Hybrid Molecular Bonding Circuit Pads for Pre-Test and Planarization
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Solution Overview
Problem
Existing electronic circuit preparation methods for hybrid molecular bonding face issues with unwanted connections between test pads and HBM pads, leading to surface defects and bonding failures due to incompatible surface states and dimensions.
Innovation Solution
The electronic circuit design includes a test pad with a higher density of conductive material and specific dimensions, allowing for pre-testing before hybrid molecular bonding, followed by surface planarization to ensure compatibility with hybrid molecular bonding requirements, using an insulating layer with exposed conductive pads and test pads that match the bonding pads in composition and structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If test pads are provided on the surface for pre-testing before hybrid molecular bonding, then testing capability is improved, but unwanted connections between test pads and HBM pads occur causing surface defects and bonding failures
Solution Approach 1:
The patent applies local quality by creating distinct regions with different conductive material densities: test pads have high density (40-80%) for electrical testing, while HBM pads have low density (<30%) for reliable molecular bonding. The insulating layer is selectively removed in test pad areas but maintained in HBM pad areas, creating locally optimized surfaces that prevent unwanted connections while enabling testing capability.
2Reliability
If the surface is prepared for hybrid molecular bonding with low density conductive material distribution, then bonding reliability is improved, but testing capability before bonding is lost
Solution Approach 1:
The patent segments the surface into functionally distinct zones: test pad regions with high conductive material density for electrical testing, and HBM pad regions with low conductive material density for molecular bonding. This segmentation allows each zone to be optimized for its specific function without interfering with the other, enabling both testing capability and bonding reliability to coexist.
3Ease of operation
If test pads with large dimensions are provided for testing, then testing accessibility is improved, but surface flatness and roughness criteria for hybrid molecular bonding are compromised
Solution Approach 1:
The patent applies preliminary action by selectively removing the insulating layer in test pad areas before the hybrid molecular bonding process. This preliminary removal creates large-dimensional test pads that are accessible for testing with proper probe contact, while the insulating layer remains intact in HBM pad areas to maintain the required surface flatness and roughness criteria for reliable molecular bonding.
Data Source
AI summary
An electronic circuit including a surface intended to be attached to another electronic circuit by hybrid molecular bonding. The electronic circuit includes an electrically-insulating layer exposed on the surface, and, distributed in the electrically-insulating layer, first electrically-conductive bonding pads exposed on a first portion of the surface, the density of the first bonding pads on the first portion of the surface being smaller than 30%, and at least one electrically-conductive test pad, exposed on a second portion of the surface containing a square having a side length greater than 30 μm. The density of electrically-conductive material of the test pad exposed on the second portion of the surface is in the range from 40% to 80%.