Light Emitting Element Protrusion Shape Control
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Solution Overview
Problem
The existing methods for manufacturing light emitting elements with surface emitting laser elements face challenges in achieving a desired cross-sectional shape for the first light reflecting layer due to issues with resist material wettability, surface tension, and gravity, leading to suboptimal laser light confinement and diffraction losses.
Innovation Solution
A method involving a stacked structure with a protrusion on the base surface, where a second light reflecting layer is formed on the second surface of the second compound semiconductor layer, and a first light reflecting layer is formed on the protrusion, using sacrificial layers to create a smooth curved cross-sectional shape, which enhances light confinement and reduces diffraction losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resist material layer is formed on the n-type compound semiconductor layer and subjected to heating treatment to create a convex portion, then the first light reflecting layer can function as a concave mirror to suppress diffraction loss, but the resist material layer does not achieve the desired cross-sectional shape due to wettability, surface tension, and gravity issues
Solution Approach 1:
The patent introduces a mold layer as an intermediary substance between the resist material layer and the n-type compound semiconductor layer. This mold layer has specific wettability characteristics that enable the resist material to form the desired convex portion shape with smooth curved cross-section. The mold layer acts as a mediator that controls the interface behavior between the resist and substrate, resolving the shape formation issues caused by direct contact between resist and semiconductor layer.
Solution Approach 2:
The patent changes the wettability parameters of the interface by introducing the mold layer with controlled surface energy characteristics. By adjusting the wettability parameters through the mold layer, the system achieves proper adhesion and shape formation of the resist material layer, transforming the cross-sectional shape from problematic (affected by surface tension and gravity) to desired (smooth convex curve).
2Ease of manufacture
If the first light reflecting layer is formed with a non-desired cross-sectional shape, then manufacturing is simpler, but diffraction loss increases and light confinement is reduced
Solution Approach 1:
The mold layer serves as an intermediary that enables precise control of the first light reflecting layer's cross-sectional shape during formation. By providing a controlled interface with specific wettability, the mold layer allows the resist material to self-organize into the optimal convex shape, ensuring that the subsequent light reflecting layer inherits this precise geometry, thereby reducing diffraction loss while maintaining manufacturing feasibility.
Solution Approach 2:
The patent performs preliminary action by forming the mold layer and using it to shape the resist material layer before forming the first light reflecting layer. This preliminary shaping action ensures that when the light reflecting layer is deposited, it automatically acquires the desired convex cross-sectional shape, preventing diffraction loss issues that would arise from improper shape formation.
3Reliability
If heating treatment is applied to the resist material layer to create an arc shape, then light confinement is improved, but the cross-sectional shape does not match the desired profile due to material properties and external forces
Solution Approach 1:
The mold layer acts as an intermediary that controls the shape formation during heating treatment. Instead of relying solely on the resist material's own properties (which are affected by surface tension and gravity), the mold layer provides a template that guides the resist material into the desired convex shape with smooth curves, achieving both proper light confinement and accurate geometric profile.
Solution Approach 2:
The patent changes the interfacial parameters between the resist material and substrate by introducing the mold layer. This modification of wettability parameters allows the resist material to properly adhere and shape during heating treatment, transforming the cross-sectional profile from one affected by uncontrolled surface tension and gravity to one that achieves the desired smooth convex curve for optimal light confinement.
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 method enables the formation of light emitting elements with improved light confinement, reduced diffraction losses, and increased light emission efficiency by achieving a desired cross-sectional shape for the first light reflecting layer, leading to enhanced laser oscillation and array density.
Implementation Method 1
laser oscillation generally occurs by causing laser light to resonate between two light reflecting layers (distributed Bragg reflector (DBR) layers)
Implementation Method 2
a structure in which the first light reflecting layer also functions as a concave mirror is well known
Implementation Method 3
In order to suppress a diffraction loss due to light field confinement in a lateral direction
Data Source
AI summary
A method for manufacturing a light emitting element according to the present disclosure is a method for manufacturing a light emitting element which includes a stacked structure 20 in which a first compound semiconductor layer 21, an active layer 23, and a second compound semiconductor layer 22 are stacked, a first light reflecting layer 41, and a second light reflecting layer 42 having a flat shape, and in which a base surface 90 positioned on a first surface side of the first compound semiconductor layer 21 has a protrusion 91 protruding in a direction away from the active layer 23, and a cross-sectional shape of the protrusion 91 includes a smooth curve, the method including: forming a first sacrificial layer 81 on the base surface on which the protrusion 91 is to be formed; forming a second sacrificial layer 82 on the entire surface; and performing etching back from the base surface 91 inward by using the second sacrificial layer 82 and the first sacrificial layer 81 as etching masks.