Self heating effect on hot carrier degradation characteristic in high voltage n-channel LDMOS

Abstract

This paper reports on self heating caused by hot-carrier (HC) stress in packaged thick gate oxide HV LDMOS devices, and how self heating significantly affects HC degradation characteristics. The time delay between the removal of the HC stress and the parameter measurement significantly after each stress cycle significantly affected the measured HC Idlin/Rdson degradation. For a longer delay time, lower Idlin degradation was observed. The difference, or recovery, of degradation with longer delay time was mainly due to the self heating effect. The Idlin degradation from self heating effect seems to be more than from the HC effect in packaged HV LNDMOS. Based on the data, some methods are proposed to eliminate the self heating effect, and to separate the self heating and local HC injection effect.