Pixel Diode Trench Isolation With Lateral Spacer Contacts
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Solution Overview
Problem
Existing methods for producing diodes, such as LEDs and photodiodes, face challenges in achieving good optical isolation between pixels while maintaining effective electrical response, often requiring complex alignment and etching processes that can degrade electrical properties or compromise optical isolation.
Innovation Solution
A method involving a stack of semiconductor layers with a dielectric spacer on the lateral flanks of the p-n junction, allowing for autoaligned production of diodes with effective optical isolation and improved electrical response, where the dielectric spacer covers the lateral flanks to provide electrical insulation and reduce the overall size of the diode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If trenches are etched as far as the substrate to achieve optical isolation, then optical isolation between pixels is improved, but electrical response deteriorates due to loss of crystalline planes parallel to growth surface
Solution Approach 1:
The patent transitions from a single-level contact approach to a multi-level contact structure. Electrical contacts are established at two different vertical levels: first contacts are made on the substrate level through partially etched trenches, while second contacts are made on the lateral flanks of the semiconductor structure. This dimensional transition allows optical isolation trenches to extend to the substrate without compromising electrical response, as the electrical contact path is relocated to preserved crystalline planes at a different vertical position.
Solution Approach 2:
The patent introduces an intermediate insulating layer that fills the optical isolation trenches between the substrate and the lateral contact surfaces. This intermediary material serves dual functions: it maintains the optical isolation by filling the trench space, and it enables electrical contact on the lateral flanks by providing an insulating barrier that prevents short circuits while allowing contact with the crystalline planes parallel to the growth surface.
2Ease of manufacture
If standard microelectronic methods are used for diode production, then manufacturing process is simplified, but optical isolation between pixels deteriorates due to crosstalk
Solution Approach 1:
The patent segments the optical isolation function from the electrical contact function. Optical isolation is achieved through deep trenches extending to the substrate, while electrical contacts are segmented into two parts: first contacts on the substrate level and second contacts on the lateral flanks. This segmentation allows each function to be optimized independently, achieving both complete optical isolation and effective electrical response.
Solution Approach 2:
The patent moves electrical contacts from a planar configuration to a three-dimensional configuration utilizing lateral surfaces. By establishing contacts on the lateral flanks of the semiconductor structure rather than only on the top surface, the invention achieves effective electrical response while maintaining complete optical isolation through vertical trenches, thereby resolving the crosstalk issue without compromising manufacturing simplicity.
3Area of stationary object
If pixel size is reduced for high-resolution devices, then integration density is improved, but optical isolation becomes more difficult to achieve
Solution Approach 1:
The patent addresses the optical isolation challenge in miniaturized devices by transitioning from surface-level isolation to deep vertical isolation. Trenches extend all the way to the substrate, creating complete optical barriers that are effective even when pixel dimensions are reduced. This vertical approach to isolation maintains effectiveness regardless of horizontal pixel size reduction.
Solution Approach 2:
The patent segments the isolation function into vertical trenches that extend through the entire device thickness to the substrate. This segmentation creates discrete optical barriers between adjacent pixels, allowing each pixel to be completely isolated optically even when pixels are densely packed at reduced sizes, thereby maintaining optical isolation effectiveness in high-resolution applications.
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 enhances optical isolation, improves electrical response, reduces manufacturing costs and energy consumption, and enables the production of high-resolution devices with smaller pixel sizes, increasing energy efficiency and integration density.
Implementation Method 1
a dielectric spacer covering side walls of said remaining portions
Implementation Method 2
filled with a material forming a reflective metallic electrode, which makes it possible to properly optically isolate the pixels from each other since the light emitted by a pixel is then directly extracted under this pixel
Data Source
AI summary
A method for producing a photoemitting or photoreceiving diode includes producing, on a first substrate, first and second semiconductor layers with opposite dopings, and a third intrinsic semiconductor layer; etching trenches surrounding remaining portions of the second and third layers and of a first part of the first layer; and producing, in the trenches, a dielectric spacer covering side walls of said remaining portions. The method also includes etching to extend the trenches as far as the first substrate; laterally etching a part of the dielectric spacer, exposing contact surfaces of the second part of the first layer; and producing, in the trenches, a first electrode in contact with the contact surfaces of the second part of the first layer and with lateral flanks of the second part of the first layer.