"Ves-620
Systems"
Applications
The
VES-620 is a fully automated batch processor designed for precise wet chemical etching of aluminum layers on semiconductor wafers. Wafers are etched under vacuum so that hydrogen bubbles, an etching reaction which causes "snow" and "bridging", are immediately removed from the wafer surface and exhausted by an evacuating pump.
Unit is capable of processing up to two (2) cassettes of
150MM or one (1) cassette of 200MM wafers.
FEATURES:
- Fully automated batch process.
-
Fast throughput
- Eliminates "snow" and "bridging"
-
High yield
- Microprocessor-based control
PUMP MODULE:
Housed in a separate module, the vacuum pump and controls are sequenced from the etch module. The water ring type vacuum pump requires minimal maintenance and is ideally suited for pumping hazardous and corrosive gases.
The pump is supplied with a continuous flow of city water which passes through two stages and encapsulates gases, preventing damage to the internal parts of the pump.
A separator on the discharge port extracts the gases and drains the water. A flow switch on the water input line cuts off the pump if the supply is . insufficient. A
non-return valve on the vacuum port prevents back-siphoning of city water to the etch module if the pump stops.
OPERATION:
Place one or two standard
cassettes in the etch process tank. One wafer is
operator-selected and placed in the Endpoint Detector Assembly.
The user programs
Etch/Overetch mode and Rinse Times. In Ready mode, Cycle Start switch evacuates the plenum which draws acid up from the reservoir into the etch tank. The Etch Tank Level switch closes the acid transfer valves and the etch cycle begins.
Etching continues until the etch time elapses or the Endpoint Detector senses that lines have been etched through the aluminum layer, and overetch time comes into effect to further define the circuit geometries.
Overetch time is programmed as either fixed time or a percentage of the Endpoint Detector time frame.
At the end of the total etching period the plenum is vented to atmosphere and the transfer valves open to drain the acid to the acid reservoir.
Nozzles in the etch tank then spray DI water onto the wafer. DI water is used in the quench rinse and the final overflow rinse period cycle.
The end of the cycle is signaled by an audible alarm which
can be operator-cancelled with the Reset switch. Reset causes the DI water to drain, after which the
cassettes can be removed. The spray nozzles are then N2 purged and the system is ready for the next process cycle. |
