Charged particle beam apparatus for measuring magnetic field

A method of measuring a magnetic field, comprising the steps of:

• transmitting a charged particle beam through a reference specimen, forming an image from the charged particle beam with a desired magnification and detecting a first image;
• storing the first image detected;
• passing the charged particle beam through a region containing a magnetic field to be measured, forming an image with a desired magnification from the charged particle beam deflected by the magnetic field to be measured, and detecting a second image;
• storing the second image detected;
• processing the first image and the second image stored and determining the displacement of the charged particle beam;
• and
• determining the magnetic field distribution to be measured in space by calculations based on the displacement,
• wherein said image processing is a digital matching operation;
• and,
• wherein said digital matching operation includes the steps of extracting a third image having a predetermined size from the first image, overlapping the third image and the second image and adding the differences of bright values of corresponding pixels in each of overlap regions, determining an overlap point of the third image and the second image associated with the minimum value of the sum, and determining the displacement of the charged particle beam from the overlap point thus determined.

A method of measuring a magnetic field comprising the steps of:

• transmitting a charged particle beam through a reference specimen, forming an image from the charged particle beam with a desired magnification and detecting a first image;
• storing the first image detected;
• passing the charged particle beam through a region containing a magnetic field to be measured, forming an image with a desired magnification from the charged particle beam deflected by the magnetic field to be measured, and detecting a second image;
• storing the second image detected;
• processing the first image and the second image stored and determining the displacement of the charged particle beam;
• and
• determining the magnetic field distribution to be measured in space by calculations based on the displacement,
• wherein said image processing is a digital matching operation;
• and,
• wherein said digital matching operation includes the steps of quantizing the first image and the second image by a finite number of pixels respectively and sampling the data of bright values of each pixel with at least one bit.

A method of measuring a magnetic field, comprising the steps of:

• transmitting a charged particle beam through a reference specimen, forming an image from the charged particle beam with a desired magnification and detecting a first image;
• storing the first image detected;
• passing the charged particle beam through a region containing a magnetic field to be measured, forming an image with a desired magnification from the charged particle beam deflected by the magnetic field to be measured, and detecting a second image;
• storing the second image detected;
• processing the first image and the second image stored and determining the displacement of the charged particle beam;
• and
• determining the magnetic field distribution to be measured in space by calculations based on the displacement,
• wherein said image processing is a digital matching operation;
• and,
• wherein said digital matching operation includes the steps of extracting a third image having a predetermined size from the second image and overlapping the third image thus extracted and the first image, said method further comprising selected one of the steps of overlapping the extracted third image and the first image thereby to calculate the cross-correlation efficient and adding the differences of bright values of corresponding pixels in an overlap region.

A charged particle beam apparatus comprising:

• means for generating a charged particle beam;
• means for focusing the charged particle beam;
• a reference specimen through which the charged particle beam is transmitted for forming an image, said reference specimen being located between said means for generating a charged particle beam and a specimen for generating a magnetic field to be measured;
• a holder for mounting said reference specimen;
• a stage for arranging at a desired position the specimen for generating a magnetic field to be measured;
• means for adjusting the image of said reference specimen formed by the transmission of the charged particle beam with a desired magnification;
• means for detecting an image of the reference specimen adjusted to the desired magnification;
• means for storing an image of said reference specimen detected;
• means for processing the image of said reference specimen stored;
• and,
• means for determining a magnetic field to be measured in space from the result of image processing.

A charged particle beam apparatus comprising:

• means for generating a charged particle beam;
• a reference specimen;
• a lens system;
• a holder for holding a specimen;
• and,
• detecting means including a two-dimensional image pickup device and an image processing section for detecting information of an image included in said charged particle beam which arrives at said means for detecting through said lens system;
• wherein the charged particle beam passes through the reference specimen before irradiating the specimen held by said holder;
• wherein a magnetic field providing an object of measurement is arranged in a route of the charged particle beam;
• wherein said charged particle beam has a finite diameter when passing through said magnetic field and includes a brightness pattern of a brightness contrast corresponding to a projected image of said reference specimen;
• wherein an imaging position of said brightness pattern is changed with respect to a position of said magnetic field by adjusting said lens system, so that a plurality of brightness patterns are obtained;
• wherein said brightness patterns are detected by said two-dimensional pickup device;
• wherein deflection angles of said charged particle beam are determined by calculations in said image processing section by using information of said brightness patterns;
• and,
• wherein a magnetic field in space is determined by calculations based on said deflection angles.