Silicon Schottky barriers and p-n junctions with highly stable aluminum contact metallization

Reactively sputtered amorphous Ta/sub 36/Si/sub 14/N/sub 50/ thin films are investigated as diffusion barriers to improve the thermal stability of contacts to electronic devices, specifically between Al overlayers and Si substrates. Electrical measurements on Schottky diodes and on shallow n/sup +/-p junction diodes are used to evaluate the thermal stability of the (Si)/W/sub 48/Si/sub 20/N/sub 32//Ta/sub 36/Si/sub 14/N/sub 50//Al metallization. The W/sub 48/Si/sub 20/N/sub 32/ contacting layer is added to raise the Schottky barrier height on n-type Si. It is shown that a 100-nm-thick Ta/sub 36/Si/sub 14/N/sub 50/ layer effectively prevents the intermixing between Al and Si. With this barrier layer, both shallow junctions and Schottky diodes are electrically stable up to 700 degrees C for 20 min (above the Al melting point of 660 degrees C ), which makes this material the best thin-film diffusion barrier on record.<
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