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UHT500™
500º C High Temperature High Vacuum Crystal Sensor System
The Ultimate Vacuum Deposition Monitor
A) Description
The UHT500™ is a temperature controllable film thickness measurement system for use in high vacuum thin film deposition systems. Using a combination of an embedded thermocouple and vacuum compatible cartridge heater in the sensor body, the UHT500™ provides the user with the capability to monitor and control a quartz or gallium phosphate crystal microbalance sensor at temperatures ranging from the chamber ambient to 500º C and with previously unattainable stability at low film deposition rates.
The UHT500 system eliminates many flaws inherent in conventional water-cooled and unmonitored quartz crystal microbalances and also offers new capabilities. The UHT500:
- Diminishes rate measurement instability, largely caused by the buildup of film stresses as a hot film deposits on a cool surface. This instability is a major source of crystal failure and film thickness errors. At low deposition rates (low fluxes) the rate noise severely limits the accuracy of the deposition rate measurement.
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Minimizes thickness measurement errors caused by temperature shifting of the crystal resonance frequency. Standard crystal sensors are not temperature monitored or controlled, and as a result have inherent uncertainty in their measurements. For sub nanometer thin films, this uncertainty can be on the order of 50% or more!
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Allows the user to match the crystal temperature to the substrate temperature, up to 500° C. This more accurately reflects the conditions that are occurring at the substrate level and may reveal useful phenomenon when studying thin film processes or vapor phase dynamics.
B) Features
The UHT500 operates at the industry standard frequency of 6 MHz, and is offered as a complete, turnkey system, consisting of:
1) The UHT500 electro polished, stainless steel sensor head with integral heater and thermocouple and demountable crystal cap
2) ConFlat™ flanged feedthrough, with high vacuum compatible TIG-welded connections
3) Matching Proportional Temperature Controller
4) All connecting cables
6) Operations manual
7) 5 pieces SuperQuartz R20 sensor crystals for use at temperatures from 50 to 500° C
C) Sensor Specifications (subject to change)
1) Operating Temperature 0-500 C
2) Vacuum rating: 10-7 Torr
3) Component materials
a) Sensor Body: 304 stainless steel, aluminum oxide insulators, 304 SS contact springs, 304 stainless steel connecting screws
b) Heater: pure alumina potted nichrome wire, 1200C UHV rated operation
c) Thermocouple: Type K, 304 stainless steel sheathed, welded to feedthrough body
d) Crystal Cable: stainless steel encased alumina beaded conductor
e) Internal heater Power Cable: alumina beaded silver plated copper wire
4) Dimensions:
a) Length: 6” to 48”, depending on customer requirements
b) Cross Section: Able to be passed through a 2.75” ConFlat port
(Note: Water lines shown only serve to support the sensor head. Contact us about the use of air cooling to maintain constant temperature above 50° C)
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