INFLUENCE OF THE TRENCH CORNER DESIGN ON EDGE TERMINATION OF UMOS POWER DEVICES

In this article, the voltage blocking capability of UMOS power devices is experimentally demonstrated to be limited by the onset of a premat ure breakdown at the corners of the trench located at the device perip hery. With the aid of numerical simulations performed in cylindrical c o-ordinates, it is shown for the first time that a race-track shape of the trench gate fingers alleviates the electric fields at the trench corners and maximizes the UMOS voltage blocking capability. In additio n, it is also shown that the breakdown voltage at the trench corners c an be made to exceed the UMOS unit cell breakdown voltage by using a d eep p diffusion around the trenches located at the device periphery. ( C) 1997 Elsevier Science Ltd.