Etching Mask Multilayer Structure for Dimensional Stability
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Solution Overview
Problem
Existing methods for forming etching masks in semiconductor device manufacturing face challenges in maintaining dimensional accuracy due to expansion and contraction of hard masks during metallization, leading to pattern deformation and reduced etching tolerance, especially for high aspect ratio patterns.
Innovation Solution
A method involving the formation of a mask layer with organic material containing reaction sites, followed by a filling layer with fewer reaction sites, which adheres firmly to the mask layer and minimizes volume change during metallization, thereby suppressing pattern deformation and enhancing etching tolerance through thermal annealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hard mask including metal oxide is used as an etching mask, then etching capability is improved, but dimensional accuracy deteriorates due to expansion and contraction during metallization
Solution Approach 1:
The mask structure is segmented into multiple functional layers: a lower mask layer containing metal oxide for etching capability, an upper mask layer for dimensional stability, and a filling layer for stress compensation. Each layer performs a specific function, allowing the system to achieve both high etching capability and dimensional accuracy simultaneously.
Solution Approach 2:
The patent employs composite material structures combining different materials with complementary properties. The lower mask layer uses metal oxide (e.g., silicon oxide, silicon nitride) for chemical stability and etching resistance, while the upper mask layer and filling layer use materials with appropriate thermal and mechanical properties to compensate for expansion and contraction during metallization processes.
2Reliability
If thermal annealing is performed to enhance etching tolerance, then etching performance is improved, but pattern deformation increases due to mask layer expansion
Solution Approach 1:
The filling layer is designed to generate compressive stress that preliminarily counteracts the tensile stress and expansion that will occur during thermal annealing and metallization processes. This pre-compensation mechanism prevents pattern deformation before it happens, allowing thermal annealing to be performed effectively without compromising dimensional accuracy.
Solution Approach 2:
The patent carefully controls the composition, thickness, and material properties of the filling layer to optimize the stress compensation effect. By adjusting parameters such as the filling layer's material composition and thickness ratio relative to the mask layer, the system achieves optimal balance between etching tolerance enhancement and pattern deformation prevention during thermal annealing.
3Measurement precision
If the mask layer is made thinner to improve resolution, then pattern resolution is improved, but etching tolerance deteriorates
Solution Approach 1:
The patent transitions from relying solely on mask layer thickness for resolution to using a multi-layer vertical structure. By adding the upper mask layer and filling layer in the vertical dimension, the system achieves high resolution through precise patterning of the upper layer while the combined multi-layer structure provides enhanced etching tolerance through stress compensation and improved mechanical strength.
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 improves the dimensional accuracy of the hard mask and enhances etching tolerance, particularly for high aspect ratio patterns, by maintaining the opening dimensions and preventing peeling of the filling layer during thermal annealing.
Implementation Method 1
the filling layer 5 adheres firmly to the mask layer 2
Implementation Method 2
enhancing etching tolerance through thermal annealing
Data Source
AI summary
A method for forming an etching mask includes forming a mask layer containing an organic material on a layer to be patterned using the etching mask in a subsequent etching process, processing the mask layer to form a pattern including an opening, forming a filling layer in the opening, impregnating the mask layer with a metal material, and removing the filling layer. The organic material in the mask layer includes reaction sites that react with the metal material, and the filling layer has fewer the reaction sites per the unit volume than the mask layer.