In the semiconductor industry, Al Etch typically refers to the process of patterning aluminum thin films. This process is used to create various electrical components and interconnects on integrated circuits.

The Al Etch process typically involves coating a thin film of aluminum onto a semiconductor substrate, such as silicon. Then, a patterned mask is applied to the aluminum film, exposing selected areas that are to be removed. The unmasked areas are then etched away using a suitable etchant, usually a solution containing phosphoric acid and other additives. The etchant chemically reacts with the aluminum film, forming volatile reaction products that can be easily removed.

This process is used to fabricate structures such as interconnections between different circuit components, bonding pads, and antennas for RFID tags. The patterned aluminum thin films produced through Al Etch can also be used for metal-supported thin-film transistors, in which the metal film acts as the gate electrode.

It's important to note that the Al Etch process must be precisely controlled to ensure accurate patterning and avoid any under-etching or over-etching that could affect the performance of the resulting devices.

In conclusion, Al Etch refers to the process of patterning aluminum thin films on semiconductor substrates, a key step in fabricating various electrical components and interconnects for integrated circuits.