Metal Carbides for Band-Edge Work Function Metal Gate CMOS Devices

Various metal carbides (TaC, HfC, WC, and VC) were thoroughly investigated for metal gate CMOS devices with band-edge work functions (WFs). It is found that TaC and HfC are more suitable for the CMOS device application among the various metal carbides. HfC is demonstrated to be a good candidate for NMOS because of its low WF and excellent thermal stability, while TaC Al shows a high WF and good thermal stability suitable for PMOS device application. In addition, HfC and TaC have a wide range of WF tunability using thin LaN and AlN interlayer or introduction of La and Al into the metal carbides.