Browsing by Author "LI, CH"

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A SIMPLE AND EFFICIENT PRETREATMENT TECHNOLOGY FOR SELECTIVE TUNGSTEN DEPOSITION IN LOW-PRESSURE CHEMICAL-VAPOR-DEPOSITION REACTOR
(1994-12-01)
CHANG, KM
;
YEH, TH
;
LI, CH
;
WANG, SW
;
電子工程學系及電子研究所
In this paper rye develop a two-step pretreatment method which is a simple but effective cleaning process that can be used to achieve a high deposition rate and excellent interface characteristics, as well as improve the selectivity. In the first step, we use CF4/O-2 mixing gases as a plasma etching system without substrate bias. The removal of damage and contaminants by reactive ion etching (RIE) during contact hole opening can thus be obtained. We consider that the role of oxygen is first to oxidize the polymer residues (i.e., fluorocarbons like CxFy) and the RIE-damaged regions on the silicon surface, and it is then followed with CF4 to remove these oxides. experiments, the plasma modification rate can be controlled at 120 Angstrom/min. Results of the high deposition rate, smooth interface, low selectivity loss and the other improvements are observed. These are superior to those of cases without pretreatment. The second step is that anhydrous HF cleaning was used to remove surface oxide which was formed during the first step. Obviously, this new cleaning technology is very efficient not only for contact hole pretreatment but also for polysilicon materials. This also implies that this technology may have potential for polycide gate applications.
HYDROTHERMAL SYNTHESIS AND CRYSTAL-STRUCTURES OF BA2FE3H(PO4)2(P2O7)2 AND BA2V3H(PO4)2(P2O7)2
(1993-10-01)
DVONCOVA, E
;
LII, KH
;
LI, CH
;
CHEN, TM
;
應用化學系
SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF SODIUM VANADYL(IV) ORTHOPHOSPHATE NAVOPO4
(1991)
LII, KH
;
LI, CH
;
CHEN, TM
;
WANG, SL
;
應用化學系
A new sodium vanadyl(IV) orthophosphate NaVOPO4 has been synthesized by solid-state and hydrothermal method and characterized by single-crystal X-ray diffraction and magnetic susceptibility. It crystallizes in the monoclinic space group P2(1)/c with a = 6.524(1), b = 8.455(4), c = 7.119(1), beta = 115.29(1)-degrees, Z = 4, R = 0.027, and is structurally similar to the triclinic analog LiVOPO4. The structure can be described as close-packed infinite chains of trans-corner-sharing VO6 octahedra with the holes around each chain filled with Na and P atoms. These infinite chains have alternating short and long V - O bonds and are similar to those found in beta-VOPO4. The Na atom has six close oxygen neighbors at distances of 2.268 to 2.511 angstrom.