Semiconductor device inspection method and semiconductor device inspection apparatus
By scanning light modulated at different frequencies on a semiconductor device and using phase difference analysis technology, the problem of difficult analysis of the electrical characteristics of multilayer semiconductor chips has been solved, and high-precision electrical characteristic estimation has been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HAMAMATSU PHOTONICS KK
- Filing Date
- 2021-04-05
- Publication Date
- 2026-07-10
Smart Images
Figure CN115552261B_ABST
Abstract
Description
Technical Field
[0001] One aspect of the implementation relates to a semiconductor device inspection method and a semiconductor device inspection apparatus. Background Technology
[0002] Currently, as a method for analyzing the electrical characteristics of semiconductor devices with three-dimensionally stacked semiconductor chips, locked-in optical beam-induced resistance change (OBIRCH) is known (see, for example, Non-Patent Document 1 below). According to this method, non-destructive fault analysis of semiconductor devices is achieved by scanning a laser on the semiconductor device and measuring changes in electrical characteristics such as resistance.
[0003] Existing technical documents
[0004] Non-patent literature
[0005] Non-patent document 1: KJP Jacobs et al., "Lock-in thermal laser stimulation for non-destructive failure localization in 3-D devices", Microelectronics Reliability, Vol. 76-77 (2017), Pages 188-193. Summary of the Invention
[0006] The problem that the invention aims to solve
[0007] In the existing methods described above, when dealing with semiconductor devices in which multiple semiconductor chips are stacked along the laser irradiation direction, it is desirable to analyze the electrical characteristics corresponding to the stacked structure.
[0008] Therefore, one aspect of the implementation is made in view of this problem, and its object is to provide a semiconductor device inspection method and a semiconductor device inspection apparatus that can resolve electrical characteristics corresponding to the stacked structure of semiconductor devices.
[0009] Methods for solving problems
[0010] One aspect of the semiconductor device inspection method includes: a measurement step, wherein, while supplying power to the semiconductor device, electrical characteristics corresponding to the power supply to the semiconductor device are measured; an acquisition step, wherein the semiconductor device is scanned with light modulated at a first frequency intensity and light modulated at a second frequency intensity higher than the first frequency, and characteristic signals representing the electrical characteristics of the first frequency component and the second frequency component corresponding to the scan are acquired; a determination step, wherein the frequency of a characteristic signal at a first scan position and a characteristic signal at a second scan position having a predetermined phase difference is determined, the characteristic signal at the first scan position reflecting the electrical characteristics of a first position in the optical axis direction of the semiconductor device, and the characteristic signal at the second scan position reflecting the electrical characteristics of a second position in the optical axis direction of the semiconductor device; a correction step, wherein, based on the phase component of the characteristic signal at the first scan position of the semiconductor device, the phase component of the characteristic signal at an arbitrary scan position is corrected; and an output step, wherein the characteristic signal at an arbitrary scan position at the determined frequency is acquired, and the in-phase component and quadrature component of the characteristic signal are output.
[0011] Alternatively, another aspect of the semiconductor device inspection apparatus includes: a measuring device that measures electrical characteristics corresponding to the power supply to the semiconductor device while supplying power to it; an optical scanning device that scans the semiconductor device with light modulated at a first frequency intensity and light modulated at a second frequency intensity higher than the first frequency; a signal acquisition device that acquires characteristic signals representing the electrical characteristics of the first frequency component and the second frequency component corresponding to the light scanning; and a processor that processes the characteristic signals; the processor determines the frequency of a characteristic signal at a first scanning position where the characteristic signal at the first scanning position and the characteristic signal at the second scanning position have a predetermined phase difference, the characteristic signal at the first scanning position reflecting the electrical characteristics of a first position in the optical axis direction of the semiconductor device, and the characteristic signal at the second scanning position reflecting the electrical characteristics of a second position in the optical axis direction of the semiconductor device; corrects the phase component of the characteristic signal at any scanning position based on the phase component of the characteristic signal at the first scanning position of the semiconductor device; acquires the characteristic signal at any scanning position at the determined frequency, and outputs the in-phase component and quadrature component of the characteristic signal.
[0012] According to one or the other aspect described above, while scanning a semiconductor device with light adjusted at a first frequency and light modulated at a second frequency, characteristic signals of the semiconductor device's electrical characteristics, measuring the first and second frequency components, are obtained. Furthermore, based on the obtained characteristic signals, the frequency at which the characteristic signal at the first scan position and the characteristic signal at the second scan position have a predetermined phase difference are determined. The characteristic signal at the first scan position reflects the electrical characteristics of the semiconductor device at a first position along the optical axis, and the characteristic signal at the second scan position reflects the electrical signal at the second position. Additionally, using the phase component of the characteristic signal at the first scan position as a reference, the phase component of the characteristic signal at any scan position is corrected to obtain the characteristic signal at any scan position at the determined frequency. The in-phase and quadrature components of the obtained characteristic signal are then output. Thus, the electrical characteristics of each layer at any scan position of the semiconductor device can be estimated, and the electrical characteristics corresponding to the stacked structure of the semiconductor device can be analyzed.
[0013] Invention Effects
[0014] According to one aspect of the present invention, the electrical characteristics corresponding to the stacked structure of a semiconductor device can be analyzed. Attached Figure Description
[0015] Figure 1 This is a schematic structural diagram of the semiconductor inspection device 1 according to the embodiment.
[0016] Figure 2 It is shown Figure 1 A block diagram illustrating an example of the hardware structure of the inspection device 19.
[0017] Figure 3 This is a diagram showing an example of the stacked structure of the semiconductor device S, which is the object of measurement in the semiconductor inspection apparatus 1.
[0018] Figure 4 It is a diagram showing an image representing the characteristic signals of multiple frequency components acquired by the inspection device 19 in a two-dimensional image.
[0019] Figure 5 It plots the phase component θ and the square root of the frequency f as analyzed by the inspection device 19. 1 / 2 A diagram showing the relationship between the two.
[0020] Figure 6 It plots the phase component θ and the square root of the frequency f, corrected by the inspection device 19. 1 / 2 A diagram showing the relationship between the two.
[0021] Figure 7 This shows the real and imaginary parts of the characteristic signal analyzed by the inspection device 19 and the square root of the frequency f. 1 / 2 A diagram illustrating an example of a relationship.
[0022] Figure 8 This shows the real and imaginary parts of the characteristic signal analyzed by the inspection device 19 and the square root of the frequency f. 1 / 2 A diagram illustrating an example of a relationship.
[0023] Figure 9 This shows the real and imaginary parts of the characteristic signal analyzed by the inspection device 19 and the square root of the frequency f. 1 / 2 A diagram illustrating an example of a relationship.
[0024] Figure 10 This is a diagram showing an example of a two-dimensional image of the in-phase component and a two-dimensional image of the orthogonal component output by the inspection device 19.
[0025] Figure 11 This is a flowchart showing the sequence of analytical processing of the semiconductor inspection device 1.
[0026] Figure 12 This is a diagram showing the output image of the analysis results of the inspection device 19.
[0027] Figure 13 This is a diagram showing an image of a difference image generated by a variation of this disclosure.
[0028] Figure 14 This is a diagram showing an image of an output image generated by a variation of this disclosure.
[0029] Figure 15 It is a vector diagram showing the corrected characteristic signal at each scan position at a frequency with a specified phase difference.
[0030] Figure 16 This is a diagram illustrating an example of the stacked structure of the semiconductor device S, the object of measurement in the modified inspection apparatus 19.
[0031] Figure 17 It is a graph showing the variation of each frequency of the characteristic signal obtained by the inspection device 19 of the modified example.
[0032] Figure 18 This is a diagram illustrating an example of the stacked structure of the semiconductor device S, the object of measurement in the modified inspection apparatus 19.
[0033] Figure 19 It plots the natural logarithm of the characteristic signal analyzed by the modified inspection device 19 and the square root of the frequency f. 1 / 2 A diagram showing the relationship between the two. Detailed Implementation
[0034] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, in the description, the same reference numerals are used for the same elements or elements having the same function, and repeated descriptions are omitted.
[0035] Figure 1 This is a schematic structural diagram of the semiconductor device inspection apparatus, namely semiconductor inspection apparatus 1, according to the embodiment. Semiconductor inspection apparatus 1 is a device used to measure the electrical characteristics of various parts of a semiconductor device (DUT) to analyze the fault locations of the device under test (DUT). Semiconductor devices with multiple semiconductor chips stacked in two or more layers are suitable for measurement by this semiconductor inspection apparatus 1. Furthermore, in Figure 1 In the diagram, solid arrows represent the flow of electrical signals between devices, while dashed arrows represent the flow of optical signals between devices.
[0036] That is, the semiconductor inspection apparatus 1 is configured to include: a measuring instrument 7 having a voltage application device 3 and a current measuring device 5, a light source 9, a signal source 11, a light scanning device 13, a lock-in amplifier (signal acquisition device) 15, a photodetector 17, and an inspection device 19. Hereinafter, each structural element of the semiconductor inspection apparatus 1 will be described in detail.
[0037] The measuring device 7 has two terminals that are electrically connected to the semiconductor device S. A constant voltage is applied to the circuit formed in the semiconductor device S by the voltage applying device 3 and power is supplied. The current flowing in the semiconductor device S between the two terminals according to the supply is measured as an electrical characteristic in the current measuring device 5.
[0038] The light source 9 is, for example, a laser source (irradiation source) that irradiates a laser. The light source 9 receives an AC signal generated at a variable frequency by the signal source 11 and generates a laser whose intensity is modulated by the frequencies contained in the AC signal. This AC signal can be a signal with a single frequency component or a signal containing multiple frequency components (e.g., a rectangular wave signal). The optical scanning device 13 guides the laser light irradiated from the light source 9 toward the semiconductor device S and irradiates it, and scans the irradiated position of the laser on the semiconductor device S in two dimensions along the surface of the semiconductor device S. Here, the two-dimensional scanning of the laser by the optical scanning device 13 is controlled by the inspection device 19. Additionally, the optical scanning device 13 guides the reflected light generated from the surface of the semiconductor device S according to the laser irradiation toward the photodetector 17. Furthermore, the light source 9 can also be an SLD or LED, a lamp light source, etc., that generates incoherent light.
[0039] Lock-in amplifier 15 monitors the AC signal output from signal source 11 and receives a characteristic signal representing the electrical characteristics measured by measuring device 7. It extracts the frequency component of the modulation frequency of the laser from the characteristic signal (lock-in detection) and outputs it to inspection device 19. At this time, lock-in amplifier 15 can also extract multiple frequency components based on multiple frequency components contained in the AC signal. Photodetector 17 receives the reflected light generated by semiconductor device S based on the laser scanned by optical scanning device 13 and outputs an intensity signal representing the intensity of the reflected light to inspection device 19.
[0040] The inspection device 19 is a data processing device electrically connected to the lock-in amplifier 15, the photodetector 17, and the light scanning device 13, controlling the two-dimensional scanning of the light scanning device 13, and processing the characteristic signal from the lock-in amplifier 15 and the intensity signal from the photodetector 17.
[0041] Figure 2 The hardware structure of the inspection device 19 is shown. For example... Figure 2 As shown, the inspection device 19 physically includes a computer, such as a processor (CPU, Central Processing Unit) 101, a recording medium (RAM, Random Access Memory) 102 or ROM (Read Only Memory) 103, a communication module 104, and an input / output module 106, all electrically connected. The inspection device 19 functions by loading programs into the CPU 101 and RAM 102, and, based on the control of the CPU 101, causing the communication module 104 and input / output module 106 to operate, and performing data reading and writing in the RAM 102. Furthermore, the inspection device 19 may also include a display, keyboard, mouse, touch panel display, etc., as input / output components, and may also include a hard disk drive, semiconductor memory, etc. Additionally, the inspection device 19 can be configured using multiple computers.
[0042] Figure 3 An example of the stacked structure of a semiconductor device S, the object of measurement in the semiconductor inspection apparatus 1, is shown. The semiconductor device S is, for example, a multilayer semiconductor device having at least: a first layer L1 including a semiconductor circuit section C1 and a wiring section W1, a second layer L2 including a semiconductor circuit section C2 and a wiring section W2, and an interlayer wiring section W12. Furthermore, in Figure 3The diagram of the insulating layer existing between the layers is omitted. In this semiconductor device S, as the voltage is applied by the voltage application device 3 of the semiconductor inspection device 1, current is generated only in the first layer L1 (region A1), only in the second layer L2 (region A2), and in both the first layer L1 and the second layer L2 (region A12), along the interlayer interface direction, i.e., the surface Su of the semiconductor device S. In this semiconductor device S, laser light is irradiated from the first layer L1 side with the optical axis of the laser approximately perpendicular to the interlayer interface (surface Su). As a result, heat is transferred from the location where the laser light is focused in the first layer L1. Therefore, the characteristic signal obtained by irradiating region A1 reflects the electrical characteristics of the first layer L1 located at the first position close to the light source 9 in the optical axis direction. In addition, the characteristic signal obtained by irradiating region A2 reflects the electrical characteristics of the second layer L2 located at the second position away from the light source 9 in the optical axis direction. In addition, the characteristic signal obtained by irradiating region A12 reflects the electrical characteristics of both the first layer L1 and the second layer L2.
[0043] The function of the inspection device 19 will be described in detail below.
[0044] The inspection device 19 controls the optical scanning device 13 to scan at least two dimensions of regions A1, A2, and A12 on the semiconductor device S, including a laser modulated at a first frequency f1 and a laser modulated at a second frequency f2 (higher than the first frequency). In this embodiment, the inspection device 19 also controls the scanning of the semiconductor device S by scanning lasers modulated at multiple frequencies other than the first and second frequencies f1 and f2. These lasers modulated at multiple frequencies can also irradiate separately. Alternatively, a state similar to simultaneous irradiation of lasers modulated at multiple frequencies can be achieved by using a laser modulated at a rectangular wave intensity.
[0045] Furthermore, the inspection device 19, under the control of laser scanning at the aforementioned multiple modulation frequencies f1, f2, ..., acquires characteristic signals locked for detection at each of the multiple frequency components f1, f2, ... as signals expressed in terms of their phase and amplitude or complex values at each scanning position of the semiconductor device S, and converts these characteristic signals into two-dimensional images for analysis. Figure 4 The image shown represents a two-dimensional image of the characteristic signal of each of the multiple frequency components acquired by the inspection device 19. This two-dimensional image may also be filtered using filters such as Gaussian filters.
[0046] Here, each of the at least one scan position contained in region A1 of the semiconductor device S and each of the at least one scan position contained in region A2 of the semiconductor device S is preset by the user in the inspection device 19 based on design data. Alternatively, each scan position is automatically determined in advance in the inspection device 19 based on design data. Alternatively, the inspection device 19 may also set the location where the phase component changes with frequency to a minimum as the scan position.
[0047] Furthermore, the inspection device 19 acquires the phase component θ of the characteristic signal obtained at each scanning position, and analyzes the phase component θ and the square root of the frequency f at each scanning position. 1 / 2 The relationship. In Figure 5 The diagram shows the phase component θ and the square root of the frequency f as analyzed by the inspection device 19. 1 / 2 The relationship is illustrated in the diagram. Thus, the analytical point P1 corresponding to the scan position in region A1, the analytical point P2 corresponding to the scan position in region A2, and the analytical point P12 corresponding to the scan position in region A12 are obtained in a manner with different characteristics. Furthermore, the inspection device 19 may not necessarily resolve the relationship between the phase component θ and the square root of the frequency f. 1 / 2 The relationship can also be analyzed to determine the relationship between the phase component θ and the frequency f.
[0048] Furthermore, the inspection device 19 corrects each resolution point of the phase component θ at any scanning position obtained as described above, using a previously known resolution point P1 at the same frequency at the scanning position as a reference, by canceling the phase component θ at resolution point P1. At this time, if the value of the phase component θ changes discontinuously from -π to π (or vice versa) due to the cancellation of the phase component θ, the inspection device 19 processes it by adding -2π (or 2π) to the phase component θ to ensure phase continuity so as not to hinder subsequent resolution. Figure 6 The diagram shows the phase component θ, corrected by the inspection device 19, versus the square root of the frequency f. 1 / 2 A graph showing the relationship. The phase component θ, thus corrected, is relative to the square root of the frequency f. 1 / 2 The characteristics exhibit different properties across regions A1, A2, and A12. Specifically, the characteristic corresponding to region A1 always has a value close to zero, while the characteristic corresponding to region A2 has a value equal to the square root f of the frequency. 1 / 2 The linear characteristic of the slope α, and the characteristic corresponding to region A12, becomes the characteristic with extrema.
[0049] Furthermore, the inspection device 19 processes specific signals reflecting the phase component θ corrected in the above manner at each scan position. That is, the inspection device 19 determines the frequency of the characteristic signal of the scan position contained in the predetermined region A1 and the characteristic signal of the scan position contained in the predetermined region A2, which is a predetermined phase difference. As an example, the predetermined phase difference is π / 2 (90 degrees).
[0050] exist Figure 7 Parts (a) and (b) respectively show the real and imaginary parts of the characteristic signal of the scan position contained in region A1 and the square root of the frequency f. 1 / 2 An example of a relationship, in Figure 8 Parts (a) and (b) respectively show the real and imaginary parts of the characteristic signal of the scan position contained in region A2 and the square root of the frequency f. 1 / 2 This is an example of a relationship. Thus, the real part of the characteristic signal at each scan position has the characteristic of decreasing with increasing frequency; the imaginary part of the characteristic signal at the scan position contained in region A1 is always zero after correction; and the imaginary part of the characteristic signal at the scan position contained in region A2 varies with frequency. The inspection device 19 obtains the frequency f* at which the real part of the corrected characteristic signal at the scan position contained in region A2 is approximately zero, using a frequency with a phase difference of π / 2. At this time, the inspection device 19 can also use the square root of the frequency f*... 1 / 2 Curve fitting of a function of the independent variable predicts the frequency characteristics of the corrected characteristic signal at the scan position contained in region A2, and uses the predicted function to obtain the frequency f* where the real part is approximately zero. For example, a polynomial function is used for curve fitting. When using a polynomial function, the function is appropriately pre-defined in a way that prevents the maximum order from becoming excessively large.
[0051] Here, when the inspection device 19 obtains the frequency of a predetermined phase difference between the characteristic signals of the two scanning positions, it may also use the characteristic signal before the phase component is corrected based on the phase of one of the characteristic signals. In this case, in order to obtain the frequency with a phase difference of π / 2, the inspection device 19 obtains the frequency at which the product of the complex number representing the characteristic signal of one and the conjugate of the complex number representing the characteristic signal of the other is zero.
[0052] Furthermore, the inspection device 19 calculates the characteristic signal with frequency f* obtained as described above by means of the frequency characteristics of the corrected characteristic signal at an arbitrary scanning position. Figure 9 Parts (a) and (b) show the real and imaginary parts of the characteristic signal at any scan position and the square root of the frequency f. 1 / 2 An example of a relationship. In this case, the inspection device 19 can use the square root of the frequency f. 1 / 2Curve fitting of a function of the independent variable is used to predict the frequency characteristics of the corrected characteristic signal at any scanning position, and the real and imaginary parts of the frequency f* are calculated using the predicted function. For example, a polynomial function is used for curve fitting. When using a polynomial function, the function is appropriately preset in a way that prevents the maximum order from becoming too large. On the other hand, the inspection device 19 can also re-obtain the characteristic signal at any scanning position of frequency f* based on the characteristic signal obtained by scanning the semiconductor device S using a laser whose modulation frequency includes frequency f*.
[0053] The inspection device 19 repeatedly acquires a characteristic signal of frequency f* at each scan position on the semiconductor device S, and acquires the real and imaginary parts of the characteristic signal at each scan position. Furthermore, the inspection device 19 outputs the real and imaginary parts of the characteristic signal acquired at each scan position as two-dimensional images showing the in-phase and quadrature components of the characteristic signal, respectively, to an input / output module 106 such as a display.
[0054] exist Figure 10 The image shown is a two-dimensional image G of the in-phase components output by the inspection device 19. I and the two-dimensional image G of the orthogonal components Q One example is this. Thus, by obtaining a characteristic signal with a phase difference of π / 2 at a frequency, in a two-dimensional image G... I The distribution of electrical characteristics of the first layer L1 of the semiconductor device S is reflected in the two-dimensional image G. Q The distribution of electrical characteristics of the second layer L2 of the semiconductor device S is reflected on the image. Furthermore, by acquiring characteristic signals with frequencies having arbitrary phase differences, the two-dimensional image G is also used. I The image above reflects the distribution of electrical characteristics of the first layer L1 and the second layer L2 of the semiconductor device S at a specified scale, in a two-dimensional image G. Q The above only reflects the distribution of electrical characteristics of the second layer L2 of the semiconductor device S.
[0055] Next, the sequence of analysis processing for the semiconductor device S using the semiconductor inspection apparatus 1 of this embodiment, i.e., the flow of the semiconductor device inspection method of this embodiment, will be described. Figure 11 This is a flowchart showing the sequence of analytical processing of the semiconductor inspection device 1.
[0056] First, the power supply to the semiconductor device S and the measurement of the electrical characteristics of the semiconductor device S are started by the measuring device 7 (step S1). Next, the operation of the optical scanning device 13 is controlled by the inspection device 19, and while the laser modulated at the intensity of the first frequency f1 scans the semiconductor device S in two dimensions, the inspection device 19 acquires the characteristic signal locked and detected by the lock-in amplifier 15 at the first frequency f1 (step S2).
[0057] In addition, the inspection device 19 acquires a two-dimensional image showing the two-dimensional distribution of the acquired characteristic signals (step S3). Thereafter, the modulation frequency of the laser is sequentially changed to a second frequency f1, and frequencies other than the first and second frequencies f1, f2 (step S4), and the processing of steps S2 and S3 is repeated to acquire multiple characteristic signals that are locked and detected at multiple frequencies f2, ... respectively.
[0058] Next, using the inspection device 19, based on the characteristic signals at each scanning position, the phase component θ of the characteristic signal is analyzed relative to the square root f of the frequency. 1 / 2 Based on the relationship between the phase components of the scanning positions in region A1 of the semiconductor device S, the resolution point of the phase component θ of any scanning position is corrected (step S5). Furthermore, the frequency at which the difference between the phase component θ of the scanning position in region A1 and the phase component of the scanning position in region A2 is a predetermined phase difference is obtained by the inspection device 19 (step S6). Each scanning position in regions A1 and A2 is preset by the user.
[0059] Subsequently, using the inspection device 19, based on the corrected characteristic signal at a scan position on the semiconductor device S, the real and imaginary parts of the frequency characteristic signal obtained in step S6 are calculated (step S7). Next, by sequentially changing the scan position of the object to be analyzed (step S8) and repeating the process of step S7, the real and imaginary parts of multiple characteristic signals at multiple scan positions are obtained.
[0060] Furthermore, the inspection device 19 converts the real and imaginary values of all scanned positions into a two-dimensional image showing the in-phase and orthogonal components (step S9). Finally, the inspection device 19 outputs the images of the in-phase and orthogonal components (step S10).
[0061] exist Figure 12 The image shown is the output image of the analysis result from the inspection device 19. The inspection device 19 outputs, for example, side-by-side: an optical image G1 of a semiconductor device based on the intensity signal obtained from the photodetector 17; and an image G showing the in-phase and quadrature components of the characteristic signal at a specified arbitrary frequency. 2I G 2QThe image G shows the in-phase and quadrature components of the characteristic signal obtained by the above analytical processing. 3I G 3Q In addition, the inspection device 19 can simultaneously output graphs GR1 and GR2 showing the frequency characteristics of the phase components of the characteristic signals at two preset scan positions Ref1 and Ref2, and graph GR3 showing the frequency characteristics of the phase components of the characteristic signals at any scan position specified by the user. The frequency of the specified phase difference can also be shown on graph GR2.
[0062] The semiconductor inspection apparatus 1 described above acquires characteristic signals of the electrical characteristics of the semiconductor device S by scanning a semiconductor device S with a laser modulated at multiple frequencies f1, f2, ... while locking and detecting the device. These characteristic signals contain multiple frequency components. Based on the acquired characteristic signals, frequencies are determined such that the characteristic signal reflecting the electrical characteristics of the first layer L1 of the semiconductor device S has a predetermined phase difference with the characteristic signal reflecting the electrical characteristics of the second layer L2. Furthermore, the phase component of the characteristic signal at any scanning position is corrected based on the phase component of the characteristic signal reflecting the electrical characteristics of the first layer L1, and the characteristic signal at any scanning position at the determined frequency is acquired. The in-phase and quadrature components of the acquired characteristic signal are then output. Thus, the electrical characteristics of each layer L1 and L2 at any scanning position of the semiconductor device S can be estimated, and the electrical characteristics corresponding to the stacked structure of the semiconductor device S can be analyzed.
[0063] Specifically, in this embodiment, the phase difference specified above is set to π / 2. In this case, the in-phase and quadrature components of the output characteristic signal directly represent the electrical characteristics of each layer L1 and L2. As a result, the electrical characteristics of each layer L1 and L2 at any scan position of the semiconductor device S can be easily analyzed.
[0064] Furthermore, this embodiment outputs an image showing the two-dimensional distribution of the in-phase component of the characteristic signal and an image showing the two-dimensional distribution of the quadrature component of the characteristic signal. With this structure, the distribution of the in-phase and quadrature components of the characteristic signal can be visually captured, and the electrical characteristics corresponding to the stacked structure of the semiconductor device S can be easily analyzed.
[0065] Furthermore, the phase component of the characteristic signal at any scan position is corrected by canceling the phase component of the characteristic signal at the scan position within region A1. Through this operation, the relative value of the phase component of any scan position with respect to the phase component of the characteristic signal at the scan position reflecting the electrical characteristics of layer L1 can be obtained. As a result, the electrical characteristics of each layer L1 and L2 at any scan position of the semiconductor device S can be easily estimated based on the output value of the characteristic signal at any scan position.
[0066] Furthermore, in this embodiment, the frequency of the characteristic signal with a predetermined phase difference is obtained by predicting the frequency characteristics of the characteristic signal through curve fitting. Based on this structure, the frequency at which the phase difference between the characteristic signals at two scanning positions is a predetermined phase difference can be obtained with high precision. As a result, the electrical characteristics corresponding to the stacked structure of the semiconductor device S can be analyzed with high precision.
[0067] Furthermore, in this embodiment, the characteristic signal at the obtained frequency is obtained by predicting the frequency characteristics of the characteristic signal at any scanning position through curve fitting. Based on this structure, the characteristic signal at the obtained frequency at any scanning position can be obtained with high precision. As a result, the electrical characteristics corresponding to the stacked structure of the semiconductor device S can be analyzed with high precision.
[0068] While various embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and may be modified or applied to other embodiments without changing the spirit of the claims.
[0069] For example, in the inspection device 19, an image showing the two-dimensional distribution of the difference between the phase component θ of the characteristic signal locked at a first frequency f1 and the phase component θ of the characteristic signal locked at a second frequency f2, which is higher than the first frequency f1, can also be generated and output. For example, as Figure 13 As shown, it can also be based on the image G showing the phase component θ at the first frequency f1. f1 The image G shows the phase component θ at the second frequency f2. f2 The generated image reflects each image G f1 G f2 The difference image G of the phase component θ diff Based on such difference image G diff This allows for the visual acquisition of layer depth information at each scan position of the semiconductor device S. The inspection device 19 outputs a differential image G. diff In this case, the difference in phase component θ can also be represented by the intensity, or the difference can be converted into hue by referring to LUT (Look-up Table) and output.
[0070] Alternatively, the semiconductor inspection apparatus 1 can also perform a two-dimensional laser scan by staggering and repeating one-dimensional scans along multiple lines on the semiconductor device S in a direction perpendicular to the lines, and by alternating the modulation frequency of each one-dimensional scan with a first frequency f1 and a second frequency. For example, the first frequency f1 can be set to 1 Hz, and the second frequency to 4 Hz. Figure 14The image shown is a two-dimensional distribution of the phase component θ generated by locking and detecting each line corresponding to modulation frequencies f1 and f2 using the semiconductor inspection apparatus 1 of this variant example. out This is one example. Through this variation, the electrical characteristics of layer L3, which is located far from the light source 9, and the electrical characteristics of layer L4, which is located close to the light source 9, can also be easily determined.
[0071] Furthermore, in the inspection device 19, the phase difference between the characteristic signals of the two pre-set scanning positions is determined to be a frequency such as π / 2, but this phase difference can also be set to any angle θ. Alternatively, the inspection device 19 can also, conversely, first set a frequency f*, and then determine the phase difference θ of that frequency f* based on the frequency characteristics of the phase components of the two scanning positions.
[0072] Figure 15 The diagram shows a vector representing the corrected characteristic signal at each scan position at a frequency f* that becomes the phase difference θ, on the IQ plane with the real axis as I and the imaginary axis as Q. Region A12 is shown in part (a). Figure 3 The characteristic signal in the image is shown in part (b), and the characteristic signal in region A1 is shown in part (c). Thus, the corrected characteristic signal SG has the following components in region A1: a component of characteristic signal SG1 representing the electrical characteristics of the first layer L1, having only the in-phase component I; a component of characteristic signal SG2 representing the electrical characteristics of the second layer L2, having phase θ; and a component SG1+SG2, which is a combination of the components of characteristic signal SG1 from the first layer L1 and characteristic signal SG2 from the second layer L2. That is, the in-phase component SG of the characteristic signal at any scan position... I and orthogonal component SG Q It is represented by the following formula.
[0073] SG Q =|SG2|*sinθ
[0074] SG I =|SG1|+|SG2|*cosθ
[0075] Utilizing the properties described above, the inspection device 19 examines the in-phase component S of the characteristic signal at each scanning position at a frequency f* that becomes a phase difference θ. I and orthogonal component S Q The values of the characteristic signals of layer 1 (L1) and layer 2 (L2) at any scanning position, |SG1| and |SG2|, are obtained by calculation using the following formula.
[0076] |SG1|=SG I -SG Q / tanθ
[0077] |SG2|=SG Q / sinθ
[0078] Furthermore, the inspection device 19 generates images representing the two-dimensional distribution of each value based on the calculated values of all scan positions |SG1| and |SG2|, and outputs these images.
[0079] This variation can also output a two-dimensional distribution image that directly shows the electrical characteristics of each layer L1 and L2. As a result, the electrical characteristics of each layer L1 and L2 at any scan position of the semiconductor device S can be easily analyzed.
[0080] In the above embodiment, the semiconductor device S with a two-layer structure including a first layer L1 and a second layer L2 is used as the target, but the inspection device 19 may also have a resolution function for semiconductor devices S with a three-layer structure or more.
[0081] For example, it can also be like Figure 16 The semiconductor device S shown is an example of a multilayer structure comprising a first layer L1 located at a first position from the side closest to the light source 9, a second layer L2 located at a second position, and a third layer L3 located at a third position. In this semiconductor device S, based on design data, it is known that: a region A1 has a current flow path PA only in the first layer L1; a region A12 has a path PA in both the first and second layers; a region A23 has a path PA in both the second and third layers L3; and a region A3 has a path PA only in the third layer L3. Furthermore, laser light from the light source 9 is focused onto the first layer L1.
[0082] Taking the semiconductor device S with the above-described structure as an example, the inspection apparatus 19 first performs phase correction on the characteristic signals of all scan positions, based on the characteristic signal of region A1. Next, taking the characteristic signals of region A1 and region A23 as examples, it performs the analytical processing described in the above embodiment and separates the characteristic signals of the first layer L1 at all scan positions. Furthermore, the inspection apparatus 19 obtains the gain related to the amplitude of each frequency based on the corrected characteristic signal of region A1. Figure 17 Part (a) shows the variation of the characteristic signal in region A1 obtained at each frequency f0, f1, f2, f3. Figure 17 Part (b) shows the amplitude-dependent gain of the characteristic signal of region A1 corresponding to each frequency f0, f1, f2, f3, which is obtained therewith.
[0083] Next, the inspection device 19 removes the characteristic signals of the first layer L1 at each scan position, which reflect the gain at each frequency f0, f1, f2, f3, targeting the characteristic signals corresponding to each frequency f0, f1, f2, f3. Then, based on the characteristic signals of the removed region A12, the inspection device 19 performs phase correction on the characteristic signals of all scan positions after removal. In addition, targeting the characteristic signals of region A3 and region A12, the analysis processing described in the above embodiment is performed to separate the characteristic signals of the second layer L2 at all scan positions, and simultaneously separate the characteristic signals of the third layer L3 at all scan positions.
[0084] Based on this variation, the electrical characteristics of each layer L1, L2, and L3 at any scanning position can be estimated using a three-layer semiconductor device as an example.
[0085] Additionally, the inspection device 19 may also have the following functions: Figure 18 The four-layer semiconductor device S shown is the object's parsing function. Figure 18 The semiconductor device S shown has a multilayer structure comprising a first layer L1 located at a first position from the side closest to the light source 9, a second layer L2 located at a second position, a third layer L3 located at a third position, and a fourth layer L4 located at a fourth position. In this semiconductor device S, according to design data, it is known that: a region A1 has a current flow path PA only in the first layer L1; and a region A234 has paths PA in the second layer L2, the third layer L3, and the fourth layer L4. Furthermore, laser light from the light source 9 is focused onto the first layer L1.
[0086] When the semiconductor device S with the above-described structure is used as the target, the inspection device 19 first performs phase correction on the characteristic signals of all scan positions based on the characteristic signal of region A1. Next, taking the characteristic signals of region A1 and region A234 as targets, the analysis processing described in the above embodiment is performed to separate the characteristic signals of the first layer L1 of all scan positions. Then, taking the characteristic signals corresponding to each frequency of each scan position as targets, the inspection device 19 removes the characteristic signals of the first layer L1 of each scan position that reflect the gain corresponding to each frequency. Afterwards, taking the characteristic signals of each scan position that have been removed as targets, the inspection device 19 performs the above-described analysis processing on the semiconductor device S with a 3-layer structure to separate the characteristic signals of each of the second layer L2 to the fourth layer L4.
[0087] Based on this variation, the electrical characteristics of each layer L1, L2, L3, L4 at any scan position can be estimated using a 4-layer semiconductor device as an example. Similarly, the electrical characteristics of each layer at any scan position can be estimated using a semiconductor device with a 5-layer or higher structure as an example.
[0088] In addition, in the inspection apparatus 19, when the semiconductor device S to be measured has region A2 but does not have region A1, the frequency at which the characteristic signal of the first layer L1 and the characteristic signal of the second layer L2 have a predetermined phase difference can also be obtained as described below.
[0089] That is, the inspection device 19 obtains the natural logarithm of the amplitude of the characteristic signal in region A2, and analyzes the natural logarithm and the square root of the frequency f. 1 / 2 The relationship. In Figure 19 The diagram shows the characteristic signal and the square root of the frequency f analyzed by the inspection device 19. 1 / 2 A diagram showing the relationship between the two.
[0090] The testing device 19 uses this relationship to determine the square root f of the frequency. 1 / 2 The natural logarithm value (slice value) when = 0. Next, the checking device 19 calculates the frequency f* when the natural logarithm value decreases by a predetermined phase difference (e.g., π / 2) based on the slice value. It can be determined that a better estimate of this frequency f* is the frequency at which the characteristic signal of the first layer L1 and the characteristic signal of the second layer L2 have a predetermined phase difference.
[0091] In addition, the inspection device 19 can also use the frequency f*, which is predetermined based on the material and structure of the semiconductor device S, as the frequency of the characteristic signal with a specified phase difference, when the material and structure of the semiconductor device S are known.
[0092] That is, in a semiconductor device S, there are N layers (N being a natural number) of different materials between the first layer L1 and the second layer L2. As for the respective structures of these N layers, the density ρ is known. k Specific heat c k Thermal conductivity λ k , film thickness d k (k = 0, 1, ... N-1). In this case, the phase difference θ between the characteristic signal of layer 1 L1 and the characteristic signal of layer 2 L2 is expressed by the following formula using each frequency ω (=2πf).
[0093]
[0094] The inspection device 19 can pre-calculate the frequency f* using this relationship, with the phase difference between the characteristic signals of the first layer L1 and the characteristic signals of the second layer L2 being a predetermined phase difference, and use this for analytical processing. Furthermore, the above calculation formula assumes that the semiconductor device S is approximated as a simple one-dimensional stacked structure. However, in cases where the actual semiconductor device S has a complex structure and is difficult to approximate in one dimension, the frequency obtained through numerical calculation based on the finite element method or similar methods, with a predetermined phase difference, can also be used. In this way, since the proportional relationship between the square root of the frequency and the phase remains unchanged, the proportionality coefficient can also be obtained through numerical calculation.
[0095] In the above embodiments, preferably, in the output step, the output includes an image showing the two-dimensional distribution of the in-phase component and an image showing the two-dimensional distribution of the quadrature component. In the above embodiments, preferably, the processor outputs an image showing the two-dimensional distribution of the in-phase component and an image showing the two-dimensional distribution of the quadrature component. This allows for visual capture of the distribution of the in-phase and quadrature components of the characteristic signal, and makes it easy to analyze the electrical characteristics corresponding to the stacked structure of the semiconductor device.
[0096] Furthermore, preferably, in the output step, based on the characteristic signal, the processor outputs: values representing the electrical characteristics of the first position at any scan location and values representing the electrical characteristics of the second position at any scan location. Alternatively, preferably, the processor outputs: values representing the electrical characteristics of the first position at any scan location and values representing the electrical characteristics of the second position at any scan location, based on the characteristic signal. In this case, values directly representing the electrical characteristics of each layer can be output. As a result, the electrical characteristics of each layer at any scan location of the semiconductor device can be easily analyzed.
[0097] Furthermore, preferably, in the correction step, the phase component of the characteristic signal at any scan position is corrected in a manner that cancels out the phase component of the characteristic signal at the first scan position. Furthermore, preferably, the processor corrects the phase component of the characteristic signal at any scan position in a manner that cancels out the phase component of the characteristic signal at the first scan position. In this case, the relative value of the phase component of any scan position with respect to the phase component of the characteristic signal at the first scan position, which reflects the electrical characteristics of the first position, can be obtained. As a result, the electrical characteristics of each layer at any scan position of the semiconductor device can be easily estimated based on the output value.
[0098] Furthermore, preferably, in the determination step, the frequency of the characteristic signal is obtained by predicting the frequency characteristics of the characteristic signal through curve fitting. Furthermore, preferably, the processor obtains the frequency of the characteristic signal by predicting the frequency characteristics of the characteristic signal through curve fitting. According to the above structure, the frequency at which the characteristic signal at the first scan position and the characteristic signal at the second scan position have a predetermined phase difference can be obtained with high precision. As a result, the electrical characteristics corresponding to the stacked structure of the semiconductor device can be analyzed with high precision.
[0099] Furthermore, preferably, in the output step, the frequency characteristic signal is obtained by predicting the frequency characteristics of the characteristic signal at any scan position through curve fitting. Alternatively, the frequency characteristic signal is obtained by predicting the frequency characteristics of the characteristic signal at any scan position through curve fitting. According to the above structure, the frequency characteristic signal obtained at any scan position can be obtained with high precision. As a result, the electrical characteristics corresponding to the stacked structure of the semiconductor device can be analyzed with high precision.
[0100] Furthermore, in the above embodiment, it is preferable that the predetermined phase difference is set to π / 2. With the above structure, the in-phase and quadrature components of the output characteristic signal directly represent the electrical characteristics of each layer. As a result, the electrical characteristics of each layer at any scan position of the semiconductor device can be easily analyzed.
[0101] [Industry availability]
[0102] The implementation method and apparatus for inspecting semiconductor devices are used to analyze the electrical characteristics corresponding to the stacked structure of semiconductor devices.
[0103] Explanation of reference numerals in the attached figures
[0104] 1… Semiconductor inspection device, 3… Voltage application device, 5… Current measurement device, 7… Measuring device, 9… Light source, 11… Signal source, 13… Optical scanning device, 15… Lock-in amplifier (signal acquisition device), 17… Photodetector, 19… Inspection device, 101… CPU (processor), 102… RAM, 103… ROM, 104… Communication module, 106… Input / output module, S… Semiconductor device.
Claims
1. A method for inspecting a semiconductor device, comprising: Measurement steps, among which, While supplying power to the semiconductor device, the electrical characteristics corresponding to the power supply to the semiconductor device are measured. The acquisition step involves scanning the semiconductor device with light modulated at a first frequency intensity and light modulated at a second frequency intensity higher than the first frequency, and acquiring a characteristic signal representing the electrical characteristics of the components of the first frequency and the second frequency corresponding to the scan. The process involves determining the frequency of the characteristic signal at the first scanning position and the characteristic signal at the second scanning position, which have a predetermined phase difference. The characteristic signal at the first scanning position reflects the electrical characteristics of the semiconductor device at the first position in the optical axis direction, and the characteristic signal at the second scanning position reflects the electrical characteristics of the semiconductor device at the second position in the optical axis direction. The correction step includes correcting the phase component of the characteristic signal at any scan position based on the phase component of the characteristic signal at the first scan position of the semiconductor device; and The output step includes obtaining the characteristic signal at any scan position of the obtained frequency, and outputting the in-phase component and quadrature component of the characteristic signal.
2. The semiconductor device inspection method according to claim 1, wherein, In the output step, the output includes: an image showing the two-dimensional distribution of the in-phase component and an image showing the two-dimensional distribution of the orthogonal component.
3. The semiconductor device inspection method according to claim 1, wherein, In the output step, based on the characteristic signal, the following are output: the value of the electrical characteristic at the first position of the arbitrary scan position and the value of the electrical characteristic at the second position of the arbitrary scan position.
4. The semiconductor device inspection method according to claim 2, wherein, In the output step, based on the characteristic signal, the following are output: the value of the electrical characteristic at the first position of the arbitrary scan position and the value of the electrical characteristic at the second position of the arbitrary scan position.
5. The semiconductor device inspection method according to any one of claims 1 to 4, wherein, In the correction step, the phase component of the characteristic signal at any scan position is corrected in a manner that cancels out the phase component of the characteristic signal at the first scan position.
6. The semiconductor device inspection method according to any one of claims 1 to 4, wherein, In the determination step, the frequency of the characteristic signal is determined by predicting the frequency characteristics of the characteristic signal through curve fitting.
7. The semiconductor device inspection method according to any one of claims 1 to 4, wherein, In the output step, the characteristic signal at the specified frequency is obtained by predicting the frequency characteristics of the characteristic signal at the arbitrary scan position through curve fitting.
8. The semiconductor device inspection method according to any one of claims 1 to 4, wherein, The specified phase difference is π / 2.
9. A semiconductor device inspection apparatus, comprising: A measuring instrument that, while supplying power to a semiconductor device, measures the electrical characteristics corresponding to the power supply to the semiconductor device. An optical scanning device that scans the semiconductor device with light modulated at a first frequency intensity and light modulated at a second frequency intensity higher than the first frequency; A signal acquisition device that acquires a characteristic signal representing the electrical characteristics of a component of the first frequency and a component of the second frequency corresponding to a scan of the light; and The processor processes the aforementioned characteristic signals. The processor, The frequency of the characteristic signal at the first scan position and the characteristic signal at the second scan position with a predetermined phase difference is obtained. The characteristic signal at the first scan position reflects the electrical characteristics of the semiconductor device at the first position in the optical axis direction, and the characteristic signal at the second scan position reflects the electrical characteristics of the semiconductor device at the second position in the optical axis direction. Using the phase component of the characteristic signal at the first scan position of the semiconductor device as a reference, the phase component of the characteristic signal at any scan position is corrected; Obtain the characteristic signal at any scanning position of the obtained frequency, and output the in-phase component and quadrature component of the characteristic signal.
10. The semiconductor device inspection apparatus according to claim 9, wherein... The processor outputs: an image showing the two-dimensional distribution of the in-phase components and an image showing the two-dimensional distribution of the orthogonal components.
11. The semiconductor device inspection apparatus according to claim 9, wherein, Based on the characteristic signal, the processor outputs: a value representing the electrical characteristic at the first position of the arbitrary scan position, and a value representing the electrical characteristic at the second position of the arbitrary scan position.
12. The semiconductor device inspection apparatus according to claim 10, wherein, Based on the characteristic signal, the processor outputs: a value representing the electrical characteristic at the first position of the arbitrary scan position, and a value representing the electrical characteristic at the second position of the arbitrary scan position.
13. The semiconductor device inspection apparatus according to any one of claims 9 to 12, wherein, The processor corrects the phase component of the characteristic signal at any scan position by canceling out the phase component of the characteristic signal at the first scan position.
14. The semiconductor device inspection apparatus according to any one of claims 9 to 12, wherein, The processor determines the frequency of the characteristic signal by predicting its frequency characteristics through curve fitting.
15. The semiconductor device inspection apparatus according to any one of claims 9 to 12, wherein, The processor obtains the characteristic signal at the specified frequency by predicting the frequency characteristics of the characteristic signal at the arbitrary scan position through curve fitting.
16. The semiconductor device inspection apparatus according to any one of claims 9 to 12, wherein, The specified phase difference is π / 2.