Pre-gate dielectric process using hydrogen annealing
First Claim
1. A method of forming a semiconductor structure, the method comprising:
- forming trench isolation regions extending from a top surface of a semiconductor substrate into the semiconductor substrate, wherein the trench isolation regions define a first active region and a second active region;
forming a first gate dielectric over the semiconductor substrate in the first active region;
forming a convex surface of the top surface of the semiconductor substrate in the second active region by performing a hydrogen anneal on the semiconductor substrate in an ambient containing hydrogen while the top surface of the semiconductor substrate in the second active region is exposed, the convex surface being between a first source/drain region of the second active region and a second source/drain region of the second active region, a curvature of the convex surface being convex in a direction from the first source/drain region to the second source/drain region; and
forming a second gate dielectric over the convex surface in the second active region.
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Abstract
The preferred embodiment of the present invention provides a novel method of forming MOS devices using hydrogen annealing. The method includes providing a semiconductor substrate including a first region and a second region, forming at least a portion of a first MOS device covering at least a portion of the first active region, performing a hydrogen annealing in an ambient containing substantially pure hydrogen on the semiconductor substrate. The hydrogen annealing is performed after the step of the at least a portion of the first MOS device is formed, and preferably after a pre-oxidation cleaning. The method further includes forming a second MOS device in the second active region after hydrogen annealing. The hydrogen annealing causes the surface of the second active region to be substantially rounded, while the surface of the first active region is substantially flat.
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Citations
21 Claims
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1. A method of forming a semiconductor structure, the method comprising:
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forming trench isolation regions extending from a top surface of a semiconductor substrate into the semiconductor substrate, wherein the trench isolation regions define a first active region and a second active region; forming a first gate dielectric over the semiconductor substrate in the first active region; forming a convex surface of the top surface of the semiconductor substrate in the second active region by performing a hydrogen anneal on the semiconductor substrate in an ambient containing hydrogen while the top surface of the semiconductor substrate in the second active region is exposed, the convex surface being between a first source/drain region of the second active region and a second source/drain region of the second active region, a curvature of the convex surface being convex in a direction from the first source/drain region to the second source/drain region; and forming a second gate dielectric over the convex surface in the second active region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of forming a semiconductor structure, the method comprising:
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forming trench isolation regions extending from a top surface of a semiconductor substrate into the semiconductor substrate, wherein the trench isolation regions define a first active region and a second active region; after forming the trench isolation regions, forming a first gate dielectric over the semiconductor substrate in the first active region; forming a first gate electrode over the first gate dielectric; after the steps of forming the first gate dielectric and the first gate electrode, performing a hydrogen anneal on the semiconductor substrate in an ambient containing substantially pure hydrogen, wherein the top surface of the semiconductor substrate in the second active region forms a round surface having a curvature that extends from one trench isolation region across the entire second active region to another trench isolation region; after the step of performing the hydrogen anneal, forming a second gate dielectric over the round surface of the semiconductor substrate in the second active region such that the second gate dielectric is non-planar; and forming a second gate electrode over the second gate dielectric. - View Dependent Claims (16, 17, 18, 19, 20)
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21. A method of forming a semiconductor structure, the method comprising:
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forming trench isolation regions extending from a top surface of a semiconductor substrate into the semiconductor substrate, wherein the trench isolation regions define a first active region and a second active region; forming a first gate dielectric over the semiconductor substrate in the first active region; after forming the first gate dielectric, performing a hydrogen anneal on the semiconductor substrate in an ambient containing hydrogen while the top surface of the semiconductor substrate in the second active region is exposed, the hydrogen anneal rounding the top surface of the semiconductor substrate in the second active region between a first source/drain region of the second active region and a second source/drain region of the second active region, the rounding of the top surface of the semiconductor substrate in the second active region forming an arc of the top surface of the semiconductor substrate in a direction from the first source/drain region to the second source/drain region; and after performing the hydrogen anneal, forming a second gate dielectric over the top surface of the semiconductor substrate in the second active region, the second gate dielectric being disposed between the first source/drain region and the second source/drain region.
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Specification