Electrically biased nanolithography with KOH-coated AFM tips.

Area of Science:

• Surface science
• Nanotechnology
• Scanning probe microscopy

Background:

• Self-assembled monolayers (SAMs) on gold-coated silicon are crucial for nanolithography.
• Oxidative patterning using atomic force microscopy (AFM) enables feature creation.
• Controlling pattern topography is essential for advanced applications.

Purpose of the Study:

• To characterize desorption and nanolithographic processes for SAM-coated substrates.
• To investigate factors influencing pattern formation (recessed vs. raised structures).
• To demonstrate control over topography via SAM properties and electrochemical conditions.

Main Methods:

• Oxidative nanolithography using AFM with a potential-controlled tip.
• Systematic study of eleven different SAMs with varying chain lengths and end groups.
• Investigation of local pH and hydroxide anion accessibility.
• Bias-controlled dip-pen nanolithography (DPN) with KOH-coated tips.

Main Results:

• Pattern topography (recessed or raised) depends on SAM characteristics and applied bias.
• Local pH and SAM choice significantly influence pattern type.
• Hydroxide anion accessibility is a key factor in determining topography.
• KOH concentration in the meniscus controls feature topography in DPN.

Conclusions:

• SAM desorption and nanolithography are controllable processes.
• Precise control over nanostructure topography is achievable through SAM selection and electrochemical environment manipulation.
• Understanding hydroxide accessibility offers a pathway to tailor nanolithographic outcomes.