566
IEEE ELECTRON DEVICE LETTERS,VOL.20,NO.11,NOVEMBER 1999
Rever Short-Channel Effect in Metal-Induced Laterally Crystallized Polysilicon Thin-Film Transistors Man Wong,Gururaj A.Bhat,and Hoi S.Kwok Abstract—A rever short-channel effect,manifested by an increa in the transistor threshold voltage as the channel length is reduced,is obrved in conventional metal-induced laterally crystallized thin-film transistors.Such an effect has not been obrved in regular solid pha crystallized thin-film transistors and can be eliminated by a brief hydrogen plasma treatment.Index Terms—MILC,short channel effect,thin film transistor.
什么房没有门I.I NTRODUCTION
P
OLYCRYSTALLINE silicon thin-film transistors (TFT’s)with high field effect mobility and low leakage current are required for realizing active matrix liquid crystal dis-plays (AMLCD’s)with integrated peripheral circuits and pixel switches.Although solid pha crystallization (SPC)is a rel-atively inexpensive batch process,its processing temperature at around 600
junctions.
Manuscript received March 5,199The authors are with the Departme ing,The Hong Kong University of Sc
Kowloon,Hong Kong.
Publisher Item Identifier S 0741-31担保书模板
WONG et al .:REVERSE SHORT-CHANNEL EFFECT IN MILC TFT’S
567
我的命运
(a)考试小结
(b)(c)
Fig.1.(a)Schematic cross ction of a conventional MILC TFT’s showing the MMGB’s lf-aligned to the S/D metallurgical junctions,(b)the energy barriers near the metallurgical junctions of the source and drain,and (c)the device model at low V d
.
Fig.2.Comparison of the V th scaling behavior of MILC and SPC TFT’s.R-SCE is evident in the MILC TFT’s.Only changes in V th are plotted,with V tho denoting the threshold voltage measured on the transistors with the longest channel lengths.
the much lower device processing temperature makes it un-likely that transient enhanced diffusion is similarly responsible for the obrved R-SCE in MILC TFT’s.
On the other hand,becau of the overlap of the MMGB’s and the metallurgical junction regions at b
oth ends of the channel,the MMGB traps are readily filled with charge carriers supplied by the source and drain.The resulting MMGB energy barriers,the height of which is a function of the trap
densities,武学宗师
Fig.3.Effects of plasma hydrogenation on the I d –V g characteristics of MILC TFT’s,showing reductions in V th and subthreshold
swing.
Fig.4.Comparison of the V th scaling behavior of MILC TFT’s before and after hydrogen plasma passivation.
extend into the channel region.This is depicted in Fig.1(b).Since a
higher
MMGB “transistors,”in ries,to both
sides of the intrinsic MILC transistor.This is depicted in Fig.1(c).
When
.Further
reduction
三头牛of
with
and the subthreshold swing can be obrved
in
the
reduced becau of the
reduction of MMGB traps,the R-SCE is also eliminated after 30min of hydrogenation.
568IEEE ELECTRON DEVICE LETTERS,VOL.20,NO.11,NOVEMBER1999
IV.C ONCLUSION
粗犷的反义词A rever SCE is obrved in conventional MILC TFT’s with the MMGB’s lf-aligned to the source and drain metal-lurgical junction regions.A high potential barrier results from the MMG
B traps,which leads to the obrved rever SCE. It is possible to reduce or eliminate the effect by reducing the density of MMGB traps.This can be accomplished by hydrogen plasma passivation.
R EFERENCES
[1]S.W.Lee and S.K.Joo,“Low temperature poly-Si thinfilm transistor
fabrication by metal-induced lateral crystallization,”IEEE Electron Device Lett.,vol.17,pp.160–163,Apr.1996.
[2]G.A.Bhat,Z.Jin,H.S.Kwok,and M.Wong,“Effects of longitudinal
grain boundaries on the performance of MILC-TFT’s,”IEEE Electron Device Lett.,vol.20,pp.97–99,Feb.1999.[3]Z.Jin,G.A.Bhat,M.Yeung,H.S.Kwok,and M.an Wong,“Nickel
induced crystallization of amorphous silicon thinfilms,”J.Appl.Phys., vol.84,no.1,pp.194–200,July1,1998.
[4]T.H.Ihn,B.I.Lee,T.K.Kim,K.H.Kim,J.W.Shin,P.S Ahn,
W.C.Jeong,and S.K.Joo,“Fabrication of metal-gate poly-Si TFT’s by metal-induced lateral crystallization,”in Dig.Tech.Papers,SID’97, pp.188–191.
[5]G.A.Bhat,M.Wong,Z.Jin,and H.S.Kwok,“Analysis and reduction
of kink effect in MILC-TFT’s,”in Proc.18th Int.Display Rearch Conf.,Seoul,Korea,Sept.28–Oct.1,1998,pp.433–436.
[6]G.A.Bhat,Z.Jin,H.S.Kwok,and M.Wong,“Effect of MIC/MILC
interface on the performance of MILC-TFT’s,”in56th Annu.Device Rearch Conf.,June22–24,1998,pp.110–111.
[7] C.Y.Lu and J.M.Sung,“Rever short-channel effects on threshold
voltage in submicrometer salicide devices,”IEEE Electron Device Lett., vol.10,pp.446–448,Oct.1989.
[8]K.Nishi,H.Matsuhashi,T.Ochiai,M.Kasai,and T.Nishikawa,
洋娃娃的英文“Evidence of channel profile modification due to implantation damage studied by a new method,and its implications to rever short channel effects of nMOSFET’s,”in IEDM Tech.Dig.,1995,pp.993–995.
