JPH05343518A - Cell for automatic layout - Google Patents

Abstract

PURPOSE:To restrain a drop, in the integration density of the cell, which is caused when a part as a wiring bottleneck is produced in the central part in an automatic layout. CONSTITUTION:The cell is realized in the following manner: primitive cells in which the thickness of power-supply wirings 1 and ground wiring 2 having the same function and the size of cells are different are prepared; the small primitive cells are arranged in the central part of a layout block; and the large primitive cells are arranged in the peripheral part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mask pattern design of a semiconductor integrated circuit, and more particularly to an automatic layout cell of a standard cell type semiconductor integrated circuit.

[0002]

2. Description of the Related Art Conventionally, in a primitive cell for automatic layout of a standard type semiconductor integrated circuit, the outer shape of the cell is constant, and the widths of power supply and ground wirings contained in the cell are also constant.

FIG. 4 shows the result of a conventional automatic layout of a semiconductor integrated circuit block. In the wiring region 3, wirings are generally densely formed in the central portion for wiring between the cell regions 3, and the height of the wiring region 3 is determined by the dense portion. Further, the height of the cell region 3 is constant. Further, the power supply wiring 1 and the ground wiring 2 are provided at both ends of the cell region 3.
Is provided.

[0004]

In the primitive cell for automatic layout as described above, the outer shape of the cell is constant, and the widths of the power supply wiring and the ground wiring included in the cell are constant. In addition, power and ground are provided from both ends of the cell area.

Now, at both ends of the cells arranged on the same cell row, it is necessary to supply power and ground to the inner cells, so that the power supply wiring and the ground wiring need to be thick. However, in the central cell, since it is less necessary to supply power and ground to other cells, the power supply line and the ground line have the same thickness as both ends although the power supply line and the ground line may be thin.

Therefore, as a result, the power supply wiring and the ground wiring are thicker than necessary depending on the location, especially the central portion, and the height direction of the semiconductor integrated circuit block becomes large.

When the area is increased in this way, there is a problem that the cost of the semiconductor integrated circuit is increased.

It is an object of the present invention to provide an automatic layout cell with improved integration.

[0009]

In order to achieve the above object, an automatic layout cell according to the present invention is an automatic layout cell of a standard cell type semiconductor integrated circuit, which is a combination of a plurality of primitive cells. The cell has a power supply line and a ground line, and the thickness of the power supply line and the ground line is set according to the minimum current capacity of the power supply line and the ground line determined by the placement position of the primitive cell.

[0010]

The thickness of the power supply line and the ground line in the primitive cell is changed according to the minimum current capacity of the power supply line and the ground line determined when the primitive cell is arranged.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 is a layout diagram showing a first embodiment of an automatic layout cell of the present invention.

In FIG. 1, as a primitive cell,
There are three types of type S, type M, and type L that have the same function but different widths of the power supply wiring 1 and the ground wiring 2. The thicknesses of the power supply wiring 1 and the ground wiring 2 in the primitive cell are Is set according to the minimum current capacity of the power supply wiring 1 and the ground wiring 2 which is determined by the arrangement position of the primitive cell.

Therefore, an appropriate primitive cell is selected according to the position where the primitive cell is arranged.
The size of the primitive cell differs depending on the width of the power supply wiring 1 and the ground wiring 2.

FIG. 2 shows the result of automatic layout of blocks using the automatic layout primitive cell of the present invention. Since the power and ground are supplied from both ends, the cells near both ends need to supply the power and ground to the cells inside themselves.

Therefore, the width of the power supply wiring and the ground wiring is the type L which is thicker than that of the inner cell. On the contrary, the cells near the center do not need to supply power and ground to others, so the power and ground widths are narrow,
The type S whose cell size may be small accordingly is used.

In the example shown in FIG. 2, type L primitive cells are arranged in both ends 1/6 of the cell region of the same column, and type S primitive cells are arranged in the center 1/3 of the cell regions. Type M primitive cells are arranged in the area sandwiched between type S and.

What should be noted here is the fact that, in contrast to the primitive cell size, in the wiring region 4, the central portion is denser than the vicinity of both ends. This is because when attempting to connect each of the primitive cells with the shortest distance, the wiring has a higher rate of passing through the central portion than near both ends. In general, the height of the wiring region 4 is determined by the number of horizontal wirings in the central portion, so that the size of the primitive cell in the central portion becomes small, so that the area of the block is surely reduced.

As described above, by always arranging and wiring the primitive cells of a size determined by the coordinates from among a plurality of primitive cells existing according to the coordinates (distance from both ends) where the primitive cells are arranged, A highly integrated layout can be realized.

(Embodiment 2) FIG. 3 is a layout diagram showing Embodiment 2 of the present invention.

In this embodiment, a plurality of primitive cells having the same function and different widths of the power supply wiring 1 and the ground wiring 2 are prepared, and an appropriate primitive cell is selected depending on the arrangement position.

In this embodiment, unlike the first embodiment, the size of the primitive cell is the same, but there is a region in which horizontal wiring is possible in the primitive cell, and as a result, the wiring region can be supplemented. .

Further, unlike the first embodiment, since the size of the primitive cell itself does not change, there is an advantage that the automatic layout tool can be used even when cells having different heights cannot be arranged.

[0024]

As described above, in the automatic layout cell of the present invention, the thickness of the power supply wiring and the ground wiring in the primitive cell is changed according to the arrangement condition, so that the characteristics are not deteriorated. By eliminating unnecessary thick power supply wiring and ground wiring, it is possible to improve the element density in the semiconductor integrated circuit and prevent an increase in cost.

[Brief description of drawings]

FIG. 1 is a layout diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a state of layout using the primitive cell according to the first embodiment of the present invention.

FIG. 3 is a layout diagram showing a second embodiment of the present invention.

FIG. 4 is a diagram showing a layout state of a conventional example.

[Explanation of symbols]

 1 power supply wiring 2 ground wiring 3 cell area 4 wiring area

Claims (1)

[Claims] 1. A cell for automatic layout of a standard cell type semiconductor integrated circuit, which is a combination of a plurality of primitive cells, wherein the primitive cell has a power supply wiring and a ground wiring, and the thickness of the power supply and the ground wiring is An automatic layout cell, which is set according to the minimum current capacity of the power supply wiring and the ground wiring determined by the placement position of the primitive cell.