Wafer-Level LED Absorber Patterning for Secondary Light Suppression
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Solution Overview
Problem
Existing methods for suppressing secondary light emission in optical apparatuses, such as LED chips, are inefficient and often leave undesirable contact grids or metal edges visible, leading to unwanted reflections and light guidance issues.
Innovation Solution
A method involving the application of a photostructurable absorption material at the wafer level to cover regions prone to secondary light emission, allowing precise application and removal of the material to expose emission and electrical connection surfaces, followed by singulation into individual optical apparatuses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional metal masks or absorbing layers are used to suppress secondary light emission, then unwanted reflections are reduced, but the production process becomes complex and visible contact grids remain on standard chips
Solution Approach 1:
The patent extracts and removes the absorption material after it has served its purpose during production. The resist is applied to suppress secondary light emission during manufacturing, then completely removed through chemical etching or mechanical means, leaving no visible traces or contact grids on the final product.
Solution Approach 2:
The absorption material is applied in advance during the production process to prevent secondary light emission from occurring during manufacturing. This preliminary action allows for effective suppression of unwanted reflections before the final product is completed, and the material is subsequently removed.
2Manufacturing precision
If absorption material is applied to cover chip regions to prevent secondary light emission, then light-emitting surface precision is improved, but additional processing steps are required
Solution Approach 1:
The application of absorption material is merged with existing production steps. The resist is applied as part of the standard manufacturing process flow, and its removal is integrated with other processing steps, thereby achieving precise light-emitting surface definition without significantly increasing the total number of processing steps.
3Manufacturing precision
If individual chip processing is used to apply absorption material, then precise coverage is achieved, but production cost increases due to processing each component separately
Solution Approach 1:
The patent applies absorption material to entire wafers containing multiple chips simultaneously, then segments the wafer into individual chips after the absorption material has been applied. This approach maintains precise coverage for each chip while achieving economies of scale by processing many chips in parallel rather than individually.
Solution Approach 2:
The absorption material application process is designed to serve multiple chips on a single wafer simultaneously. The same processing steps and materials are used for all chips in batch, making the process universal and highly efficient while maintaining the precision needed for each individual chip's light-emitting surface.
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
Minimizes or eliminates secondary light emission by precisely covering unwanted emission surfaces and edges, enabling cost-effective production of optical apparatuses like LED point emitters and displays with defined light-emitting surfaces.
Implementation Method 1
a photostructurable resist which absorbs at least the emission wavelength is used as the absorption material
Implementation Method 2
photostructurable resist
Data Source
AI summary
The invention relates to a method for producing an optical apparatus (200). The method comprises a step of providing a substrate (210) on whose first main surface (212) a plurality of emission devices (220) for emitting electromagnetic radiation (250, 255) are arranged. The substrate (210) is designed as a light-emitting diode wafer and/or formed from sapphire or gallium nitride and is transparent at least for one emission wavelength of the radiation (250, 255) emitted by the emission devices (220), The method also comprises a step of applying an absorption material (230) on the side of the first main surface (212) of the substrate (210). The absorption material (230) has a photostructurable resist that absorbs at least the emission wavelength. The method further comprises a step of processing the absorbing material (230) in order to lay bare at least one emission surface (227) of each emission device (220). In this case, a position determination of surfaces to be laid bare is carried out from a second main surface (214) of the substrate (210) opposite the first main surface (212). In addition, the method comprises a step of singulating the substrate (210) into a plurality of optical apparatuses (200) by means of a separating manufacturing process, wherein each optical apparatus (200) has at least one emission device (220).