Ion beam milling etching is used in materials science fields as well as semiconductor industries for analysis, ablation, and deposition. The etching process is used for the revealing a pattern or even for removing that pattern. Typically, etching can be done either through chemical etching or plasma etching, otherwise known as wet or dry etching. Much like in photolithography, a photoresist is set up, and the parts not protected by that resist are etched out. In the semiconductor industry, dry etching is preferred in order to prevent the cutting of underlying materials. Wet etching does not have the same repeatability as dry etching does, and thus is not as heavily utilized. Ion beam milling, however, is able to solve the problem of lack of repeatability. For this reason, this technique of etching is preferred.

Ion beam milling etching can also etch a greater array of materials that can be etched. For instance, platinum cannot be wet etched, and as a very frequently used element in industries like microwaves, it is essential that it can be etched. Ion beam milling etching solves this problem with ineffective etching, as absolutely any material can be etched with ions. Most commonly etched elements include, but are not limited to, platinum, gold, copper, nickel, and titanium.

Ion beam milling works by using argon gas. Electrical discharge creates a cloud of plasma, accelerating argon ions to bombard the wafer.  This is what does the etching, removing the materials that are not covered by the photoresist through this process. During milling, a beam is focused on the wafer (hence the often interchangeable term "focused ion beam milling") and rotates throughout the entire process. The photoresist can then be removed afterwards and the material is successfully etched.

There are many reasons why ion beam milling is a very different process from electron beam etching. For starters, ions are larger than electrons. This means they cannot penetrate as deeply and that ions are caught in the matrix of the material rather than dispersing. Ions also have a positive charge, as opposed to the negative charge of electrons. This does not cause many difficulties, however, as the polarity accelerates and controls the beam in the way the electrons would naturally. What's more, ions are heavier than electrons, meaning they can build up a much higher momentum than electrons. These differences make ion beam milling etching capable of a higher level of control in relation to electron beams. Though ions are larger and move slower, they become much more controlled, and thus can overall, if used properly, can provide larger benefits down to the size of a nanometer.

Ion beam milling etching is an excellent medium for etching a number of different materials. It can etch many more substances than some typical etching techniques, and is ideal for the microwave and semiconductor industries for this. Employing a photoresist, it removes the uncovered and unnecessary  materials in a highly controlled manner, leaving an accurate pattern. Ion beam milling, though not as fast as an electron beam, can produce a higher quality image due to its precision. Because of this, ion beam milling etching can be highly efficient for companies that require etching.