The Farbrication of Polysilicon Thin Film Transistors by Copper Induced Crystallization

• Main Authors: Wei-chieh Hsueh, 薛瑋傑
• Other Authors: Si-Chen Lee
• Format: Others
• Language: en_US
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/29230727734430690638

碩士 === 國立臺灣大學 === 電機工程學研究所 === 90 === The material properties and device characteristics of copper induced polysilicon thin film transistor are investigated. Polysilicon material has been prepared metal induced crystallization (MIC), and metal induced lateral crystallization (MILC). The polysilicon material is characteristized using Raman spectrum, transmission electron microscopy (TEM), and transmission electron diffraction (TED) patterns. It is found that the polysilicon formed by nickel induced lateral crystallization has larger average grain size (~ 1 μm) and more uniform distribution and one formed by copper induced has small grain size (~ 0.05 μm) and great growth rate of polysilicon crystallization (6~20μm per hour). The growth rate of lateral crystallization by Cu is about 5 to 12 times faster that of nickel MILC poly-Si. The fabrication processes of copper induced crystallized low temperature polysilicon thin film transistor are proposed. The characteristics of Cu MILC poly-Si TFT were measured and compared in different conditions. Effects of hydrogen plasma treatment, thickness of intrinsic film and growth temperature of LPCVD SiO2 are presented. Transistors have field effect mobility 12~29.9 cm2/V-sec with H2 plasma treatment and 1.24~3.34 cm2/V-sec and without H2 plasma treatment. The threshold voltage of the devices are at 5.51~10.4 V with H2 plasma treatment and about 29 V without H2 plasma treatment. And on/off current ratio of about 104~105 of the device with H2 plasma treatment are obtained.