primarily etched first and second spacers 350 a and 360 a are simultaneously etched by a depth h 2 of about 200 u00e5 to about 500 u00e5 the upper portion of the primarily etched first gate electrode 330 a is exposed and simultaneously the second gate electrode 340 having the previously exposed portion is further exposed accordingly the exposed thickness of the second gate electrode 340 is greater than that of the primarily etched first gate electrode 330 a referring to fig5 f in step s 36 a cobalt layer 370 having a thickness of about 50 u00e5 to about 150 u00e5 is formed on the entire surface of the substrate 310 having the first and second structures 320 and 325 using a sputtering process in alternative embodiments other materials such as tungsten w titanium ti tantalum ta etc may be used instead of cobalt to prevent a cobalt silicide layer from oxidizing a titanium nitride layer not shown may be formed on the cobalt layer 370 referring to fig5 g and fig6 in step s 37 the substrate 310 having the cobalt layer 370 is treated through the rtp process at a temperature of about 650 u00b0 c to about 750 u00b0 c to form first second and third cobalt suicide layers 380 n 380 p and 380 any remaining cobalt layer.