Semiconductor Chip Facet Etching for Smooth Perpendicular Laser Facets
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Solution Overview
Problem
Current methods for manufacturing light-emitting semiconductor chips, particularly edge-emitting lasers, face challenges in defining smooth and perpendicular facets due to serial and costly breaking processes, and etching processes that unevenly etch In-rich layers, leading to suboptimal surface profiles and performance issues in GaN material systems.
Innovation Solution
A method involving the growth of semiconductor layer sequences on substrates with recesses and pre-patterning trenches to control In content and etching rates, using a combination of wet and dry etching to form facets that are smooth and perpendicular, allowing for parallel processing and efficient production of light-emitting semiconductor chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a breaking process is used to define the facet, then the facet can be produced parallel to a crystal plane, but the process is serial and time-consuming, resulting in low productivity and high cost
Solution Approach 1:
The patent replaces the mechanical breaking process with a chemical etching process to define the facet. Instead of physically breaking the semiconductor crystal along a plane, the invention uses controlled chemical etching with specific solutions to remove material and form the desired facet geometry, enabling parallel processing of multiple chips simultaneously.
Solution Approach 2:
The patent changes the etching parameters by using a two-step etching process with different etching solutions. The first etching step uses a solution that etches In-rich layers at a controlled rate, and the second step uses a different solution to complete the facet formation. This parameter change allows uniform etching across the entire wafer surface while maintaining facet quality.
2Productivity
If an etching process is used to define the facet at wafer level, then parallel processing is enabled and productivity increases, but In-rich layers are etched faster than other layers, resulting in uneven surface profiles and under-etching
Solution Approach 1:
The patent addresses the non-uniform etching by implementing a two-step etching process with different etching solutions and parameters. The first etching step uses a solution with controlled etch rate for In-rich layers, and the second step uses a different solution to achieve the final facet geometry. This allows the entire wafer to be processed in parallel while maintaining uniform facet quality across all chips.
Solution Approach 2:
The patent performs preliminary etching of the In-rich layers before completing the facet formation. By using a first etching solution to partially remove material and then applying a second etching solution to finish the facet, the process compensates for the different etch rates of In-rich versus In-poor regions, ensuring uniform final results across the wafer.
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 the production of light-emitting semiconductor chips with smooth and perpendicular facets, improving the laser properties by reducing In content variations and enhancing etching uniformity, thus achieving better finishability and performance without compromising wavelength or performance.
Implementation Method 1
the semiconductor layer sequence is grown on a substrate by means of an epitaxy process, for example metal-organic vapor phase epitaxy (MOVPE) or molecular beam epitaxy (MBE)
Implementation Method 2
when etching with typically used solutions containing OH− ions, for example KOH, In-rich layers are often etched faster than layers with smaller or no In content
Implementation Method 3
using a combination of wet and dry etching to form facets that are smooth and perpendicular
Data Source
AI summary
In an embodiment a method for manufacturing a light-emitting semiconductor chip includes providing a substrate having a main surface with at least one recess, the main surface having a main extension plane along the longitudinal direction and along a transversal direction perpendicular to the longitudinal direction, wherein the substrate has pre-patterning trenches formed along the transversal direction between chip regions and extending along the longitudinal direction, growing the semiconductor layer sequence on the main surface with the at least one recess and forming at least one facet aligned along the transversal direction in the semiconductor layer sequence by an etching process, wherein the facet has a distance of less than or equal to 50 μm from the at least one recess in at least one direction parallel to the main extension plane of the main surface.