Study on Low Dielectric Constant Diamond-Like Carbon Thin Films by Gridless Ion Beam Deposition

• Main Authors: Hsiu-Ling Huang, 黃秀鈴
• Other Authors: Chia-Fu Chen
• Format: Others
• Language: en_US
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/04713444463115703383

碩士 === 國立交通大學 === 材料科學與工程系 === 88 === For the needs of scaling down the feature sizes and increasing the circuit speed for IC manufacturing, the trend toward increasing interconnect packing density has driven the development of multilevel interconnect system. As interconnect lines shrink and move closer together, the resistance-capacitance (RC) delay will produce and directly limit device speed. The semiconductor industry has been prompted to adopt new materials and architectures: low-k dielectric / copper damascene and dual-damascene replacing traditional SiO2 / aluminum subtractive etch architectures and processes. Diamond-like carbon (DLC) is one structure of carbon elements. It is primary a mixing structure of sp3 and sp2 bondings that its chemical property is stable. DLC films are developed for future application with the advantages of high hardness and low coefficient of friction. Because DLC films can be deposited at low temperature or at room temperature, they are easily suitable for IC manufacturing. In this study, gridless ion beam deposition has been adopted to prepare amorphous diamond-like carbon films. We took thermal annealing tests on DLC films and investigated the relationships between physical properties and dielectric properties. For the studies of physical properties, DLC films were analyzed by Raman spectroscopy for chemical bonding and by RBS for film density and porosity. For the studies of electrical properties, I-V and C-V measurements were used to evaluate the leakage current and dielectric constant of DLC films. By Raman spectrum, it was found that Raman ID/IG ratio increases with annealing temperature increasing which indicates higher sp2 content in the films. The evident indicate the films are more “graphite-like”. By RBS spectrum, the density of DLC films increases while the porosity decreases with annealing temperature increasing. The results are due to the broken of the hydrogen bonds and the formation of more sp2 bondings for DLC films with increasing temperature. For the electrical characteristics of DLC films, it was found that the leakage current of MIS capacitor increases with increasing temperature annealed in vacuum while decreases in N2 ambience. The leakage current decrease is due to the reduction of surface charging by N2 annealing. By H2 plasma post-treatment, the leakage current strongly decreases with increasing treating time. The dielectric constant of DLC films was found to degrade from 3.8 (as-deposited) to 2.9 (400℃ annealed) with increasing temperature annealed whether in vacuum or in N2 ambience.