Target acquisition and overlay metrology based on two diffracted orders imaging

US7528953B2 · kind B2 · utility

Assignee

• KLA-Tencor Technologies Corp. · US

Inventors

• Aviv Frommer · Kiryat Shmona, IL
• Vladimir Levinski · Milpitas, US
• Mark D. Smith · Austin, US
• Jeffrey Byers · Rockdale, US
• Chris Mack · Austin, US
• Michael Adel · Zichron Ya'akov, IL

Key dates

• Filing date: Feb 27, 2006
• Grant date: May 5, 2009
• Expiry date: Sep 18, 2026

Classification

• Technology area (CPC G): Physics
• CPC primary: G03F9/7088
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

In one embodiment, a system includes a beam generator for directing at least one incident beam having a wavelength λ towards a periodic target having structures with a specific pitch p. A plurality of output beams are scattered from the periodic target in response to the at least one incident beam. The system further includes an imaging lens system for passing only a first and a second output beam from the target. The imaging system is adapted such that the angular separation between the captured beams, λ, and the pitch are selected to cause the first and second output beams to form a sinusoidal image. The system also includes a sensor for imaging the sinusoidal image or images, and a controller for causing the beam generator to direct the at least one incident beam towards the periodic target or targets, and for analyzing the sinusoidal image or images.