A lateral PNP transistor based on polysilicon thermal gate and a repair method thereof

Abstract

The present invention relates to a lateral PNP transistor based on a polysilicon hot gate, comprising a polysilicon hot gate, a base region, an epitaxial layer, a buried layer, a substrate, and an electrode connected in sequence. The polysilicon hot gate is a circular ring with an opening, located at the center of the base region, and the emitter electrode is located at the center of the polysilicon hot gate ring. It also relates to a method for preparing a lateral PNP transistor based on a polysilicon hot gate, including a polysilicon hot gate layout design, processing according to the polysilicon hot gate layout design, and a process of manufacturing a lateral PNP transistor based on a polysilicon hot gate. It also relates to a method for repairing a lateral PNP transistor based on a polysilicon hot gate, including a defect characterization, obtaining a repair voltage, and implementing a repair process. The present invention sets a polysilicon hot gate electrode to realize real-time repair of ionizing radiation-induced defects in a radiation environment, separate ionizing radiation-induced defects, and improve the total dose resistance of the lateral PNP transistor.

Description

Technical Field

[0001] The invention belongs to the technical field of radiation resistance reinforcement of electronic devices, and in particular relates to a lateral PNP transistor based on a polysilicon thermal gate and a repair method thereof. Background Art

[0002] The development of aerospace technology has put forward higher requirements for space electronic devices, which require stronger resistance to total dose radiation. As an important component of space electronic systems, the radiation effect and reinforcement technology of bipolar devices have always been hot issues in the research field. Among bipolar devices, compared with vertical NPN transistors, lateral PNP transistors have a large base width and low doping concentration, and carriers are transported laterally in the base region. Therefore, the carrier transport process is susceptible to ionizing radiation-induced defects, making lateral PNP transistors the most sensitive to total dose effects. However, the existing lateral PNP transistor design reinforcement methods mainly include subsurface structure design, field plate design, F-doped base oxide layer and other methods. These methods are mainly based on reducing the impact of radiation-induced defects on devices. Among them, subsurface structure design will change the device structure and affect the conventional performance of the device, and the cost is high. Methods such as field plate design and F-doped base oxide layer do not change the number of defects generated by irradiation in the device, and the reinforcement effect is limited.

[0003] Studies have shown that ionizing radiation-induced defects will anneal under high temperature conditions. By designing a polycrystalline micro-heating structure in the bipolar lateral PNP transistor and applying a constant high temperature for a certain period of time, the radiation-induced defects can be repaired, thereby improving the radiation resistance of the lateral PNP transistor.

[0004] At present, lateral PNP transistors have the weakest total dose resistance, while existing reinforcement methods have limited effects and have disadvantages such as high cost and affecting the conventional performance of the device. Summary of the invention

[0005] In order to overcome the shortcomings of bipolar lateral PNP transistors in space applications, such as insufficient radiation resistance, high cost of existing reinforcement methods, impact on conventional performance of devices and limited effects, the present invention proposes a lateral PNP transistor based on polysilicon thermal gate and a repair method thereof.

[0006] The technical solution adopted by the present invention to solve the technical problem is:

[0007] A lateral PNP transistor based on a polysilicon thermal gate comprises a base region and an emitter electrode; further comprising a polysilicon thermal gate arranged in the base region and between the emitter electrode and the collector electrode; the polysilicon thermal gate is in the form of a ring with an opening, and a polysilicon thermal gate positive electrode P is arranged at the opening end. A , polysilicon hot gate negative electrode P CThe emitter electrode is located in the polysilicon thermal gate. The above-mentioned lateral PNP transistor based on the polysilicon thermal gate comprises a polysilicon thermal gate, a base region, an epitaxial layer, a buried layer, a substrate, and an electrode connected in sequence.

[0008] The buried layer is in the shape of a circular plate, and the circular plate surface is in contact with the epitaxial layer and the substrate respectively. In the area outside the buried layer, the epitaxial layer is in contact with the substrate.

[0009] The electrodes include a base electrode, an emitter electrode, a collector electrode, a p-type doped emitter, a p-type doped collector, an n-type doped base, a polysilicon hot gate positive electrode P A , polysilicon hot gate negative electrode P C .

[0010] The emitter electrode is led out through an emitter electrode lead wire.

[0011] The base electrode, the emitter electrode lead, the collector electrode, the polysilicon hot gate positive electrode P A , polysilicon hot gate negative electrode P C For external electrodes.

[0012] The base electrode passes through the base region and is connected to the n-type doped base in the epitaxial layer; the emitter electrode passes through the base region and is connected to the p-type doped collector in the epitaxial layer; the collector electrode passes through the base region and is connected to the p-type doped emitter in the epitaxial layer.

[0013] The p-type doped emitter, the p-type doped collector, and the n-type doped base are all connected to the base region, and the n-type doped base is connected to the buried layer.

[0014] The polysilicon heat gate is in the form of a circular ring with an opening, and a positive electrode P of the polysilicon heat gate is arranged at the opening end. A , polysilicon hot gate negative electrode P C The polysilicon thermal gate is located at the center of the base region. The emitter electrode is located at the center of the polysilicon thermal gate ring.

[0015] In the above-mentioned lateral PNP transistor based on polysilicon thermal gate, the outer surface of the base region may also be an oxide layer, and the polysilicon thermal gate is connected to the oxide layer of the base region.

[0016] A method for preparing a lateral PNP transistor based on polysilicon hot gate includes the following steps:

[0017] The first step is the design of polysilicon thermal gate layout.

[0018] Polysilicon is arranged on the surface of the base region of the lateral PNP transistor. The polysilicon is used as a heating resistor when reinforcing the lateral PNP transistor, i.e., a polysilicon heat gate. The polysilicon heat gate is a circular ring with an opening, located in the central area above the base region, between the emitter electrode and the collector electrode.

[0019] The region between the emitter electrode and the collector electrode generates oxide trap charges and interface traps, and is a sensitive region to ionizing radiation. The polysilicon hot gate is located on the upper side of the sensitive region to ionizing radiation.

[0020] The second step is to process according to the polysilicon thermal gate layout design to produce a lateral PNP transistor based on the polysilicon thermal gate.

[0021] First, according to the polysilicon hot gate layout design, the polysilicon hot gate is prepared, and the polysilicon hot gate positive electrode P of the polysilicon hot gate is led out. A , polysilicon hot gate negative electrode P C .

[0022] Secondly, packaging and testing.

[0023] A lateral PNP bipolar transistor based on polysilicon thermal gate is obtained.

[0024] A method for repairing a lateral PNP transistor based on a polysilicon thermal gate comprises the following steps:

[0025] Step 1: Defect Characterization

[0026] Firstly, a semiconductor parameter test system is used to test the ionizing radiation induced defects of the lateral PNP transistor based on the polysilicon hot gate. The base current of the base electrode is measured along with the positive electrode P of the polysilicon hot gate. A Variation law of scanning voltage.

[0027] Secondly, the defect calculation

[0028] Calculate the positive electrode P of polysilicon hot gate before and after irradiation A The change in scanning voltage ΔV peak , the change in base current of the base electrode ΔI B-peak .

[0029] Determine the increment ΔN of the interface trap charge of a lateral PNP transistor based on polysilicon hot gate before and after irradiation it , calculated as follows:

[0030]

[0031] In formula (1), q is the electron charge, σ is the carrier recombination cross section, and v th is the carrier thermal rate, S peak is the base depletion layer area when the base current is maximum, n i is the intrinsic carrier concentration of Si semiconductor, k is the Boltzmann constant, T is the absolute temperature, C ox is the gate capacitance per unit area, V EB is the emitter voltage.

[0032] Determine the increment ΔN of oxide trap charge of lateral PNP transistor based on polysilicon hot gate before and after irradiation ot , calculated as follows:

[0033]

[0034] In formula (2), C ox is the gate capacitance per unit area.

[0035] The increment ΔN of the interface trap charge of the lateral PNP transistor based on polysilicon hot gate before and after irradiation is obtained it , the increment of oxide trap charge ΔN ot .

[0036] Step 2: Calculate the repair voltage

[0037] The lateral PNP transistor based on the polysilicon thermal gate that is irradiated is repaired and the test results are optimized to obtain the repair voltage V of the polysilicon thermal gate. rep .

[0038] At this point, the repair voltage V of the lateral PNP transistor based on polysilicon hot gate is obtained. rep .

[0039] Step 3: Implement the fix

[0040] The lateral PNP transistor based on the polysilicon thermal gate works normally in a radiation environment. When the total dose of ionizing radiation exceeds the tolerance range, the repair circuit is started, that is, the repair voltage V is applied to the polysilicon thermal gate. rep , which continues for a first set time, shuts down the repair circuit, and the lateral PNP transistor based on the polysilicon thermal gate is used normally again.

[0041] When the total ionizing radiation dose of the reused polysilicon hot gate based lateral PNP transistor exceeds the tolerance range, the repair circuit is repeatedly started to perform repair again.

[0042] In the above-mentioned polysilicon thermal gate-based lateral PNP transistor repair method, step 3 also includes the step of waiting for a first set time after closing the repair circuit until the temperature of the lateral PNP transistor returns to normal and then continuing to work.

[0043] In the above-mentioned method for repairing a lateral PNP transistor based on polysilicon thermal gate, the first setting time is 100s; and the second setting time is 100s.

[0044] The above-mentioned polysilicon hot gate based lateral PNP transistor repair method, the step 2 of obtaining the repair voltage further comprises:

[0045] A lateral PNP transistor based on a polysilicon thermal gate is selected for irradiation test, and the total irradiation dose value is calculated using the test data of the lateral PNP transistor based on a polysilicon thermal gate irradiated in the first step of step 1.

[0046] Repair test of lateral PNP transistor based on polysilicon hot gate after irradiation test. A and the polysilicon hot gate negative electrode P C Apply different voltage values ​​to test the changes of interface trap charge and oxide trap charge before and after repair. The voltage value when the defect degradation reaches saturation is selected as the repair voltage V rep .

[0047] The beneficial effects of the present invention are:

[0048] A lateral PNP transistor based on polysilicon hot gate is provided. A polycrystalline hot gate electrode is fabricated in a surface oxide layer of a base region in a radiation sensitive area of ​​the lateral PNP transistor. A voltage is applied to the polycrystalline hot electrode to generate a local high temperature to repair ionizing radiation-induced defects. This can effectively improve the total dose resistance of the lateral PNP transistor.

[0049] A lateral PNP transistor repair method based on polysilicon thermal gate has a simple implementation process. The designed polycrystalline heating resistor is located above the oxide layer and will not affect the conventional performance of the device. At the same time, the size of the repair resistor is at the micron level, and the power consumption required for heating is very low.

[0050] A lateral PNP transistor based on a polysilicon hot gate provides a defect repair function design structure that can not only realize real-time repair of ionizing radiation induced defects in a radiation environment, but also realize quantitative separation of ionizing radiation induced defects in a radiation environment, thereby more accurately obtaining the change law of radiation induced defects of the device in the radiation environment, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is a cross-sectional view of a lateral PNP transistor based on a polysilicon thermal gate of the present invention;

[0052] Figure 2 It is a top view of the lateral PNP transistor based on polysilicon thermal gate of the present invention.

[0053] In the figure: 1. Base electrode; 2. Emitter electrode; 3. Collector electrode; 4. Polycrystalline silicon hot gate; 5. p-type doped emitter; 6. p-type doped collector; 7. Buried layer; 8 Substrate; 9. n-type doped base; 10. Epitaxial layer; 11. Emitter electrode lead wire; 12. Polycrystalline hot gate positive electrode P A ; 13. Polycrystalline hot grid negative electrode P C ; 14. Base area. DETAILED DESCRIPTION

[0054] Embodiment 1, 2, 3

[0055] A method for repairing a lateral PNP transistor based on a polysilicon thermal gate is disclosed. A polysilicon micro-heating resistor is fabricated above the oxide layer on the surface of the base region of a bipolar lateral PNP transistor to form a lateral PNP transistor with defect repair function. The polysilicon micro-heating resistor is used to quantitatively separate and monitor radiation-induced defects in real time.

[0056] Fabrication of lateral PNP transistor based on polysilicon thermal gate:

[0057] The layout design of the lateral PNP transistor based on polysilicon thermal gate is carried out, and a micro polysilicon resistor is made above the oxide layer of the device. The polysilicon is used to convert electrical energy into heat to repair the ionizing radiation-induced defects in the radiation-sensitive area below. The polysilicon is used to heat the radiation-sensitive area to form a gate resistor, i.e., a polysilicon thermal gate. The designed device is taped out to form a lateral PNP transistor based on polysilicon thermal gate.

[0058] The first step is to select the lateral PNP transistor to be reinforced and design the polysilicon thermal gate layout;

[0059] A polysilicon heating resistor is designed and manufactured above the oxide layer on the surface of the base region. The position of the polysilicon is as follows: Figure 1 As shown, the polysilicon is located above the base region, specifically in the surface oxide layer area between the emitter and collector electrodes. This area is the most sensitive to ionizing radiation. The oxide trap charges and interface traps generated by ionizing radiation in this area are the main factors causing device performance degradation.

[0060] The second step is to process according to the polysilicon thermal gate layout design to produce a lateral PNP transistor based on the polysilicon thermal gate.

[0061] First, according to the polysilicon thermal grid layout design, the electrodes at both ends of the polysilicon heating resistor are led out. The structure diagram is shown in Figure 2 As shown, the heating electrode anode is denoted as P A and cathode is denoted as P C .

[0062] Secondly, packaging and testing are performed to form a lateral PNP transistor based on polysilicon thermal gate.

[0063] The specific repair process includes the following steps:

[0064] Step 1: Defect Characterization

[0065] Obtaining the concentration information of radiation-induced products of lateral PNP transistors can effectively guide the repair of defects. The surface potential of the base region is controlled by polysilicon resistors, so that the base surface transitions from flat band to depletion and then to inversion. The quantitative separation of radiation-induced defects in the oxide layer is achieved through the change of the base recombination current. Therefore, the structure also has the ability to separate ionizing radiation-induced defects. The detailed defect separation characterization method is as follows:

[0066] The first step is device connection

[0067] The device is connected to a semiconductor parameter test system or a test circuit;

[0068] The second step is to test the gate scanning curve

[0069] The collector electrode and base electrode of the device are grounded, and a fixed voltage V is applied to the emitter electrode. B (Range: 0.4V~0.6V), at P A Apply a sweep voltage with a voltage range of 0V-40V and a step size of no more than 0.5V. Measure the base current I B With electrode P A Scanning voltage variation defect.

[0070] Step 3: Defect calculation

[0071] Record the peak position ΔV before and after irradiation (after repair) peak and the change in height ΔI B-peak ;

[0072] According to formula (1), the increment ΔN of the interface trap after irradiation (after repair) is solved: it ;

[0073]

[0074] According to formula (2), the increment ΔN of oxide trap charge after irradiation (after repair) is solved: ot ;

[0075]

[0076] In formulas (1) and (2), n i is the intrinsic carrier concentration of Si semiconductor, S peak is the base depletion layer area when the base current is maximum, v th is the carrier thermal rate, σ is the carrier recombination cross section, C ox is the gate capacitance per unit area, q is the electron charge, k is the Boltzmann constant, T is the absolute temperature, V EB is the emitter voltage.

[0077] Quantitatively obtain the concentration information of ionizing radiation-induced defects: oxide trap charges and interface traps.

[0078] Step 2: Selection of optimal repair voltage

[0079] The total dose irradiation test is carried out on the fabricated lateral PNP transistor, and a certain total dose is accumulated, followed by a repair test under different voltages. Since the heat generated by the polycrystalline resistor is positively correlated with the applied voltage, the repair temperature can be controlled by adjusting the applied voltage value. If the repair temperature is too high, it will cause excessive power consumption and affect the normal life of the device, and if it is too low, the repair effect cannot be achieved. It is necessary to obtain the optimal repair voltage.

[0080] First, N1 pieces of lateral PNP bipolar transistors with defect repair prepared are extracted, where N1=15 to 30 pieces.

[0081] Table 1 Related parameters

[0082] Example 1 Example 2 Example 3 <![CDATA[Per piece N1]]> 15 20 30

[0083] The selected samples were divided into 5 groups;

[0084] Secondly, perform the grid scanning curve test before irradiation according to the first and second steps in step 1;

[0085] Third, for the lateral PNP transistor, the zero bias condition is the worst irradiation bias, and the damage in the low-dose environment is the most serious. Therefore, the cobalt source irradiation test is carried out under the conditions of 0.01rad / s dose rate and zero bias, and the total dose is accumulated to the total dose value required by the specified device application, and the gate scanning curve test after irradiation is carried out according to the first and second steps in step 1.

[0086] Fourth, according to the third step in step 1, calculate the radiation-induced defect oxide trap charge ΔN after irradiation it and interface state ΔN ot concentration;

[0087] Fifth, in each group of devices P A and P C Different voltage values ​​are applied to the electrodes, ranging from 5V to 20V, for a duration of 100s. After the device temperature returns to room temperature, the gate scanning curve is tested according to the process in step 1, and the defect concentration information after repair is extracted.

[0088] Finally, the defect concentration is plotted as a function of applied voltage, and the voltage value when the defect degradation reaches saturation is taken as the optimal repair voltage V for the PNP transistor with defect repair function. rep .

[0089] Step 3, Application Process

[0090] When working normally in a radiation environment, P A and P C In floating state.

[0091] When the lateral PNP transistor is subjected to ionizing radiation doses beyond the tolerance range or the device parameters fail, the device stops working. A and P C Apply V rep Voltage for 100s, turn off the repair circuit, wait for 100s, wait for the device temperature to return to normal, and the device continues to work in the radiation environment.

[0092] When the device is exposed to ionizing radiation dose that exceeds the tolerance range again or the device parameters fail, the repair circuit is restarted.

Claims

1. A lateral PNP transistor based on polysilicon hot gate, comprising a base region (14) and an emitter electrode (2); characterized in that: The invention also comprises a polycrystalline silicon thermal gate (4) arranged in the base region (14) and located between the emitter electrode (2) and the collector electrode (3); the polycrystalline silicon thermal gate (4) is a ring with an opening, and a polycrystalline silicon thermal gate positive electrode P is arranged at the opening end. A , polysilicon hot gate negative electrode P C ; The emitter electrode (2) is located inside the polysilicon thermal gate (4); It also includes a polysilicon thermal gate (4), a base region (14), an epitaxial layer (10), a buried layer (7), a substrate (8), and electrodes that are connected in sequence; The buried layer (7) is in the shape of a circular plate, and the circular plate surface is respectively connected to the epitaxial layer (10) and the substrate (8); in the area outside the buried layer (7), the epitaxial layer (10) is connected to the substrate (8); The electrodes include a base electrode (1), an emitter electrode (2), a collector electrode (3), a p-type doped emitter (5), a p-type doped collector (6), an n-type doped base (9), a polysilicon hot gate positive electrode P A (12), polysilicon hot gate negative electrode P C (13); The emitter electrode (2) is led out through an emitter electrode lead wire (11); The base electrode (1), the emitter electrode lead wire (11), the collector electrode (3), the polysilicon hot gate positive electrode P A (12), polysilicon hot gate negative electrode P C (13) is an external electrode; The base electrode (1) passes through the base region (14) and is connected to the n-type doped base (9) in the epitaxial layer (10); the emitter electrode (2) passes through the base region (14) and is connected to the p-type doped collector (5) in the epitaxial layer (10); the collector electrode (3) passes through the base region (14) and is connected to the p-type doped emitter (6) in the epitaxial layer (10); The p-type doped emitter (5), the p-type doped collector (6), and the n-type doped base (9) are all connected to the base region (14), and the n-type doped base (9) is connected to the buried layer (7); The polycrystalline silicon thermal gate (4) is in the shape of a ring with an opening, and a positive electrode P of the polycrystalline silicon thermal gate is arranged at the opening end. A , polysilicon hot gate negative electrode P C The polysilicon thermal gate (4) is located at the center of the base region (14); and the emitter electrode (2) is located at the center of the polysilicon thermal gate (4) ring.

2. The lateral PNP transistor based on polysilicon thermal gate according to claim 1, characterized in that: The outer surface of the base region (14) is an oxide layer, and the polysilicon thermal gate (4) is connected to the oxide layer of the base region (14).

3. A method for preparing a lateral PNP transistor based on polysilicon hot gate, characterized in that: The process includes the following: The first step is the design of polysilicon thermal gate layout. Polysilicon is arranged on the surface of the base region of the lateral PNP transistor, and the polysilicon is used as a heating resistor when reinforcing the lateral PNP transistor, that is, a polysilicon thermal gate; The polysilicon thermal gate (4) is in the shape of a ring with an opening and is located in the central area above the base region, between the emitter electrode (2) and the collector electrode (3); The region between the emitter electrode (2) and the collector electrode (3) generates oxide trap charges and interface traps, and is an ionizing radiation sensitive region; the polysilicon thermal gate (4) is located on the upper side of the ionizing radiation sensitive region; The second step is to process the polysilicon thermal gate according to the layout design to produce a lateral PNP transistor based on the polysilicon thermal gate; First, according to the polysilicon hot gate layout design, the polysilicon hot gate is prepared, and the polysilicon hot gate positive electrode P of the polysilicon hot gate is led out. A , polysilicon hot gate negative electrode P C ; Secondly, packaging and testing; A lateral PNP bipolar transistor based on polysilicon thermal gate is obtained.

4. A method for repairing a lateral PNP transistor based on a polysilicon thermal gate, characterized in that: The steps include: Step 1: Defect Characterization First, a semiconductor parameter test system is used to perform an ionizing radiation induced defect test on a lateral PNP transistor based on a polysilicon hot gate that is irradiated, and the base current of the base electrode (1) is measured along with the positive electrode P of the polysilicon hot gate. A Variation law of scanning voltage; Secondly, the defect calculation: Calculate the positive electrode P of polysilicon hot gate before and after irradiation A The change in scanning voltage ΔV peak , the change in base current of the base electrode (1) ΔI B-peak ; Determine the increment ΔN of the interface trap charge of a lateral PNP transistor based on polysilicon hot gate before and after irradiation it , calculated as follows: In formula (1), q is the electron charge, σ is the carrier recombination cross section, and v th is the carrier thermal rate, S peak is the base depletion layer area when the base current is maximum, n i is the intrinsic carrier concentration of Si semiconductor, k is the Boltzmann constant, T is the absolute temperature, C ox is the gate capacitance per unit area, V EB is the emitter voltage; Determine the increment ΔN of oxide trap charge of lateral PNP transistor based on polysilicon hot gate before and after irradiation ot , calculated as follows: In formula (2), C ox is the gate capacitance per unit area; The increment ΔN of the interface trap charge of the lateral PNP transistor based on polysilicon hot gate before and after irradiation is obtained it , the increment of oxide trap charge ΔN ot ; Step 2, calculate the repair voltage: The lateral PNP transistor based on the polysilicon thermal gate that is irradiated is repaired and the test results are optimized to obtain the repair voltage V of the polysilicon thermal gate. rep ; At this point, the repair voltage V of the lateral PNP transistor based on polysilicon hot gate is obtained. rep ; Step 3, implement the fix: The lateral PNP transistor based on the polysilicon thermal gate works normally in a radiation environment. When the total dose of ionizing radiation exceeds the tolerance range, the repair circuit is started, that is, the repair voltage V is applied to the polysilicon thermal gate. rep , lasting for a first set time, the repair circuit is turned off, and the lateral PNP transistor based on the polysilicon thermal gate is used normally again; When the total ionizing radiation dose of the reused polysilicon hot gate based lateral PNP transistor exceeds the tolerance range, the repair circuit is repeatedly started to perform repair again.

5. A method for repairing a lateral PNP transistor based on polysilicon thermal gate according to claim 4, characterized in that: Step 3 also includes the step of waiting for a first set time after closing the repair circuit until the temperature of the lateral PNP transistor returns to normal and then continuing to work.

6. A method for repairing a lateral PNP transistor based on polysilicon thermal gate according to claim 5, characterized in that: The first set time is 100s.

7. The method for repairing a lateral PNP transistor based on a polysilicon thermal gate according to claim 4, 5 or 6, characterized in that: The step 2 of obtaining the repair voltage further comprises: Selecting a lateral PNP transistor based on a polysilicon thermal gate for irradiation testing, and calculating a total irradiation dose value using test data of the lateral PNP transistor based on a polysilicon thermal gate irradiated in the first step of step 1; Repair test of lateral PNP transistor based on polysilicon hot gate after irradiation test. A and the polysilicon hot gate negative electrode P C Apply different voltage values ​​to test the changes of interface trap charge and oxide trap charge before and after repair with applied voltage; select the voltage value when the defect degradation reaches saturation as the repair voltage V rep .

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