JP2007113992A - Probing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique capable of restraining the charges generated by electron beam irradiation from accumulating in a measuring sample, in a probing device that uses an SEM (scanning electron microscope) as the observation means. <P>SOLUTION: A plurality of probes 10 is operated, while observing a SEM image imaged on an operation screen, and tips thereof are brought into contact with respective patterns of the sample 8, the charges generated by the electron beam irradiation, when observing the SEM image, is neutralized by irradiating the sample 8 with ultraviolet rays from a light source part 3 and an optical system 4 installed outside a chamber 5, and the charges are restrained thereby from accumulating in the sample 8. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a probing apparatus, and more particularly to a technique that is effective when applied to a probing apparatus using a scanning electron microscope (SEM) as an observation means.

  A detection process in which charged particles generated from a sample are detected by scanning and irradiating a sample having an insulator to obtain a charged particle signal, and the sample is pulsed with excitation light. Has disclosed a charged particle detection method having a conduction process in which electrons in an insulating film are excited to conduct and thereby release electric charges (see, for example, Patent Document 1).

In addition, the ultraviolet irradiation system is controlled by the irradiation control means, the scanning of the charged particle beam is controlled by the scanning control means, and further, the irradiation control means and the scanning control means are controlled by the overall control device, and by synchronizing each other, An inspection and measurement method capable of obtaining an electron beam image with stable charge quality while maintaining a small charge-up state is disclosed (for example, refer to Patent Document 2).
JP 2000-36273 A (paragraph [0025], FIG. 1B) JP 2000-357483 A (paragraphs [0046] to [0048], FIG. 1)

  For example, there is a probing apparatus that measures electrical characteristics of a semiconductor element by directly contacting a plurality of probes (probes) with wiring or contacts of a nanometer-scale semiconductor element. In this probing apparatus, a probe having a tip diameter of about 10 nm to 10 μm is used, and the movement of a plurality of probes is operated while observing an SEM image displayed on the operation screen. The SEM scans and irradiates the surface of a semiconductor element with an electron beam, receives secondary electrons or reflected electrons emitted from the surface with a detector, and displays the intensity as an image of a bright spot array on a monitor synchronized with the scanning. It is an electron microscope which can observe the fine structure or form of the surface of the semiconductor element.

  By the way, in a probing apparatus using an SEM as an observation means, electric charges are accumulated in a part of an insulating film or an insulated conductor film provided in a semiconductor element by scanning irradiation of an electron beam, and the electric characteristics inherent in the semiconductor element are obtained. There is a problem that it fluctuates. Therefore, the present inventors prevent fluctuations in the characteristics of the semiconductor element by, for example, lowering the acceleration voltage of the electron beam or reducing the irradiation amount of the electron beam. However, if the semiconductor elements are further miniaturized and it is necessary to improve the resolution and image quality of the SEM, it is expected that it is difficult to suppress fluctuations in the characteristics of the semiconductor elements only by the above countermeasures.

  An object of the present invention is to provide a technique capable of suppressing charge accumulation in a measurement sample caused by electron beam irradiation in a probing apparatus using an SEM as an observation means.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  The present invention is a probing apparatus using an SEM as an observation means, and includes a light source capable of irradiating a sample with ultraviolet light having a wavelength of 300 nm or less outside or in a chamber, and an SEM image displayed on an operation screen is displayed. A plurality of probes are operated while observing to directly contact each pattern constituting the sample, and then light is emitted from the light source to irradiate the sample placed in the chamber with ultraviolet rays.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  After observing the SEM image displayed on the operation screen, by irradiating ultraviolet rays from a light source installed outside or inside the chamber, the charges generated by electron beam scanning when observing the SEM image are neutralized. Thus, accumulation of electric charges on the sample can be suppressed. Thereby, the fluctuation | variation of the electrical property of the sample measured can be suppressed.

  In this embodiment, when it is necessary for the sake of convenience, the description will be divided into a plurality of sections or embodiments. However, unless otherwise specified, they are not irrelevant to each other. Some or all of the modifications, details, supplementary explanations, and the like are related.

  Also, in this embodiment, when referring to the number of elements (including the number, numerical value, quantity, range, etc.), unless otherwise specified, or in principle limited to a specific number in principle. The number is not limited to the specific number, and may be a specific number or more. Further, in the present embodiment, the constituent elements (including element steps and the like) are not necessarily essential unless particularly specified and apparently essential in principle. Yes. Similarly, in this embodiment, when referring to the shape, positional relationship, etc. of the component, etc., the shape, etc. substantially, unless otherwise specified, or otherwise considered in principle. It shall include those that are approximate or similar to. The same applies to the above numerical values and ranges.

  In all the drawings for explaining the embodiments, components having the same function are denoted by the same reference numerals in principle, and the repeated description thereof is omitted. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
A probing apparatus according to the first embodiment will be described with reference to FIGS. FIG. 1 is an overall schematic configuration diagram of a probing device, and FIG. 2 is a schematic configuration diagram of another example of an optical system such as a condensing lens provided in the probing device.

  As described above, in a probing apparatus using an SEM as an observation means, when an SEM image is displayed on an operation screen, a charge is applied to a part of an insulating film or an insulated conductor film included in the sample by an electron beam that is scanned and applied to the sample. Is accumulated, and there is a problem that the electrical characteristics inherent to the sample fluctuate. Therefore, in the first embodiment, after the SEM image is projected on the operation screen using the probing apparatus having the function of irradiating ultraviolet rays as shown in FIG. 1, that is, the sample is irradiated with ultraviolet rays after being scanned and irradiated with the electron beam. Then, by neutralizing the charge generated by the electron beam scanning irradiation, fluctuations in the electrical characteristics of the sample are suppressed.

  As shown in FIG. 1, the probing apparatus 1 is roughly composed of a prober body 2, a light source unit 3, and an optical system 4 such as a condenser lens. The prober body 2 includes a chamber 5 that is evacuated, an electron gun 6 that emits an electron beam, and an electron beam irradiation unit that includes an objective lens 7 that focuses the electron beam on the sample 8. When the sample 8 is scanned and irradiated with an electron beam emitted from the electron gun 6, charged particles such as secondary electrons are generated from the surface of the sample 8. The surface of the sample 8 is scanned and irradiated with a finely focused electron beam, the generated secondary electrons are detected by an electron detector, and the generated amount is converted into a luminance signal, whereby an SEM image is obtained. Since the convex portion has a larger amount of secondary electrons generated in the concave and convex portions, the convex portion is bright and the concave portion is dark in the SEM image, and the three-dimensional concave and convex portions can be represented as a two-dimensional image on the operation screen.

  In the chamber 5, a sample stage 9 on which the sample 8 is mounted, a plurality of probes 10, and a probe driving mechanism 11 are installed. The plurality of probes 10 are operated while observing an SEM image displayed on the operation screen, and are brought into direct contact with each pattern constituting the sample 8. Although not shown, an electron detector for detecting secondary electrons emitted from the sample 8 is installed above the objective lens 7, for example.

The light source 3 and the optical system 4 installed outside the chamber 5 are used for irradiating the sample 8 with ultraviolet light. As the light source, a mercury xenon (HgXe) lamp 12 having a strong spectrum near 253 nm and close to a point light source is used. The wavelength of the HgXe lamp 12 to be used is considered to be an appropriate range of, for example, 300 nm or less in order to suppress a temperature rise (of course, it is not limited to this range depending on other conditions). Furthermore, the range of 214 to 276 nm is a necessary wavelength, and 254 nm is considered to be the most suitable wavelength for use. The intensity of the HgXe lamp 12 is set to be 5 mW / cm ² or more on the surface of the sample 8, for example. The stronger the strength, the better. However, the HgXe lamp 12 becomes larger and it becomes difficult to control the heat generation.

  The HgXe lamp 12 provided in the light source unit 3 is built in the housing 13 and held on the light source support base 14. Moreover, the lamp | ramp air cooling mechanism 18 is installed in the housing | casing 13, By this, the surface temperature of the housing | casing 13 can be maintained at 50 degrees C or less, for example.

  The optical system 4 that collects ultraviolet rays is provided with a cover 19 for preventing leakage of ultraviolet rays, a half mirror 20, and a shutter 21. The half mirror 20 is provided to remove heat rays contained in the light emitted from the light source. When the heat ray hits the sample 8 or the sample stage 9, the sample 8 moves due to thermal expansion or the like, and thus it is necessary to remove the heat ray. Further, by adjusting the angle of the half mirror 20, it is possible to irradiate the surface of the sample 8 with ultraviolet rays without being blocked by equipment in the chamber 5, such as the probe 10. The shutter 21 is provided to block the irradiation of ultraviolet rays onto the sample 8 until the light source is stabilized immediately after the power is turned on. For example, the shutter 21 may have a general shape used in a camera or the like. The shutter 21 can also be used for intermittent irradiation for the purpose of suppressing the temperature rise of the sample 8 due to the heat rays. Further, the optical system 4 is provided with a diaphragm 22, a filter 23, and a lens 24 for adjusting the light irradiation amount, but these are not always necessary and can be omitted.

  FIG. 2 shows a schematic configuration diagram of another example of the optical system. The basic configuration is the same as that of the optical system shown in FIG. 1 except that a lens 24 is installed between the filter 23 and a window 5 a made of synthetic quartz provided in the chamber 5.

  By the way, in the probing apparatus 1, the method of removing the heat rays contained in the light emitted from the light source by the half mirror 20 is adopted. However, the method for removing the heat rays is not limited to this. Below, the 1st-5th heat ray removal method applied to the probing apparatus 1 is demonstrated. FIG. 3 is a schematic diagram for explaining the first to fifth heat ray removing methods. In FIG. 3, the ultraviolet rays are irradiated from directly above the sample, but actually, the ultraviolet rays are irradiated with a predetermined angle tilted in the normal direction of the surface of the sample.

  First, in the first heat ray removing method (FIG. 3A), a filter 25 that absorbs infrared IF and transmits ultraviolet UV is installed. The light (including infrared IF and ultraviolet UV) emitted from the light source unit 3 is passed through the filter 25 to extract only the ultraviolet UV, and is further irradiated to the narrowed sample 8 by the diaphragm 26. In the second heat ray removing method (FIG. 3B), a mirror 27 that transmits infrared IF and reflects ultraviolet UV is installed. The light (including the infrared IF and the ultraviolet UV) emitted from the light source unit 3 is reflected by the mirror 27 to extract only the ultraviolet UV, and is further irradiated to the narrowed sample 8 by the diaphragm 26. In the third heat ray removing method (FIG. 3C), the diaphragm 26 is made small, and light (including infrared IF and ultraviolet UV) emitted from the light source unit 3 is irradiated only on a predetermined sample 8, The region other than the sample 8 is not irradiated with light. In the fourth heat ray removing method (FIG. 3D), a shutter 28 is installed, light (including infrared IF and ultraviolet UV) emitted from the light source unit 3 is intermittently irradiated by the shutter 28, and further narrowed by the diaphragm 26. Irradiate the aperture sample 8. This fourth heat ray removing method is employed in the optical system 4 provided in the above-described probing device 1 of FIG. In the fifth method (FIG. 3E), a plurality of mirrors 27 (for example, three mirrors 27a, 27b, and 27c) that transmit the infrared IF and reflect the ultraviolet UV are installed. The light (including the infrared IF and the ultraviolet UV) emitted from the light source unit 3 is reflected by the mirror 27 to extract only the ultraviolet UV, and is further irradiated to the narrowed sample 8 by the diaphragm 26.

  In addition, although these 1st-5th heat ray removal methods may each be used independently, you may use combining two or more heat ray removal methods. For example, by combining the second and third heat ray removing methods, it is possible to reduce the aperture 26 after taking out only the ultraviolet rays UV so that the ultraviolet rays UV are not irradiated to the region other than the predetermined sample 8.

  As described above, according to the first embodiment, the plurality of probes 10 are operated while observing the SEM image displayed on the operation screen, and the tips of the probes 10 are brought into direct contact with each pattern of the sample 8. By irradiating the sample 8 with ultraviolet rays from the light source unit 3 and the optical system 4 installed outside, the charge generated in the sample 8 is neutralized by the electron beam that is scanned and irradiated when observing the SEM image. Accumulation of charge in 8 can be suppressed. Thereby, the characteristic fluctuation | variation of the sample 8 to be measured can be suppressed. Furthermore, since the characteristic variation of the sample 8 is suppressed, the time for measuring the characteristic of the sample 8 can be shortened, and the product development period can be shortened or the yield can be improved.

  In the first embodiment, while observing the SEM image displayed on the operation screen, the tips of the plurality of probes 10 are brought into direct contact with each pattern of the sample 8 and then the sample 8 is irradiated with ultraviolet rays. While the probe 10 is being operated, the sample 8 may be irradiated with ultraviolet rays. Thereby, it can prevent that the sample 8 in which the electric charge was accumulated by irradiation of the electron beam is irreversibly changed.

(Embodiment 2)
The probing device according to the second embodiment will be described with reference to the overall schematic configuration diagram of the probing device shown in FIG. In the probing device 1 according to the first embodiment described above, the ultraviolet light source is installed outside the chamber 5, but in the probing device according to the second embodiment, the ultraviolet light source is installed in the chamber.

  As shown in FIG. 4, the probing device 31 is provided with a chamber 32 similar to the probing device 1 according to the first embodiment described above, and an electron beam irradiation unit including an electron gun 33, an objective lens 34, and the like. In the chamber 32, a sample stage 35, a probe 36, a probe driving mechanism 37, and the like are installed. The difference from the probing device 1 is that in the probing device 31, an ultraviolet light source 38 is installed in the chamber 32, and the light source 38 can be brought closer to the sample 39. For the light source 38, for example, a low-pressure mercury lamp having a strong spectrum near 253 nm is used. A power connection 40 connected to the light source 38 is placed outside the chamber 32.

  Similarly to the first embodiment described above, also in the probing device 31, there is a concern about the influence of the heat rays contained in the light emitted from the light source 38 on the sample 39. Therefore, for example, it is preferable to prevent the temperature of the sample 39 from rising by using any of the first to fifth methods described above.

  As described above, according to the second embodiment, the probing device 31 can bring the light source 38 closer to the sample 39 than the probing device 1 of the first embodiment described above, and the sample 39 can be scanned by electron beam scanning. Neutralization of the charge accumulated in the substrate can be more effectively performed by ultraviolet rays.

(Embodiment 3)
The probing apparatus according to the third embodiment will be described with reference to the overall schematic configuration diagram of the probing apparatus shown in FIG.

  As shown in FIG. 5, a light source 52 similar to the light source 38 included in the probing device 31 according to the second embodiment described above is prepared. In the probing device 51 according to the third embodiment, the light source 52 is placed outside the chamber 53. Install as close to the sample 54 as possible. For example, a low-pressure mercury lamp having a strong spectrum near 253 nm is used as the light source 52, and light emitted from the light source 52 is irradiated to the sample 54 from a window 53 a provided in the chamber 53. Also in the probing apparatus 51, since there is a concern about the influence of the heat rays contained in the light emitted from the light source 52 on the sample 54, the temperature of the sample is increased by using, for example, any one of the first to fifth methods described above. It is preferable to prevent this. Since the configuration of the probing device 51 other than the place where the light source 52 is installed is the same as the configuration of the probing device 31 according to the second embodiment described above, the description thereof is omitted.

  As described above, according to the third embodiment, similarly to the second embodiment described above, the probing apparatus 51 can bring the light source 52 closer to the sample 54 than the probing apparatus 1 of the first embodiment described above. Thus, neutralization of charges accumulated in the sample 54 due to electron beam scanning irradiation can be more effectively performed by ultraviolet rays.

(Embodiment 4)
Ultraviolet irradiation of the sample can be incorporated into a series of operating procedures (sequence) for measuring the electrical characteristics of the sample. Thereby, stabilization and simplification of the characteristic measurement of a sample can be achieved. The ultraviolet irradiation incorporated in the measurement sequence according to the fourth embodiment will be described with reference to the process chart shown in FIG.

  First, a sample (for example, a MONOS (Metal Oxide Nitride Oxide Semiconductor) or a non-volatile memory such as a flash memory, or a semiconductor integrated circuit such as an SOC (System On Chip) produced by a process of 90 nm or less) is placed on the sample stage. After moving to a predetermined position in the chamber of the probing apparatus, the tips of a plurality of probes are brought into direct contact with each pattern constituting the sample while observing the SEM image displayed on the operation screen. When the sample is a semiconductor integrated circuit, each pattern is, for example, an elliptical or substantially circular electrode pattern having a diameter of about 100 to 500 nm, or a wiring pattern having a width of 90 nm or less. Although a semiconductor integrated circuit is illustrated here as a sample, the present invention is not limited to this.

  Next, by pressing the operation switch (step P1 in FIG. 6), the following steps (step P2 to step P4 in FIG. 6) are automatically performed. First, SEM blanking is performed (step P2 in FIG. 6). Blanking is a function that deflects an electron beam so that it does not hit the sample, and the electron detector that detects secondary electrons is also turned off. Next, the sample is irradiated with ultraviolet rays for a certain time (step P3 in FIG. 6), and then the electrical characteristics of the sample are measured (step P4 in FIG. 6). A voltage is applied to each terminal, and the current at each terminal is measured. The tester reads this to measure the electrical characteristics of the sample.

  The measurement sequence described above can be applied to any of the probing device 1 according to the first embodiment, the probing device 31 according to the second embodiment, and the probing device 51 according to the third embodiment.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  For example, in the above-described embodiment, the case where the SEM is applied to a probing apparatus using observation means has been described. However, the present invention can be applied to any probing apparatus that requires ultraviolet irradiation.

  Moreover, in the said embodiment, although the probing apparatus provided with the several independent probe each was illustrated, this probing apparatus provided with the probe card which has arrange | positioned the several probe according to all the electrode pads of an integrated circuit, for example is this. The invention can be applied. A signal line corresponding to each probe protrudes from the probe card and is connected to a tester.

  The present invention can be applied to a probing apparatus that requires ultraviolet irradiation.

1 is an overall schematic configuration diagram of a probing device according to a first embodiment. It is a schematic block diagram of the other example of optical systems, such as a condensing lens, with which the probing apparatus by this Embodiment 1 is equipped. (A)-(e) shows the schematic diagram for demonstrating the temperature rise prevention countermeasure by this Embodiment 1. FIG. It is a whole schematic block diagram of the probing device by this Embodiment 2. It is a whole schematic block diagram of the probing apparatus by this Embodiment 3. It is process drawing for demonstrating the ultraviolet irradiation integrated in the measurement sequence by this Embodiment 4. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Probing apparatus 2 Prober main body 3 Light source part 4 Optical system 5 Chamber 5a Window 6 Electron gun 7 Objective lens 8 Sample 9 Sample stage 10 Probe 11 Probe drive mechanism 12 Xenon lamp 13 Case 14 Light source support stand 18 Lamp air cooling mechanism 19 Cover 20 Half mirror 21 Shutter 22 Aperture 23 Filter 24 Lens 25 Filter 26 Aperture 27, 27a, 27b, 27c Mirror 28 Shutter 31 Probing device 32 Chamber 33 Electron gun 34 Objective lens 35 Sample stage 36 Probe 37 Probe drive mechanism 38 Light source 39 Sample 40 Power supply Connection part 51 Probing device 52 Light source 53 Chamber 53a Window 54 Sample IF Infrared UV UV

Claims (5)

In the chamber to be evacuated,
(A) a sample stage on which a sample is mounted;
(B) a plurality of probes in contact with each pattern constituting the sample;
(C) an electron beam irradiation unit that scans and irradiates the sample with an electron beam;
(D) an electron detector that detects charged particles generated from the sample by scanning irradiation with the electron beam;
Outside the chamber,
(E) a light source that emits light including ultraviolet light having a wavelength of 300 nm or less;
(F) A probing apparatus comprising: an optical system that collects the ultraviolet rays and irradiates the sample. In the chamber to be evacuated,
(A) a sample stage on which a sample is mounted;
(B) a plurality of probes that contact each pattern constituting the sample;
(C) an electron beam irradiation unit that scans and irradiates the sample with an electron beam;
(D) an electron detector that detects charged particles generated from the sample by scanning irradiation with the electron beam;
(E) A probing apparatus comprising: a light source that emits light including ultraviolet light with a wavelength of 300 nm or less and irradiates the sample with the ultraviolet light. In the chamber to be evacuated,
(A) a sample stage on which a sample is mounted;
(B) a plurality of probes that contact each pattern constituting the sample;
(C) an electron beam irradiation unit that scans and irradiates the sample with an electron beam;
(D) an electron detector that detects charged particles generated from the sample by scanning irradiation with the electron beam;
Outside the chamber,
(E) A probing apparatus comprising: a light source that emits light including ultraviolet light with a wavelength of 300 nm or less and irradiates the sample with the ultraviolet light.   4. The probing apparatus according to claim 1, wherein a filter that absorbs infrared rays, one or more mirrors that transmit infrared rays and reflect ultraviolet rays, light irradiation between the light source and the sample. A probing apparatus comprising one or more of a diaphragm for adjusting the amount and a shutter for indirectly irradiating light.   4. The probing apparatus according to claim 1, wherein the plurality of probes are operated while observing an image displayed on an operation screen.

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