Abstract: A bath in which articles are processed by immersion in hot liquid chemicals has a chemical receptacle seated in a casing. Wetting of internal components in the casing, such as heating elements and thermal insulation, is prevented by a seal between the receptacle and the rim of the casing. The otherwise exposed seal is isolated from the external environment of the bath by a barrier of flowing water. The water flow shields the sealing material from corrosive chemical drips and fumes and also has a cooling effect which decreases thermal expansion of components in the region of the seal and thereby reduces structural stresses.

Abstract: A chemical bath for immersing articles such as integrated circuit wafers in a hot flow of etchant or other liquid includes a liquid receptacle with a first compartment for receiving the articles and a second compartment which acts as sump and further includes a trough which channels overflow from the first compartment into the sump. A pump recirculates liquid from the sump back to the first compartment. The receptacle is supported by a casing in which the lower region of the receptacle is situated. The casing in which the lower region of the receptacle is situated. The casing is sealed by a flange on the receptacle which overlays a rim member on the casing and by sealing material situated between the rim member and the underside of the flange. The flange is located below the trough in vertically spaced apart relationship with the trough. This inhibits direct heat transfer from the trough to the seal and thereby enhances seal durability.

Abstract: A chemical bath in which batches of integrated circuit wafers or other articles are immersed in hot liquid chemical during manufacture has a processing vessel, an adjacent sump vessel and a trough which carries overflow from the processing vessel to the sump vessel. A pump continuously recirculates liquid from the sump vessel to the processing vessel through a filter. A continuous inflow of liquid is received from a liquid chemical source and an intermittent outflow occurs through an outlet at an upper region of the sump vessel. The liquid chemical source may, for example, supply make-up fluid or be a reprocessor that repurifies the outflow from the sump vessel. The storage capacity of the sump vessel below the outlet is greater than that needed to contain the volume of liquid that is displaced in the processing vessel by the batch of wafers.

Abstract: A non-invasive liquid level sensor assembly includes a pair of conductive band electrodes oriented in parallel, narrowly spaced relationship and disposed so that the gap between the electrodes corresponds to the liquid surface level to be detected. The electrodes are secured to the outer surface of a liquid container, and connected to a capacitive detector device which measures the change in electrical capacity between the conductors as the liquid rises or falls past the level of the gap between the electrodes. A shield electrode is also provided, disposed outwardly of and concavely about the sensing electrodes to eliminate sensitivity to masses outside of the container. In one embodiment the electrodes are secured with a sealed, arcuate housing which is adapted to be permanently or temporarily secured to the exterior of a liquid container by adhesive, removable straps, or the like.