Optical Filter Array Structure for Sub-10 µm Sensor Spacing
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Solution Overview
Problem
Existing optical devices face challenges in manufacturing sensor element arrays with spacings less than approximately 20 µm, which is necessary as device quantities increase and package sizes decrease.
Innovation Solution
A filter array is disposed on a substrate with spacers of varying thicknesses, including niobium titanium oxide (NbTiOx) layers, to achieve sensor element spacings of less than 10 µm, using deposition processes like PVD and CVD, and mirror layers to align with sensor elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sensor elements are spaced greater than approximately 20 µm, then manufacturing is easier and alignment is simpler, but device quantity increases and package size decreases become difficult to achieve
Solution Approach 1:
The patent introduces an optical filter array with varying thicknesses as an intermediary layer between the substrate and sensor elements. This filter array serves as a mediator that enables precise spacing control and alignment, allowing sensor elements to be positioned closer together (less than 10 µm) while maintaining manufacturing feasibility. The filter array's variable thickness profile acts as a spacing guide that facilitates both close spacing and accurate alignment during fabrication.
Solution Approach 2:
The patent applies parameter changes by varying the thickness of the optical filter array across different regions. By controlling the filter thickness parameter spatially (thinner regions for certain sensor elements, thicker regions for others), the patent enables precise control of light transmission characteristics and spacing. This parameter variation allows the system to achieve less than 10 µm spacing between sensor elements while maintaining manufacturability through standard deposition processes.
2Productivity
If sensor element spacing is reduced to less than 10 µm, then device quantity increases and package size decreases, but manufacturing precision requirements increase
Solution Approach 1:
The patent implements preliminary action by pre-forming the optical filter array with predetermined thickness variations before positioning and bonding the sensor elements. The filter array is deposited with specific thickness profiles in advance, creating ready-to-use spacing guides and alignment references. This preliminary preparation eliminates the need for high-precision adjustments during final assembly, enabling less than 10 µm spacing to be achieved with standard manufacturing tolerances.
Solution Approach 2:
The optical filter array serves as an intermediary spacing and alignment reference that simplifies the manufacturing of closely spaced sensor elements. By incorporating the spacing information directly into the filter array structure during deposition, the patent transforms a high-precision positioning problem into a more manageable material deposition problem, achieving less than 10 µm spacing with conventional manufacturing processes.
3Measurement precision
If optical filters are designed with specific thicknesses to pass particular spectral ranges, then spectral detection capability is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by assigning different filter thicknesses to different spatial regions of the optical filter array, with each region optimized for specific spectral detection requirements. Rather than using a uniform filter structure, the patent varies the local thickness parameter to match the spectral detection needs of underlying sensor elements, enabling multi-spectral capability while keeping each local region's filter design relatively simple.
Solution Approach 2:
The optical filter array serves multiple functions simultaneously: it acts as a spacing guide for closely spaced sensor elements, provides alignment references, and implements spectral filtering. By integrating these multiple functions into a single variable-thickness filter array structure, the patent avoids the complexity that would arise from separate components for each function, achieving spectral detection capability without proportionally increasing device complexity.
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 enables sensor element arrays with reduced spacings, improved transmissivity, and reduced angle shift, suitable for hyperspectral imaging and depth sensing systems.
Implementation Method 1
different ones of the optical filters being configured to have a different thickness, to pass different bands of wavelengths by means of interference
Implementation Method 2
The plurality of spacers may be deposited onto the substrate using at least one of: a physical vapor deposition (PVD) process
Implementation Method 3
The first mirror or the second mirror may be a quarterwave stack including a low refractive index material and a high refractive index material
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A device may include a filter array disposed on a substrate. The filter array may include a first mirror disposed on the substrate. The filter array may include a plurality of spacers disposed on the first mirror. A first spacer, of the plurality of spacers, may be associated with a first thickness. A second spacer, of the plurality of spacers, may be associated with a second thickness that is different from the first thickness. A first channel corresponding to the first spacer and a second channel corresponding to the second spacer may be associated with a separation width of less than approximately 10 micrometers (µm). The filter array may include a second mirror disposed on the plurality of spacers.