US Patent 7586786 Nonvolatile semiconductor memory

A method of reading out data from nonvolatile semiconductor memory including the steps of applying a first voltage to a bit line contact; applying a second voltage to a source line contact, wherein the second voltage is substantially smaller than the first voltage; applying a third voltage gates of third and fourth select gate transistors, the third voltage configured to bring the third and fourth select gate transistors into conduction; applying a fourth voltage to gates of the plurality of memory cell transistors of a second memory cell unit, the fourth voltage configured to bring the plurality of memory cell transistors of the second memory cell unit into conduction or not, depending on the data that is stored in the memory cell unit; and applying a fifth voltage to gates of the plurality of memory cell transistors of a first memory cell unit, the fifth voltage configured to bring the plurality of memory cell transistors of the first memory cell unit into conduction; wherein the fifth voltage is bigger than the fourth voltage.