Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Multiple Independent Designs on a Mask that are Stepped Independently

IP.com Disclosure Number: IPCOM000113769D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 134K

Publishing Venue

IBM

Related People

Conway, JF: AUTHOR [+4]

Abstract

A method for placing multiple independent designs on a single reticle is disclosed. Each design can be manufactured independent of the other designs placed on the reticle, thus reducing the mask costs by a factor of the number of designs used.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Multiple Independent Designs on a Mask that are Stepped Independently

      A method for placing multiple independent designs on a single
reticle is disclosed.  Each design can be manufactured independent of
the other designs placed on the reticle, thus reducing the mask costs
by a factor of the number of designs used.

      Traditionally, reticles used to print semiconductor circuits
have a layout similar to reticles A or B, shown in the diagram below.
A single chip and kerf is positioned in the center of the reticle,
and surrounded by a frame and alignment marks.  The kerf defines the
dicing channel between each chip and may contain alignment and
measurement targets as well as test structures.  A barcode and/or
other nomenclature may also be placed outside the frame area for
reticle identification and management.  An alternative to a single
chip placement is to position multiple chips within the same field
(as shown in reticle B of the Figure) which can then be stepped
together on a wafer.

      A multiple number of reticles (one for each design layer) are
used to build a microcircuit device.  For a complex semiconductor
process, it is common to use fifteen to twenty different reticle
levels to build each part number designed.  With the ability to build
hundreds of different part numbers, the costs for masks can be quite
expensive.  A method is described to improve the utilization of the
reticle area and to reduce mask costs by placing multiple designs on
the same mask.  These designs can be independently used in the
manufacturing build process.

      Since most photolithography tools have a field size that can
support large chip sizes (on the order of 14mm x 14mm or larger),
smaller chip sizes can be grouped in order to better utilize the area
available on the reticle and the field size available in the
lithography tool.  For example, if the photolithographic field size
allows for a 20mm x 20mm chip image, then this same field can
accomodate four chip designs with images less than 10mm x 10mm.  In
practice, some area between the four chips can not be used to allow
for variations in the control and placement of the shutter blade
tooling.  Reticles C and D illustrate examples of this disclosure.

      In the diagram, reticle C shows four...