Methods of fabricating self-aligned source of flash memory device
View Patent ↗Example methods of fabricating semiconductor devices are disclosed. One example method may include depositing an oxide layer, a first conducting layer for a floating gate, a dielectric layer, and a second conducting layer for a control gate in sequence on a semiconductor substrate including a device isolation layer; forming gates by removing some parts of the oxide layer, the first conducting layer, the dielectric layer, and the second conducting layer; forming a mask pattern for a self-aligned source over the substrate including the gates; removing the device isolation layer exposed between the gates; performing an ion implantation process; and eliminating damage generated during the ion implantation process or the removal of the device isolation layer.
1. A method of fabricating a semiconductor device comprising:
depositing an oxide layer, a first conducting layer for a floating gate, a dielectric layer, and a second conducting layer for a control gate in sequence on a semiconductor substrate including a device isolation layer;
forming gates by removing some part of the oxide layer, the first conducting layer, the dielectric layer, and the second conducting layer;
forming a mask pattern for a self-aligned source over the substrate including the gates;
removing the device isolation layer exposed between the gates;
performing an ion implantation process;
eliminating damage generated during the ion implantation process or the removal process of the device isolation layer by means of a chemical dry etching process;
washing the substrate from which the damage has been eliminated through a cleaning process; and
forming an insulating layer over the resulted substrate.
2. A method as defined by claim 1 , wherein the first aid the second conducting layers are formed of polysilicon.
3. A method as defined by claim 1 , wherein the dielectric layer is an oxide-nitride-oxide (ONO) layer.
4. A method as defined by claim 1 , wherein the device isolation layer is removed by means of dry etching.
5. A method as defined by claim 4 , wherein the dry etching is performed by applying a top power between 800 W and 1500 W under a pressure between 100 mTorr and 300 mTorr.
6. A method as defined by claim 4 , wherein the dry etching is performed using C 4 F 8 between 3 sccm and 5sccm, CHF 3 between 2 sccm and 6 sccm, O 2 between 1 sccm and 5 sccm, and Ar between 100 sccm and 300 sccm.
7. A method as defined by claim 1 , wherein the chemical dry etching process employs remote plasma in order to prevent ions from entering into a reaction chamber and to allow reaction only by radicals.
8. A method as defined by claim 1 , wherein the chemical dry etching is an isotropic etching.
9. A method as defined by claim 1 , wherein the chemical dry etching is preformed by applying microwave power between 300 W and 500 W under a pressure between 200 mTorr and 250 mTorr.
10. A method as defined by claim 1 , wherein the chemical dry etching is performed using CF 4 between 200 sccm and 280 sccm and O 2 between 40 sccm and 80 sccm.