Radio frequency driven direct current electron beam source

A new type of electron beam source employing ion-induced secondary electron emission from cold cathodes is developed for feature charge neutralization during plasma etching. A low pressure (approximately 2 – 20 mTorr) inductively coupled plasma provides ions which impinge on a high secondary electron emission coefficient anodized aluminum (Al2O3) cathode surface. A separate 13.56 MHz radio frequency bias voltage is applied to the cathode, which through the rectifying behavior of the plasma sheath provides the effective DC field for both ion impingement and electron beam acceleration. The electron beam energy spectra are measured at a location 14 cm from the cold cathode using a differentially pumped retarding potential analyzer. The measured electron beam energy spectra is related to the time varying cathode sheath potential provided by the rf bias using collisionless Child-Langmuir rf sheath model with good agreement. The electron beam source is installed on an inductively coupled plasma etcher in an attempt to increase etch pattern transfer fidelity in silicon oxide feature etching. When used during CF4 plasma etching of 0.45 pm diameter via holes, the electron beam is shown to reduce microtrenching as compared to standard ion-assisted etching, as verified with scanning electron microscopic photos. A simple electrostatic model is used to explain the etch profile improvement.

Name thesis:degree_name

Doctor of Philosophy (Ph.D.)

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Electrical and Computer Engineering

Grantor dc:publisher

Colorado State University. Libraries

Year dc:date.issued

2007

Authors dc:creator

• Shaw, Denis M., author
• Collins, George, advisor

• electrical engineering

Statement dc:rights

• Copyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.

Language dc:language.iso

eng, English

Identifier URI

https://doi.org/10.25675/3.026553

OAI identifier oai:identifier

oai:mountainscholar.org:10217/243866