FinFET Gate Fabrication Using Polymer Stop Layers for Leakage Control
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Solution Overview
Problem
Current metal gate transistor architectures are insufficient in achieving desirable performance, particularly at the 10 nm node generation, due to challenges in controlling the resistance value of metal gates effectively.
Innovation Solution
A method for fabricating a semiconductor device involves forming a fin-shaped structure on a substrate, patterning a gate material layer to create a gate structure and silicon residue, transforming the silicon residue into a polymer stop layer through an ashing and cleaning process, and forming a first and second seal layer to prevent leakage during the replacement metal gate process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If metal gate transistor architecture is used at 10 nm node, then transistor scaling is achieved, but resistance value control becomes insufficient
Solution Approach 1:
A polymer stop layer is introduced as an intermediary material between the metal gate and the fin structure. This polymer layer acts as a mediator that prevents direct contact and potential leakage paths, while also serving as a barrier to control the resistance value of the metal gate. The polymer stop layer is formed by transforming silicon residue through ashing and cleaning processes, creating a controlled intermediate layer that resolves the resistance control issue.
Solution Approach 2:
The invention changes the physical and chemical parameters of the interface between the metal gate and fin structure by introducing the polymer stop layer. This layer modifies the electrical parameters (resistance) and physical properties (leakage prevention) of the interface, enabling better control over the metal gate resistance value while maintaining the scaled transistor architecture.
2Ease of manufacture
If gate material layer is patterned to form gate structure, then transistor structure is created, but silicon residue and leakage paths are generated
Solution Approach 1:
The invention converts the harmful silicon residue generated during gate patterning into a beneficial polymer stop layer. Through ashing and cleaning processes, the silicon residue is transformed into a polymer material that serves as a protective barrier. This converts what was previously a harmful byproduct (causing leakage) into a useful component (preventing leakage and controlling resistance).
Solution Approach 2:
The polymer stop layer serves as an intermediary that eliminates the harmful effect of silicon residue. Instead of removing all silicon residue (which would require additional complex processes), the invention transforms it into a polymer layer that mediates between the metal gate and fin structure, preventing direct leakage paths while maintaining the ease of gate structure formation.
3Reliability
If polymer stop layer is formed to prevent leakage, then device integrity is improved, but fabrication process complexity increases
Solution Approach 1:
The polymer stop layer is formed as a preliminary action during the gate patterning process itself. The silicon residue that naturally forms during etching is transformed into the polymer stop layer through ashing and cleaning steps that are integrated into the existing fabrication flow. This preliminary formation of the protective layer eliminates the need for separate, complex leakage prevention processes that would be required if the polymer layer were formed through traditional deposition methods.
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
The polymer stop layers effectively prevent leakage by acting as a barrier between the gate structure and the spacer, ensuring the integrity of the semiconductor device and enhancing its performance by maintaining the desired resistance value of the metal gates.
Implementation Method 1
performing an ashing process on the silicon residue, and then performing a cleaning process to transform the silicon residue into a polymer stop layer
Data Source
AI summary
A method for fabricating a semiconductor device includes the steps of: forming a fin-shaped structure on a substrate, forming a gate material layer on the fin-shaped structure, performing an etching process to pattern the gate material layer for forming a gate structure and a silicon residue, performing an ashing process on the silicon residue, and then performing a cleaning process to transform the silicon residue into a polymer stop layer on a top surface and sidewalls of the fin-shaped structure.