JP2006253353A - Electric fuse module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an electric fuse capable of storing multi-valued information with a minimum circuit. <P>SOLUTION: An electric fuse module includes a plurality of electric fuses 12 and 13 with different program characteristics, having ends individually connected to external power supply voltage terminals 10 and 11 and the other ends connected in common, a switching element 14 for controlling a program and a switching element 15 for reading which are connected in parallel between a common connection node J of the plurality of electric fuses and a grounding terminal, and a plurality of differential amplifiers 16, 17 and 18 for sensing a voltage level of the common connection node by respective reference voltages 19, 20 and 21. Timing for programming the first or second electric fuse with the different program characteristics is changed, a plurality of voltage levels are realized in the connection node between the electric fuses and the switching elements, and multiple values are realized with a minimum circuit scale. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electric fuse module that electrically cuts an electric fuse element by energization and performs programming (such as fusing and silicidation).

  Conventionally, electric fuse devices (electric fuse modules) are widely used in semiconductor integrated circuits (LSIs) such as high-frequency trimming program devices. In an electrical fuse device, an electrical fuse element formed of polysilicon or the like is connected in series to a bipolar transistor, and programmed by flowing a large current of about 1 ampere and performing programming (melting, silicidation, etc.).

  In recent years, in the field of semiconductor integrated circuits, a process has been developed in which a metal material is silicided and formed on polysilicon as a gate material to reduce the resistance of the gate material. In view of this, an electric fuse element technology has appeared that utilizes a mechanism in which a current is passed through a gate material to cut the silicide layer on the upper surface to increase the resistance. In the 130 nm and 90 nm process generations, the instantaneous current required to program the electrical fuse element by energization is 10 to 30 milliamperes per electrical fuse element.

  FIG. 6 is a circuit diagram showing a configuration example of an electric fuse device conventionally used in a semiconductor integrated circuit. In FIG. 6, 60 is an electric fuse, 61 is a PMOS transistor (switching element) connected in series with the electric fuse 60, and 62 is a NAND circuit whose output is connected to the gate of the PMOS transistor 61.

A program signal is input to the NAND circuit 62 with respect to the selected electric fuse 60, and the PMOS transistor 61 is turned on by the conduction of the NAND circuit 62 and a current flows. The electric fuse 60 is formed of a fine pattern of silicide, polysilicon, or metal, and is thermally programmed when a predetermined current is passed, causing disconnection or an increase in resistance. Accordingly, it is possible to recognize 0/1 of the signal state by reading the initial electric fuse element resistance that is not programmed and the resistance value of the programmed electric fuse that has been increased in resistance. In this way, an electric fuse device can be realized (see, for example, Patent Document 1).
Japanese National Patent Publication No. 11-512879 (pages 12-13, FIG. 3)

  However, the conventional configuration has the following problems.

  The electric fuse is configured to output data of “0” and “1” before and after programming, and stores 1-bit information. However, in recent years, the demand for improving the degree of integration has increased, and in order to meet the demand, there is a demand for a multi-value memory configuration that stores one bit or more in one memory cell.

An electrical fuse module according to the present invention comprises:
A plurality of electrical fuses having different program characteristics, one end of which is individually connected to the external power supply voltage terminal and the other end is commonly connected;
A switching element for program control and a switching element for reading connected in parallel between a common connection node of the plurality of electrical fuses and a ground terminal;
And a plurality of differential amplifiers for detecting the voltage level of the common connection node by each reference voltage.

  When selecting one or a plurality of electrical fuses from among a plurality of electrical fuses and programming (melting, silicidation, etc.), a switching element for program control is conducted, but each electrical fuse is connected to an external power supply voltage terminal. On the other hand, since they are individually connected, the power supply voltage is applied only at the external power supply voltage terminal connected to the electrical fuse to be programmed. The power supply voltage is not applied to the external power supply voltage terminal connected to the non-target electric fuse, and is left open. In this way, by turning on the switching element for program control in a state where the power supply voltage is applied, current is supplied only to the electric fuse to be programmed, and the electric fuse is programmed. This electric fuse program includes fusing as well as high resistance due to material alteration. The resistance value of the programmed resistor, which is a parallel connection body of a plurality of electric fuses, is adjusted according to which one (single or plural) of the plurality of electric fuses is to be programmed. In actual operation of the semiconductor integrated circuit, the read switching element is turned on, and the voltage appearing at the connection node between the programmed resistor and the read switching element is connected to each input terminal of the plurality of differential amplifiers. This connection node voltage corresponds to a power source voltage divided by a resistance ratio between the resistance value after programming of the programmed resistance element and the resistance value of the switching element for reading. Each differential amplifier outputs a voltage corresponding to the difference between the connection node voltage and each reference voltage, and multi-leveling is performed. According to this, the circuit scale can be reduced as compared with the case where two electrical fuse modules are arranged to realize multi-value.

The electrical fuse module according to the present invention is
A plurality of electrical fuses having different program characteristics, one end connected in common to the external power supply voltage terminal and the other end connected in common;
A switching element for program control and a switching element for reading connected in parallel between a common connection node of the plurality of electrical fuses and a ground terminal;
And a plurality of differential amplifiers for detecting the voltage level of the common connection node by each reference voltage.

  When selecting one or a plurality of electrical fuses from among a plurality of electrical fuses and programming (melting, silicidation, etc.), a switching element for program control is conducted, but each electrical fuse is connected to an external power supply voltage terminal. For this reason, the power supply voltage corresponding to the characteristics of the electric fuse to be programmed is applied to the external power supply voltage terminal. By making the switching element for program control conductive with the power supply voltage applied in this way, a current flows through all the electrical fuses, but the applied power supply voltage is adjusted so that a current suitable for the electrical fuse to be programmed is obtained. Since it will flow (because the time to program completion is adjusted), only the electrical fuse to be programmed is programmed. This electric fuse program includes fusing as well as high resistance due to material alteration. The resistance value of a programmed resistor, which is a parallel connection of multiple electrical fuses, is adjusted according to which (single or multiple) electrical fuses are targeted for programming, that is, according to the applied power supply voltage Will be. The operation in actual operation is the same as described above, and each differential amplifier outputs a voltage corresponding to the difference between the connection node voltage and each reference voltage, and multi-leveling is performed. According to this, the circuit scale can be reduced as compared with the case where two electrical fuse modules are arranged to realize multi-value.

  In order to make the program characteristics different from each other in the plurality of electric fuses having the above-described configuration, they may be made different depending on the length of the thin line portion of the electric fuse shape, or may be different depending on the thickness of the thin wire portion of the electric fuse shape. It may be different, or may be different depending on the difference in both length and thickness.

The electrical fuse module according to the present invention is
An electric fuse, and one or a plurality of series connection bodies formed by connecting an electric fuse and a resistance element in series, each one end is commonly connected to an external power supply voltage terminal, and the other ends are commonly connected to each other,
A switching element for program control and a switching element for reading connected in parallel between the common connection node and the ground terminal of the electric fuse and the serial connection body;
And a plurality of differential amplifiers for detecting the voltage level of the common connection node by each reference voltage.

  Here, in the series connection body, the resistance element may be on the external power supply voltage terminal side or on the common connection node side. The resistance element can be composed of a MOS transistor.

  A single electrical fuse and a series-connected body have the same program characteristics, but depending on the presence or absence of resistance elements and the resistance value of the resistive elements, The resistance values are different from each other. That is, even if currents are supplied simultaneously, the values of the currents flowing are different, resulting in differences in the time required for programming. As a result, the program characteristics of the single electric fuse and the serial connection body are different from each other. By adjusting the power supply voltage applied to the external power supply voltage terminal, whether the program object is a single electrical fuse or a series connection (if there are multiple series connections, which series connection is used) Can be selected. This electric fuse program includes fusing as well as high resistance due to material alteration. The resistance value of a programmed resistor, which is a parallel connection of a single electric fuse and a series connection, is adjusted according to which one is to be programmed, that is, according to the applied power supply voltage. . The operation in actual operation is the same as described above, and each differential amplifier outputs a voltage corresponding to the difference between the connection node voltage and each reference voltage, and multi-leveling is performed. According to this, the circuit scale can be reduced as compared with the case where two electrical fuse modules are arranged to realize multi-value.

The electrical fuse module according to the present invention is
A first electrical fuse formed of polysilicon having one end connected to an external power supply voltage terminal;
A second electrical fuse having one end connected to the external power supply voltage terminal and formed by siliciding a metal material on polysilicon;
A switching element for program control and a switching element for reading connected in parallel between a common connection node of the two electric fuses and a ground terminal;
And a plurality of differential amplifiers for detecting the voltage level of the common connection node by each reference voltage.

  The polysilicon electrical fuse and the polysilicon silicided electrical fuse have different program characteristics. By adjusting the power supply voltage applied to the external power supply voltage terminal, it is possible to select whether the programming target is a polysilicon electrical fuse or a polysilicon silicided electrical fuse. This electric fuse program includes fusing as well as high resistance due to material alteration. The resistance value of a programmed resistor, which is a parallel connection body of a polysilicon electric fuse and a polysilicon silicided electric fuse, depends on which one is to be programmed, that is, depending on the applied power supply voltage. Will be adjusted. The operation in actual operation is the same as described above, and each differential amplifier outputs a voltage corresponding to the difference between the connection node voltage and each reference voltage, and multi-leveling is performed. According to this, the circuit scale can be reduced as compared with the case where two electrical fuse modules are arranged to realize multi-value.

The electrical fuse module according to the present invention is
One end is connected to an external power supply voltage terminal, an electric fuse formed by siliciding a metal material on polysilicon,
A switching element for program control and a switching element for reading connected in parallel between the other end of the electric fuse and a ground terminal;
A plurality of differential amplifiers for detecting a voltage level of a connection node of the electrical fuse and the switching element by each reference voltage;

  By adjusting the power supply voltage applied to the external power supply voltage terminal or by adjusting the energization current, the degree of programming for the polysilicon silicided electric fuse is adjusted. By adjusting the power supply voltage or the energization current, it is possible to adjust the polysilicon silicidation electric fuse to a state in which only silicide is programmed or in a state in which silicide and polysilicon are programmed. This electric fuse program includes fusing as well as high resistance due to material alteration. The resistance value of the programmed resistor is adjusted according to what level is programmed, that is, according to the applied power supply voltage. The operation in actual operation is the same as described above, and each differential amplifier outputs a voltage corresponding to the difference between the connection node voltage and each reference voltage, and multi-leveling is performed. According to this, the circuit scale can be reduced as compared with the case where two electrical fuse modules are arranged to realize multi-value.

  According to the present invention, multi-value can be realized while reducing the circuit scale.

  Embodiments of an electrical fuse module according to the present invention will be specifically described below with reference to the drawings.

(Embodiment 1)
An electric fuse module according to Embodiment 1 of the present invention will be described.

FIG. 1 is a circuit diagram showing a configuration of an electric fuse module according to Embodiment 1 of the present invention. In FIG. 1, reference numerals 10 and 11 denote externally controlled power supply terminals, reference numeral 12 denotes a first electric fuse having one end connected to the external control power supply terminal 10, and reference numeral 13 denotes one end connected to the external control power supply terminal 11. This is a second electric fuse having a program characteristic different from that of the electric fuse 12. Here, the pre-program resistance value R1 ₁ of the first electric fuse 12 is higher in resistance than the pre-program resistance value R2 _{1 of} the second electric fuse 13 (R2 ₁ <R1 ₁ ). The program after the resistance value R1 ₂ of the first electrical fuse 12 is compared to the high resistance after programming the resistance value R2 ₂ of the second electrical fuse 13. That is, it is assumed that the following relationship holds.

R2 ₁ <R1 ₁ << R2 ₂ <R1 ₂
As for the voltage required for programming the electrical fuse, when the voltage necessary for programming the first electrical fuse 12 is VDD1, and the voltage necessary for programming the second electrical fuse 13 is VDD2,
VDD1 <VDD2
It shall be related. Reference numeral 14 denotes a switching element which is connected in series with the first and second electric fuses 12 and 13 and has a source connected to the ground terminal and is constituted by an NMOS transistor for program control, and 15 is turned on when reading fuse data. Switching elements 16, 17, and 18 constituted by NMOS transistors that receive the voltage at the connection node J between the parallel connection body of the first and second electrical fuses 12 and 13 and the switching element 14 for program control are input. 19 is a reference voltage of the differential amplifier 16, 20 is a reference voltage of the differential amplifier 17, and 21 is a reference voltage of the differential amplifier 18. Note that the switching element 15 for reading is smaller in size than the switching element 14 for program control used for programming. This is because a large current is not required at the time of reading as at the time of programming.

  Next, the operation of the electrical fuse module of the present embodiment having the above configuration will be described.

  First, an operation for programming the first electric fuse 12 will be described. A low-side high voltage (VDD1) is applied to the external control power supply terminal 10 connected to the first electrical fuse 12, and the external control power supply terminal 11 connected to the second electrical fuse 13 is opened for the program execution time. Keep in control. In this state, the switching element 14 for program control is turned on in response to an external signal. When the switching element 14 is turned on, a current flows from the external control power supply terminal 10 to the ground terminal via the parallel resistance of the first electric fuse 12, and the first electric fuse 12 is programmed. At this time, since the external control power supply terminal 11 is open, the second electric fuse 13 is not programmed.

Before the program control switching element 14 is turned on and the program is executed, the resistance values of the first electric fuse 12 and the second electric fuse 13 are low and the node J is at a high potential (state 1). After the first electric fuse 12 is programmed, the first electric fuse 12 is increased in resistance (R1 ₁ << R1 ₂ ), so that the potential at the node J is lowered (state 2).

  When the second electric fuse 13 is programmed, the external control power supply terminal 10 is opened for the program control time, and the high voltage (VDD2) on the higher side is applied to the external control power supply terminal 11 to switch for program control. This is realized by turning on the element 14, and the potential of the node J similarly decreases (state 3).

  When the first and second electric fuses 12 and 13 are programmed at the same time, high voltages (VDD1 and VDD2) are applied to the external control power supply terminals 10 and 11, respectively, and the switching element 14 for program control is turned on. As a result, both the first electric fuses 12 and 13 have a high resistance, so that the potential at the node J is in the lowest state (state 4).

  When the state of the electric fuse programmed as described above is read, the read switching element 15 is turned on, the parallel resistance of the first electric fuse 12 and the second electric fuse 13 and the read switching element 15. The voltage level of the node J, which is a resistance ratio with respect to the resistor, is discriminated by the three differential amplifiers 16, 17, and 18 each having a reference voltage, and output is performed. Therefore, four potential levels are generated at the node J by the selection of the programmed electric fuse, and output is performed. As described above, multi-valued electrical fuses can be realized.

(Embodiment 2)
An electric fuse module according to Embodiment 2 of the present invention will be described.

FIG. 2 is a circuit diagram showing a configuration of the electrical fuse module according to Embodiment 2 of the present invention. In addition, the same code | symbol is provided to the same thing as FIG. In FIG. 2, reference numeral 20 denotes an external control power supply terminal, 21 denotes a first electric fuse having one end connected to the external control power supply terminal 20, and 22 denotes one end connected to the external control power supply terminal 20. This is a second electric fuse having different program characteristics. Here, before programming the resistance value R1 ₁ of the first electric fuse 21, as compared to the program before the resistance R2 ₁ of the second electrical fuse 22 a high resistance (R2 ₁ <R1 _1). The program after the resistance value R1 ₂ of the first electrical fuse 21, as compared with the programmed resistance after R2 ₂ of the second electrical fuse 22 a high resistance _{(R2 1 <R1 1 << R2} 2 <R1 ₂ ).

  The voltage required for programming the electrical fuse has a relationship of VDD1 <VDD2 when the voltage required for the first electrical fuse 21 is VDD1 and the voltage required for the second electrical fuse 22 is VDD2. Shall. Reference numerals 23 and 24 are differential amplifiers each having a voltage at a connection node J between the parallel connection body of the first and second electric fuses 21 and 22 and the switching element 14 for program control as inputs, and 25 is a differential amplifier. Reference voltage 23 and 26 are reference voltages for the differential amplifier 24.

  Next, the operation of the electrical fuse module of the present embodiment having the above configuration will be described.

First, an operation for programming the first electric fuse 21 will be described. A low-side high voltage (VDD1) is applied to the external control power supply terminal 20. Next, in response to the external signal, the switching element 14 for program control is turned on. When the switching element 14 is turned on, a current flows from the external control power supply terminal 20 to the ground terminal via the parallel resistance of the first electric fuse 21 and the second electric fuse 22. At this time, the first electric fuse 21 is programmed by heating, but the second electric fuse 22 does not reach the voltage level necessary for programming, so that a current necessary for programming does not occur and is not programmed. Will remain. That is, when VDD1 is applied, only the first electric fuse 21 is programmed. After the first electric fuse 21 is programmed, the first electric fuse 21 is increased in resistance (R1 ₁ <R1 ₂ ), so that the potential at the node J becomes the high potential in the initial state where the electric fuse is not programmed. Compared to (State 1), it drops to about the middle potential (State 2).

  Similarly, the potential of the node J can be set to the lowest potential level (state 3) by programming both the first and second electrical fuses 21 and 22. For this purpose, a high voltage (VDD2) on the higher side is applied to the external control power supply terminal 20. VDD2 is a higher voltage than VDD1. The switching element 14 for program control is turned on in response to the external signal, and a current flows from the external control power supply terminal 20 to the ground terminal via the parallel resistance of the first electric fuse 21 and the second electric fuse 22, and the first Both electrical fuses 21, 22 are programmed.

  As described above, by changing the voltage level applied from the external control power supply terminal 20, the electric fuse to be programmed can be selected and the potential level of the node J can be changed to three states. Further, when reading the state, the reading switching element 15 is turned on, and the resistance ratio between the parallel resistance of the first electric fuse 21 and the second electric fuse 22 and the resistance of the reading switching element 15 is determined. The voltage level of a certain node J is discriminated by two differential amplifiers 23 and 24 each having a reference voltage, and output is performed. As described above, multi-valued electrical fuses can be realized.

(Embodiment 3)
An electric fuse module according to Embodiment 3 of the present invention will be described.

  FIG. 3 is a circuit diagram showing the configuration of the electrical fuse module according to Embodiment 3 of the present invention. In addition, the same code | symbol is provided to the same thing as FIG. In FIG. 3, 30 is an external control power supply terminal, 31 is a resistance element having one end connected to the external control power supply terminal 30, 32 is a first electric fuse having one end connected to the external control power supply terminal 30, and 33 is one end. This is a second electric fuse connected to the resistance element 31 and having the same program characteristics as the first electric fuse 33. Here, the resistance values before programming of the first electric fuse 32 and the second electric fuse 33 are the same, but the resistance element 31 is arranged in series between the second electric fuse 33 and the external control power supply terminal 30. Has been. Regarding the voltage required for programming the electric fuse, when the voltage required for the first electric fuse 32 is VDD1 and the voltage required for the second electric fuse 33 is VDD2, there is a relationship of VDD1 <VDD2. To do. Reference numerals 34 and 35 denote differential amplifiers each having as input a voltage at a connection node J between the parallel connection body of the first and second electric fuses 32 and 33 and the switching element 14 for program control, and 36 is a differential amplifier. Reference voltage 34 and 37 are reference voltages of the differential amplifier 35.

  Next, the operation of the electrical fuse module of the present embodiment having the above configuration will be described.

First, an operation for programming the first electric fuse 32 will be described. A low-side high voltage (VDD1) is applied to the external control power supply terminal 30. Next, in response to the external signal, the switching element 14 for program control is turned on. When the switching element 14 is turned on, a current flows from the external control power supply terminal 30 to the ground terminal via the first electric fuse 32, the second electric fuse 33 and the parallel resistance of the resistance element 31, and the first electric fuse 32 is programmed by heating, but in the second electric fuse 33, the voltage drops by the amount of the resistance element 31, the voltage level necessary for programming is not reached, and the current necessary for programming is not generated. Will not be left. That is, when VDD1 is applied, only the first electric fuse 32 is programmed. After the first electric fuse 32 is programmed, the resistance of the first electric fuse 32 is increased (R1 ₁ <R1 ₂ ), so that the potential of the node J becomes the high potential in the initial state where the electric fuse is not programmed. Compared to (State 1), it drops to about the middle potential (State 2).

  Similarly, the potential of node J can be brought to the lowest potential level (state 3) by programming both first and second electrical fuses 32 and 33. This is realized by applying a high voltage (VDD2) on the higher side to the external control power supply terminal 30. VDD2 is a higher voltage than VDD1. In response to the external signal, the switching element 14 for program control is turned on, and the current flows from the external control power supply terminal 30 to the ground terminal via the parallel resistance of the first electric fuse 32, the second electric fuse 33 and the resistance element 31. The first electrical fuses 32 and 33 are programmed.

  As described above, by changing the voltage level applied from the external control power supply terminal 30, it is possible to select the electric fuse to be programmed and change the potential level of the node J into three states. Further, when reading the state, the reading switching element 15 is turned on, and the resistance ratio between the parallel resistance of the first electric fuse 32 and the second electric fuse 33 and the resistance of the reading switching element 15 is determined. The voltage level of a certain node J is discriminated by two differential amplifiers 34 and 35 each having a reference voltage, and output is performed. As described above, multi-valued electrical fuses can be realized.

(Embodiment 4)
An electric fuse module according to Embodiment 4 of the present invention will be described.

FIG. 4 is a circuit diagram showing a configuration of an electrical fuse module according to Embodiment 4 of the present invention. In addition, the same code | symbol is provided to the same thing as FIG. In FIG. 4, 40 is an external control power supply terminal, 41 is a first electric fuse formed only by polysilicon having one end connected to the external control power supply terminal 40, and 42 has one end connected to the external control power supply terminal 40. This is a second electric fuse formed by siliciding a metal material on polysilicon and has the same shape but a different material. Here, before programming the resistance value R1 ₁ of the first electric fuse 41 is a high resistance compared to the program before the resistance R2 ₁ of the second electrical fuse _{42 (R2 1 <R1 1)} . The program after the resistance value R1 ₂ of the first electrical fuse 41, as compared with the programmed resistance after R2 ₂ of the second electrical fuse 42 has a high resistance _{(R2 1 <R1 1 << R2} 2 <R1 ₂ ). The voltage required for programming the electrical fuse has a relationship of VDD1 <VDD2 when the voltage required for the first electrical fuse 41 is VDD1 and the voltage required for the second electrical fuse 42 is VDD2. Shall. Reference numerals 43 and 44 denote differential amplifiers each having a voltage at a connection node J between the parallel connection body of the first and second electric fuses 41 and 42 and the switching element 14 for program control, and 45 is a differential amplifier. 43 is a reference voltage, and 46 is a reference voltage of the differential amplifier 44.

  Next, the operation of the electrical fuse module of the present embodiment having the above configuration will be described.

First, an operation for programming the first electric fuse 41 will be described. A low-side high voltage (VDD1) is applied to the external control power supply terminal 40. Next, in response to the external signal, the switching element 14 for program control is turned on. When the switching element 14 is turned on, a current flows from the external control power supply terminal 40 to the ground terminal via the parallel resistance of the first electric fuse 41 and the second electric fuse 42, and the first electric fuse 41 is heated by heating. Although being programmed, the second electrical fuse 42 does not reach the voltage level necessary for programming, so that a current necessary for programming does not occur and remains unprogrammed. That is, when VDD1 is applied, only the first electric fuse 41 is programmed. After the first electric fuse 41 is programmed, the first electric fuse 41 is increased in resistance (R1 ₁ <R1 ₂ ), so that the potential at the node J becomes the high potential in the initial state where the electric fuse is not programmed. Compared to (State 1), it drops to about the middle potential (State 2).

  Similarly, the potential of the node J is set to the lowest potential level (state 3) by programming both the first and second electric fuses 41 and 42. For this purpose, a high voltage (VDD2) on the higher side is applied to the external control power supply terminal 40. VDD2 is a higher voltage than VDD1. When a voltage is applied to one end of the first electric fuses 41 and 42, a current necessary for programming is generated, and an external signal is received to turn on the switching element 14 for program control. From the external control power supply terminal 40 to the ground terminal A current flows through the parallel resistance of the first electric fuse 41 and the second electric fuse 42, and both the first electric fuses 41 and 42 are programmed.

  As described above, by changing the voltage level applied from the external control power supply terminal 40, the timing of the electric fuse to be programmed can be changed, and the potential level of the node J can be changed to three states. Further, when reading the state, the reading switching element 15 is turned on, and the resistance ratio between the parallel resistance of the first electric fuse 41 and the second electric fuse 42 and the resistance of the reading switching element 15 is determined. The voltage level of a certain node J is discriminated by two differential amplifiers each having a reference voltage, and output is performed. As described above, multi-valued electrical fuses can be realized.

(Embodiment 5)
An electric fuse module according to Embodiment 5 of the present invention will be described.

  FIG. 5 is a circuit diagram showing a configuration of an electrical fuse module according to Embodiment 5 of the present invention. In addition, the same code | symbol is provided to the same thing as FIG. In FIG. 5, 50 is an external control power supply terminal, and 51 is an electric fuse formed by siliciding a metal material on polysilicon having one end connected to the external control power supply terminal 50. Here, the electrical fuse 51 is characterized in that it has different resistance values when programmed only with silicide and when programmed with both silicide and polysilicon. Further, if the resistance value after programming only silicide is Rs, and the resistance value after programming both silicide and polysilicon is Rsp, the following relationship is generally established.

R ₁ << Rs << Rsp
The voltage required for programming the electric fuse 51 also has a relationship of VDD1 <VDD2 when the voltage required for programming only the silicide is VDD1, and the voltage required for programming both silicide and polysilicon is VDD2. It shall be. Reference numerals 53 and 54 denote differential amplifiers each having as input a voltage at a connection node J between the parallel connection body of the electric fuse 51 and the switching element 14 for program control, 55 is a reference voltage of the differential amplifier 53, and 56 is a difference. This is the reference voltage of the dynamic amplifier 54.

  Next, the operation of the electrical fuse module of the present embodiment having the above configuration will be described.

  First, an operation for programming only the silicide of the electric fuse 51 will be described. A low-side high voltage (VDD1) is applied to the external control power supply terminal 50. Next, in response to the external signal, the switching element 14 for program control is turned on. When the switching element 14 is turned on, a current flows from the external control power supply terminal 50 to the ground terminal via the parallel resistance of the electric fuse 51, and the electric fuse 51 is programmed by heating. However, when VDD1 is applied, Fully program the silicide. However, since a current necessary for programming polysilicon is not generated and only the silicide programming is completed, the resistance value after programming becomes Rs and becomes stable.

  Next, when both the silicide and polysilicon of the electric fuse 51 are programmed, the high voltage (VDD2) on the higher side is similarly applied to the external control power supply terminal 50 to turn on the switching element 14 for program control. Is realized. Further, the resistance value after programming at that time becomes Rsp and becomes stable.

After the electrical fuse 51 is programmed only with silicide, the electrical fuse 51 is increased in resistance (R ₁ << Rs), so that the potential at the node J becomes the initial high potential (state where the electrical fuse is not programmed). Compared to 1), the voltage drops to about the middle potential (state 2).

Furthermore, by programming both the silicide and polysilicon of the electrical fuse 51, the electrical fuse 51 is further increased in resistance (R ₁ << Rs << Rsp), and the potential of the node J is set to the lowest potential level. (State 3).

  As described above, by changing the voltage level applied from the external control power supply terminal 50, the resistance level such as only silicide or both silicide and polysilicon in the electric fuse to be programmed is changed, and the potential level of the node J is changed to three. It becomes possible to change to a state. Further, when reading the state, the switching element 15 for reading is turned on, and the voltage level of the node J, which is the resistance ratio between the parallel resistance of the electric fuse 51 and the resistance of the switching element 15 for reading, is respectively referred to. Discrimination is performed by two differential amplifiers having voltage, and output is performed. As described above, multi-valued electrical fuses can be realized.

  As described above, according to the present invention, an electrical fuse capable of storing information of 1 bit or more in a small area is realized in a semiconductor memory device having an electrical fuse that outputs 1-bit data of “0” and “1”. it can.

  The electrical fuse module of the present invention can store a plurality of data in one module even when a large number of electrical fuse elements are required, for example, for RAM redundancy relief, etc. It is useful as an electrical fuse module for redundancy repair of RAM such as DRAM and SRAM.

The circuit diagram which shows the structure of the electrical fuse module in Embodiment 1 of this invention The circuit diagram which shows the structure of the electrical fuse module in Embodiment 2 of this invention The circuit diagram which shows the structure of the electrical fuse module in Embodiment 3 of this invention The circuit diagram which shows the structure of the electrical fuse module in Embodiment 4 of this invention The circuit diagram which shows the structure of the electrical fuse module in Embodiment 5 of this invention Circuit diagram showing the configuration of a conventional electric fuse device

Explanation of symbols

12, 13, 21, 22, 32, 33 Electrical fuse element 14 Switching element for program control 15 Switching element for reading 10, 20, 30, 40, 50 External control power supply terminals 16, 17, 18, 23, 24, 34, 35, 43, 44, 53, 54 Differential amplifier 31 Resistive element 41 Electrical fuse formed only of polysilicon 42 Electrical fuse formed of polysilicon and silicide 51 Electricity formed of polysilicon and silicide fuse

Claims (9)

A plurality of electrical fuses having different program characteristics, one end of which is individually connected to the external power supply voltage terminal and the other end is commonly connected;
A switching element for program control and a switching element for reading connected in parallel between a common connection node of the plurality of electrical fuses and a ground terminal;
An electrical fuse module comprising a plurality of differential amplifiers that detect the voltage level of the common connection node by each reference voltage. A plurality of electrical fuses having different program characteristics, one end connected in common to the external power supply voltage terminal and the other end connected in common;
A switching element for program control and a switching element for reading connected in parallel between a common connection node of the plurality of electrical fuses and a ground terminal;
An electrical fuse module comprising a plurality of differential amplifiers that detect the voltage level of the common connection node by each reference voltage.   3. The electric fuse module according to claim 1, wherein the plurality of electric fuses have different program characteristics due to a difference in length of a thin wire portion having an electric fuse shape. 4.   3. The electric fuse module according to claim 1, wherein the plurality of electric fuses have different program characteristics due to a difference in thickness of an electric fuse-shaped thin line portion. 4.   3. The electric fuse module according to claim 1, wherein the plurality of electric fuses have different program characteristics due to differences in both length and thickness of an electric fuse-shaped thin wire portion. 4. An electric fuse, and one or a plurality of series connection bodies formed by connecting an electric fuse and a resistance element in series, each one end is commonly connected to an external power supply voltage terminal, and the other ends are commonly connected to each other,
A switching element for program control and a switching element for reading connected in parallel between the common connection node and the ground terminal of the electric fuse and the serial connection body;
An electrical fuse module comprising a plurality of differential amplifiers that detect the voltage level of the common connection node by each reference voltage.   The electric fuse module according to claim 6, wherein the resistance element is a MOS transistor. A first electrical fuse formed of polysilicon having one end connected to an external power supply voltage terminal;
A second electrical fuse having one end connected to the external power supply voltage terminal and formed by siliciding a metal material on polysilicon;
A switching element for program control and a switching element for reading connected in parallel between a common connection node of the two electric fuses and a ground terminal;
An electrical fuse module comprising a plurality of differential amplifiers that detect the voltage level of the common connection node by each reference voltage. One end is connected to an external power supply voltage terminal, an electric fuse formed by siliciding a metal material on polysilicon,
A switching element for program control and a switching element for reading connected in parallel between the other end of the electric fuse and a ground terminal;
An electrical fuse module comprising a plurality of differential amplifiers for detecting a voltage level of a connection node of the electrical fuse and the switching element by each reference voltage.

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