Abstract:
An apparatus is disclosed for use in a charged particle instrument which defines an inner volume therein. The apparatus comprises an adaptor ( 22 ) having a first portion adapted for attachment to a part ( 20 ) of a gas injection system ( 18 ) of a charged particle instrument which is located within an inner volume of such an instrument; and a second portion arranged to receive a tool ( 24 ) adapted for interaction with a sample ( 14 ) located in the inner volume of such an instrument.

Description:
[0001]    The present invention relates to charged particle instruments, and, in particular, to charged particle microscope instruments. 
       BACKGROUND OF THE INVENTION 
       [0002]    Charged particle microscope instruments, such as a scanning electron beam microscope instrument, a transmission electron beam microscope instrument, a focussed ion beam (FIB) instrument, or a combination instrument using a combination of such technologies, are used to observe samples of materials, for example semiconductor materials. Such instruments are well-known and have been adapted to enable manipulation of samples under observation. For example, see U.S. Pat. No. 6,570,170 which describes the manipulation and observation of a sample in a charged particle instrument. 
         [0003]    Manipulation of the sample if achieved by the provision of a high accuracy tool actuator at least part of which is fitted inside the instrument, and controllable to manoeuvre a manipulation tool with respect to a sample. Such actuators are complex and hence expensive. 
         [0004]    Accordingly, it is desirable to provide an apparatus that allows samples to be manipulated within a charged particle instrument, with lower complexity and cost compared to existing solutions. 
       SUMMARY OF THE INVENTION 
       [0005]    According to a first aspect of the present invention, there is provided an apparatus for use in a charged particle instrument which defines an inner volume therein, the apparatus comprising an adaptor having a first portion adapted for attachment to a part of a gas injection system of a charged particle instrument which part is located within an inner volume of such an instrument; and a second portion arranged to receive a tool adapted for interaction with a sample located in the inner volume of such an instrument. 
         [0006]    According to another aspect of the present invention, there is provided a sample interaction apparatus for a charged particle instrument which defines an inner volume therein, the apparatus comprising an adaptor for attachment to a part of a gas injection system of a charged particle instrument which part is located within an inner volume of such an instrument, and a tool attached to the adaptor, the tool being adapted for interaction with a sample located in the inner volume of such an instrument. 
         [0007]    According to another aspect of the present invention, there is provided a charged particle instrument comprising a housing defining an inner volume therein, a particle source operable to introduce charged particles into the observation zone, a particle detector operable to detect particles in the inner volume, a sample holder located within the inner volume and adapted to hold a sample, a gas injection system which extends into the inner volume, and which is operable to introduce a selected gas into the inner volume, and an apparatus according to another aspect of the present invention, wherein the sample stage is operable to move a sample located thereon with respect to the tool. 
         [0008]    In one example, the adaptor is adapted to be releasably attached to said part of the gas injection system. In one example, the tool is adapted to be releasably attached to the adaptor. 
         [0009]    In one example, the tool is a manipulation needle. Such a needle may be of a resilient, conductive, non-metallic material, such as a carbon fibre. 
         [0010]    An embodiment of the present invention provides an adaptor that enables a tool to be mounted on an existing part of a charged particle microscope instrument inside the inner volume, without the provision of a separate dedicated piece of equipment. In one example, the tool is not movable with respect to the part on which it is mounted. The tool is movable with respect to the sample being processed, by virtue of movement of the sample itself. 
         [0011]    The adaptor may be affixed at any appropriate part of the gas injector system. In one example, the gas injector system is fixed with respect to the housing of the instrument. In another example, the gas injector system is moveable with respect to the inner volume. 
         [0012]    The charged particle microscope instrument may be a scanning electron microscope, a transmission electron microscope, a focussed ion beam (FIB) instrument, or a combination instrument using a combination of such technologies. 
         [0013]    The tool is primarily used for manipulation or probing of samples, for example cutting and repositioning sample portions, or for directly probing (electrically or otherwise) a sample or a portion of it. Any other tool may be provided for providing other functions and capabilities. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a schematic diagram of a charged particle instrument; 
           [0015]      FIG. 2  is a schematic diagram of part of the instrument of  FIG. 1 ; and 
           [0016]      FIG. 3  illustrates use of the instrument of  FIGS. 1 and 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0017]      FIG. 1  is a simplified schematic illustration of a charged particle instrument  1 , such as a microscope instrument. The instrument  1  defines an inner volume  2  in which a sample  14  is located for measurement thereof. In use, the inner volume provides a vacuum chamber in which the sample  14  is able to be observed and manipulated. 
         [0018]    The instrument comprises a particle source  10  which is operable to direct a beam of charged particles towards the sample  14 . A detector  12  is operable to detect results of the interaction of the charged particle beam and the sample. For example, the sample may reflect, scatter and/or deflect the incident charged particles. The sample may be ablated or caused to emit other charged particles by the incident beam. The detector  12  is operable to detect any such particles or emissions from the sample. The detector  12  is operable to produce detection signals for further processing to determine characteristics of the sample. For example, the shape, construction, or grain orientation of the sample may be determined from the detection signals. In addition, or alternatively, the detection signals may be used to determine material structure, or the elements that make up the sample. 
         [0019]    The sample  14  is held by a sample holder  16  which is located on a movable stage  17 . The stage  17  is used to place the sample  14  in an appropriate position in the inner volume  2  of the instrument, such that the charged particle beam from the particle source  10  interacts with a chosen part of the sample  14 . This interaction is detected by the detector  12  which produces detection signals, as is well known. The stage  17  is operable to move the sample  14  within the inner volume. For example, the stage  17  may be able to move the sample  14  in three dimensions, and is also able to rotate the sample  14  about up to three independent axes. Other combinations of linear and rotational movement are possible, as required by the application of the instrument  1 . 
         [0020]    In order to provide a suitable environment in which the charged particle beam can interact unimpeded with the sample  14 , the inner volume  2  is evacuated to provide a vacuum chamber, in accordance with well-known practice. 
         [0021]    The instrument  1  is also provided with a gas injection system  18 , a simplified example of which is illustrated schematically in in  FIG. 2 . The system  18  comprises a gas source  19 , and an injection nozzle  20  which extends into the inner volume  2  of the instrument  1 . The injection nozzle  20  defines a gas injection pathway  21  through which gas is injected into the inner volume  2  of the instrument. The gas source  19  and nozzle  20  may be provided in any appropriate configuration. 
         [0022]    In one example, the gas injection system  18  is fixed with respect to the inner volume  2  of the instrument  1 , and in another example, the gas injection system  18  can move the nozzle  20  in and out of the inner volume  2 . The gas injection nozzle  20  may be movable about such a set position within the inner volume  2  in order that the injected gas is received at an appropriate part of the sample  14  in order to aid processing of the sample. Gas is injected into the inner volume  2  adjacent the sample  14  for a variety of reasons. For example, the gas may aid imaging, may provide better etching capabilities, or may enable deposition of a desired material onto the sample  14 . 
         [0023]    In accordance with the principles of one aspect of the present invention, an adaptor  22  is mounted on the injection nozzle  20 . The adaptor is adapted to carry a tool  24  which is used for interaction with the sample  14 . In order for the tool  24  to interact with the sample  14 , the stage  17  is operable to move the sample  14  with respect to the tool  24 . When the gas injection system is extended into the inner volume  2 , either by being fixed in such a position, or by being moved into such a position, the tool  24 , being affixed to the injection nozzle  20  via the adaptor  22 , is located at a fixed position within the inner volume  2  of the instrument  1 . In the case where the gas injection nozzle  21  is movable, then the adaptor  22 , and tool  24 , will be movable with the nozzle  21 . 
         [0024]    One example of the tool  24  is a manipulator tool or needle. Such a tool is also known as a micro-manipulator or a nano-manipulator. A manipulator tool can, for example, be used to move or otherwise manipulate a portion of the sample  14 . An example of such manipulation is illustrated schematically in  FIGS. 3 and 4 . 
         [0025]    In  FIG. 3 , the sample  14  is shown having been acted upon by an incident charged particle beam from the source  10 , such that a sample portion  25  is available for removal from the sample  14  for transfer to, for example, a sample tray  26 . The stage  17  brings the sample  14  into position adjacent the manipulator tool  24  such that the tool  24  engages with the sample portion  25 , enabling the sample portion  25  to be moved from the sample  14 . As illustrated in  FIG. 4 , the stage  17  is then moved so that the tool  24 , with the sample portion  25  attached thereto, is brought into positon adjacent the sample tray  26 . The sample portion  25  can then be removed from the tool  24  and placed in the tray  16  for removal to another location for further processing. It will be readily appreciated that the process illustrated in  FIGS. 3 and 4  is merely exemplary. 
         [0026]    The manipulator tool  24  may be provided by an elongate needle of any appropriate material. For example, the needle may be of a metallic material, such as aluminium or tungsten, or an insulating material, for example a ceramics, plastics or polymer material, or an appropriate combination of the two. 
         [0027]    In one particular example, the manipulator tool  24  is provided by a resilient, conductive, non-metallic material, such as a carbon fibre filament. Using a carbon fibre filament as a manipulator tool has several advantages over other materials. A single carbon fibre is flexible such that it is not easily damaged when coming into contact with the sample  14  or other item. This flexibility also reduces the risk of the sample  14  being damaged by engagement with the manipulator tool  24 . 
         [0028]    The adaptor  22  may be of any appropriate configuration. For example, the adaptor  22  may be provided by a collar which is attached to the injection nozzle  20 . The collar may be attached by a threaded attachment or may be attached using an adhesive material. As an alternative, the adaptor may be provided by a clip that attaches releasably to the nozzle  21 . Another alternative configuration is provided by a plate or bracket. 
         [0029]    The tool  24  may be attached to the collar by an appropriate fitting technique, such as a threaded fitting or adhesive material. In another example, the adaptor  22  may be provided by an adhesive material that attaches the tool  24  directly to the injection nozzle  20 . 
         [0030]    The exact nature of the tool  24  is not limited to a needle-like manipulator. The tool  24  may be provided by one or more of the following examples:
       A gripper or tweezer arrangement for picking up and moving or simply holding or making an electrical, magnetic or thermal contact with part of the sample  14 .   A gripper with a drive motor attached for turning or bending part of the sample which can be gripped.   A needle or manipulator with one or more drivable axes of movement for the orientation of sample portions or for modifying the sample surface.   A micro or nano needle for the injection to the sample or piece of sample of a fluid.   A micro or nano needle for the injection of an additional gas onto a target region of the sample or piece of sample.   A device fixture for the application of a force to the sample either passively (sample driven into fixture, or with the fixture driven into the sample).   A device for providing indenting into the sample or part of the sample.   A source of light for directing at the sample surface, for example infra-red light produced from a suitable source.   An LED light source for various applications.   A light detector or light transmission device such as a lens of fibre optic cable either the application of light to the sample surface or the collection of light from the sample surface.   A laser (for example a laser diode) for applying laser light to the sample surface.   An assembly containing 1 or more electrical contacting elements for the purpose of either providing electrical signals to the sample surface or collecting signals from the sample surface.   An electrically biased ring structure (positive or negative bias) for the purpose of accelerating or retarding the speed of signals or products from the sample surface   A combination element of electrical contacts an optical elements for the purpose of measuring (or providing) electrical signals in parallel with optical signals (for example powering a local device and collecting any emitted light signals produced (or measuring changes in the behaviour of a device by providing it with an optical energy.   A heating or cooling element that may be brought in contact or close proximity to the surface of a sample or piece of sample.   A physical structure for concentrating the flow of an injected gas in a specific way, or for restricting or modifying the normal gas dissipation.   A system for delivering electrons to the sample surface for various applications (such as charge neutralisation or reduction or injection).   An x-ray collector, with or without an material component which may produce x-rays when excited by an incident charged particle beam   A cryogenic probe.   A mini/micro collection screen, with or without an imaging camera.   An electron detector such as an MCP, or an electron multiplier (for the collection of electrons or ions from the sample at a local location) the detector or multiplier may be above, to the side or underneath the sample or part of sample concerned.   A magnet or magnetic probe for various applications.   An electromagnet or probe for various applications.   Attachments for drilling or cutting parts of a sample.       
 
         [0055]    It will, therefore, be appreciated that embodiments of the present invention provide an apparatus that allows samples to be manipulated within a charged particle instrument, with lower complexity and cost compared to existing solutions.