The invention provides a
semiconductor memory device and a manufacturing method thereof. The manufacturing method of the
semiconductor memory device includes the steps: forming an active region, vertically interlaced word lines and bit lines, and first and second insulating
layers on a
semiconductor substrate, wherein isolation materials are filled among the bit lines; forming a contact window and gaps in the first and second insulating
layers through
etching; filling the contact window and the gaps with
conductive materials, and
etching back the
conductive materials to enable the
conductive materials to be lower than the first insulating layer; and depositing the insulating materials and
etching to remove the insulating materials at the middle part totally so as to form a
contact pad window for a
capacitor and maintain part of the insulating materials at two sides to form a
contact pad side wall insulating layer. The manufacturing method of the
semiconductor memory device manufactures a self-aligning three dimensional
contact pad structure through photoetching and
plasma etching technology, enables the word line and
bit line array to joint with the
capacitor array, and can realize connecting contact between hexagonal closest packing
capacitor array and a tetragonal word line and
bit line array, without increasing a rewiring layer, and can manufacturing the contact pad side wall insulating layer to improve the insulating effect.