A substrate bonding apparatus for bonding substrates together in a vacuum at high speeds, with a high degree of accuracy includes a first chamber C 1, where two substrates are loaded before to be bonded together , a second chamber C 2, where two substrates bonded together, and a third chamber C 3, where the two substrates are unloaded after bonded together. The first and third chambers are variably controlled from an atmospheric pressure state to a medium vacuum state. The second chamber is variably controlled from the medium vacuum state to a high vacuum state. |