System for cleaning residual paste from a mask

• US 6,032,683 A
• Filed: 02/26/1999
• Issued: 03/07/2000
• Est. Priority Date: 02/09/1998
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Cropp, Michael E., Knickerbocker, John U., Casey, Jon A., Sullivan, Robert J., Sachdev, Krishna G., Long, David C., Pomerantz, Glenn A., Harmuth, John F., Mackin, Daniel S., Speed, David E., Sullivan, Candace A., Utter, James C., DiAngelo, Donald W., Tripp, Bruce E.
• Primary Examiner(s): Gulakowski, Randy
• Assistant Examiner(s): Lee, Paul J.
• Application Number:
  US09/258,970
• Time in Patent Office: 375 Days
• Field of Search: 134/61, 134/95.1, 134/133, 134/200, 134/64 R, 134/122 R, 134/199, 15/308, 15/302, 15/303, 15/310, 15/77
• US Class Current: 134/199
• CPC Class Codes: B08B 3/02 Cleaning by the force of jets or sprays
• CPC Class Codes: B41F 35/005 for flat screens
• CPC Class Codes: B41P 2235/26 Spraying devices
• CPC Class Codes: B41P 2235/50 Selection of materials or products for cleaning
• CPC Class Codes: G03F 1/82 Auxiliary processes, e.g. cleaning or inspecting
• CPC Class Codes: G03F 7/12 Production of screen printing forms or similar printing forms, e.g. stencils
• CPC Class Codes: G03F 7/425 containing mineral alkaline compounds; containing organic basic compounds, e.g. quaternary ammonium compounds; containing heterocyclic basic compounds containing nitrogen
• CPC Class Codes: H01L 21/67028 for cleaning followed by drying, rinsing, stripping, blasting or the like
• CPC Class Codes: H05K 3/1216 by screen printing or stencil printing
• CPC Class Codes: H05K 3/26 Cleaning or polishing of the conductive pattern

Abstract

A cleaning method and related apparatus for cleaning semiconductor screening masks using an aqueous alkali detergent solution applied under high pressure simultaneously from both sides of the mask, followed by a drying step that uses air knives to blow off the mask surface any residual cleaner solution.

Claims

1. Apparatus for cleaning residual paste from a mask, the apparatus comprising:

A) a source of an alkali detergent;

B) a wash chamber and within said chamber;

1) at least one pair of primary opposing liquid spray nozzles movably mounted within the wash chamber;

2) a drive for moving said spray nozzles in tandem in a vertical path within said chamber;

C) said opposing spray nozzles oriented to direct balanced front and back liquid streams of said alkali detergent toward each other at an angle of between about 40 and about 50 degrees to the vertical;

D) a pump connected to said source of alkali detergent and said at least one pair of opposing spray nozzles, said pump generating a pressure in the liquid streams of between 150 and 500 psi;

E) a drying chamber adjacent said wash chamber, comprising;

1) an air knife supplying two symmetrically opposing gaseous streams directed toward each other; and

F) a vertical mask support attached to a transport in said wash and drying chambers located so as to support and transport a mask along a path substantially centered between said opposing liquid spray nozzles and said opposing gaseous streams.

2. Apparatus according to claim 1 wherein said liquid streams are in the form of liquid jets.

3. Apparatus according to claim 1 wherein the balanced front and back liquid streams are a first set of balanced front and back liquid streams and there is at least one secondary pair of spray nozzles to direct a second set of balanced front and back liquid streams toward each other at an angle of between about 75 and about 85 degrees to the vertical, said secondary nozzles mounted adjacent said primary nozzles so that the second set of liquid streams impinges on the mask surface behind the first set of liquid streams.

4. Apparatus according to claim 1 further comprising a heater for raising the temperature of the liquid stream to between about 150°

F. and about 200°

F.

5. Apparatus according to claim 1 further comprising a heater for raising the temperature of the gaseous stream to above room temperature.

6. Apparatus according to claim 1 wherein the heater raises the gaseous stream temperature to about 200°

F.

7. The apparatus according to claim 1 wherein said alkali detergent consists essentially of an aqueous solution of one of sodium phosphate and sodium metasilicate in a molar concentration of between about 0.025 and 0.075.

8. The apparatus according to claim 7 wherein said alkali detergent further comprises a dispersant agent.