RUGGED SURFACE POLYCRYSTALLINE SILICON FILM DEPOSITION AND ITS APPLICATION IN A STACKED DYNAMIC RANDOM-ACCESS MEMORY CAPACITOR ELECTRODE

Rugged surface polycrystalline silicon (poly-Si) films deposited by lo w-pressure chemical vapor deposition have been studied and the films h ave been applied to a storage electrode for stacked dynamic random acc ess memory capacitors. The surface morphology of the films was drastic ally affected by growth conditions and by the film thickness. However, the rugged surface poly-Si was characterized by the growth of grains that have [311] preferred orientation. The grains had grown on the amo rphous Si surface just after deposition in the low-pressure chemical v apor deposition furnace. It was observed that the amorphous Si films d eposited at the transition temperature between amorphous and polycryst alline Si have small crystalline particles in the films. We surmise th at the nucleation sites of rugged surface poly-Si grains are small cry stalline particles in amorphous Si near the surface, because the amorp hous Si films deposited at high SiH4 pressure acid low temperature (le ss than 540 degrees C) that have no crystalline particles in the film show no grain growth of rugged surface poly-Si. Stacked capacitors wer e fabricated using rugged surface poly-Si films and thin silicon nitri de dielectric films. It was found that the thin poly-Si film electrode about 100 nm thick deposited at 570 degrees C shows 2.5 times more su rface area than that of the conventional poly-Si film electrode. A rug ged surface poly-Si electrode deposited under optimized growth conditi ons is promising for high density dynamic random access memory with st acked capacitor cells. (C) 1996 American Vacuum Society.