Browsing by Author "Liou, BW"

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Applications of total reflection X-ray fluorescence to analysis of VLSI micro contamination
(1999-05-01)
Liou, BW
;
Lee, CL
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper demonstrates the microcontamination analysis on wafers after they went through the conventional ULSI processing steps, by using the vapor phase decomposition/total reflection X-ray fluorescence (VPD/TXRF) technique. It was found that the wafer location in the holding cassette during the chemical cleaning step affected the cleanness of the wafer, and the class 1 environment was not enough to keep the wafer to a contamination level below 5 x 10(9) atoms/cm(2) for three days storing, The breakdown characteristic of a gate oxide was shown to be closely related with the cleanness of the surface of the oxide.
Characteristics of high breakdown voltage Schottky barrier diodes using p(+)-polycrystalline-silicon diffused-guard-ring
(2000-04-01)
Liou, BW
;
Lee, CL
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A new structure of Schottky diode using the p(+)-polycrystalline silicon (polysilicon) diffused-guard-ring is proposed. For 950 degrees C with 30 min annealing condition, the diode gives a nearly ideal J-V characteristic with a high reverse breakdown voltage (148 V) and a low reverse leakage current density (8.4 mu A/cm(2)). The guard-ring structure prevents the premature breakdown; the polysilicon layer prevents the surface leakage. It was also found that the more the driving time of furnace, the higher the breakdown voltage of the Schottky diode. The breakdown characteristic of a Schottky diode was shown to be closely related with the diffusion length of the boron ions being inside the Si wafer. The electrical characteristics of the p(+)-polysilicon diffused-guard-ring Schottky device was compared with those of the conventional diffused-guard-ring sample. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.
Hydrogen and oxygen plasma effects on polycrystalline silicon thin films of various thicknesses
(1997-06-01)
Liou, BW
;
Lee, CL
;
Lei, TF
;
Wu, YH
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電子工程學系及電子研究所
This work studied the hydrogen and oxygen plasma effects on the resistivity, effective free carrier concentration, and mobility of As+- and BF2+-doped polycrystalline silicon (polysilicon) thin films of various thicknesses. It was found that the resistivity of a polysilicon thin film increased with the decrease of the thickness of the film. This was mainly due to the decrease of effective carrier concentration and the mobility through the decrease of the grain size since the thickness limited regrowth of the film. The hydrogen and/or oxygen plasma treatment decreased the effective carrier concentration of the film through the neutralization of boron and arsenic ions. This effect was more evident for the thinner (< 60 nm) film. The plasma treatment also decreased the mobility of the film, unless the thickness of the film was thinner than 50 nm, for which, the mobility instead increased since the plasma passivation effect became dominant.
Plasma effects of fluorine implantation on As+-doped polycrystalline silicon thin films of various thicknesses
(2000-12-08)
Liou, BW
;
Lee, CL
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This work studied plasma effects on the resistivity, effective free carrier concentration, and mobility of As (+)-doped, F-implanted polycrystalline silicon (polysilicon) thin films of various thicknesses. It was found that the resistivity of the polysilicon thin film increases with the decrease of the thickness of the film. This is mainly due to the decrease of the effective carrier concentration and mobility through the decrease of the grain size which is limited by the thickness of the him. Hydrogen and NH3 plasma treatments decrease the effective carrier concentration of the film through neutralization of As ions. This effect is more evident for the thinner films (< 60 nm). The mobility of the high F-dose sample (3 x 10(15) cm(-2)) is larger than that of the low F-dose samples (1 x 10(15) cm(-2)), because the implanted F atoms passivate trapping states of the polysilicon thin film. Through the use of the F implantation passivation and the NH3-plasma treatment, a polysilicon film of a high mobility can be obtained. (C) 2000 Published by Elsevier Science B.V. All rights reserved.
Variations of X-ray spectrum in total reflection X-ray fluorescence (TXRF) analysis with respect to Si wafer crystal orientation for different incident angles
(1999-12-01)
Liou, BW
;
Lee, CL
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This work studies the W-L-beta, Si-K-alpha and spurious radiations, which occur in the total reflection X-ray fluorescence (TXRF) analysis technique, Measurements at different azimuth angles were studied with respect to; the wafer orientation under different incident glancing angles of the X-ray beam on the surface of a bare Si-wafer, an oxide film, and an amorphous silicon film. It was found that both the W-LB radiation and the spurious radiation signals have a four fold periodic;variation with respect to the wafer orientation while the Si-K-alpha radiation signal does not have such a variation. For the oxide wafers, this periodic variation for the W-L-beta radiation and the spurious radiation signals becomes less and eventually disappears as the thickness of the oxide increases to 42 nm. For the amorphous silicon wafer, the above periodic variation phenomenon does not exist. This reveals that the W-L-beta and the:spurious radiation signals are mainly due to the interaction of incident X-ray evanescent radiation with the silicon crystal lattice. To reduce spurious signals in the TXRF analysis, a measurement at azimuth angle along the [100] directions of 45, 135, 225 or 315 degrees to the oxide-covered surface is suggested.