Advanced activation and stability of ultra-shallow junctions using flash-assisted RTP
Advanced-logic device technology for the 65 nm node and beyond requires highly-activated, shallow, and abrupt dopant profiles (Int. Technol. Roadmap for Semicond., 2003). The combination of ion implantation and an advanced annealing technology is expected to provide solutions for these requirements. In contrast to spike annealing, a diffusion-less but highly activating, high-temperature, flash-assisted RTP annealing approach for the formation of ultra-shallow junctions will be demonstrated. The flash-assisted RTP technique is a promising method for achieving junction depth and sheet resistance values low enough to meet the performance specifications for the 65 nm node and beyond (Gelpey, et al., 2002, McCoy, et al., 2004). The optimal process for high activation during flash-assisted RTP involves a temperature ramp-up to an intermediate temperature between 700degC and 900degC and, once the intermediate temperature is reached, a very short, intense flash on the front side of the wafer induces a temperature jump up to 1325degC with a peak width of approximately 1.6 ms in a 100 ppm oxygen in nitrogen gaseous ambient. In this paper, we will present some of our recent p+MOS and n+MOS results on the fabrication of ultra-shallow junctions using flash-assisted RTP in crystalline and pre-amorphized silicon. It will be shown that such junctions are suitable for future technology generations. The measured "mechanical/electrical" sheet resistance values of the junctions are compared to Hall measurements on the same samples to gain an insight into the reliability of the destructive four-point probe (4PP) method for such extremely shallow junctions. Deactivation studies will be presented to examine the stability of the process to the required subsequent thermal processes
Clusters formation in ultralow-energy high-dose boron-implanted silicon
The formation and evolution of small cluster defects in 500 eV, 1×1015 cm−2 boron-implanted silicon is investigated. These clusters are identified by high-resolution transmission electron microscopy (TEM) as small dislocation loops lying on {100} planes with an interstitial character. Weak-beam dark-field TEM analysis shows that, during annealing at 650 °C, they evolve following an Ostwald ripening mechanism. Spike anneals at high temperatures make them dissolve but an immobile boron peak is still detected in the secondary ion mass spectroscopy profiles. Upon oxidation, the average size of the clusters increases, while boron electrical deactivation occurs. These results strongly indicate that the observed clusters contain both boron interstitials and silicon self-interstitials atoms.
Evidence of spurious results along with spatially autocorrelated errors in the context of geographically weighted regression for two independent SAR(1) processes
AbstractThe aim of this paper is to examine the performance of the geographically weighted regression (GWR) technique in terms of recognizing linear relationships at the local level. Using a Monte Carlo analysis with two independent spatially autocorrelated SAR(1) processes, this study finds that spurious behavior exists at the local level along with spatially autocorrelated errors. Therefore, GWR estimation results must be interpreted with caution.
