Fin Structure With Irregular Protrusion Prevents Collapse
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Solution Overview
Problem
The current methods for forming fin field effect transistors (Fin FETs) face challenges in precision and efficiency due to limitations in mask and lithography techniques, leading to fin collapse or over-etching issues during the shrinking of fin width and pitch, which affects the efficiency of the fin structure.
Innovation Solution
A method involving a series of etching processes with etchants of varying selectivity is used to progressively remove dummy fins and form an irregular fin structure with a protrusion, ensuring precise control and preventing fin collapse or over-etching, while maintaining the fin's integrity and forming an irregular shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If mask and lithography techniques are used to shrink fin width and pitch, then miniaturization is achieved, but manufacturing precision deteriorates due to fin collapse or over-etching
Solution Approach 1:
The patent divides the single etching process into multiple sequential etching stages (first etching process, second etching process, third etching process), each with different etching conditions and selectivity parameters. This segmentation allows progressive removal of dummy fins while maintaining control over the main fin structure, preventing collapse and over-etching that occur in single-step processes.
Solution Approach 2:
The patent changes etching parameters including etchant selectivity, etching time, and process conditions across different etching stages. The first etching uses high selectivity to remove dummy fins, while subsequent etchings adjust parameters to maintain main fin integrity. This dynamic parameter adjustment resolves the contradiction between miniaturization and precision.
2Productivity
If dummy fins are removed to form irregular shape, then efficiency is improved, but device complexity increases due to multiple etching processes
Solution Approach 1:
The patent performs preliminary formation of dummy fins along with the main fin structure in the initial fabrication steps. These dummy fins are then selectively removed in controlled etching stages to create the irregular shape. This preliminary action simplifies the overall process by integrating dummy fin formation into the standard fabrication flow, reducing the need for additional complex steps.
Solution Approach 2:
The patent uses dummy fins as intermediary structures that facilitate the formation of the irregular fin shape. These dummy fins serve as placeholders during fabrication and are subsequently removed to create the desired geometry. This intermediary approach simplifies the fabrication process by using a standard fin formation technique followed by selective removal, rather than attempting to directly form the complex irregular shape.
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 enhances the etching effect, prevents fin collapse or over-etching, and allows for the formation of a fin structure with an irregular shape that improves efficiency by effectively removing dummy fins and creating isolated protrusions, thereby addressing the limitations of existing Fin FET fabrication processes.
Implementation Method 1
a first etching process is performed to remove a portion of the second fin. After that, a second etching process is performed to remove another portion of the second fin and to form an irregular shape on the second fin. Finally, a third etching process is performed to further remove another portion of the second fin and to form a protrusion
Data Source
AI summary
A fin structure and a method of forming the same, where the fin structure includes a fin and a protrusion having irregular shape. The fin and the protrusion are both formed on a substrate, and the protrusion has a height less than that of the fin. With such arrangement, the fin structure of the present invention, as well as the method of forming the same, can achieve the purpose of keeping the fin from collapsing and over etching.