Semiconductor Etching Sidewall Angle Control
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Solution Overview
Problem
As semiconductor devices integrate more densely, reducing the size of components like transistors and metal lines leads to higher aspect ratios and deteriorated profiles in contact plugs and contact holes, posing challenges in etching processes.
Innovation Solution
A method involving multiple etch processes with different etch gases and sidewall patterns, where the first etch process forms a first sidewall pattern with a specific angle, and the second etch process forms a second sidewall pattern with a different angle, allowing for controlled etching and reducing polymer deposition, thereby improving the aspect ratio and profile of trenches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the critical dimension of patterns is reduced to satisfy integration density requirements, then the size of components decreases, but the aspect ratio of contact plugs and contact holes increases and profiles deteriorate
Solution Approach 1:
The etching process is divided into multiple sequential etching processes, each forming a portion of the final trench. Sidewall patterns are formed and utilized as masks between etching steps, segmenting the overall etching operation into controlled stages that manage aspect ratio and profile quality throughout the process.
Solution Approach 2:
The sidewall patterns are formed with specific angles that are dynamically adjusted between etching steps. The angle of the sidewall pattern is optimized for each etching step to control the etching profile and reduce bowing phenomena, adapting the geometry to the specific requirements of each stage.
2Manufacturing precision
If multiple etching processes are performed with different sidewall patterns, then etching control and profile improvement are achieved, but process complexity increases
Solution Approach 1:
Sidewall patterns are formed as by-products during the etching processes themselves, utilizing chemical reactions between etch gases and the etch target layer. This self-forming mechanism eliminates the need for separate sidewall deposition steps, reducing overall process complexity while maintaining precise etching control.
3Productivity
If different etch gases are used in sequential etching processes, then polymer deposition is reduced and etching efficiency is improved, but process complexity increases
Solution Approach 1:
Different etch gases with varying polymer deposition characteristics are selected for different etching steps. The gas composition and flow parameters are optimized for each specific etching process to control polymer deposition rates and enhance etching efficiency, with parameters adjusted based on the specific requirements of each etching stage.
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 method enables more effective etching by adjusting the angle of etch gas injection, reducing bowing phenomena and achieving finer patterns with improved profiles and reduced etch loss, thus addressing the challenges of high aspect ratios and profile deterioration.
Implementation Method 1
the first sidewall pattern may be a by-product layer that is formed as a result of a chemical reaction between a carbon ion of the first etch gas and a by-product of the etch target layer
Implementation Method 2
the first sidewall pattern may be a by-product layer that is formed as a result of a chemical reaction between a carbon ion of the first etch gas and a by-product of the etch target layer
Implementation Method 3
the first and second etch processes may be performed using first and second etch gases, respectively
Data Source
AI summary
A method of fabricating a semiconductor device is disclosed. The method may include forming an target layer on a substrate, forming a mask pattern on a target layer, performing a first process to etch the target layer and form a first sub-trench, and performing a second process to further etch the target layer and form a second sub-trench. First and second sidewall patterns may be formed on a sidewall of the mask pattern to be used as an etch mask in the first and second processes, respectively. Outer sidewalls of the first and second sidewall patterns may be formed to have different angles with respect to a top surface of the substrate.