JP4118444B2 - Method for aligning energy beam for neutralization and focused ion beam apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for reducing a charge-up problem that occurs in a focused ion beam (FIB) apparatus.
[0002]
[Prior art]
The FIB apparatus has various functions such as a function of etching a sample without a mask, a function of selectively depositing a film on the sample, and a function of observing the sample. In order to realize these functions, the sample is irradiated with an ion beam in the FIB apparatus.
However, when the sample is irradiated with an ion beam, positive charges are accumulated in the sample. That is, so-called charge-up occurs. This is particularly remarkable when the sample has poor conductivity (for example, a photomask). This positive charge causes fluctuations in the trajectory of the ion beam, and causes disturbance of the electric field formed for secondary ion detection by the secondary ion detector normally provided in the FIB apparatus. Secondary ions cannot be detected.
[0003]
In order to avoid these, the FIB apparatus generally includes a neutralizer for neutralizing the positive charges. This neutralizer typically emits an electron beam as a neutralizing energy beam.
In order to make this neutralizer function effectively, it is necessary to irradiate the electron beam to a predetermined range including the region irradiated with the ion beam of the sample. Therefore, it is necessary to match the irradiation position of the ion beam and the irradiation position of the electron beam.
[0004]
As one of the methods for adjusting the irradiation position, there is a method using a Faraday cup (for example, Document 1: “New Edition Electrical Engineering Handbook” published by the Institute of Electrical Engineers of Japan, February 1988, p513). As another method, the same sample is scanned with an electron beam and an ion beam to obtain a secondary electron image and a secondary ion image, respectively. There is a method of matching an area with an ion beam irradiation area.
[0005]
[Problems to be solved by the invention]
However, the method using the Faraday cup has the following problems.
In the case of using a Faraday cup, generally, an ion beam is incident on a Faraday cup provided at a predetermined position of a sample stage of the FIB apparatus through an opening provided in a part of the cup. Then, when the incident position of the ion beam with respect to the Faraday cup is adjusted so that the ion current detected by the Faraday cup is maximized, the ion beam is incident on substantially the center of the opening of the Faraday cup. Thereby, the position of the ion beam is specified.
[0006]
When the position of the electron beam is specified, the same procedure as in the case of the ion beam is performed.
However, the opening of the Faraday cup is generally a rectangular opening having a side length of, for example, 100 μm. On the other hand, the ion beam diameter is, for example, 0.1 μmφ, and the electron beam diameter used in the neutralizer is, for example, about 200 μmφ.
[0007]
Therefore, the position of the ion beam itself can be accurately determined because the diameter of the ion beam is sufficiently smaller than the size of the opening of the Faraday cup. However, the position of the electron beam itself is shown in FIG. As described above, since the beam diameter of the electron beam 1 is larger than the size of the opening 3a of the Faraday cup 3, it becomes rough. That is, ideally, as shown in FIG. 5B, although it is preferable that the opening 3a of the Faraday cup 3 is located at the center of the irradiation region of the electron beam 1, FIG. As shown in (C), as long as a part of the irradiation region of the electron beam 1 is applied to the entire opening 3a of the Faraday cup 3, the current detected by the Faraday cup 3 is maximized. Therefore, even in the cases shown in FIGS. 5A and 5C, the position of the electron beam 1 is apparently specified.
[0008]
Even in such a case, for example, the electric field state of the surface changes on a sample with low conductivity such as a photomask while the potential drops to the ground in the Faraday cup, so the irradiation position of the electron beam is Since there is a possibility of change between the Faraday cup and the sample, it cannot always be said that the optimum position is specified. Therefore, when it is desired to match the ion beam irradiation position with a predetermined point in the electron beam irradiation region (typically the center point of the irradiation region), this conventional method is not a preferable method.
[0009]
In addition, in the above-described other conventional method, both the secondary electron detector and the secondary ion detector are required, so that the apparatus becomes large. Further, since it is necessary to generate and compare both the secondary electron image and the secondary ion image, the image processing itself becomes difficult.
The present application has been made in view of such a point. Therefore, the first object of this application is to use an arbitrary method in the irradiation region of the energy beam for neutralization with respect to the irradiation position of the ion beam by a simpler method than before. It is an object of the present invention to provide a method for aligning the energy beam for neutralization capable of aligning the positions of the neutralization energy rays.
[0010]
A second object of the present application is to provide an FIB apparatus that facilitates the implementation of the invention of the alignment method.
[0011]
[Means for Solving the Problems]
In order to achieve the first object, according to the invention of the neutralizing energy beam alignment method, the sample is irradiated with the neutralizing energy beam, and the irradiation range of the neutralizing energy beam is reflected on the sample. A first step of forming the reflected region, and a second sample of scanning the sample having the reflected region with the ion beam to obtain coordinate information on the scanning coordinate axis of the ion beam as coordinate information indicating the range of the reflected region. And a step of determining whether the irradiation range of the energy beam for neutralization is in an allowable positional relationship with respect to a predetermined irradiation point of the ion beam based on the coordinate information thus obtained. It is executed when it is determined that the above positional relationship is not satisfied in the step and the third step, and based on the information obtained in the third step so as to satisfy this positional relationship, the energy beam for neutralization Changing the irradiation area Characterized in that it comprises a fourth step.
[0012]
According to the invention of the method for aligning neutralizing energy rays, the neutralizing energy rays themselves form a reflection region corresponding to the range in which the neutralizing energy rays are irradiated on the sample. Then, the coordinate information of the reflection region is obtained by the ion beam itself that is the alignment target of the energy beam for neutralization. Then, based on the obtained coordinate information, it is determined whether the irradiation range of the energy beam for neutralization is in an allowable positional relationship with respect to a predetermined irradiation point of the ion beam, and when this positional relationship is not satisfied The irradiation area of the energy beam for neutralization is changed so as to satisfy it. Therefore, without using a Faraday cup, and without using both a secondary electron detector and a secondary ion detector, a predetermined irradiation point of the ion beam and an arbitrary region within the irradiation region of the energy beam for neutralization are used. These points can be aligned within a predetermined allowable range.
[0013]
Note that it is preferable to determine whether the irradiation range of the neutralizing energy beam is in an allowable positional relationship with respect to a predetermined irradiation point of the ion beam based on coordinate information indicating the irradiation range of the neutralizing energy beam. Examples of the method include the following methods.
That is, a predetermined point for the neutralizing energy line is determined from the coordinate information according to a predetermined condition. A method of determining whether or not the predetermined point is within a predetermined range on coordinates with respect to a predetermined irradiation point of the ion beam can be given. And when it is necessary to change the irradiation area | region of the energy beam for neutralization, it is good to change an irradiation area | region based on the deviation | shift amount of the said predetermined | prescribed point and the said predetermined irradiation point. .
[0014]
Note that the predetermined point calculated from the coordinate information of the reflection area is an arbitrary point according to the design in the reflection area. Although not limited thereto, typically, for example, the center point, the upper left point, the upper right point, the lower left point, or the lower right point of the reflection region can be used. Typically, the center point of the reflection area is good.
The predetermined irradiation point of the ion beam is an arbitrary point according to the design. Typically, the ion beam may irradiate the sample in a state where the initialization voltage is applied to the scanning electrode (see 13d in FIG. 1) for scanning the ion beam (including the case where the voltage is 0). . Of course, the ion beam may irradiate the sample with a predetermined bias voltage applied to the scanning electrode.
[0015]
In order to achieve the second object of the present application, the FIB apparatus of the present invention includes a processing chamber, an ion beam supply unit, an exhaust unit, a neutralizer, a reflection region forming unit, and a reflection region detection. A neutralization energy beam position determination unit, and a neutralization energy beam irradiation region change unit.
However, the inside of the processing chamber can be made into a vacuum atmosphere, an ion beam can be run inside, and a sample is accommodated inside. The ion beam supply unit supplies an ion beam to the sample. The exhaust unit forms a vacuum atmosphere in the processing chamber. The neutralizer irradiates an arbitrary range of the sample with a neutralizing energy beam for neutralizing charges accumulated in the sample when the sample is irradiated with an ion beam. The reflection region forming unit irradiates the sample with the energy beam for neutralization, and forms a reflection region corresponding to the irradiation range of the energy beam for neutralization on the sample. The reflection region detection unit scans the sample on which the reflection region is formed with an ion beam, and obtains coordinate information on the scanning coordinate axis of the ion beam as coordinate information indicating the range of the reflection region. The neutralization energy beam position determination unit is based on the coordinate information obtained by the reflection region detection unit, and whether the irradiation region of the neutralization energy beam is in an allowable positional relationship with respect to a predetermined irradiation point of the ion beam. Is determined. The neutralizing energy beam irradiation region changing unit operates when the neutralizing energy beam position determining unit determines that the above-described determination condition is not satisfied, and the coordinate information obtained by the reflecting region detecting unit Based on the above, the irradiation range of the neutralizer is changed so as to satisfy the above-described determination condition.
[0016]
According to the invention of the FIB apparatus, the neutralizing energy beam alignment method of this application can be easily implemented.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the invention of the neutralizing energy beam alignment method and the FIB apparatus according to the present application will be described with reference to the drawings. In addition, each figure used for the following description is only showing each component roughly to such an extent that these inventions can be understood. Moreover, in each figure, the same code | symbol is attached | subjected about the same component, and the duplicate description may be abbreviate | omitted.
[0018]
FIG. 1 is a schematic configuration diagram of an apparatus for explaining a focused ion beam (FIB) apparatus 10 suitable for carrying out the invention of the method for aligning neutralizing energy beams. The FIB apparatus 10 includes a processing chamber 11, an ion beam supply unit 13, an exhaust unit 15, a gas supply unit 17, a sample stage 19, a secondary ion detector 21, an image forming device 23, a neutralizer 25, and a reflection region forming unit. 27, a reflection region detection unit 29, a neutralization energy beam position determination unit 31, a neutralization energy beam irradiation region change unit 33, and a control unit 35.
[0019]
FIG. 1 shows a state in which the sample 37 is provided on the sample stage 19. The sample 37 can be an arbitrary sample such as a semiconductor element, a wafer on which a large number of semiconductor elements are formed, a lithography mask for light, X-rays, or the like.
The processing chamber 11 is a chamber in which a vacuum atmosphere can be formed, the ion beam 39 can travel, and the sample 37 can be taken in and out. The processing chamber 11 in the case of this embodiment includes a first chamber portion 11a that accommodates the sample stage 19 and the like, and a second chamber portion 11b that accommodates the ion beam supply portion 13 and the like and has a cylindrical shape. It is configured.
[0020]
The ion beam supply unit 13 supplies an ion beam 39 to the sample 37 in a focused ion beam state having a desired beam diameter. However, the ion beam 39 can be irradiated to an arbitrary position of the sample 37, and the ion beam 39 can be scanned to an arbitrary region of the sample 37. Therefore, the ion beam supply unit 13 of this configuration example includes an ion source 13a, an extraction electrode 13b, a blanking electrode 13c, a scanning electrode 13d, and an objective lens 13e, and as is well known, the second chamber portion 11b in this order. Is placed inside.
[0021]
The ion source 13 a generates ions for irradiating the sample 37. This ion source 13 a is provided near the top of the second chamber portion 11 b of the processing chamber 11. The ion source 13a may be an ion source that generates one type of ion, or an ion source that can generate two or more types of ions and selectively extract any one of them. Among arbitrary ion sources, the gallium ion source is particularly preferable because it is easy to design the ion source because gallium itself has a low melting point. A silicon ion source is also preferable in that it is less likely to be an impurity with respect to a semiconductor using silicon.
[0022]
The extraction electrode 13b extracts ions generated by the ion source 13a to the sample 37 side.
The blanking electrode 13c is an electrode used when it is desired to stop irradiation of the ion beam 39 to the sample 37. Specifically, the ion beam 39 directed to the sample 37 can be directed in a direction different from the direction directed to the sample 37, and thereby the irradiation of the ion beam 39 onto the sample 37 is stopped.
[0023]
The scanning electrode 13d scans the sample 37 with the ion beam 39. The objective lens 13e focuses the ion beam 39.
Moreover, the exhaust part 15 makes the inside of the process chamber 11 the vacuum state of a desired vacuum degree, and is comprised with arbitrary suitable vacuum pumps. In the configuration example shown in FIG. 1, the exhaust portion 15 is connected to the first chamber portion 11a.
[0024]
The gas supply unit 17 is provided to cause the FIB apparatus 10 to exhibit a film deposition function. The FIB apparatus 10 shown in FIG. 1 includes first to third gas supply means 17a to 17c and a gas gun 17d for blowing gas to a predetermined limited area. In the configuration example of FIG. 1, the gas gun 17 d is provided in the first chamber portion 11 a and is installed toward the sample 37. Of course, the number of gas supply means is only one example. Further, the number of gas guns 17d is not limited to one. A gas gun may be provided for each gas supply means.
[0025]
One or two or more of the first to third gas supply units 17a to 17c themselves are formed in the sample 37 when the reflection region referred to in the present invention is formed using a gas for forming a thin film. It can also be used as a gas supply means.
These first to third gas supply units 17a to 17c themselves have any suitable configuration according to the type of gas used. In other words, if the gas source of the gas to be used is originally a gas, the gas supply means, for example, as shown by the second gas supply means 17b in FIG. A configuration including a valve 17b2, a vacuum gauge 17b3, a buffer 17b4, and the like can be employed. When the gas source of the gas to be used is originally liquid or solid and it is necessary to heat the gas source, the gas supply means includes means for heating the gas source and means for controlling the flow rate. A configuration (not shown) can be used.
[0026]
Further, in the configuration example of FIG. 1, any one of the valves 18 a to 18 c is provided between each of the first to third gas supply units 17 a to 17 c and the gas gun 17 d. These valves 18a to 18c can control the connection relationship between the first to third gas supply means 17a to 17c and the gas gun 17d.
The sample stage 19 is a stage on which the sample 37 can be placed and the sample 37 can be moved to any position in the three directions x, y, and z. Here, the z direction is a direction along a line segment connecting the ion source 13a and the sample stage 19, and the x and y directions are directions orthogonal to each other constituting a plane perpendicular to the z direction. This xy plane is a mounting surface of the sample 37.
[0027]
The secondary ion detector 21 receives the secondary ions emitted from the sample 37 when the sample 37 is irradiated with the ion beam 39, converts the intensity into the intensity of the current, and converts the intensity into an image forming apparatus (for example, a scanning ion microscope (for example) SIM)) 23. The secondary ion detector 21 is provided in the first chamber portion 11a and at an optimal position for receiving secondary ions.
[0028]
The image forming apparatus 23 forms an image corresponding to the secondary ion emission ability at each point irradiated with the ion beam of the sample 37 and displays the image on the display unit 23a. Therefore, this FIB apparatus 10 can be used as a SIM. This function can be used, for example, when observing a sample.
Since the structures of the secondary ion detector 21 and the image forming apparatus 23 are well known, detailed description thereof is omitted here.
[0029]
The neutralizer 25 emits energy beams for neutralization for neutralizing charges accumulated in the sample 37 when the sample 37 is irradiated with the ion beam 39. At present, since the ion beam 39 is a positive ion beam, an electron beam or a negative ion beam can be considered as the energy beam for neutralization. In this embodiment, a neutralizer 25 that emits a known electron beam is used.
[0030]
The reflection region forming unit 27 irradiates the sample 37 with the energy beam for neutralization from the neutralizer 25 under the same conditions as in the neutralization operation, for example, and reflects the irradiation range of the energy beam for neutralization on the sample 37. The reflected reflection area (see FIG. 2) is formed. Note that when forming the reflection region, the neutralizing energy beam is not set to the same conditions as in the neutralization operation, but may be a narrow region with a predetermined relationship with the region during the neutralization operation. The reflection region itself is preferably formed in a region of the sample 37 that is not an original processing region by the ion beam. In this way, the reflection region can be formed without wasting the sample 37 without hindering the original processing.
[0031]
As a specific and preferable method for forming the reflection region, the details will be described later. In the present invention, (1) a method for forming a film due to contamination on the ground, and (2) a gas for forming a thin film. Insist on a method of forming the film of (1) on the base, and (3) a method of altering a part of the base. Therefore, the reflection region forming unit 27 has a function of causing the exhaust unit 15, the gas supply unit 17, and the neutralizer 25 to perform processing operations according to the methods (1) to (3). For example, the reflection region forming unit 27 cooperates with the control unit 35 so that the exhaust unit 15, the gas supply unit 17, the neutralizer 25, and the like perform processing operations according to the methods (1) to (3). It can be configured by an electronic circuit (including a microcomputer or the like) that operates.
[0032]
The reflection region forming unit 27 preferably stores a current irradiation condition of the neutralizing energy beam (specifically, a deflection electric field forming condition that deflects the electron beam to the current irradiation range). It is good to have a configuration with This is because it is convenient when changing the irradiation condition of the energy beam for neutralization.
The reflection area detection unit 29 scans the sample on which the reflection area is formed with the ion beam 39 and detects the range of the reflection area. At this time, coordinate information on the scanning coordinate axis of the ion beam is obtained as coordinate information indicating the range of the reflection region.
[0033]
The reflection area detection unit 29 can be configured as follows, for example. When a sample with a reflection area is scanned with an ion beam, the ion beam reflects the sample.regionThe secondary ions emitted from the sample are different between when scanning the portion other than the above and when scanning the reflection region. Therefore, the reflection region can be detected by finding such a difference from the secondary ion data detected by the secondary ion detector 21. However, it is possible to obtain the coordinate information indicating the range of the reflection region by grasping the coordinate information of the corresponding ion beam when the generation state of secondary ions changes. The reflection area detection unit 29 itself can be configured by using a known technique for forming an image from the secondary ion detector. The reflection area detection unit 29 preferably includes a memory for storing the coordinate information.
[0034]
In addition, as a method for detecting the reflection region, (a) a method of focusing attention on secondary ions emitted from the sample itself and considering a region where this cannot be detected as a reflection region, and (b) secondary ions emitted from the reflection region itself. A detection method that considers the region where this is detected as a reflection region, and (c) a method using the method (a) and the method (b) in combination are conceivable. Any method may be used.
[0035]
The neutralizing energy beam position determination unit 31 neutralizes a predetermined irradiation point of the ion beam 39 (for example, a point where the ion beam 39 irradiates the sample with the initialization voltage applied to the scanning electrode 13d). The positional relationship of the irradiation range of the energy beam for neutralization output from the vessel 25 under the current conditions is determined. For this reason, the determination unit 31 of this embodiment uses a point (for example, the center point of the irradiation range) that is calculated from the coordinate information indicating the irradiation range of the energy beam for neutralization obtained by the reflection region detection unit 29. ) And the above-mentioned coordinates of the irradiation point of the ion beam to determine whether they match or fall within a predetermined allowable range. Such a determination unit 31 can be configured by a known electronic circuit including a memory, a logic circuit, and a comparison circuit.
[0036]
The neutralizing energy beam irradiation region changing unit 33 operates when the neutralizing energy beam position determining unit 31 determines that the positional relationship is not satisfied. However, the irradiation range of the neutralizer 25 is changed based on the coordinate information obtained by the reflection area detection unit 29 so as to satisfy the above determination condition. In the case of this embodiment, the changing unit 33 operates because the deviation between the predetermined irradiation point of the ion beam and the predetermined point calculated from the coordinate information obtained by the reflection region detecting unit 29 falls within an allowable range. Since it is time to exceed, the irradiation area of the energy beam for neutralization is changed so that this deviation amount falls within an allowable range. The irradiation area itself can be changed by changing the deflection electric field condition for deflecting the neutralizing energy beam. In addition, it is preferable to store the irradiation conditions (deflection electric field conditions) so far of the energy beam for neutralization because the purpose can be changed only by correcting this.
[0037]
The control unit 35 includes a processing chamber 11, an ion beam supply unit 13, an exhaust unit 15, a gas supply unit 17, a sample stage 19, a secondary ion detector 21, an image forming apparatus 23, a reflection region formation unit 27, and a reflection region detection unit. 29, each of the neutralizing energy beam position determining unit 31 and the neutralizing energy beam irradiation region changing unit 33 controls these so as to perform a predetermined operation. The control unit 35 can be configured by a device including, for example, a computer, a sensor provided at an appropriate position, and an electronic circuit.
[0038]
Such control is performed by, for example, experimentally examining in advance, for example, the degree of vacuum in the processing chamber, the irradiation condition of the energy beam for neutralization, the ion beam intensity, and the secondary ion detection condition. Can be realized by controlling the operation according to a predetermined procedure.
Next, an embodiment of the method for aligning neutralizing energy beams according to the present invention will be described. Here, an example of alignment using the FIB apparatus 10 described with reference to FIG. 1 will be described. This description will be given with reference to FIGS. These figures are views focusing on the vicinity of the FIB apparatus 10 where the gas gun 17d, the secondary ion detector 21, the neutralizer 25, and the sample 37 are provided.
[0039]
In the alignment method of the present invention, first, a part of the sample 37 is irradiated with the energy beam for neutralization of the neutralizer 25, and the reflection region 37a in which the irradiation range of the energy beam 25a for neutralization is reflected on the sample 37. (FIGS. 2A and 2B).
There are various methods for forming the reflection region 37a. As a first method, the environment of the processing chamber 11 in which the sample 37 is accommodated is set to an environment in which a film caused by contamination is deposited on a portion irradiated with the neutralizing energy beam 25a of the sample 37. There is a method of irradiating a part of the energy beam for neutralization. Here, the environment is typically a degree of vacuum.
[0040]
  According to the first method, a film caused by contamination is deposited in a portion corresponding to the reflection region 37a, and thus the film itself exhibits a function as the reflection region 37a.
  The environment of the processing chamber, for example, the degree of vacuum when the first method is performed, can be determined by experiment, for example. Such a degree of vacuum is not limited to this,10 ^-7 It is preferable that the degree of vacuum is lower than Torr. In addition, a film containing hydrocarbons is typically formed as a film resulting from contamination.
[0041]
In addition, when the environment of the processing chamber is not an environment in which a film due to contamination is generated on the irradiated area even when the sample is irradiated with the energy beam for neutralization, for example, the degree of vacuum in the processing chamber does not cause contamination. If it is good, the following method is preferably used as the second method of forming the reflection region 37a. That is, as shown in FIG. 4, the sample 37 is irradiated with the energy beam 25a for neutralization while the gas for thin film formation is sprayed onto the sample 37 by the gas gun 17d. It is good to form. In the case of the second method, the gas-derived film itself functions as the reflection region 37a.
[0042]
As the gas for forming the thin film, a gas capable of forming a film that can be distinguished from the material of the sample 37 is used. Although not limited thereto, a hydrocarbon-based gas is preferable as such a gas. The conditions for depositing the gas-derived film with the energy beam for neutralization and the gas for forming a thin film can be determined by experiments, for example.
Further, in the case where the sample 37 itself changes in quality depending on the intensity of the energy beam 25a for neutralization, such an altered portion may be created and used as the reflection region 37a. The irradiation conditions of the energy beam for neutralization for forming the altered portion can be determined by experiments, for example. Further, as a sample in which the irradiated part is altered depending on the intensity of the energy beam for neutralization, for example, CaF₂(Calcium fluoride). In the case of calcium fluoride, the electron beam irradiated portion changes to CaO.
[0043]
After forming the reflection region 37a by any of the above methods, the neutralizing energy beam is stopped, and then the sample is scanned with the ion beam 39 to detect the reflection region 37a (FIG. 2C). . Specifically, secondary ions generated in the sample are detected by the secondary ion detector 21 while the sample 37 including the reflection region 37 a is scanned with the ion beam 39. Since the secondary ions obtained from the region 37b other than the reflection region 37a of the sample 37 are different from the secondary ions obtained from the reflection region 37a, the range of the reflection region 37a can be specified from this difference. However, the coordinate information of the ion beam when scanning on the reflection region 37 a can be known by a known technique in the ion beam supply unit 13. Specifically, coordinate information (x1, y1) when the ion beam comes to the upper left point of the reflection region 37a, and coordinate information (x2, y2) when the ion beam comes to the lower right point of the reflection region 37a. Can be known as information on scanning coordinates of the ion beam supply unit 13.
[0044]
Next, based on the obtained coordinate information, it is determined whether or not the irradiation region of the neutralizing energy beam has an allowable positional relationship with respect to a predetermined irradiation point Q of the ion beam (FIG. 3). This determination can be performed as follows, for example. A predetermined point P is obtained under predetermined conditions from the coordinate information obtained for the reflection area 37a. The predetermined point P may be, for example, the upper left point (x1, y1), the lower right point (x2, y2), or any other point. In the example of FIG. 3, this predetermined point P is set as the center point of the reflection area 37a. That is, ((x1 + x2) / 2, (y1 + y2) / 2). The irradiation point Q can also be arbitrary, but here it is a point (initial irradiation point) where the ion beam irradiates the sample without applying a voltage to the ion beam scanning electrode.
[0045]
If the coordinates of the predetermined point P coincide with the coordinates of the initial irradiation point Q or are close within a predetermined allowable range, the irradiation position of the neutralizing energy beam matches the irradiation position of the ion beam. It is determined that Otherwise, since the irradiation positions of the two do not match, the irradiation area of the neutralizing energy beam of the neutralizer 25 is changed so that the deviation between the P point and the Q point is within the allowable range. The irradiation region can be changed by appropriately correcting the deflection electric field of the neutralizing energy beam (electron beam). Instead of changing the irradiation position of the neutralizing energy beam, the position of the original processing region of the sample 37 and the irradiation position of the ion beam 39 are set to the center point of the current irradiation region of the neutralizing energy beam. May be combined.
[0046]
By this series of processing, the irradiation area of the neutralizing energy beam and the irradiation position of the ion beam are aligned in a positional relationship effective for neutralization.
After changing the irradiation region of the neutralizing energy beam, if necessary, the processing of the present invention described with reference to FIGS. It is confirmed whether the irradiation position of the ion beam has been corrected to an allowable positional relationship. If such a confirmation operation is performed, the alignment can be performed more reliably.
[0047]
Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and many modifications or changes can be added.
For example, the arrangement of each component of the FIB apparatus is not limited to the example in FIG. In addition, the processing chamber 11, the ion beam supply unit 13, the gas supply unit 17, the reflection region forming unit 27, the reflection region detection unit 29, the neutralization energy beam position determination unit 31, the neutralization energy beam irradiation region change unit 33, and the like The configuration is not limited to the above example.
[0048]
【The invention's effect】
As is clear from the above description, according to the neutralizing energy beam alignment method of the present invention, a region in which the irradiation range of the energy beam is reflected by the neutralizing energy beam itself is formed on the sample. The coordinate information of the area is detected as coordinate information on the scanning coordinate axis of the ion beam by the ion beam itself. Then, based on this coordinate information, it is determined whether or not the irradiation position of the neutralizing energy beam and the predetermined irradiation point of the ion beam are in an allowable positional relationship, and if not satisfied, the change is made. .
[0049]
Therefore, without using a Faraday cup, and without using both a secondary electron detector and a secondary ion detector, a predetermined irradiation point of the ion beam and an arbitrary region within the irradiation region of the energy beam for neutralization are used. These points can be aligned within a predetermined allowable range.
In addition, according to the FIB apparatus of this application, a predetermined processing chamber, an ion beam supply unit, an exhaust unit, a neutralizer, a reflection region forming unit, a reflection region detection unit, and a neutralization energy beam position Since the determination unit and the neutralizing energy beam irradiation region changing unit are provided, the alignment method of the present invention is easily performed.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an FIB apparatus according to an embodiment.
FIG. 2 is a process diagram illustrating an embodiment of an alignment method.
FIG. 3 is a process diagram following FIG. 2 for explaining the embodiment of the alignment method;
FIG. 4 is a diagram illustrating a specific example of a method for forming a reflection area.
FIG. 5 is a diagram illustrating a problem.
[Explanation of symbols]
10: FIB apparatus of the embodiment
11: Processing chamber
13: Ion beam supply unit
15: Exhaust section
17: Gas supply unit
17a: first gas supply means
17b: Second gas supply means
17c: third gas supply means
17d: Gas gun
19: Sample stage
21: Secondary ion detector
23: Image forming apparatus
25: Neutralizer
27: Reflection area forming section
29: Reflection area detection unit
31: Neutralization energy beam position determination unit
33: Neutralizing energy beam irradiation area changing section
35: Control unit
37: Sample
37a: Reflection area
39: Ion beam
P: Predetermined point in the reflection area
Q: Predetermined irradiation point of ion beam

Claims (11)

  Irradiation position of the energy beam for neutralization and the ion beam in neutralizing the charge accumulated in the sample when the sample is irradiated with the ion beam by irradiating the sample with the energy beam for neutralization The first step of irradiating the sample with the energy beam for neutralization to form a reflection region reflecting the irradiation range of the energy beam for neutralization on the sample; and Based on the second step of scanning the formed sample with the ion beam and obtaining coordinate information on the scanning coordinate axis of the ion beam as coordinate information indicating the range of the reflection region, and the obtained coordinate information A third step for determining whether the irradiation range of the energy beam for neutralization is in an allowable positional relationship with respect to a predetermined irradiation point of the ion beam, and the positional relationship is satisfied in the third step. And a fourth step of changing the irradiation area of the neutralizing energy beam based on the coordinate information so as to satisfy the positional relationship, and is executed when it is determined not to be performed. How to align the neutralizing energy beam.   The alignment method of the energy beam for neutralization according to claim 1, wherein the formation of the reflection region is performed by changing the environment of the processing chamber containing the sample on the region irradiated with the energy beam for neutralization of the sample. The neutralization is performed by forming the film on the sample by irradiating the sample with the energy beam for neutralization under a condition in which a film resulting from contamination is formed in the sample. Method of alignment of energy beam.   2. The method for aligning neutralizing energy rays according to claim 1, wherein the environment of the processing chamber in which the sample is accommodated is contaminated on the irradiation area even when the neutralizing energy ray is irradiated on the sample. In the case where the resulting film is not in an environment, the reflection region is formed by irradiating the sample with the energy beam for neutralization while supplying a gas for forming a thin film into the processing chamber. A method for aligning neutralizing energy rays, characterized in that the method is performed by forming a film derived from the origin.   2. The method for aligning neutralizing energy rays according to claim 1, wherein when the sample is a sample of a material that changes in quality depending on the intensity of the neutralizing energy beam, the formation of the reflection region is neutralized to the sample. A method of aligning neutralizing energy rays, wherein irradiation is performed under an intensity condition that alters the sample to form a modified region in the sample.   2. The alignment method of the energy beam for neutralization according to claim 1, wherein the coordinate information indicating the range of the reflection region is scanned when the ion beam is scanning on the reflection region and on other regions. A method for aligning neutralizing energy rays, characterized in that the determination is made by utilizing the difference in the generation of secondary ions from the sample.   The alignment method of the energy beam for neutralization according to claim 3, wherein the gas for forming the thin film is supplied by using a gas gun that selectively supplies the vicinity of the irradiation region of the energy beam for neutralization. A method for aligning neutralizing energy beams.   2. The method for aligning neutralizing energy beams according to claim 1, wherein an electron beam is used as the neutralizing energy beam. A processing chamber in which the inside can be made into a vacuum atmosphere, an ion beam can be run inside, and a sample is stored inside,
An ion beam supply unit for supplying the ion beam;
A gas supply unit including a gas gun for blowing gas onto the sample;
An exhaust section for exhausting the processing chamber;
A neutralizer for irradiating an arbitrary range of the sample with an energy beam for neutralization for neutralizing charges accumulated in the sample when the sample is irradiated with the ion beam;
A control unit that controls the processing chamber, the ion beam supply unit, the gas supply unit, and the exhaust unit to perform predetermined operations;
The gas supply unit in cooperation with the control unit, and is not a predetermined operation to the exhaust portion and the neutralizer, forming reflecting region forming a reflecting region to reflect the irradiation range of the neutralizing energy beam to a sample And
A reflection region detector that scans the sample in which the reflection region is formed with the ion beam and obtains coordinate information of a scanning coordinate axis system of the ion beam as coordinate information indicating the range of the reflection region;
Neutralizing energy for determining whether the irradiation range of the neutralizing energy beam is in an allowable positional relationship with respect to an irradiation point determined in advance by the ion beam based on the coordinate information obtained by the reflection region detection unit. A line position determination unit;
The neutralization energy beam position determination unit operates when it is determined that the positional relationship is not satisfied, and based on the obtained coordinate information, the irradiation range of the neutralization energy beam satisfies the determination condition A focused ion beam apparatus comprising: a neutralizing energy beam irradiation region changing unit that changes in a similar manner. The reflection region forming unit operates the exhaust unit to set the degree of vacuum in the processing chamber to a predetermined level so that a film due to contamination is generated on the region irradiated with the neutralizing energy beam of the sample . claim under conditions with low vacuum than the vacuum degree, and wherein said that the neutralizer is operated the neutralizing energy beam is intended to cause the film on the sample by irradiating the sample 8 The focused ion beam apparatus according to 1. The reflection region forming unit operates the gas supply unit and the neutralizer in order to form a thin film in the reflection region, and the neutralization energy in a state where a gas for forming a thin film is sprayed on the sample by the gas gun. The focused ion beam device according to claim 8, wherein the sample is irradiated with a line. The reflection region detection unit includes a secondary ion detector that monitors secondary ions generated in the sample when the sample is scanned with the ion beam, and when the ion beam is scanning over the reflection region. 9. The focused ion beam according to claim 8 , wherein the detection is performed by utilizing the difference in the generation of secondary ions from the sample when scanning over a region other than the region. apparatus.

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