Device with at least one adjustable sample holder and method of changing holder tilt angle and method of preparing a lamella

Abstract

A device comprises an electron column or an ion column, provided with an adjustable holder. The adjustable holder maintains the whole range of movements of the manipulation stage and is adapted to change its position in relation to the stage at least in one direction, wherein the range of movements of the manipulation stage is sufficient to change this position and it is unnecessary to install any other control drive or actuator.

Claims

1. A device with at least one adjustable sample holder comprising an adjustable sample holder located inside a working chamber on a placement area of a manipulation stage, wherein the adjustable sample holder comprises a moveable element with a place for sample placement, a revolving shaft having a longitudinal axis, at least one pillar adapted to support the shaft, the device further comprising a mechanism for fixing the moveable element comprising a crown mounted on the shaft and a counterpart adapted to immobilize the shaft in relation to the counterpart, the mechanism for fixing further being adapted to set the moveable element into a stationary position, in which a movement range of the manipulation stage is retained, and a moveable position, in which the adjustable sample holder has at least one degree of freedom, wherein in the moveable position of the moveable element is adapted for rotation around a longitudinal axis of the shaft, allowing changing of the position of the placement area in relation to the moveable element.

2. The device according to claim 1 wherein the mechanism for fixing the moveable element comprises a pivot on the at least one pillar, a rosette provided with openings for placing the pivot, wherein the openings correspond in size to the pivot and are arranged along a circumference of the rosette, and a pressure device adapted to accommodate the pivot in the opening for the pivot inside the working chamber.

3. The device according to claim 1 wherein a movement vector allowing changing of the position of a moveable element plane in relation to a placement area plane in the moveable position of the moveable element lies in a plane perpendicular to an axis parallel to the shaft axis.

4. The device according to claim 3 wherein the movement allowing changing of the position of the moveable element plane in relation to the placement area plane in the moveable position of the moveable element includes rotation about an axis that aligns with the shaft axis.

5. The device according to claim 1 wherein when changing the position of the moveable element in relation to the placement area, the moveable element is in stationary position in relation to the working chamber.

6. The device according to claim 1 wherein it has two pillars.

7. The device according to claim 1 wherein the sample in the adjustable holder is located in the shaft axis.

8. The device according to claim 1 further comprising at least one non-adjustable holder, which has no degree of freedom, can be put onto the manipulation stage.

9. The device according to claim 1 further comprising an electron column and an ion column.

10. A method of changing a tilt angle of the adjustable sample holder using the device according to claim 2, comprising the steps of: a) placing the adjustable sample holder having a first value of a holder tilt angle and the mechanism for fixing the moveable element in the stationary position into a position when the crown is near the counterpart; b) releasing the mechanism for fixing the moveable element by pressing the crown or the counterpart with a force sufficient to overcome a resistance of the crown or the counterpart; c) rotating the manipulation stage around the longitudinal axis of the shaft, so that a moveable element plane and a manipulation stage plane form a second value of the holder tilt angle, different from the first value of the holder tilt angle, so that during the change of tilt of the moveable element in relation to the placement area, the moveable element is in a stationary position in relation to the axis of an ion beam and the axis of an electron beam; and d) reinstating the mechanism for fixing the moveable element into the stationary position by moving the crown and the counterpart away from each other.

11. The method according to claim 10 wherein the step of rotating the manipulation stage around the longitudinal axis of the shaft, so that the moveable element plane and the manipulation stage plane form the second holder tilt angle, different from the first holder tilt angle, can be repeated multiple times during the method performance.

12. A method of preparing a lamella for transmission electron microscopy using the device with the adjustable sample holder according to claim 1, comprising the steps of: a) setting a first stage tilt angle; b) setting a first value of a holder tilt angle; c) preparing the sample for lamella production from the substrate located in a non-adjustable sample holder with the use of an ion beam; d) transferring the sample from the substrate into the adjustable sample holder; e) machining the sample located in the adjustable holder using the ion beam; f) changing the holder tilt angle into a second value of the holder tilt angle, so that during the change of the tilt of the moveable element in relation to the placement area, the moveable element is in a stationary position in relation to an axis of the ion beam and an axis of an electron beam; and g) checking the lamella quality using the electron beam.

13. The method according to claim 12, further comprising at least one change of the stage tilt angle into a second stage tilt angle corresponding to the second value of the holder tilt angle, and different from the first stage tilt angle.

14. The method according to claim 12 further comprising at least one more change of the holder tilt angle into a third value of the holder tilt angle corresponding to a third value of the holder tilt angle, different from the second value of the holder tilt angle.

15. The method according to claim 12 wherein the change of the stage tilt angle is made during sample machining using a focused ion beam.

16. The method according to claim 12 wherein the lamella quality check is performed using transmission scanning electron microscopy.

17. The method according to claim 12 wherein when transferring the sample from the non-adjustable holder into second adjustable holder, the orientation of the sample remains unchanged.

Description

DESCRIPTION OF DRAWINGS

(1) The summary of the invention is further illustrated by means of exemplary embodiments, which are described with the use of the attached drawings, in which:

(2) FIG. 1—displays a side view of an adjustable holder;

(3) FIG. 2a, 2b, 2c—displays a front view of an adjustable holder;

(4) FIG. 3—displays one of the potential examples of a rosette;

(5) FIG. 4—displays one of the examples of potential arrangement of holders on the manipulation stage;

(6) FIG. 5a, 5b, 5c—displays a schematic process of changing the position of a moveable element;

(7) FIG. 6—displays lamella preparation procedure from the front;

(8) FIG. 7—displays further lamella preparation procedure from the front;

(9) FIG. 8—displays lamella preparation procedure from the back side;

(10) FIG. 9—displays further lamella preparation procedure from the back side;

(11) FIG. 10—displays planar lamella preparation procedure.

EXAMPLES OF INVENTION EMBODIMENTS

(12) FIG. 1 shows a schematic side view of an adjustable holder 4. The device comprises a working chamber 1, inside which a manipulation stage 2 provided with a placement area 3 is arranged, and further an adjustable holder 4, an ion column 5 having the axis 6 of the ion beam, along which an ion beam is distributed towards the sample 20 (not displayed) and an electron beam 7 having the axis 8 of the electron beam, along which an electron beam is distributed towards the sample 20.

(13) The manipulation stage 2, which is provided with a moveable and rotating mechanism allowing movement along three independent mutually perpendicular axes, of which at least one is located in a plane parallel to the plane of the placement area 3, and rotation around three independent mutually perpendicular axes, of which at least one is located in a plane parallel to the plane of the placement area 3.

(14) Ion beam 5 axis and electron beam 7 axis intersect approximately in the point of impact of beams onto the sample 20. Adjustable holder 4 comprises a support pillar 9 to support a shaft 10, on which a moveable element 11 is mounted. The shaft 10 is mounted in the pillar 9 in such way that it may rotate around its longitudinal axis. The moveable element 11 is firmly mounted to the shaft 10 and can be rotated using the shaft 10. The place of the moveable element 11 forms an angle 22 of holder tilt with the manipulation stage 2 plane. The manipulation stage 2 plane forms an angle 21 of stage tilt with a plane perpendicular to axis 8 of the electron beam.

(15) In case of the holder tilt angle 22, an angle having a size of 0° is defined as an angle, in which the place 15 for sample 20 placement leads towards the manipulation stage 2 and the adjustable holder 4 plane is parallel to the manipulation stage plane. An angle having a size of 180° is defined as the angle, in which the place 15 for sample placement leads from the manipulation stage 2.

(16) FIGS. 2a, 2b and 2c schematically show the adjustable holder 4 from the front view. Apart from parts of the adjustable holder 4 already displayed in FIG. 1, the adjustable holder 4 comprises a fixation mechanism comprising a rosette 12 mounted on the shaft 10, a pivot 13 mounted on a pillar 9 and a spring 14 and further a moveable element 11 with a place 15 for sample 20 placement and a crown 16 for controlling the fixation mechanism. In addition, the device comprises a counterpart 17 located on the internal equipment 18 of the working chamber 1. In a preferred embodiment, the sample 20 is located in the shaft 10 axis.

(17) FIG. 2a shows an adjustable holder 4 in a released position. In this position, the crown 16 is pressed against the counterpart 17, wherein it overcomes the spring 14 resistance and the pivot 13 is pushed out of the rosette 12. Consequently, the shaft 10 is not locked with the pillar 9. The shaft 10 with the moveable element 11 is firmly connected to the counterpart 17 in this position and at the same time it can change position in relation to the manipulation stage 2. The counterpart 17 is mounted to the internal equipment of the working chamber 18, e.g. on the signal electron detector. However, it may be located on any equipment, which is arranged in at least one of the possible positions reachable by the crown 16 of the adjustable holder 4.

(18) FIG. 2b shows the holder 4 in a non-adjustable position. The spring 14 presses the rosette 12 towards the support pillar 9, wherein the pivot 13 is located. The pivot 13 falls into the openings 19 in the rosette 12 thus locking the shaft 10 against the pillar 9 and the moveable element 11 cannot change its position in relation to the manipulation stage 2.

(19) FIG. 2c shows another variant of the adjustable holder 4 with one pillar 9 in a released position. The difference from FIG. 2a is that the adjustable holder 4 has only one pillar 9 thus easier access to the moveable element 11 is possible from a side as well. The rosette 12 is, in this case, mounted to the pillar 9 and the corresponding pivot 13 is located on the moveable element 11. When in moveable position, the spring 14 is stretched, in contrast to adjustable holder in FIG. 2a, in which it is pressed. After releasing the crown 16 the rosette 12 is drawn to the pillar 9, the pivot 13 is pushed into the rosette 12 and, consequently, the moveable element 11 is locked.

(20) FIG. 3 shows a side view of one of potential rosette 12 shapes. The rosette 12 comprises, along its circumference, round openings 19 for pivots 13 fitting the pivot 13 shape. Along the circumference, the openings 19 are arranged in angle spacing of the size γ, which equals 45 degrees. The center of the rosette 12 is intersected by the shaft 10. The openings 19 on the rosette 12 as well as the pivot 13 may be of various sizes and shapes, although they should always ensure that after locking, the movements of the rosette 12 in relation to the pivot 13 are not possible. In a preferred embodiment, the openings in the rosette 12 and the pivot 13 shape should fit in terms of shape and size.

(21) FIG. 4 shows a manipulation stage 2, on which two samples 20 are located in adjustable holders 4 and the substrate 23 in a non-adjustable holder 24.

(22) FIGS. 5a, 5b and 5c display a schematic position change process of a moveable element 11 of an adjustable holder 4.

(23) FIG. 5a shows an adjustable holder 4 in relation to the ion beam axis 6 and the electron beam axis 8 in the first position. The ion beam axis 6 with the electron beam axis 8 form an angle of approximately 55 degrees and the electron beam axis 8 with the placement area 3 form and angle lower than 10 degrees, and with the ion beam axis 6 an angle ranging from 55° to 65°. FIB beam falls onto the moveable element plane approximately at the angle of 90 degrees and the sample 20 is irradiated from the first side.

(24) The moveable element 11 is put into a moveable position where it is not possible to change the moveable element 11 position in relation to the ion beam axis 6 and the electron beam axis 8 and it is possible to change position of the moveable element 11 in relation to the manipulation stage 2.

(25) FIG. 5b shows an adjustable holder 4 in a second position that differs from the first position only in that, in comparison to the situation in FIG. 5a, the position of the moveable element 11 rotated by more than 140 degrees around the shaft 10 axis. The position of the moveable element 11 in relation to the electron beam axis 8 remains unchanged.

(26) The moveable element 11 is put into a non-moveable position, in which it is not possible to change the moveable element 11 position in relation to the manipulation stage 2, but it is possible to change the position of the moveable element 11 in relation to the ion beam axis 6 and the electron beam axis 8.

(27) FIG. 5c shows an adjustable holder 4 in a third position, in which the adjustable holder 4 is put into approximately the same position as in FIG. 5a, where the angle between the electron beam axis 8 and the placement area 3 is lower than 10 degrees. FIB beam is impinging on the moveable element 11 plane approximately at the angle of 90 degrees and the sample 20 is irradiated from the other side. The difference between the position in FIG. 5a and FIG. 5c is based on the fact that the moveable element 11 is rotated by more than 140° in comparison with the FIG. 5a.

(28) If the adjustable device of the manipulation stage 2 does not allow sufficient tilt to perform the whole operation in a single step, it is possible to repeat the individual steps until the required position is reached.

(29) If the sample 20 is not located in the shaft 10 axis, other slight corrections are usually necessary, by movements or rotation of the manipulation stage 2.

(30) FIG. 6 shows the first TEM lamella preparation method from the front. In the first step, the substrate 23 is placed on the placement area 3, the area 3 being parallel to manipulation stage 2 plane. From this substrate 23 a sample 20 is prepared with the use of FIB for the production of a TEM lamella. The sample 20 is extracted from the substrate 23 at the tilt under the angle 21 of stage tilt of 55° with the use a manipulation device, e.g. a micro-manipulator. The adjustable holder 4 is tilted by the angle 22 of holder tilt of 90°. The sample 20 is mounted to an adjustable holder 4. In another step, with the use of FIB beam, the sample 20 is polished and formed into a TEM lamella. The ion beam axis 6 intersects the sample 20 approximately in parallel with the lamella machined surface. After machining, the angle 22 of holder tilt is set to 180° and the angle 21 of stage tilt is set to 0° and the prepared lamella quality is checked. The check may be performed with STEM and includes lamella thickness and flatness check. If the lamella meets the required parameters, the method is completed. If the required parameters are not met, the angle 22 of holder tilt is changed to 90° and the angle 21 of stage tilt to 55° and polishing is performed repeatedly.

(31) FIG. 7 shows another lamella preparation method from the front. In contrast to FIG. 6, the sample 20 for the lamella preparation is extracted at the angle 21 of stage tilt of 0° and is placed into an adjustable holder 4 with the angle 22 of holder tilt of 90°. Afterwards, the angle 22 of stage tilt is changed to 55°, when the sample 20 is polished using the FIB. Subsequently, the angle 22 of holder tilt is changed to 125°. The subsequent check may be performed with STEM and includes lamella thickness and flatness check. If the lamella meets the required parameters, the method is completed. If the required parameters are not met, the angle 22 of holder tilt is changed to 90° and the angle 21 of stage tilt to 55° and polishing is performed repeatedly.

(32) FIG. 8 shows lamella preparation method from the back side. In the first step, the substrate 23 is placed on a placement area 3, the area 3 being parallel to the manipulation stage 2 plane. From this substrate 23 a sample 20 is prepared using the FIB for the production of a TEM lamella. The sample 20 is extracted from the substrate 23 at the tilt under the angle 21 of stage tilt of 55° using a manipulation device, e.g. a micro-manipulator. The adjustable holder 4 is tilted by the angle of 22 of holder tilt of 70°. After placing the sample into the adjustable holder 4, the angle 22 of holder tilt is changed to 250°. Afterwards, lamella polishing is made at the angle 21 of stage tilt of 55°. After polishing, the angle 21 of stage tilt is set to 0° and the angle 22 of holder tilt to 160° and the lamella quality is checked. The check may be performed with STEM and includes lamella thickness and flatness check. If the lamella meets the required parameters, the method is completed. If the required parameters are not met, the angle 22 of holder tilt is changed to 250° and the angle 21 of stage tilt to 55° and polishing is performed repeatedly.

(33) FIG. 9 shows another embodiment of lamella preparation from the back side. The difference from the method shown in FIG. 8 is that the sample 20 extraction for lamella production is made at the angle 21 of stage tilt of 0° and lamella quality check at the angle 22 of holder tilt of 105° and the angle 21 of stage tilt of 55°.

(34) FIG. 10 shows planar lamella preparation method. In the first step, the substrate 23 is placed on the placement area 3, the area 3 being parallel to the manipulation stage 2 plane. From this substrate 23 a sample 20 is prepared using the FIB for the production of a TEM lamella. The sample 20 is extracted from the substrate 23 at the tilt under the angle 21 of stage tilt of 0° using a manipulation device, e.g. a micro-manipulator. The adjustable holder 4 is tilted by the angle of 22 of holder tilt of 180°. After placing the sample into the adjustable holder 4, the angle 22 of holder tilt is changed to 90°. Afterwards, lamella polishing is made at the angle 21 of stage tilt of 55°. After polishing, the angle 22 of holder tilt is set to 135° and the lamella quality is checked. If the lamella meets the required parameters, the method is completed. If the required parameters are not met, the angle 22 of holder tilt is changed to 90° and the angle 21 of stage tilt to 55° and polishing is performed repeatedly.

(35) The above mentioned are just selected examples of how an adjustable holder can be used for sample preparation. A person skilled in the art would find other ways to prepare or observe a sample using the adjustable holder.

LIST OR REFERENCE NUMBERS

(36) 1) Working chamber

(37) 2) Manipulation stage

(38) 3) Placement area

(39) 4) Adjustable holder

(40) 5) Ion column

(41) 6) Ion beam axis

(42) 7) Electron column

(43) 8) Electron beam axis

(44) 9) Pillar

(45) 10) Shaft

(46) 11) Moveable element

(47) 12) Rosette

(48) 13) Pivot

(49) 14) Spring

(50) 15) Place for sample

(51) 16) Crown

(52) 17) Counterpart

(53) 18) Internal chamber equipment

(54) 19) Opening for pivot

(55) 20) Sample

(56) 21) Stage tilt angle

(57) 22) Stage holder angle

(58) 23) Substrate

(59) 24) Non-adjustable holder