Position measurement apparatus, charged particle beam writing apparatus, and mark position measurement method

A mark position measurement method, comprising:

• searching for a position of an uneven mark on a surface of a target object placed on a stage and having the uneven mark with a concave surface and a convex surface formed of a same material by calculating the position of the uneven mark using a height position distribution of the surface of the target object as height information of the surface of the target object, the height position distribution of the surface of the target object being obtained by performing a scan with laser light so as to cross the uneven mark using a sensor having a light projector for making the laser light having a predetermined light intensity distribution and having a diameter larger than a width of the uneven mark obliquely incident on the surface of the target object and a light receiver for receiving reflected light from the target object due to emission of the laser light and outputting the height information of the surface of the target object while moving the target object and generated by a relative positional relationship between the predetermined light intensity distribution and the uneven mark;
• and
• measuring the position of the uneven mark by scanning the uneven mark with an electron beam after moving the stage to a position where the uneven mark is irradiated with the electron beam using information on a searched position of the uneven mark.