利用P型场环调节表面电场的积累层LDMOS

An Accumulation LDMOS for Adjusting Surface Electric Filed Using P-Type Filed Limiting Ring

提出了一种在N型外延层中带有P型场环的积累层LDMOS。当器件耐压时,N型漂移区中浮空P型场环能调节漂移区的电场分布,以提高器件的耐压。当器件正向导通时,漂移区上方介质层的多晶硅二极管会在漂移区表面形成一层电子积累层,大幅提高器件的导电能力,从而降低器件的比导通电阻。数值仿真结果表明,该LDMOS的比导通电阻从传统结构的371mΩ·cm2降低到60.9mΩ·cm2。相比于没有场环的传统结构,该LDMOS的耐压从660V提高到765V。

A novel accumulation LDMOS was proposed,in which a P-type field limiting ring was arranged in the N-type epitaxial layer.When the device was turned off,the P-type floating field limiting ring in the N-type drift region could modulate the electric field distribution especially in the surface of the N-type drift region,thereby greatly increasing the breakdown voltage of the device.When the device was turned on,an electron accumulation layer was induced on the surface of the drift region,thereby greatly improving the conductivity of the device and reducing the specific on-resistance.Numerical simulation results showed that the Ron,sp of the proposed LDMOS using the field limiting ring was reduced from 371 mΩ·cm2 to 60.9 mΩ·cm2 compared with that of the conventional LDMOS.Meanwhile compared with the conventional accumulation LDMOS without field limiting ring,the breakdown voltage of the proposed structure was increased from 660 Vto 765 V.