Self-aligned gate contact
The disclosed technology generally relates to semiconductor devices, and more specifically to electrical contacts to a transistor device, and a method of making such electrical contacts. In one aspect, a method of forming one or more self-aligned gate contacts in a semiconductor device includes providing a substrate having formed thereon at least one gate stack, where the gate stack includes a gate dielectric and a gate electrode formed over an active region in or on the substrate, and where the substrate further has formed thereon a spacer material coating lateral sides of the at least one gate stack. The method additionally includes selectively recessing the gate electrode of the at least one gate stack against the spacer material, thereby creating a first set of recess cavities. The method additionally includes filling the first set of recess cavities with a dielectric material gate cap. The method additionally includes etching at least one via above the at least one gate stack and through the dielectric material gate cap, where etching the at least one via comprises selectively etching against the spacer material, thereby exposing the gate electrode. The method further includes forming, in the at least one via, a gate contact electrically connecting the gate electrode.
1. A method of forming one or more self-aligned gate contacts in a semiconductor device, the method comprising:
providing a substrate having formed thereon at least one gate stack extending in a first lateral direction, the gate stack comprising a gate dielectric and a gate electrode formed over an active region in or on the substrate, the substrate further having formed thereon a spacer material coating sides of the at least one gate stack opposing each other in a second lateral direction crossing the first lateral direction;
selectively recessing the gate electrode of the at least one gate stack against the spacer material, thereby creating a first set of recess cavities;
filling the first set of recess cavities with a dielectric material gate cap;
etching at least one via above the at least one gate stack and through the dielectric material gate cap, wherein selectively recessing the gate electrode and etching the at least one via comprise selectively etching against the same spacer material, thereby exposing the gate electrode;
forming, in the at least one via, a gate contact electrically connecting the gate electrode; and
removing a lateral portion of the at least one gate stack to separate the at least one gate stack in the first lateral direction and replacing the removed lateral portion with a dielectric material different from the spacer material.
2. The method according to claim 1 , wherein providing the substrate comprises:
providing the substrate having at least one sacrificial gate stack;
coating sides of the at least one sacrificial gate stack opposing each other in the second lateral direction with the spacer material;
removing the at least one sacrificial gate stack, thereby forming at least one gate cavity; and
filling the at least one gate cavity with a replacement gate stack.
3. The method according to claim 2 , further comprising providing active area electrodes aside the at least one gate stack coated with the spacer material.
4. The method according to claim 3 , the method including providing a plurality of neighboring gate stacks, wherein providing the active area electrodes comprises filling gaps between the neighboring gate stacks.
5. The method according to claim 3 , wherein providing the active area electrodes comprises providing a conductive material contacting active areas.
6. The method according to claim 3 , wherein providing the active area electrodes comprises:
providing a dielectric material at contact areas;
forming openings in the dielectric material; and
filling the openings with a conductive material.
7. The method according to claim 6 , furthermore comprising:
selectively recessing the active area electrodes with respect to the spacer material, thereby creating a second set of recess cavities;
filling the second set of recess cavities with a dielectric material active area cap;
etching at least one via above the active area, through the dielectric active area cap, selectively with respect to the spacer material, thereby exposing the active area electrode; and
forming an active area contact electrically connecting the active area electrode.
8. The method according to claim 7 , wherein a mask is provided prior to forming the openings in the dielectric material at the contact areas and is subsequently removed after forming the openings in the dielectric material, thereby allowing the openings in the dielectric material to be limited to subsections of the dielectric material.
9. The method according to claim 1 , further comprising, after filling the first set of recess cavities with the dielectric material gate cap, covering the substrate with one or more electrically insulating layers, such that etching the at least one via above the at least one gate stack comprises etching through the one or more electrically insulating layers and through the dielectric material gate cap.
10. The method according to claim 9 , further comprising, forming at least one gate contact in the at least one via, and forming at least one line of electrically conductive material in the one or more electrically insulating layers electrically contacting the at least one gate contact.
11. The method according to claim 10 , wherein covering the substrate with one or more electrically insulating layers includes applying an etch stop layer.
12. The method according to claim 11 , wherein covering the substrate with the one or more electrically insulating layers includes applying a low-K layer.
13. The method of claim 1 , wherein during etching the at least one via through the dielectric material gate cap, a top surface of the spacer material or an etch stop layer on the top surface of the spacer material is exposed.