A trench MIS device includes a thick dielectric layer at the bottom of the trench. The thick dielectric layer can be formed by the deposition or thermal growth of a dielectric material, such as silicon dioxide, on the bottom portion of the trench. The thick dielectric layer, which reduces the capacitance...http://www.google.com.hk/patents/US7009247?utm_source=gb-gplus-share專利 US7009247 - Trench MIS device with thick oxide layer in bottom of gate contact trench
