Low volume dispense unit and method of using

#This application relates generally to a low volume dispense unit. More specifically, this application relates to a low volume dispense unit for filtering and dispensing chemical solutions used in the manufacture of semiconductors on a lab or development scale.

#“Lithography” literally means stone writing, however the contemporary meaning is to produce a three dimensional image. “Photolithography” is a term that emerges with the discovery of photosensitive compounds used to define patterns on a printed circuit board. “Micro lithography” is a term used to describe small features using photolithography or photosensitive compounds for the manufacture of integrated circuits.

#Semiconductors are manufactured using a photolithographic process. The micro lithographic process is the last step and goal in the formation of relief images. Photolithographic processes apply chemical solutions, such as photo-resist, antireflective coatings (ARC) and developer solutions, onto a surface of a semiconductor. The chemical solution is applied at the recommended film thickness to a wafer. For example, after the application of photo-resist onto the wafer, an image from a template, mask or reticule (hereinafter mask) containing clear and opaque regions is transferred into the photosensitive coating on the wafer surface using a projection system. The clear and opaque regions on the mask) correspond to the desired circuit pattern.

#FIG. 1 is a schematic diagram of a photolithography process;

#FIG. 2 is a front view of an exemplary embodiment of a dispensing unit;

#FIG. 3 is a side view of an exemplary embodiment of a filter in the dispensing unit of FIG. 2;

#Referring now to FIG. 2, an exemplary embodiment of a low volume dispense unit 26 is illustrated. Dispense unit 26 is adapted to dispense chemical solutions such as those used in the manufacture of semiconductors in conjunction with existing coat/develop track machines 10. Dispensing unit 26 is mounted on a support or stand 28. Stand 28 is adapted to be secured, for example, on machine 10 such that it's dispense nozzles extend into the machine at the appropriate coat bowl station. Dispense unit 26 dispenses chemical solutions in low volumes and with high accuracy, while generating little or no particulate matter in the chemical solution. Moreover, unit 26 is adapted to provide low overall hold-up or residual volume such that waste of the chemical solution is minimized.

#Unit 26 includes a liquid reservoir 30 for storing one or more charges of chemical solution. Since the chemical solutions are expensive, reservoir 30 is a low volume reservoir, typically about 30 cubic centimeters (cc). Preferably, reservoir 30 is a pneumatic syringe. Reservoir 30 is in fluid communication with a pneumatic valve assembly 32 by means of a conduit 34. Valve assembly 32 is in fluid communication with a dispense nozzle 36 by means of a conduit 38. Thus a flow path 40 is defined through unit 26, namely from reservoir 30 through conduit 34 to valve assembly 32, and from the valve assembly through conduit 38 to nozzle 36. Pneumatic valve assembly 32 and conduits 34 and 38, similar to reservoir 30, have a low hold-up volume, namely about 5 ml.

#The chemical solutions to be dispensed by dispensing unit 26 are often corrosive in nature. Thus, flow path 40 is made of materials effective to withstand the corrosive nature of the chemical solution. For example, reservoir 30, conduit 34, and conduit 38 are preferably are in preferably a polyethylene-based materials, such as poly tetrafluoro ethylene(“PTFE” or Teflon™, available from DuPont), while valve assembly 32 and nozzle 36 are made from stainless steel or fluoropolymer-based materials, such as Teflon™ PTFE.