Curved Substrate Etching with Equipotential Depth Uniformity
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Solution Overview
Problem
Traditional microstructure processing methods struggle to achieve uniform etching of diffraction microstructures on curved substrates due to varying electric field strengths, leading to uneven etching rates and low precision.
Innovation Solution
A method involving the formation of a conductive thin film layer with an etched pattern on a curved substrate, ensuring equal potential across the layer by connecting it to a lower electrode, allowing for consistent etching depth through reactive ion etching, and subsequent removal of the thin film to create uniform micro-nano structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a traditional RIE method with a flat plate electrode is used, then the etching process is simple to implement, but the etching uniformity across the curved substrate deteriorates due to varying electric field strengths
Solution Approach 1:
The patent applies the equipotentiality principle by making the lower electrode conform to the curved surface of the substrate. This ensures that the entire surface of the curved substrate is at the same potential during etching, eliminating the varying electric field strengths that occur with flat plate electrodes. The conformal electrode design maintains uniform etching rates across the entire curved surface, directly resolving the contradiction between ease of implementation and etching uniformity.
2Device complexity
If a flat plate lower electrode is used in RIE, then the device structure is simple, but the etching rate varies across different positions of the curved substrate
Solution Approach 1:
The patent applies the curvature principle by designing the lower electrode to match the curved geometry of the substrate. Instead of using a flat plate electrode that creates non-uniform electric fields, the electrode is formed with the same curvature as the substrate surface. This curved electrode configuration ensures uniform electric field distribution and consistent etching rates across the entire curved substrate, effectively resolving the contradiction between device simplicity and etching precision.
3Ease of manufacture
If traditional turning methods using diamond lathes are used, then the processing equipment is conventional and readily available, but the processing accuracy of curved microstructures deteriorates
Solution Approach 1:
The patent applies the mechanics substitution principle by replacing mechanical turning methods with a reactive ion etching process. Instead of using diamond lathes for mechanical machining, the invention uses RIE with a conformal lower electrode to achieve precise curved microstructure fabrication. This substitution enables processing accuracy of a few tens of nanometers, far exceeding the capabilities of conventional mechanical methods while still using readily available semiconductor processing equipment.
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 uniform etching across the entire curved substrate, overcoming the challenge of uneven etching rates and achieving high precision in micro-nano structure transfer, particularly on dielectric materials like quartz and silicon, enabling the production of functional devices with complex curved surfaces.
Implementation Method 1
connecting the conductive thin film layer with the lower electrode, such that the potential at each position of the conductive thin film layer is consistent with a potential at the lower electrode
Implementation Method 2
by using a reactive ion etching (RIE) method, a patterned microstructure of the photoresist layer is transferred to an optical material substrate
Data Source
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AI summary
A method for etching a curved substrate is provided, including: forming a conductive thin film layer (15) with an etched pattern on the curved substrate; supplying power to the conductive thin film layer (15) such that the conductive thin film layer has an equal potential at each position of the conductive thin film layer; etching each position of the curved substrate to an etching depth corresponding to the potential at each position of the conductive thin film layer (15) based on the etched pattern of the conductive thin film layer (15), so as to obtain the curved substrate having a consistent etching depth at each position of the curved substrate. With the etching method, it is possible to etch an arbitrary curved surface to obtain a microstructure with a uniform processing depth.