A large scale, 50x20 crossbar switch block (CSB) is newly developed for a nonvolatile, highly-dense reconfigurable logic. A compact two-varistors selected complementary atom switch (a.k.a. via-switch) is placed at each cross-point, in which the two control lines connected to the varistors can realize the multiple fan-outs without select transistors. The improved a-Si/SiN/a-Si varistor with a novel triple layered SiN shows superior nonlinearity (NL) of 1.1x10(5) with J(max)=1.63MA/cm(2) while keeping very low static power of 0.2 mu W for the CSB. The developed CSB is also applicable for nonvolatile configuration memory for look up tables (LUTs) as well as routing switches used in low power reconfigurable logic.