Research Of High-density Carbon Nanotubes Growth At Low Temperature For Integrated Circuit Interconnect

Carbon nanotubes (CNTs) have attracted worldwide attention and research because of their unique electromagnetic and thermal properties, and have been considered as a candidate for next generation interconnects application. Though CNTs have those properties, there are many problems for the practical application of CNTs in integrated circuit (IC) interconnects. For example, preparation of aligned CNTs with few defects and high-density is the main problem that needs to be solved in IC interconnects.In this paper, CNTs were synthesized by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD), the morphologies of CNTs were observed by scanning electron microscope (SEM), transmission electron microscope (TEM), atom force microscope (AFM) and a micro Raman spectroscopy (LRS-5). The effect of environment on the growth of CNTs, such as catalyst, substrate temperature, chamber vacuum, RF power et al., was investigated. The effect of mixture gas and RF power on the growth of CNTs at low substrate temperature (550℃)was also discussed in this paper. CNTs growth at 450℃was tried in the experiment. The main result is as follow.(1) It is experimentally found that CNTs use Fe as catalyst was little diameter and high-density. Fe catalyst is a better candidate than Ni in the growth of CNTs.(2) It is experimentally found that with the substrate temperature increasing, CNTs were synthesized aligned and high-density, and the graphitization degree of CNTs was increasing. CNTs growth in PECVD needs a high substrate temperature.(3) It is experimentally found that the working vacuum have some effect on the morphologies of CNTs. With the increasing of pressure, CNTs can growth. But if the working vacuum was more than 900Pa, amorphous carbon in the samples was increasing, and the graphitization degree of CNTs was reduced.(4) It is experimentally found that if C2H2:H2 was 1:2 CNTs were synthesized with large diameter. If C2H2:H2 was 1:4 CNTs were synthesized with small diameter.(5) The mixture gas and RF power will have obvious effect on the morphologies of CNTs growth at 550℃. It is because that the catalyst has a low activity at low substrate temperature. The best RF power is 100W and the best ratio of mixture gas was 1:3.(6) CNTs was just synthesized successfully at 450℃if the RF power was 100W, and the ratio of C2H2:Ar was 1:3. CNTs growth slowly at low substrate temperature, the graphitization degree of CNTs was 1.34.