Browse Prior Art Database

Improved Method of Exposing Resists With Lasers

IP.com Disclosure Number: IPCOM000062741D
Original Publication Date: 1986-Nov-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Fredericks, EC: AUTHOR [+3]

Abstract

In semiconductor processing, it is desirable to use near monochromatic light, such as lasers, for defining sub-micron ima In other processing steps, it is desirable to have a more incoherent exposure source for defining sloped profiles, such as for metal lift-off or contact formation. This invention provides an optical system that can be tailored to provide the type of light desired for a specific process level.

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Improved Method of Exposing Resists With Lasers

In semiconductor processing, it is desirable to use near monochromatic light, such as lasers, for defining sub-micron ima In other processing steps, it is desirable to have a more incoherent exposure source for defining sloped profiles, such as for metal lift-off or contact formation. This invention provides an optical system that can be tailored to provide the type of light desired for a specific process level.

Referring to the figure, a laser 10 emits radiation having a desired wavelength. Variable density reflecting element 12 allows 100% reflection or 100% transmission, thereby selecting the coherent path or the incoherent path, or a mixture thereof. In 100% reflection mode, the light is deflected by element 12 and passes through optics 14 and pin hole filter 16. Before striking the condenser 18, the light passes through a second variable density reflecting element 20 which is coupled to the first element 12 so that when element 12 is at 100% reflectance, element 20 is at 0% reflectance. After passing through the condenser 18, the light is projected through mask 22 onto wafer 24.

When incoherent light is desired, element 12 is adjusted for 100% transmission. The light then strikes mirror 26 before passing through a diffuser
28. Finally, the light is reflected off mirror 30, which directs the beam towards the variable density reflecting element 20. At that point, the light is reflected through the condenser 18 as...