JP2011165669A - Mirror electron type sample inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact charged particle beam device capable of maintaining high vacuum even during emission of electron beams. <P>SOLUTION: A non-evaporation getter pump is arranged at an upstream of an electron optical differential exhaust of the charged particle beam device, the minimum essential ion pump 118 is arranged downstream, and both are used in common. Furthermore, a removable coil is mounted on an electron gun part. With this, the compact charged particle beam device can be obtained capable of maintaining a vacuum degree in a column in high vacuum at a 10<SP>-8</SP>Pa scale such as, for example, a compact scanning electron microscope and the charged particle beam device having a plurality of columns. Furthermore, a compact SEM column to monitor a position of a probe of a prober device to directly measure electrical characteristics of a semiconductor can be easily built in. In addition, downsizing of an electron beam irradiation column of a mirror projection type electron beam inspection device for semiconductor element inspection becomes possible. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electron microscope, and more particularly to a mirror projection type electron beam inspection apparatus for semiconductor element inspection.

  A conventional scanning electron microscope (SEM) accelerates an electron beam emitted from an electron gun composed of a field emission type or a thermal field emission type electron source, and forms a thin electron beam with an electron lens. A scanning deflector is used as an electron beam to scan on the sample, and the resulting secondary electrons or reflected electrons are detected to obtain an image. As a material for the electron source, tungsten is used in the case of a general-purpose SEM. In addition, an electron source for semiconductor observation may contain zirconia in tungsten.

In order to emit a good electron beam from the electron source over a long period of time, it is necessary to maintain a high vacuum (10 ⁻⁷ to 10 ⁻⁸ Pa) around the electron source. For this reason, conventionally, as shown in FIG. 2, a method of forcibly differential evacuation of the column by a plurality of ion pumps (IP-1, IP-2, IP-3) has been adopted. This content is described in JP-A-2002-358920. Although the ion pump has the advantage that it can be maintained at a pressure of 10 ⁻⁸ Pa or less only by energization without moving parts, it has a size of several tens of cm square and a magnetic field is generated on the column side in order to generate a magnetic field. It is a pump that requires considerable volume and weight, such as needing a shield. Further, as a method for eliminating this and reducing the size, a non-evaporable getter pump is incorporated as described in US Pat. No. 4,833,362 and JP-A-6-111745, or JP-A-2000- As described in Japanese Patent No. 149850, there is an electron gun that does not require an ion pump by incorporating a getter ion pump.

JP 2002-358920 A US Pat. No. 4,833,362 JP-A-6-111745 JP 2000-149850 A JP 09-326425 A

When a field emission electron gun is used as described above, a high degree of vacuum of 10 ⁻⁷ to 10 ⁻⁸ Pa is required, and a plurality of dedicated ion pumps are used for evacuation of the column. It has a differential exhaust structure that can obtain a vacuum. In the conventional technology, as shown in FIG. 2, since the ion pump is large and the magnetic field is leaked, it is necessary to install it at a certain distance from the column, which makes it difficult to reduce the size. is there. Another problem that arises from this problem is that the ion pump is connected to the electron gun column, so there are large spatial restrictions, for example, it is difficult to mount a coil for increasing the current value by superimposing the magnetic field. There are problems such as.

  Furthermore, since a heavy ion pump is arranged at a high position of the electron optical system column, the position of the center of gravity becomes high, and there is a problem that the image is easily disturbed. In addition, there are cases where the ion pump housing structure is donut-shaped and coaxial with the column, but the diameter of the ion pump housing is at least several tens of centimeters. There is a problem that there is.

Furthermore, with the method using a non-evaporable getter pump, it is difficult to evacuate noble gases such as helium and argon, and electrochemically stable gases such as methane. Since consideration is required, an apparatus such as an SEM that opens to the atmosphere each time a sample is exchanged has not been put into practical use.
Here, the non-evaporable getter pump refers to a vacuum pump configured using an alloy that adsorbs gas only by heating the getter without evaporating it. For adsorption, the gas must have a very small potential or be easily chemically bonded to the getter alloy molecule, but in the case of an electrochemically stable gas such as a rare gas or fluorocarbon, it is completely in equilibrium. There is a problem that it becomes difficult to exhaust.

In order to activate the non-evaporable getter pump, it is necessary to heat at least 350 ° C. However, the heat resistance limit of the coil and wiring forming the electron optical system is about 100 ° C, so that the activation is sufficient. However, since the exhaust speed of the non-evaporable getter pump cannot be obtained sufficiently, there is a problem that the desired high vacuum cannot be reached.
Furthermore, when the electron source is operated, a part of the emitted electrons hits the components of the electron optical system, and a miscellaneous gas is released, which deteriorates the degree of vacuum and consequently shortens the life of the electron gun. There is a problem. In particular, if the electron gun or the electron optical system is downsized and the volume is reduced, the total pressure will rise even if the partial pressure of the above-mentioned rare exhaust gas or other difficult exhaust gas is low. become.

  In summary, the problem to be solved by the present invention is to provide a small charged particle beam apparatus capable of maintaining a high vacuum even while emitting an electron beam. This charged particle beam apparatus includes an FIB apparatus that uses ion particles in addition to an electron beam.

  In the present invention, the electron optical system of the charged particle beam apparatus has a differential pumping structure, a non-evaporable getter pump is disposed in the vacuum chamber on the upstream side, and a minimum ion pump is disposed in the vacuum chamber on the downstream side. This is achieved by using both together. As this ion pump, a sputter ion pump or a noble ion pump having a high rare gas exhaust efficiency is more desirable. The remarkable effect is that the high vacuum maintenance time can be extended significantly.

  A turbo molecular pump may be used instead of the ion pump. Furthermore, another problem is solved by mounting a removable coil or permanent magnet on the electron gun.

By using the present invention, a small charged particle beam device capable of maintaining the degree of vacuum in the column at a high vacuum of the order of 10 ⁻⁸ Pa, for example, a small scanning electron microscope, a focused ion beam device, a charge having a plurality of columns. A particle beam device can be obtained. Moreover, by applying it to a magnetic field superposition type electron gun, it is possible to facilitate downsizing and to greatly extend the high vacuum maintenance time.

Furthermore, a small SEM column for monitoring the probe position of a prober device that directly measures the electrical characteristics of a semiconductor can be easily incorporated.
In addition, it is possible to reduce the size of the electron beam irradiation column of the mirror projection type electron beam inspection apparatus for semiconductor element inspection.

The figure explaining the basic composition of the present invention. The figure explaining the structure of the conventional scanning electron microscope apparatus. The figure explaining the difference of the apparatus size of this invention and a prior art example. The figure explaining the high vacuum holding | maintenance of the electron gun part at the time of a maintenance. The figure explaining the Example which applied this invention to the magnetic field superposition type electron gun. The figure explaining the Example which applied this invention to the prober apparatus. The figure explaining the apparatus side surface at the time of applying this invention to a prober apparatus. The figure explaining the observation image of a probe and a circuit terminal at the time of applying this invention to a prober apparatus. The figure explaining rough alignment at the time of applying this invention to a prober apparatus. The figure explaining the Example which applied this invention to the focused ion beam apparatus. The figure explaining the Example which applied this invention to the microsampling apparatus. The figure explaining the Example which applied this invention to the semiconductor inspection apparatus of the mirror electron microscope system. The figure explaining the structure of this invention applied to the semiconductor inspection apparatus of a mirror electron microscope system. The figure explaining the Example to which the other structure of this invention is applied. The figure explaining the exhaust speed characteristic of a non-evaporable getter pump. The figure explaining the Example which applied this invention to the small magnetic field superimposition electron gun using a permanent magnet. The figure explaining the Example which applied this invention to the small magnetic field superimposition electron gun using a permanent magnet. The figure explaining the other Example which applied this invention to the prober apparatus. The figure explaining the other conventional prober apparatus. The figure explaining the Example which applied this invention to the other prober apparatus. The figure explaining the position of the probe and sample replacement | exchange means of another prober apparatus. The figure explaining the position of the probe of other prober apparatuses, and small SEM.

  FIG. 1 shows an embodiment of the present invention. A thermal field emission electron gun (TFE) is used as the electron source. The electron source 1 is attached to a flange having a diameter of 152 mm, and is connected to an introduction terminal to an electrode (suppressor, drawer, chip) (not shown). The electron source 1 is inserted and fixed in an electron gun column 2. The electron gun column 2 includes a first vacuum chamber 85 and a second vacuum chamber 86 spaced apart from the opening. By doing so, there is a differential evacuation effect by the non-evaporable getter pump, and the ultimate vacuum degree of the first vacuum chamber 85 can be increased (the pressure is decreased). Further, depending on the design, the first vacuum chamber 85 and the second vacuum chamber 86 may be the same vacuum chamber, and a part of the pipe including the valve 16 of the rough exhaust port 14 may be omitted to further reduce the size. . Further, the rough exhaust port 14 of the charged particle beam apparatus according to the present embodiment can be disconnected at the two-dot chain line portion in FIG. 1, that is, outside the valves 15 and 16. For this reason, the two-dot chain line portion in FIG. 1 is provided with a vacuum sealing member such as a flange.

  The electron gun column 2 is provided with a sheet-like non-evaporable getter pump 3 along the inner diameter. The non-evaporable getter pump 3 is activated and sucked by overheating. A heater (not shown) for this purpose is provided outside the electron gun column 2. In this embodiment, a sheathed heater is wound around. A non-evaporable getter pump 5 is also wound around the electrode heater 4. Further, by selecting a sheet-like non-evaporable getter pump 3, a larger surface area can be provided inside the narrow vacuum vessel 2 than a block-like one, so that the pumping speed is increased and the life is extended. There is an effect that can be achieved.

  Although a sheet-like non-evaporable getter pump is used here, a non-evaporable getter material may be vapor-deposited on the heater surface. In this way, the mounting density can be increased and the risk of falling off can be reduced. This is because the non-evaporable getter material is an alloy and has electrical conductivity. Therefore, it can be said that it is particularly effective when applied to an electron gun in which high-voltage parts are mixed.

  There is a thermocouple on the side of the electron gun column, and the heating temperature of the non-evaporable getter pump 3 is monitored. In the present embodiment, the sheet-like non-evaporable getter pump 3 arranged along the inner diameter of the electron gun column 2 was activated at 400 ° C. for 10 minutes. Further, a non-evaporable getter pump 5 disposed around the electrode heater 4 is activated at 550 to 600 ° C. The reason for this is that the non-evaporable getter pump 5 around the heater is activated and adsorbs a large amount of gas when baking is performed for about 8 hours using an electrode heater, as will be described later. It is to make it.

When the electron source 1 emits electrons, a part of the emitted electrons hits a component and releases a gas containing hydrocarbons. When the volume of the electron gun column 2 is small and there is no forced exhaust by the ion pump as in this embodiment, the hydrocarbon gas is difficult to exhaust by the non-evaporable getter pump. There are problems that adversely affect the electron source. Further, there is an electron optical system column 6 on the downstream side of the electron gun column 2, and the coil 38 and electric wiring are included. Therefore, a considerable amount of gas that is difficult to exhaust to the non-evaporable getter pump due to insufficient baking can be expected from the vacuum side wall. In addition, there is an inflow of rare gas such as argon gas from the sample chamber 7 having the lowest degree of vacuum, which causes a reduction in the degree of vacuum in the electron gun column 2. Special attention is required because argon gas is contained in the atmosphere at about 1%. Note that the vacuum in the sample chamber is evacuated by the turbo molecular pump 9 and is usually about 10 ⁻³ Pa.

  In order to solve the problem, the conventional apparatus has a configuration in which each chamber separated through a small-diameter opening is exhausted by a dedicated ion pump (IP-1, 2, 3). As shown in FIG. 3, it can be confirmed that the difference in size from this example is significant. In addition, each ion pump (IP-1, 2, 3) is fixed at a position somewhat away from the column in order to avoid the influence of the magnetic field generated from the pump. .

  Next, details of the present embodiment will be described with reference to FIG. As described above, since high vacuum cannot be maintained by exhausting only the non-evaporable getter pump 3, the present invention is used in combination with an ion pump. This apparatus includes an electron gun chamber (first vacuum chamber 85) having the most upstream electron source 1, an intermediate chamber (second vacuum chamber 86) through an opening, and an electron optical system column 6 through the opening. (Third vacuum chamber 87). Further, the third vacuum chamber 87 is connected to the sample chamber 7 through an opening, and has a differential exhaust structure.

  Non-evaporable getter pumps 3 and 5 are provided in the upstream electron gun chamber and the intermediate chamber, and the ion pump 13 is disposed in the downstream electron optical system column 6 for evacuation. Since the partial pressure of the gas that is difficult to exhaust by the non-evaporable getter pump is extremely small, it has been found through experiments that the ion pump can be exhausted sufficiently even with only one small pump with an exhaust speed of 20 liters / second or less. In particular, use of a sputter ion pump or a noble ion pump with high noble gas pumping efficiency is advantageous because it can be used at a lower pumping speed. As shown in FIG. 3, since it can be significantly reduced as compared with the conventional three units (indicated by broken lines), it is effective in reducing the size of the apparatus. Furthermore, the weight of the upper part of the apparatus can be reduced, and if a heavy ion pump is provided on the lower side as much as possible, the center of gravity is lowered and the vibration characteristics are greatly improved.

  A vacuum starting method in the case of adopting the configuration of this embodiment will be described. All parts facing the vacuum of the electron gun column 2 are cleaned and dried and then assembled. After that, the assembled electron gun column 2 is evacuated and attached to a device different from the device of this embodiment, which can be baked without temperature limitation of 100 ° C. or less, and wound around the electron gun column 2. Using a sheathed heater (not shown), the inside is degassed sufficiently by baking at 300 ° C. for about 8 hours. Thereafter, the atmosphere is released, the electron gun column 2 is removed, the electron gun column 2 is assembled to the electron optical system column 6 of the scanning electron microscope body, and evacuation using the turbo molecular pump 9 is started. At this time, the valves 15, 16, and 17 attached to the roughing port 14 are opened so that the gas in the electron gun column 2 can be exhausted efficiently.

  In this state, baking is performed by energizing a heater wound around the outside of the electron gun column 2 (not shown). At this time, the temperature of the contact surface between the electron gun column 2 and the electron optical system column 6 is set. When the temperature reaches about 80 ° C., it is baked for about 10 hours while controlling the temperature to turn off the heater. Thereafter, a voltage is applied to the electrode heater 4 for baking, and at the same time, the surrounding non-evaporable getter pump 5 is activated. At this time, the target temperature of the heater unit 4 is about 550 ° C. and is maintained for about 1 hour. Thereafter, after naturally cooling to room temperature, the valves 15, 16, and 17 attached to the roughing port 14 are closed, and then the ion pump 13 is energized to exhaust.

With the above procedure, the ultimate vacuum in the electron gun column 2 reached the 10 ⁻⁸ Pa level. Even if the gun valve 8 driven by the air cylinder is driven in this state and the valve is opened to open the sample chamber apart from the opening, the degree of vacuum in the electron gun column 2 can be maintained at 10 ⁻⁸ Pa level. It was confirmed. The degree of vacuum shown by the ion pump 13 was about 5 × 10 ⁻⁶ Pa. It can be said that differential exhaust works effectively, and that the higher the degree of vacuum is, the more upstream it is.

  Next, the control means 501 of the apparatus of this embodiment will be described. The turbo molecular pump 9, ion pump 13, electron source 1, gun valve 8, electron optical system 38, vacuum gauge 90, etc., which are each element of this apparatus, are connected to the control means 501 and can transmit and receive operation and detection signals. , The sequence can be controlled by the processor included in the control means 501. A display 500 can be used to interface with the user and display an SEM image.

Even when 2 kV is applied to the electron source by using the control means to emit electrons and the electron beam is emitted from the electron gun, the degree of vacuum does not vary greatly, and the degree of vacuum in the electron gun column 2 is 10 ^{The -8} Pa level was maintained.

  In addition, the non-evaporable getter pump has a characteristic that the exhaust speed decreases as the adsorption amount increases, but (1) adoption of a differential exhaust structure, (2) combined use with a sputter ion pump, (3) non-sheet-like non-evaporation Due to the increase in the exhaust speed by the evaporation getter pump, the degree of vacuum can be maintained for a long period of about 3 to 4 years without decreasing.

  As another function, a function of notifying the user of the replacement timing of the non-evaporable getter pumps 3 and 5 can be added by monitoring the above-described degree of vacuum. The relationship between the exhaust speed of the non-evaporable getter pump and the elapsed time draws a gentle curve as shown in FIG. 15, so that it is possible to inform the replacement timing of the non-evaporable getter pump with a sufficient margin. As a configuration, a vacuum gauge 90 is provided in the second vacuum chamber 86, data is sent to the control means 501, and when the preset vacuum degree is reached, it is displayed on the user interface such as a display that it is time for replacement. You can do it.

  Further, other effects of the present invention in this embodiment will be described. In FIG. 4, when performing maintenance of the apparatus, it is necessary to avoid leakage of the electron gun unit 2 that maintains the highest degree of vacuum to atmospheric pressure as much as possible and to reduce downtime. Therefore, a gun valve 8 is provided.

  In this embodiment, if this gun valve 8 is closed, the vacuum of the electron gun can be maintained without supplying any energy, and the downstream can be opened to the atmosphere for maintenance. Become. On the other hand, in the conventional case, as shown in FIG. 2, as many as three ion pumps are installed in the electron gun chamber 10, the intermediate chamber 11, and the electron optical system chamber 6, respectively, the weight is 100 kg or more. In order to maintain work and to maintain a high vacuum, it was necessary to continue supplying a high voltage of about 5 kV to each ion pump (IP-1, 2, 3), which had the problem that it was not easy. .

  In this embodiment, as shown in FIG. 4, if the valves 15 and 16 of the roughing port 14 and the gun valve 8 are closed, the electron gun portion can be removed while maintaining a high vacuum state. In addition, the conventional ion pump of the electron gun unit 2 as shown by the broken line in FIG. 3 is eliminated, the weight is reduced to about 15 kg, and it is not necessary to supply a high voltage. There is an unprecedented effect that can be easily maintained by human power.

In the apparatus shown in the conventional example of FIG. 2, the gun valve is provided at a position for opening and closing the opening between the electron optical system chamber 6 and the sample chamber 7. This is because the vacuum chamber exhausted by the ion pump does not want to be exposed to the atmosphere. However, in the present invention, as will be described below, the second vacuum chamber 86 and the third vacuum chamber 87 can be removed while maintaining a high vacuum for a portion of the electron source that is most unlikely to be exposed to the atmosphere. A gun valve 8 is provided between the electron optical system chamber 6.
This is advantageous because the lifetime of the electron source can be kept long, the lifetime of the non-evaporable getter pump can be extended, and the maintainability is improved.

  In this embodiment, an ion pump is used as a pump used in combination with a non-evaporable getter pump. However, a turbo molecular pump may be used instead of the ion pump. However, in the case of a turbo molecular pump, because of the mechanism, the blade that rotates during the evacuation operation vibrates with movement, and thus there is a problem that the SEM image shakes when placed near the electron gun. Therefore, an ion pump or a vacuum evacuation device that mechanically generates less vibration is more preferable as a pump to be used in combination. Although the present embodiment has been described by taking the scanning electron microscope as an example, it is needless to say that the present invention can be applied to a transmission electron microscope, an electron beam drawing apparatus, and various charged particle measures.

  The magnetic field superposed electron gun generates a magnetic field around the electron source 1 to reduce chromatic aberration, spherical aberration, etc. and increase the beam current depending on the design. This is an effective technology that improves measurement accuracy, resolution, and throughput. In other words, by superimposing a magnetic field, the parameters of the electron optical system can be increased and the degree of design freedom can be expanded. In other words, it means that a large current can be emitted with low aberration by using a magnetic field superposition type electron gun. However, there has been a problem that the ion pump, magnetic shield, magnetic field generating coil, etc. are bulky, large and heavy.

  When the present invention is applied to a magnetic field superposition type electron gun, it is possible to easily reduce the size of the electron gun and reduce the size of the electron gun. In this embodiment, an example in which a magnetic field superposition type electron gun is applied to the present invention will be described. FIG. 5 shows a schematic configuration of the present embodiment.

This figure is a cross-sectional view of only the magnetic field superimposing column 18 and the other parts represent the appearance. This apparatus is obtained by converting the electron gun column of FIG. 1 into the magnetic field superimposing column 18 of this embodiment, and other means and functions are the same as those of FIG. The magnetic field superimposing column 18 includes non-evaporable getter pumps 3 and 5 as in the electron gun column, and has no ion pump. The magnetic field superimposing column 18 has a cylindrical shape, and a ring-shaped coil 19 having an inner diameter corresponding to the outer diameter of the column can be attached and detached. The heat-resistant temperature of the coil 19 is at most about 100 ° C. However, by detaching the coil 19, it is possible to reach a heating temperature of about 500 ° C., which is a heating temperature for activating the non-evaporable getter pumps 3, 5. Good.
There is a magnetic path 83 at the position where the coil 19 is placed, and it is used as a component for guiding the magnetic field generated from the coil to the vicinity of the electron source 1.

  The start-up method of the present embodiment is almost the same as that of the first embodiment, but the coil 19 is removed at the beginning of the start-up, attached after the vacuum is started up, and an electron beam is emitted to adjust the coil. Just do it.

With the configuration described above, conventionally, the coil had to be enlarged in order to avoid the ion pump, and attachment / detachment of heavy objects at the time of maintenance reduced usability, but maintenance was simple and easy. Can be obtained.
Although the present embodiment has been described by taking a scanning electron microscope as an example, it is needless to say that the present invention can be applied to an electron beam drawing apparatus and various charged particle measures.

  In this embodiment, an application example to an SEM type prober will be described. The principle configuration of the SEM type prober is described in Japanese Patent Laid-Open No. 09-326425, and has a configuration in which a plurality of probes are directly brought into contact with semiconductor circuit terminals to measure current and voltage characteristics. Since the dimension of the circuit pattern is on the order of nanometers, the typical dimension of the probe is about 50 nm in radius, and the tip that contacts the circuit terminal is sharply pointed to the order of nanometers. Therefore, there is a problem that both the probe and the circuit terminal are damaged if the probe is in contact with the circuit terminal too much and a slight excessive pressure is applied to the probe. Further, in order to avoid the risk of damage to the probe, if the probe is brought close to the target slowly, there is a problem that it takes too much time for the probe to contact the circuit terminal.

  Therefore, in the conventional SEM type prober apparatus, the probe and the circuit terminal are roughly aligned using an optical microscope in advance. After that, the probe is driven in the Z direction so as to be close to the circuit terminal. At this time, using a signal such as a tunnel current or adjusting while observing the observation image of the SEM, the probe and the circuit terminal are adjusted. A collision was avoided. In addition, for precise relative positioning between the probe and the circuit terminal, the position was determined while viewing the image of the scanning electron microscope, but there was no information in the Z direction.

  The SEM prober apparatus of this embodiment is characterized in that a small electron optical column is used and two scanning electron microscopes are provided so that an image including information in the Z direction can be acquired. By looking at the same field of view from different angles, that is, by giving the angle (viewing angle) formed by the two columns, the position of the circuit terminal in the sample surface and the positional relationship of the probe and from the circuit terminal to the probe It is possible to acquire an image including information in the Z direction such as the height of the.

  FIG. 6 is a conceptual diagram showing the configuration of the prober apparatus of this embodiment. A stage 23 on which the sample 52 is placed is provided in a vacuum container evacuated by the turbo molecular pump 28. This stage can be moved and positioned along the trajectories 24, 25 in two directions (X, Y). On the stage 23, a sample 52 is placed, and probes 20 and 21 and probe stages 26 and 27 that contact the circuit terminals 22 on the sample surface are installed. The probe stages 26 and 27 have a configuration that enables precise positioning of the probe with respect to three axes in the X, Y, and Z directions. In this embodiment, the number of probes 20 and 21 is two, but the number is not particularly limited, and may be four, for example.

  A pair of SEM columns 53 are arranged on the top of the vacuum vessel. The pair of SEM columns is disposed at a desired position with an angle with respect to the sample 52, and is disposed obliquely with respect to the normal direction of the observation sample surface. Electron optical systems 32 and 33 are provided inside the SEM column 53, and the sample can be irradiated with an electron beam. The electron beam 36 emitted from the field emission electron guns 30 and 31 in the electron optical systems 32 and 33 is formed between the electrodes of the electrostatic lens composed of a plurality of lens electrodes provided below the electron beam 36. The sample is focused by the applied electric field, and is focused finely and irradiated onto the sample. At the same time, the electron beam 36 is scanned two-dimensionally on the sample. Secondary electrons generated from the sample by irradiation with the electron beam 36 reach the secondary electron detector and are detected. Although not shown, the secondary electron detector is disposed inside the SEM column 53. From this detection signal, a two-dimensional secondary electron image of the sample surface is obtained. This embodiment is intended for observation at a low acceleration voltage that can reduce charging and damage of the sample surface due to irradiation of the electron beam 36 so as to be suitable for applications such as semiconductor surface observation. The acceleration voltage Va of 36 is set to 3 kV or less (mainly around 1 kV). In the present embodiment, an electrostatic optical system is employed as the electron optical systems 32 and 33 provided in the SEM column from the viewpoint of easy miniaturization. Since the electron optical system is composed of only the electrostatic lens, the electron optical column is very small with an outer diameter of 34 mm and a height of 150 mm. At the same time, a high resolution of 6 nm was achieved with an acceleration voltage of 1 kV. In the present embodiment, the secondary electron detector is arranged inside the SEM column 53, but may be provided outside the SEM column.

  Each element described above is connected by a control means 502 signal line, and transmits and receives an operation control signal. The signals of the SEM images of the two sets of SEM monitors 53 installed in this embodiment are also sent to the control means 502 through this signal line, and are synthesized on a stereogram stereoscopic image and then displayed on the display 503. The obtained image signal can also be stored in a recording unit included in the control unit 502.

  Further, above the stage 23, there is an optical microscope 51-1 for coarse alignment of the probe and circuit terminals. This optical microscope 51-1 is located immediately above the sample, and is used for coarse alignment of the probe and circuit terminals in the X and Y planes.

  FIG. 7 shows a side view of the prober device shown in FIG. As can be seen from this side view, the prober apparatus of the present embodiment also includes an optical microscope 51-2 for coarse alignment in the Z direction in addition to the optical microscope 51-1 for coarse alignment in the X and Y plane directions. ing. The SEM column 53 is assembled to the vacuum container so as to be inclined at a predetermined angle with respect to the normal line direction of the sample 52 or the optical axis direction of the coarse alignment optical microscope 51-1.

  Next, the operation procedure of the prober apparatus of this embodiment will be described with reference to FIG. After loading the sample 52 into the apparatus and evacuating it, the stage is moved under the optical microscope 51-1, and coarse alignment is performed. Thereafter, as shown in FIG. 6, the stage is moved to the irradiation position of the electron beam 36, and the probes 20, 21 and the circuit terminal 22 are precisely aligned. That is, while observing the image data of the two scanning electron microscopes, the positions of the probes 20 and 21 and the circuit terminal 22 are determined, brought close to each other, and stopped immediately before. In order to observe the relative positional relationship between the probe and the circuit terminal, manual operation may be performed, or automatic control may be performed based on image data. Thereafter, contact may be made based on the measurement and observation results of the tunnel current and SEM image. Thereafter, the sample stage 23 and the probe stages 26 and 27 are driven and positioned so that the probes 20 and 21 are placed in the field of view of the two sets of scanning electron microscopes 32 and 33.

  In FIG. 9, the schematic diagram of the SEM image which can be acquired with the prober apparatus of a present Example was shown. In the conventional prober apparatus, only the SEM image corresponding to the top view of the sample could be obtained. However, in the prober apparatus of the present embodiment, as shown in FIG. 9, three-dimensional position image information with depth can be acquired. . As a result, the positioning of the probes 20 and 21 and the circuit terminal 22 becomes much easier, and the probability of damage to the probe or sample due to excessive contact is reduced. Furthermore, the contact time of the probe can be shortened. By using data obtained from the two SEM columns, even if one of them fails, inspection can be performed without damaging the probe or sample. Although it is possible to reduce the probability of damage to the probe or the sample only by the information obtained from the image shown in FIG. 9, the circuit is based on the tunnel current value obtained from the probes 20 and 21. If the contact between the terminal and the probe can be confirmed, the convenience of the device user is further improved.

  The apparatus configuration described above can be realized without necessarily using a differential pumping structure. However, in order to maintain the degree of vacuum around the electron gun in the SEM column, a plurality of ion pumps are used as shown in FIG. Need to use. However, when the differential pumping structure described in the first and second embodiments is applied, the configuration of the vacuum pumping system is simplified, and there are many advantages in the device design.

  Hereinafter, the configuration of the vacuum exhaust system of the prober apparatus to which the differential exhaust structure is applied will be described with reference to FIG. An opening plate 37 is provided inside the SEM column 53 and is divided into two vacuum chambers having different degrees of vacuum. One is a first vacuum chamber (electron gun chamber) in which the electron guns 30 and 31 are stored, and the other is a second vacuum chamber in which the electron optical systems 32 and 33 are stored. The sample chamber provided below the SEM column 53 is evacuated by the turbo molecular pump 28, the second vacuum chamber is evacuated by the ion pump 29, and the uppermost electron gun chamber is evacuated by the non-evaporating getter pumps 34 and 35. Is done. This makes it possible to maintain a high degree of vacuum in the electron gun chamber with a smaller number of ion pumps than in the conventional structure shown in FIG.

  Furthermore, in the prober apparatus of the present embodiment, one ion pump is shared by two SEM columns, thereby achieving high efficiency and space saving. Furthermore, if the ion pump is a sputter ion pump or a noble ion pump, the non-evaporable getter pump is more efficient in exhausting rare gases that are difficult to exhaust, which is advantageous in maintaining the degree of vacuum.

  As described above, since the conventional small scanning electron microscope requires a plurality of ion pumps, it is not practical to arrange two sets of monitoring scanning electron microscopes. An apparatus having a configuration capable of acquiring a stereoscopic image can be realized in a smaller space than in the past. In this embodiment, an example in which a circuit terminal is inspected as an inspection object of a prober device has been described. However, the present invention is not limited to a circuit terminal, and a general electronic circuit such as a wiring portion of a circuit, an electrode, or a memory cell is inspected. It goes without saying that things can be done. In addition, as a sample containing the inspection object, a semiconductor wafer, a chip or a sample substrate on which a circuit pattern is formed, a sample piece obtained by cleaving a sample substrate, and the like can be used.

  An embodiment in which the present invention is applied to a column of a focused ion beam (FIB) apparatus will be described with reference to FIG. The FIB apparatus is an apparatus that applies ion particles heavier than electrons to the sample 49 to process the surface of the sample, or detects electrons generated from a portion irradiated with an ion beam and observes an image in the same manner as the SEM.

Also in the FIB apparatus, in the conventional apparatus, as shown in FIG. Therefore, if the present invention is applied, the periphery of the FIB column can be easily downsized as in the first embodiment.
Since an electrostatic optical system comprising a plurality of electrodes 40, 41, 42, 43, 44 is used for the optical system for focusing the ion beam 50, an electromagnetic lens using a coil such as an SEM is not used. For this reason, since heat resistance is higher than that of SEM, the non-evaporable getter pumps 45 and 46 are easily introduced.

The ion source 39 of the FIB apparatus is disposed on the most upstream side and needs to maintain a degree of vacuum of about 10 ⁻⁸ Pa. For this reason, a differential exhaust structure is adopted as in the SEM described in the first embodiment. In the case of FIG. 10, two-stage differential exhaust is performed, and conventionally two ion pumps have been used. By changing one ion pump indicated by the broken line on the upstream side to the non-evaporable getter pump 45, the size and weight can be reduced. Furthermore, if the ion pump is a sputter ion pump, the exhaust efficiency of the rare gas, which is difficult to exhaust by the non-evaporable getter pump, is increased, which is desirable because the size can be further reduced.

  In addition, since the ion beam is focused by the electrostatic optical system as described above, the non-evaporable getter pump 46 can be disposed also in the column portion exhausted by the ion pump. For this reason, there is an effect that the exhaust speed can be increased.

  Note that the vacuum in the sample chamber in which the sample 49 is placed is exhausted by the turbo molecular pump 47. Each of the above-described elements is connected to the control means 504 through a signal line, can transmit / receive control signals and image data, and can manage the sequence of the entire apparatus. A display 505 can be used for user interface and image display.

  Since the other structure is the same as that of the conventional FIB, detailed description will not be given here, but it can be introduced into apparatuses other than the electron beam.

In this embodiment, an example in which the present invention is applied to a microsampling apparatus will be described with reference to FIG.
A micro-sampling device is a device that cuts out a part of a device for inspection and analysis of a semiconductor device, etc., and observes and analyzes the cross section. The FIB column 77 for enabling sample cutting and the cutting position and cut-out cross section are simultaneously displayed. This is an apparatus in which two types of columns of the SEM column 78 for observation are provided at an angle to each other. Furthermore, it has a predetermined angle with respect to the vertical axis 81 with respect to the surface of the sample 60 coinciding with the horizontal plane. For this reason, the two columns are attached close to each other at an angle. Because of this configuration, multiple ion pumps that are conventionally mounted on each column interfere with each other, or the center of gravity increases due to the weight of the ion pump, making the entire column easy to vibrate. was there.

  Since the present invention is applied to the microsampling apparatus of this embodiment, only one ion pump is used for both the FIB and SEM columns. For this reason, the weight can be drastically reduced compared with 2 to 3 units per column which is a conventional configuration. Furthermore, if the ion pump is a sputter ion pump or a noble ion pump, the exhaust efficiency of the rare gas that is difficult to exhaust by the non-evaporable getter pump is improved, so it is desirable to further reduce the size. In this embodiment, separate ion pumps are provided for the FIB column and the SEM column, but one ion pump may be used in combination.

  In the most upstream vacuum chamber of the FIB column 77, there is an ion source 61, and a non-evaporable getter pump 79 is installed. Further, a non-evaporable getter pump 80 is also provided in the vacuum chamber on the downstream side across the opening of the electrostatic optical system 63, and the vacuum chamber further separated in the opening 64 is exhausted by the ion pump 69. The ion beam radiated from the ion source 61 is narrowed to a desired position on the sample surface, and a predetermined removal process can be performed.

  The present invention is applied to the SEM column 78 as well as the FIB column. In the most upstream vacuum chamber, there is an electron source 62 and a non-evaporable getter pump 81 is installed. There is also a non-evaporable getter pump 82 in the vacuum chamber on the downstream side across the opening 66, and the downstream vacuum chamber is exhausted by the ion pump 70. This vacuum chamber has an electromagnetic optical system using coils, and its heat resistance is low, so a non-evaporable getter pump cannot be installed. This configuration is the same as the SEM column described in the first embodiment. The electron beam emitted from the electron source 62 is focused on the surface of the sample 60, generates secondary electrons, and the secondary electrons are detected by the secondary electron detector 76, so that the SEM image is being processed by the ion beam. Alternatively, it can be obtained before or after processing.

  The central axis 84 of the FIB column 77 is inclined and fixed with an angle Θ formed with respect to the vertical axis 81 being 30 °. Further, the central axis 80 of the SEM column 78 is inclined 45 ° with respect to the vertical axis 81. Further, the relative angle between the FIB column and the SEM column is fixed at 90 °.

  There is a sample chamber below the two columns described above, and the sample is evacuated by the turbo molecular pump 83. Further, there are a stage 71 on which the sample 60 can be placed and moved and positioned, arms 72 and 73 for microsampling, and driving means 74 and 75 for driving them. These microsampling means are means for handling a fine chip processed by an ion beam.

  Each element described above is connected to the control means 506 via a signal line, and can transmit and receive control signals and image data. A display 507 can be used for user interface and image display.

  In this embodiment, an example applied to a sample inspection apparatus of a mirror electron microscope (mirror projection method) will be described. Examples of the observation sample include a semiconductor wafer, a chip or a sample substrate on which a circuit pattern is formed, or a sample piece obtained by cleaving the sample substrate and taking out a part thereof. Mirror projection is a method of detecting an image by imaging an electron beam (mirror electron) reflected before reaching the sample surface by the potential distribution on the sample surface. This is different from the ordinary SEM method for detecting secondary electrons generated from the irradiated sample and detecting the intensity of reflected electrons.

  The feature of the mirror projection method is not a single stroke of an electron beam, but an image like an optical microscope can be obtained by illuminating an area of about 100 to 400 μm square with electrons. The point is that it can be shortened.

  However, unlike the conventional SEM, this mirror projection method does not directly image the shape of the sample surface because an image depending on the potential distribution on the sample surface is obtained. Therefore, if the surface shape of the region detected by mirror projection can be detected as an image, it can be used as a reference image for the mirror projection detection image, which is convenient for defect detection. For this purpose, an application that makes it possible to observe an enlarged SEM image of a part that appears to be abnormal by using another electron optical system is effective.

  In this embodiment, a small SEM column 114 is provided beside the mirror projection column 120 as shown in FIG. The distance between the two columns is accurately measured in advance, and the sample stage 106 on which the sample (wafer) 105 is placed is configured to be able to move between the two columns as necessary as indicated by the broken line. .

  Next, the configuration of this apparatus and the procedure for inspecting the surface of the wafer 105 will be described. In the electron beam illumination optical system column 101, the electron beam emitted from the electron source 100 is focused by the magnetic field superimposing coil 121 to emit a beam with a large current. This increase in current has an important effect on improving inspection throughput. This is because the signal-to-noise ratio (S / N ratio) of the mirror electron signal obtained from one large area irradiation increases and decreases in proportion to the current of the electron beam to be illuminated.

This magnetic field superposition type electron gun may be the same as that described in the second embodiment. That is, it has a differential evacuation structure with openings separated, and the electron source 100 is in the uppermost vacuum chamber and is evacuated by the non-evaporable getter pump 123. In the vacuum chamber on the downstream side, a condenser lens 102 is exhausted by an ion pump 122. With this structure, the vacuum chamber in which the electron source 100 is located is maintained at an extremely high vacuum of 10 ⁻⁸ Pa level. Further, a magnetic field superimposing coil 121 is attached to the atmosphere side so as to be detachable from the electron beam illumination optical system column 101. By adopting such a structure, the number of ion pumps installed in the electron beam illumination optical system column 101 can be reduced to one, so that the weight can be reduced and the vibration characteristics of the entire apparatus are improved. Furthermore, if the ion pump is a sputter ion pump, the exhaust efficiency of the rare gas, which is difficult to exhaust by the non-evaporable getter pump, is increased, which is desirable because the size can be further reduced.

  The electron beam emitted from the magnetic field superposition type electron gun is focused by the condenser lens 102 and irradiated on the sample almost in parallel. As the electron source 100, a Zr / O / W type Schottky electron source was used. A uniform planar electron beam having a large current beam (for example, 1.5 μA) and an energy width of 1.5 eV can be stably formed.

  An E × B deflector 103 is disposed as a separator in the vicinity of the imaging surface 304 of the imaging electron beam 302. In this arrangement, the E × B deflector generates aberration with respect to the irradiation electron beam 301. In order to correct this aberration, another aberration correcting E × B deflector 104 is arranged between the irradiation system condenser lens 102 and the E × B deflector 103.

  The electron beam is deflected to an optical axis perpendicular to the wafer 105 by the E × B deflector 103. The E × B deflector 103 has a deflecting action only on the electron beam from above. The electron beam deflected by the E × B deflector 103 is formed into a planar electron beam in a direction perpendicular to the sample (wafer) surface by the objective lens 107. Since the deflection aberration of the separator E × B deflector 103 is corrected by the E × B deflector 104, a fine crossover is formed on the focal plane of the objective lens 107. Can be irradiated to the sample.

  A negative potential slightly equal to or slightly higher than the acceleration voltage of the electron beam is applied to the sample (wafer) 105 mounted on the sample stage 106 in the vacuum sample chamber 108 by a sample application power source (not shown). , An electric field reflecting the shape of the formed semiconductor pattern and the state of charging is formed on the surface of the wafer 105. By this electric field, most of the planar electron beam is pulled back immediately before it collides with the wafer 105, and rises with a direction and intensity reflecting the pattern information of the wafer 105.

  The retracted electron beam is focused by the objective lens 107, and the deflector 103 as a beam separator has no deflection effect on the electron beam traveling from below, so it rises vertically as it is, and the objective lens 107 The image is magnified by the intermediate lens 109 and the projection lens 110, and an image of the surface of the wafer 105 is formed on the image detection unit including the scintillator 111, the optical lens 112, and the CCD 113.

  On the other hand, there is a small SEM column 114 beside the mirror projection column 120, and the pattern shape on the wafer 105 can be observed. As the electron source 115, a Schottky electron source is used. The emitted electron beam 121 can scan the wafer surface by the electrostatic optical system 117 and detect secondary electrons or reflected electrons to obtain an SEM image.

The SEM column 114 is evacuated from the electrostatic optical system 117 by a small ion pump 118 having a pumping speed of about 10 liters / second, and differentially pumped by a non-evaporable getter pump 116 on the upstream side. With this configuration, the degree of vacuum in the vicinity of the most upstream electron source 115 is about 10 ⁻⁸ Pa. The sample chamber 108 is evacuated by a turbo molecular pump 119, and a vacuum degree of 10 ⁻³ Pa is obtained.

FIG. 13 shows a detailed configuration of the small SEM column 114. The sample chamber 108 and the small SEM column 114 are connected via a bellows 201, and can be positioned by using the driving means 202 along the optical axis direction of the SEM. In this way, the focus of the SEM optical system 117 can be adjusted, and the SEM observation visual field can be enlarged or reduced, or the resolution can be selected. That is, if the distance (working distance) from the observation surface of the sample 105 is wide, the field of view is widened but the resolution is reduced. If the working distance is narrowed, the field of view is reduced, but the resolution is improved. It is a very effective function because it can be adjusted freely according to the object to be observed. The working distance is measured using a position detector (not shown). The relationship between the optical performance and the working distance of the small SEM is stored in a database in advance and is automatically adjusted. Further, fine adjustment is possible while viewing the SEM image.

Each element described above is connected to the control means 508 via a signal line. The control unit 508 is a control unit that manages the operation of the entire apparatus, a signal interface that transmits and receives control signals and image data, an image processing unit that analyzes detected image signals and detects defects, and the mirror projection column 120. A data storage unit that stores information on the distance to the small SEM column 114, the above-described database, and the like, a data processing processor that processes information stored in the data storage unit, a control computer that controls the operation of the entire apparatus, and the like. In the present embodiment, the configuration in which all the control units are arranged in the control unit 508 is shown, but each component may be arranged as a separate control unit. Although the display 509 is detected image is displayed, it is also used as a user interface when using GUI (G raphical U ser I nterface ).

  By using the apparatus configuration described above, a change in local charging potential on the surface of the wafer 105 and a difference in structure such as unevenness are formed as an image. By correcting the aberration, it is possible to irradiate the irradiation electron beam 301 with good parallelism and form a high-resolution mirror image, so that a change in charging potential of 100 nm or less and a difference in structure such as irregularities can be detected. Is possible.

  The detected image data is processed by the image processing unit, and when it is determined as a defect, it is stored in the coordinate data storage unit. When it is desired to observe the surface shape of the defect image position, the apparatus operator transmits a command for displaying the corresponding SEM image to the control means 508 via the GUI displayed on the display 509. The data processor in the control unit 508 refers to the data storage unit based on the signal input via the GUI, and acquires the coordinates of the position where SEM observation is possible. Thereafter, a control signal for moving to the acquisition coordinates is transmitted to the sample stage 106. After moving to a desired position, an SEM image of the defect position obtained from the mirror image is acquired, and necessary data such as the presence / absence of defect, shape, and dimension are stored in the data storage unit.

  Thereafter, the specimen stage is driven to return to the original coordinate position where the mirror projection observation is possible, the inspection is continued, and the inspection is completed by repeating until the entire wafer surface is inspected. The procedure up to this point is that the inspection by mirror projection is first, and the defect found is confirmed by SEM image later, but conversely, the defect coordinates obtained from SEM observation are stored and the mirror image is observed later. May be. Alternatively, the SEM image may be acquired after the entire surface of the sample is inspected by mirror projection.

  As described above, the mirror projection electron microscope apparatus of this embodiment has two types of mirror electron column and normal SEM or reflection electron column, and detects two types of mirror electron image and SEM image or reflection image. Is possible. Therefore, the SEM image or the reflected electronic image can be used as a reference image for the mirror electronic image, and the convenience of the apparatus user is significantly improved. This effect can be realized without applying a differential pumping structure to each electron optical system column.

  Furthermore, when the differential pumping structure is applied to either a mirror electron column or a normal SEM or a reflection electron column, the apparatus size can be reduced. Therefore, it is possible to realize a mirror projection type sample inspection apparatus capable of easily observing an SEM image of a defective portion without increasing the size of the entire apparatus.

  In the present embodiment, other aspects of the present invention will be described with reference to FIG. In addition to the non-evaporable getter pump 3 and the ion pump 88, the first vacuum chamber 85 in the configuration of the scanning electron microscope of the present invention described in the first embodiment is evacuated in combination with the evacuation. .

Conventionally, when the cold cathode electron source (cold FE) 89 is used, if the ultimate vacuum is lowered to the 10 ⁻⁷ Pa level, contaminants adhere to the electron source and the electron emission characteristics are deteriorated or the life is shortened. There was a problem to do. For this reason, it is necessary to perform flushing once every several months to six months. Flushing is a method in which a contamination film attached to the tip of an electron source is heated by passing a filament current and cleaned. As a result, an electron beam with high brightness can be obtained again, but the beam emission position at the tip of the electron source changes, and it becomes necessary to readjust the electron optical system. In order to solve these problems, it is necessary to keep the ultimate vacuum of the vacuum chamber 85 in which the electron source 89 is installed high.

In the method described in the first embodiment, the degree of vacuum in the first vacuum chamber with the electron source is on the order of 10 ⁻⁸ Pa, but in the method of this example, the degree of vacuum on the order of 10 ⁻⁹ Pa is achieved. it can. The reason for this is that the non-evaporable getter pump 3 exhausts most of the gas other than the difficult exhaust gas such as argon, and the ion pump 88 can remove the slightly remaining difficult exhaust gas. Therefore, as the ion pump 88, a sputter ion pump, a noble ion pump, or the like is suitable as described in the first embodiment, and the pumping speed may be as small as 20 liters / second or less.

  Each of the above-described elements is connected to the control means 510 via a signal line, can transmit and receive control signals and image data, and can manage the operation of the entire apparatus. In addition, a display 511 can be used for an interface with a user and display of an image.

  In the case of this embodiment, a vacuum gauge for monitoring the lifetime of the non-evaporable getter pumps 3 and 5 is not necessary, and the voltage applied to the ion pump 88 may be monitored to know the degree of vacuum. Data indicating the degree of vacuum of the ion pump 88 may be sent to the control means 510, and when the preset degree of vacuum is reached, the fact that it is time for replacement may be displayed on the user interface of the display 511.

  As described above, when the ion pump 88 is provided in the first vacuum chamber 85 and used together with the non-evaporable getter pump 3, the degree of vacuum around the electron source 89 is dramatically increased. Therefore, a cold cathode electron source is used. In this case, maintenance such as flushing, which was necessary in some cases, is unnecessary, and it is possible to obtain a great effect that the cold cathode electron source 89 can be used for 3 to 4 years.

  In this embodiment, an example in which the present invention is applied to a small magnetic field superposition type electron gun will be described. First, a magnetic field superposition type electron gun will be described. A magnetic field superposition type electron gun includes a magnetic field superposition electron source in which an electron source is immersed in a magnetic field, means for applying an electric field for extracting an electron beam from the electron source, and for applying a magnetic flux to the electron source. The electron gun includes an upper magnetic pole and a lower magnetic pole that also serve as means, and operates to provide a potential difference that generates an electric field between the upper magnetic pole and the lower magnetic pole.

FIG. 16A shows a cross-sectional view around the electron source of the small magnetic field superposing electron gun of this embodiment. In FIG. 16, an electric field for extracting electrons to the electron source 413 is generated by the potential difference V _{1 applied} to the upper magnetic pole 401 and the lower magnetic pole 402. Further, by using both the upper and lower magnetic poles and the means for applying the extraction electric field (extraction electrode), the aberration of the entire small magnetic field superposed electron gun 415 can be reduced. This is because a strong magnetic field is obtained in a narrow region by generating the magnetic field with the component closest to the electron source, that is, the extraction electrode. As a result, an electron lens with a short focal length is formed in the vicinity of the electron gun. Because. This is based on the fact that aberrations tend to decrease as the focal length is shortened electro-optically.

  In this embodiment, a permanent magnet is used as a magnetic field generation source without using an electromagnetic coil, and a carbon nanotube is used as an electron source. As a magnetic field generation source, it is preferable to use a permanent magnet 411 disposed in the same vacuum vessel as the electron source. Although it is possible to use a coil as the magnetic flux generation source, if a permanent magnet is used, the volume is extremely small to generate a magnetic flux of about 0.8 to 1.1 T (Tesla), which is practical as an electron lens. There is an advantage that. In order to apply a magnetic field to the electron source 413, the electron source and the magnetic field generating source are connected directly or via a magnetic pole made of a soft magnetic material. The shape of the permanent magnet 411 is generally axisymmetric with the electron emission direction viewed from the tip of the electron source as the central axis. As a result, the magnetic polarization becomes axially symmetric as in the central axis direction or radial direction, and an axial target magnetic field ideal as a low aberration electron lens can be obtained.

  The potential applied to the permanent magnet or the magnetic pole is the same as that of the electron source or the same as that of the extraction electrode. For this reason, it is possible to form magnetic poles and magnets that generate a magnetic field and electrodes that generate an electric field for extracting electrons in the same small space, so that a strong magnetic field can be obtained in a narrow region.

  The electron source 413 combined with the above-described electron gun 415 is preferably a light source having a virtual light source diameter as small as possible. In particular, when used in combination with a field emission electron source having a physical diameter at the tip of the electron source of 100 nm or less, aberrations Thus, the feature of the present invention, which is small, can be fully utilized, and an electron gun with higher performance than before can be realized.

  The configuration shown in FIG. 16 (a) will be described more specifically. A rod-like permanent magnet 411 is disposed on the optical axis of the electron source, and the magnetic field generated on the end face of a thin rod-like magnet magnetized in the longitudinal direction is used to reduce the aberration of the electron gun, thereby increasing the brightness. Has been achieved. The lower magnetic pole 402 is fixed to the insulator 407 with a bolt 408, and the base magnetic pole 403 and the insulator 405 are sandwiched and fixed therebetween. This lower magnetic pole also serves as an extraction electrode. The permanent magnet 411 is fixed together with the upper magnetic pole 401 in the magnet holder 410 by a magnet holder 404. This magnet retainer has a screw formed on the outer periphery, and meshes with the female screw of the base magnetic pole 403. The magnet holder 410 is fixed to the base magnetic pole 403 by a countersunk screw 409. In this case, since there is no conventionally used coil or magnet on the side wall of the lower magnetic pole 402, an opening can be provided as shown in FIG. A non-evaporable getter 412 is disposed on the inner wall side of the side wall provided with the opening, and a heater 414 is wound outside the side wall. The non-evaporable getter is activated by energization heating of the heater to act as a vacuum pump. By providing an opening on the side wall 402, the evacuation conductance is increased, and there is an advantage that the surroundings of the electron source 413 can be kept in a good state with few gas molecules for a long time.

  Although an example using carbon nanotubes as an electron source has been described, other electron sources may be used as long as the light source diameter or virtual light source diameter of the electron emission source is about 3 nm or less. For example, a W needle having a tip diameter of 100 nm or less or a nanotip formed on the tip has the same effect because the light source diameter is small. A nanotip is formed by forming a protrusion of several atoms at the tip of a needle by applying a positive voltage while heating the W-FE needle to achieve field evaporation conditions. In addition to W, refractory metals such as Pt and Mo may be used.

When the electron source 413 is operated, the extraction voltage V ₁ is practically in the range of 100 V to 4 kV when the electron source is a carbon nanotube, and in the range of 2 kV to 5 kV when the tip diameter is 100 nm with a W needle. Thus, while observing the emission current _Ie from the electron source, it is determined so that _Ie becomes a desired value. This I _e is practically selected from the range of 10 nA to 500 μA for carbon nanotubes and from 10 nA to 30 μA for W needles. The upper magnetic pole 401 is at the same potential as the electron source 413, the acceleration voltage _{V 0} is applied. Practically, V ₀ is selected from the range of −30 kV to −30 V for SEM (scanning electron microscope) and from the range of −30 kV to −1000 kV for TEM (transmission electron microscope).

  As explained above, a magnetic field superposition type electron gun is realized by using an electron source tip of 100 nm or less and using a permanent magnet. it can.

  Next, the overall configuration of the small magnetic field superposition type electron gun of this embodiment will be described with reference to FIG. The first vacuum chamber 421 at the uppermost stream has the above-described small magnetic field superposition type electron gun 415. A non-evaporable getter pump 416 is provided on the inner wall of the first vacuum chamber and can be activated by a heater (not shown). The first vacuum chamber is connected to the second vacuum chamber 422 through an anode electrode 406 having an opening through which an electron beam passes. A non-evaporable getter pump 417 is also provided on the inner wall of the second vacuum chamber, and is activated by being heated by a heater (not shown).

  An opening is provided on the downstream side of the second vacuum chamber and is connected to the third vacuum chamber 423. This opening can be opened and closed by a gun valve 418. During maintenance, the gun valve is closed, and the second vacuum chamber and the third vacuum chamber can be separated while maintaining a region where the electron gun 415 is kept at a high vacuum. .

  The third vacuum chamber has an electron optical system including a coil 420 and is evacuated by an ion pump 419. There is also an opening on the downstream side of the third vacuum chamber, which is further connected to the vacuum chamber on the downstream side.

  By adopting the configuration described above, a magnetic field superposition type electron gun having no coil on the atmosphere side and small in size and light in aberrations can be obtained.

  In the present embodiment, as in the fourth embodiment, another example in which the present invention is applied to a prober apparatus will be described with reference to FIG.

  In Example 4, the SEM column 53 for monitoring was installed obliquely with respect to the sample to obtain a stereogram image. On the other hand, in this embodiment, one of the monitoring SEM columns 53 was placed directly on the sample 52, and the other column was placed so that the optical axis was placed on the surface of the sample. Each column can be adjusted and focused by a driving means (not shown).

  With the above arrangement, the sample 52 is moved to the observation position of the SEM column 53 after coarse alignment of the probe and the circuit terminal by an optical microscope not shown in FIG. Using the SEM image, the in-plane alignment can be performed from the SEM image directly above the sample, and the relative height distance between the probe and the circuit terminal can be observed from the other SEM image. As a result, the contact operation can be performed quickly without damaging the short hand and the circuit terminal.

  The vacuum pumping by the ion pump 29 of the SEM column 53 according to the present invention can be shared by the same ion pump 29.

  Other apparatus configurations and procedures may be performed in the same manner as those shown in the fourth embodiment.

  In the present embodiment, another configuration example of the prober device will be described. In the conventional SEM type prober described in Japanese Patent Application Laid-Open No. 09-326425, when the probe is brought into contact with the sample, information in the Z direction of the probe cannot be obtained from the SEM image. There is a problem that it takes too much time to complete contact with the test piece, or the sample and the probe are easily damaged by accidentally bringing the probe too close to the sample.

  The prober apparatus of the present embodiment employs a configuration in which a small SEM column is disposed directly beside or obliquely with respect to the column of the main electron optical system apparatus. With this configuration, an SEM type prober device that can acquire the position information of the probe in the Z direction is realized, and the above-described problems can be solved. For this reason, the vacuum sample chamber housing for holding the main electron optical system apparatus is provided with a vacuum introduction mechanism for introducing a small SEM column.

  First, the basic configuration and function of the prober 901 will be described. FIG. 19 shows the overall configuration of the prober 901 of this embodiment. In FIG. 19, a prober 901 includes a stage including a sample holder 902 for holding a sample in a sample chamber 907 and a sample holder receiver 917 for holding the sample, and a probe stage 906 including a probe unit 933. Here, although the sample is fixed to the sample holder 902, it is a thin piece and is not shown in FIG. 19 for the convenience of drawing. A first electron optical system device 904 (referred to as a charged particle device) having an ion pump 944 such as a scanning electron microscope (SEM) or a focused ion beam (FIB) device facing a sample holder 902 for inspection of a sample. Is provided in the housing of the sample chamber 907. Although not shown in FIG. 19, the second electron optical system device is disposed on the opposite side of the first electron optical system device 904 from the paper surface. In addition, a probe rough approach image acquisition device 910 is provided in the vicinity of the first electron optical system device 904. A charged particle beam (electron or ion beam) for observing the movement of the surface of the sample or the probe (probe) 903 is irradiated from the first electron optical system device 904 toward the sample holder 902.

  A probe rough approach image acquisition device 910, which is arranged in parallel with the first electron optical system device 904 on the upper surface of the housing of the sample chamber 907, includes a probe rough approach optical microscope (light microscope) and a CCD for image acquisition. A rough camera state of the probe 903 with respect to the sample, and can be acquired as image information. Further, as the probe rough alignment image acquisition device 910, not only the vertical one 910A but also a horizontal arrangement 910B arranged in a cross shape is used. With this cross-shaped arrangement, the probe 903 can be observed from above and from the side, and the rough approach state can be reliably grasped. At this time, the magnification of the coarsely aligned image from the horizontal direction is configured to be larger than the magnification of the coarsely aligned image from above.

  In the measurement, first, the upper probe rough approach image acquisition device 910A performs rough approach to bring the probes 903 closer to each other in the horizontal direction. At this time, it is necessary to capture a plurality of probes 903 as a rough approach image. In the rough approach from the lateral direction, the probe 903 is lowered while looking at the rough approach image in the lateral direction to approach the sample. Thereafter, the first electron optical system device 904 is used to perform an operation of bringing the probe 903 into contact with the sample while examining how the tip of the probe 903 is focused on the sample. When the distance between the probe 903 and the sample is small in the rough approach from the lateral direction, the time required for the approach operation of the probe 903 and the sample using the first electron optical system device 904 can be shortened. For this reason, the magnification of the roughly aligned image from the horizontal direction is configured to be larger than the magnification of the roughly aligned image from above.

  The stage includes a sample holder 902 that holds a sample, a sample stage 950 on which the sample holder 902 is mounted, a large stage 949 on which the sample holder 950 is mounted, and a base 948 on which the large stage 949 moves. This stage is attached to the side surface of the sample chamber 907 via a face plate 971. The face plate 971 is attached to the sample chamber 907 via a guide connecting plate 971a and a guide 971b using a roller.

  Next, a front view and a side view of the prober apparatus of the present embodiment are shown in the right and left views of FIG. 20, respectively. As shown in FIG. 20, when performing stage maintenance or probe unit replacement, the stage is pulled out along the guide 971b. A guide block 948a attached to the lower portion of the sample chamber 907 in FIG. 19 is used for vertical positioning of the stage with respect to the first electron optical system device 904, and also guides when the stage is pulled out from the sample chamber 907. . A sliding material 948b such as a polymer material that easily slips between the bottom of the base 948 is bonded to the upper portion of the guide block 948a.

  The probe stage 906 includes a probe unit 933 including a probe holder 931 that holds the probe 903, a probe unit base 934 that holds the probe unit 931, and a probe unit base 935 that connects the probe unit base 934 to the large stage 949. The probe unit 933 includes an x, y, and z table (not shown), and can move the probe 903 in a three-dimensional direction.

The base 948 is fixed to the face plate 971 by a fixing member 947. The sample chamber 907 is provided with a sample exchange chamber 908 and a probe exchange chamber 909.
In the face plate 971, a signal for controlling the operation of the x, y, z table of the probe unit 933 and a signal for controlling the operation of the x, y, z table 961, 962, 963, 963a of the sample stage 950 are supplied to the sample chamber 907. A field-through is provided for sending from outside.

  The inside of the sample exchange chamber 908 and the inside of the sample chamber 907 are connected via a gate valve 921. The inside of the sample exchange chamber 908 is connected to a dry pump (DP) 952, and vacuum processing is performed. As a result, the sample holder 902 holding the sample by the transport means 929 can be exchanged while maintaining the vacuum in the material chamber 907. In FIG. 19, for convenience of drawing, the sample exchange chamber 908 is illustrated as being connected to the right side surface of the sample chamber 907. However, as shown in FIG. It is provided on the side surface of the sample chamber 907 in the front direction of FIG. 19 so that it can be easily placed on the stage below the electron optical system device 904.

  A first electron optical system device 904 and a probe rough alignment image acquisition device 910A are arranged in parallel on the upper surface of the housing of the sample chamber 907, and a probe replacement chamber 909 is provided in proximity to the probe rough alignment image acquisition device 910A. It is provided. The inside of the probe exchange chamber 909 is connected to the inside of the sample chamber 907 via a gate valve 923. The probe exchange chamber 909 is connected to a turbo molecular pump (TMP) 951 and a DP 952 connected thereto, and vacuum processing is performed. The probe unit 931 is exchanged by the exchange means 955 while maintaining a high vacuum in the sample chamber 907.

A TMP 911 is connected to the sample chamber 907 via a gate valve 953, and this TMP 911 is further connected to the DP 912. The housing of the sample chamber 907 is supported by a gantry 925 indicated by a one-dot chain line.
A control device 913 including a probe unit control unit and a stage control unit, and another control device 913A for controlling high vacuum processing by the TMP 911 and the DP 912 are provided. The control device 913A also controls the TMP 951 and the DP 952.

  Further, the prober 901 includes a display device 914 including an image display unit 915 and an image display control unit 916, and a probe 903 and a stage operation signal from the image display control unit 916 are transmitted to the probe unit control unit and the stage control unit. The probe unit 933, the stage, and the large stage 949 are controlled.

Further, the prober 901 includes a computer aided design (CAD) workstation (WS) 981 including an image display unit 982 and an image display control unit 983. The CAD WS 981 is connected to the display device 914 and transmits CAD image data to the display device 914 as necessary.
When exchanging probes, the y table and x table of the probe unit 933 are moved to a predetermined position (for example, the rear end), and the z table is moved to a predetermined position (for example, to the upper end).

  The part of the sample to be measured, that is, the part to be contacted with the probe 903 is displayed by moving the sample stage 950 on the image display unit 915 that displays image information from the first electron optical system apparatus 904, and the probe is displayed on the part. While viewing the sample 903 and the sample, the probe 903 is brought into contact with the portion of the sample to be contacted by operating the x, y, and z tables of the probe unit 933.

  In the present invention, the probe 903 and the stage driving device are not particularly limited. For example, a probe driving mechanism using a piezo element, a DC motor, an ultrasonic motor, or the like is used. Further, a pulse motor, a DC motor, an ultrasonic motor, or the like is used as a stage driving mechanism.

Hereinafter, the configuration and operation of the main elements of the apparatus will be described.
1. Configuration and Operation of Main Elements of Apparatus (1) Stage The stage includes a large stage 949 and a sample stage 950.

(A) Sample stage 950
The sample stage 950 includes a y table 962, an x table 961, and z tables 963 and 963a, and each table is moved in the y, x, and z directions by a driving mechanism. Here, since the sample stage 950 includes a driving means in the z (vertical) direction, the sample stage 950 is lowered in the z direction before the large stage 949 and the sample stage 950 are moved in the xy direction. Thus, mechanical interference between the sample 902a and the tip of the electron gun 904 can be avoided. Furthermore, in practice, when performing SEM observation using the present embodiment, the working distance from the tip of the electron gun 904 to the sample 902a can be reduced by raising the sample stage 950 in the z direction. It is possible to improve the spatial resolution. In this embodiment, the driving means in the z direction is incorporated in the sample stage 950, but it may be incorporated in the large stage 949 or both, and the same effect can be obtained.

  The y and x tables 962 and 961 are moved by driving a ball screw with a DC motor placed in the sample chamber 907, and guidance is performed by a cross roller (not shown). The z table 963 is moved by driving a DC motor attached to the z table 963. As shown in FIG. 19, the sample holder 902 and the sample are fixed to the sample holder receiver 917 attached on the z table 963. Accordingly, the sample is moved in the x, y, and z directions with respect to the electron beam. The z table 963 has a measurement position, a sample exchange position, and a probe exchange position. The measurement position is a position where the probe 903 is brought into contact with the sample, the sample exchange position is a position lowered from the measurement position, and the probe exchange position is a position further lowered. By setting this position, collision between the sample and the probe 903 is prevented when the probe 903 and the sample are exchanged.

(B) Large stage 949
As shown in FIG. 19, the large stage 949 includes a y table 965 and an x table 964, and is moved in the y direction and the x direction by a driving device (not shown). The sample stage 950 is mounted on the large stage 949 and driven.

  As shown in FIG. 19, on the large stage 949, a probe unit 933 constituting the probe stage 906, a probe unit base 934 holding the probe unit 934, and a probe unit base 935 are placed. The probe unit 933 is moved in the y direction, the x direction, and the z direction. As a result, the probe holder 931 held by the probe unit 933 is moved, and the probe 903 held at the tip thereof is moved in the y direction, the x direction, and the z direction.

The large stage 949 is moved on the base 948, and the sample stage 950 is moved on the large stage 949. Since the electron optical device 904, the probe rough approach image acquisition device 910A, and the probe exchange chamber 909 are arranged in parallel on the upper surface of the housing of the sample chamber 907, the moving mechanism places the sample and the probe 903 in the probe rough approach image acquisition position. And can be moved to the SEM observation position and the probe replacement position. That is, the moving mechanism moves the stage (the sample stage 950 and the probe stage 906) to the vertical position of the probe rough approach image acquisition device 910, the vertical position of the first electron optical system device 904, and the probe exchange chamber 909. It is possible to move between the vertical positions.
Therefore, the sample and the probe 903 are located between the vertical position of the probe rough approach image acquisition device 910, the vertical position of the first electron optical system device 904, and the vertical position of the probe exchange chamber 909. Moved.

In this embodiment, the movement on the base 948 can be performed while maintaining a high vacuum. By adopting such a moving method, it is possible to quickly and easily perform rough approach and high-accuracy positioning of the probe 903 with respect to the sample. Furthermore, even when the probe 903 is replaced, it can be performed while maintaining a high vacuum, and the probe 903 can be replaced quickly and easily.
Therefore, the moving mechanism moves the sample and the probe 903 from a position directly below the probe rough alignment image acquisition apparatus 910 provided in parallel to the first electron optical system apparatus 904 to a position directly below the first electron optical system apparatus 904. The movement can be performed while maintaining a high vacuum.

(2) Scanning electron microscope (SEM)
This is an example of the first electron optical system device 904, and is used as an observation means for bringing the probe 903 into contact with a target location of the sample, and is disposed on the upper portion of the sample chamber 907. The evacuation is performed by an ion pump 944. 990 shown in the left diagram of FIG. 20 is a second electron optical system apparatus, which includes a small SEM column 991, a small SEM column driving means 992, and a connecting member that connects between them. The small SEM column driving means 992 and the connecting member include an exhaust pipe for evacuation inside, and the small SEM column driving means 992 includes an ion pump 993 for rough exhaust inside the small SEM column 991. Is provided. It is preferable that the connecting member is composed of the exhaust pipe itself because conductance during rough exhaust increases. Since the internal structure of the small SEM991 is the same as that described in the first to ninth embodiments, it will be described briefly. However, the electron gun chamber including the electron gun and the casing surrounding the electron gun, and the electron gun chamber are irradiated. Irradiation optical system consisting of a scanning coil for scanning the sampled electron beam on the sample and an objective lens for focusing the electron beam passed through the scanning coil on the sample, secondary electron detection for detecting the generated secondary electrons It consists of a vessel. Further, the small SEM column 991 of the present embodiment has a differential exhaust structure using a non-evaporable getter pump (not shown) and an ion pump 993 installed in the small SEM column 992, and each upstream vacuum chamber has a differential exhaust structure. The combined use with the non-evaporable getter pump provided keeps the uppermost electron gun chamber in the exhaust system at an extremely high vacuum. In the present embodiment, the ion pump 993 is provided in the small SEM column driving means 922. However, the ion pump can be attached to the small SEM column 911, and the differential pumping structure is used in any configuration. It is feasible. However, the housing size of the sample chamber 907 may be smaller if the ion pump is attached to the outside of the sample chamber 907 (that is, to the small SEM column driving means 922).

  The second electron optical system device 990 is installed immediately above the sample exchange chamber 908 on the side surface of the sample chamber 907. For this reason, a vacuum introduction mechanism composed of bellows or the like is provided at the corner of the sample chamber 907. By the vacuum introduction mechanism, the second electron optical system device 990 is positioned in the direction in which the sample 902 is obliquely desired. The second electron optical system device 990 is installed in a drive guide 994 provided with a drive unit such as a motor. When acquiring an image in an oblique direction, the second electron optical system device 990 approaches the sample 902 up to a predetermined observation position, and other than that. In the case, it is moved to the retracted position. Note that the small SEM column 991 is always in a vacuum in the sample chamber 907 even when the second electron optical system 990 is moved to the retracted position. By adopting the structure as described above, the sample exchange process and SEM image observation for approaching the probe's circuit terminals can be performed quickly and safely (no crash between the probe and the circuit terminals). It becomes possible. In the left diagram of FIG. 20, the second electron optical system device is disposed in an oblique direction with respect to the sample, that is, inclined with respect to the first electron optical system device 904. May be arranged horizontally. However, in this case, it is necessary to provide it close to a position where no mechanical interference with the sample exchange chamber 908 occurs. On the other hand, when placed obliquely with respect to the sample, the working distance between the small SEM column 991 and the sample can be shortened, which is advantageous in obtaining an SEM image with high resolution. On the other hand, when the probe is arranged in a horizontal direction with respect to the sample, the probe can be observed from the side, which is advantageous in obtaining position information of the probe tip.

(3) Sample chamber 907
The sample chamber 907 is composed of a sample chamber case which is an upper lid and a housing, and a base 948 is attached to a face plate 971 on a side surface of the sample chamber case via a fixing member 947, and is placed on the large stage 949 in the sample chamber 907. A probe unit 933 is mounted, and a sample exchange chamber 908 is attached to the other side surface. A first electron optical system device 904, a probe rough alignment image acquisition device 910, and a probe exchange chamber 909 are attached to the upper lid. The sample chamber 907 is fixed on a load plate attached on a vibration isolation mount attached to the gantry 925. The sample chamber 907 is evacuated by TMP911 and DP912.

(4) Probe rough contact light microscope, CCD camera, probe rough contact image acquisition device The sample for measuring electrical characteristics is, for example, a semiconductor, and the probe 903 is normally brought into contact with a plug connected to the source, drain, gate and well. The plug is small and has a diameter of several tens of nanometers, and a high-resolution SEM is required to bring the probe into contact therewith. However, if the semiconductor sample is irradiated with an electron beam, the electron beam may be damaged, and it is desirable to shorten the beam irradiation time as much as possible. Therefore, based on the detection value of the probe rough approach image acquisition device 910, a plurality of probes are brought close to the horizontal direction in advance, and the vertical direction is made close to the sample surface. An image obtained from the probe rough approach light microscope and the CCD camera attached thereto is displayed on the monitor of the image display unit 915, and this operation is performed while viewing this image.

  The magnification on the monitor is several tens of times in order to bring the probes 903 as close as possible and capture the probe 903 and the sample on one screen. A light source is disposed adjacent to the probe rough approach light microscope. Observation with a probe rough approach light microscope and a CCD camera and introduction of light from the light source into the sample chamber are performed through the observation window 939 shown in FIG.

(5) Sample exchange chamber 908
The sample exchange chamber 908 is provided for exchanging the sample without breaking the vacuum of the sample chamber 907, and is evacuated by DP952. The sample exchange chamber 908 is separated from the sample chamber 907 by a gate valve 921. When the sample is introduced, the sample and the male screw at the tip of the exchange rod as the conveying means 929 of the sample holder 902 are screwed into the female screw provided in the sample holder 902, the gate valve 921 is opened, and z of the sample stage 950 is opened. This is done by inserting into a holder receiver 917 attached to the upper end of the table 963. When removing the sample, the reverse operation is performed. This shortens the sample exchange time.

(6) Probe exchange chamber 909
The probe exchange chamber 909 is provided for exchanging the probe 903 without breaking the vacuum in the sample chamber 907, and is for shortening the probe exchange time. The probe exchange chamber 909 is partitioned from the sample chamber 907 by a gate valve 923. The probe exchange chamber 909 is evacuated by TMP951 and DP952. The TMP 951 is used because the probe exchange chamber 909 is large, and if the gas is exhausted only with DP952, the gate valve 923 is opened while the pressure in the probe exchange chamber 909 is high, and the pressure in the sample chamber 907 after the exchange is the original pressure. This is because it takes a long time to recover the value.

2. Control System The first electron optical system device 904, the second electron optical system device 990, the probe unit 933, and each part of the stage are controlled using respective control circuits and computers built in the control device 913. The SEM, the probe unit 933, and the stage can be operated by any of the operation panels and the GUI on the monitor.

  The control device 913 includes a stage control unit for controlling the position of each stage, and a probe control unit for driving the probe unit 933 independently of the stage. The image control unit 916 includes a secondary electron detector control unit, a control unit for an electron beam irradiation optical system, and the like. In addition, the calculation processing unit has a function of displaying, as an image, the probe holder 931, the sample, the stylus state of the probe 903 on the sample, and the like, integrated with the control unit of the display device 914.

  Further, by operating the operation screen of the image display unit, an operation signal is given to the probe unit control unit and the stage control unit through the image display control unit, and the probe unit 933 and the stage are moved and positioned. Alternatively, the probe unit 933 and the stage can be moved and positioned using an operation panel having a joystick.

(1) SEM
The electron beam generated by the electron gun is irradiated onto the sample through a focusing lens and an objective lens, secondary electrons generated from the sample are detected by a secondary electron detector, and the signal is subjected to various electrical processes in the display. An image of the sample surface is displayed on the monitor on the image display unit 915 of the display device 914.

(2) Probe unit 933
As shown in FIG. 19, the signal for controlling the operation of the x, y, and z table of the probe unit 933 is obtained by using the signal from the control circuit 913 in the gantry 925 through the field through attached to the face plate 971 of the stage. 907 to the probe unit 933.

  An input signal given to the sample through the probe 903 attached to the probe holder 931 and an output signal obtained from the sample are input / output to, for example, a semiconductor parameter analyzer via a three-layer coaxial hermetic connector attached to the sample chamber 907.

(3) A signal for controlling the operation of the x, y, and z tables 961, 962, 963, and 963a of the sample stage 950 on the stage stage is obtained through a field-through attached to the face plate 971 by a control circuit signal in the gantry 925. To the sample stage 950 in the sample chamber 907.

3. Display device 914
The display device 914 displays the rough approach image acquired by the probe rough approach image acquisition device 910 and the stylus image of the probe 903 acquired by the first electron optical system device 904 or the second electron optical system device 990 on the sample. To do. That is, the probe operation screen and the operation procedure screen showing the operation procedure contents are displayed.

  In accordance with the operation procedure displayed on the operation procedure screen, the user positions the sample and the probe 903 with high accuracy while viewing the rough alignment image and the stylus image.

4). CAD workstation 981
The prober 901 includes a CAD WS 981 including an image display unit 982 and an image display control unit 983. The CAD WS 981 is connected to the display device 914 and transmits CAD image data to the display device 914 as necessary.

  According to the above configuration, the part of the sample to be measured on the image display unit 915 that displays the image information from the first electron optical system apparatus 904 while referring to the CAD information, that is, the part where the probe 903 is to be contacted The sample stage 950 is moved and displayed, and the probe unit 933, that is, the probe 903 is placed in the x, y, and z directions on the sample portion to be contacted while viewing the SEM image and CAD image of the probe 903 and the sample at that portion. It can be operated and brought into contact.

Furthermore, in this embodiment, the display device 914, the CAD workstation 981 and other control units are configured as separate computers, but these may be integrated and configured as a single computer.
Thus, the introduction of CAD navigation has the effect of significantly improving user convenience when probing the probe to the stylus position.

  In this embodiment, a semiconductor is used as an example of a sample. However, for the purpose of measuring local electrical characteristics, the apparatus of the present invention may be used for measuring a sample other than a semiconductor. For example, it may be used for measurement of local insulation resistance of a magnetic head. In addition to this, it goes without saying that fine electronic circuits in general, such as circuit wiring portions, electrodes, and memory cells, can be used as inspection objects. In addition, as a sample containing the inspection object, a semiconductor wafer, a chip or a sample substrate on which a circuit pattern is formed, a sample piece obtained by cleaving a sample substrate, and the like can be used.

  21 and 22 show the positional relationship between the probe 906, the sample transport means 929, and the small SEM column 991 of the present invention when the stage is viewed from above. Six probe stages 906 are arranged on the stage 965 so as to surround the sample holder 995. The space is partially fan-shaped, and the sample fixed to the tip of the sample transport means 929 and the small SEM column 991 of the present invention can be alternately inserted. As described above, the small SEM column may be introduced obliquely or vertically with respect to the first electron optical system device 904. That is, it is important to arrange both the sample introduction mechanism and the small SEM introduction mechanism in the same direction when viewed from above the sample stage. This has the advantage that both the small SEM column 991 and the sample transport means 929 can be introduced onto the stage without reducing the number of probe stages arranged on the stage.

  Next, the steps from sample exchange to contact between the probe and the circuit terminal will be described. The sample is attached to the tip of the sample exchange means 929 in the sample exchange chamber 908. After evacuating the sample exchange chamber 908, the gate valve 921 is opened, the sample transport means 929 moves into the sample chamber 971, and the sample 995 is inserted into the sample receiver 917 installed on the stage 965 and fixed. The The sample transport means 929 is pulled back after the sample 995 is released and stored in the sample exchange chamber 908.

  Thereafter, the stage is driven to move to a position where the rough image acquisition device 910 is located, and the coarse alignment of the probe and the circuit terminal on the sample is performed using the rough image acquisition device 910 by the method described above. Then, the stage is driven, and the SEM 904 moves to a position where high magnification observation can be performed using the SEM image from above. The probe 903 needs to be lowered and brought into contact with the circuit terminal after precisely aligning the positions of the probe 903 and the circuit terminal on the sample 995 as viewed from above with the SEM image.

  At this time, the small SEM column 991 of the present invention is introduced in place of the region used when the sample transport means 929 introduced the sample 995, and SEM image observation can be performed. The SEM image that can be observed is an image of the probe and the circuit terminal viewed obliquely from above, and is similar to FIG. 9 that is an image obtained from the apparatus described in the fourth embodiment. Since this SEM image provides information that can visually grasp the distance between the probe 903 and the circuit terminal, the approach and contact operation between the probe and the circuit terminal can be performed quickly and safely without causing a crash. become able to. In addition, it is possible to realize an efficient arrangement using six probes 906 without mechanical interference with probes 906 densely arranged on the stage, and at the same time, six circuit terminals can be used at the same time. There is also an effect that can be set widely.

The apparatus configuration described above can be realized without necessarily using a differential exhaust structure. However, by applying the differential pumping structure, the number of ion pumps that need to be provided in the second electron optical system device 990 can be reduced, which is very advantageous in improving the vibration isolation performance of the device. is there. In addition, as shown in FIG. 19, the first electron optical system device 904 also includes a plurality of ion pumps 944. By applying the differential pumping structure to the first electron optical system 904, It becomes possible to reduce the required number of ion pumps to one.
As described above, by applying the differential pumping structure to the vacuum pumping system of each electro-optical system device, the anti-vibration performance and the anti-vibration performance of the device are remarkably improved as compared with the prior art.

In this embodiment, the following prober device is disclosed.
A scanning electron microscope column that has a differential pumping structure in which two or more vacuum chambers are connected through an opening, is equipped with a non-evaporable getter pump on the upstream side, and an ion pump in one of the downstream vacuum chambers. A prober apparatus comprising two sets, or the prober apparatus described above, wherein one ion pump installed in the two sets of scanning electron microscope columns is used in combination with the two scanning electron microscope columns. Or the above-described prober device, wherein the same region is disposed in the field of view of the two sets of scanning electron microscope columns so that the viewing angles are different from each other.

  Or a prober device comprising a circuit terminal provided on the surface of the sample, a plurality of probes contacting the circuit terminal, a means for positioning the probe, and a means for introducing the sample into the prober device. It has a differential evacuation structure in which two or more vacuum chambers are connected through an opening, and has a scanning electron microscope column equipped with a non-evaporable getter pump on the upstream side and an ion pump on one of the downstream vacuum chambers A prober device characterized by that.

Alternatively, in the prober apparatus described above, the scanning electron microscope column has a moving means that can be positioned in a uniaxial direction.
Alternatively, in the prober apparatus described above, a plurality of the probes are arranged around the sample, and the sample introduction means and the scanning electron microscope column are arranged without a part of the plurality of probes. A prober device characterized by being vacated as a shared space.

  In this embodiment, the following focused ion beam apparatus and sample preparation apparatus are disclosed. It has a differential pumping structure in which two or more vacuum chambers are connected through an opening, and is equipped with a non-evaporable getter pump on the upstream side, an ion pump on one of the downstream vacuum chambers, and the uppermost vacuum chamber. A focused ion beam apparatus comprising an ion source.

  Alternatively, in the sample preparation device including a focused ion beam column, a scanning electron microscope column, and a sampling arm that cuts out a minute sample from the sample, the focused ion beam column has two or more vacuum chambers through openings. It has a combined differential pumping structure, equipped with a non-evaporable getter pump on the upstream side, an ion pump in one of the downstream vacuum chambers, and an ion source in the most upstream vacuum chamber Sample preparation device.

  Alternatively, in the sample preparation apparatus including a focused ion beam column, a scanning electron microscope column, and a sampling arm that cuts out a minute sample from the sample, the scanning electron microscope column passes through two or more vacuum chambers through openings. It has a combined differential pumping structure, with a non-evaporable getter pump on the upstream side, an ion pump in one of the downstream vacuum chambers, and an electron source in the uppermost vacuum chamber Sample preparation device.

  Alternatively, in the sample preparation device, the scanning electron microscope column has a differential pumping structure in which two or more vacuum chambers are connected through an opening, and is not evaporated on the upstream side. A sample preparation apparatus comprising a getter pump, an ion pump in one of the downstream vacuum chambers, and an electron source in the most upstream vacuum chamber.

1: electron source, 2: electron gun column, 3: non-evaporable getter pump, 4: heater, 5: non-evaporable getter pump, 6: electron optical system column, 7: sample chamber, 8: gun valve, 9: turbo Molecular pump, 10: electron gun column, 11: intermediate chamber, 12: rough exhaust port, 13: ion pump, 14: rough exhaust port, 15: metal valve, 16: metal valve, 17: metal valve, 18: magnetic field Superposition type electron gun, 19: electromagnetic coil, 20: probe, 21: probe, 22: circuit terminal, 23: sample stage, 24: stage drive means, 25: stage drive means, 26: probe drive means, 27 : Probe driving means, 28: turbo molecular pump, 29: ion pump, 30: electron source, 31: electron source, 32: electrostatic optical system, 33: electrostatic optical system, 34: non-evaporable getter pump, 35: Non-evaporation Tutter pump, 36: electron beam, 37: aperture plate, 38: electromagnetic coil, 39: ion source, 40: electrostatic electrode, 41: electrostatic electrode, 42: electrostatic electrode, 43: electrostatic electrode, 44: electrostatic Electrode, 45: Non-evaporable getter pump, 46: Non-evaporable getter pump, 47: Turbo molecular pump, 48: Ion pump, 49: Sample, 50: Ion beam, 51: Optical microscope, 52: Sample, 53: Monitor SEM Column: 60: Sample, 61: Ion source, 62: Electron source, 63: Electrostatic optical system, 64: Electrostatic optical system, 65: Electrostatic optical system, 66: Electrode, 67: Electromagnetic optical system, 69: Ion Pump: 70: Ion pump, 71: Stage, 72: Micro sampling arm, 75: Micro sampling arm driving means, 7
6: secondary electron detector, 77: FIB column, 78: SEM column, 79: non-evaporable getter pump, 80: non-evaporable getter pump, 81: non-evaporable getter pump, 82: non-evaporable getter pump, 83: magnetic path 85: first vacuum chamber 86: second vacuum chamber 87: third vacuum chamber 88: ion pump 89: cold cathode electron source 90: vacuum gauge 100: electron source 101: Electron beam illumination optical system column, 102: electromagnetic lens, 103: E × B deflector, 104: E × B deflector, 105: sample (wafer), 106: sample stage, 107: objective electromagnetic lens, 108: sample chamber 109: Intermediate electromagnetic lens, 110: Imaging electromagnetic lens, 111: Scintillator, 112: Optical lens, 113: CCD image sensor, 114: Small SEM column, 115: Electron source, 116: Non Evaporation getter pump, 117: Electrostatic optical system, 118: Ion pump, 119: Turbo molecular pump, 120: Mirror projection column, 121: Electron beam, 301: Irradiation electron beam, 302: Imaging electron beam, 304: Imaging Surface, 401: upper magnetic pole, 402: lower magnetic pole, 403: base magnetic pole, 404: magnet presser, 405: insulator, 406: anode, 407: insulator, 408: bolt, 409: countersunk screw, 410: magnet holder, 411 : Permanent magnet, 412: non-evaporable getter pump, 413: electron source, 414: heater, 415: small magnetic field superposed electron gun, 416: non-evaporable getter pump, 417: non-evaporable getter pump, 418: gun valve, 419: ion pump , 420: electromagnetic coil, 421: first vacuum chamber, 422: second vacuum chamber, 423: third Vacuum chamber, 500: Display, 501: control unit. 901: prober device, 990: small SEM column.

Claims (5)

A first electron optical system column for detecting mirror electrons, a second electron optical system column for detecting secondary electrons or reflected electrons, a sample stage on which a sample to be inspected is placed, and the sample stage are stored inside And a vacuum sample chamber in which the first electron optical system column and the second electron optical system column are fixed, and a detection signal acquired by the first electron optical system column or the second electron optical system column. Signal processing means for processing,
A mirror electronic sample inspection apparatus characterized in that an acquired image in the first electron optical system column can be compared with an acquired image in the second electron optical system column. In the mirror electronic sample inspection device according to claim 1,
The second electron optical system column has a differential evacuation structure in which two or more vacuum chambers are connected through an opening, and includes a non-evaporable getter pump on the upstream side, and an ion in any one of the downstream vacuum chambers. A mirror electronic sample inspection apparatus comprising a pump. In the mirror electronic sample inspection device according to claim 1,
The sample stage is capable of positioning a specific position on the sample acquired from the first electron optical system column to a position where an image can be acquired by the second electron optical system column. Mirror electronic sample inspection device. In the mirror electronic sample inspection device according to claim 1,
A mirror electronic sample inspection apparatus comprising a magnetic field superposition type electron gun, wherein the magnetic field superposition type electron gun adopts a differential pumping structure in which two or more vacuum chambers are connected through an opening. In the mirror electronic sample inspection device according to claim 1,
The magnetic field superimposed electron gun includes an electron source provided on the most upstream side of the vacuum exhaust system,
A non-evaporable getter pump that evacuates around the electron source;
An ion pump provided downstream from the non-evaporable getter pump;
A mirror electronic sample inspection apparatus comprising a removable electromagnetic coil disposed in the vicinity of the electron source.

Images