Design of the 30 nm FinFETs and Double Gate MOSFETs with the halo structure for suppressing the threshold voltage roll-off and improving the subthreshold swing at the same time is proposed for the first time. The performances of nano scale FinFETs and Double Gate MOSFETs with the halo structure are analyzed using a two-dimensional device simulator. The device characteristics, focusing especially on the threshold voltage and subthreshold slope, are investigated for the different gate length, body thickness, and halo impurity concentration. From the viewpoint of body potential control, it is made clear on how to design the halo structure to suppress the short channel effects and improve the subthreshold-slope. It is shown that by introducing the halo structure to FinFETs and Double Gate MOSFETs, nano-scale FinFETs and Double Gate MOSFETs achieve an improved S-factor and suppressed threshold voltage Vth roll-off simultaneously.

Recent technical trends of electrically programmable ROM (E-PROM) and electrically erasable and programmable PROM (EE-PROM) are reviewed in this paper. The reduction of the cell size and high speed access have been realized by the several breakthroughs of the device structure. The invention of the Flash EE-PROM makes the cell size same as that of E-PROM. Therefore, the bit capacity of Flash EE-PROM is supposed to be quadrupled every three years, same as DRAM's and E-PROM's scaling speed. Furthermore, the much higher density EE-PROM can be realized by the use of the NAND EE-PROM, recently. The invention of the NAND EE-PROM has enabled the semiconductor device engineers to replace the magnetic memory with Si device in very near future.

The data retention characteristics of a Flash memory cell with a self-aligned double poly-Si stacked structure have been drastically improved by applying a bi-polarity write and erase technology which uses uniform Fowler-Nordheim tunneling over the whole channel area both during write and erase. It is clarified experimentally that the detrapping of electrons from the gate oxide to the substrate results in an extended retention time. A bi-polarity write and erase technology also guarantees a wide cell threshold voltage window even after 106 write/erase cycles. This technology results in a highly reliable EEPROM with an extended data retention time.

A new reference voltage generator for megabit DRAMs is proposed. The supply voltage dependence of the generator is successfully suppressed in comparison with the conventional reference voltage circuit. It is shown that the Vcc Margin of DRAM operation can be noticeably improved by using this generator.

This paper presents the history of Flash memories and the basic concept of their functions and also reviews a variety of Flash EEPROM's so far. As Flash memories have two influential features, non-volatility and low cost per bit, they are expected to become a driving force after DRAM's to support the semiconductor industry for the next thirty years, replacing hard and floppy disks which have a large market.

The excellent performance of the 10 nm gate Multi-Nano-Pillar type (M-) Vertical MOSFET has been numerically shown for the first time. It is made clear that the M-Vertical MOSFET, in comparison with the conventional Single Pillar type (S-) Vertical MOSFET, has achieved an increased driving current by more than 2 times, a nearly ideal S-factor, and a suppressed cutoff-leakage current by less than 1/60 by suppressing both the short channel effect and the DIBL effect. Moreover, mechanisms of these improvements of the M-Vertical MOSFET are made clear. From all of the above, it is shown that the M-Vertical MOSFET is a key device candidate for future high speed and low power LSI's in the sub-10 nm generation.

A new, simple test circuit for measuring the threshold voltage distribution of flash EEPROM cell transistors is described. This circuit makes it possible to perform a reliability test for a large number of memory cell transistors with easy static operation because it reduces the measuring time drastically. In addition, this circuit can measure the highest and lowest thresh-old voltages of memory cell transistors easily. This method is suitable for performing the reliability test, such as program/erase endurance test and data retention test, for a large number of flash memory cell transistors. The usefulness of this new test circuit has been confirmed by applying it to 64 Kbit NAND-type flash memory cell array.