Cut Gate Dielectric Structure With Helmet Layer for CMG Protection
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Solution Overview
Problem
The challenge in semiconductor manufacturing lies in protecting epitaxial source/drain structures from damage during the cut metal gate (CMG) process, which can occur due to increased volume and reduced process window in forming trenches, leading to potential damage and reduced effectiveness of these structures.
Innovation Solution
The introduction of a helmet layer to protect epitaxial source/drain structures during the CMG process, utilizing a higher etch resistance material that shields these structures from etchant gases with varying molecular weights, thereby maintaining their integrity and allowing for precise trench formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If trenches are formed with increased volume to accommodate larger epitaxial structures, then the process window is reduced and damage to epitaxial source/drain structures occurs, but if trenches are formed with smaller volume, then the epitaxial structures cannot be adequately protected
Solution Approach 1:
A helmet layer is introduced as an intermediary protective structure between the etchant and the epitaxial source/drain structures. This helmet layer acts as a mediator that absorbs the harmful etching action, preventing direct contact with the vulnerable epitaxial structures while enabling the trench formation process to proceed with an expanded process window.
Solution Approach 2:
The helmet layer is formed beforehand to provide cushioning protection to the epitaxial source/drain structures before the trench etching process begins. This pre-positioned protective layer absorbs the mechanical and chemical stresses of the etching process, preventing damage to the underlying epitaxial structures during trench formation.
2Productivity
If the volume of epitaxial source/drain structures is increased to improve device performance, then the structures become more susceptible to damage during CMG process, but reducing volume improves process robustness
Solution Approach 1:
The helmet layer serves as a protective intermediary that allows larger epitaxial structures to be formed without increasing their susceptibility to etchant damage. The helmet layer absorbs the harmful etching effects, enabling the use of larger volume epitaxial structures for improved device performance while maintaining process robustness.
3Manufacturing precision
If standard etching processes are used for trench formation, then epitaxial source/drain structures are damaged, but if etching is avoided, then trench formation cannot be completed
Solution Approach 1:
The helmet layer is formed beforehand to provide a protective cushion during the trench etching process. This pre-positioned layer absorbs the mechanical and chemical stresses of etching, enabling precise trench formation while preventing damage to the underlying epitaxial source/drain structures.
Solution Approach 2:
The helmet layer acts as an intermediary between the etchant and the epitaxial structures, allowing the etching process to proceed with high precision while the helmet layer absorbs the harmful effects, protecting the vulnerable epitaxial structures from damage.
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 helmet layer effectively prevents damage to epitaxial source/drain structures, enhances the process window for trench formation, and allows for larger merged epitaxial materials, improving the overall integrity and performance of the semiconductor device.
Implementation Method 1
utilizing a higher etch resistance material that shields these structures from etchant gases
Data Source
AI summary
A device includes a semiconductor fin, a gate structure, gate spacers, and a dielectric feature. The semiconductor fin is over a substrate. The gate structure is over the semiconductor fin and includes a gate dielectric layer over the semiconductor fin and a gate metal covering the gate dielectric layer. The gate spacers are on opposite sides of the gate structure. The dielectric feature is over the substrate. The dielectric feature is in contact with the gate metal, the gate dielectric layer, and the gate spacers, and an interface between the gate metal and the dielectric feature is substantially aligned with an interface between the dielectric feature and one of the gate spacers.