Model 110
Dual Channel Detector
Model 110 Detector Head and Controller
Model
110 Brochure
124kb Acrobat file
The Model 110
Optical Endpoint System consists of two modules -a detector head and a
remotely mounted variable gain amplifier/controller. The Model 110 Detector
Head contains a dual channel photodiode detector. Two large area photodiodes
are coupled to highly sensitive JFET amplifiers with jumper selectable
gain. The photodiodes are kept at a constant temperature with a closed
loop controlled Thermo-Electric Cooling device. Separate 10nm bandpass
filters, one for each photodiode detector, are mounted in an easily removed
tray. Light collimating lenses precede the filters for enhanced sensitivity
and broadband light rejection. A built in preamplifier ensures a strong
noise-free signal will reach the remote variable gain amplifier.
The Variable Gain Amplifier/Controller contains
two separate 0-40dB variable gain amplifiers -one for each photodiode
detector. Independent control of these amplifiers is facilitated through
two 0-10vdc analog inputs. In addition to the two 0-10vdc signal outputs,
two chart recorder outputs are available on BNC connectors, one for each
photodiode detector. The Amplifier/Controller contains the driver and
control circuitry for the Thermo-Electric Cooler. The entire system is
powered by +24 and +5vdc.
Endpoint Detection
In order to ensure run-to-run repeatability in semiconductor processing, today's fine-line geometries demand tighter control of the process parameters directly associated with the plasma reaction itself. Endpoint is one of those parameters and is defined as the point in time when an overlying layer of materials is completely removed, thus exposing the underlying layer. In order to prevent dimensional loss and undercutting of subsequent layers, it is critical that the process is terminated at the endpoint interface, with some degree of control, rather than relying on fixed times or a visible change in the color of the plasma.
