contact trenches 509 in fig9 h a step of p type dopant bf 2 ion implantation is carried out to form a p ohmic body doped region 512 within the p body region 506 and surrounding bottom and sidewalls of each the contact trench 509 underneath the n source regions 507 then a rta rapid thermal annealing is performed to activate the p type dopant in the p ohmic body doped region 512 in fig9 i a layer of ti tin 521 is first deposited along inner surface of each the contact trench 509 and top surface of the insulation layer 510 to function as barrier metal layer then tungsten metal is deposited onto the barrier layer and filling into the contact trench 509 after that the tungsten metal and the barrier metal layer is etched back to be left within the contact trench 509 to act as tungsten plug 508 next a layer of al alloys overlying a ti or ti tin layer or ti ni ag is deposited onto the tungsten plug 508 and the insulation layer 510 to act as a source metal 511 which connected to the n source regions 507 and the p body regions 506 via the tungsten plug 508 fig1 is a cross sectional view for showing an alternative step during fabricating the trench mosfet which is similar with fig9 f except that before the n type dopant ion implantation a thin screen oxide layer 525 is deposited along inner surface of the contact opening 520 to minimize ion implantation damage the screen oxide layer 525 is then removed before the dry silicon etching as in fig9 g although the present invention has.