Fin Structure Removal via Two-Step Etching Masking
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Solution Overview
Problem
Existing methods for forming fin structures in FinFET devices face challenges due to the loading effect when trying to achieve different densities, leading to mismatched shapes and potential damage to wanted fin structures during the removal of redundant ones.
Innovation Solution
A two-step etching process is employed, where a dry etching process is used to remove the mask layer, followed by a wet etching process to selectively remove the fin structures, ensuring that the wanted fin structures are protected and not damaged during the removal of redundant ones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single etching process is used to remove redundant fin structures, then the removal process is simple and fast, but the wanted fin structures may be damaged along with the redundant ones
Solution Approach 1:
The single etching process is divided into two sequential etching processes: a first etching process that selectively removes redundant fin structures, and a second etching process that removes the mask layer. This segmentation allows each process to have optimized selectivity and protection mechanisms, preventing damage to wanted fin structures while maintaining efficient removal of redundant ones
Solution Approach 2:
A mask layer is formed on the substrate before the etching processes begin. This mask layer serves as a protective preliminary structure that prevents etching damage to wanted fin structures during the removal process. The mask layer is strategically positioned to protect only the desired fin structures while allowing access to redundant ones
2Adaptability or versatility
If fin structures with different densities are formed, then the device can accommodate varying transistor densities, but the loading effect causes mismatched shapes and formation challenges
Solution Approach 1:
The mask layer is applied with spatial variation to create different local properties: in high-density regions, the mask layer provides full protection to maintain uniform fin shapes, while in low-density regions, the mask layer configuration allows for selective removal. This local quality approach enables different fin structure densities to be achieved while maintaining shape consistency through controlled etching exposure
Solution Approach 2:
The etching process parameters are optimized to account for loading effects. By adjusting etching conditions and mask layer characteristics, the process compensates for the loading effect that occurs when fin structures are formed at different densities, ensuring that the final fin structures maintain consistent shapes regardless of local density variations
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 method allows for the precise removal of redundant fin structures without damaging the wanted ones, maintaining the original design and shape of the fin structures across different density regions, thereby improving the fabrication process of FinFET devices.
Implementation Method 1
a dry etching process is utilized to remove a mask layer on the fin structure
Implementation Method 2
a wet etching process removes the entire fin structure
Data Source
AI summary
A method of removing a fin structure includes providing a substrate. A fin structure extends from the substrate. A mask layer is disposed on a top surface of the fin structure. An organic dielectric layer covers the substrate, the fin structure and the mask layer. A first etching process is performed to entirely remove the mask layer by taking the organic dielectric layer as a mask. Then a second etching process is performed to remove the fin structure. The first etching process is preferably an anisotropic etching process, and the second etching process is an isotropic etching process.