Phosphorus and Boron Ion Implantation Profiles in Molybdenum Gates

In this brief, we evaluated phosphorus (P) and boron (B) ion implantation profiles in molybdenum (Mo) gates using secondary ion mass spectrometry (SIMS) and showed that the P and B profiles have significant channeling tails. We expressed the SIMS profiles using an analytical model and established a corresponding database. We also studied the structure of the Mo layer using X-ray diffraction and transmission electron microscopy. The Mo layer had a polycrystalline structure with (110), (211), and (200) dominant orientations. The average grain size of the Mo layer was 53 nm, growing cylindrically from the SiO₂/Mo interface to the Mo surface. Therefore, the significant channeling was due to the crystalline structure of as-deposited Mo gates. We also showed that this significant channeling of P and B could be suppressed by high tilt angle ion implantation or by using a multideposited Mo gate, and we proposed empirical models for the corresponding profiles