Stacked LED Hybrid Bonding Alignment Precision
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional die-to-wafer bonding processes for LED devices face challenges with die-shift issues, particularly for smaller LED devices, leading to reduced reliability and performance due to lateral position shifts exceeding +/-38 microns, which are exacerbated by the decreasing size of LED dies.
Innovation Solution
A semiconductor structure with a stacked light-emitting diode configuration, where each LED unit is bonded to a CMOS chip using a hybrid bonding process that includes metal-to-metal and dielectric-to-dielectric bonds, with a transparent filling to prevent light scattering and cross-talk, and a redistribution layer providing electrical channels and mechanical support, ensuring precise alignment and stability of LED units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional die-to-wafer bonding processes are used with flux reflow oven or eutectic die-to-wafer bonders, then the bonding process can be completed, but die-shift exceeds +/-38 microns leading to reduced reliability and performance
Solution Approach 1:
The patent applies preliminary action by performing alignment marks formation and registration hole creation before the actual bonding process. The alignment marks are etched and filled with reflective material in advance, allowing for precise measurement and correction of die positions before final bonding occurs, thereby preventing excessive die-shift
Solution Approach 2:
The patent replaces conventional mechanical bonding systems (flux reflow oven, eutectic bonders) with a hybrid bonding approach that incorporates alignment marks, registration holes, and controlled bonding parameters. This substitution enables precise positioning and reduces die-shift by using optical/measurement-based alignment rather than purely mechanical placement
2Area of moving object
If LED die size continues to decrease to achieve smaller device size, then device miniaturization is achieved, but die-shift becomes a bigger issue causing greater reduction in reliability and performance
Solution Approach 1:
The patent applies segmentation by dividing the bonding process into distinct stages: alignment mark formation, registration hole creation, and controlled bonding. This segmentation allows for precise positioning of each component (alignment marks, registration holes) independently, enabling accurate placement of smaller LED dies without excessive die-shift
Solution Approach 2:
The patent introduces alignment marks and registration holes as intermediary features that facilitate precise positioning. These intermediaries serve as reference points that enable accurate alignment between LED dies and bonding pads, even when die sizes are reduced, thereby maintaining positioning precision
Data Source
AI summary
A semiconductor structure is disclosed. The semiconductor structure includes: a first light-emitting diode (LED) layer including a first LED of a first color type, the first LED layer having a first side and a second side opposite to the first side; a second LED layer over the first LED layer, the second LED layer including a second LED of a second color type, and the second LED layer having a first side and a second side opposite to the first side; and a third LED layer over the second LED layer, the third LED layer including a third LED of a third color type, and the third LED layer having a first side and a second side opposite to the first side; wherein the first color type, the second color type, and the third color type are different from each other.