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Quality AlignmentTargets for Thick Sputtered Film Deposition Disclosure Number: IPCOM000010454D
Original Publication Date: 2002-Dec-03
Included in the Prior Art Database: 2002-Dec-03
Document File: 2 page(s) / 41K

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Quality alignment marks and overlay test sites are crucial for pattern recognition in photolithographic steppers and overlay metrology systems. Producing quality targets in thick sputtered materials is challenging due to the type of edges that can occur over the underlying layer. This disclosure describes a method to tackle these challenges.

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Quality AlignmentTargets for Thick Sputtered Film Deposition

Disclosed is a design for producing quality alignment marks and overlay test sites within thick sputtered materials. Past methods have produced poor quality targets due to the rounded edges that were produced. The rounded edges, as seen in Fig 1, make pattern recognition difficult in photolithographic steppers as well as overlay metrology systems.

                        top cross-section view view


Figure 1. Top and Side view of previous target design

UnderlyingTarget formed with sharp edges

Rounded edges formed after thick film deposition

The targets presented in this disclosure can produce quality target edges within the thick film and therefore significantly improve pattern recognition. Fig 2 illustrates the improved target design. From Fig. 1, the target design is formed by two squares of the underlaying material using the large spacing between the squares as the target. When the thick film is deposited over the single box, rounded edges are formed over the underlying material. Instead of using the opening between the underlying material boxes, move the underlying material close together forming a trench, as seen in Fig 2. A rounded edge will form over the underlying material edge, leaving an opening within the trench of the underlying layer. The width of this opening becomes a function of the underlying material spacing, thickness of the underlying layer, and the thickness of the deposited film.


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