LED Device with Through-Substrate Contact Plug
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Solution Overview
Problem
Conventional LED devices fabricated on sapphire substrates typically use two contacts on the same side, limiting the number of devices that can be formed on a wafer and complicating packaging due to the need for two wire bonds.
Innovation Solution
A light-emitting device design featuring a contact plug extending through the substrate between opposing surfaces, allowing electrical contacts to be placed on opposing sides of the chip, with an ohmic contact layer and conductive contact plug materials that enhance electrical connectivity and light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If two contacts are placed on the same side of the chip, then the device structure is simpler, but the number of devices that can be formed on a wafer is limited and packaging complexity increases
Solution Approach 1:
The patent transitions from a planar contact arrangement (both contacts on the same side) to a three-dimensional arrangement (contacts on opposing sides of the substrate). This dimensional change allows electrical contacts to be positioned on the front and back surfaces of the chip, effectively utilizing the vertical dimension to increase device density on the wafer while maintaining structural simplicity.
2Device complexity
If two contacts are placed on the same side of the chip, then the device structure is simpler, but packaging complexity increases due to the need for two wire bonds
Solution Approach 1:
By positioning contacts on opposing sides of the substrate, the patent enables a more straightforward packaging configuration. The vertical separation of contacts eliminates the need for complex planar wire bonding arrangements, simplifying the packaging process while maintaining structural integrity.
3Productivity
If contacts are placed on opposing sides of the chip, then the number of devices per wafer increases, but the device structure becomes more complex
Solution Approach 1:
The patent divides the electrical connection function into two separate locations on the substrate - one contact on the front surface and another on the back surface. This segmentation of the contact function across different surfaces allows for increased device density while managing structural complexity through functional distribution.
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 design increases the number of devices that can be formed on a wafer and simplifies packaging by enabling electrical contacts on opposing sides, while improving light extraction and current spreading.
Implementation Method 1
a contact plug extending therethrough between first and second opposing surfaces... The contact plug couples the second electrical contact to the active region
Implementation Method 2
An ohmic contact layer may be disposed between the first surface and the active region... improve light extraction and current spreading
Data Source
AI summary
A light-emitting device comprises a substrate that has a contact plug extending therethrough between first and second opposing surfaces. An active region is on the first surface, a first electrical contact is on the active region, and a second electrical contact is adjacent to the second surface of the substrate. The contact plug couples the second electrical contact to the active region. Such a configuration may allow electrical contacts to be on opposing sides of a chip, which may increase the number of devices that may be formed on a wafer.