Browse Prior Art Database

MLM Process Simplification

IP.com Disclosure Number: IPCOM000119811D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 47K

Publishing Venue

IBM

Related People

Bartush, TA: AUTHOR [+4]

Abstract

The simplified MLM process described in this article eliminates two existing photoresist processing steps by the employment of silylated image resist as a lift-off barrier.

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MLM Process Simplification

      The simplified MLM process described in this article
eliminates two existing photoresist processing steps by the
employment of silylated image resist as a lift-off barrier.

      Standard MLM processing employs a layer (in the order of 3000
Angstroms thick) of resin glass, plasma nitride or plasma HMDS as a
lift-off barrier material.  This results in certain process
limitations, e.g., the inability to perform a CF4 cycle in RIE
(reactive ion etch) once the image has been transferred to the
barrier layer.  A thin insulating layer (composite insulator, buried
nitride, etc.) is sometimes placed under the lift-off structure to
overcome this difficulty, but this requires a separate masking step
to open this thin insulating layer, since it is unable to withstand
an extended CF4 RIE cycle without destroying the effectiveness of the
lift-off structure.

      The simplified MLM process here described avoids this problem
by having the image resist layer become the lift-off barrier through
silylation in HMTCS.  This layer is thick enough (usually in the
order of one micron or more)  to tolerate a CF4 RIE, making it
possible to consider processes employing composite materials, ones
inherently simpler than existing techniques.

      By way of example, two shallow via etches (through nitride) can
be eliminated by "burying" the nitride insulator under the sputtered
quartz.  This is accomplished by applying a blanket coat of nitride
...