Hitachi, Ltd.

Renesas Technology Corp.

Hiroto Kawagoe

Norio Suzuki

Kosei Nomiya

Shogo Kiyota

Eiichi Yamada

Yoshihiko Sakurai

Tatsumi Shirasu

Hisashi Arakawa

Yuji Sugino

Manabu Kitano

Takashi Naganuma

Jiroh Sakaguchi

Haruo Keida

Yoshikazu Hatsukano

Over the principal surface of a semiconductor substrate body containing an impurity of a predetermined conduction type, there is formed an epitaxial layer which contains an impurity of the same conduction type as that of the former impurity and the same concentration as the designed one of the former impurity. After this, there are formed a well region which has the same conduction type as that of said impurity and its impurity concentration gradually lowered depthwise of said epitaxial layer. The well region is formed with the gate insulating films of MIS&middot;FETs.

Process for manufacturing a semiconductor wafer, a semiconductor wafer, process for manufacturing a semiconductor integrated circuit device, and semiconductor integrated circuit device

Over the principal surface of a semiconductor substrate body containing an impurity of a predetermined conduction type, there is formed an epitaxial layer which contains an impurity of the same conduction type as that of the former impurity and the same concentration as the designed one of the former impurity. After this, there are formed a well region which has the same conduction type as that of said impurity and its impurity concentration gradually lowered depthwise of said epitaxial layer. The well region is formed with the gate insulating films of MIS.FETs.

Process for manufacturing a semiconductor wafer, a semiconductor wafer,

In a semiconductor integrated circuit device composed of insulated gate field-effect transistors, the improvement comprises the fact that insulated gate field-effect transistors having gate insulating films of substantially equal thicknesses are arranged on a principal surface of a semiconductor substrate in the shape of a matrix. Gate input columns of the transistors are formed of polycrystalline silicon layers, and some of the transistors are enhancement type, while others are depletion type. Further, the respective transistors are formed by the self-alignment technique which employs the polycrystalline silicon layers as a diffusion mask, and the depletion type transistors are formed by implanting impurity ions opposite in the conductivity type to the substrate into selected areas of the surface of the substrate. Thus, a read only memory in a MOS-IC chip has its occupying area reduced remarkably.

Semiconductor integrated circuit device manufacturing method

Semiconductor integrated circuit device composed of insulated gate

In a circuit arrangement wherein a memory matrix and an address decoder are constructed of read only memories (ROMs), a semiconductor read only memory is characterized in that at least the address decoder ROM in which the number of output lines to be selected is smaller than that of output lines not be selected is made of a longitudinal system in which a plurality of MISFETs are connected in series between respective output lines arranged in a column and a reference voltage terminal, the MISFETs forming a desired pattern in a row, and that current is permitted to flow through only a load MISFET connected with a selected one of the address select lines.

Semiconductor read only memory

An input circuit has at least an enhancement type first MISFET incorporated between an input terminal and a power supply terminal for the input circuit. A gate electrode of the first MISFET is connected to the power supply terminal, and at least a second MISFET is incorporated between the input terminal and a gate electrode of a third MISFET constituting the input circuit. A gate electrode of the second MISFET is connected to the power supply terminal, whereby the dielectric breakdown of the gate of the third MISFET is prevented.

Input circuit

In a large scale integrated circuit wherein insulated gate field-effect transistors are arrayed in the shape of a matrix on a single semiconductor substrate, an improvement is provided comprising the fact that some of the transistors are of the depletion type, while others of the transistors are of the enhancement type, so that a very large number of contact holes which are otherwise required for electrical connection between aluminum wiring and the drain regions are unnecessary. This permits the density of integration of the integrated circuit to be raised.

Semiconductor device

An initial state-setting circuit wherein a malfunction preventing transistor is connected in series with an input transistor of a flip-flop, and is rendered conductive a short time after closure of a power supply switch. Even when noise arises immediately after the closure of the power supply, no malfunction due to the noise is induced, since the malfunction preventing transistor is not yet conductive.

Circuit for setting an initial state after connection of a power supply

In order to provide compensation for changes in the ambient temperature and supply voltage for an electronic circuit, such as a pulse generator circuit made up of MOSIC structure, a field effect transistor circuit includes a high value resistor and an enhancement and depletion type MOSFET, connected in parallel. The drain electrodes of the MOSFETs are connected to the power supply through the resistor and are also connected to the gate electrode of a depletion type load MOSFET which is the load transistor for an enhancement type MOSFET. When the compensating circuit is provided in a pulse generator circuit, instability in the oscillating frequency of the pulse generator due to changes in ambient temperature and supply voltage is overcome and the difference in the oscillating periods for the various MOSICs are decreased.

Electronic circuit using field effect transistor with compensation means

A compensation circuit for electronic circuits such as pulse generator circuits which are suitable for MOSICS includes a resistor of high resistance and parallel-connected MOSFETs of the enhancement type and depletion type, respectively. The drain electrodes of the MOSFETs are connected to a power supply through the resistor, and are also connected to the gate electrode of load MOSFET of the depletion type which constitutes a load for a MOSFET of the enhancement type. To the gate of the former enhancement type MOSFET, a controlled bias voltage is applied from the connection point of MOSFETs connected in series between the power supply and ground. By employing the compensation circuit in pulse generator circuits, the instability of the oscillating periods due to changes in the ambient temperature and changes in the supply voltage is compensated. Also, the differences of oscillating periods are decreased among MOSICs.

A switching circuit for use as, e.g., a digitron driver circuit in an electronic desk top calculator, comprises a driving MISFET whose source terminal is connected to a ground reference potential, at least one protective MISFET whose source terminal is connected to a drain terminal of the driving MISFET, and a bias power source which is connected through a load to a drain terminal of the protective MISFET. A d.c. voltage is applied to a gate terminal of the protective MISFET and an output signal is derived from the drain terminal of the protective MISFET on the basis of an input signal which is supplied to a gate terminal of the driving MISFET. The driving MISFET is an enhancement mode transistor, while the protective MISFET is a depletion mode transistor, whereby the withstand voltage of the switching circuit is enhanced.

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Kodaira, Japan

Hiroto Kawagoe