| 摘要 |
PURPOSE:To contrive uniform illumination by dividing a luminous flux from a light source by an optical member into a plurality, and feeding it through rounding circuit means between the optical members to provide an optical path difference of luminous flux distance or longer between each luminous flux. CONSTITUTION:A luminous flux from a light source is divided into luminous flux B1 and flux B2 by a member 9, rounded by mirrors R1, R2, reflected on a mirror 10, and the flux B1 and flux B2 are used for illumination. A distance l1 between the member 9 and the mirror R1 and a distance l2 between the mirror R2 and the mirror 10 are selected to give an optical path length l1+l2 longer by coherent length than l1-l2 between the flux B1 and flux B2. The diameters of similar luminous flux B1 to flux Bn are contracted by a lens 3, converged to the focal surface of a plurality of fine lenses of the lens 5 to form the secondary light source surface 6. A reticle R is emitted with luminous flux from the surface 6 by a condenser lens 7, and projected at 8 on a wafer W. With this construction, noncoherent point light source is formed in the vicinity to prevent the irregular illumination on the mask and the wafer, thereby obtaining an exposure device of high resolution. |
