Performance and Reliability Impact in Strained-Silicon n-LDMOS

In this brief, the dc device performance and reliability characteristics of n-type lateral double-diffused MOSFET (nLDMOS) with various operating voltages processed by the stress memorization technique are discussed. Two tensile-inducing layers, SIN and HKSION, were deposited overlaying the drift zone, accumulation region, and channel of LDMOS, respectively. Following annealing, the specific on-resistance (Ron,sp) of every LDMOS falls, although the breakdown voltage (BV) remains same. During the thermal process, the hydrogen bond formed in the tensile-inducing layer will move to the vicinity of the gate oxygen, where it will combine with Boron in the channel region, causing a 50 mV decrease in the threshold, but will be captured by the silicon hanging bonds in the accumulation region. Devices with a longer drift region have a greater likelihood of accumulation zones trapping hydrogen bonds, resulting in greater deterioration than devices with a shorter drift region. HKSION offers superior hot-carrier immunity than SIN because the majority of its hydrogen bonds are N-H bonds, which are less likely to break during the thermal process than Si-H bonds.