DESIGN OF SALICIDE NMOS TRANSISTOR HAVING SHALLOW JUNCTION AND REDUCED ELECTROSTATIC DISCHARGE SENSITIVITY

摘要

PROBLEM TO BE SOLVED: To optimize transistor characteristics by employing established values of M parameter,βparameter and Rsub parameter thereby improving electrostatic/electric overstress performance. SOLUTION: An essential factor having effect on the behavior of an NMOS transistor is theβof a lateral NPN transistor and the amount thereof functions as an index of soundness of high current with respect to a lateral NPN transistor having a given Rsub . Critical level ofβis 5 and a second breakdown trigger current I12 decreases abruptly as theβdecreases below 5. The I12 also decreases as the Rsub decreases. A mechanism for determining the I12 is Joule's heat at the junction of a reverse biased drain substrate. When theβor Rsub is decreased due to increase of M, Joule's heat is increased and the I12 is decreased. Consequently, electrostatic discharge performance is lowered through shallow junction and thick salicide.