Fin Structure Recess for Epitaxial Layer Quality
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Solution Overview
Problem
Conventional FinFET fabrication methods result in fin-shaped structures being lower than surrounding shallow trench isolation due to over-etching, affecting the formation and quality of epitaxial layers.
Innovation Solution
The process involves partially removing each fin structure to form recesses for epitaxial layer growth, where the removed region is used to extend the epitaxial layer from one fin structure to another, ensuring the epitaxial layer's bottom surface is lower than the isolation regions, thereby improving epitaxial layer quality and allowing it to contact multiple fin structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional FinFET fabrication process is used to form recesses after removing part of fin-shaped structures, then the epitaxial layer can be grown, but the fin-shaped structures become lower than the surrounding shallow trench isolation due to over-etching, affecting epitaxial layer formation quality
Solution Approach 1:
The patent performs preliminary etching of the fin structures before forming the shallow trench isolation, creating recesses in advance. This preliminary action allows the epitaxial layer to be grown in the recessed regions, ensuring proper epitaxial layer formation quality while preventing the fin structures from becoming lower than the isolation regions during subsequent processing steps.
Solution Approach 2:
The patent applies different etching depths to different regions of the fin structures, creating localized recesses only in specific areas where epitaxial layer growth is desired. This local quality approach ensures that the epitaxial layer forms correctly in the recessed regions while maintaining the height of other fin structure regions relative to the shallow trench isolation.
2Manufacturing precision
If fin structures are partially removed to accommodate epitaxial layer growth, then epitaxial layer quality improves, but the process complexity increases
Solution Approach 1:
The patent merges the etching step for creating recesses with the existing fin structure formation process, combining multiple functions into a single integrated process flow. This merging reduces the overall process complexity while still achieving the desired epitaxial layer quality through selective removal of fin structure portions.
Solution Approach 2:
The patent designs the etching process to serve multiple functions simultaneously: it defines the fin structure shape, creates recesses for epitaxial layer growth, and establishes the relative height positioning between fin structures and shallow trench isolation. This multi-functionality reduces the need for separate dedicated steps, thereby simplifying the overall fabrication process.
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 quality of the epitaxial layer, improves semiconductor device performance, and simplifies the process by allowing simultaneous formation of source/drain regions for multiple transistors.
Implementation Method 1
at least an epitaxial layer disposed on the side of the first fin structure and the second fin structure
Data Source
AI summary
The present invention provides a method for forming a semiconductor structure, comprising: firstly, a substrate is provided, having a first fin structure and a second fin structure disposed thereon, next, a first isolation region is formed between the first fin structure and the second fin structure, a second isolation region is formed opposite the first fin structure from the first isolation region, and at least an epitaxial layer is formed on the side of the first fin structure and the second fin structure, wherein the epitaxial layer has a bottom surface, the bottom surface extending from the first fin structure to the second fin structure, and the bottom surface is lower than a bottom surface of the first isolation region and a top surface of the second isolation region, in addition, the epitaxial layer has a stepped-shaped sidewall profile.