Plasma Etch Reactor Sidewall Protection via Cyclical Polymer Deposition
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Solution Overview
Problem
The cyclical etch process in some etch reactors lacks effective control, leading to increased sidewall roughness and longer etching durations due to poor deposition control, resulting in defective microelectronic devices.
Innovation Solution
A method involving the deposition of a polymer on substrate features using a polymer-forming gas, followed by etching with an etching gas and bombarding with inert, oxidizing, or reducing gases to remove the polymer and damage the surface, repeated until the desired depth is achieved, utilizing a plasma etch reactor with controlled RF and bias power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cyclical etch process with deposition steps is used to protect sidewalls, then sidewall protection is improved, but sidewall roughness increases and manufacturing precision deteriorates
Solution Approach 1:
The patent employs periodic switching between etching and deposition phases within each etch cycle. The deposition phase deposits protective species on sidewalls during etching, while the etching phase removes material from the substrate bottom. This periodic action allows sidewall protection without continuous deposition that would cause roughness, resolving the contradiction between protection and precision.
Solution Approach 2:
The patent changes process parameters dynamically during the etch cycle by adjusting gas flow rates, RF power, and pressure between etching and deposition phases. By optimizing these parameters, the deposition rate is controlled to provide just enough protection without excessive material buildup that would increase roughness, thus maintaining manufacturing precision while ensuring sidewall protection.
2Reliability
If deposition species are not well controlled, then deposition on surfaces to be etched occurs, but etching duration increases
Solution Approach 1:
The patent performs preliminary deposition of protective species on sidewalls before the main etching operation begins. By pre-coating the sidewalls with protective material, the subsequent etching process can proceed more efficiently without needing to repeatedly deposit and remove material, thus reducing overall etching duration while maintaining good deposition control.
Solution Approach 2:
The patent implements feedback control by monitoring the deposition rate and adjusting process parameters in real-time. When deposition on etched surfaces is detected, the system adjusts gas flows or timing to correct the imbalance, preventing excessive deposition that would require longer etching to remove, thereby optimizing etching duration while maintaining deposition control.
3Manufacturing precision
If additional process steps are added to remove deposition species, then deposition control is improved, but device complexity and process time increase
Solution Approach 1:
The patent merges the deposition and etching operations into a single integrated cyclical process. The deposition phase and etching phase are combined in alternating sequences within one etch cycle, eliminating the need for separate additional process steps to remove deposition species. This integration maintains precise deposition control while reducing overall process complexity and time.
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 reduces etching duration and achieves smoother surfaces by precise control over the etching process, preventing scalloping and undercutting, thereby improving the quality of etched features.
Implementation Method 1
depositing a polymer on surfaces of a feature formed in a substrate disposed in the etch reactor using a first reactive species formed from a first process gas comprising a polymer forming gas
Implementation Method 2
etching the bottom surface of the feature of the substrate in the etch reactor using a third reactive species formed from a third process gas including an etching gas
Implementation Method 3
bombarding a bottom surface of the feature with a second reactive species formed from a second process gas comprising one or more of an inert gas, an oxidizing gas, a reducing gas, or the polymer forming gas
Data Source
AI summary
Methods for etching a substrate in a plasma etch reactor may include (a) depositing polymer on surfaces of a feature formed in substrate disposed in the etch reactor using first reactive species formed from a first process gas comprising a polymer forming gas; (b) etching the bottom surface of the feature of the substrate in the etch reactor using a third reactive species formed from a third process gas including an etching gas; and (c) bombarding a bottom surface of the feature with a second reactive species formed from a second process gas comprising one or more of an inert gas, an oxidizing gas, a reducing gas, or the polymer forming gas while at least one of depositing the polymer to remove at least some of the polymer disposed on the bottom surface or etching the bottom surface to at least one of chemically or physically damage the bottom surface.