| Summary: | 碩士 === 國立交通大學 === 電子研究所 === 98 === In this thesis, we use carbon plasma immersion ion implantation (CPIII) and low temperature carbon ion implantation as carbon implantation source. We applied the two processes on the application of increase NiSi thermal stability and Si-C formation.
On the research of CPIII, first we find the leakage current of N+P junction after CPIII process didn’t increase. This result is beneficial for application on junction structure. After CPIII at 5 keV for 1 minute, the agglomeration temperature of NiSi thin film without arsenic doping could increase to 800 ℃. But on the arsenic doped sample, CPIII could not increase NiSi thermal stability. We also find CPIII will deposit a carbon thin film on the surface during process, if the carbon film is too thick after all ion implantation process, it will affect the formation of NiSi. The result of CPIII application on Si-C formation is not ideal, the substitutional carbon density of sample that performed CPIII at 3 keV for 5 minutes then annealing at 650 ℃ for 120 sec is only 0.301 %. That is because the surface amorphous layer produced by CPIII is not thick enough and the level of amorphous is low.
The benefit of low temperature carbon ion implantation is it can produce thick amorphous layer with high amorphous level after process. After implantation at 7kev with a dose of 5×1015 cm-2 on a -15℃ chuck, the surface amorphous layer is about 49 nm and is near totally amorphous. We also find the implanted phosphorous profile after annealing would be shallower than the profile of as-implanted sample. This characteristic is beneficial for application on ultra-shallow junction fabrication. On the NiSi thermal stability application, we find low temperature carbon ion implantation could not improve thermal stability of phosphorous implanted NiSi film, which is similar to CPIII. We find low temperature carbon ion implantation is promising on Si-C formation application because it can produce thick and high quality surface amorphous layer after process. We perform low temperature carbon ion implantation with different energy、dose and chuck temperature and try to find the ideal implantation condition. From the result we find implantation energy at 7keV with a dose of 5×1015 cm-2 is the most ideal condition. We also try different annealing condition including first step annealing temperature、time and second step annealing method to find the ideal annealing condition. For first step annealing, temperature at 750 ℃ for 120 sec is the ideal condition. If the temperature is too high or the time is toolong, the density of substitutional carbon would decrease. Second step annealing time should be very high to increase carbon solid state solubility in silicon under supersatuation state, but the annealing duration time should be much shorter than 1 sec or the substitutional carbon density will decrease, too. The time duration of PLA is only about 25 ns for each shot, which is a promising second step annealing technique. Finally, by combine the optimized process condition, sample implanted at 7keV with a dose of 5×1015 cm-2 on a -15℃ chuck after first step annealing at 750 ℃ for 120 second and second step annealing using PLA at energy 350 mj/cm2 for 5 shots, the substitutional carbon density can reach 1.091%.
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