Abstract: Multi-zone IR solar cell processing furnaces using a single, full-width conveyor belt; selected zones are divided into multiple lanes by upper or/and lower longitudinal divider walls, and heated by high intensity radiation IR lamps backed by a flat plate of ultra-high reflectance ceramic material. Lamp numbers and spacing in each zone/lane can be varied. Power to each lamp, or zone/lane lamp array, both upper and lower, is individually and independently controlled to provide infinite number of temperature profiles in each heating zone/lane. In multi-lane zones the IR lamps are folded, the inner ends being supported by the lane dividers. Lamp external power leads are both accessible from one side of the furnace. The lamp internal filaments include non-radiant and radiant sections arranged so that a pair of radiant sections are aligned in the lamp-folded configuration and disposed over the full width of the solar cell wafers.

Abstract: Multi-zone, solar cell diffusion furnaces having a plurality of radiant element (SiC) or/and high intensity IR lamp heated process zones, including baffle, ramp-up, firing, soaking and cooling zone(s). The transport of solar cell wafers, e.g., silicon, selenium, germanium or gallium-based solar cell wafers, through the furnace is implemented by use of an ultra low-mass, wafer transport system comprising laterally spaced shielded, synchronously driven, metal bands or chains carrying non-rotating alumina tubes suspended on wires between them. The wafers rest on raised circumferential standoffs spaced laterally along the alumina tubes, which reduces contamination. The high intensity IR flux rapidly photo-radiation conditions the wafers so that diffusion occurs >3× faster than conventional high-mass thermal furnaces. Longitudinal side wall heaters comprising coil heaters in Inconel sheaths inserted in carrier tubes are employed to insure even heating of wafer edges adjacent the side walls.

Abstract: A new class of work-piece conveyors, comprising zero-mass, shadow-less transport systems, with a drive having a pair of parallel, laterally spaced, movable chains defining a processing path, with fingers projecting transversely toward the process path centerline. The gap between fingers eliminates conveyor tube/rod supports, improving wafer quality and conserving energy. Implementations include wire chain, band and roller chain transports to which fingers are secured. Fingers are angled down so that the intersection of the bottom and side edges of the work-piece make only point contacts with each finger. A pair of finger chains implement a single lane drive; adding center bilateral finger drive chains with oppositely pointing fingers implement a multi-lane system. The inventive method includes individually configurable processing temperature profiles in side-by-side lanes, on a zone-by-zone, upper and lower half basis for broad processing flexibility.

Abstract: Multi-lane, side-by-side, independently driven transport systems particularly useful for transfer on conveyor belts or finger/chains of thin work pieces, such as silicon wafers, through processing equipment for converting the wafers into solar cells, including UV pre-treaters, dopers, dryers, diffusion furnaces and metallization furnaces. The inventive multi-lane transport systems may employ wire mesh belts having a flying bridge wafer support system comprising longitudinally spaced carrier wire elements that support the wafers at their side edges at only point contacts, by means of opposed, inwardly inclined, downwardly slanted segments or wings. Alternately, finger drives comprising spaced-apart chains having inwardly projecting fingers may be used for transport of the wafers by side edge contact. Friction or sprocket drives having tensioner assemblies associa-ted therewith are used to move the transport belts or finger chains through the furnace zones.

Abstract: Silicon wafer processing system, apparatus and method of doping silicon wafers with hot concentrated acid dopant compositions for forming p-n junction and back contact layers during processing into PV solar cells. Highly concentrated acid dopant is atomized with pressurized gas and heated in the range of 80-200° C., then introduced into a concentrated acid vapor processing chamber to apply vapor over 1.5-6 min to wafers moving horizontally on a multi-lane conveyor system through the processing chamber. The wafers are dried and forwarded to a diffusion furnace. An optional UV pre-treatment assembly pre-conditions the wafers with UV radiation prior to dopant application, and doped wafers may be post-treated in a UV treatment module before being fired. The wafers may be cooled in the processing chamber. Post-firing, the wafers exhibit excellent sheet resistance in the 60-95?/sq range, and are highly uniform across the wafers and wafer-to-wafer.

Abstract: Multi-zone IR solar cell processing furnaces using a single, full-width conveyor belt; selected zones are divided into multiple lanes by upper or/and lower longitudinal divider walls, and heated by high intensity radiation IR lamps backed by a flat plate of ultra-high reflectance ceramic material. Lamp numbers and spacing in each zone/lane can be varied. Power to each lamp, or zone/lane lamp array, both upper and lower, is individually and independently controlled to provide infinite number of temperature profiles in each heating zone/lane. In multi-lane zones the IR lamps are folded, the inner ends being supported by the lane dividers. Lamp external power leads are both accessible from one side of the furnace. The lamp internal filaments include non-radiant and radiant sections arranged so that a pair of radiant sections are aligned in the lamp-folded configuration and disposed over the full width of the solar cell wafers.

Abstract: High reflectance element IR lamp module and method of firing multi-zone IR furnaces for solar cell processing comprising lamps disposed backed by a flat or configured plate of ultra-high reflectance ceramic material. Optionally, the high reflectance plate can be configured with ripples or grooves to isolate each lamp from adjacent lamps in the process zone. Furnace cooling air is exhausted and recycled upstream for energy conservation. Lamp spacing can be varied and power to each lamp individually controlled to provide infinite control of temperature profile in each heating zone. The high reflectance element may be constructed of dense ceramic fiber board, and then coated with high reflectance ceramic composition, and baked or fired to form the finished element.

Abstract: Multi-zone, solar cell diffusion furnaces having a plurality of radiant element (SiC) or/and high intensity IR lamp heated process zones, including baffle, ramp-up, firing, soaking and cooling zone(s). The transport of solar cell wafers, e.g., silicon, selenium, germanium or gallium-based solar cell wafers, through the furnace is implemented by use of an ultra low-mass, wafer transport system comprising laterally spaced shielded, synchronously driven, metal bands or chains carrying non-rotating alumina tubes suspended on wires between them. The wafers rest on raised circumferential standoffs spaced laterally along the alumina tubes, which reduces contamination. The high intensity IR flux rapidly photo-radiation conditions the wafers so that diffusion occurs>3× faster than conventional high-mass thermal furnaces. Longitudinal side wall heaters comprising coil heaters in Inconel sheaths inserted in carrier tubes are employed to insure even heating of wafer edges adjacent the side walls.

Abstract: Multi-zone, solar cell diffusion furnaces having a plurality of radiant element (SiC) or/and high intensity IR lamp heated process zones, including baffle, ramp-up, firing, soaking and cooling zone(s). The transport of solar cell wafers, e.g., silicon, selenium, germanium or gallium-based solar cell wafers, through the furnace is implemented by use of an ultra low-mass, wafer transport system comprising laterally spaced shielded metal bands or chains carrying non-rotating alumina tubes suspended on wires between them. The wafers rest on raised circumferential standoffs spaced laterally along the alumina tubes, which reduces contamination. The bands or chains are driven synchronously at ultra-low tension by a pin drive roller or sprocket at either the inlet or outlet end of the furnace, with appropriate tensioning systems disposed in the return path. The high intensity IR flux rapidly photo-radiation conditions the wafers so that diffusion occurs >3× faster than conventional high-mass thermal furnaces.

Abstract: Multi-lane, side-by-side, independently driven transport systems particularly useful for transfer on conveyor belts or finger/chains of thin work pieces, such as silicon wafers, through processing equipment for converting the wafers into solar cells, including UV pre-treaters, dopers, dryers, diffusion furnaces and metallization furnaces. The inventive multi-lane transport systems may employ wire mesh belts having a flying bridge wafer support system comprising longitudinally spaced carrier wire elements that support the wafers at their side edges at only point contacts, by means of opposed, inwardly inclined, downwardly slanted segments or wings. Alternately, finger drives comprising spaced-apart chains having inwardly projecting fingers may be used for transport of the wafers by side edge contact. Friction or sprocket drives having tensioner assemblies associa-ted therewith are used to move the transport belts or finger chains through the furnace zones.

Abstract: Silicon wafer processing system, apparatus and method of doping silicon wafers with hot concentrated acid dopant compositions for forming p-n junction and back contact layers during processing into PV solar cells. Highly concentrated acid dopant is atomized with pressurized gas and heated in the range of 80-200° C., then introduced into a concentrated acid vapor processing chamber to apply vapor over 1.5-6 min to wafers moving horizontally on a multi-lane conveyor system through the processing chamber. The wafers are dried and forwarded to a diffusion furnace. An optional UV pre-treatment assembly pre-conditions the wafers with UV radiation prior to dopant application, and doped wafers may be post-treated in a UV treatment module before being fired. The wafers may be cooled in the processing chamber. Post-firing, the wafers exhibit excellent sheet resistance in the 60-95 ?/sq range, and are highly uniform across the wafers and wafer-to-wafer.

Abstract: A new class of work-piece conveyors, comprising zero-mass, shadow-less transport systems, with a drive having a pair of parallel, laterally spaced, movable chains defining a processing path, with fingers projecting transversely toward the process path centerline. The gap between fingers eliminates conveyor tube/rod supports, improving wafer quality and conserving energy. Implementations include wire chain, band and roller chain transports to which fingers are secured. Fingers are angled down so that the intersection of the bottom and side edges of the work-piece make only point contacts with each finger. A pair of finger chains implement a single lane drive; adding center bilateral finger drive chains with oppositely pointing fingers implement a multi-lane system. The inventive method includes individually configurable processing temperature profiles in side-by-side lanes, on a zone-by-zone, upper and lower half basis for broad processing flexibility.

Abstract: Multi-zone, solar cell diffusion furnaces having a plurality of radiant element (SiC) or/and high intensity IR lamp heated process zones, including baffle, ramp-up, firing, soaking and cooling zone(s). The transport of solar cell wafers, e.g., silicon, selenium, germanium or gallium-based solar cell wafers, through the furnace is implemented by use of an ultra low-mass, wafer transport system comprising laterally spaced shielded metal bands or chains carrying non-rotating alumina tubes suspended on wires between them. The wafers rest on raised circumferential standoffs spaced laterally along the alumina tubes, which reduces contamination. The bands or chains are driven synchronously at ultra-low tension by a pin drive roller or sprocket at either the inlet or outlet end of the furnace, with appropriate tensioning systems disposed in the return path. The high intensity IR flux rapidly photo-radiation conditions the wafers so that diffusion occurs >3× faster than conventional high-mass thermal furnaces.

Abstract: Multi-zone, solar cell diffusion furnaces having a plurality of radiant element (SiC) or/and high intensity IR lamp heated process zones, including baffle, ramp-up, firing, soaking and cooling zone(s). The transport of solar cell wafers, e.g., silicon, selenium, germanium or gallium-based solar cell wafers, through the furnace is implemented by use of an ultra low-mass, wafer transport system comprising laterally spaced shielded metal bands or chains carrying non-rotating alumina tubes suspended on wires between them. The wafers rest on raised circumferential standoffs spaced laterally along the alumina tubes, which reduces contamination. The bands or chains are driven synchronously at ultra-low tension by a pin drive roller or sprocket at either the inlet or outlet end of the furnace, with appropriate tensioning systems disposed in the return path. The high intensity IR flux rapidly photo-radiation conditions the wafers so that diffusion occurs >3× faster than conventional high-mass thermal furnaces.

Abstract: High reflectance element IR lamp module and method of firing multi-zone IR furnaces for solar cell processing comprising lamps disposed backed by a flat or configured plate of ultra-high reflectance ceramic material. Optionally, the high reflectance plate can be configured with ripples or grooves to isolate each lamp from adjacent lamps in the process zone. Furnace cooling air is exhausted and recycled upstream for energy conservation. Lamp spacing can be varied and power to each lamp individually controlled to provide infinite control of temperature profile in each heating zone. The high reflectance element may be constructed of dense ceramic fiber board, and then coated with high reflectance ceramic composition, and baked or fired to form the finished element.

Abstract: Multi-zone, solar cell diffusion furnaces having a plurality of radiant element (SiC) or/and high intensity IR lamp heated process zones, including baffle, ramp-up, firing, soaking and cooling zone(s). The transport of solar cell wafers, e.g., silicon, selenium, germanium or gallium-based solar cell wafers, through the furnace is implemented by use of an ultra low-mass, wafer transport system comprising laterally spaced shielded metal bands or chains carrying non-rotating alumina tubes suspended on wires between them. The wafers rest on raised circumferential standoffs spaced laterally along the alumina tubes, which reduces contamination. The bands or chains are driven synchronously at ultra-low tension by a pin drive roller or sprocket at either the inlet or outlet end of the furnace, with appropriate tensioning systems disposed in the return path. The high intensity IR flux rapidly photo-radiation conditions the wafers so that diffusion occurs >3× faster than conventional high-mass thermal furnaces.

Abstract: Isolation IR heat lamp module and method of firing multi-zone IR furnaces for solar cell processing comprising lamps disposed in individual parallel channels in a reflector/insulator body to provide a cooling air channel surrounding each tube; the channels are covered with IR-transmissive plate material to isolate each lamp from adjacent lamps and the process zone. Cooling air is exhausted and recycled upstream for energy conservation. Lamp spacing can be varied and power to each lamp individually controlled to provide infinite control of temperature profile in each heating zone. For a spike zone, and in combination with downstream quench control and annealing zones, steep heating and cooling curves with very short dwell (sharp) peak temperature profiles permit faster throughput due to operation of the lampsm at essentially 100% rated capacity, at a 2× or greater heating and throughput rate without compromising lamp life, while producing solar cells with improved output efficiency.

Abstract: Isolation IR heat lamp module and method of firing multi-zone IR furnaces for solar cell processing comprising lamps disposed in individual parallel channels in a reflector/insulator body to provide a cooling air channel surrounding each tube; the channels are covered with IR-transmissive plate material to isolate each lamp from adjacent lamps and the process zone. Cooling air is exhausted and recycled upstream for energy conservation. Lamp spacing can be varied and power to each lamp individually controlled to provide infinite control of temperature profile in each heating zone. For a spike zone, and in combination with downstream quench control and annealing zones, steep heating and cooling curves with very short dwell (sharp) peak temperature profiles permit faster throughput due to operation of the lampsm at essentially 100% rated capacity, at a 2× or greater heating and throughput rate without compromising lamp life, while producing solar cells with improved output efficiency.

Abstract: A heated fuel line for preventing solidifying of fuel in the fuel line of an engine in extremely low-temperature environments includes an electrical resistance heating element positioned directly inside the fuel line. A thin, tape-like heating element is preferably employed through the length of the fuel line between the tank and the connection to a fuel filter near the engine. Lead wires extend from the downstream end of the heating element through a fitting which carries the leads to the exterior of the fuel line. The heating element is preferably of a type including a pair of spaced conductor wires covered with and separated by a sheath of a radiation cross-linked polymer which has the property of becoming more conductive in lower temperatures and less conductive in higher temperatures. At lower temperatures, where heating of the fuel in the line is most needed, the element therefore produces the greatest amount of heat.