Alignment targets having enhanced contrast

Details Alignment targets having enhanced contrast Alignment targets having enhanced contrast

1997-02-18

1999-04-27

Saadat, Mahshid

Active solid-state devices (e.g., transistors, solid-state diode

Alignment marks

438401, 438975, H01L 23544

Patent

active

058982272

ABSTRACT:
Various alignment targets are disclosed having improved visibility. A first embodiment includes an alignment target having a first reflective layer of a first material such as tungsten having a roughened surface; and a second layer of a second material, such as aluminum, deposited on the first layer. The surface of the second layer is roughened by conforming with the roughened surface of the first layer to provide both layers with a uniform optical layers. The edges of the second layer provides an optical signal to contrast between the two layers for alignment. A second embodiment includes an alignment target with a plurality of parallel elongated trenches; a first material fills each of the trenches; and a patterned layer of a second material is deposited on top the elongated trenches and the insulator layer.

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patent: 5663099 (1997-09-01), Okabe et al.
patent: 5665645 (1997-09-01), Kinugawa

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