Fin Structure Profile Control via SiCoNi Dry Etching
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Solution Overview
Problem
Conventional methods for forming fin structures in integrated circuits result in significant width differences between the top and bottom surfaces, wicking features, and lack of corner rounding, which impact the performance and production time of non-planar FET devices.
Innovation Solution
A semiconductor process involving a SiCoNi dry etching method using HF and NH3-based process gases to define the height of fin structures, along with a series of etching and planarization steps to improve the fin structure profiles and reduce surface differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional etch back process using diluted hydrofluoric acid is used to form fin structures, then the process is simple and easy to manufacture, but the width difference between top and bottom surfaces of fin structures becomes large (greater than 1 nm) and corner wicking features occur
Solution Approach 1:
The patent changes the etching parameters by switching from wet etching (diluted HF acid) to dry etching processes. Specifically, it uses a first dry etching process with CF4-based gas followed by a second dry etching process with BF3-based gas, which fundamentally alters the etching mechanism and control characteristics, enabling precise fin structure formation with minimal width difference and no corner wicking
Solution Approach 2:
The patent divides the etching process into two distinct stages: a first dry etching process to initially form the fin structures, and a second dry etching process to precisely define the fin height and profile. This segmentation allows each process to be optimized independently, achieving both ease of manufacture and high precision
2Device complexity
If conventional etch back process is used to form fin structures, then the process steps are fewer, but additional H2 annealing process is necessary to obtain corner rounding feature
Solution Approach 1:
The dry etching process parameters are optimized to self-generate the desired corner rounding features during the etching process itself, without requiring subsequent annealing steps. The CF4-based and BF3-based gases create controlled etching profiles that inherently produce rounded corners, making the process self-sufficient
3Productivity
If conventional etch back process is used to form fin structures, then production time is reduced, but the fin structures exhibit significant wicking features with height difference exceeding 40 Å
Solution Approach 1:
The patent replaces the wet chemical etching mechanism (diluted HF acid) with a dry plasma-based etching mechanism using CF4 and BF3 gases. This substitution provides superior control over the etching process, eliminating wicking features and achieving uniform fin structures with high productivity
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 process achieves better fin structure profiles, enhancing the electrical properties of non-planar FETs by minimizing surface differences and eliminating the need for additional annealing processes, thereby simplifying the manufacturing process and improving device performance.
Implementation Method 1
performing a SiCoNi dry etching process using HF and NH3 based process gases to define the height of fin structures
Data Source
AI summary
A method of forming fin structure in integrated circuit comprising the steps of forming a plurality of fin structures on a substrate, covering an insulating layer on said substrate, performing a planarization process to expose mask layers, performing a wet etching process to etch said insulating layer, thereby exposing a part of the sidewall of said mask layer, removing said mask layer, and performing a dry etching process to remove pad layer and a part of said insulating layer, thereby exposing the top surface and a part of sidewall of said fin structures.