DocumentCode :
1311856
Title :
Polished TFT´s: surface roughness reduction and its correlation to device performance improvement
Author :
Chan, Alice B Y ; Nguyen, Cuong T. ; Ko, Ping K. ; Chan, Simon T H ; Wong, S. Simon
Author_Institution :
Dept. of Electr. & Electron. Eng., Hong Kong Univ. of Sci. & Technol., Kowloon, Hong Kong
Volume :
44
Issue :
3
fYear :
1997
fDate :
3/1/1997 12:00:00 AM
Firstpage :
455
Lastpage :
463
Abstract :
Chemical-mechanical polishing (CMP) has been applied to the fabrication of n-channel polysilicon thin film transistors (poly-Si TFT´s). Three different polishing conditions are compared: (1) polishing before; (2) polishing after; and (3) both polishing before and after the a-Si recrystallization. Devices with no polishing act as control samples. Experiments consistently reveal that devices with post-anneal polishing exhibit the best performance, Two-fold improvement of drain current is attributed to the smoother active polysilicon surface. The electrical characteristics of a post-anneal polished TFT in terms of field effect mobility μFE, threshold voltage VT, and subthreshold swing S can be further improved if hydrogenation is employed. It is also found that a large decrease in the poly-Si surface roughness leads to higher dielectric breakdown strength and improved short-channel effects. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) results are presented and correlated with electrical results
Keywords :
atomic force microscopy; carrier mobility; electric breakdown; elemental semiconductors; polishing; recrystallisation annealing; silicon; surface topography; surface treatment; thin film transistors; transmission electron microscopy; Si; a-Si recrystallization; active polysilicon surface; atomic force microscopy; chemical-mechanical polishing; device performance improvement; dielectric breakdown strength; drain current; electrical characteristics; field effect mobility; hydrogenation; poly-Si TFT; polysilicon thin film transistors; post-anneal polishing; short-channel effects; subthreshold swing; surface roughness reduction; threshold voltage; transmission electron microscopy; Atomic force microscopy; Chemicals; Electric variables; Fabrication; Iron; Rough surfaces; Surface roughness; Thin film transistors; Threshold voltage; Transmission electron microscopy;
fLanguage :
English
Journal_Title :
Electron Devices, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9383
Type :
jour
DOI :
10.1109/16.556156
Filename :
556156
Link To Document :
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