Transient phase change effect in phase change memory devices

Phase change random access memory (PCRAM) is a leading contender for next generation nonvolatile memory. The phase change mechanism from high resistance amorphous phase to low resistance crystalline phase in nano-timescale is the most important characteristic of these materials. However, full understanding of the mechanism is still not achieved. Two time parameters were identified from the transient waveform, namely the delay and current recovery times. The link between crystallization kinetics and the transient phase change effect was established by associating nucleation with delay time and growth with current recovery time. Real-time crystallization characterization was achieved. Parasitic capacitance had strong implications on the programming performance of PCRAM. Larger parasitic capacitance results in a larger leakage current, and hence higher applied voltage for RESET operation needs to be applied. The larger parasitic capacitance also results in an increased quenching time due to a longer voltage fall time, which results in a partially crystallized amorphous state. Continuing work is studying the effect of filament formation on phase change. Filament formation is linked to the actual operating performance of the PCRAM device. This link is important in understanding how phase change occurs electrically and whether filament formation has any effect on scaling of PCRAM devices.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical & Computer Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Yeo, Eng Guan

Contributors dc:contributor

• Adesida, Ilesanmi
• Jain, Kanti
• Kim, Kyekyoon
• Bishop, Stephen G.

• phase change memory
• Phase change random access memory (PCRAM)
• transient effect
• time-resolved
• filament

Statement dc:rights

• Copyright 2010 Eng Guan Yeo

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/18640

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/18640