| CPC H01L 29/41766 (2013.01) [H01L 21/823814 (2013.01); H01L 29/0665 (2013.01); H01L 29/42392 (2013.01)] | 18 Claims |
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1. A method for forming heterogeneous complementary FETs using a compact stacked nanosheet process, the method comprising:
forming, on a first sacrificial layer and over a substrate, a first nanosheet stack comprising two layers made of a first channel material separated by a second sacrificial layer;
forming, over the first nanosheet stack, a second nanosheet stack comprising two layers made of a second channel material separated by a third sacrificial layer, wherein the first nanosheet stack and the second nanosheet stack form a nanosheet double stack;
wherein a fourth sacrificial layer separates the first and the second nanosheet stack, and wherein the first channel material is complementary to the second channel material;
forming a first source region and a first drain region, both being in direct contact with the two layers of the first channel material and the first and second sacrificial layer to build a first FET;
forming, over the first source region and the first drain region, a second source region and a second drain region, both being in direct contact with the two layers of the second channel material and the third and fourth sacrificial layer to build a second FET;
wherein:
the second source region is positioned over the first source region;
the second drain is positioned over the first drain region; and
at least one of the following two elements is true:
the first source and the second source are in direct contact; and
the first drain and the second drain are in direct contact;
the method further comprising:
removing, selectively, the first, the second, the third, and the fourth sacrificial layer by an etch process that is selective to the material of the first channel material and the second channel material, and that is not selective to the first, the second and the third sacrificial layer; and
forming a gate stack comprising a gate-all-around structure around the channels that replace the first, second, third, and fourth sacrificial layer;
wherein:
only one or none of the following two elements is true:
the first source region and the second source region are separated by an isolating layer;
the first drain and the second drain are separated by the isolating layer; and
further wherein:
the first nanosheet stack and the second nanosheet stack are separated by the isolating layer.
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