FinFET Etching Uniformity via Sacrificial Layer Loading Effect
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Solution Overview
Problem
Existing FinFET devices face challenges in controlling etching uniformity due to the loading effect, which occurs when etching fin structures with different pattern densities in various regions, leading to mismatched etching rates and difficulties in maintaining uniformity of height and thickness of deposited layers.
Innovation Solution
The implementation of a sacrificial layer with a higher-than-normal thickness over-deposited on fin structures to reduce the loading effect, maintaining a gap height between fin structures within a specific range (0.4 nm to 4 nm) to improve uniformity and control the etching process, thereby enhancing the performance of FinFET structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fin structures with different pattern densities are etched in various regions, then device density and integration are improved, but etching uniformity deteriorates due to the loading effect
Solution Approach 1:
A sacrificial layer is introduced as an intermediary material between the etching process and the fin structures. This sacrificial layer is deposited over the fins with different pattern densities and then removed, allowing the etching process to proceed uniformly across all regions without the loading effect, thereby maintaining etching uniformity while supporting high device density
Solution Approach 2:
The sacrificial layer is deposited in advance before the final etching process. This preliminary deposition action compensates for the loading effect that would otherwise occur during etching, ensuring that all fin structures receive uniform etching treatment regardless of their pattern density, thus resolving the contradiction between high device density and etching uniformity
2Manufacturing precision
If sacrificial layer is over-deposited on fin structures, then loading effect is reduced and etching uniformity is improved, but process complexity increases
Solution Approach 1:
The thickness parameter of the sacrificial layer is optimized to a specific range (0.4 nm to 4 nm) to achieve the desired balance. By controlling this parameter, the sacrificial layer effectively reduces the loading effect and improves etching uniformity without requiring excessive process complexity, as the thickness can be precisely controlled through standard deposition processes
3Manufacturing precision
If gap height between fin structures is maintained within specific range, then uniformity of deposited layers is improved, but fabrication precision requirements increase
Solution Approach 1:
The gap height between fin structures is controlled within a specific range (0.4 nm to 4 nm) based on feedback from the etching process. This feedback mechanism ensures that the gap height is maintained at optimal values that improve the uniformity of subsequently deposited layers such as gate dielectric and gate electrode layers, while the precision requirements are managed through process control rather than extreme fabrication precision
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 the loading effect, improves the uniformity of fin heights, and enhances the performance of FinFET structures by maintaining uniformity in the thickness of deposited layers, such as the gate dielectric and gate electrode layers.
Implementation Method 1
a sacrificial layer is over-deposited on the first fin structures, the second fin structures and the isolation structure
Implementation Method 2
challenges from both fabrication and design issues have resulted in the development of three-dimensional designs, such as the fin field effect transistor (FinFET)... challenges in controlling etching uniformity due to the loading effect, which occurs when etching fin structures with different pattern densities
Data Source
AI summary
A fin field effect transistor (FinFET) device structure is provided. The FinFET structure includes a substrate, and the substrate includes a first region and a second region. The FinFET structure includes a first plurality of fin structures formed on the first region and a second plurality of fin structures formed on the second region. A density of the first plurality of fin structures is greater than a density of the second plurality of fin structures. The FinFET structure also includes a plurality of protruding structures between two adjacent second plurality of fin structures in the second region and an isolation structure formed on the substrate. The isolation structure has a gap height between the first plurality of fin structures and the second plurality of fin structures.