deposition of wall materials or other impurities were also included in these studies. Test structures included MOS capacitors consisting of (Al/100 Angstoms of SiO2/Si). Source parameters were varied including pressure, RF power, gas composition, pulse length, and, in the case of neutral stream cleaning, reflected neutral energy and flux. Ion fluxes were estimated from measured plasma parameters and by calorimeter probe methods. Pre-exposure and post-exposure damage levels, under these variations of conditions, were measured using simulataneous high frequency and low frequency C-V and i-V techniques.Results are compared to damage assessments and to models which have previously been reported. Results showed less gate oxide damage in the neutral stream cleaning source. Residue removal and correlative surface damage from impurity effects are assessed by studies using XPS, STM, and Auger spectroscopy. Simulation models are used to correlate the process damage to the plasma discharge parameters.