Remote Plasma Etch Selectivity via Precursor Excitation
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Solution Overview
Problem
Existing remote plasma etch processes face challenges in achieving selective etching of patterned substrates with off-the-shelf hardware, particularly in controlling etch rates and reducing plasma power to prevent damage to miniature structures.
Innovation Solution
The method involves exciting inert species in a remote plasma to form plasma effluents that interact with an oxidizing precursor in a remote chamber, creating a distinct plasma-free environment for etching, allowing for controlled etching of patterned substrates with a first exposed portion etching at a higher rate than a second exposed portion, while reducing plasma power and extending component longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If remote plasma is used for etching, then selectivity is improved, but plasma power must be reduced to prevent damage to miniature structures
Solution Approach 1:
The system divides the plasma generation and substrate processing into separate spatial zones. A remote plasma source generates plasma in a first chamber, which then flows into a second chamber where substrate processing occurs. This segmentation allows high plasma power to be applied in the remote source without directly exposing the substrate to high power plasma, thereby maintaining both etch selectivity and preventing damage to miniature structures.
Solution Approach 2:
The patent introduces an intermediary remote plasma chamber that acts as a buffer between the plasma source and substrate. Plasma effluents from the remote plasma source travel through this intermediary region before reaching the substrate, allowing energy dissipation and species transformation. This intermediary zone enables the use of high plasma power to generate reactive species while protecting the substrate from direct high-power plasma exposure.
2Device complexity
If off-the-shelf remote plasma hardware is used, then device complexity is reduced, but selectivity control is limited
Solution Approach 1:
The system achieves enhanced selectivity control by manipulating process parameters rather than hardware complexity. By adjusting gas flow rates, pressure conditions, and precursor compositions in the remote plasma chamber, the patent optimizes the composition and reactivity of plasma effluents. This allows standard hardware to deliver selective etching through careful parameter optimization, maintaining simplicity while achieving precision.
Solution Approach 2:
The patent creates locally optimized conditions in different chamber regions. The remote plasma chamber is configured with specific gas compositions and flow patterns to generate plasma effluents with desired reactive species concentrations. Downstream in the substrate chamber, different local conditions (pressure, flow velocity, temperature) are maintained to control the interaction between plasma effluents and substrate, achieving selective etching without complex hardware modifications.
3Productivity
If high etch rate is achieved on first exposed portion, then productivity is improved, but etch rate uniformity across different materials becomes difficult to control
Solution Approach 1:
The system dynamically controls etch rates for different materials by adjusting plasma effluent composition and flow conditions. By varying the ratio of reactive to inert species in the plasma effluents, and by controlling flow rates and residence times, the system can optimize etch rates for different material types. This dynamic control allows high productivity for primary materials while maintaining appropriate etch rates for secondary materials through parameter adjustment rather than fixed hardware configurations.
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 enables a well-controlled, selective etching process with reduced plasma power, increasing the longevity of chamber components and achieving a high etch rate difference between substrate portions, thus addressing the limitations of existing remote plasma etch technologies.
Implementation Method 1
exciting inert species in a remote plasma to form plasma effluents
Implementation Method 2
The first plasma effluents interact with the oxidizing precursor in a remote chamber region and form second plasma effluents
Data Source
AI summary
Methods of selectively etching an exposed portion of a patterned substrate relative to a second exposed portion are described. The etching process is a gas phase etch which uses an oxidizing precursor unexcited in any plasma prior to combination with plasma effluents formed in a remote plasma from an inert precursor. The plasma effluents may be combined with the oxidizing precursor in a plasma-free remote chamber region and/or in a plasma-free substrate processing region. The combination of the plasma effluents excites the oxidizing precursor and removes material from the exposed portion of the patterned substrate. The etch rate is controllable and selectable by adjusting the flow rate of the oxidizing precursor or the unexcited/plasma-excited flow rate ratio.