A novel high-voltage device structure with a floating heavily doped N^+ ring embedded in the substrate is reported,which is called FR LDMOS.When the N^+ ring is introduced in the device substrate,the electric field peak of the main junction is reduced due to the transfer of the voltage from the main junction to the N^+ ring junction, and the vertical breakdown characteristic is improved significantly.Based on the Poisson equation of cylindrical coordinates,a breakdown voltage model is developed.The numerical results indicate that the breakdown voltage of the proposed device is increased by 56%in comparison to conventional LDMOS.
提出具有浮空埋层的变掺杂高压器件新结构(BVLD:Variation in lateral doping with floating buriedlayer),建立其击穿电压模型。线性变掺杂漂移区的电场耦合作用使表面电场达到近似理想的均匀分布,n+浮空等电位层与衬底形成新平行平面结,使得纵向电压由常规结构的一个pn结承受转变为两个串联pn结分担,改善了器件的击穿特性;建立二维的击穿电压模型,获得器件结构参数间的优化关系。结果表明:与常规LDMOS相比,BVLD结构的击穿电压提高94%。
