Assessment of the Risk of Crack Formation at a Hybrid Bonding Interface Using Numerical Analysis

Area of Science:

• Materials Science and Engineering
• Semiconductor Manufacturing
• Reliability Engineering

Background:

• Hybrid bonding is a key technology for advanced semiconductor packaging.
• Reliability challenges, including crack formation from defects and misalignment, hinder commercialization.
• Understanding thermomechanical stress is critical for improving hybrid bonding.

Purpose of the Study:

• To investigate crack formation in hybrid bonding structures due to chemical mechanical polishing (CMP) defects and misalignment.
• To analyze the effects of annealing temperature and dishing on non-bonding area and peeling stress.
• To identify vulnerable interfaces and conditions prone to cracking.

Main Methods:

• Numerical simulations were employed to analyze crack formation and thermomechanical stress in two common hybrid bonding structures.
• The study systematically evaluated the impact of annealing temperature and dishing value on non-bonding area and peeling stress.
• Calculated peeling stresses were compared with bonding interface strengths to pinpoint regions susceptible to cracking.

Main Results:

• Non-bonding area increases with lower annealing temperatures and higher dishing values; annealing >200°C ensures >90% bonding area.
• SiCN-to-SiCN interfaces exhibit highest peeling stress during heating (risk at 350°C, minimized <250°C).
• SiCN-to-Cu interfaces show highest stress during cooling, but simulated stresses remain below adhesion strength, indicating low cracking risk.

Conclusions:

• Optimizing annealing temperature and dishing is essential for maximizing bonding area and preventing cracks in hybrid bonding.
• The SiCN-to-SiCN interface is most vulnerable during annealing, while SiCN-to-Cu is most stressed during cooling.
• This research provides critical insights for enhancing the reliability of advanced hybrid bonding structures.