The invention relates to a
deep trench MOSFET device structure with low on-resistance. The
deep trench MOSFET device structure is characterized in that the shielded gate
electrode polysilicon of the device is in
short circuit with gate
electrode polysilicon above the shielded gate
electrode polysilicon, an accumulation layer is formed in an MESA region close to a
deep trench region, and the left side and the right side of the gate electrode polysilicon extend downwards to form a low-resistance region on the side wall of the deep trench. According to the invention, the traditional short circuitbetween the shielded gate electrode and the source region is improved into the
short circuit between the shielded gate electrode and the gate electrode, so that the
dielectric between the polysilicons is reduced to the minimum, the upper gate electrode
polycrystalline silicon layer extends downwards, and part of MESA resistance of the device is converted into accumulation layer resistance with lower resistivity; and through the extension of the gate electrode
polycrystalline silicon layer, the
equipotential line in the MESA is transferred to the middle position of the deep trench from the PNjunction between the
body region and the drift region, so that the longitudinal
electric field intensity of the deep
trench MOSFET platform is converted into more uniform approximate rectangular distribution from hump distribution.