Browsing by Author "Kao, RH"

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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.