AVS 47th International Symposium
    Plasma Science and Technology Friday Sessions
       Session PS-FrM

Paper PS-FrM8
Selective, Anisotropic and Damage-Free SiO@sub 2@ Etching with a Hyperthermal Fluorine Atom Beam

Friday, October 6, 2000, 10:40 am, Room 310

Session: Dielectrics II
Presenter: D.B. Oakes, Physical Sciences Inc.
Authors: D.B. Oakes, Physical Sciences Inc.
W.G. Lawrence, Physical Sciences Inc.
A.H. Gelb, Physical Sciences Inc.
Correspondent: Click to Email
The SIA Roadmap for semiconductors calls for the introduction of neutral beam etching processes in future device generations. Specifically, neutral beam tools are required for silicon dioxide (SiO@sub 2@) etching in the formation of the gate dielectric and contact and via holes. The need for neutral beam tools arises from the combination of space-charge limitations on etch anisotropy and etch induced damage due to the charge content of the beam. The objective of this project is to demonstrate a neutral beam tool that selectively and anisotropically etches SiO@sub 2@. Physical Sciences Inc's FAST@super TM@ plasma technology was used to produce hyperthermal fluorine atom beams with tunable translational energy in the range, 1 to 15 eV. This unique technology accesses an energy range that can facilitate efficient, high rate etching of certain materials without the use of ions that produce damage. The SiO@sub 2@ etching study included the first measurement of the velocity and temperature (20 to 200 C)dependence of atomic fluorine reacting with SiO@sub 2@ in the 1 to 10 eV translational energy range. The data suggests two reaction mechanisms contribute to etching under these conditions. Etching near 1 eV includes a significant thermal component while etching near 10 eV is dominated by a direct process, dependent on the fluorine atom translational energy. Under conditions in which the direct process dominates, anisotropic etching has been demonstrated. Both the selectivity and anisotropy of SiO@sub 2@ etching are dependent on the discharge chemistry. Selectivity ratios of 7:1 for SiO@sub 2@ etching versus both silicon and photoresist were demonstrated. Anisotropies of etching profiles exceeded 20:1. Future work will seek to improve both the selectivity and anisotropy of the process and will address scale-up of the tool for 300 mm wafer etching. Application of the FAST technology to low k dielectric etching based upon organic materials will also be discussed.