Controlling RMG Critical Dimension via Dummy Gate Replacement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The integration of replacement metal gates (RMGs) in semiconductor devices often results in dimensional inconsistencies with dummy gates, leading to poor performance and reduced AC performance due to changes introduced by spacers and other integration specifics.
Innovation Solution
A method is implemented to control the critical dimension (CD) of RMGs by forming a dummy gate with a cap layer over a substrate, followed by a re-oxide layer, doping implants, removal of the re-oxide layer, formation of spacers and an epitaxial layer, and eventual replacement with a metal gate, ensuring dimensional consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If spacers are introduced when forming a replacement metal gate (RMG), then the RMG width increases significantly compared to the dummy gate, but this results in dimensional inconsistency and poor device performance
Solution Approach 1:
The method performs preliminary actions by forming the re-oxide layer and performing doping implants before removing the dummy gate. This sequence ensures that the substrate is properly prepared and doped before the metal gate is formed, preventing dimensional inconsistencies while maintaining ease of manufacture
Solution Approach 2:
The process segments the gate formation into distinct stages: dummy gate formation with cap layer, re-oxide layer formation, doping implants, re-oxide removal, and final metal gate formation. This segmentation allows each step to be optimized independently, achieving both manufacturing ease and dimensional precision
2Adaptability or versatility
If the dummy gate dimensions are greatly different from the final RMG dimensions, then integration specifics such as spacer introduction are required, but this leads to diminished AC performance
Solution Approach 1:
The method changes the critical dimension parameter by forming the re-oxide layer that extends beyond the dummy gate edges, then performing doping implants that define the final gate dimensions. This parameter change ensures dimensional consistency between dummy and metal gates while maintaining integration flexibility
Solution Approach 2:
The re-oxide layer serves as an intermediary structure that mediates between the dummy gate and the final metal gate. It provides a template for doping and ensures dimensional consistency, acting as a bridge that maintains reliability during the transition from dummy to metal gate
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 maintains dimensional consistency between dummy gates and RMGs, improving device performance by reducing Cov and enhancing Leff, Loff, and Cov metrics, as shown in simulation results.
Implementation Method 1
forming a re-oxide layer over the substrate and around the dummy gate
Implementation Method 2
implanting a set of doping implants in the substrate
Implementation Method 3
forming an epitaxial layer around the dummy gate
Data Source
AI summary
An approach for controlling a critical dimension (CD) of a RMG of a semiconductor device is provided. Specifically, embodiments of the present invention allow for CD consistency between a dummy gate and a subsequent RMG. In a typical embodiment, a dummy gate having a cap layer is formed over a substrate. A re-oxide layer is then formed over the substrate and around the dummy gate. A set of doping implants will then be implanted in the substrate, and the re-oxide layer will subsequently be removed (after the set of doping implants have been implanted). A set of spacers will then be formed along a set of side walls of the dummy gate and an epitaxial layer will be formed around the set of side walls. Thereafter, the dummy gate will be replaced with a metal gate (e.g., an aluminum or tungsten body having a high-k metal liner there-around).