Shorten the length of the diode edge termination to less than 1/5

A team of Fuji Electric and the Hong Kong University of Science and Technology announced a new technology at ISPSD 2016 to reduce the area of the diode's Eedge Termination. This technique allows the length of the edge termination to be reduced to less than 1/5 compared to the edge termination that previously provided the guard ring.

As diodes continue to be miniaturized, active regions that function as elements become smaller and smaller, and edge terminals occupy a larger and larger proportion of the diode chips. Especially the output current of smaller diodes, the proportion of the edge terminal larger. In a 600 V 5A diode used for white goods and the like, the length of the edge terminal is about 350 μm, and the proportion of the entire chip area reaches about 55%. Therefore, the research team began to study how to reduce the edge of the terminal.

This time, the trench was dug at the diode surface and the trench was filled with "BCB (benzocyclobutene)" or the like. With the active area of 0.55 mm 2 (equivalent to 2 A), the edge termination was provided with this structure, and the withstand voltage of 755 V was obtained with a length of 35 μm only. According to reports, this value is less than the previous use of guard ring mode edge terminal 1/5.