Metal oxide stack for flash memory application
First Claim
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1. A method of manufacturing a semiconductor device comprising a gate structure, the method comprising:
- forming a polysilicon layer on a tunnel oxide layer;
forming an interpoly dielectric layer over the polysilicion layer;
forming a tungsten layer on the polysilicon layer; and
forming a tungsten silicide layer on the tungsten layer.
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Abstract
In order to alleviate lifting problems and to reduce the height of the stack, a tungsten layer is formed on a interpoly dielectric layer, such as an ONO layer, which separates the conductive control gate from a polysilicon floating gate that is in turn formed on a tunnel oxide layer. The tungsten layer is protected by the provision of a tungsten silicide cap which is formed over the tungsten layer and which therefore prevents oxidation of the metal. The two tungsten based layers are such as to replace the second polysilicon layer which is normally used to form the floating gate.
28 Citations
8 Claims
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1. A method of manufacturing a semiconductor device comprising a gate structure, the method comprising:
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forming a polysilicon layer on a tunnel oxide layer; forming an interpoly dielectric layer over the polysilicion layer; forming a tungsten layer on the polysilicon layer; and forming a tungsten silicide layer on the tungsten layer. - View Dependent Claims (2, 3)
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4. A semiconductor device having a gate comprising:
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a tunnel oxide layer formed on a main surface of a substrate; a polysilicon layer formed on the tunnel oxide layer; an interpoly dielectric layer formed over the polysilicion layer; a tungsten layer formed on the polysilicon layer; and a tungsten silicide layer formed on the tungsten layer. - View Dependent Claims (5, 6, 7, 8)
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Specification