LDMOS using a combination of enhanced dielectric stress layer and dummy gates
First Claim
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1. A method of fabrication of a semiconductor transistor comprising the steps of:
- providing a substrate with a deep well having dopants of a second dopant type;
forming a gate over the substrate, the gate having first and second sides and a channel under the gate;
forming a first junction region in the substrate on the first side of the gate, the first junction region having dopants of a first dopant type with a first dopant concentration;
forming a second junction region in the substrate on a second side of the gate adjacent the channel, the second junction region having dopants of the first type with a second dopant concentration, wherein the deep well comprises a depth deeper than the first and second junction regions, the deep well encompassing the first junction region and overlaps a portion of the second junction region without encompassing the second junction;
forming a third junction region in the substrate adjacent the second junction region and spaced apart from the second side of the gate, the third junction region having dopants of the first type with a third dopant concentration, the second dopant concentration of the second junction region is less than the first and third dopant concentration of the first and third junction regions;
forming at least one dummy gate over the second junction region; and
forming a stress layer over the substrate and over the gate and at least one dummy gate, the stress layer creates a stress in the channel and in the second junction region, wherein the dummy gate is arranged to assist in distributing the stress of the stress layer over the second and third junctions to increase the stress exerted across the second junction region as compared to that without the at least one dummy gate to improve performance of the transistor.
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Abstract
First example embodiments comprise forming a stress layer over a MOS transistor (such as a LDMOS Tx) comprised of a channel and first, second and third junction regions. The stress layer creates a stress in the channel and the second junction region of the Tx. Second example embodiments comprises forming a MOS FET and at least a dummy gate over a substrate. The MOS is comprised of a gate, channel, source, drain and offset drain. At least one dummy gate is over the offset drain. A stress layer is formed over the MOS and the dummy gate. The stress layer and the dummy gate improve the stress in the channel and offset drain region.
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Citations
44 Claims
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1. A method of fabrication of a semiconductor transistor comprising the steps of:
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providing a substrate with a deep well having dopants of a second dopant type; forming a gate over the substrate, the gate having first and second sides and a channel under the gate; forming a first junction region in the substrate on the first side of the gate, the first junction region having dopants of a first dopant type with a first dopant concentration; forming a second junction region in the substrate on a second side of the gate adjacent the channel, the second junction region having dopants of the first type with a second dopant concentration, wherein the deep well comprises a depth deeper than the first and second junction regions, the deep well encompassing the first junction region and overlaps a portion of the second junction region without encompassing the second junction; forming a third junction region in the substrate adjacent the second junction region and spaced apart from the second side of the gate, the third junction region having dopants of the first type with a third dopant concentration, the second dopant concentration of the second junction region is less than the first and third dopant concentration of the first and third junction regions; forming at least one dummy gate over the second junction region; and forming a stress layer over the substrate and over the gate and at least one dummy gate, the stress layer creates a stress in the channel and in the second junction region, wherein the dummy gate is arranged to assist in distributing the stress of the stress layer over the second and third junctions to increase the stress exerted across the second junction region as compared to that without the at least one dummy gate to improve performance of the transistor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of fabrication of a metal-oxide-semiconductor device;
- comprising the steps of;
providing a substrate with a deep well having dopants of a second dopant type; forming a gate over the substrate, the gate having first and second sides and a channel under the gate; forming a source in the substrate proximate the first side of the gate;
the source having dopants of a first dopant type with a first dopant concentration;forming a body sinker in the substrate spaced apart from the first side of the gate; forming an offset drain region in the substrate adjacent the second side of the gate;
the offset drain region having dopants of the first type with a second dopant concentration, wherein the deep well comprises a depth deeper than the source and offset drain regions, the deep well encompassing the source and overlaps a portion of the offset drain region without encompassing the offset drain region;forming a drain in the substrate adjacent the offset drain region and spaced apart from the second side of the gate, the drain having dopants of the first type with a third dopant concentration, the second dopant concentration of the offset drain being less than the first and third dopant concentration of the source and drain; forming at least one dummy gate over the offset drain region; and forming a stress layer over the substrate and over the gate and the at least one dummy gate, wherein the dummy gate is arranged to assist in distributing the stress of the stress layer over the offset drain region and the drain to increase the stress exerted across the offset drain region as compared to that without the at least one dummy gate to improve performance of the device. - View Dependent Claims (12, 13, 14, 15, 16, 17)
- comprising the steps of;
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18. A method of fabricating a semiconductor device comprises:
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providing a substrate with a deep well having dopants of a second dopant type; forming a transistor gate over a surface of the substrate with a channel beneath the gate; forming a first junction region in the substrate on a first side of the gate, the first junction region having dopants of a first dopant type with a first dopant concentration; forming a second junction region in the substrate on a second side of the gate adjacent to the channel, the second junction region having dopants of the first type with a second dopant concentration, wherein the deep well comprises a depth deeper than the first and second junction regions, the deep well encompassing the first junction region and overlaps a portion of the second junction region without encompassing the second junction; forming at least one dummy gate over the substrate within the second junction region; and forming a stress layer over the substrate and over the gate and the at least one of the dummy gate, wherein the stress layer provides a first type stress in the channel and in the second junction region, wherein the dummy gate is arranged to assist in distributing the stress of the stress layer over the second junction to increase the stress exerted across the second junction region as compared to that without the at least one dummy gate to improve performance of the device. - View Dependent Claims (19, 20)
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21. A method of forming a device comprising:
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providing a substrate with a deep well having dopants of a second dopant type, wherein the device region is prepared with a gate on the substrate with a channel region below the gate, a first junction region adjacent to and on a first side of the gate, the first junction region comprising a first dopant type having a first dopant concentration, a second junction region adjacent to and on a second side of the gate, the second junction region comprising the first dopant type having a second dopant concentration which is lower than the first dopant concentration, wherein the deep well comprises a depth deeper than the first and second junction regions, the deep well encompassing the first junction region and overlaps a portion of the second junction region without encompassing the second junction, a third junction region adjacent on the second side of the gate and separated from the gate by the second junction region, wherein the third junction region comprises the first dopant type having a third dopant concentration which is greater than the second dopant concentration, and at least one dummy gate disposed on the substrate over the second junction region; and forming a stress layer over the substrate and the at least one dummy gate, the stress layer exerts a stress in the channel, wherein the at least one dummy gate is arranged to assist in distributing the stress of the stress layer over the second and third junctions to increase the stress exerted across the second junction region as compared to that without the at least one dummy gate to improve performance of the device. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44)
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Specification