AutoEtch 490 plasma etcher plasma etch semiconductor

The AutoEtch 490 transfers wafers from a send cassette to an entrance station, then into an entrance airlock, and into the process chamber for etching. After etching, the wafer moves to an exit airlock, then to the exit station, and finally to a receive cassette. The double airlocks allow the process chamber to remain under vacuum at all times.^[1][4][5]

The process chamber is anodized and equipped with quartz windows on the front and back, each with a wire mesh screen to contain the RF field and a plexiglass cover for UV filtering. The lower electrode (anode) holds the wafer, and its temperature is controlled by circulating ethylene glycol. The upper electrode (cathode) can be moved up or down by four DC motors driving lead screws, ganged with a common chain to ensure parallelism. A 10-turn potentiometer senses the position.^[1][4][5]

The upper electrode assembly includes an insulator ring, baffles, and the cathode. Process gases flow through a gas manifold and a showerhead hole pattern into the chamber. The cathode is electrically connected to the RF generator via an RF match assembly that automatically matches impedance using two adjustable air gang capacitors driven by DC motors.^[1][4][5]

Chamber pressure is controlled by a butterfly throttle valve attached to the chamber vacuum manifold, controlled by an automatic throttle valve controller (AC-2). The AC-2 compares the pressure setpoint with the chamber pressure measured by a capacitance manometer.^[1][4][5]

Wafer transport uses Hine Design Send/Receive Indexers mounted on the top-front plates. A motor-driven belt conveyor system moves wafers to and from the indexers. Entrance and exit station lifters elevate wafers using pneumatically driven pistons, with vacuum hold and infrared sensors for wafer presence and double-wafer detection.^[1][5]