AN ADVANCED TECHNIQUE FOR FABRICATING HEMISPHERICAL-GRAINED (HSG) SILICON STORAGE ELECTRODES

In this new fabrication technology for high-density DRAM's, an electro de with an even-surface amorphous-silicon is changed to one with an un even-surface hemispherical-grained Si (HSG-Si). This fabrication metho d consists of easily controllable processes: formation of smooth amorp hous Si electrodes by low-pressure chemical vapor deposition followed by removal of native oxide and high-vacuum annealing. This annealing p rocess can form HSG-Si covering the entire surface of all types of sto rage electrodes, including side-wall surfaces which had previously bee n dry-etched. The resulting storage electrode with HSG-Si can store 1. 8 times as much charge as can be stored an electrode without HSG-Si. S uch an increase makes it possible to reduce the height of storage elec trodes. This technique is applicable to the fabrication of high-densit y DRAM's.