A non-volatile semiconductor memory device includes a first memory bank, a second memory bank, a first power supply circuit, and a second power supply circuit. The transmitting shaft including driving arm is meshed with the motor. The pressing plate is movable in the vertical direction and can lower to the holding table to press a resist film on the substrate from above. The densification treatment is particularly suitable for silicon-oxygen-carbon low dielectric constant films that have been deposited at low temperature. At least in one layer a permeability area which is permeable to moisture is provided through which the cover can be moistened in a controlled way.