An electron-beam exposure system is constructed using electromagnetic lenses, apertures and an electron-beam mask, which are arranged and aligned in line between an electron source and a substrate. Within a trajectory of an electron beam that is radiated from the electron source and is then irradiated onto the substrate, crossover planes emerge with respect to electrons of the electron beam. The electron-beam mask is arranged at one crossover plane, while the aperture is arranged at another crossover plane. In addition, one aperture is an object aperture that narrows down the electron beam in sectional shape and size. The electron source is designed to bring a specific electron-beam intensity distribution in which electrons corresponding to periphery in section of the electron beam is made higher in intensity than electrons corresponding to a center portion in section of the electron beam, wherein a zonal-annular projection portion is formed to surround a center portion of a radiation surface of the electron source. To perform oblique illumination in which the electron beam is incident on the substrate in an oblique manner, the system is equipped with a modified object aperture, at the crossover plane, which is constructed by a center shield member for cutting off electrons having small beam incident semi-angles and a ring opening portion for selectively transmitting electrons having large beam incident semi-angles. Thus, it is possible to reduce Coulomb effect, and it is possible to improve resolution and throughput in manufacture of integrated circuits.
Methods and devices are disclosed for controlling blur resulting from the space-charge effect and geometrical aberration in a charged-particle-beam microlithography apparatus. Based on the pattern-element densities of the exposure units to be transferred to the substrate, a relationship between the total blur and the beam semi-angle, the current density, and/or the beam-acceleration voltage is determined. An optimal beam semi-angle, current density, and/or beam-acceleration voltage is calculated to: (1) minimize the blur during the transfer-exposure of an exposure unit having a certain pattern-element density; (2) make the blur constant during the transfer-exposure of a group of exposure units having various pattern-element densities; or (3) maximize the patterned-beam current during the transfer-exposure of an exposure unit having a certain pattern-element density and blur tolerance. The beam semi-angle, current density, and/or acceleration voltage of the CPB-optical system is then adjusted to the calculated value.
A stencil-scattering mask for e-beam lithography includes four complementary sub-field reticles, each of which is exposed with one fourth of the total dose. "Doughnut" stencil shapes have four different patterns of struts, so that an area that is blocked by a strut in one shape is exposed in three other shapes.
The present invention describes an aperture comprising an opaque plate with a central opening and at least one peripheral opening and a method for combining an on-axis component and at least one off-axis component of illumination light.
A method and system is disclosed for directing charged particles on predetermined areas on a target semiconductor substrate. After aligning a wafer mask with a semiconductor wafer, with the wafer mask having one or more mask patterns thereon, the charged particles are directed to pass through the mask patterns to land on one or more selected areas on the semiconductor wafer.
For producing an exposure pattern on a resist material layer on a substrate, a mask having a pattern of transparent structures is illuminated with a beam of energetic radiation and the structure pattern is imaged onto the substrate by means of the structured beam within a pattern transfer system such as an ion-beam lithography system. The pattern image produced on the substrate is shifted laterally with respect to the substrate between a plurality of predetermined shift positions and with each shift position the substrate is irradiated for a predetermined time, wherein the width of lateral displacements is smaller than the minimum feature size of the exposure pattern, the blur as determined by the pattern transfer system is not smaller than the width of lateral displacements, and the dimension and/or direction of the structure patterns are incongruent with respect to the lateral displacements. Thus on the substrate, the exposures superpose into a spatial distribution of exposure dose which exceeds the specific minimum exposure dose of the resist material only within the desired regions of the exposure pattern.
