In Situ Declogging for High-Aspect-Ratio Plasma Etching
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Solution Overview
Problem
Plasma etching in semiconductor device fabrication is hindered by the inadvertent deposition of clogging materials in recessed features, leading to slowed processes and non-uniformity, particularly in the formation of high aspect ratio recessed features.
Innovation Solution
A method involving alternating plasma etching and declogging steps, where the declogging step is performed in situ without external biasing, using a halogen source and optionally an organic solvent or water vapor, to remove the clogging material without altering the critical dimensions of the features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If plasma etching is used to form recessed features, then directional etching capability is improved, but clogging material deposition narrows the recessed features and slows the process
Solution Approach 1:
The patent applies periodic action by alternating between plasma etching steps and declogging steps. The plasma etching step deposits clogging material that narrows the recessed features, while the subsequent declogging step using halogen source removes this material. This periodic alternation maintains etching speed while preventing feature narrowing and non-uniformity, directly resolving the technical contradiction between etching speed and feature uniformity.
2Object-generated harmful factors
If conventional declogging methods using organic solvents or water are used, then clogging material removal is achieved, but substrate damage and critical dimension alteration occur
Solution Approach 1:
The patent applies parameter changes by using a halogen source (such as CF4, CCl4, or CBr4) instead of conventional organic solvents or water for declogging. The halogen source reacts with the clogging material through chemical reactions to form volatile products that can be removed, providing effective declogging without the substrate damage and critical dimension alteration caused by conventional liquid-based methods. This parameter change in the declogging chemistry resolves the contradiction between effective clogging removal and maintaining feature integrity.
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
Enables efficient formation of high aspect ratio recessed features with minimal damage and uniformity, allowing for faster processing and maintaining the integrity of the substrate features.
Implementation Method 1
etching the target material using a plasma etch
Implementation Method 2
etching the clogging material by contacting the semiconductor substrate with a halogen source
Data Source
AI summary
In semiconductor processing. plasma etching of materials (e.g., of carbon or silicon) to form vertical high aspect ratio recessed features can lead to clogging inside the recessed features due to unwanted deposition of a mask-derived clogging material (e.g., silicon oxide). This is addressed by declogging, which includes etching the clogging material preferably in the same process chamber by contacting the substrate with a halogen source. After the declogging step, plasma etching proceeds further. The declogging and plasma etching steps can be repeated as many times as needed to etch a recessed feature of desired depth.