JPS58124266A - Semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To make it possible to utilize the circuit even though it has defects without discarding it, by preparing a plurality of circuit blocks with the same function comprising high density active element regions which tend to include serious defects, wiring the selected good circuit so as to contribute the operation, thereby improving the circuit design and the yield rate. CONSTITUTION:In a microcomputer chip in an example in the figure, two ROMs and two ALUs having the same functions, respectively, are prepared. In this constitution, e.g. in the ROMs (A) and (B), the probability of the even either of (A) or (B) does not have the defect is twice the probability of the event the ROM (A) does not have the defect. Then a plurality of the blocks (e.g. two), which are formed by the high density active elements and have a small occupying area, and whose probability of the event of including the defect is low, are intentionally prepared. A selecting circuit (e.g. a fuse circuit wherein polysilicon is used) is provided for each block. The characteristics of the blocks are checked by the selecting circuits, and the block which does not have the defect is selected. Then the yield rate is improved by twice or more by only increasing a pellet area by 1.5 times.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor integrated circuit, and more particularly to an integrated circuit configured by connecting circuit blocks having a certain function on one chip with wiring.

Conventionally, there is a microcomputer whose block diagram is shown in FIG. 1 as a typical example of such an integrated circuit.

This micro combinator has a ROMI as a program memory, a program counter 2 as its addressing circuit, a ROM 3 as a data memory, and a register 4, ALU 5, Ilo 6, etc. connected via a data bus 7. There is. Among these, ROM, RAM, and ALU are composed of active elements.

Engineering 10. When comparing active areas such as program counters and registers with wiring areas such as data buses that do not include active elements, there is a characteristic that the area occupied by the wiring areas occupies more than half of the pellet area. Furthermore, the probability that each block constituting a microcomputer does not contain defects is a function of the integration density, and when comparing the same area, P (ROM, RAM) < P (random circuit) x P (wiring). Here, the random circuit includes an ALU and Iρ.

Contains program counter, registers, etc.

In general, the probability that a block does not have a fatal defect is NA It is expressed as P(NA)=e.

Here, N is the number of fatal defects per unit area,
This is the area occupied by the AFi book.

Figure 2 shows the probability that the blocks constituting the microcomputer are free of defects. The probability P (RUM nFtAM n random n wiring) that a microcomputer does not contain a defect is extremely small if the area occupied by each block is large, and it is almost impossible to obtain a good product. Therefore, it is necessary to increase the probability of not including defects.

Generally, in an LSI or VLSI, the wiring area occupies most of the area, and the area occupied by a block composed of active elements is small. Furthermore, the number of fatal defects per unit area is different between high-density blocks such as R, OM, and RAM and low-density blocks such as random circuits, and ROM and RAM have extremely high defect density. As described above, since the bullet area is dominated by the wiring area, whether or not the chip itself can be manufactured with good yield is determined by the ROM, RAM, and random circuits.

Looking at conventional integrated circuits from this perspective, the number of circuit blocks formed on a chip is the safe minimum, that is, only one each.

This can be said to be the result of advances in semiconductor technology that have made it possible to miniaturize patterns, and to expand functionality by providing as many types of circuits and large-capacity memory IJ's as possible on a single chip. For this reason, defective products with poor manufacturing yields had no choice but to be disposed of.

An object of the present invention is to improve the yield by improving the circuit design, and to provide a semiconductor integrated circuit M' that can be used without being discarded even if there are defects.

Based on the above-mentioned viewpoint, the present invention prepares a plurality of circuit blocks with the same function made of high-density active element fabrics that are likely to contain all fatal defects, and selects a good circuit block by conducting a characteristic test on these circuit blocks. It is characterized in that it is connected to the wiring to contribute to the operation.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a block diagram of this embodiment, taking a microcomputer chip as an example.

Here, we will introduce two LOOMs and two ALUs each with the same function.
We have pieces available. By doing this, for example, the ROM
The probability that either one of (1) and (2) does not contain a defect is more than twice the probability that ROM (2) does not contain a defect. Therefore, it is formed with high-density active elements, occupies a small area,
We deliberately selected multiple blocks with a low probability of containing no defects (
For example, two blocks) are prepared, and a selection circuit (for example, a fuse circuit using polysilicon) is provided for each block.
If this is used to select blocks with no defects after characteristic inspection, the pellet area can be reduced to 1.5 in the example shown in Figure 2.
You can more than double the yield by simply doubling it.

Figure 4 shows an example of a circuit that uses a polysilicon fuse to separate I' (OM) from the data bus. If ROM ■ is defective, connect a voltage of about 15 V between the power supply terminal VD and the write terminal W. Polysilicon fuse 8
A current of several tens of mA is applied to the wire to cut it. After connecting to the write terminal in this way and disconnecting the power supply,
When an external source is connected to the power supply terminal VD, the write terminal W
becomes the ground potential, and the t source supply switch Pl to the ROM becomes non-conductive. Also, P'1. + P3 r mouth 2. n3
The ROM data bus output buffer consisting of P4 + '4 + '5 is non-conductive, and the ROM manual buffer consisting of P4 + '4 + '5 is also non-conductive, so the elements constituting the ROM It can be electrically separated from the data bus without consuming anything.

In addition to applying the present invention to both the ALU and the ROM as shown in this example, the present invention may also be applied to only one of them (preferably RO or M). Further, a transistor switch or a diode switch may be used instead of the polysilicon fuse.

The above was explained using a microcomputer with various functional blocks connected to the data bus.
Even in integrated circuits without buses (particularly VLSIs), the yield of VLSIs can be improved by preparing two or more blocks with the same function and selecting functional blocks without defects.

[Brief explanation of the drawings] Figure 1 is a block diagram of a conventional microcomputer configured by connecting various functional blocks to a data bus, and the second diagram shows the occupation of the various functional blocks shown in Figure 1. Figure 3 shows a characteristic diagram of the area and the probability of not containing a defect.This book shows a method in which two or more functional blocks with a low probability of not containing defects are prepared in the same block, and the one with no defects is selected using polysilicon fuses. VLSI in one embodiment of the invention
FIG. 4, a block diagram of the microcomputer, is a circuit diagram of the switch portion of this embodiment. ■...ROM, 2...Program counter, 3...RAM, 4...Register, 5...ALU, 6...・・Ilo, 7・・
...Data bus, 8...Polysilicon fuse. 7- Ward 1 Random Which AFI F? 0/'I Dake circuit Haas Y5 shoulder area ? Figure 3rd ward

Claims (1)

[Claims] 1. A semiconductor integrated circuit comprising a plurality of circuit blocks having the same function on the same substrate, and comprising means for selecting a defect-free circuit block from among the circuit blocks.