Wafer alignment method for dual beam system

An alignment method in a charged particle beam apparatus including a stage capable of moving inside an XY plane and in a Z axis direction perpendicular to said XY plane while holding a sample, a first column having an optical axis parallel to said Z axis and a second column having an optical axis inclined to said Z axis, said method comprising steps of:

• moving said stage inside the XY plane and positioning a first known mark on a sample to the visual field center of said first column;
• moving said stage by an offset between the visual field of said first column and the visual field of said second column;
• observing said first known mark by said second column and determining a deviation amount from the visual field center;
• determining a height deviation of the sample from a reference height on the basis of said deviation amount;
• moving said stage by the height deviation in the Z axis direction and adjusting a sample surface provided with said first known mark to said reference height and determining a position of said first known mark;
• moving said stage inside the XY plane while fixing in said Z direction and positioning to a second known mark on the sample;
• and
• determining a position of the second known mark by said second column and achieving Die alignment.

An alignment method in a charged particle beam apparatus including a stage capable of moving inside an XY plane and in a Z axis direction perpendicular to said XY plane while holding a sample, an optical microscope having an optical axis parallel to said Z axis, a first column having an optical axis inclined at 45° with respect to said Z axis inside a YZ plane and a second column having an optical axis inclined at 45° with respect to said Z axis inside an XZ plane, said method comprising steps of:

• moving said stage inside the XY plane and positioning a known mark on a sample to the visual field center of said optical microscope;
• moving said stage by a difference between the stage coordinates of said first known mark by said optical microscope and the stage coordinates of said first known mark by said first column;
• observing said first known mark by said first column and calculating a deviation amount ΔY from the visual field center in the Y direction;
• moving said stage by −√2·ΔY in the Z axis direction and adjusting the sample surface on which said first known mark is disposed to a reference height and determining a position of said first known mark;
• moving said stage inside the XY plane while fixing in said Z direction and positioning to a first known mark on the sample;
• and
• determining a position of the first known mark by said first column and achieving Die alignment.