Metal cap protection layer for gate and contact metallization
First Claim
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1. A method comprising:
- forming a sacrificial gate on a semiconductor substrate;
forming spacers on sidewalls of the sacrificial gate, the spacers having top surfaces;
removing the sacrificial gate, thereby forming a trench bounded by the spacers;
forming a gate dielectric layer within the trench;
forming a first barrier layer on the gate dielectric layer;
forming a cobalt gate on the first barrier layer;
forming a first metal cap layer sealing the cobalt gate, the first metal cap layer being entirely within the trench and entirely beneath the top surfaces of the spacers, the first metal cap layer being less chemically reactive than the cobalt gate;
forming a dielectric cap within the trench and on the first metal cap layer; and
forming an interconnect layer on the substrate by;
forming a dielectric layer on the substrate;
forming pathways within the dielectric layer;
forming a second barrier layer lining the pathways;
forming a cobalt layer within the pathways and on the second barrier layer, andforming a second metal cap layer directly contacting and sealing the cobalt layer, the second metal cap layer being less chemically reactive than the cobalt layer.
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Abstract
A CMOS fabrication process provides metal gates and contact metallization protected by metal cap layers resistant to reagents employed in downstream processing. Cobalt gates and contact metallization are accordingly feasible in CMOS processing requiring downstream wet cleans and etch processes that would otherwise compromise or destroy them. Low resistivity metal cap materials can be employed.
72 Citations
20 Claims
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1. A method comprising:
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forming a sacrificial gate on a semiconductor substrate; forming spacers on sidewalls of the sacrificial gate, the spacers having top surfaces; removing the sacrificial gate, thereby forming a trench bounded by the spacers; forming a gate dielectric layer within the trench; forming a first barrier layer on the gate dielectric layer; forming a cobalt gate on the first barrier layer; forming a first metal cap layer sealing the cobalt gate, the first metal cap layer being entirely within the trench and entirely beneath the top surfaces of the spacers, the first metal cap layer being less chemically reactive than the cobalt gate; forming a dielectric cap within the trench and on the first metal cap layer; and forming an interconnect layer on the substrate by; forming a dielectric layer on the substrate; forming pathways within the dielectric layer; forming a second barrier layer lining the pathways; forming a cobalt layer within the pathways and on the second barrier layer, and forming a second metal cap layer directly contacting and sealing the cobalt layer, the second metal cap layer being less chemically reactive than the cobalt layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 19, 20)
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12. A semiconductor structure comprising:
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a semiconductor substrate; a plurality of gate structures on the substrate, each gate structure including; a pair of spacers defining a trench, the spacers including top surfaces, a cobalt gate within the trench, a gate dielectric layer between the semiconductor substrate and the cobalt gate, a barrier layer between the gate dielectric layer and the cobalt gate, a first metal cap layer sealing the cobalt gate, the first metal cap layer being positioned entirely beneath the top surfaces of the spacers and being less chemically reactive than the cobalt gate, and a dielectric cap within the trench and on the first metal cap layer; a dielectric layer on the substrate; and a plurality of contact structures within the dielectric layer, each of the contact structures including; a pathway within the dielectric layer, a second barrier layer lining the pathway, a cobalt layer directly contacting the second barrier layer and recessed within the pathway, and a second metal cap layer directly contacting and sealing the cobalt layer, the second metal cap layer being less chemically reactive than the cobalt layer. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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Specification