In a closed chamber, an anode target is placed, filled with gas, maintained at a certain degree of vacuum, and a high voltage is applied between the anode and the cathode, and a glow discharge phenomenon will occur. The ionized gas ions bombard and erode the anode target. The target atoms are thus diffused around and deposited on the sample, resulting in a uniform coating on the sample surface. This coating can inhibit charging, reduce thermal damage, and increase secondary electron yield, thereby improving SEM observations.

In normal use, the most common target is the gold target. It is for this reason that the ion sputtering instrument is also commonly known as "gold spraying instrument".
1. Chromium target: In recent years, the use of chromium target coating has become more and more popular. Chromium targets provide thinner continuous dense films and produce fewer backscattered electrons than other targets.
2. Iridium target: The latest research shows that using iridium for sputtering can also obtain ultra-fine thin films (sub-nanometer), which is comparable to that of chromium target coatings. But whether a chromium target or an iridium target is used, high vacuum equipment is required for effective sputtering.