Open-circuit fault positioning method

Abstract

The invention provides an open-circuit fault positioning method, which comprises the following steps of: providing a phase-locked signal source and a high-frequency signal source, and configuring the phase-locked signal source to output a low-frequency signal to a trigger end of the high-frequency signal source; modulating a high-frequency signal generated by the high-frequency signal source by using the low-frequency signal to form a high-frequency modulation signal, and outputting the high-frequency modulation signal to the tested sample to enable the open-circuit fault position of the tested sample to generate heat radiation; the infrared camera is used for detecting heat radiation generated by the detected sample so as to position the open-circuit fault position of the detected sample. According to the invention, the open-circuit fault can be quickly positioned, and the positioning success rate is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to an open circuit fault locating method. BACKGROUND

[0002] Failure analysis is an important part of semiconductor process research and yield improvement, and failure positioning plays a crucial role in the failure analysis process. The commonly used failure positioning tools in the semiconductor industry include photon emission microscope (EMMI), optical beam induced resistance change microscope (OBIRCH) and thermal emission microscope (Thermal). None of the three failure positioning tools is suitable for open circuit failure positioning, because under the excitation of direct current bias or low frequency signal, open circuit generates little or no thermal radiation.

[0003] At present, the packaging level open circuit failure positioning tool adopts time domain reflectometer (TDR), and the disadvantage of time domain reflectometer is low resolution and non-direct positioning of the physical position of the open circuit. The chip level open circuit failure positioning adopts electron beam absorption current (EBAC) method, and the surface positioning accuracy is high. With layer removal sample preparation, deep fault points can be located. For example, by removing the top metal layer for sample preparation, the fault point in the bottom metal layer can be located. The disadvantage of electron beam absorption current is that special sample preparation is required, the scanning time is long, and the single scanning area is small (less than 0.5mm*0.5mm). Especially for multi-layer metal and large size samples, the efficiency is low and the positioning is complex.

[0004] Lock-in thermography (LIT) is a non-destructive testing method based on infrared technology, which detects material properties or detects structural defects by modulating thermal signals. Lock-in thermography locates fault points by applying a low-frequency excitation signal and lock-in amplifying the thermal signals collected by the infrared camera. Then, due to the working frequency of the infrared camera, only low-frequency thermal radiation signals can be detected, and under the excitation of low-frequency signal, open circuit failure almost does not generate or generates little thermal radiation (i.e. almost no thermal signal is generated), and the infrared camera is difficult to detect open circuit failure. SUMMARY

[0005] The purpose of the present application is to provide an open circuit fault locating method, which can quickly locate the open circuit fault position and improve the success rate of positioning.

[0006] In order to achieve the above purpose, the present application provides an open circuit fault locating method, comprising:

[0007] providing a lock-in signal source and a high-frequency signal source, and configuring the lock-in signal source to output a low-frequency signal to the trigger end of the high-frequency signal source;

[0008] modulate the high frequency signal generated by the high frequency signal source to form a high frequency modulation signal, and output the high frequency modulation signal to the sample under test, so that the open-circuit fault position of the sample under test generates thermal radiation;

[0009] detect the thermal radiation generated by the sample under test by using an infrared camera to locate the open-circuit fault position of the sample under test.

[0010] Optionally, the low frequency signal is a square wave signal.

[0011] Optionally, the frequency of the low frequency signal is less than or equal to the working frequency of the infrared camera.

[0012] Optionally, the lock-in signal source comprises a signal-synchronized lock-in amplifier and a low frequency signal source, and the low frequency signal source outputs the low frequency signal.

[0013] Optionally, the infrared camera and the lock-in amplifier are signal-synchronized.

[0014] Optionally, after being modulated by the low frequency signal, the high frequency signal source outputs a high frequency signal when the trigger end thereof is at a high level, and does not output when the trigger end thereof is at a low level.

[0015] Optionally, the high frequency modulation signal periodically outputs a high frequency signal at the same frequency as the low frequency signal.

[0016] Optionally, the high frequency modulation signal is output to an open-circuit port of the sample under test.

[0017] Optionally, the sample under test comprises a chip, a package, and a PCB board.

[0018] Optionally, after detecting the thermal radiation generated by the sample under test by using the infrared camera, the method further comprises adjusting the frequency and amplitude of the high frequency signal in real time according to the detection result of the infrared camera.

[0019] In the open-circuit fault positioning method provided by the application, a phase-locked signal source and a high-frequency signal source are provided, the phase-locked signal source is configured to output a low-frequency signal to a trigger end of the high-frequency signal source; the low-frequency signal is used to modulate a high-frequency signal generated by the high-frequency signal source to form a high-frequency modulated signal, and the high-frequency modulated signal is output to a sample under test, so that the open-circuit fault position of the sample under test generates thermal radiation; and an infrared camera is used to detect the thermal radiation generated by the sample under test to position the open-circuit fault position of the sample under test. The application uses a high-frequency signal to generate thermal radiation at the open-circuit fault position, and detects the thermal radiation position by an infrared camera to position the open-circuit fault position; and after the high-frequency signal is modulated by a low-frequency signal, the open-circuit fault position generates thermal radiation under high-frequency excitation, and the thermal radiation has a low frequency to be detected by the infrared camera, so as to position the open-circuit fault position; and the method does not need to damage the sample under test for lossless fault positioning, can position the open-circuit fault while keeping the structure of the sample under test intact, and improves the success rate of positioning. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The flow chart of the open-circuit fault positioning method provided by an embodiment of the application is shown.

[0021] Figure 2 The block diagram of the open-circuit fault positioning method provided by an embodiment of the application is shown.

[0022] Figure 3 The waveform diagram of signal modulation in the open-circuit fault positioning method provided by an embodiment of the application is shown.

[0023] Figure 4 The positioning example diagram of the open-circuit fault point in the open-circuit fault positioning method provided by an embodiment of the application is shown.

[0024] In the drawings, the reference signs are as follows:

[0025] 10-phase-locked signal source; 11-low-frequency signal source; 12-phase-locked amplifier; 20-high-frequency signal source; 30-sample under test; 40-infrared camera. DETAILED DESCRIPTION

[0026] To make the purpose, technical solutions and advantages of the embodiments of the application clearer, the technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are some embodiments of the application, rather than all the embodiments of the application. The drawings are all very simplified and not drawn according to scale, and are only used to facilitate and clarify the purpose of explaining the embodiments of the application. In addition, the structures shown in the drawings are often part of the actual structures; in particular, the emphasis shown in each drawing is different, and sometimes different scales are used.

[0027] The following detailed description of embodiments of the application in the drawings provided in the accompanying drawings is not intended to limit the scope of the application claimed, but merely represents selected embodiments of the application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0028] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly understood by those skilled in the art, or the orientation or positional relationship commonly understood by those skilled in the art, only for the convenience of describing the present application and simplifying the description, and not indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0029] In addition, the relational terms such as "first" and "second" and the like are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of additional identical elements in the article or device including the element. The above terms can be specifically understood in the context of the present application.

[0030] Figure 1 The flowchart of the open circuit fault locating method provided by the present embodiment is shown in FIG. 1. Figure 1 The present embodiment provides an open circuit fault locating method, comprising:

[0031] Step S1: providing a locking signal source and a high-frequency signal source, configuring the locking signal source to output a low-frequency signal to the trigger end of the high-frequency signal source;

[0032] Step S2: using the low-frequency signal to modulate the high-frequency signal generated by the high-frequency signal source to form a high-frequency modulated signal, and outputting the high-frequency modulated signal to the measured sample, so that the open circuit fault position of the measured sample generates thermal radiation;

[0033] Step S3: using an infrared camera to detect the thermal radiation generated by the measured sample to locate the open circuit fault position of the measured sample.

[0034] Figure 2 The block diagram of the open-circuit fault locating method provided in the embodiment, Figure 3 The waveform diagram of signal modulation in the open-circuit fault locating method provided in the embodiment. The following will be described in combination with Figure 2 and Figure 3 The open-circuit fault locating method provided in the embodiment will be described in detail.

[0035] Please refer to Figure 2 and Figure 3 , execute step S1: provide a phase-locked signal source 10 and a high-frequency signal source 20, configure the phase-locked signal source 10 to output a low-frequency signal V L to the trigger end of the high-frequency signal source 20. In the embodiment, the phase-locked signal source 10 includes a low-frequency signal source 11 and a phase-locked amplifier 12, and the low-frequency signal source 11 and the phase-locked amplifier 12 are signal-synchronous, wherein the low-frequency signal source 11 outputs a low-frequency signal V L to the trigger end of the high-frequency signal source 20. In the embodiment, the low-frequency signal V L is a square wave signal (as shown in the uppermost waveform diagram in Figure 3 ), which is beneficial for phase-locked amplification. Since the working frequency of the infrared camera 40 can only detect a thermal radiation signal with a relatively low frequency, that is, a thermal radiation signal with a frequency less than or equal to the working frequency of the infrared camera 40 can be detected, it is required that the frequency of the low-frequency signal V L be less than or equal to (not higher than) the working frequency of the infrared camera 40, so that the infrared camera 40 can also detect the low-frequency signal after the low-frequency signal is used to modulate the high-frequency signal. Generally, the working frequency of the infrared camera 40 can be several tens of HZ, for example, the frequency of the low-frequency signal V L may be 1 HZ, which is not limited thereto.

[0036] Execute step S2: the high-frequency signal source 20 generates a high-frequency signal V H (as shown in the middle waveform diagram in Figure 3 ), and the frequency of the high-frequency signal V H may be several hundred KHZ to GHZ. Under the excitation of the high-frequency signal V H , a thermal radiation signal with the same frequency is generated, and the power of the thermal radiation signal is relatively large. The greater the frequency of the high-frequency signal V H , the greater the power of the thermal radiation signal with the same frequency generated, so as to generate sufficient thermal radiation. Since the open-circuit failure generates almost no or very little thermal radiation under the excitation of the low-frequency signal, the high-frequency signal V H is used for excitation, so that sufficient thermal radiation is generated at the open-circuit fault position; however, the working frequency of the infrared camera 40 can only detect a thermal radiation signal with a relatively low frequency, and if the high-frequency signal V HWhen applied to the sample 30, although sufficient thermal radiation can be generated at the open-circuit fault location, the frequency of the thermal radiation signal is too high to be detected by the infrared camera 40. Therefore, a low-frequency signal V is needed. L Demodulation of high-frequency signal V H To form a high-frequency modulation signal V T (like Figure 3 (As shown in the bottom waveform diagram).

[0037] Specifically, low-frequency signal source 11 outputs a low-frequency signal V. L The signal is transmitted to the trigger terminal of the high-frequency signal source 20, via the low-frequency signal V. L Modulation, the high-frequency signal source 20 is at a high level at its trigger terminal (i.e., low-frequency signal V) L When the signal is high, a high-frequency signal V is output. H The high-frequency signal source 20 is at a low level at its trigger terminal (i.e., low-frequency signal V). L When the signal is low, no output is generated, thus forming a high-frequency modulation signal V. T High-frequency modulated signal V T With low-frequency signal V L The same frequency periodically outputs a high-frequency signal for excitation, i.e., a high-frequency modulation signal V. T With low frequency signal V L At the same frequency, low-frequency signal V L The low frequency ensures that the frequency of the thermal radiation signal generated by subsequent positioning is within the operating frequency range of the infrared camera 40.

[0038] The high-frequency modulation signal V T The output is sent to the sample under test 30, due to the high-frequency modulation signal V T It periodically outputs a high-frequency signal to excite the open-circuit fault location in the tested sample 30, causing thermal radiation. Because the conductivity loss at the open-circuit fault location is relatively high, thermal radiation is generated at that location. In this embodiment, the tested sample 30 includes a chip, a package, and a PCB board, wherein the package is a product in which the chip is packaged. Figure 2 The sample 30 in the example is only for illustration. The high-frequency modulation signal V... T The output is sent to the open-circuit port of the sample under test 30 (the port can be a pin, pad, or lead), which can generate thermal radiation at the open-circuit fault location in the sample under test 30.

[0039] The step S3 is performed: under the excitation of the high-frequency signal, the open-circuit fault position in the measured sample 30 generates thermal radiation. Since the frequency of the excited thermal radiation signal is within the working frequency range of the infrared camera 40, the thermal radiation generated by the measured sample 30 can be detected by the infrared camera 40, so as to locate the open-circuit fault position of the measured sample 30. In the embodiment, the infrared camera 40 and the lock-in amplifier 12 are synchronized to lock the amplification of the low-frequency signal V L The thermal radiation signal has the same frequency.

[0040] Further, after detecting the thermal radiation generated by the measured sample 30 by the infrared camera 40, the excitation signal can be adjusted in real time according to the detection result of the infrared camera 40, that is, the frequency and amplitude of the high-frequency signal V H are adjusted. When the detection result of the infrared camera 40 is poor, the frequency and amplitude of the high-frequency signal V H are increased, so as to enhance the thermal radiation generated by the measured sample 30.

[0041] Figure 4 An example of locating the open-circuit fault point in the open-circuit fault locating method provided in the embodiment is shown in FIG. 6. Please refer to Figure 4 , Figure 4 The resistance to be measured in FIG. 6 is a vertical interconnection channel structure. Figure 4 In FIG. 6, the modulated 300MHz excitation signal is applied to one of the pads (the pad pointed by the cursor) of the measured sample on the left side, so as to locate a hot spot (shown in the red box), which indicates that the position is the open-circuit fault position. Figure 4 In FIG. 6, the enlarged view of the hot spot position is shown on the right side above. Figure 4 In FIG. 6, the circuit diagram corresponding to the hot spot position is shown on the right side below. The corresponding circuit position can be found through the hot spot position.

[0042] The method can locate the open-circuit fault position in a board, a package or a chip without damaging the measured sample, and improves the success rate of positioning. Compared with the TDR positioning, the method has higher resolution, and the hot spot position is superimposed on the photo of the measured sample, which is more intuitive than the waveform diagram of the TDR. Compared with the EBAC positioning, the method has a large scanning range (about 20cm*20cm), does not need to remove layers and make samples, and can locate from the back of the crystal, so as to quickly lock the open-circuit fault position and improve the positioning efficiency.

[0043] In summary, in the open-circuit fault positioning method provided by the application, a locking signal source and a high-frequency signal source are provided, the locking signal source is configured to output a low-frequency signal to a trigger end of the high-frequency signal source; the low-frequency signal is used to modulate a high-frequency signal generated by the high-frequency signal source to form a high-frequency modulated signal, and the high-frequency modulated signal is output to a measured sample, so that the open-circuit fault position of the measured sample generates thermal radiation; and an infrared camera is used to detect the thermal radiation generated by the measured sample to position the open-circuit fault position of the measured sample. The application utilizes the high-frequency signal to generate thermal radiation at the open-circuit fault position, and detects the thermal radiation position by the infrared camera to position the open-circuit fault position; and by modulating the high-frequency signal at a low frequency, the open-circuit fault position generates thermal radiation under high-frequency excitation, and at the same time, the thermal radiation changes at a low frequency to be detected by the infrared camera, so as to position the open-circuit fault position; and the method does not need to damage the measured sample for lossless fault positioning, and can position the open-circuit fault while keeping the structure of the measured sample intact, thereby improving the success rate of positioning.

[0044] The above is only the preferred embodiment of the application, and does not limit the application in any way. Any person skilled in the art can make any equivalent replacement, modification or change of the technical solutions and technical contents disclosed by the application without departing from the scope of the technical solutions of the application, and such change still falls within the protection scope of the application.

Claims

1. A method for locating open-circuit faults, characterized in that, include: Provide a phase-locked signal source and a high-frequency signal source, and configure the phase-locked signal source to output a low-frequency signal to the trigger terminal of the high-frequency signal source; The low-frequency signal is used to modulate the high-frequency signal generated by the high-frequency signal source to form a high-frequency modulated signal, and the high-frequency modulated signal is output to the sample under test so that thermal radiation is generated at the open circuit fault location of the sample under test. An infrared camera is used to detect the thermal radiation generated by the sample under test in order to locate the open circuit fault location of the sample under test.

2. The open-circuit fault location method as described in claim 1, characterized in that, The low-frequency signal is a square wave signal.

3. The open-circuit fault location method as described in claim 2, characterized in that, The frequency of the low-frequency signal is less than or equal to the operating frequency of the infrared camera.

4. The open-circuit fault location method as described in claim 1, characterized in that, The phase-locked signal source includes a phase-locked amplifier for signal synchronization and a low-frequency signal source, wherein the low-frequency signal source outputs the low-frequency signal.

5. The open-circuit fault location method as described in claim 4, characterized in that, The infrared camera and the lock-in amplifier are synchronized.

6. The open-circuit fault location method as described in claim 1, characterized in that, Modulated by the low-frequency signal, the high-frequency signal source outputs a high-frequency signal when its trigger terminal is at a high level, and does not output a high-frequency signal when its trigger terminal is at a low level.

7. The open-circuit fault location method as described in claim 1, characterized in that, The high-frequency modulation signal periodically outputs a high-frequency signal at the same frequency as the low-frequency signal.

8. The open-circuit fault location method as described in claim 1, characterized in that, The high-frequency modulation signal is output to the open port of the sample under test.

9. The open-circuit fault location method as described in claim 1, characterized in that, The tested samples include chips, packages, and PCBs.

10. The open-circuit fault location method as described in claim 1, characterized in that, After detecting the thermal radiation generated by the sample under test using the infrared camera, the method further includes adjusting the frequency and amplitude of the high-frequency signal in real time based on the detection results of the infrared camera.

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