JP2009099634A - Inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently detect a defect present in a semiconductor device with high sensitivity. <P>SOLUTION: An inspection device 10 including an irradiation unit 13 which irradiates a reverse surface of the semiconductor device having a circuit formed on the top surface with light 13a having a wavelength to be transmitted up to a formation surface of the circuit, a detection unit 15 which detects light 13b emitted from the reverse surface of the semiconductor device as the light 13a is incident, and an acquisition unit which acquires intensity of the detected light 13b irradiates the reverse surface of the semiconductor device having the circuit formed on the top surface with the light 13a having the wavelength to be transmitted up to the formation surface of the circuit, detects the light 13b emitted from the reverse surface of the semiconductor device, and acquires the intensity of the detected light 13b. Consequently, the defect present in the semiconductor device on a wafer scale or chip scale can be efficiently detected with high sensitivity. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inspection apparatus, and more particularly to an inspection apparatus for a semiconductor device.

  In recent years, as a transistor constituting a semiconductor device is miniaturized, the manufacturing process of the semiconductor device becomes more and more complicated, and accordingly, the number of processes increases with each generation. In order to improve the operating characteristics and reliability of semiconductor devices, demands for reducing the size and density of defects have become increasingly severe.

  Here, the defect means various lattice defects such as a point defect and a dislocation contained in the semiconductor substrate, the insulating film, or the wiring. And about such a defect, various analysis means are devised according to a failure mode and an object place.

For example, a typical example is one that detects an abnormal response caused by a defect using an electron, light, or the like as a probe.
As a typical example of analysis means using electrons as a probe, the most common one is observation with an electron microscope. According to this method, the abnormal part can be observed directly.

  On the other hand, the analysis means using light as a probe can easily detect defects existing in the semiconductor device. For example, OBIC (Optical Beam Induced Current) method and OBIRCH (Optical Beam Induced Resistivity CHange) method are typical examples.

  In the OBIC method, a semiconductor device to which a reverse bias is applied is irradiated with light, and the flow of electrons and holes generated by the light irradiation is observed. And the voltage distribution of a pn junction part is analyzed from the measured electric current value. Here, it is known that if the insulating film in the semiconductor device is defective or a defect exists in the bonding layer, the voltage distribution becomes abnormal. By measuring this voltage distribution, the presence or absence of defects in the semiconductor device can be determined (for example, see Non-Patent Document 1).

  Similar to the OBIC method, the OBIRCH method irradiates light to a semiconductor device to which a reverse bias is applied, and observes a change in resistance from the flow of electrons and holes generated by the light irradiation. Here too, the presence or absence of defects in the semiconductor device can be determined (for example, see Non-Patent Document 2).

As described above, the OBIC method and the OBIRCH method are excellent for detecting minute defects in a semiconductor device, and are used as effective means for failure / failure analysis.
Haraguchi Koshi., "Microscope Optical Beam Induced Current Measurements and their Application", HYPERLINK "http://ieeexplore.ieee.org/xpl/RecentCon.jsp?punumber=1120" Instrumentation and Measurement Technology Conference, 1994. Conference Proceedings 10th Anniversary Advanced Technologies in I & M., 1994, IEEE, P693-699 Phang JCH, et al., "A review of laser induced techniques for microelectronic failure analysis", Physical and Failure Analysis of Integrated Circuits, 2004, IPFA 2004. Proceedings of 11th International Symposium on the Volume, Issue, 5-8, July, 2004, p255−261

  However, in the above OBIC method and OBIRCH method, since it is necessary to apply a reverse bias to the analysis sample (subject), it is necessary to dispose the wiring for applying the reverse bias after the analysis sample is separated into pieces. . For this reason, there exists a problem that a sample process takes time and effort. In addition, the current OBIC method and OBIRCH method are effective for analyzing a local region, but have a limit in the analysis region. Therefore, when the analysis sample has a large area, there is a problem that the analysis sample cannot be evaluated efficiently and with high sensitivity over the entire region.

  In particular, in recent years, the diameter of the wafer itself has increased. Accordingly, the number of semiconductor devices formed on the wafer by the wafer process is increasing. Therefore, there is a demand for a method capable of efficiently and highly sensitively analyzing variations in characteristics of semiconductor devices in a wafer state and differences in yield.

  Also in chip-like semiconductor devices, with the recent miniaturization of semiconductor elements, the number of transistors and the like arranged per chip has become enormous. Therefore, there is a demand for a method that can easily analyze variations and defects in characteristics of transistors and the like in a chip state.

As described above, there is a demand for a technique for efficiently and highly sensitively analyzing defects existing in a semiconductor device on a wafer scale or a chip scale.
The present invention has been made in view of such a point, and an object of the present invention is to provide an inspection apparatus that efficiently detects a defect existing in a wafer scale or chip scale semiconductor device with high sensitivity. .

  In the present invention, in order to solve the above-described problem, as illustrated in FIG. 1, an irradiation unit 13 that irradiates light 13 a having a wavelength that is transmitted from the back surface of a semiconductor device having a circuit formed on the front surface to the formation surface of the circuit; There is provided an inspection apparatus 10 including a detection unit 15 that detects light 13b emitted from the back surface of the semiconductor device by the incidence of light 13a, and an acquisition unit that acquires the intensity of the detected light 13b. The

  According to such an inspection apparatus, light having a wavelength that is transmitted from the back surface of the semiconductor device having a circuit formed on the front surface to the formation surface of the circuit is irradiated, and light emitted from the back surface of the semiconductor device is caused by the incident light. As a result, the intensity of the detected light is acquired.

  In the present invention, light of a wavelength that is transmitted from the back surface of the semiconductor device having a circuit formed on the front surface to the formation surface of the circuit is irradiated, and light emitted from the back surface of the semiconductor device is detected by light incidence. The detected light intensity was acquired. Thereby, defects existing in a wafer scale or chip scale semiconductor device can be detected efficiently and with high sensitivity.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments.
In this embodiment mode, an inspection apparatus using light for detecting defects contained in a semiconductor device will be described. Specifically, in the first embodiment, photoluminescence that is spectrally detected by irradiating light from the back surface of the semiconductor device is used, and in the second embodiment, similarly, scattered light that is spectrally detected is used. In the third embodiment, a method for detecting defects by irradiating light in the same manner and directly observing scattered light will be described.

First, the first embodiment will be described.
FIG. 1 is a schematic diagram of a main part of an inspection apparatus system.
The inspection apparatus 10 includes a support 12 for supporting the semiconductor substrate 11, an irradiation unit 13 for irradiating the semiconductor substrate 11 with light 13 a by a laser, a spectroscopic unit 14 for splitting light 13 b emitted from the semiconductor substrate 11, and detecting the split light. And a device control unit 16.

  The semiconductor substrate 11 is, for example, a semiconductor device in a wafer state before being singulated as a semiconductor chip. The semiconductor substrate 11 is a semiconductor substrate (wafer substrate) made of silicon (Si) or gallium arsenide (GaAs), a transistor, a capacitor In addition, semiconductor elements composed of multilayer wiring and the like are formed vertically and horizontally. For example, a semiconductor substrate 11 having a diameter of 300 mm is installed on the support base 12.

  As described above, the support base 12 supports the semiconductor substrate 11 that is the subject. The support 12 can move in a three-dimensional range in the direction facing the light 13a (Z direction in the drawing) and the vertical direction (X, Y direction) with respect to the Z direction. Further, the support base 12 is configured to be able to vary the incident angle of the light 13a with respect to the semiconductor substrate 11 by rotating about any of the X, Y, and Z axes as required. In addition to the semiconductor substrate 11 in the wafer state, the support table 12 can also support individual semiconductor chips.

  The light 13a emitted from the irradiation unit 13 is reflected by the reflecting plates 17a and 17b, and then irradiated to the back surface of the semiconductor substrate 11. Note that a number of metal wirings are disposed on one main surface (front surface side) of the semiconductor substrate 11, and the light does not pass through the semiconductor substrate 11 when irradiated from the front surface side of the semiconductor device. Defect detection sensitivity decreases. Therefore, the present embodiment is characterized in that light irradiation is performed from the back surface of the semiconductor substrate 11.

When the semiconductor substrate 11 is irradiated with light 13a, the semiconductor substrate 11 emits specific photoluminescence (light emission), scattering of the irradiated light, and reflection of the irradiated light.
Here, photoluminescence, scattered light, and reflected light generated from the semiconductor substrate 11 will be described.

FIG. 2 is a schematic cross-sectional view of an essential part for explaining the principle of photoluminescence.
The semiconductor device 21a includes a substrate 21 and an element layer 22 in which a semiconductor element such as a transistor, a capacitor, and a multilayer wiring is formed on the substrate 21. Further, in the element layer 22, there are defects 23 such as point defects and dislocations introduced during crystal growth or element processing. The case where the light 24a and 26a are irradiated to the back surface 20a of the board | substrate 21 of such a semiconductor device 21a is demonstrated.

First, the irradiated light 24 a enters the substrate 21. As shown in Non-Patent Document 2, when a long-wavelength laser is used, the light 24a can reach the active layer (not shown) in the element layer 22 because the transmittance in Si is high. Further, as shown in Non-Patent Document 2, the transmittance varies depending on the impurity concentration doped into Si and the thickness of Si (details will be described later with reference to FIG. 4). By selecting the wavelength of light to be irradiated with reference to this known transmittance change, it is possible to control the entry of light into Si. One example is described below. When the penetration length of light into Si doped with an impurity of about 1.0 × 10 ¹⁵ atoms / cm ^{3 is} determined from the transmittance, it is about 1 μm (the wavelength of the irradiated light is about 500 nm), about 100 μm (of the irradiated light) The wavelength is about 967 nm), about 200 μm (the wavelength of irradiated light is about 1018 nm), and about 500 μm (the wavelength of irradiated light is about 1057 nm). Therefore, even if the thickness of the semiconductor device 21a varies, it is possible to cause the light 24a irradiated on the back surface 20a to reach the element layer 22 by selecting the wavelength of light to be irradiated. There are various types of semiconductor lasers as the light source of the light 24a to be irradiated. Typical wavelengths are listed as follows: about 473 nm, about 532 nm, about 527 nm, about 648 nm, about 1047 nm, about 1053 nm, and about 1064 nm. Among these, the laser that seems to be suitable for causing the light 24a irradiated to the back surface 20a to reach the element layer 22 is a laser having a long penetration length of about 1064 nm. A YAG (Yttrium Aluminum Garnet) laser is known as a laser having a wavelength of about 1064 nm. The YAG laser light 24a is larger than the Si energy band gap (corresponding to a wavelength of about 1150 nm). When such light 24a is irradiated, electrons in the valence band are excited to the conduction band. At this time, holes corresponding to electrons are generated in the valence band. Thereafter, the electrons / holes 25 generated in this manner are recombined, and light is emitted in the recombination process, thereby generating light 24b by photoluminescence having a wavelength unique to the Si crystal.

  On the other hand, when the YAG laser beam 26a is irradiated in the same manner, the electron / hole 25 is generated as described above and recombination occurs. However, if the defect 23 exists and the defect 23 forms a unique electronic level in the band gap, either an electron or a hole is used in the electron-hole 25 recombination process. Or trap both. Since the density of the electrons / holes 25 is reduced by the trapping of the electrons / holes 25 by the defects 23, the intensity of the light 24b by photoluminescence having a wavelength unique to the Si crystal is reduced. Further, when the defect 23 traps the electrons / holes 25 and the electrons / holes 25 disappear, the light 26b having energy (wavelength) different from the light emission unique to the Si crystal may be emitted.

In this way, it is possible to evaluate the quality in the semiconductor device 21a by detecting the light 24b and 26b by photoluminescence and detecting the presence of the defect 23.
In addition, although it demonstrated that photoluminescence generate | occur | produces from the semiconductor device 21a, referring to FIG. 2, the light reflected or scattered in the semiconductor device 21a is also actually generated by the light from the irradiation unit 13.

  Therefore, referring to FIG. 1 again, the light 13b generated in the active layer by the irradiation of the YAG laser and transmitted through the semiconductor device, and the other reflected or scattered light 13b is reflected on the semiconductor substrate 11. Generated from the back side. Then, after the light 13b passes through the spectroscopic unit 14 via the reflector 17c, it is detected by the detection unit 15.

  The data of the photoluminescence / scattered light / reflected light of the semiconductor device obtained by such a method is processed in the device control unit 16, and the two-dimensional distribution of the light intensity at a specific wavelength of the photoluminescence / scattered light / reflected light is processed. Are output as an image display.

In addition, the apparatus control unit 16 not only performs the data processing as described above, but also controls the entire inspection apparatus 10.
For example, in the apparatus control unit 16, an irradiation unit control unit 16a that controls the irradiation unit 13, a detection unit control unit 16b that controls the detection unit 15, and light emission data detected by the detection unit 15 are processed to detect defects. Data processing means 16c for storing data, storage means 16d for storing data, and input / output means 16e serving as a user interface.

Next, the basic principle of a semiconductor device inspection method using the above-described inspection apparatus 10 will be described.
FIG. 3 is a flowchart of the inspection method.

The inspection apparatus 10 performs inspection of defects in the semiconductor device according to the flowchart of FIG. Hereinafter, description will be made with reference to FIG. 3 together with FIG.
[Step S21] Measurement conditions are input to the device control unit 16 of the inspection device 10.

[Step S <b> 22] The semiconductor substrate 11 in a wafer state, for example, is mounted on the support base 12 so that the back surface side is exposed from the support base 12.
[Step S23] The irradiation unit control means 16a controls the irradiation unit 13 to irradiate the irradiation unit 13 with the light 13a from the YAG laser, and irradiates the light 13a to an arbitrary position of the semiconductor substrate 11 from the back side.

  [Step S24] The detection unit 15 is controlled by the detection unit control unit 16b, and the detection unit 15 detects the photoluminescence emitted from the semiconductor device and dispersed by the spectroscopic unit 14. In addition to photoluminescence, scattered light from the semiconductor substrate 11 or reflected light from the active layer of the semiconductor device may be detected. That is, in this stage, photoluminescence, scattered light and reflected light are spectrally detected.

[Step S25] The photoluminescence data detected in step S24 is processed by the data processing means 16c and the storage means 16d.
[Step S26] The input / output unit 16e displays, for example, an emission spectrum or an image display as a detection result. In particular, in the image display, the light intensity of the specific wavelength that is spectrally detected is displayed as a two-dimensional distribution.

  According to such a flow, the back surface of the semiconductor device is irradiated with light, the light emitted from the back surface of the semiconductor device is spectrally detected by the light irradiation, and the light intensity of a specific wavelength obtained by the spectral detection is measured. The Further, after the measurement, the measured light intensity is displayed as an image as a two-dimensional distribution.

The result of actually detecting defects contained in the semiconductor device formed in the semiconductor substrate 11 using such an inspection apparatus 10 will be described.
4A and 4B show the wavelength dependence of the transmittance of the silicon wafer substrate, where FIG. 4A shows the doping amount, FIG. 4B shows a graph for each film thickness of the silicon wafer substrate, and FIG. 5 shows the first embodiment. It is an image of a two-dimensional distribution detected by a detection method.

  By the way, in FIG. 4 described in Non-Patent Document 2, the horizontal axis represents wavelength (nm), and the vertical axis represents transmittance (arbitrary unit). According to this, as shown in FIG. 4A, the transmittance of light having a wavelength of 800 nm or less is substantially 0 (%). However, at 800 nm or more, the transmittance changes according to the doping amount. For example, for the silicon wafer substrate with the lowest doping amount (highest resistance), the transmittance increases in the vicinity of about 1150 nm, which corresponds to the band gap of Si, and thereafter shows a substantially constant value. Further, the higher the doping amount (low resistance) silicon wafer substrate, the transmittance once increased to about 1150 nm and showed the maximum value, but thereafter, the transmittance tends to decrease.

Further, as shown in FIG. 4B, when the film thickness of the silicon wafer substrate is changed, the transmittance increases as the film thickness decreases.
From these data, it can be seen that light in the vicinity of the wavelength of the band edge emission (about 1150 nm) is transparent to the silicon wafer substrate.

  Then, as described above, the back surface of the semiconductor device is irradiated with a YAG laser, and the light emitted from the back surface of the semiconductor substrate 11 is dispersed to detect an emission spectrum of a specific wavelength. At this time, a wavelength of about 1150 nm that is transparent to the semiconductor device and has a high S / N ratio is detected from the result of FIG. Then, the apparatus control unit 16 maps the intensity of light of each wavelength as a two-dimensional distribution 40, and the result of image display is shown in FIG.

  A black contrast portion indicated by an arrow 41 appears in a part of the image of the two-dimensional distribution 40. In the image display of the two-dimensional distribution 40, the black portion is where the intensity of the detected light is low. That is, this is a defect located in the active layer. On the other hand, when the characteristics of this semiconductor device were evaluated, it was found that the location indicated by the arrow 41 was defective in characteristics. Therefore, the defect in the active layer can be detected by the inspection apparatus 10.

  As described above, the inspection apparatus 10 according to the first embodiment includes the support 12 that supports the semiconductor substrate 11, the irradiation unit 13 that irradiates the semiconductor substrate 11 with the light 13a by the YAG laser, and the light 13b that is emitted from the semiconductor substrate 11. Are provided with a spectroscopic unit 14 that splits the light, a detection unit 15 that detects the split light, and an apparatus control unit 16. The inspection apparatus 10 uses photoluminescence by a YAG laser to detect defects in the vicinity of the active region of the semiconductor device formed on the semiconductor substrate 11 by a wafer process, so that it can be detected easily, efficiently, and with high sensitivity. can do. Further, by forming an image as a two-dimensional distribution from light intensity data detected by the YAG laser, defects in the active layer can be visually grasped, and the semiconductor device can be easily analyzed.

Next, a second embodiment will be described.
In the first embodiment, a defect in a semiconductor device is detected from photoluminescence. On the other hand, in the second embodiment, a defect of the semiconductor device is detected from the scattered light.

First, an emission spectrum when a YAG laser is irradiated on defective silicon will be described.
FIG. 6 is an emission spectrum of the silicon wafer substrate irradiated with the YAG laser. The horizontal axis represents the emission wavelength (nm), and the vertical axis represents the emission intensity (arbitrary unit).

  As described above, when the back surface of the silicon wafer substrate is irradiated with YAG laser light, the light irradiated from the back surface reaches the active layer of the semiconductor device. At this time, in the first embodiment, electrons and holes are generated, and defects are detected from photoluminescence in the recombination process. On the other hand, in the second embodiment, when light is irradiated on the back surface, a phenomenon called Rayleigh scattering in which light is scattered by fine particles occurs. That is, the irradiated light is scattered by fine particles that are defects. Therefore, the light in the active layer can be detected by spectrally detecting the light scattered by the defect and displaying the intensity of the light. FIG. 6 shows the spectrum of the scattered light and reflected light at this time, and a large peak can be confirmed at a wavelength equal to the wavelength of the YAG laser (about 1064 nm).

Then, the result of using this detection method will be described below.
7A is a schematic cross-sectional view showing the mechanism of the intensity distribution of scattered light and reflected light when a semiconductor device is irradiated with a YAG laser, and FIG. 7B is an intensity distribution of light based on (A). FIG. 8 shows a two-dimensional distribution image detected by the detection method according to the second embodiment, (A) before processing and (B) after processing.

  As shown in FIG. 7A, the semiconductor device 50 includes a substrate 51 and an element layer 52 in which a semiconductor element such as a transistor, a capacitor, or a multilayer wiring is formed over the substrate 51. In general, a semiconductor element has a periodic structure. Further, defects 53 such as point defects and dislocations introduced during crystal growth and element processing exist in the vicinity of the element layer 52. The back surface 50a of the substrate 51 is irradiated with YAG laser beams 54a and 54c. Then, light 54b and 54d in which the light 54a and 54c are scattered by the periodic structure of the element layer 52 and the defect 53 are emitted from the back surface 50a.

  Further, FIG. 7B shows the intensity distribution of the light 54b and 54d emitted from the back surface 50a. In FIG. 7B, the intensity distribution is simulated, the horizontal axis represents the position of the semiconductor device, and the vertical axis represents the light intensity (arbitrary unit). When the back surface 50a of the substrate 51 is irradiated with the YAG laser light 54a to reach the element layer 52, the structure in the element layer 52 becomes a light scattering source, and thus the light caused by the element layer in FIG. As shown in the component 52a, the intensity of light corresponding to the structure of the element is observed. When the rear surface 50a of the substrate 51 is irradiated with the YAG laser light 54c and reaches the defect 53, as shown in FIG. 7B, the light component 52a caused by the element layer is replaced by the light component caused by the defect. 53a is added. Therefore, focus only on non-periodic components, or when it is difficult to distinguish between periodic and non-periodic components, only the non-periodic components can be made obvious by removing the low-intensity components of the periodic components little by little. With this method, the light caused only by the defect 53 becomes obvious and the defect 53 can be recognized.

  FIG. 8 shows the result of selectively displaying a wavelength of about 1064 nm from the emission spectrum from the back surface 50a, mapping the intensity of light of each wavelength as a two-dimensional distribution, and displaying the image.

In FIG. 8A, a white contrast portion can be confirmed in a part of the image. In this image display, the white portion has a high intensity in the detected light.
However, as shown in FIG. 7B, in FIG. 8A, in addition to the component of the defect 53, the periodic component of the element layer 52 is also detected. Therefore, as described above, only the intensity due to the defect 53 can be detected by removing the low intensity component of the periodic structure of the element layer 52 little by little.

As a result of such processing, light caused only by the defect 53 was made obvious and detected in the white portion at the center of the two-dimensional distribution as shown in FIG. 8B.
As described above, in the second embodiment, the scattered light of the defect by the YAG laser is used to detect the defect near the active region of the semiconductor device formed on the semiconductor substrate by the wafer process, and it is easy and efficient. , Can be detected with high sensitivity. Further, by forming an image as a two-dimensional distribution from light intensity data detected by the YAG laser, defects in the active layer can be visually grasped, and the semiconductor device can be easily analyzed.

Next, a third embodiment will be described.
As described in the first and second embodiments so far, when a semiconductor substrate is irradiated with light from a YAG laser, photoluminescence, scattered light, and reflected light are emitted. Of these three types of light, the highest intensity is scattered light and reflected light as shown in FIG.

  Therefore, in the third embodiment, spectral detection is not performed, only the light intensity is detected, and the light intensity is imaged as a two-dimensional distribution. The two-dimensional distribution is considered to be almost due to the intensity of scattered light and reflected light.

FIG. 9 is a schematic diagram of a main part of an inspection apparatus system according to the third embodiment.
The inspection apparatus 60 includes a support base 62 that supports the semiconductor substrate 61, an irradiation unit 63 that emits light 63a to the semiconductor substrate 61 by a YAG laser, and light from the semiconductor substrate 61 that is irradiated with the light 63a reflected by the reflector 67. The detection part 65 which detects 63b, and the apparatus control part 66 are provided. That is, the inspection apparatus 60 does not include a spectroscopic unit, and the inspection apparatus 10 has the same configuration except for the spectroscopic unit 14. For this reason, description of each component is abbreviate | omitted.

  Accordingly, the flow of the semiconductor device inspection method using the inspection apparatus 60 is the same as that of the flowchart of FIG. However, in the third embodiment, in [Step S24] in the flowchart of FIG. 20, only scattered light is detected without performing spectroscopy.

Next, a result of actually detecting defects included in the semiconductor device formed in the semiconductor substrate 61 using the inspection apparatus 60 will be described.
FIG. 10A is a schematic cross-sectional view of the relevant part showing the detection principle, and FIG. 10B is a detected observation image in the third embodiment. In the following, description will be given with reference to FIG. 10 together with FIG.

  9 and 10A, the semiconductor substrate 61 is fixed to the support base 62 so that the back surface 72a of the semiconductor device 72 is exposed, and the irradiation unit 63 irradiates the back surface 72a with light 63a by a YAG laser. To do. The light 63b emitted from the back surface 72a of the semiconductor device 72 is detected by a detection unit 65 such as a CCD (Charge Coupled Device) camera.

  Then, as shown in FIG. 10A, the light 63a is applied to the back surface 72a of the semiconductor device 72 obliquely from above. The irradiated light 63a is first reflected at point A on the back surface 72a, and light 73b is emitted from the back surface 72a. On the other hand, the light 73c is refracted from the point A into the semiconductor device 72, is scattered at the point B of the semiconductor device 72, and the light 73d is emitted from the back surface 72a.

  FIG. 10B shows an image obtained by observing these lights 73b and 73d with the detection unit 65 from the upper side of the back surface 72a. According to this, the point on the straight line when the point A and the point B are connected by a straight line corresponds to the depth position from the back surface 72 a to the front surface of the semiconductor device 72. Therefore, it is possible to obtain a two-dimensional distribution of scattered light at an arbitrary depth position of the semiconductor device 72 by determining not only the point B but also a point on a straight line and imaging it as a two-dimensional distribution.

FIG. 11 is an image of a two-dimensional distribution detected by the detection method according to the third embodiment, (A) before processing and (B) after processing.
FIG. 11 shows the result of imaging the intensity of light only at point B in FIG. 10 as a two-dimensional distribution. Point B is scattering from the back surface 72a of the semiconductor device 72, and its light intensity is imaged as a two-dimensional distribution, so FIG. 11 shows the scattered light intensity on the semiconductor circuit surface.

  As shown in FIG. 11A, a point where the intensity of light is locally strong was observed. However, as described with reference to FIG. 7 of the second embodiment, an element layer (not shown) in which a semiconductor element such as a transistor, a capacitor, and a multilayer wiring is formed has a periodic structure. In A), not only defects but also their periodic structures are observed together.

  Therefore, FIG. 11B shows the result of performing the processing described in FIG. As a result, it is possible to reveal scattering caused only by defects. It can be seen that even if the scattering caused by the periodic structure of the element layer is removed, it still exists as a bright spot, and a scattering point, that is, a defect exists.

  As described above, in the third embodiment, the defect is detected by directly observing the scattered light of the defect by the YAG laser for detecting the defect near the active region of the semiconductor device formed on the semiconductor substrate by the wafer process. Therefore, it can be detected easily, efficiently and with high sensitivity. Further, by forming an image as a two-dimensional distribution from light intensity data detected by the YAG laser, defects in the active layer can be visually grasped, and the semiconductor device can be easily analyzed.

It is a principal part schematic diagram of a test | inspection apparatus system. It is a principal part cross-sectional schematic diagram explaining the principle of photoluminescence. It is a flowchart figure of an inspection method. It is a wavelength dependence of the transmittance | permeability of a silicon wafer board | substrate, Comprising: (A) is a doping amount, (B) is a graph for every film thickness of a silicon wafer board | substrate. It is the image of the two-dimensional distribution detected with the detection method in 1st Embodiment. It is an emission spectrum of a silicon wafer substrate irradiated with a YAG laser. (A) is a schematic cross-sectional view showing the mechanism of the intensity distribution of scattered light and reflected light when the semiconductor device is irradiated with a YAG laser, and (B) is the light intensity distribution based on (A). (A) is an image before processing, and (B) is an image of a two-dimensional distribution after processing, which is detected by the detection method according to the second embodiment. It is a principal part schematic diagram of the test | inspection apparatus system in 3rd Embodiment. In 3rd Embodiment, (A) is a principal part cross-sectional schematic diagram which shows a detection principle, (B) is the detected observation image. Detected by the detection method according to the third embodiment, (A) is an image before processing, and (B) is an image of a two-dimensional distribution after processing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inspection apparatus 11 Semiconductor substrate 12 Support stand 13 Irradiation part 13a, 13b Light 14 Spectroscopy part 15 Detection part 16 Apparatus control part 16a Irradiation part control means 16b Detection part control means 16c Data processing means 16d Storage means 16e Input / output means 17a, 17b , 17c Reflector

Claims (5)

An irradiation unit that irradiates light having a wavelength that is transmitted from the back surface of the semiconductor device on which the circuit is formed to the formation surface of the circuit;
A detector for detecting light emitted from the back surface of the semiconductor device by the incidence of the light;
An acquisition unit for acquiring the detected light intensity;
An inspection apparatus comprising:   The inspection apparatus according to claim 1, wherein the irradiation unit irradiates the light with a YAG laser.   The inspection apparatus according to claim 1, wherein the light emitted from the back surface is scattered light from an active region of the semiconductor device.   The inspection apparatus according to claim 1, wherein the acquisition unit acquires an intensity of a specific wavelength of the detected light.   The inspection apparatus according to claim 1, further comprising a display unit that displays an intensity distribution of light acquired by the acquisition unit.

Images