JP2007258273A - Ion beam processing method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion beam processing method and an ion beam processing apparatus capable of reducing deformation on the surface of a material to be exposed in irradiating the material to be exposed with an ion beam. <P>SOLUTION: In processing a material W to be exposed having a processing area larger than an exposure area, an ion beam is relatively moved at a predetermined distance in one direction on a processing target portion, and/or ion beam is relatively moved at a predetermined distance in a direction different from the one direction on the processing target portion of the material to be exposed, and then, irradiation of the ion beam is executed for a predetermined time, and the ion beam is relatively moved so that the center of figure of a polygon using a plurality of centers of the irradiated ion beam as apexes can be included within a semi-diameter of the distribution of the number of ions of the ion beam. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ion beam processing method and apparatus for irradiating an exposed material with an ion beam to form a desired microstructure on the exposed material.

  2. Description of the Related Art In recent years, a process called LIGA (Lithographie, Galvanoforming and Abforming) has been used for the production of molds used in microfabrication apparatuses such as nanoimprints. The LIGA process has a feature that an aspect ratio (ratio of processing depth to processing width) can be increased (Non-Patent Documents 1 and 2).

  On the other hand, since the LIGA process uses a proximity X-ray mask to transfer a pattern to a resist layer (polymethyl methacrylate: PMMA), the proximity X-ray mask must be manufactured separately, and the cost for that must be estimated. There is a problem of not becoming. Further, the use of X-rays increases the equipment cost, and there is a problem that strict safety management is required during operation.

To solve these problems, a technique is disclosed in which a resist layer is directly exposed to a pattern by a light ion beam such as hydrogen ions, helium ions, or lithium ions without using a mask (Patent Document 1).
Internet, http://www.ritsumei.ac.jp/se/~sugiyama/research/re_5.1.html Internet, http://staff.aist.go.jp/k.awazu/Japanese-folder/nanoimprint1021.htm Special table 2001-50369 gazette

The method of exposing a pattern to a resist layer with a light ion beam has a large aspect ratio because there is less scattering inside the exposed material than the method of irradiating an electron beam, and a beam of heavy ions such as gallium is used. Compared to the method used, this method is superior in that the deep portion of the exposed material can be processed.
However, the irradiated ions not only cause changes in the cross-linking structure inside the exposed material, for example, PMMA, but also cause dissociation on the exposed material surface, resulting in surface deformation (dents corresponding to the dose distribution). ). As shown in FIG. 14, the surface deformation of the exposed material after ion beam irradiation (after exposure) has a shape that depends on the dose distribution, that is, the deformation is larger at the center of the beam axis and more deformed at the periphery of the beam axis. Is small. During ion beam irradiation, the surface gradually deforms and dents, and the ion penetration depth starts from the recessed surface, so the ion penetration depth gradually increases with the progress of the surface depression, and development with a developer Later, a recess similar to the surface is formed at the bottom of the processed portion. Therefore, for example, when a groove having a width larger than the diameter of the ion beam is processed into the exposed material W by scanning while irradiating the ion beam, a recess is formed at the bottom of the groove 81 as shown in FIG. A continuous streak pattern is generated, which is a factor that deteriorates the processing accuracy of the resist.

  The present invention has been made in view of the above-described problems, and provides an ion beam processing method and an ion beam processing apparatus capable of reducing surface deformation of a material to be exposed when the material to be exposed is irradiated with an ion beam. For the purpose.

In order to achieve the above object, the present invention takes the following technical means.
In other words, the ion beam processing method according to the present invention is a processing method for irradiating the material to be exposed having a processing area larger than the exposure area of the ion beam, with the ion beam being processed on the material to be exposed. Irradiation of the ion beam for a predetermined time after the relative movement in one direction in the portion and / or relative movement of the ion beam in a direction different from the one direction in the processing target portion of the exposed material The relative movement in the one direction of the ion beam and the relative movement in a direction different from the one direction were repeated alternately or individually in the portion to be processed, and each of the relative movements was irradiated. A polygonal centroid having a plurality of centers of the ion beam as vertices is within a half-value width of the ion number distribution of the ion beam. It performed as Murrell.

  Here, “relative movement in the one direction and relative movement in the direction different from the one direction... Alternately or individually and repeatedly” means relative to the one direction and the direction different from the one direction. In addition to repeating the movement alternately, the relative movement in the direction different from the one direction may be repeated one or more times after the relative movement in the one direction is repeated, and the relative movement in the one direction may be repeated again. It is meant to include.

In addition, “included within the half-width diameter” means that the distance between the centroid and the center of the ion beam is equal to or less than the distance between the half-width boundary in the direction connecting the center and the centroid in the ion beam and the center. It means that.
ADVANTAGE OF THE INVENTION According to this invention, the surface deformation | transformation of a to-be-exposed material can be reduced in the process which irradiates an ion to the to-be-exposed material with a process area larger than the exposure area of an ion beam.

Preferably, the irradiation of the ion beam is performed for a predetermined time determined based on a distribution of the number of ions of the ion beam and a dose necessary for processing the exposed material with respect to the same portion of the exposed material. .
By doing in this way, it can prevent that an ion beam is irradiated to the same part more than required time, and can reduce the surface deformation of a to-be-exposed material.

Irradiation of the ion beam can be performed in multiple times for the same portion of the material to be exposed until the predetermined time is reached.
Here, “performed in a plurality of times until a predetermined time is reached” means that it is performed a plurality of times until the total irradiation time of each time reaches a predetermined time.
An ion beam processing apparatus according to the present invention is an ion beam processing apparatus that processes an exposed material by irradiating an ion beam, and irradiating means that irradiates the same portion of the exposed material with the ion beam for a predetermined time. A first position changing means for repeatedly changing a relative position between the irradiation position of the ion beam and the material to be exposed in one direction on a surface orthogonal to the ion beam at a predetermined distance; and the ion beam Second position changing means for repeatedly changing the relative position between the irradiation position and the material to be exposed at a predetermined distance in a direction orthogonal to the one direction on a surface orthogonal to the ion beam. The irradiating means is configured to be able to irradiate the ion beam each time the relative position between the irradiation position of the ion beam and the material to be exposed is changed. The second position changing means may be either or any of such that a polygonal centroid having apexes at a plurality of centers of the irradiated ion beam is included within a half-value width diameter of the ion number distribution of the ion beam. It is configured to change the relative position between the irradiation position of the ion beam and the material to be exposed.

According to the present invention, for example, surface deformation of a material to be exposed can be reduced in processing of irradiating a material to be exposed having a processing area larger than the exposure area of the ion beam.
Preferably, the irradiation unit determines the irradiation of the ion beam based on a distribution of the number of ions of the ion beam and a dose necessary for processing the exposed material with respect to the same portion of the exposed material. It is configured to perform for a predetermined time.

In the present invention, it is possible to prevent the same part from being irradiated with an ion beam for more than a necessary time, and to reduce surface deformation of the exposed material.
The irradiation unit may be configured to perform irradiation of the ion beam for the predetermined time in a plurality of times.

  ADVANTAGE OF THE INVENTION According to this invention, the ion beam processing method and ion beam processing apparatus which can reduce the surface deformation | transformation of the to-be-exposed material at the time of ion beam irradiation can be provided.

FIG. 1 is a configuration diagram of an ion beam processing apparatus 1 according to the present invention, FIG. 2 is a diagram illustrating a configuration of an arithmetic unit 2, and FIG. 3 is a diagram illustrating a scanning state at the time of measurement by a current measuring probe 6.
In the following description, the vertical direction in FIG. 1 is referred to as the Z direction.
In FIG. 1, an ion beam processing apparatus 1 includes an ion beam irradiation apparatus 3, an ion beam controller 4, an exposed material support stage 5, a current measurement probe 6, a Faraday cup 7, a computing unit 2, a chamber 8, and a vacuum controller. 9 mag.

The ion beam irradiation apparatus 3 includes an ion source 10, an accelerator 11, a focusing device 12, and the like.
The ion source 10 generates proton ions by applying a voltage between a sharp metal tip and the surroundings in a hydrogen atmosphere. The ion source 10 is not limited to the above-described configuration itself, and various types such as an electron collision type, a high frequency discharge type, a duoplasmatron type, and a PIG type can be adopted.

The accelerator 11 includes a plurality of extraction electrodes 13 stacked, and accelerates ions generated in the ion source 10 by extracting them in a certain direction.
The focusing device 12 includes a magnifying lens 14, a deflector 15, and a focusing lens 16. The focusing device 12 is for energizing to form a predetermined electromagnetic field, focusing focused ions extracted from the ion source 10 and irradiating a predetermined position of the material W to be exposed. The magnifying lens 14 is formed of an electrostatic field generating plate or a magnetic field generating coil, and attracts proton ions passing through the center to expand in the radial direction. The deflector 15 is composed of two sets of parallel electrode plates that are shifted by 90 degrees from each other. By applying a DC voltage corresponding to a desired degree of beam deflection to each set of electrode plates, the axis of the ion beam is deflected. Move to deflect. The focusing lens 16 is formed of an electrostatic field generating plate or a magnetic field generating coil, and focuses proton ions passing through the central gap back to the beam center axis side.

The ion beam controller 4 adjusts the voltage applied to the focusing device 12 (magnifying lens 14, deflector 15, focusing lens 16) and controls the degree of focusing and irradiation position of the ion beam formed by the focusing device 12. To work.
The exposed material support stage 5 is for placing the exposed material W processed by the ion beam processing apparatus 1. The exposed material support stage 5 includes a small stage 17 on which the exposed material W is directly placed and a large stage 18 that supports the small stage 17. The small stage 17 freely moves in two orthogonal directions (hereinafter, these may be referred to as “X direction” and “Y direction”) on a plane orthogonal to the Z axis on the large stage 18 by a driving device (not shown). It is configured to be able to move in minute units. The large stage 18 is configured to be movable between a position where the material to be exposed W is exposed to the ion beam and a position where it is not exposed by a driving device (not shown).

  The current measuring probe 6 is for measuring the electric charge of ions forming the ion beam as a current value, and is arranged with the detection surface 19 facing the ion beam irradiation device 3 side. Further, as shown in FIG. 1, the current measuring probe 6 is arranged such that the detection surface 19 is substantially at the same position in the Z direction as the exposure surface of the material to be exposed W placed on the small stage 17. The current measuring probe 6 contacts the exposed material W or the exposed material support stage 5 when the large stage 18 is moved to the exposure position (right direction in FIG. 1) where the exposed material W is exposed to the ion beam. In order to prevent this, the entire current measurement probe 6 is configured to be movable to the retracted position (left direction in FIG. 1) by a driving device (not shown).

  Further, as shown in FIG. 3, the current measuring probe 6 can scan the irradiation range of the ion beam in two directions (X direction and Y direction) orthogonal to each other on a surface where the detection surface 19 is substantially orthogonal to the Z direction. It is configured. The scanning in these two directions is performed by a driving device including a piezo element (not shown) that is coupled to the current measurement probe 6 and expands and contracts in directions orthogonal to each other. The current measuring probe 6 measures the current value at regular intervals in the process of scanning in the X direction, and moves in the Y direction by a certain distance when scanning in the X direction is completed. Since the ion beam irradiation range is unknown before measurement, the current measurement probe 6 is configured to be able to scan a range larger than the predicted ion beam irradiation range.

In the current measuring probe 6, the front end edge in the scanning direction on the detection surface 19 has a knife edge shape as shown in FIG. 1, and the current measuring probe 6 prevents diffraction at the end of the ion beam detection portion to prevent current. Care is taken to increase the accuracy of the measurement. Hereinafter, one of the scanning directions is referred to as an X direction, and the other direction orthogonal to the X direction is referred to as a Y direction.
A signal line for transmitting the measurement result of the current measuring probe 6 is connected to the computing unit 2 described later.

  The Faraday cup 7 receives all the ions of the ion beam in a cross section orthogonal to the Z axis, and outputs a current corresponding to the number of ions. The Faraday cup 7 moves between a position where the driving device 20 receives an ion beam (hereinafter, sometimes referred to as “light receiving position”) and a position where the ion beam is not received (hereinafter, sometimes referred to as “retreat position”). It is configured to be possible. A known Faraday cup 7 is used.

  Further, the ion beam processing apparatus 1 measures the absolute position of the current measuring probe 6 in the X direction and the Y direction (a position uniquely determined in the ion beam processing apparatus 1, hereinafter simply referred to as “position”). A probe position measuring device 31 not shown in FIG. 1 and an exposed material position measuring device 32 not shown in FIG. 1 for measuring the positions of the small stage 17 on which the exposed material W is placed in the X direction and the Y direction are provided. Is provided. The exposed material position measuring device 32 and the probe position measuring device 31 are each provided with a known distance meter using, for example, laser interference, one in each of the X direction and the Y direction. The measurement of the position in the X direction of the material to be exposed W and the current measurement probe 6 may be performed with one measuring device, and the position in the Y direction may be measured with one measuring device.

The computing unit 2 includes a probe scanning unit 21, a probe position detection unit 22, a current detection unit 23, a Faraday cup management unit 24, a stage drive unit 25, a beam outline calculation unit 26, an exposed material position detection unit 27, an exposure unit 28, The storage unit 29 and the control unit 30 are included.
The probe scanning unit 21 controls the scanning of the current measurement probe 6, and also includes a position for measuring the charge of the ion beam for the current measurement probe 6 (hereinafter also referred to as “measurement position”) and a retracted position. Manage movement between.

The probe position detector 22 receives the position information of the current measurement probe 6 measured by the probe position measurement device 31 and calculates the position of the reference point of the current measurement probe 6. The reference point is set at the lower right end of the detection surface 19 in FIG.
Hereinafter, the positions in the X direction and the Y direction in the ion beam processing apparatus 1 are referred to as “X coordinate” and “Y coordinate”, respectively.

The current detection unit 23 takes in the current value measured by the current measurement probe 6 and digitizes it. The current detection unit 23 associates the current value with the X coordinate and the Y coordinate of the reference point of the current measurement probe 6 at the time of measurement, and the associated information is stored in the storage unit 29.
The Faraday cup management unit 24 controls the movement of the Faraday cup 7 between the position where the ion beam is received and the position where the ion beam is not received, receives the current value measured by the Faraday cup 7, and stores the current value in the storage unit 29. Remember me.

  The stage driving unit 25 controls a minute movement of the small stage 17 in the exposure process for processing the material to be exposed W, and a position at which the material to be exposed W is exposed to the ion beam with respect to the large stage 18 and a position at which the material is not exposed. To move between. The stage drive unit 25 manages the current measurement probe 6 and the material to be exposed W or the large stage 18 so as not to contact each other in cooperation with the probe scanning unit 21.

The beam outline calculator 26 calculates the center position of the ion beam on the irradiation surface, the range of the ion beam, and the current value (number of ions) from the current value measured by the current measuring probe 6 and associated with the X coordinate and the Y coordinate. Calculate the distribution.
The “irradiated surface” refers to the exposed portion of the surface of the material to be exposed W when the material to be exposed W is irradiated with the ion beam, and the “irradiated range” refers to the range of the irradiated surface. And

  The exposed material position detector 27 receives the position information of the exposed material W measured by the exposed material position measuring device 32 in the step of the ion beam processing apparatus 1 irradiating the exposed material W with the ion beam, and receives the exposed material. An X coordinate and a Y coordinate of a portion serving as a reference of the material W are calculated. Regarding the position of the material to be exposed W, since the positional relationship between the material to be exposed W and the small stage 17 is known, a specific position of the small stage 17 is actually measured. The calculated X coordinate and Y coordinate of the material to be exposed W are used for control by the exposure unit 28.

The exposure unit 28 drives the focusing device 12 and the small stage 17 according to the preset processing content of the material to be exposed W when the ion beam processing apparatus 1 performs processing by irradiating the material to be exposed W with the ion beam. Make the device work properly.
The storage unit 29 stores the current value associated with the X coordinate and the Y coordinate, the current value measured by the Faraday cup 7, the center position of the ion beam, the distribution of the current value (number of ions), and the processing content of the material W to be exposed. The operation conditions of the focusing device 12 according to the above are stored, and called in response to a request from the control unit 30.

The control unit 30 controls the operation of all the elements constituting the computing unit 2 described above. Further, the control unit 30 sets the position of the current measuring probe 6, the position of the material to be exposed W, the center position of the ion beam when the ion beam is irradiated on the material to be exposed on one X, Y coordinate axis. Arrange and manage these positions.
The computing unit 2 is realized by an external storage device such as a CPU (microcomputer), RAM, and hard disk, a control program, an interface having an A / D conversion function or a D / A conversion function, and the like.

  The chamber 8 is a pressure vessel that houses the ion beam irradiation device 3, the exposed material support stage 5, the current measurement probe 6, and the Faraday cup 7. A vacuum gauge 33 is attached to the chamber 8, and the vacuum is formed from the atmospheric pressure range by a vacuum device constituted by a rotary pump (not shown) for roughing and a turbo molecular pump (not shown) for vacuuming in the middle vacuum range. The internal pressure of the chamber 8 can be adjusted up to a range.

The vacuum controller 9 opens and closes the automatic valve 34 connected to the vacuum device or the automatic valve 35 for leaking based on the measurement value by the vacuum gauge 33, so that the chamber in the processing of the exposed material W by the ion beam is performed. Maintain the vacuum in 8 appropriately.
Next, how to obtain the dose distribution in the ion beam processing apparatus 1 will be described.
FIG. 4 is a flowchart showing a procedure for measuring the current value of the ion beam in the ion beam processing apparatus 1, and FIG. 5 is a diagram showing an example of a measurement result by the current measuring probe 6.

Before the measurement of the current value of the ion beam performed by scanning the current measurement probe 6, an operation check of the ion beam irradiation apparatus 3 is performed.
In the operation check, the probe scanning unit 21 moves the current measuring probe 6 to the retracted position (# 12), and the Faraday cup management unit 24 moves the Faraday cup 7 to the light receiving position (# 13). The ion beam controller 4 excites the ion source 10 and energizes the magnifying lens 14, the deflector 15, and the focusing lens 16 to form a predetermined electromagnetic field, and irradiates the focused ion beam toward the Faraday cup 7. (# 14). The Faraday cup management unit 24 determines whether or not the received current value is equal to or greater than a predetermined value (# 15). For example, the current density of the ion beam in consideration of the predicted irradiation area of the exposed material W surface is 10 μA / If cm ² or more cannot be obtained (No in # 15), it is determined that the ion beam is not focused, and the ion beam irradiation is stopped (# 17). In such a case, the ion beam irradiation device 3 is inspected or the control value of the focusing device 12 in the ion beam controller 4 is changed.

When the control unit 30 confirms that a predetermined current value is measured in the Faraday cup 7 (Yes in # 15), the Faraday cup management unit 24 starts from the Faraday cup 7 according to the number of irradiated ions. The measured current value is received and stored in the storage unit 29.
The Faraday cup management unit 24 moves the Faraday cup 7 to the retracted position, and the probe scanning unit 21 controls the driving device to move the current measurement probe 6 to the measurement position (# 16).

  The reference point of the current measurement probe 6 after moving to the measurement position is located at the scanning origin P ((X1, Y1) in FIG. 3). The scanning origin P is out of the ion beam irradiation range, and the current is detected on the detection surface 19 even when the current measuring probe 6 is scanned from the scanning origin P in the X direction and moved from the scanning origin P to the Y direction. It is preferable to set a position that is not performed. For example, the scanning origin P in FIG. 3 is selected at a position further to the left than the left end of the ion beam irradiation range and above the upper end of the ion beam irradiation range.

The position of the reference point of the current measuring probe 6 is measured by the probe position measuring device 31 every time the current value is measured.
The current measurement probe 6 measures the current value every time it is scanned at a constant interval in the X direction, for example, every time it moves a quarter of the length of the detection surface 19 in the X direction as shown in FIG. 18). When the measurement at the scanning end point (X = Xf) in the X direction is completed, the current measuring probe 6 moves by a predetermined distance (Y2-Y1) in the Y direction (# 20).

The current value measured by the current measuring probe 6 is stored in the storage unit 29 together with the X coordinate and Y coordinate of the reference point at the time of measurement. The scanning of the current measuring probe 6 in the X direction and the movement of a predetermined distance in the Y direction are repeatedly performed until the movement in the Y direction ends (Y = Yf) (# 19).
Based on the X coordinate, the Y coordinate, and the current value stored in the storage unit 29, the beam summary calculation unit 26 determines the center position and current value of the ion beam on the irradiation surface of the material W to be exposed. Distribution (hereinafter, sometimes referred to as “ion beam overview”) is calculated (# 21).

While the ion beam irradiation apparatus 3 is in operation, the vacuum controller 9 controls the automatic valve connected to the vacuum apparatus and the automatic valve for leakage, and the inside of the chamber 8 is in a vacuum state (for example, 1 × 10 ^-5 Pa or less).
Next, calculation of the outline of the ion beam on the irradiation surface of the material to be exposed W will be described.
FIG. 6 is a current value distribution of a band-like portion extending in the X direction having a width w2 on the ion beam irradiation surface.

In the following description, it may be referred to as “current value distribution” or “ion number distribution”, but the ion number is obtained by dividing the measured current value by the charge of one proton ion. Therefore, the above two expressions are appropriately selected according to the preceding and following descriptions without strictly distinguishing the two expressions.
Length w1 as shown in FIG. 3, in the measurement by the current measuring probe 6 having a detection surface 19 of the width w2, the current value A _m of the measurement position of the m-th in FIG. 6 (X _m, Y _n), represented by the area a _m of the X = X _m-3 to X = X _m.

A _m = a _m−3 + a _m−2 + a _m−1 + a _m (1)
Here, a _m−3 , a _m−2 , a _m−1 and a _m are portions corresponding to an area of a quarter of the detection surface 19 (hereinafter sometimes referred to as “minimum unit surface”). Represents the detected current value. The current value _Am-1 measured at the "m-1" th time is
A _m-1 = a _m-4 + a _m-3 + a _m-2 + a _m-1 (2)
In so expressed, the measurement position (X _m, Y _n) current value a _m detected by the front end side quarter of the detection surface 19 in,
a _m = A _m −A _m−1 + a _m−4 (3)
As required.

It should be noted that the current values a ₂ , a ₃ , and a _{4 on} the minimum unit surface from the first significant current value detected in the X direction scan of the current measuring probe 6 to the fourth time are
a ₂ = A ₂ −a ₁
a ₃ = A ₃ −A ₂
a ₄ = A ₄ −A ₃
Is required. From the current values a ₂ , a ₃ , a ₄ and the equation (4), the current value of the minimum unit surface at Y = Y _n is sequentially calculated.

The “significant current value” means not a noise but a current value at which it is determined that a current is clearly detected by the current measuring probe 6.
The current value a _m is obtained by the number of ions irradiated on the area (w1 × w2 ÷ 4) of the minimum unit surface centered on the coordinates (X _m −w1 ÷ 8, Y _n −w2 ÷ 2). since, the current value E _m per unit area in the coordinate _{(X m -w1 ÷ 8, Y} n -w2 ÷ 2),
E _m = a _m ÷ (w1 × w2 ÷ 4) (4)
It becomes.

Similarly, the current value E _m (1 ≦ m ≦ X _f) in the X direction when the Y coordinate is Y _n −w 2 ÷ 2 from the current values A ₁ ,..., A _f measured with the Y coordinate of the reference point as Y _n. ) Distribution, that is, the distribution of the number of ions.
Further, Y = Y _n -w2 left ion beam irradiation range of FIG. 3 in ÷ 2 extracts the X coordinate a _m becomes significant current values, the right of the ion beam irradiation range of 3, a _m Is obtained by extracting an X coordinate that is small enough to be ignored.

  The above processing is performed for the current value obtained by scanning in the X direction at each Y coordinate, the distribution of the current value E in the X direction at each Y coordinate is calculated, and the irradiation range of the ion beam is extracted at the same time. By such processing, the current value E in the ion beam irradiation range is obtained for each minimum unit surface, and a map of the current value E in the ion beam irradiation range, that is, the distribution of the number of irradiated ions is obtained. The distribution of the number of ions is stored in the storage unit 29 as the number of ions I (X, Y) per unit area centered on the X and Y coordinates.

At the center position of the ion beam, the distribution of the number of ions I (X, Y) is smoothed and interpolated to extract the X and Y coordinates of the smallest unit surface showing the largest number of ions I (X, Y). Is determined by The determined X and Y coordinates are stored in the storage unit 29.
According to the above method, the current value E for each minimum unit surface smaller than the detection surface 19 is obtained by making the measurement interval of the current value in scanning in the X direction smaller than the length w1 of the detection surface 19 in the scanning direction. Therefore, it is possible to obtain a highly accurate distribution of the number of ions I (X, Y). In order to improve the accuracy of the distribution of the number of ions I (X, Y), for example, the current value may be measured every one eighth of the length of the detection surface 19 in the X direction. By doing so, the number of minimum unit planes (w1 × w2 ÷ 8) in the ion beam irradiation range is subdivided twice, and a more accurate distribution of the number of ions I (X, Y) is obtained. Further, by making the amount of movement (# 20) of the current measuring probe 6 in the Y direction smaller, it is possible to obtain a more accurate distribution of the number of ions I (X, Y) in the Y direction.

Next, for reducing the surface deformation of the material to be exposed W when processing a groove having a width larger than the irradiation area of the ion beam, ions using the distribution of the number of ions I (X, Y) obtained above are used. A beam irradiation method will be described.
In this method, the processed portion of the material to be exposed W is stopped scanning at regular intervals and irradiated with an ion beam for a predetermined time, and the ion beam is applied so that a part of the ion beams irradiated to different portions overlap each other. By scanning, the surface deformation of the processed portion due to the dose distribution is averaged and reduced to reduce the degree of unevenness generated at the bottom of the groove after development.

FIG. 7 is a conceptual diagram of an array representing the number of ions I (X, Y) in the ion beam irradiation range. The number of ions I (X, Y) for an arbitrary position (X, Y) is obtained by smoothing and interpolation based on the array of FIG. 7 stored in the storage unit 29.
Incidentally, as shown in FIG. 14, in order to cause a chemical change in the material to be exposed W by irradiation with an ion beam so as to make it developable with a developer, a certain amount of dose is required. The dose amount refers to the number of ions per unit area implanted into the material to be exposed W, and is a value determined regardless of the intensity (density) of the ion beam.

FIG. 8 is a diagram showing the dose amount (FIG. 8B) when irradiation is performed so that two-thirds of the irradiation width of the ion beam overlap in the X direction (FIG. 8A). From FIG. 8, it is understood that the amount of irradiated beam is averaged by superimposing the ion beams.
When a groove having a width larger than the ion beam irradiation area is processed, for example, when exposure is performed so that two-thirds of the ion beam irradiation width overlaps in the X direction, the ion beam is usually moved in the Y direction. In order to average the surface deformation, it is preferable to perform exposure so that two-thirds of the irradiation width overlap.

Hereinafter, a method of obtaining the distribution of the number of ions Is (X, Y) irradiated to the material to be exposed W will be described by taking as an example a case where exposure is performed so that two-thirds of the irradiation width overlap.
FIG. 9 is a diagram showing a state of overlapping when exposure is performed so that two-thirds of the irradiation width overlap, and FIG. 10 is an ion beam (B11, B11, which is individually irradiated to the region ABCD (repeating unit) in FIG. ..., B33) is a diagram showing the configuration of the number of ions I (X, Y).

  As shown in FIG. 9, the region ABCD is subjected to nine ion beam irradiations (B11,..., B33). Since the processing target portion of the material to be exposed W is considered to be irradiated with the region ABCD as one unit, all the regions ABCD are irradiated with the number of ions that cause a change in the material to be exposed W. That is, the time and intensity of each ion beam irradiation (B11,..., B33) are set so that the required dose amount Dq is satisfied even in the portion where the number of ions is the smallest in the region ABCD.

  The distribution of the number of ions I (X, Y) in FIG. 7 is applied to the region ABCD in each of the ion beam irradiations B11 to B33 in FIG. 9, and the number of ions Is (Xi, Yj) in the superimposed region ABCD (where, Considering the distribution of Xi ≦ Xe ÷ 3, Yj ≦ Ye ÷ 3), the number of ions Is (Xi, Yj) at an arbitrary position (Xi, Yj) in the region ABCD is as follows for each irradiation B11 to B33. The total number of ions at the position.

Irradiation B11: Position (2 × Xe ÷ 3 + Xi, 2 × Ye ÷ 3 + Yj)
Irradiation B12: Position (2 × Xe ÷ 3 + Xi, Ye ÷ 3 + Yj)
Irradiation B13: Position (2 × Xe ÷ 3 + Xi, Yj)
Irradiation B21: Position (Xe ÷ 3 + Xi, 2 × Ye ÷ 3 + Yj)
Irradiation B22: Position (Xe ÷ 3 + Xi, Ye ÷ 3 + Yj)
Irradiation B23: Position (Xe ÷ 3 + Xi, Yj)
Irradiation B31: Position (Xi, 2 × Ye / 3 + Yj)
Irradiation B32: Position (Xi, Ye ÷ 3 + Yj)
Irradiation B33: Position (Xi, Yj)
The number of ions I (X, Y) at each position in the irradiations B11 to B33 is obtained from the storage unit 29 or obtained by interpolation from the number of ions I (X, Y) at a plurality of surrounding positions. FIG. 10 shows the number of ions I (X, Y) at each position in the irradiation ranges B11 to B33.

The beam outline calculation unit 26 obtains the total number Is (Xi, Yj) of the number of ions at each position (X, Y) for the region ABCD according to the equation (5), and determines the total number I _min of the smallest number of ions from among them. Extract.
Is (Xi, Yj) = I (2 × Xe ÷ 3 + Xi, 2 × Ye / 3 + Yj)
+ I (2 × Xe ÷ 3 + Xi, Ye ÷ 3 + Yj)
+ I (2 × Xe ÷ 3 + Xi, Yj)
+ I (Xe ÷ 3 + Xi, 2 × Ye ÷ 3 + Yj)
+ I (Xe ÷ 3 + Xi, Ye ÷ 3 + Yj)
+ I (Xe ÷ 3 + Xi, Yj)
+ I (Xi, 2 × Ye ÷ 3 + Yj)
+ I (Xi, Ye ÷ 3 + Yj)
+ I (Xi, Yj) (5)
Since the dose amount Dq (the number of ions per unit area, hereinafter sometimes referred to as “required dose amount Dq”) necessary for processing the material to be exposed W is determined by the type of the material to be exposed W, it is obtained. The time and intensity of ion beam irradiation (B11,..., B33) from the sum I _min of the smallest number of ions in the total number of ions Is (Xi, Yj) and the required dose Dp Can be requested. For example, the irradiation time T of the ion beam is
T = Dq ÷ I _min (6)
It becomes.

Further, the irradiation time T of each ion beam when the ion beam irradiation intensity is taken into consideration is the ion beam irradiation intensity when the ion beam irradiation intensity and the number of ions I (X, Y) actually used for processing are obtained. If the ratio to is R,
T = Dq ÷ I _min ÷ R (7)
Can be obtained.

  In the above example, the beam scan pitch (irradiation interval) Px (= Xe ÷ 3), Py (= Ye ÷ 3) in the X direction and Y direction of the ion beam is set to the width Dx (= Xe) of each direction of the ion beam. ), Dy (= Ye), but when the beam scan pitches Px and Py are different from the above example, for example, the beam scan pitches Px and Py are set in the respective directions of the ion beam. In the case where the widths Dx and Dy are 1/4, the ion beam irradiation time T and irradiation intensity can be set in the same manner as in the above example.

  FIG. 11 is a diagram showing a state of overlapping when exposure is performed so that three-quarters of the irradiation width of the ion beam overlap, and FIG. 12 is individually irradiated to the area ABCD (repetition unit) of FIG. FIG. As can be seen from a comparison between FIG. 11 and FIG. 12, as the number of overlaps increases, the number of arrays indicating the configuration of ions irradiated to the repeating unit increases, and the number of rows and columns, that is, the number of overlaps increases. For example, it is reflected in the denominator of the first term of the X coordinate and Y coordinate of B11 in FIG.

Since the processing of the material to be exposed is performed when the required dose amount Dq is satisfied, the same part is irradiated with the ion beam a plurality of times, and the total of each irradiation time processes the material to be exposed W. The dose amount Dq required for the above may be set.
The beam scan pitches Px and Py in the X direction and the Y direction of the ion beam are based on the half-value width that is often used as the effective diameter of the ion beam. It is preferable to set so that it may be covered with the irradiation surface.

  FIG. 13 is a diagram showing the superposition of ion beams based on the half width. In FIG. 13A in which the beam scan pitches Px and Py in the X direction and the Y direction are equal, the beam scan pitches Px and Py are squares in which the outer circumference of the half width of each ion beam is formed by the center of the ion beam. The repeating unit ABCD in the processing target portion of the material to be exposed W is covered with an irradiation surface having a half-value width as a diameter. In FIG. 13B, the beam scan pitches Px and Py ′ are set so that the outer peripheries of the half widths of the respective ion beams pass through the center of an equilateral triangle formed by the center of the ion beam. The repeating unit EFG in the portion to be processed of W is covered with an irradiation surface having a half-value width as a diameter.

By setting the beam scan pitches Px, Py, and Py ′ in this way, the processing target portion of the material to be exposed W can surely receive irradiation of a relatively large number of ions in the ion beam, Surface deformation of the exposed material, that is, unevenness of the processed groove is reduced and averaged.
In other ion beam superposition methods, similarly to FIG. 13, by setting the beam scan pitch so that the outer circumference of the half width passes through the polygonal centroid formed by the center of the ion beam, All of the processing target portion of the material to be exposed W is irradiated with ions within the half width, and the unevenness of the processing groove is reduced and averaged. By setting the beam scan pitch so that the half-width regions of each ion beam overlap, the unevenness of the processed groove is reduced and averaged.

  In the above-described embodiment, FIGS. 9, 11 and 13 show that the ion beam irradiation range is a perfect circle. Can do. When the irradiation range is an ellipse or an ellipse and the difference between the major axis and the minor axis is large, the number of overlaps of the ion beam in the X direction and the Y direction is made different so that the interval between the centers of the ion beams is set in the X direction and the Y direction. You may adjust so that it is not greatly different.

  Even when the number of times of overlap of ion beams in the X direction and the Y direction or in the direction inclined by a certain angle from the X direction is made different, the repetition unit (area ABCD, area EFG) shown in FIGS. 10, 12 and 13 is irradiated. If the number of constituents of the rows and columns of the array for obtaining the number of ions to be used is the number of overlaps, the ion beam irradiation time and intensity can be set by the above method.

In the above-described method, irradiation is performed with a certain distance interval in the X direction and the Y direction so that the center of the ion beam becomes a rectangular vertex, or the X direction and the X direction so that the center of the ion beam becomes a rectangular vertex. Irradiation is performed with a certain distance interval in a direction inclined by a certain angle from the direction, but the center of the ion beam may be a vertex of a polygon that is a pentagon or more.
In order to increase the accuracy of the distribution of the number of ions I (X, Y), the number of ions I (X, Y) in the ion beam irradiation range is integrated, and the number of ions corresponding to the current value measured by the Faraday cup 7 The number of ions I (X, Y) may be corrected based on the obtained ratio.

  The ion beam irradiation device 3, the ion beam controller 4, the exposed material support stage 5, the current measurement probe 6, the Faraday cup 7, the arithmetic unit 2, the chamber 8, the vacuum controller 9 and the like should be used in various ways. Can do. In addition, each structure of the ion beam processing apparatus 1 and the ion beam processing apparatus 1 or the overall structure, shape, dimensions, number, material, and the like can be appropriately changed in accordance with the spirit of the present invention.

  INDUSTRIAL APPLICABILITY The present invention can be used in industries that irradiate an exposed material with an ion beam to form a desired microstructure on the exposed material.

It is a block diagram of the ion beam processing apparatus which concerns on this invention. It is a figure which shows the structure of a calculating unit. It is a figure which shows the mode of the scanning at the time of the measurement of an electric current measurement probe. It is a flowchart which shows the procedure of the current value measurement of the ion beam in an ion beam processing apparatus. It is a figure which shows the example of the measurement result by an electric current measurement probe. It is a figure which shows distribution of the electric current value of the strip | belt-shaped part of the width | variety in an ion beam irradiation surface. It is a conceptual diagram of the arrangement | sequence showing the number of ions in the irradiation range of an ion beam. It is a figure which shows the dose amount when it irradiates so that 2/3 of the irradiation width of an ion beam may overlap. It is a figure which shows the mode of duplication when it exposes so that 2/3 of irradiation width may overlap. It is a figure which shows the structure of the number of ions irradiated individually to area | region ABCD of FIG. It is a figure which shows the mode of duplication when it exposes so that 3/4 of the irradiation width of an ion beam may overlap. It is a figure which shows the structure of the number of ions irradiated separately to area | region ABCD of FIG. It is a figure which shows the superimposition of the ion beam on the basis of a half value width. It is a figure which shows the deformation | transformation of the to-be-exposed material by ion beam irradiation. It is a perspective view of the streaky pattern which arises in the bottom of a processing groove.

Explanation of symbols

1 Ion beam processing device 3 Irradiation means (ion beam irradiation device)
Dq Required dose (required dose)
I (X, Y) Number of ions T Predetermined time (irradiation time)
W Material to be exposed

Claims (6)

A processing method of irradiating the material to be exposed having a processing area larger than the exposure area of the ion beam with the ion beam,
Relative movement of the ion beam by a predetermined distance in one direction in the processing target portion of the exposed material and / or relative movement of the ion beam in a direction different from the one direction in the processing target portion of the exposed material The ion beam is irradiated for a predetermined time after
Performing the relative movement in the one direction of the ion beam and the relative movement in a direction different from the one direction alternately or individually in the processing target portion,
Any of the relative movements is performed such that a polygonal centroid having a plurality of centers of the irradiated ion beam as vertices is included within a half-value width of the ion number distribution of the ion beam. Ion beam processing method. Irradiation of the ion beam,
The ion beam processing method according to claim 1, wherein the ion beam processing method is performed for a predetermined time determined based on a distribution of the number of ions of the ion beam and a dose necessary for processing the material to be exposed on the same portion of the material to be exposed. Irradiation of the ion beam,
The ion beam processing method according to claim 1, wherein the ion beam machining method is performed in a plurality of times until the predetermined time is reached for the same portion of the material to be exposed. An ion beam processing apparatus that processes an exposed material by irradiating an ion beam,
Irradiation means for irradiating the same portion of the exposed material with the ion beam for a predetermined time;
First position changing means for repeatedly changing the relative position between the irradiation position of the ion beam and the material to be exposed in one direction on a surface orthogonal to the ion beam at predetermined distances;
Second position changing means for repeatedly changing a relative position between the irradiation position of the ion beam and the material to be exposed at a predetermined distance in a direction orthogonal to the one direction on a surface orthogonal to the ion beam; Have
The irradiation means is configured to be capable of irradiating the ion beam every time the relative position between the irradiation position of the ion beam and the exposed material is changed,
The first position changing means and the second position changing means are:
Either or both of the irradiation positions of the ion beam are such that polygonal centroids having apexes at the plurality of centers of the irradiated ion beam are included within the half-value width of the ion number distribution of the ion beam. The ion beam processing apparatus is configured to change a relative position between the exposure object and the exposed material. The irradiation means includes
The ion beam irradiation is performed for a predetermined time determined based on a distribution of the number of ions of the ion beam and a dose required for processing the exposed material with respect to the same portion of the exposed material. The ion beam processing apparatus according to claim 4. The irradiation means includes
The ion beam processing apparatus according to claim 4, wherein the ion beam irradiation is performed in a plurality of times.

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