JPH09232614A - Radiation dose detecting semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To electrically remove the positive electric charge generated by the irradiation by a method wherein a non-volatile rewritable semiconductor element is provided. SOLUTION: In a MONOS type semiconductor element, the threshold voltage changed by the irradiation can be electrically changed. A characteristic curve 41 is the initial characteristics of the MONOS type semiconductor element, and a characteristic curve 42 is the specific character when the radiation exposure of 1×107 RAD are effected. When plus voltage of 9V of pulse width 20m/sec is applied to the gate electrode of the MONOS type semiconductor element showing the specific character of the characteristic curve 42, the specific character of characteristic curve 44 is formed. The characteristic curve 44 is same as the write-in state characteristics which are the initial characteristics of the MONOS type semiconductor element shown by the characteristic curve 43, and the positive electric charge caught in a gate insulating film by the irradiation of radiation can be electrically removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device for detecting a radiation dose in a place where radiation is applied, such as outer space or a nuclear reactor, and in particular, electric charge generated by the irradiation can be electrically removed for regeneration. The present invention relates to the structure of a semiconductor device for detecting radiation dose.

[0002]

2. Description of the Related Art When a MOS semiconductor device is used in an environment such as outer space or a nuclear reactor where radiation is emitted, malfunction occurs when the total radiation dose (total dose amount) reaches about 1 × 10 ⁶ RAD. .

The cause of the malfunction of this MOS semiconductor device under irradiation of radiation will be described with reference to FIGS. 12 and 13.

FIG. 12 is a graph showing a change characteristic of a threshold voltage of an N-channel type MOS semiconductor device due to radiation irradiation. The horizontal axis shows the gamma ray irradiation amount, and the vertical axis shows the change amount (ΔVth) of the threshold voltage due to the radiation irradiation.

As shown in FIG. 12, as the radiation dose increases, the threshold voltage of the N-channel MOS semiconductor device decreases. Therefore, the leak current of the N-channel MOS semiconductor device increases.

FIG. 13 is a graph showing the change characteristics of the threshold voltage of a P-channel MOS semiconductor device due to radiation irradiation. The horizontal axis shows the gamma ray irradiation amount, and the vertical axis shows the change amount (ΔVth) of the threshold voltage due to the radiation irradiation.

As shown in FIG. 13, as the radiation dose increases, the threshold voltage of the P-channel MOS semiconductor device increases. For this reason, the P-channel type MOS semiconductor element is turned off and becomes inoperable.

As described above, when the MOS semiconductor element is used under the environment where the radiation is applied, the MOS semiconductor of the N-channel type MOS semiconductor element and the P-channel type MOS semiconductor element is increased with the increase of the radiation dose. The amount of change in the threshold voltage of the device also becomes large.

Further, since the threshold voltage shift direction is negative, it is known that the charges generated by the radiation irradiation are positive charges, and it has been confirmed that the positive charges are generated in the gate oxide film. .

For this reason, the system constituted by the MOS semiconductor device becomes inoperable when used in a radiation irradiation environment and becomes inoperable when the radiation irradiation amount increases.

As a measure against the inoperability of this MOS semiconductor device, in the prior art, a method of removing the positive charges generated in the gate oxide film by applying a heat treatment at a temperature of about 300 ° C. to 400 ° C. is considered. .

However, it is difficult to completely remove the positive charges even by this heat treatment method, and the total irradiation amount is limited, so that the system needs to be replaced.

Further, there is a problem that the system becomes large because an apparatus for performing the heat treatment is required. Furthermore, since the conventional apparatus cannot know the radiation dose, it is impossible to know the time when the apparatus cannot be operated. For this reason, it is necessary to perform the heat treatment at regular intervals, which is a problem because the effect is insufficient under the environment where the radiation dose is constantly changed.

[0014]

In a system using a MOS semiconductor element, as shown in the graphs of FIG. 12 and FIG. 13, a positive charge is generated in the gate oxide film of the MOS semiconductor element due to the irradiation of radiation, and the system operates. Cause a defect.

An object of the present invention is to solve the above problems and
It is an object of the present invention to provide a semiconductor device that detects a radiation dose for grasping a radiation dose before a system including a MOS semiconductor element causes a malfunction, thereby preventing a malfunction of the system.

Further, an object of the present invention is to solve the above problems and provide a semiconductor device for detecting a radiation dose in a place where radiation is irradiated, such as outer space or a nuclear reactor, and in particular, it is generated by radiation irradiation. It is an object of the present invention to provide a radiation dose detecting semiconductor device capable of electrically removing positive charges and reproducing.

[0017]

In order to achieve the above object, the radiation dose detecting semiconductor device of the present invention employs the following means.

The semiconductor device for detecting radiation dose according to the present invention is characterized by including an electrically rewritable nonvolatile semiconductor element.

The radiation dose detecting semiconductor device according to the present invention is a non-volatile semiconductor element in which the gate insulating film is a tunnel oxide film, a silicon nitride film and a top oxide film and is electrically rewritable. It is characterized by being provided.

The semiconductor device for detecting radiation dose according to the present invention is a non-volatile semiconductor element in which the gate insulating film is a tunnel oxide film, a silicon nitride film, and a top oxide film and is electrically rewritable. ,
And a resistor.

The radiation dose detecting semiconductor device according to the present invention is a non-volatile semiconductor element in which a gate insulating film is a tunnel oxide film, a silicon nitride film, and a top oxide film and is electrically rewritable. ,
It is characterized by including a resistor and a NAND circuit.

The radiation dose detecting semiconductor device according to the present invention is an electrically rewritable MONOS type semiconductor device in which the gate insulating film is a tunnel oxide film, a silicon nitride film and a top oxide film as a nonvolatile semiconductor device. ,
It is characterized by including a resistor and an inverter circuit.

The semiconductor device for radiation dose detection according to the present invention is a non-volatile semiconductor element in which a gate insulating film is a tunnel oxide film, a silicon nitride film, and a top oxide film and is electrically rewritable. ,
And a MOS semiconductor element.

The semiconductor device for detecting radiation dose according to the present invention is an electrically rewritable MONOS type semiconductor element having a gate insulating film composed of a tunnel oxide film, a silicon nitride film and a top oxide film as a nonvolatile semiconductor element, MO
It is characterized by including an S semiconductor element and a NAND circuit.

The radiation dose detecting semiconductor device according to the present invention is an electrically rewritable MONOS type semiconductor element having a gate insulating film composed of a tunnel oxide film, a silicon nitride film and a top oxide film as a nonvolatile semiconductor element. MO
It is characterized by including an S semiconductor element and an inverter circuit.

A radiation dose detecting semiconductor device according to the present invention is an electrically rewritable MONOS type semiconductor device having a gate insulating film made of a tunnel oxide film, a silicon nitride film and a top oxide film as a non-volatile semiconductor device. A semiconductor device including a resistor and a peripheral circuit provided in a shield wall which is not irradiated with radiation are provided.

The radiation dose detecting semiconductor device of the present invention is a non-volatile semiconductor element in which the gate insulating film is a tunnel oxide film, a silicon nitride film, and a top oxide film, and is a rewritable MONOS type semiconductor element. ,
A semiconductor device including a MOS semiconductor element and a peripheral circuit provided in a shield wall which is not irradiated with radiation are provided.

The radiation dose detecting semiconductor device according to the present invention is a non-volatile semiconductor element in which a gate insulating film is a tunnel oxide film, a silicon nitride film, and a top oxide film and is electrically rewritable. ,
A semiconductor device including a MOS semiconductor element, and a control circuit including a power supply circuit, a write voltage generation circuit, and an arithmetic circuit provided in a shield wall that is not irradiated with radiation are provided.

As described above, the radiation dose detecting semiconductor device of the present invention uses the electrically rewritable nonvolatile semiconductor element. Therefore, the positive charges generated in the gate insulating film of the nonvolatile semiconductor element due to the irradiation of radiation can be removed by applying a positive voltage to the gate electrode of the nonvolatile semiconductor element.

As a result, the radiation dose detecting semiconductor device of the present invention can be reused by electrically removing the positive charges accumulated by the radiation irradiation.

Further, in the radiation dose detecting semiconductor device of the present invention, the amount of positive charges accumulated in the non-volatile semiconductor element is set to a threshold value by a resistor not affected by radiation or accumulation of positive charges. P-channel MO with high voltage
The detection is performed by utilizing the conduction resistance of the S semiconductor element. Therefore, it can be used as a semiconductor device for detecting a radiation dose.

As described above, the radiation dose detecting semiconductor device of the present invention can be reused because it can electrically remove the positive charges, and at the same time, before the system constituted by the MOS semiconductor elements malfunctions. You can know the radiation dose. Therefore, malfunction of the system can be prevented.

Further, in the semiconductor device for detecting radiation dose of the present invention, since the heat treatment which has been conventionally required is not required, a special device is not required and the system can be downsized.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described below with reference to the drawings. First, the configuration of the radiation dose detecting semiconductor device according to the embodiment of the present invention will be described with reference to the circuit diagram of FIG.

The semiconductor device for detecting radiation dose of the present invention is a non-volatile semiconductor element MON as shown in FIG.
It is composed of an OS type semiconductor element 1 and a resistor 2 made of polycrystalline silicon whose resistance value change amount is small due to radiation irradiation.

The connection state in this circuit is MONOS.
The source 33 of the type semiconductor element 1 is connected to the ground potential (GND), the drain 32 is connected to one terminal of the resistor 2 and the detection terminal, and the gate electrode 37 is a write when writing the MONOS type semiconductor element 1. It is connected to the voltage (Vpp) and is usually connected to the ground potential (GND). Also,
The other terminal of the resistor 2 is connected to a positive voltage (Vcc).

Next, regarding the structure and characteristics of the MONOS type semiconductor element 1 constituting the radiation dose detecting semiconductor device of the embodiment of the present invention shown in FIG. 1, FIG. 2, FIG. 3 and FIG. 4 are used. Explain.

FIG. 2 is a sectional view showing the structure of the MONOS type semiconductor element 1 which constitutes the radiation dose detecting semiconductor device of the present invention. The MONOS type semiconductor device 1 includes a tunnel oxide film 34 having a film thickness of 2.4 nm formed on a P type semiconductor substrate 31, and a silicon nitride film having a film thickness of 4.0 nm formed on the tunnel oxide film 34. An ONO (Ox composed of a film 35 and a top oxide film 36 formed on the silicon nitride film 35 and having a film thickness of 4.0 nm).
ide Nitride Oxide) structure gate insulating film 38,
A gate electrode 37 formed on the gate insulating film 38 is provided.

Further, a P-type silicon substrate 31 aligned with the gate electrode 37 is provided with a drain 32 and a source 33 made of an N-type high-concentration impurity layer to form the MONOS type semiconductor device 1.

In this MONOS type semiconductor device, by applying a positive voltage (denoted as Vpp) to the gate electrode 37, electrons are injected from the P type semiconductor substrate 31 into the gate insulating film 38 having the ONO film structure. The transistor operation can be enhanced.

Conversely, when a negative voltage is applied to the gate electrode 37, holes are injected from the P-type semiconductor substrate 31 into the gate insulating film 38 having the ONO film structure, and the transistor operation can be a depletion operation. . Therefore, it can be used as an electrically rewritable nonvolatile semiconductor element.

Next, changes in the threshold voltage (sometimes referred to as Vth) when the MONOS type semiconductor element is irradiated with radiation will be described with reference to the graph of FIG.

In the graph of FIG. 3, the horizontal axis represents the radiation dose of gamma rays using Co60 as the radiation source, and the vertical axis represents the threshold voltage (Vth) of the MONOS type semiconductor device.

As is clear from the graph of FIG. 3, M
The threshold voltage of the ONOS type semiconductor element changes substantially in proportion to the radiation dose. This threshold voltage change amount is expressed by an empirical formula as follows: Vth = −0.485 · log (Tdose) +2.445 (1) Vth: Threshold voltage of MONOS type semiconductor device
(V) Tdose: It can be expressed as a radiation dose (RAD).

If the circuit is constructed with the threshold voltage of the MONOS type semiconductor element in the above equation (1) as the sense level, the radiation dose when the threshold voltage is reached is obtained from the equation (1). Therefore, the MONOS type semiconductor element can be used as a semiconductor device for radiation dose detection.

Further, in the MONOS type semiconductor device, it is possible to electrically change the threshold voltage changed by the irradiation of radiation. This characteristic will be described with reference to the graph of FIG.

FIG. 4 is a graph showing the correlation between the gate voltage and the drain current of the MONOS type semiconductor device. The horizontal axis represents the gate voltage applied to the gate electrode 37, and the vertical axis represents the drain current.

A characteristic curve 41 shown in FIG. 4 shows the initial characteristic of the MONOS type semiconductor device, and a characteristic curve 42 shows the radiation dose 1
The characteristics are shown when irradiation with × 10 ⁷ RAD is performed. Similar to the MOS semiconductor device of FIGS. 12 and 13 described in the prior art, holes of electron-hole pairs generated by radiation irradiation are trapped in the gate insulating film 38, positive charges are accumulated, and characteristics in the negative direction are generated. Shifts.

MONOS showing the characteristic of the characteristic curve 42.
When a positive voltage of 9 V and a pulse width of 20 msec is applied to the gate electrode of the semiconductor device, the characteristic curve 44 is obtained. This is because by applying a positive voltage to the gate electrode, holes trapped in the gate insulating film due to radiation irradiation are rejected to the P-type semiconductor substrate, and electrons are further emitted from the P-type semiconductor substrate into the gate insulating film. Because it was injected into.

The characteristic curve 44 is the same as the characteristic in the written state which is the initial characteristic of the MONOS type semiconductor device shown by the characteristic curve 43, and the positive charges trapped in the gate insulating film by the irradiation of radiation are electrically removed. It shows that it is possible.

That is, the MONOS type semiconductor device can operate normally even if it is electrically rewritten even in an environment where it is irradiated with radiation. This means that if the MONOS type semiconductor element is used as the radiation dose detecting semiconductor device of the present invention, it can be reused by a rewriting process with a voltage.

A more detailed embodiment of the radiation dose detecting semiconductor device of the present invention using such a MONOS type semiconductor element will be described more specifically with reference to the circuit diagram of FIG.

The semiconductor device for detecting radiation dose of the present invention is an MO device having a channel width of 10 μm and a channel length of 2 μm.
It is composed of a NOS type semiconductor element 1 and a resistor 2 made of polycrystalline silicon having a resistance value of 150 KΩ and having a small resistance value change amount due to radiation irradiation.

When the resistance value of the resistor 2 is 150 KΩ, the detection voltage in the circuit diagram of FIG. 1 is a positive voltage (V
cc) level, but the radiation dose increased and MO
The threshold voltage (Vth) of the NOS type semiconductor device is −0.
At about 5V, the detection voltage becomes the ground potential (GND) level.

The radiation dose when the threshold voltage of this MONOS type semiconductor device is -0.5 V is 1 × 10 ⁶ RAD according to the equation (1).

When the detected voltage reaches the ground potential (GND), the writing voltage (Vpp) is applied to the gate electrode of the MONOS type semiconductor element 1 at 9 V with a pulse width of 1 ms, thereby initializing the voltage. Return to the threshold voltage. After that, by setting the gate electrode to the ground potential (GND), the threshold value of the MONOS type semiconductor element changes again according to the formula (1) according to the radiation dose.

By repeating this operation, the radiation dose is integrated, so that the total radiation dose can be known.

As described above, since the MONOS type semiconductor element 1 and the resistor 2 form an inverter circuit, the resistor 2
Depending on the resistance value of the MONOS type semiconductor element 1 of the formula (1)
It is possible to detect the threshold voltage Vth. Therefore, it is possible to know the desired radiation dose by changing the resistance value of the resistor 2.

Next, the configuration of the radiation dose detecting semiconductor device according to the embodiment of the present invention, which is different from the above description, will be described with reference to the circuit diagram of FIG.

As shown in FIG. 5, a circuit is composed of the MONOS type semiconductor element 1, the resistor 2, the pulse generating circuit 6 and the NAND circuit 5. The source of the MONOS type semiconductor element 1 is connected to the ground potential (GND), the drain is connected to one terminal of the resistor 2 and the input 5b of the NAND circuit 5, and the gate electrode is used for writing the MONOS type semiconductor element 1. Is connected to the write voltage (Vpp) and is usually connected to the ground potential (GND). Also, the resistor 2
The other terminal of is connected to a positive voltage (Vcc).

The MONOS type semiconductor device 1 and the resistor 2 have the same connection as shown in FIG. 1, the output is connected to the input 5b of the NAND circuit 5, and the output of the pulse generating circuit 6 is NA.
It is connected to the input 5a of the ND circuit 5. For this reason, FIG.
The pulse generated by the pulse generation circuit 6 is output as the initial output of the circuit shown in FIG.

When the radiation dose becomes 1 × 10 ⁶ RAD, the input 5b of the NAND circuit 5 becomes the ground potential (GND) level, so that the output becomes the ground potential (GND) level and the oscillation stops. This gives a radiation dose of 1 x 1
It is possible to know that 0 ⁶ RAD has been reached.

As described above, the circuit of the semiconductor device for detecting radiation dose according to the present invention has a feature that the radiation dose can be known by stopping the oscillation of the output.

Next, the configuration of the radiation dose detecting semiconductor device according to the embodiment of the present invention, which is different from the above description, will be described with reference to the circuit diagram of FIG.

As shown in FIG. 6, the MONOS type semiconductor element 1, the resistor 2 and the inverter circuit 7 constitute the circuit. The source of the MONOS type semiconductor element 1 is connected to the ground potential (GND), the drain is connected to one terminal of the resistor 2 and the inverter circuit 7, and the gate electrode is a write voltage when writing the MONOS type semiconductor element 1. It is connected to (Vpp) and is usually connected to the ground potential (GND). The other terminal of the resistor 2 is connected to a positive voltage (Vcc).

The MONOS type semiconductor element 1 and the resistor 2 are in the same connection state as shown in FIG. 1, and the initial output of the radiation dose detecting semiconductor device of the embodiment shown in FIG.
The ground potential (GND) level is output.

When the radiation dose becomes 1 × 10 ⁶ RAD, the input of the inverter circuit 7 becomes the GND level, and the output becomes the Vcc level. This makes it possible to know that the radiation dose has reached 1 × 10 ⁶ RAD.

As described above, the radiation dose detecting semiconductor device according to the embodiment of the present invention stabilizes radiation by amplifying and outputting the output voltage from the MONOS type semiconductor element 1 and the resistor 2 by the inverter circuit 7. It has the feature that it can detect the irradiation dose.

Next, the configuration of the embodiment of the semiconductor device for detecting radiation dose of the present invention, which is different from the above description, will be described with reference to the circuit diagram of FIG.

As shown in FIG. 7, a circuit is composed of the MONOS type semiconductor element 1 and the P channel type semiconductor element 8.

The connection state in this embodiment is MON.
The source 33 of the OS type semiconductor element 1 is at the ground potential (GND).
, The drain 32 is connected to the drain 81 of the P-channel type semiconductor element 8 and the detection terminal, and the gate electrode 37 is connected to the writing voltage (Vpp) when writing the MONOS type semiconductor element 1, and is usually grounded. It is connected to the electric potential (GND). Further, the source 82 of the P-channel semiconductor element 8 is connected to the positive potential (Vcc), and the gate electrode 83 is connected to the ground potential (GND). And M
The ONOS type semiconductor element 1 and the P channel type semiconductor element 8 form an inverter circuit.

The P-channel type MOS semiconductor element 8 has a channel width of 6 μm and a channel length of 18 μm, and the conduction resistance of the P-channel type MOS semiconductor element 8 is set to 150 KΩ. Therefore, the initial output of the inverter circuit composed of the MONOS type semiconductor element 1 and the P-channel type semiconductor element 8 is a positive potential (Vcc) level, and the Vcc level can be detected at the detection terminal.

The P-channel type MOS semiconductor element 8 forming an inverter circuit together with the MONOS type semiconductor element 1 is shown in FIG.
As shown in 3 for the change in threshold voltage due to radiation irradiation, the threshold voltage is increased due to radiation irradiation. For this reason, the conduction resistance also increases with the radiation dose and is 200 KΩ.
About.

When the radiation dose reaches 5 × 10 ⁵ RAD, the output of the inverter circuit composed of the MONOS type semiconductor element 1 and the P channel type semiconductor element 8 is at the ground potential G.
ND level. This gives a radiation dose of 5 x 1
It is possible to know that the 0 ⁵ RAD has been reached.

As described above, in the circuit of the present invention, by using the P-channel type semiconductor element 8 whose threshold voltage is increased by radiation irradiation, the P-channel type semiconductor element 8 and the MONOS type semiconductor element 1 are configured. The radiation dose can be known by detecting the output detection of the inverter circuit.

Next, the configuration of the radiation dose detecting semiconductor device according to the embodiment of the present invention, which is different from the above description, will be described with reference to the circuit diagram of FIG.

As shown in FIG. 8, a circuit is constituted by the MONOS type semiconductor element 1, the P channel type semiconductor element 8, the pulse generating circuit 6 and the NAND circuit 5. The source of the MONOS type semiconductor device 1 is connected to the ground potential (GND),
The drain is the drain of the P-channel semiconductor element 8 and the NA.
It is connected to the input 5b of the ND circuit 5, and the gate electrode is connected to the write voltage (Vpp) when writing the MONOS type semiconductor element 1, and is usually connected to the ground potential (GND). Furthermore, the source of the P-channel semiconductor element 8 is connected to the positive potential (Vcc), and the gate electrode is connected to GND.

The P-channel MOS semiconductor element 8 is manufactured with a channel width of 6 μm and a channel length of 18 μm, and the conduction resistance of the P-channel MOS semiconductor element 8 is set to 150 KΩ. The output of the pulse generation circuit 6 is connected to the input 5a of the NAND circuit 5, and the P-channel semiconductor element 8 and the MON are connected.
The output of the OS type semiconductor element 1 is the input 5 of the NAND circuit 5.
b. Therefore, as the initial output of the circuit shown in FIG. 8, the pulse generated by the pulse generation circuit 6 is output.

The P-channel type MOS semiconductor element 8 forming an inverter circuit together with the MONOS type semiconductor element 1 is shown in FIG.
As shown in 3 for the change in threshold voltage due to radiation irradiation, the threshold voltage is increased due to radiation irradiation. For this reason, the conduction resistance also increases with the radiation dose and is 200 KΩ.
About.

When the radiation dose becomes 5 × 10 ⁵ RAD, the input 5b of the NAND circuit 5 becomes the GND level, so that the output becomes the GND level and the oscillation stops. This allows
It is possible to know that the radiation dose has reached 5 × 10 ⁵ RAD.

As described above, the semiconductor device for detecting radiation dose according to the embodiment of the present invention has a feature that the radiation dose can be known by stopping the oscillation of the output.

Next, the structure of the radiation dose detecting semiconductor device according to the embodiment of the present invention, which is different from the above description, will be described with reference to the circuit diagram of FIG.

As shown in FIG. 9, the MONOS type semiconductor element 1, the P channel type MOS semiconductor element 8 and the inverter circuit 7 constitute a circuit. The source of the MONOS type semiconductor element 1 is connected to the ground potential (GND), the drain is connected to the drain of the P-channel type semiconductor element 8 and the inverter circuit 7, and the gate electrode is written when writing the MONOS type semiconductor element 1. It is connected to the voltage (Vpp) and is usually connected to the ground potential (GND). Furthermore, the source of the P-channel semiconductor element 8 is connected to the positive potential (Vcc), and the gate electrode is connected to the ground potential (GN
Connect to D).

The MONOS type semiconductor device 1 and the P channel type MOS semiconductor device 8 have the same structure as shown in FIG.
A GND level is output as the initial output of the circuit shown in FIG.

When the radiation dose becomes 5 × 10 ⁵ RAD, the input of the inverter circuit 7 becomes the GND level, so that the output becomes the positive potential (Vcc) level. This makes it possible to know that the radiation dose has reached 5 × 10 ⁵ RAD.

Next, the configuration of the radiation dose detecting semiconductor device according to the embodiment of the present invention, which is different from the above description, will be described with reference to the circuit diagram of FIG.

As shown in FIG. 10, the MONOS type semiconductor element 1 under the environment of being irradiated with radiation, the resistor 2 made of polycrystalline silicon whose resistance value change little due to the irradiation of radiation, and covered with lead or the like. A circuit is composed of the inverter circuit 7 inside the shield wall 9. MONOS
The source of the semiconductor device 1 is connected to the ground potential (GND), the drain is connected to one terminal of the resistor 2 and the inverter circuit 7, and the gate electrode is the write voltage (Vpp) when writing the MONOS semiconductor device 1. ), And is usually connected to the ground potential (GND). The other terminal of the resistor 2 is connected to a positive voltage (Vcc).

In the embodiment shown in FIG. 10, the radiation detection method is the same as that of the embodiment shown in FIG. 6, but under the radiation environment, the MONOS type semiconductor element 1 for detecting the radiation dose and the influence of the radiation irradiation. The accuracy is improved because there is only the resistor 2 made of polycrystalline silicon with a small amount. It is effective to carry out the method in this embodiment in an environment where wiring to the outside such as a nuclear reactor is possible.

Next, the configuration of the semiconductor device for detecting radiation dose in the embodiment of the present invention which is different from the above description is shown in FIG.
This will be described with reference to the circuit diagram of FIG.

As shown in FIG. 11, the MONOS type semiconductor element 1 and the resistor 2 under the environment where the radiation is applied,
Control circuit 1 inside shield wall 9 covered with lead, etc.
The circuit is composed of 0s.

The embodiment shown in FIG. 11 is the same as the embodiment shown in FIG. 10, and in the radiation environment, the MONOS type semiconductor element 1 for detecting the radiation dose and the polycrystalline silicon which is less affected by the radiation dose are used. There is only the resistor 2. Then, the control circuit 10 provided inside the shield wall 9 can detect the radiation dose without being affected by radiation such as writing to the MONOS type semiconductor element 1 or changing the Vcc level to change the detection amount. it can.

As a different embodiment from the embodiment of the semiconductor device for detecting radiation dose shown in FIG. 11,
The control circuit 10 may be composed of a power supply circuit, a write voltage generation circuit, an arithmetic circuit, and a voltage detection circuit.

In this embodiment, the voltage output from the MONOS type semiconductor element 1 and the resistor 2 is detected by the voltage detection circuit constituting the control circuit 10, and the result is calculated by the arithmetic circuit to calculate the radiation dose. To detect. When the detected irradiation amount becomes 1 × 10 ⁵ RAD, the write voltage generating circuit is driven to write the MONOS type semiconductor element 1. By repeating the detection of the radiation dose and the writing of the MONOS type semiconductor element 1, the total amount of the radiation dose can be known from the number of repetitions.

In the embodiments of the present invention described above, the MONOS type semiconductor element is used as the non-volatile semiconductor element. However, the non-volatile semiconductor element is an electrically rewritable element, the MNOS type semiconductor element. A device or a floating semiconductor device is also possible. Also, as the resistor, the resistor formed of polycrystalline silicon, which is less affected by the radiation dose, has been described, but similarly, the pinch-off resistor or the oxide film formed in the semiconductor substrate, which is less affected by the radiation dose, is used. The same applies when a resistor in which the influence of the electric charges is suppressed is used.

[0095]

As is apparent from the above description, the semiconductor device for detecting radiation dose according to the present invention uses a nonvolatile semiconductor element that is electrically rewritable, and therefore is non-volatile by irradiation with radiation. The positive charges generated in the gate insulating film of the semiconductor element can be electrically removed by applying a positive voltage to the gate electrode of the non-volatile semiconductor element. It can be repeatedly used as a semiconductor device for dose detection.

Further, in the radiation dose detecting semiconductor device of the present invention, the amount of the positive charges accumulated in the non-volatile semiconductor element is controlled by the resistor not affected by the radiation or the threshold voltage by the accumulation of the positive charges. Since the detection is performed by utilizing the higher conduction resistance of the P-channel type MOS semiconductor element, a highly accurate radiation dose detecting semiconductor device can be obtained.

Further, the radiation dose detecting semiconductor device of the present invention can be reused because it can electrically remove positive charges, and requires a special device because it does not require the heat treatment which has been conventionally required. The system can be made small.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a radiation dose detecting semiconductor device according to an embodiment of the present invention.

FIG. 2 is a non-volatile semiconductor element MON that constitutes a radiation dose detection semiconductor device according to an embodiment of the present invention.
It is sectional drawing which shows the structure of an OS type semiconductor element.

FIG. 3 is a graph showing a correlation between a radiation dose and a threshold voltage of a MONOS type semiconductor element, which is a nonvolatile semiconductor element that constitutes the radiation dose detection semiconductor device of the present invention.

FIG. 4 is a graph showing a correlation between a gate voltage and a drain current before and after radiation irradiation of a MONOS type semiconductor element, which is a nonvolatile semiconductor element that constitutes the radiation dose detection semiconductor device of the present invention.

FIG. 5 is a circuit diagram showing a configuration of a radiation dose detecting semiconductor device according to an embodiment of the present invention.

FIG. 6 is a circuit diagram showing a configuration of a radiation dose detecting semiconductor device according to an embodiment of the present invention.

FIG. 7 is a circuit diagram showing a configuration of a radiation dose detecting semiconductor device according to an embodiment of the present invention.

FIG. 8 is a circuit diagram showing a configuration of a radiation dose detecting semiconductor device according to an embodiment of the present invention.

FIG. 9 is a circuit diagram showing a configuration of a radiation dose detecting semiconductor device according to an embodiment of the present invention.

FIG. 10 is a circuit diagram showing a configuration of a radiation dose detecting semiconductor device according to an embodiment of the present invention.

FIG. 11 is a circuit diagram showing a configuration of a radiation dose detecting semiconductor device according to an embodiment of the present invention.

FIG. 12 is a graph showing the correlation between the dose of radiation and the amount of change in threshold voltage of an N-channel MOS semiconductor device in the prior art.

FIG. 13 is a graph showing the correlation between the dose of radiation and the amount of change in threshold voltage of a P-channel type MOS semiconductor device in the prior art.

[Explanation of symbols]

 1 MONOS type semiconductor element 2 resistor 5 NAND circuit 6 pulse generation circuit 7 inverter circuit 8 P-channel type MOS semiconductor element 9 shield wall

Claims (11)

[Claims] 1. A semiconductor device for radiation dose detection, comprising a non-volatile semiconductor element that is electrically rewritable. 2. A radiation dose detecting device, comprising a non-volatile semiconductor element, which is an electrically rewritable MONOS type semiconductor element whose gate insulating film comprises a tunnel oxide film, a silicon nitride film and a top oxide film. Semiconductor device. 3. A non-volatile semiconductor device comprising an electrically rewritable MONOS type semiconductor device whose gate insulating film is composed of a tunnel oxide film, a silicon nitride film and a top oxide film, and a resistor. Semiconductor device for detecting radiation dose. 4. A non-volatile semiconductor device comprising an electrically rewritable MONOS type semiconductor device whose gate insulating film is a tunnel oxide film, a silicon nitride film and a top oxide film, a resistor and a NAND circuit. A semiconductor device for detecting a radiation dose, which is characterized by: 5. An electrically rewritable MONOS type semiconductor element having a gate insulating film made of a tunnel oxide film, a silicon nitride film, and a top oxide film, a resistor, and an inverter circuit as a nonvolatile semiconductor element. A semiconductor device for detecting a radiation dose, which is characterized by: 6. A non-volatile semiconductor device comprising an electrically rewritable MONOS type semiconductor device whose gate insulating film is composed of a tunnel oxide film, a silicon nitride film and a top oxide film, and a MOS semiconductor device. Semiconductor device for detecting radiation dose. 7. A non-volatile semiconductor device comprising an electrically rewritable MONOS type semiconductor device whose gate insulating film is composed of a tunnel oxide film, a silicon nitride film and a top oxide film, a MOS semiconductor device and a NAND circuit. A semiconductor device for detecting radiation dose, which is characterized in that: 8. A non-volatile semiconductor device comprising an electrically rewritable MONOS type semiconductor device whose gate insulating film is composed of a tunnel oxide film, a silicon nitride film and a top oxide film, a MOS semiconductor device and an inverter circuit. A semiconductor device for detecting radiation dose, which is characterized in that: 9. A semiconductor device comprising a non-volatile semiconductor element, which is an electrically rewritable MONOS type semiconductor element whose gate insulating film is composed of a tunnel oxide film, a silicon nitride film and a top oxide film, and a resistor. A semiconductor device for radiation dose detection, comprising: a peripheral circuit provided inside a shield wall that is not irradiated with radiation. 10. A semiconductor device comprising an electrically rewritable MONOS type semiconductor element whose gate insulating film is a tunnel oxide film, a silicon nitride film and a top oxide film as a non-volatile semiconductor element, and a MOS semiconductor element. A semiconductor device for radiation dose detection, comprising: a peripheral circuit provided inside a shield wall that is not irradiated with radiation. 11. A semiconductor device comprising a non-volatile semiconductor element, an electrically rewritable MONOS type semiconductor element whose gate insulating film is a tunnel oxide film, a silicon nitride film and a top oxide film, and a MOS semiconductor element. A semiconductor device for radiation dose detection, comprising: a power supply circuit provided in a shield wall that is not irradiated with radiation; a write voltage generation circuit; a control circuit including an arithmetic circuit and a voltage detection circuit.