KR0169158B1 - Apparatus for analyzing optical beam induced current of sample - Google Patents

Abstract

omission

Description

Scanning photoorganic current analysis device capable of detecting the photoorganic current of a sample in a non-biased state

1 is a schematic block diagram of a scanning type photoorganic current analyzing apparatus according to a first embodiment of the present invention.

2 is a schematic diagram of the main parts of the first embodiment of the present invention, including the measurement object.

3 is a schematic diagram showing the operation of the first embodiment of the present invention.

(a) is sectional drawing of a to-be-tested object with respect to the scanning area of a laser.

(b) is a waveform diagram which shows the change of the electric current value when scanning laser light.

(c) is a figure which shows the image image output based on the waveform diagram of (b).

4 is a schematic block diagram of a scanning photoorganic current analyzing apparatus according to a second embodiment of the present invention.

5 is a schematic diagram of the main parts of a third embodiment of the present invention including a measurement object.

6 is a schematic diagram of the main parts of a fourth embodiment of the present invention including a measurement object

7 is a schematic block diagram of a scanning type photoorganic current analyzing apparatus according to a fifth embodiment of the present invention.

8 is a schematic view of the main parts of a fifth embodiment of the present invention including a measurement object

9 is a schematic diagram of the main parts of a sixth embodiment of the present invention including a measurement object

10 is a schematic diagram of the main parts of a seventh embodiment of the present invention including an object to be measured.

11 is a schematic block diagram of a scanning type photoorganic current analyzing apparatus according to an eighth embodiment of the present invention.

12 is a schematic block diagram of a scanning optical organic current analysis device according to a ninth embodiment of the present invention.

13 is a schematic diagram showing the operation of the ninth embodiment of the present invention.

(a) is sectional drawing of a to-be-tested object with respect to the scanning area of a laser.

(b) is a temperature distribution diagram in A1 wiring at the time of scanning laser light at low speed.

(c) is a temperature distribution diagram in A1 wiring at the time of scanning the highway laser light.

14 is a schematic block diagram of a scanning optical organic current analysis device according to a tenth embodiment of the present invention.

15 is a schematic block diagram of a laser scanning microscope according to an eleventh embodiment of the present invention.

16 is a schematic block diagram of a scanning optical organic current analysis device according to a twelfth embodiment of the present invention.

FIG. 17 is an image diagram showing an example of an image designating a scanning region of laser light in the twelfth embodiment of the present invention. FIG.

18 is a schematic block diagram of a scanning type photoorganic current analyzing apparatus according to a thirteenth embodiment of the present invention.

Fig. 19 shows an image of image output in a thirteenth embodiment of the present invention.

(a) is an image diagram showing an example of an image designating a current detection region in a thirteenth embodiment of the present invention.

(b) is an image diagram of an output current from a designated area.

20 is a schematic block diagram of a conventional scanning photoorganic current analysis device.

21 is a schematic view of the main parts of a conventional example including a measurement object.

Fig. 22 is a schematic block diagram showing the structure of a conventional laser scanning microscope.

23 is a schematic diagram showing the operation principle of a conventional photoorganic current analysis device.

[Field of Invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoorganic current analysis device, and more particularly, to a scan type photoorganic current analysis device for detecting a photoorganic current in a state in which a normal current does not flow to a measurement object.

Description of Background Art

In the semiconductor integrated circuit, the wiring which connects elements, such as a transistor and a resistor, currently uses the wiring which mainly uses aluminum (Al) for the low resistivity and the easy arm of a process. Along with the miniaturization of semiconductor integrated circuits and the multilayering of structures, the degradation of the reliability of this Al wiring is a serious problem. This is due to the increase in current stress and mechanical stress associated with Al wiring. In other words, the Al wiring has a few hundred microwatts of current flowing therein, and its current density reaches 10 ⁵ A / cm 2 despite the submicron order. Moreover, the mechanical stress of a 100 MPa order is added to wiring for heat processing etc. in a LSI manufacturing process. When such stress is added to the wiring, Al mobility is generated due to so-called electromigration, stress migration, and the like, and voids are generated in the wiring. With the growth of the voids, the resistance of the wiring increases, leading to disconnection.

Therefore, detection and observation of the density and position of the voids in the wiring are essential techniques for improving the reliability of the Al wiring. As a method of detecting the voids of the Al wiring Ganode, a surface potential contrast method using a scanning electron microscope (SEM) and a focused ion beam (FIB) device is known. However, there are limitations such as the analysis in vacuum, the analysis of only the wiring exposed on the surface, and the detection of only the disconnected place.

As a method of removing these limitations, for example, there is an OBIRCH method (Optical Beam Induced Resistance Change method) disclosed in Proceedings of The 19th International Symposium for Testing Failure Analysis, pp 303 to 310 (1993).

20 shows a schematic block diagram of an apparatus configuration for implementing the OBIRCH method.

First, the operation will be described.

In the sample 6 to be measured, a current flows by the DC power supply 8, and the current value is monitored by the current up 10.

In the region designated by the signal r from the device control unit 20, the laser scanning microscope focuses the laser light on the sample 6 to be measured and simultaneously scans it.

For example, when a HeNe laser (wavelength 633 nm) is used as the laser light source, the laser light is narrowed down to a beam diameter of about 0.5 mu m on the sample 6 to be measured.

The image information converting device 12 receives the laser light dice signal 1 from the device control unit 20 and the signal i corresponding to the current value flowing through the sample from the current up 10.

The image information converting apparatus 12 outputs image information corresponding to the signal i for each dice, for example, a signal b converted to bend the magnitude of the signal i. The image output device 14 outputs an image corresponding to the signal b.

21 is a schematic view showing an example of the configuration of the sample 6 to be measured. As described above, in the OBIRCH method, it is necessary to apply a current to the sample 6 to be measured, and therefore the wiring to be measured needs to be a dedicated pattern for measurement by the wiring pattern 16 and the power supply pad 18.

22 is a schematic block diagram showing an example of the configuration of the laser scanning microscope 2. The laser beam 4 from the laser light source 100 enters the light deflecting element 102. The optical deflecting element 102 deflects the laser beam 4 at an angle corresponding to the control signal r of the device control unit 20. The laser beam 4 is also focused on the sample 6 to be measured through the focusing device 106.

Since the position where the laser beam is focused on the sample 6 to be measured varies depending on the deflection angle, the focused laser beam is scanned in accordance with the signal r. In FIG. 22, the focusing device 106 is composed of a reflecting mirror 58 and an objective lens 56. As shown in FIG.

Moreover, by providing the imaging means 104 on the optical path of the laser beam 4, it is possible to image the reflected light from the sample under test 6 and extract it as an imaging information signal v. In this example, the reflected light is extracted by the beam splitter 50 and formed on the photodetector 54 by the imaging lens 52. As the photodetector 54, for example, a one-dimensional CCD (Charge Coupled Device) or the like can be used, and the electric signal v corresponding to the reflected light intensity is output.

The imaging information signal v is also input to the image information converting apparatus 12. The image information conversion device 12 switches whether to output the image information signal b or the image formation information signal v as an output signal in accordance with the control signal 1 from the device control unit 20.

Next, with reference to FIG. 23, the one-ring which detects the position of the void which generate | occur | produces in the wiring 16, for example, Al wiring according to this apparatus structure is demonstrated.

Considering the case where the laser beam is irradiated to the voidless area P of the Al wiring, the thermal conductivity deteriorates when the laser beam is irradiated to the voided area Q. Therefore, compared with the temperature rise (DELTA) T _P of the area | region when the laser beam is irradiated to the area | region _P , the temperature rise (DELTA) T _Q of the area | region when it irradiates to the area | region Q is larger. Therefore, when laser light is irradiated to the area | region Q, resistance change also becomes large. Therefore, when the current I flowing in the middle of the wiring is monitored, the change? I of the current value when the laser light is irradiated to the voided and the non-voided regions differs, so that? I is converted into luminance information with respect to the dice. When the information is output to the image output means 14, for example, the CRT, it is possible to obtain an image output in which the void position can be specifically determined.

In this case, the position of the void in the Al wiring 16 is specifically determined by comparing with the image output by the imaging information from the laser scanning microscope 2.

However, in this method, since the resistance change (resistance increase) caused by the heat generation of the void portion at the time of laser irradiation is taken as the change (current reduction) of the current flowing in the center of the sample under test 6, the shape is changed. It was necessary to analyze with the voltage applied and the mA level current flowing. Therefore, analysis of a high resistance sample (about 10 kPa or more) was impossible, and the resistance value of the sample was limited. In addition, since it is difficult to apply a voltage to an arbitrary wiring portion in a device such as an LSI and flow a current, it is almost impossible to apply this method to the analysis of an actual device.

[Overview of invention]

An object of the present invention is to provide a scanning type photoorganic current analyzing apparatus which can obtain, as image information, a photoorganic current generated in a measured object without applying a current bias to the measured object.

Another object of the present invention is to provide a scanning type photoorganic current analysis device which is not limited to the resistance value of the object to be measured and can detect the positions of the holes and defects in the object to be measured.

Further, another object of the present invention is to provide a scanning type photoorganic current analyzing apparatus which is not limited to the limitation of the shape of the measurable object to be measured, or the limitation that the closed circuit must be able to be configured.

Summary of the Invention The present invention is a scanning type photoorganic current analyzing apparatus which detects photoorganic current induced in an object under measurement by scanning while irradiating focused laser light, comprising: a laser light source, a beam scanning element, a light concentrating element, a control unit; It is equipped with current amplifier, image converter and image output device.

The laser light source generates laser light for measurement. The luminous flux scanning element scans the laser light in the region according to the first control signal. The light converging element focuses the laser light on the sample under measurement. The controller outputs a first control signal. The current amplifier amplifies the current flowing through the sample under test, and outputs an output signal corresponding to the amplified current. The image conversion device converts and outputs the image information corresponding to the output signal of the current amplifier in synchronization with the scanning of the laser light. The image output device outputs an image according to the image information.

According to another aspect of the present invention, a scanning photoorganic current analyzing apparatus includes a laser light source, a beam scanning element, a light converging element, a control unit, a current amplifier, an imaging device, an image conversion device, and an image output device. The laser light source generates laser light. The luminous flux scanning element scans the laser light in the region according to the first control signal. The light converging element focuses the laser light on the sample under measurement. The current amplifier is connected to both ends of the sample under test, amplifies the current flowing through the sample under test, and outputs an output signal corresponding to the amplified current. The imaging apparatus forms reflected light from the sample under test and outputs imaging information. The image converting apparatus includes an apparatus for converting and outputting image information corresponding to an output signal of a current amplifier in synchronization with scanning of laser light, and a first state for outputting image information in accordance with a second control signal and outputting image formation information. And switching means for switching two states. The control means outputs the first and second control signals.

In addition, according to another aspect of the present invention, a scanning photoorganic current analyzing apparatus includes a laser light source, a beam scanning element, a light focusing element, a control unit, a first power supply, a current amplifier, an image conversion device, and an image output device. The laser light source generates laser light. The luminous flux scanning element scans the laser light in the region according to the first control signal. The light converging element focuses the laser light on the sample under measurement. The controller outputs a first control signal. The current amplifier is connected between the other end of the sample under test, the one end of which is electrically open, and the first power supply, amplifies the current flowing through the sample under test, and outputs a corresponding signal. The image conversion device converts and outputs the image information corresponding to the output signal of the current amplifier in synchronization with the scanning of the laser light. The image output device outputs an image according to the image information.

Therefore, the main advantage of the present invention is that the position of the hole or the like of the sample under measurement can be detected without applying a current bias to the sample under measurement, and therefore, a sample having a high resistance, for example, a bin A hole is formed and applicable to the detection of the position of the void in the wiring of the semiconductor integrated circuit immediately before the disconnection.

Another advantage of the present invention is that the sample to be measured does not need to form a closed circuit in the measurement, so that the shape of the sample to be measured is not limited to a specific dedicated pattern. .

[Description of Preferred Embodiment]

FIG. 1 is a schematic block diagram showing a scanning type photoorganic current analyzing apparatus of a first embodiment of the present invention.

In the embodiment shown in FIG. 1, except for the DC power source 8, one end of the sample 6 to be measured is directly grounded, and the other end is fitted with the current-up 10, except for the DC power source 8. It is different in that it is grounded.

2 is a schematic diagram showing the connection relationship between the sample 6 under test, the ground potential, and the current up 10 in more detail.

Also in this example, the wiring under measurement is a dedicated pattern for measurement composed of the wiring pattern 16 and the power supply pad 18 as in the conventional example.

One of the electrode pads 18 is directly grounded, and the other is connected to the current up 10.

That is, it is set as the structure which irradiates a laser beam on a sample, scans, and obtains a current phase, without a voltage being applied to the to-be-measured sample 6, and a current does not flow. In this embodiment, as the photoorganic current analyzing apparatus, a device having a laser beam 4 having an output of about 0.7 mW on a sample and a current up 10 having a detection limit current of 40 pA was used. Moreover, when the laser beam of the same power was used, the detection of the void under such a non-bias was possible in the sensitivity of the current up 10 whose detection limit current is 1nA or less.

3 shows a schematic diagram of the current image detected in the void portion according to the present embodiment. (A) of FIG. 3 shows the cross-sectional structure of the Al wiring sample, and (b) of FIG. 3 shows the irradiation position when the laser beam 4 scans the Al wiring 22 shown in (a) of FIG. Correspondingly, the change in the current value detected by the current up 10, (c) in FIG. 3 reflects the change in the current value in (b) in FIG. 3, and the current image obtained in the image output device 14 in FIG. A schematic is shown.

In the drawing, the Al wiring 22 has a single layer structure or a single layer structure made of a material containing Si, Cu or the like, or a laminated structure in which a layer such as TiN or W is formed above or below. The passivation film 24 or the interlayer insulating film 26 is made of a material such as SiN or SiO ₂ .

As shown in FIG. 3B, when the laser light 4 is scanned on the aluminum wiring 30 formed on the silicon substrate 28 and passes through the void 30 existing in the aluminum wiring 32. In the non-biased state, reverse current occurs in both of the voids 30, and becomes larger as the void approaches. Accordingly, the current phase in the void portion can be obtained as a characteristic phase having a pair of light and dark portions around the void 30 as shown in Fig. 3C. In addition, in FIG. 3C, the region 32 of the aluminum wiring in the current image is shown along the dotted line. The current image image can be considered to be due to the self-generating thermal electromotive force due to Seebeck effect in the void portion accompanying laser irradiation, and is completely different from the principle according to the conventional method.

Here, compared to the conventional example of FIG. 20, one end of the sample to be measured 6 is grounded to remove the DC power source 8 from the measurement system. As a result, the current phase becomes clearer and the detection sensitivity of the void is also improved.

4 is a schematic block diagram showing a second embodiment of the present invention. In other words, instead of fixedly grounding the one-side electrode as in the first embodiment, the structure has a mechanism for changing whether to ground or connect to the DC power source 8. In the figure, reference numerals 2 to 20 denote the same components as those in FIG. 1, and the exchange mechanism 34 exchanges the DC power supply 8 with the ground potential. By constructing the device in this manner, the analysis in the bias applied state can also be performed.

In the first embodiment, the one-side electrode of the sample is directly grounded. However, as shown in FIGS. 5 and 6, a load such as the resistor 36 or the capacitor 38 may be provided on the pad 18. FIG. 5 shows a third embodiment in which the resistor 36 is provided between the electrode pad 18 and the ground node, and FIG. 6 shows a fourth embodiment in which the capacitor 38 is provided. In both drawings, 6-18 represent the same component as FIG. In this way, by providing the load, noise was further reduced, a clearer image was obtained in the void portion, and the effect of improving the detection sensitivity was confirmed. In addition, the same noise reduction effect can be obtained by attaching both the resistor and the capacitor.

For example, in the case where a low frequency electromagnetic wave is transmitted to the center of the measurement space to give noise to the output signal of the current up 10, this is the case of the joule column in the resistor 36 and the capacitor 38. As the dielectric loss, low-frequency electromagnetic waves are absorbed, which may be effective for reducing noise.

In addition, when the capacitor 38 is connected, it is also effective for removing noise on the high frequency side.

In the above embodiment, the one-side electrode of the sample is fixed by OV (grounding), but may be in an open state. In other words, the measuring system does not have to be a closed circuit. 7 shows the configuration of the photoorganic current analyzing apparatus according to the fifth embodiment having the above configuration. In the drawings, reference numerals 2 to 20 denote the same components as those in FIG. The analysis in the open state is possible because the current generated in response to the void during laser irradiation is caused by the unbalanced current caused by the self-generated thermal electromotive force. Since it was not affected by the noise from the DC power supply 8 as in the first embodiment, it was confirmed that the current layer became clearer and the detection sensitivity of the voids was improved.

FIG. 8 is a schematic diagram showing in more detail the connection between the sample under test 6, the current up 10, and the ground potential in the fifth embodiment of FIG. Even in such an apparatus configuration, as the void can be detected, the object to be measured 6 does not need to be a dedicated measurement pattern, and a shape capable of connecting a current probe to at least one end thereof is sufficient. That is, the present invention can also be applied to real semiconductor integrated circuit devices.

In the fifth embodiment, the one-side electrode of the object to be measured 6 is only opened, but as shown in FIGS. 9 and 10, a load such as the resistor 36 and the capacitor 38 may be attached. . 9 shows the case of the sixth embodiment with the resistor 36 attached, and FIG. 10 shows the case of the seventh embodiment with the capacitor attached. In both drawings, reference numerals 6 to 18 are the same components as those in FIG. Thus, by attaching a load, the influence of the fluctuations of the space electric field and the floating electric field as in the third and fourth embodiments is reduced and the noise is reduced. As a result, a more clear current phase can be obtained, and the effect of improving the detection sensitivity was confirmed. In addition, the same noise reduction effect can be obtained by attaching both the resistor 36 and the capacitor 38.

In addition, although the noise was reduced in accordance with the treatment of the one-side electrode portion of the measurement object 6 in the above embodiment, the noise can also be reduced by surrounding the measurement object 6 with the electromagnetic shielding body. An example is shown in FIG. 11 is a schematic block diagram of a photoorganic current analyzing apparatus showing an example of the eighth embodiment. In the figure, reference numerals 2 to 20 denote components as shown in FIG. 1, and the laser scanning microscope 2 and the object to be measured 6 are made of an alloy such as a permalloy or an electron shield 40 such as a common metal. It is covered by the finished case. As described above, by covering the object to be measured 6 with the electromagnetic shielding body 40, the effects of variations in the space ceiling and the floating electric field were alleviated, and noise was reduced, and the same effects as in the sixth and seventh embodiments were confirmed.

In addition, in this embodiment, the one-side electrode of the object under test 6 is only in an open state, but the same as in the first embodiment, and even when connected to the ground potential, the resistor 36 is similar to the sixth and seventh embodiments. Even when the capacitor 38 and the capacitor 38 are connected, of course, there is an effect of reducing noise.

In the first to eighth embodiments, an example in which the detection sensitivity of the void is improved by improving the S / N ratio (signal / noise) and obtaining a clearer current phase as the noise is reduced. However, at the time of laser irradiation, the same S / N ratio is improved and the detection sensitivity of Hide is improved by increasing the current itself generated corresponding to the void. The example is shown below.

12 is a schematic block diagram showing the structure of a scanning type photoorganic current analyzing apparatus of a ninth embodiment of the present invention.

The configuration of the first embodiment of FIG. 1 is a configuration in which the scanning speed control signal ss is sent from the apparatus control section 20 to the scanning speed control section 42 of the laser light, and the scanning speed of the laser light can be changed based on this signal ss. One point differs from one point in that the sampling rate of the current up 10 can be changed in accordance with the signal si from the device control unit 20.

For example, in the structure of the laser scanning microscope of FIG. 22, when the laser optical scanning device 102 is an acoustooptical deflection element, the speed which changes the frequency of the high frequency limit signal which is an input of this acoustooptic deflection element, If the structure which can be changed based on the signal ss can change the speed which a polarization angle changes, the scanning speed of a laser beam can be changed.

In this embodiment, in the photoorganic current analyzing apparatus, the scanning speed of the laser beam is set to 33 milliseconds or less (for example, 30 frames / sec) per screen of the conventional apparatus, and according to the scanning speed. The function is to increase the sampling rate, that is, increase the scanning speed of the laser beam to 33 milliseconds or less per screen without changing the display resolution capability of the current. In the present invention using the electromotive force in the void portion, the current can be increased corresponding to the void portion by increasing the scanning speed of the laser beam. This is because the current generated corresponding to the voids during laser irradiation is due to the thermal resistance at the void portion.

FIG. 13 is a schematic diagram showing why an increase in beam scanning speed causes an increase in current. (A) of FIG. 13 is a cross-sectional structure of the Al wiring sample, and (b) and (c) of FIG. 13 show the Al wiring 22 when the laser beam 4 is irradiated to point A of (a) of FIG. In Fig. 1, temperature gradients on both sides of the irradiation point are shown. The state when the scanning speed of the beam 4 is slow is (b) of FIG. 13, and (c) is FIG. 13 which shows the state when it is fast. In the drawing, reference numerals 4 to 30 denote the same components as those in FIG. 3, and express the change 44 of the temperature distribution when the laser beam 4 is irradiated to the point A by hatching density. As a result, the higher the hatching density in the drawings, the higher the temperature. According to the difference between the temperature gradients kr and kl on the right and left sides of the irradiation point, the current I _A according to the thermal electromotive force is generated at the point A where the beam 4 is irradiated.

In the void portion 30 and its periphery, the thermal conductivity is lowered and the thermal resistance is high as compared with other normal places in the Al wiring 22. Therefore, as shown in FIG. 13, when a beam is irradiated in the vicinity of a void, the temperature gradient kl of a void side with respect to a irradiation point becomes large compared with the opposite kr. As a result, an electromagnetic flow in the left direction is generated, and a current I _A is generated. The magnitude of the generated current depends on the difference of the temperature gradients on both sides of the irradiation point, and the larger the difference, the larger the current. In addition, since the temperature gradient is caused by the difference in the thermal conduction speeds at both the irradiation points, as shown in FIG. Since is greater than the increase in the temperature gradient kr, the difference between kr and kl increases and the current I _A also increases.

Therefore, as the scanning speed is increased, S / N, which is an output signal of the current up 10, is improved, and a clearer current phase can be obtained.

In the ninth embodiment, the current generated in response to the void is increased by increasing the scanning speed of the laser beam and increasing the difference between the thermal inclinations of both irradiation points. Also in cooling, since the thermal electromotive force increases with temperature decrease, the current can be increased.

FIG. 14 is a schematic block diagram of the photoorganic current analyzing apparatus of the tenth embodiment. In the figure, reference numerals 2 to 20 denote the same components as those in FIG. 1, and the apparatus further includes a cooling device 46 for cooling the sample. As the cooling device 46, a cooling device using liquefied gas such as nitrogen or helium, or an electronic cooling device using a Peltier effect or the like can be used. According to the cooling device 46, it was confirmed that as the sample temperature is lower than room temperature, the current corresponding to the void increases and the detection sensitivity of the void improves. This is accompanied by an increase in the temperature change Δt at the irradiation point shown in FIG. 13B.

In the second to ninth embodiments, a common embodiment for improving the detection sensitivity of the voids in the analysis under the non-bias shown in the first embodiment is shown. However, the present analysis method is described on an example device such as LSI. Embodiments useful for applications in the analysis of Al wirings, via holes, and the like are shown.

FIG. 15 shows a schematic block diagram of a laser scanning microscope in the eleventh embodiment.

In this embodiment, the output wavelength of the laser light source 100 is made 1.2 m or more, for example in FIG. This eliminates the generation of the photoorganic current in the Si substrate, and enables the detection of voids in the Al wiring in a non-biased state. In a real device such as an LSI, unlike the Al wiring test sample, the Al wiring is always in contact with the Si substrate somewhere. In the conventional apparatus, as the light beam 4, a laser beam having a higher energy than the band gap energy (1.19 V; corresponding to the wavelength of 1.2 m of light) of Si, such as wavelength 633 mm (HeNe laser) and 488 mm (Ar laser), is used. Was doing. Therefore, when the beam is irradiated to the Si substrate, an electron-hole band is generated in the Si substrate, and this electron or hole is attracted to the center of the Al wiring at the contact point and detected as a current. The photoorganic current generated in this Si substrate is extremely large compared to the current generated in response to the voids in the Al wiring under the same conditions. In this Si substrate part, it is difficult to analyze actual devices, such as LSI, by this method with a conventional apparatus by the influence of a photoorganic current. In the present embodiment, the wavelength of the light beam 4 is set to 1.2 mu m or more below the band gap energy of Si to suppress the generation of electron-hole bands in the silicon substrate, thereby suppressing the influence of the photoorganic current in the Si substrate portion. I can eliminate it.

As more 1.2㎛ wavelength laser light source, for example, it is possible to use a solid state laser using a crystal doped with Co, Ni, etc. to MgF _2.

In this embodiment, the case where the substrate is Si has been described, but in the case of other semiconductor substrates, the same effect as in the above embodiment can be obtained by using a laser light source having a lower energy than the band gap of the substrate material.

In the eleventh embodiment, an example in which the influence from the silicon substrate is removed in place of the wavelength of the light beam is shown. However, the influence of the substrate can also be eliminated by irradiating the laser beam only with Al wiring.

FIG. 16 is a schematic block diagram of an optical organic current analysis device showing a twelfth embodiment of the present invention. This embodiment differs from the first embodiment in FIG. 1 in that it has a scanning area input device 48.

On the basis of the input signal from the scanning area input device 48, the laser light scanning area designation signal r from the device control unit 20 is output, and the laser light of the laser scanning microscope 2 is scanned in accordance with the signal r. The area to be limited is limited.

17 is a schematic diagram showing the imaging information by the photoorganic current analysis device. In the object under test in which the Al wiring 60 is formed on the Si substrate 62, the void 64 is present in the Al wiring 60. In this case, the laser light 4 is scanned only in the predetermined region 66 on the Al wiring 60. In this embodiment, since the scanning area input device 48 which can set the beam dice and the range on the monitor screen is added to the scanning photoorganic current analyzer, the laser beam is irradiated only on the Al wiring. It was confirmed that the influence of the photoorganic current generated in the substrate portion can be eliminated, and even the actual device such as the LSI can detect the void in the Al wiring with the light sensitivity.

In the eleventh embodiment, the irradiation position and the range of the laser beam 4 are controlled to extract only the Al wiring information. However, the same effect can be obtained even if the position and area for detecting current can be set.

18 is a schematic block diagram of a scanning optical organic current detection device showing a thirteenth embodiment of the present invention.

This embodiment differs from the first embodiment in FIG. 1 in that the current detection area input device 49 is provided.

Based on the input signal from the current detection area input device 49, the current detection area designation signal ri is output from the device control unit 20, and the area where the current up 10 detects the current is limited in accordance with the signal ri. do.

19 is a current phase showing an example of the present embodiment. FIG. 19 (a) shows a conventional current image before designating a position and region for performing current detection in a real device such as an LSI, and FIG. 19 (b) designates on an Al wiring using the function of this embodiment. The current phase redisplays only the area. In the measurement object 6 in which the Al wiring 60 is formed on the Si substrate 62, a void 64 is present in the Al wiring 60. In this case, only during the period in which the laser light 4 scans the constant region 68 on the Al wiring 60, the current up 10 detects the photoorganic current.

In the re-displayed current phase 68, an image 70 of the void is shown in the designated area.

In the conventional photoorganic current analyzing apparatus, the displacement from the reference of each point is converted to luminance on the basis of the average current value in the scanning area of the beam, and is output as, for example, a current of 256 gradations in general. Therefore, when the current phase is displayed by the conventional photoorganic current analyzing apparatus, as shown in Fig. 19 (a), the area of the Al wiring is black and the area of the Si substrate is white and the information of the Al wiring is not displayed. Therefore, when the sensitivity of the current up is raised to increase the detection resolution capability, the range of the current displacement that can be expressed is narrowed. In order to detect voids in the Al wiring, it is usually necessary to hold a current displacement of less than InA. However, for example, when a current detection limit of 40 pA or lower detection limit (detection resolution) is used, the current range that can be expressed is very small, about 10 nA. . As shown in Fig. 19, if there is a Si substrate portion in the scanning region, the average current value in the region is at the power level, and if it is assumed that the luminance conversion is made out of the range of 10 nA based on that, the Si substrate as shown in Fig. 19A is shown. Each of the negative / Al wiring portions becomes an image saturated at the top and bottom of the luminance gradation, that is, a white color / black color.

In this embodiment, by adding a function of arbitrarily setting a region for current detection or luminance conversion to the scanning photoorganic current analysis device, the influence of the photoorganic current generated in the Si substrate portion can be eliminated, and the LSI It was confirmed that the voids in the Al wiring can be detected with light sensitivity even in the case of devices such as the above.

Claims (15)

In the scanning type photoorganic current analysis device which detects the photoorganic current induced in the sample 6 to be measured by irradiating with scanning the connected laser light, the laser light source 100 which generate | occur | produces the said laser light, and 1st control Luminous flux scanning means 102 for scanning the laser light in an area corresponding to the signal, luminous focusing means 106 for focusing the laser light on the sample under test, and control means for outputting the first control signal. (20), current amplifying means (10) for amplifying a current flowing through the sample to be measured and outputting an output signal corresponding to the amplified current, and an output signal of the current amplifying means in synchronization with the scanning of the laser light The image converting means 12 converts and outputs the image information corresponding to the image information, the image output means 14 for outputting the image according to the image information, and neither the voltage nor the current is applied to the sample to be measured. And a sample state setting means for allowing the photoorganic current analysis device to obtain a current flowing through the sample to be measured. 2. An image forming means according to claim 1, further comprising image forming means (104) for forming reflected light from said sample under test and outputting image forming information to said image converting means, wherein said image converting means (12) is provided from said control means. And the image information and the image formation information are selectively output to the image output means in accordance with a second control signal. 2. A first state according to claim 1, wherein the first power source 8 that supplies the first potential, both ends of the sample under test 6, and the current amplifying means 10 are connected, and the sample under test ( 6) and a switching means 34 for switching a second state in which the first power source 8 and the current amplifying means 10 are connected in series. . 2. The sample to be measured has connection ends at both ends, one of the connection ends is connected to the current amplifying means, and the sample state setting means is coupled between the other of the connection ends and the ground potential. Scan type photoorganic current analysis device, characterized in that it comprises a resistor (36). 2. The sample to be measured has connection ends at both ends, one of the connection ends is connected to the current amplifying means, and the sample state setting means is coupled between the other of the connection ends and the ground potential. Scanning photoorganic current analysis device, characterized in that it comprises a capacitor (38). A scanning type photoorganic current analyzing apparatus for detecting a photoorganic current induced in a sample to be measured by irradiating while scanning the connected laser light, comprising: a laser light source 100 for generating the laser light and a first control signal Luminous flux scanning means 102 for scanning the laser light in an area, luminous focusing means 106 for focusing the laser light on the sample under test, and control means 20 for outputting the first control signal. And a first power source 9 for supplying a first potential, and the other end of the sample under test, the one end of which is electrically open, and the first power source to supply current flowing through the sample under test. Current amplifying means 10 for amplifying and outputting a corresponding signal, and image converting means 12 for converting and outputting image information corresponding to the output signal of the current amplifying means in synchronization with the scanning of the laser light and the image thereof. Information And an image output means (14) for outputting an image according to the present invention. The image converting means (12) according to claim 6, further comprising image forming means (104) for forming reflected light from the sample under test and outputting image forming information to the image converting means. And switching means for switching the first state for outputting the image information to the image output means and the second state for outputting the imaging information, wherein the control means outputs the second control signal. Scanning type photoorganic current analysis device. 7. The scan type photoorganic current analysis device according to claim 6, further comprising a resistor (36) connected to one end of the sample under test in the open state. 7. The scan type superorganic current analysis device according to claim 6, further comprising a capacitor (38) connected between one end of the sample under test and the first power source. 7. An electron shield according to claim 6, further comprising at least the laser light source 100, the beam scanning means 102, the light converging means 106, and the sample 6 to be measured. Scanning photoorganic current analysis device. 7. The scanning optical organic current analysis device according to claim 6, wherein the luminous flux scanning means (102) further comprises a scanning speed varying means (42) capable of changing the scanning speed of the laser light. 7. The scan type photoorganic current analyzing apparatus according to claim 6, further comprising cooling means (46) for cooling the sample under test to be below an environmental temperature. 7. The scanning type photoorganic device according to claim 6, wherein the laser light generated by the laser light source when the sample to be measured contains a semiconductor has a wavelength longer than a wavelength corresponding to a band gap energy of the semiconductor. Current analyzer. 8. The control apparatus according to claim 7, wherein said control means further comprises a control signal generating means (48) for generating said first control signal for scanning said laser light in a region corresponding to a part of said designated imaging information. Scanning type photoorganic current analysis device. 8. The apparatus according to claim 7, wherein said control means further comprises region designation signal output means (49) for outputting region designation signals for designating an area corresponding to a part of said imaging information. And image information output means for outputting the image information corresponding to the area corresponding to the area designation signal.