Sequential complimentary FET incorporating backside power distribution network through wafer bonding prior to formation of active devices
A semiconductor device includes backside power rails over a bulk semiconductor material, a first bonding dielectric layer over the backside power rails, a first tier of transistors over the first bonding dielectric layer, a second bonding dielectric layer over the first tier of transistors, and a second tier of transistors over the second bonding dielectric layer. The first tier of transistors includes first channel structures having a first epitaxially grown semiconductor material. The second tier of transistors includes second channel structures having a second epitaxially grown semiconductor material. The backside power rails are spaced apart from the first tier of transistors by the first bonding dielectric layer. The first tier of transistors is spaced apart from the second tier of transistors by the second bonding dielectric layer.
1 . A method of manufacturing a semiconductor device, the method comprising:
bonding a first wafer to a second wafer via a first bonding dielectric layer, the first wafer including a first bulk semiconductor material, the second wafer including a first stack of alternating layers of epitaxially grown semiconductor layers formed over a second bulk semiconductor material;
removing the second bulk semiconductor material to uncover the first stack;
forming a first tier of transistors from the first stack;
bonding a third wafer to the second wafer via a second bonding dielectric layer, the third wafer including a second stack of alternating layers of epitaxially grown semiconductor layers formed over a third bulk semiconductor material;
removing the third bulk semiconductor material;
forming a second tier of transistors from the second stack;
removing the first bulk semiconductor material to uncover the first bonding dielectric layer; and
forming a power delivery network in contact with the first bonding dielectric layer, the power delivery network including backside power rails in contact with vias that extend through the first bonding dielectric layer.
2 . The method of claim 1 , further comprising:
forming the backside power rails after forming the first tier of transistors and the second tier of transistors.
3 . The method of claim 1 , before bonding the third wafer to the second wafer, the method further comprising:
forming local interconnect (LI) structures connected to source/drain (S/D) structures of the first tier of transistors; and
forming at least one via that connects to a respective LI structure and extends through the first bonding dielectric layer.
4 . The method of claim 3 , further comprising:
forming a respective backside power rail in contact with the at least one via.
5 . The method of claim 3 , further comprising:
forming at least one via opening to uncover the first bulk semiconductor material;
partially filling the at least one via opening with a filler material;
forming LI openings including a respective LI opening which connects to the at least one via opening;
removing the filler material; and
filling the LI openings and the at least one via opening with a conductive material to form the LI structures and the at least one via.
6 . The method of claim 1 , after bonding the third wafer to the second wafer, the method further comprising:
forming LI structures connected to S/D structures of the second tier of transistors; and
forming at least one via that connects to a respective LI structure and extends through the second bonding dielectric layer and the first bonding dielectric layer.
7 . The method of claim 6 , further comprising:
forming a respective backside power rail in contact with the at least one via.
8 . The method of claim 6 , further comprising:
forming at least one via opening to uncover the first bulk semiconductor material;
partially filling the at least one via opening with a filler material;
forming LI openings including a respective LI opening which connects to the at least one via opening;
removing the filler material; and
filling the LI openings and the at least one via opening with a conductive material to form the LI structures and the at least one via.
9 . The method of claim 1 , further comprising:
forming at least one via that extends through the second bonding dielectric layer and is configured to electrically connect a first S/D structure of the first tier of transistors to a second S/D structure of the second tier of transistors.
10 . The method of claim 1 , further comprising:
forming a signal wiring layer over the second tier of transistors.
11 . The method of claim 10 , further comprising:
forming vias that connect the signal wiring layer to the first tier of transistors and the second tier of transistors.
12 . The method of claim 1 , before removing the first bulk semiconductor material to uncover the first bonding dielectric layer, the method further comprising:
bonding a carrier wafer to the third wafer.
13 . The method of claim 1 , after forming the power delivery network, the method further comprising:
bonding a carrier wafer to the backside power rails or forming a fourth bulk semiconductor material to cover the backside power rails.