DRAM cell with a roughened poly-Si electrode

摘要

A porous silicon layer is created by using wet etching to etch a polysilicon layer. In preferred embodiment, the polysilicon layer is treated by H3PO4 solution at 60-165 DEG C. for about 3-200 minutes. The porous silicon layer is subsequently treated by using a SC-1 solution at a temperature about 50-100 DEG C. for about 5-30 minutes to form a roughened polysilicon layer. The SC-1 solution is composed of NH4OH, H2O2 and H2O. The volume ratio for the three compounds of said SC-1 is NH4OH:H2O2:H2O=0.1-5:0.1-5:1-20. The next step of the formation is the deposition of a dielectric film along the roughened surface of the micro-islands polysilicon layers. A conductive layer is deposited over the dielectric film. Next, photolithgraphy and etching process are used to etch the conductive layer, the dielectric film and the micro-islands polysilicon layer into a portion of the layer.