FinFET Source/Drain Profiles for Lower Contact Resistance
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Solution Overview
Problem
In the formation of Fin Field-Effect Transistors, existing methods face challenges in reducing fin bending and contact resistance due to the merging of epitaxy regions and planar top surfaces, which affect the performance of p-type FinFETs, while n-type FinFETs do not experience significant fin bending but have high contact resistance.
Innovation Solution
The solution involves forming n-type source/drain regions with wavy-shaped top surfaces and p-type source/drain regions with cone-shaped profiles, reducing fin bending in p-type FinFETs and increasing contact areas to lower contact resistance for both types, achieved through specific epitaxy processes and silicide region formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If epitaxy regions are grown from recesses of neighboring semiconductor fins, then source/drain regions are formed, but the epitaxy regions merge with planar top surfaces causing fin bending in p-type FinFETs
Solution Approach 1:
The patent applies different epitaxy growth conditions to n-type and p-type FinFETs locally. For p-type FinFETs, the epitaxy regions are grown with controlled merging to form convex top surfaces, while n-type FinFETs receive different treatment. This local differentiation resolves the fin bending issue in p-type devices without compromising n-type device performance.
Solution Approach 2:
The patent changes the epitaxy growth parameters (such as temperature, pressure, and doping conditions) specifically for p-type FinFETs to control the merging behavior of epitaxy regions. By adjusting these parameters, the convex profile is achieved that prevents fin bending while still forming functional source/drain regions.
2Ease of manufacture
If epitaxy regions merge with planar top surfaces, then manufacturing is simplified, but contact resistance increases for n-type FinFETs
Solution Approach 1:
The patent applies different top surface profiles to n-type and p-type FinFETs locally. For n-type FinFETs, the epitaxy regions are grown with profiles that increase contact area (such as wavy or non-planar surfaces), while p-type FinFETs receive different treatment. This local differentiation reduces contact resistance in n-type devices without complicating the overall manufacturing process.
3Device complexity
If standard epitaxy growth is used for both n-type and p-type FinFETs, then manufacturing is simplified, but p-type FinFETs experience significant fin bending
Solution Approach 1:
The patent implements local quality by differentiating the epitaxy growth process between n-type and p-type FinFETs. Specifically, p-type FinFETs receive controlled epitaxy growth that creates convex top surfaces to prevent fin bending, while n-type FinFETs receive different growth conditions. This targeted approach addresses the p-type issue without significantly increasing overall manufacturing complexity.
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 effectively reduces fin bending in p-type FinFETs and decreases contact resistance for both n-type and p-type FinFETs, enhancing the overall performance by optimizing the shape and structure of source/drain regions.
Implementation Method 1
growing epitaxy regions starting from the recesses
Data Source
AI summary
A method includes etching a first and a second semiconductor fin to form a first and a second recesses, epitaxially growing an n-type source/drain region comprising a first portion and a second portion from the first and the second recesses, and a first middle portion in between and having a concave top surface. A first contact opening is formed extending into the n-type source/drain region and having a first V-shaped bottom. The method further includes etching a third and a fourth semiconductor fin to form a third and a fourth recesses, and forming a p-type source/drain region including a third portion and a third portion grown from the third and the fourth recesses, and a second middle portion in between and having a convex top surface. A second contact opening is formed and has a second V-shaped bottom, with a tip of the second V-shaped bottom being downwardly pointing.