Nonvolatile memory devices with colloidal, 1.0 nm silicon nanoparticles : principles of operation, fabrication, measurements, and analysis

Silicon nanoparticles are candidate charge trapping and storage elements for future high density, low-voltage nonvolatile memory devices. Most previous works have studied nanoparticles of larger than 5 nm size and exhibited bulk-like trapping characteristics. Technologically viable and competitive future devices, however, will require nanoparticles of sub 3-nm dimensions; a zero-dimensional regime where significant changes to silicon electronic structure occur. In this thesis, the physical processes involved in charge based nonvolatile memory device operation with colloidal mono-disperse 1.0 nm silicon nanoparticles embedded in a metal-oxide-semiconductor (MOS) gate stack is studied for the first time. Spin-coating was used to uniformly deliver the nanoparticle colloid across 150 mm wafers with density control over a thin tunneling oxide. Material characterization via spectroscopic ellipsometry, atomic force microscopy and transmission electron microscopy showed that across wafer sub-monolayer coverage with low-levels of agglomeration was achieved with nanoparticles so positioned possibly due to solvent-mediated self-assembly effects, and that the intrinsic nanoparticle crystallinity was intact after complete device processing. MOS capacitors with Si nanoparticles embedded in their dielectric exhibit strong endurance and well-behaved impedance (capacitance-voltage) characteristics with persistent hysteresis and only 53 mV standard deviation across wafer. Measurements showed that successive dilution of the nanoparticle colloid correlated directly with a decreased measured hysteresis and similarly fabricated zero-nanoparticle control devices exhibited a negligible hysteresis. Systems with 1.0 nm nanoparticles exhibited pure hole storage.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2009

Author dc:creator

• Nayfeh, Osama Munir, 1980-

Advisor dc:contributor.advisor

• Dimitri A. Antoniadis.

• Electrical Engineering and Computer Science.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/47785

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/47785