Wet Etching Orientation Control for Curved Semiconductor Channels
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Solution Overview
Problem
Current semiconductor fabrication techniques, such as wet and dry etching, face challenges in achieving high aspect ratio channels with specific geometries, particularly bent or curved channels, due to limitations in directional control and etch rate precision.
Innovation Solution
The use of metal-assisted chemical etching with a silver catalyst and a hydrogen fluoride/hydrogen peroxide etchant solution, combined with controlled orientation of the semiconductor relative to gravity, allows for the precise formation of channels with arbitrary geometries by adjusting the semiconductor's orientation during the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional wet or dry etching techniques are used, then etching can be performed on semiconductor structures, but achieving high aspect ratio channels with specific geometries (particularly bent or curved channels) is difficult due to limitations in directional control and etch rate precision
Solution Approach 1:
A metal catalyst layer is introduced as an intermediary between the etchant solution and the semiconductor substrate. This catalyst layer enables selective chemical reactions that facilitate precise etching of high aspect ratio channels with controlled geometries, including bent and curved configurations, while maintaining process feasibility
Solution Approach 2:
The etching process utilizes controlled changes in semiconductor orientation relative to gravity during metal-assisted chemical etching. By adjusting the orientation parameter dynamically, the method achieves precise control over channel geometry and etch rates, enabling formation of channels with arbitrary geometries including bent and curved shapes
2Manufacturing precision
If metal-assisted chemical etching with controlled orientation is used, then channels with high aspect ratios and complex geometries can be formed with precise control, but the process requires maintaining specific orientation relative to gravity during etching
Solution Approach 1:
The semiconductor substrate orientation is made dynamic during the etching process rather than fixed. The substrate is rotated or repositioned at different stages of metal-assisted chemical etching to control the direction and geometry of channel formation. This dynamic orientation control enables precise manipulation of etch rates and channel shapes while maintaining ease of operation through automated positioning mechanisms
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 method enables the creation of channels with high aspect ratios and complex geometries, such as bent or curved channels, with controlled etch rates and precise cross-sectional dimensions, overcoming the limitations of traditional etching techniques.
Implementation Method 1
catalyzing an etching chemical reaction between the etchant solution and the semiconductor using the metal catalyst
Implementation Method 2
holding the semiconductor immersed in the etchant solution with a surface normal of the surface of the semiconductor at a non-zero angle respective to gravity
Data Source
AI summary
A method of fabricating a semiconductor structure includes disposing a metal catalyst on a surface of a semiconductor. Thereafter, metal assisted chemical etching is performed, including holding the semiconductor immersed in an etchant solution and catalyzing an etching chemical reaction between the etchant solution and the semiconductor using the metal catalyst to etch the semiconductor to form a channel in the semiconductor. During at least a portion of the metal assisted chemical etching the semiconductor is held immersed in the etchant solution with a surface normal of the surface of the semiconductor at a non-zero angle respective to gravity. In some examples, an orientation of the semiconductor is changed during the metal assisted chemical etching to form the channel in the semiconductor with at least one bend or curved portion.