Improvement of electron diffusion lengths in polycrystalline silicon wafers by aluminium
In order to improve the electron diffusion lei wafers, an aluminium layer was deposited on the back sul 2 h. It was found that Ln is increased, provided the initi; density of dislocations is larger than 5 x 104 cm-2. Backsig to explain the results and it is assumed that dissolved c
Lateral reaction of polycrystalline silicon film with overlapping aluminum film
Remarkable substitution reaction between aluminum and polycrystalline silicon, which occurs below the eutectic temperature (577 °C), has been studied. This reaction proceeds laterally in the polycrystalline silicon film, and the reaction product contains aluminum. In order to elucidate the cause of the rapid reaction, the influences of aluminum volume, substrate materials, and polycrystalline silicon grain size on the reaction rate were investigated. Results indicate that the reaction proceeds preferentially along polycrystalline silicon grain boundaries on SiO2 substrate and depends on silicon solubility and diffusivity in aluminum.
Grain boundary diffusion of aluminum in polycrystalline silicon films
Grain boundary diffusion of Al in poly‐Si films has been measured by an Auger sputter profiling technique in a temperature range of 350–425 °C. The Al atoms were observed to diffuse through Si grain boundaries, then accumulated near a poly‐Si/SiO2 interface. By concentrating on the initial stage of diffusion, the diffusion problem was analyzed using a simple model in which a steady‐state flux of Al though Si grain boundaries is accumulated by an effectively infinite sink at the poly‐Si/SiO2 interface. Auger measurements yielded quantitative information regarding the concentration gradient in the middle of the poly‐Si layer and the amount of accumulation near the poly‐Si/SiO2 interface. From this information, the grain boundary diffusion coefficient of Al in Si Db was determined. The temperature dependence of Db fits an Arrhenius‐type relation with D°b =1.3×107 cm2/s and Qb =2.64 eV. The measured activation energy was found to be consistent with that of the grain boundary diffusion of P and B as well as th...