Peripheral Wafer Support Structure for Damage-Free Thinning
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Solution Overview
Problem
The challenge in manufacturing multi-dimensional integrated chips is the damage to semiconductor wafers during thinning and trimming processes due to lack of structural support, leading to reduced yield and device density.
Innovation Solution
Incorporating a support structure between the peripheral regions of bonded wafers to provide structural integrity, mitigating damage during fabrication processes and allowing for the omission of trimming, thereby enhancing reliability and increasing lateral area for semiconductor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If wafers are thinned during fabrication, then device density is improved, but wafer damage occurs due to lack of structural support
Solution Approach 1:
A support structure is introduced as an intermediary element between the bonded wafer peripheral regions. This support structure provides mechanical reinforcement during the thinning process, preventing wafer damage while allowing high device density in the central region. The support structure acts as a mediator that enables the thinning operation without compromising wafer integrity.
Solution Approach 2:
The wafer structure is segmented into a central region for high-density devices and peripheral regions for structural support. The support structure is specifically positioned in the peripheral regions, separating the functional device area from the structural reinforcement area. This segmentation allows the central region to be thinned for high device density while the peripheral support structure maintains overall wafer integrity.
2Reliability
If trimming process is performed to remove damaged edges, then wafer quality is improved, but fabrication time and cost increase
Solution Approach 1:
The support structure is formed in advance during the fabrication process, before the thinning operation. This preliminary action of adding structural support prevents edge damage from occurring in the first place, eliminating the need for subsequent trimming operations. By performing the protective action beforehand, fabrication time is reduced while maintaining wafer quality.
Solution Approach 2:
The support structure, which adds material to the wafer periphery, actually prevents the harmful effect of edge damage during thinning. By converting the potential harm of unsupported edges into a beneficial reinforced structure, the need for corrective trimming is eliminated, reducing both time and cost.
3Strength
If support structure is added between wafers, then structural integrity is improved, but device area is reduced
Solution Approach 1:
The support structure is localized to the peripheral regions of the bonded wafers, while the central region maintains high device density. By applying structural reinforcement only where needed at the edges rather than uniformly across the entire wafer, the device area in the central region is maximized while still providing the necessary structural integrity for thinning operations.
Data Source
AI summary
Various embodiments of the present disclosure are directed towards a method for forming a semiconductor structure. The method includes bonding a first semiconductor wafer to a second semiconductor wafer. A bond interface is disposed between the first and second semiconductor wafers. The first semiconductor wafer has a peripheral region laterally surrounding a central region. A support structure is formed between a first outer edge of the first semiconductor wafer and a second outer edge of the second semiconductor wafer. The support structure is disposed within the peripheral region. A thinning process is performed on the second semiconductor wafer.