Method for testing the eddy current conductivity of semiconductor materials with cooling function

Abstract

The application discloses a kind of semiconductor material eddy conductivity testing methods with cooling function, including the silicon wafer to be measured motion to be measured site, the conductivity probe is moved to the measured site, while using the cooling spray head cooling spray, according to the vortex cold gas calibration curve, determine the gas supply amount required to be provided by the cooling spray head, while according to the standard relationship curve between the current in the existing passive coil and the conductivity of the standard silicon wafer determines the conductivity of the measured site;The application utilizes the hollow part of active electromagnetic coil, by installing cooling spray head in hollow part, according to the heat quantity of material, a certain flow and pressure cooling air is passed in, the heat of semiconductor material surface is promptly exported, ensure that the temperature of semiconductor material surface is in specified range, improve the measurement accuracy of conductivity tester.

Description

Technical Field

[0001] This invention relates to the field of semiconductor material performance parameter testing, specifically to a method for testing the eddy current conductivity of semiconductor materials with cooling function. 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 products, 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. In particular, non-contact measurement methods greatly improve the yield of products during the production process.

[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 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, in turn, 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.

[0004] Therefore, it is necessary to find a way or method that can reduce the temperature in the corresponding area while ensuring measurement accuracy. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. This invention proposes a method for testing the eddy current conductivity of semiconductor materials with cooling function, comprising:

[0006] A standard silicon wafer with known conductivity is placed on a test platform. Simultaneously, a conductivity probe containing an active coil and a passive coil is moved to the area to be tested. During the test, a cooling nozzle including an air inlet, an air outlet, and a vent structure is used to cool the area to be tested. By testing the duration of the eddy current at the area to be tested on the standard silicon wafer, the coordination of the cooling nozzle with the cooling air supply, and the current data, an eddy current-cooling air calibration curve is formed, which is the relationship between the duration of the eddy current and the cooling air supply. The above process is repeated multiple times to obtain the eddy current-cooling air calibration curve corresponding to the area to be tested.

[0007] The silicon wafer to be tested is moved to the test location, the conductivity probe is moved to the test location, and cooling spray is performed using the cooling nozzle. The required air supply of the cooling nozzle is determined according to the eddy current cooling gas calibration curve. At the same time, the conductivity of the test location is determined according to the standard relationship curve between the current in the passive coil and the conductivity of the standard silicon wafer.

[0008] The present invention provides a method for testing the eddy current conductivity of semiconductor materials with a cooling function. By utilizing the hollow part of an active electromagnetic coil and installing a cooling nozzle in the hollow part, cooling air with a certain flow rate and pressure is introduced according to the heat generated by the material. This method effectively removes heat from the surface of the semiconductor material, ensuring that the surface temperature of the semiconductor material is within a specified range and improving the measurement accuracy of the conductivity tester.

[0009] In addition, the eddy current conductivity testing method for semiconductor materials with cooling function disclosed in this invention also has the following additional technical features:

[0010] Furthermore, the cooling nozzle is placed at a predetermined position in the hollow portion of the active coil or at a predetermined position on the upper side of the hollow portion.

[0011] Furthermore, the test platform on which the standard silicon wafer or the silicon wafer under test is placed is mounted on a two-dimensional motion platform.

[0012] Furthermore, the motion platform includes an X-axis motion module and a Y-axis motion module for moving the test platform in the X-axis and Y-axis directions.

[0013] Furthermore, the motion platform also includes a rotary motion module for rotating the test platform, the rotary motion module being mounted on the X-axis motion module or the Y-axis motion module.

[0014] Furthermore, an electro-proportional valve is connected to the rear end of the cooling nozzle to control the gas flow rate and gas pressure of the air inlet and the air outlet. An air pump is connected to the rear end of the electro-proportional valve to provide cooling gas at a constant temperature. The cooling gas enters the air-cooled area of ​​the cooling nozzle through the air inlet, exchanges heat with the heat-affected zone of the standard silicon wafer or the silicon wafer under test, and is then discharged through the air outlet, carrying away heat and keeping the temperature of the heat-affected zone of the standard silicon wafer or the silicon wafer under test within a predetermined range.

[0015] Furthermore, the cooling nozzle is a cylindrical multi-hole structure with an outer diameter smaller than the inner diameter of the active coil. The cylindrical multi-hole structure has an air inlet in the middle, and the air outlets are evenly distributed around the air inlet. The lower part of the cooling nozzle has a concave air pocket structure that can temporarily store cold air and improve heat exchange efficiency.

[0016] Furthermore, the cooling nozzle is made of a non-metallic material.

[0017] Furthermore, the cross-sectional area of ​​the air inlet of the cooling nozzle is the same as the cross-sectional area of ​​all the air outlets.

[0018] Furthermore, the method also includes a control system for controlling the movement of the silicon wafer under test or the standard silicon wafer, the supply of cooling air, and the data acquisition, analysis, and processing.

[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 illustrating the principle of electromagnetic induction measurement of conductivity in existing technologies.

[0022] Figure 2 This is a schematic diagram of the conductivity detection structure with cooling function of the present invention;

[0023] Figure 3 This is a schematic diagram of the cooling nozzle and gas flow channel structure of the present invention;

[0024] Figure 4 This is a schematic diagram showing the air intake and blowing pressure of the cooling nozzle of the present invention;

[0025] Figure 5 This is the eddy current existence time gas flow rate calibration curve of the present invention;

[0026] Figure 6 This is a schematic diagram of the overall device structure according to a specific embodiment of the present invention;

[0027] Among them, 01 magnetic field lines, 02 active coil, 03 heat-affected zone, 04 silicon wafer, 05 passive coil; 06 cooling nozzle, 061 air inlet, 062 air outlet, 063 vortex zone, 07 electric proportional valve, 08 air pump, 09 control system, P1, P2 air outlet side pressure, P0 air inlet side pressure, L gas flow rate, and T vortex existence time. Detailed Implementation

[0028] 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.

[0029] According to embodiments of the present invention, a method for testing the eddy current conductivity of semiconductor materials with cooling function is proposed, comprising:

[0030] A standard silicon wafer with known conductivity is placed on a test platform. Simultaneously, a conductivity probe containing an active coil and a passive coil is moved to the area to be tested. During the test, a cooling nozzle including an air inlet, an air outlet, and a vent structure is used to cool the area to be tested. By testing the duration of the eddy current at the area to be tested on the standard silicon wafer, the coordination of the cooling nozzle with the cooling air supply, and the current data, an eddy current-cooling air calibration curve is formed, which is the relationship between the duration of the eddy current and the cooling air supply. The above process is repeated multiple times to obtain the eddy current-cooling air calibration curve corresponding to the area to be tested.

[0031] The silicon wafer to be tested is moved to the test location, the conductivity probe is moved to the test location, and cooling spray is performed using the cooling nozzle. The required air supply of the cooling nozzle is determined according to the eddy current cooling gas calibration curve. At the same time, the conductivity of the test location is determined according to the standard relationship curve between the current in the passive coil and the conductivity of the standard silicon wafer.

[0032] In the prior art, the active electromagnetic coil and the passive electromagnetic coil are located on the upper and lower surfaces of the silicon wafer and the distance between them is fixed. When the control system applies an alternating current to the active electromagnetic coil and forms an alternating magnetic field, the alternating magnetic field induces eddy currents on the surface of the silicon wafer. The eddy currents generate a thermal effect at the location where the magnetic field lines pass, causing the surface temperature of the silicon wafer to rise. This invention can further improve the accuracy of the measurement in the prior art by providing a cooling airflow and a corresponding calibration curve.

[0033] According to some embodiments of the present invention, the cooling nozzle is placed at a predetermined position in the hollow portion of the active coil or at a predetermined position above the hollow portion, such as... Figure 2 As shown.

[0034] According to some embodiments of the present invention, the test platform on which the standard silicon wafer or the silicon wafer under test is placed is mounted on a two-dimensional motion platform.

[0035] According to some embodiments of the present invention, the motion platform includes an X-axis motion module and a Y-axis motion module for moving the test platform in the X-axis and Y-axis directions.

[0036] According to some embodiments of the present invention, the motion platform further includes a rotary motion module for rotating the test platform, the rotary motion module being mounted on the X-axis motion module or the Y-axis motion module.

[0037] According to some embodiments of the present invention, an electro-proportional valve for controlling the gas flow rate and gas pressure at the air inlet and the air outlet is connected to the rear end of the cooling nozzle, and an air pump for providing cooling gas at a constant temperature is connected to the rear end of the electro-proportional valve; the cooling gas enters the concave area of ​​the cooling nozzle through the air inlet, exchanges heat with the heat-affected zone of the surface of the standard silicon wafer or the silicon wafer under test, and is then discharged through the air outlet, carrying away heat and maintaining the temperature of the heat-affected zone of the surface of the standard silicon wafer or the silicon wafer under test within a predetermined range.

[0038] According to an embodiment of the present invention, the cooling nozzle is a cylindrical multi-hole structure with an outer diameter smaller than the inner diameter of the active coil. The cylindrical multi-hole structure has an air inlet in the middle, and the air outlets are evenly distributed around the air inlet. The lower part of the cooling nozzle has a concave air pocket structure that can temporarily store cold air to improve heat exchange efficiency. The capacity and time of cold air storage need to be determined through experiments and calculations.

[0039] During gas supply, the supplied gas has a certain pressure. If the pressure is too high, it will cause the position of the silicon wafer relative to the electromagnetic coil to change. If the pressure is too low, it will not be able to remove the heat generated by the eddy currents in time. At this time, it is necessary to test and match the inlet and outlet pressures to balance the pressure generated by the gas in the confined area and avoid blowing pressure on the silicon wafer. Figure 4 As shown. The duration of the eddy current during measurement determines the amount of heat generated, which in turn determines the amount of cooling air supplied. A curve showing the relationship between the eddy current duration and the amount of cooling air supplied needs to be established through testing, as shown below. Figure 5 As shown

[0040] Furthermore, the cooling nozzle is made of a non-metallic material.

[0041] Furthermore, the cross-sectional area of ​​the air inlet of the cooling nozzle is the same as the cross-sectional area of ​​all the air outlets.

[0042] According to an embodiment of the present invention, the method further includes a control system for controlling the movement of the silicon wafer under test or the standard silicon wafer, the supply of cooling air, and the data acquisition, analysis and processing.

[0043] According to an embodiment of the present invention, the test platform is used to fix the test sample and perform planar motion, and moves to a set position according to instructions. The control system is used for motion flow control, current data acquisition and data processing tasks during the measurement process. The conductivity value of the silicon wafer is calculated based on the measured current value, and finally the conductivity value at the standard temperature is obtained.

[0044] It consists of active and passive electromagnetic coils, a cooling system, a control system, an XY motion platform, and a test silicon wafer.

[0045] According to one embodiment of the present invention, the active coil and the passive coil are respectively located on the upper and lower surfaces of the test silicon wafer, 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 fixed, and the active coil and the passive coil are coaxial.

[0046] The method employs a cooling system including an air pump, an electro-proportional valve, and a cooling nozzle. The air pump provides cooling air at a constant temperature, and the electro-proportional valve controls the gas flow rate and pressure at the inlet and outlet. The cooling air enters the cooling nozzle's concave zone through the inlet, exchanges heat with the heat-affected zone (HAZ) on the silicon wafer surface, and is then discharged through the outlet, carrying away heat and maintaining the temperature of the HAZ within a certain range.

[0047] The control system is used to control the sequence of actions during the operation of the tester, control the air supply and pressure of the cooling system, collect the current in the driven coil, process the data, and calculate the conductivity value of the silicon wafer at the standard temperature according to the calibration curve.

[0048] During measurement, a silicon wafer semiconductor sample with parallel upper and lower surfaces of a certain thickness is placed on the test platform. The test platform moves the semiconductor sample between the active coil and the passive coil, performing planar motion. The electro-proportional valve is opened, and the pressure and flow rate of the inlet and outlet are controlled according to the set value of the time-gas flow curve. Then, the control system supplies alternating current to the active coil and reads the alternating current in the passive coil. The alternating current value in the passive coil at the current position is read multiple times. After completing the rated number of readings, the control system processes the data and calculates the conductivity value at the current position based on the current value. The test platform then moves the semiconductor sample to the next position, and the above actions are repeated until the data measurement at all positions is completed.

[0049] 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 semiconductor materials with cooling function, characterized in that, include: A standard silicon wafer with known conductivity is placed on a test platform. Simultaneously, a conductivity probe containing an active coil and a passive coil is moved to the area to be tested. During the test, a cooling nozzle including an air inlet, an air outlet, and a vent structure is used to cool the area to be tested. By testing the duration of the eddy current at the area to be tested on the standard silicon wafer, the coordination of the cooling nozzle with the cooling air supply, and the current data, an eddy current-cooling air calibration curve is formed, which is the relationship between the duration of the eddy current and the cooling air supply. The above process is repeated multiple times to obtain the eddy current-cooling air calibration curve corresponding to the area to be tested. The silicon wafer to be tested is moved to the test location, the conductivity probe is moved to the test location, and the cooling nozzle is used to perform cooling spray. According to the eddy current cooling gas calibration curve, the required air supply of the cooling nozzle is determined. At the same time, the conductivity of the test location is determined according to the standard relationship curve between the current in the passive coil and the conductivity of the standard silicon wafer. The cooling nozzle is positioned at a predetermined position in the hollow portion of the active coil or at a predetermined position above the hollow portion. An electro-proportional valve is connected to the rear end of the cooling nozzle to control the gas flow rate and pressure at the inlet and outlet. An air pump is connected to the rear end of the electro-proportional valve to provide cooling gas at a constant temperature. The cooling gas enters the cooling nozzle's air-cooling structure through the inlet, exchanges heat with the heat-affected zone of the standard silicon wafer or the silicon wafer under test, and is then discharged through the outlet, carrying away heat and maintaining the temperature of the heat-affected zone of the standard silicon wafer or the silicon wafer under test within a predetermined range.

2. The method for testing the eddy current conductivity of semiconductor materials with cooling function according to claim 1, characterized in that, The test platform on which the standard silicon wafer or the silicon wafer under test is placed is mounted on a two-dimensional motion platform.

3. The method for testing the eddy current conductivity of semiconductor materials with cooling function according to claim 2, characterized in that, The motion platform includes an X-axis motion module and a Y-axis motion module for moving the test platform in the X-axis and Y-axis directions.

4. The method for testing the eddy current conductivity of semiconductor materials with cooling function according to claim 3, characterized in that, The motion platform also includes a rotary motion module for rotating the test platform, which is mounted on the X-axis motion module or the Y-axis motion module.

5. The method for testing the eddy current conductivity of semiconductor materials with cooling function according to claim 1, characterized in that, The cooling nozzle is a cylindrical multi-hole structure with an outer diameter smaller than the inner diameter of the active coil. The cylindrical multi-hole structure has an air inlet in the middle, and the air outlets are evenly distributed around the air inlet. The lower part of the cooling nozzle has a concave air-gathering structure that can improve heat exchange efficiency and accommodate temporary storage of cold air.

6. The method for testing the eddy current conductivity of semiconductor materials with cooling function according to claim 5, characterized in that, The cooling nozzle is made of a non-metallic material.

7. The method for testing the eddy current conductivity of semiconductor materials with cooling function according to claim 5, characterized in that, The cross-sectional area of ​​the air inlet of the cooling nozzle is the same as the cross-sectional area of ​​all the air outlets.

8. The method for testing the eddy current conductivity of semiconductor materials with cooling function according to claim 1, characterized in that, The method also includes a control system for controlling the movement of the silicon wafer under test or the standard silicon wafer, supplying cooling air, and acquiring, analyzing and processing data.

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