Surface Treatment for Complete Crystallite Removal on Epitaxial Substrates
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Solution Overview
Problem
Existing surface treatment methods, such as the 'Etch back' method, are ineffective in completely removing crystallites from substrates due to their geometry and size disparity, particularly when patterns have inclined flanks, as plasma etching fails to remove lateral portions of the bottom part of the patterns.
Innovation Solution
A surface treatment method involving the formation of a protection layer and a flattening layer on a substrate, followed by selective wet chemical etching to expose and remove the masses of matter, allowing for complete elimination of crystallites regardless of geometry or size, using a protection layer that acts as an etch mask to protect the areas of selective epitaxy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma etching is used to remove patterns, then etching efficiency is improved, but complete removal of patterns with inclined flanks and size disparity cannot be achieved
Solution Approach 1:
The etching process is divided into multiple sequential steps: first wet chemical etching to remove lateral portions of patterns, then plasma etching to remove remaining pattern material. This segmentation allows each etching method to address specific portions of the pattern removal task, achieving complete elimination of patterns with inclined flanks while maintaining high overall efficiency
Solution Approach 2:
A flattening layer is deposited beforehand on the substrate surface before etching. This preliminary action creates a uniform starting surface that enables the subsequent wet chemical etching to effectively access and remove lateral portions of patterns that would otherwise be inaccessible due to inclined flanks and size variations
2Area of stationary object
If a flattening layer is deposited on structured surfaces, then surface coverage is improved, but lateral portions of pattern bottom parts remain after plasma etching
Solution Approach 1:
The etching process applies different etching methods to different regions: wet chemical etching targets lateral portions of pattern bottom parts, while plasma etching removes the remaining vertical portions. This local differentiation of etching approaches ensures complete pattern removal across all surface areas, including regions with inclined flanks and size disparities
3Manufacturing precision
If wet chemical etching is used to clear border areas, then complete pattern elimination is achieved, but processing time increases
Solution Approach 1:
The wet chemical etching and plasma etching steps are merged into a unified multi-step etching process. The wet chemical etching step is optimized to quickly remove lateral portions of patterns, while the subsequent plasma etching step efficiently removes remaining material. This combination achieves complete pattern elimination without excessive processing time by leveraging the complementary strengths of both etching 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
The method enables the total removal of crystallites with inclined flanks and varying sizes by using wet chemical etching to clear border areas, facilitating subsequent plasma etching and ensuring the protection of selective epitaxy areas, thus overcoming the limitations of existing methods.
Implementation Method 1
etching, by a wet chemical etching, the exposed top areas of the protection layer and lateral areas of the protection layer extending at the border of the masses of matter, the wet chemical etching being executed by an etching agent allowing a selective etching of the second material with respect to the first material
Implementation Method 2
The areas of the flattening layer, facing the top parts of the patterns, are removed by thinning of the flattening layer (e.g. etching) so as to expose the top parts of the patterns. Then, the patterns are removed by a plasma etching.
Data Source
AI summary
A surface treatment method includes providing a substrate with a surface having areas of selective epitaxy of a first material and masses of matter of the first material; forming a protection layer, produced in a second material, on the surface of the substrate; and forming a flattening layer on the protection layer. Areas of the flattening layer facing the masses of matter and top areas of the protection layer are removed so as to expose the masses of matter. Lateral areas of the protection layer are etched by a selective wet chemical etching. The flattening layer is removed; the masses of matter are etched, the protection layer forming an etch mask; and protection layer is removed.