Etching Method for High Aspect Ratio Recesses
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Solution Overview
Problem
In the manufacturing of semiconductor devices, fine etching of SiN or Si on high aspect ratio grooves or holes often results in non-uniform etching due to the loading effect, where the top portion is preferentially etched, leading to uneven etching between the top and bottom portions.
Innovation Solution
An etching method involving an oxygen-containing plasma process to modify the surface of the etching target portion at the top of the recess, followed by isotropic dry-etching, which reduces the loading effect and achieves uniform etching by forming a modified layer that suppresses etching at the top portion while allowing more etching at the bottom portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If isotropic dry-etching is performed directly on SiN or Si in high aspect ratio recesses, then etching speed is maintained, but etching uniformity deteriorates due to loading effect causing preferential etching at top portions
Solution Approach 1:
An oxygen-containing plasma process is performed before the isotropic dry-etching process to modify the surface of the etching target portion at the top portion of the recess. This preliminary modification creates a protective layer that suppresses preferential etching at the top, enabling uniform etching throughout the recess while maintaining efficient etching speed.
Solution Approach 2:
The patent changes the chemical state of the etching target surface by performing an oxygen-containing plasma process that modifies the surface properties. This parameter change (from pristine SiN/Si surface to oxygen-modified surface) creates differential etching resistance between top and bottom portions, achieving uniform etching while maintaining overall etching efficiency.
2Manufacturing precision
If oxygen-containing plasma process is performed to modify the top portion surface, then etching uniformity is improved, but process complexity increases
Solution Approach 1:
The oxygen-containing plasma process and the isotropic dry-etching process are performed in the same processing container without requiring transfer between different equipment. This merging of processes reduces equipment complexity and simplifies the overall manufacturing flow while achieving improved etching uniformity.
Solution Approach 2:
The patent achieves process simplification by changing the gas composition parameter within the same etching system. By adjusting from oxygen-containing plasma to fluorine-containing etching gas, the system performs both surface modification and etching functions, reducing the need for additional equipment while improving uniformity.
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 ensures more uniform etching of SiN or Si on the inner surface of recesses by reducing the difference in etched amounts between the top and bottom portions, enhancing the uniformity and efficiency of the etching process.
Implementation Method 1
preferentially modifying a surface of the etching target portion at a top portion of the recess by performing an oxygen-containing plasma process on the substrate inside the processing container
Implementation Method 2
performing an oxygen-containing plasma process on the substrate inside the processing container; subsequently, dry-etching the etching target portion in an isotropic manner
Data Source
AI summary
There is provided an etching method including: loading a substrate having a recess and an etching target portion existing on an inner surface of the recess into a processing container, the etching target portion being made of SiN or Si; preferentially modifying a surface of the etching target portion at a top portion of the recess by performing an oxygen-containing plasma process on the substrate inside the processing container; and subsequently, dry-etching the etching target portion in an isotropic manner.