Process and device design of a 1000-V MOS IC

High-voltage MOS devices and logic N-MOS circuits have been integrated on the same chip by using a silicon-gate isoplanar process that is compatible with present N-MOS LSI technology. The electrical characteristics of high-voltage MOS devices are modeled and characterized in terms of channel length, drift-layer length, drift-layer ion dose, and extended source field-plate effect. The theoretical calculations of on-resistanee, saturation drain current, and pinchoff voltage agree well with the experimental results. Based on the experimental and theoretical results, the device structure and the process parameters are optimized to obtain maximum drain saturation current with a low on-resistance and a drain breakdown of 1000 V. The optimized high-voltage MOS device can perform with a saturation drain current as high as 84 mA with an on-resistance as low as 300 Ω within an area of 520 µm × 1320 µm while maintaining a drain breakdown of 1000 V.