On the Study of Zinc Oxide Thin Film Varistor manufacturing and ESD Application

• Main Authors: Yuan-Shun Chang, 張淵舜
• Other Authors: Liann-Be Chang
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/34377004041565403257

碩士 === 長庚大學 === 電子工程研究所 === 95 === Conventional ceramic varistors based on bulk zinc oxide (ZnO) with various metal additives have been widely used in surge protection device by grounding the excessive current for a long time. Present sintered bulk ZnO is known to exhibit high nonlinearity coefficient (α＞50) and good reliability for many commercial applications. However, high temperature ceramic sintering process limits the practicability for integrating bulk ZnO varistor with semiconductor devices. In this thesis, we propose a new manufacturing method for ZnO varistor thin-film produced, by RF sputtering system and annealing treatment, and have shown many good characteristics. The fabricated thin-film ZnO varistors were made by sputtering ZnO targets which contains Al2O3 as dopant and another without. Their nonlinear coefficients (α) in the correspondent current-voltage (I-V) measurement are 50 at an electric field of 1.2 kV/cm and can conduct a grounding current density as high as 50 A/㎝2 successfully. In addition, our fabricated thin film varistors have been combined with light emitting diode(LED) chips and reveal an obvious improvement of the LED electrostatic discharge protection. Sputtering and annealing are two commonly used processes in general semiconductor manufacture procedures. Therefore this proposed method is easy to integrate ZnO thin film varistor with other semiconductor device to accomplish on-chip surge protection.