Abstract: Disclosed is a semiconductor integrated circuit device which includes first field effect transistors of an LDD structure having a floating gate as memory cells and second field effect transistors of the LDD structure as elements other than the memory cells, and which is used as EPROM. A shallow, low impurity concentration region of the first field effect transistor as a part of its source or drain region has a higher impurity concentration than a shallow, low impurity concentration region of the second field effect transistor as a part of its source or drain region.

Abstract: A method of fabrication comprising forming a semiconductor integrated circuit device LSI which has a microcomputer CPU furnished with an EPROM, determining a program for controlling the microcomputer CPU and to be set in the EPROM (performing an initial evaluation) while information is being written into and erased from the EPROM built in the semiconductor integrated circuit device LSI, and thereafter forming a semiconductor integrated circuit device LSI in which the EPROM of the first-mentioned semiconductor integrated circuit device LSI is replaced with a mask ROM. In replacing the EPROM with the mask ROM, peripheral circuits required for both the EPROM and the mask ROM have their circuit arrangements held basically the same, and specific peripheral circuits for use in only the EPROM have their circuit regions left as they are as logically inactive regions.

Abstract: Disclosed is a semiconductor integrated circuit device which includes first field effect transistors with an LDD structure having a floating gate in memory cells and second field effect transistors with an LDD structure as elements other than memory cells, and which is used as an EPROM. A shallow, low impurity concentration region of the first field effect transistor as a part of its source or drain region has a higher impurity concentration than a shallow, low impurity concentration region of the second field effect transistor as a part of its source or drain region.

Abstract: A method of fabricating a second semiconductor integrated circuit device includes steps of forming a first semiconductor integrated circuit device which has a microcomputer and is furnished with an EPROM; determining a program for controlling the microcomputer and to be set in the EPROM (performing an initial evaluation) while information is being written into and erased from the EPROM built in the first semiconductor integrated circuit device; and thereafter forming a second semiconductor integrated circuit device in which the EPROM of the first semiconductor integrated circuit device is replaced with a mask ROM. In replacing the EPROM with the mask ROM, the peripheral circuits required for both the EPROM and the mask ROM have their circuit arrangements held basically the same, and specific peripheral circuits for use in only the EPROM have their circuit regions left as they are as logically inactive regions.

Abstract: Disclosed is a semiconductor integrated circuit device which includes first field effect transistors of a LDD structure having a floating gate as memory cells and second field effect transistors of the LDD structure as elements other than the memory cells, and which is used as EPROM. A shallow, low impurity concentration region of the first field effect transistor as a part of its source or drain region has a higher impurity concentration than a shallow, low impurity concentration region of the second field effect transistor as a part of its source or drain region.

Abstract: In a semiconductor integrated circuit device having a dynamic type memory element (DRAM), a non-volatile memory element of FLOTOX structure and a MISFET, a dielectric film of an information storing capacitance element fo the DRAM and a tunnel insulation film of the non-volatile memory element are constituted in film thickness less than that of a gate insulation film of the MISFET. Thin dielectric film increases the charge storage quantity of the information storing capacitance element and decreases the occupation area of the DRAM. Thin tunnel insulation film increases the tunnel current quantity and decreases the information write time of the non-volatile memory element. Process of forming the dielectirc film and process of forming the tunnel insulation film are performed in the same process, thereby the manufacaturing process of the semiconductor integrated circuit device is reduced.

Abstract: Disclosed is a semiconductor integrated circuit device which includes first field effect transistors of an LDD structure having a floating gate as memory cells and second field effect transistors of the LDD structure as elements other than the memory cells, and which is used as EPROM. A shallow, low impurity concentration region of the first field effect transistor as a part of its source or drain region has a higher impurity concentration than a shallow, low impurity concentration region of the second field effect transistor as a part of its source or drain region.

Abstract: Disclosed herein is a MOS-type field-effect transistor in which a semiconductor region having the same type of conductivity as the substrate and an impurity concentration higher than that of the substrate is formed under the channel so as to come at both ends thereof into contact with the source and drain regions. The semiconductor region restricts the extension of depletion layer from the source and drain regions, and restricts the short-channel effect. The junction capacity is small between the semiconductor region and the source and drain regions.

Abstract: Disclosed herein is a MOS-type field-effect transistor in which a semiconductor region having the same type of conductivity as the substrate and an impurity concentration higher than that of the substrate is formed under the channel so as to come at both ends thereof into contact with the source and drain regions. The semiconductor region restricts the extension of depletion layer from the source and drain regions, and restricts the short-channel effect. The junction capacity is small between the semiconductor region and the source and drain regions.

Abstract: A semiconductor integrated circuit device is provided which includes first field effect transistors of an LDD structure having a floating gate as memory cells and second field effect transistors of the LDD structure as elements other than the memory cells. A shallow, low impurity concentration region of the first field effect transistor which is a part of its source or drain region has a higher impurity concentration than a shallow, low impurity concentration region of the second field effect transistor which is a part of its source or drain region. The device is particularly useful in an EPROM arrangement.

Abstract: An elastic surface wave propagation device is disclosed which is composed of a substrate for elastic surface wave propagation and at least one transducer disposed on the major surface of the substrate for converting an electric signal into an elastic surface wave or vice versa. The substrate is formed of quartz crystal and the major surface of the substrate is 43.degree. rotated Y cut plane of the quartz crystal. The angle between the direction of propagation of the elastic surface wave and the X-axis direction of the quartz crystal is selected to be in the range of 8.degree. to 12.degree. so that spurious components are sufficiently suppressed or negligible.