Patent ID: 12222303

REFERENCE SIGNS LIST

S: sample, P: measurement position,10: goniometer,11: rotation arm,12: first arm member,13: second arm member,14: third arm member,12a,13a: guide rail,15: lower holding member,16: upper holding member,17: support member,20: X-ray irradiation unit,21: X-ray tube,22: focusing mirror,23: aperture,24: guard slit,25: slit,30: two-dimensional X-ray detector,31: direct beam stopper,32: vacuum path,35: optical microscope,36: laser inclination measuring device,36a: laser light source,36b: laser detector,37: moving table,40: sample stage,41: frame body,42: sample holder,43: cavity,50: base frame,51: X-axis moving frame,52: X-axis rotating table,52a: bearing,53: Y-axis moving table,54: Z-axis driving table,55: Z-axis moving table,56: sample holding frame,57: X-ray transmission hole,58: suction support piece,59: vacuum nozzle,60: rotation guide portion,61: rotation support portion,62: support roller,63: driven-side pulley,64: in-plane rotation drive motor,65: drive-side pulley,66: drive belt,67: X-axis drive motor,68: ball screw,69: screw shaft,70: nut member,71: guide rail,72: slider,73: bearing,74: swing support shaft,75: Y-axis drive motor,76: ball screw,77: screw shaft,78: bearing,79: nut member,80: Z-axis drive motor,81: guide member,82: sliding member,83: guide rail,84: slider,85: X-axis drive motor,86: driving force transmission belt,87: worm,88: worm wheel,89: drive-side pulley,90: driven-side pulley,91: guide rail,92: slider,93: guide rail,94: slider,95: ball screw,96: nut member,100: central processing unit,101: X-ray irradiation controller,102: image recognition circuit,103: focus controller,104: positioning controller,105: goniometer controller,106: storage unit,107: detection control circuit,110: sample positioning mechanism,200: external housing,201: housing main body,202,203: housing element member,210,211: guide rail,220: shielding panel,300: fan filter unit,310: substrate feeding device (EFEM),320: electrical component portion

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[Overview]

First, an outline of a transmission type small-angle scattering device according to an embodiment of the present invention will be described.

When a sample is irradiated with an X-ray beam, X-rays are scattered in a small angle region (small angle region) near a traveling direction of the X-ray beam. This scattering is called small-angle scattering, and a particle size, a periodic structure, etc. relating to a substance can be known by measuring the small-angle scattering. Further, in recent years, development of an analysis method for obtaining various information on thin films forming semiconductor devices by this small-angle scattering measurement has been promoted.

A device for measuring this small-angle scattering is a small-angle scattering device.

As the small-angle scattering device are known a reflection type small-angle scattering device for irradiating the surface of a sample with X-rays and detecting scatter X-rays reflected from the surface of the sample, and a transmission type small-angle scattering device for irradiating the back surface of a sample with X-rays and detecting scatter X-rays emitted from the front surface of the sample.

The present invention relates to a transmission type small-angle scattering device. This transmission type small-angle scattering device has a basic structure in which an X-ray source and a two-dimensional X-ray detector are arranged so as to face each other with interposing a sample therebetween, the back surface of the sample is irradiated with X-rays from the X-ray source, and scatter X-rays radiated from the front surface of the sample at a specific angle are detected by a two-dimensional X-ray detector.

Conventionally, a general small-angle scattering device has a horizontal layout structure in which an X-ray source and a two-dimensional X-ray detector are horizontally arranged, so that it needs a large installation area.

On the other hand, the transmission type small-angle scattering device according to the present embodiment can be installed on a floor surface having a limited area in a clean room where a semiconductor manufacturing line is constructed, so that the transmission type small-angle scattering device has a vertical layout structure in which the X-ray source and the two-dimensional X-rays detector are arranged vertically.

[Overall Structure]

FIG.1Ais a side configuration diagram schematically showing the overall structure of the transmission type small-angle scattering device according to the embodiment of the present invention, andFIG.1Bis also a front configuration diagram.FIGS.2and3are perspective views of the appearance of the transmission type small-angle scattering device when viewed from different directions.

The transmission type small-angle scattering device according to the present embodiment includes a goniometer10. The goniometer10has a function of rotationally driving a rotation arm11around a θ-axis extending in a horizontal direction. The rotation arm11includes an X-ray irradiation unit20and a two-dimensional X-ray detector30which are installed at both end portions thereof. Here, a vertical arrangement state in which the rotation arm11is vertically arranged is defined as an origin. The X-ray irradiation unit20is installed at a lower end portion, and the two-dimensional X-ray detector30is installed at an upper end portion. Such a vertical arrangement structure enables the transmission type small-angle scattering device to be installed even on a floor surface having a relatively small area.

The X-ray irradiation unit20and the two-dimensional X-ray detector30are arranged so as to face each other with interposing a sample stage40therebetween, and configured so that the X-ray irradiation unit20irradiates a sample S supported by a sample holder42of the sample stage40with X-rays from the lower side of the sample S, and the two-dimensional X-ray detector30detects scatter X-rays generated in a minute angle region around the X-rays transmitted through the sample S.

Here, as shown inFIGS.1A and1B, a cavity43through which X-rays emitted from the X-ray irradiation unit20is transmitted is formed in the sample stage40, and the back surface of the sample S is irradiated with X-rays through this cavity43.

A cylindrical vacuum path32is installed in the rotation arm11of the goniometer10. The vacuum path32has a function of eliminating air scattering occurring when X-rays transmitted through the sample S collide with air, thereby improving the measurement accuracy of small-angle scattering.

The sample stage40is configured so that it is driven by a sample positioning mechanism described later to move the sample holder42in a longitudinal direction (Y direction) and a lateral direction (X direction) parallel to the horizontal plane, and in a vertical direction (Z direction) perpendicular to the horizontal plane respectively, thereby positioning an inspection target point of the sample S at a measurement position P of the transmission type small-angle scattering device.

Further, the sample positioning mechanism has a function of causing the sample S supported by the sample holder42to perform in-plane rotation (φ-rotation). The sample positioning mechanism has also a function of causing the sample S supported by the sample holder42to swing around the χ-axis (χ-swing). This χ-axis intersects the θ-axis of the goniometer10at right angles in the horizontal plane. The intersection between the θ-axis and the χ-axis is positioned so as to match the measurement position P of the transmission type small-angle scattering device.

The sample stage40is supported by the frame body41as shown inFIGS.2and3. The frame body41and the rotation arm11of the goniometer10are adjusted in mutual positional relation so as not to interfere with each other.

Further, the transmission type small-angle scattering device according to the present embodiment includes an optical microscope35for recognizing the surface of the sample S. The optical microscope35is installed at a position where it does not interfere with surrounding components such as parts driven by the sample positioning mechanism, the X-ray irradiation unit20and the two-dimensional X-ray detector30to be rotated by the goniometer10.

The sample S can be moved to a lower position of the optical microscope35by the sample positioning mechanism.

[Rotation Arm of Goniometer and Components to be Installed in the Same Arm]

Next, the detailed configurations of the rotation arm of the goniometer and respective components to be installed in the rotation arm will be described mainly with reference toFIGS.4and5.

FIG.4is a perspective view showing the appearance of the rotation arm of the goniometer constituting the transmission type small-angle scattering device according to the present embodiment and the components to be installed in the rotation arm.FIG.5is a perspective view showing a state in which the rotation arm of the goniometer shown inFIG.4is folded to shorten the total length.

The rotation arm11of the goniometer10includes a plurality of arm members. The rotation arm11of the present embodiment shown inFIGS.4and5includes first, second, and third arm members12,13, and14, and the first arm member12is fixed to a θ-rotation shaft (θ-axis inFIG.1A) of the goniometer10.

The rotation arm11of the goniometer10is configured so that the second arm member13slides in the longitudinal direction with respect to the first arm member12, and the third arm member14slides in the longitudinal direction with respect to the second arm member13, whereby the arm members12,13and14are overlapped with and fitted to one another, whereby they are set to folded up as shown inFIG.5.

By folding up the respective arm members12,13and14as described above, the total length can be shortened and the rotation arm11can be arranged in a compact form.

By arranging the rotation arm11in the compact form shown inFIG.5, a transportation work and an installation work on site can be extremely easily performed, and it is possible to realize shortening of work times required for these works and reduction of labors required for these works.

Specifically, a guide rail12ais provided in the longitudinal direction on the surface of the first arm member12, and the second arm member13is freely slidable along the guide rail12a. Likewise, a guide rail13ais provided in the longitudinal direction on the surface of the second arm member13, and the third arm member14is freely slidable along the guide rail13a.

The rotation arm11is provided with a lock mechanism (not shown) for keeping each of a state in which the respective arm members12,13, and14are unfolded to extend the total length as shown inFIG.4and a state in which the respective arm members12,13, and14are folded up to shorten the total length as shown inFIG.5.

A lower holding member15for installing the X-ray irradiation unit20is provided at a lower end portion of the first arm member12. The X-ray irradiation unit20is fixed to the lower holding member15. The lower holding member15is incorporated with a slide mechanism (not shown) for moving and adjusting the fixed position of the X-ray irradiation unit20in the longitudinal direction.

Further, an upper holding member16for installing the two-dimensional X-ray detector30is provided at an upper end portion of the third arm member14. The two-dimensional X-ray detector30is fixed to the upper holding member16. The upper holding member16is also incorporated with a slide mechanism (not shown) for moving and adjusting the fixed position of the two-dimensional X-ray detector30in the longitudinal direction.

When installing the device on site, it is possible to install the device according to a preset specification by moving and adjusting the X-ray irradiation unit20and the two-dimensional X-ray detector30.

Further, a direct beam stopper31is installed in front of the two-dimensional X-ray detector30on the upper holding member16. The direct beam stopper31has a function of shielding X-rays that have passed through the sample S from the X-ray irradiation unit20and travelled straight, and preventing the X-rays from entering the two-dimensional X-ray detector30.

As described above, the rotation arm11is also equipped with the vacuum path32. Each of the arm members12,13and14is provided with a support member17for supporting the vacuum path32. The vacuum path32is supported by these support members17and is arranged on an optical path of X-rays that have passed through the sample S and scatter X-rays generated around the X-rays. The upper end surface of the vacuum path32is positioned in the vicinity of the two-dimensional X-ray detector30.

The scatter X-rays that have passed through the sample S spread radially and reach the two-dimensional X-ray detector30. Therefore, the vacuum path32is configured so that the diameter of a lower end surface thereof facing the sample S is reduced and the diameter thereof is stepwise increased toward an upper end surface thereof.

The inside of this vacuum path32is hermetically sealed to form a vacuum state therein, and both the end surfaces of the vacuum path32are formed of a material such as carbon, boron carbide, or Kapton, which has a small X-ray absorption rate. As a result, the vacuum path32can transmit therethrough the X-rays and scatter X-rays that have passed through the sample S, and prevent occurrence of air scattering.

[Optical System Including X-Ray Irradiation Unit and Two-Dimensional X-Ray Detector]

FIG.6is a diagram schematically showing an optical system configured between the X-ray irradiation unit and the two-dimensional X-ray detector.

The X-ray irradiation unit20includes components such as an X-ray tube21, a focusing mirror22, and an aperture23. Further, a guard slit24is arranged in front of the sample S.

As the X-ray tube21is used an X-ray tube in which the electron beam focal size on a target is equal to 70 μm or less, preferably 40 μm or less. Copper (Cu), molybdenum (Mo), silver (Ag), gold (Au) or the like can be selected as a target material, but in the case of the transmission type, high-energy X-rays capable of transmitting through an Si wafer which is the substrate are required, and thus it is desirable to use molybdenum (Mo) or silver (Ag) that meets this condition.

As the focusing mirror22may be adopted a side-by-side type focusing mirror22in which two multilayer mirrors each having a multilayer formed on the surface thereof are arranged in an L shape and integrated with each other. Further, a Kirkpatrick Baez type focusing mirror in which two multilayer mirrors are arranged independently of each other may be adopted.

The focusing mirror22is adjusted so as to focus on the detection surface of the two-dimensional X-ray detector30, and has a function of focusing X-rays on a rectangular spot of 100 μm or less, preferably 50 μm or less lengthwise and breadthwise at the focal point.

The aperture23has a function of shielding leaked light generated when the X-rays emitted from the X-ray tube21are not incident to the focusing mirror22and pass to the outside as they are. The X-rays emitted from the X-ray tube21are passed through the aperture23while leaked light is shielded by the aperture23, and then monochromatized and focused by the focusing mirror22.

The guard slit24is a single crystal pinhole slit formed of a single crystal of germanium, and it is supported by a slit support member (not shown) provided on the rotation arm11and arranged in front of the sample S.

Normal slits have a disadvantage that when X-rays impinge on them, parasitic scattering occurs to intensify the background. On the other hand, the guard slit24formed of a single crystal of germanium can reduce parasitic scattering and suppress the background.

Note that a slit25for further reducing the cross-sectional area of X-rays may be arranged between the focusing mirror22and the guard slit24.

The X-rays emitted from the X-ray tube21are incident to the focusing mirror22while shielding the leaked light by the aperture23. Then, the X-rays that have been monochromatized and focused by the focusing mirror22are narrowed in cross-sectional area by the guard slit24and applied to an inspection point having a small area on the sample S.

Subsequently, the X-rays transmitted through the sample S and the scatter X-rays generated in a small angle region around the X-rays travel to the two-dimensional X-ray detector30through the vacuum path32shown inFIG.4. Out of these X-rays, the X-rays that have passed through the sample S from the X-ray irradiation unit20and traveled straight are shielded by the direct beam stopper31provided in front of the two-dimensional X-ray detector30. As a result, only the scatter X-rays generated in the small angle region of the X-rays are incident to the two-dimensional X-ray detector30.

Here, the distance L1from the focal point of the X-ray tube21to the sample S affects the focused area of the X-rays to be applied to the sample S. In other words, as the distance L1is longer, the focused area of the X-rays to be applied to the sample S is smaller. Further, in the transmission type small-angle scattering device, the distance L2from the sample S to the two-dimensional X-ray detector30is referred to as a camera length, and this camera length L2affects the angular resolution of the two-dimensional X-ray detector30. In other words, as the camera length L2is longer, the angular resolution is more improved.

However, in the transmission type small-angle scattering device arranged vertically as in the present embodiment, there is a limit in securing a long distance L1and a long camera length L2. Therefore, it is preferable that these dimensions are appropriately determined in comprehensive consideration of the environment at the site where the device is installed, the focused area of X-rays on the sample S, and the angular resolution.

As described above, the rotation arm11is configured so that the second arm member13slides in the longitudinal direction with respect to the first arm member12, and the third arm member14slides in the longitudinal direction with respect to the second arm member13. Therefore, the camera length L2can be arbitrarily set by appropriately adjusting the respective slide positions of the sliding arm members13and14.

Note that the rotation arm11may be provided with a position adjusting mechanism for moving the X-ray irradiation unit20in the optical axis direction of X-rays to arbitrarily change the distance L1. Further, a position adjusting mechanism for moving the two-dimensional X-ray detector30in the optical axis direction of X-rays to arbitrarily change the camera length L2may be installed in the rotation arm11.

[Sample Stage]

Next, the detailed structure of the sample stage will be described mainly with reference toFIGS.7to12.

FIG.7is a perspective view showing the appearance of the sample stage constituting the transmission type small-angle scattering device according to the present embodiment.FIG.8is an enlarged plan view showing the sample holder for supporting the sample, andFIGS.9to11are perspective views of different sites of the sample stage when the different sites are focused on in order to describe the sample positioning mechanism, andFIG.12is a longitudinally sectional view showing the sample stage.

As described above, the sample stage40includes the sample holder42for supporting the sample S and the sample positioning mechanism for driving the sample holder42.

The sample positioning mechanism includes an in-plane rotation mechanism for causing the sample S supported by the sample holder42to perform in-plane rotation (φ-rotation), a Y-axis moving mechanism for moving the sample holder42in the longitudinal direction (Y-axis direction) parallel to the surface of the sample S supported by the sample holder42, an X-axis moving mechanism for moving the sample holder42in the lateral direction (X-axis direction) parallel to the surface of the sample S supported by the sample holder42, a Z-axis moving mechanism for moving the sample holder42in the vertical direction (Z-axis direction) perpendicular to the surface of the sample S supported by the sample holder42, and a χ-axis swing mechanism for swinging the sample holder42around the χ-axis.

Here, as shown inFIG.7, the sample stage40is configured such that an X-axis moving frame51is installed on a base frame50, a χ-axis rotating table52is installed on the X-axis moving frame51, a Y-axis moving table53is installed on the χ-axis rotating table52, a Z-axis driving table54and a Z-axis moving table55are installed on the Y-axis moving table53, and a sample holding frame56forming the sample holder42is installed on the Z-axis moving table55.

As shown inFIG.8, the sample holder42is formed inside a circular sample holding frame56. The inside of the sample holding frame56serves as an X-ray transmission hole57, and is configured so as to support the sample S in a state where the sample S faces the X-ray transmission hole57. Suction support pieces58are provided on the inner peripheral edge of the sample holding frame56so as to protrude inward from a plurality of locations (4locations in the figure).

A part of the outer peripheral edge portion of the sample S is placed on the upper surfaces of the suction support pieces58, and vacuum-sucked onto the upper surfaces of the suction support pieces58. Note that a vacuum nozzle59is opened on the upper surface of each suction support piece58, and the vacuum nozzles59are vacuum-sucked by a vacuum suction device (not shown).

The X-ray transmission hole57formed inside the sample holding frame56communicates with the cavity43of the sample stage40shown inFIGS.1A and1B(seeFIG.12). The X-rays emitted from the X-ray irradiation unit20are passed through the X-ray transmission hole57from the cavity43, and applied to the back surface of the sample S supported by the suction support pieces58.

The conventional X-ray inspection device has a general configuration in which the sample holder42is formed of a material having a low X-ray absorption rate such as Kapton, and the entire back surface of the sample S is arranged in close contact with the upper surface of the sample holder42. However, for example, when a semiconductor device formed on a semiconductor wafer is an inspection target, the back surface of the semiconductor wafer may come into contact with the sample holder42formed of a material such as Kapton, and be contaminated.

According to the sample holder42of the present embodiment, with respect to the back surface of the sample S, only a limited part of the outer peripheral edge thereof is in contact with the suction support pieces58, so that the sample S can be supported without touching a central portion of a semiconductor wafer on which a circuit pattern is formed.

In addition, almost the entire region of the sample S except for partial minute regions supported by the suction support pieces58can be irradiated with X-rays from the X-ray irradiation unit20through the cavity43and the X-ray transmission hole57, so that a wide measurable region can be secured. With respect to the partial minute regions supported by the suction support pieces58, the partial minute regions can be also irradiated with X-rays by changing the suction positions thereof with a sample S transport robot.

Next, the in-plane rotation mechanism will be described in detail mainly with reference toFIGS.8and9.

The sample holding frame56constituting the sample holder42has a rotation guide portion60formed at a circular outer peripheral edge portion thereof, and the rotation guide portion60is supported so as to be freely rotatable within a plane by rotation support portions61which are provided at a plurality of locations (four locations in the figure) on the upper surface of the Z-axis moving table55. Each rotation support portion61supports the rotation guide portion60from the upper and lower sides by a pair of upper and lower support rollers62.

A driven-side pulley63is formed on the sample holding frame56. Further, an in-plane rotation drive motor64is installed on the Z-axis moving table55, and a drive belt66is looped between a drive-side pulley65provided on a drive shaft of the in-plane rotation drive motor64and the driven-side pulley63of the sample holding frame56.

The in-plane rotation mechanism is configured by these components of the rotation guide portion60, the rotation support portions61, the in-plane rotation drive motor64, the drive-side pulley65, the driven-side pulley63, and the drive belt66. In other words, the rotational driving force from the in-plane rotation drive motor64is transmitted to the sample holding frame56via the drive belt66. The rotation driving force causes the sample holding frame56supported by the rotation support portions61to rotate within a plane.

Next, the X-axis moving mechanism, the Y-axis moving mechanism, and the Z-axis moving mechanism will be described in detail mainly with reference toFIG.10A.

The X-axis moving frame51is installed on the base frame50via the X-axis moving mechanism.

The X-axis moving mechanism includes an X-axis drive motor67, a ball screw68, guide rails71, and sliders72.

The X-axis drive motor67, a screw shaft69of the ball screw68, and the guide rail71are installed on the base frame50.

The guide rails71extend in the X-axis direction, and the sliders72are freely movable along the guide rails71. The guide rail71is installed at each of both end portions of the base frame50, and the sliders72which are combined with the respective guide rails71support the X-axis moving frame51so as to be freely movable.

The screw shaft69of the ball screw68is freely rotatably supported by a bearing73provided on the base frame50, and extends in the X-axis direction. The screw shaft69is connected to a rotary drive shaft of the X-axis drive motor67, and is rotationally driven by the rotational driving force of the motor67.

A nut member70is engaged with the screw shaft69, and the nut member70moves in the X-axis direction as the screw shaft69rotates. The nut member70is fixed to the X-axis moving frame51, and the X-axis moving frame51moves integrally with the nut member70in the X-axis direction.

As shown inFIGS.10A and7, the X-axis moving frame51is provided with a pair of bearings52aat both end portions thereof, and the χ-axis rotating table52is installed so as to be freely swingable via swing support shafts74which are freely swingably supported by these bearings52a. The Y-axis moving table53is installed on the χ-axis rotating table52via the Y-axis moving mechanism.

The Y-axis moving mechanism includes a Y-axis drive motor75, a ball screw76, and guide rails91and sliders92shown inFIG.12. The guide rail91is provided at each of both end portions of the χ-axis rotating table52, and extends in the Y-axis direction. The slider92is freely movably combined with each guide rail91, and the Y-axis moving table53is supported by these sliders92.

The Y-axis drive motor75and a screw shaft77of the ball screw76are installed on the side wall of the χ-axis rotating table52. The screw shaft77of the ball screw76is freely rotatably supported by a bearing78provided on the side wall of the χ-axis rotating table52, and extends in the Y-axis direction. The screw shaft77is connected to the rotational drive shaft of the Y-axis drive motor75, and is rotationally driven by the rotational driving force of the motor75.

A nut member79is engaged with the screw shaft77, and the nut member79moves in the Y-axis direction as the screw shaft77rotates. The nut member79is fixed to the Y-axis moving table53, and the Y-axis moving table53moves integrally with the nut member79in the Y-axis direction.

Further, the Z-axis driving table54is installed on the Y-axis moving table53.

Guide rails93extending in the Y-axis direction are installed on the Y-axis moving table53, and sliders94are combined with the guide rails93(seeFIG.12). The Z-axis driving table54is installed on the Y-axis moving table53while supported by the sliders94.

Further, a ball screw95shown inFIG.12and a Z-axis drive motor80shown inFIG.10Aare installed on the Y-axis moving table53, and a screw shaft of the ball screw95is connected to the rotational drive shaft of the motor80. The screw shaft is freely rotatably supported on the Y-axis moving table53by a bearing (not shown).

The nut member96shown inFIG.12is engaged with the screw shaft, and the nut member96moves in the Y-axis direction as the screw shaft rotates. The nut member96is fixed to the Z-axis driving table54, and the Z-axis driving table54moves integrally with the nut member96in the Y-axis direction.

The Z-axis moving table55is supported on the Z-axis driving table54via guide members81and sliding members82that are combined in a wedge-like shape as shown inFIG.10B.

The guide member81is installed at each of both end portions of the Z-axis driving table54. The sliding members82which are respectively combined with the guide members81are fixed to the bottom surface of the Z-axis moving table55.

Guide rails83extending in the Z-axis direction are installed at both end portions of the Y-axis moving table53, and sliders84which are combined with the guide rails83are fixed to the Z-axis moving table55. As a result, the Z-axis moving table55is freely movable in the Z-axis direction integrally with the sliders84along the guide rails83.

When the Z-axis driving table54moves in one direction of the Y-axis upon reception of the rotational driving force of the Z-axis drive motor80, the guide members81also move integrally in the same direction. Along with this movement, the sliding members82which are combined with the guide members81in the wedge-like shape are pushed up in the Z-axis direction. Further, when the Z-axis driving table54moves in the opposite direction, the guide members81also move integrally in the same direction, and the sliding members82which are combined with the guide members81in the wedge-like shape descend. As a result, the Z-axis moving table55moves in the vertical direction along the guide rails83.

Since the guide member81and the sliding member82which are combined with each other in the wedge-like shape are always kept in a sliding contact state without rattling, the sample holder42can be accurately moved in the vertical direction and positioned to a desired height position.

Next, the χ-axis swing mechanism will be described in detail mainly with reference toFIG.11.

The χ-axis swing mechanism is incorporated between the X-axis moving frame51and the χ-axis rotating table52. In other words, the χ-axis swing mechanism includes a χ-axis drive motor85, a driving force transmission belt86, a worm87, and a worm wheel88.

The fan-shaped worm wheel88is provided at a position below the bearing52aprovided at one end portion of the X-axis moving frame51, and the pitch circle thereof is positioned on the same axis as the swing support shaft74supported by the bearing52a.

The χ-axis drive motor85and the worm87are installed on the outer surface of the side wall of the χ-axis rotating table52. A driving force transmission belt86is wound between a drive-side pulley89provided on the rotational driving shaft of the χ-axis drive motor85and a driven-side pulley90provided on the rotating shaft of the worm87. As a result, the rotational driving force from the χ-axis drive motor85is transmitted to the worm87via the driving force transmission belt86. This rotational driving force causes the worm87to rotate and turn along the pitch circle of the worm wheel88, and the χ-axis rotating table52rotates around the swing support shaft74integrally with the worm87. The central axis of the swing support shaft74is positioned so as to match the χ-axis shown inFIG.1B.

The optical axis angle of incident X-rays with respect to the sample S supported by the sample holder42can be arbitrarily changed by driving the above-mentioned X-axis swing mechanism and the rotation arm11of the goniometer10.

As shown inFIG.12, the sample stage40of the present embodiment is configured so that the cross-sectional area of the cavity43is increased from an upper end opening portion43acommunicating with the X-ray transmission hole57of the sample holding frame56to a lower end opening portion43bthrough which incident X-rays are taken in. As a result, an angle range in which the incident X-rays can be inclined without being blocked by members around the cavity43(that is, an angle range in which the optical axis of the incident X-rays with respect to the sample S can be inclined) is widened, and thus it is possible to flexibly adapt to various measurement conditions.

For example, in a dimensional example shown inFIG.12, the optical axis of X-rays incident from the vertical direction can be inclined at an angle of 200 or less with respect to a semiconductor wafer (sample S) of 150 mm in radius.

[Structure of External Housing]

FIG.13is a perspective view showing a state in which the transmission type small-angle scattering device according to the present embodiment is covered with an external housing.FIG.15Ais also a left-side view,FIG.15Bis also a plan view, andFIG.16is also a longitudinally sectional view.FIG.14is a perspective view showing a state in which the external housing is folded.

Generally, a transmission type small-angle scattering device using X-rays is installed in a state in which the periphery thereof is covered with an external housing for protection against X-rays.

The transmission type small-angle scattering device1according to the present embodiment has a vertically elongated structure in order to irradiate the sample S supported by the sample holder42with X-rays in the vertical direction (seeFIGS.1A to3). Therefore, as shown inFIG.13, the external housing200also has a vertically elongated structure.

Here, in the present embodiment, the external housing200includes a housing main body201and a plurality of housing element members202and203, and is configured so that each of the housing element members202and203is freely movable in the vertical direction with respect to the housing main body201.

Specifically, as shown inFIGS.15A and15B, the housing element member202on the middle stage is freely movable in the vertical direction along guide rails210with respect to the housing main body201, and further the housing element member203on the upper stage is freely movable in the vertical direction along guide rails211with respect to the housing element member202.

The driving force from a drive motor (not shown) is transmitted to each of the housing element members202and203via a drive mechanism (not shown) to drive the housing element members202and203in the vertical direction.

When the external housing200is transported or installed on site, as shown inFIG.14, both the housing element members202and203are moved to a lower position and set to be overlapped with one another and folded up inside the housing main body201. As described above, the external housing200is set to be in a compact form having a small height dimension, so that a transportation work and an installation work of the external housing200can be extremely easily performed, and it is possible to realize shortening of the work times required for these works and reduction of labors for these works.

If the external housing200is configured so that the respective housing element members202and203are disassembled from the housing main body201, a disassembling/assembling work would be troublesome because the external housing200is a heavy object. However, as described above, the external housing200is configured so that the housing element members202and203are driven in the vertical direction with the driving force of the drive motor, whereby the disassembling/assembling work on site is not required, and the installation work and the removal work on site can be further easily performed.

Note that inFIGS.13to15A, a part or all of the wall surface covering the transmission type small-angle scattering device is omitted in order to visually recognize the inside of the external housing200. Further, a substrate feeding device310is juxtaposed with the external housing200in front of the external housing200as described later, and the external housing200is configured so as to have no wall surface on the side where the substrate feeding device310is juxtaposed, and the substrate feeding device310communicates with the inside of the external housing200.

Further, as shown inFIG.16, the internal space of the external housing200is vertically partitioned into upper and lower spaces by shielding panels220which are horizontally arranged above the sample stage40. The lower space partitioned by the shielding panels220(that is, the lower space in which the sample stage40is installed) is supplied with air from which dust has been removed with high accuracy in a fan filter unit300juxtaposed outside the external housing200. As a result, the lower space becomes a clean space with extremely little dust, and it is possible to prevent dust from adhering to the semiconductor wafer (sample S) supported by the sample holder42.

The shielding panels220block the upward flow of air from the fan filter unit300, and realize an efficient and economical supply of air to the semiconductor wafer and its surroundings.

[Overall Structure as Semiconductor Inspection Device]

FIG.17is a perspective view showing the appearance of a semiconductor inspection device incorporating the transmission type small-angle scattering device according to the present embodiment.

As shown inFIG.17, in addition to the fan filter unit300described above, a substrate feeding device (EFEM)310and an electrical component portion320are juxtaposed with the external housing200outside the external housing200that covers the periphery of the transmission type small-angle scattering device, thereby constituting the semiconductor inspection device.

The substrate feeding device310has a function of automatically feeding a semiconductor wafer (sample S) as a measurement target to the sample holder42, and automatically carrying out a measured semiconductor wafer from the sample holder42. Note that the semiconductor wafer is automatically carried out while it is stored in a hermetically sealed cassette (FOUP).

Further, in the electrical component portion320are installed a power supply for supplying electric power to the transmission type small-angle scattering device and a computer for controlling the device.

Furthermore, the semiconductor inspection device is equipped with equipment for supplying utilities (not shown).

With these configurations, the semiconductor inspection device incorporated with the transmission type small-angle scattering device according to the present embodiment automatically feeds the semiconductor wafer and realizes execution of in-line automatic measurement in the middle of the semiconductor manufacturing process.

[Control System]

FIG.18is a block diagram showing a control system of the transmission type small-angle scattering device according to the present embodiment.

An X-ray irradiation controller101controls the X-ray irradiation unit20.

Further, an image of the sample S captured by the optical microscope35is subjected to image recognition by an image recognition circuit102. The optical microscope35and the image recognition circuit102constitute image observing means for observing the image of the sample S placed in the sample holder42. Note that the focal position of the optical microscope35is adjusted by a focus controller103.

A positioning controller104drives and controls a sample positioning mechanism110. In particular, when an inspection target point of the sample S is placed at a measurement position P of the device, the positioning controller104drives and controls the sample positioning mechanism110based on the image of the sample S which has been captured by the optical microscope35and recognized by the image recognition circuit102.

The goniometer10is driven and controlled by a goniometer controller105.

Each of the components such as the X-ray irradiation controller101, the image recognition circuit102, the focus controller103, the positioning controller104, and the goniometer controller105operates based on setting information sent from a central processing unit100. Here, the setting information is prestored as a recipe in a storage unit106, and it is read out by the central processing unit100and output to each of the above-mentioned components. The two-dimensional X-ray detector30is controlled by a detection control circuit107.

[Execution Procedure of Measurement Operation]

FIG.19is a flowchart showing an execution procedure of a measurement operation by the transmission type small-angle scattering device according to the present embodiment having the above-described configuration.

Here, a measurement operation when a semiconductor wafer having a circuit pattern of a semiconductor device formed thereon is used as the sample S will be described.

Software for executing small-angle scattering measurement is prestored in the storage unit106, and the central processing unit100(CPU) executes the following processing steps according to the software.

After the semiconductor wafer which is the sample S as an inspection target is sucked and supported by the sample holder42, the positioning controller104first drives and controls the sample positioning mechanism110to place the semiconductor wafer at a position below the optical microscope35(step S1).

Next, the surface of the semiconductor wafer is observed by the optical microscope35, and the image recognition circuit102recognizes a unique point formed on the surface of the semiconductor wafer based on image data from the optical microscope35(step S2).

Here, the unique point formed on the surface of the semiconductor wafer is prestored as a recipe in the storage unit106. As the unique point is set a portion which the image recognition circuit102can recognize without confusion based on image information from the optical microscope35, such as a characteristic pattern shape formed on the surface of the semiconductor wafer.

Next, the positioning controller104drives and controls the sample positioning mechanism110to place a preset inspection target point at the measurement position P of the device based on position information of the inspection target point with the unique point recognized by the image recognition circuit102being set as a reference (Step S3).

Subsequently, small-angle scattering measurement is executed (step S4), and the central processing unit100analyzes measurement data (step S5).

Here, for example, when performing shape analysis measurement such as analysis of the tilt angle of a deep hole formed on the surface of the semiconductor wafer, by driving the rotation arm11of the goniometer10or by swinging the semiconductor wafer by the χ-axis swing mechanism, the optical axis angle of X-rays with respect to the semiconductor wafer is changed, whereby the shape analysis on the tilt angle of the deep hole, etc. can be performed.

Each of the steps S3to S5described above is executed on all inspection target points set on the semiconductor wafer (step S6), and after the small-angle scattering measurement is executed on all the inspection target points, the measurement operation is terminated.

Measurement Example of Semiconductor Device and Inclination Measuring Means of Semiconductor Wafer

A semiconductor device is usually formed on a semiconductor wafer, and scattering bodies as measurement targets are periodically arranged in a direction parallel to the principal plane of the semiconductor wafer.

Measurement targets include minute holes and pillars that constitute the semiconductor device.

Semiconductor devices are evolving in miniaturization and high integration day by day, and there are cases where the diameters of holes and pillars are several tens of nm and the depths (heights) thereof are several μm, resulting in extremely fine and high aspect ratio. By using the transmission type small-angle scattering device according to the present embodiment for such structures, it is possible to specify the accurate three-dimensional shapes of these holes and pillars.

Here, it is preferable to measure the inclination of the surface of the semiconductor wafer and adjust so that the surface of the semiconductor wafer is perpendicular to the optical axis of incident X-rays before performing the small-angle scattering measurement.

FIG.20Ais a front configuration diagram schematically showing a configuration example relating to means for measuring the inclination of the semiconductor wafer.

As shown inFIG.20A, a laser inclination measuring device36is provided in the rotation arm11of the goniometer10to be arranged side by side with the two-dimensional X-ray detector30. The two-dimensional X-ray detector30and the laser inclination measuring device36are installed in a moving table37that moves in the lateral direction.

The moving table37moves in the lateral direction with the driving force of a drive motor (not shown), and any one of the two-dimensional X-ray detector30and the laser inclination measuring device36can be placed at a position facing the optical axis O of X-rays emitted from the X-ray irradiation unit20while the two-dimensional X-ray detector30and the laser inclination measuring device36are switched to each other.

The laser inclination measuring device36includes a laser light source36aand a laser detector36b, and it has a function of irradiating the surface of the semiconductor wafer (sample S) supported by the sample holder42with laser light from the laser light source36a, and detecting the laser light reflected from the surface of the semiconductor wafer by the laser detector36bto measure the inclination of the surface of the semiconductor wafer with respect to the optical axis O.

Based on the inclination of the surface of the semiconductor wafer with respect to the optical axis O measured by the laser inclination measuring device36, the χ-axis swing mechanism and the in-plane rotation mechanism of the sample stage40are driven to adjust the inclination of the surface of the semiconductor wafer so that the surface of the semiconductor wafer is vertical to the optical axis O of incident X-rays.

By adjusting the inclination of the surface of the semiconductor wafer as described above, the χ-axis swing mechanism and the rotation arm11of the goniometer10are driven with the adjusted orientation being defined as an origin (χ=0°, θ=0°), which makes it possible to arbitrarily change the optical axis angle of X-rays with respect to the semiconductor wafer.

By adjusting the inclination of the surface of the semiconductor wafer, it is possible to measure the positional relation (inclination) of the holes and pillars formed in the semiconductor wafer with the surface of the semiconductor wafer, and also it is possible to obtain useful information regarding the shape of the device.

Thereafter, the small-angle scattering measurement is executed according to a flowchart ofFIG.19.

FIG.20Bis a side configuration diagram schematically showing another configuration example relating to the means for measuring the inclination of the semiconductor wafer.

In the configuration shown inFIG.20B, the laser inclination measuring device36is installed side by side with the optical microscope35. In order to measure the inclination of the surface of the semiconductor wafer, the semiconductor wafer (sample S) supported by the sample holder42is moved to a position below the laser inclination measuring device36by driving the Y-axis moving mechanism and the X-axis moving mechanism of the sample stage40.

The laser inclination measuring device36has a function of measuring the inclination of the surface of the semiconductor wafer by irradiating the surface of the semiconductor wafer with laser light from the laser light source36aand detecting the laser light reflected from the surface of the semiconductor wafer by the laser detector36b.

Here, for example, if the positions of the laser light source36aand the laser detector36bare adjusted in advance so that the laser inclination measuring device36can measure an inclination with the horizontal plane set as a reference, the inclination of the surface of the semiconductor wafer with respect to the horizontal plane or the vertical axis can be measured.

Note that the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications and applications can be carried out as needed.

For example, the rotation arm is not limited to the configuration including the three arm members12,13and14as shown inFIG.4, and it may include two or four or more arm members.

Further, as shown inFIGS.13to16, the external housing is not limited to the configuration in which the two housing element members202and203are freely movable with respect to the housing main body201, and it may be configured so that one or three or more housing element members are freely movable with respect to the housing main body. Further, the movement of these housing element members may be configured to be manually moved as needed instead of use of the driving force from the drive motor.