INFICON MDC-370 Thin Film Deposition Controller - Manual (Page 44)

MDC-370 DEPOSITION CONTROLLER
Soak Power Ramp - Rise to Soak Time, Soak Power and Soak Time
Predeposit Power Ramp - Rise to Predeposit Time, Predeposit Power and Ramp
to Feed Time
Feed Power Ramp - Ramp to Feed Time, Feed Power and Feed Time
4.2.7.2 AUTOMATIC CRYSTAL SWITCHING
To enable automatic Crystal switching upon failure, set the Fail parameter in the
Configure Sensors screen to Switch then set the Backup Sensor and Backup
Crystal parameters to define what to switch to.
4.2.7.3 RATE ESTABLISH
The rate establish feature is used in critical processes where it is important to
establish the correct deposition rate prior to opening the source shutter and
depositing on the substrates. To use this feature, the sensor head must be
mounted in such a way that it is in the material vapor stream with the source
shutter either opened or closed.
To enable this feature you must set the Rate Estab. Time and Rate Estab. Error
parameters. The Rate Establish Time parameter sets the maximum time that the
controller will attempt to keep the rate error within the Rate Estab. Error limit for
a period of five seconds. If the rate error condition is meet within the allotted
time then the controller will enter the deposit state. If not, then the process will be
halted and a Rate Establish Error will be displayed.
4.2.7.4 RATE RAMPS
Rate ramping is typically used at the beginning of the deposition to ease the rate
up slowly to prevent material spitting. Rate ramping is also used towards the end
of the deposition to achieve a more accurate endpoint thickness. By slowing
down the rate, the thickness overshoot caused by the delay of the shutter closing
is diminished
The MDC-370 has four rate ramps available. A rate ramp is defined by its Ramp
Start and Ramp Stop Thickness % and the next rate. For example, to setup the
370 to deposit at 20Å/sec for 90% of the layer, then ramp down to 5 Å/sec over
the last 10%, you would enter the following material parameters:
Deposit Rate #1 = 20Å/sec
Ramp Start Thk #1 = 90%
Ramp StopThk #1 = 100%
Deposit Rate #2 = 5Å/sec
The rate ramps are disabled by default with the Ramp Start and Ramp Stop
Thicknesses set to 100% since 100% represents the end of deposition for the
layer.
PROGRAMMING AND CONTROLLER SETUP 4-12