INFICON STM-100/MF Thin Film Deposition Monitor - Manual (Page 97)

SHMX-4 Operation
The Sensor Head Multiplexer (SHMX-4) used with a custom software
version of the STM-100/MF Thin Film Thickness/Rate Monitor allows the
individual monitoring of film thickness and deposition rates occurring upon up
to four crystal sensing heads. The SHMX-4 allows the signals from 1 of 4
active sensors to be displayed on the controlling STM-100. This combination
of the STM-100/MF and the SHMX-4 is useful in many multi-sensor monitoring
applications. While only one of the four sensors can be actively measuring the
rate and thickness, the accumulated thickness on each of these sensors can
be calculated and displayed as the sensors are selected during a deposition
process. This is because the initial frequency of the sensing crystal along with
its film parameters are stored for each sensor. The custom version software
for the STM-100 which accompanies this multiplexer provides the method and
means for storing these initial conditions for each sensing crystal. This allows
the user to switch between sensing crystals and display the correct thickness
reading for each sensor along with the current deposition rate occurring at the
selected sensor.
The front panel of the SHMX-4 is shown below, LED's indicate the active
sensor. During operation a Crystal fail condition in the sensors will be
indicated by a flashing LED.
SHMX-4
1 2 3 4
SENSOR HEAD MULTIPLEXER
instruments
ACTIVE SENSOR
Figure C.1: SHMX-4 Front Panel
Special firmware is required in the controlling STM-100, and the two relay
outputs
1. Elapsed Timer
2. Thickness Setpoint
have been disabled to allow access to the 4, individual sensors. The firmware
version of the controlling STM-100 must be STM100
VI6 or above. The
version can be verified by inspecting the label on the ROM Chip U15 on the
printed circuit board. The label will look like the diagram below.
Introduction
Page C- 1 SHMX-4 Operation