WO2017021655A1

WO2017021655A1 - Method and device for the ion beam analysis of a sample

Info

Publication number: WO2017021655A1
Application number: PCT/FR2016/052021
Authority: WO
Inventors: Eric BROCHARD; Smail CHAHAL; Isabelle ZACHARIE-AUBRUN
Original assignee: Commissariat à l'énergie atomique et aux énergies alternatives
Priority date: 2015-08-03
Filing date: 2016-08-03
Publication date: 2017-02-09
Also published as: FR3039899A1; FR3039899B1

Abstract

Method and device for the ion beam analysis of a sample. The invention relates to a method for analysing a sample arranged in an analysis chamber (11) and subjected to a focussed ion beam, in which a protective body (20) is detachably fixed in the analysis chamber, said protective body (20) having an opening for the passage of the ion beam and comprising a structure for collecting sprayed particles, which extends around the opening, at a distance from the focussing point of the ion beam.

Description

Method and device for analyzing a sample by ion beam

TECHNICAL AREA

The present invention relates to a device for analyzing an object by ion beam, in particular a device for analyzing or imaging a sample or fragment of an object radiating by ion beam, and to a method for analysis using such a device.

STATE OF THE ART

It is known to analyze a sample, object, or substrate, generally under vacuum, by subjecting the sample, object, or substrate to the action of an ion beam, for example a gallium ion beam.

In the present application, the term "sample" is used to designate an object, a substrate, or a material.

In this application, the term "analysis" is used to refer to physical or chemical analysis as well as observation or imaging.

The invention is particularly applicable to analytical devices such as ion probes and scanning electron microscopes and focused ion beam.

Such an apparatus generally comprises: an analysis chamber intended to receive the sample and in which a high vacuum can be made; a sample holder; an ion column producing a focused ion beam that can be directed to a surface of a sample disposed on the support; and at least one analysis instrument, in particular an electron beam producing an electron beam which can be directed towards the sample, or a detector sensitive to the particles or radiations emitted by the sample by interaction between the ion beam and the material of the sample.

In order to be able to analyze all or part of a sample, the sample or the sample support can be placed on a cross-table allowing the analysis zone to be moved. "Point" of the sample which is subjected to ion bombardment, according to at least two orthogonal axes.

As described in particular in US4976843, the impact of an ion beam on the surface of a sample can cause a sputtering of particles - ions, electrons, or atoms - or clusters of particles that are ripped off. ) s - or ejected (s) - from the sample.

US4976843 discloses an apparatus which has a metal screen pierced with an orifice disposed immediately above a region of a substrate subjected to the ion beam.

This screen allows the path of the ion and electron beams to the region of the substrate, prevents the deviation of the electron beam by parasitic electrostatic fields, and supports a gas injection needle.

The orifice of the screen allows the passage of the pulverized particles which move away from the surface of the substrate, up to detectors.

Sputtered particles from the sample can then be deposited on the walls of the chamber, ionic and electronic columns, and instruments and detectors disposed in the chamber.

When the sample subjected to the ion beam contains a material that is dangerous for a human being, in particular a radioactive or toxic material, the accumulation of these deposits over time can lead to a contamination of these walls which can make it dangerous. use of the device, and may falsify the analysis results.

STATEMENT OF THE INVENTION

An object of the invention is to propose a method and a device for analyzing or treating an object by ion beam, in particular a device for analyzing or imaging an ion beam irradiating sample, which is improved and / or that remedies, at least in part, the shortcomings or disadvantages of known methods and devices ion beam analysis.

According to one aspect of the invention, there is provided an analysis device which comprises an analysis chamber and an ion column arranged to produce a focused ion beam in the analysis chamber, a shield member having a first aperture for the passage of the ion beam and having a pulverized particle collection structure which extends around the aperture and away from the focal point of the ion beam, as well as means for releasably fixing the protective member in the analysis chamber, so that the protective member can be placed in the chamber to collect particles of a sample removed by the ion beam and to prevent their deposition on walls of the chamber, the ion column, or an instrument disposed in the chamber, and can be removed from the chamber to be cleaned or replaced.

To facilitate the passage of the ion beam through the aperture, the smallest dimension of the projection of the first aperture in a plane perpendicular to the axis of propagation of the ion beam - or the longitudinal axis of the ion column - , is large in front of the diameter of the focused ion beam.

The relationship between this smallest dimension (if the diameter of the opening) and the diameter of the focused ion beam can be located in a range of 10 ³ to about 10 ^7, more preferably in a range of 10 ⁴ about 10 to about ⁶ .

The first opening may extend in a plane perpendicular to the axis of propagation of the ion beam.

The first opening may extend in the immediate vicinity of the nose of the ion column.

The distance separating the collection structure from the focal point of the ion beam may especially be in a range from about 5 millimeters to about 25 millimeters.

The collection structure may extend continuously around the first opening, so that it has a closed contour, in particular a circular contour. Alternatively, the collection structure may partially surround the first opening which then forms an indentation and has an open contour, in particular a contour in the form of a circular arc.

In particular, when the analysis device comprises (at least) an instrument which is located in the analysis chamber and extends in the vicinity of the nose of the ion column, such as an electronic column arranged to produce an electron beam in the analysis chamber, the collection structure may have (at least) a second opening or notch, in particular a notch provided in the contour of the collection structure.

The second opening - or indentation - may have a shape and dimensions adapted to marry, with a small clearance, a portion of the wall of the instrument.

When the instrument is an electronic column, the second opening - or indentation - may have a shape and dimensions suitable for the passage of an electron beam produced by the electronic column, through the protective member.

The protective member may have a third opening or indentation whose shape and dimensions are adapted for the passage, through the protection member and up to a particle or radiation detector emitted by a sample subjected to the beam. focused ion or electron beam, particularly to an energy dispersive analyzer located in the chamber.

The protective member may have a fourth opening or indentation whose shape and dimensions are adapted for the passage, through the protection member and up to another detector of particles or radiation emitted by a sample subjected to the beam of ion focused or electron beam, in particular up to a secondary ion detector or secondary electron, which is also located in the chamber. The collection structure may have a plurality of collector surfaces or walls that extend respectively along planes that may be mutually inclined two by two.

In particular, the collection structure may comprise a first collection wall surrounding the first opening.

The first wall may be substantially planar and may extend in a first plane substantially perpendicular to the axis of the ion beam.

The collection structure may comprise a second collection wall which may have a second opening or indentation in an arc.

The second wall may be substantially planar and may extend along a second plane inclined to the first plane by a non-zero angle and different from 180 degrees, in particular an angle in a range of about 40 or 50 degrees up to at about 60 degrees.

In particular, the second wall may extend in a plane substantially perpendicular to the axis of the electron beam produced by an electronic column.

The collection walls may extend in the extension of each other, or may be connected (two by two) by elements - or walls - of connection.

To allow the interception of a substantial portion of the atomized particles under the action of the ion beam, the contour of the collection structure may extend to a distance from the ion beam axis and / or the axis of the first aperture, which is such that the apex angle of the smallest circular base cone whose apex is on the focal point of the ion beam, whose axis coincides with that of the ion beam, and in which fits the collection structure, is greater than or equal to about 60 degrees, especially in a range from about 60 degrees up to about 120 degrees, especially within a range of 70 degrees about 1 to about 10 degrees, or in a range from about 80 degrees to about 120 degrees.

The means for fixing the protection member in the analysis chamber may comprise - or essentially consist of - mechanical fixing means.

These fixing means may be integral with the protection member and be complementary to other fastening means which are integral with a wall of the chamber, the ion column, or an instrument disposed in the chamber.

To facilitate the establishment and extraction of the protective member in the analysis chamber, the analysis device may further comprise means for guiding the protection member in the analysis chamber, allowing to guide the movement of this member between a position of engagement - and release - mutual securing respectively integral means of the protective member and the chamber or an instrument, and a mutual locking position of these means of fixation.

These guiding means may comprise - or be essentially constituted by - translation guiding means, in particular translation guiding means along an axis perpendicular to the plane of one of the first and second collection walls, and / or according to an axis parallel to the axis of passage permitted by one of the first and second openings - or notches -.

These translational guiding means may be supplemented by means for guiding rotation, in particular locking means preventing the rotation of the protective member inside the chamber, during its movement between the position of engagement of the fastening means and the locking position of the fastening means.

According to another aspect of the invention, there is provided a method of analyzing a sample disposed in an analysis chamber and subjected to a focused ion beam, in which removable, in the analysis chamber, a protective member having a first opening for the passage of the ion beam and having a pulverized particle collection structure which extends around the first opening and away from the focus point of the beam ionic.

According to embodiments of the analysis method, an analysis device as described or defined in the present application is used.

Other aspects, features, and advantages of the invention appear in the following description which refers to the appended figures and illustrates, without any limiting character, preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 schematically illustrates, in side view, the main components of an analysis device according to one embodiment.

FIG. 2 illustrates, in sectional view and on an enlarged scale, the protection member illustrated in FIG. 1, and is a view along II - II of FIG.

FIG. 3 illustrates, in front view, along the axis of propagation of a focused ion beam, the protection member illustrated in FIGS. 1 and 2.

DETAILED DESCRIPTION OF THE INVENTION

Unless otherwise explicitly or implicitly stated, elements or members - structurally or functionally identical or similar - are designated by identical reference numerals in the different figures.

As illustrated in FIG. 1, the analysis device 10 comprises an analysis chamber 11 that can receive a sample 12 placed on a sample support 13.

The chamber 1 1 receives an ion column 14 producing an ion beam propagating along the axis 15 to the surface of the sample, at the focal point 18 of the ion beam. The chamber 1 1 also receives an electronic column 16 producing an electron beam propagating along the axis 17 to the surface of the sample.

In order to collect a large part of the particles sprayed by interaction of the ion beam and the sample, a protective member 20 is arranged in the chamber, between the point of focus of the ion beam and the instruments 14, 16.

This member 20 comprises a pulverized particle collection structure which extends near the nose 28 of the ion column 14, around the axis 15 of the ion beam.

As illustrated in FIGS. 2 and 3, the collection structure of the protection member 20 comprises four planar walls 21 to 24 for collecting pulverized particles, which extend facing the point of focus of the ion beam:

a side wall 21 extending perpendicular to the axis 15 of the ion beam;

a central wall 23 which also extends perpendicular to the axis 15 and is pierced by at least a first central circular opening 26 centered on the axis 15 to allow the passage of the ion beam through the body member 20; protection;

an intermediate wall 22 which extends substantially parallel to the axis 15 and connects the side wall 21 and the central wall 23; and

another lateral wall 24 which forms an angle close to 50 degrees to the plane of the central wall 23, and which has an indentation 27.

These walls 21 to 24 can be obtained by folding a plane metal blank.

For an ion column producing a focused beam whose diameter is of the order of 5 to 10 nanometers, it is possible to drill into the central wall 23 an opening 26 whose diameter is of the order of 1 millimeter, for example. With reference to FIG. 2, the angle 29 at the apex of the smallest circular base cone 30 whose vertex coincides with the focusing point 18 of the ion beam, whose axis coincides with the axis 15 of the ion beam and which surrounds (framed) the structure 21 to 24 of collection, may be of the order of about 100 degrees, so that the walls 21 to 24 intercept a large portion of the particles sprayed.

As illustrated in FIG. 2, the indentation 27 is centered on the axis 17 of propagation of the electron beam produced by the column 16; the dimensions of the notch 27 are adapted to that of the nose of the column 16, in order to fit a part of the wall of this nose, and avoid the deposition of particles on the part of the column located behind - for an observer placed in point 18 - the wall 24. These dimensions are also suitable for the passage of the electron beam.

The collection wall 23 further comprises a third opening 31 of oblong shape and axis 32 which can be inclined with respect to the axis 15. This opening 31 can be shaped and sized to fit - and protect - a part of a wall of an analysis instrument, in particular an energy dispersive analyzer ("EDS"), which is located in the chamber, in the vicinity of columns 14, 16 .

The collection wall 23 further comprises a fourth notch 38, in the form of a rectangular notch formed on the contour of the wall 23.

This notch 38 may be shaped and dimensioned to fit - and protect - part of a wall of another analysis instrument, in particular an instrument - or detector - for imaging secondary ions and / or secondary electrons emitted by the sample subjected to an ionic or electronic bombardment, which is also located in the chamber, in the vicinity of the columns 14, 16.

The shape and the dimensions of the indentation 38 may also be adapted for the passage, through the protection member and up to the detector of secondary ions or secondary electrons, of particles emitted by a sample subjected to the focused ion beam or electron beam.

To detachably (reversibly) fix the protective member 20 facing the nose 28 of the column 14 and the sample holder 13, additional removable fixing means are respectively provided on the walls of the chamber or instruments 14, 16, and on the protective member 20, for example on the intermediate wall 22.

With reference to FIG. 2, the fastening means integral with the member 20 comprise a tip 33 designed to cooperate with a sleeve (not shown) of complementary shape which is integral with the chamber or an instrument.

The tip 33 has an elongated shape along an axis 34 parallel to the axis 17 of the notch 27.

The base 35 of the tip is connected to the intermediate wall 22 (connection) of the member 20.

The base 35 is extended by a cylindrical portion 36, of axis 34, which allows the displacement of the tip 33 - and the member 20 - along this axis 34, between a position of engagement - and disengagement - mutual of the tip and the socket which receives it, and a mutual locking position of these fastening means, by sliding the portion 36 in a bore of the sleeve, with a small clearance.

In this locking position, a lug 37 protruding on the portion 36 can be engaged in a complementary locking member which is integrated in the socket.

The cylindrical portion 36 for guiding the tip in translation in the bushing may also be provided with a flat portion (not shown) providing rotational guidance during the sliding of the nozzle 33, so as to prohibit the rotation of the nozzle. the portion 36 in the sleeve, and thus to avoid the rotation of the protective member 20 inside the chamber, during the mutual engagement movement of the fastening means of the member 20.

Claims

claims

1 - Apparatus (10) for analysis which comprises a chamber (1 1) for analysis and an ion column (14) arranged to produce a focused ion beam in the analysis chamber, characterized in that it further comprises a protection member (20) having a first opening (26) for the passage of the ion beam and having a spray particle collection structure (21-24) which extends around the opening (26) and away from the focusing point (18) of the ion beam, as well as means (33) for releasably fixing the protection member in the analysis chamber, so that the protective member can be put in place in the chamber for collecting particles of a sample torn off by the ion beam and to prevent their deposition on walls of the chamber, the ion column, or an instrument disposed in the chamber, and can be removed from the chamber for cleaning or replaced.

2 - Device according to claim 1 wherein the contour of the structure (21 to 24) of collection extends to a distance from the axis (15) of the ion beam and / or the axis of the first opening (26), which is such that the angle (29) at the apex of the smallest cone (30) of circular base whose vertex is at the point (18) of focusing of the ion beam, whose axis coincides with that ( 15) of the ion beam, and in which the collection structure (21 to 24) is inscribed, is greater than or equal to about 60 degrees, especially in a range of from about 60 degrees to about 120 degrees.

3 - Device according to claim 2 wherein the angle (29) at the top of the cone (30) is in a range of about 70 degrees to about 10 degrees.

4 - Device according to claim 2 wherein the angle (29) at the top of the cone (30) is in a range of about 80 degrees to about 120 degrees. 5 - Device according to any one of claims 1 to 4 wherein the ratio between the smallest dimension of the projection of the first opening (26) in a plane perpendicular to the axis (15) of propagation of the ion beam - or to the longitudinal axis of the ion column -, and the diameter of the focused ion beam is set within a range of 10 ³ to about 10 ^7, more preferably in a range of 10 ⁴ to about 10. ⁶

6 - Device according to any one of claims 1 to 5 wherein the first opening (26) extends near the nose (28) of the ion column (14).

7 - Device according to any one of claims 1 to 6 wherein the first opening (26) extends in a plane perpendicular to the axis (15) of propagation of the ion beam.

8 - Device according to any one of claims 1 to 7 wherein the structure (21 to 24) of collection extends continuously around the first opening (26) which has a closed contour.

9 - Device according to any one of claims 1 to 5 wherein the structure (21 to 24) partially surrounds the first opening (26) which forms a notch and has an open contour.

10 - Device according to claim 8 or 9 wherein the first opening (24) has a circular contour, respectively arcuate.

1 1 - Device according to any one of claims 1 to 10 which comprises at least one instrument (16) extending in the analysis chamber, and wherein the protective member (20) has a second opening or notch (27).

12 - Device according to claim 1 1 wherein the second opening or indentation (27) has a shape and dimensions adapted to fit, with a small clearance, a portion of the wall of the instrument (16) which extends to near the nose of the instrument. 13 - Device according to claim 10 or 1 1 wherein the instrument (16) is an electronic column, and wherein the dimensions of the second opening or indentation (27) are adapted for the passage of an electron beam produced by the column (16).

14 - Device according to any one of claims 1 to 13 wherein the protective member (20) has a third opening or indentation (31) whose shape and dimensions are adapted for the passage of particles or radiation emitted by a sample subjected to the focused ion beam or electron beam, through the protective member and to a detector, in particular to a dispersive energy analysis detector, which is located in the bedroom.

15 - Device according to any one of claims 1 to 14 wherein the protective member (20) has a fourth opening or notch (38) whose shape and dimensions are suitable for the passage of particles or radiation emitted by a sample subjected to the focused ion beam or to an electron beam, through the protection member and to another detector, in particular to a secondary ion or secondary electron detector, which is located in the room.

16 - Device according to any one of claims 1 to 15 wherein the collection structure has a plurality of surfaces or walls (21 to 24) of collection which extend respectively along mutually inclined planes two by two.

17 - Device according to any one of claims 1 to 16 wherein the collection structure comprises a first wall (23) of collection surrounding the first opening (26).

18 - Device according to claim 17 wherein the first wall (23) is substantially planar and extends in a first plane substantially perpendicular to the axis (15) of the ion beam. 19 - Device according to any one of claims 17 or 18 wherein the collection structure comprises a second wall (24) of collection which has a second opening or notch (27).

20 - Device according to claim 19 wherein the second wall (24) is substantially planar and extends in a second plane substantially perpendicular to the axis (17) of an electron beam produced by an electronic column (16) located in bedroom.

21 - Device according to claim 19 or 20 wherein the second wall (24) is inclined relative to the first wall (23) of an angle (25) in a range from about 40 degrees to about 60 degrees, in in particular about 50 to 60 degrees.

22 - Device according to any one of claims 1 to 21 wherein the means (33) for fixing the protective member in the analysis chamber comprises mechanical fixing means.

23 - Device according to any one of claims 1 to 22 wherein the means (33) of attachment are integral with the member (20) of protection and are complementary to fastening means integral with a wall of the chamber, the ionic column, or instrument disposed in the chamber.

24 - Device according to any one of claims 1 to 23 which further comprises guiding means (36, 37) of the protective member (20) in the analysis chamber, to guide the movement of this organ between a position of engagement - and disengagement - means (33) of attachment integral with the member (20), with complementary fixing means which are integral with a wall of the chamber, the ion column, or an instrument disposed in the chamber, and a locking position of said fastening means (33).

25 - Device according to claim 24 wherein the guide means (36, 37) comprise guide means (36) in translation, in particular translation guide means along an axis (34) perpendicular to the plane of the one first and second collecting walls (23, 24), and / or along an axis parallel to the axis (15, 17) of the first and second openings - or indentations - (26, 27).

26 - Device according to claim 24 or 25 wherein the guide means (36, 37) comprise means for guiding (37) in rotation, in particular locking means prohibiting the rotation of the protective member inside. of the chamber, during its movement between the engagement position of the fastening means and the locking position of the fastening means.

27 - Method for analyzing a sample placed in an analysis chamber and subjected to a focused ion beam, in which is fixed removably, in the analysis chamber, a protective member (20) having a first aperture (26) for the passage of the ion beam and having a collection structure (21-24) of pulverized particles which extends around the first aperture (26) and away from the focusing point (18) of the ion beam.

28 - The method of claim 27 wherein the sample is radioactive.

29 - Method according to claim 27 or 28 wherein a device according to any one of claims 1 to 26 is used.