Improvement of Against Oxidation and Electrical Properties of Passivated Cu(Hf) Thin Film

• Main Authors: Yu-Tzu Chen, 陳佑慈
• Other Authors: 方昭訓
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/5vhzmm

碩士 === 國立虎尾科技大學 === 材料科學與綠色能源工程研究所 === 96 === In this study, the characteristics of Cu(Hf) alloy thin films and its applications as the materials of interconnect were investigation. Driven by copper has much lower electrical resistivity and higher electron migration (EM) resistance than that of aluminum. Hower, the copper suffers from poor adhesion with glass substrated and can not form self-passivation layer after annealed. This work aims at preparing a low resistivity, high adhesion, oxidation resistance and self-passivated Cu(Hf) alloy thin film, which will be potentially adopted as gate material on TFT-LCD and interconnection on microelectronics . Cu1-xHfx (x = 0.62-7.93 at.%) films were prepared on glass substrate by a co-sputtering method and were subsequently annealed by a RTA in a temperature range of 200°C - 600°C for 10-30 min in oxygen ambient. Self-passivated Cu thin film in the form of HfO2/Cu/SiO2 was therefore obtained because Hf diffused easily from matrix to the surface and reacted with oxygen by forming HfO2, thus oxidation of copper film can be prevented. The formation of HfO2/Cu/SiO2 improved the resistivity, adhesion to SiO2, oxidation resistance and passivative behavior of the studied film. The Cu (0.62 at.% Hf) thin film had the lowest resistivity of 2.17 μΩcm, and exhibited a superior passivated behavior among the studied films. The current-voltage measurement using metal-oxide-semiconductor (MOS) capacitor structure reveals low leakage current (10-7~10-8 A/cm2) for capacitors with as-deposited pure Cu and Cu (7.93 at.% Hf) metal gates. However, after annealing at 600˚C for 15 min, leakage current of MOS capacitors using pure copper gate exhibited a dramatic increase in leakage current, while leakage current of capacitors with Cu (7.93 at.% Hf) gate remaind at 1.968×10-8 A/cm2, indicating that the Cu (7.93 at.% Hf)/SiO2 system possessed a superior reliability to the Cu/SiO2 system.