JP2009266564A - Sample device of charged particle beam device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sample device of a charged particle beam device capable of observing a sample without changing an observation position even when the sample is tilted. <P>SOLUTION: This sample device of a charged particle beam device is provided with: a sample chamber 12; a moving stage arranged in the sample chamber, mounting a sample 4 thereon, and movable by a rotating drive shaft; a tilting stage 11 mounting the moving stage thereon, and tilting the sample around a tilting axis Q; a drive mechanism for the tilting stage for rotating the tilting stage 11 around the tilting axis Q; and a drive mechanism for the moving stage used for driving the moving stage, arranged independently at a position separated from the tilting stage 11, and connected to the drive shaft of the moving stage by a universal joint. The sample device of a charged particle beam device is characteristically provided with a control means controlling the drive mechanism for the moving stage by being associated with the tilt of the tilting stage 11 to prevent movement of the moving stage regardless of the tilt of the tilting stage 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sample apparatus for a charged particle beam apparatus having a tilt mechanism.

  A scanning electron microscope scans a predetermined region on a sample to be observed with an electron beam, and obtains a sample image based on secondary electrons such as secondary electrons generated from the predetermined region by the scanning. It is useful for observation and analysis.

  FIG. 1 shows one schematic example of such a scanning electron microscope.

  In the figure, 1 is an electron gun, 2 and 3 are a condenser lens and an objective lens for converging an electron beam from the electron gun on the sample 4, respectively.

Reference numerals 5X and 5Y denote an X direction scanning coil and a Y direction scanning coil for scanning the sample 4 in the X direction and the Y direction with the electron beam from the electron gun 1, respectively.
A control device 7 generates various commands for each input. It also accepts input of sample position movement designation and angle movement designation.

  6 is a scanning signal generation circuit that performs various calculations and generates a scanning signal in response to a scanning signal generation command from the control device 7, and the generated X-direction scanning signal is applied to the X-direction scanning coil 5X, and the Y-direction scanning signal is input to the scanning signal generation circuit. Each of the Y-direction scanning coils 5Y is supplied.

  Reference numeral 8 denotes a secondary electron detector that detects secondary electrons generated from the sample 4 by scanning the sample 4 with the electron beam, and 9 denotes a secondary electron detector from the secondary electron detector 8 via an AD converter 10. The image processing apparatus performs various image processing on the secondary electron signal and sends the secondary electron signal subjected to the image processing to the control device 7.

  Reference numeral 11 denotes an inclination stage for inclining the sample 4 and is supported by an inclined rotating body 13 attached to the side wall of the sample chamber 12 so as to be orthogonal to the electron optical axis O. On this inclined stage, a Y-direction stage 14 for moving the sample 4 in the Y direction and an X-direction stage 15 for moving in the X direction are provided.

  FIG. 2 shows details of the sample apparatus provided with the tilt stage 11, the Y direction stage 14, and the X direction stage 15, as viewed from the electron gun 1 side.

  In FIG. 2, reference numeral 16 denotes a worm gear having gear teeth, which is connected to a rotating shaft 18 of a tilting motor 17 provided outside the sample chamber (or the outer wall of the sample chamber) and is rotated by bearings 19 </ b> A and 19 </ b> B attached to the tilting stage 11. Supported as possible.

  A worm wheel 20 is attached around the end of the inclined stage so as to mesh with the gear teeth of the worm gear.

  Reference numeral 21 denotes a bearing provided between the side surface of the tilt stage end portion and the side wall of the sample chamber, which forms the tilt rotating body 13 shown in FIG. The rotation of 18 is transmitted from the worm gear 16 to the worm wheel 20, and the tilt stage 11 is tilted about a horizontal axis Q perpendicular to the electro-optic axis O. The horizontal axis Q is at the same height as the sample surface.

  A Y-direction rail 22 and a Y-direction feed screw 23 are provided on the inclined stage 11 so as to face each other and be separated from each other by a certain distance in parallel, and in a portion that contacts the Y-direction rail 22 of the Y-direction stage 14. A Y-direction groove (not shown) for fitting with the rail is provided. A nut (not shown) to which the feed screw is screwed is attached to a portion of the Y-direction stage 14 facing the Y-direction feed screw 23. The Y-direction feed screw 23 is rotatably supported by the tilt stage 11 by bearings 24A and 24B, and is provided outside the sample chamber (or the sample chamber outer wall) via universal joints 25A and 25B and a connecting rod 26. The Y-direction moving motor 27 is connected to the rotation shaft 27R, and the rotation of the rotation shaft 27R by the operation of the Y-direction movement motor 27 is performed through the universal joint 25B, the connecting rod 26, and the universal joint 25A in the Y direction. By being transmitted to the feed screw 23, the Y-direction stage 14 is configured to move in the Y-direction on the tilt stage.

  An X-direction rail 33 and an X-direction feed screw 28 are provided on the Y-direction stage 14 so as to face each other and be spaced apart from each other by a fixed distance, and are in contact with the X-direction rail 33 of the X-direction stage 15. Is provided with an X-direction groove (not shown) for fitting with the rail. A nut (not shown) to which the feed screw is screwed is attached to a portion of the X direction stage 15 that faces the X direction feed screw 28. The X-direction feed screw 28 is rotatably supported by bearings 29A and 29B on the Y-direction stage 14, and is provided outside the sample chamber (or the sample chamber outer wall) via universal joints 30A and 30B and a connecting rod 31. The rotation shaft 32R of the X-direction movement motor 32 is connected to the rotation shaft 32R, and the rotation of the rotation shaft 32R by the operation of the X-direction movement motor 32 is performed through the universal joint 30B, the connecting rod 31, and the universal joint 30A. By being transmitted to the direction feed screw 28, the X direction stage 15 is configured to move in the X direction on the Y direction stage 14.

  Returning to FIG. 1, reference numerals 34, 35, and 36 in the drawing respectively generate a tilt drive signal, a Y-direction movement drive signal, and an X-direction movement drive signal in response to a command from the control device 7. These are a tilting driver, a Y-direction moving driver, and an X-direction moving driver sent to the tilting motor 17, Y-direction moving motor 27, and X-direction moving motor 32, respectively.

  Reference numeral 37 denotes a display for displaying a sample image or the like in accordance with a command from the control device 7.

  In the scanning electron microscope having such a configuration, a predetermined Y-direction movement drive signal is received from the Y-direction movement driver 35 and a predetermined X-direction movement drive signal is received from the X-direction movement driver 36 according to a command from the control device 7. Are sent to the Y-direction moving motor 27 and the X-direction moving motor 32, respectively, whereby the Y-direction stage 14 moves on the tilt stage 11 in a predetermined distance Y-direction, and the X-direction stage 15 moves. A predetermined distance X is moved on the Y-direction stage 14. As a result, the predetermined region on the sample 4 is centered on the electron optical axis O.

  In this state, the electron beam from the electron gun 1 is focused on the sample 4 by the condenser lens 2 and the objective lens 3. Then, the X-direction and Y-direction scanning signals from the scanning signal generation circuit 6 generated according to the command of the control device 7 are supplied to the X-direction scanning coil 5X and the Y-direction scanning coil 5Y, so that the electron beam is A predetermined area on the sample 4 is scanned.

  Secondary electrons generated from a predetermined region on the sample by the scanning are detected by the secondary electron detector 8 and sent to the image processing apparatus 9 via the AD converter 10.

  The signal subjected to the image processing is sent to the control device 7, and a secondary electron image of a predetermined area on the sample is displayed on the display 37.

JP 2000-133184 A JP-A-9-223477

When a predetermined region is observed with the sample tilted, the tilt drive signal is tilted from the tilt driver 34 according to a command from the control device 7 before or after the movement in the X and Y directions. The tilt stage 11 is tilted by a predetermined angle (θ), and in this state, the sample is observed with an electron beam in the same manner as in the case of observing the sample in a state perpendicular to the electron optical axis O. A predetermined region on the sample is scanned to obtain a secondary electron image of the predetermined region.
When the tilt stage 11 is tilted in this way, the Y-direction stage 14 and the X-direction stage 15 placed on the tilt stage are tilted together.
When the Y-direction stage 14 and the X-direction stage 15 are stopped, the X-direction movement driver 36 is transferred from the Y-direction movement driver 35 to the Y-axis direction movement motor 27 so that the stage position is not moved by an external force. Then, a restraining current is supplied to the X-direction moving motor 32 to generate a restraining magnetic flux so that the rotating shaft 27R and the rotating shaft 32R are restrained from rotating.
As a result, the universal joint 26, the Y-direction feed screw 23 connected to the rotation shaft 27R, and the universal joint 31, the X-direction feed screw 28 connected to the rotation shaft 32R are also restrained from rotating.
When the tilt stage 11 is tilted by a predetermined angle (θ) in this state, the Y-direction stage 14 placed on the tilt stage 11 is also tilted by the angle (θ). As described above, the Y-axis direction moving motor 27 fixed to the sample chamber 12 is restrained by the restraining magnetic flux, and the Y-direction feed screw 23 connected to the Y-axis direction moving motor 27 is also restrained. When the stage 14 is inclined by the angle (θ), the Y-direction feed screw 23 is rotated by the angle (θ) when viewed from the inclined Y-direction stage 14 side.
Similarly, when the tilt stage 11 is tilted by a predetermined angle (θ), the X-direction stage 15 placed on the tilt stage 11 also rotates by the angle (θ). An angle (−θ) rotation occurs between the X-direction feed screw 28 that is restrained and fixed to the sample chamber 12 and the X-direction stage 15.

  Therefore, the Y direction stage 14 is in the Y direction, the X direction stage 15 is in the X direction, and the Y direction feed screw 23 and the X direction feed screw 28 are the distance corresponding to the rotation of the angle (−θ). It moves relative to the tilt stage 11.

  When the sample is scanned with an electron beam in such a state, the observation area set before tilting is not scanned accurately, and therefore information other than the area to be observed is obtained. Will occur.

  Therefore, by attaching the Y direction moving motor 27 and the X direction moving motor 32 on the tilt stage 11, the tilt stage 11 is tilted, and the Y direction stage 14 and the X direction stage 15 are tilted together. However, a countermeasure is proposed in which the Y-direction moving motor 27 and the X-direction moving motor 32 themselves are tilted together so that the Y-direction stage 14 and the X-direction stage 15 do not move with respect to the tilt stage 11. Has been.

  However, the Y-direction moving motor 27 and the X-direction moving motor 32 are placed in the sample chamber 12, so that the sample chamber 12 becomes very large and the scanning electron microscope itself becomes large.

  In addition, when the sample chamber is enlarged, a pump having a very high exhaust capacity must be prepared as a pump for exhausting the sample chamber, which is extremely expensive.

  Further, heat from the motor is conducted to each stage, and a sample drift is generated based on thermal expansion of each stage. In addition, the sample is contaminated by the gas released from the motor.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a sample apparatus for a novel charged particle beam apparatus.

  A vacuum chamber, a movable stage provided in the vacuum chamber and movable in at least one direction by a driving shaft on which the sample is placed and rotated, and the movable stage is placed, and the sample is tilted by rotating around the tilt axis. A tilt stage, a tilt stage drive mechanism for rotating the tilt stage about a tilt axis, and a drive mechanism for driving the moving stage, which are arranged independently from the tilt axis. In the sample apparatus of a charged particle beam apparatus having a moving stage drive mechanism connected to a drive shaft of the moving stage by a universal joint, the tilting stage is prevented from moving regardless of the tilt of the tilting stage. A charged particle beam comprising control means for controlling the moving stage drive mechanism in relation to the tilt of the stage Sample unit of the device.

  According to the present invention, the charged particle beam in which the moving stage on which the sample is set in the sample chamber to be evacuated is placed on the tilting stage, and the motor for moving the moving stage is provided outside the sample chamber. In the sample apparatus of the apparatus, even if the moving stage is tilted and moved with the tilt of the tilting stage, the movement generated with the tilt is canceled, so the sample chamber is made large. Therefore, the charged particle beam can be accurately irradiated to the region to be observed or analyzed in the sample in a state where there is no drift of the sample due to heat from the motor.

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

  First, the principle of the present invention will be described.

  When the tilt stage is tilted at an angle (θ), the Y direction stage on the tilt stage is in the Y direction, and the X direction stage is in the X direction by a distance corresponding to the angle (−θ). Since the tilt stage is tilted by an angle (θ), the Y direction stage is moved in the Y direction and the X direction stage is moved in the X direction by a distance corresponding to the angle (θ). The Y-direction stage and the X-direction stage on the tilt stage are moved by the tilt of the tilt stage if the tilt stage 11 is moved, that is, moved by the same amount of movement in the direction opposite to the move. Even if they are tilted together, the movement of the X direction stage and the Y direction stage becomes zero as a result.

  FIG. 3 shows a schematic example of a scanning electron microscope which is an example of a charged particle beam apparatus provided with a sample apparatus based on such a principle. In the figure, the same reference numerals as those used in FIGS. 1 and 2 denote the same components.

  In the figure, 38 is a Y-direction rotary encoder that generates pulses corresponding to the rotation amount of the rotation shaft 27R of the Y-direction movement motor 27, and 39 is a pulse generation corresponding to the rotation amount of the rotation shaft 32R of the X-direction movement motor 32. Both of the rotary encoders for the X direction have a known configuration including a rotary plate with a slit attached to a rotary shaft, a light emitting element, a light receiving element and the like arranged with the rotary plate interposed therebetween.

  Reference numeral 40 denotes a rotation amount of the rotation shaft 27R of the Y-direction moving motor 27 based on the pulse signal from the Y-direction rotary encoder 38, and the movement amount and an inclination angle signal sent from the control device 7 are obtained. On the basis of this, the Y direction computing device obtains the characteristics of the tilt angle and the rotation amount of the Y direction rotating shaft 27R.

  41 calculates the amount of rotation of the rotating shaft 32R of the X-direction moving motor 32 based on the pulse signal from the X-direction rotary encoder 39, and uses the amount of movement and the tilt angle signal sent from the control device 7. Based on this, it is an X-direction arithmetic unit that obtains the characteristics of the tilt angle and the rotation amount of the X-direction rotation shaft 32R.

42 and 43 indicate the characteristics of the tilt angle and the amount of movement of the Y-direction rotating shaft 27R, the characteristics of the tilt angle and the amount of rotation of the X-direction rotating shaft 22R obtained by the Y-direction computing device 40 and the X-direction computing device 41, respectively. , Y direction table and X direction table to be stored respectively.
A stage fixing jig 45 can fix the X direction stage 15 and the Y direction stage 14 to the tilt stage 11. Remove when using as sample stage.

  In the scanning electron microscope having such a configuration, the following operation is performed before the sample image is observed.

First, the X direction stage 15 and the Y direction stage 14 are fixed to the inclined stage 11 by the stage fixing jig 45. As a result, the X-direction feed screw 28 is fixed to the X-direction stage 15 and the Y-direction feed screw 23 is fixed to the Y-direction stage 14.
Next, in the case where the restraint magnetic flux generation of the Y-direction moving motor 27 and the X-direction moving motor 32 is temporarily stopped and no movement drive signal is sent to each motor, if an external force is applied, The rotary shafts 27R and 32R are kept in a rotating state.

  In this state, the control device 7 issues a tilt command to the tilt driver 34 so that the tilt driver 34 sends a tilt drive signal that gradually increases the tilt angle to the tilt motor 17.

  As a result, the tilt stage 11 is gradually tilted with increasing tilt angles.

  When the tilt stage 11 is sequentially tilted in this way, the Y-direction stage 14 and the X-direction stage 15 riding on the tilt stage are also tilted with increasing tilt angles.

  At this time, the X-direction feed screw 28 is fixed to the X-direction stage 15 and the Y-direction feed screw 23 is fixed to the Y-direction stage 14, the restraint excitation generation of each motor is stopped, and the Y-axis direction moving motor 27 Since the rotary shaft 27R and the rotary shaft 32R of the X-direction moving motor 32 are moved by an external force, the Y-direction feed screw 23 connected to the rotary shaft 27R and the X-direction feed screw 28 connected to the rotary shaft 32R are described above. The rotation shaft 27R of the Y-axis direction movement motor 27 and the rotation shaft 32R of the X-direction movement motor 32 are sequentially rotated by the rotation according to the inclination angle.

  At this time, the rotation amounts of the rotary shaft 27R of the Y-axis direction moving motor 27 and the rotary shaft 32R of the X-direction moving motor 32 with respect to the angle at which the tilt stage 11 is tilted are respectively the Y-direction rotary encoder 38 and the X-direction rotary encoder. The Y-direction computing device 40 and the X-direction computing device 41 detected by the rotary encoder 39 are respectively characterized by the inclination angle and the movement amount of the Y-direction stage 14, and the inclination angle and the movement amount of the X-direction stage 15 respectively. Each characteristic is stored in the Y direction table 42 and the X direction table 43, respectively. After storing the Y-direction table and the X-direction table, the stage fixing jig 45 is removed, the X-direction feed screw 28 and the X-direction stage 15, the Y-direction feed screw 23 and the Y-direction stage 14 are unfixed, and the Y-direction movement motor 27 and the X direction moving motor 32 are restarted, and when no movement drive signal is sent to each motor, the rotating shafts 27R and 32R of each motor do not rotate even if an external force is applied. Keep it.

  After such operation is completed, the observation operation with the sample tilted is started. For example, after a predetermined amount of sample movement is performed in the X direction and the Y direction, a tilt drive signal is sent from the tilt driver 34 to the tilt motor 17 in accordance with a command from the control device 7, whereby the tilt stage 11 is moved to a predetermined level. The angle (θ) is inclined.

  When the tilt stage 11 is tilted in this way, the Y direction stage 14 and the X direction stage 15 that are on the tilt stage are also tilted together.

  At this time, since the stage fixing jig 45 is removed, the Y-direction feed screw 23 and the X-direction feed screw 28 rotate freely. The Y-direction feed screw 23 connected to the rotary shaft 27R and the X-direction feed screw 28 connected to the rotary shaft 32R do not rotate because the restraining magnetic flux of the Y-direction moving motor 27 and the X-direction moving motor 32 is generated. Therefore, the Y-direction feed screw 23 is rotated by an angle (θ) when viewed from the Y-direction stage 14, and the X-direction feed screw 28 is rotated by an angle (θ) when viewed from the X-direction stage 15. Thereby, the Y direction stage 14 and the X direction stage 15 move with respect to the tilt stage 11 by a distance corresponding to the angle (θ).

  At this time, the control device 7 reads, from the Y direction table 42 and the X direction table 43, the rotation amount of the Y direction moving motor rotating shaft 27R and the X direction moving motor rotation amount corresponding to the inclination angle (θ), respectively. A Y-direction movement drive signal for correcting the rotation of the Y-direction stage 14 and the Y-direction feed screw 23 generated by the inclination, and an X-direction movement drive signal for correcting the rotation of the X-direction stage 15 and the X-direction feed screw 28, respectively. The Y-direction movement driver 35 is sent to the Y-direction movement motor 27 from the Y-direction movement driver 35 and the X-direction movement motor 32 is sent from the X-direction movement driver 36 to the X-direction movement motor 32. Since the command is sent to the driver 36, the Y direction stage 14 is in the Y direction, and the X direction stage 15 is in the X direction. It moves relative to the tilt stage 11 only by separation.

If corrected in this way, even if the Y direction stage 14 and the X direction stage 15 on the tilt stage are tilted together by tilting the tilt stage by an angle (θ), as a result, The movement of the Y direction stage and the X direction stage is zero.
In this embodiment, the X-direction rotary encoder 39 and the Y-direction rotary encoder 38 are attached and the rotation amount of the motor corresponding to the tilt angle is obtained and stored in the X-direction table 43 and the Y-direction table 42. If the data for the tilt angle measured in advance by the reference device is stored in the X direction table 43 and the Y direction table 42, the X direction rotary encoder 39 and the Y direction rotary encoder 38 are unnecessary.
Further, although the relationship between the tilt angle and the movement amount is stored in the X direction table 43 and the Y direction table 42, the relationship between the tilt angle and the rotation amount of the feed screw may be stored.
Further, during the tilting operation of the tilting stage 11 during the tilting operation of the X-direction stage 15 and the Y-direction stage 14 due to the tilting of the tilting stage 11, the electron beam can be corrected even during the tilting movement by sequentially performing the correction according to the tilting angle during the operation. Irradiation position shift can be eliminated.

In the above example, the case where the sample apparatus of the present invention is applied to a scanning electron microscope has been described. However, the sample apparatus of the present invention may be another charged particle beam apparatus such as an electron probe analyzer, an electron beam drawing apparatus, or a focused ion beam. It can also be applied to beam processing equipment.
The X and Y stages mounted on the tilt stage have been described. However, the present invention is not limited to the X and Y stages, and is a stage mounted on the tilt stage and movable in one direction (for example, a rotary stage, vertical movement). The present invention can be applied to any stage provided with a mechanism for moving the stage and the like from outside the tilt axis by rotational driving.

1 shows a schematic example of a conventional scanning electron microscope. The details of a sample device provided in a conventional scanning electron microscope are shown. An example in which the sample apparatus of the present invention is applied to a scanning electron microscope which is one of charged particle beam apparatuses will be described.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electron gun, 2 ... Condenser lens, 3 ... Objective lens, 4 ... Sample, 5X ... X direction scanning coil, 5Y ... Y direction scanning coil, 6 ... Scanning signal generation circuit, 7 ... Control apparatus, 8 ... Secondary electron Detector: 9 ... Image processing apparatus, 10 ... AD converter, 11 ... Inclination stage, 12 ... Sample chamber, 13 ... Inclination rotating body, 14 ... Y direction stage, 15 ... X direction stage, 16 ... Worm gear, 17 ... Inclination Motor 18 ... Rotary shaft 19A, 19B ... Bearing 20 ... Worm wheel 21 ... Bearing 22 ... Y direction rail 23 ... Y direction feed screw 24A, 24B ... Bearing 25A ... Universal joint 25B ... Free Joint, 26 ... connecting rod, 27 ... motor for Y direction movement, 27R ... rotating shaft, 28 ... X direction feed screw, 29A ... bearing, 29B ... bearing 30A ... universal joint, 30B ... universal joint, 31 Connecting rod, 32 ... X direction moving motor, 32R ... Rotating shaft, 33 ... X direction rail, 34 ... Tilt driver, 35 ... Y direction moving driver, 36 ... X direction moving driver, 37 ... Display, 38 ... Y-direction rotary encoder, 39 ... X-direction rotary encoder, 40 ... Y-direction computing unit, 41 ... X-direction computing unit, 42 ... Y-direction table, 43 ... X-direction table, 45 ... Stage fixing jig, O ... Electro-optic axis, Q ... tilt axis

Claims (3)

  A vacuum chamber, a movable stage provided in the vacuum chamber and movable in at least one direction by a driving shaft on which the sample is placed and rotated, and the movable stage is placed, and the sample is tilted by rotating around the tilt axis. A tilt stage, a tilt stage drive mechanism for rotating the tilt stage about a tilt axis, and a drive mechanism for driving the moving stage, which are arranged independently from the tilt axis. In the sample apparatus of a charged particle beam apparatus having a moving stage drive mechanism connected to a drive shaft of the moving stage by a universal joint, the tilting stage is prevented from moving regardless of the tilt of the tilting stage. A charged particle beam comprising control means for controlling the moving stage drive mechanism in relation to the tilt of the stage Sample unit of the device.   Means for storing a relationship between a control amount for controlling the moving stage drive mechanism so that the moving stage does not move and an inclination angle of the inclination stage; and the control means is an inclination detected by the inclination angle detection means. 2. The charged particle according to claim 1, wherein a control amount corresponding to the tilt angle is read from the storage unit based on an angle, and the moving stage drive mechanism is controlled based on the read control amount. Beam device sample device.   Means for designating a tilt angle of the stage; means for calculating a relationship between a control amount for controlling the drive mechanism for the movable stage so that the movable stage does not move; and a tilt angle of the tilt stage; 2. A control amount is calculated from an inclination angle specified by the inclination angle specifying means, and the drive mechanism for the inclination angle moving stage is controlled based on the control amount obtained by the calculation. The sample apparatus of the described charged particle beam apparatus.

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