Atomic Layer-Deposited Interlayers for Robust Metal-Polymer Interfaces

Area of Science:

• Materials Science
• Surface Science
• Mechanical Engineering

Background:

• Flexible electronics and space applications require robust metal thin films on polymer substrates.
• Film cracking and interfacial delamination are critical limitations in current flexible device technologies.

Purpose of the Study:

• To enhance the adhesion and electromechanical properties of aluminum films on polyimide substrates.
• To investigate the role of an amorphous aluminum oxide/hydroxide (AlO_xH_y) interlayer in improving film-substrate integrity.

Main Methods:

• Magnetron sputtering for aluminum film deposition.
• Atomic Layer Deposition (ALD) for the amorphous AlO_xH_y interlayer.
• In situ X-ray diffraction and electrical resistance measurements during uniaxial and equi-biaxial tensile testing.

Main Results:

• An up-to-3-fold increase in crack onset and electronic failure strains was observed.
• Adhesion energy of the metal-polymer system was doubled.
• The AlO_xH_y interlayer shifted interface deformation mechanisms from absorbing to blocking dislocations.

Conclusions:

• The integrated ALD-PVD approach significantly enhances the strain tolerance and adhesion of aluminum films on polyimide.
• The strengthened interface improves electromechanical stability, enabling flexible devices to withstand greater deformation.
• This method offers new possibilities for durable flexible electronics conforming to complex surfaces.