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Browse Prior Art Database

Six Square Stacked Cell Layout

IP.com Disclosure Number: IPCOM000109320D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

DeBrosse, JK: AUTHOR [+2]

Abstract

Described is a layout for a six square, node over bitline, stacked capacitor, open bitline memory cell. The diagonal bitlines connect the cells in an open bitline configuration without interfering with cell node diffusion contacts. Diagonal active areas and bitline extension tabs are avoided. Compared to a conventional six square array, the new array uses chip space more efficiently, and the reliability of bitline contacts is enhanced. A rectangular array is preserved by proper routing of the bitlines.

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This is the abbreviated version, containing approximately 90% of the total text.

Six Square Stacked Cell Layout

       Described is a layout for a six square, node over
bitline, stacked capacitor, open bitline memory cell.  The diagonal
bitlines connect the cells in an open bitline configuration without
interfering with cell node diffusion contacts.  Diagonal active areas
and bitline extension tabs are avoided.  Compared to a conventional
six square array, the new array uses chip space more efficiently, and
the reliability of bitline contacts is enhanced.  A rectangular array
is preserved by proper routing of the bitlines.

      Several cells of the six square stacked layout are shown in
Fig. 1 where the cell pitch intervals are defined by the wordline and
bitline pitches.  Any row of cells is offset by one wordline interval
from each adjacent row.  Note that each diagonal bitline connects
cells that are staggered by two wordline pitch intervals and one
bitline pitch interval.  For this reason, the node diffusion/contact
and active areas of each cell can form a simple rectangular array.
Space that is not utilized in a conventional six square array can be
used to advantage.  First, all word lines are run on a regular pitch
as shown in Fig. 1.  Conventional six square arrays have an unused
gap between each pair of word lines. Second, Fig. 1 shows that
otherwise unused space between the bitlines may be used for fully
overlapped bitline contacts to enhance contact reliability.

      The expanded view of Fig. 2 shows that a rectangula...