APPARATUS FOR ANALYZING AND/OR PROCESSING A SAMPLE WITH A PARTICLE BEAM AND METHOD

Abstract

An apparatus for analyzing and/or processing a sample with a particle beam, comprising: a sample stage for holding the sample; a providing unit for providing the particle beam comprising: an opening for guiding the particle beam to a processing position on the sample; and a shielding element for shielding an electric field generated by charges accumulated on the sample; wherein the shielding element covers the opening, is embodied in sheetlike fashion and comprises an electrically conductive material; wherein the shielding element comprises a convex section, this section being convex in relation to the sample stage; and wherein the convex section has a through opening for the particle beam to pass through to the sample.

Claims

1. An apparatus for analyzing and/or processing a sample with a particle beam, the sample being a lithography mask, comprising: a sample stage for holding the sample; a providing unit for providing the particle beam comprising: an opening for guiding the particle beam to a processing position on the sample; and a shielding element for shielding an electric field generated by charges accumulated on the sample; wherein the shielding element covers the opening, is embodied in sheetlike fashion and comprises an electrically conductive material; wherein the shielding element comprises a convex section, this section being convex in relation to the sample stage and being curved in the direction of the sample stage; wherein the convex section has a through opening for the particle beam to pass through to the sample; and wherein the apparatus is configured such that the convex section of the shielding element is at a distance from the sample of at most 500 μm during an analysis or processing of the sample with the particle beam.

2. The apparatus of claim 1, comprising a gas feed configured for feeding a process gas through the through opening of the shielding element to the processing position on the sample.

3. The apparatus of claim 1, comprising a gas feed configured for feeding a process gas into a gap, wherein the gap is formed by the sample arranged on the sample stage and by the shielding element.

4. The apparatus of claim 2, wherein the gas feed comprises a feed channel integrated into the shielding element.

5. The apparatus of claim 1, wherein the through opening comprises the point of a smallest distance between the shielding element and the sample stage.

6. The apparatus of claim 1, wherein the shielding element comprises a planar section, from which the convex section extends in the direction of the sample stage.

7. The apparatus of claim 1, wherein the convex section is embodied in funnel-shaped fashion, in particular with a circular cross section.

8. The apparatus of claim 1, wherein the convex section includes a strictly convex section, a spherical surface and/or a segment of a spherical surface.

9. The apparatus of claim 1, wherein the convex section is embodied in such a way that a connecting straight line that connects two points (P1, P2) on a surface of the convex section of the shielding element runs outside the shielding element for any combination of two points (P1, P2) on the surface of the convex section of the shielding element.

10. The apparatus of claim 1, wherein the shielding element comprises on its surface a layer composed of an electrically conductive material, wherein a layer thickness of the layer is greater than or equal to a penetration depth of the particles of the particle beam into the material.

11. The apparatus of claim 1, wherein the shielding element has exactly one through opening.

12. The apparatus of claim 1, wherein the shielding element has a plurality of through openings separated from one another by webs.

13. The apparatus of claim 12, wherein the through openings each have a hexagonal cross section.

14. The apparatus of claim 12, wherein the webs are shaped in such a way that a sample stage-side cross-sectional area of a respective one of the plurality of through openings in a first plane perpendicular to a surface normal of the shielding element on the through opening is smaller than an opening-side cross-sectional area of the respective through opening in a second plane parallel to the first plane.

15. The apparatus of claim 12, wherein one of the plurality of through openings has a geometric feature that distinguishes the through opening from the further through openings.

16. The apparatus of claim 12, wherein one of the plurality of through openings comprises the point of a smallest distance between the shielding element and the sample stage and the further through openings are arranged symmetrically with respect to the one through opening.

17. The apparatus of claim 1, comprising a beam generating unit and a beam guiding element, which is arranged between the beam generating unit and the shielding element and which is configured for guiding the particle beam, wherein provision is made of a voltage source for applying a voltage between the shielding element and the beam guiding element.

18. The apparatus of claim 17, wherein the shielding element is secured to the providing unit by use of a holding apparatus, wherein the holding apparatus and the shielding element are electrically insulated from one another, wherein provision is made of a further voltage source for applying a voltage between the holding apparatus and the beam guiding element and/or the shielding element.

19. The apparatus of claim 1, wherein the shielding element is held in an electrically insulated manner, and comprising a detecting unit for detecting a current that flows away from the shielding element.

20. The apparatus of claim 1, wherein the shielding element comprises a plurality of sections which are electrically insulated from one another and which delimit the through opening, wherein a voltage is able to be applied between in each case two oppositely arranged sections by use of a respective voltage source.

21. The apparatus of claim 1, wherein a plurality of shielding elements are arranged one behind another in the beam direction and cover the opening, wherein at least one of the plurality of shielding elements is held in a displaceable manner for the purpose of providing a settable stop opening.

22. A combination of an apparatus of claim 1 and a sample, the sample being a lithography mask.

23. A method for analyzing and/or processing a sample with a particle beam by use of an apparatus of claim 1, the sample being a lithography mask, the method comprising the following steps: arranging the sample on the sample stage; providing the particle beam; and radiating the particle beam through the through opening onto the processing position on the sample.

Description

DESCRIPTION OF DRAWINGS

[0127] FIG. 1 shows a schematic view of a first exemplary embodiment of an apparatus for analyzing and/or processing a sample with a particle beam;

[0128] FIG. 2 shows an excerpt from a schematic view of a second exemplary embodiment of an apparatus for analyzing and/or processing a sample with a particle beam;

[0129] FIG. 3 shows an excerpt from a schematic view of a third exemplary embodiment of an apparatus for analyzing and/or processing a sample with a particle beam;

[0130] FIG. 4 schematically shows six different exemplary embodiments for a shielding element;

[0131] FIG. 5 schematically shows a cross section through one exemplary embodiment of a shielding element;

[0132] FIG. 6 schematically shows a further exemplary embodiment of a shielding element;

[0133] FIG. 7 shows a schematic view of a fourth exemplary embodiment of an apparatus for analyzing and/or processing a sample with a particle beam;

[0134] FIG. 8 shows a schematic view of a fifth exemplary embodiment of an apparatus for analyzing and/or processing a sample with a particle beam;

[0135] FIG. 9 schematically shows a further exemplary embodiment of a shielding element;

[0136] FIG. 10 schematically shows an excerpt from a sixth exemplary embodiment of an apparatus for analyzing and/or processing a sample with a particle beam;

[0137] FIG. 11 shows a schematic block diagram of one exemplary embodiment of a method for analyzing and/or processing a sample with a particle beam;

[0138] FIG. 12 schematically shows an excerpt from a seventh exemplary embodiment of an apparatus for analyzing and/or processing a sample with a particle beam;

[0139] FIG. 13 shows an excerpt from a schematic view of an eighth exemplary embodiment of an apparatus for analyzing and/or processing a sample with a particle beam;

[0140] FIGS. 14A-D each show a cross section through a shielding element in different embodiments; and

[0141] FIG. 15 shows a schematic diagram for explaining the term “convex”.

DETAILED DESCRIPTION

[0142] Identical elements or elements having an identical function have been provided with the same reference signs in the figures, unless indicated to the contrary. It should also be noted that the illustrations in the figures are not necessarily true to scale.

[0143] FIG. 1 shows a schematic view of a first exemplary embodiment of an apparatus 100 for analyzing and/or processing a sample 200 (see FIG. 2, 3 or 12) with a particle beam 112. The apparatus 100 is preferably arranged in a vacuum housing (not illustrated). The apparatus 100 comprises a providing unit 110 for providing the particle beam 112 and a sample stage 120 for holding the sample 200, said sample stage being arranged below the providing unit 110.

[0144] The providing unit 110 comprises in particular a particle beam generating unit 111, which generates the particle beam 112. The particle beam 112 consists of charged particles, for example of ions or of electrons. An electron beam is involved in the example in FIG. 1. The providing unit 110 is therefore also referred to as an electron column, wherein the apparatus 100 forms a scanning electron microscope, for example. The electron beam 112 is guided by use of beam guiding elements (not shown in FIG. 1). This is also referred to as an electron optical unit. Furthermore, the electron column 110 in FIG. 1 comprises detectors (not shown) for detecting an electron signal originating from backscattered electrons and/or from secondary electrons, for example.

[0145] The electron column 110 has a dedicated vacuum housing, which is evacuated to a residual gas pressure of 10.sup.−7 mbar-10.sup.−8 mbar, for example. An opening 114 for the electron beam 112 is arranged at the underside. The opening 114 is covered by a shielding element 116. The shielding element 116 is embodied in sheetlike fashion and comprises an electrically conductive material. By way of example, the shielding element 116 is formed from gold. The shielding element 116 has a convex section 117, this section being convex relative to the sample stage 120. The convex section 117 curves in the direction of the sample stage 120. The convex section 117 has a through opening 118 for the particle beam 112 to pass through. The through opening 118 comprises in particular a point of the convex section 117 which is closest to the sample stage. The distance between the shielding element 116 and the sample stage 120 is thus the smallest in the region of the through opening 118. The distance between the through opening 118 and the sample 200 is preferably between 5 μm-30 μm, preferably 10 μm, during operation of the apparatus 100. Preferably, the sample stage 120 has a positioning unit (not shown), by use of which a distance between the sample stage 120 and the electron column 110 is settable.

[0146] The shielding element 116 can have a planar region 116A (see FIGS. 14A-D), from which the convex section 117 projects. The planar region 116A preferably extends in a radial direction from an upper end of the convex section 117. The shielding element 116 is secured at the opening 114 of the electron column 110 for example at an outer edge of the planar region 116A.

[0147] Earth potential is applied to the shielding element 116. The shielding element is thus configured to shield an electric field E. In order to clarify this, charges Q that generate the electric field E are illustrated by way of example in FIG. 1. The charges Q are illustrated below the shielding element 116, in a region where the processing region 202 (see FIG. 2, 3 or 12) of the sample 200 would be situated during use of the apparatus 100. Particularly in the case of samples 200 which are electrically non-conductive or only slightly conductive (at least in sections), when the particle beam 112 is incident on the sample 200, charging of the sample 200 and thus the formation of the electric field E occur, as illustrated in FIG. 1. Negative charges Q that arise as a result of the incidence of the electron beam 112 are shown by way of example in FIG. 1.

[0148] As a result of the shielding of the electric field E, firstly, an increased accuracy is achieved with regard to an impingement point and also a focus position of the electron beam 112 on the sample 200, which improves a resolution and process control. Secondly, a flight trajectory of backscattered electrons and secondary electrons that fly counter to the electron beam 112 in the direction of the beam providing unit 111 is influenced to a lesser extent, which likewise improves the resolution and the process control and additionally a sensitivity.

[0149] FIG. 2 shows an excerpt from a schematic view of a second exemplary embodiment of an apparatus 100 for analyzing and/or processing a sample 200 with a particle beam 112. Unless described otherwise below, the apparatus 100 in FIG. 2 can have the same features as the apparatus 100 in FIG. 1. The example shown is configured in particular to carry out a particle beam-induced processing process.

[0150] When the apparatus 100 is operated, the sample stage 120 with the sample 200 arranged thereon is positioned below the providing unit 110, such that the through opening 118 is situated above the processing position 202 on the sample 200 in the beam direction. A gap forms between the sample 200 and the providing unit 110, in particular the shielding element 116.

[0151] In this example, the providing unit 110 has a gas feed 130 configured for feeding a process gas PG into the gap. The process gas PG flows along the gap and thus reaches the processing position 202 on the sample 200. By use of the gas feed 130, it is thus firstly ensured that the processing position 202 is sufficiently supplied with process gas PG; secondly a volumetric flow rate of the process gas PG through the through opening 118 into the providing unit 110 is comparatively low, in particular much lower than if the process gas PG were guided through the through opening 118 from above to the processing position 202.

[0152] The sample 200 is for example a lithography mask having a feature size in the range of 10 nm-10 μm. This can be for example a transmissive lithography mask for DUV lithography (DUV: “deep ultraviolet”, operating light wavelengths in the range of 30-250 nm) or a reflective lithography mask for EUV lithography (EUV: “extreme ultraviolet”, operating light wavelengths in the range of 1-30 nm). The processing processes that are carried out in this case comprise for example etching processes, in which a material is locally removed from the surface of the sample 200, deposition processes, in which a material is locally applied to the surface of the sample 200, and/or similar locally activated processes, such as forming a passivation layer or compacting a layer.

[0153] The process gas PG can comprise a mixture of a plurality of gaseous substances. Appropriate process gases PG suitable for depositing material or for growing elevated structures are, in particular, alkyl compounds of main group elements, metals or transition elements. Examples thereof are cyclopentadienyl trimethylplatinum CpPtMe.sub.3 (Me=CH.sub.4), methylcyclopentadienyl trimethylplatinum MeCpPtMe.sub.3, tetramethyltin SnMe.sub.4, trimethylgallium GaMe.sub.3, ferrocene Cp.sub.2Fe, bis-arylchromium Ar.sub.2Cr, and/or carbonyl compounds of main group elements, metals or transition elements, such as, for example, chromium hexacarbonyl Cr(CO).sub.6, molybdenum hexacarbonyl Mo(CO).sub.6, tungsten hexacarbonyl W(CO).sub.6, dicobalt octacarbonyl Co.sub.2(CO).sub.8, triruthenium dodecacarbonyl Ru.sub.3(CO).sub.12, iron pentacarbonyl Fe(CO).sub.5, and/or alkoxide compounds of main group elements, metals or transition elements, such as, for example, tetraethyl orthosilicate Si(OC.sub.2H.sub.5).sub.4, tetraisopropoxytitanium Ti(OC.sub.3H.sub.7).sub.4, and/or halide compounds of main group elements, metals or transition elements, such as, for example, tungsten hexafluoride WF.sub.6, tungsten hexachloride WCl.sub.6, titanium tetrachloride TiCl.sub.4, boron trifluoride BF.sub.3, silicon tetrachloride SiCl.sub.4, and/or complexes comprising main group elements, metals or transition elements, such as, for example, copper bis-(hexafluoroacetylacetonate) Cu(C.sub.5F.sub.6HO.sub.2).sub.2, dimethylgold trifluoroacetylacetonate Me.sub.2Au(C.sub.5F.sub.3H.sub.4O.sub.2), and/or organic compounds such as carbon monoxide CO, carbon dioxide CO.sub.2, aliphatic and/or aromatic hydrocarbons, and suchlike.

[0154] Appropriate process gases suitable for etching material are for example: xenon difluoride XeF.sub.2, xenon dichloride XeCl.sub.2, xenon tetrachloride XeCl.sub.4, water vapor H.sub.2O, heavy water D.sub.2O, oxygen O.sub.2, ozone O.sub.3, ammonia NH.sub.3, nitrosyl chloride NOCl and/or one of the following halide compounds: XNO, XONO.sub.2, X.sub.2O, XO.sub.2, X.sub.2O.sub.2, X.sub.2O.sub.4, X.sub.2O.sub.6, where X is a halide.

[0155] Additive gases, which can be admixed for example in proportions with the process gas PG in order to better control the processing process, comprise for example oxidizing gases such as hydrogen peroxide H.sub.2O.sub.2, nitrous oxide N.sub.2O, nitrogen oxide NO, nitrogen dioxide NO.sub.2, nitric acid HNO.sub.3, and further oxygen-containing gases, and/or halides such as chlorine Cl.sub.2, hydrogen chloride HCl, hydrogen fluoride HF, iodine I.sub.2, hydrogen iodide HI, bromium Br.sub.2, hydrogen bromide HBr, phosphorus trichloride PCl.sub.3, phosphorus pentachloride PCl.sub.5, phosphorus trifluoride PF.sub.3, and further halogen-containing gases, and/or reducing gases, such as hydrogen H.sub.2, ammonia NH.sub.3, methane CH.sub.4, and further hydrogen-containing gases. Said additive gases can be used for example for etching processes, as buffer gases, as passivating media and suchlike.

[0156] FIG. 3 shows an excerpt from a schematic view of a third exemplary embodiment of an apparatus 100 for analyzing and/or processing a sample 200 with a particle beam 112. This involves, in particular, a particular embodiment of the apparatus 100 shown in FIG. 2.

[0157] In this case, the shielding element 116 comprises a channel that forms the last line section of the gas feed 130. In this case, therefore, the process gas PG is guided through the shielding unit 116. In this way, the process gas PG can be brought very close to the processing position 202. Escape of process gas PG into surroundings of the apparatus 100 can thus be reduced and a consumption of process gas PG can thus be reduced. In particular, a higher process gas pressure with at the same time a lower consumption of process gas can be achieved at the processing position 202. A processing speed can thus be increased.

[0158] The shielding element 116 with the integrated gas feed is produced for example by use of special production methods, in particular LIGA fabrication methods (LIGA: an abbreviation from the German Lithographie, Galvanik und Abformung [lithography, electroplating and moulding]).

[0159] FIG. 4 schematically shows six different exemplary embodiments (A)-(F) for a shielding element 116. FIG. 4 shows the shielding elements 116 in a plan view, for example in the beam direction, for which reason the convex section 117 is indicated in each case only as a dashed line. By way of example, the convex section 117 begins at the line; outwards the shielding element can be embodied in planar fashion, in particular. The examples illustrated in FIG. 4 all comprise a shielding element 116 having a circular outer edge, but geometries deviating therefrom are also possible. Each of the shielding elements 116 illustrated can be used in an apparatus 100 in accordance with any of FIGS. 1-3, 7, 8, 10 or 12.

[0160] In the example in FIG. 4 (A), the shielding element 116 is embodied in the form of a single-hole stop. The shielding element 116 has for example a diameter of 4 mm and the through opening 118 has a diameter of 30 μm. The convex section 117 has for example a diameter of 2 mm.

[0161] In the example in FIG. 4 (B), the shielding element 116 has a plurality of through openings 118, only one of which is identified by a reference sign for the sake of better clarity. Webs 119 are situated between two through openings 118, said webs consisting of the material of the shielding element 116, for example. By way of example, the shielding element 116 is formed from a gold film having a thickness of 10 μm, wherein the through openings 118 were formed by a stamping method. In this example, a plurality of the through openings 118 are situated in the convex section 117 of the shielding element 116. In this example, the through openings 118 all have the same size and geometry, but a plurality of through openings 118 having varying sizes and/or varying geometries can also be provided.

[0162] In the example in FIG. 4 (C), the shielding element 116 has a plurality of through openings 118, only one of which is identified by a reference sign for the sake of better clarity. The through openings 118 here all have a hexagonal geometry. Therefore, a respective web 119 between two through openings 118 has a constant width. In this example, a plurality of through openings 118 are likewise situated in the convex section 117, at least in part.

[0163] In the example in FIG. 4 (D), the shielding element 116 has a plurality of through openings 118, only one of which is identified by a reference sign for the sake of better clarity. The through openings 118 here all have a square geometry. Therefore, a respective web 119 between two through openings 118 has a constant width. In this example, a plurality of through openings 118 are likewise situated in the convex section 117, at least in part.

[0164] In the example in FIG. 4 (E), the shielding element 116 has a plurality of through openings 118, only one of which is identified by a reference sign for the sake of better clarity. The through openings 118 here all have a hexagonal geometry. However, through openings 118 of different sizes are provided.

[0165] The largest through opening 118 is arranged centrally in the convex section 117. The central through opening 118 comprises that point of the shielding element 116 which is closest to the sample stage 120 (see FIGS. 1-3, 5, 7, 8, 10 or 12). The central through opening 118 is preferably that through opening 118 through which the particle beam 112 (see FIGS. 1-3, 7, 8, 10 or 12) for analyzing or processing the sample 200 is guided. Six somewhat smaller through openings 118 are arranged in a manner directly adjoining the central through opening 118. A web width of the web 119 between these through openings 118 is 10 μm, for example. Arranged further outwards in a radial direction are a total of twelve further through openings 118, which are arranged in particular in a hexagonal pattern. A web width between these outer through openings 118 is 50 μm, for example.

[0166] The shielding element 116 of this example makes it possible, firstly, to produce an overview recording of the sample 200 by scanning the particle beam 112 over each of the through openings 118; secondly, however, at the same time a free cross-sectional area is reduced by the wide webs 119, thereby reducing a process gas volumetric flow rate through the shielding element 116.

[0167] In the example in FIG. 4 (F), the shielding element 116 has a plurality of through openings 118, only one of which is identified by a reference sign for the sake of better clarity. The through openings 118 here all have a hexagonal geometry. In this example, the through openings 118 are all of the same size and the webs 119 have a constant width, which is 40 μm, for example. The shielding element 116 of this example has for example the same advantages as the shielding element 116 of Example (E).

[0168] FIG. 5 schematically shows an excerpt from a cross section through one exemplary embodiment of a shielding element 116 having a plurality of through openings 118, only one through opening 118 of which is shown in the excerpt in FIG. 5. The shielding element 116 can be embodied for example as described with reference to FIGS. 1-4. The exit opening 118 is delimited by two webs 119. A cross section of the webs 119 is formed in such a way that a sample stage-side cross-sectional area 118A in a first plane perpendicular to a surface normal N of the shielding element 116 on the through opening 118 is smaller than an opening-side cross-sectional area 118B of the through opening 118 in a second plane parallel to the first plane.

[0169] It can be stated that the webs 119 taper upwards. The webs 119 can be embodied as triangular or trapezium-shaped, for example. What is achieved by this cross section is that backscattered electrons or secondary electrons that are emitted by the sample 200 can be detected in a larger solid angle range over the shielding element 116, as is illustrated by way of example by the cone with opening angle α depicted in FIG. 5.

[0170] A detection efficiency and/or a resolution can thus be improved with the same mechanical stability of the shielding element 116.

[0171] If the shielding element 116 is embodied as a single-hole stop (see FIG. 4 (A)), for example the sidewalls of the individual through opening 118 are correspondingly shaped to achieve the same effect. By way of example, the sidewalls of the through opening 118 form a cone (not illustrated).

[0172] FIG. 6 schematically shows a further exemplary embodiment of a shielding element 116, which is embodied like that from FIG. 4 (F), with the difference that one of the through openings 118 has a geometric feature. In this example, the through opening 118* comprises two adjacent through openings 118, between which the web 119 has been removed. This through opening 118* is therefore unambiguously distinguishable from the other through openings 118 and thus enables an orientation. In particular, proceeding from the through opening 118*, it is possible to find the central through opening 118, which comes closest to the sample stage 120 (see FIGS. 1-3, 5, 7, 8, 10 or 12).

[0173] FIG. 7 shows a schematic view of a third exemplary embodiment of an apparatus 100 for analyzing and/or processing a sample 200 (see FIG. 2, 3 or 12) with a particle beam 112. Unless described otherwise below, the apparatus 100 in FIG. 7 can have the same features as the apparatus 100 in any of FIG. 1, 2 or 3.

[0174] In this example, the providing unit 110 comprises a beam guiding element 113 arranged between the shielding element 116 and the beam generating unit 111. A voltage source U0 is configured to apply a specific accelerating voltage between the beam generating unit 111 and the beam guiding element 113. The charged particles of the particle beam 112 are therefore accelerated in the direction of the beam guiding element 113.

[0175] The shielding element 116 is held for example in a manner insulated from the providing unit 110. A further voltage source U1 is configured for applying a voltage between the beam guiding element 113 and the shielding element 116. As a result, an electric field (not illustrated) forms between the beam guiding element 113 and the shielding element 116. This electric field is controllable by way of the voltage applied by use of the further voltage source U1. The particle beam 112 can thus be guided, in particular accelerated or decelerated and/or deflected, in the region between the beam guiding element 113 and the shielding element 116. The same applies to charged particles which, coming from the sample 200, pass through the shielding element 116 counter to the beam direction. It can also be stated that the beam guiding element 113 together with the shielding element 116 and the voltage source U1 form an electro-optical element.

[0176] As an alternative to the illustration in FIG. 7, the further voltage source U1 can be arranged for example between a beam guiding element 113 embodied as a magnetic pole shoe and the shielding element 116.

[0177] FIG. 8 shows a schematic view of a fourth exemplary embodiment of an apparatus 100 for analyzing and/or processing a sample 200 (see FIG. 2, 3 or 12) with a particle beam 112. The apparatus 100 of this example has the same construction as the apparatus 100 in FIG. 7. The shielding element 116 here, however, is additionally held by a holding apparatus 116*. The holding apparatus 116* is embodied here as a separate element and the shielding element 116 is electrically insulated from the holding apparatus 116*. An additional voltage source U2 is configured for applying a voltage between the beam guiding element 113 and the holding apparatus 116*.

[0178] In the beam direction two electric fields (not shown) arranged one behind the other thus arise, through which the particle beam 112 passes and by use of which the particle beam 112 can be influenced. A large number of different field configurations are settable with this construction.

[0179] As an alternative to the construction shown, the additional voltage source U2 can also be arranged between the holding apparatus 116* and the shielding element 116.

[0180] A further alternative is to arrange the voltage source U1 between the holding apparatus 116* and the beam guiding element 113 and the additional voltage source U2 between the holding apparatus 116* and the shielding element 116.

[0181] FIG. 8 additionally shows a current measuring device I1 configured for detecting a current flowing away from the shielding element 116. The current measuring device I1 can be used as a detector in various ways. Particularly in conjunction with a voltage which is applied between the shielding element 116 and the holding apparatus 116* or the beam guiding element 113 and which acts as an energy filter, it is possible to discriminate for example between secondary electrons having a low energy in the range of from a few electronvolts to a few tens of electronvolts and backscattered electrons having a higher energy in the range of the beam energy. The shielding element 116 can then be used for example as a secondary electron detector.

[0182] Furthermore, a gas pressure in the region of the shielding element 116 can be deduced from the detected current since there is a positive correlation between the gas pressure and the current. Increased gas pressure gives rise to more collisions between particles of the particle beam and gas molecules, and so scattering occurs to a greater extent, thus resulting in an increase in the number of particles scattered to the shielding element 116, and thus also in the detected current.

[0183] FIG. 9 schematically shows a further exemplary embodiment of a shielding element 116, which here comprises eight sections Ia, Ib, IIa, IIb, IIIa, IIIb, IVa, IVb insulated from one another, which each adjoin the through opening 118. A voltage is able to be applied to a respective mutually opposite pair of the sections, that is to say Ia-Ib, IIa-Ilb, IIIa-IIIb, IVa-IVb, by use of a controllable voltage source UI, UII, UHI, UIV respectively assigned to the pair. By use of this shielding element 116, which forms a beam deflecting element, it is possible to achieve additional control over the particle beam 112 (see FIG. 1-3, 7, 8, 10 or 12).

[0184] FIG. 10 schematically shows an excerpt from a further exemplary embodiment of an apparatus 100 for analyzing and/or processing a sample 200 (see FIG. 2, 3 or 12) with a particle beam 112. Unless described otherwise below, the apparatus 100 in FIG. 10 can have the same features as the apparatus 100 in any of FIGS. 1-3, 7 or 8.

[0185] The special feature of this exemplary embodiment is that two shielding elements 116 are provided one behind the other in the beam direction, both of said shielding elements covering the opening 114. In this case, one of the shielding elements 116 is held by a positioning unit 140. The shielding element 116 can thus be displaced relative to the shielding element 116 arranged fixedly thereabove. In this way, the two shielding elements 116 form a settable stop. The positioning unit 140 comprises in particular one or more flexures and/or piezo-actuators. The shielding element 116 is thus displaceable along at least one axis. Preferably, the shielding element 116 is displaceable along at least two axes. Additionally and/or alternatively, the shielding element 116 can be held in a rotatable manner.

[0186] FIG. 11 shows a schematic block diagram of one exemplary embodiment of a method for analyzing and/or processing a sample 200 (see FIG. 2, 3 or 12) with a particle beam 112 (see FIGS. 1-3, 7, 8, 10 or 12). The method is preferably carried out by use of one of the apparatuses 100 in FIGS. 1-3, 7, 8, 10 or 12.

[0187] In a first step S1, the sample 200 is arranged on the sample stage 120. This comprises for example positioning the sample 200 below the shielding element 116 (see FIGS. 1-10 or 12) in such a way that the through opening 118 (see FIGS. 1-10 or 12) is directly above the processing position 202 (see FIG. 2, 3 or 12) on the sample 200.

[0188] In a second step S2, the particle beam 112 is provided and, in a third step S3, the particle beam 112 is radiated through the through opening 118 onto the processing position 202 on the sample 200 and the sample 200 is analyzed and/or processed in this way.

[0189] FIG. 12 shows a schematic illustration of a further exemplary embodiment of an apparatus for analyzing and/or processing a sample 200 with a particle beam 112. Unless described otherwise below, the apparatus 100 in FIG. 12 can have the same features as the apparatus 100 in any of FIGS. 1-3, 7, 8 or 10.

[0190] In this exemplary embodiment, the apparatus 100 is configured to establish an electrical contact with the sample 200 by way of the convex section 117 of the shielding element 116. This may be advantageous particularly in the case of samples 200 having a conductive surface, since charges can directly flow away from the surface of the sample, with the result that a disturbing electric field does not form. In particular, in this exemplary embodiment, before the sample 200 was contacted with the shielding element 116, a protective layer 204 was deposited on the surface of the sample around the processing position 202 by use of a particle beam-induced process. The deposition process was carried out by the apparatus 100, in particular. For this purpose, for example, molybdenum hexacarbonyl Mo(CO).sub.6 was used as process gas PG (see FIG. 2 or 3). The protective layer 204 thus produced is advantageously electrically conductive and serves as protection against mechanical damage to the sample 200 caused by the shielding unit 116 when the latter is in contact with the sample 200. After conclusion of the analysis or the processing, the protective layer 204 can be removed again, for example by use of a particle beam-induced etching process.

[0191] FIG. 13 shows an excerpt from a schematic view of an eighth exemplary embodiment of an apparatus 100 for analyzing and/or processing a sample 200 with a particle beam 112. Unless described otherwise below, the apparatus 100 in FIG. 13 can have the same features as the apparatus 100 in any of FIGS. 1-3, 7, 8, 10 or 12.

[0192] In this example, the providing unit 110 comprises a gas feed 130 configured for feeding a process gas PG through the through opening 118 of the shielding element 116 to the processing position 202 on the sample 200. The process gas PG flows along the beam direction of the particle beam 112 through the through opening 118 and thus reaches the processing position 202 on the sample 200.

[0193] With this arrangement of the gas feed 130, there is the risk of the process gas PG also flowing counter to the beam direction towards the beam generating unit 111 (see FIG. 1, 7 or 8) and reacting chemically with elements in the providing unit 110, for example. Therefore, in this example, an aperture 132 is provided above a nozzle or an outlet of the gas feed 130. The aperture 132 has a through opening for the particle beam 112. The aperture 132 prevents an unimpeded gas flow upwards counter to the beam direction.

[0194] At the same time an electrical potential can be applied to the aperture 132 and the latter can thus be used for beam guiding and/or else be used as a detector. In addition to the aperture 132, differential pump stages can be provided (not illustrated), which further reduce a gas flow upwards counter to the beam direction.

[0195] FIGS. 14A-D each show a cross section through a shielding element 116 in different embodiments. The respective shielding element 116 illustrated in these figures can be used in particular in conjunction with the apparatus 100 from FIGS. 1-3, 7, 8, 10, 12 or 13.

[0196] All the shielding elements 116 illustrated in FIGS. 14A-D have a planar section 116A, from which a convex section 117 extends. The shielding elements 116 illustrated here differ in particular in the geometry of their respective convex section 117. It should be noted, however, that the planar section 116A is not a necessary feature of the shielding element 116. In embodiments (not illustrated), the shielding element 116 does not comprise a planar section 116A. In further embodiments, the shielding element 116 consists of the convex section 117.

[0197] The shielding element 116 illustrated in FIG. 14A has a hemispherical convex section 117, wherein the through opening 118 is arranged at a deepest point of this hemisphere. It should be noted that the convex section 117 need not comprise a complete hemisphere. In further embodiments, the convex section 117 comprises a smaller segment from a spherical surface. In addition, the shape need not be exactly spherical, rather deviations therefrom may also be present, such as instances of compression or stretching of the shape.

[0198] FIG. 14B shows a shielding element 116 that is geometrically identical to the one shown in FIG. 14A, but has even further openings (without reference signs) in addition to the through opening 118. It can also be stated that the convex section 117 of the shielding element 116 is embodied as a net.

[0199] The shielding element 116 illustrated in FIG. 14C has a convex section 117 in the form of a paraboloid of revolution, wherein the through opening 118 is arranged at a deepest point of the paraboloid of revolution.

[0200] The shielding element 116 illustrated in FIG. 14D has a convex section 117 in the form of a cone, wherein the through opening 118 is arranged at the vertex of the cone.

[0201] It should be noted that each of the shielding elements 116 illustrated in FIGS. 4(A)-(F), 6 or 9 can be shaped as illustrated with reference to FIGS. 14A-D. In other words, each of the shielding elements 116 illustrated in FIGS. 14A-D can likewise have the additional features of the shielding elements 116 described with reference to FIGS. 4(A)-(F), 6 or 9.

[0202] The embodiments illustrated in FIGS. 14A-C are examples of a convex section 117 that is strictly convex in accordance with the mathematical definition. The term “convex” is explained on the basis of an illustrative example with reference to FIG. 15.

[0203] FIG. 15 shows a schematic diagram for explaining the term “convex”. FIG. 15 shows a curved line 117 representing for example a sectional edge of a section through a convex section 117. Two points P1, P2 on the curved line 117 are highlighted. A connecting straight line LIN between these two points P1, P2 is furthermore illustrated.

[0204] The curved line 117 is convex, which is discernible for example from the fact that the connecting straight line LIN for any arbitrary pair of points P1, P2 on the curved line 117 runs outside the curved line 117, as illustrated by way of example for the two points P1, P2 in FIG. 15.

[0205] Although the present invention has been described on the basis of exemplary embodiments, it is modifiable in diverse ways. In particular, the features and aspects explained in the various exemplary embodiments are combinable among one another, even if this is not explicitly mentioned in the respective description of the exemplary embodiment.

LIST OF REFERENCE SIGNS

[0206] 100 Apparatus [0207] 110 Providing unit [0208] 111 Beam generating unit [0209] 112 Particle beam [0210] 113 Beam guiding element [0211] 114 Opening [0212] 116 Shielding element [0213] 116* Holding apparatus [0214] 116A Planar region [0215] 117 Convex section [0216] 118 Through opening [0217] 118* Through opening [0218] 118A Cross-sectional area [0219] 118B Cross-sectional area [0220] 119 Web [0221] 120 Sample stage [0222] 130 Gas feed [0223] 132 Aperture [0224] 140 Positioning unit [0225] 200 Sample [0226] 202 Processing position [0227] 204 Protective layer [0228] A Opening angle [0229] E Electric field [0230] I1 Current measuring device [0231] Ia Section [0232] Ib Section [0233] IIa Section [0234] Illb Section [0235] IIa Section [0236] IIIb Section [0237] IVa Section [0238] IVb Section [0239] LIN Connecting straight line [0240] P1 Point [0241] P2 Point [0242] PG Process gas [0243] Q Charges [0244] S1 Method step [0245] S2 Method step [0246] S3 Method step [0247] U0 Voltage source [0248] U1 Voltage source [0249] U2 Voltage source [0250] UI Voltage source [0251] UII Voltage source [0252] UIII Voltage source [0253] UIV Voltage source