Transistor, method of manufacturing same, etchant for use during manufacture of same, and system containing same
A transistor comprises a gate ( 110 ) comprising a gate electrode ( 111 ) and a gate dielectric ( 112 ), an electrically insulating cap ( 120, 720 ) over the gate, and a source/drain contact ( 130 ) adjacent to the gate. The electrically insulating cap prevents electrical contact between the gate and the source/drain contact. In one embodiment, the electrically insulating cap is formed in a trench ( 160, 660 ) that is self-aligned to the gate and that is created by the removal of a sacrificial cap using an aqueous solution comprising a carboxylic acid and a corrosion inhibitor.
1. A method of manufacturing a transistor having a metal gate, the method comprising:
forming an etch stop layer over the metal gate; and
forming a source/drain contact adjacent to the metal gate,
wherein:
forming the etch stop layer comprises:
aligning the etch stop layer to the metal gate;
forming a first capping layer over the metal gate;
forming an electrically insulating layer over the first capping layer;
exposing the first capping layer by removing a portion of the electrically insulating layer;
removing the first capping layer to form a trench aligned to the metal gate; and
filling the trench with an electrically insulating cap; and
the etch stop layer prevents a formation of an electrical connection between the metal gate and the source/drain contact.
2. The method of claim 1 wherein:
the metal gate is a copper gate; and
forming the first capping layer comprises forming a layer comprising cobalt.
3. The method of claim 2 wherein:
removing the first capping layer comprises etching the first capping layer using an etchant that is an aqueous solution comprising a carboxylic acid and a corrosion inhibitor.
4. The method of claim 3 wherein:
the carboxylic acid is an α-hydroxy acid comprising no more than approximately 50 percent of the aqueous solution; and
the corrosion inhibitor comprises no greater than approximately 0.2 percent of the aqueous solution.
5. The method of claim 1 wherein:
forming the first capping layer comprises electrolessly depositing the first capping layer.