Wafer-to-Wafer Bonding for LED Light Extraction
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Solution Overview
Problem
Wafer-to-wafer bonding methods for LED manufacturing suffer from low light extraction efficiency, limiting the effectiveness of semiconductor LEDs in directing emitted light in a desired direction.
Innovation Solution
The method involves modifying the p-type layer of a semiconductor material to create alternating high and low resistivity areas, bonding a base wafer to the p-type layer using different metals or the same metal, and patterning trenches between light emitters to enhance light extraction, along with forming lenses on the semiconductor surface to increase light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wafer-to-wafer bonding is used to manufacture smaller LEDs, then LED size is reduced and manufacturing efficiency is improved, but light extraction efficiency deteriorates
Solution Approach 1:
The patent applies local quality by creating alternating high and low resistivity regions within the p-type layer, where low resistivity regions serve as light emitters and high resistivity regions act as isolation barriers. This localized differentiation enables improved light extraction at specific locations without compromising the overall bonding structure or manufacturing process efficiency.
Solution Approach 2:
The patent segments the p-type layer into alternating high and low resistivity areas, and further segments the LED structure by patterning trenches between adjacent light emitters. This segmentation isolates individual light emitters while maintaining the wafer-level bonding process, thereby improving light extraction efficiency without sacrificing manufacturing productivity.
2Ease of manufacture
If conventional wafer-to-wafer bonding is used, then manufacturing process is simple, but light extraction efficiency is low
Solution Approach 1:
The patent performs preliminary actions by modifying the p-type layer to create alternating high and low resistivity regions before the wafer bonding process. This pre-modification enables subsequent light extraction enhancement without complicating the bonding process itself, as the resistivity pattern is established in advance and remains compatible with standard wafer-to-wafer bonding procedures.
Solution Approach 2:
The patent changes the electrical resistivity parameter of the p-type layer by creating alternating high and low resistivity regions. This parameter modification enables improved light extraction efficiency while maintaining compatibility with conventional bonding processes, as the resistivity changes are achieved through material processing rather than fundamental process changes.
3Loss of energy
If trenches are patterned between light emitters, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
The patent uses segmentation to pattern trenches between adjacent light emitters, which physically separates the emission regions and improves light extraction efficiency by reducing optical interference between neighboring LEDs. The segmentation is achieved through standard lithography and etching processes, adding minimal structural complexity while delivering significant performance improvement.
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 improves light extraction efficiency and reduces the emission cone of LEDs, allowing for more directed and efficient light emission, enabling the production of smaller LEDs with enhanced performance.
Implementation Method 1
modifying a p-type layer of a semiconductor material to form a plurality of alternating high resistivity areas and low resistivity areas
Implementation Method 2
The base wafer may be bonded to the first surface of the p-type layer via metal-to-metal bonding
Implementation Method 3
forming lenses on the semiconductor surface to increase light extraction efficiency
Data Source
AI summary
Disclosed herein are techniques for wafer-to-wafer bonding for manufacturing light emitting diodes (LEDs). In some embodiments, a method of manufacturing LEDs includes modifying a p-type layer of a semiconductor material to form a plurality of alternating high resistivity areas and low resistivity areas, wherein the low resistivity areas correspond to light emitters; bonding a base wafer to a first surface of the p-type layer; removing a substrate from a second surface of the semiconductor material, wherein the second surface of the semiconductor material is opposite to the first surface of the p-type layer; and patterning a trench between each adjacent pair of the light emitters.