| 摘要 |
For a vertical DMOS power transistor or a high voltage bipolar transistor, an edge termination at the perimeter of the die surrounding the active transistor cells includes multiple spaced apart field rings. A trench is located between each adjacent pair of field rings and is insulated either by oxide formed on the sidewalls thereof or by an oxide filling. The insulated trenches allow the field rings to be very closely spaced together. Advantageously the trenches may be formed in the same process steps as are the trenched gate electrodes of the active portion of the transistor. This structure eliminates the necessity for fabricating thick field oxide underlying a conventional field plate termination, and hence allows fabrication of a transistor without the need for a field plate termination, and in which the multiple field rings are suitable for a transistor device having a breakdown voltage in the range of 20 to 150 volts. The trenches advantageously eliminate the process sensitivity of using multi field ring terminations with low resistivity semiconductor material.
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