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Improved E-Beam Registration for Thick Films

IP.com Disclosure Number: IPCOM000048351D
Original Publication Date: 1982-Jan-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Bartush, TA: AUTHOR

Abstract

Conventionally, E-beam registration is performed by searching for a registration mark which is buried beneath a composite film (resist, resin glass, underlay) whose thickness is governed by the particular process being practiced. There exist well-defined cutoff points for the maximum film thickness through which registration can take place. This limit is typically 3.5 microns to 4.0 microns of composite lift off materials.

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Improved E-Beam Registration for Thick Films

Conventionally, E-beam registration is performed by searching for a registration mark which is buried beneath a composite film (resist, resin glass, underlay) whose thickness is governed by the particular process being practiced. There exist well-defined cutoff points for the maximum film thickness through which registration can take place. This limit is typically 3.5 microns to 4.0 microns of composite lift off materials.

This technique describes a sequence of process steps which will allow for registration limits to be increased by at least 2.0 microns.

The sequence of steps begins with a specially constructed optical mask which has no product data on it, but does have the E-beam registration marks defined. Wafers are coated with the lift-off structure which allows for at least a
2.0 micron thick metal deposition. Exposure is done optically since no critical dimensions are present, and lift-off will produce an E-beam registration mark which is 2.0 microns high. The wafers are now ready to enter the personality sector for processing of multilayer metallization (MLM).

In MLM processing, the height of the stud via connecting metal levels has normally been limited to the E-beam registration capability. With afers prepared as above, the cross section would look as shown in the drawing. Note that the thickness of the resist composite has been substantially reduced by the special metal deposition at the registration marks....