Replacement gate process for making a semiconductor device that includes a metal gate electrode
First Claim
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1. A method for making a semiconductor device comprising:
- forming a dielectric layer on a substrate;
forming a polysilicon layer on the dielectric layer; and
etching the polysilicon layer to generate a patterned polysilicon layer that has an upper surface and a lower surface, the upper surface having a first width that is less than or equal to about 45 angstroms and the lower surface having a second width that is less than or equal to about 40 angstroms;
wherein the first width is at least about 5 angstroms greater than the second width.
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Abstract
A method for making a semiconductor device is described. That method comprises forming a polysilicon layer on a dielectric layer, which is formed on a substrate. The polysilicon layer is etched to generate a patterned polysilicon layer with an upper surface that is wider than its lower surface. The method may be applied, when using a replacement gate process to make transistors that have metal gate electrodes.
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Citations
20 Claims
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1. A method for making a semiconductor device comprising:
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forming a dielectric layer on a substrate;
forming a polysilicon layer on the dielectric layer; and
etching the polysilicon layer to generate a patterned polysilicon layer that has an upper surface and a lower surface, the upper surface having a first width that is less than or equal to about 45 angstroms and the lower surface having a second width that is less than or equal to about 40 angstroms;
wherein the first width is at least about 5 angstroms greater than the second width. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for making a semiconductor device comprising:
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forming a silicon dioxide layer on a substrate;
forming on the silicon dioxide layer a polysilicon layer that is between about 100 and about 2,000 angstroms thick;
forming a first silicon nitride layer that is between about 100 angstroms and about 500 angstroms thick on the polysilicon layer;
etching the first silicon nitride layer to create a hard mask; and
etching the polysilicon layer to generate a patterned polysilicon layer that has an upper surface and a lower surface, the upper surface having a first width that is less than or equal to about 45 angstroms, and the lower surface having a second width that is less than or equal to about 40 angstroms;
wherein the first width is at least about 5 angstroms greater than the second width. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method for making a semiconductor device comprising:
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forming a nitrided silicon dioxide layer on a substrate;
forming on the nitrided silicon dioxide layer a polysilicon layer that is between about 100 and about 2,000 angstroms thick;
forming a first silicon nitride layer that is between about 100 and about 500 angstroms thick on the polysilicon layer;
etching the first silicon nitride layer, the polysilicon layer, and the nitrided silicon dioxide layer, to form a hard mask, a patterned polysilicon layer, and a patterned nitrided silicon dioxide layer;
depositing a second silicon nitride layer on the substrate, the hard mask and on opposite sides of the patterned polysilicon layer;
removing the second silicon nitride layer from part of the substrate and from the hard mask to form first and second spacers on opposite sides of the patterned polysilicon layer;
forming a dielectric layer on the hard mask and on the substrate;
removing the dielectric layer from the hard mask;
removing the hard mask, the patterned polysilicon layer and the patterned nitrided silicon dioxide layer to generate a trench that is positioned between the first and second spacers;
forming a high-k gate dielectric layer on the substrate at the bottom of the trench; and
filling at least part of the trench with a metal layer that is formed on the high-k gate dielectric layer;
wherein the nitrided silicon dioxide layer maintains an electric charge for substantially the entire time that the polysilicon layer is etched. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification