Patent ID: 8718972

Claim:
An electron beam writing apparatus that corrects an image displacement error of an EUV mask based on a back surface shape of the EUV mask and a surface shape of an electrostatic pin chuck contacting the back surface of the EUV mask to hold the EUV mask on the electrostatic pin chuck, said electron beam writing apparatus comprising: a measuring unit that measures flatness of the back surface shape of the EUV mask held on the electrostatic pin chuck; a first storing unit that stores back surface shape data of the EUV mask measured by the measuring unit; a second storing unit that stores surface shape data of the electrostatic pin chuck, comprising shape data of pins of the electrostatic pin chuck based on a relationship with center coordinates of the EUV mask, pitch data between the pins, and chucked region data; a data extraction unit that extracts only a portion of the back surface shape data of the EUV mask using the surface shape data of the electrostatic pin chuck, the extracted portion of the back surface shape data of the EUV mask including only back surface shape data of the EUV mask at positions of the EUV mask that frictionally contact the pins of the electrostatic pin chuck; a first calculating unit that approximates a shape of the EUV mask by a polynomial expression of only the extracted portion of the back surface shape data of the EUV mask extracted by the data extraction unit; a tilt calculating unit that determines a local tilt distribution at back surface of the EUV mask from the polynomial expression that approximates the shape of the EUV mask using only the back surface shape data of the EUV mask at the positions of the EUV mask that frictionally contact the pins of the electrostatic chuck; a second calculating unit that calculates an amount of image displacement error based on the determined local tilt distribution and a predetermined amount of distortion where the back surface of the EUV mask is held by the electrostatic pin chuck when a pattern is written onto a front surface of the EUV mask; a coefficient calculating unit that obtains a coefficient, by computation of another polynomial expression that indicates an amount of deformation of the EUV mask surface when flat correction is performed on the EUV mask by holding the EUV mask with the electrostatic pin chuck while the EUV mask is used in a scanning process; and a third calculating unit that calculates a correction amount to correct the image displacement error of the EUV mask based on the calculated amount of image displacement error, by applying the coefficient.