Process Temperature Control for Low Dishing in CMP

Area of Science:

• Materials Science
• Semiconductor Manufacturing
• Chemical Engineering

Background:

• High-performance semiconductors demand hybrid bonding, necessitating precise copper dishing control.
• Chemical Mechanical Planarization (CMP) is vital for achieving this control.
• Existing methods modifying slurry or mechanics have proven insufficient for optimal dishing control.

Purpose of the Study:

• To investigate the impact of process temperature on CMP performance.
• To demonstrate temperature's role in integrating chemical and mechanical aspects of CMP.
• To develop a method for precise temperature control in CMP.

Main Methods:

• Evaluated removal rates of Cu, Ta, and SiO2 films using blanket wafer experiments.
• Analyzed film removal rates as a function of temperature and activation energy (Arrhenius-type behavior).
• Developed a vortex-tube-based pad cooling system for precise temperature regulation.

Main Results:

• Film removal rates exhibited Arrhenius-type behavior with temperature.
• A process temperature of 30 °C balanced selectivity and minimized dishing on patterned wafers.
• Temperature control reduced dishing from 12-16 nm to 4 nm and below 1 nm for 100 µm and 50 µm patterns, respectively.

Conclusions:

• Process temperature is a critical, yet often overlooked, parameter in CMP.
• Precise temperature control is essential for managing selectivity and minimizing copper dishing.
• Optimized temperature control via a novel cooling system meets hybrid bonding requirements.