Robust SERS substrates with hotspots on a large scale from massive nanogaps can be fabricated by assembling Ag nanocubes on the massed Ag mirror via 1,2-ethanedithiol monolayer as linkage and ultrathin spacer. X-ray spectroscopy was used to confirm the existence of nanogaps. The plasmonic interaction between Ag nanocubes and the massed Ag mirror was corroborated by UV-Vis spectra. The strength and frequency change of plasmon resonance indicates the electrical field coupling between Ag nanocubes and the massed Ag surface. The 1,2-ethanedithiol spacer prevents the plasmon quench from complete contact between Ag nanocubes and the massed Ag surface, being corroborated by both simulations and SERS results. The SERS results prove the supreme performance of the robust substrate by detecting 10(-9) M rhodamine 6G solution with high sensitivity (analytical enhancement factor 2.8 x 10(8)), high reliability (6.6% standard deviation from 20-sites measurements), and high precision (calibration line with 99.9% correlation coefficient). (C) 2013 Elsevier B.V. All rights reserved.