The STM tip is a crucial component of the scanning tunneling microscope, as it enables the precise measurement of electronic properties and atomic-scale interactions.

In order to achieve the desired high-resolution and sensitivity, the STM tip must be extremely sharp, often consisting of a single atom or a few atoms at the apex. STM tip etching is a technique employed to create and maintain these sharp tips. This process generally involves the use of electrochemical methods, where the tip material is selectively removed to create a well-defined, atomically sharp tip.

The performance and reliability of scanning tunneling microscopy depend significantly on the quality of the STM tip, making tip etching an essential step for achieving accurate and reproducible results in atomic-scale investigations.