Profile of flash memory cells
First Claim
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1. A method comprising:
- forming a tunneling layer over a semiconductor substrate;
forming a source region adjacent the tunneling layer;
forming a floating gate over the tunneling layer;
forming a blocking layer over the floating gate, wherein the blocking layer has a first edge facing a same direction as a first edge of the floating gate;
forming a control gate over the blocking layer; and
recessing the first edge of the blocking layer until the first edge of the blocking layer is recessed from an edge of the control gate facing the same direction.
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Abstract
A semiconductor structure includes a semiconductor substrate; a tunneling layer on the semiconductor substrate; a source region adjacent the tunneling layer; and a floating gate on the tunneling layer. The floating gate comprises a first edge having an upper portion and a lower portion, wherein the lower portion is recessed from the upper portion. The semiconductor structure further includes a blocking layer on the floating gate, wherein the blocking layer has a first edge facing a same direction as the first edge of the floating gate.
22 Citations
19 Claims
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1. A method comprising:
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forming a tunneling layer over a semiconductor substrate; forming a source region adjacent the tunneling layer; forming a floating gate over the tunneling layer; forming a blocking layer over the floating gate, wherein the blocking layer has a first edge facing a same direction as a first edge of the floating gate; forming a control gate over the blocking layer; and recessing the first edge of the blocking layer until the first edge of the blocking layer is recessed from an edge of the control gate facing the same direction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method comprising:
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forming shallow trench isolation (STI) regions in a semiconductor substrate, wherein the STI regions define; a strip of active region in the semiconductor substrate; and a connecting active region perpendicular to the strip of active region and separating the strip of active region into a first active region and a second active region; forming a first tunneling layer over the first active region and a second tunneling layer over the second active region; forming a first floating gate leg over the first tunneling layer; forming a second floating gate leg over the second tunneling layer; forming a connecting floating gate portion over the connecting active region and connecting the first and the second floating gate legs; and etching the connecting floating gate portion to form a first floating gate and a second floating gate, wherein each of the first floating gate and the second floating gate comprises a first edge facing the connecting active region, and wherein each of the first edges of the first floating gate and the second floating gate comprise a lower portion and an upper portion, with the lower portion recessed from the upper portion. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A method comprising:
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forming a tunneling layer over a semiconductor substrate; forming a source region adjacent the tunneling layer; forming a floating gate over the tunneling layer; forming a blocking layer over the floating gate; forming a control gate over the blocking layer; and over-etching an edge of the floating gate and an edge of the blocking layer facing a same direction until the edge of the blocking layer is recessed from an edge of the control gate facing the same direction and until the edge of the floating gate is recessed from the edge of the blocking layer. - View Dependent Claims (17, 18, 19)
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Specification