Column transistor for semiconductor devices

Details Column transistor for semiconductor devices Column transistor for semiconductor devices

2000-12-29

2003-02-18

Meier, Stephen D. (Department: 2822)

Active solid-state devices (e.g., transistors, solid-state diode

Field effect device

Having insulated electrode

C257S369000

Reexamination Certificate

active

06521960

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improved column transistor configuration for use in semiconductor devices and, more particularly, to a column transistor in a semiconductor memory device, which transmits data on a bit line to a local data line or vice versa, having an improved and more efficient layout that allows increased device packing density.
2. Background of the Related Art
In semiconductor memory devices, the layout area of the sense amplifier usually depends on the size of a memory cell. For this reason, as the packing density of the memory device increases, the size of each memory cell is also decreased. This reduction in memory cell size requires that the size of the sense amplifier, which senses and amplifies the data from the memory cell, must be reduced in proportion to the size reduction of the memory cell. This reduction in the size of the sense amplifier lowers the driving performance of the sense amplifier as well. It is very important, however, to increase or at least maintain the operating frequency of the memory device to correspond to the increased operating frequencies obtained by advanced microprocessors.
The present invention provides a method for enhancing the driving performance of the sense amplifier as one of method for increasing the operating frequency of the memory device. The present invention also provides a method for providing a more efficient and effective layout for column transistors that are located between the bit lines and the local data lines to maximize the area of the sense amplifiers located between the bit lines.
FIG. 1
illustrates a circuit diagram of for conventional prior art column transistors, showing an example of the column transistors each with a width of 2.28 &mgr;m. A plurality of paired bit lines Biti, BitBi, Bitj, and BitBj are arranged in one direction, and a plurality of local data (bus) lines LDBi, LDBBi, LDBj, and LDBBj that are arranged in a generally perpendicular relation to the bit lines and connected to the column transistors (CT
1
~CT
8
). As shown, the data on the bit line Biti is transferred to the local data line LDBj through nodes N
1
and N
2
by the column transistors CT
1
and CT
5
, the data on the bit line Bitj is transferred to local data line LDBBj through nodes N
3
and N
4
by the column transistors CT
2
and CT
6
. Similarly the data on the bit line BitBi is transferred to the local data line LDBBi through nodes N
5
and N
6
by the column transistors CT
3
and CT
7
, and the data on the bit line BitBj is transferred to local data line LDBj through nodes N
7
and N
8
by the column transistors CT
4
and CT
8
. That is, there are data transmission paths of Biti→CT
1
→LDBi, Bitj→CT
2
→LDBBj, BitBi→CT
3
→LDBBi, and BitBj→CT
4
→LDBj.
The physical layout of such column transistors will be discussed with reference to
FIGS. 2 and 3
. Rectangular shaped active regions
10
are arranged on a semiconductor substrate in a regular check pattern with groups of four adjacent active regions
10
constituting one set of active regions. Each active region
10
is crossed twice by a gate electrode
12
, to produce an effective gate width of approximately twice the width of the active region (1.14 &mgr;m) for a total width of 2.28 &mgr;m. A single gate electrode
12
structure overlaps a set of active regions
10
to form a set of four column transistors, for example CT
1
~CT
4
. Bit lines
14
, Biti, Bitj, BitBi, and BitBj, are arranged sequentially in one direction across a set of active regions, with each bit line contacting a separate one of the adjacent active regions
10
via a pair of contacts BC. Local data lines
16
, LDBi, LDBBj, LDBBi, LDBj, are arranged in a direction perpendicular to the bit lines
14
and overlapping two of the adjacent active regions
10
. Each of the local data lines
16
is in contact with a separate one of the set of active regions
10
, and consequently a separate one of the column transistors CT
1
~CT
4
, via a local data line contact LDBC. The gate electrodes
12
for the column transistors CT
1
~CT
4
are connected by metal lines via metal contacts MC. This basic structure is then repeated for each set of active regions across the semiconductor device.
Because the prior art methods for forming the column transistor can not effectively reduce the area of the column transistors connected to the sense amplifiers, the prior art methods are generally unsuitable for improving the efficiency of the sense amplifier layout within a given area. In light of these deficiencies, previous attempts to produce devices having both extremely high packing densities and enhanced operating performance have failed.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed toward a column transistor arrangement in a semiconductor device that substantially reduces or eliminates one or more of the limitations and disadvantages of the prior art arrangements.
The claimed inventions provide column transistors for semiconductor devices that include a sense amplifier connected to a local data line and a bit line having shared active regions. More specifically, each of the active areas constitutes either a source or a drain region for a pair of adjacent column transistors that are separate sets of column transistors.
The configuration of the gate electrode structures is modified to remain more substantially within the column transistor, thereby increasing the effective width of the resulting transistor. With the gate electrodes bent to form a ¤ character form, all the gate electrodes of corresponding column transistors are connected to a single sense amplifier, the gate electrode for each set of column transistors contacts metal wiring at only one point, and each active region is in contact with two bit lines and one local data line. In another aspect of the present invention, a semiconductor device can be fabricated in which the column transistors are arranged in an orthogonal matrix comprising a plurality of sets of four square active regions, a gate electrode having a bent portion overlapped with the set and being connected to a sense amplifier along with a plurality of other column transistors. Further the column transistors according to the present invention are arranged with four bit lines running over each one of the active regions, with only two the bit lines making contact with any single active region, and four local data lines running in a direction perpendicular to the bit lines, with only two of the data lines running over any single active region, only one of which will be in contact with a specific active region.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.


REFERENCES:
patent: 5389810 (1995-02-01), Agata et al.
patent: 5416350 (1995-05-01), Watanabe
patent: 5444275 (1995-08-01), Kugishima et al.
patent: 5689129 (1997-11-01), Pearce
patent: 5859805 (1999-01-01), Takashima et al.
patent: 0 840 325 (1998-05-01), None
patent: 60167360 (1995-08-01), None

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