Preoxidation treatments for very thin oxides grown after silicon exposure to reactive ion etching plasma
Very thin silicon dioxide (<100 A) has been widely used as a tunnel barrier for floating gate electrically erasable read only memory (EEPROM) devices. Small tunneling areas are required in the new EEPROM cell generations and the use of reactive ion etching (RIE) plasma is mandatory in order to define windows with a diameter <1.2 ..mu..m. The tunnel oxide has to be grown in these windows opened in the thicker (150--300 A) gate oxide. The surface damage induced by plasma RIE requires postetch treatments. In this paper, we deal with the effects induced on the oxide characteristics by different postetch treatments. The analysis has been focused on both the recovery of the surface damage and the electrical characteristics of a 95-A-thick tunnel oxide grown after different postetch processes. The oxide degradation under current stress has been evaluated using metal--oxide--semiconductor capacitors. The best preoxidation treatment that we found among our experiments has also been tested on an EEPROM cell. The tunnel oxide degradation, i.e., the cell threshold voltage shift, was found to be very negligible after 10/sup 5/ write--erase cycles.
- Research Organization:
- SGS Microelettronica, Central Research and Development, Via C. Olivetti, 2, 20041 Agrate Brianza, Milan, Italy
- OSTI ID:
- 5677065
- Journal Information:
- J. Vac. Sci. Technol., B; (United States), Vol. 6:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
MEMORY DEVICES
TUNNEL EFFECT
SILICA
PHYSICAL RADIATION EFFECTS
DAMAGE
ETCHING
ION COLLISIONS
OXIDATION
SURFACE TREATMENTS
CHALCOGENIDES
CHEMICAL REACTIONS
COLLISIONS
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
RADIATION EFFECTS
SILICON COMPOUNDS
SILICON OXIDES
SURFACE FINISHING
360605* - Materials- Radiation Effects