Experimental Study on the Potential of nLDMOSFETs with Partial Drain Slit Structure

It is well-known that a drain multi-finger STI nLDMOSFET structure in which an STI section and a silicon surface section in the drift region are repeated in the channel width direction can improve the specific on-resistance (R
sp
) versus the off-state breakdown voltage (BV
off
) trade-off. However, an nLDMOSFET to which this structure is applied is not suitable for high BV
off
(> 50 V) because it is difficult to relax the electric field at both sides of the drain silicon slit and at the channel side edge of the silicon slit. To overcome the first drawback, it is proposed to incorporate an STI section without silicon slits into the drain side region (partial drain slit structure) in this paper. The gate polysilicon cutout structure on an accumulation region is also proposed to overcome the second drawback.