A method for measuring radiation dose based on a floating-gate semiconductor transistor.

Abstract

This invention provides a radiation dose measurement method based on a floating-gate semiconductor transistor, primarily addressing the technical problem that existing technologies cannot accurately measure the radiation dose of floating-gate semiconductor transistors. The invention employs a method of measuring the voltage after charging the transistor under test (TUT) and then measuring it after irradiation. Based on a constant current method, it obtains the difference in threshold voltage between the TUT and its pre-irradiation values. Using this method, it obtains the difference in threshold voltage under different radiation doses and finally calculates the curve of the difference in threshold voltage as a function of cumulative radiation dose. This invention involves multiple programming and erasing of the floating-gate device, thereby significantly increasing the measurement range of radiation dose and enabling precise control of the radiation process.

Description

Technical Field

[0001] This invention relates to radiation dose measurement methods in the field of aerospace applications, specifically to a radiation dose measurement method based on a floating gate structure semiconductor transistor. Background Technology

[0002] The concept of a floating gate was first mentioned by D. Kahng and SMSze in 1967. It was applied to non-volatile memory devices with a MIMIS structure. The floating gate adds a Poly-Si layer to the MOS structure. The Poly-Si layer can trap electrons, thus affecting the device's threshold voltage and other performance parameters. Based on this structure, many floating gate structures suitable for detectors have been developed. When the floating gate structure is applied to memory, the device mainly exists in two states: programmed and erased. The state is determined by the magnitude of the current at its operating voltage. However, when the floating gate structure is applied to a radiation dosimeter (i.e., a detector), these two states are no longer considered.

[0003] Previous research has focused on space radiation dosimeters using P-type thick-gate oxide MOS devices as radiation-sensitive probes, with little research on radiation detection technology based on floating-gate structure devices as radiation-sensitive probes. Furthermore, using P-type thick-gate oxide MOS semiconductor devices as radiation-sensitive probes presents limitations in application environments due to the trade-off between measurement range and response sensitivity.

[0004] With the rapid development of semiconductor technology, it has been discovered that online radiation dose monitoring systems based on floating-gate transistors (FTMTs) exhibit better radiation response linearity, significantly improving the range of radiation dose measurements and enabling precise monitoring. These findings are crucial for the development of next-generation total dose detectors. However, currently, there is no precise method for measuring radiation dose using FTMTs, making it impossible to effectively evaluate the performance of radiation dosimeters employing them. Summary of the Invention

[0005] The purpose of this invention is to provide a radiation dose measurement method based on a floating gate structure semiconductor transistor, so as to solve the technical problem that the existing technology cannot accurately measure the radiation dose of a floating gate structure semiconductor transistor.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A radiation dose measurement method based on a floating-gate semiconductor transistor, characterized by the following steps:

[0008] Step 1: Charge the transistor under test to put it into a programming state, and use a semiconductor parameter testing device to measure the first characteristic curve; the transistor under test is a semiconductor transistor with a floating gate structure; the first characteristic curve refers to the initial Id-Vgs transfer characteristic curve of the transistor under test before irradiation.

[0009] Step 2: Select a current value Id from the first characteristic curve in Step 1, and then obtain the gate voltage V of the transistor under test at that current value. T初 ;

[0010] Step 3: Short-circuit all pins of the transistor under test that was in the programming state in Step 1, place it in the radiation field for the first irradiation, and then take it out. Use a semiconductor parameter testing device to measure and obtain the second characteristic curve; the second characteristic curve refers to the Id-Vgs transfer characteristic curve of the transistor under test after irradiation.

[0011] Step 4: Select the same current value Id from the second characteristic curve in Step 3 as in Step 2, and then obtain the gate voltage V corresponding to that current value of the transistor under test after irradiation. T后 ;

[0012] Step 5, combine the gate voltage V from step 2 T初 and the gate voltage V in step 4 T后 The difference ΔV between the gate voltages of the transistor under test is obtained. T1 , where ΔV T1 =V T初 –V T后 The difference in gate voltage ΔV T1 This is the difference in threshold voltage of the transistor under test after the first irradiation. This difference is used as a physical parameter characterizing the radiation dose of the transistor under test.

[0013] Step 6: Perform an erasure operation on the transistor under test to remove the charge inside the transistor. Repeat the radiation measurement N times according to the method of steps 1 to 5, and obtain the difference ΔV of the threshold voltage of the transistor under test after irradiation. T2 ΔV T3 ……ΔV TN Where N≥5;

[0014] Step 7: Calculate the cumulative radiation dose after each irradiation and the difference in threshold voltage ΔV after each irradiation based on the number of times the transistor under test is irradiated. T1 ΔV T2 ΔV T3 ……ΔV TN This allows us to obtain the curve of the difference in threshold voltage of the transistor under test as a function of the cumulative radiation dose, thus completing the radiation dose measurement of the floating gate structure semiconductor transistor.

[0015] Further, in step 1, the charging operation involves applying an external voltage to the source and gate of the transistor under test, and grounding the source and substrate of the transistor under test, so that the transistor under test carries a charge. After 0.1s to 10s, the external voltage is removed, thus completing the charging operation.

[0016] Furthermore, the applied voltage is 5 to 10V.

[0017] Furthermore, in step 2, the current value Id is taken as 1 to 10 μA.

[0018] Further, in step 3, the radiation field is 60 Co-γ ray radiation field or X-ray radiation field.

[0019] Furthermore, in step 3, the radiation dose of the radiation field is D = 5krad(Si).

[0020] Further, in step 6, the erasure operation involves applying a low voltage to the gate of the transistor under test and grounding the source, drain, and substrate so that the charge inside the transistor under test is 0. The low voltage is -5 to -10V.

[0021] Furthermore, in step 6, N is set to 10.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The radiation dose measurement method of this invention is based on the characteristic that charge loss on a floating-gate semiconductor transistor causes changes in the device's characteristic parameters, and the amount of change in characteristic parameters corresponds to the radiation dose. The method involves charging the transistor under test and then measuring it after irradiation. Using a constant current method, the difference in threshold voltage between the transistor under test and before irradiation is obtained. Based on this method, the difference in threshold voltage under different radiation doses is obtained, and finally, the curve of the difference in threshold voltage of the transistor under test as a function of cumulative radiation dose is calculated. This invention performs multiple programming and erasing operations on the floating-gate device, thereby significantly improving the measurement range of radiation dose and enabling precise control of the radiation process.

[0024] 2. The radiation dose measurement method of the present invention does not require power during the irradiation of the transistor under test, resulting in low power consumption and low testing cost.

[0025] 3. The radiation dose measurement method of the present invention is based on the detection technology of radiation dosimeter, which is highly applicable and easy to implement, so as to obtain radiation dose test information of floating gate structure semiconductor transistor. This method has positive significance for the theoretical guidance, method and technology establishment of the development of domestic floating gate dosimeter. Attached Figure Description

[0026] Figure 1 This is a curve showing the change of threshold voltage difference as a function of cumulative radiation dose for a semiconductor transistor based on a floating gate structure in an embodiment of the present invention. Detailed Implementation

[0027] The design principle of this invention is as follows: When the floating gate structure is applied to a radiation dosimeter, the floating gate is in a pre-charged state. Initial charge control in the floating gate employs methods such as FN tunneling or hot carrier injection. Under irradiation, the stored charge on the floating gate is lost, causing changes in the device's characteristic parameters. These changes correspond to the radiation dose, thus enabling radiation dose measurement. This invention measures semiconductor transistors with floating gate structures. These transistors are based on standard process lines, facilitating readout circuit integration. Furthermore, the floating gate structure allows for multiple programming and erasing operations, significantly expanding the radiation dose measurement range and broadening the applicable environments.

[0028] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0029] This invention provides a radiation dose measurement method based on a floating-gate semiconductor transistor, specifically including the following steps:

[0030] Step 1: Charge the transistor under test to put it into a programming state, and use a semiconductor parameter testing device to measure the first characteristic curve; the transistor under test is a semiconductor transistor with a floating gate structure; the first characteristic curve refers to the initial Id-Vgs transfer characteristic curve of the transistor under test before irradiation.

[0031] In this embodiment, the charging operation involves applying an external voltage, typically 5–10V, to the source and gate of the transistor under test (TUT). The source and substrate of the TUT are then grounded, causing the TUT to carry a charge. Once the TUT has accumulated sufficient electrons, the external voltage is removed, typically after 0.1–10 seconds, completing the charging operation.

[0032] Step 2: Select a current value Id from the first characteristic curve in Step 1. The current value Id can be between 1 and 10 μA, or any current value can be obtained from the Id-Vgs transfer characteristic curve. In this embodiment, the current value Id = 10 μA. By combining the current value with the Id-Vgs transfer characteristic curve, the gate voltage V corresponding to the transistor under test at this current value can be obtained. T初 .

[0033] Step 3: Short-circuit all pins of the transistor under test that was in the programming state in Step 1, and place it in a radiation field with a radiation dose of D = 5krad(Si) for the first irradiation. Then remove it and use a semiconductor parameter testing device to measure the second characteristic curve. The second characteristic curve refers to the Id-Vgs transfer characteristic curve of the transistor under test after irradiation.

[0034] In this embodiment, the radiation field is 60 A Co-γ ray radiation field or an X-ray radiation field can be used, or other types of radiation irradiation fields can be selected according to the actual situation. The radiation dose D = 5krad(Si) is the radiation dose point at which the transistor under test is most sensitive to radiation, that is, at this dose point, the threshold voltage drift of the transistor under test is the largest. If measuring other semiconductor transistors, the specific setting of the radiation field dose should be based on the actual needs and the radiation dose point at which the semiconductor transistor is most sensitive to radiation.

[0035] Step 4: Select the same current value Id (i.e., Id = 10 μA) from the second characteristic curve in Step 3, and then obtain the gate voltage V corresponding to this current value for the transistor under test after irradiation. T后 .

[0036] Step 5, combine the gate voltage V from step 2 T初 and the gate voltage V in step 4 T后 The difference ΔV between the gate voltages of the transistor under test is obtained. T1 , where ΔV T1 =V T初 –V T后 The difference in gate voltage ΔV T1 This is the difference in threshold voltage of the transistor under test after the first irradiation. This difference is used as a physical parameter characterizing the radiation dose of the transistor under test.

[0037] Step 6: Perform an erasure operation on the transistor under test to remove the charge inside the transistor. Then, repeat the radiation measurement N times according to the method of steps 1 to 5 to obtain the difference ΔV of the threshold voltage of the transistor under test after N radiation measurements. T2 ΔV T3 ……ΔV TN , where N≥5.

[0038] In this step, the erasure operation involves applying a low voltage to the gate of the transistor under test (TUT) and grounding the source, drain, and substrate, resulting in zero charge within the TUT and a low voltage of -5 to -10V. In this embodiment, N is set to 10, meaning the TUT undergoes 10 radiation dose measurements, with the cumulative radiation dose of the 10th measurement being 50 klad(Si). Before each subsequent radiation dose measurement, the TUT must be erased, followed by a charging operation to put it in a programmed state before irradiation. After the final radiation measurement, no further erasure operation is required; only the test data needs to be read.

[0039] Step 7: Calculate the cumulative radiation dose after each irradiation based on the number of times the transistor under test is irradiated, and then combine this with the difference in threshold voltage ΔV after each irradiation. T1 ΔV T2 ΔV T3 ΔV T4 ΔV T5 ΔV T6 ΔV T7 ΔV T8 ΔV T9 ΔV T10 This allows us to calculate the curve of the difference in threshold voltage of the transistor under test as a function of the cumulative radiation dose (e.g., Figure 1 As shown in the figure, the radiation dose measurement of the floating gate structure semiconductor transistor is then completed.

[0040] In this embodiment, the curve of the difference in threshold voltage of the transistor under test as a function of cumulative radiation dose can be expressed by the formula: ΔV TN =A·Dose n

[0041] In the formula, ΔV TN is the threshold voltage drift, which is the difference in threshold voltage of the transistor under test; Dose is the radiation dose; A is a constant; and n represents the linearity of the response, where 0 ≤ n ≤ 1. The closer n is to 1, the higher the linearity, and vice versa.

[0042] After obtaining the curve of the difference in threshold voltage of the transistor under test as a function of cumulative radiation dose, any such semiconductor transistor can be placed in an unknown radiation field. Based on the above curve and the difference in threshold voltage of the semiconductor transistor obtained through the Id-Vgs transfer characteristic curve, the radiation dose of the radiation field in which the semiconductor transistor is located can be obtained.

[0043] The radiation dose measurement method of the present invention is based on the detection technology of radiation dosimeter, which is highly applicable and easy to implement, so as to obtain radiation dose test information of floating grating structure device. This method has positive significance for the theoretical guidance, method and technology establishment of the development of domestic floating grating dosimeter.

[0044] Although embodiments of the present invention have been shown and described above, those skilled in the art should consider any variations and modifications of the above embodiments that fall within the spirit and scope of the present invention to be within the protection scope of the present invention.

Claims

1. A method for measuring radiation dose based on a floating-gate semiconductor transistor, characterized in that, Includes the following steps: Step 1: Charge the transistor under test to put it into a programming state, and use a semiconductor parameter testing device to measure the first characteristic curve; the transistor under test is a semiconductor transistor with a floating gate structure; the first characteristic curve refers to the initial Id-Vgs transfer characteristic curve of the transistor under test before irradiation. Step 2: Select a current value Id from the first characteristic curve in Step 1, and then obtain the gate voltage V of the transistor under test at that current value. T初 ; Step 3: Short-circuit all pins of the transistor under test that was in the programming state in Step 1, place it in the radiation field for the first irradiation, and then take it out. Use a semiconductor parameter testing device to measure and obtain the second characteristic curve; the second characteristic curve refers to the Id-Vgs transfer characteristic curve of the transistor under test after irradiation. Step 4: Select the same current value Id from the second characteristic curve in Step 3 as in Step 2, and then obtain the gate voltage V corresponding to that current value of the transistor under test after irradiation. T后 ; Step 5, combine the gate voltage V from step 2 T初 and the gate voltage V in step 4 T后 The difference ΔV in the threshold voltage of the transistor under test after the first irradiation is obtained. T1 , where ΔV T1 =V T初 –V T后 ; will ΔV T1 As a physical parameter characterizing the radiation dose of the transistor under test; Step 6: Perform an erasure operation on the transistor under test to remove the charge inside the transistor. Repeat the radiation measurement N times according to the method of steps 1 to 5, and obtain the difference ΔV of the threshold voltage of the transistor under test after irradiation. T2 , ΔV T3 ……ΔV TN Where N≥5; Step 7: Calculate the cumulative radiation dose after each irradiation based on the number of times the transistor under test is irradiated, and then combine this with the difference in threshold voltage ΔV after each irradiation. T1 , ΔV T2 , ΔV T3 ……ΔV TN The difference in threshold voltage of the transistor under test is obtained as a function of cumulative radiation dose, thus completing the radiation dose measurement of the floating gate structure semiconductor transistor.

2. The radiation dose measurement method based on a floating-gate semiconductor transistor according to claim 1, characterized in that: In step 1, the charging operation involves applying an external voltage to the source and gate of the transistor under test, and grounding the source and substrate of the transistor under test to make the transistor under test carry a charge. After 0.1s to 10s, the external voltage is removed, thus completing the charging operation.

3. The radiation dose measurement method based on a floating-gate semiconductor transistor according to claim 2, characterized in that: The applied voltage is 5 to 10V.

4. The radiation dose measurement method based on a floating-gate semiconductor transistor according to claim 3, characterized in that: In step 2, the current value Id is 1 to 10 μA.

5. The radiation dose measurement method based on a floating-gate semiconductor transistor according to claim 4, characterized in that: In step 3, the radiation field is 60 Co-γ ray radiation field or X-ray radiation field.

6. The radiation dose measurement method based on a floating-gate semiconductor transistor according to claim 5, characterized in that: In step 3, the radiation dose of the radiation field is D = 5krad(Si).

7. The radiation dose measurement method based on a floating-gate semiconductor transistor according to claim 6, characterized in that: In step 6, the erasure operation involves applying a low voltage to the gate of the transistor under test and grounding the source, drain, and substrate so that the charge inside the transistor under test is 0; the low voltage is -5 to -10V.

8. The radiation dose measurement method based on a floating-gate semiconductor transistor according to claim 7, In step 6, N is set to 10.

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