Method of manufacturing EEPROM device
View Patent ↗A method of manufacturing an EEPROM device can reduce the cell area. The method of manufacturing an Electrically Erasable Programmable Read-Only Memory (EEPROM) includes forming a mask pattern over a semiconductor substrate; forming a gate oxide layer over a top of the semiconductor substrate exposed through the mask pattern; forming access gates which are self-aligned with both side walls of the mask pattern, over a top of the gate oxide layer; removing the mask pattern; forming first dielectric spacers to be attached to side walls of the access gates; forming an insulating layer adapted to cover the access gates and the first dielectric spacers; and forming two cell gates, which are self-aligned with opposite side walls of the two access gates, respectively, each first dielectric spacer being interposed between a corresponding cell gate and a corresponding access gate, the cell gates separately arranged over a top of the insulating layer.
1. A method comprising:
forming a mask pattern over a semiconductor substrate;
forming a gate oxide layer over a top of the semiconductor substrate exposed through the mask pattern;
forming access gates which are self-aligned with both side walls of the mask pattern, over a top of the gate oxide layer;
removing the mask pattern;
forming first dielectric spacers to be attached to side walls of the access gates;
forming an insulating layer adapted to cover the access gates and the first dielectric spacers; and
forming two cell gates, which are self-aligned with opposite side walls of the two access gates, respectively, each first dielectric spacer being interposed between a corresponding cell gate and a corresponding access gate, said cell gates separately arranged over a top of the insulating layer.
2. The method of claim 1 , wherein the method further comprises, after forming the two cell gates, selectively removing an exposed portion of the insulating layer using the cell gates as an etching mask.
3. The method of claim 2 , wherein the method further comprises, after selectively removing the exposed portion of the insulating layer, forming source and drain junctions and an intermediate transfer node junction on portions of the semiconductor substrate which are exposed through the access gates and the cell gates, through ion implantation.
4. The method of claim 1 , wherein the mask pattern is formed to include two distinct dielectric layers.
5. The method of claim 1 , wherein the forming the access gates comprises:
forming an access gate layer to cover the mask pattern;
forming a second spacer layer over a top of the access gate layer; and
etching back the second spacer layer and the access gate layer.
6. The method of claim 1 , wherein the forming the cell gates comprises:
forming a cell gate layer;
forming a third spacer layer over a top of the cell gate layer; and
etching back the third spacer layer and the cell gate layer.
7. The method of claim 1 , wherein the insulating layer is an Oxide-Nitride-Oxide (ONO) layer.
8. The method of claim 1 , wherein the method is a method of manufacturing an Electrically Erasable Programmable Read-Only Memory (EEPROM) device.