Semiconductor Light Source Alignment Marks
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Solution Overview
Problem
Existing methods for manufacturing semiconductor light sources, such as BH laser arrays and SOA arrays, face challenges in precise XYZ alignment due to imprecise vertical contact areas and alignment marks, which are dependent on dry etching and lithography precision, limiting their effectiveness in flip-chip mounting.
Innovation Solution
A method involving patterning a layer sequence to form a light-emitting stripe and a parallel alignment stripe, applying a cover layer, and selectively exposing regions as vertical and horizontal alignment marks, allowing for precise XYZ alignment independent of etching and lithography precision, with vertical alignment marks positioned away from light-entrance and exit edges to prevent facet coating interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If vertical contact areas are manufactured by means of dry etching, then contact areas can be formed for flip-chip mounting, but the precision of vertical Z alignment is insufficient due to imprecise etching depth
Solution Approach 1:
The patent introduces an intermediary measurement mark structure that mediates between the dry etching process and the final alignment requirement. This measurement mark serves as a reference that decouples the alignment precision from the etching depth precision, allowing accurate Z-alignment to be achieved through optical measurement of the measurement mark rather than direct reliance on etching depth control.
Solution Approach 2:
The patent replaces the mechanical/physical dry etching depth control system with an optical measurement system. Instead of relying on mechanical etching depth control to achieve vertical alignment, the invention uses optical measurement of the measurement mark to determine and control the vertical position, substituting a less precise mechanical control system with a more precise optical measurement system.
2Ease of operation
If alignment marks are applied to laser components using lithography, then horizontal alignment can be achieved, but the position precision is insufficient due to limited lithography precision
Solution Approach 1:
The patent applies preliminary action by forming the measurement mark structure during the laser component manufacturing process itself, rather than as a separate post-processing step. The measurement mark is integrated into the component structure through epitaxial growth, ensuring its position is inherently tied to the component geometry from the outset, which prevents cumulative positioning errors.
Solution Approach 2:
The patent changes the fundamental parameter of how the alignment mark is created - from lithographic patterning (which has resolution limits) to epitaxial growth (which can achieve superior precision). By changing the creation method from a top-down lithographic approach to a bottom-up epitaxial approach, the precision of the alignment mark position is significantly improved.
3Ease of operation
If horizontal stops are used for alignment perpendicular to laser direction, then lateral positioning can be achieved, but they cannot be used with oblique laser stripes like SOA due to limited gap precision
Solution Approach 1:
The patent creates a universal measurement mark structure that can serve multiple alignment functions. The measurement mark can be used for both X-direction and Y-direction alignment, and can accommodate different laser stripe orientations including oblique stripes. This multi-functional measurement mark replaces the need for direction-specific alignment features like horizontal stops, providing a single solution that works for all laser configurations.
Data Source
AI summary
What is shown is a method for manufacturing a semiconductor light source. The semiconductor light source has a substrate and a layer sequence arranged above the substrate, the same having a light-emitting layer and an upper boundary layer arranged above the light-emitting layer. The layer sequence is patterned in order to form a light-emitting stripe for defining the semiconductor light source and an alignment stripe, extending in parallel thereto, as a horizontal alignment mark at the same time. Then, a cover layer is applied on the patterned layer sequence and a part of the cover layer is removed in order to expose the alignment stripe and expose a region of the layer sequence outside the light-emitting stripe and spaced apart from a light-entrance edge or a light-exit edge of the light-emitting stripe as a vertical alignment mark.