Sense amplifier configuration with fused diffusion regions...

Details Sense amplifier configuration with fused diffusion regions... Sense amplifier configuration with fused diffusion regions...

2000-02-24

2001-05-29

Hoang, Huan (Department: 2818)

Static information storage and retrieval

Format or disposition of elements

C365S063000, C365S205000

Reexamination Certificate

active

06240005

ABSTRACT:

BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention lies in the semiconductor technology field. More specifically, the present invention relates to a sense amplifier configuration for a semiconductor memory device having a multiplicity of sense amplifier (sense-amp) transistors and drivers assigned thereto. Such sense amplifiers are also frequently referred to as read-write amplifiers.
The term “drivers” as used in this text is intended to mean a single transistor or else a multiplicity of individual transistors which are each provided for driving the sense-amp transistors.
In existing semiconductor memory devices, the sense-amp transistors are arranged alternately with drivers at the edge of a cell array. In other words, a group of sense-amp transistors is followed by a driver, which is in turn followed by a group of sense-amp transistors. Such an arrangement is shown in
FIG. 3
, which illustrates groups
1
of sense-amp transistors alternating with drivers
2
. The cell array or cell field is situated on the right-hand side of
FIG. 3
in the illustrated arrangement.
Such a configuration of sense-amp transistors
1
and drivers
2
opens up certain advantages for the layout of semiconductor memory devices, which is why there has been no departure from such an implementation heretofore. These advantages include, by way of example, a saving of area on account of the alternate implementation of sense amplifier groups and drivers.
It is disadvantageous, however, in the existing sense amplifier configuration shown in
FIG. 3
, that the individual sense-amp transistor groups
1
each have different diffusion regions and, moreover, the wiring paths between individual sense-amp transistors of the respective groups
1
and the associated driver
2
may be relatively long.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a sense amplifier configuration, which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type, in which critical diffusion region distances between individual sense-amp transistor groups are avoided, and in which the drivers can be optimally coupled to the sense-amp transistors.
With the foregoing and other objects in view there is provided, in accordance with the invention, a sense amplifier configuration for a semiconductor memory device, comprising:
a multiplicity of sense-amp transistors of a given conductivity type each disposed in a common continuous diffusion region; and
a driver for the sense-amp transistors disposed directly adjacent the sense-amp transistors and parallel to the diffusion region.
In other words, the objects of the invention are satisfied with the sense amplifier configuration in which the sense-amp transistors of each conductivity type each have a common continuous diffusion region and the drivers for the sense-amp transistors are arranged parallel to the diffusion region directly next to the transistors.
Therefore, the sense amplifier configuration according to the invention departs from the concept of the previous layout for sense amplifiers and drivers: instead of the alternate arrangements of sense-amp transistor groups and drivers, in this case a respective continuous diffusion region in the form of a strip is provided in the first instance for the sense-amp transistors of each conductivity type, that is to say for P-type sense-amp transistors and N-type sense-amp transistors, with the result that critical diffusion region distances for fabrication are avoided in principle. The drivers each lie directly next to the N-type sense-amp transistors and the P-type sense-amp transistors, with the result that the drivers and the sense-amp transistors can be optimally coupled and, in particular, no large wiring resistances delay the charge transfer.
What is essential to the present invention, therefore, is that all the P-type sense-amp transistors and all the N-type sense-amp transistors in each case have a common diffusion region located at the side of a memory cell array. A respective driver comprising one or a multiplicity of transistors, as was explained in the introduction, is provided parallel to these diffusion regions for the P-type sense-amp transistors and the N-type sense-amp transistors.
In accordance with an added feature of the invention, the sense-amp transistors are U-shaped with limbs, and the sense-amp transistors are arranged linearly in rows, with the limbs in each row extending in one direction and the driver arranged parallel to the row along the open limbs.
The U-shaped configuration of the sense-amp transistors means that the width of the latter is practically doubled. Instead of the previously straight gates of the sense-amp transistors of existing semiconductor memory devices, therefore, the sense amplifier configuration according to the invention employs sense-amp transistors whose gates are no longer straight but U-shaped, which, in an advantageous manner, essentially doubles the channel width.
As has already been pointed out, these U-shaped sense-amp transistors are each provided in direct proximity to the drivers, with the result that short local connections can be constructed between the drivers and the sense-amp transistors without large wiring resistances. Delays in the power transfer between the drivers and the sense-amp transistors are thereby avoided.
In accordance with an additional feature of the invention, therefore, a short local connection is provided between each sense amplifier transistor and the driver.
In accordance with a concomitant feature of the invention, a drain of the sense-amp transistor is disposed between the limbs, and a source of the sense-amp transistor is disposed outside the limbs.
In other words, it is also advantageous, in the case of the U-shaped sense-amp transistors, for the drain to be situated between the limbs of the “U” and for the source to be situated outside the limbs of the “U”.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a sense amplifier configuration with fused diffusion regions and a distributed driver system, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.


REFERENCES:
patent: 4660174 (1987-04-01), Takemae et al.
patent: 5875452 (1999-02-01), Katayama et al.
patent: 4132864C2 (1995-12-01), None
patent: 2184311A (1987-06-01), None

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