Atomic layer deposition ultra-barriers for electronic applications-strategies and implementation

Area of Science:

• Materials Science
• Thin Film Technology
• Surface Chemistry

Background:

• Polyester films are widely used but often require enhanced barrier properties for applications sensitive to moisture.
• Atomic Layer Deposition (ALD) offers precise control over thin film growth, making it a candidate for creating high-performance barrier layers.

Purpose of the Study:

• To evaluate the moisture barrier performance of aluminum oxide (Al2O3) thin films deposited by ALD on polyester.
• To investigate the mechanism of gas permeation through ALD Al2O3 films and identify factors influencing barrier effectiveness.

Main Methods:

• Atomic Layer Deposition (ALD) of Al2O3 thin films on polyester substrates.
• Long-term moisture permeation testing (over three years) to quantify barrier performance (<10(-5) g-H2O/m2-day).
• Analysis of permeation onset mechanisms, film thickness, ALD process temperature, and surface treatments (plasma treatment, substrate side).

Main Results:

• ALD Al2O3 films demonstrated ultrabarrier performance with moisture permeation below 10(-5) g-H2O/m2-day, sustained over three years.
• Gas permeation was found to initiate abruptly, not due to pinholes, and was influenced by film thickness and ALD temperature.
• Plasma treatment of polyester enhanced hydrophilicity and reduced moisture permeation; deposition on the bare or non-slip side was also beneficial.

Conclusions:

• ALD Al2O3 films provide exceptional, long-lasting moisture barrier properties on polyester.
• The permeation mechanism is linked to film defects rather than pinholes, and can be optimized through process control and surface engineering.
• ALD Al2O3 represents a promising technology for creating high-performance flexible barrier films.