Diffusion Barrier for Hybrid Bonding Copper Pads
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Solution Overview
Problem
In three-dimensional integrated circuit (3DIC) semiconductor packaging, hybrid bonding of wafers faces challenges due to copper diffusion issues caused by misalignment and process variations, which can degrade device performance by exposing conductive pads to insulating materials.
Innovation Solution
A diffusion barrier layer, typically made of materials like TaN, SiN, or polymers such as benzocyclobutene, is formed around the conductive pads to prevent copper diffusion, ensuring alignment control and bonding with insulating materials to prevent shorting and device degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hybrid bonding is performed without a diffusion barrier layer, then bonding speed and process simplicity are improved, but copper diffusion occurs causing device degradation and electrical shorts
Solution Approach 1:
A diffusion barrier layer is deposited over the conductive pad before the bonding process. This preliminary action prevents copper diffusion during hybrid bonding, eliminating the need for post-bonding repairs while maintaining bonding speed and process simplicity.
Solution Approach 2:
The diffusion barrier layer acts as an intermediary between the conductive pad and the bonding interface. It mediates the interaction by blocking copper atoms from diffusing into the insulating material, thus preventing device degradation without interfering with the bonding process.
2Reliability
If a diffusion barrier layer is added to prevent copper diffusion, then device reliability is improved, but process complexity and manufacturing steps increase
Solution Approach 1:
The diffusion barrier layer deposition is merged with the existing hybrid bonding process flow. By integrating this single additional step into the standard process, the patent achieves reliable copper diffusion prevention without significantly increasing overall process complexity.
3Reliability
If the diffusion barrier layer completely covers the conductive pad, then copper diffusion is fully prevented, but alignment precision requirements increase due to potential misalignment
Solution Approach 1:
The diffusion barrier layer is applied with varying thickness or coverage based on local requirements. Areas with higher misalignment risk receive more extensive coverage, while well-aligned regions use minimal coverage, thus preventing copper diffusion without uniformly increasing alignment precision requirements across the entire wafer.
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
The diffusion barrier layer effectively prevents copper diffusion, maintaining device performance by ensuring alignment accuracy and preventing electrical shorts, thus enhancing the reliability of 3DIC structures.
Implementation Method 1
A diffusion barrier layer, typically made of materials like TaN, SiN, or polymers such as benzocyclobutene, is formed around the conductive pads to prevent copper diffusion
Data Source
AI summary
A method of forming a hybrid bonding structure includes depositing an etch stop layer over surface of a substrate, wherein the substrate comprises a conductive structure, and the etch stop layer contacts the conductive structure. The method further includes depositing a dielectric material over the etch stop layer. The method further includes depositing a first diffusion barrier layer over the dielectric material. The method further includes forming an opening extending through the etch stop layer, the dielectric material and the diffusion barrier layer. The method further includes lining the opening with a second diffusion barrier layer. The method further includes depositing a conductive pad on the second diffusion barrier layer in the opening, wherein a surface of the first diffusion barrier layer is aligned with a surface of the conductive pad.