Plasma Etching Monolayer Removal via Adsorption Desorption Cycling
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Solution Overview
Problem
Conventional plasma processing techniques for semiconductor manufacturing face challenges in achieving high precision etching with minimal damage, particularly due to aspect ratio and profile variation issues during selective etching of microelectronic features.
Innovation Solution
The method involves transitioning between adsorption and desorption plasma states to selectively remove monolayers from semiconductor substrates, utilizing a plasma processing system that alternates between different plasma conditions, including varying gas mixtures, power, and pressure, to achieve high precision etching with self-limiting etch selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma processing techniques are used for selective etching, then etching precision may be improved, but aspect ratio and profile variation issues worsen
Solution Approach 1:
The patent applies periodic action by alternating between adsorption plasma and desorption plasma in cyclic pulses. The adsorption plasma deposits material to form a protective layer, while the desorption plasma removes material selectively. This periodic switching enables precise control over etching depth and profile, maintaining manufacturing precision while avoiding aspect ratio and profile variation issues that plague conventional continuous etching methods.
Solution Approach 2:
The patent utilizes parameter changes by varying plasma conditions (such as gas composition, power, and pressure) between the adsorption and desorption phases. During adsorption, parameters are optimized for material deposition, while during desorption, parameters are adjusted to maximize selective removal. This dynamic parameter adjustment allows the process to achieve high etching precision while maintaining uniform profiles and aspect ratios.
2Productivity
If plasma treatment is applied to remove monolayers, then etching speed may be improved, but damage to underlying substrate increases
Solution Approach 1:
The patent applies preliminary action by using adsorption plasma to deposit a protective layer on the substrate surface before the desorption plasma acts on it. This pre-formed layer serves as a sacrificial barrier that the desorption plasma can selectively remove. The underlying substrate is thus protected from direct exposure to the aggressive desorption plasma, enabling faster etching speeds without increasing substrate damage.
Solution Approach 2:
The adsorbed layer acts as an intermediary between the desorption plasma and the underlying substrate. This intermediate layer absorbs the harmful effects of the desorption plasma, allowing rapid material removal while shielding the substrate from damage. The intermediary layer is designed to be selectively removable, enabling high productivity while protecting the substrate from harmful plasma exposure.
3Manufacturing precision
If alternating plasma deposition and etching is used, then etching precision may be improved, but cycle time increases
Solution Approach 1:
The patent maintains continuity of useful action by ensuring that the transition between adsorption and desorption plasma phases is seamless and optimized. Both phases contribute productively to the overall etching process - adsorption forms the protective layer while desorption removes material. By eliminating idle transition times and optimizing the duration of each phase, the process achieves high etching precision without significant cycle time penalties compared to conventional methods.
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 the systematic removal of monolayers with high precision, minimizing damage to underlying substrates by exploiting differences in etch selectivity between the adsorbed layer and the substrate, thereby improving etching accuracy and reducing cycle time constraints.
Implementation Method 1
the adsorption plasma may be used to pre-treat or prepare portions of the substrate that may be removed by the desorption plasma
Implementation Method 2
the adsorption plasma may be used to pre-treat or prepare portions of the substrate that may be removed by the desorption plasma
Data Source
AI summary
A plasma processing system and methods for high precision etching of microelectronic substrates. The system may include a combination of microwave and radio frequency (RF) power sources that may generate plasma conditions to remove monolayer(s). The system may generation a first plasma to form a thin adsorption layer on the surface of the microelectronic substrate. The adsorbed layer may be removed when the system transition to a second plasma. The differences between the first and second plasma may be include the ion energy proximate to the substrate. For example, the first plasma may have an ion energy of less than 20 eV and the second plasma may have an ion energy greater than 20 eV.