FinFET Fin Structure with Nitridation Etch Stop for Edge Shrinkage
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Solution Overview
Problem
In the manufacturing of FinFET devices, the reduction in fin profile due to plasma etching in low-density areas leads to reduced quality and potential device breakdown, as the edge fins shrink, affecting the overall performance and reliability of the transistors.
Innovation Solution
The introduction of a surface nitridation layer as an etch stop layer prior to oxide deposition helps protect the edge fins from shrinkage during etching processes, maintaining uniform fin thickness and preventing material removal from the sidewalls, thereby enhancing the fin profile and device stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma etching is used to define fins and device isolation structures, then manufacturing precision is improved, but fin profile shrinkage occurs in low-density areas leading to reduced reliability
Solution Approach 1:
A surface nitridation layer is formed on the fin structure before the plasma etching process. This preliminary action creates a protective barrier that prevents material removal from the fin sidewalls during etching, thereby maintaining uniform fin thickness and preventing the fin profile shrinkage that leads to device breakdown in low-density areas.
Solution Approach 2:
The surface nitridation layer acts as an intermediary protective layer between the fin structure and the plasma etching process. This intermediate layer has different etching characteristics than the underlying fin material, allowing it to serve as an etch stop layer that protects the fin profile while still permitting the etching process to define the fins and device isolation structures.
2Device complexity
If standard etching processes are used without protective layers, then manufacturing complexity is reduced, but fin thickness uniformity deteriorates due to edge fin shrinkage
Solution Approach 1:
The surface nitridation layer is formed as a preliminary step before the main etching process. This additional step, while increasing process complexity, ensures uniform fin thickness by preventing material removal from fin sidewalls, particularly in low-density areas where edge fins are susceptible to shrinkage.
Solution Approach 2:
The surface nitridation provides localized protection to the fin structure where it is most needed - at the sidewalls and in low-density areas. The nitridation layer has different properties than the bulk fin material, creating a localized protective zone that maintains fin thickness uniformity without affecting the overall etching 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
The use of an enhancement layer prevents fin profile shrinkage and maintains uniform thickness, reducing the risk of device breakdown and improving the quality and performance of FinFET devices by acting as a barrier during etching processes.
Implementation Method 1
The introduction of a surface nitridation layer as an etch stop layer prior to oxide deposition helps protect the edge fins from shrinkage during etching processes
Data Source
AI summary
A method for forming a semiconductor device. The method includes performing a first etching process to define one or more fins and corresponding device isolation structures on a substrate. The method further includes forming an enhancement layer on each of the fins, such that the enhancement layer encapsulates each fin. The method further performs a second etching process to remove one or more of the fins, and performs a third etching process to remove a portion of the enhancement layer. The method also includes depositing an STI material on the fins and the device isolation structures, followed by recessing the fins relative to the STI material.