Abstract: A solder reflow convection furnace employing flux collection and heating to minimize flux and solvent build up and gas densification to reduce input gas flow is disclosed. As solder melts in the furnace, an effluent of vaporized flux is driven off and can condense on cooler components. To minimize such condensation, the gas is directed through a cooling system in which the flux condenses, and the cooled, cleaned gas is directed into the furnace's product cooling section. In another embodiment, in which the gas in the furnace is recirculated, a cooling coil is located upstream of the recirculating gas mover to heat the primary gas. The vaporized flux condenses on the cooling coil, which can be readily removed and replaced. In another aspect of the invention, when the furnace employs a gas amplifier, the recirculating gas is cooled prior to reentry into the heating chamber, which increases its density and removes flux by condensation.

Abstract: A walking beam furnace is provided for moving a work product through a high temperature (1,600.degree. C.) furnace at high speed in large horizontal increments. A monolithic walking beam mechanism, including an array of parallel beams and support therefor, fabricated entirely from a refractory material such as silicon carbide (SIC), provides a movable, planar hearth surface. A fixed array of longitudinally disposed, spaced-apart hearth members, provides a fixed, planar hearth surface. The beams are narrower than the spacing between the hearth members to permit passage of the ,array of beams in coplanar alignment with the fixed hearth members through the spacing between the hearth members.

Abstract: A longitudinally extending cross-flow liner within a longitudinally extending cylindrical reaction vessel cooperates with at least one longitudinally extending gas injector within the cross-flow liner to provide transversely flowing gas across the surfaces of vertically oriented semiconductor wafers in such a way as to substantially eliminate both depletion phenomenon and downstream wafer pollution caused from particulates, unreacted reactant gas, and other contaminants and to provide uniformly coated wafers in a batch and repeatability batch to batch.

Abstract: A high temperature electrical resistance heater in which an electrically resistive strip is supported so that the strip may freely expand and contract and substantially all of the strip may directly radiate to provide maximum heat transport therefrom. The strip is carried in a serpentine configuration by support blocks which are arranged in abutting relation in spaced, parallel rows. Each block includes a lower portion embedded in a ceramic base and an upper portion extending above the base. The upper portion includes a structural portion which encircles minor portions of the strip to carry it spaced above the base to allow substantially unimpeded radiation from the strip and free strip expansion. Anchors securely hold the support blocks embedded within the base.

Abstract: One fast cool-down furnace embodiment discloses a double wall in the interspace of which a cooling air stream is flowable to provide fast cool-down of a load of wafers. The double wall embodiment is retrofittable on existing diffusion furnaces, and includes a cylindrical member aligned in concentric relation with the diffusion tube by combination plenum defining and supporting manifolds. In a second embodiment, the fast cool-down furnace includes a reaction vessel and a heating core relatively movable relative to each other in such a way that in a fast cool-down condition the core and reaction vessel are spaced apart. Cooling tubes are embedded in the movable core. Fans or other aids to cooling are provided. Operation is either in a controlled cool-down mode or in a quick quench mode.

Abstract: One fast cool-down furnace embodiment discloses a double wall in the interspace of which a cooling air stream is flowable to provide fast cool-down of a load of wafers. The double wall embodiment is retrofittable on existing diffusion furnace, and includes a cylindrical member aligned in concentric relation with the diffusion tube by combination plenum defining and supporting manifolds. In a second embodiment, the fast cool-down furnace includes a reaction vessel and a heating core relatively movable relative to each other in such a way that in a fast cool-down condition the core and reaction vessel are spaced apart. Cooling tubes are embedded in the movable core. Fans or other aids to cooling are provided. Operation is either in a controlled cool-down mode or in a quick quench mode.

Abstract: A generally cylindrical, self-supporting, unitary high-temperature electrical resistance heating element is disclosed. The heating element is composed of a wire grate formed from a plurality of electrically continuous and intersecting wire segments made of electrical resistance wire. The configuration of the heating element can be maintained by a plurality of circular rings made of conductive wire and placed orthogonally at intermediate points along the length of the heating element and which can serve as electrical terminals. The resulting heating element offers advantages of low weight, high efficiency and minimal thermal inertia, and provides a unitary heater structure which provides the ability to have different temperature zones along its length.