Replacement Metal Gate with Capping Layer for Uniform Chamfering
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Solution Overview
Problem
In FinFET technologies, shorting of trench silicide to the metal gate material and workfunction chamfering issues occur due to different etching rates in long and short channel devices, leading to metal gate height non-uniformity and contact shorting problems.
Innovation Solution
The implementation of a structure comprising a conductive gate material with a capping layer extending over the sides for long channel devices and a separate capping material configuration for short channel devices, using spacer and workfunction metals, to prevent chamfering and ensure uniform metal gate height, along with specific fabrication processes to maintain the integrity of the workfunction metal within trenches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single capping layer configuration is used for both long and short channel devices, then the manufacturing process is simplified, but metal gate height non-uniformity occurs due to different etching rates
Solution Approach 1:
The patent applies different capping layer configurations to different device types (long channel vs. short channel devices) based on their specific etching rate characteristics. Long channel devices receive a first capping layer configuration while short channel devices receive a second configuration, ensuring each device type achieves optimal metal gate height uniformity according to its local etching behavior.
2Productivity
If contact trench silicide spacing is reduced to increase device density, then productivity is improved, but shorting between trench silicide and metal gate material increases
Solution Approach 1:
The patent introduces a spacer material as an intermediary layer between the contact trench silicide and the metal gate material. This spacer prevents direct contact and potential shorting between these conductive elements, enabling reduced spacing between trenches while maintaining electrical isolation and preventing shorts.
3Adaptability or versatility
If different etching rates are utilized for long and short channel devices, then device optimization is improved, but workfunction chamfering differences occur
Solution Approach 1:
The patent applies different capping layer configurations specifically tailored to the etching rate characteristics of long versus short channel devices. This local differentiation allows each device type to be optimized for its specific etching behavior while the capping layers work to minimize chamfering effects, achieving a balance between device optimization and chamfering control.
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to replacement metal gate structures with reduced shorting and uniform chamfering, and methods of manufacture. The structure includes: a long channel device composed of a conductive gate material with a capping layer over the conductive gate material and extending to sides of the conductive gate material; and a short channel device composed of the conductive gate material and the capping layer over the conductive gate material.