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

In this new fabrication technology for high-density DRAM's, an electrode with an even-surface amorphous-silicon is changed to one with an uneven-surface hemispherical-grained Si (HSG-Si). This fabrication method consists of easily controllable processes: formation of smooth amorphous Si electrodes by low-pressure chemical vapor deposition followed by removal of native oxide and high-vacuum annealing. This annealing process can form HSG-Si covering the entire surface of all types of storage electrodes, including side-wall surfaces which had previously been 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. Such an increase makes it possible to reduce the height of storage electrodes. This technique is applicable to the fabrication of high-density DRAM's.