impurity regions as shown in fig4 b subsequently a titanium target not shown is sputtered and a titanium layer 26 is deposited to 40 nanometers thick over the entire surface of the resultant structure the titanium layer 26 is heated to 650 degrees in centigrade for 30 seconds then the titanium reacts with the silicon polysilicon and the titanium layer 26 is selectively converted to titanium silicide regions 26a however the titanium does not react with the silicon oxide and silicon nitride and titanium regions 26b are left on the side wall spacers 25b and the buried isolating structure 24 as shown in fig4 c the titanium regions 26b are etched away by using the etchant containing ammonia and hydrogen peroxide and only the titanium silicide regions 26a are left on the heavily doped n type source drain regions 25d 25e and the polysilicon gate electrode 25a as shown in fig4 d in this instance the n type source drain region 25e and the titanium silicide layer 26a formed thereon form in combination a conductive region subsequently silicon oxide is deposited to 100 nanometers thick by using the chemical vapor deposition over the entire surface of the resultant structure and the silicon oxide layer is covered with a boro phosphosilicate glass layer of 900 nanometers thick the boro phosphosilicate glass layer is reflowed at 800 degrees in centigrade for 30 seconds the silicon.