|학술대회||2010년 봄 (05/13 ~ 05/14, 삼척 팰리스 호텔)|
|발표분야||B. Nanomaterials Technology (나노소재기술)|
|제목||Formation of TaNx diffusion barrier using plasma enhanced atomic layer deposition|
|초록||With the scaling down of ultra large integrated circuits (ULSI) to the sub-50 nm technology node, the need for an ultrathin, continuous and conformal diffusion barrier is increasing. However, diffusion barrier formation with a physical vapor deposition (PVD) method has become difficult as the technology node is reduced to 30 nm and beyond.
In this works, we investigated the variation in the properties of TaNx barrier deposited using plasma enhanced atomic layer deposition (PEALD) with various nitride contents. Terbutylimidotris(diethylamido)tantalum (TBTDET) and (H2+N2) forming gas were selected as the precursor for PEALD TaNx and reactive gas, respectively. A thermal oxide covered Si plane and trench wafer with feature size of 24 nm were used as the substrate. Measuring the growth rate of the PEALD TaNx thin film when increasing precursor feeding time and purge time up to 1 s and 10 s, confirmed the self-limiting process of PEALD with growth rate of 0.75 Å/cycle. To check the PEALD window, TaNx thin films were deposited at varying substrate temperatures from 100 to 350 ˚C. The contents of nitrogen in the TaNx thin films from 45 to 62 at. % was controlled by increasing the flow of N2 gas at the plasma exposure cycle, which was identified by XPS. To investigate Cu diffusion barrier properties of PEALD TaNx, current–voltage (I–V) measurements were made to get the leakage current density through the MOS structure (Cu/TaNx/SiO2/p-type Si) after annealing using HP4140B semiconductor parameter analyzer. The about 4 nm TaNx diffusion barrier was able to sustain a thermal annealing at temperatures up to 500 °C without degradation to the electrical characteristics. A severe degradation of the I-V characteristics of the MOS structure occurred after 550 °C annealing.
The conformality of PEALD techniques can overcome the limitations of PVD to make conformal thin films in narrow trenches, which is required in smaller electronic devices. This process should make it possible to extend the current electroplating process to devices with much smaller features.
|저자||문대용, 한동석, 김경택, 박종완|
|키워드||Cu interconnect; tantalum nitride; diffusion barrier; atomic layer deposition|