Memory cell with recessed source/drain contacts to reduce capacitance
A method includes forming a device above an active region defined in a semiconducting substrate. The device includes a plurality of gate structures, a spacer formed adjacent each of the plurality of gate structures, and conductive source/drain contact structures positioned adjacent each of the plurality of gate structures and separated from the associated gate structure by the spacer. A first portion of the conductive source/drain contact structures of a subset of the plurality of gate structures is recessed at a first axial position along a selected gate structure of the plurality of gate structures to define a cavity. A selected source/drain contact structure is not recessed. A first dielectric layer is formed in the cavity. A conductive line contacting the selected source/drain contact structure in the first axial position is formed.
1. A method, comprising:
forming a device above an active region defined in a semiconducting substrate, said device comprising a plurality of gate structures, a spacer formed adjacent each of said plurality of gate structures, and conductive source/drain contact structures positioned adjacent each of said plurality of gate structures and separated from an associated gate structure by said spacer;
recessing a first portion of said conductive source/drain contact structures of a subset of said plurality of gate structures at a first axial position along a selected gate structure of said plurality of gate structures to define a cavity, wherein a selected source/drain contact structure is not recessed;
forming a first dielectric layer in said cavity; and
forming a conductive line contacting said selected source/drain contact structure in said first axial position.
2. The method of claim 1 , wherein said conductive line has a first axial length in a direction perpendicular to a second axial length of said selected source/drain contact structure.
3. The method of claim 1 , further comprising:
forming a second dielectric layer above said conductive source/drain contact structures;
forming a trench in said second dielectric layer exposing said selected source/drain contact structure; and
forming said conductive line in the trench.
4. The method of claim 3 , further comprising recessing said selected source/drain contact structure after forming said first dielectric layer and prior to forming said conductive line.
5. The method of claim 1 , wherein said plurality of gate structures comprise a portion of a static random access memory (SRAM) cell.
6. The method of claim 5 , wherein said selected gate structure and said selected source/drain contact structure is associated with a pass gate transistor in said SRAM cell, and said conductive line comprises a bit line of said SRAM cell.
7. The method of claim 6 , wherein said subset of said plurality of gate structures are associated with a pull-down transistor in said SRAM cell.
8. The method of claim 6 , wherein said subset of said plurality of gate structures are associated with a pull-up transistor in said SRAM cell.
9. The method of claim 1 , wherein said first dielectric layer comprises a low-k dielectric.
10. The method of claim 1 , wherein a remaining portion of said recessed first portion of said conductive source/drain contact structures has a thickness less than half of an original thickness of said conductive source/drain contact structures.
11. A method, comprising:
forming a static random access memory (SRAM) device above an active region defined in a semiconducting substrate, said SRAM device comprising a plurality of gate structures including a first gate structure associated with a first pass gate transistor and a second gate structure associated with one of a pull-up transistor or a pull-down transistor, and conductive source/drain contact structures positioned adjacent each of said plurality of gate structures;
recessing a first portion of said conductive source/drain contact structure associated with said one of said pull-up transistor or said pull-down transistor at a first axial position along a first gate structure to define a cavity;
forming a first dielectric layer in said cavity; and
forming a conductive line contacting said source/drain contact structure of said one of said pull-up transistor or said pull-down transistor in said first axial position.
12. The method of claim 11 , wherein said conductive line has a first axial length in a direction perpendicular to a second axial length of said source/drain contact structure of said one of said pull-up transistor or said pull-down transistor.
13. The method of claim 11 , further comprising:
forming a second dielectric layer above said conductive source/drain contact structures;
forming a trench in said second dielectric layer exposing said source/drain contact structure of said one of said pull-up transistor or said pull-down transistor; and
forming said conductive line in said trench.
14. The method of claim 13 , further comprising recessing said source/drain contact structure of said one of said pull-up transistor or said pull-down transistor after forming said first dielectric layer and prior to forming said conductive line.
15. The method of claim 11 , wherein said first dielectric layer comprises a low-k dielectric.
16. The method of claim 11 , wherein a remaining portion of said recessed first portion of said conductive source/drain contact structure associated with said one of said pull-up transistor or said pull-down transistor has a thickness less than half of its thickness prior to said recessing.