Temperature-compensated semiconductor material eddy current conductivity testing method

Abstract

The application discloses a kind of temperature-compensated semiconductor material eddy conductivity test methods, comprising S1, determining current temperature calibration curve;S2, the conductivity of the sample to be measured is measured;Wherein, the infrared temperature measurement system includes infrared CCD and focusing mirror, the central axis of the infrared CCD and the focusing mirror and the central axis of the active coil coincide, and the infrared CCD and the focusing mirror are located in the active coil or the passive coil or the magnetic field influence area formed by the active coil and the passive coil, the photosurface of the infrared CCD is located in the focal plane of the focusing mirror;The application can obtain more accurate conductivity of the position to be measured, improve the measurement accuracy of conductivity tester.

Description

Technical Field

[0001] This invention relates to the field of semiconductor material performance parameter testing, and specifically to a temperature-compensated method for testing the eddy current conductivity of semiconductor materials. Background Technology

[0002] In semiconductor manufacturing, the performance of end products depends on the performance of semiconductor materials. To ensure that the measurement process does not affect the quality of the end product, non-contact measurement methods are widely used to measure the performance of semiconductor materials. Non-contact measurement methods are non-destructive and do not introduce new defects. Especially in the production process, non-contact measurement methods greatly improve the product yield. These non-contact measurement methods can be classified in principle into electromagnetic induction methods, electrostatic induction methods, and microwave methods, etc. The quantities measured include the conductivity, mobility, carrier concentration, and lifetime of semiconductor materials.

[0003] The electrical conductivity of semiconductor materials is a fundamental parameter. A commonly used non-contact measurement method is electromagnetic induction. During measurement, an active electromagnetic coil and a passive electromagnetic coil are placed on the upper and lower surfaces of the semiconductor sample, respectively. An alternating current flows through the active electromagnetic coil, generating a magnetic field. This magnetic field induces eddy currents on the surface of the semiconductor material. These eddy currents then generate their own magnetic fields, which in turn affect both the active and passive electromagnetic coils. The magnetic field generated by the active electromagnetic coil and the magnetic field generated by the eddy currents in the semiconductor material are superimposed and pass through the passive electromagnetic coil. By detecting the induced current in the passive electromagnetic coil, the electrical conductivity of the semiconductor material at that current location can be obtained. A standard sample is used to calibrate the conductivity of the semiconductor material and the induced current in the passive electromagnetic coil, obtaining a curve of conductivity versus induced current. This curve can then be used to measure the conductivity of unknown semiconductor materials. During the measurement process, to ensure the repeatability of the measurement data, multiple measurements are required at the same location. The eddy currents generated during these multiple measurements produce a thermal effect on the semiconductor material surface, causing the surface temperature to rise. This temperature increase affects the conductivity measurement value, introducing new measurement errors. Since each product requires measurements at multiple locations to obtain conductivity data for the entire product surface, increasing the time interval between measurements to mitigate the temperature impact would significantly extend the measurement time, reducing efficiency and affecting production schedules. Therefore, to address the influence of potential heat changes on conductivity during measurement, new testing methods or structures are needed. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. This invention proposes a temperature-compensated method for testing the eddy current conductivity of semiconductor materials, comprising:

[0005] S1, Determine the current-temperature calibration curve

[0006] A standard silicon wafer with known conductivity is placed on a test platform. A conductivity test probe, which includes an active coil, a passive coil, and an infrared temperature measurement system, is moved directly or relatively to the test position of the standard silicon wafer. An alternating current is passed through the active coil by the control system to obtain the current value in the passive coil. The difference between the standard temperature and the actual temperature is measured by changing the temperature of the standard silicon wafer using the infrared temperature measurement system. After a predetermined number of tests and repeated tests on different standard silicon wafers for a predetermined number of times, a calibration lookup table including the relationship between current, temperature, and conductivity is established, and finally converted into a temperature-current calibration curve.

[0007] S2, Measure the conductivity of the sample.

[0008] The sample to be tested is placed on the test platform, the conductivity test probe is moved to the test position of the sample, an alternating current is passed through the active coil, the alternating current in the passive electromagnetic coil is read by the control system, and the temperature value measured by the infrared temperature measurement system is read simultaneously. After a predetermined number of times, the alternating current value of the passive coil at the current position and the temperature value at the current position are read. The control system processes the data and obtains the conductivity value at the standard temperature at the current position according to the temperature-current calibration curve and the calibration lookup table. Then the conductivity test probe is moved or relatively moved to the next test position of the sample to be tested and the process is repeated until the data measurement at all positions is completed.

[0009] The infrared temperature measurement system includes an infrared CCD and a focusing lens. The central axis of the infrared CCD and the focusing lens coincides with the central axis of the active coil. The infrared CCD and the focusing lens are located outside the magnetic field influence area formed by the active coil, the passive coil, or the active coil and the passive coil. The photosensitive surface of the infrared CCD is located at the focal plane of the focusing lens.

[0010] The temperature-compensated semiconductor material eddy current conductivity testing method of the present invention utilizes the hollow portion of the active electromagnetic coil structure. By installing an infrared temperature probe in the hollow portion or above it at a position outside the magnetic field influence area, a calibration lookup table and temperature-current calibration curve containing passive coil current, temperature, and conductivity are obtained using a standard silicon wafer. Then, by comparing the temperature and current at the test location of the sample online in real time with the calibration lookup table and calibration curve, a more accurate conductivity at the test location is obtained, improving the measurement accuracy of the conductivity tester.

[0011] In addition, the temperature-compensated semiconductor material eddy current conductivity testing method disclosed in this invention also has the following additional technical features:

[0012] Furthermore, the active coil and the passive coil in the conductivity test probe are located on the upper and lower surfaces of the test silicon wafer, respectively, and the distance from the end face of the active coil and the passive coil to the upper and lower surfaces of the silicon wafer is the expected value, and the active coil and the passive coil are coaxial.

[0013] Furthermore, the active coil and the passive coil in the conductivity test probe are housed in a base, and the active coil and the passive coil are connected to the detection equipment and analysis equipment via circuitry.

[0014] Furthermore, both the active coil and the passive coil are cylindrical coils, and the base is a cylindrical structure with the same shape as the active coil and the passive coil. The active coil is installed on the lower side of the passive coil. The active coil and the passive coil have the same inner and outer diameters and are fixedly installed on the inner side of the base.

[0015] Furthermore, the passive coil is disposed inside the active coil, the outer diameter of the passive coil matches the inner diameter of the active coil, and the active coil is disposed inside the base.

[0016] Optionally, the probe further includes an inner base, which is a cylindrical structure with a sandwich layer. The active coil is located between the inner wall of the outer base and the outer wall of the inner base, and the passive coil is placed in the sandwich layer of the inner base.

[0017] Preferably, the inner base is fixedly installed with the passive coil, and the inner base is movably installed inside the active coil.

[0018] Furthermore, in the infrared temperature measurement system, the infrared CCD and the focusing lens are located above the active coil and the passive coil, which have hollow structures. The determination of the upper position needs to be determined through calculation and experimentation to avoid adverse effects from corresponding magnetic fields, etc., so as to avoid measurement problems caused by them.

[0019] Additional aspects and advantages of embodiments of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0021] Figure 1 This is a schematic diagram of the structure of an embodiment of the prior art;

[0022] Figure 2 This is a schematic diagram illustrating the infrared temperature measurement principle of the present invention;

[0023] Figure 3 This is a schematic diagram of the structure of an embodiment of the conductivity testing probe of the present invention;

[0024] Figure 4 This is a schematic diagram of the temperature-current calibration curve of the present invention;

[0025] Figure 5 This is a schematic diagram of the device structure of the present invention;

[0026] Figure 6 This is a schematic diagram of a specific embodiment of the conductivity testing probe of the present invention;

[0027] Figure 7 This is another structural schematic diagram of a specific embodiment of the conductivity testing probe of the present invention;

[0028] Among them, 01 magnetic field lines, 02 active coil, 03 heat-affected zone, 04 silicon ingot, 05 passive coil; I current, T temperature, A1 infrared CCD, A2 focusing lens, A3 incident light; B2 distance detection component, B5 outer base, B6 inner base, B7 wire. Detailed Implementation

[0029] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0030] According to embodiments of the present invention, a temperature-compensated method for testing the eddy current conductivity of semiconductor materials is proposed, comprising:

[0031] S1, Determine the current-temperature calibration curve

[0032] A standard silicon wafer with known conductivity is placed on a test platform. A conductivity test probe, which includes an active coil, a passive coil, and an infrared temperature measurement system, is moved directly or relatively to the test position of the standard silicon wafer. An alternating current is passed through the active coil by the control system to obtain the current value in the passive coil. The difference between the standard temperature and the actual temperature is measured by changing the temperature of the standard silicon wafer using the infrared temperature measurement system. After a predetermined number of tests and repeated tests on different standard silicon wafers for a predetermined number of times, a calibration lookup table including the relationship between current, temperature, and conductivity is established, and finally converted into a temperature-current calibration curve.

[0033] S2, Measure the conductivity of the sample.

[0034] The sample to be tested is placed on the test platform, the conductivity test probe is moved to the test position of the sample, an alternating current is passed through the active coil, the alternating current in the passive electromagnetic coil is read by the control system, and the temperature value measured by the infrared temperature measurement system is read simultaneously. After a predetermined number of times, the alternating current value of the passive coil at the current position and the temperature value at the current position are read. The control system processes the data and obtains the conductivity value at the standard temperature at the current position according to the temperature-current calibration curve and the calibration lookup table. Then the conductivity test probe is moved or relatively moved to the next test position of the sample to be tested and the process is repeated until the data measurement at all positions is completed.

[0035] The infrared temperature measurement system includes an infrared CCD and a focusing lens. The central axis of the infrared CCD and the focusing lens coincides with the central axis of the active coil. The infrared CCD and the focusing lens are located outside the magnetic field influence area formed by the active coil, the passive coil, or the active coil and the passive coil. The photosensitive surface of the infrared CCD is located at the focal plane of the focusing lens.

[0036] According to some embodiments of the present invention, both the active coil and the passive coil are cylindrical coil structures. The active coil and the passive coil in the conductivity testing probe are located on the upper and lower surfaces of the silicon wafer being tested, respectively. The distances from the end faces of the active coil and the passive coil to the upper and lower surfaces of the silicon wafer are expected values. The active coil and the passive coil are coaxial. Figure 1 , 3 As shown in Figure 5.

[0037] Furthermore, the active coil and the passive coil in the conductivity test probe are housed in a base, and the active coil and the passive coil are connected to the detection equipment and analysis equipment via circuitry.

[0038] Optionally, both the active coil and the passive coil are cylindrical coil structures, and the base is a cylindrical structure with the same shape as the active coil and the passive coil. The active coil is mounted below the passive coil. The active coil and the passive coil have the same inner and outer diameters and are fixedly mounted inside the base, such as... Figure 6 As shown.

[0039] Optionally, the passive coil is disposed inside the active coil, the outer diameter of the passive coil matches the inner diameter of the active coil, and the active coil is disposed inside the base, such as... Figure 7 As shown.

[0040] Preferably, the conductivity test probe further includes an inner base, which is a cylindrical structure with a sandwich layer. The active coil is located between the inner wall of the outer base and the outer wall of the inner base, and the passive coil is placed in the sandwich layer of the inner base.

[0041] Preferably, the inner base is fixedly installed with the passive coil, and the inner base is movably installed inside the active coil.

[0042] According to some embodiments of the present invention, the infrared CCD and the focusing lens in the infrared temperature measurement system are located above the active coil and the passive coil, which have hollow structures, such as... Figure 3 As shown.

[0043] According to some embodiments of the present invention, the conductivity testing probe is equipped with a distance detection component for detecting the distance between the bottom end of the conductivity testing probe and the upper surface of the silicon ingot below. The use of the distance detection component allows for automatic backend feedback and automatic adjustment of the distance between the entire probe and the silicon ingot surface.

[0044] Furthermore, the distance detection component is a non-contact displacement sensor.

[0045] Optionally, the distance detection component is a laser position sensor.

[0046] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for testing the eddy current conductivity of a temperature-compensated semiconductor material, characterized in that, include: S1, Determine the current-temperature calibration curve A standard silicon wafer with known conductivity is placed on a test platform. A conductivity test probe, which includes an active coil, a passive coil, and an infrared temperature measurement system, is moved directly or relatively to the test position of the standard silicon wafer. An alternating current is passed through the active coil by the control system to obtain the current value in the passive coil. The difference between the standard temperature and the actual temperature is measured by changing the temperature of the standard silicon wafer using the infrared temperature measurement system. After a predetermined number of tests and repeated tests on different standard silicon wafers for a predetermined number of times, a calibration lookup table including the relationship between current, temperature, and conductivity is established, and finally converted into a temperature-current calibration curve. S2, Measure the conductivity of the sample. The sample to be tested is placed on the test platform, the conductivity test probe is moved to the test position of the sample, an alternating current is applied to the active coil, the alternating current in the passive coil is read by the control system, and the temperature value measured by the infrared temperature measurement system is read simultaneously. After a predetermined number of reads, the alternating current value of the passive coil at the current position and the temperature value at the current position are read. The control system processes the data and obtains the conductivity value at the standard temperature at the current position according to the temperature-current calibration curve and the calibration lookup table. Then the conductivity test probe is moved or relatively moved to the next test position of the sample to be tested and the process is repeated until the data measurement at all positions is completed. The infrared temperature measurement system includes an infrared CCD and a focusing lens. The central axis of the infrared CCD and the focusing lens coincides with the central axis of the active coil. The infrared CCD and the focusing lens are located outside the magnetic field influence area formed by the active coil, the passive coil, or the active coil and the passive coil. The photosensitive surface of the infrared CCD is located at the focal plane of the focusing lens.

2. The method for testing the eddy current conductivity of temperature-compensated semiconductor materials according to claim 1, characterized in that, The active coil and passive coil in the conductivity test probe are located on the upper and lower surfaces of the test silicon wafer, respectively, and the distances from the end faces of the active coil and the passive coil to the upper and lower surfaces of the silicon wafer are expected values. The active coil and the passive coil are coaxial.

3. The method for testing the eddy current conductivity of temperature-compensated semiconductor materials according to claim 1, characterized in that, The active coil and the passive coil in the conductivity test probe are placed in the same base on the same side of the silicon wafer, and the active coil and the passive coil are connected to the detection and analysis equipment through circuits.

4. The method for testing the eddy current conductivity of temperature-compensated semiconductor materials according to claim 3, characterized in that, Both the active coil and the passive coil are cylindrical coils. The base is a cylindrical structure with the same shape as the active coil and the passive coil. The active coil is installed on the lower side of the passive coil. The active coil and the passive coil have the same inner and outer diameters and are fixedly installed on the inner side of the base.

5. The method for testing the eddy current conductivity of temperature-compensated semiconductor materials according to claim 3, characterized in that, The passive coil is disposed inside the active coil, the outer diameter of the passive coil matches the inner diameter of the active coil, and the active coil is disposed inside the base.

6. The method for testing the eddy current conductivity of temperature-compensated semiconductor materials according to claim 5, characterized in that, The probe also includes an inner base, which is a cylindrical structure with a sandwich layer. The active coil is located between the inner wall of the outer base and the outer wall of the inner base, and the passive coil is placed in the sandwich layer of the inner base.

7. The method for testing the eddy current conductivity of temperature-compensated semiconductor materials according to claim 6, characterized in that, The inner base is fixedly installed with the passive coil, and the inner base is movably installed inside the active coil.

8. The method for testing the eddy current conductivity of temperature-compensated semiconductor materials according to claim 1, characterized in that, In the infrared temperature measurement system, the infrared CCD and the focusing lens are located above the active coil and the passive coil, which have hollow structures.

9. The method for testing the eddy current conductivity of temperature-compensated semiconductor materials according to claim 1, characterized in that, The conductivity test probe is equipped with a distance detection component that detects the distance between the bottom of the conductivity test probe and the upper surface of the silicon ingot below.

10. The method for testing the eddy current conductivity of temperature-compensated semiconductor materials according to claim 9, characterized in that, The distance detection component is a non-contact displacement sensor.

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