1. Process System
The process tube, made from GE214 Quartz, is 45 inches in length, and 4 inches inside diameter. It is canter levered on one end and supported by a water-cooled flange with dual "O" rings. A safety vacuum is maintained between these seals.
A condensation sleeve at the exhaust end of the process tube serves to collect particles, and is easily cleaned.
The load door assembly provides gas-tight entry to the process tube from the glovebox. It also supports the slider positioning mechanism, which has adjustable features to accommodate different boats.
A calibrated Type "R" thermocouple sheathed in fused quartz, is inserted into the boat to provide accurate, continuous monitoring of the process temperature.
2. Furnace System
The horizontal furnace, 30 inch long hot zone and 5 inch inside diameter, consists of an 18 inch long uniform hot zone, bounded by 6 inch end zones and 3 inches of insulation on each side. Kanthal heating elements allow a furnace temperature of up to 1100 degrees C, and are controlled by a three mode Temperature Control System, accurate to 0.1 degree C.
The furnace is rolled on and off the process tube by a motorized precision drive mechanism. A directed special cooling fan allows rapid cooling of the process tube once the furnace has been rolled back.
3. Vacuum System
Rough pumping is provided by a 4.5 CFM 2-stage pump. This is followed by a dual sorption pumping system, cooled with liquid Nitrogen. They can be operated independently, in sequence or in parallel.
Automatic leak detection is performed by ensuring that an evacuation process tube remains at a specified pressure for a specified time. In the event of a power failure during processing, Argon will automatically be flushed through the process tube, placing it a safe condition.
All vacuum lines are one inch in diameter with air operated/spring to close, high conductance type valves for maximum performance. A Fore-line filter and liquid Nitrogen trap eliminate hydrocarbon backstreaming. Type 316 S/S is used in all compartments of the manifold for optimum life under corrosive conditions.
A dual stage Pyrex Bubbler containing high grade Mineral Oil traps exhaust effluents and prevents backstreaming of Air, Oxygen, or contaminants from the exhaust system.
4. Gas Handling System
Argon and Hydrogen flow is precisely controlled by two Loop Mass Flow Controllers with a repeatability of 0.2 percent and an accuracy of 1.0 percent of full scale. Up to four Mass Flow Controllers for other processes are available as an option.
All gas lines are constructed from 0.25 inch type 304L S/S and have an inside surface finish of 16 RA. All valves, fittings, and assembled tubing are cleaned to standards for Oxygen service, and must pass a Helium Leak Test rate of less than 1 x 10-9 cc/sec.
Filters containing 5.0 micron sintered elements are placed on the inlet gas lines. A Palladium Hydrogen Purifier supplies ultra pure H2.
A glovebox, constructed of 304 S/S with a ½ inch thick polycarbonate window provides an inert gas purge interlock to the process tube. The glovebox is accessed through a vacuum cycled antechamber.
5. Control System
The Control System consists of three temperature controllers, a Programmable Logic Controller (PLC), vacuum pressure gauge, Graphic Control Display, press-to-test buttons, Sonalert Audible Alarm, and Alarm controls.
The temperature controllers are self-contained and store up to 15 temperature profile sequences, each with up to 8 segments.
The PLC automatically controls the furnace travel, mass-flow controller selection and flow rate, valve sequencing, interfaces to the furnace temperature controllers, and the slider positioning mechanism. The present step number and time remaining for each step are displayed.
In addition to the safety limit monitors, hydrogen detectors are used to sense the level of hydrogen in the furnace hood.
6. Computer Control System - An IBM compatible PC-AT is used to develop process recipes which are downloaded to the PLC. Ongoing processes can be monitored and displayed by the PC. The software was developed to require minimum programming knowledge. A color graphics display indicating the various process modes and status is available as an option.
Oxygen Analyzer capable of measuring O2
levels down to 5 to 10 PPB
Personal Computer Display Interface
SUPPORT SERVICES REQUIRED
Nitrogen or Argon: 4-8 LPM @ 40-100 PSI
Hydrogen: 1-5 LPM @ 150 PSI
Plant N2 or Air: 60-80 PSI
Process Exhaust: 11 LPM
Cabinet Exhaust: 375 CFM
Electrical: 15 kVA
Water Cooling at 25°C: 0.3 GPM