Angled Mask Features for Ion Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for forming angled structures in optical lenses, such as micro-diffraction gratings, face challenges with non-ideal shape formation due to changing sidewall inclination and shadowing issues during ion etching, leading to suboptimal width and spacing of trenches.
Innovation Solution
The method involves forming angled mask features with sidewalls at a non-zero angle of inclination, using a mask forming layer and directing ions with trajectories aligned parallel to these angles to etch the substrate, minimizing shadowing and maintaining consistent spacing and width of angled structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If directional ions are used to etch a grating layer with a mask disposed on the grating layer, then angled structures are formed, but the sidewalls of the angled structures change inclination as etching proceeds deeper into the substrate layer, leading to a non-ideal shape
Solution Approach 1:
The mask features are pre-formed with angled sidewalls at a specific inclination angle before the etching process. This preliminary angular configuration of the mask serves as a template that guides the ion trajectories, ensuring that the etched structures maintain consistent sidewall inclination throughout the etching depth, thereby resolving the sidewall convergence problem
Solution Approach 2:
The mask layer with angled features acts as an intermediary between the ion beam and the substrate. By positioning the mask between the directional ions and the grating layer, the mask's angled sidewalls redirect the ion trajectories to follow the desired angle, preventing direct shadowing effects and maintaining geometric precision of the final etched structures
2Shape
If directional ions are used to etch the substrate, then angled structures are formed, but shadowing of ions by the mask features causes the width of trenches to be less than desired
Solution Approach 1:
The mask features are pre-formed with angled sidewalls that are specifically designed to match the desired trench angle. This preliminary angular configuration ensures that as etching proceeds, the mask sidewalls continue to define the trench boundaries at the correct angle, preventing shadowing-induced width reduction and maintaining accurate trench dimensions throughout the etching process
3Ease of manufacture
If vertical mask features are used, then simple mask fabrication is achieved, but the resulting angled structures have non-ideal geometry due to shadowing effects
Solution Approach 1:
The mask features are designed with asymmetric angled sidewalls rather than vertical symmetry. This asymmetric angular configuration is specifically tailored to match the desired etch angle, allowing the mask to effectively guide ion trajectories at the required inclination while maintaining fabrication simplicity through standard lithographic patterning followed by angled etching of the mask itself
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 ensures the preservation of intended dimensions and geometry of angled structures, including optical gratings, by aligning ion trajectories with the mask features, preventing sidewall convergence and maintaining consistent width and spacing throughout the etching process.
Implementation Method 1
etching the substrate with the mask in place, the etching comprising directing ions having trajectories arranged at a non-zero angle of incidence with respect to a perpendicular to the main surface
Data Source
AI summary
A method of forming angled structures in a substrate. The method may include the operation of forming a mask by etching angled mask features in a mask layer, disposed on a substrate base of the substrate, the angled mask features having sidewalls, oriented at a non-zero angle of inclination with respect to perpendicular to a main surface of the substrate. The method may include etching the substrate with the mask in place, the etching comprising directing ions having trajectories arranged at a non-zero angle of incidence with respect to a perpendicular to the main surface.