JP2017033920A - Ion beam irradiation method and ion beam irradiation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform ion beam irradiation with high uniformity by accurately determining the number of scans and rotations of a substrate capable of performing ion beam irradiation with high uniformity in a device having such current density distribution that an ion beam is pulsated and using both scans and rotations of the substrate.SOLUTION: An ion beam irradiation method includes: calculating current density distribution of an ion beam 28 in an X direction at a position of a substrate 6 on the basis of a beam current density distribution measured by a beam measuring instrument 52; using the current density distribution and a scan waveform of the substrate 6 to change a combination of the number of scans rotations of the substrate 6 among a plurality of combinations; and calculating an irradiation amount density of an ion beam 28 at a plurality of points on the substrate 6 for each combination. The ion beam irradiation method also includes: calculating uniformity of the beam irradiation amount density on the substrate 6 on the basis of the irradiation amount density; determining the number of scans and rotations of the substrate 6 for obtaining desired uniformity based on the uniformity; and irradiating the substrate 6 with the ion beam 28 with the determined number of scan and rotation.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an ion beam irradiation method and an ion beam irradiation apparatus for performing processing by irradiating a substrate in a vacuum vessel with an ion beam in an ion beam irradiation apparatus such as an ion milling apparatus and an ion implantation apparatus. The present invention relates to a method and an apparatus for performing ion beam irradiation with good uniformity by accurately determining the number of scans and the number of rotations of a substrate.

  In Patent Document 1, an ion source having an ion beam extraction aperture smaller than the substrate size is used, and the entire surface of the substrate is irradiated with the ion beam by using both rotation (autorotation) and reciprocating linear drive (scanning) of the substrate. Thus, an ion beam irradiation method (ion beam milling method) and an apparatus are described in which the beam density is averaged on a substrate to uniformize the beam irradiation amount (etching).

  In Patent Document 2, when irradiating a substrate with an ion beam extracted from an ion source having a multi-slit electrode in which a plurality of slits are arranged in parallel, the substrate has a vibration width about the slit arrangement pitch of the multi-slit electrode. Describes an ion implantation apparatus that employs an ion beam irradiation method that equalizes the beam irradiation amount (ion implantation amount) by averaging the pulsation distribution of the beam intensity caused by the multi-slit electrode on the substrate by vibrating the substrate Has been.

JP-A-8-134668 (paragraphs 0011-0016, FIGS. 1 and 3) JP-A-8-287863 (paragraphs 0010-0013, FIG. 1)

  In the technique described in Patent Document 1, it is considered that the uniformity of the beam irradiation amount on the substrate can be improved to some extent by using both the scanning and the rotation of the substrate. Patent Document 1 does not describe how to determine the number of scans and the number of rotations of the substrate in order to obtain performance.

  To describe this in detail, Patent Document 1 describes, for example, “If the ion beam milling apparatus has a distribution with a high ion beam density in a narrow portion in the center of the movement range of the substrate 6, the movement of the substrate 6 is considerably constant. Although it is described that “a uniform irradiation dose can be obtained” (paragraph 0021), since the substrate is two-dimensional instead of one-dimensional, simply scanning and rotating the substrate at a constant speed can be performed on the substrate. The beam dose distribution is not very uniform. This is because the beam dose distribution varies greatly depending on the combination of the number of scans and the number of rotations of the substrate.

  An example of this will be described with reference to FIGS. FIG. 1 shows a circular shape on the substrate 6 when the scanning and rotation of the substrate 6 are both at the same speed, and the number of scans and the number of rotations of the substrate 6 is 1: 1 (that is, one rotation during one scan). It is a schematic plan view which shows the example of the time change of beam irradiation area | regions 3a-3i. Time has elapsed from (A) → (B) → (C) →... → (H) → (I).

  In this figure, the substrate 6 is assumed to have a notch (notch) 7 so that the rotational position of the substrate 6 can be easily understood. (A) is an initial state, and in each state after (B), the substrate 6 is changed by 1/8 rotation (45 degrees rotation) in the direction of arrow C and 1/8 scan in the direction of arrow D. (I ) To return to the same initial state as (A). Since the position of the ion beam does not change, the absolute position of the beam irradiation regions 3a to 3i does not change, but the relative position on the substrate changes as the substrate 6 is scanned.

  FIG. 2 shows an enlarged view of the overlapped beam irradiation regions 3b to 3i on the substrate 6 in the states (B) to (I) in FIG. As can be seen from this figure, the beam irradiation regions 3b to 3i on the substrate 6 are greatly deviated. In this case, the beam irradiation amount distribution on the substrate 6 is not uniform.

  On the other hand, since the technique described in Patent Document 2 has a current density distribution in which the ion beam extracted from the ion source pulsates, the beam on the substrate is made by vibrating the substrate as compared with the case where the substrate is not vibrated. Although the uniformity of the irradiation amount can be improved to some extent, the improvement of the uniformity of the beam irradiation amount is limited because the rotation of the substrate is not used together.

  Therefore, the present invention performs ion beam irradiation with good uniformity on a substrate in an apparatus that has a current density distribution in which an ion beam extracted from an ion source pulsates and uses both scanning and rotation of the substrate. An object of the present invention is to provide a method and an apparatus capable of accurately determining the number of scans and the number of rotations of the substrate that can be performed and performing ion beam irradiation with good uniformity.

One of the ion beam irradiation methods according to this invention is
A vacuum vessel that is evacuated to vacuum,
A holder that is housed in the vacuum vessel and holds a substrate;
A rotation mechanism for rotating the holder and the substrate held by the holder around the center of the substrate;
An ion source that has a plasma generation unit that generates plasma and an extraction electrode system that extracts an ion beam from the plasma by the action of an electric field, and irradiates the extracted ion beam onto a substrate held by the holder, In the extraction electrode system, a region where the ion beam is extracted and a region where the ion beam is not extracted are alternately arranged in the X direction at a predetermined period, and the region where the ion beam is extracted from the region where the ion beam is extracted An ion source for extracting an ion beam having a substantially uniform current density distribution in a range equal to or larger than the dimension of the substrate in a Y direction substantially orthogonal to the X direction;
A scanning mechanism for mechanically reciprocatingly scanning the holder, the substrate held by the holder, and the rotating mechanism substantially in the X direction with a predetermined scanning waveform;
An ion beam irradiation apparatus comprising: a beam measuring device that measures a current density distribution of the ion beam in the X direction;
Based on the current density distribution measured by the beam measuring device, obtain a current density distribution in the X direction of the ion beam at the position of the substrate,
Irradiation of an ion beam at a plurality of points on the substrate for each combination by using the obtained current density distribution and the scan waveform of the substrate and changing the combination of the scan number and the rotation number of the substrate by a plurality of combinations. Calculating the dose density, and calculating the uniformity of the beam dose density on the substrate based on the dose density;
Based on the calculated uniformity, determine the combination of the number of scans and the number of rotations of the substrate that achieves the desired uniformity,
The substrate is irradiated with an ion beam with a combination of the determined scan number and rotation number.

  According to this ion beam irradiation method, the combination of the number of scans and the number of rotations of the substrate is changed into a plurality of combinations, and for each combination, the ion beam irradiation density at a plurality of points on the substrate is calculated, and the irradiation amount is calculated. Calculate the uniformity of the beam dose density on the substrate based on the density, and determine the combination of the number of scans and the number of rotations of the substrate that achieves the desired uniformity based on the calculated uniformity. Since the substrate is irradiated with an ion beam with a combination of the scan number and the rotation number, the substrate scan number and rotation number that can perform ion beam irradiation with good uniformity on the substrate are determined accurately, and the substrate is irradiated. On the other hand, ion beam irradiation with good uniformity can be performed.

One of the ion beam irradiation apparatuses according to the present invention includes a control device having a function of controlling at least the rotation mechanism and the scan mechanism, and the control device includes:
(A) current density distribution calculating means for obtaining a current density distribution in the X direction of the ion beam at the position of the substrate based on the current density distribution measured by the beam measuring device;
(B) Using the obtained current density distribution and the scan waveform of the substrate, and changing the number of scans and rotations of the substrate in a plurality of combinations, for each combination, ions at a plurality of points on the substrate The beam irradiation density at the time of each combination of the number of scans and the number of rotations of the substrate is calculated by calculating the beam irradiation density and calculating the uniformity of the beam irradiation density on the substrate based on the irradiation density. Uniformity calculation means for outputting the uniformity of quantity density,
(C) After the uniformity of the beam irradiation dose density is output, the selected combination is received from among a plurality of combinations of the scan number and the rotation number of the substrate, and the selected combination is stored. Combination storage means to
(D) drive control means for controlling the scanning mechanism and the rotation mechanism so that the combination of the number of scans and the number of rotations of the substrate stored in the combination storage means when irradiating the ion beam to the substrate; have.

One of the ion beam irradiation methods according to this invention is
A vacuum vessel that is evacuated to vacuum,
A holder that is housed in the vacuum vessel and holds a substrate;
A rotating mechanism for rotating the holder and a substrate held by the holder around a central portion of the substrate on which a plurality of columnar bodies are arranged; and
An ion source that has a plasma generation unit that generates plasma and an extraction electrode system that extracts an ion beam from the plasma by the action of an electric field, and irradiates the extracted ion beam onto a substrate held by the holder, In the extraction electrode system, a region where the ion beam is extracted and a region where the ion beam is not extracted are alternately arranged in the X direction at a predetermined period, and the region where the ion beam is extracted from the region where the ion beam is extracted An ion source for extracting an ion beam having a substantially uniform current density distribution in a range equal to or larger than the dimension of the substrate in a Y direction substantially orthogonal to the X direction;
A substrate tilting mechanism capable of tilting the holder and the substrate held by the holder so that a substrate tilting angle, which is an angle formed between the normal of the substrate and the traveling direction of the ion beam, is 0 degree or more;
A scanning mechanism for mechanically reciprocally scanning the holder, the substrate held thereon, the rotating mechanism, and the substrate tilting mechanism substantially in the X direction with a predetermined scanning waveform;
An ion beam irradiation apparatus comprising: a beam measuring device that measures a current density distribution of the ion beam in the X direction;
Using the substrate tilt mechanism, the substrate tilt angle is set to a predetermined angle excluding 0 degrees,
Based on the current density distribution measured by the beam measuring device, obtain a current density distribution in the X direction of the ion beam at the position of the substrate,
Using the obtained current density distribution, the scan waveform of the substrate and the predetermined substrate tilt angle, and changing the combination of the scan number and the rotation number of the substrate in a plurality of combinations, the plurality of circles for each combination Calculate the throughput by the ion beam for each side surface of each columnar body, and calculate the throughput uniformity for the side surfaces of the plurality of columnar bodies based on the throughput amount,
Based on the calculated throughput uniformity, determine a combination of the number of scans and the number of rotations of the substrate that provides the desired throughput uniformity;
The substrate is irradiated with an ion beam with a combination of the determined scan number and rotation number.

  According to this ion beam irradiation method, the combination of the number of scans and the number of rotations of the substrate is changed by a plurality of combinations, and for each combination, the amount of processing by the ion beam on each side surface of each of the plurality of cylindrical bodies on the substrate is changed. Calculate the processing amount uniformity for the side surfaces of the plurality of cylindrical bodies based on the processing amount, and calculate the processing amount uniformity of the substrate from which the desired processing amount uniformity is obtained based on the calculated processing amount uniformity The combination of the number of scans and the number of rotations is determined, and the substrate is irradiated with the ion beam with the determined combination of the number of scans and the number of rotations. Therefore, a uniform process is performed on the side surface of the cylindrical body on the substrate. It is possible to accurately determine the number of scans and the number of rotations of the substrate that can be performed and to perform processing with good uniformity on the side surface of the cylindrical body on the substrate.

Another one of the ion beam irradiation apparatuses according to the present invention includes a control device having a function of controlling at least the rotation mechanism, the scan mechanism, and the substrate tilting mechanism,
(A) substrate tilt angle control means for controlling the substrate tilt mechanism to control the substrate tilt angle to a predetermined angle excluding 0 degrees;
(B) current density distribution calculating means for obtaining a current density distribution in the X direction of the ion beam at the position of the substrate based on the current density distribution measured by the beam measuring device;
(C) Using the obtained current density distribution, the scan waveform of the substrate and the predetermined substrate tilt angle, and changing the combination of the scan number and the rotation number of the substrate in a plurality of combinations, The processing amount by the ion beam for each side surface of each of the plurality of cylindrical bodies is calculated, and the processing amount uniformity for the side surfaces of the plurality of cylindrical bodies is calculated based on the processing amount, Uniformity calculation means for outputting the processing amount uniformity at each combination of scan number and rotation number;
(D) A combination memory that receives an input for selecting a predetermined combination among a plurality of combinations of the number of scans and the number of rotations of the substrate after the processing amount uniformity is output, and stores the selected combination Means,
(E) drive control means for controlling the scanning mechanism and the rotation mechanism so that the combination of the number of scans and the number of rotations of the substrate stored in the combination storage means at the time of ion beam irradiation on the substrate; have.

  Instead of providing the beam measuring device, the beam current density distribution in the X direction measured in advance by experiments or the like is stored in the storage means, and the position of the substrate is determined based on the stored beam current density distribution. The current density distribution in the X direction of the ion beam may be obtained and used.

  The ion source irradiates the substrate held by the holder with an ion beam having a dimension at a position of the substrate larger than a size including the substrate and a region where the substrate is scanned. There may be.

  Other modifications may be adopted.

  According to the invention described in claim 1 or 2, the combination of the number of scans and the number of rotations of the substrate is changed by a plurality of combinations, and for each combination, the ion beam irradiation density at a plurality of points on the substrate is calculated, In addition, the uniformity of the beam dose density on the substrate is calculated based on the dose density, and the combination of the number of scans and the number of rotations of the substrate that obtains the desired uniformity is determined based on the calculated uniformity. Since the substrate is irradiated with the ion beam with the combination of the determined scan number and rotation number, the substrate scan number and rotation number capable of performing ion beam irradiation with good uniformity on the substrate are accurately determined. Thus, ion beam irradiation with good uniformity can be performed on the substrate.

  According to invention of Claim 3, there exists the following further effect. That is, when the scan waveform of the substrate is substantially a triangular wave, the calculation results confirm that the combination with the same number of scans and the same number of rotations of the substrate is not good, so this combination is excluded in advance. By doing so, unnecessary calculations are not required, and the calculation of the irradiation dose density and uniformity of the ion beam can be simplified.

  According to invention of Claim 4 or 5, the control which has the uniformity calculation means etc. which calculate and output the uniformity of the beam irradiation amount density on a board | substrate about each combination of the scanning number of a board | substrate and the rotation speed Since the apparatus is provided, it becomes easy to accurately determine the number of scans and the number of rotations of the substrate that can perform ion beam irradiation with good uniformity on the substrate. As a result, it becomes easy to perform ion beam irradiation with good uniformity on the substrate.

  According to the invention described in claim 6 or 7, the combination of the number of scans and the number of rotations of the substrate is changed by a plurality of combinations, and for each combination, the ion beam is applied to all side surfaces of the plurality of cylindrical bodies on the substrate. And the processing amount uniformity for the side surfaces of the plurality of cylindrical bodies is calculated based on the processing amount, and the desired processing amount uniformity is calculated based on the calculated processing amount uniformity. Since the combination of the number of scans and the number of rotations of the substrate to be obtained is determined and the substrate is irradiated with the ion beam with the combination of the determined number of scans and rotations, the uniformity of the side surface of the cylindrical body on the substrate is good. By accurately determining the number of scans and the number of rotations of the substrate that can be processed, it is possible to perform processing with good uniformity on the side surfaces of the cylindrical body on the substrate.

  The invention according to claim 8 has the following further effect. That is, the ion source irradiates an ion beam having a size larger than the size including the substrate and the region to be scanned, so that the scan width of the substrate is not increased. However, ion beam irradiation with good uniformity can be performed by irradiating the entire surface of the substrate with an ion beam. As a result, the time required for substrate processing can be shortened by reducing the substrate scanning time, thereby improving the substrate processing efficiency.

  According to the invention described in claim 9 or 10, uniformity calculation means for calculating and outputting the processing amount uniformity for the side surfaces of the plurality of cylindrical bodies on the substrate for each combination of the scan number and the rotation number of the substrate. Therefore, it is easy to accurately determine the number of scans and the number of rotations of the substrate that can perform processing with good uniformity on the side surface of the cylindrical body on the substrate. As a result, it becomes easy to perform processing with good uniformity on the side surface of the cylindrical body on the substrate.

It is a schematic plan view showing an example of a time change of a beam irradiation region on a substrate when the scanning and rotation of the substrate are both at the same speed and the scanning number and the rotation number of the substrate are 1: 1, (A) → Time has elapsed from (B) → (C) →... → (H) → (I). It is a schematic plan view which expands and shows what overlapped the beam irradiation area | region on the board | substrate by the state of (B)-(I) in FIG. It is a schematic sectional drawing which shows one Embodiment of the ion beam irradiation apparatus which enforces the ion beam irradiation method concerning this invention. It is a schematic plan view which shows an example of the dimension of the ion beam in the position of a board | substrate. It is a schematic sectional drawing which expands and shows an example of an ion source. It is a schematic plan view which shows an example of the ion beam extraction area | region part of the plasma electrode which comprises the extraction electrode system shown in FIG. FIG. 6 is a schematic plan view showing another example of an ion beam extraction region portion of a plasma electrode constituting the extraction electrode system shown in FIG. 5. It is the schematic which shows an example of the current density distribution of the ion beam in the position of a board | substrate. It is the schematic which shows the example which simplified the current density distribution of the ion beam in the position of a board | substrate. It is the schematic which shows the scanning and rotation of a board | substrate simplified. It is the schematic which shows an example of the scan waveform of a triangular wave. It is the schematic which shows an example of the normalized beam current density distribution. It is process drawing which shows one Embodiment of the ion beam irradiation method which concerns on this invention. It is a block diagram which shows an example of a structure of the control apparatus which comprises the ion beam irradiation apparatus shown in FIG. It is a block diagram which shows the other example of a structure of the control apparatus which comprises an ion beam irradiation apparatus. It is the schematic which shows the example of the relationship between the change of the direction accompanying a board | substrate scan and board | substrate rotation, and ion beam distribution of the prism side surface on the said board | substrate at the time of inclining a board | substrate, (A) shows ion beam distribution, (B) shows the passage of time for substrate scanning, and (C) shows the passage of time for substrate rotation. It is a schematic sectional drawing which shows other embodiment of the ion beam irradiation apparatus which enforces the ion beam irradiation method concerning this invention. It is process drawing which shows other embodiment of the ion beam irradiation method which concerns on this invention. It is the schematic which shows the rotation and scanning of the said board | substrate at the time of inclining a board | substrate by the angle (theta) simplified, (A) is a top view in a substrate surface, (B) is a side view. It is a graph which shows an example of the result of having calculated the sputtering rate of the target material by ion irradiation in the case of incident angle (alpha) by public software SRIM. It is the schematic which shows beam incident angle (beta) etc. with respect to the prism side surface on the board | substrate inclined by angle (theta). The basic vector (i, j, k) of the (X, Y, Z) coordinate system and the basic vector (i ′, j ′, k) of the coordinate system (X ′, Y ′, Z ′) on the substrate inclined by the angle θ. It is the schematic which shows the relationship with k '). It is a schematic diagram showing a side number S _n and the initial angle eta _p such polygonal prism on the substrate. It is the schematic which shows beam incident angle (beta) etc. with respect to the side surface of the cylindrical body on the board | substrate inclined by angle (theta). It is the schematic which shows the other example of the normalized beam current density distribution. It is a graph which shows an example of the result of having calculated the milling uniformity of the cylindrical body side surface by changing the number of rotations of the substrate when the number of scans is one. It is a block diagram which shows an example of a structure of the control apparatus which comprises the ion beam irradiation apparatus shown in FIG. It is a block diagram which shows the other example of a structure of the control apparatus which comprises an ion beam irradiation apparatus.

(1) One Embodiment of Ion Beam Irradiation Apparatus FIG. 3 shows one embodiment of an ion beam irradiation apparatus for carrying out the ion beam irradiation method according to the present invention. In order to facilitate understanding of the directions, the X direction, the Y direction, and the Z direction that are orthogonal to each other at one point are illustrated in each drawing. For example, the Y direction and the Z direction are horizontal directions, and the X direction is a vertical direction. In this example, the ion beam 28 travels in the −Z direction (that is, the direction opposite to the Z direction).

  This ion beam irradiation apparatus is an apparatus that irradiates the substrate 6 with the ion beam 28 in a vacuum atmosphere. The ion container 28 is evacuated to a vacuum by a vacuum evacuation apparatus (not shown) and is housed in the vacuum container 4. A holder 8 for holding the substrate 6 to be processed and a rotation mechanism 10 for rotating the holder 8 and the substrate 6 held by the holder 8 around the central portion 6a of the substrate 6 are provided. An example of the rotation direction C of the substrate 6 or the like is shown in the figure, but it may be in the opposite direction. The rotation may be continuous rotation or step rotation for each predetermined angle.

  The substrate 6 is, for example, a semiconductor substrate such as a silicon wafer, or a substrate in which a film such as a magnetic film is formed on the surface of the semiconductor substrate, but is not limited thereto.

  The shape of the substrate 6 is, for example, a circle (including an orientation flat or a notch in a part of the circumference), but is not limited thereto.

  As shown in this example, the ion beam irradiation apparatus tilts the holder 8 and the substrate 6 held by the holder 8 by rotating the holder 8 and the like as indicated by the arrow E, so that the perpendicular of the substrate 6 and the traveling direction of the ion beam 28 are determined. There may be provided a substrate tilting mechanism 12 capable of setting the substrate tilting angle (see the substrate tilting angle θ in FIG. 17) to 0 ° or more. This will be further described later.

The ion beam irradiation apparatus further includes a plasma generation unit 22 that generates the plasma 23 and an extraction electrode system 24 that extracts the ion beam 28 from the plasma 23 by the action of an electric field. The ion beam 28 is extracted from the holder 8. An ion source 20 for irradiating the substrate 6 held on the substrate is provided. Extraction electrode system 24, for example 6, as in the example shown in FIG. 7, the ion beam 28 is the area A ₁ and the ion beam 28 is not pulled out region B ₁ and a predetermined period P ₁ in the X direction drawn It has a configuration in which the ion beams are extracted and from the region A ₁ where the ion beam is extracted, at a position of the substrate 6, substantially in a range equal to or larger than the size of the substrate 6 in the Y direction substantially orthogonal to the X direction. The ion beam 28 having a uniform current density distribution is extracted. The extraction electrode system 24 will be further described later.

  This ion beam irradiation apparatus further includes a holder 8, a substrate 6 held on the shaft 16, a rotating mechanism 10, and a substrate tilting mechanism 12 in this example via a shaft 16. A scanning mechanism 14 that scans mechanically in a reciprocating manner in the X direction with a waveform (that is, mechanical reciprocating scanning) is provided. In this application, for example, one scan refers to one reciprocating scan. The scanning mechanism 14 is provided outside the vacuum container 4 in this example, but is not limited thereto.

  The ion beam irradiation apparatus further includes a beam measuring device that measures the current density distribution of the ion beam 28 in the X direction. The beam measuring device may be, for example, a multi-point beam measuring device in which a large number of beam current detectors (for example, Faraday cups, and so on) are arranged in the X direction, or one beam current detector is moved in the X direction. A movable beam measuring device may be used. A beam measuring device 52 shown in FIG. 3 is an example of the former case.

  The beam measuring device may be a movable type that moves to the position of the substrate 6 so as not to interfere with the substrate 6, and is provided at a position upstream or downstream of the substrate 6. Things can be used. The beam measuring device 52 in FIG. 3 shows an example provided on the downstream side of the substrate 6. When provided on the upstream side of the substrate 6, the substrate 6 may be moved to a position that does not interfere with the irradiation of the ion beam 28 on the substrate 6.

In the ion source 20, the size at the position of the substrate 6 with respect to the substrate 6 held by the holder 8 includes the substrate 6 and a region where the substrate 6 is scanned, as in the example illustrated in FIG. 4. What irradiates the ion beam 28 of a size larger than this is preferable. In Figure 4, also shows an example of a scan direction D and the scan width W _S of the substrate 6. 4 shows an example in which the substrate 6 indicated by a broken line in FIG. 4 is located at one end of the scan, and the substrate 6 indicated by a two-dot chain line is located at the other end of the scan. With such an ion source 20, without increasing the scan width W _S of the substrate 6, the entire surface of the substrate 6 by irradiating the ion beam 28, it is possible to perform good uniformity ion beam irradiation. As a result, the scan time of the substrate 6 can be shortened, and the time required for the substrate processing can be shortened, thereby improving the processing efficiency of the substrate 6.

  The kind of ion source 20 is not limited to a specific type. For example, the ion source 20 may be a so-called bucket type ion source (also called a multipole magnetic field type ion source) that performs confinement of the plasma 23 using a multipolar magnetic field (cusp magnetic field), or (b) A high-frequency ion source that generates plasma 23 by high-frequency discharge may be used. (C) A so-called Bernas type in which plasma 23 is generated by applying a magnetic field in a direction along an axis connecting the cathode and the reflective electrode. An ion source may be used. The number of electrodes constituting the extraction electrode system 24 is not limited to a specific one.

  A more detailed example of the ion source 20 of the example shown in FIG. 3 will be further described with reference to FIG. The plasma generation unit 22 that generates the plasma 23 is a known plasma generation unit that constitutes, for example, the above-described bucket ion source, high-frequency ion source, or Bernas ion source, and is simplified in FIG. .

  The ion source 20 of the example shown in FIG. 5 has a plurality of (three in this example) electrodes 31 to 33 as a component of the extraction electrode system 24. In this application, of the three electrodes, the electrode closest to the plasma 23 is referred to as the plasma electrode 31, and the electrode on the downstream side (downstream in the traveling direction of the ion beam 28, hereinafter the same) is referred to as the extraction electrode 32. The downstream electrode is called a ground electrode 33. For example, a positive acceleration voltage is applied to the plasma electrode 31 from a DC power source (not shown). A negative extraction voltage is applied to the extraction electrode 32 from a DC power source (not shown). The ground electrode 33 is electrically grounded.

The extraction electrode system 24, more specifically, each of the electrodes 31 to 33 in this example is an ion beam extraction region 26 (see FIG. 5) having a size larger than the size including the substrate 6 and the region in which the substrate 6 is scanned. 6 and FIG. 7). The ion beam extraction region 26 is a region having a number of openings (ion extraction openings) such as holes and slits through which the ion beam 28 is extracted. For example, the ion beam extraction region 26 shown in FIG. 6 has a large number of holes 34, and the ion beam extraction region 26 shown in FIG. 7 has a large number of slits 37. As an example of dimensions, if the diameter of the substrate 6 is 300 mm, the scan width W _S is 80 mm, height and width of the ion beam extraction region 26 is 400 mm × 400 mm. However, it is not limited to this.

  In this example, the three electrodes 31 to 33 have substantially the same configuration except for the cooling pipes 40 and 41. Therefore, the plasma electrode 31 represents the ion beam extraction region 26 portion. The plan view is shown in FIG. 6 or FIG.

  Each of the electrodes 31 to 33 may have a large number of holes 34 for extracting the ion beam 28 as in the examples shown in FIGS. 5 and 6, or the ion beam 28 as in the example shown in FIG. 7. You may have many slits 37 for drawer | drawing-out.

For example, at least the plasma electrode 31 may be provided with a cooling pipe for cooling the electrode in the electrode constituting the extraction electrode system 24. In this example, a plurality of cooling pipes 40 are arranged on the plasma electrode 31 at a constant pitch in the X direction. In the cooling pipe 40, for example, a coolant such as cooling water flows. Since the ion beam 28 is not extracted from the portion where the cooling pipe 40 is provided, the extraction electrode system 24 has a plurality of holes 34 (see FIG. 6) or a plurality of slits 37 (see FIG. 6) as in the examples shown in FIGS. see FIG. 7) have a region a ₁ in which the ion beam 28 is drawn out, has cooling pipe 40 is provided and the region B ₁ is not drawn out ion beam 28, at a predetermined period P ₁ in the X direction It has an alternately arranged structure.

  You may provide the cooling pipe which cools the said electrode also in the electrode downstream from the plasma electrode 31 as needed. In the example shown in FIG. 5, the extraction electrode 32 is also provided with a plurality of cooling pipes 41. Each cooling pipe 41 is arranged corresponding to the position of each cooling pipe 40 in this example. In the cooling pipe 41, for example, a coolant such as cooling water flows.

An example of the current density distribution at the position of the substrate 6 of the ion beam 28 extracted from the ion source 20 having the extraction electrode system 24 having the two types of regions A ₁ and B ₁ as described above is shown in FIG. The current density distribution is pulsating at a constant period P _2. The peak portion A ₂ is a portion corresponding to the region A ₁ where the ion beam of the extraction electrode system 24 is extracted, and the valley portion B ₂ is a portion corresponding to the region B ₁ where the ion beam of the extraction electrode system 24 is not extracted. . The relationship between the period P ₂ and the period P ₁ of the extraction electrode system 24 can often be considered as P ₁ ≈P ₂ except in special cases (for example, when the divergence of the ion beam 28 is large). .

The current density distribution shown in FIG. 8 is only an example, and the relationship between the widths of the two regions A ₁ and B ₁ of the extraction electrode system 24 and the ion beam extracted from each hole and slit in each region A ₁ . A current density distribution with smaller pulsation, a current density distribution with larger pulsation, and other current density distributions can be realized depending on the divergence angle. For example, see FIG.

Since the plasma electrode 31 has the largest heat input from the plasma generation unit 22, in order to further increase the cooling capacity thereof, the plasma electrode 31 is cooled in parallel with the cooling pipe 40 in the middle of the region A ₁ from which each ion beam is extracted. A cooling pipe thinner than the pipe 40 may be further arranged. Even in such a case, it can be said that the basic period of the area A ₁ that is regarded as large is still P ₁ . Further, when the additional cooling pipe is arranged, the ion beam is not drawn from the cooling pipe portion. Therefore, each mountain portion of the current density distribution of the ion beam 28, for example, each mountain of the current density distribution shown in FIG. Although the portion A ₂ has two peaks, it can be said that the basic (ie, greatly regarded) period of the beam current density distribution is still P ₂ .

The extraction electrode system 24 of the ion source 20 may have a split structure electrode on at least one of the electrodes constituting the extraction electrode system 24. The electrode having a divided structure referred to here is a plurality of electrode pieces each having a number of ion extraction openings (for example, openings corresponding to the holes 34 or the slits 37), and in a predetermined direction (for example, FIG. 6). Electrode pieces each having a connecting portion extending in the Y direction) are arranged in a predetermined cycle in the X direction and connected to form one electrode. Since each connection portion does not have an ion extraction opening, the ion beam is not extracted from the connection portion. Therefore, even if the extraction electrode system 24 has an electrode having such a divided structure, the extraction electrode system 24 (corresponding to the region A ₁₎ area the ion beam 28 is drawn out and pull out the ion beam 28 The region (corresponding to the region B ₁ ) that is not performed is alternately arranged in a predetermined direction at a predetermined period (corresponding to the period P ₁ ).

  Referring to FIG. 3 again, the ion beam irradiation apparatus further controls the scanning mechanism 14 to scan the substrate 6 within the irradiation region of the ion beam 28 according to a predetermined scan waveform. Is provided with a control device 50 having a function of irradiating the entire surface with the ion beam 28.

  For example, the scan waveform of the substrate 6 is substantially a triangular wave, substantially a sine wave, or the like. A substantially triangular wave is meant to include a triangular wave and a blunted triangular wave in which the triangular wave is somewhat dull. Substantially sine wave is meant to include sine waves and distorted sine waves that are somewhat distorted.

  Therefore, according to the ion beam irradiation apparatus, the substrate 6 can be processed by irradiating the entire surface of the substrate 6 held by the holder 8 with the ion beam 28. For example, the substrate 6 can be subjected to ion milling such as cutting its surface. Also, ion implantation can be performed on the substrate 6. The type of the ion beam 28 may be selected according to the processing content to be applied to the substrate 6. For example, when ion milling is performed, an inert gas ion beam such as an argon ion beam may be used as the ion beam 28. When ion implantation is performed, an ion beam containing a desired dopant may be used as the ion beam 28.

  In this example, the control device 50 further has a function of controlling the rotating mechanism 10 and the substrate tilting mechanism 12. In this example, the control device 50 is given measurement data from the beam measuring device (for example, the beam measuring device 52), that is, measurement data of the current density distribution of the ion beam 28 in the X direction. In this example, the control device 50 includes a storage device (storage means) that stores the measurement data and the like. A more specific example of the configuration of the control device 50 will be described later.

(2) One Embodiment of Ion Beam Irradiation Method Next, an embodiment of an ion beam irradiation method in the ion beam irradiation apparatus as described above will be described. The main points of this ion beam irradiation method are as follows. In this embodiment, as shown in FIG. 3, the substrate 6 is not inclined with respect to the ion beam 28 (that is, the substrate inclination angle θ = 0 degrees).

  (A) Based on the current density distribution measured by the beam measuring device (for example, the beam measuring device 52), the current density distribution in the X direction of the ion beam 28 at the position of the substrate 6 is obtained. This step is referred to as a step 101 for obtaining a current density distribution as shown in FIG.

  (B) Using the obtained current density distribution and the scan waveform of the substrate 6 and changing the combination of the number of scans and the number of rotations of the substrate 6 to a plurality of combinations, for each combination, ions at a plurality of points on the substrate 6 The dose density of the beam 28 is calculated, and the uniformity of the beam dose density on the substrate 6 is calculated based on the dose density. This step is called a uniformity calculation step 102 as shown in FIG.

  (C) Based on the calculated uniformity, the combination of the number of scans and the number of rotations of the substrate 6 that obtains the desired uniformity is determined. This step will be referred to as a combination determination step 103 as shown in FIG.

  (D) The ion beam 28 is irradiated onto the substrate 6 with the combination of the determined scan number and rotation number. This step is referred to as an ion beam irradiation step 104 as shown in FIG.

  The steps (a) to (c) may be performed for each of the substrates 6 to be processed, or may be performed for each of a plurality of substrates 6, for example, for each lot. The same applies to other embodiments described later.

  Each process of said (a)-(d) is explained in full detail below.

(A) Step 101 for obtaining a current density distribution
First, the current density distribution in the X direction of the ion beam 28 at the position of the substrate 6 is obtained based on the current density distribution measured by the beam measuring device (for example, the beam measuring device 52).

For example, an equation representing the current density distribution I (x) of each peak portion constituting the beam current density distribution in the X direction of the ion beam 28 at the position of the substrate 6, the peak period P ₂ and the number of peak portions are obtained. Thus, a distribution corresponding to a beam current density distribution f (x) shown in Equation 9 described later is obtained. The current density distribution I (x) at each peak is expressed by a Gaussian distribution formula in the example described later, but is not limited thereto.

  When the beam measuring device is provided at the position of the substrate 6, the beam current density distribution measured by the beam measuring device may be directly used as the beam current density distribution at the position of the substrate 6.

  When the beam measuring device is not provided at the position of the substrate 6, by performing calculation using the geometrical arrangement relationship between the position of the beam measuring device and the position of the substrate 6, the divergence state of the ion beam 28, and the like, The beam current density distribution at the position of the substrate 6 may be obtained.

A schematic example of the beam current density distribution f (x) on the substrate 6 is shown in FIG. In this figure, for easy understanding of the following description, the distribution waveform is greatly simplified and the current density of the valley portion B ₂ is set to zero. The actual beam current density distribution usually has a smooth pulsating distribution as in the examples shown in FIGS.

(B) Uniformity calculation step 102
Next, using the obtained beam current density distribution and the scan waveform of the substrate 6 and changing the combination of the number of scans and the number of rotations of the substrate 6 in a plurality of combinations, each combination is obtained at a plurality of points on the substrate 6. The dose density of the ion beam 28 is calculated, and the uniformity of the beam dose density on the substrate 6 is calculated based on the dose density. This will be described in detail below. In this application, the number of scans of the substrate 6 has the same meaning as the number of mechanical reciprocal scans of the substrate 6. For example, one scan is one reciprocal scan.

As shown in a simplified manner in FIG. 10, in this example, the rotation direction of the substrate 6 is the arrow C direction, the scan direction D of the substrate 6 is the X direction, and the time period of the scan is T _S. Further, the time change x (t) of the center point of the substrate 6 at time t = 0 is expressed by the following equation. Here, g (t) is a periodic function with respect to time.

[Equation 1]
x (t) = g (t)

In the following, as an example, the periodic function g (t), as shown in FIG. 11, the amplitude P _2/2, the period is a triangular wave of T _S. In this case, the scanning width W _S of the substrate 6 is equal to the period P _2.

  Referring to FIG. 10 again, when the substrate 6 is only rotated, the positions x (t) and y (t) on the X and Y coordinates of the temporal movement of the point Q (x, y) on the substrate 6 are When expressed using the initial position (R, φ) on the substrate 6, the following expression is obtained. Here, R is the radius of the initial position, φ is the initial angle (that is, the angle at time t = 0 with respect to the X axis that is the scanning direction), and ω is the angular velocity of the substrate rotation.

[Equation 2]
x (t) = R · cos (ωt + φ)
y (t) = R · sin (ωt + φ)

  Therefore, the trajectory of the point Q (x, y) on the substrate 6 when the substrate 6 is scanned and rotated is expressed by the following equation, taking into account the equation 1 given above.

[Equation 3]
x (t) = g (t) + R · cos (ωt + φ)
y (t) = R · sin (ωt + φ)

  As described above, since the current density distribution in the Y direction of the ion beam 28 extracted from the ion source 20 is substantially uniform in a range equal to or larger than the dimension of the substrate 6, the beam dose density at each point on the substrate 6. The x position is necessary for evaluating the uniformity of the.

  The beam dose density W for one scan (that is, one reciprocal scan) when the substrate 6 is scanned and rotated is expressed by the following equation.

When the number of scans N _S and the number of rotations N _R (N _S , N _R are integers of 1 or more) of the substrate 6 are added to the above formula, the following results. That is, it is assumed that the substrate 6 rotates N _{R at} the time of N _S scan t = N _S · T _S. In this case, the following relationship is established.

[Equation 5]
ω (N _S · T _S ) = 2π · N _R
∴ω = 2π (N _R / N _S ) (1 / T _S )

By substituting this into the above equation 4 and setting the range of integration to 0 to N _S · T _S , the following equation is obtained. This is the beam dose density W in the case that the substrate 6 is rotated N _S scans and N _R times.

  In order to calculate the uniformity of the beam dose density on the substrate 6, the beam dose density is calculated over the entire surface of the substrate 6 by changing the radius R and the initial angle φ in predetermined increments. An example of this step is the following equation, but is not limited to this.

[Equation 7]
ΔR = R / 20 (ie, the radius is divided into 20 equal parts)
Δφ = 2π / 72 (ie, one round is divided into 72 equal parts)

Yet, by changing the combination of the scan number N _S and the rotational speed N _R of the substrate 6 by a plurality of combinations (e.g., see Table 1, Table 2 to be described later), the calculation of the beam dose density W for each combination.

  For simple evaluation of the beam dose density W on the substrate 6, for example, the initial angle φ is fixed to two of 0 (on the X axis) or π / 2 (on the Y axis), and the radius Calculation may be performed by changing only R.

Here, as an example, the current density distribution I (x) of each peak portion in the X direction of the ion beam 28 at the position of the substrate 6 is assumed to be a Gaussian distribution represented by the following equation (actually, the beam measuring device). The current density distribution I (x) measured using 52 or the like may be used. Here, x is a position in the X direction on the substrate 6, I ₀ is a peak intensity, d is a width at which the peak intensity is 1 / e (this will be referred to as 1 / e width. E is a natural logarithm). E = 2.718).

[Equation 8]
I (x) = I ₀ · exp (−x ² / d ² )

In the following, in order to simplify the calculation, the normalized beam current density distribution obtained by normalizing the beam current density distribution of the above equation by I ₀ (ie, dividing by I ₀ and setting the peak intensity to 1) is shown below. Use. FIG. 12 is illustrated using this. If normalization with I ₀ is not performed, the entire right side of the following formula 9 may be put in parentheses and I ₀ may be added to the head.

The period of the beam current density distribution in the scanning direction on the substrate 6 and P _2, the distance units and P _2/2. The beam current density distribution shown in FIG. 12 is an example in which there are five crests on the substrate 6 and the centers in the unit of distance are x = −4, −2, 0, 2, and 4, respectively. is there.

The 1 / e width (= d) of each peak was calculated under three conditions: d = 1/3, 2/3, and 4/5. These show examples in which the divergence angles of the ion beams extracted from the region A ₁ from which each ion beam of the extraction electrode system 24 of the ion source 20 is extracted are small, medium, and large, respectively.

  The beam current density distribution f (x) on the substrate 6 of the entire ion beam 28 having the five peak portions can be expressed by the following equation.

[Equation 9]
f (x) = exp {− (x + 4) ² / d ² } + exp {− (x + 2) ² / d ² }
+ Exp {−x ² / d ² } + exp {− (x−2) ² / d ² }
+ Exp {− (x−4) ² / d ² }

  FIG. 12 shows the beam current density distribution f (x) expressed by the above equation 9 in a graph for each 1 / e width.

In triangular scan waveform of the substrate 6 has been described above, the case where the beam current density distribution on the substrate 6 is of three kinds shown in FIG. 12, a combination of the scan number N _S and the rotational speed N _R of the substrate 6 by a plurality of combinations Instead, for each combination, the ion dose density W of the ion beam at a plurality of points on the substrate 6 is calculated, and the uniformity U of the beam dose density on the substrate 6 is calculated based on the dose density W. An example of the results will be described below.

The uniformity U of the beam dose density on the substrate 6 is expressed by the following equation. Here, W _max is the maximum value of the beam irradiation density W, and W _min is the minimum value of the beam irradiation density W.

[Equation 10]
U = (W _max −W _min ) / (W _max + W _min )

The calculation of the uniformity U was performed with 0 ≦ R ≦ 4 in this example. This 4 are those when the unit of distance as described above was P _2/2, the actual dimensions are _{(P 2/2) × 4} = 2P 2.

Tables 1 and 2 show the calculation results of the uniformity U of the beam dose density at each combination of the scan number N _S and the rotation number N _R. Table 1 shows the case of 1 / e width = 1/3 (in simple terms, each peak portion of the ion beam 28 is sharp), and Table 2 shows the case of 1 / e width = 4/5 (in simple terms, This is a case where each peak portion of the ion beam 28 is gentle. Here, the scan number N _S 1 to 7 times in the range, the rotational speed N _R is calculated in a range of 1 to 10 times.

  In Tables 1 and 2, the case where the uniformity U is ± 0% to ± 1% and particularly good is colored gray so that it can be easily distinguished from others.

  From Table 1 and Table 2 above, it can be seen that when the peak portions of the ion beam 28 become gentle (that is, the 1 / e width increases), the number of good combinations of uniformity U increases. In the case of 1 / e width = 2/3, since it is about the middle of Table 1 and Table 2, the table is omitted here.

(C) Combination determining step 103
Then, based on the uniformity U was calculated as described above, we determine a combination of the scan number N _S and the rotational speed N _R of the substrate 6 which desired uniformity U is obtained.

(D) Ion beam irradiation step 104
Then, the ion beam 28 to the substrate 6 by a combination of number of scans N _S and the rotational speed N _R of the determined.

For example, a desired combination is determined from the combination of the scan number N _S and the rotation number N _R that provide the gray-colored uniformity U, and the substrate is determined based on the determined combination of the scan number N _S and the rotation number N _R. 6 is irradiated with an ion beam 28.

As described above, according to this ion beam irradiation method, the combination of the scan number N _S and the rotation number N _R of the substrate 6 is changed to a plurality of combinations, and the ion beam irradiation is performed at a plurality of points on the substrate 6 for each combination. The dose density W is calculated, and the uniformity U of the beam dose density on the substrate 6 is calculated based on the dose density W, and the desired uniformity U is obtained based on the calculated uniformity U. and determines a combination of the scan number N _S and the rotational speed N _R of the substrate 6 to be, since the ion beam 28 to the substrate 6 by a combination of the determined number of scans N _S and the rotational speed N _R, relative to the substrate 6 It is possible to accurately determine the number of scans N _S and the number of rotations N _R of the substrate 6 that can perform ion beam irradiation with good uniformity, and to perform ion beam irradiation with good uniformity on the substrate 6. .

  Next, some other embodiments of the ion beam irradiation method will be described. In the following, differences from the above embodiment will be mainly described.

  Instead of providing the beam measuring device (for example, the beam measuring device 52), the beam current density distribution in the X direction measured in advance by experiments or the like is used, for example, by using an ion beam irradiation device equivalent to the ion beam irradiation device. The measurement result is stored in a storage means, for example, a storage device in the control device 50, and in the step 101 for obtaining the current density distribution, the substrate 6 is based on the stored beam current density distribution. The current density distribution f (x) in the X direction of the ion beam 28 at the position may be obtained and used. The same applies to other embodiments described later.

  In addition, when the ion beam irradiation process is performed on the substrate 6 by changing various conditions (this is called a recipe) such as the energy, current value, and ion type of the ion beam 28, the beam current density distribution is changed depending on the recipe. In this case, the beam current density distribution is experimentally measured and stored in advance for each recipe, and when calculating the uniformity U, the beam current density distribution corresponding to the recipe is calculated. You may decide to use it. The same applies to other embodiments described later.

  After obtaining the current density distribution in the X direction of the ion beam 28 at the position of the substrate 6 as described above, it is the same as in the case of the above embodiment.

  By doing as described above, it is not necessary to provide a beam measuring device for measuring the beam current density distribution in the actual ion beam irradiation apparatus, so that the configuration of the ion beam irradiation apparatus can be simplified. The same applies to other embodiments described later.

Further, as described above, the ion source 20 irradiates the ion beam 28 having a size larger than the size including the substrate 6 and the region where the substrate 6 is scanned (for example, the size at the position of the substrate 6). (See FIG. 4). In so doing, without increasing the scan width W _S of the substrate 6, the entire surface of the substrate 6 by irradiating the ion beam 28, it is possible to perform good uniformity ion beam irradiation. As a result, the scan time of the substrate 6 can be shortened, and the time required for the substrate processing can be shortened, thereby improving the processing efficiency of the substrate 6. The same applies to other embodiments described later.

When the scan waveform of the substrate 6 is substantially a triangular wave, as shown in Tables 1 and 2, the uniformity U is not good in the combination in which the scan number N _S and the rotation number N _R of the substrate 6 are the same. Therefore, when calculating the ion beam irradiation density W and the uniformity U, the combination of N _S = N _R may be excluded in advance. By doing so, unnecessary calculations are not required, and the calculation of the ion beam irradiation density W and uniformity U can be simplified.

(3) More specific example of control device 50 The control device 50 may have a function of performing the ion beam irradiation method of (2). An example of the configuration of the control device 50 in that case will be described below. In addition, you may comprise the control apparatus 50 demonstrated below using a computer. In addition to the functions described below, the ion beam irradiation apparatus as a whole may be controlled. The same applies to other embodiments described later.

  14 includes a current density distribution calculation unit 62 (current density distribution calculation unit), a uniformity calculation unit 64 (uniformity calculation unit), a combination storage unit 66 (combination storage unit), and a drive control unit 68 ( Drive control means). These arithmetic units, storage units, and the like exchange signals with each other via a bus 60, for example.

  Based on the current density distribution measured by the beam measuring device (for example, the beam measuring device 52), the current density distribution calculating unit 62 determines the current density distribution f (x) in the X direction of the ion beam 28 at the position of the substrate 6. Ask for. More specific contents are substantially the same as the contents described above for the step 101 for obtaining the current density distribution in FIG.

The uniformity calculation unit 64 uses the obtained current density distribution f (x) and the scan waveform of the substrate 6 and changes the combination of the scan number N _S and the rotation number N _R of the substrate 6 in a plurality of combinations, For each combination, calculate the dose density W of the ion beam at a plurality of points on the substrate 6 and calculate the uniformity U of the beam dose density on the substrate 6 based on the dose density W. The uniformity U of the beam dose density at each combination of the scan number N _S and the rotation number N _R of the substrate 6 is output. The more specific contents are substantially the same as those described above for the uniformity calculation step 102 in FIG.

  The output from the uniformity calculation unit 64 may be, for example, a signal to be displayed on a display or a signal to be printed by a printer. The format of the output data may be, for example, a table format as shown in Tables 1 and 2 above, a graph format as shown in FIG. 26 described later, or other formats. The control device 50 may have a display device that displays the output.

The combination storage unit 66 outputs a predetermined combination of a plurality of combinations of the scan number N _S and the rotation number N _R of the substrate 6 after the uniformity U of the beam irradiation density is output from the uniformity calculation unit 64. In response to an input to be selected, the selected combination is stored. For example, if the operator selects a combination that provides a desired uniformity from a plurality of combinations of the scan number N _S and the rotation number N _R of the substrate 6 and inputs the selected combination to the combination storage unit 66. good. For example, the input may be performed by a keyboard, a touch panel, or the like. The control device 50 may have such an input device.

The drive control unit 68 is configured so that when the ion beam 28 is irradiated onto the substrate 6, the scan mechanism 14 is configured to have a combination of the scan number N _S and the rotation number N _R of the substrate 6 stored in the combination storage unit 66. And the rotation mechanism 10 is controlled.

  Note that the processing such as the calculation in the current density distribution calculation unit 62, the uniformity calculation unit 64, and the combination storage unit 66 may be performed for each of the substrates 6 to be processed, or for each of the plurality of substrates 6. For example, it may be performed for each lot. The same applies to other embodiments described later.

According to the ion beam irradiation apparatus has a control device 50 as described above, accurately scan number N _S and the rotational speed N _R of the substrate can be performed with good uniformity ion beam irradiating the substrate 6 It becomes easier to decide. As a result, it becomes easy to perform ion beam irradiation with good uniformity on the substrate 6.

  As in the example illustrated in FIG. 15, the control device 50 may include a current density distribution storage unit 70 (current density distribution storage unit). That is, instead of providing the beam measuring device (for example, the beam measuring device 52), the beam current density in the X direction measured in advance by an experiment or the like by using an ion beam irradiation device equivalent to the ion beam irradiation device, for example. The distribution is measured, and the result is stored in the current density distribution storage unit 70. Based on the stored beam current density distribution, the current density distribution calculation unit 62 determines the ions at the position of the substrate 6. The current density distribution f (x) in the X direction of the beam 28 may be obtained and used.

  Also in this case, as described above, for example, the beam current density distribution is experimentally measured for each recipe in advance and stored in the current density distribution storage unit 70. A corresponding beam current density distribution may be used.

  The other parts of the control device 50 are the same as the example shown in FIG.

  By doing as described above, it is not necessary to provide a beam measuring device for measuring the beam current density distribution in the actual ion beam irradiation apparatus, so that the configuration of the ion beam irradiation apparatus can be simplified.

  Note that both the combination storage unit 66 and the current density distribution storage unit 70 may be configured by a single storage device. In other words, one storage device may be shared by the combination storage unit 66 and the current density distribution storage unit 70. The same applies to other embodiments described later.

(4) Background Art Leading to Other Embodiments of Ion Beam Irradiation Method and Ion Beam Irradiation Apparatus Background arts leading to other embodiments will be described below. As the substrate 6, a substrate in which a plurality of columnar elements are formed side by side on the substrate may be used, and a process such as milling may be performed on the side surface of each columnar element by irradiation with the ion beam 28.

  For example, in the following Patent Documents 3 and 4, in manufacturing a magnetoresistive effect element such as an MRAM (Magnetic Random Access Memory), the side surface of an MTJ element (magnetic tunnel junction element) which is an example of a columnar element on a substrate is described. A technique for performing treatment by irradiating an ion beam is described.

Patent Document 3: JP-A-2005-44848
Patent Document 4: JP2011-166157A

  More specifically, Patent Document 3 discloses a technique for reducing the defect rate of MTJ elements by using ion etching by oblique incidence to suppress adhesion of substances scattered by etching to the side surfaces of the MTJ elements. (See paragraphs 0095 and 0098, FIGS. 7 and 16, for example).

  Patent Document 4 describes a technique for forming a small and excellent MTJ element by obliquely incident and trimming the side wall of the MTJ element and removing a residue (for example, claim 1, paragraphs 0006 and 0036). FIG. 2 and FIG. 4).

  In these applications, in order to change the beam incident angle with respect to the side surface of the cylindrical element on the substrate, the substrate is tilted (that is, with the angle corresponding to the substrate tilt angle θ described above being other than 0 degrees). ) Ion beam irradiation is performed. In addition, the substrate is rotated in order to irradiate the ion beam to the entire circumference of the side surface of the cylindrical element with good uniformity.

  Processing such as milling of the side surfaces of the columnar elements needs to be performed with good uniformity on the columnar elements distributed and disposed on substantially the entire surface of the substrate. If the process on the side surface of the cylindrical element is not uniform, the element shape after the process becomes asymmetric with respect to the central axis of the element, and the element performance deteriorates. In addition, if the processing for a plurality of columnar elements arranged on substantially the entire surface of the substrate is not uniform, the element performance will vary, which will have a serious adverse effect on device production. Therefore, in these applications, it is important to perform processing with good uniformity on the side surface of the cylindrical element.

  In such an application, if the ion beam irradiation method or ion beam irradiation apparatus of the above-described embodiment of the present invention is used as it is, the following problems may occur.

For example, in Table 2, when the number of substrate scans _NS is one and the number of substrate rotations _NR is two, the uniformity U is ± 0% and good uniformity is obtained. However, this uniformity U is the uniformity of the beam irradiation density on the surface of the substrate 6 as described above. With reference to FIG. 16, it will be described that even if the above combination is adopted for the processing of the side surface of the cylindrical element on the substrate, processing such as milling becomes non-uniform.

  FIG. 16A shows the distribution of the ion beam 28 in the case of 1 / e width = 4/5 in FIG. 12, and corresponds to the conditions shown in Table 2. FIG. 16B shows the time lapse of the scan of the tilted substrate 6 in the direction of arrow D, and is performed every ¼ scan from (a) to (e), and one scan is made in total. . In order to simplify the description, a case where a prism (more specifically, a quadratic prism) 56 is provided at the center on the substrate 6 instead of the cylindrical element is schematically shown. In order to make the drawing easier to see, one side surface 56a of the prism 56 is shown by a thick line, and the opposite side surface 56b is shown by a broken line. FIG. 16C shows the time elapse of the rotation of the substrate 6 in the C direction, showing the substrate rotation position for every 1/4 scan, and is a total of 2 rotations. A notch 7 is provided so that the direction of the substrate 6 accompanying the rotation is known.

  At the time of 0 scan of (a), the side surface 56a of the prism 56 is irradiated with the ion beam 28, and the opposite side surface 56b is shaded so that the ion beam 28 does not hit. At this time, the distribution of the ion beam applied to the side surface 56a is a peak as shown in FIG. 5A, and the ion beam intensity (that is, the beam current density, the same applies hereinafter) is large.

  At the time of 1/4 scan of (b), the side surface 56b of the prism 56 is irradiated with the ion beam 28. At this time, the ion beam distribution irradiated to the side surface 56b is a valley portion as shown in (A). The ion beam intensity is small.

  The 2/4 scan of (c) is the same as that of (a), the side surface 56a is again irradiated with the ion beam 28, and the ion beam intensity is high.

  In the 3/4 scan of (d), the side surface 56b of the prism 56 is again irradiated with the ion beam 28. At this time, the ion beam distribution irradiated to the side surface 56b is a valley portion as shown in (A). Yes, the ion beam intensity is small.

  At the time of 4/4 scan of (e), the state is returned to the state of (a), the side surface 56a is again irradiated with the ion beam 28, and the ion beam intensity is high.

  As described above, in the example shown in FIG. 16, the side surface 56a of the prism 56 on the substrate 6 has a large ion beam intensity every time it comes in the direction of receiving the ion beam 28, and the opposite side surface 56b The ion beam intensity is small every time it is in the direction of receiving 28 irradiation. Therefore, the ion beam irradiation intensity on the side surfaces of the prisms 56 on the substrate 6 is not uniform, and therefore processing such as milling is not uniform. Although the above description has been made using the prism 56 for the sake of simplification of explanation, the same result as described above is obtained when a cylindrical element is provided on the substrate 6.

  Therefore, in order to uniformly process the side surface of the cylindrical element on the substrate 6, further contrivance is necessary.

  In addition, the cylindrical element is not yet formed on the substrate, and the cylindrical element is formed on the substrate (that is, on the surface of the substrate or a film (for example, a multilayer film) formed on the surface). A columnar mask (for example, a columnar metal or a columnar resist mask) is formed, and a columnar element is formed on the substrate under the columnar mask by ion milling or the like using the columnar mask. In this case as well, the shape of the columnar mask affects the shape of the columnar element formed thereunder, so that the side surface of the columnar mask is further formed and the columnar shape that is still under formation It is important to treat the side surfaces of the element uniformly.

  As terms of high-level concepts including three of (a) a cylindrical element, (b) a cylindrical mask, and (c) a combination of a cylindrical mask and a cylindrical element under formation as described above. In the following, a cylindrical body is used.

  In the following, an embodiment of an ion beam irradiation method and an ion beam irradiation apparatus capable of performing processing with good uniformity on the side surfaces of a plurality of cylindrical bodies on a substrate will be described. In the following description, the same or corresponding parts as those of the previous embodiment are denoted by the same reference numerals, and differences from the previous embodiment will be mainly described.

(5) Other Embodiments of Ion Beam Irradiation Apparatus FIG. 17 is a schematic sectional view showing another embodiment of an ion beam irradiation apparatus for carrying out the ion beam irradiation method according to the present invention, and corresponds to FIG. Yes.

  In the following embodiment, as the substrate 6 held by the holder 8, the substrate 6 in which a plurality of cylindrical bodies 54 (see FIG. 19) are formed side by side on the substrate, for example, on substantially the entire surface of the substrate. deal with. However, in FIG. 19, in order to make the explanation easy to understand, the cylindrical body 54 is enlarged to show only one.

  The columnar body 54 may be formed on the surface of the substrate 6 or may be formed on a film (for example, a multilayer film) formed on the surface of the substrate 6. As described above, the columnar body 54 may be (a) a columnar element, or (b) a columnar mask (for example, a columnar metal or a columnar resist mask) for forming the columnar element. (C) A combination of a cylindrical mask and a cylindrical element under the formation may be used. The columnar element may be a single-layer element or a multi-layer element. Further, in this application, the “columnar body” is used to include a column, a truncated cone, and an element having a shape close thereto.

  The ion beam irradiation apparatus shown in FIG. 17 also tilts the holder 8 and the substrate 6 held by the rotation mechanism 10, the holder 8, and the substrate 6 held by the rotation mechanism 10 as shown by the arrow E, thereby tilting the substrate 6. The substrate tilting mechanism 12 and the like that can make the substrate tilting angle θ, which is an angle formed by the vertical line of the ion beam 28 and the traveling direction of the ion beam 28, 0 ° or more.

  For example, the substrate tilting mechanism 12 can change the substrate tilt angle θ in the range of 0 ° ≦ θ ≦ 90 °, but is not limited thereto. For example, the variable range of the angle θ may be about 0 ° ≦ θ ≦ 60 °.

  Other configurations of the ion beam irradiation apparatus include, for example, the configuration of the ion source 20, the size / current density distribution of the ion beam 28, the scan mechanism 14, the scan waveform of the substrate 6, the beam measuring instrument 52, etc. This is substantially the same as that described with reference to FIG. However, the control device 50 is different. The difference will be described later.

(6) Other Embodiments of Ion Beam Irradiation Method Next, embodiments of the ion beam irradiation method in the ion beam irradiation apparatus as described above will be described. The main points of this ion beam irradiation method are as follows.

(A) Using the substrate tilting mechanism 12, the substrate tilt angle θ is set to a predetermined angle excluding 0 degrees. This step will be referred to as a substrate tilt angle setting step 100 as shown in FIG.
(B) Based on the current density distribution measured by the beam measuring device (for example, the beam measuring device 52), the current density distribution f (x) in the X direction of the ion beam 28 at the position of the substrate 6 is obtained. This step is referred to as a step 101 for obtaining a current density distribution as shown in FIG.
(C) the determined current density distribution f (x), using the scan waveform and the predetermined substrate inclination angle θ of the substrate 6, and combining a plurality of said number of scans N _S and the rotational speed N _R of the substrate 6 For each combination, the amount of treatment by the ion beam 28 for each side surface of each of the plurality of columnar bodies 54 on the substrate 6 is calculated, and the plurality of columnar bodies 54 are calculated based on the amount of treatment. Calculate the throughput uniformity for the side of This step is called a uniformity calculation step 102a as shown in FIG.
(D) Based on the calculated processing amount uniformity, a combination of the scan number N _S and the rotation number N _R of the substrate 6 that obtains the desired processing amount uniformity is determined. This step is called a combination determination step 103 as shown in FIG.
(E) The substrate 6 is irradiated with the ion beam 28 by a combination of the determined scan number N _S and rotation number N _R. This step is referred to as an ion beam irradiation step 104 as shown in FIG.

  Of the steps (a) to (e), the substrate tilt angle setting step 100 will not require further explanation. The step 101 for obtaining the current density distribution, the combination determining step 103, and the ion beam irradiation step 104 are substantially the same as the corresponding steps in FIG. The uniformity calculation step 102a is different from the uniformity calculation step 102 in FIG. 13 described above, and will be described in detail below.

(6-1) Rotation and Scan of Substrate 6 As shown in FIG. 19, the substrate tilt mechanism 12, the rotation mechanism 10 and the scan mechanism 14 tilt the substrate 6 to the substrate tilt angle θ, for example, the arrow C Rotate in direction and scan in arrow D direction.

As shown in a simplified manner in FIG. 19, the rotation direction of the substrate 6 is the arrow C direction, the scan direction D of the substrate 6 is the X direction, and the time period of the scan is T _S. Further, the time change x (t) of the center point of the substrate 6 at time t = 0 is expressed by the following equation. This is the same formula as the previous equation (1). Here, g (t) is a periodic function with respect to time.

[Equation 11]
x (t) = g (t)

Even below, as an example, the periodic function g (t), as shown in FIG. 11, the amplitude P _2/2, the period is a triangular wave of T _S. In this case, the scanning width W _S of the substrate 6 is equal to the period P _2.

(6-2) Rotation and scanning of tilted substrate 6 When only the substrate 6 is rotated, the coordinate system (X ′, Y ′, Z) of the point Q (x, y) on the substrate 6 taken on the substrate plane The time movement (X ′ (t), Y ′ (t)) in “) is expressed by the following equation using the initial position (R, φ) on the substrate 6. Here, R is the radius of the initial position, φ is the initial angle (that is, the angle at time t = 0 with respect to the X axis that is the scanning direction), and ω is the angular velocity of the substrate rotation.

[Equation 12]
x ′ (t) = R · cos (ωt + φ)
y ′ (t) = R · sin (ωt + φ)

  Next, as shown in FIG. 19B, when the substrate 6 is tilted to the substrate tilt angle θ, if the coordinate system before tilting is (X, Y, Z), this coordinate system (X, Y, Z ) With respect to the time point (x (t), y (t)) of the point Q on the substrate 6 is expressed by the following equation.

[Equation 13]
x (t) = R · cos (ωt + φ) · cos (θ)
y (t) = R · sin (ωt + φ)

  Therefore, the trajectory of the point Q (x, y) on the substrate 6 when the substrate 6 is scanned and rotated is expressed by the following equation, taking into account the equation 11 that is the scan equation.

[Formula 14]
x (t) = g (t) + R · cos (ωt + φ) · cos (θ)
y (t) = R · sin (ωt + φ)

  As described above, since the current density distribution in the Y direction of the ion beam 28 extracted from the ion source 20 is substantially uniform in a range equal to or larger than the dimension of the substrate 6, the beam dose density at each point on the substrate 6. The x position is necessary for evaluating the uniformity of the.

(6-3) Processing speed at the time of ion beam irradiation When processing is performed by irradiating the side surface of the cylindrical body 54 on the tilted substrate 6 with the ion beam 28, the processing speed varies depending on the beam incident angle with respect to the side surface. This will be described below. In the following, ion milling is taken up as an example of processing.

The sputtering rate Y _i of the target material by ion irradiation can be obtained by calculation using public software SRIM (The Stopping and Range of Ions in Matter) or the like. That is, a predetermined incidence depends on the type of ion (eg, Ar ⁺ , Ne ⁺ , He ⁺ , Kr ^+, etc.), ion energy [eV], and the type of target material (eg, Co, Fe, Ta, Mg, etc.). Since the sputtering rate Y _i in the case of the angle α [degree] can be obtained, it is performed.

For example, FIG. 20 shows an example of the result of calculating the sputtering rate Y _i at each incident angle α by SRIM when the target material is Co (cobalt), the ion is Ar ⁺ , and the energy is 500 eV. It can be seen that the sputtering rate Y _i varies with the incident angle α.

Using the sputtering rate Y _i obtained as described above, the milling rate R _m by ions is calculated according to the following equation. Here, [rho is the density of the target material, the m _i mass of the target material atoms, I is an ion beam current density, e is the elementary charge.

Thus, the calculation of the milling rate R _m for the side surface of the cylindrical body 54 on the substrate 6 requires the incident angle of the ion beam with respect to the side surface, and the calculation of the incident angle will be described next. In order to simplify the calculation, the cylindrical body 54 may be approximated by a regular polygonal column (for example, a regular 20-sided prism).

(6-4) Beam incident angle β with respect to the side surface of the cylindrical body FIG. 21 shows the beam incident angle β with respect to the side surface of the prism (more specifically, quadrangular column) 56 on the substrate 6 inclined by the angle θ. Here, a prism 56 is used instead of the cylindrical body 54 so that the relationship can be easily seen. The beam incident angle β is an angle formed by the surface normal i ′ _p of the side surface of the prism 56 and the traveling direction of the ion beam 28. p is a side number. In the case of the cylindrical body 54, the beam incident angle β is an angle formed by the surface normal line i ′ _p of the side surface of the cylindrical body 54 and the traveling direction of the ion beam 28.

When the substrate 6 rotates (see arrow C), the prism 56 rotates around the Z ′ axis, so that the surface normal i ′ _p changes its direction three-dimensionally. For example, if the surface normal vector at time t is i ′ _p (ωt), the surface normal vector after Δt time is i ′ _p {ω (t + Δt)}, and the beam incident angle β also changes. Therefore, the surface normal is represented by a three-dimensional vector, and the beam incident angle β is obtained by calculation. This will be described below.

  As shown in FIG. 22, the basic vector (i, j, k) of the (X, Y, Z) coordinate system and the basic vector (i ′, j ′, k ′) on the tilted substrate 6 are taken. Reference numeral 80 denotes a unit circle. When the substrate tilt angle is θ, the relationship between both basic vectors (i, j, k) and (i ′, j ′, k ′) is as follows.

[Equation 16]
i ′ = i · cos (θ) + k · sin (θ)
j '= j

  When the substrate 6 rotates at the angular velocity ω, the change of the basic vector i ′ on the substrate 6 with time t is expressed by the following equation in the (X, Y, Z) coordinate system.

[Equation 17]
i ′ (ωt) = i ′ · cos (ωt) + j ′ · sin (ωt)
= I · cos (θ) · cos (ωt) + k · sin (θ) ·
cos (ωt) + j · sin (ωt)

A surface normal vector of another side surface of the cylindrical body 54 or the prism can be obtained by shifting the phase of the vector i ′ (ωt). This will be described with reference to FIG. 23. When the cylindrical body 54 is approximated by a polygonal column, when the side surface number is p (p is an integer of 1 ≦ p ≦ n and n is an integer of 3 or more), the side surface The surface normal unit vector i ′ _p (ωt) of S _p is expressed by the following equation. η _p is the initial angle of the side surface p (that is, the angle at time t = 0 with respect to the X axis that is the scanning direction). In this example, the initial angle η ₁ of the side surface S ₁ is set to 0 degree.

[Equation 18]
i ′ _p (ωt) = i · cos (θ) · cos (ωt + η _p ) + k · sin (θ) ·
cos (ωt + η _p ) + j · sin (ωt + η _p )

  On the other hand, since the ion beam 28 travels in the −Z direction in this embodiment as described above, the unit vector in the traveling direction of the ion beam 28 is −k as shown in FIGS. 22 and 24 (here, the ion beam). The divergence angle of 28 is ignored because it is small).

Therefore, regarding the beam incident angle β _{p with} respect to the S _p side surface of the ion beam 28, calculation in the middle is omitted from the inner product of the surface normal unit vector i ′ _p (ωt) and the beam traveling direction unit vector −k. The following relationship is obtained.

[Equation 19]
cos (β _p ) = sin (θ) · cos (ωt + η _p )

Therefore, from the above equation, the beam incidence angle beta _p for S _p side of the ion beam 28 can be determined by the following equation. Here, the sign is + (plus) when the ion beam 28 is incident on the front surface of the side surface, and − (minus) when it is incident on the back surface of the side surface. In the case of the back surface, since it is behind the cylindrical body 54, beam incidence does not occur.

[Equation 20]
β _p = acos {sin (θ) · cos (ωt + η _p )}

(6-5) Change in Beam Current Density with Beam Incident Angle β Next, the change in beam current density with the beam incident angle β is calculated. When the beam current density of the ion beam 28 is I, the beam current density I ′ of the cylindrical body 54 with respect to the side surface having the beam incident angle β _p is expressed by the following equation as can be seen from FIG. The

[Equation 21]
I ′ = I / {1 / cos (β _p )}
= I · cos (β _p )

As described above, the change in the beam incident angle β with respect to the side surface of the cylindrical body 54 causes (a) the change in the sputtering rate Y _i and (b) the change in the beam current density I ′. In calculating the processing amount of the side surface of the body 54, for example, the milling thickness, the above (a) and (b) are reflected.

That is, milling thickness D _p for side S _p of the cylindrical body 54 on the substrate 6 scanned once (i.e. one round trip lines) of the case where the substrate 6 scanned and rotated tilted, the current density in the number of 21 As I, the beam current density distribution f (x) described above with reference to FIG. 9 or the like is used, and this is expressed by the following equation using the above equation (15).

Substituting x (t) in Equation 14 into this equation yields the following equation. This is milling thickness D _p for side S _p of the cylindrical body 54 scans once (i.e. one round trip lines) of the substrate 6 in case of scanning and rotating the substrate 6 inclined angle theta.

When the number of scans N _S and the number of rotations N _R (N _S , N _R are integers of one or more or half integers) of the substrate 6 are added to the above formula, the following is obtained. That is, it is assumed that the substrate 6 rotates N _{R at} the time of N _S scan t = N _S · T _S. In this case, the following relationship is established. This is the same formula as Equation 5 above.

[Equation 24]
ω (N _S · T _S ) = 2π · N _R
∴ω = 2π (N _R / N _S ) (1 / T _S )

By substituting this into equation 23 and setting the range of integration to 0 to N _S · T _S , the following equation is obtained. This is a substrate 6 inclined angle theta N _S scans and N _R milling thickness D _p for side S _p of the cylindrical body 54 on the substrate 6 when rotating.

In order to calculate the uniformity of the processing amount with respect to the side surfaces of the plurality of cylindrical bodies 54 on the substrate 6, for example, the uniformity of the milling thickness, the milling thickness D _p of the equation 25 is set to the side number p, the radius R, and the initial value. The angle φ is changed in predetermined increments, and the calculation is performed for all side surfaces of each columnar body 54 with respect to all the plurality of columnar bodies 54 arranged on the substrate 6.

  An example of this step is shown in the following equation, but is not limited to this. Further, the following formula is an example in which a plurality of columnar bodies 54 are concentrically arranged, but the present invention is not limited to this, and may be arranged in a lattice shape.

[Equation 26]
p = 20 (that is, a cylinder is approximated by a regular 20 prism)
ΔR = R / 20 (ie, the radius is divided into 20 equal parts)
Δφ = 2π / 72 (ie, one round is divided into 72 equal parts)

Yet, by changing the combination of the scan number N _S and the rotational speed N _R of the substrate 6 by a plurality of combinations, the calculation of the milling thickness D _p for each combination.

The processing amount uniformity for the side surfaces of the plurality of cylindrical bodies 54 on the substrate 6, for example, the milling uniformity U _sm is calculated according to the following equation. Here, D _pmax is the maximum value of the milling thickness on the side surface of the entire cylindrical body 54 disposed on the substrate 6, and D _pmin is the minimum value of the milling thickness on the side surface of the entire cylindrical body 54.

[Equation 27]
U _sm = (D _pmax −D _pmin ) / (D _pmax + D _pmin )

  The processing amount uniformity other than the milling thickness can be calculated in the same manner as described above.

  The above is a detailed example of the uniformity calculation step 102a in FIG. Subsequent steps 103 and 104 are as described above, and thus a duplicate description is omitted here.

  Note that when viewed closely, the processing amount uniformity obtained by the uniformity calculation step 102a (for example, milling uniformity) does not take into account the reattachment of scattered substances to the side of the cylindrical body accompanying ion beam irradiation. It does not necessarily match the shape uniformity of the cylindrical body side surface.

(6-6) Calculation Example of Milling Uniformity U _sm Next, a specific example of calculating the milling uniformity U _sm according to the uniformity calculation step 102a will be described.

Here, as an example, the ion beam 28 is Ar ⁺ ion having an energy of 500 eV, the material of the cylindrical body 54 is Co (cobalt), and the substrate tilt angle θ is 45 degrees.

As an example, the current density distribution I (x) of each peak portion in the X direction of the ion beam 28 at the position of the substrate 6 is a Gaussian distribution represented by the following equation (actually, the beam measuring device 52 is The current density distribution I (x) measured by using it may be used). Here, x is a position in the X direction on the substrate 6, I ₀ is a peak intensity, d is a width at which the peak intensity is 1 / e (this will be referred to as 1 / e width. E is a natural logarithm). E = 2.718).

[Equation 28]
I (x) = I ₀ · exp (−x ² / d ² )

In the following, in order to simplify the calculation, the normalized beam current density distribution obtained by normalizing the beam current density distribution of the above equation by I ₀ (ie, dividing by I ₀ and setting the peak intensity to 1) is shown below. Use. FIG. 25 is illustrated using this. If normalization with I ₀ is not performed, the entire right side of the following formula 29 may be put in parentheses and I ₀ may be added to the head.

The period of the beam current density distribution in the scanning direction on the substrate 6 and P _2, the distance units and P _2/2. The beam current density distribution shown in FIG. 25 is an example in which there are five crests on the substrate 6 and the respective centers in the unit of distance are x = −4, −2, 0, 2, 4 respectively. is there.

The 1 / e width (= d) of each peak portion was calculated under three conditions of d = 1/2, 2/3, and 4/5. These show examples in which the divergence angles of the ion beams extracted from the region A ₁ from which each ion beam of the extraction electrode system 24 of the ion source 20 is extracted are small, medium, and large, respectively.

  The beam current density distribution f (x) on the substrate 6 of the entire ion beam 28 having the five peak portions can be expressed by the following equation.

[Equation 29]
f (x) = exp {− (x + 4) ² / d ² } + exp {− (x + 2) ² / d ² }
+ Exp {−x ² / d ² } + exp {− (x−2) ² / d ² }
+ Exp {− (x−4) ² / d ² }

  FIG. 25 summarizes the beam current density distribution f (x) expressed by the above equation 29 with respect to each 1 / e width.

In triangular scan waveform of the substrate 6 has been described above, the case where the beam current density distribution on the substrate 6 is of three kinds shown in FIG. 25, as one scan number N _S of the substrate 6, the rotational speed N _R of the substrate 6 Was changed from 2 to 10 times, including the intermediate half-integer times, and the milling uniformity U _sm was calculated. The result is shown in FIG.

As can be seen from this figure, when the 1 / e width is 1/2 or more, the milling uniformity U _sm is ± 10% or less when the rotation speed N _R of the substrate 6 is an integer of 6 or more, Good results have been obtained.

Thus, according to the ion beam irradiation method, accurately determine the number of scans N _S and the rotational speed N _R of the substrate which can be subjected to a good process uniformity with respect to the side surface of the cylindrical body 54 on the substrate 6 Thus, a process with good uniformity can be performed on the side surface of the cylindrical body 54 on the substrate 6.

  Also in the case of this ion beam irradiation method, instead of providing the beam measuring device (for example, the beam measuring device 52), for example, by using an ion beam irradiation device equivalent to the ion beam irradiation device, etc. The beam current density distribution in the measured X direction is measured, and the result is stored in storage means, for example, a storage device in the control device 50, and stored in step 101 for obtaining the current density distribution. Based on the beam current density distribution, the current density distribution f (x) in the X direction of the ion beam 28 at the position of the substrate 6 may be obtained and used.

  By doing as described above, it is not necessary to provide a beam measuring device for measuring the beam current density distribution in the actual ion beam irradiation apparatus, so that the configuration of the ion beam irradiation apparatus can be simplified.

(7) Other More Specific Examples of Control Device 50 The control device 50 may have a function of performing the ion beam irradiation method of (6). An example of the configuration of the control device 50 in that case will be described below. In the following, the same or corresponding parts as those in the examples shown in FIGS. 14 and 15 are denoted by the same reference numerals, and differences from the examples shown in FIGS. 14 and 15 will be mainly described.

  The control device 50 shown in FIG. 27 includes a substrate tilt angle control unit 72 (substrate tilt angle control unit) and a uniformity calculation unit 64a (uniformity calculation unit). Since the configuration other than these is the same as that described with reference to FIG. 14, redundant description is omitted here.

  The substrate tilt angle control unit 72 controls the substrate tilt mechanism 12 to control the substrate tilt angle θ to a predetermined angle excluding 0 degrees. For example, the predetermined substrate inclination angle θ may be set in the substrate inclination angle control unit 72.

Uniformity calculating unit 64a, a manner determined current density distribution as described above, by using the scan waveform and the substrate inclination angle θ of the substrate 6, and a combination of the scan number N _S and the rotational speed N _R of the substrate 6 For each combination, the amount of treatment by the ion beam 28 for each side surface of the plurality of cylindrical bodies 54 is calculated for each combination, and the side surfaces of the plurality of cylindrical bodies 54 are calculated based on the amount of treatment. The processing amount uniformity is calculated for each combination of the scan number N _S and the rotation number N _R of the substrate 6. More specific contents are substantially the same as those described above for the uniformity calculation step 102a in FIG.

According to the ion beam irradiation apparatus including the control device 50 as described above, the number of scans _NS and rotation of the substrate that can perform processing with good uniformity on the side surface of the cylindrical body 54 on the substrate 6. It becomes easy to accurately determine the number N _R. As a result, it becomes easy to perform a process with good uniformity on the side surface of the cylindrical body 54 on the substrate 6.

  As in the example illustrated in FIG. 28, the control device 50 may include a current density distribution storage unit 70 (current density distribution storage unit). Since this current density distribution storage unit 70 is the same as that shown in FIG. 15, the previous description thereof will be referred to, and a duplicate description will be omitted here.

  Other parts of the control device 50 are the same as the example shown in FIG.

  By doing as described above, it is not necessary to provide a beam measuring device for measuring the beam current density distribution in the actual ion beam irradiation apparatus, so that the configuration of the ion beam irradiation apparatus can be simplified.

DESCRIPTION OF SYMBOLS 4 Vacuum container 6 Substrate 8 Holder 10 Rotation mechanism 14 Scan mechanism 20 Ion source 22 Plasma generation part 24 Extraction electrode system 26 Ion beam extraction area 28 Ion beam 50 Controller 52 Beam measuring instrument 54 Cylindrical body 62 Current density distribution calculation part 64 64a Uniformity calculation unit 66 Combination storage unit 68 Drive control unit 70 Current density distribution storage unit 72 Substrate tilt angle control unit 100 Substrate tilt angle setting step 101 Step for obtaining current density distribution 102, 102a Uniformity calculation step 103 Combination determination step 104 Ion beam irradiation process A ₁ Area where ion beam is extracted B ₁ Area where ion beam is not extracted NS Number of scans of N _S substrate Number of rotations of N _R substrate θ Substrate tilt angle

Claims (10)

A vacuum vessel that is evacuated to vacuum,
A holder that is housed in the vacuum vessel and holds a substrate;
A rotation mechanism for rotating the holder and the substrate held by the holder around the center of the substrate;
An ion source that has a plasma generation unit that generates plasma and an extraction electrode system that extracts an ion beam from the plasma by the action of an electric field, and irradiates the extracted ion beam onto a substrate held by the holder, In the extraction electrode system, a region where the ion beam is extracted and a region where the ion beam is not extracted are alternately arranged in the X direction at a predetermined period, and the region where the ion beam is extracted from the region where the ion beam is extracted An ion source for extracting an ion beam having a substantially uniform current density distribution in a range equal to or larger than the dimension of the substrate in a Y direction substantially orthogonal to the X direction;
A scanning mechanism for mechanically reciprocatingly scanning the holder, the substrate held by the holder, and the rotating mechanism substantially in the X direction with a predetermined scanning waveform;
An ion beam irradiation apparatus comprising: a beam measuring device that measures a current density distribution of the ion beam in the X direction;
Based on the current density distribution measured by the beam measuring device, obtain a current density distribution in the X direction of the ion beam at the position of the substrate,
Irradiation of an ion beam at a plurality of points on the substrate for each combination by using the obtained current density distribution and the scan waveform of the substrate and changing the combination of the scan number and the rotation number of the substrate by a plurality of combinations. Calculating the dose density, and calculating the uniformity of the beam dose density on the substrate based on the dose density;
Based on the calculated uniformity, determine the combination of the number of scans and the number of rotations of the substrate that achieves the desired uniformity,
An ion beam irradiation method comprising irradiating the substrate with an ion beam with a combination of the determined scan number and rotation number. A vacuum vessel that is evacuated to vacuum,
A holder that is housed in the vacuum vessel and holds a substrate;
A rotation mechanism for rotating the holder and the substrate held by the holder around the center of the substrate;
An ion source that has a plasma generation unit that generates plasma and an extraction electrode system that extracts an ion beam from the plasma by the action of an electric field, and irradiates the extracted ion beam onto a substrate held by the holder, In the extraction electrode system, a region where the ion beam is extracted and a region where the ion beam is not extracted are alternately arranged in the X direction at a predetermined period, and the region where the ion beam is extracted from the region where the ion beam is extracted An ion source for extracting an ion beam having a substantially uniform current density distribution in a range equal to or larger than the dimension of the substrate in a Y direction substantially orthogonal to the X direction;
A scanning mechanism for mechanically reciprocatingly scanning the holder, the substrate held by the holder, and the rotating mechanism substantially in the X direction with a predetermined scanning waveform;
In an ion beam irradiation apparatus comprising a storage means for storing the current density distribution of the ion beam in the X direction and used for determining the number of scans and the number of rotations of the substrate,
Based on the stored current density distribution, a current density distribution in the X direction of the ion beam at the position of the substrate is obtained.
Irradiation of an ion beam at a plurality of points on the substrate for each combination by using the obtained current density distribution and the scan waveform of the substrate and changing the combination of the scan number and the rotation number of the substrate by a plurality of combinations. Calculating the dose density, and calculating the uniformity of the beam dose density on the substrate based on the dose density;
Based on the calculated uniformity, determine the combination of the number of scans and the number of rotations of the substrate that achieves the desired uniformity,
An ion beam irradiation method comprising irradiating the substrate with an ion beam with a combination of the determined scan number and rotation number. The scan waveform of the substrate is substantially a triangular wave;
3. The ion beam irradiation method according to claim 1, wherein a combination in which the number of scans and the number of rotations of the substrate are the same is excluded when calculating the dose density and uniformity of the ion beam. (A) a vacuum container that is evacuated to a vacuum;
(B) a holder that is housed in the vacuum vessel and holds the substrate;
(C) a rotation mechanism for rotating the holder and the substrate held by the holder around the center of the substrate;
(D) An ion source that has a plasma generation unit that generates plasma and an extraction electrode system that extracts an ion beam from the plasma by the action of an electric field, and that irradiates the extracted ion beam onto a substrate held by the holder. The extraction electrode system alternately arranges the region from which the ion beam is extracted and the region from which the ion beam is not extracted at a predetermined period in the X direction, and from the region from which the ion beam is extracted, An ion source for extracting an ion beam having a substantially uniform current density distribution in a range equal to or larger than the dimension of the substrate in the Y direction substantially perpendicular to the X direction at a position of
(E) a scanning mechanism for mechanically reciprocatingly scanning the holder, the substrate held by the holder, and the rotating mechanism substantially in the X direction with a predetermined scanning waveform;
(F) a beam measuring device for measuring a current density distribution of the ion beam in the X direction;
(G) an ion beam irradiation apparatus comprising at least a control device having a function of controlling the rotation mechanism and the scan mechanism,
The control device includes:
(A) current density distribution calculating means for obtaining a current density distribution in the X direction of the ion beam at the position of the substrate based on the current density distribution measured by the beam measuring device;
(B) Using the obtained current density distribution and the scan waveform of the substrate, and changing the number of scans and rotations of the substrate in a plurality of combinations, for each combination, ions at a plurality of points on the substrate The beam irradiation density at the time of each combination of the number of scans and the number of rotations of the substrate is calculated by calculating the beam irradiation density and calculating the uniformity of the beam irradiation density on the substrate based on the irradiation density. Uniformity calculation means for outputting the uniformity of quantity density,
(C) After the uniformity of the beam irradiation dose density is output, the selected combination is received from among a plurality of combinations of the scan number and the rotation number of the substrate, and the selected combination is stored. Combination storage means to
(D) drive control means for controlling the scanning mechanism and the rotation mechanism so that the combination of the number of scans and the number of rotations of the substrate stored in the combination storage means when irradiating the ion beam to the substrate; An ion beam irradiation apparatus characterized by comprising: (A) a vacuum container that is evacuated to a vacuum;
(B) a holder that is housed in the vacuum vessel and holds the substrate;
(C) a rotation mechanism for rotating the holder and the substrate held by the holder around the center of the substrate;
(D) An ion source that has a plasma generation unit that generates plasma and an extraction electrode system that extracts an ion beam from the plasma by the action of an electric field, and that irradiates the extracted ion beam onto a substrate held by the holder. The extraction electrode system alternately arranges the region from which the ion beam is extracted and the region from which the ion beam is not extracted at a predetermined period in the X direction, and from the region from which the ion beam is extracted, An ion source for extracting an ion beam having a substantially uniform current density distribution in a range equal to or larger than the dimension of the substrate in the Y direction substantially perpendicular to the X direction at a position of
(E) a scanning mechanism for mechanically reciprocatingly scanning the holder, the substrate held by the holder, and the rotating mechanism substantially in the X direction with a predetermined scanning waveform;
(F) an ion beam irradiation apparatus including at least a control device having a function of controlling the rotation mechanism and the scan mechanism,
The control device includes:
(A) current density distribution storage means for storing a current density distribution of the ion beam in the X direction, which is used for determining the number of scans and the number of rotations of the substrate;
(B) current density distribution calculating means for obtaining a current density distribution in the X direction of the ion beam at the position of the substrate based on the stored current density distribution;
(C) Using the obtained current density distribution and the scan waveform of the substrate, and changing the combination of the scan number and the rotation number of the substrate in a plurality of combinations, for each combination, ions at a plurality of points on the substrate The beam irradiation density at the time of each combination of the number of scans and the number of rotations of the substrate is calculated by calculating the beam irradiation density and calculating the uniformity of the beam irradiation density on the substrate based on the irradiation density. Uniformity calculation means for outputting the uniformity of quantity density,
(D) After the uniformity of the beam irradiation density is output, an input for selecting a predetermined combination among a plurality of combinations of the scan number and the rotation number of the substrate is received, and the selected combination is stored. Combination storage means to
(E) drive control means for controlling the scanning mechanism and the rotation mechanism so that the combination of the number of scans and the number of rotations of the substrate stored in the combination storage means at the time of ion beam irradiation on the substrate; An ion beam irradiation apparatus characterized by comprising: A vacuum vessel that is evacuated to vacuum,
A holder that is housed in the vacuum vessel and holds a substrate;
A rotating mechanism for rotating the holder and a substrate held by the holder around a central portion of the substrate on which a plurality of columnar bodies are arranged; and
An ion source that has a plasma generation unit that generates plasma and an extraction electrode system that extracts an ion beam from the plasma by the action of an electric field, and irradiates the extracted ion beam onto a substrate held by the holder, In the extraction electrode system, a region where the ion beam is extracted and a region where the ion beam is not extracted are alternately arranged in the X direction at a predetermined period, and the region where the ion beam is extracted from the region where the ion beam is extracted An ion source for extracting an ion beam having a substantially uniform current density distribution in a range equal to or larger than the dimension of the substrate in a Y direction substantially orthogonal to the X direction;
A substrate tilting mechanism capable of tilting the holder and the substrate held by the holder so that a substrate tilting angle, which is an angle formed between the normal of the substrate and the traveling direction of the ion beam, is 0 degree or more;
A scanning mechanism for mechanically reciprocally scanning the holder, the substrate held thereon, the rotating mechanism, and the substrate tilting mechanism substantially in the X direction with a predetermined scanning waveform;
An ion beam irradiation apparatus comprising: a beam measuring device that measures a current density distribution of the ion beam in the X direction;
Using the substrate tilt mechanism, the substrate tilt angle is set to a predetermined angle excluding 0 degrees,
Based on the current density distribution measured by the beam measuring device, obtain a current density distribution in the X direction of the ion beam at the position of the substrate,
Using the obtained current density distribution, the scan waveform of the substrate and the predetermined substrate tilt angle, and changing the combination of the scan number and the rotation number of the substrate in a plurality of combinations, the plurality of circles for each combination Calculate the throughput by the ion beam for each side surface of each columnar body, and calculate the throughput uniformity for the side surfaces of the plurality of columnar bodies based on the throughput amount,
Based on the calculated throughput uniformity, determine a combination of the number of scans and the number of rotations of the substrate that provides the desired throughput uniformity;
An ion beam irradiation method comprising irradiating the substrate with an ion beam with a combination of the determined scan number and rotation number. A vacuum vessel that is evacuated to vacuum,
A holder that is housed in the vacuum vessel and holds a substrate;
A rotating mechanism for rotating the holder and a substrate held by the holder around a central portion of the substrate on which a plurality of columnar bodies are arranged; and
An ion source that has a plasma generation unit that generates plasma and an extraction electrode system that extracts an ion beam from the plasma by the action of an electric field, and irradiates the extracted ion beam onto a substrate held by the holder, In the extraction electrode system, a region where the ion beam is extracted and a region where the ion beam is not extracted are alternately arranged in the X direction at a predetermined period, and the region where the ion beam is extracted from the region where the ion beam is extracted An ion source for extracting an ion beam having a substantially uniform current density distribution in a range equal to or larger than the dimension of the substrate in a Y direction substantially orthogonal to the X direction;
A substrate tilting mechanism capable of tilting the holder and the substrate held by the holder so that a substrate tilting angle, which is an angle formed between the normal of the substrate and the traveling direction of the ion beam, is 0 degree or more;
A scanning mechanism for mechanically reciprocally scanning the holder, the substrate held thereon, the rotating mechanism, and the substrate tilting mechanism substantially in the X direction with a predetermined scanning waveform;
In an ion beam irradiation apparatus comprising current density distribution storage means for storing a current density distribution of the ion beam in the X direction and used for determining the number of scans and the number of rotations of the substrate,
Using the substrate tilt mechanism, the substrate tilt angle is set to a predetermined angle excluding 0 degrees,
Based on the stored current density distribution, a current density distribution in the X direction of the ion beam at the position of the substrate is obtained.
Using the obtained current density distribution, the scan waveform of the substrate and the predetermined substrate tilt angle, and changing the combination of the scan number and the rotation number of the substrate in a plurality of combinations, the plurality of circles for each combination Calculate the throughput by the ion beam for each side surface of each columnar body, and calculate the throughput uniformity for the side surfaces of the plurality of columnar bodies based on the throughput amount,
Based on the calculated throughput uniformity, determine a combination of the number of scans and the number of rotations of the substrate that provides the desired throughput uniformity;
An ion beam irradiation method comprising irradiating the substrate with an ion beam with a combination of the determined scan number and rotation number.   The ion source irradiates the substrate held by the holder with an ion beam having a dimension at a position of the substrate larger than a size including the substrate and a region where the substrate is scanned. 8. The ion beam irradiation method according to claim 1, 2, 3, 6, or 7. (A) a vacuum container that is evacuated to a vacuum;
(B) a holder that is housed in the vacuum vessel and holds the substrate;
(C) a rotating mechanism that rotates the holder and a substrate held by the holder around which a plurality of columnar bodies are arranged side by side around the center of the substrate;
(D) An ion source that has a plasma generation unit that generates plasma and an extraction electrode system that extracts an ion beam from the plasma by the action of an electric field, and that irradiates the extracted ion beam onto a substrate held by the holder. The extraction electrode system alternately arranges the region from which the ion beam is extracted and the region from which the ion beam is not extracted at a predetermined period in the X direction, and from the region from which the ion beam is extracted, An ion source for extracting an ion beam having a substantially uniform current density distribution in a range equal to or larger than the dimension of the substrate in the Y direction substantially perpendicular to the X direction at a position of
(E) a substrate tilting mechanism capable of tilting the holder and the substrate held by the holder so that a substrate tilting angle, which is an angle formed between a normal of the substrate and the traveling direction of the ion beam, is 0 ° or more;
(F) a scanning mechanism that mechanically reciprocally scans the holder, the substrate held by the substrate, the rotating mechanism, and the substrate tilting mechanism substantially in the X direction with a predetermined scanning waveform;
(G) a beam measuring device for measuring a current density distribution of the ion beam in the X direction;
(H) an ion beam irradiation apparatus comprising at least a control device having a function of controlling the rotation mechanism, the scanning mechanism, and the substrate tilting mechanism;
The control device includes:
(A) substrate tilt angle control means for controlling the substrate tilt mechanism to control the substrate tilt angle to a predetermined angle excluding 0 degrees;
(B) current density distribution calculating means for obtaining a current density distribution in the X direction of the ion beam at the position of the substrate based on the current density distribution measured by the beam measuring device;
(C) Using the obtained current density distribution, the scan waveform of the substrate and the predetermined substrate tilt angle, and changing the combination of the scan number and the rotation number of the substrate in a plurality of combinations, The processing amount by the ion beam for each side surface of each of the plurality of cylindrical bodies is calculated, and the processing amount uniformity for the side surfaces of the plurality of cylindrical bodies is calculated based on the processing amount, Uniformity calculation means for outputting the processing amount uniformity at each combination of scan number and rotation number;
(D) A combination memory that receives an input for selecting a predetermined combination among a plurality of combinations of the number of scans and the number of rotations of the substrate after the processing amount uniformity is output, and stores the selected combination Means,
(E) drive control means for controlling the scanning mechanism and the rotation mechanism so that the combination of the number of scans and the number of rotations of the substrate stored in the combination storage means at the time of ion beam irradiation on the substrate; An ion beam irradiation apparatus characterized by comprising: (A) a vacuum container that is evacuated to a vacuum;
(B) a holder that is housed in the vacuum vessel and holds the substrate;
(C) a rotating mechanism that rotates the holder and a substrate held by the holder around which a plurality of columnar bodies are arranged side by side around the center of the substrate;
(D) An ion source that has a plasma generation unit that generates plasma and an extraction electrode system that extracts an ion beam from the plasma by the action of an electric field, and that irradiates the extracted ion beam onto a substrate held by the holder. The extraction electrode system alternately arranges the region from which the ion beam is extracted and the region from which the ion beam is not extracted at a predetermined period in the X direction, and from the region from which the ion beam is extracted, An ion source for extracting an ion beam having a substantially uniform current density distribution in a range equal to or larger than the dimension of the substrate in the Y direction substantially perpendicular to the X direction at a position of
(E) a substrate tilting mechanism capable of tilting the holder and the substrate held by the holder so that a substrate tilting angle, which is an angle formed between a normal of the substrate and the traveling direction of the ion beam, is 0 ° or more;
(F) a scanning mechanism that mechanically reciprocally scans the holder, the substrate held by the substrate, the rotating mechanism, and the substrate tilting mechanism substantially in the X direction with a predetermined scanning waveform;
(G) an ion beam irradiation apparatus comprising at least a control device having a function of controlling the rotation mechanism, the scanning mechanism, and the substrate tilting mechanism;
The control device includes:
(A) substrate tilt angle control means for controlling the substrate tilt mechanism to control the substrate tilt angle to a predetermined angle excluding 0 degrees;
(B) a current density distribution storage means for storing a current density distribution of the ion beam in the X direction, which is used to determine the number of scans and the number of rotations of the substrate;
(C) current density distribution calculating means for obtaining a current density distribution in the X direction of the ion beam at the position of the substrate based on the stored current density distribution;
(D) using the obtained current density distribution, the scan waveform of the substrate and the predetermined substrate tilt angle, and changing the combination of the scan number and the rotation number of the substrate in a plurality of combinations, The processing amount by the ion beam for each side surface of each of the plurality of cylindrical bodies is calculated, and the processing amount uniformity for the side surfaces of the plurality of cylindrical bodies is calculated based on the processing amount, Uniformity calculation means for outputting the processing amount uniformity at each combination of scan number and rotation number;
(E) A combination memory that receives an input for selecting a predetermined combination of a plurality of combinations of the scan number and the rotation number of the substrate after the processing amount uniformity is output, and stores the selected combination Means,
(F) drive control means for controlling the scanning mechanism and the rotation mechanism so that the combination of the number of scans and the number of rotations of the substrate stored in the combination storage means at the time of ion beam irradiation on the substrate; An ion beam irradiation apparatus characterized by comprising: