JP2017199603A - Ion beam etching apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a single-wafer-processing type ion beam etching apparatus arranged to measure a beam current during an ion beam etching process, which can increase the efficiency of using an ion beam and which can reduce an amount of sputtered particles coming from a holder.SOLUTION: An ion beam etching apparatus IE is arranged to apply an ion beam 3 to a whole face of a wafer 10 in a way to scan and reciprocate the wafer 10 in a second direction crossing an ion beam 3 while turning around the wafer 10. The ion beam etching apparatus comprises a beam current measuring instrument P disposed on a downstream side of the wafer 10 for measuring a beam current of the ion beam 3. The wafer 10 is reciprocated and scanned so as to satisfy the relation given by: 0<S≤IBw+D, where S is a scan width of the wafer 10 in the second direction, IBw is a size of the ion beam 3 in the second direction, and D is a larger size of either a size of the wafer 10 and a size of a holder 11 supporting the wafer 10 in the second direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a single-wafer type ion beam etching apparatus, and more particularly to an ion beam etching apparatus having means for measuring a beam current of an ion beam during an ion beam etching process.

  As an ion beam etching apparatus, an apparatus described in Patent Document 1 is known. This apparatus performs ion beam etching on individual wafers at a time by irradiating a plurality of wafers arranged in the circumferential direction of the disk-shaped holder with an ion beam having a size covering all the wafers. This is a so-called batch type ion beam etching apparatus.

  The ion beam etching apparatus also includes an adjusting unit that measures the beam current distribution in the wafer surface irradiated with the ion beam during the ion beam etching process and adjusts the beam current distribution according to the measurement result. Yes. Hereinafter, a specific configuration will be described.

As a means for measuring the beam current, there are a plurality of Faraday cups arranged in the radial direction from the center of the holder. During the ion beam etching process, the beam current of the ion beam incident on each Faraday cup is determined at a predetermined timing. It is measured several times.
The beam current value measured in each Faraday cup is transmitted to the current integrator, and the beam current value measured for each Faraday cup is integrated by the current integrator.

  The integrated value of the beam current measured in each Faraday cup is averaged for each group of Faraday cups grouped into two groups along the holder radial direction. The integrated values averaged for each group are compared with each other, and the beam current in the wafer surface irradiated with the ion beam is increased or decreased by increasing or decreasing the high-frequency power source output of the high-frequency ion source according to the magnitude relationship of the integrated values. Distribution adjustments are made.

JP 2010-118290 A

The extraction electrode system of the ion source is composed of a plurality of three or four electrodes. In the process of extracting the ion beam from the extraction electrode system, ions collide with some of the electrodes. As a result, the electrode is sputtered and consumed.
Further, sputtered particles are generated from the wafer by the ion beam etching process. When the sputtered particles are scattered on the extraction electrode system, they are deposited on the extraction electrode system, causing clogging of the electrodes constituting the extraction electrode system and abnormal discharge between the electrodes.

  For the above reason, the state of the extraction electrode system changes every moment while the ion beam etching process is performed. Since the change in the state of the extraction electrode system affects the beam current and beam current distribution of the ion beam extracted from the extraction electrode system, the ion beam etching apparatus performs ion beam etching processing as in Patent Document 1. It is desirable to have a device configuration that can measure the beam current of the ion beam while adjusting the measured beam current as necessary.

  The ion beam etching apparatus is not necessarily limited to the batch type apparatus described in Patent Document 1. There is also a single wafer processing apparatus for processing wafers one by one. FIG. 10 shows a holder when a beam current measuring unit similar to that of Patent Document 1 is applied to a single-wafer type apparatus.

  Since it is a single wafer type, the number of wafers 10 supported by the holder 11 is one, and this wafer 10 is irradiated with an ion beam 3 having a size slightly larger than that of the wafer 10. A plurality of Faraday cups F are arranged in the holder 11 in the radial direction from the center C as in Patent Document 1. In this configuration, the holder 11 is rotated about the center C in the direction of arrow A, and the wafer 10 is irradiated with the ion beam 3, whereby an ion beam etching process is performed on the wafer 10. Further, the measurement of the beam current by the Faraday cup F is performed when the Faraday cup F moves to the irradiation position of the ion beam 3.

  By adding means for adjusting the beam current distribution to the configuration shown in the figure, the beam current is measured during the ion beam etching process as in Patent Document 1, and is extracted from the extraction electrode system of the ion source according to the measurement result. Although it becomes possible to adjust the beam current distribution of the ion beam, problems remain in the following points.

  In the configuration of FIG. 10, the wafer 10 is irradiated with the ion beam 3 by rotating the wafer 10 to the irradiation position of the ion beam 3, but the ion beam 3 is irradiated on the wafer 10 for a long time. Without being used for the ion beam etching process, the holder 11 is merely irradiated. That is, the utilization efficiency of the ion beam 3 is poor only by applying the configuration of Patent Document 1 as it is to a single-wafer apparatus.

  Moreover, since the time during which the holder 11 is irradiated with the ion beam 3 becomes longer, the ion beam 3 sputters the holder 11 for a long time, and a large amount of sputtered particles are generated from the holder 11. These sputtered particles can be mixed into devices on the wafer surface and cause device manufacturing defects, or can be scattered on the extraction electrode system side and deposited on the electrodes, causing clogging of electrodes and abnormal discharge between electrodes. There is concern that it will be a factor.

  Therefore, in the present invention, it is an object to improve the use efficiency of the ion beam and reduce the amount of sputtered particles generated from the holder in a single-wafer type ion beam etching apparatus that measures the beam current during the ion beam etching process. To do.

  The ion beam etching apparatus according to the present invention is configured so that the second ion beam intersects the ion beam irradiated in the third direction while rotating the wafer with respect to the ion beam longer than the wafer size in the first direction. In the ion beam etching apparatus that irradiates the entire surface of the wafer with an ion beam by reciprocally scanning the wafer in the direction, the ion beam is disposed downstream of the wafer in the third direction and measures the beam current of the ion beam. A beam current measuring device, wherein the scanning width of the wafer in the second direction is S, the size of the ion beam in the second direction is IBw, and the wafer or the wafer in the second direction When the larger dimension of the holder that supports is D, the wafer is reciprocally scanned so as to satisfy the relationship of 0 <S ≦ IBw + D.

With the above configuration, the beam current of the ion beam can be measured during wafer processing by using the beam current measuring device arranged on the downstream side of the wafer in the third direction in which the ion beam is irradiated.
Further, since the beam current measuring instrument is provided at a place different from the holder, the holder can be miniaturized. As a result, the irradiation amount of the ion beam to the holder is reduced, and the amount of sputtered particles generated from the holder can be reduced.
Furthermore, by reciprocatingly scanning the wafer so as to satisfy the above formula, the time during which the ion beam is not irradiated on the wafer can be reduced to zero, or can be reduced to a very short time. improves.

  For the purpose of measuring the beam current distribution over the entire area of the ion beam irradiated on the wafer in the first direction, the scan width is D <S ≦ IBw + D, and the beam current measuring instrument is A configuration having a length equal to or larger than the dimension of the wafer in the first direction and having a plurality of measurement regions in the first direction may be used.

In the second direction, even if the beam current distribution of the ion beam is somewhat non-uniform, the wafer is scanned back and forth, so that the dose distribution of the ion beam irradiated onto the wafer is averaged.
On the other hand, since the wafer is not reciprocally scanned in the first direction, the beam current distribution of the ion beam greatly affects the irradiation amount distribution of the ion beam irradiated onto the wafer.
For this reason, it is desirable to be able to measure the beam current distribution in the first direction, which has a great influence on the uniformity of ion beam irradiation. In particular, it is desirable to be able to measure the beam current distribution over the entire area of the ion beam irradiated on the wafer in the first direction.
In order to realize this, a plurality of beam current measuring devices are arranged in the first direction, and the scanning width during the reciprocating scanning of the wafer is made larger than D. With this configuration, the entire ion beam is irradiated to the downstream side of the wafer in the first direction in a region in the second direction. As a result, the beam current distribution can be measured over the entire area of the ion beam irradiated on the wafer in the first direction on the downstream side of the wafer, and the ion beam irradiation amount can be determined from the measured beam current distribution. Uniformity adjustment and evaluation can be performed.

  The beam current measuring instrument preferably measures the beam current in each region where the periphery and center of the wafer pass in the first direction.

Since the wafer is reciprocally scanned and rotated while the ion beam etching process is being performed, the ion beam area passing through the center and the periphery of the wafer is different.
In particular, when the beam current measuring device is arranged at a location different from the holder to reduce the size of the holder, and the rotation center of the holder and the rotation center of the wafer substantially coincide, Thus, the peripheral portion of the wafer moves greatly in the first direction. On the other hand, the central portion of the wafer hardly moves.
Further, the angular velocity is different between the wafer periphery and the center. Even if the ion beam region having the same beam current is passed, the ion beam dose differs between the periphery and the center of the wafer due to the difference in angular velocity.
In view of these points, it is desirable to be able to measure the beam current of the ion beam in each region where the center and the periphery of the wafer pass.

  A tilt mechanism is used to rotate the wafer around a predetermined axis to set the irradiation angle of the ion beam with respect to the wafer. As the tilt mechanism, the first direction as the rotation axis, It is desirable to tilt the wafer.

  The tilt mechanism described above is configured to rotate the wafer about the first direction orthogonal to the second direction, which is the wafer reciprocating scanning direction. Therefore, when the wafer is tilted by the tilt mechanism, ion beam etching is performed. Sputtered particles scattered from the wafer to the extraction electrode system side are scattered substantially in the second direction, and are deposited on the electrodes.

In this case, the deposition amount of sputtered particles on the electrode is biased in the second direction, so that the beam current distribution of the ion beam extracted from the electrode is non-uniform in the second direction.
However, since the wafer is reciprocated in the second direction and the ion beam dose distribution in the wafer surface is averaged, the influence on the uniformity of the ion beam etching process in the wafer surface is small. Tesumu.

  Further, an auxiliary plate having an outer shape of a quadrangle that is reciprocally scanned with the wafer and shields the ion beam in a fixed state is provided on the downstream side of the wafer in the third direction, and the outer shape of the auxiliary plate A configuration in which the shape has two sides parallel to the first direction may be adopted.

When the wafer outer shape is circular, when the ion beam is partially shielded by the wafer, the shape of the ion beam irradiated to the beam current measuring device on the downstream side of the wafer becomes distorted, but the above auxiliary plate is used. This shape can be shaped.
If the auxiliary plate is provided, the ion beam irradiation angle in the second direction can be calculated based on the temporal change in the beam current shielded by the auxiliary plate.

Since the beam current measuring instrument is arranged on the downstream side of the wafer in the third direction of irradiation with the ion beam, the beam current measuring instrument can be used to measure the beam current of the ion beam during wafer processing. Become.
Further, since the beam current measuring instrument is provided at a place different from the holder, the holder can be miniaturized. As a result, the irradiation amount of the ion beam to the holder is reduced, and the amount of sputtered particles generated from the holder can be reduced.
Furthermore, by setting the scanning width of the wafer so as to satisfy a predetermined relationship, the time during which the ion beam is not irradiated on the wafer can be reduced to zero or very short. Use efficiency improves.

1 is a schematic plan view according to an ion beam etching apparatus of the present invention. FIG. 2 is a schematic plan view when the ion beam etching apparatus shown in FIG. 1 is viewed on a YZ plane. FIG. 3 is a schematic plan view when the processing chamber illustrated in FIGS. 1 and 2 is viewed from a Z direction. The typical top view which shows an example of the beam current distribution measured with the current distribution measuring device. Explanatory drawing of the electric current distribution measuring device which has a measurement area | region corresponding to the center and periphery of a wafer. The typical top view which shows a structure when the rotating shaft of a tilt mechanism is made into an X-axis. The typical top view which shows the structural example which provided the auxiliary | assistant board in the ion beam etching apparatus of FIG. FIG. 8 is a schematic plan view when the processing chamber illustrated in FIG. 7 is viewed from the Z direction. The typical top view which shows the example of the irradiation angle measurement using an auxiliary | assistant board. The typical top view which shows the structural example when the structure of a prior art is applied to a single wafer apparatus.

  1 to 3 are schematic plan views when the ion beam etching apparatus IE of the present invention is viewed from different planes. The configuration of the ion beam etching apparatus IE according to the present invention will be described with reference to these drawings.

  The ion source 1 is a conventionally known ion source such as a bucket type, a high frequency type, or a Bernas type, and includes an extraction electrode system 2 for extracting an ion beam. The extraction electrode system 2 is composed of 3 to 4 plate-like electrodes in which a plurality of ion beam extraction holes made of a porous or multi-slit are formed.

  The ion beam 3 extracted through the extraction electrode system 2 of the ion source 1 is irradiated to the processing chamber 4. The wafer 10 is, for example, a disk-shaped wafer, and the back surface thereof is supported by a holder 11 having a size equal to or smaller than the wafer diameter.

  The holder 11 is driven by three conventionally known mechanisms. Each mechanism will be briefly described.

  The reciprocating scanning mechanism 14 is a mechanism that reciprocally scans the holder 11 in a direction that intersects the Z direction shown in the figure, which is the traveling direction of the ion beam 3, and in the configuration of FIGS. The shaft is reciprocated in the X direction using a drive source such as a motor (not shown).

The tilt mechanism 13 is a mechanism used to set the irradiation angle of the ion beam 3 irradiated to the wafer 10 by rotating the holder 11 around an arbitrary axis. In the configuration shown in FIGS. It is a mechanism that is connected to one end of a drive shaft that is moved by the scanning mechanism 14 and rotates the holder 11 around the Y axis.
In the present invention, the tilt angle is set by the tilt mechanism 13 before the ion beam etching process on the wafer 10 is started.

  The twist mechanism 12 is a mechanism that rotates the holder 11 around its center. In the present invention, the twist mechanism 12 continuously rotates the holder 11 while the ion beam etching process is performed.

  The reciprocating scanning mechanism 14, the tilt mechanism 13, and the twist mechanism 12 are all mechanisms that drive the holder 11. However, since the holder 11 supports the wafer 10, it can also be considered as a mechanism that drives the wafer 10. .

  In the present invention, the beam current measuring device P is provided at a place different from the holder 11. With this configuration, the holder 11 can be downsized, the amount of irradiation of the ion beam 3 onto the holder 11 can be reduced, and the amount of sputtered particles generated from the holder 11 can be reduced.

1 to 3, it is assumed that an electrostatic chuck is used as the holder 11. Therefore, the holder 11 that supports the back surface of the wafer is smaller in size than the wafer 10. In some cases, the size of the holder 11 is larger than that of the wafer 10. For example, if the holder includes a mechanical clamp mechanism that holds the outer periphery of the wafer, the size is slightly larger than that of the wafer.
In the present invention, a holder having a size larger than that of the wafer described above may be used. Even in such a holder, since the beam current measuring device P is provided at a place different from the holder 11, the holder size can be made smaller than that of the conventional configuration.

A specific location of the beam current measuring device P is a location on the downstream side of the holder in the Z direction where the ion beam 3 is irradiated.
1 to 3, a multipoint Faraday cup in which a plurality of Faraday cups are arranged in the Y direction is assumed as the beam current measuring device P. However, a configuration using a single Faraday cup may be used. That is, the measurement region in the Y direction of the beam current measuring device P may be divided into a large number or may be a single configuration without being divided.

  If the beam current is measured only at an arbitrary point without monitoring the beam current distribution and the state of the electrode from which the ion beam is extracted is monitored, the beam current measuring instrument P is a single Faraday. A configuration using a cup may be used.

  FIG. 3 is a plan view of the processing chamber 4 shown in FIGS. 1 and 2 when viewed from the Z direction. The dimension of the ion beam 3 is larger than the diameter of the wafer 10 in the Y direction and smaller than the diameter of the wafer 10 in the X direction. Since the wafer 10 is continuously rotated while reciprocating the wafer 10 in the X direction intersecting with the ion beam 3 as described above, irradiation of the ion beam on the entire surface of the wafer can be realized.

  Wafers 10 drawn on both sides of the ion beam 3 in the X direction show the state of the wafer at the turn-back position of the wafer reciprocation scanning. Speaking of the reciprocal scanning of the wafer 10, as shown in the figure, it may be scanned to a position completely crossing the ion beam 3 in the X direction. However, the time during which the ion beam 3 is not irradiated on the wafer 10 may be used. The scanning width S of the wafer 10, which is the distance between the centers of the wafers at the turn-back position of the wafer reciprocating scanning, is taken into consideration in order to improve the ion beam utilization efficiency in a very short time. , Is set within a range that satisfies the following mathematical formula.

  When the scanning width of the wafer 10 reciprocally scanned along the X direction is S, the dimension of the ion beam 3 in the X direction is IBw, and the dimension of the wafer 3 in the X direction is D, 0 <S ≦ IBw + D The scanning width S of the wafer is set in a range that satisfies the above.

  Except for the case where the scanning width S is IBw + D, the wafer 10 is always irradiated with a part of the ion beam 3 during the wafer reciprocating scanning. Since the wafer is always irradiated with a part of the ion beam 3 at the turn-back position of the reciprocating scanning where the wafer scanning speed is particularly low, the irradiation amount of the ion beam locally increases within the wafer surface. However, in the present invention, since the wafer 10 is continuously rotated by the twist mechanism 13 during the reciprocating scanning of the wafer, it is possible to average the dose in the wafer plane.

  In FIG. 3, since the wafer reciprocating scan direction and the X direction are parallel, the above formula shows the dimensional relationship of each part in the X direction. However, when the wafer reciprocating scan direction is not parallel to the X direction, The scanning width S at the time of wafer reciprocating scanning is set in relation to the dimension IBw of the ion beam and the dimension D of the wafer in a direction parallel to the wafer reciprocating scanning direction.

Further, the dimensions of the wafer are not necessarily the diameter of the wafer. FIG. 3 shows a case where the tilt angle of the wafer 10 is 0 °. When the tilt angle of the wafer 10 is set by the tilt mechanism 13, if the tilt angle is θ and the diameter of the circular wafer is R, the wafer dimension in the wafer reciprocating scanning direction is R cos θ. D is Rcosθ. The tilt angle refers to an angle formed by the normal direction to the wafer surface and the irradiation direction of the ion beam applied to the wafer surface.
In the present invention, the shape of the wafer is not limited to a circle. For example, if the wafer is rectangular, D in the above formula is the size of the rectangular wafer in the wafer reciprocating scanning direction.

Further, when the holder 11 having a size larger than that of the wafer 10 such as a mechanical clamp is used, the above-described numerical formula D is the size of the holder 11 in the wafer reciprocating scanning direction.
That is, D in the above formula is the larger dimension of the wafer 10 or the holder 11 that supports the wafer 10 in the wafer scanning direction.

  The scanning width S at the time of wafer reciprocating scanning may be set in the range of D <S ≦ IBw + D.

In the wafer reciprocating scanning direction, even if the beam current distribution of the ion beam 3 is somewhat non-uniform, the irradiation distribution of the ion beam irradiated onto the wafer 10 is averaged by the wafer 10 being reciprocated.
On the other hand, since the wafer 10 is not reciprocally scanned in the Y direction, there is a concern that the beam current distribution of the ion beam 3 in the Y direction has a great influence on the dose distribution of the ion beam 3 in the wafer plane. For this reason, it is desirable to be able to measure the beam current distribution in the Y direction, which has a great influence on the uniformity of the irradiation amount of the ion beam 3. In particular, it is desirable to be able to measure the beam current distribution over the entire area of the ion beam 3 irradiated on the wafer 10 in the Y direction.

  In order to realize this, the beam current measuring device P is configured to have a length equal to or larger than the dimension of the wafer 3 in the Y direction and to have a plurality of measurement regions in the Y direction, and to scan width S during wafer reciprocating scanning. Is larger than D. With this configuration, the entire ion beam 3 is irradiated to the downstream side of the wafer in the Y direction in a certain region in the wafer reciprocating scan direction during the wafer reciprocating scan. As a result, it becomes possible to measure the beam current distribution over the entire area of the ion beam irradiated to the wafer 10 in the Y direction on the downstream side of the wafer, and to adjust and evaluate the uniformity of the irradiation amount of the ion beam 3. It can be performed.

Various methods for determining whether the ion beam 3 irradiated from the ion source 1 is normal can be considered.
For example, before the start of the ion beam etching process, a reference beam current is measured in advance and stored as a reference value in a storage area of a control device that controls the reciprocating scanning mechanism and the like. Then, the beam current is measured during the ion beam etching process, compared with the reference value read from the control device, and whether the ion beam is normal or abnormal is determined based on the amount of deviation from the reference value. It ’s okay.

  Even when beam current is measured at a plurality of points in the Y direction, the beam current values measured at a plurality of points before the start of the ion beam etching process described above are prepared as reference values, and the actually measured beam By comparing with the current, the normal or abnormal state of the ion beam may be determined. If the beam current values are substantially the same depending on the measurement location, the reference value may be measured only at an arbitrary point.

  On the other hand, instead of preparing such a reference value in advance, it may be possible to determine whether the ion beam is normal or abnormal by using only measured values.

  For example, the case where the scanning width S is IBw + D in FIG. 3 will be described as an example. FIG. 4 shows the beam current I measured by the eight Faraday cups F1 to F8. 4 also illustrates the configuration of FIG. 3 so that the relationship with the configuration illustrated in FIG. 3 becomes clear. The beam current distribution shown in FIG. 4 is a beam current distribution in the Y direction measured by the beam current measuring instrument P when the wafer is at the turning point of the reciprocating scan.

  An average beam current is calculated from the beam currents I measured by the eight Faraday cups F1 to F8, and the calculated average beam current is compared with the beam current measured by each Faraday cup. As a result of the comparison, if a difference of a predetermined value or more is confirmed, it is determined that the ion beam is abnormal.

  On the other hand, instead of calculating the average beam current, the beam currents measured in each Faraday cup may be compared with each other to determine whether the ion beam is normal or abnormal. For example, the measured values of the beam currents measured in adjacent Faraday cups are compared, and if this difference is greater than or equal to a predetermined value, it is determined that the ion beam is abnormal.

  In FIG. 4, since the scanning width S is IBw + D, the irradiation area of the ion beam irradiated to each Faraday cup is constant. However, when the scanning width S is less than IBw + D, each Faraday cup is irradiated. There is a difference in the irradiation area of the ion beam. In this case, normal or abnormal ion beams cannot be determined by simply comparing the beam currents measured in each Faraday cup as described above.

  Therefore, in this case, prior to the comparison between the beam currents, the conditions of the beam current values measured in each Faraday cup are made uniform. Various methods are conceivable. For example, the area where the ion beam incident on each Faraday cup is shielded by the wafer at the turn-back point of the wafer reciprocating scan is obtained by calculation. This calculation is performed using known values such as the irradiation position of the ion beam, the size of the ion beam, the size of the wafer and the holder, and the size and arrangement of the Faraday cup.

  Thereafter, the ratio of the area of the measurement region of each Faraday cup to the shielding area of the ion beam by the wafer is calculated. Using this ratio, the beam current value measured by each Faraday cup is converted at the turning point of the wafer reciprocating scanning. In this way, using the converted beam current value, the beam current value for each Faraday cup is compared to determine whether the ion beam is normal or abnormal.

  When the wafer 10 is continuously rotated around the center, there is a difference in the region where the ion beam passes between the center and the periphery of the wafer. The reason for this will be described with reference to FIG.

When the wafer 10 is reciprocally scanned in the direction indicated by the arrow A and continuously rotated around the center C, the peripheral area of the wafer is the Faraday cups A to C illustrated in the Y direction as the wafer 10 rotates. Cross the group area. On the other hand, since the wafer center region is close to the center of rotation, it moves only within the region of group B.
In other words, the ion beam of the beam current measured by the Faraday cups F1 to F8 is irradiated to the peripheral area of the wafer, whereas the ion of the beam current measured by the Faraday cups F4 and F5 is irradiated to the central area of the wafer. Only the beam will be irradiated.

  Further, the angular velocity is different between the wafer periphery and the center. Even if the ion beam region having the same beam current is passed, the irradiation amount at the periphery and the center of the wafer differs due to the difference in angular velocity.

  In consideration of the above matters, when adjusting the dose distribution in the wafer surface including the center and the periphery of the wafer, the beam current measuring device P is used for each of the periphery and center of the wafer passing in the Y direction. It is desirable that the beam current is measured in the region.

  The tilt mechanism 13 is used to rotate the wafer around a predetermined axis and set the irradiation angle of the ion beam with respect to the wafer. The effect on the dose distribution is very different.

For example, as in the configuration shown in FIG. 6, when the X direction is the rotation axis when the tilt angle is set, there is a concern that the dose distribution in the wafer surface will be large and non-uniform.
As shown in the figure, it is assumed that the wafer 10 is rotated around an axis parallel to the X direction by the tilt mechanism 13 so that the irradiation angle of the ion beam 3 to the wafer 10 is set to an arbitrary angle other than 0 °. The sputtered particles Q are scattered from the wafer 10 to the extraction electrode system 2 side by the ion beam etching process. However, in the configuration of FIG. 6, the tilt mechanism 13 rotates the wafer in the X direction. The sputtered particles Q are locally deposited on the extraction electrode system 2 in the Y direction.

  If the amount of deposited deposit increases, the ion extraction hole of the extraction electrode system is clogged, and the beam current distribution of the ion beam 3 extracted from the extraction electrode system becomes non-uniform. In the configuration of FIG. 6, since the sputtered particles Q tend to scatter in the Y direction due to the irradiation angle of the ion beam onto the wafer 10, there is a concern that the beam current distribution in the same direction becomes non-uniform. The

  When the ion beam having this non-uniform beam current distribution is irradiated onto the wafer, the ion beam irradiation amount distribution in the wafer surface becomes non-uniform, and therefore, in combination with the reciprocating scanning of the wafer 10 in the wafer surface. It is conceivable to make the irradiation dose distribution uniform, but since the wafer reciprocating scan is performed along the X direction, the wafer reciprocating scan improves the ion beam irradiation distribution within the wafer surface. I can't.

  Therefore, in the present invention, as shown in FIGS. 1 and 2, a tilt mechanism 14 having a rotation axis in the Y direction perpendicular to the scanning direction at the time of wafer reciprocating scanning is employed.

  With such a tilt mechanism 14, the wafer 10 is rotated about the Y direction orthogonal to the second direction, which is the wafer reciprocating scanning direction. Therefore, when the wafer 10 is tilted by the tilt mechanism 13, The sputtered particles scattered from the wafer 10 to the extraction electrode system 2 side by the ion beam etching process are scattered substantially in the wafer reciprocating scanning direction and deposited on the electrode.

In this case, since the deposition amount of sputtered particles on the electrode is biased in the wafer reciprocating scanning direction, the beam current distribution of the ion beam 3 extracted from the electrode is also non-uniform in the wafer reciprocating scanning direction. Become.
However, since the wafer 10 is reciprocated in this direction, the dose distribution of the ion beam 3 is averaged, and the influence on the uniformity of the ion beam etching process within the wafer surface can be reduced.

Furthermore, in the present invention, an auxiliary plate 15 that reciprocally scans with the wafer 10 and shields the ion beam 3 with the posture fixed may be provided on the downstream side of the wafer 10 in the Z direction.
6 and 7 show a configuration example of the ion beam etching apparatus IE of the present invention provided with such an auxiliary plate 15.

The auxiliary plate 15 is fixed to the tilt mechanism 13 by a fastener such as a bolt (not shown), for example, and a through-hole through which the tilt mechanism 13 is inserted is formed inside.
When the auxiliary plate 15 is viewed from the Z direction, the auxiliary plate 15 is a rectangular plate extending outward from the wafer 10 and has two sides parallel to the Y direction. Further, the auxiliary plate 15 partially overlaps the wafer 10 in the Z direction.

When the ion beam 3 is shielded by the circular wafer 10 as the wafer is reciprocated, the shape of the ion beam applied to the beam current measuring device P on the downstream side of the wafer becomes distorted. For example, when a multipoint Faraday cup is used, if the shape of the ion beam is distorted, a difference occurs in the amount of ion beam incident on each Faraday cup.
However, as shown in FIG. 8, since the ion beam is shielded by a rectangular wafer by using the auxiliary plate 15, the ion beam incident on each Faraday cup arranged on the downstream side of the wafer is used. The amount of shielding can be made constant. As a result, the measurement results at each Faraday cup can be directly compared, and the measurement results can be easily used.

  Further, if the auxiliary plate 15 is provided, the irradiation angle of the ion beam 3 can be obtained during the reciprocating scanning of the wafer. FIG. 9 is an explanatory diagram of a method for calculating the irradiation angle of the ion beam 3 using the auxiliary plate 15.

  Ideally, the beam current distribution of the ion beam 3 is a Gaussian distribution. If the center of the beam current measuring device P in the X direction coincides with the center of the ion source 1 and the ion beam 3 emitted from the ion source 1 is irradiated straight, the peak of the beam current is measured by the beam current measurement. Appears at the center of the vessel P.

The beam current of the ion beam 3 irradiated to an arbitrary Faraday cup is measured while moving the auxiliary plate 15 in the X direction as the wafer reciprocates. From the measurement result, the change amount of the beam current is calculated, and how far the peak of the change amount is in the X direction from the center position of the beam current measuring device P is calculated. If the separation distance is L1, and the distance between the beam current distribution measuring instrument P and the ion source 1 is L2, the irradiation angle of the ion beam 3 can be calculated from θ = tan ⁻¹ (L1 / L2). .

  The beam irradiation angle measurement method described above is generally known as a knife edge method, but the method of measuring the beam irradiation angle is not limited to this method. For example, a pinhole or slit is opened in the auxiliary plate 15, the beam current amount of the ion beam 3 incident on the beam current measuring instrument P is measured through these, and the irradiation angle of the ion beam 3 is calculated from the measurement result. Good. In this case, the center position of the ion beam 3 is located at the place where the beam current value measured by the beam current measuring device P becomes the maximum through the pinhole or slit formed in the auxiliary plate 15 while moving the auxiliary plate 15. Ion beam irradiation based on the amount of deviation between this location and the location where the central position of the ion beam 3 is irradiated, and the distance from the ion source 1 to the beam current measuring device P. It is conceivable to calculate the angle.

Based on the result of the normal / abnormal ion beam determination described in the embodiments so far, an adjustment unit for adjusting the beam current distribution of the ion beam may be provided in the ion source.
For example, when the ion source is a high-frequency ion source, it is configured so that the increase / decrease adjustment of the high-frequency power output of the ion source can be performed. In the case of an ion source having a plurality of cathodes, the beam current distribution of the ion beam drawn from the ion source may be adjusted by adjusting the amount of current flowing through each cathode. Further, in the case of an ion source having a plurality of ionized gas supply paths, the flow rate of the gas flowing through each gas supply path is individually increased or decreased to adjust the beam current distribution of the ion beam drawn from the ion source. Also good.

  In addition to the above, various improvements and modifications may be made without departing from the scope of the present invention.

1. Ion source 2. 2. Extraction electrode system Ion beam4. Processing chamber 10. Wafer 11. Holder 12. Twist mechanism 13. Tilt mechanism 14. Reciprocating scanning mechanism 15. Auxiliary plate Beam current measuring instrument

Claims (5)

Reciprocally scan the wafer in a second direction intersecting the ion beam irradiated in a third direction while rotating the wafer with respect to an ion beam longer than the wafer dimension in the first direction. In an ion beam etching apparatus that performs ion beam irradiation on the entire wafer surface,
A beam current measuring device disposed downstream of the wafer in the third direction and measuring a beam current of the ion beam;
The scanning width of the wafer in the second direction is S,
The dimension of the ion beam in the second direction is IBw,
When the larger dimension of the wafer or the holder supporting the wafer in the second direction is D,
An ion beam etching apparatus for reciprocally scanning the wafer so as to satisfy a relationship of 0 <S ≦ IBw + D. The scan width is D <S ≦ IBw + D,
The ion beam etching apparatus according to claim 1, wherein the beam current measuring instrument has a length equal to or larger than the dimension of the wafer in the first direction, and has a plurality of measurement regions in the first direction.   3. The ion beam etching apparatus according to claim 2, wherein the beam current measuring device measures the beam current in each of the regions where the periphery and center of the wafer pass in the first direction.   The ion beam etching apparatus according to any one of claims 1 to 3, further comprising a tilt mechanism that tilts the wafer with the first direction as a rotation axis. In a state where the posture is fixed, the wafer is reciprocally scanned with the wafer, and an auxiliary plate having an outer shape of a quadrangle that shields the ion beam is provided on the downstream side of the wafer in the third direction,
The ion beam etching apparatus according to any one of claims 2 to 4, wherein an outer shape of the auxiliary plate has two sides parallel to the first direction.