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Endpoint Detection by Change in Reflectance During Laser Repair of Thin Film Metallurgy

IP.com Disclosure Number: IPCOM000062780D
Original Publication Date: 1986-Dec-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Smith, KA: AUTHOR

Abstract

A method has been developed for detecting the endpoint when multilayer semiconductor devices are repaired by means of a laser. Introduction of a blue-green light onto the metallurgy surface provides the necessary contrast to determine when the repair has been completed.

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Endpoint Detection by Change in Reflectance During Laser Repair of Thin Film Metallurgy

A method has been developed for detecting the endpoint when multilayer semiconductor devices are repaired by means of a laser. Introduction of a blue- green light onto the metallurgy surface provides the necessary contrast to determine when the repair has been completed.

In conventional procedures, which use normal white lighting, it is difficult to determine when the line being repaired has been cleared of its polyimide (PI) passivation layer. This is because both the PI and the metal line reflect the white light with there not being enough contrast between the two to easily determine endpoint. Introduction of a blue-green light onto the surface during etching is a viable means of determining endpoint. The PI absorbs the blue-green light and the metal line reflects the blue-green light thereby providing a sharp contrast. When the laser has etched through the PI to the metal surface, the reflection from the metal shows bright green indicating the PI has cleared and the etching is complete.

In laser repair techniques the laser has its beam Fig. 1-1 directed through a mask 2 and a series of lenses 3 onto the substrate 4 being repaired. The blue- light required in the new procedure is directed from a xenon arc lamp 5 through blue-green filters 6 and through an arrangement of mirrors 7 and lenses 8 so as to impinge upon the substrate. Overetching and shorting between metallurgies ...