A slope SOI-LDMOS power device is proposed for high-voltage. When a positive bais is applied to the drain electrode, holes are induced and astricted by the slope buried oxide layer. So a high density positive charge layer is formed on the buried oxide layer. The electrical field in the buried oxide is improved as well as vertical breakdown voltage by the layer. Because the thickness of the drift region linearly increases from the source to the drain, the surface electric field is optimized, resulting in increase of lateral breakdown voltage. In this paper, the electric characteristics of the new device are simulated by Medici softerware. The result is shown that above 600 V breakdown voltage is obtained at 1μm thick buried oxide layer. The breakdown voltage is higher by three times than that of conventional SOI LDMOS.
Electrical field distribution of 35 KV Igla under polluted and ice-covered situation at power frequency