Browsing by Author "WANG, PW"

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A NEW PORTRAYAL OF OXIDATION OF UNDOPED POLYCRYSTALLINE SILICON FILMS IN A SHORT-DURATION
(1994-01-01)
WANG, PW
;
SU, HP
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TSAI, MJ
;
HONG, G
;
FENG, MS
Both polysilicon films low-pressure chemical-vapor-deposited (LPCVD) at 625 degrees C and amorphous films deposited at 550 degrees C with subsequent annealing at 600 degrees C for 24 h to form polysilicon films were used to grow polyoxides at 850 degrees C in wet or dry oxygen. Detailed high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) studies have been performed to determine the microstructures of the polyoxide/polysilicon interface and the crystallinity of the polysilicon films. It is found that the oxidation phenomena of these two films are very different. For the recrystallized amorphous silicon specimens, the polyoxide/polysilicon interface is very flat because of the poor crystallinity and low-angle grain boundaries between the grains. On the other hand, the polyoxide/polysilicon interface is rough for the as-deposited polysilicon samples due to the distinct grain characteristics and the high-angle grain boundaries between these grains.
EFFECTS OF POSTETCHING TREATMENTS ON ELECTRICAL CHARACTERISTICS OF THERMAL OXIDES ON REACTIVE-ION-ETCHED SILICON SUBSTRATES
(1995-09-01)
CHENG, HC
;
UENG, SY
;
WANG, PW
;
KANG, TK
;
CHAO, TS
Thin oxides thermally grown on the reactive-ion-etched (RIE) silicon substrates in N2O and diluted O-2 ambients have been studied. The RIE will strongly affect the silicon surface microroughness and lead to poor oxides properties. Using the after-treatment-chamber (ATC) process, CF4 addition in the O-2 plasma can further improve the time-zero-to-dielectric-breakdown (TZDB) characteristics of the thin oxides as compared with pure O-2 plasma. This is because CF4 addition in the ATC can remove the damaged silicon layer and smooth the silicon surface since the (O)2 plasma can effectively only strip the polymeric layer. In addition, the N2O-grown oxides can enlarge the process window of the CF4/O-2 ATC treatments with respect to pure oxides.
ELECTRICAL CHARACTERISTICS OF THIN-FILM TRANSISTORS WITH DOUBLE-ACTIVE-LAYER STRUCTURE
(1995-02-01)
TSAI, MJ
;
WANG, PW
;
SU, HP
;
CHENG, HC
;
電子工程學系及電子研究所
Thin-film transistors (TFTs) with a doubie-active-layer (DAL) structure have been proposed and found to exhibit two kinds of special electrical characteristics. One is the improvement of current drivability and transconductance as compared to the traditional structure. The other is the double-switching characteristics caused by the bi-transistor action. By means of a buried oxide separating the conduction channel into two parts, carrier transport could be enhanced due to the reduction of the vertical electric Field. In addition, the weak avalanche breakdown for the top channel results in hole accumulation in the top poly-Si/buried oxide interface, further promoting the conduction of the bottom active layer, leading to the novel double-switching properties.
IMPROVEMENT OF THIN OXIDES THERMALLY GROWN ON THE REACTIVE-ION-ETCHED SILICON SUBSTRATES
(1995-05-01)
UENG, SY
;
WANG, PW
;
KANG, TK
;
CHAO, TS
;
CHEN, WH
Thin oxides thermally grown in reactive-ion-etched (RIE) silicon substrates in N2O and diluted O-2 ambient have been studied. The microroughness of the oxide-silicon interface was investigated using a spectrophotometer, atomic force microscopy (AFM), and cross-sectional high-resolution electron microscopy (HRTEM). The microroughness is strongly dependent on the RIE conditions and the post etching treatments. Furthermore, oxidation-enhanced interface microroughness has been observed. As compared with the pure oxides grown in diluted oxygen, N2O-grown oxides exhibit stronger immunity to RIE-induced damage. N2O oxidation of the etched specimens treated with an after-treatment-chamber (ATC) process result in the best electrical properties.
NOVEL TUNNELING DIELECTRIC PREPARED BY OXIDATION OF ULTRATHIN RUGGED POLYSILICON FOR 5-V-ONLY NONVOLATILE MEMORIES
(1995-06-01)
SU, HP
;
LIU, HW
;
WANG, PW
;
CHENG, PW
;
JEN, IM
A novel dielectric fabricated dy thermal oxidation of ultrathin rugged polysilicon film is proposed for nonvolatile memories, Different roughness degrees for the top and bottom interfaces of this dielectric ate detected by the atomic-force-microscopy (AFM) and high resolution transmission electron microscopy (HRTEM), Due to the microtips formed at the bottom interface of the dielectric, significant improvements in the high conduction efficiency, low trapping rate, good uniformity, and high reliability under positive gate-bias are obtained for the dielectric. Therefore, rugged polyoxide is promising for future 5-V-only floating-gate applications.