JPH04188835A - Semiconductor device - Google Patents

Abstract

PURPOSE:To reduce the defective circuit switching by the failure of disconnection due to the irradiation position error of a laser beam by a method wherein the change-over system of inner circuit wherein only one out of multiple polycrystalline silicon wirings is disconnected is adopted. CONSTITUTION:When one of the fuses 1-3 is disconnected by the laser beam irradiation, one input out of 3-input NAND gate 7 is turned into L by the pull- down resistor. Accordingly, the output from the gate 7 is transferred from L to H so as to switch the output of an inverter 8 from H to L so that the transfer gate 10 may be turned OFF while a gate 11 may be turned ON. Thus, an address bus 9 is disconnected from another bus 12 to be connected to a redundant address bus 13. Through these procedures, even if only one out of multiple polycrystalline silicon wirings is disconnected, the defective circuit switching due to the irradiation position error of a laser beam can be reduced by changing-over the inner circuits.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a circuit in a portion of a semiconductor device in which internal circuits are switched by irradiation with a laser beam.

[Summary of the Invention] The present invention provides a semiconductor device having a circuit for switching internal circuits by cutting a polycrystalline silicon wiring by irradiation with a laser beam. By adopting a circuit system in which there are multiple crystalline silicon wirings and the internal circuit is switched if even one of them is cut, it is possible to prevent cutting failures due to misalignment of the irradiation position of the laser beam on the polycrystalline silicon being cut. This is intended to reduce the occurrence of circuit switching failures.

[Conventional technology J] By cutting the conventional polycrystalline silicon wiring,
When switching internal circuits, one polycrystalline silicon wiring must be cut in order to switch one internal circuit.

A conventional circuit system in which one internal circuit is switched by cutting one polycrystalline silicon wiring is shown in FIG. FIG. 2 is a circuit diagram of a redundant day path switching section of a semiconductor memory manufactured by a conventional method. 101 is a fuse formed of polycrystalline silicon to be cut, 102 is a resistor, 103 is an inverter, 104 is an address bus, 105 is a transfer gate, 106 is a transfer gate, 107 is an address bus, and 108 is a redundant address bus. It is.

The operation of reconnecting address bus 104 from address bus 107 to redundant address bus 108 by cutting fuse 101 will be described. Fuse 1
01 is in a conductive state before being disconnected, the input of the inverter 103 is at "H" level, and the inverter 103
Since the output of is at L++ level, transfer gate 105 is turned on, transfer gate 106 is turned off, and address bus 104 is connected to address bus 107.

When fuse 101 is cut by laser irradiation,
The input of the inverter 103 is pulled down by the resistor 102, and the input of the inverter 103 becomes L'' level.
Since the output of the inverter 103 becomes "H" level,
Transfer gate 105 is turned off, transfer gate 106 is turned on, and address bus 10 is turned off.
4 is separated from address bus 107 and connected to redundant address bus 108.

[The issue that gPA Ming is trying to solveWi1 However, in the above conventional method, only one polycrystalline silicon wiring is cut to switch one internal circuit, so the irradiated laser beam may shift in the irradiation position. If this occurs, the internal circuit cannot be switched.

The present invention is intended to solve these problems, and its purpose is to create a plurality of polycrystalline silicon wirings that are cut to switch one internal circuit, and to cut even one of them. By adopting a circuit system in which the internal circuit is switched when the laser beam is cut, it is possible to reduce the occurrence of circuit switching defects due to cutting defects due to misalignment of the irradiation position of the polycrystalline silicon wiring to be cut by the laser beam. .

[Means for Solving the Problem] When internal circuits are switched by cutting polycrystalline silicon wiring by laser beam irradiation, the polycrystalline silicon wiring that is cut to switch one internal circuit is It is characterized by a circuit system in which there are multiple wires, and if even one of them is disconnected, the internal circuit is switched.

[Example 1 Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a circuit diagram of a switching portion of a redundant circuit of a semiconductor memory using the present invention.

1.2.3 is a fuse formed by polycrystalline silicon to be cut, 4.5.6 is a pull-down resistor, 7 is a three-way NAND gate, 8 is an inverter 9 is an address bus,
10 is a transfer gate, 11 is a transfer gate, 12 is an address bus, and 13 is a redundant address bus.

Address bus 9 is then connected to address bus 1 by cutting at least one of fuses 1.2.3.
2 to the redundant address bus 13 will be explained.

Since the fuses 1, 2, and 3 are in a conductive state before being cut by the laser beam, all inputs to the 3-man NAND gate 7 are at the "H" level, and the output of the 3-man power NAND gate 7 is at the "L" level. , the output of inverter 8 is 'H
” level, the transfer gate 10 is turned on, the transfer gate 11 is turned off, and the address bus 9 is connected to the address bus 12.

If any one of the fuses 1, 2, and 3 is cut by laser beam irradiation, for example, if only fuse 1 is cut, the pull-down resistor 4 will cause one of the inputs of the three-man NAND gate 7 to be cut. becomes "L" level, the output of the three-man power NAND gate becomes "H" level, and the output of inverter 8 becomes "L", so transfer gate 10 is in the off state and transfer gate 11 is in the OFF state.
is turned on, and address bus 9 is disconnected from address bus 12 and connected to redundant address bus 13.

[Effect of the invention 1 As described above, according to the present invention, a plurality of polycrystalline silicon wirings are cut to switch one internal circuit, and if even one of them is cut, the internal circuit is By adopting a switching circuit system, it is possible to reduce the occurrence of circuit switching failures due to cutting failures due to deviations in the irradiation position of the laser beam on the polycrystalline silicon to be cut.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a switching portion of a redundant circuit of a semiconductor memory using the present invention. FIG. 2 is a circuit diagram of a switching portion of a redundant circuit of a semiconductor memory using a conventional method. 1...Fuse 2...-Fuse 3...Fuse 4...Pull-down resistor 5...Pull-down resistor 6...Pull-down resistor 7...3 Manual NAND gate 8...Inverter 9... Address bus 10...Transfer gate 11...Transfer gate 12...Address bus 13...Redundant address bus 101...Fuse 102...Pull-down resistor 103...Inverter 104... Address bus 105...Transfer gate 106...Transfer gate 107...Address bus 108...Redundant address bus and above Applicant Seiko Epson Corporation agent Patent attorney Kizobe Suzuki and 1 other person "4 z diagram

Claims (1)

[Claims] A circuit that switches internal circuits by cutting a polycrystalline silicon wiring by irradiation with a laser beam, the polycrystalline silicon wiring being cut in order to switch one of the internal circuits. 1. A semiconductor device comprising a plurality of polycrystalline silicon wirings, and a circuit in which the internal circuit is switched if even one of the polycrystalline silicon wirings is cut. 3.