Multi-Layer Etching Mask for High-k Safe Pattern Transfer
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Solution Overview
Problem
Conventional etching processes in integrated circuit formation face challenges with dimension control and etching profile limitations due to damage from strong acids or alkalis, particularly when using tri-layer etching masks, which can damage high-k dielectric and fin structures during patterning of work-function layers.
Innovation Solution
An etching mask comprising a Bottom Anti-Reflective Coating (BARC), an inorganic middle layer formed of an amphoteric material, and a photo resist is used, where the inorganic middle layer is selectively removable using weak acids or alkalis to prevent damage to underlying layers, ensuring high etching selectivity and controlled patterning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional tri-layer etching masks with organic materials are used, then the etching process can be performed, but damage occurs to high-k dielectric and fin structures due to strong acids or alkalis
Solution Approach 1:
The patent introduces an inorganic middle layer (such as silicon oxide or silicon nitride) between the organic BARC and photo resist layers. This inorganic layer acts as a mediator that is resistant to strong acids and alkalis, preventing these harsh chemicals from damaging the underlying high-k dielectric and fin structures while still allowing the etching process to proceed effectively
Solution Approach 2:
The patent creates a composite multi-layer mask structure combining organic materials (BARC and photo resist) with inorganic materials (middle layer). This composite structure leverages the advantages of both material types: the organic layers provide good photo patterning properties while the inorganic middle layer provides chemical resistance, resulting in a mask that protects sensitive underlying structures during etching
2Productivity
If strong acids or alkalis are used for etching, then the etching process can proceed, but dimension control and etching profile are limited due to damage to underlying layers
Solution Approach 1:
The inorganic middle layer serves as a protective intermediary that allows the use of strong acids or alkalis for efficient etching while preventing these chemicals from contacting and damaging the underlying high-k dielectric and fin structures, thereby maintaining both high productivity and manufacturing precision
Solution Approach 2:
The patent changes the chemical composition parameter of the mask structure by introducing an inorganic layer with different chemical resistance properties. This parameter change allows the etching process to use harsh chemicals for efficiency while the inorganic layer's resistance properties prevent damage, achieving both high productivity and precision
3Ease of manufacture
If organic BARC and photo resist are used, then the mask structure can be formed, but high etching selectivity is not achieved
Solution Approach 1:
The patent combines organic materials (BARC and photo resist) with an inorganic middle layer to create a composite mask structure. The inorganic middle layer provides high etching selectivity by being resistant to the etching chemicals used on underlying layers, while the organic layers maintain ease of manufacture through standard photo patterning processes
Solution Approach 2:
The patent applies different material qualities to different layers of the mask structure: the organic BARC and photo resist layers are optimized for ease of formation and patterning, while the inorganic middle layer is specifically designed with high chemical resistance for etching selectivity. Each layer has localized properties optimized for its specific function
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 prevents damage to underlying features, enhances etching selectivity, and improves control over etching processes, reducing the risk of accidental removal or damage to critical layers like high-k dielectric and conductive layers.
Implementation Method 1
the inorganic middle layer is selectively removable using weak acids or alkalis
Implementation Method 2
an inorganic middle layer formed of an amphoteric material, where the inorganic middle layer is selectively removable using weak acids or alkalis
Data Source
AI summary
A method includes forming an etching mask, which includes forming a bottom anti-reflective coating over a target layer, forming an inorganic middle layer over the bottom anti-reflective coating, and forming a patterned photo resist over the inorganic middle layer. The patterns of the patterned photo resist are transferred into the inorganic middle layer and the bottom anti-reflective coating to form a patterned inorganic middle layer and a patterned bottom anti-reflective coating, respectively. The patterned inorganic middle layer is then removed. The target layer is etched using the patterned bottom anti-reflective coating to define a pattern in the target layer.