Graded Semiconductor Fin Height Control via Selective Etching
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Solution Overview
Problem
The challenge in semiconductor manufacturing is the inconsistency in fin height during the production of three-dimensional semiconductor devices like FinFETs, leading to performance variability across the wafer due to difficulties in controlling the etching depth and uniformity of semiconductor layers.
Innovation Solution
A method involving the sequential formation of semiconductor layers with a compound semiconductor having a graded concentration distribution, where the first semiconductor layer is designed to match the substrate and second layer interfaces, allowing for selective etching and reduced etching depth, and the use of a dielectric isolation layer to control fin height and parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional planar semiconductor devices are scaled down, then device density increases, but short channel effects become more significant and fin height uniformity deteriorates
Solution Approach 1:
The semiconductor structure is divided into multiple segments: a first semiconductor layer with graded composition, a second semiconductor layer, and an isolation layer. This segmentation allows each layer to serve specific functions - the graded layer controls etching selectively, the second layer provides structural integrity, and the isolation layer defines precise fin height, collectively solving the uniformity problem while maintaining high device density
Solution Approach 2:
An intermediary isolation layer is introduced between the semiconductor layers and the substrate. This isolation layer acts as a mediator that enables precise control of fin height by providing a reference plane for etching, thereby improving manufacturing precision without compromising device density
2Reliability
If etching depth is increased to form taller fins, then device performance improves, but etching uniformity across the wafer deteriorates
Solution Approach 1:
The first semiconductor layer exhibits local quality through its graded composition distribution, where the composition varies locally to create selective etching characteristics. This allows the etching process to proceed uniformly across the wafer while achieving the required fin height, as different regions etch at controlled rates based on their local composition
Solution Approach 2:
The graded composition layer is formed in advance before the final etching process. This preliminary action prepares the structure with built-in etching selectivity, enabling uniform etching across the wafer without requiring precise control of etching depth, thereby maintaining both device performance and etching uniformity
3Manufacturing precision
If fin height is controlled precisely, then device performance consistency improves, but parasitic capacitance increases
Solution Approach 1:
The harmful effect of parasitic capacitance is extracted and isolated by introducing a dedicated isolation layer. This layer separates the fin structure from the substrate, allowing precise fin height control while minimizing parasitic capacitance through proper material selection and geometric configuration of the isolation structure
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 uniformity of fin height and reduces parasitic capacitance, improving the consistency and performance of semiconductor devices by allowing for precise control of etching and layer thickness, thereby addressing the inconsistency issues in existing technologies.
Implementation Method 1
the first semiconductor layer comprises a compound semiconductor, with at least one component whose concentration has a graded distribution in a stack direction of the first and second semiconductor layers
Data Source
AI summary
A semiconductor device and a method for manufacturing the same. An example method may include: forming a first semiconductor layer and a second semiconductor layer sequentially on a substrate; patterning the second and first semiconductor layers to form an initial fin; forming an isolation layer on the substrate, wherein the isolation layer exposes partially the first semiconductor layer, and thus defines a fin above the isolation layer; and forming a gate stack intersecting the fin on the isolation layer, wherein the first semiconductor layer comprises a compound semiconductor, with at least one component whose concentration has a graded distribution in a stack direction of the first and second semiconductor layers.