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Proceedings Paper

CMOS degradation effects due to electron beam lithography in smart NEMS fabrication
Author(s): Francesca Campabadal; Sara Ghatnekar-Nilsson; Gemma Rius; Celeste Fleta; Joan Marc Raf; Eduard Figueras; Jaume Esteve
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Paper Abstract

The effects of electron beam lithography for patterning to the nanoscale a polysilicon layer electrically connected to the gate of an NMOS transistor are investigated by means of the analysis of the transistor current-voltage characteristics. In order to evaluate the impact of the electron beam process, two sets of experiments are carried out. The first set consists in the assessment of the effect on the transistor when directly exposing the polysilicon layer and in the second, the impact of the complete electron beam lithography process is investigated using different acceleration voltages. The results obtained show that a severe degradation of the transistor characteristics occurs when processing at high acceleration voltages. The degradation is observed as a threshold voltage shift and a decrease in the transconductance. This behaviour can be related to positive charge trapping in the gate oxide and generation of interface states at the SiO2-Si interface. In addition unbiased room temperature annealing is found to significantly reduce or compensate the induced positive trapped charges. The results suggest that the secondary radiation created by the primary electron beam is damaging the transistor characteristics and can lead to the loss of circuit performance when using electron beam lithography to fabricate nanostructures in already processed CMOS circuits.

Paper Details

Date Published: 1 July 2005
PDF: 8 pages
Proc. SPIE 5836, Smart Sensors, Actuators, and MEMS II, (1 July 2005); doi: 10.1117/12.607926
Show Author Affiliations
Francesca Campabadal, Ctr. Nacional de Microelectronica (Spain)
Sara Ghatnekar-Nilsson, Lund Univ. (Sweden)
Gemma Rius, Ctr. Nacional de Microelectronica (Spain)
Celeste Fleta, Ctr. Nacional de Microelectronica (Spain)
Joan Marc Raf, Ctr. Nacional de Microelectronica (Spain)
Eduard Figueras, Ctr. Nacional de Microelectronica (Spain)
Jaume Esteve, Ctr. Nacional de Microelectronica (Spain)

Published in SPIE Proceedings Vol. 5836:
Smart Sensors, Actuators, and MEMS II
Carles Cane; Jung-Chih Chiao; Fernando Vidal Verdu, Editor(s)

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