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Lithographic Measurement Aid for VLSI Technology

IP.com Disclosure Number: IPCOM000041931D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 3 page(s) / 53K

Publishing Venue

IBM

Related People

Alcorn, CN: AUTHOR [+3]

Abstract

As device technology for VLSI (very large-scale integration) application approaches the one-micron region, in-line measurement for process and device parameter control of dimensions becomes increasingly important. A visual pattern test structure is disclosed which allows the rapid determination of over-etching or, alternately, of the excessive deposition of vacuum-evaporated structures during semiconductor manufacture. In Fig. 1, the pattern 1 and the pattern 5 form a measurement device for determining when an excessive deposition of vacuum-evaporated metal, for example, has taken place. The patterns 1 and 5 can be formed by correspondingly shaped apertures in the vacuum-evaporation mask. The pattern 1 has the projections 2, 3 and 4 which are spaced equidistantly along the pattern.

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Lithographic Measurement Aid for VLSI Technology

As device technology for VLSI (very large-scale integration) application approaches the one-micron region, in-line measurement for process and device parameter control of dimensions becomes increasingly important. A visual pattern test structure is disclosed which allows the rapid determination of over- etching or, alternately, of the excessive deposition of vacuum-evaporated structures during semiconductor manufacture. In Fig. 1, the pattern 1 and the pattern 5 form a measurement device for determining when an excessive deposition of vacuum-evaporated metal, for example, has taken place. The patterns 1 and 5 can be formed by correspondingly shaped apertures in the vacuum-evaporation mask. The pattern 1 has the projections 2, 3 and 4 which are spaced equidistantly along the pattern. The pattern 5 has the recessed portions 6, 7 and 8 which have their midpoints spaced periodically along the pattern. The midpoints for the projections 2, 3 and 4 are coincident with the midpoints of the recessed portions 6, 7 and 8. When a vacuum evaporation deposition step takes place, for example, when a metal structure is to be deposited on a semiconductor surface, a vacuum-evaporative mask is placed proximate to the semiconductor surface and the assembly positioned in a vacuum-evaporation chamber. A beam of atoms of the material which is desired to be deposited is rendered incident upon the mask, and those portions of the beam which project through the apertures in the mask deposit the material on the semiconductor. Since there is some solid angle over which the beam is projected, there will be some expansion of the resultant deposited image on the semiconductor surface with respect to the size of the aperture through which that beam traversed the mask. If the process deviates from the nominal dimension for the deposited structure, the transverse size of the structure increases. In the measurement pattern shown in Fig. 1, the projections 2, 3 and 4 for the pattern 1 will increase in width and the recessed portions 6, 7 and 8 of the pattern 5 will decrease in width. As can be seen from an examination of Fig. 1, when an excessive deposition takes place, the longitudinal sides of the projection 2 and the recessed portion 6 will no longer be aligned; however, the longitudinal sides of the projection 3 and the recessed portion 7 will come closer to alignm...