Effect of stress in the deposited silicon nitride films on boron diffusion of silicon

The effect of stress in silicon nitride films on boron diffusion of silicon has been studied. Dur ing anneal ing in nitrogen, the degree of the retardation in boron diffusion becomes larger as the temperature becomes lower and the thickness of nitride films increases. On the other hand, boron diffusion of Si covered with very thin nitride films is enhanced for long diffusion times. These results suggest that nitride film stress makes the region near the surface of the silicon substrate compressed and changes vacancy and interstitial concentrations. The various thin films used in LSI usually develop stress during the thermal process and the stress causes problems such as leak current and generation of dislocations in large scale integrated (LSI) devices. Moreover, accurate control of boron diffusion %vith doses of 1012 to 1013/cm 2 in silicon covered with various films is essential for channel doping with the scaling down of LSI. Therefore, it is necessary to investigate the effects of stress in the films on the substrate and on dopant diffusion in the silicon substrate