Semiconductor structure with reduced junction leakage and method of fabrication thereof
First Claim
1. A method for forming a semiconductor structure, comprising:
- providing a substrate;
forming a first masking layer for a first device area of the substrate;
epitaxially growing a first layer for a first field effect transistor, the first layer having a defined dopant concentration and grown to a preselected thickness;
epitaxially growing a second layer for the first field effect transistor on the first layer, the second layer having a preselected dopant concentration and grown to a preselected thickness;
removing the first masking layer for the first device area of the substrate;
forming a second masking layer for a second device area of the substrate;
epitaxially growing a first layer for a second field effect transistor, said first layer for the second field effect transistor having a defined dopant concentration and grown to a preselected thickness;
epitaxially growing a second layer for the second field effect transistor on the first layer for the second field effect transistor, the second layer for the second field effect transistor having a preselected dopant concentration and a preselected thickness;
removing the second masking layer for the second device area of the substrate;
wherein at least some of the epitaxially grown layers form facets at edges of the first and second masking layers, the facets being eliminated by forming an isolation region in an area of the facets, the isolation region isolating the first field effect transistor from the second field effect transistor.
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Abstract
A semiconductor structure is formed with a NFET device and a PFET device. The NFET device is formed by masking the PFET device regions of a substrate, forming a screen layer through epitaxial growth and in-situ doping, and forming an undoped channel layer on the screen layer through epitaxial growth. The PFET device is similarly formed by masking the NFET regions of a substrate, forming a screen layer through epitaxial growth and in-situ doping, and forming an undoped channel layer on the screen layer through epitaxial growth. An isolation region is formed between the NFET and the PFET device areas to remove any facets occurring during the separate epitaxial growth phases. By forming the screen layer through in-situ doped epitaxial growth, a reduction in junction leakage is achieved versus forming the screen layer using ion, implantation.
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Citations
20 Claims
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1. A method for forming a semiconductor structure, comprising:
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providing a substrate; forming a first masking layer for a first device area of the substrate; epitaxially growing a first layer for a first field effect transistor, the first layer having a defined dopant concentration and grown to a preselected thickness; epitaxially growing a second layer for the first field effect transistor on the first layer, the second layer having a preselected dopant concentration and grown to a preselected thickness; removing the first masking layer for the first device area of the substrate; forming a second masking layer for a second device area of the substrate; epitaxially growing a first layer for a second field effect transistor, said first layer for the second field effect transistor having a defined dopant concentration and grown to a preselected thickness; epitaxially growing a second layer for the second field effect transistor on the first layer for the second field effect transistor, the second layer for the second field effect transistor having a preselected dopant concentration and a preselected thickness; removing the second masking layer for the second device area of the substrate; wherein at least some of the epitaxially grown layers form facets at edges of the first and second masking layers, the facets being eliminated by forming an isolation region in an area of the facets, the isolation region isolating the first field effect transistor from the second field effect transistor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A semiconductor structure, comprising:
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a substrate; a first field effect transistor formed on the substrate, the first field effect transistor comprising; a first screen layer epitaxially grown on the substrate, the first screen layer having a first dopant and a first dopant concentration; a first channel layer epitaxially grown on the first screen layer, the first channel layer being undoped; a second field effect transistor, the second field effect transistor comprising; a second screen layer epitaxial grown on the substrate, the second screen layer having a second dopant and a second dopant concentration; a second channel layer epitaxially grown on the second screen layer, the second channel layer being undoped; and an isolation region separating the first field effect transistor from the second field effect transistor, the isolation region being formed after the formation of the first and second screen layers and first and second channel layers for the first and second filed field effect transistors; wherein a thickness of the first channel layer for the first field effect transistor is different than a thickness of the second channel layer for the second field effect transistor. - View Dependent Claims (15, 16, 17, 18, 19)
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20. A semiconductor structure, comprising:
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a substrate; a first field effect transistor formed on the substrate, the first field effect transistor comprising; a first screen layer epitaxially grown on the substrate, the first screen layer having a first dopant and a first dopant concentration; a first channel layer epitaxially grown on the first screen layer, the first channel layer being undoped; a second field effect transistor, the second field effect transistor comprising; a second screen layer epitaxial grown on the substrate, the second screen layer having a second dopant and a second dopant concentration; a second channel layer epitaxially grown on the second screen layer, the second channel layer being undoped; and an isolation region separating the first field effect transistor from the second field effect transistor, the isolation region being formed after the formation of the first and second screen layers and first and second channel layers for the first and second field effect transistors; wherein the first screen layer or the second screen layer has a lower junction leakage due to epitaxial growth than a comparable ion implanted screen layer.
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Specification