Characterization of highly strained nFET device performance and channel mobility with SMT

This paper compares and analyzes the strained negative channel field effect transistor (nFET) device performance and the channel mobility behavior obtained by the stress memorization technique (SMT) using two different types of nitride films. These nitride film properties and wafer bowing during SMT fabrication are investigated. The electrical properties of SMT strained nFET devices including current-voltage characteristics, transconductance, carrier mobility, and interface state (D_it) are also analyzed. Although SMT nitride strain can enhance electron mobility, it is critical to control the nitride properties and its hydrogen content to minimize electron mobility degradation due to interface-state generation. Thus, a simple view of the essential physics of mobility enhancement in SMT strained nFETs has been provided. Results in this work also provide guidance to further nFET performance enhancement in the ever-more challenging device targets of future technology generations.