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Browse Prior Art Database

Etching Holes In Metal Masks

IP.com Disclosure Number: IPCOM000097285D
Original Publication Date: 1962-Sep-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Ofca, EJ: AUTHOR [+2]

Abstract

Apertured metal masks are employed in the manufacture of semiconductor devices such as transistors. Such masks can be about 1 inch x 1 inch x 0. 001 inch in size and can be made from molybdenum foil. Several hundred holes having dimensions of about 1. 5 x 2. 7 mils may be needed in a mask.

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Etching Holes In Metal Masks

Apertured metal masks are employed in the manufacture of semiconductor devices such as transistors. Such masks can be about 1 inch x 1 inch x 0. 001 inch in size and can be made from molybdenum foil. Several hundred holes having dimensions of about 1. 5 x 2. 7 mils may be needed in a mask.

Both surfaces of an imperforate foil are covered uniformly with a chemically resistant, photo sensitive coating. This bears a pattern representative of the holes to be etched in the foil. After developing and treating that coating, there exist several hundred tiny exposed areas 10 of metal on both sides of the foil 11
(A).

Next, the coated foil is clamped in a rotary holder 12 (B).

The holder is mounted in grooved rollers 13 and in vertical guideways 14 of etching chamber 15. The holder is centrally located between a pair of spray nozzles 16 (C). These simultaneously direct uniform fan shaped sprays 17 of an etching solution at both sides of foil 11.

The pressure range of the spray is 4-16 psi and the temperature of the solution is from 22-30 degrees C. The distance between each spray nozzle and its foil surface is 4 inches +- 0.5 inches.

The following etching solutions are employed on molybdenum:

Minimum Maximum Optimum

Potassium Ferricyanide 90g 140g 115g Sodium Hydroxide 12g 22g 13g Water 1000ml 1000ml 1000ml Wetting Agent (optional) 3 drops 10 drops 5 drops

One of the rollers 13 is driven by a shaft 18 and rotates the holder 12. Thus, sprays 17...