Plasma Etching Sequence for Low-Roughness Silicon Recesses
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Solution Overview
Problem
Conventional etching methods for silicon-containing films in manufacturing electronic devices, such as NAND flash memory, result in carbon deposition on masks, leading to uneven etching and increased edge roughness of recesses.
Innovation Solution
A multi-step etching process using first, second, and third plasmas generated from different process gases, including a tungsten-containing gas, to form a recess with reduced edge roughness by forming conductive tungsten-containing layers on the side walls of the recess.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fluorine-based plasma is used for etching silicon-containing films, then etching speed is maintained, but carbon deposition on mask increases leading to edge roughness
Solution Approach 1:
The patent converts the harmful carbon deposition on mask into a beneficial protective layer by introducing a carbon-containing film between the mask and silicon-containing film. This intermediate carbon layer prevents direct carbon deposition on the mask while maintaining etching performance, thus reducing edge roughness.
Solution Approach 2:
The patent introduces a carbon-containing film as an intermediary layer between the mask and silicon-containing film. This intermediate layer acts as a mediator that prevents direct interaction between the mask and etching plasma, thereby preventing carbon deposition on the mask and reducing edge roughness.
2Reliability
If carbon-containing deposit is formed on mask to protect it, then mask protection is improved, but etching uniformity deteriorates
Solution Approach 1:
The patent applies different properties to different parts of the system: the carbon-containing film provides local protection at the mask interface where carbon deposition occurs, while maintaining uniform etching properties in the bulk etching region. This localized quality improvement protects the mask without compromising etching 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
The method achieves a recess with intended shape and reduced edge roughness, enhancing the precision and uniformity of silicon-containing film etching, particularly in three-dimensional structures.
Implementation Method 1
etching the silicon-containing film with first plasma generated from a first process gas to form a recess
Implementation Method 2
forming conductive tungsten-containing layers on the side walls of the recess
Data Source
AI summary
An etching method and a plasma processing apparatus form a recess with an intended shape. The etching method includes (a) providing a substrate, the substrate including a silicon-containing film and a mask on the silicon-containing film; (b) etching the silicon-containing film with a first plasma to form a recess, the first plasma generated from a first process gas; (c) supplying a second plasma to the substrate, the second plasma generated from a second process gas comprising tungsten; and (d) etching the recess with a third plasma generated from a third process gas.