JP3017181B1 - Semiconductor integrated circuit wiring method - Google Patents

Abstract

[PROBLEMS] Because thin wiring is frequently used, a space between wiring grids becomes a useless space. To avoid this, manual wiring must be used instead of automatic wiring. SOLUTION: In a wiring from a large-scale function cell (macro) to an input / output unit (I / O unit), a branch block is arranged at an arbitrary position near a macro, so that a connection from the I / O unit to the branch block is obtained. Automatic wiring is performed with a wide wiring of an arbitrary wiring width, and automatic wiring is performed with a narrow wiring from a branch block to a macro.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for automatically wiring a large-scale function cell of a semiconductor integrated circuit and another large-scale function cell, or a large-scale function cell and an input / output portion.

[0002]

2. Description of the Related Art With the remarkable progress in miniaturization of LSI processes in recent years, the scale of integration of LSI chips has been increasing year by year, and wiring widths have been reduced. Therefore, in particular, the wiring width of the power supply wiring needs to be connected with a thick wiring in order to avoid a reduction in the power supply voltage due to the potential drop. On the other hand, due to the increase in the circuit scale of the LSI chip, manual layout design is practically impossible, and an automatic placement and routing tool is indispensable for the design.

However, in the current wiring method of the automatic placement and routing tool, a wiring layer and a wiring width to be wired by the tool are defined in advance as a library of tools, and the rules are followed and executed.

[0004] For this reason, unless the designer considers the specifications and limitations of the tool in advance and sets the optimal parameters in the automatic placement and routing tool, dead space or unwiring that cannot be arranged in the LSI chip occurs.

[0005]

From the above background, a method and problems of the conventional automatic wiring of a large-scale function cell (hereinafter referred to as "macro") will be described below. That is, in the prior art of which an example is shown in FIG.
Taking the wiring from 5 to the macro as an example, the wiring width of the wiring 26 could not be changed to an arbitrary wiring width in the middle of the wiring in the past, so that a plurality of wirings were previously set to satisfy the electromigration condition. The automatic wiring by the book had to prevent the power supply voltage from dropping due to the potential drop. In FIG. 6, reference numeral 7 denotes a wiring from inside the macro, and 8 denotes a loop ring of the macro.

In another conventional example shown in FIG. 8, a wiring 7 from the inside of the macro is connected to a circling ring 8 of the macro, and a wiring 29 from the I / O section 5 is connected to the circling ring 8 of the macro.
This is an example of connecting to. In this configuration, as shown in FIG. 9, if the interval between the wirings 7 was wide in multiple sentences, the wiring 31 from the I / O unit could be automatically thickened, but when the interval between the wirings 7 was narrow as shown in FIG. In conventional automatic wiring, only one kind of wiring width can be used.
Had become.

Further, in the conventional example shown in FIG. 6, since a large number of thin wires are used, the space 25 between the wiring grids becomes a useless space. To avoid these drawbacks,
Instead of automatic wiring, manual wiring 27 as shown in FIG.
Had to be wired.

An object of the present invention is to provide an arrangement and wiring method for automatically branching a wiring having a large wiring width to a plurality of connection portions in a power supply wiring and a signal wiring.

[0009]

According to the present invention, there is provided a wiring method for a semiconductor integrated circuit, wherein wiring is performed by automatic connection to a functional cell of the semiconductor integrated circuit. The present invention is characterized in that the branch wiring to the functional cell and the branch block is realized by a narrow wiring, and the wiring to the branch block is realized by a wide wiring by automatic connection.

In this case, as an embodiment of the present invention, the functional cells are arranged on an LSI chip, and the line width corresponding to the total of the narrow line widths of the branched narrow line lines is changed to an electronic line. Set the wiring width so that the power supply voltage does not decrease due to the potential drop by satisfying the migration condition.
Set the wiring width and the number of branches of the narrow wiring, select a dummy block according to the number of branches from a plurality of types of interconnectable branch block library prepared in advance, determine the arrangement of the dummy block, Thereafter, a method of automatically connecting the wide wiring and the narrow wiring is effective.

In such a wiring method, a function cell (for example, a large-scale function cell called a macro) is connected to an input / output unit (I / O).
By arranging the branch block at an arbitrary position near the functional cell in the wiring up to the / O section), the wiring from the I / O section to the branch block is automatically wired with a wide wiring having a required wiring width, and from the branch block. Up to macros can be automatically wired with narrow wiring. In addition, since the total wiring width of the wide wiring and the narrow wiring does not change, automatic wiring can be performed while satisfying the electromigration conditions.

When there are a plurality of wirings having the same potential,
By using a branch block, it is possible to perform automatic wiring by bundling into one wiring, and there is no useless space between wirings when a plurality of signal wirings are used, and it is possible to increase the wiring area. . In addition, a plurality of wires
By bundling the wirings in a book, the lateral capacitance of the wirings with respect to the board can be reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing an example in which wiring from an input / output unit (I / O unit) 5 to a large-scale function cell (macro) is automatically wired using a wide wiring 4 and a narrow wiring 6 using a branch block 2. This is illustrated. Reference numeral 1 denotes a wiring grid, 7 denotes a wiring from inside the macro, 8 denotes a circling ring of the macro, and 37 denotes a through hole.

By arranging the branch block 2 at an arbitrary position near the macro, the branch block 2 is removed from the I / O section.
Can be automatically wired with a wide wire 4 having an arbitrary wire width 3 and a narrow wire 6 can be automatically wired from a branch block to a macro. Since the total wiring width of the wide wiring 4 and the narrow wiring 6 does not change, automatic wiring can be performed while satisfying the electromigration conditions.

When there are a plurality of wirings 26 having the same potential as shown in FIG. 6, it is possible to use the branch block 2 as shown in FIG. When the plurality of signal wirings 26 shown in FIG. 6 are used, there is no needless space 25 between the wirings, and the wiring area can be increased.

Also, by bundling the plurality of wirings 9 shown in FIG. 2 into one wiring 11 as shown in FIG. 3, unnecessary space 38 is eliminated, and the lateral capacitance of the wiring with respect to the base 10 is reduced. I can do it.

Next, the wiring method of the present invention will be described with reference to the flowchart shown in FIG. 4 while corresponding to FIG. 1 showing a layout diagram. FIG. 1 shows a part of a semiconductor integrated circuit in which wirings 4 and 6 from an I / O unit 5 to a macro are automatically connected by a wide wiring using a branch block 2. In FIG. 1, reference numeral 1 denotes a wiring grid, 7 denotes a wiring from inside the macro, 8 denotes a circling ring of the macro, and 37 denotes a through hole.

Referring to the flowchart shown in FIG. 4, first, in the macro arrangement step 12, LS
A macro is arranged on the I chip. Next, a wiring width 3 that satisfies the electromigration conditions and does not cause a reduction in the power supply voltage due to the potential drop is determined in step 13.
For example, by setting the sum of the thin wirings 26 shown in FIG. 6 to the wiring width 3 of the thick wiring, automatic wiring can be performed while satisfying the electromigration conditions.

Next, the width of the wide wiring is divided by the minimum wiring width of the design rule, and the number of narrow wirings into which the wide wiring is branched is determined in step 14. In step 16, a branch block for N division according to the number of branches is selected from the result of the determination of the number and the branch block library 15 prepared in advance, which can be interconnected. That is, the wide wiring 4 is divided into N by the minimum wiring width of the design rule or the minimum connectable wiring width.

Next, in step 17, the arrangement position of the branch block is determined. 5, 20, 21 and 22 are examples of branch blocks for 2-branch, 3-branch, and 4-branch, respectively. Reference numerals 23 and 24 indicate input / output ports. The determination of the arrangement position of the branch block is performed such that a minimum area capable of narrow wiring is secured from the branch block to the target macro, and the branch block is arranged at a position closest to the target block.

When the arrangement of the branch blocks is determined, the branch blocks are arranged, and in step 18, wide automatic wiring from the dummy block to the branch block is executed.
At 9, a narrow automatic wiring from the branch block to the buffer is executed.

As described above, by using the branch block, wiring can be automatically performed without changing the wiring width satisfying the electromigration condition, and the waste formed between thin wirings by being bundled into one thick wiring. The space can be efficiently used as an effective space, and as can be seen from FIG. 2, the lateral capacitance is also reduced.

Next, in step 19, narrow automatic wiring is performed from the branch block to the buffer.

Next, another embodiment of the present invention will be described with reference to FIG.

FIG. 10 shows that the buffer 35
This is an example of automatic connection using the branch block 34. Conventionally, as shown in FIG. 11, the buffer 35 to the buffer 33 are connected by a plurality of thin wirings 36. However, by using the branch block 34, automatic wiring can be performed with an arbitrary wiring width 32. .

As in the case of FIG. 2, four wires 36
By bundling the wires 32, the lateral capacitance is reduced to a quarter, and the useless wiring space is increased by bundling the wasted space between the wires.

[0028]

As described above, according to the present invention, by using the branch block, the automatic connection with the function cell, which was previously possible only with one kind of wiring width, can be performed by using the branch block. By inserting, for example, it is possible to obtain an effect that the wide wiring and the branched narrow wiring can be automatically wired in a state where the electromigration condition is satisfied.

Further, by increasing the width of the wiring, there is no useless space between the wirings, the number of effective grids increases, and the wiring area increases.

Further, by bundling the thin wiring 9 in FIG. 2 like the thick wiring 11 in FIG. 3, the side capacitance of the wiring with respect to the substrate 10 can be reduced. The wiring delay time is reduced, and the effective current density does not change because the cross-sectional area of the wiring is the same.

[Brief description of the drawings]

FIG. 1 is a plan view illustrating a wiring from a large-scale function cell to an input / output unit 5 wired according to the present invention.

FIG. 2A is a plan view of a plurality of wirings, and FIG. 2B is a cross-sectional view showing a relationship between the arrangement and a substrate.

3A is a plan view of a bundled wiring, and FIG. 3B is a cross-sectional view showing a relationship between the arrangement and a substrate.

FIG. 4 is a flowchart illustrating an example of steps of a wiring method for a semiconductor integrated circuit according to the present invention.

FIGS. 5A, 5B, and 5C are cross-sectional views each showing a different number of bundled wirings.

FIG. 6 is a plan view of a semiconductor integrated circuit wired by a conventional wiring method.

FIG. 7 is a plan view of a semiconductor integrated circuit wired by another conventional wiring method.

FIG. 8 is a plan view of a semiconductor integrated circuit wired by another conventional wiring method.

FIG. 9 is a plan view of a semiconductor integrated circuit wired by another conventional wiring method.

FIG. 10 is a plan view showing a semiconductor integrated circuit wired by the wiring method of the present invention.

FIG. 11 is a plan view showing a semiconductor integrated circuit wired by a conventional wiring method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 wiring grid 2 branch block 3 wiring width 5 input / output unit 4 wide wiring 6 narrow wiring 6 7 wiring from inside macro 8 circling ring 9 wiring 10 board 11 wiring 20, 21, 22 branch block 23, 24 input / output port 32 Wiring width 33,34 Branch block 35 Buffer 37 Through hole 38 Interval

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/82 G06F 15/60

Claims (2)

(57) [Claims] 1. A wiring method for a semiconductor integrated circuit, wherein wiring is performed by automatic connection to a function cell of the semiconductor integrated circuit, wherein a branch block is provided near the function cell, and the branch wiring to the function cell is narrow-width wiring. Wherein the wiring between the functional cell and the branch block and the wiring to the branch block are realized by a wide-width wiring by automatic connection, respectively. 2. A power supply by arranging the functional cell on an LSI chip and, with respect to the sum of the line widths of the branched narrow wirings, changing the corresponding wide wirings to a potential drop by satisfying an electromigration condition. The wiring width is set so as not to cause a voltage drop.The wiring width and the number of branches of the narrow wiring are set in accordance with the design rules. 2. The wiring of a semiconductor integrated circuit according to claim 1, wherein a dummy block corresponding to the number of branches is selected, an arrangement of the dummy block is determined, and then the wide wiring and the narrow wiring are automatically connected. Method.