FinFET Fin Surface Roughness Reduction via Crystal Orientation
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Solution Overview
Problem
Conventional methods for forming fin-shaped channels in FinFET devices face challenges due to surface roughness affecting the electrical properties of high k-metal gate structures, particularly as feature sizes shrink, leading to decreased performance and increased complexity in semiconductor manufacturing.
Innovation Solution
A method involving ion implantation to create implanted regions on a semiconductor substrate, followed by epitaxial growth of fins between these regions, and the formation of an insulating structure to reduce surface roughness, allowing for a surface orientation that minimizes disruptions to the metal gate work function and enhances electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to form fin-shaped channels, then the fin structure can be created, but the surface roughness of the fin increases which degrades the electrical properties of the high k-metal gate structure
Solution Approach 1:
The patent changes the crystallographic orientation parameter of the fin surface from conventional <100> to <110>, which fundamentally alters the surface atomic arrangement and reduces surface roughness. This parameter change in crystal orientation directly addresses both the surface roughness issue and the electrical property degradation of the metal gate structure.
Solution Approach 2:
Instead of trying to reduce surface roughness through post-etching processing steps, the patent inverts the approach by selecting a different crystal orientation that inherently provides smoother surfaces. This reverses the conventional wisdom that etching must be followed by extensive surface planarization.
2Productivity
If feature sizes are shrunk to increase transistor density, then more devices can be packed, but the surface roughness effect becomes more pronounced leading to decreased electrical performance
Solution Approach 1:
By changing the fin crystal orientation to <110>, the patent enables continued scaling to smaller feature sizes while maintaining smooth surfaces. The new orientation provides inherent surface smoothness that counteracts the increased surface area effects that occur during scaling, allowing higher transistor density without sacrificing electrical performance.
3Ease of manufacture
If conventional fin formation processes are used, then the process is well-established, but the metal gate work function changes due to surface roughness causing performance degradation
Solution Approach 1:
The patent modifies the crystal orientation parameter to <110> which provides inherent surface smoothness, thereby stabilizing the metal gate work function. This parameter change maintains compatibility with existing manufacturing processes while improving the critical work function stability issue.
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
The approach results in a FinFET device with reduced surface roughness and improved electrical properties, ensuring stable performance and manufacturing efficiency by maintaining the integrity of the metal gate work function and enhancing transistor density.
Implementation Method 1
performing an ion implantation on the semiconductor substrate using the patterned photoresist as a mask
Implementation Method 2
epitaxial growth of fins between these regions
Data Source
AI summary
A method for manufacturing a fin for a FinFET device includes providing a semiconductor substrate, forming a plurality of implanted regions in the semiconductor substrate, and epitaxially forming fins between two adjacent implanted regions. The method also includes forming an insulating structure between two adjacent fins.