Preparation and performance of semiconductor device bonding joints based on Cu@Sn@Ag preform

Area of Science:

• Materials Science
• Electrical Engineering
• Solid-State Physics

Background:

• Silicon (Si) diodes require robust interconnects capable of withstanding high temperatures and power cycling.
• Traditional lead-tin (PbSn) solders face limitations in high-temperature applications and environmental concerns.
• Transient liquid-phase diffusion soldering offers a promising alternative for creating high-performance interconnections.

Purpose of the Study:

• To develop and evaluate a novel Cu@Sn@Ag interconnection for high-power Si diodes.
• To investigate the mechanical, thermal, and power cycle reliability of the Cu@Sn@Ag joint.
• To compare the performance of the Cu@Sn@Ag joint against conventional PbSn5Ag2.5 joints.

Main Methods:

• Fabrication of Cu@Sn@Ag preforms using electroplating and physical vapor deposition.
• Transient liquid-phase diffusion soldering to create a dense Cu/Cu3Sn/Ag3Sn joint.
• Mechanical testing (shear strength), thermal resistance measurement, and active power cycle reliability testing.

Main Results:

• The Cu@Sn@Ag joint exhibits an average shear strength of ~35 MPa, surpassing PbSn5Ag2.5 joints.
• The minimum thermal resistance of the device with the Cu@Sn@Ag joint is ~0.18 K/W, comparable to PbSn5Ag2.5 joints.
• The Cu@Sn@Ag joint demonstrates excellent power cycle reliability, with forward voltage drop below 2% after 150,000 cycles, meeting automotive standards.

Conclusions:

• The Cu@Sn@Ag joint fabricated via transient liquid-phase diffusion soldering offers superior performance and reliability for high-power Si diodes.
• This advanced interconnection technology is a viable alternative to PbSn solders for high-temperature and high-reliability power device applications.
• The developed joint meets stringent automotive reliability requirements, indicating its potential for widespread adoption.