초록 ▼

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

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. This avoids pump starvation when liquid level is lowered in the processing vessel by removal of a batch of wafers and also assures that outflow matches inflow from the liquid chemical source over a period of time without requiring flow sensing devices, dynamic valving or other complications.

대표청구항 ▼

A chemical bath for immersing articles in a volume of liquid chemical comprising: a processing vessel for receiving said liquid chemical and said products, said processing vessel having a flow inlet and an upper edge across which liquid chemical may overflow from said processing vessel, an inclined

A chemical bath for immersing articles in a volume of liquid chemical comprising: a processing vessel for receiving said liquid chemical and said products, said processing vessel having a flow inlet and an upper edge across which liquid chemical may overflow from said processing vessel, an inclined trough positioned to receive said overflow from said processing vessel, a sump vessel positioned to receive said overflow from said trough and having upper and lower vertically spaced flow outlets, said sump vessel having a liquid storage region between said upper and lower outlets that has a Volume which exceeds the volume of liquid chemical that is displaced from said processing vessel as said products are immersed therein, pump and filter means for withdrawing liquid chemical through said lower outlet of said sump vessel and for recirculating the withdrawn liquid chemical to said processing vessel in filtered condition, and means for delivering an inflow of liquid chemical to said bath, whereby outflow of liquid chemical through said upper outlet of said sump vessel temporarily increases in response to immersion of said articles and is temporarily interrupted when said product is removed from said processing vessel but is substantially equivalent in volume to said inflow over a period of time.