Sacrificial Redistribution Layer for Void-Tolerant Direct Bonding
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Solution Overview
Problem
Direct bonding in microelectronic assemblies faces challenges due to the small size and thickness of components, finer interconnect pitches, and reduced z-height, leading to voids and incomplete connections, especially when conventional testing methods create particle and material pileup at the bonding plane, reducing adhesion strength and interconnect density.
Innovation Solution
A sacrificial redistribution layer with voids is introduced to facilitate testing without particle pileup, allowing for improved coupling and adhesion by selectively removing the RDL layer, which thins the DB contacts and forms voids between them, enabling better assembly yields and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional testing methods are used on IC dies, then die functionality can be tested, but particle and material pileup occurs at the bonding plane, reducing adhesion strength and interconnect density
Solution Approach 1:
A sacrificial redistribution layer is introduced as an intermediary between the die and the bonding interface. This layer allows testing to be performed on the die while preventing direct contact between testing materials and the bonding plane, thus avoiding particle pileup that would compromise adhesion strength.
Solution Approach 2:
The sacrificial redistribution layer is selectively removed after testing to expose the bonding interface. By extracting this temporary layer, the harmful particles and materials accumulated during testing are removed from the bonding plane, preserving adhesion strength while maintaining the ability to perform functionality testing.
2Manufacturing precision
If direct bonding is performed with smaller component sizes and finer interconnect pitches, then interconnect pitch is improved and z-height is reduced, but voids and incomplete connections occur
Solution Approach 1:
The sacrificial redistribution layer is prepared and patterned before the direct bonding process. This preliminary structure provides a controlled interface that guides the bonding process, ensuring complete connections even when working with finer interconnect pitches and smaller component sizes, thus preventing void formation.
3Strength
If the sacrificial RDL layer is selectively removed to thin the DB contacts, then voids are formed and adhesion is improved, but interconnect density may be reduced
Solution Approach 1:
The sacrificial redistribution layer is selectively removed only in specific regions where voids would form or where adhesion improvement is needed, rather than uniformly across the entire bonding interface. This localized removal maintains interconnect density in areas where it is critical while improving adhesion where needed.
Data Source
AI summary
Microelectronic assemblies, related devices and methods, are disclosed herein. In some embodiments, a microelectronic assembly may include a first microelectronic component having a first direct bonding region, wherein the first direct bonding region includes first metal contacts and a first dielectric material between adjacent ones of the first metal contacts; a second microelectronic component having a second direct bonding region, wherein the second direct bonding region includes second metal contacts and a second dielectric material between adjacent ones of the second metal contacts, wherein the first microelectronic component is coupled to the second microelectronic component by interconnects, and wherein the interconnects include individual first metal contacts coupled to respective individual second metal contacts; and a void between an individual first metal contact that is not coupled to a respective individual second metal contact, wherein the void is in the first direct bonding region.