Metal Gate Contact Interface With Conductive Layer for Low Resistance
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Solution Overview
Problem
The challenge in semiconductor device fabrication is the high resistance at the interface between metal gate structures and contact features, particularly due to multiple work function metal layers, which complicates electrical property control as feature sizes decrease.
Innovation Solution
A conductive layer is formed between the metal gate structure and the contact feature to reduce resistance, achieved through a surface treatment that converts the passivation layer into a low resistive conductive layer, maintaining electrical stability of the metal gate by confining the conductive layer within smooth boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low resistive conductive layer is grown between the contact feature and metal gate to reduce resistance, then contact resistance is reduced, but the electrical property stability of the metal gate may be interfered with
Solution Approach 1:
A passivation layer is introduced as an intermediary between the metal gate structure and the low resistive conductive layer. This passivation layer protects the metal gate from chemical reactions and diffusion with the conductive layer materials, thereby maintaining the electrical property stability of the metal gate while still allowing the conductive layer to reduce contact resistance effectively.
Solution Approach 2:
The passivation layer is formed on the metal gate structure before depositing the low resistive conductive layer. This preliminary protective action prevents potential damage to the metal gate's electrical properties before the conductive layer is introduced, ensuring that the metal gate's work function and electrical characteristics remain stable throughout the subsequent processing steps.
2Productivity
If feature size is decreased to increase functional density, then production efficiency is improved, but interface resistance control becomes more difficult
Solution Approach 1:
The passivation layer serves as a mediator that decouples the interface between the contact feature and metal gate, providing a controlled transition zone. This intermediary layer enables precise control of interface resistance even at reduced feature sizes by managing the chemical and physical interactions between adjacent materials.
Solution Approach 2:
The formation of the passivation layer changes the chemical and physical parameters of the metal gate surface, creating a stable interface that maintains consistent electrical properties. This parameter change allows for reliable resistance control despite the scaling down of feature dimensions.
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 reduces contact resistance by over 50% and maintains electrical property stability, facilitating the integration of the conductive layer into existing semiconductor fabrication processes.
Implementation Method 1
performing a surface treatment to a top surface of the metal gate structure, wherein the surface treatment converts a top portion of the gate electrode to an oxidation layer
Implementation Method 2
the forming of the conductive layer includes substituting oxygen in the oxidation layer with a metallic element
Implementation Method 3
In some embodiments, the surface treatment includes applying plasma to the top surface of the metal gate structure
Data Source
AI summary
A semiconductor structure includes a metal gate structure including a gate dielectric layer and a gate electrode, a conductive layer disposed on the gate electrode, and a gate contact disposed on the conductive layer. The conductive layer extends from a position below a top surface of the metal gate structure to a position above the top surface of the metal gate structure. The gate electrode includes at least a first metal, and the conductive layer includes at least the first metal and a second metal different from the first metal. Laterally the conductive layer is fully between opposing sidewalls of the metal gate structure.