Hybrid Bonding Pad Alignment for Differential Thickness Structures
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Solution Overview
Problem
In directly bonded semiconductor structures, achieving reliable electrical connections between finely pitched contact pads is challenging due to misalignment caused by differential expansion and warpage resulting from thickness differences between elements, leading to ineffective electrical connections.
Innovation Solution
The implementation of a lithographic magnification correction factor and differential expansion compensation structures, such as dielectric layers or hydrogen plasma treatment, to align contact pads and reduce warpage, ensuring proper electrical connectivity across the bonded structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If elements of differential thickness are directly bonded, then bonding reliability is improved, but misalignment and warpage occur due to differential expansion
Solution Approach 1:
The patent applies preliminary action by performing lithographic magnification correction during the patterning process before bonding. A correction factor is applied to the lithography step to pre-compensate for the differential expansion that will occur after bonding, ensuring contact pads are properly aligned despite thickness differences between elements.
Solution Approach 2:
The patent changes the lithographic magnification parameter to compensate for differential expansion. By adjusting the magnification correction factor based on the known thickness differential between elements, the contact pad dimensions are deliberately modified during patterning to account for post-bonding dimensional changes.
2Productivity
If contact pads are finely pitched, then device integration density is improved, but alignment tolerance becomes more critical and connections become unreliable
Solution Approach 1:
For finely pitched contact pads, the patent applies preliminary lithographic magnification correction to pre-establish proper alignment before bonding. This preliminary action ensures that even with tight pitch dimensions, the contact pads will align correctly after differential expansion occurs during bonding.
3Adaptability or versatility
If thickness differential between elements is large, then design flexibility is improved, but warpage and misalignment increase
Solution Approach 1:
The patent addresses warpage from large thickness differentials by changing the lithographic magnification parameter. The magnification correction factor is calculated based on the thickness differential, allowing the contact pad dimensions to be adjusted during patterning to compensate for the expected warpage and maintain proper alignment.
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
These measures effectively compensate for misalignments and warpage, ensuring that a high percentage of contact pads form reliable electrical connections, enhancing the yield and reliability of hybrid direct bonding applications.
Implementation Method 1
hydrogen plasma treatment
Data Source
AI summary
A method of direct hybrid bonding first and second semiconductor elements of differential thickness is disclosed. The method can include patterning a plurality of first contact features on the first semiconductor element. The method can include second a plurality of second contact features on the second semiconductor element corresponding to the first contact features for direct hybrid bonding. The method can include applying a lithographic magnification correction factor to one of the first patterning and second patterning without applying the lithographic magnification correction factor to the other of the first patterning and the second patterning. In various embodiments, a differential expansion compensation structure can be disposed on at least one of the first and the second semiconductor elements. The differential expansion compensation structure can be configured to compensate for differential expansion between the first and second semiconductor elements to reduce misalignment between at least the second and fourth contact features.