Advantages and disadvantages of atomic force microscope probe

AFM probes are basically prepared by processing Si or Si3N4 with MEMS technology. The radius of the probe tip is generally 10 to several tens of nm. Micro-cantilever is usually made of silicon wafer or silicon nitride, with a length of 100~500μm and a thickness of about 500 nm ~ 5 μ m. A typical silicon micro-cantilever is about 100μm long, 10μm wide and several microns thick.

Microscopes in different application fields are developed by using different interaction forces between probes and samples, such as AFM (Van der Mana), electrostatic microscope EFM (electrostatic force), magnetic microscope MFM (static magnetic force) and lateral force microscope LFM (lateral deflection force of probe), so different kinds of microscopes have corresponding probes.

The probes of atomic force microscope mainly include the following types:

(1), non-contact/tapping mode needle tip and contact mode probe: the most commonly used products with high resolution and average service life. The probe is constantly worn in the process of use, and the resolution is easy to decrease. Main uses and surface morphology observation.

(2) Conductive probe: It is obtained by plating Pt (and other metals, such as Cr, Ti, Pt and Ir) with a thickness of 10-50 nm on a common probe. Conductive probes are used in EFM, KFC, SCM, etc. The resolution of the conductive probe is worse than that of tapping contact, and the conductive coating is easy to fall off during use, so it is difficult to maintain conductivity for a long time. The new products of conductive needle tip include carbon nanotube needle tip, diamond coated needle tip, all-diamond needle tip and all-wire needle tip. These new technologies overcome the shortcomings of short life and low resolution of common conductive needle tips.

(3) Magnetic probe: used in MFM, it is made by plating ferromagnetic layers such as cobalt and iron on common tapping and contact probes. The resolution is worse than that of ordinary probes, and the conductive coating is easy to fall off during use.

(4) High aspect ratio probe: The high aspect ratio probe is specially designed and produced for measuring deep grooves and nearly vertical sides. Features: Unused products, high resolution and average service life. Technical parameters: needle tip height >; 9 μm； The length-width ratio is 5:1; Needle tip radius

(5) Diamond-like carbon AFM probe/all-diamond probe: one is to add a diamond-like carbon film on the tip of the silicon probe, and the other is to prepare all-diamond materials (very expensive). These two kinds of diamond carbon probes have strong durability, which reduces the wear of the needle tip and increases the service life.

There are also biological probes (molecular functionalization), force modulation probes and indentation probes.