FIELD EFFECT TRANSISTOR HAVING LDD REGION FORMED USING COUNTER AND NON-COUNTER DOPANT ELEMENT

摘要

PROBLEM TO BE SOLVED: To prevent the lifetime of an FET from being shortened through hot carriers, due to incorrect formation a junction by including a step for implanting an LDD dopant and a counter dopant into a substrate on the boundary of an LDD region. SOLUTION: An LDD region 24 is formed by masking a gate 22 using a layer of photoresist 26 and implanting an LDD dopant 28, e.g. arsenic, at a low dose through an oxide layer 20 into a substrate 12. On the other hand, the LDD region 24 is counter doped, using an electrically active counter dopant 32. Net active concentration of the LDD dopant 28 is lowered at the junction due to the presence of the counter dopant 32, e.g. boron. In this way, an electrically active boundary of a doped region can be formed more accurately by implanting a counter dopant into the doped region of a semiconductor substrate.