A floating gate B4-flash memory cell technology, which provides high speed programming with excellent programming efficiency for NOR architecture, has been developed. We have reported a pchannel SONOS type B4-flash cell utilizing novel Back Bias assisted Band-to-Band tunneling induced Hot-Electron(B4-HE) injection. This paper demonstrates that B4-HE injection programming scheme can be easily evolved to a floating gate cell. By applying a moderate back bias to the cell during programming, the bit-line voltage can be reduced below the supply voltage, 1.8V. As a result, B4-flash can achieves high speed programming comparable to conventional NOR and high programming efficiency comparable to NAND flash at the same time. Basic operations of the floating gate B4-flash cells have been investigated. It is also confirmed that B4-HE injection programming provides very weak temperature dependency in comparison with CHE and FN injection, and does not have a negative impact to its reliability.