VCSEL Epi Layer Transfer to Metal Host Substrate
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Solution Overview
Problem
Current semiconductor lasers face challenges in achieving high power output while maintaining tight-pitch packing and resolving thermal crosstalk issues, which limits their application in high-resolution printing and other demanding applications.
Innovation Solution
The development of independently-addressable VCSEL architectures with improved laser array designs, chip tiling, and advanced mounting and cooling architectures, including direct die attachment to 3D submounts with integrated cooling channels, allows for high power output and efficient thermal management, enabling tight-pitch packing and high-resolution capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If VCSEL aperture size is increased to achieve high power output, then light output power is improved, but device size increases and tight-pitch packing becomes difficult
Solution Approach 1:
The patent divides the VCSEL structure into separate functional layers: the active laser epi layer is transferred onto an independent metal host substrate. This segmentation allows the laser aperture to be optimized for high power output while the overall device footprint is controlled by the host substrate dimensions, enabling tight-pitch packing despite large aperture requirements for 50 mW output.
Solution Approach 2:
The patent moves the laser active layer from the original semiconductor substrate plane to a separate metal host substrate plane through transfer processing. This dimensional reorganization allows independent optimization of aperture size for power output while controlling device density through substrate arrangement, resolving the contradiction between large aperture and small pitch.
2Manufacturing precision
If VCSELs are packed tightly to achieve high resolution arrays, then array density is improved, but thermal crosstalk increases
Solution Approach 1:
The patent introduces a metal host substrate as an intermediary thermal management layer between the laser epi layer and the heat sink. This metal substrate acts as a thermal conductor that distributes heat from densely packed lasers, preventing thermal crosstalk while allowing high array density for 1200 dpi resolution.
Solution Approach 2:
The patent extracts the thermal management function from the original semiconductor substrate by transferring the laser layer to a dedicated metal host substrate. This separation allows the metal substrate to be optimized specifically for thermal conduction, extracting heat efficiently from densely packed lasers and eliminating thermal crosstalk issues.
3Temperature
If substrate is thinned to enable heat extraction, then thermal management is improved, but substrate structural integrity deteriorates
Solution Approach 1:
The patent extracts the laser active layer from the thinned substrate using a transfer process involving mounting wax and solvent removal. This allows the substrate to be thinned for heat extraction while the laser layer is rescued and transferred to a new metal host substrate that provides the required structural integrity, decoupling thermal management from structural support functions.
Solution Approach 2:
The patent performs preliminary substrate thinning and polishing before transfer, removing only the necessary minimum thickness for heat extraction while preserving enough material integrity to allow subsequent handling and transfer operations. The actual laser layer is then transferred to the metal host where final structural support is established.
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
The solution enables VCSEL arrays to achieve high power output with resolutions greater than 300 dpi, effectively addressing thermal management issues and enabling applications such as high-speed printing, facial recognition, and lidar systems.
Implementation Method 1
An epi layer of a semiconductor chip (e.g., semiconductor laser array) including a substrate can be mounted onto a planar handle wafer with mounting wax
Implementation Method 2
The planar handle wafer can then be removed from the epi layer by dissolving the mounting wax with a solvent
Implementation Method 3
The planar handle wafer can be placed into a thin film evaporator wherein an n-type ohmic contact metal is blanket deposited on the polished backside of the substrate as a metal film
Implementation Method 4
The semiconductor chip can be annealed to complete an n-side ohmic contact interface
Data Source
AI summary
A method of transferring a semiconductor epi layer onto a metal host substrate is described. An epi layer of a semiconductor chip (e.g., semiconductor laser array) including a substrate can be mounted onto a planar handle wafer with an adhesive, wherein a backside of the substrate faces upward and away from the epi layer and the planar handle wafer. The backside of the substrate can be treated to substantially remove the substrate, while leaving the epi layer undamaged (e.g., by polishing to where no more than 20 micrometers of the substrate remains). Metal can be formed on the treated backside resulting in a metalized backside. The planar handle wafer can then be removed from the epi layer by dissolving the adhesive with a solvent, wherein a modified semiconductor chip remains. The semiconductor chip can be annealed to form a backside ohmic contact interface. The semiconductor chip can then be attached to a mechanical block by the ohmic contact interface.