| Summary: | 碩士 === 國立臺南大學 === 電機工程學系碩士班 === 100 === A Gate-Grounded N-channel Metal-Oxide-Semiconductor Field-Effect Transistor (GGNMOSFET) structure is presented to provide the effective ESD protection. By implementing Shallow Trench Isolation (STI) and N+ buried layer (NBL) into the GGNMOSFET, the snapback effect of the structure can be further controlled.
The effectiveness of an ESD protection circuit is highly dependent with the NMOSFET snapback characteristic. The key point is how to control appropriate breakdown voltage and holding voltage, which would provide the effective ESD protection and avoid latch-up phenomena in the circuit. The proper breakdown voltage can protect circuit immediately. The holding voltage supplies the stability to the input of the next level while the holding current is sufficient to drive it. In this thesis, the breakdown voltage, the holding voltage and the holding current are designed with about 25V, 10V and 2A, respectively. The snapback characteristic curve provides the GGNMOSFET with proper protection and stability. When the input voltage of the GGNMOSFET is 25V, it causes breakdown to protect the circuit from burning out. The holding voltage with steady 10V is supplied to the input of the next level circuit, and the holding current of 2A can keep the next level circuit under normal operation. The sensitivity to different NBL concentrations is investigated for the snapback effect. The manufacturing process is discussed to prevent damage or crack and improve repeatedly to increase the yield rate for the GGNMOSFET.
Finally, the device is connected with RC transient test circuit. Such a circuit has been verified as an effective method to evaluate the stability in ESD applications. When the ESD protection effect is observed, the rise time and time constantτare utilized to obtain the time-domain temperature and I-V curve. The analysis indicates that the GGNMOSFET can provide stable and effective ESD protection for the circuit.
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