Metal Gate Electrode Structure for Threshold Voltage and Filling Control
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Solution Overview
Problem
The challenge in semiconductor manufacturing lies in forming metal gate electrodes with improved filling capability, threshold voltage control, and reduced resistance, as existing methods face issues with increased trench aspect ratios, uneven barrier layers, and the trade-off between leakage current reduction and work function tuning.
Innovation Solution
The proposed solution involves reducing or removing barrier layers in metal gate electrodes post-formation to achieve varying thicknesses, allowing for better threshold voltage control and increased filling area, coupled with thermal treatments to minimize leakage, thereby enhancing the performance and flexibility of metal gate electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If barrier layers are maintained with uniform thickness to reduce leakage current, then reliability is improved, but manufacturing precision deteriorates due to inability to achieve varying thicknesses for different transistor requirements
Solution Approach 1:
The barrier layer is segmented into multiple discrete thickness regions (first thickness, second thickness, third thickness) within the same gate electrode structure. This segmentation allows different portions of the gate electrode to have different barrier layer thicknesses, enabling precise threshold voltage control for different transistor types while maintaining adequate leakage protection in each region.
Solution Approach 2:
Different thickness regions of the barrier layer are strategically positioned to provide locally optimized properties: thicker regions provide enhanced leakage current reduction, while thinner regions enable better work function tuning and threshold voltage control. This local quality variation resolves the contradiction between uniform leakage protection and differentiated threshold voltage requirements.
2Reliability
If barrier layer thickness is increased to reduce leakage current, then reliability is improved, but device complexity increases due to additional process steps required
Solution Approach 1:
The barrier layer is deposited with varying thicknesses in a preliminary action during the gate electrode formation process, before subsequent processing steps. This preliminary structuring of the barrier layer with multiple thickness regions is achieved through controlled deposition techniques, and subsequent selective removal or modification steps create the final differentiated structure without requiring entirely separate processing sequences.
Solution Approach 2:
The barrier layer thickness parameter is varied continuously or discretely across different regions of the gate electrode through controlled deposition parameters (such as deposition time, rate, or selective masking). This parameter change approach creates multiple thickness regions in a single integrated process flow, avoiding the need for multiple separate deposition and etching cycles that would increase device complexity.
3Manufacturing precision
If barrier layers are removed or reduced in thickness to improve filling capability, then manufacturing precision is improved, but reliability deteriorates due to increased leakage current
Solution Approach 1:
The barrier layer structure implements local quality variation where certain regions have reduced or removed barrier layers to improve filling capability and work function tuning, while other regions maintain adequate barrier thickness for leakage current control. This spatial differentiation of barrier layer properties resolves the contradiction between filling performance and leakage protection.
Solution Approach 2:
The gate electrode structure is segmented into regions with different barrier layer configurations: some portions have full-thickness barrier layers for leakage protection, while other portions have reduced or removed barrier layers for improved filling and threshold voltage control. This segmentation allows simultaneous optimization of both filling capability and leakage current control in different parts of the same device.
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 improves the filling performance and corner profile control of metal gate electrodes, reduces resistance, and allows for precise threshold voltage management across different transistors, leading to enhanced semiconductor device performance and manufacturing flexibility.
Implementation Method 1
coupled with thermal treatments to minimize leakage
Data Source
AI summary
A method includes: providing a first gate electrode over the substrate; forming a first pair of spacers on two sides of the first gate electrode; removing the first gate electrode to form a first trench between the first pair of spacers; depositing a dielectric layer in the first trench; depositing a first layer over the dielectric layer; removing the first layer from the first trench; and depositing a work function layer over the dielectric layer in the first trench.