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Contamination Particle Detection and Location

IP.com Disclosure Number: IPCOM000086438D
Original Publication Date: 1976-Sep-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

McGough, LJ: AUTHOR

Abstract

Contamination particles on a mask or wafer are detected by illuminating the mask or wafer at a very shallow angle (approximately 1 degrees -4 degrees from the surface of the mask or wafer). This indicates the presence of a certain number of particles but not in relation to the device geometry.

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Contamination Particle Detection and Location

Contamination particles on a mask or wafer are detected by illuminating the mask or wafer at a very shallow angle (approximately 1 degrees -4 degrees from the surface of the mask or wafer). This indicates the presence of a certain number of particles but not in relation to the device geometry.

The contamination particles and device geometry can be seen simultaneously by a particle detection system which illuminates the wafer from above and the mask from below, while the top surface of each is being illuminated from two directions by shallow angle contamination particle illumination.

This detection system locates contamination particles in relation to the device geometry to determine if the particle is located in a critical area of the device, or to determine particle location for further analysis or measurement.

The system is made more efficient by the use of mirrors which reflect the light back to the wafer or mask, as shown in the figure. Wafer 1 is illuminated with shallow angle illumination from two directions by light sources 2 and 3 which are located at an angle of about 90 degrees. Mirrors 4 and 5 reflect the light back to the wafer surface. The mask is similarly illuminated by another pair of light sources and mirrors.

This method of illumination also illuminates the contamination particles from all sides as well as slightly from the top, which causes the particles to be more easily detected and yields a more...