JP4951201B2 - Beam irradiation method and beam irradiation apparatus - Google Patents

Description

  The present invention relates to a method and apparatus for uniformly irradiating an irradiation object with a beam (particle beam) of light, electrons, ions, or the like.

As a method for uniformly irradiating the irradiated object with particles such as electrons and ions, the irradiated object is mounted on a rotating disk, and the rotating disk is rotated at a constant speed so that the irradiated object There is a method of scanning across a beam of ions. In this method, the entire rotating disk is generally reciprocated in the radial direction of the rotating disk so that the entire irradiated object is irradiated with the beam. A typical example of using this technique is an ion implantation apparatus for implanting ions into a silicon wafer in a semiconductor manufacturing process. The following description will be made by taking this ion implantation apparatus for a silicon wafer as an example.
FIG. 2A shows a state of ion implantation into the wafer 3 by this method.

As shown in FIG. 2A, the scanning direction due to the rotation of the rotating disk 1 and the scanning direction due to the reciprocating motion of the rotating disk 1 have directions substantially orthogonal to each other. Ions are uniformly implanted over the entire surface. In general, rotation is much faster in scanning speed, so it is called fast scan. One reciprocating scan is called slow scan because of its slow speed.
When the rotating disk 1 is rotated for fast scanning, as shown in FIG. 15, conventionally, the wafer 3 ′ mounted on the disk 1 ′ rotates with the disk 1 ′ when viewed from the outside and changes its posture. In addition, the code | symbol 3a in FIG. 15 is the notch previously formed in wafer 3 '. If attention is paid to the direction of the notch 3a, it can be seen that the wafer 3 'rotates together with the disk 1' to change its posture.

In the case of ion implantation into a silicon wafer, from which direction to implant the silicon crystal lattice, or from which direction to implant the semiconductor device shape formed on the wafer, Incident direction becomes a problem. In general, two angles are used as quantities representing the incident direction.
One is the angle (tilt angle) of how much the incident ion beam is tilted from the normal of the wafer. The other is the angle (twist angle) that indicates which direction the wafer is tilted, which is the line formed by projecting the ion beam incident vector onto the wafer and the reference direction line. Defined by angle. An example of this definition is shown in FIG. 2 (particularly (b) and (c)). When the tilt angle is 0 degree, this means that ions are incident on the wafer perpendicularly from the normal direction, and the direction is not fixed even if the incident vector is projected onto the wafer, so the twist angle is not defined. .

  When the wafer 3 is loaded on the rotating disk 1 and ion implantation is performed as shown in FIG. 2A, the tilt angle is adjusted by tilting the entire rotating disk 1 with respect to the ion beam 5. The twist angle is adjusted by changing the angle of loading to the pedestal 2 (wafer loading holder) on the rotating disk 1.

The above-described ion implantation is described in, for example, the following Patent Document 1 (particularly FIG. 3 and the explanation thereof in the document).
JP 2000-111942 A

  When ion implantation is performed using a rotating disk as described above, improvements regarding the following points are desired.

First, the tilt angle and twist angle described above are not constant over the entire wafer surface, and a deviation occurs in each angle.
In general, a rotating disk is formed such that a pedestal having a wafer holding material on the surface is inclined slightly inward toward the central rotation axis. The inclination of this pedestal is called the cone angle. This cone angle creates a component force in the direction of pressing the wafer against the pedestal from the centrifugal force during disk rotation, making it easier to hold the wafer by crimping and improving the thermal contact state between the wafer and the rotating disk and improving the cooling capacity. improves. However, because of this cone angle, while the wafer crosses the ion beam, the attitude of the wafer changes so as to be twisted, and a deviation occurs in which the implantation angle changes depending on the location within the wafer. The amount of this implantation angle deviation varies depending on the radius of the wafer loading position on the rotating disk, the cone angle, the set tilt angle, the wafer size, and the like.
In particular, a problem when the disk is largely tilted with respect to the beam axis is a twist deviation rather than a tilt deviation. The tilt deviation is not so large. For example, if the cone angle is 0 degree, the tilt angle deviation is always zero. However, the twist deviation increases as the tilt angle increases. This is unavoidable even if the cone angle is 0 degree, as the direction of the wafer changes with the rotation of the tilted disk.
Recently, since semiconductor devices have been miniaturized, a slight implantation angle deviation may affect device characteristics, and more accurate implantation is required for the ion implantation process. Any tilt angle setting value requires that the deviation within the wafer surface be as small as possible for both the tilt angle and the twist angle.

The second point to be improved is that the slow scan is scanned while changing the speed so that it is inversely proportional to the radial distance (R) where the beam hits the rotating disk.
In general, since the rotating disk rotates at a constant speed (constant angular velocity), the scanning speed of the fast scan is proportional to the radial distance (R) where the beam hits the rotating disk when viewed from the center of the rotating disk. Get faster. For this reason, if the slow scan is simply performed at a constant speed, the ion implantation density (concentration) is reduced at a portion where the fast scanning speed is high, and the implantation density is increased at a slow portion. In order to compensate for this, the slow scan is delayed when the fast scan is fast (that is, R is large), and conversely, the slow scan is accelerated when the fast scan is slow (R is small). The injection amount (dose) is made uniform.
The slow scan method in inverse proportion to R is called “1 / R scan” and is used in all batch processing type ion implanters using a rotating disk. Since the 1 / R scan is performed, the beam position in the R direction must be measured each time, and there is a possibility that the repetition accuracy of the implantation dose will be reduced due to the measurement error.

  Note that the above-described problems are not limited to the case where ions are implanted into a wafer, but commonly occur when a beam is irradiated onto an object to be irradiated on a rotating body.

The beam irradiation method of the invention is
A beam (light) is irradiated on the plane portion of the irradiated object at a specific irradiation position (that is, part or all of the moving path) while moving the planar irradiated object (for example, the silicon wafer) on the circular orbit. Or a particle beam of electrons, ions, etc.)
-During the irradiation (between each irradiation when irradiating at multiple locations), the absolute posture of the irradiated object (ie, the posture viewed from the outside. The posture in the absolute coordinate system, not the posture with respect to the rotating disk, etc. The posture with respect to the beam (For example, the straight line connecting any two points on the irradiated object is translated)
It is characterized by that.

The purpose of beam irradiation here and the type of beam are not limited. For example, as described above, it is conceivable to irradiate an ion beam to inject ions into a semiconductor wafer, or to irradiate light to various articles for inspection or processing. It is assumed that the position of the beam is unchanged.
The method for keeping the absolute posture of the irradiated object constant is not limited. It is possible to maintain the posture by giving an appropriate amount of displacement to the irradiated object (for example, as in the following method), and using a gyro-type multi-stage multi-axis turning mechanism etc. It is also possible to maintain the posture in that way without any manipulation or displacement.

Since the absolute posture of the irradiated object is kept constant while the beam is irradiated, according to the method of the present invention , the beam irradiation is performed on the entire surface of the irradiated object from a uniform angle. Therefore, for example, even when ion implantation is performed as described above, there is no deviation in the tilt angle or twist angle. The movement of the irradiated object described above may be a movement or a linear movement along an arbitrary curve including a circular motion and a reciprocating arc motion having a continuous constant trajectory. Even if the movement of the irradiation object is arbitrary, the irradiation of the beam from a uniform angle is realized as long as the absolute posture of the irradiation object at the irradiation position is kept constant.
Further, according to the method of the present invention , as long as the irradiated beam is uniform, the irradiation density (concentration) distribution according to the distance from the center of curvature of the moving path is on the irradiated object irradiated and moved. There is also an advantage that does not occur. That is, the problem that the irradiation density is reduced in proportion to the specific distance (R) as in the above example does not occur.

Beam irradiation method of the invention is, in particular,
・ By rotating (revolving) the irradiated object around a center line that does not pass over the irradiated object, the irradiated object is rotated (rotated) in a fixed cycle in the opposite direction to the rotation. Keep the absolute attitude of
Good . Each rotation described above is not limited to continuous rotation in one direction, and may be reciprocal rotation within a specific angle range.

  If the irradiated object is rotated (revolved and rotated) in this way, it is easy to keep the absolute posture constant as described above. For example, as shown in FIG. 1C, when the wafer 3 (object to be irradiated) on the rotating disk 1 (rotating body) rotates (revolves) with the rotating disk 1 in the direction of arrow A, an arrow cancels the rotation. If the wafer 3 is rotated (rotated) at the direction and speed of B, the change in the absolute posture of the wafer 3 can be eliminated. That is, in the above example, the twist deviation can be prevented from occurring. In FIG. 1C, reference numeral 3a denotes a notch formed in the wafer 3 (the same applies to other drawings).

The beam irradiation method of the invention further includes:
The object to be irradiated in a direction intersecting the center line (preferably a direction perpendicular to or close to the movement direction / irradiation direction), which is different from the irradiation direction of the beam and the moving direction of the irradiation object at the center of the irradiation position. Is moved linearly (including reciprocal linear movement)
・ Perform the linear movement based on a constant speed.
Good .
The irradiation direction of the beam refers to the direction of the beam 5 in the example of FIG. 2, for example, and the moving direction of the irradiation object at the center of the irradiation position refers to the direction along the α axis in FIG. Direction). Further, the above-mentioned “linear movement” of the irradiated object corresponds to, for example, the slow scan described above.

In this method, the linear movement of the irradiated object corresponding to the slow scan or the like is performed at a constant speed without changing the speed at a specific rate as in the “1 / R scan”. Therefore, the control regarding the said linear movement is simplified and a required installation cost is also reduced. Since the absolute posture of the irradiated object is kept constant during the irradiation of the beam, the irradiation density distribution on the irradiated object corresponding to the radius of rotation does not occur even if the speed change such as 1 / R scan is not performed.
Note that this method is advantageous for uniformly irradiating the entire surface of the irradiation object because the irradiation object is irradiated with the beam by a combination of two scans. When the irradiation cross section of the beam is smaller than the surface of the irradiated object, it is particularly meaningful to move the irradiated object linearly.

The beam irradiation method of the invention further includes:
During the irradiation, the moving speed of the irradiated object in the direction along the moving direction of the irradiated object at the center of the irradiation position (the direction of the fast scan described above) (in the example of FIG. 2, in the circumferential direction) The speed component in the direction of the fast scan (not the speed)
Good .

As described above, when the irradiated object is moved while keeping the absolute posture constant and no other operation is performed, it is inevitable that non-uniform irradiation occurs on the irradiated object. For example, as shown in FIG. 4, consider a case where a wafer 3 (object to be irradiated) on a rotating disk 1 (rotating body) is irradiated with a beam while keeping the absolute posture while moving by the rotation of the rotating disk 1. In each of FIGS. 4A and 4B, the direction of movement (fast scan) of the wafer 3 at the center of the irradiation position is horizontal (the left-right direction in the figure), and the direction of linear movement (slow scan) is the same. It is shown vertically (up and down in the figure).
According to FIG. 4A, the wafer 3 traverses the beam as the rotating disk 1 rotates without changing the direction (phase). Assuming that the wafer 3 is mounted on the rotating disk 1 at the radius R, the wafer 3 crosses the beam along the locus A of the radius R while keeping the absolute posture constant. Since the beam itself does not move, the trajectory of the beam left on the wafer 3 becomes an arc trajectory A ′ having a radius R in the reverse direction. If the speed of the slow scan is constant, beam trajectories A ′ having the same radius R are arranged at regular intervals in the slow scan direction.
However, when the wafer 3 is rotated on the disk 1 while keeping the absolute posture constant, the speed of the wafer 3 increases or decreases depending on the position on the disk 1. As shown in FIG.
v ₀ = v ₁ −v ₃ = v ₂ + v ₃
However, the velocity in the moving direction is always constant at any point on the wafer 3 at one point. However, at another point, for example, when moving from point a to point b in FIG. 4 (a), all speeds change,
v ₀ '<v ₀
It is.
In such a scan, non-uniformity of injection occurs such that irradiation (injection) is intense at both ends in the horizontal direction. The cause seems to be the close spacing of the trajectories on both sides, but it is not. When viewed along the slow scan direction, the trajectory interval is constant. The cause is that the velocity component in the direction perpendicular to the slow scan direction (in this case, the horizontal velocity component) is not constant.
FIG. 5 shows the reason. Since the beam scanning speed (V) is constant in the direction along the arc of the locus A ′ in FIG. 5A (V = Rω), the horizontal speed component V _H is the same as that in FIG. V _H = V becomes centered at the maximum so, will be reduced by the V _H = Vcosθ = Rωcosθ the position where the angle theta. For this reason, the area to be implanted at the same time with the same beam width decreases in proportion to cos θ, and the implantation dose is inversely proportional to 1 / cos θ, resulting in implantation non-uniformity that is densely implanted at both ends. . In the case of FIG. 5B, since the area to be implanted in a certain time is S1>S2> S3, the S3 region is more densely implanted than the S1 region.

In the irradiation method described above, during irradiation, there is a change in the movement speed (in this case, speed V _H ) of the irradiation object in the movement direction of the irradiation object in the center of the irradiation position (the direction of the fast scan). (In the above case, the speed is V _H = V cos θ
The operation is applied to the position or speed of the irradiated object so that the degree of change becomes smaller than the change in (or the change becomes zero). If the change in the velocity V _H can be reduced or V _H can be made constant, the area theorem of the parallelogram is close to S1 = S2 = S3 as shown in FIG. A uniform dose (irradiation density) can be obtained even if the trajectory interval looks close. Note that if the distribution of the velocity V _H during irradiation is less than 0.1%, the distribution of irradiation density is less than + 1.0%, which is extremely advantageous in terms of ion implantation for a semiconductor wafer.

Beam irradiation method of the invention, using the above method, in particular,
・ Ion beam is irradiated to the semiconductor wafer that is the object to be irradiated.
Good .

Regarding ion implantation into semiconductor wafers, as described above, slight deviations in the implantation angle may affect device characteristics. Therefore, the tilt angle and twist angle both vary within the wafer surface regardless of the tilt angle setting value. It needs to be as small as possible. Needless to say, it is desirable that the dose on the wafer surface be uniform. Therefore, it can be said that the method of the present invention can provide extremely useful irradiation with high industrial value.

The beam irradiation apparatus of the invention is
・ Attach a holder to hold the object to be irradiated at a place other than the center of rotation in the rotating body (refers to a rotating object, which can be of any shape;
Irradiation means for irradiating the irradiated object with a beam at a specific irradiation position (that is, part or all of the path) of the irradiation object on the holder rotating (turning) with the rotation of the rotating body Provided,
-A means for keeping the absolute posture of the irradiated object constant during the irradiation at the irradiation position is attached to the rotating body or the holder. Needless to say, the purpose and type of beam irradiation are not limited, and the means for keeping the absolute posture of the irradiated object constant is not limited to the above.

According to this irradiation apparatus, the irradiation method of the invention can be carried out smoothly. This is because when the object to be irradiated is held on the holder and the beam is irradiated by the irradiation means while rotating the rotating body, the irradiation of the beam and the movement of the object to be irradiated can be performed as described above . Since the means for keeping the absolute posture of the irradiated object constant is attached to the rotating body or the holder, the absolute posture of the irradiated object does not change during irradiation.
Therefore, as described above, the entire surface of the irradiated object is irradiated with the beam from a uniform angle. For example, even when ion implantation is performed on a semiconductor wafer to be irradiated, deviations in tilt angle and twist angle are generated. There is no. In addition, as long as the irradiated beam is uniform, the irradiation density distribution according to the distance from the center of curvature of the moving path does not occur on the irradiated object that is irradiated and moved.
This device also has a feature that the configuration is simple. This is because the movement of the irradiated object for scanning in a specific direction (fast scan in the above example) is realized by a simple configuration in which a holder for holding the irradiated object is mounted on the rotating body.

The beam irradiation apparatus of the invention
・ As a means to keep the absolute posture of the irradiated object constant, a rotating drive source for the holder to rotate the holder separately from the rotating body (when rotating with the rotating body is referred to as “rotation”) (Motor etc.) is provided, and control means is provided to make the rotational speeds of both (the rotating body and the holder) the same angular speed in the opposite direction.
It ’s good to have something .

According to this irradiation apparatus, the irradiation method of the invention can be carried out and the merit obtained thereby can be enjoyed. The holder is held to the irradiated object, in the same magnitude in the opposite direction rotates (spins) of the rotation of the rotating body (revolving) by said control means, the absolute posture of said following irradiation object constant Because it can keep.

Irradiation system invention,
・ As the above means to keep the absolute posture of the irradiated object constant, power transmission means is provided to connect the rotating body and the holder so that the holder rotates at the same angular velocity opposite to the rotating body as the rotating body rotates. The
It ’s good to have something .

With this irradiation device, it is possible to carry out the irradiation method of the invention. When rotating together with the rotating body holder was holding the irradiated object (revolution), a result of the holder is rotated at a speed of the same magnitude of the rotational direction opposite of the rotating body by the action of the power transmission means described above, as the This is because the absolute posture of the irradiated object can be kept constant.

The beam irradiation apparatus of the invention
・ A sun gear (including not only gears but also sprockets or timing pulleys) is provided on the rotation center line of the rotating body to fix the rotation, and planetary gears (also gears) with the same number of teeth as the sun gear. In addition to sprockets or timing pulleys, etc. are provided on the rotating body and connected to the sun gear (this connection involves meshing the gears between the sun gear and the planetary gear, or a chain or timing belt) To realize a differential gear mechanism or a differential winding transmission mechanism, which is used as the above power transmission means,
・ The above holder is mounted integrally with the rotating shaft of the planetary gear (that is, the holder rotates together with the planetary gear).
It ’s good to have something . “Differential gear mechanism” refers to a mechanism in which the centers of a plurality of meshed gears are connected by a rotatable link (arm) or the like. Further, the “differential winding transmission mechanism” is a mechanism in which a plurality of vehicles around which belts or chains are wound are similarly connected by links or the like instead of the gears of the differential gear mechanism.
An example of the main part of this apparatus is as shown in FIGS. 1 (a) and 1 (b). A differential winding transmission mechanism 20 is configured by connecting a fixed pulley 21 that is a sun gear and a pulley 22 on the pedestal 2 (holder) side that is a planetary gear with a uniform number of teeth by a timing belt 23. . And the pedestal 2 is attached integrally with the axis | shaft 12 of the pulley 22 which is a planetary gear.

In this apparatus, when the pedestal 2 (holder) is rotated (revolved) together with the rotating disk 1 (rotating body), the rotating disk is driven by the action of the differential winding transmission mechanism (or differential gear mechanism) 20 serving as power transmission means. The pedestal 2 rotates at the same speed opposite to the rotation of 1. Therefore, the wafer 3 that is the object to be irradiated can be moved while keeping the absolute posture constant as described above (that is, as shown in FIG. 1C).
There is no need for a drive source (motor, etc.) or control equipment for rotating (spinning) the holder, and the rotation is always in the proper direction and speed, and the main part can be configured with general-purpose simple parts. The device has the following advantages.

The beam irradiation apparatus of the invention further includes
・ In order to change the absolute posture of the irradiated object during the above irradiation, a holder setting posture changing means was provided.
It ’s good to have something .

  During the irradiation, the absolute posture of the irradiated object (and hence the holder) is kept constant as described above. In this apparatus, the absolute posture kept constant is appropriately changed by the setting posture changing means (that is, another position is changed). A certain posture). If the absolute posture of the irradiation object can be appropriately changed in this way, the direction of the irradiation object with respect to the irradiation direction of the beam can be easily changed. This is because it is not necessary to remove the irradiated object from the holder, change the direction and hold it again on the holder.

The beam irradiation apparatus of the invention
・ The phase (ie angle) of the sun gear that fixes rotation can be changed to change the absolute posture of the irradiated object during the irradiation.
It ’s good to have something . That is, in this apparatus, as the setting posture changing means of the holder, the phase of the sun gear in the differential gear mechanism (or the differential winding transmission mechanism) (in the example of FIGS. 1A and 1B, the fixed pulley 21 it is to allow changing the angle).

  With such an apparatus, the above-described change in the absolute posture of the irradiated object can be easily performed with a simple structure. This is because the absolute posture of the holder can be changed around the center of rotation of the holder simply by changing the angle of the sun gear that is fixed. When a plurality of planetary gears are connected to a common sun gear and a holder is attached to the rotation shaft of each planetary gear, only the angle of the sun gear is changed as described above, and FIG. As in (b), the effect that the absolute postures of all pedestals 2 (holders) and wafers 3 (objects to be irradiated) can be changed at the same time also occurs. Since the fixed pulley 21 (sun gear) is on the line of the rotation center of the rotating body 1 (on the support shaft 11) and does not change its position while the rotating body 1 is rotating, the fixed pulley 21 (sun gear) can be used while the pedestal 2 is rotating. The phase of the pedestal 2 and the wafer 3 can be changed at any time.

The beam irradiation apparatus of the invention further includes
A constant reference speed of the rotating body in a direction different from the irradiation direction of the beam and the movement direction of the irradiation object at the center of the irradiation position (preferably in the direction perpendicular to or near the movement direction / irradiation direction). In addition to linear movement (including reciprocal linear movement),
・ Measure the beam dose with the measuring means,
・ Change the speed of the linear movement from the reference speed according to the measured beam dose.
It ’s good to have something .
As described above, the irradiation direction of the beam refers to the direction of the beam 5 in the example of FIG. 2, for example, and the moving direction of the irradiated object at the center of the irradiation position is along the α axis 6 in FIG. The direction (the direction of the fast scan described above). The above-mentioned “linear movement” of the irradiated object corresponds to, for example, the slow scan described above.

In this apparatus, the linear movement of the irradiated object corresponding to the slow scan or the like can be performed based on the constant speed movement at a constant reference speed (for this reason, the control related to the linear movement is simplified and necessary) Equipment costs are also reduced). However, since the irradiation amount of the beam is measured as described above and the speed of the linear movement is changed in accordance with the irradiation amount, there is an effect that the accuracy of the irradiation amount uniformity is increased. This is because when there is a change in the irradiation amount of the beam, the change is known by the above-mentioned measuring means, and the speed of linear movement (slow scan) can be changed in order to make the irradiation amount uniform according to the change in the irradiation amount.
In addition, since the irradiated object is irradiated with the beam by a combination of the two scans, this apparatus is advantageous for uniformly irradiating the entire surface of the irradiated object. It is also clear that it is significant when it is small compared to the surface.

The beam irradiation apparatus of the invention further includes
-The angle of the rotating body with respect to the beam irradiation direction (and therefore the angle formed by the surface including the circumferential trajectory and the beam irradiation direction) can be changed.
It ’s good to have something .

  When the angle of the rotating body is changed by this apparatus, the angle of the holder with respect to the beam irradiation direction can be changed, and therefore the angle of the irradiated object with respect to the beam irradiation direction can be changed. Therefore, even when devices / parts such as a drive source are connected to the holder, the absolute posture (such as the tilt angle) of the holder and the irradiated object can be easily changed. In the case where a plurality of holders are provided on one rotating body, there is also an advantage that the absolute postures of all holders and irradiated objects can be changed simultaneously.

The beam irradiation apparatus of the invention further includes
A constant speed means for displacing the holder while suppressing a change in the moving speed of the holder in the direction along the moving direction of the holder at the center of the irradiation position (the above-described fast scan direction) during the irradiation. Provided
Shall .

According to this irradiation apparatus, the beam irradiation method according to the invention can be carried out. Therefore, it is possible to solve the problem related to non-uniform irradiation amount that occurs when a beam is irradiated onto an object to be moved that keeps an absolute posture constant. That is, it is possible to irradiate the entire surface of the irradiated object with a beam from a uniform angle and improve the uniformity of the irradiation density.

The beam irradiation apparatus of the invention
・ As the above speed equalization means, the rotating drive source of the rotating body is arranged to operate the angular velocity of the rotating body every time the holder reaches the irradiation position (including the vicinity).
It is also good to make things .

  For example, a servo motor capable of appropriately changing the speed may be used as the above-described means for operating the angular speed of the rotating body by arranging it in the rotational drive source of the rotating body. Also, when using a constant speed motor, etc., an inconstant speed gear (for example, non-circular gear) is provided in the power transmission path from the motor etc. to the rotating body, and the angular velocity of the rotating body is appropriately set in an appropriate phase. It is also possible to change it. By appropriately manipulating the angular velocity of the rotating body by such means, the change in the moving speed of the holder in the above direction (direction perpendicular to the linear moving direction) can be reduced.

The beam irradiation apparatus of the invention
-As a means for equalizing the speed, a mechanism for operating the moving speed of the holder every time the holder reaches the irradiation position (that is, changing the relative speed of the holder with respect to the rotating body), apart from the rotational drive source of the rotating body. Arranged
It is also good to make things .

  As the mechanism for changing the moving speed of the holder separately from the rotation driving source of the rotating body, the following may be considered. a) The holder that has reached the vicinity of the irradiation device is displaced at an appropriate speed in an appropriate direction (direction perpendicular to the linear movement direction) by an articulated robot arm or the like, b) The turning radius of the holder in the vicinity of the irradiation device (Position on the rotating body) is changed by guide grooves, articulated links, etc. c) Cylinders that expand and contract due to fluid pressure etc. are connected to the holders and mounted on the rotating body, and each holder is an irradiation device Each cylinder is expanded and contracted each time it reaches the vicinity, and the holder is displaced at an appropriate speed in an appropriate direction.d) Each cylinder that expands and contracts due to fluid pressure is connected to the holder and mounted on the rotating body. Each time the laser reaches the vicinity of the irradiation device, each cylinder is expanded and contracted to change the turning radius of the holder. By such means, the change in the moving speed of the holder in the above direction (direction perpendicular to the linear moving direction) can be reduced.

The beam irradiation apparatus of the invention
・ As the above speed equalization means, an intermediate holder is provided on the rotating body, and the holder is attached so as to be eccentrically rotated (rotation about a line off the center line of the intermediate holder) on the intermediate holder,
・ By combining the rotation of the intermediate holder on the rotating body and the eccentric rotation of the holder on the intermediate holder, the change in the moving speed of the holder during irradiation is suppressed as described above.
It ’s good to have something .

This irradiation apparatus can be configured as shown in FIG. 13, for example. The pedestal 2 (holder) is mounted on the rotating disk 1 (rotating body) via an intermediate holder 25, respectively, and the pedestal 2 is eccentrically rotated by the intermediate holder 25 that is off its center point 2a. The pedestal 2 moves along the locus Q by performing a combined motion of the rotation of the intermediate holder 25 on the rotating disk 1 and the rotation locus P of the rotating disk 1. These trajectories P · Q are also shown in FIG. When the vicinity of the center upper part of each locus in FIGS. 7B and 13 is a beam irradiation position, the moving speed of the pedestal 2 (and the wafer 3) during irradiation due to a small rotation radius at the top. The change in the horizontal direction component becomes small. FIG. 14 shows the temporal change of the moving speed V _H in the horizontal direction (direction along the α axis in FIG. 2) of the pedestal 2 and the like. Appear in
As long as the change in the moving speed of the holder (pedestal 2) can be reduced in this way by the action of the constant velocity means, the uniformity of the irradiation density can be improved also in this apparatus.

The beam irradiation apparatus of the invention
・ A sun gear (gear, sprocket or pulley) is installed on the rotation center line of the rotating body to fix its rotation, and a planetary gear (same as above) with the same number of teeth as the sun gear is installed on the rotating body and connected to the sun gear. To make a differential gear mechanism or a differential wrapping transmission mechanism (this is the power transmission means)
A second sun gear is provided on the rotating shaft of the planetary gear, and a second planetary gear having the same number of teeth as the second sun gear is connected to the second sun gear to connect the second differential gear mechanism or the second differential winding. Configure the hanging transmission mechanism,
· A transmission mechanism is provided to multiply the number of rotations of the second differential gear mechanism or the second differential winding transmission mechanism by an integer (n) with respect to the number of rotations of the differential gear mechanism or the differential winding transmission mechanism. As a constant speed method)
・ The above holder is attached to the rotating shaft of the second planetary gear.
It ’s good to have something . The integer (n) is preferably set to 3 to 5.

This irradiation apparatus can be configured as shown in FIGS. In the examples in these figures,
1. On the central axis of the main rotation of the rotary disk 1, there are fixed pulleys 21 and 21a fixed from the machine frame.
2. An outer pulley 34 is pivotally supported at an appropriate interval around the circumference of the rotating disk 1, and a timing belt 33 is hung between the fixed pulley 21 and a third differential winding transmission. The mechanism 40 is configured.
3. The pulley 22 is supported on the same axis as the outer pulley 34, and the timing belt 23 is hung between the pulley 22 and the fixed pulley 21a to constitute the differential winding transmission mechanism 20.
4. A pulley 31 is coaxially connected to the pulley 22 via a boss portion 27 to constitute a relay two-stage pulley.
5. An eccentric rotor 25 is coaxially connected to the outer pulley 34 on the rotating disk 1.
6. On the circumference of the eccentric rotor 25, a pedestal 2 (wafer 3) and a coaxially connected pulley 32 are pivotally supported, and a timing belt 23 'is hung between the pulley 32 and the pulley 31. The 2nd differential winding transmission mechanism 30 is comprised. (However, the fixed pulleys 21 and 21a are coaxial and multi-stage pulleys according to the number of outer wafer pedestals.)
Note that when these are constituted by a gear train, each pulley gear is replaced, and an intermediate gear is supported between the pulley shafts instead of the timing belt, as shown in FIG.

The beam irradiation apparatus of the invention
A beam irradiation apparatus that irradiates and implants an ion beam onto a semiconductor wafer that is an object to be irradiated on a holder;
・ Multiple holders are provided to rotate with a single rotating body.
It ’s good to have something .

In this irradiation apparatus, since the ion beam is irradiated / implanted on the semiconductor wafer, the above-described beam irradiation method can be carried out, and as described above, highly useful irradiation with high industrial value can be performed.
In addition, since the plurality of holders are provided so as to rotate together with one rotating body, the plurality of holders are rotated by a set of driving sources that rotate the rotating body, thereby irradiating a plurality of irradiated objects with beams. It can be done efficiently at the same time. There is also an advantage that operations for linearly moving the object to be irradiated (the slow scan described above) and changing its absolute posture can be performed simultaneously for each object to be irradiated by simply moving the rotating body or changing the angle.

According to the beam irradiation method of the invention, the beam irradiation is performed on the entire surface of the irradiated object from a uniform angle. For example, even when ion implantation is performed on a semiconductor wafer as the irradiated object, the tilt angle or the twist angle is not corrected. Will not occur. Moreover, as long as the irradiated beam is uniform, an irradiation density distribution according to the distance from the center of curvature of the moving path does not occur on the irradiation object.

In the beam irradiation method of the invention , the linear movement of the irradiated object corresponding to slow scan or the like is performed based on a constant speed, so that the control relating to the linear movement is simplified and the necessary equipment cost is also reduced.

According to the beam irradiation method of the invention , the density of the irradiation amount on the irradiation object can be made uniform.

The beam irradiation method of the invention can perform extremely useful irradiation particularly with respect to ion implantation into a semiconductor wafer.

According to the beam irradiation apparatus according to the invention, the irradiation method can be smoothly carried out, the effect described above is provided. There is also an advantage that the apparatus can be configured easily. If it is an apparatus of invention , the drive source (motor etc.) and control apparatus for rotating a holder (autorotation) are unnecessary. In particular, there is an advantage that the main part can be constituted by general-purpose simple parts.

In the beam irradiation apparatus of the invention, the direction of the irradiated object with respect to the beam irradiation direction can be easily changed.
With the beam irradiation apparatus of the invention , the above changes can be easily made with a simple structure. When a plurality of holders are attached, there is an effect that the postures of all the holders and the irradiated object can be changed at the same time. Moreover, such a posture change is possible even while the rotating body 1 is rotating.

In the beam irradiation apparatus of the invention , the linear movement of the irradiated object corresponding to slow scan or the like can be performed based on the constant speed motion at a constant reference speed, and the control is simplified, and the uniformity of the irradiation amount There is also an effect that accuracy is increased.

In the beam irradiation apparatus of the invention , the angle of the irradiated object with respect to the beam irradiation direction can be easily changed.

According to the beam irradiation apparatus of the invention , the above-described beam irradiation method can be carried out, and it is possible to irradiate the entire surface of the irradiation object with a beam from a uniform angle and to improve the uniformity of the irradiation density. is there.

If beam irradiation apparatus of the present invention, the terms of capable of performing beam irradiation method, it is possible to perform a plurality of beam irradiation to the irradiated object simultaneously efficiently.

  In the following, an embodiment of an ion implantation apparatus for mounting a plurality of semiconductor wafers (objects to be irradiated) on a disk-shaped or wheel-shaped rotating disk and irradiating the wafer with ions will be introduced. In the ion implantation apparatus, each wafer is uniformly irradiated with an ion beam (ion particles) by rotating the rotating disk and reciprocating the entire rotating disk in the radial direction of the rotating disk (see FIG. 2).

  In a general ion implantation apparatus, since the attitude of the wafer changes as the rotating disk rotates while the wafer crosses the ion beam, the incident angle of the beam with respect to the wafer (implantation angle: hereinafter referred to as the tilt angle) and the incident direction (Implantation direction: hereinafter referred to as twist angle) varies within the plane of the wafer and has a deviation. The apparatus shown below aims to obtain means for reducing or completely eliminating the occurrence of tilt angle and twist angle deviations. At the same time as this purpose, even if the wafer is loaded on the rotating disk and the rotating disk is rotating, by establishing means to arbitrarily change the tilt angle and twist angle, the beam can be viewed from multiple directions. It is an object of the present invention to perform a process of irradiating (injecting) a wafer onto a wafer with high productivity.

  The root cause of the twist deviation is that the direction of the wafer changes as the disk rotates (see FIG. 15). Therefore, as shown in FIG. 1C, if the pedestal 2 rotates on the rotating disk 1 in a direction to cancel the rotation, the direction of the wafer 3 seen from the outside does not change, that is, no twist deviation can be generated.

  In order to rotate the pedestal 2 so as to cancel the rotation on the disk 1, each pedestal 2 is provided with a rotation driving mechanism (motor or the like) for rotating the pedestal, and is synchronized with the main rotation A of the rotating disk 1. The pedestal 2 may be rotated (rotated B) at the same rotational speed in the direction opposite to the direction of the main rotation A. For example, if the pedestal 2 rotates once clockwise on the rotating disk 1 while the rotating disk 1 rotates counterclockwise, the posture of the pedestal 2 viewed from the outside does not change.

A method of performing the same movement without using a motor or the like for each pedestal 1 is shown in FIGS. In (a) and (b), a pedestal 2 loosely fitted to the rotating disk 1 and a fixed gear (pulley) 21 that does not rotate together with the rotating disk 1 are connected at a rotation ratio of 1: 1. By doing so, even if the rotating disk 1 rotates, the direction (phase) of the loosely fitted pedestal 2 is always kept the same as the direction (phase) of the fixed gear 21.
In FIGS. 1 (a) and 1 (b), the link (connection) between the two is constituted by pulleys 21 and 22 and a timing belt 23. However, this is an example, and a link can be constituted by a planetary gear or the like. It is.

  The advantage of this method is that there is no need to install a motor or the like in each pedestal 2, and this is advantageous in terms of ease of configuration, cost of components, weight reduction, and the like. In addition, when there is an independent rotation drive mechanism for each pedestal 2, it is expected that the adjustment method and control method for synchronizing the respective rotation speeds and phases will be complicated. Since the phase of the pedestal 2 is interlocked with the phase, synchronization adjustment and control are unnecessary. Furthermore, regardless of whether the rotating disk 1 is stopped or rotating, the phase of all the pedestals 2 can be changed by changing the phase of the fixed gear 21 as shown in FIG. In the case where it is desired to continuously perform the implantation, the wafer 3 can be continuously performed without remounting the wafer 3 on the pedestal 2 and without stopping the rotation of the rotating disk 1. In a device in which the tilt angle and twist angle are changed by tilting the rotary disk 1 with two axes, the twist angle can be adjusted entirely by changing the phase of the pedestal 2. The rotation axis can be reduced to only one axis.

  The movement of the main rotation A of the rotating disk 1 can be canceled by the rotation B of the pedestal 2 on the disk 1, so that the posture of the pedestal 2 (wafer 3) viewed from the outside can be kept unchanged. If the cone angle is set to 0 degree, the deviation of the tilt angle and the twist angle can be made zero by this method for any tilt angle.

When a fast scan by rotation of the rotating disk 1 and a slow scan (arrow 8 in FIG. 2) in which the rotating disk 1 reciprocates in a direction perpendicular to the rotating direction are performed by the mechanism as shown in FIG. As described with reference to FIG. 5, the ion implantation density tends to be non-uniform in the wafer 3. As described above, the countermeasure against this phenomenon is to make the speed component (in this case, the horizontal speed V _H ) of the first scan in the direction perpendicular to the slow scan direction constant.

  In order to make the velocity component in the direction perpendicular to the slow scan direction constant, theoretically, the main rotation A depends on the rotation angle θ of the rotating disk 1 within the time when the wafer 3 crosses the beam 5 (see FIG. 2). A method of modulating the speed of the image can also be considered.

  As an embodiment, the wafer 3 (pedestal 2) is held eccentrically, and the wafer 3 (pedestal 2) is eccentrically rotated around the eccentric center in conjunction with the main rotation A of the disk 1. This is a method of canceling the change in the horizontal speed caused by the main rotation with the horizontal speed component of the eccentric rotation.

This method is shown in FIG.
Here, numerical values are defined as follows.
Main turning radius: R
Eccentric turning radius: r
Assumed beam diameter: φ
Wafer diameter: Φ
Eccentric / Main rotation ratio: n
Initial phase difference: δ
Main rotational angular velocity: ω
Eccentric rotation angular velocity: nω

First, a scan angle θs that requires a constant speed is obtained.
Since a constant speed is required while the wafer crosses the beam, the scan angle θs during that time is
R sin θs = r + (Φ + φ) / 2
Θs = sin ⁻¹ {(2r + Φ + φ) / 2R}
It is enough if there is only.

The horizontal velocity V _{RH at the} center of eccentricity is
V _RH = Rω cosωt
The horizontal velocity V _rH of the wafer center relative to the eccentric center is
V _rH = r nω cos (nωt + δ)
Therefore, the actual horizontal velocity V _{WH at} the wafer center seen from the outside is
_{V WH = Rω cosωt + r nω} cos (nωt + δ)
It becomes.
The V _WH, may be determined a combination of variables such that substantially constant in the range of [theta] s.

  7A and 7B show a calculation example of the deviation of the actual horizontal velocity and the trajectory Q of the wafer 3 when R = 655 mm, r = 26.175 mm, and n = 3. In this case, with respect to the wafer diameter Φ = 300 mm and the assumed beam diameter φ = 100 mm, the horizontal speed deviation is within ± 0.06% within the region of the scan angle θs where a constant speed is required. It may be said that the speed is constant. 8A and 8B show the trajectories Q ′ and Q ″ of the wafer 3 in another case where n = 4 and 5 are set.

  Furthermore, according to this method, since the horizontal speed of the fast scan across the wafer 3 is constant at any position in the slow scan, it is not necessary to use the 1 / R scan for the slow scan. That is, the slow scan is based on a reciprocating motion at a constant speed, and it is only necessary to modulate the slow scan speed to compensate for the increase or decrease in the current value of the ion beam. The slow scan speed may be modulated in inverse proportion to the fluctuation rate P of the beam current with respect to the reference beam current. Since the 1 / R scan is not used, there is no need to measure the center of gravity position of the beam in the R direction, and there is no need to worry about a decrease in the repetition accuracy of the implantation dose due to the measurement error.

Examples embodying the concept shown above are shown in FIGS. 9, 11, and 12. FIG.
There are five main structural parts in this example: the pedestal 2, the eccentric rotor (intermediate holder) 25, the disc body 1, the fixed pulley 21, and the relay pulley (or gear) 27. The pedestal 2 holds the wafer 3 and has a structure that can freely rotate around the wafer center. A link is taken by a timing belt 23 (or a planetary gear or the like) to a fixed pulley 21 on the main rotation center axis through a relay two-stage pulley 27. The eccentric rotor 25 holds the rotation axis of the pedestal 2 at an eccentric position, and the eccentric rotor 25 itself has a structure that can rotate around its own central axis. The relay pulley 27 is used as a link for matching the phases of the fixed pulley 21 and the pedestal 2 at the main rotation center, and is loosely fitted on the central axis of the eccentric rotor 25. Can rotate freely independently. The fixed pulley 21 is an independent pulley that does not interlock with the main rotation, and is disposed on the central axis of the main rotation. The center of gravity of the eccentric rotor 25 and the pedestal 2 is made to substantially coincide with the central axis of the eccentric rotor 25 so that the rotational moment of the entire disk 1 does not change due to the eccentric rotation.

  Since the rotating disk 1 rotates while the posture of the pedestal 2 (wafer 3) remains constant when viewed from the outside, the centrifugal force due to the main rotation changes the direction according to the phase of the main rotation, and in all directions of the wafer 3. Works. Therefore, clamps for holding the wafer 3 must be arranged on the pedestal 2 at substantially equal intervals over the entire circumference of the wafer 3. Regardless of the direction in which the centrifugal force acts, in order to resist the centrifugal force with multiple clamps at the same time, the distance between adjacent clamps should be arranged at an angle not exceeding 90 degrees at the maximum. desirable.

In the ion implantation into the wafer 3, cooling is required to suppress the temperature rise of the wafer 3 during the implantation. For example, if an ion having an energy of 50 keV is irradiated onto the wafer 3 at a current value of 20 mA, the heat quantity of the ion beam will be as high as 1 kW. If there is no cooling, the temperature of the wafer 3 will be the temperature of the device pattern formation. This easily exceeds the heat resistance temperature of the photoresist applied to the wafer surface.
Therefore, in the normal rotating disk 1, a path for flowing a coolant such as water is provided in the rotating disk up to the vicinity of the pedestal 2, and the temperature of the wafer 3 is indirectly suppressed by cooling the pedestal 2 with the coolant. ing. Usually, a rubber is stuck on the pedestal surface holding the wafer 3, and heat transfer between the wafer 3 and the pedestal 2 is performed via this rubber. This heat transfer increases in efficiency as the force pressing the wafer against the pedestal increases.

If the cone angle is θ, a component force obtained by multiplying the centrifugal force acting on the wafer 3 by sin θ acts as a force for pressing the wafer 3 against the pedestal 2. The normal rotating disk 1 utilizes the centrifugal force component as a pressing force for improving heat transfer.
However, as the cone angle is decreased, the pressing force of the wafer 3 against the pedestal 2 decreases, and when the cone angle becomes 0 degrees, the pressing force becomes zero. When the pressing force decreases or disappears in this way, heat transfer between the wafer 3 and the pedestal 2 decreases, so that an alternative means is necessary.

  As an alternative, a mechanism called an electrostatic chuck is used in this embodiment. This is a method of holding the wafer 3 on the pedestal 2 using an electrostatic force, and is a mechanism widely used in a single-wafer type ion implanter, but is not used for holding the wafer 3 by the rotating disk 1. .

  Gas cooling is also effective for cooling between the wafer 3 and the pedestal 2. Gas cooling here does not transport heat by the specific heat of the gas, but when the mean free path of gas molecules is close to the distance between the two walls that sandwich the gas under low pressure, This is a phenomenon in which the movement of gas molecules efficiently transfers heat between the low temperature side wall and the other wall. The efficiency of this gas cooling is determined by the type of gas, the size of the gap into which the gas enters, and the pressure of the gas. Since the pressing force for maintaining the heat transfer efficiency is not required as in the case of rubber, gas cooling may be more appropriate for the rotating disk 1 having a small or zero cone angle than cooling via rubber.

In such a configuration, as described above, since the pedestal 2 is held by the disk body 1 via the eccentric rotor 25, the heat flow for cooling the wafer 3 is as follows.
Wafer 3 → Pedestal 2 → Eccentric rotor 25 → Disk body 1
It becomes.

  Although a liquid refrigerant such as water can flow through the disk main body 1, it is difficult to flow the liquid refrigerant up to the pedestal 2 and the eccentric rotor 25 having a structure that can be freely fitted and rotated there. Therefore, effective heat transfer means must be provided between the pedestal 2 and the eccentric rotor 25 and between the eccentric rotor 25 and the disk 1. Gas cooling that does not interfere with rotation without contact is also effective here (see FIG. 12).

Therefore, the cooling means considered as a whole is wafer 3 → (rubber) → pedestal 2 → (gas) → eccentric rotor 25.
→ (Gas) → Disc body 1 → (Cooling water)
Or
Wafer 3 → (Gas) → Pedestal 2 → (Gas) → Eccentric rotor 25
→ (Gas) → Disc body 1 → (Cooling water)
Can be considered.

In the former case, gaps for introducing gas are provided between the pedestal 2 and the eccentric rotor 25 and between the eccentric rotor 25 and the disc body 1. In the latter case, a gap is also provided between the wafer 3 and the pedestal 2 in addition to the above.
It is necessary to design the gap interval and the area of the two opposing surfaces sandwiching the gap in accordance with the amount of heat required for transport by gas cooling. When the gap interval is set to a value approximately close to the mean free path of the gas molecule at the introduced gas pressure, the heat transfer efficiency per unit area is good. The required area of the two opposing surfaces across the gap may be determined from the total heat input and the heat transfer coefficient per unit area.
Since the gap interval and the area of the two opposing surfaces sandwiching the air gap can be managed almost uniformly by the mechanical structure, it is necessary to measure and manage the gas pressure before use. Therefore, a mechanism (vacuum gauge) for measuring the pressure of the introduced gas is installed in the introduction path connected to the gas introduction gap.

  In order to prevent gas leakage and perform a rotation operation, a magnetic fluid seal is used for holding the pedestal 2 with the eccentric rotor 25 and holding the eccentric rotor 25 with the rotating disk 1. When gas is also introduced between the wafer 3 and the pedestal 2, a seal such as an O-ring is provided in the vicinity of the outer periphery of the wafer 3 at the contact surface between them. The gas is introduced from an introduction path provided in the rotating disk 1.

FIGS. 1A, 1B, and 1C are conceptual diagrams showing a basic configuration and an aspect relating to keeping the absolute posture of the wafer 3 (object to be irradiated) constant in the beam irradiation apparatus of the invention. It is a conceptual diagram which shows the relationship between the rotary disk 1 (rotary body), the wafer 3, the beam 5, etc. in the beam irradiation apparatus of invention. It is a conceptual diagram regarding changing the absolute attitude | position of the wafer 3 in the beam irradiation apparatus of invention. 3 is an explanatory diagram showing a beam trajectory and the like on the surface of a wafer 3; FIGS. 5A, 5B, and 5C are explanatory diagrams showing the reason why the irradiation density is non-uniform on the surface of the wafer 3 and the improvement method. It is a conceptual diagram for demonstrating the method of equalizing an irradiation density. FIGS. 7A and 7B are diagrams showing an example of calculation of the deviation of the actual horizontal velocity by the method of FIG. 6 and the wafer trajectory. 8A and 8B are diagrams showing another locus of the wafer calculated by the method of FIG. 9A and 9B are conceptual diagrams (a side view and a front view) showing a specific configuration of the beam irradiation apparatus. FIGS. 10A and 10B are conceptual diagrams (side view and front view) showing a specific configuration of another beam irradiation apparatus. It is a conceptual diagram which similarly shows the specific structure of a beam irradiation apparatus. Similarly, it is a figure which shows the specific structure of a beam irradiation apparatus, Comprising: It is an expanded sectional view of the vicinity of the pedestal 2. FIG. It is a conceptual diagram for demonstrating the locus | trajectory and speed of the wafer 3 about the specific structure of a beam irradiation apparatus. It is a diagram showing a temporal change in horizontal velocity V _H of the wafer corresponding to the trajectory. It is a conceptual diagram which shows the relationship between the rotating disk 1 'and the wafer 3' in the conventional beam irradiation apparatus.

Explanation of symbols

1 Rotating disc (rotating body)
2 Pedestal (holder)
3 Semiconductor wafer (object to be irradiated)
4 beam 20 differential winding transmission mechanism 21 fixed pulley (sun gear)
23 Timing belt 25 Eccentric rotor (intermediate holder)
30 Second differential winding transmission mechanism 33 Timing belt A Main rotation Q Trajectory

Claims (11)

A holder that holds the object to be irradiated is attached to a part other than the rotation center of the rotating body, and the beam is irradiated to the object at a specific irradiation position in the moving path of the object to be irradiated on the holder that rotates as the rotating body rotates. Irradiating means for irradiating, and means for maintaining the absolute posture of the irradiated object constant during irradiation at the irradiation position, attached to the rotating body or holder ,
During the irradiation, a constant speed means for displacing the holder while suppressing a change in the moving speed of the holder in the direction along the moving direction of the holder at the center of the irradiation position,
A beam irradiation apparatus characterized in that , as the constant velocity means, an intermediate holder is provided on a rotating body and the holder is attached so as to rotate eccentrically on the intermediate holder . The constant velocity means suppresses the change in the moving speed of the holder during irradiation as described above by combining the rotation of the intermediate holder on the rotating body and the eccentric rotation of the holder on the intermediate holder. The beam irradiation apparatus according to claim 1, wherein: A sun gear is provided on the rotation center line of the rotating body to fix the rotation, and a planetary gear having the same number of teeth as the sun gear is provided on the rotating body and connected to the sun gear, thereby providing a differential gear mechanism or differential winding. Configure the hanging transmission mechanism,
A second sun gear is provided on the rotating shaft of the planetary gear, and a second planetary gear having the same number of teeth as the second sun gear is connected to the second sun gear to connect the second differential gear mechanism or the second differential winding. Configure the transmission mechanism,
Provided with a transmission mechanism that makes the rotational speed of the second differential gear mechanism or the second differential winding transmission mechanism an integral multiple of the rotational speed of the differential gear mechanism or the differential winding transmission mechanism;
The beam irradiation apparatus according to claim 2 , wherein the holder is attached integrally with a rotation shaft of the second planetary gear. A beam irradiation apparatus for irradiating an ion beam to the semiconductor wafer as an object to be irradiated on the holder infusion claim 1 in which a plurality of holders, characterized in that is provided so as to rotate with one of the rotary body The beam irradiation apparatus in any one of -3 . As a means for keeping the absolute posture of the irradiated object constant, a control means for providing a rotation drive source for the holder to rotate the holder separately from the rotating body and setting both rotation speeds to the same angular speed in opposite directions. The beam irradiation apparatus according to claim 1 , wherein the beam irradiation apparatus is provided. As the means for keeping the absolute posture of the irradiated object constant, there is provided a power transmission means for connecting the rotating body and the holder so that the holder rotates at the same angular velocity opposite to that of the rotating body as the rotating body rotates. The beam irradiation apparatus according to claim 1 or 2 , characterized by the above. A sun gear is provided on the rotation center line of the rotating body to fix the rotation, and a planetary gear having the same number of teeth as the sun gear is provided on the rotating body and connected to the sun gear, thereby providing a differential gear mechanism or differential winding. 7. The beam irradiation apparatus according to claim 6 , wherein a hanging transmission mechanism is configured as the power transmission means, and the holder is integrally attached to the rotating shaft of the planetary gear. 8. The beam irradiation apparatus according to claim 1 , further comprising a holder setting posture changing means for changing the setting of the absolute posture of the irradiation object during the irradiation. The beam irradiation apparatus according to claim 7 , wherein the phase of the sun gear that fixes rotation can be changed in order to change the absolute posture of the irradiated object during the irradiation. While moving the rotating body linearly at a constant reference speed in a direction intersecting the center line, which is different from the irradiation direction of the beam and the moving direction of the irradiated object at the center of the irradiation position,
Measure the irradiation amount of the beam with the measuring means,
The beam irradiation apparatus according to claim 1, wherein the linear movement speed is changed from a reference speed according to the measured beam irradiation amount. The beam irradiation apparatus according to claim 1, wherein an angle of a posture of the rotating body on a plane with respect to a beam irradiation direction can be changed.

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