WO2024252499A1 - Surface inspection device - Google Patents

Abstract

A surface inspection device (1) according to the present invention comprises: a motor (4) that rotates a sample holding member (3); a turntable (5) that rotates by means of the motor (4); and a drive mechanism (11) that displaces the sample holding member (3) in a focus direction. The drive mechanism (11) comprises: a yoke (13) having a cylindrical shape and fixed to the sample holding member (3); a plurality of first magnets (14) fixed to the surface of the yoke (13) and magnetized in the radial direction of the yoke (13); a plurality of second magnets (15) fixed to the surface of the yoke (13) and magnetized in the direction opposite to the polarity of the first magnets (14); a first coil (17) disposed around the outer side in the radial direction of the first magnets (14); a second coil (18) disposed around the outer side in the radial direction of the second magnets (15); a coil fixing member (16) for fixing the coils (17, 18); and a ferromagnetic outer plate (19) positioned on the outer side in the radial direction of the coils (17, 18).

Description

Surface Inspection Equipment

The present invention relates to a surface inspection device that inspects the surface of a sample such as a wafer.

In the manufacturing process of semiconductor devices, surface inspection equipment is used to check for the presence of foreign matter adhering to the surface of samples such as wafers and for the presence of surface defects. The surface inspection equipment irradiates the surface of a rotating, disk-shaped sample with laser light, and moves the sample in its radial direction to inspect the entire surface of the sample. If there is a foreign matter or defect on the surface of the sample, the laser light irradiated onto the sample will scatter. The surface inspection equipment detects foreign matter or defects by receiving this scattered light with a detection optical system, and identifies the position of the foreign matter or defect on the sample from the rotation angle and radial position of the sample.

In response to the miniaturization of semiconductor devices, surface inspection equipment is required to improve its detection sensitivity for foreign objects and defects. As a method of improving detection sensitivity, efforts are being made to shorten the wavelength of laser light. When the wavelength of laser light is shortened, the focal depth of the optical system becomes shallower. Therefore, if the height position (height position) of the sample surface fluctuates during inspection, the height position of the sample surface may deviate from the allowable focal range of the optical system, which may result in a decrease in detection sensitivity or a shift in the detection position.

In order to keep the height position of the sample surface within the allowable focus range of the optical system, a focus drive mechanism may be used that drives the sample in a focus direction perpendicular to the sample surface while rotating the sample, thereby correcting the height position of the sample with high precision. An electromagnetic drive system, for example, is used as such a focus drive mechanism, but with electromagnetic drive systems, there is a concern that the temperature around the sample increases due to heat generated when electricity is applied, which could affect the inspection accuracy. Therefore, there is a demand for the focus drive mechanism of surface inspection equipment to have high drive efficiency and be able to obtain a large drive force in the focus direction (focus drive force) with little power consumption.

An example of a conventional surface inspection device that drives a sample such as a wafer in the focus direction with high precision is described in Patent Document 1. The device described in Patent Document 1 is equipped with a θZ actuator, which includes a coil and magnets arranged in two tiers, upper and lower (Z direction), on the outer periphery of a yoke. The first magnets in the upper tier are arranged at equal pitches. The second magnets in the lower tier have the same pitch as the first magnets in the upper tier, but are arranged at a position shifted by half a pitch from the first magnets in the upper tier.

JP 2011-119320 A

In conventional surface inspection devices such as the device described in Patent Document 1, magnets are arranged at equal pitch in the circumferential direction (the direction of rotation of the sample), and it is difficult to increase the proportion of magnets in the circumferential direction to increase the magnetic field acting on the coil, which creates a problem in sufficiently increasing the focus driving force (driving force in the focus direction, which is the height direction).

The object of the present invention is to provide a surface inspection device that can achieve a large focus driving force with low power consumption.

The surface inspection device according to the present invention comprises a plate-shaped sample holding member capable of holding a sample, a spindle motor for rotating the sample holding member, a turntable fixed to the spindle motor and rotated by the action of the spindle motor, and a focus drive mechanism for displacing the sample holding member in a focus direction, which is a height direction, relative to the turntable. The focus drive mechanism is cylindrical with the rotation axis of the spindle motor as its central axis, and comprises a yoke fixed to the sample holding member, a plurality of first magnets fixed to the surface of the yoke at a first height position in the focus direction and magnetized in the radial direction of the yoke, a plurality of second magnets fixed to the surface of the yoke at a second height position different from the first height position in the focus direction and magnetized in the opposite polarity to the first magnet, a first coil arranged around the outer side of the first magnet in the radial direction, a second coil arranged around the outer side of the second magnet in the radial direction, a coil fixing member for fixing the first coil and the second coil, and a ferromagnetic outer plate located on the outer side of the first coil and the second coil in the radial direction.

The present invention provides a surface inspection device that can achieve a large focus driving force with low power consumption.

1 is a diagram showing a configuration of a surface inspection device according to a first embodiment of the present invention; FIG. 2 is an exploded view of a focus driving mechanism in the first embodiment. FIG. 2 is a diagram showing a part of a focus driving mechanism, a sample holding member, a spindle motor, and a turntable in the first embodiment. FIG. 2 is a cross-sectional view of the focus drive mechanism, the sample, the sample holding member, the spindle motor, and the turntable in the XZ plane in the first embodiment. FIG. 10 is a diagram showing a schematic example of a magnetic field acting on a coil in a conventional surface inspection device. 4 is a diagram showing a schematic diagram of a magnetic field acting on a coil in the surface inspection device according to the first embodiment; FIG. FIG. 11 is a cross-sectional view in the XZ plane showing a focus drive mechanism of a surface inspection apparatus according to a second embodiment of the present invention. 11 is a diagram showing a schematic diagram of a magnetic field acting on a coil in the surface inspection device according to the second embodiment. FIG. FIG. 11 is a cross-sectional view in the XZ plane showing a focus drive mechanism of a surface inspection apparatus according to a third embodiment of the present invention. FIG. 11 is an exploded view of a focus drive mechanism in a surface inspection apparatus according to a fourth embodiment of the present invention. FIG. 13 is a diagram showing a focus drive mechanism provided in a surface inspection apparatus according to a fifth embodiment of the present invention. 13 is a diagram showing a schematic diagram of a magnetic field acting on a coil in the surface inspection device according to the fifth embodiment. FIG.

The surface inspection device according to the present invention is a device that inspects the presence or absence of foreign matter adhering to the surface of a sample such as a wafer, and the presence or absence of surface defects. The surface inspection device according to the present invention has a magnetic field acting on a coil in a direction perpendicular or nearly perpendicular to the focus direction (height direction), and is equipped with an efficient magnetic circuit structure, so that it is possible to increase the focus driving force (driving force in the focus direction), and a large focus driving force can be obtained with low power consumption.

Below, a surface inspection device according to an embodiment of the present invention will be described with reference to the drawings. Note that in the drawings used in this specification, identical or corresponding components are given the same reference numerals, and repeated explanations of these components may be omitted.

This section describes a surface inspection device according to a first embodiment of the present invention.

FIG. 1 is a diagram showing the configuration of a surface inspection device 1 according to this embodiment. The surface inspection device 1 includes a sample holding member 3, a spindle motor 4, a frame 6, a turntable 5, a focus drive mechanism 11, a vertical drive stage 7, a horizontal drive stage 8, an illumination optical system 9, a detection optical system 10, and a sample height position sensor 30.

The sample holding member 3 is plate-shaped and can hold the sample 2. The sample 2 is, for example, a disk-shaped wafer. In the following description, the sample holding member 3 and the sample 2 are assumed to be disk-shaped.

In Figure 1, the height direction of the surface inspection device 1 (the up and down direction in Figure 1) is called the focus direction or Z direction, and the two directions perpendicular to the focus direction (horizontal directions) are called the X and Y directions. The focus direction (Z direction) is the direction perpendicular to the surface of the sample 2, and is also simply called the height direction. The direction around the focus direction (the rotation direction of the sample holding member 3 and sample 2) is called the circumferential direction, and the direction perpendicular to the focus direction (the radial direction of the sample holding member 3) is called the radial direction. The imaginary axes parallel to the X, Y, and Z directions are called the X, Y, and Z axes, respectively.

The spindle motor 4 is a motor for rotating the sample 2 and the sample holding member 3 around the Z axis, and is fixed to the frame 6.

The turntable 5 is fixed to one end of the spindle motor 4, and the sample holding member 3 is connected via a support member 12. The turntable 5 rotates around the Z axis by the action of the spindle motor 4. When the turntable 5 rotates, the sample holding member 3 connected to the turntable 5 and the sample 2 held by the sample holding member 3 rotate around the Z axis.

The focus drive mechanism 11 is a mechanism that displaces the sample holding member 3 and the sample 2 in the focus direction relative to the turntable 5. Details of the focus drive mechanism 11 will be described later.

The vertical drive stage 7 moves the frame 6 in the focus direction (Z direction) so that the position of the surface of the sample 2 falls within a predetermined height range. By moving the frame 6, the vertical drive stage 7 moves the spindle motor 4, turntable 5, sample holding member 3, and sample 2 in the focus direction.

The horizontal drive stage 8 moves the vertical drive stage 7 and frame 6 in the radial direction of the sample holding member 3 (the X direction in FIG. 1). By moving the vertical drive stage 7 and frame 6, the horizontal drive stage 8 moves the frame 6, spindle motor 4, turntable 5, sample holding member 3, and sample 2 in the radial direction of the sample holding member 3.

The illumination optical system 9 irradiates the surface of the sample 2 with laser light. If there is a foreign object or defect on the surface of the sample 2, the laser light irradiated onto the surface of the sample 2 is scattered there and becomes scattered light.

The detection optical system 10 receives the scattered light generated on the surface of the sample 2. A processing device (not shown) is connected to the detection optical system 10. This processing device detects the presence or absence of foreign matter or defects on the surface of the sample 2 from the signal of the scattered light received by the detection optical system 10, and identifies the position of the foreign matter or defect from the rotation angle and radial (X-direction) position of the sample holding member 3.

The sample height position sensor 30 is a sensor that detects the height position (position in the focus direction) of the surface of the sample 2. The sample height position sensor 30 can be configured, for example, as an optical or ultrasonic displacement sensor.

The surface inspection device 1 rotates the sample holding member 3 around the Z axis using the spindle motor 4 while moving the sample holding member 3 in the radial direction (X direction) using the horizontal drive stage 8, thereby scanning the entire surface of the sample 2 with laser light from the illumination optical system 9.

The vertical drive stage 7 is a mechanism that adjusts the average height position (position in the focus direction) of the surface of the sample 2. The speed at which the vertical drive stage 7 moves the frame 6 in the focus direction, i.e., the speed at which the sample holding member 3 moves in the focus direction by the vertical drive stage 7, is slow compared to the speed at which the sample holding member 3 is rotated by the spindle motor 4. Therefore, the movement of the sample 2 in the focus direction by the vertical drive stage 7 is not fast enough to correct the positional fluctuation of the sample 2 in the focus direction during rotation.

In order to inspect the sample 2 with high precision, it is necessary to adjust the height position of the surface of the sample 2 held by the sample holding member 3 in accordance with the positional fluctuation of the sample 2 in the focus direction while the sample 2 is rotating.

The surface inspection device 1 according to this embodiment is equipped with a focus drive mechanism 11 that displaces the sample holding member 3 and the sample 2 in the focus direction relative to the turntable 5, and the height position of the surface of the sample 2 during rotation can be adjusted by the focus drive mechanism 11. As shown in FIG. 1, the focus drive mechanism 11 is equipped with a coil fixing member 16 and an outer plate 19, which will be described later. The focus drive mechanism 11 will be described below.

FIG. 2 is an exploded view of the focus drive mechanism 11. FIG. 2 shows the focus drive mechanism 11, the sample holding member 3, the spindle motor 4, and the turntable 5. FIG. 2 also shows the central axis 20 of the sample holding member 3. The central axis 20 is parallel to the Z axis and coincides with the rotation axis of the spindle motor 4.

The focus drive mechanism 11 includes a support member 12, a yoke 13, a plurality of first magnets 14, a plurality of second magnets 15, a first coil 17, a second coil 18, a coil fixing member 16, and an outer plate 19.

FIG. 3 shows a part of the focus drive mechanism 11, the sample holding member 3, the spindle motor 4, and the turntable 5. FIG. 3 also shows the support member 12, yoke 13, first magnet 14, second magnet 15, first coil 17, and second coil 18 of the focus drive mechanism 11.

FIG. 4 is a cross-sectional view of the focus drive mechanism 11, the sample 2, the sample holding member 3, the spindle motor 4, and the turntable 5 in the XZ plane.

The support member 12 is an annular member provided between the sample holding member 3 and the turntable 5, with one surface in the focus direction fixed to the sample holding member 3 at multiple points and the other surface fixed to the turntable 5 at multiple points. The support member 12 is made of an elastic body such as metal, and supports the sample holding member 3 and the sample 2 fixed to the sample holding member 3 so that they can be displaced in the focus direction relative to the turntable 5.

The yoke 13 has a cylindrical shape with the rotation shaft of the spindle motor 4 (i.e., the central axis 20) as its central axis, and as shown in FIG. 2, includes a cylindrical portion 13b and a yoke mounting portion 13a located at the top of the cylindrical portion 13b. The cylindrical portion 13b is cylindrical with the central axis 20 as its center. The yoke mounting portion 13a extends upward from the cylindrical portion 13b and passes through an opening provided in the turntable 5, and is fixed to the sample holding member 3. Note that FIG. 2 shows a configuration in which the yoke 13 has four yoke mounting portions 13a as an example, but the number of yoke mounting portions 13a can be determined arbitrarily.

The first magnet 14 has an arc shape when viewed from the focusing direction, i.e., a shape curved along the circumferential direction, and is fixed to the surface of the cylindrical portion 13b of the yoke 13 at a first height position in the focusing direction. The multiple first magnets 14 are arranged at intervals from each other along the circumferential direction. The first magnets 14 are magnetized in the radial direction of the cylindrical portion 13b of the yoke 13. In this embodiment, the surface of the first magnet 14 that contacts the yoke 13 is an S pole, and the surface opposite to the surface that contacts the yoke 13 is an N pole. The radial direction of the cylindrical portion 13b is the same as the radial direction of the sample holding member 3.

The second magnet 15 has an arc shape when viewed from the focus direction, i.e., a shape curved along the circumferential direction, and is fixed to the surface of the cylindrical portion 13b of the yoke 13 at a second height position in the focus direction. The second height position is different from the first height position in the focus direction. The multiple second magnets 15 are arranged at intervals from each other along the circumferential direction. The second magnets 15 are magnetized in the radial direction of the cylindrical portion 13b of the yoke 13 in the opposite polarity to that of the first magnet 14. That is, in this embodiment, the surface of the second magnet 15 that contacts the yoke 13 is the north pole, and the surface opposite the surface that contacts the yoke 13 is the south pole.

In this embodiment, as an example, the multiple first magnets 14 are positioned above the multiple second magnets 15 (at the top in the focus direction). In other words, the first height position in the focus direction is higher than the second height position in the focus direction.

The first magnet 14 and the second magnet 15 are fixed to the cylindrical portion 13b of the yoke 13.

The first magnet 14 and the second magnet 15 are preferably positioned so that they at least partially overlap each other when viewed from the focus direction (i.e., at least partially in the same position in the circumferential direction of the yoke 13). If the first magnet 14 and the second magnet 15 are positioned in this way, the magnetic field is prevented from spreading in a direction perpendicular to the focus direction (horizontal direction), and the magnetic field acting on the first coil 17 and the second coil 18 in a direction oblique to the focus direction can be reduced, thereby increasing the focus driving force, which is the driving force in the focus direction. It is even more preferable that the first magnet 14 and the second magnet 15 are positioned so that they entirely overlap each other when viewed from the focus direction (i.e., entirely in the same position in the circumferential direction of the yoke 13).

Furthermore, it is preferable that the first magnet 14 and the second magnet 15 have the same length in the focusing direction. Furthermore, it is preferable that the first magnet 14 and the second magnet 15 are arranged in contact with each other in the focusing direction.

In the examples shown in Figures 2 and 3, the number of first magnets 14 and second magnets 15 is equal to four, but this is not limited to this and can be determined arbitrarily. In addition, the polarity of the first magnets 14 and second magnets 15 may be reversed from that shown in the examples shown in Figures 2 and 3.

In this embodiment, the first magnet 14 and the second magnet 15, which has a polarity different from that of the first magnet 14, are installed on the yoke 13 in a position where they overlap when viewed from the focus direction. Therefore, a magnetic path can be formed by the magnets 14 and 15 installed above and below in the focus direction, so the first magnet 14 and the second magnet 15 can be stably installed on the yoke 13.

Furthermore, the spacing between the first magnets 14 in the circumferential direction can be made smaller than the length of the first magnets 14 in the circumferential direction, as long as it is within a range in which there is no repulsion between adjacent magnets in the circumferential direction. Similarly, the spacing between the second magnets 15 in the circumferential direction can be made smaller than the length of the second magnets 15 in the circumferential direction. For this reason, the surface inspection device 1 according to this embodiment has a high ratio of magnets to the circumferential length of the yoke 13, and this also makes it possible to increase the focus driving force, which is the driving force in the focus direction, and to obtain a large focus driving force with low power consumption.

The first coil 17 is annular, arranged around the radially outer periphery of the first magnet 14, and fixed to the coil fixing member 16.

The second coil 18 is annular, arranged around the radially outer periphery of the second magnet 15, and fixed to the coil fixing member 16.

Note that FIG. 4 shows a first coil 17 and a second coil 18 that are annular and extend in the circumferential direction.

The coil fixing member 16 is an annular member made of a non-magnetic material and is fixed to the frame 6 (Figure 1). The coil fixing member 16 is located on the outer periphery of the first coil 17 and the second coil 18, and fixes the first coil 17 and the second coil 18.

The outer plate 19 is a cylindrical member made of a ferromagnetic material, and is installed on the outer peripheral surface of the coil fixing member 16. The outer plate 19 is located radially outside the first coil 17 and the second coil 18. In other words, in the radial direction, the outer plate 19 is located at the outermost periphery, the first coil 17 is between the outer plate 19 and the first magnet 14, and the second coil 18 is between the outer plate 19 and the second magnet 15.

It is preferable that the center position of the outer plate 19 in the focus direction is the same as the center position of the first magnet 14 and the second magnet 15 in the overall focus direction.

When a current flows through the first coil 17, an electromagnetic force acts on the first coil 17 and the first magnet 14 due to the interaction between this current and the magnetic field from the first magnet 14. When a current flows through the second coil 18 in the opposite direction to the current flowing through the first coil 17, an electromagnetic force acts on the second coil 18 and the second magnet 15 due to the interaction between the current flowing through the second coil 18 and the magnetic field from the second magnet 15. The direction of this electromagnetic force is the same as the direction of the electromagnetic force acting on the first coil 17 and the first magnet 14.

The first coil 17 and the second coil 18 are fixed to a coil fixing member 16 that is fixed to the frame 6, so the displacement in the focus direction caused by the electromagnetic force is small enough to be negligible. In other words, it is considered that the first coil 17 and the second coil 18 do not move in the focus direction even if an electromagnetic force acts on them.

On the other hand, when an electromagnetic force acts on the first magnet 14 and the second magnet 15, they move in the focus direction. Therefore, due to the electromagnetic force acting on the first magnet 14 and the second magnet 15, the first magnet 14, the second magnet 15, the yoke 13, the sample holding member 3, and the sample 2 are displaced in the focus direction as a single movable part.

In this way, the surface inspection device 1 according to this embodiment can rotate the sample holding member 3 and the sample 2 with the spindle motor 4 while driving and displacing the sample holding member 3 and the sample 2 in the focus direction with the focus drive mechanism 11.

The method for adjusting the height position (position in the focus direction) of the sample 2 will now be described. In the surface inspection device 1, the focus drive mechanism 11 drives the sample holding member 3 and the sample 2 in the focus direction based on the height position of the surface of the sample 2 detected by the sample height position sensor 30 (Figure 1), and adjusts the height position of the surface of the sample 2 so that it falls within the allowable focus range of the detection optical system 10. In this way, the surface inspection device 1 can adjust the height position of the sample 2 during rotation.

The following explains how the surface inspection device 1 of this embodiment can increase the focus drive force by providing an outer plate 19.

FIG. 5 is a schematic diagram showing an example of the magnetic field acting on a coil in a conventional surface inspection device. The conventional surface inspection device does not have the outer plate 19 that is provided in the surface inspection device 1 of this embodiment. Note that, for ease of understanding, FIG. 5 only shows cross sections in the XZ plane of the yoke 13, first magnet 14, second magnet 15, coil fixing member 16, first coil 17, and second coil 18.

As shown in Figure 5, in a conventional surface inspection device, the magnetic field 31 from the north pole on the surface of the first magnet 14 spreads outward in the vertical direction (Z direction) while moving radially outward (X direction in Figure 5) and converges on the south pole on the surface of the second magnet 15. The magnetic field that passes through the inside of the second magnet 15 passes through the inside of the yoke 13 from the north pole on the back surface of the second magnet 15 and returns to the first magnet 14. At this time, the magnetic field acting on the first coil 17 and second coil 18 is oblique to the focus direction (Z direction).

Electromagnetic force is generated perpendicular to the direction of the magnetic field. For this reason, in conventional surface inspection devices, the electromagnetic force generated is a force in a direction inclined to the Z direction. In surface inspection devices, the effective focus driving force is a component in the Z direction. Therefore, in conventional surface inspection devices, electromagnetic force is generated at an angle to the Z direction, and sufficient effective focus driving force cannot be obtained, making it difficult to obtain a large focus driving force with low power consumption.

FIG. 6 is a schematic diagram showing the magnetic field acting on the coil in the surface inspection device 1 according to this embodiment. The surface inspection device 1 according to this embodiment is equipped with an outer plate 19. Note that, for ease of understanding, FIG. 6 only shows cross sections in the XZ plane of the yoke 13, first magnet 14, second magnet 15, coil fixing member 16, first coil 17, second coil 18, and outer plate 19.

As shown in FIG. 6, in the surface inspection device 1 according to this embodiment, the magnetic field 32 from the north pole on the surface of the first magnet 14 is directed toward the surface of the outer plate 19 in the area facing the first magnet 14, so that the magnetic field 32 can be prevented from spreading in the vertical direction (Z direction). The magnetic field 32 directed toward the outer plate 19 passes through the inside of the outer plate 19, and then from the surface of the area of the outer plate 19 facing the second magnet 15, toward the south pole on the surface of the second magnet 15. At this time, the magnetic field 32 acting on the first coil 17 and the second coil 18 is in the horizontal direction (i.e., perpendicular to the focus direction) or close to the horizontal direction.

In this way, the surface inspection device 1 according to this embodiment can improve the efficiency of the magnetic circuit, and the generated electromagnetic force is parallel or nearly parallel to the Z direction. Therefore, the surface inspection device 1 according to this embodiment can increase the effective focus driving force, which is the component parallel to the Z direction, and can reduce the power consumption when the focus driving mechanism 11 drives the sample holding member 3 and sample 2 in the focus direction.

Also, because the outer plate 19 is cylindrical, the circumferential distribution of the magnetic field 32 acting on the first coil 17 and the second coil 18 can be made symmetrical with respect to the central axis 20. This allows the center of action of the focus driving force to coincide with the central axis 20, and suppresses tilt and vibration that occurs in the sample holding member 3 and the sample 2 when the focus driving mechanism 11 drives the sample holding member 3 and the sample 2 in the focus direction.

Furthermore, in the surface inspection device 1 according to this embodiment, the outer plate 19 can make the direction of the magnetic field 32 acting on the first coil 17 and the second coil 18 horizontal or close to horizontal, so that the focus drive mechanism 11 can drive the sample holding member 3 and the sample 2 in a direction closer to the focus direction. If the focus drive mechanism 11 drives the sample holding member 3 and the sample 2 in a direction oblique to the focus direction, the sample holding member 3 and the sample 2 will be displaced obliquely to the focus direction. The surface inspection device 1 according to this embodiment can prevent the sample holding member 3 and the sample 2 from being displaced obliquely to the focus direction, so it is possible to reduce power consumption when the focus drive mechanism 11 drives the sample holding member 3 and the sample 2 in the focus direction.

As described above, the surface inspection device 1 according to this embodiment can improve the efficiency of the magnetic circuit, and can obtain a large focus driving force with low power consumption.

A surface inspection device according to a second embodiment of the present invention will be described. Below, the differences between the surface inspection device 1 according to the second embodiment and the surface inspection device 1 according to the first embodiment will be mainly described.

Figure 7 is a cross-sectional view in the XZ plane showing the focus drive mechanism 11 of the surface inspection device 1 according to this embodiment. Figure 7 shows the yoke 13, first magnet 14, second magnet 15, coil fixing member 16, first coil 17, second coil 18, and outer plate 19 of the focus drive mechanism 11.

In the surface inspection device 1 according to this embodiment, the length Hp of the outer plate 19 in the focus direction (Z direction) is smaller than the total length Hm of the first magnet 14 and the second magnet 15 in the focus direction.

FIG. 8 is a schematic diagram showing the magnetic field acting on the coil in the surface inspection device 1 according to this embodiment. For ease of understanding, FIG. 8 shows cross sections in the XZ plane of the yoke 13, first magnet 14, second magnet 15, coil fixing member 16, first coil 17, second coil 18, and outer plate 19.

As shown in FIG. 8, the magnetic field 32 from the N pole on the surface of the first magnet 14 heads toward the surface of the outer plate 19 in the area facing the first magnet 14, passes through the inside of the outer plate 19, and heads from the surface of the area facing the second magnet 15 of the outer plate 19 toward the S pole on the surface of the second magnet 15. In the surface inspection device 1 according to this embodiment, the length Hp of the outer plate 19 in the focus direction is smaller than the total length Hm of the first magnet 14 and the second magnet 15 in the focus direction. Therefore, the magnetic field 32 from near the upper end of the first magnet 14 heads toward the upper end of the outer plate 19 without spreading upward, and the magnetic field 32 from near the lower end of the outer plate 19 heads toward the second magnet 15 without spreading downward. Because the length Hp is smaller than the length Hm, the magnetic field 32 does not spread in the vertical direction, but acts on the first coil 17 and the second coil 18 in the horizontal direction or a direction close to the horizontal direction.

The length Hp of the outer plate 19 in the focus direction may be equal to the total length Hm of the first magnet 14 and the second magnet 15 in the focus direction. Even if the length Hp is equal to the length Hm, the magnetic field 32 can be applied to the first coil 17 and the second coil 18 in a horizontal direction or a direction close to the horizontal direction.

With this configuration, in the surface inspection device 1 according to this embodiment, the magnetic field 32 acting on the first coil 17 and the second coil 18 can be made even closer to the horizontal direction. As a result, in the surface inspection device 1 according to this embodiment, the effective focus driving force, which is the component parallel to the Z direction, can be further increased, and an even larger focus driving force can be obtained with low power consumption.

A surface inspection device according to a third embodiment of the present invention will be described. Below, the differences between the surface inspection device 1 according to this embodiment and the surface inspection device 1 according to the first and second embodiments will be mainly described.

Figure 9 is a cross-sectional view in the XZ plane showing the focus drive mechanism 11 of the surface inspection device 1 according to this embodiment. Figure 9 shows the yoke 13, first magnet 14, second magnet 15, coil fixing member 16, first coil 17, second coil 18, and outer plate 19 of the focus drive mechanism 11.

In the surface inspection device 1 according to this embodiment, the thickness tc of the central portion of the outer plate 19 in the focus direction (Z direction) is greater than the thickness te of the upper end portion and the thickness te of the lower end portion of the outer plate 19 in the focus direction. Preferably, the thickness of the outer plate 19 becomes monotonically smaller from the central portion toward the upper end portion and the lower end portion in the focus direction.

The shape of the outer peripheral surface of the outer plate 19 can be determined arbitrarily. For example, the shape of the outer peripheral surface of the outer plate 19 in the XZ cross section shown in FIG. 9 can be a trapezoid, an arc shape, a triangle, or the like.

In this embodiment, the thickness of the upper end and the thickness of the lower end of the outer plate 19 in the focus direction are equal to each other, but the thickness of the upper end and the thickness of the lower end may be different from each other.

The magnetic flux passing through the outer plate 19 is greater in the center in the focus direction and less at the upper and lower ends. Therefore, by making the thickness tc of the center of the outer plate 19 in the focus direction greater than the thickness te of the upper and lower ends, it is possible to reduce the magnetic flux leaking from the inside of the outer plate 19 to the outside.

With this configuration, the surface inspection device 1 according to this embodiment can increase the amount of magnetic flux flowing from the first magnet 14 to the outer plate 19 and from the outer plate 19 to the second magnet 15. As a result, the surface inspection device 1 according to this embodiment can further increase the effective focus driving force, which is the component parallel to the Z direction, and can obtain an even larger focus driving force with low power consumption.

In addition, in the surface inspection device 1 according to this embodiment, the thickness of the upper and lower ends of the outer plate 19, which have little effect on the amount of magnetic flux passing through the inside of the outer plate 19, can be reduced, making the outer plate 19 lighter, and also reducing the power consumption required to drive the vertical drive stage 7 and the horizontal drive stage 8.

A surface inspection device according to a fourth embodiment of the present invention will be described. Below, the differences between the surface inspection device 1 according to this embodiment and the surface inspection device 1 according to the first to third embodiments will be mainly described.

FIG. 10 is an exploded view of the focus drive mechanism 11 in the surface inspection device 1 according to this embodiment. FIG. 10 shows the focus drive mechanism 11, the sample holding member 3, the spindle motor 4, and the turntable 5. FIG. 10 also shows the central axis 20 of the sample holding member 3.

In the surface inspection device 1 according to this embodiment, the outer plate 19 is divided in the circumferential direction on the outer peripheral surface of the coil fixing member 16. That is, the outer plate 19 comprises a plurality of partial outer plates 19a, 19b. When viewed from the focus direction, the partial outer plates 19a, 19b have an arc shape, that is, a shape that curves along the circumferential direction. The multiple partial outer plates 19a, 19b are arranged so as to be lined up with each other along the circumferential direction on the outer peripheral surface of the coil fixing member 16.

In the surface inspection device 1 according to this embodiment, the outer plate 19 is divided in the circumferential direction, so that the outer plate 19 can be easily attached to the coil fixing member 16. Furthermore, the outer plate 19 can be attached to the coil fixing member 16 so that there is no gap between the outer circumferential surface of the coil fixing member 16.

In the surface inspection device 1 according to this embodiment, the gap between the outer plate 19 and the outer peripheral surface of the coil fixing member 16 is eliminated, and the distance between the outer plate 19 and the magnets 14 and 15 can be reduced, thereby increasing the focus driving force. Furthermore, by eliminating the gap between the outer plate 19 and the outer peripheral surface of the coil fixing member 16, the distance from the first magnet 14 and the second magnet 15 to the outer plate 19 can be made constant over the entire circumferential direction, and the circumferential distribution of the magnetic field acting on the first coil 17 and the second coil 18 can be made symmetrical with respect to the central axis 20.

For example, if the outer plate 19 is cylindrical as described in Example 1, the circumferential distribution of the magnetic field 32 acting on the first coil 17 and the second coil 18 can be easily made symmetrical with respect to the central axis 20. However, in reality, if the outer plate 19 is cylindrical, there is a possibility that a gap will be formed between the outer plate 19 and the outer peripheral surface of the coil fixing member 16 when the outer plate 19 is attached to the coil fixing member 16.

In the surface inspection device 1 according to this embodiment, the outer plate 19 is divided in the circumferential direction, so that the outer plate 19 can be easily attached to the coil fixing member 16 without leaving any gaps between the outer plate 19 and the outer peripheral surface of the coil fixing member 16.

Note that FIG. 10 shows, as an example, an example in which the outer plate 19 is divided into two in the circumferential direction (i.e., the outer plate 19 has two partial outer plates 19a, 19b). The number of divisions of the outer plate 19 is not limited to two and can be determined arbitrarily.

A surface inspection device according to a fifth embodiment of the present invention will be described. Below, the differences between the surface inspection device 1 according to this embodiment and the surface inspection device 1 according to the first to fourth embodiments will be mainly described.

FIG. 11 is a diagram showing the focus drive mechanism 11 provided in the surface inspection device 1 according to this embodiment.

In the surface inspection device 1 according to this embodiment, the focus drive mechanism 11 includes a third magnet 21, a fourth magnet 22, and magnet holding members 23 and 24 that hold these magnets. For ease of understanding, FIG. 11 shows only the coil fixing member 16, the outer plate 19, the third magnet 21, the fourth magnet 22, and the magnet holding members 23 and 24 of the focus drive mechanism 11.

The third magnet 21 is an annular magnet for adjusting the direction of the magnetic field acting on the first coil 17. The fourth magnet 22 is an annular magnet for adjusting the direction of the magnetic field acting on the second coil 18.

In this embodiment, the focus drive mechanism 11 includes a third magnet 21 located above an outer plate 19 that is installed on the outer peripheral surface of the coil fixing member 16, and a fourth magnet 22 located below the outer plate 19. The third magnet 21 is attached to a magnet holding member 23. The fourth magnet 22 is attached to a magnet holding member 24. The magnet holding members 23 and 24 are fixed to the frame 6 (Figure 1). For example, the magnet holding member 23 can be fixed to the frame 6 using a connecting member or the like.

FIG. 12 is a schematic diagram showing the magnetic field acting on the coil in the surface inspection device 1 according to this embodiment. For ease of understanding, FIG. 12 shows cross sections in the XZ plane of the yoke 13, first magnet 14, second magnet 15, coil fixing member 16, first coil 17, second coil 18, outer plate 19, third magnet 21, fourth magnet 22, and magnet holding members 23 and 24.

The third magnet 21 and the fourth magnet 22 are magnetized in the focus direction (Z direction).

The polarity of the third magnet 21 on its surface closest to the outer plate 19 (lower surface) is the same north pole as the polarity of the surface facing the first coil 17 of the first magnet 14 (surface closest to the outer plate 19), and the polarity of the surface closest to the magnet holding member 23 (upper surface) is a south pole.

The polarity of the fourth magnet 22 on its surface (upper surface) closest to the outer plate 19 is the same S pole as the polarity of the surface (surface closest to the outer plate 19) facing the second coil 18 of the second magnet 15, and the polarity of the surface (lower surface) closest to the magnet holding member 24 is the N pole.

In this way, in the surface inspection device 1 according to this embodiment, the polarity of the surface of the third magnet 21 close to the outer plate 19 is the same as the polarity of the surface of the first magnet 14 close to the outer plate 19. Therefore, the magnetic field from near the upper end of the first magnet 14 to near the upper end of the outer plate 19 and the magnetic field from the third magnet 21 to the upper end of the outer plate 19 repel each other. In addition, the polarity of the surface of the fourth magnet 22 close to the outer plate 19 is the same as the polarity of the surface of the second magnet 15 close to the outer plate 19. Therefore, the magnetic field from near the lower end of the outer plate 19 to near the lower end of the second magnet 15 and the magnetic field from the lower end of the outer plate 19 to the fourth magnet 22 repel each other.

With this configuration, in the surface inspection device 1 according to this embodiment, the magnetic field 32 acting on the first coil 17 and the second coil 18 can be made even closer to the horizontal direction. As a result, in the surface inspection device 1 according to this embodiment, the effective focus driving force, which is the component parallel to the Z direction, can be further increased, and an even larger focus driving force can be obtained with low power consumption.

In addition, because the third magnet 21 and the fourth magnet 22 are annular, the circumferential distribution of the magnetic field acting on the first coil 17 and the second coil 18 can be kept symmetrical with respect to the central axis 20. This allows the center of action of the focus driving force to coincide with the central axis 20, suppressing tilt and vibration during focus driving.

As described above, the surface inspection device 1 according to this embodiment can obtain a large focus driving force with low power consumption. Note that the present invention is not limited to the above embodiment, and various modifications are possible. For example, the above embodiment has been described in detail to easily explain the present invention, and the present invention is not necessarily limited to an embodiment having all of the configurations described. It is also possible to replace a part of the configuration of one embodiment with the configuration of another embodiment. It is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to delete a part of the configuration of each embodiment, or to add or replace another configuration.

　1...surface inspection device, 2...sample, 3...sample holding member, 4...spindle motor, 5...turntable, 6...frame, 7...vertical drive stage, 8...horizontal drive stage, 9...illumination optical system, 10...detection optical system, 11...focus drive mechanism, 12...support member, 13...yoke, 13a...yoke mounting portion, 13b...cylindrical portion, 14...first magnet, 15...second magnet, 16...coil fixing member, 17...first coil, 18...second coil, 19...outer plate, 19a, 19b...partial outer plate, 20...center axis, 21...third magnet, 22...fourth magnet, 23, 24...magnet holding member, 30...sample height position sensor, 31, 32...magnetic field.

Claims (9)

A plate-shaped sample holding member capable of holding a sample;
A spindle motor for rotating the sample holding member;
a turntable fixed to the spindle motor and rotated by the action of the spindle motor;
a focus driving mechanism that displaces the sample holding member in a focus direction, which is a height direction relative to the turntable;
Equipped with
The focus drive mechanism includes:
a yoke having a cylindrical shape with the rotation shaft of the spindle motor as a central axis and fixed to the sample holding member;
a plurality of first magnets fixed to a surface of the yoke at a first height position in the focusing direction and magnetized in a radial direction of the yoke;
a plurality of second magnets fixed to a surface of the yoke at a second height position different from the first height position in the focus direction, the second magnets being magnetized in a direction opposite to the polarity of the first magnets;
A first coil disposed around the radially outer periphery of the first magnet;
A second coil disposed around the outer periphery of the second magnet in the radial direction;
a coil fixing member that fixes the first coil and the second coil;
an outer plate made of a ferromagnetic material positioned radially outward of the first coil and the second coil;
Equipped with
A surface inspection device characterized by: The outer plate is installed on the outer peripheral surface of the coil fixing member and has a cylindrical shape.
The surface inspection apparatus according to claim 1 . the outer plate has a length in the focusing direction that is smaller than a total length of the first magnet and the second magnet in the focusing direction;
The surface inspection apparatus according to claim 1 . a thickness of a central portion of the outer plate in the focus direction is greater than thicknesses of an upper end portion and a lower end portion of the outer plate in the focus direction;
The surface inspection apparatus according to claim 1 . The outer plate is divided in a circumferential direction on the outer circumferential surface of the coil fixing member.
The surface inspection apparatus according to claim 2. the first magnets are located above the second magnets,
The focus drive mechanism includes:
a third magnet located above the outer plate and magnetized in the focusing direction;
a fourth magnet located below the outer plate and magnetized in the focusing direction,
the third magnet has a surface close to the outer plate that has the same polarity as a surface of the first magnet that is close to the outer plate;
The polarity of the fourth magnet on a surface close to the outer plate is the same as the polarity of the second magnet on a surface close to the outer plate.
The surface inspection apparatus according to claim 1 . The third magnet and the fourth magnet are annular.
The surface inspection apparatus according to claim 6. The first magnets and the second magnets are positioned so as to at least partially overlap each other when viewed from the focusing direction.
The surface inspection apparatus according to claim 1 . A center position of the outer plate in the focus direction is the same as a center position of the first magnet and the second magnet in the focus direction.
The surface inspection apparatus according to claim 1 .

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