Operation of semiconductor devices subject to hot carrier injection

DSONDqDSGSGiven a set of hot carrier stress data measured at a fixed level of an operating parameter (e.g., V), my invention predicts what the overall hot carrier stress will be when the same operating parameter is dynamically varied in time pursuant to a predetermined function. One embodiment of my invention is a method of operating a semiconductor device (e.g., a LDMOS FET) that is subject to hot carrier injection (HCI) and is characterized by a device parameter (e.g., R; I) and a dynamically varied operating parameter (e.g., V, V) comprising the steps of: (a) determining a device parameter that is a measure of the performance of the device; (b) determining the desired lifetime of the device based on an acceptable level of degradation of the device parameter; (c) determining the stress history of the device, including whether or not the device has been previously stressed by HCI; (d) determining the function that describes how the operating parameter is dynamically varied during operation of the device; (e) determining the HCI-induced changes in the device parameter when the operating parameter is fixed in time; (f) based on the stress history of step (c), the function of step (d), and the HCI-induced changes of step (e), determining the HCI-induced degradation of the device parameter; and (g) operating the device with the function if the degradation of step (f) is not greater than the acceptable level of step (b).