BTU International
TFQ In-line Diffusion Furnace w/ Gas-Tight Case
Specification No.: TFQ361-16-384A108GT Rev 4-4-08
Date: November 30, 2007
The BTU TFQ Series Furnace is a continuous conveyor furnace used for in-line Phosphorus Diffusion and other processes requiring air or nitrogen operation up to 1000°C.
A. GENERAL DESCRIPTION
The furnace is used for the in-line diffusion process, which is carried out in a ceramic and quartz chamber, with nitrogen atmosphere containing a small amount of oxygen. The atmosphere has to be stable in time especially with respect to the oxygen content. Moreover, only low flows of gasses in the muffle are allowed. By the nature of the diffusion process used, small amounts of phosphoric acid from the wafer will escape into the muffle atmosphere and then exhaust out of the process chamber by means of venturi actuated exhaust stacks.
B. FURNACE SPECIFICATION
Maximum temperature rating / 1050°COperating temperature range / 200-10000C
Number of controlled heat zones / 16
Heated Length / (384”) 9.7M
Working Dimensions / 914mm (36”) wide x 25mm (1”)
Clearance above the belt
Conveyor Height / 914 mm ± 25 mm (36 in. ± 1 in.) Standard
1000mm +/- 25mm (39 in. ± 1 in.) Optional
C. FURNACE LAYOUT
millimeters / inchesEntrance with Curtain, Baffle Assembly / 305 / 12
Entrance Vestibule
Preheated Atmosphere Inlet Zone 1 / 190 / 7.5
Zone I / 610 / 24
Dual Venturi Exhaust mounted in a controlled heated box and each with cooled exhaust traps w/clean-out access. / 38 / 1.5
Zone 2 / 610 / 24
Zone 3 / 610 / 24
Dual Venturi Exhaust mounted in a controlled heated box and each with cooled exhaust traps w/clean-out access. / 38 / 1.5
Zone 4 / 610 / 24
Preheated Atmosphere Inlet
Zone 5 / 610 / 24
Zone 6 / 610 / 24
Zone 7 / 610 / 24
Zone 8 / 610 / 24
Zone 9 / 610 / 24
Zone 10 / 610 / 24
Zone 11 / 610 / 24
Zone 12 / 610 / 24
Zone 13 / 610 / 24
Zone 14 / 610 / 24
Zone 15 / 610 / 24
C. FURNACE LAYOUT (Continued)
Zone 16 / 610 / 24
Exit Vestibule of Inconel Construction / 152 / 6
Hearth Plate Cooling with Separation Joint and Preheated Atmosphere Inlet / 456 / 18
Water Cooling Zone 1 / 914 / 36
Water Cooling Zone 2 / 914 / 36
Water Cooling Zone 3 / 914 / 36
Exit with Curtain Baffle Assembly / 305 / 12
Frame Allowance / 128 / 5
APPROXIMATE WORKING LENGTH / 14M / 46FT
Loading Table 1372 mm (54 in.) Wide
Loading Table Length / 610 / 24
Unloading Table 1372 mm (54 in.) Wide
Unloading Table Length / 610 / 24
APPROXIMATE TOTAL FURNACE LENGTH / 15.1M / 50FT
APPROXIMATE TOTAL FURNACE WIDTH / 1625 / 64
D. PROCESS CHAMBER
· The process chamber is an open chamber design, featuring an enclosed gas-tight outer case with strategically located access panels.
· Heaters are Fully Enclosed Coil (FEC) manufactured by BTU, using coils enclosed in ceramic fiber plates. Heaters are located top and bottom in the process chamber and feature cross-belt, left/center/right independent trim. Trim control allows for precise temperature uniformity tuning.
· Quartz plates are used between the heaters and the processing area to create a clean, contaminant-free environment, maintain tight atmosphere control and shield heaters from the exposure to phosphoric acid.
· The conveyor belt travels on top of quartz hearth tubes.
· The refractory furnace case (between the quartz lined process chamber and the outer gas-tight case enclosure) is purged with Nitrogen, in order to minimize any migration of the phosphoric acid outside of the quartz lined process chamber. The gas tight case will prevent any leakage of the phosphoric acid fumes into the room.
· Water-cooling section consists of copper tubes on the outside of the metal muffle. The water-cooling tubes are secured to the muffle with high conductivity aluminum heat sinks. Compared to other water jacket design, the heat sink system has a higher heat transfer rate per unit under identical water flow rates and heat load.
· Thermostatic water control, water flow and temperature alarms are included in the cooling section. The system will shut down the heater power in the event of a loss of water flow or excessive water temperature.
· Water flow meters are included in each cooling zone.
· Case cooling exhaust fans maintain comfortable exterior panel temperature and can be connected directly to room exhaust system.
· Spent Process gasses are exhausted independently from the process chamber by means of the venturi actuated exhaust stacks. These stacks include a heated box with a gas cooled trap arrangement with clean out. Once trapped, remaining gasses are directed to customer supplied facility exhaust.
E. CONVEYOR SYSTEM
Belt Material / Nichrome VBelt Mesh /
B24-12-16
Belt Width / 914mm (36 in.)Belt Speed Range / 25-152 mm per min (10-60 IPM)
Design Speed / 686mm per min (27 IPM) *See Below
Maximum Belt Loading / 2.5 Kg/M2 (0.5 lbs/ft2
· Nichrome V (high temperature, oxide resistant material, made of 80% Nickel and 20% Chromium)
· Speed Control is programmable in inches per minute with readout on the PC. Deviation from set point alarm is programmable.
· *Belt speed could operate up to 762 mm (30 IPM) and still achieve a 10 minute flat.
· All belt return components that come in contact with the belt are to be iron free.
· Tabletops and entrance muffle include quartz hearth tubes to minimize belt contact with metal surfaces.
· An ultrasonic conveyor belt cleaner is provided and designed for use with DI Water and a forced air radiant dryer. The dryer is designed to dry the belt at a maximum speed of up to 762 mm per min. (30 IPM). It is recommended that this operation be carried out during non-processing times. The cleaning process is started by the recipe scheduler and is fully automatic. DI water from the Ultrasonic Tank is to be plumbed to customer furnished neutralization unit, prior to returning to the tank or to the plant drain
· Alarms include Belt Stopped and Belt Stretched. (From sensor in USBC)
F. MATERIAL CONTAMINATION
The wafers should not come into contact with any other material other than the conveyor belt. The belt should not contact any materials other than quartz and iron free components. In particular the belt will not be in contact with any aluminum, aluminum alloys, copper, copper alloys or iron
G. CONTROLS
· Controls are located on the right hand side as viewed from the entrance of the furnace.
· BTU “Intellimax” microprocessor-based controller controls furnace.
· Zones I through XVI are each controlled by:
o 1- Microprocessor control channel
o 1- Type KPB dual thermocouple
o 3- Solid State Relays
o 3- Programmable Trims (Digitally set Left-Center-Right trims enable precise cross belt temperature uniformity and are stored as part of the recipe for specific profiles)
· A Flat Panel VGA Color Graphic Monitor as well as a Pentium computer with Windows based “WINCON” furnace control software for full temperature and conveyor speed, monitoring, setting, profiling and recipe storage are provided. The flat-panel display and keypad are mounted on a swivel type bracket near the gas-panel to ensure clearance over the exit table. PC is mounted beneath the load table.
· General Alarms:
o High Temperature Limit
o Low Temperature Limit
o Furnace Over-temperature
o Low Gas Pressure
o Low Water Flow
o Water Over temperature
o Conveyor Stopped
o Conveyor Deviation
G. CONTROLS (Continued)
· A 4-color (red/amber/green) status Light Tower is included and located at the exit, top of the furnace. Light color indicators are as follows:
o Red = Fault/Alarm/Error Condition
o Yellow = Alert Condition
o Green = Process/ Machine Ready Condition
o Blue = Requires load/unload (Note: No circuitry provided to enable this light as a SMEMA system not purchased or provided)
H. OVER-TEMPERATURE PROTECTION
A separate and independent non-indicating factory set overheat protection is provided in each zone. When furnace temperature exceeds overheat condition, heater power is shut down. A Heater Failure Alarm is included.
I. ATMOSPHERE CONTROL SYSTEM
Gas System
BTU Atmosphere Control System is included for operating in Air or Nitrogen. Flow meters are provided as follows:
1 - Entrance Curtain
1 - Preheated Atmosphere Inlet Zone 1
1 - Dual Venturi Actuated Exhaust Zone 1/2
1 - Dual Venturi Actuated Exhaust Zone 3/4
1 - Preheated Atmosphere Inlet Zone 4
1 - Preheated Firing Chamber (inlet at the end of the insulated cooling section with counter flow)
1 - Oxygen Mixing
1 - Exit Curtain
1 - Case Purge
· System includes two low gas pressure alarms for detecting a loss in supply pressure (N2 and Air) to the furnace.
· Low-pressure alarms are silenced via the furnace controller.
Gas Flow
· The pre-heated firing section atmosphere is introduced into the furnace at the end of the insulated cooling section and flows counter to the travel of the belt towards the venturi actuated exhaust stacks, located between zones 1 & 2. A pre-heated gas inlet is included at the beginning of zone 1 with flow towards the venturi actuated exhaust stacks between zones 1 & 2. An additional atmosphere inlet is located at the end of zone 4 towards the venturi exhaust stacks located between zones 3 & 4.
· All gas plumbing for the furnace atmosphere is to be standard copper tubing with compression fittings and high purity PP (Poly Propylene with a NSF-51 rating) lines and fittings. Stainless steel lines and fittings used in all high heat areas.
· All plumbing utilities (Gasses and water inlet and outlet) will connect to fittings at the top rear exit corner bulkhead panel.
J. ELECTRICAL SPECIFICATION
Connected Load / 325 kWNominal Load / 200 kW
Available Voltage / (R-2) 440-480 volts (as previous) including step-down transformers mounted within the furnace enclosure
· Heater Power Figure is approximate and should not be used for design purposes. Actual loading (KVA) is determined at the time of engineering and formal notification will be sent to the purchaser.
· Five (5) Emergency Off Buttons are provided, two at each end of the furnace and one at the gas-panel, connected to a 24V emergency off circuit.
K. PHYSICAL CHARACTERISTICS
Color / Pillar WhiteApproximate Shipping Weight / TBD
L. INSTRUCTIONS
Two books of instructions covering all phases of installation, operation and maintenance are included. In addition, an electronic copy of the manual is also included.
M. FEATURES INCLUDED TO MEET BP SOLAR REQUIREMENTS
Note: Items listed below are features added to our standard design to meet BP Solar requirements. These are features that have previously been included in BTU equipment for Phosphorous Diffusion furnaces, as recently furnished to BP Solar in Frederick, Sydney, Madrid and Bangalore, as well as items requested by the BP Solar Global Evaluation Team.
· Heater Failure Alarm is included to detect and alarm in the event of any heater failure, including the left, center and right trim segments of each heater (Top & Bottom), of each zone.
· A lockable main circuit breaker with shunt trip and 30 mA leak detection ground fault is included with Plexiglas cover internal to the cabinet side cover.
· A UPS system is included to function as a voltage surge protection and to enable the controls and conveyor belt to operate and unload the furnace.
· A voltage monitor is included is included to alarm in the event that the power level drops below a pre-selected level.
· Outlets are included internal to the furnace enclosure for the PC and monitor, etc. Indian style switched outlets with plugs are included for furnaces destined for Bangalore, India.
· Electrical safety interlocking panels are included to open the main contactor if any panel is removed. The panel interlocking circuitry will have a maintenance by-pass key switch capability, to permit live probing of components. This interlocking panel system circuit is also interconnected with the Emergency Off button system, to open the main contactor and power-off all components downstream (Except for the PC –stays on), similar to latest BTU diffusion furnaces supplied to Frederick, Madrid, Sydney and Bangalore.
M. FEATURES TO MEET BP SOLAR REQUIREMENTS (Continued)
· Flat panel display and keyboard can be mounted on a swing-arm type bracket mounted on the exit end panel or on top of the furnace enclosure, near the exit end of the furnace. (Pls. specify)
· A back-up V hard drive (USB type) is included with cable to “WINCON”.
· Remote Diagnostic system (MS “PC Anywhere”) is included, enabling accessing control system remotely.
· A ¼ turn safety N2 lockable gas valve is included for maintenance use.
· Top isolation valves are included for the three water-cooling sections.
· A cooling water flow alarm is included. In addition a type E thermocouple wired to “WINCON” is included complete with auto-switching to the cool-down recipe, in the event of a cooling-water temperature failure.
· An alarm to detect high temperatures within the water-cooling enclosure module (rear of gas panel) is included, consisting of a type K thermocouple (Mounted to measure free air in the enclosure) and wired to a dedicated Overtemp type module, to activate a rotating warning light beacon located on the water-cooling enclosure top cover, in the event of a high temperature condition.
· Vertical metal strips with zone indication on the side of the furnace case are no longer required since the zones are clearly delineated, as part of the case construction.
· Install drawing to include exhaust flow requirements, as well as a sketch of a typical hood installation over the stacks, with recommended spacing between the stack top and the start of the hood. Provide maximum/average flows for N2/Air and exhaust. DI and cooling water to have maximum/average flow requirements listed, as well as describing the DI water and cooling-out water with a pressure figure or simply RETURN, in lieu of the current OPEN DRAIN. NOTE: The install drawing and all drawings normally provided to the customer (Plumbing and Electrical Schematics) to be in world-standard SI units.