GaN VCSEL Substrate Removal Using Sacrificial Layer Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in manufacturing Vertical Cavity Surface Emitting Lasers (VCSELs) in the GaN material system lies in efficiently removing the GaN substrate while maintaining the integrity of the semiconductor device, as existing methods are inefficient and resource-intensive.
Innovation Solution
A method involving epitaxial growth of a sacrificial layer over a GaN substrate, forming fluid channels or trenches, and using an etchant to remove the substrate, followed by the formation of dielectric layers to create resonator mirrors, allowing for the recycling of the GaN substrate and precise control of the semiconductor layer stack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional substrate removal methods are used, then the GaN substrate can be removed, but the process is inefficient and resource-intensive
Solution Approach 1:
The patent introduces fluid channels that segment the etchant delivery process into multiple localized pathways, allowing parallel etching of multiple substrate regions simultaneously. This segmentation enables the etchant to reach the sacrificial layer at multiple points, dramatically improving substrate removal efficiency while reducing overall process time and resource consumption.
Solution Approach 2:
The patent transitions from conventional planar substrate removal to a three-dimensional approach by forming vertical fluid channels through the semiconductor layer stack. These channels extend in the vertical dimension, allowing etchant to be delivered directly to the sacrificial layer beneath the semiconductor structure, enabling efficient substrate removal without compromising device integrity.
2Productivity
If fluid channels are formed through the semiconductor layer stack, then substrate removal efficiency improves, but device complexity increases
Solution Approach 1:
The patent performs preliminary actions by forming the fluid channels and sacrificial layer structure before final device assembly. The sacrificial layer is epitaxially grown in advance, and fluid channels are formed through the layer stack prior to substrate removal. This preliminary structuring simplifies the subsequent substrate removal process and enables efficient manufacturing while managing complexity through staged fabrication.
Solution Approach 2:
The patent introduces a sacrificial layer as an intermediary element between the GaN substrate and the semiconductor layer stack. This sacrificial layer serves as a temporary structure that facilitates fluid channel formation and enables controlled substrate removal. The intermediary sacrificial layer simplifies the overall process by providing a defined etching target and protection mechanism for the semiconductor structures.
3Ease of repair
If the GaN substrate is removed, then resource recycling is enabled, but the risk of damaging the semiconductor device increases
Solution Approach 1:
The patent provides beforehand cushioning by forming a passivation layer on the semiconductor structures before substrate removal. This passivation layer acts as a protective cushion that prevents damage to the semiconductor devices during the substrate removal process. The sacrificial layer also serves as a cushioning element that can be selectively removed without affecting the semiconductor structures, enabling safe substrate recycling.
Solution Approach 2:
The patent converts the potential harm of substrate removal into benefit by using the sacrificial layer as a controlled removal mechanism. The sacrificial layer is specifically designed to be removable while protecting the semiconductor structures. By converting the GaN substrate into a recyclable resource through controlled removal, the process transforms a potentially damaging operation into a beneficial resource recovery process.
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 efficient manufacturing of GaN-based VCSELs with high reflectivity resonator mirrors, reduces resource consumption by recycling the GaN substrate, and improves the semiconductor device's efficiency by allowing precise control of the optical resonator length.
Implementation Method 1
etching the sacrificial layer, comprising introducing an etchant into the fluid channel, to remove the GaN substrate
Implementation Method 2
epitaxially growing a sacrificial layer over a GaN substrate, epitaxially growing a first semiconductor layer over the sacrificial layer
Data Source
AI summary
A method of manufacturing a semiconductor device includes epitaxially growing a sacrificial layer over a GaN substrate, epitaxially growing a first semiconductor layer over the sacrificial layer and forming a first layer over a first main surface of the first semiconductor layer, the first main surface being on a side of the first semiconductor layer remote from the GaN substrate. The method further includes forming a fluid channel or trench extending through the first layer and the first semiconductor layer to the sacrificial layer, etching the sacrificial layer, including introducing an etchant into the fluid channel or trench, to remove the GaN substrate and forming a second dielectric layer over a second main surface of the first semiconductor layer.