Homogeneous Illumination of Electron Beam Transmission Masks
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-03
A transmission mask for electron beam lithography is repeatedly scanned by an electron beam, the diameter of which is small in relation to the mask size and which is offset for each scan by a distance W from the previous scanning path to compensate for inhomogeneous intensity distributions across the beam diameter. Fig. 1 shows a transmission mask with two complementary patterns 1, 2 (as described in U.S. Patent 4,169,230). Pattern 1 to be projected onto a photoresist-covered substrate is scanned along a meander path 4 by an electron beam in the form of a hexagon 3. The tips of hexagon 3 overlap in the X-direction during scanning to allow small beam displacements without changing the electron dose deposited at the boundaries of the scanning path.