Hitachi, Ltd.

Hitachi Ulsi Systems Co., Ltd.

Other

Hitachi Ulsi Engineering Corp.

Yousuke Tanaka

Masatoshi Hasegawa

Tomofumi Hokari

Kenichi Tajima

Hiroshi Akasaki

Tadahiro Obara

Kazuhiko Kajigaya

Seiji Narui

Shinichi Miyatake

Toru Kobayashi

Masayuki Nakamura

Yuji Yokoyama

Shuichi Kubouchi

Shuichi Miyaoka

Masahiro Katayama

A DRAM whose operation is sped up and power consumption is reduced is provided. A pair of precharge MOSFETs for supplying a precharge voltage to a pair of input/output nodes of a CMOS sense amplifier is provided; the pair of input/output nodes are connected to a complementary bit-line pair via a selection switch MOSFET; a first equalize MOSFET is provided between the complementary bit-line pair for equalizing them; a memory cell is provided between one of the complementary bit-line pair and a word line intersecting with it; gate insulators of the selection switch MOSFETs and first equalize MOSFET are formed by first film thickness; a gate insulator of the precharge MOSFET is formed by second film thickness thinner than the first film thickness; a precharge signal corresponding to a power supply voltage is supplied to the precharge MOSFET; and an equalize signal and a selection signal corresponding to a boost voltage are supplied to the first equalize MOSFET and the selection switch MOSFET, respectively.

Semiconductor integrated circuit device

A semiconductor memory device capable of improving the reliability when driving a word line and capable of reducing the access delay due to the defect relief is provided. In order to prevent the multiple selection of a sub-word line of a normal memory mat and a sub-word line of a redundant memory mat, the start of the redundant memory mat is delayed from that of the normal memory mat, and in order to compensate the start delay, the shared circuit is eliminated and the bit line length is reduced in the redundant memory mat. By doing so, the read time of the bit lines is reduced and the signal amount is increased. Consequently, the same activation timing of the sense amplifier as that of the normal memory mat can be used also in the redundant memory mat.

Semiconductor memory device

A semiconductor integrated circuit device equipped with a memory circuit, which realizes the speeding up of its operation and low power consumption in a simple configuration is provided. At input/output nodes of a sense amplifier including a CMOS latch circuit for performing an amplifying operation in response to an operation timing signal, a pair of first precharge MOSFETs brought to an on state during a precharge period to supply a precharge voltage, and select switch MOSFETs for connecting the input/output nodes and each complementary bit line pair in response to a select signal are provided. A second precharge MOSFET for short-circuiting the complementary bit line pair is provided between the complementary bit line pair. A memory array is provided which includes dynamic memory cells each comprising an address selecting MOSFET and a storage capacitor, each of which is provided between one of the complementary bit line pair and a word line intersecting it. The thickness of a gate insulating film for the second precharge MOSFET is formed thin as compared with that of a gate insulating film for the selecting MOSFETs.

Semiconductor memory device operating at high speed and low power consumption

The present invention provides a dynamic RAM which can be operated at a low voltage and realizes the enhancement of a read margin and an area-saving layout. In a memory array including a plurality of memory cells having capacitors which are formed corresponding to a plurality of word lines and a plurality of bit lines, stored information of the memory cell which is read to one bit line out of the pair of bit lines is sensed by a sense amplifier in response to a reference voltage which is formed by a dummy cell connected to another bit line, a precharge voltage of high level or low level corresponding to an operational voltage by a precharge circuit is supplied to the bit lines, and the dummy cells having the same structure as the memory cells are formed at crossing points of word lines for dummy cells and bit lines arranged outside the memory array, MOSFETs which precharge an intermediate voltage between the high level voltage and the low level voltage to the capacitors are provided, and gates of the MOSFETs are connected with charge word lines for dummy cells which are extended in parallel with the word lines for dummy cells.

Disclosed herein is a semiconductor integrated circuit device equipped with a memory circuit, which realizes the speeding up of its operation and low power consumption thereof in a simple configuration. At input/output nodes of a sense amplifier including a CMOS latch circuit for performing an amplifying operation in response to an operation timing signal, a pair of first precharge MOSFETs brought to an on state during a precharge period to thereby supply a precharge voltage, and select switch MOSFETs for connecting the input/output nodes and each complementary bit line pair in response to a select signal are provided. A second precharge MOSFET for short-circuiting the complementary bit line pair is provided between the complementary bit line pair. A memory array is provided which includes dynamic memory cells each comprising an address selecting MOSFET and a storage capacitor, each of which is provided between one of the complementary bit line pair and a word line intersecting it. The thickness of a gate insulating film for the second precharge MOSFET is formed thin as compared with that of a gate insulating film for the selecting MOSFETs.

Semiconductor integrated circuit device operating at high speed and low power consumption

The column address strobe signal (CAS) which is changed in cycles as many as a plurality of times that of a clock signal cycle is input to the memory block (MBK to MBKn). A plurality of serial data readout from the memory cell array ( ) and parallel/serial converted by a parallel/serial converter circuit ( ) in synchronism with a clock signal cycle are output for every cycle when the column address signal (CASADR) is changed. Parallel data input to the memory block and serial/parallel converted by a serial/parallel converter circuit ( ) in synchronism with the clock signal cycle are written in the memory cell array. In this way, the access specification that the column address strobe signal is varied once per n cycles of the clock signal allows for a more rapid memory operation.

High speed clock synchronous semiconductor memory in which the column address strobe signal is varied in accordance with a clock signal

In a dynamic RAM having a memory cell array in which a dynamic memory cell is arranged at an intersection between a word line and one of a pair of bit lines, a select level signal corresponding to a supply voltage and an unselect level signal corresponding to a negative potential lower than circuit ground potential are supplied to the word line. A signal of a memory cell read to the pair of bit lines by a sense amplifier that operates on the circuit ground potential and an internal voltage formed by dropping the supply voltage by an amount equivalent to the threshold voltage of the address select MOSFET is amplified. The dynamic RAM has an oscillator that receives the supply voltage and circuit ground potential and a circuit that receives an oscillation pulse generated by the oscillator to generate the negative potential.

Growing community of inventors

Ome, Japan

Yousuke Tanaka