| US 7,507,626 B2 | ||
| Floating gate of flash memory device and method of forming the same | ||
| Chang Hun Han, Icheon-si (Korea, Republic of) | ||
| Assigned to Dongbu Electronics Co., Ltd., Seoul (Korea, Republic of) | ||
| Filed on Dec. 27, 2006, as Appl. No. 11/647,021. | ||
| Claims priority of application No. 10-2005-0132652 (KR), filed on Dec. 28, 2005. | ||
| Prior Publication US 2007/0145461 A1, Jun. 28, 2007 | ||
| Int. Cl. H01L 21/336 (2006.01) | ||
| U.S. Cl. 438—257 [438/207; 438/261; 438/266; 438/303; 257/E21.209] | 13 Claims |
| 1. A method of forming a floating gate in a flash memory device, the method comprising the steps of:
forming a tunneling oxide layer on a semiconductor substrate;
forming a conductive layer on the tunneling oxide layer;
coating a photoresist layer on the conductive layer and then selectively patterning the photoresist layer, thereby defining
a floating gate area;
selectively removing a predetermined thickness of a top surface of the conductive layer using the patterned photoresist layer
as a mask;
reflowing the photoresist layer into a lens shape having a convex top surface;
simultaneously etching the reflowed photoresist layer and the conductive layer, thereby forming a floating gate with a convex
top surface;
forming a gate oxide on the floating gate; and
forming a concave control gate on the gate oxide.
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