Abstract: Provided are a thin-film transistor formed by connecting polysilicon layers having different conductivity types with each other which prevents occurrence of inconvenience resulting from diffusion of impurities and a method of fabricating the same. A drain (6), a channel (7) and a source (8) are integrally formed on a surface of a second oxide film (4) by polysilicon. The drain (6) is formed to be connected with a pad layer (3) (second polycrystalline semiconductor layer) through a contact hole (5) which is formed to reach an upper surface of the pad layer (3). The pad layer (3) positioned on a bottom portion of the contact hole (5) (opening) is provided with a boron implantation region BR.

Abstract: Provided are a thin-film transistor formed by connecting polysilicon layers having different conductivity types with each other which prevents occurrence of inconvenience resulting from diffusion of impurities and a method of fabricating the same. A drain (6), a channel (7) and a source (8) are integrally formed on a surface of a second oxide film (4) by polysilicon. The drain (6) is formed to be connected with a pad layer (3) (second polycrystalline semiconductor layer) through a contact hole (5) which is formed to reach an upper surface of the pad layer (3). The pad layer (3) positioned on a bottom portion of the contact hole (5) (opening) is provided with a boron implantation region BR.

Abstract: Provided are a thin-film transistor formed by connecting polysilicon layers having different conductivity types with each other which prevents occurrence of inconvenience resulting from diffusion of impurities and a method of fabricating the same. A drain (6), a channel (7) and a source (8) are integrally formed on a surface of a second oxide film (4) by polysilicon. The drain (6) is formed to be connected with a pad layer (3) (second polycrystalline semiconductor layer) through a contact hole (5) which is formed to reach an upper surface of the pad layer (3). The pad layer (3) positioned on a bottom portion of the contact hole (5) (opening) is provided with a boron implantation region BR.

Abstract: Provided are a thin-film transistor formed by connecting polysilicon layers having different conductivity types with each other which prevents occurrence of inconvenience resulting from diffusion of impurities and a method of fabricating the same. A drain (6), a channel (7) and a source (8) are integrally formed on a surface of a second oxide film (4) by polysilicon. The drain (6) is formed to be connected with a pad layer (3) (second polycrystalline semiconductor layer) through a contact hole (5) which is formed to reach an upper surface of the pad layer (3). The pad layer (3) positioned on a bottom portion of the contact hole (5) (opening) is provided with a boron implantation region BR.

Abstract: Provided are a thin-film transistor formed by connecting polysilicon layers having different conductivity types with each other which prevents occurrence of inconvenience resulting from diffusion of impurities and a method of fabricating the same. A drain (6), a channel (7) and a source (8) are integrally formed on a surface of a second oxide film (4) by polysilicon. The drain (6) is formed to be connected with a pad layer (3) (second polycrystalline semiconductor layer) through a contact hole (5) which is formed to reach an upper surface of the pad layer (3). The pad layer (3) positioned on a bottom portion of the contact hole (5) (opening) is provided with a boron implantation region BR.

Abstract: A local decoder controlling activation of each word line includes a first transistor connected between first and second nodes, a second transistor connected between a power-supply voltage and the first node, and an inverter driving a word line with the power-supply voltage or a ground voltage in accordance with the voltage of the first node. When a corresponding word line is activated, the second node is set at the ground voltage while the first transistor is turned on. In a burn-in test, a burn-in control circuit forcibly turns off the second transistor in a local decoder corresponding to a word line to be activated.

Abstract: The structure around a high-resistance element is formed in mirror symmetry to a plane perpendicular to a semiconductor substrate and the surface of the sheet. Specifically, high-resistance element, contact plugs and extending portion of interconnection layers are symmetric, each of the interconnection layers covering high-resistance element by the same amount. Thus, a semiconductor device of which degree of freedom on designing layout of interconnections which is to be connected to interconnection layers electrically connected to the high-resistance element via contact plugs can be attained.

Abstract: A local decoder controlling activation of each word line includes a first transistor connected between first and second nodes, a second transistor connected between a power-supply voltage and the first node, and an inverter driving a word line with the power-supply voltage or a ground voltage in accordance with the voltage of the first node. When a corresponding word line is activated, the second node is set at the ground voltage while the first transistor is turned on. In a burn-in test, a burn-in control circuit forcibly turns off the second transistor in a local decoder corresponding to a word line to be activated.

Abstract: The structure around a high-resistance element is formed in mirror symmetry to a plane perpendicular to a semiconductor substrate and the surface of the sheet. Specifically, high-resistance element, contact plugs and extending portion of interconnection layers are symmetric, each of the interconnection layers covering high-resistance element by the same amount. Thus, a semiconductor device of which degree of freedom on designing layout of interconnections which is to be connected to interconnection layers electrically connected to the high-resistance element via contact plugs can be attained.

Abstract: In a chip with pads provided on four sides, I/O defects of the chip can be determined with test probes applied to two sides of the chip. A semiconductor storage unit has data pads which input/output data arranged on predetermined two sides, and control pads which input/output control data arranged on other two sides. The unit includes test circuits connected in series and connected to a corresponding data pads and has a register circuit. The register circuit holds and outputs inputted data based on a test signal. Storage elements stores data and are connected to a corresponding test circuit. At the time of testing, the elements store the data from a predetermined data pad and transmitted to a predetermined test circuit. The register circuit reads the data in the corresponding storage element and outputs the data from the predetermined data pad via other register circuit.

Abstract: In a test operation for a semiconductor memory device, memory power supply lines are disconnected from a power supply node by using switch gates. Voltages of the memory power supply lines are detected using detection holding circuits. When the detected voltage is lower than a predetermined value, the corresponding memory power supply line is driven to a ground voltage level by the detection holding circuit. Thereby, a standby-current-defective but normally-operable memory cell is forced to an operation-defective state. Then, the standby-current-defective memory cell is identified, and redundancy replacement is performed thereon. Consequently, the standby current abnormality in the semiconductor memory device can be repaired.

Abstract: An output buffer of a semiconductor memory device includes two N channel pull-down transistors both caused to become conductive in response to a falling edge of an internal data signal. One of the two N channel MOS transistors is caused to become nonconductive in the period starting from the time when the level of an external data signal falls beyond a reference potential to the time when the level of the external data signal reaches L level. Accordingly, noise generated on a line of the ground potential can be reduced without deterioration of the falling speed of the external data signal from H level to the reference potential.

Abstract: In a test operation for a semiconductor memory device, memory power supply lines are disconnected from a power supply node by using switch gates. Voltages of the memory power supply lines are detected using detection holding circuits. When the detected voltage is lower than a predetermined value, the corresponding memory power supply line is driven to a ground voltage level by the detection holding circuit. Thereby, a standby-current-defective but normally-operable memory cell is forced to an operation-defective state. Then, the standby-current-defective memory cell is identified, and redundancy replacement is performed thereon. Consequently, the standby current abnormality in the semiconductor memory device can be repaired.

Abstract: An SRAM according to the present invention includes a voltage-down circuit and an internal circuit. The voltage-down circuit includes three resistors, two PMOS transistors and an NMOS transistor. One PMOS transistor directly applies an external power supply voltage to the internal circuit. The NMOS transistor applies a voltage obtained by reducing the external power supply voltage by a threshold voltage thereof to the internal circuit. The value of a predetermined voltage as a condition for switching such application of the voltage by the PMOS transistor and application Of the voltage by the NMOS transistor is determined by the resistance ratio of the two resistors. Each of the three resistors is formed by a plurality of resistance elements of one kind. Thus, even if the process parameter varies, the ratio of the resistance values of the two resistors which determines the switching point can be kept constant, thereby preventing variation in switching point.

Abstract: A semiconductor memory device includes load circuits of column sense amplifiers arranged correspondingly to Y-addresses (global bit line pairs), respectively. A plurality of memory blocks commonly use the load circuit. Each memory block includes input circuits of the column sense amplifiers for the bit line pairs, respectively. Each input circuit is activated in response to the corresponding block select signal. In response to the potential on the corresponding bit line pair, a potential difference occurs on the corresponding global bit line pair. The load circuit increases this potential difference.

Abstract: An internal voltage generating circuit down-converts an external supply voltage and changes a reduction in its output voltage level from the external supply voltage level as the external supply voltage increases. The internal supply voltage is kept lower than the external supply voltage by the constant value while the external supply voltage stays under a predetermined voltage. The reduction amount is increased in proportion to the external supply voltage while the external supply voltage is over the predetermined voltage.

Abstract: A resistor connected in series with a source of external supply potential and a transistor circuit. The transistor circuit comprises a plurality of MOS transistors each of whose drain and gate are connected together, and is grounded. This transistor circuit detects whether an external supply potential is below or above a specific value. When the external supply potential is detected as being below the specific value, another MOS transistor connected to the source of external supply potential is made to conduct, and the external supply potential is supplied to a semiconductor memory circuit without voltage step-down. However, when the external supply potential is detected as being above the specific value, the external supply potential is stepped down through the other MOS transistor, and supplied to the semiconductor memory circuit. An internal supply potential is supplied to a semiconductor memory circuit device in a specific range even if the external supply potential fluctuates.

Abstract: In a line configuration of each memory cell array employed in a semiconductor memory device, a pair of bit line signal input/output lines or a pair of input/output data lines for transmitting complementary signals are disposed on both sides of and adjacent the global word line so as to cancel the influence of the global word line. By these configurations, the number of shielded lines may be reduced and the width of each line and the interval between the lines are arrayed for preventing the respective lines from breaking or being short-circuited.

Abstract: A memory cell includes two bipolar transistors. An upper side word line is connected to the gates of one access transistor and one depletion type transistor in the memory cell. A lower side word line is connected to the gates of the other access transistor and the other depletion type transistor in the memory cell. In data write operation, the potential on the upper side word line is set to "H" level for a prescribed period and the potential on the lower side word line is thereafter set to "H" level for a prescribed period, regardless of the type of data. As a result, a circuit related to row decoding can be simplified since a circuit for determining the type of data is not necessary in the circuit related to row decoding.

Abstract: An SRAM according to the present invention includes a voltage-down circuit and an internal circuit. The voltage-down circuit includes three resistors, two PMOS transistors and an NMOS transistor. One PMOS transistor directly applies an external power supply voltage to the internal circuit. The NMOS transistor applies a voltage obtained by reducing the external power supply voltage by a threshold voltage thereof to the internal circuit. The value of a predetermined voltage as a condition for switching such application of the voltage by the PMOS transistor and application of the voltage by the NMOS transistor is determined by the resistance ratio of the two resistors. Each of the three resistors is formed by a plurality of resistance elements of one kind. Thus, even if the process parameter varies, the ratio of the resistance values of the two resistors which determines the switching point can be kept constant, thereby preventing variation in switching point.