VCSEL Oxide Aperture Uniformity Through Spatial Mask Layout
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Solution Overview
Problem
Variations in oxidation rates across a wafer lead to non-uniform oxide aperture sizes in VCSELs, resulting in performance issues and yield loss.
Innovation Solution
Using trench or mesa etch photomasks during wafer fabrication to vary the trench-to-trench distance or mesa size based on predicted oxidation rate variations, thereby compensating for location-specific differences in oxidation rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a constant trench-to-trench distance is used across the wafer, then the manufacturing process is simple, but the oxide aperture sizes become non-uniform due to oxidation rate variations
Solution Approach 1:
The patent applies local quality by varying the trench-to-trench distance in different regions of the mask to compensate for spatial variations in oxidation rates across the wafer. Specifically, the mask includes a first region with a first trench-to-trench distance and a second region with a second trench-to-trench distance, where the distances are differently configured to achieve uniform oxide aperture sizes despite non-uniform oxidation conditions across the wafer surface.
2Manufacturing precision
If extensive process calibrations are performed to achieve uniform oxidation, then oxidation uniformity improves, but the manufacturing time and complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-configuring the mask with spatially varying trench-to-trench distances that anticipate and compensate for oxidation rate variations across the wafer. This preliminary design of the mask eliminates the need for extensive process calibrations during manufacturing, as the compensation for oxidation non-uniformity is built into the mask structure before the oxidation process begins.
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 improves the uniformity of oxide aperture sizes across the wafer, reducing emitter performance variations and yield loss, while also eliminating the need for extensive process calibrations.
Implementation Method 1
a respective trench-to-trench distance associated with the plurality of VCSELs varies across the wafer based on a predicted variation of an oxidation rate of an oxidation layer across the wafer
Data Source
AI summary
A wafer may comprise a substrate layer and a plurality of vertical cavity surface emitting lasers (VCSELs) formed on or within the substrate layer. A respective trench-to-trench distance associated with the plurality of VCSELs may vary across the wafer based on a predicted variation of an oxidation rate of an oxidation layer across the wafer.