Abstract
A low-temperature, uniform, high-density plasma is produced by applying ultrahigh-frequency (UHF) power through a spokewise antenna. The plasma is uniform within ±5% over a diameter of 30cm. No magnetic field is needed to maintain the high-density plasma. Consequently, the plasma source is fairly simple and lightweight. This plasma creates a high electron density and a low degree of dissociation of the feed gas at the same time because the electron energy distribution function is not Maxwellian (bi-Maxwellian distributions). The plasma characteristics are highly suitable for the precise etching of Al and gate electrodes. Additionally, by the combination of bi-Maxwellian electron energy distribution in the UHF plasma and new fluorocarbon gas chemistries (C2F4, CF3I), selective radical generations of CF2 and CF3 could be realized for high-aspect contact hole patterning of SiO2. A high ion density and a high-energy tail in the electron energy distribution can also be maintained over a wide range of pressure (from 3 to 20mTorr), whereas in conventional inductively coupled plasma (ICP: 13.56 MHz), the ion density and number of high-energy electrons are drastically reduced when the gas pressure is increased. This indicates that the ionization in the UHF plasma does not depend significantly on gas pressures between 3 and 20mTorr because the discharge frequency is higher than the frequency of electron collisions in the plasma. As a result, the UHF plasma provides a process window for high-performance etching that is wider than the one provided by an ICP.
Original language | English |
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Pages (from-to) | 1583-1596 |
Number of pages | 14 |
Journal | Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers |
Volume | 39 |
Issue number | 4 A |
DOIs | |
Publication status | Published - 2000 |
Externally published | Yes |
Keywords
- Discharge frequency
- Electron energy distribution function
- Inductively coupled plasma
- Plasma etching
- Ultrahigh-frequency plasma
ASJC Scopus subject areas
- Engineering(all)
- Physics and Astronomy(all)