0.10 mu m dense hole pattern formation by double exposure utilizing alternating phase shift mask using KrF excimer laser as exposure light

Dense 0.10 mu m hole pattern formation is achieved by optical Lithography w ith a KrF excimer laser. A Double exposure utilizing two alternating Phase shift masks (PSMs) of the line-and-space (L/S) pattern laid Out in differen t directions produces a dense and small hole image in bright field with lar ge focus and exposure latitude. Applying this method with a KrF excimer las er stepper and a chemically amplified negative-tone resist, a two-dimension al (2-D) 0.10 mu m hole, array with 0.40 mu m pitch is resolved with a 0.6 mu m depth of focus (DOF). The hell diameter and pitch in the. resolution l imit seem to be less than 0.10 mu m and 0.28 pm, respectively. Also, 2-D ho le arrays with different pitches in the x and y directions are easily forme d using masks with different pitches in each direction. The hole pattern of an actual DRAM;cell is successfully formed by this method. Because df the excellent; patterning performance, this method will enable the fabrication. of multi giga bit DRAMs by KrF excimer laser lithography.