Browse Prior Art Database

Protective Mold Etching

IP.com Disclosure Number: IPCOM000079674D
Original Publication Date: 1973-Aug-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Baran, EF: AUTHOR [+3]

Abstract

The described etching process reduces the undercutting effect experienced in wet etching films. The process is most applicable to materials not easily plated, or where nonplated films are desired. Tungsten and molybdenum are typical examples.

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Protective Mold Etching

The described etching process reduces the undercutting effect experienced in wet etching films. The process is most applicable to materials not easily plated, or where nonplated films are desired. Tungsten and molybdenum are typical examples.

The process initially employs a "mold" made of a material easily plated to the finished line requirements, as depicted in Fig. A. Typically, copper may be employed since it can be controlled to thicknesses of 4 Mu or greater, and widths to less than 1 mil. In this regard, a photoresist may be applied, developed and a mold of copper plated up as shown by 1 in Fig. A.

After the copper mold has been formed, the desired line material, such as tungsten, is deposited upon the copper mold, as shown by 2 in Fig. B. As can be seen, the lines of the copper mold act to delimit the tungsten therebetween, as shown for example at 2A, to the desired line widths of tungsten. Thereafter, a photoresist may be applied and developed, and a further copper mold plated up over the desired tungsten lines, as shown by 3 in Fig. C.

As shown in Fig. D, the undesired tungsten may then be etched away, leaving the copper mold and desired tungsten lines. Thereafter, the copper mold may be etched away leaving only the desired tungsten lines, as shown in Fig. E. It can be seen, that during the tungsten etch step of Fig. D, any undesirable undercutting of the desired tungsten line 1 is precluded, until essentially all of the undesired...