Method of forming semiconductor device

A method of forming a semiconductor device, comprising:

• forming a buried type gate structure in a substrate;
• forming a bit line structure and a plurality of landing pads on the substrate;
• forming a stopping insulating layer on the bit line structure and the landing pads;
• forming a lower molding layer on the stopping insulating layer;
• forming an upper molding layer on the lower molding layer;
• forming a first supporter on the upper molding layer;
• forming a stack of buffer layers on the first supporter including by forming a first buffer layer on the first supporter, forming a second buffer layer on the first buffer layer and forming a third buffer layer on the second buffer layer;
• patterning the buffer layers to form patterned first, second and third buffer layers;
• forming holes each passing vertically through the first supporter, the upper molding layer, the lower molding layer, and the stopping insulating layer and exposing the landing pads, respectively, including by:
• selectively etching the first supporter with a first etchant while using the patterned first, second and third buffer layers as an etch mask to form an initial section of each of the holes passing vertically through the first supporter, and wherein the first etchant etches the patterned third buffer layer and leaves the first and second patterned buffer layers on the first supporter,
• selectively etching the upper molding layer with a second etchant different from that first etchant and while using the first and second patterend buffer layers as an etch mask to extend the initial section of each of the holes vertically through the upper molding layer, wherein the second etchant etches the second patterned buffer layer and leaves the first patterned buffer layer on the first supporter;
• selectively etching the lower molding with an etchant different from the second etchant and while using the first patterned buffer layer as an etch mask to further extend each of the holes vertically through the lower molding layer;
• forming storage electrodes in the holes;
• removing a part of the first supporter located between the storage electrodes to expose the upper molding layer between the storage electrodes;
• removing the upper molding layer to expose parts of surfaces of the storage electrodes;
• removing the lower molding layer to expose other parts of the surfaces of the storage electrodes;
• forming a capacitor dielectric layer on the exposed parts of the surfaces of the storage electrodes, a surface of the stopping insulating layer and a surface of the first supporter;
• and
• forming a plate electrode on the capacitor dielectric layer.

A method of forming a semiconductor device, comprising:

• forming a pad of electrically conductive material;
• forming an etch stop layer of insulating material on the pad;
• forming a lower molding layer on the etch stop layer;
• forming an upper molding layer on the lower molding layer, and wherein the upper molding layer has an etch selectivity with respect to the lower molding layer;
• forming a stack of buffer layers on the upper molding lower, and wherein the buffer layers comprise layers of the same types of materials as those of the upper and lower molding layers, respectively, such that one of the buffer layers has an etch selectivity with respect to another of the buffer layers;
• selectively etching the upper molding layer, the lower molding layer and the etch stop layer to form a hole that exposes the pad, including by:
• patterning the buffer layers,
• selectively etching the upper molding layer using a first etchant that has an etch selectivity with respect to the lower molding layer, and wherein said one of the patterned buffer layers is etched by the first etchant, and
• selectively etching the lower molding layer with a second etchant different from the first after said one of the patterned buffer layers has been etched by the first etchant, and wherein said another of the patterned buffer layers is etched by the first etchant;
• forming a first electrode in the hole after the hole has been extended to expose the pad;
• after the first electrode is formed, removing the upper molding layer with a third etchant of the same type as the first etchant to form a space that exposes a part of a side surface of the first electrode;
• subsequently removing the lower molding layer with a fourth etchant of the same type as the second etchant to expand the space such that the expanded space also exposes another part of the side surface of the first electrode;
• forming a dielectric layer on the exposed parts of the side surface of the first electrode;
• and
• forming a second electrode on the dielectric layer.