High contrast chemically amplified 193 nm resist for gigabit dynamic random access memory generation

Abstract

Four Gb dynamic access random memory (DRAM) cell patterns which have a 0.12 μm design rule were demonstrated by using a high contrast chemically amplified 193 nm positive resist and high resolution exposure. All critical layers of 4 Gb DRAM, such as isolation, word line, contact hole, bit line, and storage node, were successfully resolved with suitable focus margin. The dissolution contrast of the resist film and the slope of dissolution rate curve were much higher than those of conventional polyhydroxystyrene based chemically amplified KrF positive resist. Moreover, the dry etch resistance of the resist film for both the polysilicon etch and the oxide etch was better than those of KrF resist. These results indicated that this resist material has enough potential for practical use. Furthermore, the resist profile simulation showed that mass production of 4 Gb DRAMs can be achieved by a combination of a high contrast resist and a higher numerical aperture lens under annular illumination.