JP2007287495A - 2-lens optical system scanning type aberration corrected focused ion beam device, 3-lens optical system scanning type aberration corrected focused ion beam device, and 2-lens optical system projection type aberration corrected ion lithography device as well as 3-lens optical system projection type aberration corrected ion lithography device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide 2-lens and 3-lens optical system scanning type aberration corrected focused ion beam device and 2-lens and 3-lens optical projection type aberration corrected ion lithography device. <P>SOLUTION: An extraction electrode to extract an ion beam from an ion source, a gun lens constituted of a condenser lens to control an opening angle of the extracted ion beam, an current limitation diaphragm to extract the ion beam having a specific radiation angle from the ion beams having comparatively wide radiation angles generated from the ion source, an electrostatic type aberration corrected device to correct an electrostatic type opening angle control lens capable of the open lens control without changing current amount of the ion beam which has passed the current limitation diaphragm, an electrostatic type aberration corrected device to correct color aberration and spherical aberration, and an electrostatic type objective lens to focus the beams on a sample are arranged in this order, and furthermore, this is provided with a deflector to scan the focused ion beams in the two-dimensional direction on a sample. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a two-lens optical system scanning aberration correction focused ion beam apparatus, a three-lens optical system scanning aberration correction focused ion beam apparatus, a two-lens optical system projection aberration correction ion lithography apparatus, and a three-lens optical system projection aberration correction. The present invention relates to an ion lithography apparatus.

  The present invention relates to a scanning ion microscope that detects secondary electrons, secondary ions, and the like generated from an ion beam scanning region, a microfabrication apparatus using a sputtering phenomenon in an ion beam scanning region, or a projection ion irradiation region, and ion beam irradiation. It is used in an ion beam lithography apparatus that utilizes a photosensitivity phenomenon to a resist or the like.

  In many focused ion beam apparatuses (hereinafter abbreviated as FIB apparatuses) on the market, basically, an electrostatic focusing lens for controlling the opening angle of the beam and an electrostatic objective for focusing the beam on the sample. An electrostatic two-lens optical system in which only two lenses are mounted is used. On the other hand, FIB apparatuses using a three-lens optical system are also on the market.

  FIG. 13 is a conceptual diagram of an optical system FIB apparatus with two lenses and three lenses. (A) shows a two-lens optical system FIB apparatus, and (b) shows a three-lens optical system FIB apparatus. In the figure, reference numeral 1 denotes an emitter that emits an ion beam, 2 denotes an extraction electrode provided below the emitter 1, and 3 denotes a focusing lens (CL1) that controls an opening angle of the beam provided below the extraction electrode 2. .

  4 is a movable current limiting diaphragm provided below the focusing lens 3, 5 is a deflector disposed below the movable current limiting diaphragm 4, 6 is an objective lens disposed below the deflector 5, and 7 is an objective lens 6. An objective lens provided at the lower part, 7 is a sample provided at the lower part of the objective lens 6. The above configuration is common to the two-lens optical system FIB apparatus and the three-lens optical system FIB apparatus. In the three-lens optical system FIB apparatus, 8 is a beam aligner for adjusting the beam provided at the lower part of the focusing lens 3, and 9 is an opening angle control lens (CL2) provided at the lower part of the movable current limiting diaphragm 4. . The opening angle control lens 9 is not provided in the two-lens optical system.

The three-lens optical system has the following advantages over the two-lens optical system.
1) The beam current of the two-lens system can be defined by only one current in principle for one inner diameter of the current limiting diaphragm 4. Of course, a beam current in a considerable range can be controlled by the excitation intensity of the focusing lens 3, but the beam diameter is extremely deteriorated except for a specific current. Accordingly, the number of types of aperture diameters that can be exchanged becomes the number of currents that can be defined.

  On the other hand, in the three-lens optical system, the opening angle can be controlled regardless of the beam current, so that the beam current can be controlled in a wide range without extreme deterioration of the beam diameter with one current limiting diaphragm inner diameter. . That is, since a wide range of beam currents can be defined with at least one aperture diameter that can be exchanged as compared with the two-lens optical system, it is possible to specify a substantially arbitrary beam current.

FIG. 14 is a diagram showing a comparison between the two- and three-lens optical systems having a beam diameter dp-ion beam current Ip characteristic. The vertical axis represents the beam diameter [nm], and the horizontal axis represents the probe current [pA]. The solid line indicates the characteristic of the three lens system, and the broken line indicates the characteristic of the two lens system. An arrow indicates a current region in which an improvement in beam diameter can be expected by the opening angle control lens. Each curve number represents a movable aperture number. As can be seen from the figure, the usable width of the two-lens system is narrow.
2) Other applications of FIB equipment using microfabrication using sputtering include a) thin film formation by deposition, b) maskless gas etching, c) SIMS (mass spectrometry), etc. By using a three-lens optical system that can be specified, it is possible to dramatically increase these throughputs.

As described above, the superiority of the three-lens optical system is clear, but the following reasons can be considered that the FIB apparatus cannot actually occupy the majority.
1) Rather than increasing the number of lenses, it is cheaper to increase the number of interchangeable limiting apertures according to the number of necessary beam current types.
2) Even if the number of lenses is increased, the maximum resolution and the maximum current density, which are guidelines for the performance of the FIB apparatus, are not improved, but only the available current types are increased.
3) It is conceivable that the three-lens optical system has a thought that it is more difficult to adjust the device than the two-lens optical system.

On the other hand, in order to tackle the problems demanded by the semiconductor industry in recent years, the following FIB apparatus has been improved.
1) Aim to realize a high-throughput, high-resolution FIB apparatus by applying an optimum optical system.
2) In general-purpose FIB equipment, the acceleration voltage, which is usually 30 to 50 kV, is further accelerated to achieve high throughput and high resolution FIB equipment.
3) Development of a gas field ion source using a rare gas that is expected to have high brightness and high resolution instead of the Ga-liquid metal ion source (G-LMIS) that is normally used in general-purpose FIB equipment, and is free from Ga contamination Aim to realize high throughput and high resolution FIB equipment.
4) Establishment of an ion optical system capable of realizing an ion lithography apparatus with a single column.

  The direction shown in the above 1) has already stalled around 1997, and since then there have been few papers on FIB optical systems. On the other hand, although the current density and resolution can be increased to some extent by increasing the acceleration in the item 2), the demand from the semiconductor industry in the last two to three years is conversely the acceleration.

  The reason is that high acceleration ion irradiation inevitably increases the damage to the low / high-k substance, which is a new material, the thickness of the cross-sectional amorphous layer at the time of TEM sample preparation, and the like. Items 3) and 4) have been extensively studied, but there is no prospect of practical use until now.

This type of conventional device has a scanning mode in which the aberration corrector is operated and a scanning mode in which the aberration corrector is not operated, and a technique for controlling the operation of the aberration corrector so that the object point position of the objective lens does not change in both. (See, for example, Patent Document 1). In addition, each line in the two-dimensional scan of the sample is repeatedly scanned three times with acceleration voltages ΔE + E1, ΔE, ΔE + E2, and three types of images based on this scan are displayed on a three-divided display. By focusing the image on the left side of the display image and adjusting the power of the aberration corrector so that the image on the right side of the display is also focused. A technique for correcting chromatic aberration is known (see, for example, Patent Document 2).
Japanese Patent Laying-Open No. 2004-303547 (paragraphs 00001 to 0017, FIG. 1) Japanese Patent Laying-Open No. 2004-355822 (paragraphs 0035 to 0039, FIG. 5)

  Common performances that are strongly demanded for FIB devices at present are high resolution, high current density, and low acceleration contrary to this. For example, with a current FIB device of 30 kV, a maximum resolution of about 5 nm is obtained with a beam current Ip = 0.5 pA, and a beam diameter of about 80 nm is obtained with 1 nA, but with a maximum resolution of about 20 nm at 5 kV, about 400 nm with 1 nA That is, the beam diameter can be obtained.

  The factors that limit the beam diameter are Gaussian image and first order chromatic aberration when Ip ≦ 10 pA, and first order chromatic aberration and third order spherical aberration when 10 pA ≦ Ip ≦ 1 nA, and third order spherical aberration when 1 nA ≦ Ip. From this, it can be considered that the deterioration in resolution and beam diameter due to the reduction in acceleration is due to chromatic aberration.

  That is, it can be seen that if the aberration correction is performed, the deterioration of the beam diameter can be minimized within a wide acceleration voltage range. And if this technique is realizable, even if the ion source which replaces Ga-liquid metal is developed, it will become possible to apply immediately.

  On the other hand, in recent years, aberration correction apparatuses using an electrostatic magnetic field for correcting chromatic aberration and spherical aberration have been developed, and various electron microscopes equipped with these apparatuses have achieved high resolution far exceeding the conventional limit. However, an aberration correction apparatus using a magnetic field has the following disadvantages: a) it is difficult to adjust due to its poor reproducibility, so that the throughput is lowered, and b) it cannot be applied to an ion optical system having a large mass. However, recently, a paper on all-electrostatic aberration correction has been published and has attracted attention as a concept that can improve the drawbacks of the above-described electrostatic magnetic field-type aberration correction apparatus.

One way to overcome the limitations of the prior art with respect to improving the resolution of the FIB device (reducing the beam diameter) and increasing the beam current density is the aberration correction technique.
The present invention has been made in view of such problems, and firstly, an aberration-corrected focused ion beam apparatus and an optical projection type that realize a maximum resolution and a maximum beam current density by executing a theoretical study on aberration correction. An object of the present invention is to provide an aberration correction ion lithography apparatus, and secondly, an aberration correction focused ion beam apparatus and an optical projection type aberration correction ion capable of automatically executing aberration correction which is considered to be very difficult to adjust in the past. The object is to provide a lithography apparatus.

  (1) The invention described in claim 1 is a gun lens comprising an ion source that emits ions, an extraction electrode that extracts an ion beam from the ion source, and a condenser lens that controls an opening angle of the extracted ion beam, A current limiting diaphragm that extracts an ion beam having a specific radiation angle from an ion beam having a relatively wide radiation angle generated from the ion source, an electrostatic aberration correction device that corrects chromatic aberration and spherical aberration, and an ion beam on the sample. It is characterized by comprising a deflector arranged in the order of the electrostatic objective lenses for focusing, and further scanning the focused ion beam in a two-dimensional direction on the sample.

  (2) The invention according to claim 2 is a gun lens comprising an ion source that emits ions, an extraction electrode that extracts an ion beam from the ion source, and a condenser lens that controls an opening angle of the extracted ion beam, An electrostatic aberration correction device that corrects chromatic aberration and spherical aberration, and an electrostatic objective lens for focusing the ion beam on the sample, are arranged in this order, and somewhere between the optical elements or below the objective lens It is characterized by being composed of a placed drawing stencil mask.

  (3) The invention according to claim 3 is a gun lens comprising an ion source that emits ions, an extraction electrode that extracts an ion beam from the ion source, and a condenser lens that controls an opening angle of the extracted ion beam, A current limiting diaphragm for extracting an ion beam having a specific radiation angle from an ion beam having a relatively wide radiation angle generated from the ion source, and an opening angle control without changing the current amount of the ion beam that has passed through the current limiting diaphragm. Ion beam that is arranged in the order of an electrostatic type aperture angle control lens capable of correcting, an electrostatic type aberration correcting device for correcting chromatic aberration and spherical aberration, and an electrostatic type objective lens for focusing the beam on the sample. Is provided with a deflector that scans the sample in a two-dimensional direction on the sample.

  (4) The invention according to claim 4 is characterized in that, on the current limiting diaphragm, ions are placed between a two-stage swing-back type electrostatic deflector, an electrostatic opening angle control lens, and an electrostatic aberration correcting device. An electrostatic deflector capable of independently deflecting the beam in a two-dimensional direction is provided.

  (5) The invention according to claim 5 is a gun lens comprising an ion source that emits ions, an extraction electrode that extracts an ion beam from the ion source, and a condenser lens that controls an opening angle of the extracted ion beam, An electrostatic opening angle control lens capable of controlling the opening angle, an electrostatic aberration correcting device for correcting chromatic aberration and spherical aberration, and an electrostatic objective lens for focusing the ion beam on the sample are arranged in this order. It is characterized by comprising a drawing stencil mask placed somewhere between the optical elements or under the objective lens.

  (6) The invention according to claim 6 is a gun lens comprising an ion source that emits ions, an extraction electrode that extracts an ion beam from the ion source, and a condenser lens that controls an opening angle of the extracted ion beam, 2-stage swing-back electrostatic deflector, drawing stencil mask, electrostatic opening angle control lens capable of controlling the opening angle, electrostatic deflector capable of independently deflecting the ion beam in the two-dimensional X and Y directions, An electrostatic aberration correction device for correcting chromatic aberration and spherical aberration and an electrostatic objective lens for focusing an ion beam on a sample are arranged in this order.

(1) According to the first aspect of the invention, the resolution and current density can be increased.
(2) According to the invention described in claim 2, it is possible to perform drawing with good resolution using the drawing stencil mask.
(3) According to the invention described in claim 3, ion beam irradiation can be performed while reducing aberrations.
(4) According to the invention described in claim 4, it is possible to provide an aberration-corrected focused ion beam apparatus that realizes the maximum resolution and the maximum beam current density, and the aberration that is considered to be very difficult to adjust conventionally. It is possible to provide an apparatus capable of automatically executing correction.
(5) According to the invention described in claim 5, it is possible to perform beam drawing with high accuracy using the drawing stencil mask.
(6) According to the invention described in claim 6, it is possible to provide an ion lithography apparatus capable of automatically performing aberration correction.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram showing a configuration example of a focused ion beam apparatus using a two-lens optical system. In this figure, the FIB apparatus as a base is composed of an ion source (emitter) 11, an extraction electrode 12 for extracting an ion beam from the ion source 11, and a focusing lens 13 for controlling the opening angle of the extracted ion beam. A gun lens (condenser lens), a current limiting diaphragm 14 for extracting a beam having a specific radiation angle (solid angle) from an ion beam having a relatively wide radiation angle generated from the ion source 11, and deflecting the ion beam in a two-dimensional direction. A two-lens optical system is used in which the deflector 16 and the electrostatic objective lens 15 for focusing the ion beam on the sample M are arranged in this order.

  The condenser lens 13 includes a lens electrode 13B and a ground electrode 13C. The objective lens 15 includes an electrode 15A, an electrode 15B, and an electrode 15C. Reference numeral 18 denotes a sample stage on which the sample M is placed, 17 denotes a detector that detects reflected particles when the ion beam is irradiated on the sample M, and 27 denotes a display device that displays a detection signal detected by the detector 17. is there. For example, a CRT or a liquid crystal display is used as the display device 27.

  Reference numeral 21 denotes an accelerating power source that applies an accelerating voltage to the emitter 11, 22 denotes an extracting power source that applies an extracting voltage to the extracting electrode 12, 23 denotes a lens power source that supplies an operating voltage to the condenser lens 13, and 24 denotes a deflecting power source that applies a deflecting voltage to the deflector 16. , 25 is a lens power supply for applying an operating voltage to the objective lens 15.

  As a result of calculation, it was concluded that an FIB apparatus in which an aberration correction apparatus is mounted on the two-lens optical system should be configured as shown in FIG. FIG. 2 is a diagram showing a configuration example of a scanning focused ion beam apparatus equipped with a two-lens optical system aberration correction apparatus. The same components as those in FIG. 1 are denoted by the same reference numerals. In the figure, 11 is an emitter, 12 is an extraction electrode, 13 is a focusing lens (CL1), 28 is a beam aligner disposed below the focusing lens 13, and 14A is a movable current limiting aperture disposed below the beam aligner 28. is there.

  Reference numeral 29 denotes an aberration correction device disposed below the movable current limiting diaphragm 14A, and includes an upper aberration correction device 29A and a lower aberration correction device 29B. Reference numeral 16 denotes a deflector (deflector) arranged at the lower part of the aberration correction device 29, 15 denotes an objective lens arranged at the lower part of the deflector 16, and M denotes a sample.

  25, an objective lens voltage power source for driving the objective lens 15, 30 an aberration correction lens component voltage power source, 31A receiving an output from the aberration correction lens component voltage power source 30, and driving an upper aberration correction device 29A, Reference numeral 31B denotes an aberration correction power source lower power source that receives the output of the aberration correction lens component voltage power source 30 and drives the lower aberration correction device 29B.

The reason why it is concluded that the configuration configured in this way is the best is as follows.
1) Considering the reduction of the beam diameter that can be achieved (the relationship between aberration generation and aberration correction by attaching an aberration correction device), the position of the aberration correction device is an extraction electrode that can drive the aberration correction device at a low voltage. It is best to place it between the focusing lens 13 and the objective lens 15 than between the focusing lens 13 and the focusing lens 13 or below the objective lens 15.
2) It is considered that the position of the aberration correction device between the focusing lens 13 and the objective lens 15 is best placed between the current limiting aperture 14A and the objective lens 15. This is because of the following advantages.
Excitation of the aberration correction device 29 (applied voltage applied to the electrodes for correcting each aberration) varies depending on the settings of the emitter 11 and the objective lens 15. However, if the aberration corrector 29 is on the current limiting aperture 14 </ b> A, the beam current changes depending on the excitation state of the aberration corrector 29.
In order to perform aberration correction, the beam must be crossed at different positions in the x and y directions (see FIG. 3). FIG. 3 is a diagram showing a typical beam trajectory during aberration correction. The X and Y trajectories in the aberration corrector are shown. The aberration correction device 29 is composed of an incident multipole element, a first / second correction element, and an output multipole element, and draws a trajectory as shown in the figure in each component, and at the exit multipole exit X The track and Y track are integrated.

  On the other hand, at the same acceleration voltage, the influence of the space charge effect is larger than that of the electron beam in the case of ion particles having a large mass. For this reason, in order to minimize the influence of the space charge effect on the beam diameter, the ion beam current incident on the aberration correction device 29 must be minimized.

The operation of the apparatus configured as described above will be described as follows.
Now, the beam diameter dp-beam current Ip characteristics when an aberration correction device 29 having a length of about 300 mm is mounted at a position shown in FIG. 2 in a standard two-lens optical system FIB device are compared with those when the lens is not mounted. Then, optical calculation is performed under the following conditions.
1) Emitter angular current density: 20 μA / sr
2) Virtual source diameter: 50 nm
3) Energy spread: 5 eV
As a result, the beam diameter reduction as shown in FIG. 4 is achieved with the acceleration voltage V _acc = 30 keV. FIG. 4 is an explanatory diagram of beam diameter reduction by aberration correction. The vertical axis represents the beam diameter dp [nm] of the ion beam, and the horizontal axis represents the ion beam current Ip [pA]. The locus indicated by ● is a measured value, the curve f1 is an uncorrected theoretical value, and f2 is an aberration correction FIB (theoretical value). The acceleration voltage V _acc is 30 kV. From this figure, the following can be read.
a) Reduction of the beam diameter when the beam current Ip is the same can be read by comparing values parallel to the Y axis (vertical axis). Although the reduction ratio varies depending on the beam diameter, it is about 1/3 to 1/5.
b) The increase in beam current density when the beam diameter is the same can be read by comparing values parallel to the X axis (horizontal axis). Thereby, although the beam current density increase rate varies depending on the beam diameter, it is estimated to be about 8 to 20 times. The rate of increase in current density is proportional to the square of the inverse of the reduction rate.

FIG. 5 shows a typical potential distribution and ion trajectory in the entire FIB column region when the above performance is obtained in this embodiment. FIG. 5 is a diagram showing a typical potential distribution and ion trajectory in the lens optical system aberration correction FIB apparatus. The upper row shows X and Y trajectories, the middle row shows the axial potential, and the lower row shows the multipole field strength. In the on-axis potential and the multipole field strength, the horizontal axis indicates the length in the Z direction. In the on-axis potential, the vertical axis indicates [kV], in the multipole field strength, the solid line indicates the quadrupole strength [10 V / mm ² ], and the broken line indicates the octupole strength [0.05 V / mm ⁴ ].

According to this embodiment, the resolution and current density can be increased.
(Embodiment 2)
As an example of an FIB apparatus equipped with an electrostatic aberration correction apparatus, FIG. 6 shows a projection type two-lens optical system ion lithography apparatus. 6, the same components as those in FIG. 2 are denoted by the same reference numerals. In the figure, 11 is an emitter, 12 is an extraction electrode disposed below the emitter 11, 13 is a focusing lens disposed below the extraction electrode 12, 28 is a beam aligner disposed below the focusing lens 13, and 35 is This is a stencil mask disposed below the beam aligner 28. The stencil mask 35 is provided in place of the current limiting aperture 14A.

  Reference numeral 29 denotes an aberration correction device arranged below the stencil mask 35, 15 denotes an objective lens arranged below the aberration correction device 29, and M denotes a sample arranged below the objective lens 15. Reference numeral 25 denotes an objective lens voltage power source for driving the objective lens 15, 30 denotes an aberration correction lens component voltage power source for driving the aberration correction device 29, 31A denotes an aberration correction device upper power source for driving the upper aberration correction device 29A, and 31B denotes This is the lower power source of the aberration correction device that drives the lower aberration correction device 29B.

  In this embodiment, the stencil mask 35 is placed between the emitter 1 and the electrostatic aberration corrector 29, but is not necessarily placed at this position. For example, the stencil mask position may be under the objective lens 15. It should be noted that the role of each lens varies depending on the position of the stencil mask. That is, when the stencil mask position is provided between the emitter 11 and the electrostatic aberration corrector 29, the focusing lens 13 must be controlled so as to form a crossover at the stencil mask position. In the case below the lens 15, the objective lens 15 must be controlled to focus at the stencil mask position, not on the sample M.

In FIG. 6, the deflector is omitted to emphasize that it is not necessary in the projection lithography apparatus. However, in the actual apparatus, it is not always necessary to remove the deflector for the following reason.
1) In order to determine the quality of an apparatus related to an optical system, it is necessary to produce an image.
2) A normally used two-stage swing-back deflector is often used as a beam aligner.

According to this embodiment, it is possible to perform drawing with high resolution using the drawing stencil mask.
(Embodiment 3)
According to the theoretical detailed examination when the all-electrostatic aberration correction apparatus is mounted on the two-lens FIB apparatus, the optical performance and ease of use are obtained in the configuration of the lens barrel as shown in the first and second embodiments. From the point of view, it was found that there was a problem. In the third and fourth embodiments, a method for dealing with the problems in the first and second embodiments will be described. Here, a countermeasure for the following problems in the first and second embodiments is given.
1) Reduction of a Gaussian image reflecting the size of a virtual light source that restricts the reduction of the beam diameter in the small beam current region. The Gaussian image size d _G is expressed by the following equation where the magnification of the system is m and the size of the virtual light source is do. d _G = m · do
2) Optimization of the beam current limiting aperture diameter and the beam incident angle on the sample to reduce the influence of the fifth-order aperture aberration that limits the beam diameter reduction in the large beam current region.
3) Introduction of a simple and highly accurate beam alignment method.
4) Provision of means capable of automatic beam alignment that can distinguish aberrations of different orders.

In the third embodiment, a method capable of handling the above items 1) and 2) is shown, and in the fourth embodiment, a method capable of dealing with the preceding items 1) to 4) is shown.
As the third embodiment, a three-lens scanning focused ion beam device equipped with an electrostatic aberration correction device as shown in FIG. 7 is used. 7, the same components as those in FIGS. 2 and 6 are denoted by the same reference numerals. In the figure, 11 is an emitter that emits ions, 12 is an extraction electrode disposed below the emitter 11, 13 is a focusing lens (CL1) disposed below the extraction electrode 12, and 28 is a lower portion of the focusing lens 13. 14A is a movable current limiting diaphragm disposed below the beam aligner 28, and 40 is a second focusing lens (opening angle control lens, condenser) disposed below the movable current limiting diaphragm 14A. (Also referred to as a lens) (CL2), 41 is a drift space provided below the second focusing lens 40, and 29 is an aberration correction device disposed below the drift space 41. The upper aberration correction device 29A and the lower aberration And a correction device 29B.

16 is a deflector (deflector) disposed at the lower part of the aberration correction device 29, 15 is an objective lens disposed at the lower part of the deflector 16, and M is a sample disposed at the lower part of the objective lens 15. The major difference between the first embodiment and this embodiment is that the second condenser lens (opening angle control lens) (CL2) 40 is provided immediately below the movable current limiting diaphragm 14A, and the opening angle control. The drift space 41 is provided below the lens 40. The drift space 41 is a simple space of about several tens of millimeters, and is not always necessary to obtain the target performance. However, the drift space 41 has the following two advantages.
1) The required maximum voltage of the opening angle control lens (CL2) 40 can be reduced.
2) The drive voltage of various correction elements of the aberration correction device 29 can be reduced.

The operation of the apparatus configured as described above will be described below.
a) Operation in a small current region When the FIB apparatus is used for acquiring a SIM (Scanning Ion Microscope) image, the beam current is made small. The factor that limits beam diameter reduction when such a beam current is in the region of several pA is the size of the virtual light source (Gaussian image). Therefore, resolution improvement in a small current region can only be achieved by realizing high “Demagnification”. This means that a second stage for “Demagnification” is needed.

In the present embodiment, the opening angle control lens 40 creates a crossover before the collector (all electrostatic focused ion beam device). In the region where most of the current is limited by the movable current limiting aperture (aperture) 14A of the opening angle control lens 40 and only a current of about several pA flows, the space charge effect due to crossover does not become a big problem.
b) Operation in a large current region When the FIB apparatus is used for processing, the beam current is increased in order to improve the throughput. The situation in such a current region is different from that in the small current region. The performance limiting element here includes not only the size of the virtual light source but also emitter luminance and fifth-order aberration. Theoretical studies have shown that performance improvements in this current region can be achieved only by a significant reduction in fifth order aberrations.

According to this embodiment, ion beam irradiation can be performed while reducing aberrations.
(Embodiment 4)
As a fourth embodiment, a three-lens system focused ion beam apparatus equipped with an electrostatic aberration correction apparatus as shown in FIG. 8 is shown. The same components as those in FIG. 7 are denoted by the same reference numerals. The major difference between the apparatus shown in the third embodiment and this apparatus is that one stage of x, y is provided in the drift space under the opening angle control lens 40 for high-precision axis alignment mechanism and automatic aberration correction. The deflection system (beam aligner in the figure) 45 is arranged. In FIG. 8, the two-stage swing-back electrostatic deflector 28 above the movable current limiting aperture 14A is the beam aligner 1, and the electrostatic deflector 45 below the opening angle control lens 40 is the beam aligner 2. Other configurations are the same as those in FIG.

In the apparatus configured as described above, in order to perform adjustment of the aberration correction apparatus, knowledge of aberration is generally required, and a long adjustment time may be required. In order to avoid such a problem, it is necessary to provide an apparatus capable of automatic aberration correction. However, there are two important problems when doing this:
1) It is possible to distinguish aberrations of different orders from the SIM image.
2) Establishment of a reliable detection method for higher-order aberrations.

  In this embodiment, by introducing a new deflection system between the movable current limiting diaphragm 14A and the collector, it is possible to tilt the beam with respect to the virtual light source while creating a series of images having a large virtual aperture angle. If such a thing is performed with a series of tilt angles and defocused and astigmatism images are analyzed, it becomes possible to measure all aperture aberrations. Different orders of aberration can be distinguished from each other by using different tilt angles.

  If only the aberration below the movable current limiting diaphragm 14A is important (small current region), the first stage is above the movable current limiting diaphragm 14A and the second stage is below the movable current limiting diaphragm 14A. A virtual aperture can be formed by deflecting the beam (see the upper part of FIG. 9). FIG. 9 is a diagram showing the principle of virtual aperture shift for automatic aberration measurement and automatic aberration correction. The state of the aperture deflection at the first deflection fulcrum of the beam aligner (1), the second deflection fulcrum of the beam aligner (1), the aperture position, and the deflection fulcrum of the beam aligner (2) is shown.

  The virtual aperture must be present in the emitter 11 when the contribution of the emitter 11 to the aberration is large, as is the case with the large current region. Therefore, a two stage deflection system must be used with the newly introduced deflection system as shown in the lower part of FIG.

  Even if emitted to an angular region of a certain size, the beam reaching the sample passes through all important optical elements. The contribution to the aberration of the entire aperture angle control lens 40 located near the aperture (movable stop), through which the beam always passes near the center, is generally negligible.

  Similarly, the alignment method can be simplified by adding a new deflection system. In the current column, the aperture must be mechanically adjusted only above the collector center. Therefore, when the aperture diameter (aperture number) is changed, readjustment of the aperture position is often required due to the poor mechanical position reproducibility and the requirement for accurate mechanical alignment during aberration correction. However, with the introduction of a new deflection system, readjustment after exchanging the aperture diameter can be easily realized with an electrical virtual virtual shift.

  Now, the beam diameter when a drift space having a length of 100 mm is provided in a standard three-lens optical system FIB apparatus will be compared with the beam diameter in the first embodiment. The calculation conditions are the same as those in the first embodiment. FIG. 10 is a diagram showing a comparison of reaching beam diameters between the first embodiment and the fourth embodiment.

  From this figure, it can be seen that the presence of the aperture angle control lens CL2 improves the beam diameter only by 1 pA in the small current region, and the effect is small in the large current region. This is because the optimized aperture diameter at each current is used. The existence value of the opening angle control lens CL2 in the large current region is when the beam current is different from the beam current defined by the optimum aperture diameter.

This is shown in FIG. FIG. 11 is a diagram showing a comparison between the two- and three-lens optical systems of the beam diameter dp-current Ip characteristics at the time of aberration correction. The vertical axis represents the beam diameter dp [nm], and the horizontal axis represents the ion beam current Ip [pA]. A circle indicates a three-lens optical system, and a circle indicates a two-lens optical system. The case where the acceleration voltage V _acc = 30 kV is shown. At this time, the aperture diameter is optimized with a beam current of 10 nA. Thus, the effect of the opening angle control lens CL2 can be seen even in a large current region. That is, if several types of aperture diameters are prepared, it is possible to realize a beam diameter under an optimum condition with an arbitrary current.

According to this embodiment, it is possible to provide an aberration-corrected focused ion beam apparatus that realizes the maximum resolution and the maximum beam current density, and the aberration correction that has been considered to be very difficult to adjust is automatically performed. An executable device can be provided.
(Embodiment 5)
In the fifth embodiment, the third embodiment is used as a projection type aberration correction ion lithography apparatus.

According to this embodiment, beam drawing can be performed with high accuracy using a drawing stencil mask.
(Embodiment 6)
In the sixth embodiment, the fourth embodiment is used as a projection type aberration correction ion lithography apparatus.

According to this embodiment, an ion lithography apparatus capable of automatically performing aberration correction can be provided.
FIG. 12 is a diagram showing calculated beam diameters that can be reached in the present invention. This figure compares the acceleration voltage _Vacc , beam current, and maximum current density with the two-lens, three-lens optical system of the present invention and a typical conventional FIB beam diameter. It can be seen that the 3-lens optical system is superior in all respects.

From the above results, it can be seen that the focused ion beam apparatus equipped with the all-electrostatic aberration correction apparatus has the following effects.
1) Since 1997, the performance limit of the focused ion beam apparatus mounted on Ga-LMIS, which has been stagnant, can be significantly exceeded.
2) The low acceleration voltage FIB device that has been sought in recent years can be realized without degrading the performance at the current 30 kV.
3) The realization of large current and high current density opens up the possibility of realizing a single lens barrel ion lithography apparatus.
4) Automatic adjustment of the FIB apparatus, which is generally recognized as difficult, and automatic aberration correction can be realized.

It is a figure which shows the structural example of a 2 lens optical system focused ion beam apparatus. It is a figure which shows the structural example of the scanning-type focused ion beam apparatus which mounts a 2 lens optical system aberration correction apparatus. It is a figure which shows the typical beam orbit at the time of aberration correction. It is explanatory drawing of reduction of the beam diameter by aberration correction. It is a figure which shows the typical potential distribution and ion trajectory in a lens optical system aberration correction FIB apparatus. It is a figure which shows the structural example of the projection type 2 lens optical system ion lithography apparatus carrying an aberration correction apparatus. It is a figure which shows the structural example of the 3 lens type | system | group scanning-type focused ion beam apparatus carrying an all-electrostatic type aberration correction apparatus. It is a figure which shows the structural example of the 3 lens type | system | group focused ion beam apparatus which mounts the beam aligner between the opening angle control lens and the aberration correction apparatus. It is a figure which shows the principle of the virtual aperture shift for automatic aberration measurement and automatic aberration correction. It is a figure which shows the comparison of the arrival beam diameter of Embodiment 1 and Embodiment 4. FIG. It is a figure which shows the comparison of the 2 and 3 lens optical system of the beam diameter dp-current Ip characteristic at the time of aberration correction. It is a figure which shows the beam diameter calculation value which can be reached | attained by this invention. It is a conceptual diagram of the optical system FIB apparatus of 2 lenses and 3 lenses. It is a figure which shows the comparison of the 2 and 3 lens optical system of beam diameter dp-current Ip characteristic.

Explanation of symbols

11 Emitter (ion source)
12 Extraction electrode 13 Focusing lens (CL2)
14A Movable Current Limiting Aperture 15 Objective Lens 16 Deflector 28 Beam Aligner (1)
29 Aberration corrector 29A Upper aberration corrector 29B Lower aberration corrector 45 Beam aligner (2)
M sample

Claims (6)

  An ion source that emits ions, an extraction electrode that extracts an ion beam from the ion source, a gun lens that includes a condenser lens that controls the opening angle of the extracted ion beam, and a relatively wide radiation angle generated from the ion source Current limiting diaphragm for extracting an ion beam having a specific radiation angle from an ion beam having a chromaticity, an electrostatic aberration correction device for correcting chromatic aberration and spherical aberration, and an electrostatic objective lens for focusing the ion beam on a sample. A two-lens optical system scanning-type aberration-corrected focused ion beam apparatus comprising a deflector configured to scan a focused ion beam in a two-dimensional direction on a sample.   An ion source that emits ions, an extraction electrode that extracts an ion beam from the ion source, a gun lens that includes a condenser lens that controls the opening angle of the extracted ion beam, an electrostatic aberration that corrects chromatic aberration and spherical aberration A correction device, which is arranged in the order of an electrostatic objective lens for focusing the ion beam on the sample, and further comprises a drawing stencil mask placed somewhere between the optical elements or under the objective lens. Two-lens optical system projection type aberration correction ion lithography apparatus.   An ion source that emits ions, an extraction electrode that extracts an ion beam from the ion source, a gun lens that includes a condenser lens that controls the opening angle of the extracted ion beam, and a relatively wide radiation angle generated from the ion source A current-limiting aperture for extracting an ion beam having a specific radiation angle from an ion beam having an electrostatic opening angle control lens capable of controlling the opening angle without changing the current amount of the ion beam that has passed through the current-limiting aperture, Electrostatic aberration correction device for correcting chromatic aberration and spherical aberration, deflector arranged in order of electrostatic objective lens for focusing the beam on the sample, and further deflecting the focused ion beam in a two-dimensional direction on the sample A three-lens optical system scanning-type aberration-corrected focused ion beam device comprising:   On the current limiting diaphragm, an electrostatic beam that can independently deflect the ion beam in a two-dimensional direction between a two-stage swing-back electrostatic deflector, an electrostatic opening angle control lens, and an electrostatic aberration corrector. A three-lens optical system scanning-type aberration-corrected focused ion beam device including an electric deflector.   An ion source that emits ions, an extraction electrode that extracts an ion beam from the ion source, a gun lens that includes a condenser lens that controls the opening angle of the extracted ion beam, and an electrostatic opening angle that can be controlled A control lens, an electrostatic aberration correction device for correcting chromatic aberration and spherical aberration, and an electrostatic objective lens for focusing the ion beam on the sample, are arranged in this order, and somewhere between the optical elements or the objective lens A three-lens optical system projection-type aberration-correction ion lithography apparatus comprising a drawing stencil mask placed underneath.   An ion source that emits ions, an extraction electrode that extracts an ion beam from the ion source, a gun lens that includes a condenser lens that controls the opening angle of the extracted ion beam, a two-stage swing-back electrostatic deflector, Stencil mask for drawing, electrostatic opening angle control lens capable of controlling opening angle, electrostatic deflector capable of independently deflecting ion beam in two-dimensional X and Y directions, electrostatic aberration correcting chromatic aberration and spherical aberration A three-lens optical system projection type aberration correction ion lithography apparatus in which a correction apparatus and an electrostatic objective lens for focusing an ion beam on a sample are arranged in this order.

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