Browsing by Author "JAN, ST"

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EFFECTS OF COBALT SILICIDATION ON THE ELECTRICAL CHARACTERISTICS OF SHALLOW P(+)N JUNCTIONS FORMED BY BF2+ IMPLANTATION INTO THIN POLYCRYSTALLINE SI FILMS
(1995-03-01)
LIN, CT
;
CHAO, CH
;
JUANG, MH
;
JAN, ST
;
CHOU, PF
Excellent shallow p(+)n junctions have been formed by implanting BF2+ ions into thin polycrystalline Si films and subsequent annealing. The samples implanted at 50 keV to a dose 5 x 10(15) cm(-2) show a leakage of 1 nA/cm(2) and a junction depth of about 0.05 mu m after a 800 degrees C annealing. To reduce the series resistances of the junctions, silicidation with different col;alt thickness was used to drive the as-implanted dopants in the polysilicon films into the resultant junctions of the silicon substrates. For the low energy implantation at 50 keV at all dosages, silicidation can result in poor electrical characteristics due to the confinement of the dopants by the silicidation process. On the other hand, the electrical characteristics can be retained when a higher implantation energy of 100 keV with a dosage higher than 5 x 10(15) cm 2 was used. In addition, the samples implanted at 125 keV show poor electrical characteristics for the nonsilicided junctions but good characteristics after the silicidation. It is attributed to the enhanced defect annihilation by the formed silicide. Furthermore, silicided implanted through poly-Si junctions with excellent characteristics can be fabricated after a low temperature (600 degrees C) annealing if the samples are implanted at 100 keV with a dosage higher than 5 X 10(15) cm(-2).
FORMATION OF SHALLOW P(+)N JUNCTIONS BY BF2+ IMPLANTATION INTO THIN POLYCRYSTALLINE SI FILMS
(1994-09-15)
LIN, CT
;
JUANG, MH
;
JAN, ST
;
CHOU, PF
;
CHENG, HC
Excellent shallow p(+)n junctions have been formed by implanting BF2+ ions into thin polycrystalline Si films and subsequent annealing. The samples implanted with 5X10(15) cm(-2) at 50 keV show a leakage of 1 nA/cm(2) and a junction depth of about 0.05 mu m after a 800 degrees C annealing. Various implant and annealing cases were examined to determine and characterize their effects on the resultant junctions. High energy implantations (125 and 150 keV) exhibit poor characteristics at all annealing temperatures because the Si substrates are severely damaged. However, the specimens implanted below 100 keV result in excellent diode characteristics for all implantation doses after an 800 degrees C annealing since the implantation defects are confined in the poly-Si layer. The major factors affecting the junction depth were found to be the implantation energy and annealing temperature, while a minor for the implantation dosage. Furthermore, the effects of the subsequent silicidation on the resultant junction characteristics were also investigated.
THE PROCESS LIMITATION FOR FORMING TI SILICIDED SHALLOW JUNCTION BY BF(2)+ IMPLANTATION INTO THIN POLYCRYSTALLINE SI FILMS AND SUBSEQUENT TI SILICIDATION
(1993-08-30)
JUANG, MH
;
LIN, CT
;
JAN, ST
;
CHENG, HC
;
電控工程研究所
Excellent shallow p+n junctions have been formed by implanting BF2+ ions into thin polycrystalline Si films and subsequent annealing; these junctions which show a leakage of 1 nA/cm2 and a junction depth of about 0.05 mum. An anomalous boron diffusion occurs when subsequent silicidation is carried out. Silicidation using 300-angstrom Ti just slightly affected the junction profile. However, the junction is considerably deepened for 600-angstrom Ti silicidation, yielding a resulting depth of about 0.11 mum. The large boron redistribution is attributed to the point defects induced by silicidation. Hence, proper silicide thickness should be chosen to retain the junction profile as well as to reduce the parasitic source/drain resistance.