Triple Layer Anti-Reflective Hard Mask for Semiconductor Lithography
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Solution Overview
Problem
Conventional photolithographic techniques suffer from large variations in critical dimensions of semiconductor devices due to reflective issues, which are not adequately addressed by existing anti-reflective coatings.
Innovation Solution
A triple layer bottom anti-reflective coating (BARC) is formed using layers of silicon oxynitride, silicon rich nitride, or silicon nitride, with specific anti-reflective materials having varying extinction coefficients to minimize reflectivity and enhance the accuracy of the photolithographic process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single layer anti-reflective coating is used, then the complexity of the coating structure is reduced, but large variations in critical dimensions still occur due to reflectivity
Solution Approach 1:
The patent divides the anti-reflective coating into three distinct layers with different materials and extinction coefficients. This segmentation allows each layer to contribute differently to reflectivity reduction, achieving superior critical dimension control compared to a single-layer coating.
Solution Approach 2:
The patent employs a composite structure consisting of three layers made from different anti-reflective materials with varying extinction coefficients. This composite approach enables optimized optical properties that minimize reflectivity and reduce critical dimension variations more effectively than homogeneous single-layer coatings.
2Ease of manufacture
If conventional photolithographic techniques are used, then the process is simple and widely applicable, but reflectivity causes large variations in critical dimensions
Solution Approach 1:
The patent applies the triple-layer anti-reflective coating before the photolithographic exposure process. This preliminary action of reducing reflectivity in advance allows the subsequent conventional photolithography to proceed with improved precision, minimizing critical dimension variations caused by reflective interference.
3Productivity
If the number of devices on an IC is increased by decreasing feature size, then device density is improved, but conventional photolithography cannot achieve the required precision
Solution Approach 1:
The patent addresses the critical dimension precision problem by adding a dimensional aspect to the coating structure - transitioning from a single-layer to a triple-layer configuration. This dimensional change in the coating architecture enables the photolithographic process to achieve the precision required for smaller features and higher device density.
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 triple layer BARC significantly reduces variations in critical dimensions, improving the accuracy of the photolithographic process and enabling the fabrication of smaller semiconductor device features.
Implementation Method 1
forming a first layer of anti-reflective material over the layer of SiON, SiRN or Si3N4 and forming a second layer of anti-reflective material over the first layer... the first anti-reflective layer having a first extinction coefficient... the second anti-reflective layer having a second extinction coefficient, where the second extinction coefficient is smaller than the first extinction coefficient
Data Source
AI summary
A method includes forming a layer of silicon oxynitride (SiON), silicon rich nitride (SiRN) or silicon nitride (Si3N4) over a layer of semiconducting material. The method further includes forming a first layer of anti-reflective material over the layer of SiON, SiRN or Si3N4 and forming a second layer of anti-reflective material over the first layer. The method also includes using the first layer, second layer and layer of SiON, SiRN or Si3N4 as a mask when etching a pattern in the layer of semiconducting material.