A photocell for high altitude nuclear explosion environment

Abstract

The present application relates to the field of radiation protection technology in high-altitude nuclear explosion environments, and in particular to a photocell. High-energy particles in a nuclear explosion environment can cause a voltage track collapse effect in the chip circuit, resulting in chip state errors and catastrophic consequences. In order to make the chip circuit resistant to radiation, the traditional method of using capacitors to compensate for the voltage drop generated by the photocurrent has the disadvantages of complex structure, small unit charge and large volume. The present application provides a photocell, including a PN junction system and a Schottky diode; stacking PN junctions to receive X-rays to generate photocurrent, using Schottky diodes to control the current direction of the circuit to compensate for the voltage drop caused by the nuclear explosion to the chip circuit; at the same time, because the photocurrent generated by the photocell increases with the increase of the X-ray dose rate, it has adaptability, making the circuit more suitable for nuclear explosion environments; the present application has the advantages of simple structure, small photocell area and good voltage stabilization effect.

Description

Technical Field

[0001] This application relates to the technical field of anti-radiation in the high-altitude nuclear explosion environment, and particularly to a photovoltaic cell in the high-altitude nuclear explosion environment. Background Art

[0002] The damage of ground nuclear explosions is mainly shock waves and long-term nuclear radiation, while the damage of high-altitude nuclear explosions mainly comes from high-energy particles generated by the explosion. High-altitude nuclear explosions produce radiation with a relatively high dose rate, and this radiation can trigger transient photocurrents in the PN junction sensitive region of semiconductor devices. One effect of the transient photocurrent is to cause leakage current from the chip power supply to the ground. In chips with a large integration density, a large amount of power supply-ground leakage causes the chip power supply voltage to drop, resulting in problems such as the inability of the internal circuits of the chip to work properly, clock errors, and data loss, which is called the voltage rail collapse effect.

[0003] In response to the high-altitude nuclear explosion environment, in order to keep the circuit still in a normal working state and achieve the anti-radiation effect, targeted reinforcement designs of electronic components have emerged. In traditional designs, sufficient charge is stored in the form of on-chip capacitors to compensate for the voltage drop generated by the photocurrent. This traditional method of capacitance compensation has the disadvantages of a relatively complex structure, a low stored charge amount, and a large volume. Summary of the Invention

[0004] This application provides a photovoltaic cell to solve the problems of complex structure, low charge amount, and large volume existing in the existing capacitance compensation method.

[0005] The technical solution adopted in this application is as follows:

[0006] In the first aspect of this application, a photovoltaic cell is provided, including a PN junction system and a Schottky diode;

[0007] The PN junction system includes stacked PN junctions. In the stacked PN junctions, the PN junctions are connected in series, the Schottky diode is connected in reverse series with the PN junction system, the cathode of the Schottky diode serves as the positive pole of the photovoltaic cell output, and the last cathode of the PN junction system is led out as the negative pole of the photovoltaic cell output.

[0008] The number N of stacked PN junctions is related to the chip power supply voltage VCC, and the relationship is VCC - 0.3 < 0.6N - 0.4 < VCC + 0.3. For example, when the power supply voltage is 1.2V, the stacking number is 3.

[0009] The positive pole of the photovoltaic cell output is connected to the chip power supply, and the negative pole of the photovoltaic cell output is connected to the chip ground.

[0010] The Schottky diode is arranged between the photovoltaic cell stack and the circuit structure, and the Schottky diode is used to isolate the photovoltaic cell stack and the circuit structure.

[0011] In a nuclear explosion environment, the photocurrent provided by the photocell is used to stabilize the voltage of the chip.

[0012] The current provided by the photocell increases with the increase of the X-ray dose rate, which has an adaptive effect.

[0013] Optionally, the photovoltaic cell is produced on an SOI production line.

[0014] Optionally, the area of ​​the photovoltaic cell is 2-3 times the area of ​​the active region.

[0015] Another aspect of the present application provides another photovoltaic cell having a structure different from the photovoltaic cell described above, comprising:

[0016] Multiple PN junction systems and Schottky diodes;

[0017] In the multiple PN junction systems, the PN junction systems are connected in parallel, the Schottky diodes are connected in reverse series with the multiple PN junction systems, the cathodes of the Schottky diodes serve as the positive poles of the photocell output terminals, and the cathodes of the multiple PN junction systems are led out as the negative poles of the photocell output terminals.

[0018] The area of ​​the photocell is 2-3 times the area of ​​the active region.

[0019] The present application also provides a chip, in which any of the above-mentioned photoelectric cells is arranged.

[0020] The beneficial effects of adopting the technical solution of this application are as follows:

[0021] The photocell of the present application includes a plurality of stacked PN junctions and Schottky diodes. The chip circuit protected by the photocell is characterized by a PMOS tube and an NMOS tube. The cathode of the Schottky diode serves as the positive electrode of the photocell output terminal, and the last cathode of the stacked PN junction serves as the negative electrode of the photocell output terminal. The positive electrode of the output terminal of the photocell is connected to the chip power supply, and the negative electrode of the output terminal of the photocell is connected to the chip ground. In the chip, the source of the PMOS tube is connected to the power supply, the drain of the PMOS is connected to the drain of the NMOS, and the source of the NMOS is connected to the chip ground.

[0022] On the other hand, by connecting at least two groups of several stacked PN junctions in parallel in the same direction, a Schottky diode is connected in series with several stacked PN junctions in the opposite direction to form a basic photovoltaic cell group. The cathode of the Schottky diode serves as the positive electrode of the photovoltaic cell output terminal, and the last cathode of the multiple stacked PN junctions is connected to each other and led out as the negative electrode of the photovoltaic cell output terminal. The positive electrode of the photovoltaic cell output terminal is connected to the chip power supply, and the negative electrode of the photovoltaic cell output terminal is connected to the chip ground. In the chip, the source of the PMOS tube is connected to the power supply, the drain of the PMOS is connected to the drain of the NMOS, and the source of the NMOS is connected to the chip ground.

[0023] In actual chips, multiple photovoltaic groups are distributed in multiple areas of the chip, effectively reducing the burden on the power supply network.

[0024] During the period of space radiation, the photocell device is used to compensate the photocurrent to maintain the voltage stability inside the chip and realize the radiation hardening design for nuclear explosion environment. Through the above two implementation methods, the internal node voltage of the electronic components can be stably output under the hardening index condition of X-ray dose rate 10^12rad(Si) / s in a nuclear explosion environment, avoiding the track collapse effect of the circuit.

[0025] The photovoltaic cell has a simple structure and can be realized on the SOI production line without special processes; for the same dose of X-rays, the charge replenishment efficiency is several times that of traditional MOS capacitors, and the increased area is relatively small relative to the chip. Different from the fixed compensation method of traditional capacitors, the photocurrent generated by the photovoltaic cell of this application increases with the increase of X-ray dose rate, and is adaptive, so it is more suitable for reinforcement in nuclear explosion environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0027] Figure 1 This is a schematic diagram of the structure of an embodiment of the present application;

[0028] Figure 2 This is a structural schematic diagram of another embodiment of the present application;

[0029] Figure 3 A schematic diagram of a TCAD model corresponding to an equivalent circuit of an embodiment of the present application;

[0030] Figure 4 A schematic diagram comparing a photovoltaic cell circuit and a capacitor compensation circuit according to an embodiment of the present application. DETAILED DESCRIPTION

[0031] The following embodiments are described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following embodiments do not represent all implementations consistent with the present application. They are only examples of systems and methods consistent with some aspects of the present application as detailed in the claims.

[0032] See also Figure 1 , for ease of understanding the structural diagram of the following embodiments.

[0033] In a first aspect of the present application, a photocell is provided, comprising a PN junction system and a Schottky diode;

[0034] The PN junction system includes stacked PN junctions, in which PN junctions are connected in series, the Schottky diode is connected in reverse series with the PN junction system, the cathode of the Schottky diode serves as the positive electrode of the photocell output terminal, and the last cathode of the PN junction system is led out as the negative electrode of the photocell output terminal.

[0035] In the present embodiment, in the stacked PN junctions, the PN junctions and the PN junctions are connected in series in the same direction. If there is no special explanation, the PN junction stacks appearing in this application are all in the same direction, and should not be misinterpreted as stacks in the same direction and in different directions. When the photocell encounters nuclear explosion radiation, the stacked PN junctions in series can generate photocurrent, and power the chip through the connection with the chip power supply, so that the voltage of the entire circuit remains stable, thereby achieving the purpose of resisting nuclear explosion attacks. The number of stacked PN junctions is related to the chip power supply voltage. Each PN junction can generate a voltage of 0.6V, but as an isolated Schottky diode, it will consume a voltage of 0.4V. The voltage of the photocell needs to be controlled within the power supply voltage + / - 0.3V. In the present embodiment, the power supply voltage is 1.2V, so three stacked PN junctions of the photocell are required, and the output voltage is 1.4V.

[0036] In this embodiment, the Schottky diode is arranged between the photovoltaic cell stack and the circuit structure, and the Schottky diode is used to isolate the photovoltaic cell stack and the circuit structure. In a non-nuclear explosion environment, the photovoltaic cell does not affect the normal operation of the circuit structure of the chip. The Schottky diode is named after its inventor, Dr. Schottky (Schottky), and SBD is the abbreviation of Schottky Barrier Diode (Schottky Barrier Diode, abbreviated as SBD). SBD is not made using the principle of PN junction formed by contact between P-type semiconductor and N-type semiconductor, but is made using the principle of metal-semiconductor junction formed by contact between metal and semiconductor. Therefore, SBD is also called metal-semiconductor (contact) diode or surface barrier diode, which is a single carrier diode. In this embodiment, the unidirectional rectification characteristics and small forward conduction voltage characteristics of the Schottky diode are utilized.

[0037] The photocell stack described in this embodiment refers to a photoelectric circuit in which a Schottky diode is connected to a stacked PN junction, while a normal circuit structure refers to a conventional connection circuit of a PMOS tube and an NMOS tube. The photocurrent provided by the photocell is used to stabilize the voltage of the circuit connecting the PMOS tube and the NMOS tube.

[0038] In this embodiment, the improvement of the present application is highlighted. There is no improvement in the conventional connection circuit of the PMOS tube and the NMOS tube, but a core component of the photocell is connected outside the conventional connection circuit of the PMOS tube and the NMOS tube, that is, a photoelectric circuit using a Schottky diode connected to a stacked PN junction. When this part of the photoelectric circuit is exposed to nuclear explosion radiation, a photocurrent is generated and connected to the conventional connection circuit of the PMOS tube and the NMOS tube, thereby offsetting the voltage drop caused by the radiation.

[0039] Optionally, the current provided by the photocell increases as the X-ray dose rate increases, which has an adaptive effect.

[0040] Optionally, the photovoltaic cell is produced on an SOI production line.

[0041] Optionally, the area of ​​the photovoltaic cell is 2-3 times the area of ​​the active region.

[0042] See also Figure 2 , understand that another aspect of the present application provides another photovoltaic cell having a structure different from the above photovoltaic cell, including a plurality of PN junction systems and a Schottky diode;

[0043] In the multiple PN junction systems, the PN junction systems are connected in parallel, the Schottky diodes are connected in reverse series with the multiple PN junction systems, the cathodes of the Schottky diodes serve as the positive electrodes at the output terminals of the photocells, and the cathodes of the multiple PN junction systems are led out as the negative electrodes at the output terminals of the photocells;

[0044] In this embodiment, by connecting at least two sets of parallel stacked PN junctions with reverse Schottky diodes, this parallel structure is conducive to providing a larger photocurrent, thereby achieving the purpose of stabilizing the voltage.

[0045] Optionally, the area of ​​the photovoltaic cell is 2-3 times the area of ​​the active region.

[0046] The present application also provides a chip, in which any of the above-mentioned photoelectric cells is arranged.

[0047] In order to verify the beneficial effects of the present application, the comparative experiments conducted in the present application will be described in detail below, which will help to understand the essential features of the present application.

[0048] Referring to the above embodiment, a TCAD model corresponding to the equivalent circuit of the above embodiment is established. Figure 3 As shown. Through TCAD simulation, the voltage value corresponding to point V in the circuit is obtained. In the circuit designed without photocell, at an X-ray dose rate of 10^12rad(Si) / s and a duration of 20ns, the voltage value drops significantly, see Figure 4 Compared with the photovoltaic cell of the present application, the voltage value is kept stable while increasing by 0.1V, which is more conducive to stable output.

[0049] The reasonable photovoltaic cell area is 2-3 times the chip active area. Considering that the chip active area will not exceed 50% of the total area, the final photovoltaic cell design will double the chip area. And the photocurrent itself can increase with the increase of X-ray dose rate. For example, through theoretical calculation, the photovoltaic cell can provide 25-50nC / mm at a dose rate of 10^12rad(Si) / s and a duration of 100ns. 2 Therefore, the compensation method is more suitable for the case of high X-ray dose rate and plays an adaptive role.

[0050] The traditional MOS capacitor method can only provide 4nC / mm for photocurrent compensation. 2 The charge of the MOS capacitor is much smaller than that of the photocell solution. MOS capacitors can only hold fixed charges. To achieve the transient dose rate resistance index, it is necessary to 2 The active area is equipped with a 400nF capacitor (considering that the charge of the capacitor will lose 30-40% due to the insulator ionization effect under the pulse dose rate), the MOS capacitor needs to be 40 times the area of ​​the active area, which is very difficult. Although the Trench capacitor or Stack capacitor under special processing technology, the unit area mm 2 Capable of providing larger capacitance, such as Trench capacitors that can provide 80 to 250 nC / mm at a fixed voltage 2However, compared with the Trench capacitor, which uses a special processing technology, the photovoltaic cell has a simple structure and can be realized on the SOI production line without special processes.

[0051] The chip uses a distributed photocell device to effectively reduce the burden on the power supply network. The photocell has a simple structure and can be realized on the SOI production line without special processes. For the same dose of X-rays, the charge replenishment efficiency is several times that of traditional MOS capacitors, and the increase in chip area is limited. Compared with the ability of capacitors to accommodate fixed charges, the photocurrent increases with the increase of X-ray dose rate. The photocurrent compensation device of this photocell device is more suitable for reinforcement in nuclear explosion environments than MOS capacitors.

[0052] Similar parts between the embodiments provided in this application can be referenced to each other. The specific implementation methods provided above are only a few examples under the general concept of this application and do not constitute a limitation on the protection scope of this application. For those skilled in the art, any other implementation methods expanded based on the scheme of this application without creative work belong to the protection scope of this application.

Claims

1. A photovoltaic cell, characterized in that: It includes a PN junction system and a Schottky diode; The PN junction system includes stacked PN junctions, which are used to generate photocurrent when the photovoltaic cell encounters nuclear explosion radiation to stabilize the power supply voltage of the connected chip. In a non-nuclear explosion environment, the photovoltaic cell does not affect the operation of the chip's circuit structure; In the stacked PN junctions, the PN junctions are connected in series in the same direction, and the Schottky diode is connected in series in the reverse direction with the PN junction system. The cathode of the Schottky diode serves as the positive electrode of the photovoltaic cell output, and the cathode of the last PN junction in the PN junction system is led out as the negative electrode of the photovoltaic cell output; The number N of the stacked PN junctions is related to the chip power supply voltage VCC, and the relationship is VCC - 0.3 < 0.6N - 0.4 < VCC + 0.3; the provided current increases with the increase of the X-ray dose rate, having an adaptive effect.

2. The photovoltaic cell according to claim 1, characterized in that: The positive electrode of the photovoltaic cell output is connected to the chip power supply, and the negative electrode of the photovoltaic cell output is connected to the chip ground.

3. The photovoltaic cell according to claim 1, characterized in that: The Schottky diode is arranged between the photovoltaic cell stack and the circuit structure, and the Schottky diode is used to isolate the photovoltaic cell stack and the circuit structure.

4. The photovoltaic cell according to claim 1, characterized in that: The photovoltaic cell is manufactured on the SOI production line.

5. A photovoltaic cell according to claim 1, characterized in that: The area of the photovoltaic cell is 2 - 3 times the area of the chip active region.

6. A photovoltaic cell, characterized in that: It includes multiple groups of PN junction systems and a Schottky diode; the multiple groups of PN junction systems are used to generate photocurrent when the photovoltaic cell encounters nuclear explosion radiation to stabilize the power supply voltage of the connected chip. In a non-nuclear explosion environment, the photovoltaic cell does not affect the operation of the chip's circuit structure; In the multiple groups of PN junction systems, the PN junction systems are all connected in parallel, the Schottky diode is connected in series in the reverse direction with the multiple groups of PN junction systems, the cathode of the Schottky diode serves as the positive electrode of the photovoltaic cell output, and the cathodes of the multiple groups of PN junction systems are led out as the negative electrode of the photovoltaic cell output.

7. A photovoltaic cell according to claim 6, characterized in that: The positive electrode of the photovoltaic cell output is connected to the chip power supply, and the negative electrode of the photovoltaic cell output is connected to the chip ground.

8. A photovoltaic cell according to claim 6, characterized in that: The area of the photovoltaic cell is 2 - 3 times the area of the active region.

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