Die Alignment Fiducials for Infrared Bonding Verification
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Solution Overview
Problem
In IC packaging, direct bonding methods require higher placement accuracy due to tighter interconnect pitches, making it challenging to accurately align electrically conductive interconnects, and traditional alignment methods are hindered by metallization layers that block infrared signals used for fiducial detection.
Innovation Solution
The use of lower alignment fiducials that can be imaged via infrared signals from the backside, allowing for precise verification of bonding alignment by capturing fiducials through substrate material layers, and the creation of regions within metallization levels that are free of metallization features to enhance visibility for fiducial detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If direct bonding methods are used to achieve tighter interconnect pitches, then computational performance and integration density are improved, but placement accuracy requirements increase making alignment more difficult
Solution Approach 1:
Alignment fiducials are established on the die before bonding occurs, allowing alignment measurements to be performed on the die itself rather than requiring post-bonding measurements through obstructive metallization layers. This preliminary positioning enables accurate alignment verification without the bonding process interfering with detection.
Solution Approach 2:
The patent transitions from attempting to detect fiducials through the bonding interface (z-dimension obstruction) to detecting fiducials on the die surface or through transparent substrate material layers. This dimensional shift in detection approach bypasses the metallization layer obstruction problem and enables accurate alignment verification.
2Ease of operation
If traditional alignment methods using infrared signals are used, then alignment verification is simplified, but metallization layers block the infrared signals preventing accurate fiducial detection
Solution Approach 1:
The patent extracts the fiducial detection function from the bonding interface region where it is blocked by metallization layers. By placing fiducials on the die surface or within transparent substrate layers away from the bonding interface, the detection function is separated from the obstructive metallization structure, enabling clear infrared signal detection.
Solution Approach 2:
Transparent substrate material layers serve as intermediary detection regions that allow infrared signals to pass through while providing a plane for fiducial placement. These intermediary layers mediate between the fiducial marking function and the infrared detection function, enabling signal transmission without obstruction from metallization layers.
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 enables accurate measurement of placement accuracy and verification of bonding alignment, reducing errors and ensuring proper contact between interconnect features, even in complex composite IC structures.
Implementation Method 1
lower alignment fiducials that can be imaged via infrared signals from the backside, allowing for precise verification of bonding alignment by capturing fiducials through substrate material layers
Data Source
AI summary
An integrated circuit (IC) device comprises a host component and an IC die directly bonded to the host component. The IC die comprises a substrate material layer and a die metallization level between the substrate material layer and host component. The IC die includes an upper die alignment fiducial between the die metallization level and host component. The upper die alignment fiducial at least partially overlaps one or more metallization features within the die metallization level. In embodiments, at least two orthogonal edges of the upper die alignment fiducial do not overlap any of the metallization features within the die metallization level. In embodiments, the IC die includes a lower die alignment fiducial between the substrate material layer and the die metallization level. The lower die alignment fiducial may at least partially overlap one or more second metallization features within a second die metallization level of the IC die.