Metal Gate Fin Electrode Structure for Lower Gate Resistance
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Solution Overview
Problem
As gate pitch shrinks in advanced technology nodes, self-aligned contacts in semiconductor devices increase the risk of unwanted electrical issues during etching, leading to increased gate resistance and challenges in controlling the gapfill area over fin gate electrodes.
Innovation Solution
A method is employed to form a gate contact by etching back a gate fill portion to create a fin gate electrode, which increases the surface area and reduces gate resistance, while controlling the height of a low-k dielectric layer to manage the gapfill area effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If self-aligned contacts are used to accommodate shrinking gate pitch, then integration density is improved, but gate resistance increases and electrical reliability deteriorates
Solution Approach 1:
The gate contact structure is segmented into multiple components: a wide base contact region for low resistance, a vertical electrode fin extending from the base, and a capping structure at the top. This segmentation allows each part to serve a specific function - the base provides electrical connection, the fin provides structural support and additional contact area, and the cap protects the electrode fin while enabling self-aligned formation.
Solution Approach 2:
The gate contact is extended into the vertical dimension by forming an electrode fin that protrudes upward from the contact region. This three-dimensional structure increases the effective contact surface area and provides multiple interfaces for electrical connection, thereby reducing gate resistance while maintaining the self-aligned configuration needed for high integration density.
2Reliability
If metal fill is deposited to form gate electrode, then gate resistance is reduced, but control over gapfill area becomes difficult
Solution Approach 1:
A sacrificial dummy gate structure is formed beforehand, extending beyond the actual gate region. This preliminary structure defines the boundaries for subsequent metal fill deposition, ensuring that the conductive material is deposited only in the desired gapfill area. The dummy gate acts as a mask and template, providing precise spatial control over where metal fill occurs.
Solution Approach 2:
The sacrificial dummy gate material is selectively removed after serving its purpose as a boundary definition during metal fill deposition. This extraction leaves behind precisely controlled gapfill areas where metal fill was deposited, while removing the temporary struct ure that enabled precise control during manufacturing.
3Reliability
If gate contact surface area is increased to reduce resistance, then electrical performance is improved, but device complexity increases
Solution Approach 1:
The electrode fin structure is formed using self-aligned processes where the fin itself defines the location and dimensions of subsequent processing steps. The capping structure is deposited conformally on the electrode fin, automatically conforming to its shape and position. This self-service approach increases contact surface area for better electrical performance while minimizing the need for additional alignment steps and complex processing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances gate contact for reduced resistance and improves the control of gapfill area, addressing the issues associated with self-aligned contacts and ensuring reliable electrical performance in semiconductor devices.
Implementation Method 1
performing a gate replacement cycle to replace the dummy gate structure with a replacement metal gate, the gate replacement cycle including: removing the dummy gate structure to form a first recess... and etching back the gate dielectric, the metal gate, and the metal fill, to thereby forming an electrode fin from the metal fill
Data Source
AI summary
Embodiments provide a replacement metal gate in a FinFET or nanoFET which utilizes a conductive metal fill. The conductive metal fill has an upper surface which has a fin shape which may be used for a self-aligned contact.