Chip circuit defect detection system and method based on terahertz on-chip spectrum

Abstract

The invention provides a terahertz on-chip spectrum-based chip circuit defect detection system and method, and the system comprises a laser device which is used for generating femtosecond laser; the spectroscope is used for splitting the femtosecond laser into emitted light and received light; the transmitting end is used for generating terahertz waves after the transmitting light is incident, and the terahertz waves are coupled and transmitted to the receiving end; the receiving end is used for incidence of the receiving light and generating a current signal based on the receiving light and the terahertz wave; and the radio frequency probe is used for transmitting the current signal to a chip to be detected. According to the invention, traditional far-field detection is converted into near-field detection on the basis of the mode that the terahertz waves are coupled and transmitted from the transmitting end to the receiving end to generate the current signals for detection at the receiving end, so that the signal-to-noise ratio and the transmission efficiency can be remarkably improved, and the mode can be suitable for the terahertz waves with higher frequency, and the detection precision is improved. And the detection precision is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of chip detection, and in particular, to a chip circuit defect detection system and method based on terahertz on-chip spectroscopy. Background Art

[0002] At present, the rapidly developing integrated circuits have higher and higher requirements for back-end packaging and testing. Chips are developing towards the directions of low power consumption, integration, high speed, and miniaturization. The miniaturization of the integrated circuit size makes the wiring of internal chips more complex and diverse, and the three-dimensional development direction also brings huge technical challenges to failure analysis. Therefore, the packaging and testing technology is also known as one of the fastest developing technologies in recent years. With the continuous development of 2.5D and 3D packaging technologies, many new packaging technologies have emerged, such as system-in-package technology (SiP), through-silicon via technology (TSV), and wafer-level packaging technology (3D WLP). The complexity and diversity of packaging determine new challenges in the manufacturing process, resulting in more defects and damages during the process.

[0003] Electrical failure analysis is the first step in the failure analysis of integrated circuit packaging. Its purpose is to detect the electrical performance between chip pins, as well as possible abnormal open circuits, short circuits, and current leakage phenomena between the pins. Then, subsequent physical failure analyses such as optical microscopy imaging, ultrasonic imaging, thermal imaging, and ray imaging can be performed on the integrated circuit packaging. There are mainly two problems with traditional failure analysis detection means. First, for advanced processes, the resolution of commonly used detection methods is insufficient, making it difficult to meet the defect detection requirements for smaller sizes, such as defects in the order of dozens of micrometers. Second, the detection time is long. For imaging-based detections, ultrasonic or X-ray methods are generally commonly used for detection. However, ultrasonic detection requires the introduction of a medium, and for unknown defects, large-area detection is required. X-ray detection has poor detection effects on cracks and air layers, and the resolution is not high enough.

[0004] Chip circuit fault detection based on terahertz waves detects faults by transmitting terahertz waveforms. Its rising edge is in the femtosecond order of magnitude and the time jitter is in the picosecond order of magnitude. Therefore, it can handle defect accuracies in the range of a few micrometers to dozens of micrometers. At the same time, the detection belongs to waveform detection and does not require as much time as traditional imaging-based detections, so the timeliness is better. However, the existing circuit fault detections using terahertz waves adopt vector network analyzers. The frequency of the terahertz waves generated by vector network analyzers for detection is relatively low, making it difficult to further improve the detectable defect accuracy. Moreover, the existing terahertz wave detections belong to far-field detections, that is, terahertz waves need to be emitted and received into free space, resulting in large signal noise, low transmission efficiency, and the antenna is usually several centimeters to more than a dozen centimeters in size, and the transmission end even reaches dozens of centimeters in size, increasing the size of the detection equipment. Summary of the Invention

[0005] In view of the above problems, the present invention proposes a chip circuit defect detection system and method based on terahertz on-chip spectroscopy. It focuses the emitted light on the terahertz wave generated at the transmitting end and couples it to the receiving end. The receiving end then generates an electrical signal based on the received light and the coupled terahertz wave, and finally inputs the terahertz wave into the chip through a radio frequency probe to complete the detection of the chip. It can not only achieve terahertz wave detection at a higher frequency, effectively improve the detection accuracy, but also, since the transmission of the electrical signal belongs to near-field detection, compared with the transmission and reception in free space, it can significantly improve the signal-to-noise ratio and transmission efficiency, and the entire transmission structure and detection system are more compact.

[0006] The above object of the present invention is achieved by the following technical solutions:

[0007] A chip circuit defect detection system based on terahertz on-chip spectroscopy, comprising:

[0008] A laser for generating femtosecond laser;

[0009] A beam splitter for splitting the femtosecond laser into transmitted light and received light;

[0010] A transmitting end for generating a terahertz wave after the incident of the transmitted light, and coupling and transmitting the terahertz wave to the receiving end;

[0011] A receiving end for the incident of the received light, and generating a current signal based on the received light and the terahertz wave;

[0012] A radio frequency probe for transmitting the terahertz signal generated by the transmitting end to the chip to be detected.

[0013] In this technical solution, the laser of the detection system is used to emit femtosecond laser. After the femtosecond laser is split by the beam splitter, the transmitted light for incident on the transmitting end and the received light for incident on the receiving end are obtained. The transmitted light generates a terahertz wave after being focused and incident on the transmitting end, and the terahertz wave is coupled and transmitted to the receiving end. After the receiving end receives the terahertz wave, the terahertz wave electric field excites the carriers of the receiving end chip to generate a directional movement. At the same time, under the action of the received light, an electrical signal is generated and amplified by a current amplifier, so as to form a current signal at the receiving end. Finally, the terahertz signal continues to be transmitted to the radio frequency probe and further transmitted to the chip to be detected.

[0014] During detection, the radio frequency probe contacts the chip to be detected, and the generated terahertz wave signal is transmitted to the inside of the chip through the radio frequency probe. When encountering the condition of impedance mismatch, a detection echo signal is returned. By comparing the differences in the waveforms of the standard echo signal and the detection echo signal, it can be judged whether the chip to be detected is faulty, the type of fault and the location of the fault.

[0015] In this technical solution, the traditional far-field detection is transformed into near-field detection by coupling and transmitting terahertz waves from the transmitting end to the receiving end to generate a current signal for detection at the receiving end. This not only significantly improves the signal-to-noise ratio and transmission efficiency, but also this method can be applied to terahertz waves with higher frequencies, effectively improving the detection accuracy. In addition, since the signal transmission end of this signal transmission method is not free space, the detection system can use an antenna with a smaller size to complete the transmission. Therefore, the entire transmission structure and the structure of the detection system will be more compact, further improving the transmission efficiency and ensuring effective transmission coupling.

[0016] Further, the transmitting end includes a transmitting antenna and two mutually parallel first transmission lines connected to the transmitting antenna, and the first transmission lines are connected to a DC bias voltage source; the receiving end includes a receiving antenna and two mutually parallel second transmission lines connected to the receiving antenna, the second transmission lines are connected to the RF probe, and a galvanometer for weak signal amplification is also provided on the second transmission lines.

[0017] In this technical solution, the transmitting antenna at the transmitting end is arranged on two mutually parallel first transmission lines. The transmitting antenna is preferably made of terahertz transmitting chip material, such as InGaAs / InAlAs superlattice material. Preferably, the substrate of the transmitting antenna is InP, with a thickness of 1 μm to 5 μm and a period of 50 to 150 layers. A DC bias voltage source is also connected to the first transmission lines to apply an adjustable DC bias voltage to both ends of the transmitting antenna. When the emitted light is focused and incident on the transmitting antenna to activate the carriers, the DC bias voltage can make the carriers move in a directional manner, thereby radiating terahertz waves.

[0018] The receiving antenna at the receiving end is arranged on two mutually parallel second transmission lines. The receiving antenna is preferably made of InGaAs or InAlAs superlattice material. During the process of the terahertz waves generated at the transmitting end moving along the first transmission lines, they can be coupled and transmitted to the second transmission lines at the receiving end and transmitted to the receiving antenna, where they interact with the received light to form a current signal. The galvanometer connected to the second transmission lines is used to detect the current signal. A current amplifier is also connected to the second transmission lines to amplify the current signal for easy detection.

[0019] To improve the coupling transmission efficiency of terahertz waves and reduce the crosstalk between transmission lines at the same time, the distance between adjacent first transmission lines and second transmission lines is 5 μm to 20 μm. Preferably, the distance between the first and second transmission lines is 5 μm to 10 μm.

[0020] In the signal transmission structure of the present technical solution, millimeter-sized antenna materials can be used for the transmitting and receiving antennas, and the distance between each transmission line reaches the micron level, so that the area of the entire signal transmission structure is only millimeter-sized, which is much smaller than the existing transmission structures in the order of dozens of centimeters in size, effectively ensuring the effective transmission efficiency and transmission coupling, and at the same time greatly reducing the transmission structure and volume of the detection system.

[0021] Further, the four transmission lines can be arranged to be parallel to each other and extend along a straight line. This structure is simpler. If it is desired that the loss of the terahertz wave coupled and transmitted between the first and second transmission lines is smaller, a smaller distance is required between the first transmission line and the second transmission line; if it is desired that the crosstalk generated by the terahertz wave on the first transmission line is smaller, a larger distance is required between the first and second transmission lines. Therefore, preferably, the first transmission line is arranged in a multi-segment structure.

[0022] Further, the first transmission line is parallel to the second transmission line. The first transmission line includes a coupled transmission section and an uncoupled transmission section, and the distance between the coupled transmission section and the second transmission line is smaller than the distance between the uncoupled transmission section and the second transmission line.

[0023] In the present technical solution, the first transmission line is in a multi-segment structure, and the multi-segment structure includes a coupled transmission section and an uncoupled transmission section. All regions of the first transmission line except the coupled transmission section are uncoupled transmission sections. Among them, the distance between each point on the coupled transmission section and the second transmission line is closer, and the distance between each point on the uncoupled transmission section and the second transmission line is farther. By setting the coupled transmission section, the distance between the first and second transmission lines can be made closer, reducing the transmission loss of the terahertz wave and improving the transmission efficiency. Preferably, the transmitting antenna can be arranged on the coupled transmission section to efficiently couple the generated terahertz wave to the second transmission line after generation; at the same time, the distance between the uncoupled transmission section on the first transmission line and the second transmission line can be set farther, greatly reducing the crosstalk formed by the terahertz wave on the second transmission line when propagating on the uncoupled transmission section, while satisfying the high transmission efficiency and low crosstalk of the terahertz wave, which is beneficial to further improving the detection accuracy.

[0024] Preferably, the distance between the coupled transmission section and the second transmission line can be 5μm to 20μm, and the distance between the uncoupled transmission section and the second transmission line can be 15μm to 50μm.

[0025] Further, the coupled transmission section includes a transmission section parallel to the second transmission line and a connection section connecting the transmission section and the uncoupled transmission section, and the distance between the transmission section and the second transmission line is 5μm to 10μm.

[0026] In this technical solution, the transmission section of the coupled transmission section is mainly used for coupling terahertz waves, and the connection section is used to connect the transmission section and the non-coupled transmission section. Among them, the transmission section needs to be parallel to the second transmission line. Preferably, the distance between the transmission section and the second transmission line is 5 μm to 10 μm. There are various ways to set the connection section, which can extend along a straight line, a broken line or a curve, and different setting methods of the connection section also affect the final form of the coupled transmission section.

[0027] Preferably, the connection section is a straight line or a curve.

[0028] Preferably, the connection section is a straight line, and the included angle between the connection section and the transmission section is a right angle.

[0029] Preferably, the connection section can also be a curve.

[0030] Furthermore, the first included angle between the transmission section and the connection section, and the second included angle between the connection section and the non-coupled transmission section are both obtuse angles. In this technical solution, by setting the first included angle and the second included angle as obtuse angles, compared with right angles, the loss of terahertz waves propagating along the first transmission line can be reduced, and the transmission efficiency of terahertz waves can be further improved.

[0031] Furthermore, the coupled transmission section is located on the side of the receiving antenna away from the RF probe. In this technical solution, the terahertz waves coupled to the second transmission line through the coupled transmission section can better act on the received light focused by the receiving antenna.

[0032] Furthermore, photonic bandgap filters are provided on the first transmission line and the second transmission line. The photonic bandgap filters provided on the first and second transmission lines can eliminate the echo of the reflected signal during the detection process, so as to more effectively detect the detection echo signal returned by the chip to be detected.

[0033] Another object of the present invention is to provide a method for detecting chip circuit defects based on terahertz on-chip spectroscopy. This method is based on a special terahertz signal transmission method, and can achieve higher-frequency terahertz wave detection, significantly improving the signal-to-noise ratio and transmission efficiency compared with traditional far-field detection.

[0034] Specifically, a method for detecting chip circuit defects based on terahertz on-chip spectroscopy includes the following steps:

[0035] Generate femtosecond laser, and the femtosecond laser is split into transmitted light and received light;

[0036] The transmitted light is incident on the transmitting antenna to generate terahertz waves propagating along the first transmission line. The terahertz waves are coupled and transmitted to the second transmission line connected to the receiving antenna, and the terahertz waves interact with the received light at the chip at the receiving antenna to generate a current signal;

[0037] The terahertz signal is transmitted to the chip to be detected through a radio frequency probe, and a return detection echo signal is generated from the end of the chip to be measured. The echo signal interacts with the received light again at the receiving antenna to generate an electrical signal for detection;

[0038] Compare the detection echo signal of the chip to be detected with the standard echo signal of the standard chip sample, and judge whether the chip to be detected is faulty, as well as the type and location of the fault based on the comparison result.

[0039] In this technical solution, the current signal generated at the receiving antenna is transmitted along the transmission line to the radio frequency probe. The radio frequency probe contacts the circuit board of the chip to be detected, and transmits the terahertz current signal into the chip through the probe. When encountering impedance mismatch conditions, a return echo signal is generated and then returns to the receiving antenna. By comparing the waveform differences between the echo signals of the standard chip sample and the chip to be detected, it can be judged whether the chip to be detected is faulty and the type of the fault; at the same time, after obtaining the dielectric constant of the material of the chip to be detected in the terahertz frequency band, the transmission distance of the terahertz current signal inside the medium can also be calculated, and this distance can locate the specific position of the defect. This method is applicable to the high-precision detection of open and short circuit defects in 2.5D and 3D chip packages.

[0040] Further, the steps for judging whether the chip to be detected is faulty and the type of the fault are as follows:

[0041] Obtain the reference impedance information of each position of the standard chip sample based on the standard echo signal, and obtain the detection impedance information of each position of the chip to be detected based on the detection echo signal;

[0042] Calculate the reflection coefficient according to the reference impedance information and the detection impedance information;

[0043] If the reflection coefficient is 0, the chip to be detected has no fault;

[0044] If the reflection coefficient is 1, the chip to be detected has an open circuit fault;

[0045] If the reflection coefficient is -1, the chip to be detected has a short circuit fault.

[0046] Further, the steps for judging the fault position of the chip to be detected are as follows:

[0047] Obtain the dielectric constant of the material of the chip to be detected in the terahertz frequency band, the first time of the contact point between the radio frequency probe and the chip to be detected, and the second time when impedance mismatch appears in the detection echo signal, and calculate the fault position of the chip to be detected based on the dielectric constant, the first time, and the second time.

[0048] Compared with the prior art, the present invention has the following beneficial technical effects:

[0049] Based on the terahertz wave coupled and transmitted from the transmitting end to the receiving end, and in the way of generating a current signal for detection at the receiving end, the present invention transforms the traditional far-field detection into near-field detection, which can not only significantly improve the signal-to-noise ratio and transmission efficiency, but also this method can be applied to terahertz waves with higher frequencies, effectively improving the detection accuracy;

[0050] The signal transmission method of the present invention enables the transmitting and receiving antennas to adopt antenna materials with millimeter-scale sizes, and the distance between each transmission line reaches the micron scale, so that the area of the entire signal transmission structure is only millimeter-scale, which is much smaller than the transmission structure with a size of dozens of centimeters in the prior art in terms of size, effectively ensuring the effective transmission efficiency and transmission coupling, and simultaneously greatly reducing the transmission structure and volume of the detection system;

[0051] The present invention makes the distance between the first and second transmission lines closer by setting a coupling transmission section, reducing the transmission loss of the terahertz wave and improving the transmission efficiency. At the same time, the distance between the non-coupling output section and the second transmission line can be set farther, greatly reducing the crosstalk formed on the second transmission line when the terahertz wave propagates in the non-coupling transmission section, and simultaneously satisfying the high transmission efficiency and low crosstalk of the terahertz wave, which is beneficial to further improving the detection accuracy;

[0052] The present invention can reduce the loss of the terahertz wave propagating along the first transmission line and further improve the transmission efficiency of the terahertz wave by setting the first included angle between the transmission section and the connection section and the second included angle between the connection section and the non-coupling transmission section to obtuse angles. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0054] Figure 1 It is a structural block diagram of a chip circuit defect detection system based on terahertz on-chip spectroscopy provided by an embodiment of the present invention;

[0055] Figure 2 It is a schematic structural diagram of the transmitting end and the receiving end provided by an embodiment of the present invention;

[0056] Figure 3 It is a schematic diagram of the defect detection system testing the chip through a radio frequency probe provided by an embodiment of the present invention;

[0057] Figure 4 It is a schematic diagram of a setting method of the transmission line of the transmitting end provided by an embodiment of the present invention;

[0058] Figure 5 It is a schematic diagram of another setting method of the transmission line at the transmitting end provided by the embodiment of the present invention;

[0059] Figure 6 It is a schematic flowchart of a chip circuit defect detection method based on terahertz on-chip spectroscopy provided by the embodiment of the present invention.

[0060] Description of reference numerals: 1 - laser, 2 - beam splitter, 3 - transmitting end, 4 - receiving end, 5 - RF probe; 31 - first transmission line, 311 - connection section, 312 - transmission section, 32 - transmitting antenna, 33 - DC bias voltage source, 34 - first photonic bandgap filter, 35 - second photonic bandgap filter; 41 - second transmission line, 42 - receiving antenna, 43 - galvanometer, 44 - third photonic bandgap filter. Detailed implementation manners

[0061] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0062] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the protection scope of the present invention.

[0063] As Figure 1 shown, a chip circuit defect detection system based on terahertz on-chip spectroscopy proposed by the present invention includes:

[0064] A laser 1 for generating femtosecond laser;

[0065] A beam splitter 2 for splitting the femtosecond laser into transmitted light and received light;

[0066] A transmitting end 3 for generating terahertz waves after the incident of the transmitted light, and coupling and transmitting the terahertz waves to the receiving end 4;

[0067] A receiving end 4 for the incident of the received light, and generating an amplified current signal to be measured based on the interaction between the received light and the terahertz waves at the receiving chip end;

[0068] A radio frequency probe 5 for transmitting the terahertz signal generated by the transmitting end 3 to the chip to be detected;

[0069] As Figure 2 shown, wherein, the transmitting end 3 includes a transmitting antenna 32 and two mutually parallel first transmission lines 31 connected to the transmitting antenna 32, and the first transmission line 31 is connected to a DC bias voltage source 33; the receiving end 4 includes a receiving antenna 42 and two mutually parallel second transmission lines 41 connected to the receiving antenna 42, the second transmission line 41 is connected to the radio frequency probe 5, and a galvanometer 43 is further arranged on the second transmission line 41.

[0070] In some preferred embodiments, the parameters of the femtosecond laser are: wavelength 1560 nm, pulse width 100 fs, repetition frequency 100 MHz, and power 60 mW.

[0071] In some preferred embodiments, the radio frequency probe 5 is a GSG probe.

[0072] In some embodiments, the materials of the transmitting antenna 32 and the receiving antenna 42 are the same. In one or more embodiments, the transmitting antenna 32 and the receiving antenna 42 are selected from InGaAs or InAlAs superlattice materials. In some preferred embodiments, the substrate of the receiving antenna 42 is InP, with a thickness of 1 μm to 5 μm and a period of 50 to 150 layers.

[0073] In some preferred embodiments, in order to improve the coupling transmission efficiency of terahertz waves and at the same time reduce the crosstalk between transmission lines, the distance D3 between adjacent first transmission lines 31 and second transmission lines 41 is 5 μm to 20 μm. Preferably, the distance between the first and second transmission lines is 5 μm to 10 μm.

[0074] In one or more embodiments, the distance D1 between the two first transmission lines 31 is 5 μm to 15 μm. Preferably, the distance between the two first transmission lines 31 is 10 μm to 15 μm. Further preferably, this distance is 10 μm. In one or more embodiments, the distance D2 between the two second transmission lines 41 is 5 μm to 15 μm. Preferably, the distance between the two second transmission lines 41 is 10 μm to 15 μm. Further preferably, this distance is 10 μm. In some preferred embodiments, the distance between the two first transmission lines 31 is equal to the distance between the two second transmission lines 41.

[0075] In some embodiments, photon bandgap filters are arranged on the first transmission line 31 and the second transmission line 41.

[0076] In some preferred embodiments, as Figure 2As shown, two first transmission lines 31 extend in parallel. One end of the two first transmission lines 31 is connected to a first photonic bandgap filter 34, and the other end is connected to a second photonic bandgap filter 35. At the same time, the two first transmission lines 31 are also connected to a DC bias source 33. Two second transmission lines 41 also extend in parallel. One end of one second transmission line 41 is grounded, and the other end is connected to a galvanometer 43 through a third photonic bandgap filter 44. One end of the other second transmission line 41 is connected to a radio frequency probe 5, and the other end is also connected to the galvanometer 43 through the third photonic bandgap filter 44.

[0077] Based on the manner that the terahertz wave coupled and transmitted from the transmitting end 3 to the receiving end 4 generates a current signal for detection at the receiving end 4, the present invention transforms the traditional far-field detection into near-field detection, which can not only significantly improve the signal-to-noise ratio and transmission efficiency, but also this method can be applied to higher-frequency terahertz waves, effectively improving the detection accuracy. This transmission structure can be used not only for defect detection of chips, but also for detection of other new materials.

[0078] On the other hand, as Figure 2 shown, the first transmission line 31 is parallel to the second transmission line 41. The first transmission line 31 includes a coupled transmission section and an uncoupled transmission section. The distance between the coupled transmission section and the second transmission line 41 is less than the distance between the uncoupled transmission section and the second transmission line 41. By setting the coupled transmission section, the distance between the first and second transmission lines can be made closer, reducing the transmission loss of the terahertz wave and improving the transmission efficiency. In one or more embodiments, the transmitting antenna can be arranged in the coupled transmission section to efficiently couple the generated terahertz wave to the second transmission line 41. At the same time, the distance between the uncoupled transmission section on the first transmission line 31 and the second transmission line 41 can be set farther, greatly reducing the crosstalk formed by the terahertz wave on the second transmission line 41 when propagating in the uncoupled transmission section, while meeting the high transmission efficiency and low crosstalk of the terahertz wave, which is beneficial to further improving the detection accuracy. In one or more embodiments, the distance between the coupled transmission section and the second transmission line 41 can be 5 μm to 20 μm, and the distance between the uncoupled transmission section and the second transmission line 41 can be 15 μm to 50 μm.

[0079] Preferably, the coupled transmission section includes a transmission section 312 parallel to the second transmission line 41 and a connection section 311 connecting the transmission section 312 and the non-coupled transmission section. The transmission section 312 needs to be parallel to the second transmission line 41, and the distance between the transmission section 312 and the second transmission line 41 is 5 μm to 10 μm. The coupled transmission section is located on the side of the receiving antenna 42 away from the radio frequency probe 5. Both the first angle between the transmission section 312 and the connection section 311 and the second angle between the connection section 311 and the non-coupled transmission section are obtuse angles. There are various ways to arrange the connection section 311, and it can extend along a straight line, a broken line or a curve. Different arrangements of the connection section 311 also affect the final form of the coupled transmission section. The transmission section 312 of the coupled transmission section is mainly used for coupling terahertz waves, and the connection section 311 is used to connect the transmission section 312 and the non-coupled transmission section.

[0080] In this embodiment, the signal transmission method can use antenna materials with millimeter-scale dimensions for the transmitting and receiving antennas, and the distance between each transmission line reaches the micron scale, so that the area of the entire signal transmission structure is only millimeter-scale, which is much smaller than the existing transmission structures with dimensions of dozens of centimeters in the prior art, effectively ensuring the effective transmission efficiency and transmission coupling, and at the same time greatly reducing the transmission structure and volume of the detection system.

[0081] Preferably, as Figure 4 shown, both the first angle and the second angle in the first transmission line 31 are right angles. This structure can also achieve the coupled transmission of terahertz waves, but the loss of the right angle is higher than that of the obtuse angle.

[0082] Preferably, as Figure 5 shown, the connection section of the first transmission line 31 can also adopt a curve.

[0083] The present invention also provides a method for detecting chip circuit defects based on terahertz on-chip spectroscopy. As Figure 6 shown, the method includes the following steps:

[0084] Generate femtosecond laser, and the femtosecond laser is split into transmitted light and received light;

[0085] The transmitted light is incident on the transmitting antenna 32 to generate terahertz waves transmitted along the first transmission line 31. The terahertz waves are coupled and transmitted to the second transmission line 41 connected to the receiving antenna 42, and the terahertz waves and the received light generate current signals at the receiving antenna 42;

[0086] The current signal is transmitted to the chip under test through the radio frequency probe 5 and returns a detection echo signal;

[0087] Compare the detected echo signal of the chip to be detected with the standard echo signal of the standard chip sample, and based on the comparison result, determine whether the chip to be detected is faulty, the type of fault, and the location of the fault.

[0088] In this embodiment, as Figure 3 shown, after the emitted light is focused and incident on the transmitting antenna 32, the generated terahertz wave is transmitted to the second transmission line 41 in the bent coupling transmission section. After passing through the received light focusing incidence and terahertz wave transmission at the receiving antenna 42, a current signal is generated at the receiving antenna 42. The terahertz signal is transmitted along the transmission line to the RF probe 5. The RF probe 5 contacts the circuit board of the chip to be tested, and transmits the terahertz current signal into the chip through the probe. When encountering impedance mismatch conditions, a return signal is generated and then returns to the receiving antenna 42. By comparing the waveform differences between the echo signals of the standard chip sample and the chip to be detected, it can be determined whether the chip to be detected is faulty and the type of fault. At the same time, after obtaining the dielectric constant of the material of the chip to be detected in the terahertz frequency band, the transmission distance of the terahertz current signal inside the medium can also be calculated, and this distance can locate the specific location of the defect.

[0089] Among them, the steps for determining whether the chip to be detected is faulty and the type of fault are as follows:

[0090] Obtain the reference impedance information of each position of the standard chip sample based on the standard echo signal, and obtain the detected impedance information of each position of the chip to be detected based on the detected echo signal;

[0091] Calculate the reflection coefficient according to the reference impedance information and the detected impedance information;

[0092] If the reflection coefficient is 0, the chip to be detected has no fault;

[0093] If the reflection coefficient is 1, the chip to be detected has an open circuit fault;

[0094] If the reflection coefficient is -1, the chip to be detected has a short circuit fault.

[0095] In this embodiment, set the reference impedance information based on the standard chip sample as Z Ref , and the detected impedance information of the chip to be detected as Z L , then the reflection coefficient ρ can be calculated, and the calculation method is:

[0096] ;

[0097] According to the calculation result of the reflection coefficient, determine whether the chip to be detected is faulty and the type of the fault. If the reflection coefficient is 0, it indicates that there are no defects inside the circuit of the chip to be detected and the impedance is matched everywhere; if the reflection coefficient is 1, it indicates that there is an open - circuit defect inside the circuit, and at this time, the waveform of the detected echo signal is positive; if the reflection coefficient is - 1, it indicates that there is a short - circuit defect inside the circuit, and at this time, the waveform of the detected echo signal is negative.

[0098] Among them, the steps to determine the fault location of the chip to be detected are as follows:

[0099] Obtain the dielectric constant of the material of the chip to be detected in the terahertz frequency band, the first time when the radio - frequency probe contacts the chip to be detected, and the second time when impedance mismatch appears in the detected echo signal, and calculate the fault location of the chip to be detected based on the dielectric constant, the first time, and the second time.

[0100] In this embodiment, when it is determined that the circuit has a fault according to the reflection coefficient, the dielectric constant of the material of the chip to be detected in the terahertz frequency band can be obtained, and based on the dielectric constant, the first time, and the second time, calculate the flight distance of the terahertz current signal inside the medium. This distance is the position distance between the contact point of the radio - frequency probe 5 and the chip to be detected and the short - circuit or open - circuit defect. The calculation method is:

[0101] ;

[0102] Among them, c is the speed of light, t0 is the first time, t1 is the second time, is the dielectric constant.

[0103] The "first", "second", etc. (such as the first transmission line, the second transmission line, etc.) used in the present invention are only used to distinguish the corresponding components for the sake of clear description, and are not intended to limit any order or emphasize importance, etc. In addition, the term "connection" used in the present invention, without special explanation, can be directly connected or indirectly connected through other components.

[0104] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A chip circuit defect detection system based on terahertz on-chip spectroscopy, characterized in that, The system includes: A laser (1) for generating femtosecond laser; A beam splitter (2) for splitting the femtosecond laser into transmitted light and received light; A transmitting end (3) for generating terahertz waves after the incident of the transmitted light, and the terahertz waves are coupled and transmitted to a receiving end (4); A receiving end (4) for the incident of the received light and generating a current signal based on the received light and the terahertz waves; A radio frequency probe (5) for transmitting the terahertz signal generated by the transmitting end (3) to the chip to be detected.

2. The chip circuit defect detection system based on terahertz on-chip spectroscopy according to claim 1, wherein The transmitting end (3) includes a transmitting antenna (32) and two mutually parallel first transmission lines (31) connected to the transmitting antenna (32), and the first transmission line (31) is connected to a DC bias voltage source (33); the receiving end (4) includes a receiving antenna (42) and two mutually parallel second transmission lines (41) connected to the receiving antenna (42), the second transmission line (41) is connected to the radio frequency probe (5), and a galvanometer (43) for weak signal amplification is further provided on the second transmission line (41).

3. The chip circuit defect detection system based on terahertz on-chip spectroscopy according to claim 2, characterized in that, The first transmission line (31) is parallel to the second transmission line (41), the first transmission line (31) includes a coupled transmission section and an uncoupled transmission section, and the distance between the coupled transmission section and the second transmission line (41) is less than the distance between the uncoupled transmission section and the second transmission line (41).

4. The chip circuit defect detection system based on terahertz on-chip spectroscopy according to claim 3, wherein The coupled transmission section includes a transmission section (312) parallel to the second transmission line (41) and a connection section (311) connected between the transmission section (312) and the uncoupled transmission section, and the distance between the transmission section (312) and the second transmission line (41) is 5μm - 10μm.

5. The chip circuit defect detection system based on terahertz on-chip spectroscopy according to claim 4, wherein Both the first included angle between the transmission section (312) and the connection section (311) and the second included angle between the connection section (311) and the uncoupled transmission section are obtuse angles.

6. The chip circuit defect detection system based on terahertz on-chip spectroscopy according to claim 3, wherein, The coupled transmission section is located on the side of the receiving antenna (42) away from the radio frequency probe (5).

7. The chip circuit defect detection system based on terahertz on-chip spectroscopy according to any one of claims 2 to 6, characterized in that Photonic bandgap filters are provided on the first transmission line (31) and the second transmission line (41).

8. A method for detecting chip circuit defects based on terahertz on-chip spectroscopy, characterized in that, The method includes the following steps: Generating femtosecond laser, and splitting the femtosecond laser into transmitted light and received light; The transmitted light is incident on the transmitting antenna (32) to generate terahertz waves transmitted along the first transmission line (31), the terahertz waves are coupled and transmitted to the second transmission line (41) connected to the receiving antenna (42), and the terahertz waves and the received light generate a current signal at the receiving antenna (42); The terahertz waves generated by the transmitting end are transmitted to the chip to be detected through the radio frequency probe (5) and return a detection echo signal, and the echo signal interacts with the received light again at the receiving antenna (42) to generate an electrical signal for detection; Comparing the detection echo signal of the chip to be detected with the standard echo signal of the standard chip sample, and judging whether the chip to be detected is faulty, the type of fault and the location of the fault based on the comparison result.

9. The chip circuit defect detection method based on terahertz on-chip spectroscopy according to claim 8, wherein The steps for judging whether the chip to be detected is faulty and the type of fault are: Obtain the reference impedance information of each position of the standard chip sample based on the standard echo signal, and obtain the detection impedance information of each position of the chip to be detected based on the detection echo signal; Calculate the reflection coefficient according to the reference impedance information and the detection impedance information; If the reflection coefficient is 0, the chip to be detected has no fault; If the reflection coefficient is 1, the chip to be detected has an open circuit fault; If the reflection coefficient is -1, the chip to be detected has a short circuit fault.

10. The method for detecting chip circuit defects based on terahertz on-chip spectroscopy according to claim 8, wherein The steps for judging the fault position of the chip to be detected are as follows: Obtain the dielectric constant of the material of the chip to be detected in the terahertz frequency band, the first time when the radio frequency probe (5) contacts the chip to be detected, and the second time when impedance mismatch appears in the detection echo signal, and calculate the fault position of the chip to be detected based on the dielectric constant, the first time, and the second time.

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