JPS63161638A - Power supply wiring method of semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To constitute a semiconductor integrated circuit by connecting a plurality of cell lines to power cells by a minimum cell area by conforming width by using the cells for power supply, in which the positions of equipotential power terminals in the horizontal direction of the upper and lower sides of the cells for power supply inserted into cell lines differ, and arranging power lines. CONSTITUTION:Power lines 4 in the vertical direction displaying power wirings in the horizontal direction and power lines 6 in the horizontal direction are connected by contact holes 5, and the power lines 6 in the horizontal direction is connected to a power line for a standard cell adjacent to a power cell. Since horizontal pitches in the power cell can be changed, this method has a merit that a dummy cell for conforming width as seen in conventional methods may not be employed. Power cells having the different angles of the cranks of wiring patterns in the cell are registered previously to a plurality of cell libraries actually in the power cells, and it is preferable that the optimum power cell is selected in response to the condition of the arrangement of other standard cell.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a standard cell type semi-custom integrated circuit,
In particular, the present invention relates to a semi-custom semiconductor integrated circuit power wiring method that can efficiently supply power to each cell row.

(Prior Art) The standard cell method is often used as a construction method for semiconductor integrated circuits. In this method, standard cells containing pre-designed active elements, etc. are arranged in multiple rows (or columns), and connections between each cell are made using an automatic wiring program, etc., making it a one-man design method. In comparison, it is characterized by shortening the period required for development. As one of the power supply methods for such standard cell type integrated circuits.

As shown in FIG. 3, a special cell for power supply (power supply cell and power supply cell) as shown in FIG. As shown in Fig. 3, the power supply wiring 4 is vertically connected by using a wiring that is thicker than the metal wiring used for the signal wiring (usually abbreviated as second layer M wiring = 2At). Pass two lines parallel to each other. In the standard cells arranged on the left and right sides of the power supply cell 3, power supply wiring 6 is already provided by IM in the vertical and horizontal directions, and as shown in FIG. 2A-t is connected to 1M at the same location as other cells.

Power is supplied to all the standard cells by connecting the end of the 2At that is passed through in the vertical direction to a power supply pad (not shown). Note that 7 is a dummy cell. The problem with this method is that the type of power supply cell is limited to those in which the horizontal coordinates of the equipotential terminals on the upper and lower sides are equal, as shown in Figure 4, and the power supply line is In order to pass the power cell in a straight line in the vertical direction, the insertion position of the power supply cell in each row must be such that the horizontal coordinates are naturally equal. However, there are a wide variety of circuits realized using standard cells, and it is not always possible to insert power cells in a straight line. If this is not the case, it is necessary to add dummy cells to adjust the cell width in order to adjust the position of the power cells. No.

Adding dummy cells not only increases the chip area but also increases the total number of cells in one circuit, which places a burden on automatic placement/routing programs and reduces design efficiency. Furthermore, the more cell rows there are, or the more wide cells there are in one row, the more the cell width adjustment becomes more difficult.
Increased difficulty.

A large number of dummy cells are required.

(Problems to be Solved by the Invention) The present invention has been made in view of these problems.
It is an object of the present invention to provide a wiring method for a semiconductor integrated circuit that can reduce the addition of width matching cells for inserting power supply cells and can efficiently route power supply lines.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve this object, the present invention, in a standard cell type semi-custom integrated circuit, cranks a vertical wiring pattern inside the cell as illustrated in FIG. A power supply cell with different X coordinates on the upper and lower sides of the first equipotential terminal is also prepared, and this cell and a conventional power supply cell are inserted into each cell row as appropriate.

The present invention is characterized in that the number of width adjustment cells required for inserting these power supply cells can be reduced as much as possible.

(Function) By cranking the wiring pattern in the special cell for power supply as shown in FIG.

The horizontal coordinates of the power supply cells as shown in FIG. 4, which have been adjusted by width adjustment cells, can be adjusted without adjustment or by reducing the number of dummy cells for width adjustment. This becomes more effective by preparing several types of power cells with different crank angles, as shown in FIG.

(Example) The present invention will be described in detail below with reference to one drawing.

FIG. 1 shows an embodiment of a power supply cell in a standard cell type integrated circuit according to the present invention. In the figure.

1 is a cell row consisting of standard cells, and a portion designated by 2 is a new type of power supply cell according to the present invention. FIG. 2 is a detailed diagram of the power supply cell 2 according to the present invention in FIG.
A vertical power line 4 and a horizontal power line 6 are connected through a contact hole 5, and the horizontal power line 6 is connected to the power source of a standard cell adjacent to the power cell in question. connected to the line.

A first method using a power supply cell as shown in FIG. 2 according to the present invention.
The power supply wiring method shown in the figure has the advantage that it is not necessary to use dummy cells for width adjustment as in the conventional method, since the horizontal pitch can be changed within the power supply cells.

In practice, for these power cells according to the present invention, a plurality of cell wiring patterns with different crank angles are registered in a cell library, and the optimal one is selected according to the arrangement of other standard cells. It is desirable to do so.

In addition, the present invention can be implemented with various modifications without departing from the scope.

The wiring method of the present invention and the conventional method will be compared and explained using FIGS. 5 to 7. FIG. 5 is a diagram showing the arrangement of standard cells before the power supply cells are inserted. In the first row, four cells each having a width of 2 units are lined up, and in the second row, cells having a width of 5 units and 3 units are lined up.

When inserting a power supply cell with a cell width of 2 units into the cell row shown in FIG. 5 using the conventional method, as shown in FIG.
Unless we add dummy cells for width adjustment (the cell width is l units) to the left end of the row and the right end of the second row, we cannot route the power supply line of 2/L/ in the vertical direction, and the total cell width Both the 1st and 2nd lines have 11 units.

On the other hand, as shown in FIG. 7, if a power supply cell with a cell width of 2 units according to the present invention is inserted, a dummy cell for 1 width adjustment becomes unnecessary, and the total cell width can be reduced to 10 units in both the 1st and 2nd rows.

〔Effect of the invention〕

According to the present invention, a semiconductor integrated circuit can be constructed by connecting a plurality of cell rows to power supply cells with a minimum cell area of a board without using dummy cells.

[Brief explanation of the drawing]

FIG. 1 is an overall view of an embodiment according to the present invention, FIG. 2 is a detailed view of a power supply cell according to the present invention, FIG. 3 is an explanatory diagram of how to use a conventional power supply cell, and FIG. Figure 4 is a detailed diagram of the power supply cell used in Figure 3, Figure 5 is a cell layout diagram before power cell insertion, and Figure 6 is a diagram of the conventional power supply cell inserted into the circuit shown in Figure 5. Figure 8g7 is a diagram in which a power supply cell according to the present invention is inserted into the circuit of Figure 5. I... Standard cell row, 2... Power supply cell according to the present invention,
3... Conventional power supply cell, 4... Vertical power supply wiring, 5... Contact hole, 6... Horizontal power supply wiring, 7... Dummy cell for cell row width adjustment. Agent Patent Attorney Nori Ken Yudo Takehana Kikuo＼J To〈ton', J)／? l-J

Claims (1)

[Claims] Multiple cell rows equipped with active elements are arranged on a semiconductor substrate,
In standard cell type semiconductor integrated circuits in which a desired circuit is realized by wiring between them, power supply lines are placed above and below the power supply cells inserted into the cell row in order to arrange the power supply lines perpendicularly to the cell row. A power supply wiring method for a semiconductor integrated circuit, characterized in that the power supply lines of the power supply cells are wired by aligning the widths using power supply cells whose sides have different equipotential power supply terminal positions in the horizontal direction. .