Seal Ring for 3D IC Wafer Bonding Delamination
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Solution Overview
Problem
The semiconductor industry faces challenges in further shrinking minimum feature size of integrated circuits due to process limitations, leading to difficulties in improving processing capabilities and reducing power consumption, which is addressed by vertically integrating two-dimensional ICs into three-dimensional ICs using wafer-to-wafer bonding technology.
Innovation Solution
The integration of 2D ICs into 3D ICs is achieved through wafer-to-wafer bonding, where a seal ring is formed to prevent delamination by creating a hybrid bond between the IC dies, using dielectric-to-dielectric and conductor-to-conductor interfaces, and extending from one semiconductor substrate to another to enclose the bond interface, thereby protecting the 3D IC from delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wafer-to-wafer bonding is used to vertically integrate 2D ICs into 3D ICs, then processing capabilities are improved and power consumption is reduced, but delamination may occur at the bond interface during die saw process
Solution Approach 1:
The bonding interface is segmented into multiple bonding regions (conductor-to-conductor bonding regions and dielectric-to-dielectric bonding regions) arranged in an interdigitated pattern. This segmentation allows different bonding mechanisms to work together, with conductor regions providing strong electrical and mechanical bonding while dielectric regions providing additional bonding area and stress distribution, preventing delamination during subsequent processing steps.
Solution Approach 2:
Different regions of the bonding interface are assigned different properties: conductor regions provide high-strength electrical bonding while dielectric regions provide mechanical support and stress distribution. The seal ring structure is also applied locally at periphery regions to provide additional mechanical reinforcement where delamination is most likely to occur during die saw processing.
2Productivity
If minimum feature size is shrunk to improve processing capabilities, then IC performance is enhanced, but process limitations make further shrinking difficult
Solution Approach 1:
The patent transitions from two-dimensional planar integration to three-dimensional vertical integration by stacking multiple IC layers. This dimensional change allows continued improvement of processing capabilities and power consumption without further shrinking the minimum feature size in the planar direction, overcoming the physical limitations of continued feature size scaling.
3Reliability
If seal ring is formed to prevent delamination, then bond interface integrity is maintained, but device complexity increases
Solution Approach 1:
The seal ring structure serves multiple functions: it provides mechanical reinforcement to prevent delamination during die saw processing, defines the boundary of the bonding region, and provides a path for stress distribution. By combining multiple functions into a single structure, the overall device complexity is minimized while achieving reliable delamination prevention.
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 effectively reduces the footprint and power consumption of ICs, enhances processing capabilities, and prevents delamination during the die saw process by maintaining the integrity of the hybrid bond interface within the seal ring, even when delamination occurs outside it.
Implementation Method 1
creating a hybrid bond between the IC dies, using dielectric-to-dielectric and conductor-to-conductor interfaces
Implementation Method 2
bonded to the first conductive structure... the second conductive structure is bonded to the first conductive structure
Data Source
AI summary
A device includes first and second dies and a seal ring. The first die includes a top dielectric layer. The second die is over the first die. The second die includes a bottom dielectric layer bonded to the top dielectric layer of the first die at an interface between the first die and the second die. The seal ring extends from the first die to the second die through the interface. A portion of the top dielectric layer of the first die and a portion of the bottom dielectric layer of the second die are separated by a gap outside the seal ring.