Practical Consideration for PLR versus WLR HCI Testing

Abstract

There are two methods to conduct hot carrier (HCI) test, which are wafer level (WLR) and packaged level (PLR). The tests are normally conducted on wafer level (WLR) using a manual probe station or automatic tester with probe card. WLR testing is more convenient on the wafer itself and directly from production, faster pre-assessment can be obtained without additional packaging which costs some dollars and cents. However, PLR provide more accurate lifetime extrapolation through higher sampling rate and stress time. The comparison was made in this paper. The correlation between WLR and PLR was studied also for MOSFET devices with standard LV NMOS and MV LDMOS device. The PLR showed higher HCI degradation compared to WLR for MV LDMOS device, whereas comparable for LV NMOS. This was very low level of device self-heating effect on LDMOS from characteristic curves. However, the heat dissipation from ceramic packages took time compared to large silicon wafer on probe chuck. The stress-induced heating impact on LDMOS is discussed in this paper.