VCSEL Substrate Orientation Mark for Precise Layer Alignment
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Solution Overview
Problem
The production of vertical-cavity surface-emitting lasers (VCSELs) is complex and requires precise alignment of layers, which is challenging due to inaccuracies in existing marking and alignment techniques, leading to insufficient resolution and alignment accuracy.
Innovation Solution
A vertical-cavity surface-emitting laser design with an orientation mark on the outer face of the first semiconductor substrate, allowing precise alignment of layers during production without altering the active region, using wafer bonding and epitaxial growth to connect reflectors and active regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If markings are applied in the tunnel junction layer and one Bragg mirror is removed for visibility, then the marking remains visible in the assembled VCSEL, but an additional work step is required
Solution Approach 1:
The marking is extracted from the tunnel junction layer and placed on the outer face of the first semiconductor substrate, separating the marking function from the active region structure. This eliminates the need to remove Bragg mirror material for visibility while maintaining marking visibility for alignment purposes.
2Ease of manufacture
If infrared radiation is used to detect the marking through the component, then no material needs to be removed, but the detection accuracy is limited due to wavelength
Solution Approach 1:
The marking is moved from an internal layer (tunnel junction) to the outer surface of the substrate, changing the detection dimension from transmission through the component to direct observation of the surface feature. This enables high-precision alignment marking detection without material removal.
3Device complexity
If markings are transferred from one layer to another during production, then additional material removal is omitted, but alignment inaccuracies accumulate with each transfer
Solution Approach 1:
The alignment marking is created in advance on the outer face of the first semiconductor substrate before wafer bonding and assembly. This preliminary placement eliminates the need for multiple marking transfers during production, preventing accumulation of alignment inaccuracies.
4Adaptability or versatility
If the active region is altered to include the marking, then the marking can be integrated into the structure, but the active region design becomes more complex
Solution Approach 1:
The marking function is extracted from the active region and placed on the substrate outer face, allowing the active region to maintain its simple, optimized design for light generation while the marking serves its alignment function independently on the substrate 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
Enables precise alignment of VCSEL components, facilitating a simpler and more flexible production process with higher light output and reduced inaccuracies, avoiding alterations to the active region.
Implementation Method 1
an active region arranged between the Bragg reflectors having one or a plurality of quantum wells for generating the laser light
Implementation Method 2
two distributed Bragg reflectors (DBR) arranged parallel to the wafer surface... Bragg reflectors typically comprise layers with alternating high and low refractive indices
Implementation Method 3
the Bragg reflectors and the active region arranged between them can be produced separately and then joined together by wafer bonding (fusion bonding)
Data Source
AI summary
A vertical-cavity surface-emitting laser includes a first reflector connected to a first semiconductor substrate, a second reflector, and an active region including a quantum well structure for emitting light. The active region is located in series between the first reflector and the second reflector. The first reflector is located in series between the first semiconductor substrate and the active region. A surface of an outer face of the first semiconductor substrate that faces away from the first reflector has an orientation mark that is configured so as to define a position of the vertical-cavity surface-emitting laser in a plane in parallel with the outer face of the first semiconductor substrate.