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3 September 1998 Influence of topographical variations on reliable via and contact formation
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The continuing trend toward smaller device feature sizes and the associated use of high numerical aperture lenses has decreased the depth-of-focus budget available to resolve critical vias. This problem is aggravated by localized topographical variations in device structure, such as double poly capacitors or EEPROM structures, which can induce excessive vertical variation in via height. Such variation places severe demands on the available focus beget, and can result in localized regions of the die experiencing incompletely formed via structures. Topographical variations in device structure can also induce highly isolated and incompletely formed active area contacts as a result of localized resist pooling. In this situation, the topography usually consists of large double poly structures which surround an active area contact, and induce a dramatic variation in resist thickness over the contact area. This can lead to incompletely formed active area contacts and device failure. In both cases, topography play has a key role in inducing these failures mechanisms. This paper presents two case studies: one involving incompletely formed vias due to topographically induced focus failure, and the other a case study involving a EEPROM contact failure caused by topographically induced resists pooling.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Jerry T. Healey and Scott E. Rubel "Influence of topographical variations on reliable via and contact formation", Proc. SPIE 3507, Process, Equipment, and Materials Control in Integrated Circuit Manufacturing IV, (3 September 1998);

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