New Approaches for Characterization of Advanced Annealing Techniques for Ultra-Shallow Junction Formation

Abstract

Low thermal budget annealing approaches, such as millisecond annealing or solid‐phase epitaxy (SPE), can electrically activate ultra‐shallow junctions (USJ) without excessive diffusion, but they must also remove implant damage to minimize junction leakage. This paper presents results from annealing low‐energy B implants into both crystalline and pre‐amorphized silicon. Some wafers also received As implants for halo‐style doping, and some halo‐implanted wafers were pre‐annealed at 1050 °C before B‐doping. The final anneal was either SPE at 650 °C, spike annealing at 1050 °C, or millisecond annealing with flash‐assisted RTP™ (fRTP™) at temperatures between 1250 °C and 1350 °C. Electrical activation was assessed by sheet resistance (Rs) measurements with conventional four‐point probing (4PP) as well as Hg‐probe 4PP and a non‐contact method. Residual damage was characterized by photoluminescence, thermal wave studies, optical reflectance and non‐contact junction leakage current measurements. Damage from the heavy ions used for the halo and pre‐amorphization implants dominates the annealing behaviour. Halo doping is the critical factor in determining junction leakage current. High temperature fRTP is shown to minimize residual damage.