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US 5,392,989 AGranted
Nozzle assembly for dispensing liquid
AssigneeSemiconductor Systems, Inc.
InventorRoy E. Hurtig
Life of this patent
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AssigneeSemiconductor Systems, Inc.
InventorRoy E. Hurtig
Estimating the term…
An improved nozzle assembly for dispensing liquid is disclosed. In a first embodiment of the invention, the liquid dispenser comprises a nozzle assembly with an expansive cavity at its dispensing end. When the flow of liquid in the dispenser is halted, a pocket of liquid formed inside the cavity ties the liquid in the nozzle to the liquid in a drop formed at the tip of the nozzle. Thus, when "suck-back" is applied, the drop is pulled into the cavity and up the nozzle, leaving at most a very small and stable amount of liquid inside the cavity. In a second embodiment of the invention, an inner nozzle tube extends beyond the end of an outer nozzle tube, creating an external annular recess which captures and holds a drop of liquid over the end of the nozzle. After suck-back, the drop is pulled up into the nozzle, leaving a small, stable amount of liquid in the annular recess.
A spin coating machine for applying photoresist to a semiconductor wafer, said machine comprising a nozzle assembly for dispensing a stream of solvent and a semiconductor wafer, said nozzle assembly having an expansive cavity at a dispensing end thereof, said nozzle assembly being located over said semiconductor wafer and being positioned such that said stream of solvent is oriented at an oblique angle to a top surface of said wafer, said expansive cavity being adapted to prevent a drop of said solvent from falling from said nozzle assembly onto said semiconductor wafer following an interruption of flow of said stream of solvent through said nozzle assembly.
A method dispensing liquid, said method comprising the steps of:
A spin coating machine for applying photoresist to a semiconductor wafer, said machine comprising a nozzle assembly for dispensing a stream of solvent and a semiconductor wafer, said nozzle assembly having an internal channel for said stream of said solvent, said nozzle assembly further having an external annular recess formed at an end of said channel, said annular recess surrounding said channel, said nozzle assembly being located over said semiconductor wafer and being positioned such that said stream of solvent is oriented at an oblique angle to a top surface of said wafer, said annular recess being adapted to prevent a drop of said solvent from falling from said nozzle assembly onto said semiconductor Wafer following an interruption of flow of said stream of solvent through said nozzle assembly.
Dependencies are inferred from the claim text.