Browsing by Author "Tsai, C"

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Deuterium effect on stress-induced leakage current
(1999-04-01)
Lin, BC
;
Cheng, YC
;
Chin, A
;
Wang, T
;
Tsai, C
We have studied and compared stress-induced leakage current in oxides subjected to H-2 and D-2 annealing. There is not much difference in stress-induced leakage current between thick 70-Angstrom-oxides annealed by these two isotopes. In sharp contrast, an improvement of several-fold in stress-induced leakage current is observed in 27-Angstrom-thick oxides annealed in D-2 ambient compared to that annealed in H-2. The significant improvement in this direct-tunneling oxide may be due to the passivation of intrinsic defects and dangling bonds in a transition SiOx layer.
Electrical characterization of Al2O3 on Si from thermally oxidized AlAs and Al
(1999-05-01)
Liao, CC
;
Chin, A
;
Tsai, C
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The scaling limit for VLSI gate oxide (SiO2) is 15-20 Angstrom that is determined by the large direct-tunneling leakage current. Further scaling to improve device performance can be obtained using a higher dielectric constant material. We have studied the Al2O3 to use as an alternative gate dielectric. To ensure good quality, Al2O3 is thermally oxidized from MBE-grown AlAs or Al on Si-substrates. Experimental results indicate that the leakage current from oxidized AlAs is larger than that from directly oxidized Al, which may be due to the weak As2O3 inside Al2O3. The leakage current of a 53 Angstrom Al2O3 is already lower than that of SiO2 with an equivalent oxide thickness of 21 Angstrom. (C) 1999 Published by Elsevier Science B.V. All rights reserved.
Improved electrical characteristics of CoSi2 using HF-vapor pretreatment
(1999-05-01)
Wu, YH
;
Chen, WJ
;
Chang, SL
;
Chin, A
;
Gwo, S
We have developed a simple process to form epitaxial CoSi2 for shallow junction. Prior to metal deposition, the patterned wafers were treated with HF-vapor passivation. As observed by scanning tunneling microscopy (STM), this HF, treatment drastically improves the native oxide-induced sur face roughness. The epitaxial behavior was confirmed by cross-sectional transmission electron microscopy (TEM), Decreased sheet resistance and leakage current, and improved thermal stability are displayed by the HF treated samples, which is consistent with STM and TEM results.
Improved electrical characteristics of CoSi2 using HF-vapor pretreatment
(1999-05-01)
Wu, YH
;
Chen, WJ
;
Chang, SL
;
Chin, A
;
Gwo, S
We have developed a simple process to form epitaxial CoSi2 for shallow junction. Prior to metal deposition, the patterned wafers were treated with HF-vapor passivation. As observed by scanning tunneling microscopy (STM), this HF, treatment drastically improves the native oxide-induced sur face roughness. The epitaxial behavior was confirmed by cross-sectional transmission electron microscopy (TEM), Decreased sheet resistance and leakage current, and improved thermal stability are displayed by the HF treated samples, which is consistent with STM and TEM results.
Improved electrical characteristics of CoSi2 using HF-vapor pretreatment
(1999-07-01)
Wu, YH
;
Chen, WJ
;
Chang, SL
;
Chin, A
;
Gwo, S
We have developed a simple process to form epitaxial CoSi2 for shallow junction. Prior to metal deposition, the patterned wafers were treated with HF-vapor passivation. As observed hy scanning tunneling microscopy (STM), this HF treatment drastically improves the native oxide-induced surface roughness. The epitaxial behavior was confirmed by cross-sectional transmission electron microscopy (TEM). Decreased sheet resistance and leakage current, and improved thermal stability are displayed by the HF treated samples, which is consistent with STM and TEM results.
In0.52Al0.48As/InAs/InxAl1-xAs pseudomorphic HEMT's on InP
(1997-04-01)
Chin, A
;
Liao, CC
;
Tsai, C
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The dc and microwave performance of an InAs channel HEMT is reported. Room-temperature electron mobility as high as 20 200 cm(2)/Vs is measured, with a high carrier concentration of 2.7x10(12) cm(-2). DC extrinsic transconductance of 714 mS/mm is measured and a unity-current-gain cut-off frequency of 50 GHz is obtained for a 1.1-mu m gate length HEMT. The success of achieving superior Hall mobility and device performance is strongly dependent on the InxAl1-xAs buffer layer design that changes the lattice constant from lattice-matched In0.52Al0.48As to In0.75Al0.25As. The multiple In0.52Al0.48As/InAs monolayer superlattices buffer achieves the best performance as compared to the step-graded InxAl1-xAs and the uniform In0.75Al0.25As buffer.
Mobility and oxide breakdown behavior in ultra-this oxide with atomically smooth interface
(1998)
Cheng, YC
;
Chen, WJ
;
Lin, BC
;
Tsai, C
;
Chin, A
The device performance made by thin gate oxide is related to the oxide thickness uniformity and the interface smoothness. Unfortunately, native oxide roughens the initial surface before thermal oxidation. in this paper, we have designed a leak-tight low-pressure N2O oxidation system, and the native oxide is desorbed in-situ under H-2 environment, Atomically smooth oxide and Si interface of ultra-thill oxides (11-38 Angstrom) were achieved as observed by high-resolutional TEM. Significant mobility enhancement over large gate field is obtained by reducing interface roughness scattering. The oxide reliability is also improved by this smoother interface between Si and oxide.
The effect of native oxide on epitaxial SiGe from deposited amorphous Ge on Si
(1999-01-25)
Wu, YH
;
Chen, WJ
;
Chin, A
;
Tsai, C
;
電子工程學系及電子研究所
We have investigated the effect of native oxide on the epitaxial SiGe from deposited amorphous Ge on Si. Instead of epitaxial growth by molecular beam epitaxy or ultrahigh-vacuum chemical vapor deposition, the SiGe layer is formed by this simple process followed by an annealing step. As observed by transmission electron microscopy, the suppression of native oxide plays an important role to achieve epitaxial SiGe. The SiGe quality degrades with increasing native oxide thickness and becomes polycrystalline with a similar to 20 Angstrom interfacial native oxide. On the other hand, single crystalline SiGe can be routinely formed from a HF-vapor treated Si surface. (C) 1999 American Institute of Physics. [S0003-6951(99)04504-0].
The leakage current effect of thin gate oxides (2.4-2.7 nm) with in situ native oxide desorption
(1999-06-01)
Lai, JM
;
Chieng, WH
;
Lin, BC
;
Chin, A
;
Tsai, C
An intrinsic defect may exist in thin gate oxides. Such a defect can increase the leakage current in a manner similar to stress-induced leakage current. In this paper, we have shown that the effect of this intrinsic defect can be greatly reduced by in situ removal of the native oxide followed by growing a high-quality thermal oxide. By using such in situ cleaning, ultrathin oxides can be prepared with atomically smooth interfaces, good thickness uniformity, and reduced leakage currents. (C) 1999 The Electrochemical Society. All rights reserved.
Thin oxides with in situ native oxide removal
(1997-09-01)
Chin, A
;
Chen, WJ
;
Chang, T
;
Kao, RH
;
Lin, BC
We have studied the inversion layer mobility of n-MOSFET's with thin-gate oxide of 20 to 70 Angstrom. Direct relationship of electron mobility to oxide/channel interface roughness was obtained from measured mobility of MOSFET's and high-resolution TEM. By using a low-pressure oxidation process with native oxide removed in situ prior to oxidation, atomically smooth interface of oxide/channel was observed by high-resolution TEM for oxide thicknesses of 11 and 38 Angstrom. The roughness increased to one to two monolayers of Si in a 55-Angstrom oxide. Significant mobility improvement was obtained from these oxides with smoother interface than that from conventional furnace oxidation. Mobility reduction with decreasing oxide thickness was observed in the 20- and 35-Angstrom oxide, with the same atomically smooth oxide/channel interface. This may be due to the remote Coulomb scattering from gate electrode or the gate field variation from poly-gate/oxide interface roughness.
Thin oxides with in situ native oxide removal
(1997-09-01)
Chin, A
;
Chen, WJ
;
Chang, T
;
Kao, RH
;
Lin, BC
We have studied the inversion layer mobility of n-MOSFET's with thin-gate oxide of 20 to 70 Angstrom. Direct relationship of electron mobility to oxide/channel interface roughness was obtained from measured mobility of MOSFET's and high-resolution TEM. By using a low-pressure oxidation process with native oxide removed in situ prior to oxidation, atomically smooth interface of oxide/channel was observed by high-resolution TEM for oxide thicknesses of 11 and 38 Angstrom. The roughness increased to one to two monolayers of Si in a 55-Angstrom oxide. Significant mobility improvement was obtained from these oxides with smoother interface than that from conventional furnace oxidation. Mobility reduction with decreasing oxide thickness was observed in the 20- and 35-Angstrom oxide, with the same atomically smooth oxide/channel interface. This may be due to the remote Coulomb scattering from gate electrode or the gate field variation from poly-gate/oxide interface roughness.
Ultra-thin oxide with atomically smooth interfaces
(1995)
Chin, A
;
Chen, WJ
;
Kao, RH
;
Lin, BC
;
Chang, T
Native oxide is an important issue for ultra-thin oxide, which is strongly related to the gate oxide integrity such as Q(BD), interface scattering, etc. We have designed a leak-tight low-pressure oxidation system to desorb the native oxide in-situ. Atomically flat interfaces between oxide and Si are obtained for oxide thicknesses of 11 and 38 Angstrom. Because of the smooth interface and good thickness uniformity of oxide, both high-field electron mobility and oxide breakdown behavior are much improved.
Ultrathin N2O-oxide with atomically flat interfaces
(1997-05-01)
Chin, A
;
Chen, WJ
;
Lin, BC
;
Kao, JH
;
Tsai, C
Silicon oxide has been grown in a low pressure furnace using N2O. An atomically fiat SiO2 (N2O)/Si interface, as determined by high resolution transmission electron microscopy, has been achieved by desorbing the native oxide in situ for oxide thicknesses 11 to 38 Angstrom. The thickness variation of a 20 Angstrom N2O-oxide, grown on a 4 in. substrate <1 Angstrom. The excellent uniformity is attributed to the increased mean-free path of N2O molecules in the low pressure environment. Since only one Si plane was distorted beneath the N2O-oxide/Si interface, this suggests that thermal stress is not the limiting factor for obtaining an atomically smooth interface.
Ultrathin N2O-oxide with atomically flat interfaces
(1997-05-01)
Chin, A
;
Chen, WJ
;
Lin, BC
;
Kao, JH
;
Tsai, C
Silicon oxide has been grown in a low pressure furnace using N2O. An atomically fiat SiO2 (N2O)/Si interface, as determined by high resolution transmission electron microscopy, has been achieved by desorbing the native oxide in situ for oxide thicknesses 11 to 38 Angstrom. The thickness variation of a 20 Angstrom N2O-oxide, grown on a 4 in. substrate <1 Angstrom. The excellent uniformity is attributed to the increased mean-free path of N2O molecules in the low pressure environment. Since only one Si plane was distorted beneath the N2O-oxide/Si interface, this suggests that thermal stress is not the limiting factor for obtaining an atomically smooth interface.