Dielectric Mirror Light Extraction in Semiconductor Chips
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Solution Overview
Problem
Current light emitting semiconductor devices face challenges in maximizing light output and mechanical strength while maintaining electrical isolation and avoiding aging issues with metallic mirrors, particularly in designs that require efficient light coupling and protection from electrostatic discharge.
Innovation Solution
A light emitting semiconductor device is developed with a molded carrier body that encloses the semiconductor chip, featuring a dielectric mirror on its top face for enhanced light reflection and an embedded electrical semiconductor component for ESD protection, along with a wavelength conversion element for mixed-color light emission, and an electrical connecting element for conductive contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a metallic mirror is used on the carrier body top face, then light reflection efficiency is improved, but aging issues and reliability deteriorate
Solution Approach 1:
The patent changes the material parameter of the mirror from metallic to dielectric, specifically using a high-refractive-index dielectric material with refractive index n≥2.0. This parameter change enables the dielectric mirror to achieve high light reflection efficiency (comparable to or exceeding metallic mirrors) while eliminating the aging and reliability issues associated with metallic mirrors, as dielectric materials are more chemically stable and resistant to degradation.
Solution Approach 2:
The patent employs a composite structure for the dielectric mirror, using a dielectric material that combines high refractive index properties with protective characteristics. The mirror may consist of multiple dielectric layers with different refractive indices, creating a composite optical structure that optimizes both reflection efficiency and long-term stability, replacing the single-material metallic mirror approach.
2Illumination intensity
If the carrier body top face is left exposed, then light coupling efficiency is improved, but mechanical strength and protection deteriorate
Solution Approach 1:
The patent applies the molded body selectively to specific regions of the carrier body, covering the side faces and peripheral areas while leaving the central top face exposed. This local application approach provides mechanical strength and environmental protection where needed (edges and sides) while maintaining optimal light coupling efficiency at the center where light extraction is most critical. The molded body acts as a protective frame rather than a complete cover.
Solution Approach 2:
The patent segments the carrier body into different functional zones: the central top face region optimized for light coupling (exposed), the side face regions optimized for mechanical support and protection (covered with molded body), and the peripheral regions for structural integrity. This spatial segmentation allows each region to fulfill its specific function optimally without compromise.
3Reliability
If electrical isolation measures are added, then reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The dielectric material serving as the mirror material simultaneously provides multiple functions: (1) high light reflection efficiency due to its high refractive index, (2) electrical isolation between the carrier body and any adjacent conductive elements, and (3) protective insulation properties. This multi-functionality eliminates the need for separate passivation layers or electrical isolation structures, reducing device complexity and manufacturing steps while maintaining or improving reliability.
Solution Approach 2:
The patent merges the optical function (light reflection) and the electrical function (isolation and protection) into a single integrated component - the dielectric mirror layer. By combining these functions into one material layer rather than using separate metallic mirror and passivation layers, the device structure is simplified, manufacturing is streamlined, and reliability is enhanced through reduced interfaces and potential failure points.
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 increases light coupling efficiency, enhances mechanical strength, eliminates aging risks associated with metallic mirrors, and provides effective electrostatic discharge protection, while enabling cost benefits by reducing the need for passivation and using varnish-based dielectrics.
Implementation Method 1
a dielectric mirror (5), which is applied to the top face (30) of the carrier body (3)
Implementation Method 2
A light emitting semiconductor device is developed with a molded carrier body that encloses the semiconductor chip, featuring a dielectric mirror on its top face for enhanced light reflection and an embedded electrical semiconductor component for ESD protection, along with a wavelength conversion element for mixed-color light emission
Data Source
AI summary
A light emitting semiconductor device includes at least one light emitting semiconductor chip having a semiconductor layer sequence, a light outcoupling surface, a rear face on an opposite side of the semiconductor layer sequence from the light outcoupling surface, and side faces which connect the light outcoupling surface and the rear face. The light emitting semiconductor device further includes a carrier body, having a molded body which covers the side faces of the at least one light emitting semiconductor chip directly and in a positively-locking manner. The carrier body comprises, at the light outcoupling surface of the at least one light emitting semiconductor chip, a top face on which a dielectric mirror is disposed. At least part of the light outcoupling surface is uncovered by the dielectric mirror.