TW357455B - High-density DRAM built-in capacitor structure and the assembly method - Google Patents

Abstract

A method of forming DRAM built-in capacitor structure in a silicon substrate, including: forming on said silicon substrate a first photoresist implanting shade having an opening array; forming N+ doped area on the opening of said silicon substrate by means of ion implanting, being the first photoresist implanting shade preventing ion implanting in other areas on the silicon substrate; removal of said first photoresist implanting shade; forming a crystalline silicon layer on said silicon substrate; forming a P-type well array in the crystalline silicon layer on top of said N+ doped area by means of patterned second photoresist implanting shade; removal of said second photoresist implanting shade; deposition a padded oxide layer and a nitride silicon layer and forming an opening area in the field oxide insulation area in said silicon nitride layer; forming in the surrounding of the cell area said field oxide insulation area, and electrically isolate said cell area, which is aligned to said N+ doped area; one-way etching said cell area by passing through said silicon nitride layer and the P-type well in the crystalline siliocn layer to reach the N+ doped area, for forming perfroation; even selection of etching of said perforation, for removal of said N+ doped area and forming cavities in said silicon substrate; removal of said silicon nitride layer by means of etching; deposition an electrode dielectric layer on the surface of said cavity and by said perforation; deposiition a dual crystalline silicon doped between the electrodes on said cavityy surface and stuffing said perforations, forming on the dual crystalline silicon dooped layer in said cavity, said built-in capacitor anode electric contact; grinding said dual crystalline silicon doped layer by means of chemical and mechanical grinding, for completing the assembly of said built-in capacitor.