Semiconductor structures employing strained material layers with defined impurity gradients and methods for fabricating same
First Claim
Patent Images
1. A semiconductor structure comprising:
- a substrate; and
at least one strained layer disposed on the substrate, thereby defining an interface therebetween, the at least one strained layer having a distal zone away from the interface;
wherein the substrate, the interface, and the at least one strained layer are characterized at least in part by an impurity gradient having a value substantially equal to zero in the distal zone.
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Abstract
Semiconductor structures and devices including strained material layers having impurity-free zones, and methods for fabricating same. Certain regions of the strained material layers are kept free of impurities that can interdiffuse from adjacent portions of the semiconductor. When impurities are present in certain regions of the strained material layers, there is degradation in device performance. By employing semiconductor structures and devices (e.g., field effect transistors or “FETs”) that have the features described, or are fabricated in accordance with the steps described, device operation is enhanced.
262 Citations
62 Claims
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1. A semiconductor structure comprising:
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a substrate; and
at least one strained layer disposed on the substrate, thereby defining an interface therebetween, the at least one strained layer having a distal zone away from the interface;
wherein the substrate, the interface, and the at least one strained layer are characterized at least in part by an impurity gradient having a value substantially equal to zero in the distal zone. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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- 16. A FET fabricated in a semiconductor substrate, the FET comprising a channel region including at least one strained channel layer, the at least one strained channel layer having a distal zone away from the substrate, wherein the substrate and the channel region are characterized at least in part by an impurity gradient having a value substantially equal to zero in the distal zone.
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31. A method for fabricating a semiconductor structure in a substrate, the method comprising the steps of:
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disposing at least one strained layer on the substrate thereby defining an interface therebetween, the at least one strained layer having a distal zone away from the interface; and
performing at least one subsequent processing step on the substrate after which an impurity gradient characterizing, at least in part, the substrate, the interface, and the at least one strained layer has a value substantially equal to zero in the distal zone. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46)
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47. A method for fabricating a FET in a semiconductor substrate, the FET comprising a channel region, the method comprising the steps of:
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disposing at least one strained channel layer in at least the channel region, the at least one strained channel layer having a distal zone away from the substrate; and
performing at least one subsequent processing step on the substrate after which an impurity gradient characterizing, at least in part, the substrate and the at least one strained layer has a value substantially equal to zero in the distal zone. - View Dependent Claims (48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62)
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Specification