SiC Optical Filter Coating for Reduced Angle Shift
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Solution Overview
Problem
Existing optical filters face challenges in achieving reduced angle shift in visible, near infrared, and extreme ultraviolet wavelengths due to the limited availability of high refractive index materials and the difficulty in sputtering materials like TiO2, which leads to scatter loss and requires extensive layering.
Innovation Solution
The use of silicon carbide (SiC) as a high refractive index material, combined with low refractive index materials like SiO2, and a dual cathode sputtering process with controlled hydrogen and argon gas flows, along with annealing, to deposit thin films with improved light transmission and reduced angle shift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If TiO2 is used as a high refractive index material, then the optical filter can achieve reduced angle shift, but the sputtering process becomes difficult and scatter loss increases
Solution Approach 1:
The patent changes the material parameter from TiO2 to SiC, which has different physical and chemical properties. SiC has a refractive index of approximately 2.65 in the visible range, making it suitable for optical filter applications while being much easier to sputter deposit without causing scatter loss.
Solution Approach 2:
The patent employs a disposable target approach where a SiC target is used for sputtering. The target can be readily replaced when depleted, simplifying the manufacturing process. The SiC target material is consumed during the sputtering process to deposit films on substrates.
2Measurement precision
If TiO2 is sputtered to form optical filter layers, then reduced angle shift is achieved, but scatter loss increases
Solution Approach 1:
The patent changes the material parameter from TiO2 to SiC, which produces smoother film deposits with fewer scattering centers. SiC films exhibit lower scatter loss while maintaining the necessary refractive index for reduced angle shift performance in optical filters.
3Measurement precision
If extensive layering is used to achieve optical filter performance, then reduced angle shift is achieved, but device complexity increases
Solution Approach 1:
The patent changes the material parameter to SiC, which has superior sputtering characteristics and forms high-quality films with fewer defects. This allows for simpler layer structures to achieve the same optical performance that would require extensive layering with TiO2.
4Quantity of substance
If RF sputtering is used to deposit silicon carbide, then silicon carbide films can be produced, but deposition rate is slow
Solution Approach 1:
The patent replaces the RF sputtering process with a different deposition mechanism that achieves higher productivity. The alternative process maintains the ability to produce silicon carbide films while significantly increasing the deposition rate beyond the single angstroms per second achieved by RF sputtering.
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 solution results in optical filters with enhanced light transmission in visible and near infrared wavelengths, reducing angle shift and enabling applications in three-dimensional sensing, while minimizing scatter loss and layer thickness.
Implementation Method 1
a cathode sputter-deposition system, introducing, to a process chamber of a cathode sputter-deposition system, a first target including a high refractive index material
Implementation Method 2
the optical filter exhibits a reduced angle shift in at least one of a visible, near infrared, and an extreme ultraviolet wavelength
Data Source
AI summary
An optical filter including at least one of a high refractive index material and a low refractive index material; wherein the optical filter exhibits a reduced angle shift in at least one of a visible, near infrared, and an extreme ultraviolet wavelength is disclosed. A method of depositing a film is also disclosed.