Flash Annealing Technology for USJ: Modeling and Metrology
Millisecond annealing either by flash lamp or laser appears to be the leading approach to meet the needs of ultra-shallow junction annealing and polysilicon activation for advanced technology nodes. There are many advantages to this technology including high electrical activation, excellent lateral abruptness, controlled and limited dopant diffusion and the ability to engineer the extended defects remaining from the ion implantation. There are also many challenges such as potential pattern effects, local and global wafer stress and difficulty in process integration. Additional challenges include the need to extend the capabilities of process TCAD to allow accurate simulation and prediction of the ms processes. Modeling of diffusion, activation and defect evolution for a variety of technologically interesting doping conditions must be dependable to allow the device designer and process engineer to predict the device behavior after ms annealing. Existing models fall short or still need to be validated. Metrology for ultra-shallow junctions is also a challenge. The ability to accurately and repeatably measure sheet resistance and junction leakage on junctions of the order of 10nm deep is very difficult. This paper provides an overview of flash lamp annealing and deal with some promising extensions of process simulation to enable the predictive modeling of junction behavior under flash lamp annealing conditions. We also examine some of the new metrology techniques for characterization of these very shallow junctions and look at some of the trends exhibited for different junction formation details
The Influence of the Amorphous Phase on Ion Distributions and Annealing Behavior of Group III and Group V Ions Implanted into Silicon
A study has been made of room‐temperature implantations of group III and group V ions into amorphous Si layers prepared by the previous implantation of Si ions into crystalline Si substrates. Neutron activation combined with anodic oxidation and HF stripping techniques was used to determine the proflies of the implanted ions for Ga71 and Sb121. Electrical evaluation of the implanted layers by Hall effect and sheet resistivity measurements in conjunction with layer removal techniques yielded profiles of the net electrically active species and the depth variation of mobility after annealing for 30 min in the temperature range 600°–900°C. The ion species studied were B11 (60–200 keV), Al27 (200 keV), Ga69&71 (140 and 280 keV), P31 (100–280 keV), As75 (280 keV), Sb121&123 (120 and 260 keV), and Bi209 (240 keV). The epitaxial regrowth of the amorphous phase at 600°C causes most of the implanted ions within this region to become electrically active and uncompensated for the ion species B, P, As, Sb, and Bi even for peak ion concentrations in excess of 1020 cm−3. For Al and Ga implants, the number of carriers was less than the number of implanted ions. The profiles obtained for these implantations into amorphous Si were compared with predictions based on the theory of Lindhard, Scharff, and Schiott.
Evolution of carbide precipitates in Hastelloy N joints during welding and post weld heat treatment
Abstract The effects of welding and post weld heat treatment (PWHT) on the morphology, composition and lattice parameter of the precipitates in the welding joints of Hastelloy N alloy have been investigated. Joint samples were prepared using a gas tungsten arc welding process with ERNiMo-2 fillers, and then solid-solution treated at 1100 °C for 20 min. After welding, eutectic M6C carbides can be observed in the heat affected zones (HAZ) and weld zones (WZ). These eutectic M6C carbides become spheroidized during the following PWHT. The concentration of Si decreases during the transformation from the primary ones to eutectic ones, and then increases during the spheroidizing process. The total concentration of Si + Cr in M6C carbides remains stable during welding and PWHT. At the same time, the heat leads to the outward diffusion of Mo from the M6C carbides, which results in a decrease of the lattice parameter.