Method for fabricating semiconductor device
First Claim
1. A method for fabricating semiconductor device, comprising:
- providing a substrate, wherein the substrate comprises a first device region and a second device region;
forming a floating gate structure in the first device region;
sequentially depositing a liner layer and a nitride layer over the first device region and the second device region, wherein the floating gate structure is conformally covered by the liner layer and the nitride layer;
performing an etching back process on the nitride layer to reduce a thickness of the nitride layer, wherein the first device region is still covered by the nitride layer;
forming a photomask layer over the substrate with an opening region to expose the second device region;
cleaning the second device region;
removing the photomask layer;
growing a gate oxide layer on the substrate in the second device region; and
performing an anisotropic etching process to remove the nitride layer, resulting in a nitride spacer on a lower portion of a sidewall of the floating gate structure.
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Abstract
A method for fabricating semiconductor device includes providing a substrate having a first device region and a second device region. Floating gate structure is formed in the first device region. Liner layer and nitride layer are sequentially deposited over the first device region and the second device region. The floating gate structure is conformally covered. Etching back process is performed on the nitride layer to reduce thickness of the nitride layer. The first device region is still covered by the nitride layer. A photomask layer is formed over the substrate with an opening region to expose the second device region for cleaning. The photomask layer is removed. A gate oxide layer grows on the substrate in the second device region. Anisotropic etching process is performed to remove the nitride layer, resulting in a nitride spacer on a lower portion of a sidewall of the floating gate structure.
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Citations
15 Claims
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1. A method for fabricating semiconductor device, comprising:
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providing a substrate, wherein the substrate comprises a first device region and a second device region; forming a floating gate structure in the first device region; sequentially depositing a liner layer and a nitride layer over the first device region and the second device region, wherein the floating gate structure is conformally covered by the liner layer and the nitride layer; performing an etching back process on the nitride layer to reduce a thickness of the nitride layer, wherein the first device region is still covered by the nitride layer; forming a photomask layer over the substrate with an opening region to expose the second device region; cleaning the second device region; removing the photomask layer; growing a gate oxide layer on the substrate in the second device region; and performing an anisotropic etching process to remove the nitride layer, resulting in a nitride spacer on a lower portion of a sidewall of the floating gate structure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A floating gate structure of semiconductor device, comprising:
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a floating gate structure on a substrate, wherein the floating gate structure comprises; a tunnel oxide layer on the substrate; a polysilicon layer on the tunnel oxide layer; and a polysilicon oxide layer on the polysilicon layer; a liner oxide layer on the substrate covering the floating gate structure; and a nitride spacer, on the liner oxide layer at a lower portion of a sidewall of the floating gate structure, wherein the tunnel oxide layer has a central region thickness and an edge thickness, and a thickness ratio of the edge thickness to the central region thickness is in a range of equal to or less than 1.7 and greater than 1. - View Dependent Claims (14, 15)
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Specification