Kabushiki Kaisha Toshiba

Nobuaki Ohtsuka

Junichi Miyamoto

Sumio Tanaka

Shigeru Atsumi

Shinji Saito

Keniti Imamiya

Yumiko Iyama

Masaki Sato

Seiichi Mori

Tadashi Miyakawa

Masao Kuriyama

Kuniyoshi Yoshikawa

Naoto Tomita

Noriaki Suzuki

Imamiya Keniti

A plurality of erase circuits are provided for the blocks BLK(0) to BLK(n), each for one block. Protect circuits are connected to the erase circuits, respectively. The protects circuits generate protect signals PROT0 to PROTn, respectively. Each protect signal indicates whether the protect circuit is set in protect mode or not. Each erase circuit receives the protect signal from the protect circuit connected to it. A unit provided in the erase circuit determines, from the protect signal, whether the protect circuit is set in the protect mode. The unit changes the voltage applied to the sources of the memory cells of the cell block connected to the erase circuit, in accordance with whether the protect circuit is set in the protect mode or not. When a voltage is applied to the sources of the memory cells, a data item of a logic value is read from each memory cell. When a different voltage is applied to the sources of the memory cells, a data item of the other logic value is read from each memory cell. Hence, whether or not the protect circuits are set in protect mode can be determined, without erasing or writing data in the block of the memory cell array.

Nonvolatile semiconductor memory with a protect circuit

A semiconductor memory circuit includes a memory cell array having a plurality of memory cells. Column selection lines constitute connection lines extending from the memory cell array and are divided into hierarchies like a tree by selecting transistors. More specifically, a column selection system is hierarchically divided into column selection lines belonging to a first-stage column decoder and a second-stage column decoder. Row selection lines are controlled by a row decoder. The semiconductor memory circuit also includes an ATD circuit for detecting a transition of an address signal to generate a pulse, a pulse width control circuit for controlling the width of the pulse to determine data in a sense amplifier, and a latch circuit for latching readout data in response to the width of the pulse. A delay circuit is provided in the first-stage column decoder of an upper hierarchy to which a small number of selecting transistors belong and from which a signal rises at high speed. The delay circuit of the first-stage column decoder causes the pulse from the ATD circuit to always operate the latch circuit earlier than the timing of transition of data in the sense amplifier, thereby latching the preceding data.

Semiconductor memory device having a delay circuit for controlling

Word lines are divided into a plurality of blocks in a row direction, and divided into a plurality of sections having e.g., four word lines in a column direction. An area where each block and each section are crossed is used as a sector. One sector includes four word lines. A control gate of a plurality of transistors constituting a memory cell is connected to each of the word lines, each drain is connected to each of the bit lines, and each source is connected to each of source lines in common. A source main decoder is provided in each section, source sub-decoders are provided in each sector. Each source sub-decoder includes each of supply circuits. The source main decoder outputs a sector selection signal in accordance with a row address signal, and a block decoder outputs block selection signals in accordance with a column address signal. One supply circuit is selected by the sector selection signal and the block selection signals, and the selected supply circuit supplies the sector selection signal outputted from the source main decoder source lines as an erase signal.

Nonvolatile semiconductor memory device

A semiconductor integrated circuit includes a circuit block whose operation is controlled by a inverted control signal whose significant potential level is set at a ground potential, and a wiring for transmitting a control signal for controlling the operation of the circuit block. An inverting circuit provided near the circuit block inverts the control signal and then supplies the inverted signal to the circuit block via a wiring. The inverter includes a first capacitor connected between the power source terminal and a node which is set at a high potential level in the inverter circuit when the control signal is set at the non-significant potential level and a second capacitor connected between a ground potential terminal and a node which is set at a ground potential level when the control signal is set at the non-significant potential level.

Semiconductor integrated circuit capable of preventing occurrence of

A bias voltage generating circuit supplies a bias voltage to a memory's bit lines. One end of a first transistor is connected to a first power supply. The first transistor conducts in response to a control signal. A second transistor is connected to another end of the first transistor. Another end of the second transistor and a gate of the second transistor are connected to an output node. One end of a third transistor and a gate connected to the output node. One end of a fourth transistor and a gate are connected to a second end of the third transistor. A second end of the fourth transistor is connected to a second power supply. One end of a fifth transistor is connected to the first power supply. The fifth transistor also conducts in response to the control signal. A sixth transistor is connected to a second end of the fifth transistor. A second end of the sixth transistor is connected to the output node and the gate of the sixth transistor is connected to a potential source. A seventh transistor is connected to the output node. A second end of the seventh transistor is connected to a ground potential. The seventh transistor also conducts in response to the control signal. The output node outputs a bias voltage to the bit lines when the control signal is activated, and is grounded through the seventh transistor when the control signal is non-activated.

Bias voltage generating circuit

The stress applied to a gate insulation film can be reduced by raising the potentials of the source and drain terminals of input gate transistors whose gate are applied with a high potential to a Vcc level or the like, when a programming high potential (V.sub.PP) or a high potential for tri-state control is applied to an external input terminal of an input-stage circuit of an EPROM. Therefore, occurrence of problems of the reliability such as TDDB can be prevented and thus a highly reliable nonvolatile semiconductor memory device can be provided. Further, the elements can be miniaturized to increase the capacity of the nonvolatile semiconductor memory device, without scaling the conventional programming high potential and the high potential for tri-state control.

A semiconductor integrated circuit comprises a first MOS transistor, a capacitor element, a second MOS transistor, and a node. One current path of the first MOS transistor is connected to a first power source, and the gate and the other current path thereof are connected together. The capacitor element is connected between a second power source and the other current path of the first MOS transistor. The second MOS transistor is of the same conductivity type as the first MOS transistor. One current path of the second MOS transistor is connected to the first power source, and the gate thereof is connected to the gate of the first MOS transistor. The node is connected to the other current path of the second MOS transistor. The node is pre-charged at a predetermined potential level by a current flowing from the other current path of the second MOS transistor.

Semiconductor integrated circuit

A nonvolatile semiconductor memory device comprising a power source terminal and a P-channel MOS transistor. A low power-source voltage is applied to the terminal during a read period. The source of the P-channel MOS transistor is coupled to the power source terminal. The conduction of the MOS transistor is controlled by data-writing operation. The drain of the MOS transistor is connected by a node to a plurality of bit lines. The device further comprises a plurality of memory cells and a plurality of N-channel MOS transistor. The memory cells have double-gate structure, each having a source coupled to the ground and a drain coupled to the corresponding bit line. Each N-channel MOS transistor has a source and a drain connected to the ground and the corresponding bit line, respectively, for discharging the bit line. Each N-channel MOS transistor is rendered conductive temporarily when the supply of the high power source voltage to the power source terminal is started, whereby the potential of the corresponding bit line is decreased. The bit-line potential is decreased sufficiently since the P-channel MOS transistors have a conductance greater than that of any other transistor incorporated in the device.

Semiconductor nonvolatile memory device for controlling the potentials

A memory cell array includes data storing memory cells which are arranged in a matrix form of m rows.times.n columns. The data storing memory cells are selected by means of m word lines and n bit lines. Dummy capacitance cells are arranged on the (n+1)th column of the memory cell array, and are connected to the word lines. The dummy capacitance cells are each formed of a transistor which has the same construction as a field transistor having a gate electrode formed of a polysilicon layer or the data storing memory cell and whose source is set in the electrically floating condition. Array edge memory cells are arranged on the (m+1)th row of the memory cell array, and are connected to n bit lines. The array edge memory cells have no influence on the circuit operation. A dummy memory cell is arranged in an intersecting position of the (m+1)th row and the (n+1)th column. A dummy bit line is connected to the dummy capacitance cells and dummy memory cell, and a dummy word line is connected to the array edge memory cell and dummy memory cell.

Cell array pattern layout for EEPROM device

A semiconductor integrated circuit having a test mode in addition to a normal mode, includes a mode detecting circuit for detecting a state of each mode and generating a mode signal, a prebuffer circuit for receiving the mode signal generated by the mode detecting circuit, amplifying an input signal by using an output driving capacity corresponding to the mode signal, and outputting the amplified signal, and an output buffer circuit for receiving an output from the prebuffer circuit and outputting data outside the integrated circuit.

Semiconductor integrated circuit including output buffer

A semiconductor memory device includes a first power source terminal supplied with a first power source voltage for data readout, a second power source terminal supplied with a second power source voltage for data write-in, memory cells formed of a floating gate type MOS transistor, a voltage switching circuit for selectively outputting one of the first and second power source voltages supplied to the first and second power source terminals, a voltage lowering circuit for lowering the second power source voltage supplied to the second power source terminal and outputting the lowered voltage, a gate potential control circuit connected to receive an output voltage of the voltage switching circuit as a power source voltage and supplies an output to the gate of the memory cell, and a drain potential control circuit connected to receive an output voltage of the voltage lowering circuit as a power source voltage and supplies an output to the drain of the memory cell. The second power source voltage for data write-in supplied to the second power source terminal is lowered by the power source voltage lowering circuit and is then supplied to the drain of the memory cell via the drain potential control circuit.

Semiconductor memory device capable of preventing data of non-selected

An improved semiconductor memory device having a memory array, a dummy cell and a redundancy cell column is disclosed. At least one dummy capacity cell is connected to the reference bit line to which the dummy cell is connected, and also to a redundancy bit line to which redundancy cells are connected. Therefore, since a capacity on the reference bit line is roughly equalized to that on the redundancy bit line by these dummy capacity cells, it is possible to prevent erroneous potential level determination by a sense amplifier for comparing both the potentials on both the bit lines, without being subjected to the influence of supply voltage fluctuations.

Redundant semiconductor memory device

In a nonvolatile semiconductor memory, a plurality of nonvolatile semiconductor memory cells are arranged in a matrix form. Each of the memory cells is connected to a corresponding one of a plurality of bit lines and to a corresponding one of a plurality of word lines. The ends of the bit lines are commonly connected to a programming transistor for setting a programming mode through transistors for selecting the bit lines. The transistors are connected to column decoders and the word lines are connected to a row decoder. Furthermore, the other ends of the bit lines are connected to a common connecting line through transistors for setting a test mode and the common connecting line is connected to a node between the test mode transistors and a series circuit of a transistor and a dummy memory cell in a clamp circuit. The transistor of the clamp circuit is connected to a high voltage and the series circuit is connected to the ground. In the test mode, the programming transistor and the bit line selecting transistors are turned off and the test mode transistors and the transistor connected to the clamp circuit are turned on. Thus, a test voltage is applied to the memory cells through the common connecting line, the test mode transistors and the bit lines.

Nonvolatile semiconductor memory having a stress test circuit

A semiconductor memory device includes a memory cell transistor, a voltage switching circuit supplied with a first voltage for data readout and a second voltage for data write and selectively generating one of the first and second voltages in response to a write control signal, a first driving circuit supplied with an output from the voltage switching circuit and driving the gate of the memory cell transistor in response to a memory cell selection signal, a sense circuit for sensing data of the memory cell transistor by comparing a sense potential corresponding to data from the memory cell transistor with a reference potential, a reference cell transistor for generating the reference potential, and a second driving circuit supplied with the output from the voltage switching circuit and driving the gate of the reference cell transistor in response to the write control signal.

Nonvolatile semiconductor memory device having reference potential

A nonvolatile semiconductor memory according to this invention is so constructed that different data readout references are used in an ordinary readout mode and in a program verification mode. The different read-out references can be set by changing reference input potential VREF supplied to a differential sense amplifier for amplifying a potential derived onto a bit line from a memory cell, or by changing an input threshold level of a circuit for sensing the potential on the bit line. In this case, the readout reference in the program verification mode is set severe, or high, in comparison with that in the ordinary readout mode.

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Yokohama, Japan

Nobuaki Ohtsuka