Characterization of gate charging N-channel mosfet to determine the effects of different gate bias voltages and temperature conditions

• Main Author: Garcia, Rommel Galang
• Format: text
• Language: English
• Published: Animo Repository 2008
• Subjects: Metal Oxide Semiconductor Field Effect Transistor; Metal oxide semiconductors; Field-effect transistors; Electrical and Computer Engineering
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/3726; https://animorepository.dlsu.edu.ph/context/etd_masteral/article/10564/viewcontent/CDTG004470_P.pdf
• Institution: De La Salle University

Usual applications of Metal Oxide Semiconductor Field Effect Transistor (MOSFET) such as in the field of battery operated systems; drivers and solid state relays require a stable threshold voltage. A MOSFET with varying threshold voltage can cause degradation of the output signal or complete malfunction of the final product where it is being used. Recent failure cause encountered on MOSFET known as Gate Charging phenomena proved that varying threshold voltage could happen on MOSFET. An immediate screening method was put in place to ensure affected product would not escape during production testing. However, with the recent customer complaints involving failed MOSFET device due to Gate Charging phenomena, a characterization on reject units representing different categories and a known good unit must be performed. This research aims to completely understand the characteristics of MOSFET affected by Gate Charging phenomena as compared to a known good unit through characterization in terms of the electrical test parameters. This research also verifies the effectiveness of the existing screening method. Analysis of the results shows that application of different gate bias voltages has significant effects on MOSFET affected by gate charging phenomena. The existing screening method was proven inefficient and incomplete based on the characterization results of the unit with marginal threshold voltage. Further iii characterization was performed on the characterized samples to be able to plot their respective transfer characteristic curves. Analysis of the results shows significant difference in terms of slope between units affected by Gate Charging phenomena and a known good unit. A new screening method that includes a test parameter function to subtract values of two threshold voltage (Vth) parameters measured at different drain current (Id) was generated. Through retesting and verification of units from different production lots that already passed using the old screening method, the new screening method was confirmed effective and efficient. No single reject unit affected by Gate Charging phenomena escaped during testing and at the same time no occurrence of over-rejection on known good unit. The final test program is already revised and approved to include the new screening method and now for immediate implementation.