VCSEL Microlens Wafer Processing with Low-Reflective Layer
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Solution Overview
Problem
The manufacturing process of light emitting devices, such as LED and VCSEL arrays, is slow and costly due to the separate production and alignment of microlens arrays, which often result in unwanted polymerization on bond pads and saw lines, causing contamination and wirebonding issues.
Innovation Solution
A processing layer is integrated with the light emitting structure to reduce reflection and absorption of curing light, allowing direct replication of microlens arrays on the wafer, thereby avoiding separate alignment and reducing reflection at lateral structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If microlens arrays are separately manufactured and actively aligned above VCSEL arrays, then alignment precision can be achieved, but manufacturing time and cost increase significantly
Solution Approach 1:
The patent merges the microlens array manufacturing process with the VCSEL array fabrication process by integrating the optical structure directly into the semiconductor wafer. The optical structure is formed as part of the same wafer fabrication sequence, eliminating the need for separate microlens manufacturing and subsequent alignment operations, thus resolving the contradiction between alignment precision and manufacturing speed
Solution Approach 2:
The optical structure is prepared in advance during the wafer fabrication process itself, before final assembly. By forming the optical structure as an integrated part of the VCSEL wafer during the same fabrication sequence, the alignment issue is preemptively resolved, enabling high-speed manufacturing without sacrificing precision
2Ease of manufacture
If curing light is used to solidify optical structure material on VCSEL wafer, then optical structure can be formed, but unwanted polymerization occurs on bond pads and saw lines causing contamination
Solution Approach 1:
The patent applies local quality by providing laterally structured shielding at specific locations (bond pads and saw lines) on the VCSEL wafer. These localized shielding structures selectively block curing light only where unwanted polymerization would occur, while allowing the optical structure to be properly cured in the desired regions, thus eliminating contamination without compromising the optical formation process
Solution Approach 2:
The shielding structures act as intermediaries between the curing light and the sensitive areas (bond pads and saw lines). By introducing these intermediate elements, the harmful polymerization effect is blocked at the source, preventing direct interaction between the curing light and the areas where polymerization would cause contamination
3Object-affected harmful factors
If processing light reflection is reduced by processing layer, then unwanted polymerization is eliminated, but manufacturing process complexity increases
Solution Approach 1:
The patent employs parameter changes by utilizing the optical properties (refractive index, thickness) of the processing layer to control light reflection. By carefully selecting and optimizing these parameters, the processing layer achieves effective reflection reduction to prevent unwanted polymerization, while the added structural complexity remains manageable through parameter optimization rather than complex multi-layer designs
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 method enhances manufacturing efficiency by eliminating unwanted polymerization and improving adhesion, allowing higher temperature processing without damage to the optical structure.
Implementation Method 1
The processing layer is adapted to reduce reflection of processing light in a direction of at least one material for building an optical structure at least by 50%, preferably at least by 80%, more preferably at least by 95% and most preferably at least by 99%
Implementation Method 2
The processing layer is adapted to absorb a significant part of the processing light which is used to solidify or cure the optical structure
Implementation Method 3
providing processing light for curing the at least one material to build the optical structure
Implementation Method 4
The process step of providing at least one processing layer may comprise the step of providing or disposing an titanium layer and thermally oxidizing at least a part of the titanium layer to titanium oxide respectively titanium dioxide
Data Source
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AI summary
The invention describes a light emitting device (100). The light emitting device (100) comprises at least one light emitting structure (110), at least one processing layer (120) and at least one optical structure (130). The optical structure (130) comprises at least one material processed by means of processing light (150). The at least one processing layer (120) is arranged to reduce reflection of the processing light (150) ina direction of the optical structure (130) at least by 50%, preferably at least by 80%, more preferably at least by 95% and most preferably at least by 99% during processing of the material by means of the processing light (150). It is a basic idea of thepresent invention to incorporate a non-or low- reflective processing layer (120) on top of a light emitting structure (110) like a VCSEL array in order to enable on wafer processing of light emitting structures (130) like microlens arrays. The invention further describes a method of manufacturing such a light emitting device (100).