Integrally Formed Microlens Array for VCSEL Wafer Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The integration of pre-attached lenses with VCSELs and photodiodes during conventional IC fabrication is challenging, leading to low scalability and increased production costs due to the need for precise mechanical alignment after wafer dicing.
Innovation Solution
A method for fabricating optical element assemblies with integrally formed microlenses, where a microlens array is directly attached to the wafer surface overlying the optical transmission ports of laser diodes or photodiodes, allowing for precise alignment and eliminating the need for separate lens integration during device assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If lenses are integrated with VCSELs and photodiodes as separate components after wafer dicing, then precise mechanical alignment can be achieved, but production scalability is reduced and manufacturing costs increase
Solution Approach 1:
The patent merges the lens and optical element fabrication processes by integrating lens formation directly into the wafer-level fabrication sequence. The lens layer is deposited and patterned on the same wafer as the optical elements before dicing, eliminating the need for separate lens components and their subsequent mechanical alignment during assembly. This combining of processes maintains precision while enabling scalable production.
Solution Approach 2:
The lens is formed preliminary during the wafer fabrication process, before the wafer is diced into individual devices. By pre-forming the lens structure on the wafer in its initial state, the alignment between lens and optical element is established at the wafer level, allowing all subsequent processing and dicing to proceed without requiring precise mechanical alignment steps.
2Ease of operation
If lenses are attached as separate components after wafer dicing, then mechanical alignment can be performed, but the number of assembly steps increases
Solution Approach 1:
The patent combines multiple separate assembly operations into a single integrated wafer-level process. The lens deposition, patterning, and attachment to optical elements all occur during the wafer fabrication sequence rather than as separate post-dicing steps. This merging eliminates intermediate handling and alignment steps, reducing overall device complexity.
Solution Approach 2:
The fabrication process is segmented into distinct wafer-level steps (lens deposition, patterning, attachment) that are performed sequentially on the complete wafer before dicing. This segmentation allows each step to be optimized independently while maintaining the benefit of wafer-level processing, reducing the number of assembly steps compared to post-dicing integration.
3Ease of manufacture
If conventional IC fabrication procedures are used without integrated lenses, then manufacturing is simpler, but beam collimation quality is insufficient
Solution Approach 1:
The lens structure is formed preliminarily during the wafer fabrication process using standard semiconductor manufacturing techniques. By incorporating lens formation into the initial wafer processing sequence, the method maintains the simplicity of conventional IC fabrication while achieving the precision required for beam collimation, as the lens is precisely positioned relative to each optical element before dicing.
Solution Approach 2:
The patent introduces lens-specific parameters (curvature, focal length, material composition) into the conventional IC fabrication process by adding lens deposition and patterning steps. These parameter changes enable beam collimation functionality while maintaining compatibility with existing semiconductor manufacturing infrastructure, thus preserving fabrication simplicity while improving optical performance.
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 enables more accurate and cost-effective production of optical devices with improved beam collimation, reducing alignment steps and enhancing scalability in device assembly.
Implementation Method 1
A microlens array is attached to the wafer top surface, so that each microlens in the array overlies a corresponding optical element optical transmission port
Implementation Method 2
VCSELs make use Distributed Bragg Reflectors (DBRs). These are formed by laying down alternating layers of semiconductor or dielectric materials with a difference in refractive index
Implementation Method 3
Today, most VCSEL devices employ quantum wells within the cavity. By depositing a thin layer of semiconductor with a slightly smaller band gap, one cannot only define a region for recombination to occur, one can control the optical properties of the device
Implementation Method 4
When a photon of sufficient energy strikes the diode, it excites an electron, thereby creating a positively charged electron hole. This mechanism is also known as the photoelectric effect. If the absorption occurs in the junction's depletion region, or one diffusion length away from it, these carriers are swept from the junction by the built-in field of the depletion region
Data Source
AI summary
An optical element assembly with integrally formed microlens is presented. A wafer is provided with a plurality of adjacent IC optical elements, each optical element having an optical transmission port in a wafer top surface. A microlens array is attached to the wafer top surface, so that each microlens in the array overlies a corresponding optical element optical transmission port. Then, a wafer of optical elements with attached microlenses is formed, where each microlens has a first lens surface adhering directly to a corresponding optical transmission port. Subsequent to forming the wafer of optical elements with attached microlenses, the wafer is diced forming a plurality of optical element assemblies. Each optical element assembly includes an optical element integrally formed with an attached microlens.