JP2000301353A - Ion milling method and apparatus - Google Patents

Abstract

(57) [Summary] [Issue] An ion which is capable of extracting a uniform and stable ion beam current from a large-diameter ion source electrode even when thermal deformation occurs in the large-diameter ion source electrode, thereby improving processing accuracy. An object of the present invention is to provide a milling method and an apparatus therefor. According to the present invention, in an ion source including a plasma chamber for converting an introduced gas into plasma and an ion source electrode for extracting ions from the plasma chamber, each electrode is divided as means for increasing the diameter. Each of the divided electrode blocks is combined and independent, and the gap formed between the divided adjacent blocks is closed with cross-shaped clamps 11, 12, and the accelerating electrodes 6, The gap between the deceleration electrodes 7 is connected by an insulating spacer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to ion milling of a workpiece using an ion source having at least two stacked electrodes for extracting ions and having a plurality of divided electrodes. The present invention relates to an ion milling method and an apparatus therefor.

[0002]

2. Description of the Related Art As measures for increasing the size and diameter of an ion source electrode in ion milling, Japanese Patent Publication No.
As described in JP-A-74901, a method of dividing an ion source electrode into two or more is known.

[0003]

However, in the above prior art, in order to cope with the enlargement (larger diameter) such as the detailed structure in the basic structure of the ion source electrode, the combination structure of the electrodes and the elimination of the thermal influence are required. There was a lack of consideration in this regard. In particular, the ion beam extraction current becomes non-uniform due to the thermal deformation applied to the ion source electrode due to the filament accompanying the enlargement (larger diameter) and the radiant heat supplied to the ion source electrode from the arc power supply, and between the electrodes. However, there is a problem that the insulation is deteriorated due to spatter adherence (fouling) to the insulating spacer.

[0004] An object of the present invention is to solve the above problems.
Provided is an ion milling method and an apparatus for improving the processing accuracy by enabling uniform and stable extraction of an ion beam current from a large-diameter ion source electrode even when thermal deformation occurs in the large-diameter ion source electrode. It is in. Also,
Another object of the present invention is to provide an ion milling method and an apparatus for improving the processing accuracy by preventing unnecessary workpieces from being irradiated with unnecessary ion beams from a large-diameter ion source electrode. It is in. Still another object of the present invention is to provide a large-diameter ion source electrode in which a reduction in insulation due to spatter adherence (contamination) to an insulating spacer between the electrodes is reduced, and a cycle of operations such as replacement or cleaning of the ion source electrode. It is an object of the present invention to provide an ion milling method and an apparatus therefor which have a prolonged length.

[0005]

In order to achieve the above object, the present invention relates to a plate-like accelerating electrode formed by arranging a plurality of blocks divided so as to make the individual temperature rise and thermal deformation independent. A plate-shaped deceleration electrode formed by arranging a plurality of blocks divided so as to make the temperature rise and thermal deformation independent is arranged to face each other with a desired gap formed, and at least formed between the blocks in the acceleration electrode Using an electrode configured to close the gap with a holding metal, ions converted into plasma in the plasma chamber are narrowed down by each of a large number of holes formed in each block of the accelerating electrode, and the narrowed ion beam is further irradiated with the ion beam. It is characterized in that it is pulled out through each of a large number of holes formed in each block of the deceleration electrode and is irradiated on the workpiece in the sample chamber to perform ion milling. An ion milling method to. Further, the present invention provides a plate-shaped accelerating electrode configured by arranging a plurality of blocks divided so as to make each temperature rise and thermal deformation independent, and a plurality of blocks divided so as to make each temperature rise and thermal deformation independent. A plate-shaped deceleration electrode formed by arranging them is arranged to face each other while forming a desired gap, and each of a gap formed between blocks in the acceleration electrode and a gap formed between blocks in the deceleration electrode is Using an electrode configured to be closed with a pair of holding members, ions converted into plasma in the plasma chamber are narrowed down by each of a large number of holes formed in each block of the accelerating electrode. It is pulled out through each of the many holes formed in each block of the deceleration electrode and irradiated on the workpiece in the sample chamber for ion milling. It is an ion milling method comprising.

Further, the present invention is characterized in that in the above-mentioned ion milling method, the workpiece is rotated around a central portion of the electrode as an axis. In addition, the present invention provides a plasma chamber for converting an introduced inert gas such as Ar gas into plasma, a stage on which a workpiece is mounted, a sample chamber which is evacuated, and a plurality of divided blocks. A plate-shaped acceleration electrode formed side by side and a plate-shaped deceleration electrode formed by arranging a plurality of divided blocks are arranged so as to face each other with a desired gap formed therebetween, and the ionized plasma is formed in the plasma chamber. An electrode which is drawn out through each of a large number of holes formed in each block of the acceleration electrode and each block of the deceleration electrode and irradiates a workpiece in the sample chamber to perform ion milling. It is a milling device. In addition, the present invention provides a plasma chamber for converting an introduced inert gas such as Ar gas into plasma, a stage on which a workpiece is mounted, a sample chamber which is evacuated, and a plurality of divided blocks. A plate-shaped acceleration electrode formed by arranging a plurality of divided blocks and a plate-shaped deceleration electrode formed by arranging a plurality of divided blocks are arranged so as to face each other with a desired gap therebetween, and are formed between blocks in the acceleration electrode. Each of the gap and the gap formed between the blocks in the deceleration electrode is closed by a pair of presser fittings, and the plasma-formed ions are formed in each block of the acceleration electrode and each block of the deceleration electrode in the plasma chamber. An electrode for performing ion milling by irradiating the workpiece through the plurality of holes and irradiating the workpiece in the sample chamber with the electrode. It is a ring processing equipment.

Further, the present invention provides a plasma chamber for converting an introduced inert gas such as Ar gas into a plasma, a sample chamber having a stage on which a workpiece is mounted, and being evacuated,
A disk-shaped accelerating electrode formed by arranging a plurality of blocks circumferentially divided around the center in the circumferential direction, and a plurality of blocks divided circumferentially around the center in the circumferential direction A disc-shaped deceleration electrode arranged side by side is arranged facing each other to form a desired gap, and at least a gap formed between the blocks in the acceleration electrode is closed with a presser fitting, and is formed in the plasma chamber. An electrode for drawing ionized plasma through each of a large number of holes formed in each block of the acceleration electrode and each block of the deceleration electrode and irradiating the workpiece in the sample chamber with an ion milling process. An ion milling apparatus characterized in that: The present invention also provides a plasma chamber for converting an introduced inert gas such as Ar gas into a plasma, a stage on which a workpiece is mounted, a sample chamber to be evacuated, and a circle centered on the center. A disk in which a plurality of blocks divided in the circumferential direction are arranged in the circumferential direction and a disk-shaped acceleration electrode and a plurality of blocks divided in the circumferential direction around the central portion are arranged in the circumferential direction. And a deceleration electrode having a desired shape are formed so as to face each other with a desired gap formed therebetween, and each of the gap formed between the blocks of the acceleration electrode and the gap formed between the blocks of the deceleration electrode is formed by a pair of presser fittings. The sample is constructed by closing and drawing out plasma-formed ions in the plasma chamber through each of a number of holes formed in each block of the acceleration electrode and each block of the deceleration electrode. By irradiating the workpiece inner is an ion milling apparatus characterized by comprising an electrode subjected to ion milling.

Further, the present invention is characterized in that, in the above-mentioned ion milling apparatus, the metal holding member is formed in a rib shape. Further, the present invention is characterized in that, in the ion milling apparatus, each block of an acceleration electrode and each block of a deceleration electrode are connected to each other by a plurality of insulating spacers at a central portion of the electrode. Also,
The present invention is characterized in that in the ion milling apparatus, the insulating spacer is formed so as to have a protrusion on an outer periphery. Further, according to the present invention, in the ion milling apparatus, the material of the insulating spacer is alumina, SiO _2, or glass macor. In addition, the present invention accurately measures the gap between the accelerating electrode and the decelerating electrode using a laser inclination sensor that is appropriately tilted, and optimizes the degree of tightening of the gap spacing adjusting spacer based on the obtained measurement result. By doing so, the gap after assembling the electrodes is kept constant.

As described above, according to the above configuration,
In a large-diameter ion source electrode, the gap formed between each divided block from one side or both sides of the accelerating electrode and the decelerating electrode, which are two stacked, is closed and closed with, for example, a cross-shaped press fitting. Thus, the thermal deformation of each block of the ion source electrode can be held in a uniform direction by acting in a uniform direction. As a result, a large number of holes formed in the acceleration electrode for extracting ions and the deceleration electrode are formed. The gap formed between the accelerating electrode and the decelerating electrode can be kept constant, and the directionality of the ion beam emission can be kept constant. In addition, it is possible to draw out an ion beam current that is uniform and has stable discharge characteristics, thereby improving the fine processing accuracy of ion milling. Also,
In the case of a large-diameter ion source electrode, the two electrodes of the central part (the central part of the combined electrode) of the two accelerating electrodes and the decelerating electrodes arranged for each block are connected by insulating spacers. It is possible to prevent displacement of a hole for extracting ions due to thermal deformation of the beam extraction portion of the electrode.

In mass production of ion milling, if the ion source becomes contaminated, it is necessary to remove the electrode from the apparatus and clean it. In this case, the electrode is disassembled, and each component is cleaned and reassembled. However, after reassembly, the gap between the electrodes often changes compared to that before cleaning. However, in the present invention, it is possible to accurately measure by using a CCD laser displacement sensor in which the gap interval after reassembling the electrodes is appropriately inclined,
By optimizing the degree of tightening of the gap spacing adjusting spacer based on the measurement results, the gap spacing can be made the same as before assembling, and as a result, the amount of extracted ions does not change and the processing amount is stabilized. It becomes possible.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an ion source, an ion beam processing apparatus and a method thereof according to the present invention will be described with reference to the drawings. FIG. 1 is a front view and a plan view showing a first embodiment of a divided ion source electrode used in the ion source according to the present invention, and FIG. 2 is a divided ion source electrode used in the ion source according to the present invention. FIG. 3 is a front view showing a second embodiment of the source electrode, FIG. 3 is a rear view of FIG.
FIG. 4 is a detailed view of a central portion showing a second embodiment of a divided ion source electrode, FIG. 5 is a sectional view taken along the line BB of FIG. 4, and FIG. 6 shows an ion source according to the present invention. FIG. 7 is a side sectional view showing a schematic configuration of an embodiment of an ion beam processing apparatus provided with the ion beam processing apparatus, and FIG. 7 is a sectional view showing a part of an ion source electrode in an enlarged manner.

As shown in FIG. 6, a plurality of filaments 2 are installed in a plasma chamber 1 symmetrically with respect to the center axis of the electrode in order to generate a high-density plasma having a uniform density over the electrode 5. A gas inlet 4 for introducing an inert gas such as an argon gas for conversion into a gas is provided. Note that the current introduction terminal 3 conducts a current to heat the filament 2. As described above, in the plasma chamber 1, discharge is performed in the plurality of filaments 2 with respect to the inert gas such as Ar gas introduced from the gas introduction port 4 to generate a high-density plasma 20 having a uniform density. become. Then, the generated plasma 20 is applied to the plasma chamber 1.
Along the side wall and the upper wall of the plasma chamber 1 from the N-pole to prevent it from hitting the side wall and the upper wall of the plasma chamber 1 and disappearing.
A magnet that generates a magnetic field to the poles (permanent magnets may be used) 2
1 are juxtaposed on the outside of the side wall and the upper wall of the plasma chamber 1. That is, the plasma is confined in the plasma chamber 1 by the magnetic field generated from the magnets 21 arranged outside the side walls and the upper wall of the plasma chamber 1, and the high-density and uniform plasma 20 is generated. .

Further, on the lower surface of the plasma chamber 1, an electrode 5 composed of an acceleration electrode 6 and a deceleration electrode 7 is provided mounted on an electrode holder 36. As shown in FIG. 7, the electrode 5 has approximately 4000 to 6000 holes 22 and 23 for injecting Ar ions two-dimensionally arranged at an equal pitch, and is divided into a plurality (for example, four in a cross shape). An accelerating electrode 6 for accelerating and decelerating ions and a decelerating electrode 7 are provided between the insulating spacers 8 formed of ceramics, insulators, or the like.
a, 8b, 8c, 13 gap 40 of about 2-3 mm
While being fixed to the electrode support fitting 9.
The acceleration electrode 6 and the deceleration electrode 7 are made of a material such as Mo, W, Ta, or carbon having a thickness of about 1 to 3 mm. A positive potential is applied to the accelerating electrode 6 by a power supply 25 to reduce Ar ions in the plasma from 4000 to 600.
A role of narrowing (focusing) into about 0 holes 22 is that a negative potential is applied to the deceleration electrode 7 by the power supply 23 so that the ion beam narrowed down into about 4000 to 6000 holes 22 is reduced. It serves to irradiate the workpiece 35 with a substantially parallel ion beam extracted from each hole 23. As described above, since the negative potential applied to the deceleration electrode 7 is higher than the positive potential applied to the acceleration potential 6, the narrowed ion beam is substantially parallel from the holes 23 of the deceleration electrode 7. It will be emitted. Note that the current flowing through the acceleration electrode 6 is larger than the current flowing through the deceleration electrode 7. By the way, the amount of processing of the workpiece by the ion beam emitted in a substantially parallel state from each hole 23 of the deceleration electrode 7 is substantially proportional to the product of the potential applied to both electrodes and the difference between the currents flowing through both electrodes. Will be. The above hole 2
The diameters of 2 and 23 are formed in the order of 2 to 4 mm, and if the diameter becomes smaller, the diameter of the ion beam emitted from each hole 23 becomes smaller.

Next, the sample chamber 30 will be described. In the sample chamber, there are a plurality of rotating stages 33 that rotate so that the workpiece 35 is placed and rotate, and a plurality of rotating stages 32 that are installed and rotate so as to revolve. A stage means 31; a shutter means 36 for turning on / off the emission of the ion beam to the workpiece; an exhaust pump 37 connected to the sample chamber 30 to evacuate the sample chamber; An ion current measuring device 38 composed of a Faraday cup measuring the ion current emitted from the electrode 5 and a processing amount detector 39 monitoring the processing amount processed by the ion beam emitted from the electrode 5. You. Therefore, by heating the plurality of filaments 2, the plasma chamber 1 is heated.
The plasma 20 is generated in the
The workpiece is irradiated with a number of parallel ion beams to start ion milling. When the processing is stopped, the shutter means 36 is closed. In addition, the ion current measuring device 38
Can measure the ion current emitted from the electrode 5 based on the measured ion current. The voltage or current applied to the acceleration electrode 6, the voltage or current applied to the deceleration electrode 7, or the plasma chamber is measured based on the measured ion current. The desired ion current can be obtained by controlling the amount of the inert gas introduced into 1. Further, since the processing amount can be monitored by the processing amount detector 39, the shutter means 36 can be controlled according to the monitored processing amount.

Incidentally, the ion source electrode 5, ie, the acceleration electrode 6 and the deceleration electrode 7, have a large diameter due to an increase in the number of processed workpieces of the ion beam processing apparatus and an increase in the size of the processing substrate. (1) The electrode material may not be able to be obtained with one sheet of material, and (2) The increase in the radiant heat of the filament of the ion source may cause a large amount of deformation with one electrode, making uniform fine processing impossible. 1 and 3, a plane perpendicular to the ion beam 24 to be accelerated is divided into a plurality (for example, four in a cross shape) as shown in FIGS. Further, each of the divided blocks of the acceleration electrode 6 and the deceleration electrode 7 is configured so that the divided electrodes 6a to 6d and 7a to 7d (shown as 7) are combined to maintain an independent state. Is done. Since the gap 42 is formed with a gap of about 1 to 2 mm between the blocks adjacent to the plurality of divided electrodes, the electrodes of each block are made independent by the gap. In order to assemble the electrodes, the ring-shaped electrode support metal 9 is placed on the lower surface, and the divided acceleration electrodes 6a to 6d and deceleration electrodes 7a to 7d are installed thereon, and the gap 40 is held therebetween. Insulation spacer 8
a, 8b, 8c and 13 are arranged. Therefore, the divided acceleration electrodes 6a to 6d and deceleration electrodes 7a to 7d
The peripheral portion d is semi-fixed and supported on the ring-shaped electrode support 9 so as to be finely movable in the radial direction.

That is, the gap 40 between the accelerating electrode 6 and the decelerating electrode 7 is held by about 2 to 4 insulating spacers 8a for each divided block in the peripheral portion of the electrode, and divided in the central portion of the radius. The gap 40 between the accelerating electrode 6 and the decelerating electrode 7 is held by about 3 to 5 insulating spacers 8b for each of the divided blocks, and the central portion has one for each divided block as shown in FIG. The gap 40 between the accelerating electrode 6 and the decelerating electrode 7 is held by about two insulating spacers 8c and about two insulating spacers 13.
Further, it is arranged on the upper surface of the deceleration electrode 7 so as to be covered with a shield 10 formed of a ring-shaped quartz or ceramic material. The shield 10 functions to prevent the insulating spacer 8a disposed around the electrode from being soiled and to reduce the electric field with the ground side. In the acceleration electrode 6 and the deceleration electrode 7 configured as described above, the gap 42 formed between blocks adjacent to the plurality of divided electrodes is about 1 to 2 mm. 6a to 6d and 7a to 7d are in an independent state.

However, the central portion of the divided ion source electrode is most easily heated by thermionic electrons emitted from the filament 2 and receives a large amount of radiant heat, so that the temperature becomes the highest and is susceptible to thermal deformation. Become. Even in such a state, the slit-like gaps 42 between the divided blocks of the acceleration electrode 6 and the deceleration electrode 7 are formed in a rib shape from the plasma chamber side of the acceleration electrode 6 and the sample chamber side of the deceleration electrode 7 respectively. Even if the divided accelerating electrode 6 and decelerating electrode 7 belonging to each block are thermally deformed by being closed and supported by
Partial due to rigidity of 1 and 12 (part of divided side)
Is restrained, a considerable amount of deformation can be reduced in the divided acceleration electrode 6 and deceleration electrode 7. The center of the divided acceleration electrodes 6a to 6d and the center of the deceleration electrodes 7a to 7d are firmly clamped by the center of each of the holding members 11, 12, so that the center of the electrode and the holding member 11, 12 are fixed to each other. In particular, by fixing each of the plate-shaped reinforcing portions 11a and 12a to the center of each of the cross-shaped holding members 11 and 12 by welding or the like, the holding members 11 and 12 are fixed.
Can be increased in rigidity and can be firmly integrated. In addition, the case where the holding metal fittings 11 and 12 have four cross-shaped pieces corresponding to the gap 42 has been described, but a total of eight holding pieces may be provided by, for example, passing one piece to the center of each divided block.

Further, as shown in FIGS. 8 (a) and 8 (b), a shaft-like mounting means 53 made of ceramics, insulators or the like is used.
By making the mounting holes 51 and 52 in the peripheral portions of the holding metal fittings 11 and 12 to be elongated, the structure can absorb thermal deformation, so that the deformation of the divided electrodes 6 and 7 can be further reduced. As shown in FIG.
The gap between the accelerating electrode 6 and the deceleration electrode 7 does not occur between the acceleration electrode 6 and the deceleration electrode 7 without any misalignment.
There is no fluctuation of 0, and the luminous flux and current of the ion beam 24 emitted from the hole 23 of the deceleration electrode 7 are kept constant, so that fine processing is further facilitated. Here, the electrode gap 40
The relationship between (G) and the ion milling speed R when an inert gas such as Ar gas is used is represented by the following expression (1).

R∝ (1 / G) ² (Equation 1) Accordingly, the accelerating electrode 6 and the decelerating electrode 7 are divided into a plurality in the circumferential direction centering on the central portion, and the divided gap portions 50 are formed on both sides of the electrodes. Rib-shaped presser fitting 1 with rigidity
By keeping the gap G constant, for example, by restricting the deformation of the electrodes 6 and 7 by sandwiching them so as to close them with 1 and 12, the ion milling speed can be stabilized. Further, in the divided acceleration electrodes 5a to 5d and deceleration electrodes 6a to 6d, the central part was retracted by about 5 to 10 mm with respect to the peripheral part on the plasma chamber side, and thereby divided by a small number of insulating spacers 8b. Waveform deformation (unevenness deformation) at the center between the ribs of the holding members 11, 12 in the circumferential direction of the acceleration electrodes 6a to 6d and the deceleration electrodes 7a to 7d can be eliminated.
Further, the acceleration electrode 5 and the deceleration electrode 6 divided into each block are arranged in the divided portion (the portion shown in FIG. 4) at the center of the electrode, compared with the number of insulating spacers 8a arranged in the entire circumferential direction. The number of the insulating spacers 8c is small, and is directly affected by the radiant heat generated by the above-described flying element 2, and a hole shift occurs between the accelerating electrode 6 and the decelerating electrode 7 due to a temperature difference between the two electrodes.

According to our experiments, one batch is one batch.
After pulling out the ion beam for about 2 hours,
When the batch is continuously operated, the uniformity of the ion beam (the uniformity of processing) is considerably deviated, and the processing accuracy is initially ±
3.0% was satisfactory, but ± 6.0 in several experiments.
% And ± 8.0% sequentially, and it became clear that they did not reproduce uniformly. In order to deal with these problems, at least two insulating spacers 13 are arranged at the center of the divided ion source electrode for each block of the divided electrode as shown in FIGS. 4 and 5. In this manner, a hole having the same size as the electrode holes 22 and 23 is formed in the center of the acceleration electrode 6 and the deceleration electrode 7, and the insulating spacer 13 made of ceramic or insulator having the same radius as the holes is attached to both electrodes. By searching in the middle, it is possible to prevent the above hole deviation. As a material of the insulating spacer 13, a ceramic such as alumina or SiO ₂ is usually used. In particular, when glass macol (cuttable glass) is used, even if spatter is attached, it is easily cleaned using sandpaper or the like. There are advantages that can be.

Furthermore, by providing a circumferential projection 13a having a tapered cross section at the center of the insulating spacer 13 to increase the surface area, acceleration can be achieved when a sputter adheres to the surface of the insulating spacer 13. The circumferential projection 13a between the electrode 6 and the deceleration electrode 7 makes it difficult for dielectric breakdown to occur. In addition, in the electrode central part of each block of the ion source electrode, in order to be less susceptible to radiant heat and to reduce the thermal deformation of the electrode, as shown in FIGS. Closed at 15. In the first embodiment shown in FIG. 1, a case is shown in which each of the thin mask plates 14 and 15 is placed on each of the holding metal fittings 11 and 12. As described above, even if the accelerating electrodes 6a to 6d and the decelerating electrodes 7a to 7d are thermally deformed, they are absorbed in the radial direction by the semi-fixed support that is finely movable with respect to the electrode support fitting 9 in the peripheral portion, and Can be absorbed by the gap 42 between the electrode blocks, and the parts of the sides of the divided acceleration electrodes 6a to 6d and deceleration electrodes 7a to 7d have a cross shape.
Since the acceleration electrodes 6a to 6d and the deceleration electrodes 7a to 7d are not bent, the gap between the acceleration electrodes 6a to 6d and the deceleration electrodes 7a to 7d can be precisely formed. Can be maintained and the acceleration electrode 6
It is possible to prevent a misalignment between the hole 22 of the deceleration electrode 7 and the hole 23 of the deceleration electrode 7, to obtain a uniform beam distribution of the ion beam current, and to perform uniform and fine high-precision ion milling. Can be realized.

The gap 42 between the electrode blocks is
Since the crosspieces are closed by the holding members 11 and 12, unnecessary ion beams are not emitted from the vicinity of the gap 42. However, since the workpiece 35 is revolved by the rotary stage 32, the workpiece 35 is revolved in total. It is possible to realize uniform and fine high-precision ion milling on the workpiece 35. Further, since the rotating stage 33 is also rotated, the plasma density generated in the plasma chamber 1 varies in the radial direction, and changes in the ion beam current (the energy density of the ion beam) emitted from the electrode 5 in the radial direction. However, since the rotary stage 33 is also rotated, it is possible to perform a uniform and fine ion milling process on the workpiece 35 as a whole with high precision. It is necessary to form a film having etching resistance corresponding to the ion milling pattern on the workpiece 35 before performing the ion milling process. After the ion milling process, it is necessary to remove this film.

As described above, since thermal deformation of the electrode can be prevented, misalignment between the hole 22 formed in the acceleration electrode 6 and the hole 23 formed in the deceleration electrode 7 shown in FIG. And the gap 40 between the acceleration electrode 6 and the deceleration electrode 7 can be prevented from fluctuating, so that the ion beam 24 focused in the hole 22 of the acceleration electrode 6 hits the deceleration electrode 7 and is sputtered. Can be prevented, and as a result, the insulating spacers 8a, 8b, 8
It is possible to reduce the frequency of breakdown between the electrodes due to the contamination of c and 13 and the adhesion of sputters, and it has become possible to realize a stable ion source electrode. In particular,
Since the diameter of the ion source electrode 5 can be increased,
The rotary stages 32 and 33 are enlarged, and a large number of workpieces are mounted on the rotary stage 33 to realize simultaneous large-volume processing, thereby improving the productivity of ion milling, and furthermore, fine ion milling. Processing can be realized.

Next, a description will be given of an embodiment of an inspection as to whether a desired gap 40 is obtained by measuring a gap between electrodes after assembling an electrode as an ion source according to the present invention. FIG. 9 shows an embodiment of the measuring device for the gap between the electrodes. The inter-electrode gap measuring device includes an optical surface plate 51 for fixing the ion milling electrode 5 and a stage 53 for moving a laser displacement sensor 52. The laser displacement sensor 52 includes an LD (laser diode) 521, a lens 522, a lens 523, and a CCD 524 as shown in FIG. Here, the laser displacement sensor 52 is arranged at an inclination angle θ with respect to the electrode surface. It is appropriate that the inclination angle θ is about 15 °. By arranging the laser displacement sensor 52 at an angle, a part of the surface of the acceleration electrode 6 located below the deceleration electrode 7 can be irradiated with laser light, and the gap G between the two electrodes can be detected. It becomes possible. If the inclination angle θ of the laser displacement sensor 52 is inappropriate,
Since the laser light is no longer irradiated on the surface of the electrode 6 located on the lower surface, the position of the lower electrode 6 cannot be detected.

When the laser displacement sensor 52 is moved on the stage 53 in the direction shown in FIG. 10, the light emitted from the LD 521 is emitted in the order of the surface A of the deceleration electrode 7, the surface B of the acceleration electrode 6, and the surface C of the surface plate. . At this time, the return light from each surface is focused on A ', B', and C 'by the CCD 524. By detecting which position the CCD 524 focuses on, the distance between the laser displacement sensor 52 and the surface of the electrode can be measured. The specifications of the laser displacement sensor 52 are shown in (Table 1). As a light source, a semiconductor laser: 670 nm, output: 0.95 mW, spot diameter: φ
By using 70 nm, the reference distance (the surface of the laser displacement sensor and the electrode) is 80 mm, and the measurement range is ± 15 mm.
A resolution of μm is obtained.

[0026]

[Table 1]

The measurement conditions are shown in (Table 2). The measurement frequency is 50 Hz, the scanning speed (moving speed) of the laser displacement sensor is 10 mm / s, that is, the moving distance of the laser sensor is 0.2 mm / count, and the deceleration electrode 7 having an electrode hole diameter of 4 mm and the acceleration electrode The distance of No. 6 was measured. At this time, the position information from the CCD 524 is output as a potential difference.

[0028]

[Table 2]

FIG. 11 shows a measurement example of a metal block having a known step measured by the laser displacement sensor 52. The relationship between the metal step and the potential difference is a linear relationship,
It can be seen that unknown distance and step information can be obtained from the potential difference information of the laser displacement sensor.

FIG. 12 is a view showing the result of measuring the inter-electrode gap of the assembled electrodes by using a laser displacement sensor. Distance (gap) between deceleration electrode 7 and acceleration electrode 6
G can be measured with an accuracy of ± 10 μm. According to this method, the electrodes are disassembled, and the gap between the electrodes after reassembly is measured. If the value is different from the value before disassembly, the tightening of the holding metal fittings 11 and 12 or the insulating spacer 8 is performed.
It is possible to eliminate the difference in the gap between the electrodes before and after dismantling by exchanging a, 8b, 8c, 13 with new ones, and the like. As described above, the gap G between the accelerating electrode 6 and the decelerating electrode 7 is measured with an accuracy of ± 10 μm by using the laser displacement sensor 52, and based on the measurement result, the holding members 11, 1
2 to adjust the degree of tightening, or to set the insulating spacers 8a and 8
By making adjustments such as replacing b, 8c, and 13, it is possible to reduce the variation in the gap G between the electrodes to ± 3% or less. As a result, from the relationship of the above equation (1),
Variations in the ion milling speed R can be reduced to about ± 6% or less, and highly accurate ion milling can be realized.

[0031]

According to the present invention, the large-diameter ion source electrode is divided and made independent, and the gap between the divided electrode blocks is closed and held by the presser fitting, so that the thermal deformation of each block of the ion source electrode is achieved. Can be suppressed in a certain direction, and as a result, it is possible to extract an ion beam current with uniform and stable discharge characteristics, thereby achieving an effect of improving the fine processing accuracy of ion milling. Further, according to the present invention, the large-diameter ion source electrode is divided and made independent, and the gap between the divided electrode blocks is closed with a presser fitting and restrained, and the two electrodes are insulated at the center of the divided electrode. By connecting with a spacer, the thermal deformation of each block of the ion source electrode can be suppressed in a certain direction, and the displacement of the accelerating electrode and the central portion of the decelerating electrode due to the thermal deformation can be prevented. As a result, there is an effect that the ion beam current can be extracted uniformly and the discharge characteristics are stable and the precision of ion milling can be improved.

In particular, according to the present invention, by using a large-diameter ion source electrode, productivity can be improved by simultaneous large-volume processing, and fine ion milling can be realized. According to the present invention,
By accurately measuring the gap between the electrodes when assembling a large-diameter ion source electrode and adjusting the gap interval based on the measurement result, the interval can always be kept constant.

[Brief description of the drawings]

FIG. 1 is a front view and a plan view showing a configuration of a first embodiment of an ion source electrode used in an ion source according to the present invention.

FIG. 2 is a front view showing the configuration of a second embodiment of the ion source electrode used in the ion source according to the present invention.

FIG. 3 is a plan view showing the configuration of a second embodiment of the ion source electrode used in the ion source according to the present invention.

FIG. 4 is a central detailed view showing the configuration of a second embodiment of the ion source electrode used in the ion source according to the present invention.

FIG. 5 is a sectional view taken along line BB in FIG. 4;

FIG. 6 is a side sectional view showing a schematic configuration of an embodiment of the ion milling apparatus according to the present invention.

FIG. 7 is a cross-sectional view showing, on an enlarged scale, a part of an electrode in which a divided acceleration electrode and a divided deceleration electrode according to the present invention are arranged to form a desired gap and ions are extracted. is there.

FIG. 8 is a cross-sectional view showing one embodiment of a structure of a peripheral portion of an electrode including a press fitting according to the present invention.

FIG. 9 is a schematic view showing an embodiment of the inter-electrode gap measuring device according to the present invention.

10 is a diagram illustrating the principle of measuring the gap between electrodes by the laser displacement sensor shown in FIG. 9;

FIG. 11 is a diagram showing a relationship between a step and a potential difference obtained from a laser displacement sensor.

FIG. 12 is a diagram showing a measurement example of a gap between electrodes measured using a laser displacement sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Plasma chamber, 2 ... Filament, 3 ... Current introduction terminal, 4 ... Gas introduction port, 5 ... Electrode, 6 ... Acceleration electrode, 6a-
6d: each divided block in the acceleration electrode, 7: deceleration electrode, 7a to 7d: each divided block in the deceleration electrode, 8a, 8b, 8c: insulating spacer, 9: electrode support bracket, 10: shield member, 11 … Holding bracket, 12…
Presser fitting, 13: insulating spacer, 13a: circumferential projection,
14 ... mask, 15 ... mask, 20 ... plasma, 21 ...
Magnet, 25, 26 Power supply, 30 Sample chamber, 32 Rotary stage, 33 Rotary stage, 35 Workpiece, 36
Electrode holder, 37: Exhaust pump, 38: Ion current measuring instrument, 39: Processing amount detector, 52: Laser displacement sensor, 5
21 ... Laser, 524 ... CCD.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/3065 H01L 21/302 D (72) Inventor Shinji Sasaki 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa-pref. Inside Hitachi, Ltd., Production Technology Laboratory (72) Inventor Takako Okawa 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside Hitachi, Ltd. Production Technology Laboratory (72) Inventor, Kentaro Oishi 1-chome, Kokubuncho, Hitachi City, Ibaraki Prefecture No. 1-1 F-term in the Kokubu Plant of Hitachi, Ltd. (Reference) 4E066 AA00 BA13 BD03 BE05 BE08 4K057 DA11 DD04 DE14 DG16 DM12 DM23 DM24 DM35 DM38 5C030 DD05 DD06 DE04 DG09 5C034 BB09 CC01 CD02 5F004 AA16 BA13 BB01 BB24 BC08

Claims (11)

[Claims] A plate-shaped acceleration electrode formed by arranging a plurality of divided blocks and a plate-shaped deceleration electrode formed by arranging a plurality of divided blocks are arranged to face each other with a desired gap formed therebetween. Using an electrode configured by closing at least a gap formed between blocks in the acceleration electrode with a holding metal, each of a number of holes formed in each block of the acceleration electrode by plasma-generated ions in a plasma chamber. The ion beam is extracted by each of a number of holes formed in each block of the deceleration electrode, and irradiated to a workpiece in a sample chamber to perform ion milling. Milling method. 2. A plate-shaped acceleration electrode formed by arranging a plurality of divided blocks and a plate-shaped deceleration electrode formed by arranging a plurality of divided blocks are arranged to face each other with a desired gap. Using an electrode formed by closing each of the gap formed between the blocks in the acceleration electrode and the gap formed between the blocks in the deceleration electrode with a pair of presser fittings, ionizes the plasma-formed ions in the plasma chamber. Each of the holes formed in each block of the accelerating electrode is narrowed down by each of the holes, and the narrowed ion beam is drawn out through each of the holes formed in each block of the deceleration electrode, and the workpiece in the sample chamber is extracted. An ion milling process by irradiating the substrate with ion milling. 3. The ion milling method according to claim 1, wherein the workpiece is rotated around a center of the electrode as an axis. 4. A plate-like structure comprising a plasma chamber for converting introduced gas or the like into plasma, a stage on which a workpiece is placed, a sample chamber to be evacuated, and a plurality of divided blocks arranged side by side. The acceleration electrode and a plate-shaped deceleration electrode formed by arranging a plurality of divided blocks are arranged so as to face each other with a desired gap formed therebetween, and ions converted into plasma in the plasma chamber are converted into blocks of the acceleration electrode and An electrode for drawing out through each of a large number of holes formed in each block of the deceleration electrode and irradiating a workpiece in the sample chamber to perform an ion milling process. 5. A plate-like structure comprising a plasma chamber for converting introduced gas or the like into plasma, a stage on which a workpiece is mounted, a sample chamber to be evacuated, and a plurality of divided blocks arranged side by side. The acceleration electrode and a plate-shaped deceleration electrode formed by arranging a plurality of divided blocks are arranged so as to face each other with a desired gap, and the gap formed between the blocks in the acceleration electrode and the deceleration electrode Each of the gaps formed between the blocks is closed with a pair of presser fittings, and each of a number of holes formed in each block of the accelerating electrode and each block of the decelerating electrode is formed by ionizing the plasma-formed ions in the plasma chamber. An electrode for performing ion milling by irradiating a workpiece in the sample chamber with the workpiece and irradiating the workpiece in the sample chamber. 6. A plasma chamber for converting an introduced gas or the like into plasma, a stage on which a workpiece is mounted, and a sample chamber to be evacuated and evacuated, are divided in a circumferential direction around a central portion. A disk-shaped acceleration electrode formed by arranging a plurality of blocks in the circumferential direction and a disk-shaped deceleration electrode formed by arranging a plurality of blocks divided in the circumferential direction around the center portion in the circumferential direction. A desired gap is formed and arranged to face each other, at least a gap formed between the blocks in the acceleration electrode is closed by a presser fitting, and ions converted into plasma in the plasma chamber are formed in each block of the acceleration electrode. An electrode for drawing out through each of a number of holes formed in each block of the deceleration electrode and irradiating the work in the sample chamber with an ion milling process. Ion milling apparatus. 7. A plasma chamber for converting an introduced gas or the like into a plasma, a stage on which a workpiece is placed, and a sample chamber to be evacuated and evacuated, are divided in a circumferential direction around a central portion. A disk-shaped acceleration electrode formed by arranging a plurality of blocks in the circumferential direction and a disk-shaped deceleration electrode formed by arranging a plurality of blocks divided in the circumferential direction around the center portion in the circumferential direction. Forming a desired gap and arranging them facing each other, closing each of the gap formed between the blocks in the acceleration electrode and the gap formed between the blocks in the deceleration electrode with a pair of presser fittings, Ions converted into plasma in the plasma chamber are drawn through each of a number of holes formed in each block of the acceleration electrode and each block of the deceleration electrode, and illuminated on the workpiece in the sample chamber. To an ion milling apparatus characterized by comprising an electrode subjected to ion milling. 8. The ion milling apparatus according to claim 4, wherein the metal holding member is formed in a rib shape. 9. The ion milling device according to claim 4, wherein each block of the accelerating electrode and each block of the decelerating electrode are connected by an insulating spacer at a central portion of the electrode. Processing equipment. 10. An ion milling apparatus according to claim 9, wherein said insulating spacer is formed so as to have a projection on an outer periphery. 11. The ion milling apparatus according to claim 9, wherein a material of said insulating spacer is alumina, SiO ₂ or glass macor.