| 학회 | 한국재료학회 |
| 학술대회 | 2011년 봄 (05/26 ~ 05/27, 제주 휘닉스 아일랜드) |
| 권호 | 17권 1호 |
| 발표분야 | B. Nanomaterials and Processing Technology((나노소재기술) |
| 제목 | Effects of nitrogen reactive gas on PEALD TaNx diffusion barrier for Cu interconnect |
| 초록 | In the copper interconnection schemes, TaNx thin films have been widely used as a copper diffusion barrier. Collimated and ionized physical vapor deposition (PVD) techniques have been conventionally used to fabricate the TaNx diffusion barrier. As feature sizes are further reduced below 20 nm, however, such PVD techniques eventually meet their technological limits in forming conformal diffusion barrier films on nanoscaled contacts and via holes. Atomic layer deposition (ALD) has received great attention as the most feasible method of fabricating TaNx thin films for Cu diffusion barrier layer because it has many inherent advantages, including excellent conformality, accurate thickness controllability, and uniformity over large areas. In fact, many reports for ALD TaNx barrier processes have already been carried out, but the thermal stability and electrical properties of plasma enhanced ALD (PEALD) TaNx with various compositions have not investigated yet. In this work, low temperature PEALD TaNx thin films were deposited with various the flow ratios of reactive gas (N2/H2) and their microstructure, electrical properties and thermal stability were investigated. A PEALD of TaNx was performed on a 100 nm thick SiO2 covered plan and 24 nm sized trench substrate using tertiary-butyl lmido tris-ethylmethylamino tantalum (TBITEMAT) as a Ta precursor at a deposition temperature of 250 ˚C. The cycle for TaNx formation ad the following sequence: A TBITEMAT injection, a purge, an exposure to N2/H2 (0 - 0.2) plasma, and another purge step. The film resistivity was measured by the four-point probe method. X-ray diffraction (XRD) measurements were used to examine the crystal structure of the deposited films. The film composition was measured using X-ray photoelectron spectroscopy (XPS). To evaluate thermal stability, leakage currents of metal-oxide-semiconductors (MOSs) formed by depositing the Cu/TaNx films on the SiO2/Si substrate were measured after annealing at 300 – 700 ˚C for 12 h. The flow ratio of reactant gas (N2/H2) affected the microstructure and composition of the PEALD TaNx thin film. The nitrogen contents (x) in the TaNx film were controlled from 0.96 to 1.71. As the nitrogen contents increased, the thermal stability of the TaNx diffusion barrier was enhanced. However, phase changes as Ta2N and TaN in the films were observed as the N2/H2 ratio increased. The phase changes were associated with a change in the resistivity and excessive nitrogen contents increase the resistivity of TaNx. |
| 저자 | 박재형, 문대용, 한동석, 신새영, 박종완 |
| 소속 | 한양대 |
| 키워드 | PEALD; Diffusion barrier; Cu interconnect |
