Charged particle beam device, autofocus processing method of charged particle beam device, and detector

A charged particle beam device comprising:

• an electron optics system;
• a stage;
• a sample chamber holding a sample between a first insulating layer and a second insulating layer facing the first insulating layer, and including a conductive layer formed on the first insulating layer;
• a first signal detection circuit connected to the conductive layer and detecting a current flowing through the conductive layer;
• and
• a second signal detection circuit including a detection electrode providing a reference potential and arranged to face the sample across the second insulating layer, and detecting an electric signal generated in the detection electrode;
• and
• a main control unit for controlling the electron optics system and the stage, wherein
• the main control unit irradiates the conductive layer of the sample chamber placed on the stage with an electron beam from the electron optics system, and is input with a first detection signal from the first signal detection circuit and a second detection signal from the second signal detection circuit.

A charged particle beam device comprising:

• an electron optics system placed on a column;
• a stage placed in a sample chamber with a vacuum degree lower than that of the column;
• a vacuum membrane holder including a membrane including an insulating layer and a conductive layer;
• a signal detection circuit connected to the conductive layer and detecting a current flowing through the conductive layer;
• and
• a main control unit for controlling the electron optics system and the stage, wherein
• the column and the sample chamber are connected via the vacuum membrane holder, and
• in the main control unit, a sample placed on the stage is irradiated with an electron beam from the electron optics system through the membrane, and a detection signal from the signal detection circuit is input.

An autofocus processing method of a charged particle beam device including an electron optics system, a stage, a main control unit for controlling the electron optics system and the stage, and a computer performing image processing, the method comprising:

• placing a sample chamber that includes a first insulating layer that is in contact with a sample, an outer frame portion that supports the first insulating layer and includes a window portion recessed in an inverted pyramid shape, and a conductive layer, on the stage, wherein the conductive layer is formed on the first insulating layer in an inner region which is the bottom surface of the window portion, and is formed on the outer frame portion in other than the inner region,
• connecting a signal detection circuit connected to the conductive layer and detecting a current flowing through the conductive layer, to the main control unit,
• in the main control unit, scanning an electron beam with respect to a region including the window portion by the electron optics system, and converting a detection signal from the signal detection circuit into first pixel gradation data of a low-magnification image according to the intensity thereof for each deflection position of the electron beam to the sample chamber,
• in the computer, performing image processing on the low-magnification image acquired from the first pixel gradation data, and acquiring the position coordinates of a rectangular area including one vertex of the internal region and an inclined surface of the window portion in contact with one vertex of the internal region,
• in the main control unit, moving the field of view so that the rectangular region becomes the center, scanning an electron beam at a predetermined observation magnification by the electron optics system, and converting a detection signal from the signal detection circuit into second pixel gradation data of a high-magnification image according to the intensity thereof for each deflection position of the electron beam to the sample chamber, and
• in the computer, performing image processing on the high-magnification image acquired from the second pixel gradation data, calculating a sharpness evaluation value, and determining the success or failure of autofocus processing based on the sharpness evaluation value.

A detector comprising:

• a vacuum membrane holder including a membrane including an insulating layer and a conductive layer;
• and
• a signal detection circuit connected to the conductive layer and detecting a current flowing through the conductive layer when the conductive layer is irradiated with an electron beam, wherein
• the vacuum membrane holder is arranged between a column where an electron optics system for emitting an electron beam is stored and a sample chamber having a vacuum degree lower than that of the column.