Plasma etcher

A plasma etcher, or etching tool, is a tool used in the production of semiconductor devices. Plasma etcher produces a plasma from a process gas, typically oxygen or a fluorine bearing gas, using a high frequency electric field, typically 13.56 MHz. A silicon wafer is placed in the plasma etcher, and the air is evacuated from the process chamber using a system of vacuum pumps. Then a process gas is introduced at low pressure, and is excited into a plasma through dielectric breakdown.

Uses

Plasma can be used to grow a silicon dioxide film on a silicon wafer (using an oxygen plasma), or can be used to remove silicon dioxide by using a fluorine bearing gas. When used in conjunction with photolithography, silicon dioxide can be selectively applied or removed to trace paths for circuits.

For the formation of integrated circuits it is necessary to structure various layers. This can be done by a plasma etcher. Before etching, a photo resist is deposited on the surface, illuminated through a mask, and developed. The dry etch is then performed so that structured etching is achieved. After the process, the remaining photo resist has to be removed. This is also done in a special plasma etcher, called an Asher.

Dry etching allows a reproducible, uniform etching of all materials used in silicon and III-V-semiconductor technology.

Plasma etchers are also used for delayering integrated circuits in failure analysis

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