A chip multi-physical field point-by-point scanning measurement imaging system and imaging method

Abstract

The present invention is a chip multi-physical field point-by-point scanning measurement imaging system and imaging method, in which FPGA performs pulse modulation on laser source and microwave source, and the measurement probe is composed of a diamond probe and a metal coil; the electric scanning device is composed of an electric displacement stage carrying the chip to be tested and the probe to perform multi-physical field point-by-point scanning on the chip surface; the signal processing device is composed of a spectrum analyzer and artificial intelligence processing, the spectrum analyzer can process and analyze the fluorescent signal collected by the optical path, and then automatically identify the chip surface defect points through artificial intelligence, and the microwave source directly connects to the chip to be tested. The microwave field is measured; the microwave source provides a microwave signal to the diamond probe when it is connected to the metal coil to measure the temperature. The present invention realizes the dual measurement of the chip surface temperature field and the microwave field, and uses artificial intelligence to screen good products, saving the chip design cycle and greatly improving the yield rate in the chip design process.

Description

Technical Field

[0001] The invention belongs to the technical field of chip multi-physical field measurement, and in particular relates to a chip multi-physical field point-by-point scanning measurement imaging method. Background Art

[0002] Chip manufacturing has gradually become the core technology of the manufacturing industry. However, today's integrated circuit process node has reached 7nm, which is technically close to the limit of semiconductor single crystal silicon, and Moore's Law proposed by Gordon Moore is failing. Against this background, the third-generation semiconductors with advantages such as high thermal conductivity, high breakdown field strength, high saturated electron drift rate, and high bonding energy have come onto the world stage. They will meet the new requirements of modern electronic technology for harsh conditions such as high temperature, high power, high voltage, high frequency, and radiation resistance. They are of great significance to 5G communications, electric vehicles, new energy, and national defense. Therefore, they have become a hot spot in the semiconductor research field of various countries. The substantial increase in integration and the extreme reduction in line width have increased the R&D cycle of the third-generation semiconductor chips and reduced the efficiency of good product delivery. Improper chip thermal management is the most common cause of chip failure, and temperature testing is an extremely important link.

[0003] However, the semiconductor temperature measurement technology and infrared microscopy imaging technology commonly used in the market can no longer meet today's requirements due to defects such as low resolution, narrow temperature measurement range, and low efficiency. A new high-resolution temperature field measurement technology is urgently needed.

[0004] In addition, the electromagnetic compatibility test of the chip cannot be ignored. Due to the characteristics of large product batches, high quality requirements, and strict operating procedures in the quality inspection of precision parts, the traditional manual method has high costs and low stability, especially in the fields of chip manufacturing and precision instrument manufacturing. Temperature measurement and electromagnetic compatibility testing are indispensable key steps in the chip design and manufacturing process, so high-precision and high-efficiency quality inspection solutions are needed. Summary of the invention

[0005] In view of the bottleneck problems of low resolution, low sensitivity and low measurement efficiency in the existing chip measurement technology, the present invention provides a chip surface multi-physical field scanning imaging method integrating microwave field and temperature field measurement. The present invention improves the resolution and measurement efficiency by using a sub-micron diamond tapered fiber probe, a micron-level stepping electric translation stage and an FPGA integrated board.

[0006] In order to achieve the above object, the present invention is achieved through the following technical solutions:

[0007] The present invention discloses a chip multi-physical field point-by-point scanning measurement and imaging system, comprising a laser source, an optical path, an FPGA, a metal coil, an avalanche photodiode, a spectrum analyzer, an electric displacement stage, a microwave source and a computer; the FPGA and the spectrum analyzer are connected to the computer; the laser source and the microwave source are connected to the FPGA; the laser source is used to generate a green laser; the microwave source is used to generate a modulated microwave signal; the FPGA is used to generate a pulse signal for controlling the laser source and the microwave source; the avalanche photodiode is used to collect a fluorescence signal; the spectrum analyzer is used to process the collected fluorescence signal; the electric displacement stage carries a chip to be tested to perform point-by-point scanning imaging; and the computer is used to write a software program to control the synchronous operation of each instrument.

[0008] A further improvement of the present invention is that the FPGA sends a pulse signal to modulate the laser source to generate a 532nm green laser with an adjustable duty cycle.

[0009] A further improvement of the present invention is that the diamond tapered optical fiber probe is a high-resolution diamond tapered optical fiber probe that is made by melting the optical fiber to make the tip into a cone shape by means of melting and taper, and then attaching diamond particles of similar size to the end of the optical fiber.

[0010] A further improvement of the present invention is that during scanning and imaging, the electric displacement stage is controlled by a computer, so that micron-level stepping electric scanning and imaging can be achieved.

[0011] The present invention is a chip multi-physical field point-by-point scanning measurement imaging method, comprising:

[0012] FPGA performs pulse modulation control on the laser generated by the laser source and the microwave signal generated by the microwave source. Diamond generates a red fluorescent sideband signal under the action of the laser and microwave. The signal is returned through the optical fiber, and then the laser signal is filtered out by a dichroic mirror. Finally, the signal is focused on the avalanche photodiode through the objective lens. The avalanche photodiode converts the optical signal into an electrical signal and transmits it to the spectrum analyzer, which is finally processed to obtain the data results.

[0013] When measuring the microwave field, the microwave source is directly connected to the chip to be tested, and the diamond is placed close to the chip surface to perform a Rabi oscillation experiment. The microwave field intensity at that point can be calculated by measuring the Rabi oscillation frequency. Finally, the diamond is controlled by an electric translation stage to scan point by point to obtain an imaging diagram of the microwave field on the chip surface.

[0014] When measuring temperature, the microwave source is connected to the metal coil, the microwave is transmitted to the metal coil, and the metal coil is placed near the diamond tapered fiber probe to keep the microwave field around the probe constant. Then they are placed close to the chip surface, and the zero-field D value of the NV color center is measured by ODMR technology. The temperature of the point is calculated according to the D value-temperature change formula, and finally the electric translation stage is used to control the diamond to scan point by point to obtain the temperature field imaging diagram of the chip surface.

[0015] The beneficial effects of the present invention are:

[0016] The present invention realizes high-resolution multi-physical field measurement of a chip, and can measure both the microwave field on the chip surface and the temperature field on the chip surface, thereby greatly improving the measurement accuracy and efficiency.

[0017] The present invention can be applied to the quality inspection of chips, advanced packaged chips and precision devices. Through physical field image data with high accuracy and high spatial resolution, it can accurately locate chip thermal design defects and hotspots, effectively guide chip design, shorten the R&D cycle, reduce costs, and propose precision device quality inspection solutions for small sample defect identification. Cooperate with upstream and downstream industries to provide an overall solution for chip testing.

[0018] The present invention has significant advantages in resolution and operating frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic block diagram of the structure of the imaging system of the present invention.

[0020] Figure 2 It is a detailed diagram of the process in which the green laser is emitted from the laser source and reaches the chip to be tested, and the red fluorescent signal is transmitted back to the spectrum analyzer in the present invention.

[0021] Figure 3 This is a diagram of a probe composed of a tapered optical fiber containing a diamond NV color center and a metal coil according to the present invention, wherein the diamond NV color center sample is at the tip of the probe.

[0022] Figure 4 This is a microwave field measurement imaging diagram in an embodiment of the present invention.

[0023] Figure 5 It is an imaging diagram of the surface temperature of the limiter chip in the embodiment of the present invention.

[0024] Figure 6 This is a diagram of the ODMR measurement results of the present invention.

[0025] Figure 7 It is a fitting diagram of the Rabi measurement results of the present invention. DETAILED DESCRIPTION

[0026] The following will disclose the embodiments of the present invention with drawings. For the purpose of clear description, many practical details will be described together in the following description. However, it should be understood that these practical details should not be used to limit the present invention. That is, in some embodiments of the present invention, these practical details are not necessary. In addition, for the purpose of simplifying the drawings, some conventional structures and components will be depicted in a simple schematic manner in the drawings.

[0027] like Figure 1 As shown, the present invention is a chip multi-physical field point-by-point scanning measurement and imaging system, the imaging system includes a laser source 5, a microwave source 12, an optical path, an FPGA system 9 for generating pulse signals, a measuring probe, a signal processing device, an electric scanning device and a computer 1, the laser source 5 and the microwave source 12 are electrically connected to the FPGA 9 respectively; the laser source 5 is used to generate laser; the microwave source 12 is used to generate a modulated microwave signal; the measuring probe is used to perform multi-physical field detection scanning imaging on the chip surface; it includes a diamond probe 11 and a metal coil 13, and the diamond NV color center is arranged at the lower end of the diamond probe 11.

[0028] like Figure 3 As shown, the diamond probe 11 is a diamond tapered optical fiber probe, the metal coil 13 surrounds the tapered optical fiber probe to provide microwaves for chip temperature measurement, and the optical fiber is fused into a tapered tip by means of fusion splicing. The diameter of the diamond tapered optical fiber and the diameter of the simple diamond attached to the tapered optical fiber are both 5 microns. The diameter of the conventional optical fiber end face is 125 microns, and the diameter of the tapered optical fiber of the present invention can reach 5 microns. With a 5-micron diamond particle sample, the fluorescence collection efficiency can be increased by 12 times.

[0029] The optical path includes a laser source 5 connected to the FPGA system 9, and the optical path also includes a dichroic mirror 6, a filter 7, an objective lens 10 and an avalanche photodiode 8. The microwave source 12 generates a microwave signal, the laser source 5 generates a laser signal, and the FPGA system 9 sends a pulse signal to modulate the laser source 5 and the microwave source 12 to generate a 532nm green laser and a high-frequency microwave with an adjustable duty cycle. The FPGA performs pulse subcarrier modulation on the microwave source, and two subcarriers are added to the microwave signal, that is, the FPGA modulation method for microwaves is adopted to achieve the measurement of the sideband signal with a better signal-to-noise ratio, so that the measurement signal-to-noise ratio is improved by 12dB.

[0030] The green laser generated by the laser source 5 enters the optical path and is refracted by the reflector toward the dichroic mirror 6, and is focused to the probe of the diamond NV color center at the lower end of the diamond probe 11 through the objective lens 10. The optical path is responsible for emitting green laser to excite the diamond NV color center and the optical path is responsible for collecting red fluorescence signals through the avalanche photodiode 8, and the fluorescence signals are collected in the signal collector 4; then the collected fluorescence signals are transmitted to the spectrum analyzer 3 of the signal processing device for analysis and processing. The signal processing device includes a spectrum analyzer 3 and an artificial intelligence system 2. The spectrum analyzer 3 processes and analyzes the red fluorescence signal collected by the signal collector 4 in the optical path, and then sends the data results to the RNN neural network, and then to the GAN network for imaging restoration, and finally automatically identifies the surface defects of the chip through the artificial intelligence system 2.

[0031] The artificial intelligence system consists of two parts, one is neural network processing, and the other is AI automatic defect recognition. Neural network processing refers to sending the data results processed by the spectrum analyzer into the RNN neural network to obtain a lower-precision image, and then sending it to the GAN neural network for image restoration and output of the imaging results, which can greatly improve the accuracy of the measurement result imaging map while shortening the imaging time and improving the imaging efficiency. AI automatic defect recognition refers to the use of artificial intelligence to automatically learn the chip data set, and then measure the temperature field and microwave field of the chip. When it is found that the measured value of the measured part is too different from the data obtained by simulation in the chip design process or the measurement data of the same part of other chips in the same batch, an alarm is issued to the engineer, indicating that there is a defect in this part of the chip, which greatly improves the chip factory yield.

[0032] The electric scanning device comprises an electric displacement stage 15, which is a micron-level three-dimensional electric displacement stage, on which a chip to be tested 14 is fixed, and the diamond probe 11 is placed on the surface of the chip to be tested 14, and the electric scanning device performs multi-physical field point-by-point scanning on the surface of the chip to be tested 14. The FPGA 9, the spectrum analyzer 3, and the electric displacement stage 15 are electrically connected to the computer 1 respectively;

[0033] The microwave source 12 measures the microwave field when it is directly connected to the chip to be tested 14. When measuring the microwave field, the microwave source 12 is directly connected to the chip to be tested 14, and the diamond probe 11 is placed close to the surface of the chip to be tested 14 to perform a Rabi oscillation experiment. The microwave field intensity at the point can then be calculated by measuring the Rabi oscillation frequency. Finally, the electric translation stage 15 controls the diamond probe 11 to scan point by point to obtain a microwave field imaging diagram of the chip surface.

[0034] When the microwave source 12 is connected to the metal coil 13, it provides a microwave signal to the diamond probe 11 to measure the temperature. When measuring the temperature, the microwave source 12 is connected to the metal coil 13, transmits the microwave to the metal coil 13, and then places the metal coil 13 near the diamond probe 11, so that the microwave field around the diamond probe 11 remains constant, and then the diamond probe 11 and the metal coil 13 are close to the surface of the chip to be tested 14, and then the zero field D value of the diamond NV color center is measured by the ODMR technology, and the temperature of the point is calculated according to the D value-temperature change formula, and finally the electric translation stage 15 controls the diamond probe 11 to scan point by point to obtain the chip surface temperature field imaging diagram.

[0035] like Figure 2 As shown, the laser source emits green laser light, which passes through the polarization system composed of a half-wave plate, a lens and a beam splitter. The laser light entering the polarization system will be divided into multiple optical paths. The parallel laser beam is focused on the acousto-optic modulator. After being pulse modulated by the FPGA, it is reflected by the reflector and shot into the aperture to limit the beam. It is then reflected by the dichroic mirror and focused by the objective lens and shot into the optical fiber. The probe at the end of the optical fiber is located above the surface of the chip to be tested. The diamond NV color center is excited by the green laser and emits red fluorescence. After returning to the original path, it passes through the dichroic mirror and the lens and then irradiates the photosensitive area of ​​the avalanche photodiode. The avalanche photodiode converts the collected red fluorescence signal into an electrical signal and transmits it to the spectrum analyzer for data processing. At the same time, the FPGA sends a pulse signal to modulate the microwave source. The high-frequency microwave signal is connected to the chip to be tested, and different microwave field intensities are displayed on the chip surface, which affects the diamond NV color center. The microwave field intensity at the diamond probe on the chip surface can be measured by measuring the Rabi oscillation frequency. Finally, the relative position change between the diamond probe and the chip to be tested is controlled by the electric translation stage. The microwave field distribution imaging diagram of the chip surface to be tested can be obtained by point-by-point measurement.

[0036] In addition, the present invention also provides an imaging method of a chip multi-physical field point-by-point scanning measurement imaging system, and the imaging method comprises the following steps:

[0037] Step 1: Computer 1 controls the FPGA system to send out a pulse signal to modulate the laser source and the microwave source to generate a 532nm green laser and a high-frequency microwave with an adjustable duty cycle;

[0038] Step 2: The microwave source is directly connected to the chip to be tested, and the diamond probe is placed close to the surface of the chip to be tested to perform a Rabi oscillation experiment. The Rabi measurement result fitting diagram is shown in FIG. Figure 7As shown, after the Rabi oscillation experiment, the microwave field intensity at that point can be calculated by measuring the Rabi oscillation frequency, and finally the diamond probe is controlled by the electric translation stage to scan point by point to obtain the microwave field imaging diagram of the chip surface; the microwave field measurement imaging diagram is shown in Figure 4 The microwave field measurement principle is based on the fact that the front section of the rabi oscillation is close to a linear rising straight line. The change of microwave field intensity will change the steepness of the front section. The increase of microwave field intensity will make this section steeper. The present invention only needs to fix the horizontal coordinate and measure the change of the vertical coordinate value to know the change of microwave field intensity.

[0039] Step 3: When measuring the temperature, the microwave source is connected to the metal coil to transmit the microwave to the metal coil, and then the metal coil is placed near the diamond probe to keep the microwave field around the diamond probe constant. Then the diamond probe and the metal coil are placed close to the surface of the chip to be tested, and the zero-field D value of the diamond NV color center is measured by ODMR technology. The temperature of the point is calculated according to the D value-temperature change formula: the temperature of the measuring point = (D-2870) × 0.074 + room temperature. Finally, the electric translation stage is used to control the diamond probe to scan point by point to obtain an imaging diagram of the chip surface temperature field. This embodiment provides a limiter chip surface temperature imaging, and the imaging picture is as follows: Figure 5 The specific ODMR measurement results are shown in the figure Figure 6 The D value refers to the lowest point between the two peaks, which will shift left and right due to the influence of temperature.

[0040] Step 4: The measurement results of step 2 and step 3 are processed by the artificial intelligence system, and defects are identified on the surface of the chip to be tested.

[0041] The present invention improves resolution and measurement efficiency by adopting a submicron diamond tapered optical fiber probe, a micron-level stepping electric displacement stage, and an FPGA integrated plate.

[0042] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A chip multi-physical field point-by-point scanning measurement imaging system, characterized in that: The system comprises a microwave source (12), an optical path, an FPGA system (9), a measuring probe, a signal processing device, an electric scanning device and a computer (1). The measuring probe comprises a diamond probe (11) and a metal coil (13), and a diamond NV color center is arranged at the lower end of the diamond probe (11); The optical path includes a laser source (5) connected to the FPGA system (9), and the optical path also includes a dichroic mirror (6), a filter (7), an objective lens (10) and an avalanche photodiode (8). The microwave source (12) generates a microwave signal, and the laser source (5) generates a laser signal. The FPGA system (9) sends a pulse signal to modulate the laser source (5) and the microwave source (12) to generate green laser and high-frequency microwaves. The green laser generated by the laser source (5) enters the optical path and is refracted by a reflector toward the dichroic mirror (6). The green laser is focused by the objective lens (10) to the probe of the diamond NV color center at the lower end of the diamond probe (11). The optical path is responsible for emitting green laser to excite the diamond NV color center and the optical path is responsible for collecting fluorescence signals through the avalanche photodiode (8). The fluorescence signals are collected in the signal collector (4). The electric scanning device comprises an electric displacement stage (15), a chip to be tested (14) is fixed on the electric displacement stage (15), the diamond probe (11) is placed on the surface of the chip to be tested (14), and the electric scanning device performs multi-physical field point-by-point scanning on the surface of the chip to be tested (14); The signal processing device comprises a spectrum analyzer (3) and an artificial intelligence system (2); the spectrum analyzer (3) processes and analyzes the red fluorescent signal collected by the avalanche photodiode (8) in the optical path, and then sends the data result to the artificial intelligence system to automatically identify defect points on the chip surface; When the microwave source (12) is directly connected to the chip to be tested (14), the microwave field is measured; When the microwave source (12) is connected to the metal coil (13), it provides a microwave signal to the diamond probe (11) to measure the temperature.

2. According to claim 1, a chip multi-physical field point-by-point scanning measurement imaging system is characterized in that: When measuring the microwave field, the microwave source (12) is directly connected to the chip to be tested (14), the diamond probe (11) is placed close to the surface of the chip to be tested (14), a Rabi oscillation experiment is performed, and the microwave field intensity at the point can be calculated by measuring the Rabi oscillation frequency. Finally, the diamond probe (11) is controlled by the electric displacement stage (15) to scan point by point to obtain a microwave field imaging diagram of the chip surface.

3. According to claim 1, a chip multi-physical field point-by-point scanning measurement imaging system is characterized in that: The diamond probe (11) is a diamond tapered optical fiber probe. The metal coil (13) surrounds the tapered optical fiber probe. The optical fiber is melted into a tapered tip by means of fusion taper. The diameter of the diamond tapered optical fiber is 5 microns. Diamond is attached to the tip of the tapered optical fiber. The diameter of the diamond is 5 microns.

4. According to claim 3, a chip multi-physical field point-by-point scanning measurement imaging system is characterized in that: When measuring temperature, the microwave source (12) is connected to the metal coil (13) to transmit microwaves to the metal coil (13), and then the metal coil (13) is placed near the diamond probe (11) so that the microwave field around the diamond probe (11) remains constant. Then, the diamond probe (11) and the metal coil (13) are placed close to the surface of the chip (14) to be measured, and the zero-field D value of the diamond NV color center is measured by ODMR technology. The temperature of the point is calculated according to the D value-temperature change formula, and finally, the diamond probe (11) is controlled by the electric translation stage (15) to scan point by point to obtain an imaging diagram of the chip surface temperature field.

5. According to claim 1, a chip multi-physical field point-by-point scanning measurement imaging system is characterized in that: The artificial intelligence system (2) includes two parts, one is neural network processing, and the other is AI automatic defect recognition, wherein the neural network processing refers to sending the data results processed by the spectrum analyzer into the RNN neural network to obtain a relatively low-precision image, and then sending it into the GAN neural network to perform image restoration and output the imaging result; AI automatic defect recognition refers to using artificial intelligence to automatically learn the chip data set, and then measure the temperature field and microwave field of the chip. When it is found that the measured value of the measured part is too different from the data obtained by simulation in the chip design process or the measurement data of the same part of other chips in the same batch, an alarm is issued to the engineer to indicate that there is a defect in this part of the chip.

6. A chip multi-physical field point-by-point scanning measurement imaging system according to any one of claims 1 to 5, characterized in that: The green laser and the high-frequency microwave are 532nm green laser and high-frequency microwave with adjustable duty cycle.

7. A chip multi-physical field point-by-point scanning measurement imaging system according to any one of claims 1 to 5, characterized in that: The electric displacement stage (15) is a micrometer-level three-dimensional electric displacement stage.

8. An imaging method of a chip multi-physical field point-by-point scanning measurement imaging system according to any one of claims 1 to 5, characterized in that: The imaging method comprises the following steps: Step 1: The computer (1) controls the FPGA system (9) to send a pulse signal to modulate the laser source (5) and the microwave source (12), thereby generating a 532nm green laser and a high-frequency microwave with an adjustable duty cycle; Step 2: The microwave source (12) is directly connected to the chip to be tested (14), and the diamond probe (11) is placed close to the surface of the chip to be tested (14), and a Rabi oscillation experiment is performed. The microwave field intensity at the point can be calculated by measuring the Rabi oscillation frequency, and finally the diamond probe (11) is controlled by the electric displacement stage (15) to scan point by point to obtain a microwave field imaging diagram of the chip surface; Step 3: When measuring the temperature, the microwave source (12) is connected to the metal coil (13) to transmit the microwave to the metal coil (13), and then the metal coil (13) is placed near the diamond probe (11) so that the microwave field around the diamond probe (11) remains constant. Then, the diamond probe (11) and the metal coil (13) are placed close to the surface of the chip to be measured (14), and then the zero-field D value of the diamond NV color center is measured by ODMR technology. The temperature of the point is calculated according to the D value-temperature change formula, and finally, the diamond probe (11) is controlled by the electric translation stage (15) to scan point by point to obtain an imaging diagram of the chip surface temperature field; Step 4: The measurement results of step 2 and step 3 are processed again by the artificial intelligence system (2), and at the same time, defects are identified on the surface of the chip to be tested (14).

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