This invention discloses an optimized
cell layout structure for a
trench MOSFET and its fabrication method. The optimized
cell layout structure of the
trench MOSFET includes an epitaxial layer, within which multiple trench structures extending in the thickness direction and of different depths are formed. The trench walls are provided with a
gate oxide layer and filled with a
polysilicon gate. A first well region and a second well region with different extension depths are formed between the trenches, and a corresponding
conductivity-type doped region is formed on the surface of each well region. By constructing trench and well region structures of different depths, this invention enables the formation of channel units with different conduction characteristics inside the device, achieving
current distribution and flow when the device is turned on, improving
current density concentration, enhancing
current distribution uniformity, and improving device reliability.