Microscopy imaging method and system

• US 9,633,819 B2
• Filed: 05/14/2012
• Issued: 04/25/2017
• Est. Priority Date: 05/13/2011
• Status: Active Grant

• Current Assignee: Fibics Incorporated
• Original Assignee: Fibics Incorporated
• Inventors: Phaneuf, Michael William, Lagarec, Ken Guillaume
• Primary Examiner(s): Patel, Jay
• Assistant Examiner(s): Habib, Irfan
• Application Number:
  US14/117,256
• Publication Number:
  US 20140226003A1
• Time in Patent Office: 1,807 Days
• CPC Class Codes: G06T 2207/10061 from scanning electron microscope
• CPC Class Codes: H01J 2237/226 Image reconstruction
• CPC Class Codes: H01J 2237/2811 Large objects
• CPC Class Codes: H01J 2237/3174 Etching microareas
• CPC Class Codes: H01J 2237/31749 Focused ion beam
• CPC Class Codes: H01J 37/222 Image processing arrangements associated with the tube
• CPC Class Codes: H01J 37/26 Electron or ion microscopes; Electron or ion diffraction tubes
• CPC Class Codes: H01J 37/28 with scanning beams H01J37/268, H01J37/292, H01J37/2955 take precedence
• CPC Class Codes: H01J 37/3005 Observing the objects or the point of impact on the object
• CPC Class Codes: H01J 37/304 Controlling tubes by information coming from the objects or from the beam, e.g. correction signals
• CPC Class Codes: H01J 37/3045 Object or beam position registration
• CPC Class Codes: H01J 37/3056 for microworking, e. g. etching of gratings or trimming of electrical components

Abstract

Generally, the present disclosure provides a method and system for improving imaging efficiency for CPB systems while maintaining or improving imaging accuracy over prior CPB systems. A large field of view image of a sample is acquired at a low resolution and thus, at high speed. The low resolution level is selected to be sufficient for an operator to visually identify structures or areas of interest on the low resolution image. The operator can select one or more small areas of arbitrary shape and size on the low resolution image, referred to as an exact region of interest (XROI). The outline of the XROI is mapped to an x-y coordinate system of the image, and the CPB system is then controlled to acquire a high resolution image of only the XROI identified on the low resolution image. For 3D imaging, once the XROI is identified, each section of the sample can be iteratively imaged in the previously described manner, with the operator having the option to redefine the XROI later.

Claims

1. A selective high resolution imaging method for a charged particle beam apparatus, comprising:

acquiring and displaying a sample area image of a sample at a first resolution on a display;

scanning at least one exact region of interest in the sample area image defined by an arbitrary outline positioned on the sample area image, including

receiving the arbitrary outline corresponding to the at least one exact region of interest in the sample area and receiving a second arbitrary outline corresponding to a second exact region of interest positioned on the sample area image,

mapping the arbitrary outline to a coordinate system of the sample area impage,

generating a raster pattern for directing a beam in response to the arbitrary outline, and

rastering the beam at a position of the sample corresponding to the arbitrary outline and within an area defined by the arbitrary outline;

acquiring an image of the at least one exact region of interest at a second resolution greater than the first resolution;

overlaying the image of the at least one exact region of interest at the second resolution, over the arbitrary outline positioned on the sample area image;

sectioning the sample to expose a new sample surface after acquiring and displaying the image of the at least one exact region of interest;

scanning the at least one exact region of interest of the new sample surface, acquiring and displaying another image of the at least one exact region of interest of the new sample surface at a second resolution greater than the first resolution, wherein a sequence of sectioning, scanning, acquiring and displaying is executed iteratively until a request for a new sample area image at a first resolution is received.

2. The method of claim 1, wherein receiving the request for a new sample area image includes receiving a new arbitrary outline corresponding to a different exact region of interest in the new sample area image.

3. The method of claim 2, wherein receiving the new arbitrary outline includes modifying the arbitrary outline.

4. The method of claim 1, wherein a focused ion beam is operated to section the sample by advancing the focused ion beam to a predetermined position and rastering the focused ion beam along a line.

5. The method of claim 4, wherein advancing the focused ion beam includes

generating a primary digital code corresponding to a primary deflection voltage for moving a position of the focused ion beam,

generating at least one additional digital code proximate to the primary digital code for generating a secondary deflection voltage, and

averaging the primary deflection voltage and the secondary deflection voltage to provide a final deflection voltage.

6. The method of claim 5, wherein the at least one additional digital code is one step greater than or less than the primary digital code, or two steps greater than or less than the primary digital code.

7. The method of claim 4 including determining a thickness of the sectioned portion of the sample by comparing a first distance between a pair of notches in a current image of the sample surface with a second distance between another pair of notches in a previous image of the sample surface.

8. The method of claim 7 further including comparing the thickness of the sectioned portion of the sample to a desired cross section thickness, and adjusting a milling rate of the focused ion beam.

9. The method of claim 1, further including

executing at least one correlative technique to obtain corresponding data, and

mapping said corresponding data to the sample area image for display.

10. The method of claim 9, wherein the at least one correlative technique includes optical microscopy based image capture.

11. The method of claim 1, further including

acquiring a second image of the second exact region of interest at the second resolution, and

overlaying the second image over the second arbitrary outline positioned on the sample area image.