Abstract: In a micro-patterned semiconductor device that uses thin-film polycrystalline silicon for both interconnection and TFT (Thin Film Transistor) configuration elements, the required current supply capacity is achieved by increasing the leakage current of a reverse-direction diode when the reverse-direction junction diode is present in the current path consisting of polycrystalline silicon. Leakage current is increased by steepening the density slope at the PN junction of the diode which consists of polycrystalline silicon, or by making the region near the junction amorphous. For example, sufficient current can be supplied to a large number of memory cells via reverse-direction diodes even when cells that use TFTs consisting of thin-film polycrystalline silicon as the load for the flip-flop are used as large-scale SRAM memory cells. In this way, ultra high-integration memory ICs can be realized.

Abstract: The disclosure includes preferred semiconductor transistor devices utilizing thin film transistors, as well as preferred methods of forming such devices. Specifically, a bottom thin film transistor gate is formed having a top surface. An insulating filler is provided adjacent the thin film transistor gate to an elevation at least as high as the thin film transistor gate top surface, and subsequently levelled to provide generally planar insulating surfaces adjacent the thin film transistor gate. The planar insulating surfaces are substantially coplanar with the thin film transistor gate top surface. A planar semiconductor thin film is then formed over the thin film transistor gate and over the adjacent planar insulating surfaces. The thin film is doped to form source and drain regions of a thin film transistor which is bottom gated by the thin film transistor gate.

Abstract: The present invention provides an improved static random access memory which can be manufactured into values as designed by photolithography. Second direct contract for connecting active region and ground line for first and second memory cells is provided at a boundary between the first memory cell and second memory cell. Second direct contact is divided into a plurality of portions.

Abstract: A semiconductor device is disclosed including a first insulating film having a contact hole and being formed on a substrate. A first impurity region is formed in the active layer on the bottom of the contact hole, and a second impurity region is formed in the active layer on the first insulating film outside the contact hole. In addition, a semiconductor region is formed in the active layer on the sidewall of the contact hole, and a second insulating film is formed on the first impurity region in the contact hole. A gate electrode is formed on the second insulating film.

Abstract: A first word line connects the gate electrodes of first transfer transistors in adjacent memory cells. A second word line connects the gate electrodes of second transfer transistors in adjacent memory cells. A ground line connects the source regions of first and second driver transistors. The first and second word lines and ground line are formed by a wiring layer different from the wiring layer that forms the gate electrodes of the first and second transfer transistors. The ground line shields the first and second driver transistors, TFTs and the like. Drain contacts include chamfered sides between which the ground line is disposed.

Abstract: A memory cell in which data is written and read from a pass gate. The memory cell has a connection to a first pass gate, connecting the memory cell to a bit line. Additionally, the memory cell has a second pass gate connecting the memory cell to a complementary bit line. The pass gates are controlled by a word line and a complementary word line.

Abstract: A semiconductor device having an integrated circuit with high density load elements in memory cells forming a memory array wherein the load elements are either of the active (e.g., TFTs) or passive (e.g., resistance) type and designed so that the connection path between these elements and active element domains is extended to be longer within the same or smaller scale of the memory cell configuration. For this purpose, the connection path may be made to meander to provide for greater length, i.e., extend in one direction and then another within a single memory cell configuration. This further creates additional space for extending the resistance value of the active or passive load element which, in turn, permits a reduction in drain current, i.e., current consumption, during operational conditions of the memory cells or other circuits.

Abstract: A three-dimensional integrated circuit and fabrication process is provided for producing active and passive devices on various levels of the integrated circuit. The present process is particularly suited to interconnecting a source of one transistor to a drain of another to form series-connected transistors often employed in core logic units. A junction of an underlying transistor can be connected to a junction of an overlying transistor, with both transistors separated by an interlevel dielectric. The lower transistor junction is connected to the upper level transistor junction using a plug conductor. The plug conductor and, more specifically, the mutually connected junction, is further coupled to a laterally extended interconnect. The interconnect extends from the mutual connection point of the plug conductor to a substrate of the overlying transistor.

Abstract: A TFT circuit according to the present invention includes a first transistor and a second transistor both formed on an insulating substrate. The first transistor has a channel region comprising a polycrystalline silicon film to which a metal element for enhancing crystallization is added. The second transistor has a channel region comprising a polycrystalline silicon film to which no metal element for enhancing crystallization is added.

Abstract: A dual level transistor integrated circuit and a fabrication technique for making the integrated circuit. The dual level transistor is an integrated circuit in which a first transistor is formed on an upper surface of a global dielectric and a second transistor is formed on an upper surface of a first local substrate such that the second transistor is vertically displaced from the first transistor. The first local substrate is formed upon a first inter-substrate dielectric. By vertically displacing the first and second transistors, the lateral separation required to isolate first and second transistors in a typical single plane process is eliminated. The integrated circuit includes a semiconductor global substrate. The integrated circuit further includes a first transistor. The first transistor includes a first gate dielectric formed on an upper surface of the global substrate and a first conductive gate structure formed on an upper surface of the first dielectric.

Abstract: A semiconductor device includes an insulating support. A strip of semiconductor material has two ends in contact with the insulating support and a midsection extending between the ends. A dielectric layer encircles the midsection, and a conductive layer encircles the dielectric layer. The conductive layer has a substantially constant width such that a gate electrode formed within the conductive layer is fully self-aligned with drain and source regions formed within the ends.

Abstract: In an integrated circuit, gate electrode stack of which is subjected to self-alignment processes, the sheet resistance is lowered by including a tungsten layer 15. The tungsten layer 14 is protected by a sidewall material 21 of SiN.sub.x or SiO.sub.2 after an etching step which did not extend to the substrate 11. During a subsequent etching step in which the stack extends to the substrate 11, the sidewall material 31 acts as a hard mask protecting the upper portion of the stack. After the lower portion of the stack is protected by a re-oxidation layer 41, the entire stack can be processed further without deterioration of the sheet resistance of the tungsten layer 15.

Abstract: A static random access memory cell having a plurality of active regions defined on a semiconductor substrate, includes a plurality of first bulk transistors having a first common gate electrode and first impurity-doped regions, the first common gate electrode and first impurity-doped regions being formed on a portion of the active regions; a plurality of second bulk transistors spaced from the first bulk transistors, the second bulk transistors including a second common gate electrode and second impurity-doped regions, the second common gate electrode and second impurity-doped regions being formed on a portion of the active regions; and a plurality of thin film transistors formed on the second bulk transistors and including the second common gate electrode and a conductive layer formed above the second common gate electrode, wherein the conductive layer overlaps and is substantially coextensive with the second common gate electrode.

Abstract: A thin film transistor having two vertically stacked channels and dual gate non-photosensitive structure, where the source drain to bottom gate structure is self-aligned. This structure occupies the same area on a substrate as a conventional single gate thin film transistor. This invention also discloses a process for manufacturing a dual gate structure with a simple three mask procedure.

Abstract: A CMOS SRAM cell has a polycrystalline silicon signal line between a common node, which is the data storage node, and the power supply. A field effect device is fabricated within this polycrystalline silicon signal line. The channel of the field effect device is separated from an active region in the substrate by a thin gate dielectric, and the active region within the substrate functions as the control gate for the field effect device. Such a device can be used to provide polycrystalline silicon P-channel transistors for use in CMOS SRAM cells.

Abstract: A semiconductor device having the high integration and great driving ability is provided. An upper gate oxide film is formed on a gate electrode. An upper drain region is formed on a lower drain region through an oxide film, and an upper source region is formed on a lower source region through the oxide film. A polysilicon region is formed on the upper gate oxide film provided between the upper drain region and the upper source region. The lower layer portion of the polysilicon region is defined as a channel region.

Abstract: Each memory cell of an SRAM has a structure in which a gate electrode of a drive MOSFET is formed by a first conductive film, a gate electrode of a load TFT is formed by a third conducive layer and a second conductive film does not exist in an area where two gate electrodes overlap with each other. After the second conductive film is subjected to patterning, a first interlayer insulating film is successively removed with the same photolithographic mask. Since the parasitic capacitance at a memory node of the memory cell is increased by thinning the insulating film between the two gate electrodes, the SRAM has an excellent resistance to soft errors.

Abstract: A non-volatile memory device in which gate electrodes are formed on an upper surface and a lower surface of the channel via insulating layers, respectively, one of them is used as a read electrode and the other is used as a write electrode, whereby, at a read operation the reading is carried out without exerting an influence upon stored charges stored at the time of writing. Particularly, it has a structure in which a source and drain region of the non-volatile semiconductor memory device in formed in the semiconductor layer formed on the insulating layer and, at the same time, one of the read electrode and write electrode is buried in the insulating layer.

Abstract: A large-area electronic device such as, e.g, a large-area image sensor or flat panel display comprises thin-film drive circuitry including inverters each comprising a driver TFT (M1), a load TFT (M2) and a bootstrap capacitor (C.sub.s). Most TFT types which may be used to fabricate the transistors (M1 and M2) have a high parasitic gate capacitance due, inter alia, to overlap of the gate electrode (g) with their source and drain electrodes (21 and 22). This parasitic capacitance degrades the inverter gain Av by coupling between the output line (O/P) of the inverter and the gate electrode (g) of its load device (M2) and an excessively large capacitor (C.sub.s) is required to overcome this degradation. The present invention uses a reduction in the transconductance (gm2) of the load TFT (M2) to permit a reduction in the size of the boot strapping capacitor (C.sub.s) to within practical limits, while still obtaining a desirably high gain Av from the inverter in spite of the parasitic capacitances. A factor .mu..

Abstract: A static metal oxide semiconductor random access memory (SRAM) having NMOS and thin film transistors (TFTs) formed from a single polysilicon layer, and a method for forming the same. The SRAM cell comprises a plurality of NMOS transistors and TFTs that are interconnected by a local interconnect structure. The single layer of poly is used to define the TFT bodies and gates of NMOS transistors in the SRAM cell. Each TFT comprises a single polysilicon layer comprising source gate and drain regions. During the fabrication process, exposed portions of the TFT polysilicon body and exposed regions of NMOS transistors react with a refractory metal silicide to form polycide and silicide regions, respectively. An amorphous silicon pattern also reacts with the refractory metal silicide to form a local interconnect structure connecting the silicided portions of the thin film transistors and the MOS transistors.

Abstract: A semiconductor device and fabrication process wherein the device includes a conductive layer with a localized thick region positioned below the contact hole. In one embodiment of the invention, the thick region to which contact is made is formed by means of an opening in an underlayer of material. This embodiment of the device includes an underlayer of material having an opening therein; a layer of thin conductive material formed on the underlayer and in the opening; an overlayer of material having a contact hole therethrough formed on the layer of thin conductive material; a conductor contacting the layer of thin conductive material through the contact hole; and wherein the opening in the underlayer is positioned below the contact hole and sized and shaped to form a localized thick region in the layer of thin conductive material within the opening.

Abstract: The present invention is directed to a thin film transistor (TFT) structure having a channel region formed of a crystallized SiGe and is to provide a thin film transistor having a large carrier mobility. In this case, a channel region (4) is formed of a crystallized SiGe thin film.

Abstract: In one memory cell forming region of an SRAM, a field oxide film having edges straight and parallel to each other is formed. Active regions are formed sandwiching field oxide film. One word line is formed extending over field oxide film and active regions. On word line 6, gate electrodes of a driver transistor and GND lines are formed at prescribed positions. Gate electrodes of the driver transistor also serve as a gate electrode of a TFT. On gate electrodes of the driver transistor and on GND lines, polycrystalline silicon layers in which channel region and source/drain regions of the TFT are formed, are formed respectively. Consequently, a high performance SRAM which can reduce cell area and which has high reliability can be obtained.

Abstract: A thin film field effect transistor has a three-layer structure including a polycrystalline semiconductor layer to be a channel region, a conductive layer to be a gate electrode and a insulating layer to be a gate insulating film between the channel region and the gate electrode. The roughness of an interface between the channel region and the gate insulating film is less than a few nm so that the current drivability of the transistor is improved.

Abstract: The disclosure includes preferred semiconductor transistor devices utilizing thin film transistors, as well as preferred methods of forming such devices. Specifically, a bottom thin film transistor gate is formed having a top surface. An insulating filler is provided adjacent the thin film transistor gate to an elevation at least as high as the thin film transistor gate top surface, and subsequently levelled to provide generally planar insulating surfaces adjacent the thin film transistor gate. The planar insulating surfaces are substantially coplanar with the thin film transistor gate top surface. A planar semiconductor thin film is then formed over the thin film transistor gate and over the adjacent planar insulating surfaces. The thin film is doped to form source and drain regions of a thin film transistor which is bottom gated by the thin film transistor gate.

Abstract: The present invention provides a field effect transistor comprising the following elements. An insulation film is provided on a semiconductor substrate. The insulation film has an opening positioned on a predetermined region of the semiconductor substrate. A first polysilicon film is provided over the insulation film. A second polysilicon film is provided in contact with the first polysilicon film. The second polysilicon film extends on inside walls of the opening of the insulation film and over a peripheral portion of the predetermined region of the semiconductor substrate so that the first polysilicon film is connected through the second polysilicon film to the peripheral portion in the predetermined region of the semiconductor substrate.

Abstract: Reduced area metal contacts to a thin polysilicon layer contact structure having low ohmic resistance was achieved. The structure involves forming contact openings in an insulating layer over a buffer layer composed of a thick polysilicon layer. A portion of the sidewall in the opening includes a patterned thin polysilicon layer that forms part of a semiconductor device and also forms the electrical connection to the metal contact. The structure provides metal contacts having very low resistance and reduced area for increased device packing densities. The metal contact structure also eliminates the problem of forming P.sup.+ /N.sup.+ non-ohmic junctions usually associated with making P.sup.+ /N.sup.+ stacked contact. The structure further allows process steps to be used that provide larger latitude in etching the contact opening and thereby provides a structure that is very manufacturable.

Abstract: The cross-sectional area of a thin-film transistor (TFT) is decreased in order to minimize bitline to supply leakage of the TFT. This is accomplished by utilizing a spacer etch process to manufacture a TFT having a very narrow and thin channel in a controllable manner. The spacer dimensions of the TFT may be adjusted by simply modifying the thicknesses of the poly gate and the channel poly. The channel thickness is limited by the thickness of the deposited channel polysilicon which may be as thin as approximately 300 .ANG. to 500 .ANG., and the channel width of the TFT corresponds to the height of the spacer etched along the polysilicon gate of the device which may be as small as approximately 0.15 to 0.25 .mu.m.

Abstract: A thin film transistor includes a first active layer formed on a substrate; a gate electrode formed on a center portion of the first active layer and having a lower side connected to the center portion of the first active layer; a second active layer electrically connected to the first active layer and formed on lateral sides and on an upper side of the gate electrode; and impurity regions formed at opposing lateral sides of the gate electrode.

Abstract: SRAM memory cells is provided with high resistance to soft error and no parasitic capacitance due to PN junction.SRAM memory cells comprises the load resister is a thin film transistor having a same conductive type as that of the driver transistor.

Abstract: The invention is directed to a thin film transistor (TFT) fabricated by using a planarized poly plug as the bottom gate for use in any integrated circuit and in particular an static random access memory (SRAM). The TFT is used in an SRAM device to form a planarized SRAM cell comprising: a pulldown transistor having a control gate and source/drain terminals; a planarized insulating layer having grooves therein, each groove providing access to an underlying conductive material; a planarized conductive plug residing inside each groove, whereby a first conductive plug forms a thin film transistor gate connecting to an to an adjacent inverter and a second conductive plug provides connection to the gate of the pulldown device; a gate dielectric overlying the first planarized conductive plug; and a patterned semiconductive layer doped such that a channel region aligns to each thin film transistor gate and a source/drain region aligns to each side of the channel region is formed.

Abstract: A multilevel gate array MOS-type integrated circuit structure is described wherein each source, drain, and gate electrode region in the integrated circuit structure is accessible directly through a contact opening formed normal to the plane of the underlying substrate through an overlying insulation layer.

Abstract: An insulating film having a through hole aligned with an electrode on a first semiconductor element is formed on a first semiconductor substrate and a metal is disposed in the through hole. A second semiconductor element on a second semiconductor substrate is placed on the insulating film in such a way that an electrode of the second semiconductor element contacts the metal. Thus, a plurality of transistors having different performance characteristics and functions can be easily disposed adjacent to each other for improved integration.

Abstract: A transistor comprising a P-type high concentration impurity diffusion layer which can also serve as an emitter for a parasitic PNP transistor wherein a layer of crystal defect obtained by ion implantation of inert impurity atoms or a compound thereof is arranged in the P-type high concentration impurity diffusion layer thereby decreasing the current amplification rate of the parasitic transistor.

Abstract: A field-effect semiconductor element implemented with a fewer number of elements and a reduced area and capable of storing data by itself without need for cooling at a cryogenic temperature, and a memory device employing the same. Gate-channel capacitance is set so small that whether or not a trap captures one electron or hole can definitely and distinctively be detected in terms of changes of a current of the semiconductor FET element. By detecting a change in a threshold voltage of the semiconductor element brought about by trapping of electron or hole in the trap, data storage can be realized at a room temperature.

Abstract: A semiconductor device according to the invention includes a first conductivity type of driver transistor, a second conductivity type of load transistor formed on the driver transistor and an insulation layer formed between the driver transistor and the load transistor. The insulation layer is provided thereon with a depression area in which a channel region, a gate insulation layer and a gate electrode of the load transistor are formed.

Abstract: Amorphous silicon in impurity regions (source and drain regions or N-type or p-type regions) of TFT and TFD are crystallized and activated to lower electric resistance, by depositing film having a catalyst element such as nickel (Ni), iron (Fe), cobalt (Co) or platinum (Pt) on or beneath an amorphous silicon film, or introducing such a catalyst element into the amorphous silicon film by ion implantation and subsequently crystallizing the same by applying heat annealing at an appropriate temperature.

Abstract: Chips having subsurface structures within or adjacent a horizontal trench in bulk single crystal semiconductor are presented. Structures include three terminal devices, such as FETs and bipolar transistors, rectifying contacts, such as pn diodes and Schottky diodes, capacitors, and contacts to and connectors between devices. FETs have low resistance connectors to diffusions while retaining low overlap capacitance. A low resistance and low capacitance contact to subsurface electrodes is achieved by using highly conductive subsurface connectors which may be isolated by low dielectric insulator. Stacks of devices are formed simultaneously within bulk single crystal semiconductor. A subsurface CMOS invertor is described. A process for forming a horizontal trench exclusively in heavily doped p+ regions is presented in which porous silicon is first formed in the p+ regions and then the porous silicon is etched.

Abstract: A silicon layer in a lower layer and an interconnection layer arranged in an upper layer are electrically connected through an opening for contact. A silicon plug layer having the same conductivity type as that of the silicon layer is embedded in the opening. The silicon plug layer is embedded in the opening by an etch back method after deposited using a CVD method. The interconnection layer in the upper layer has conductivity type different from that of the silicon plug layer. A refractory metal silicide layer is formed between the upper interconnection layer and the silicon plug layer.The refractory metal silicide layer prevents pn junction from being formed between the upper interconnection layer and the silicon plug layer.

Abstract: A combination of a lower thin film transistor formed on an insulating substrate and an upper thin film transistor laminated over the lower transistor has a lower channel formed in the lower transistor, an upper channel formed in the upper transistor, a lower gate electrode disposed under the lower channel, an intermediate gate electrode disposed between the lower channel and the upper channel, and an upper gate electrode disposed over the upper channel.

Abstract: A transistor is formed on a substrate of dielectric material. The transistor includes a layer of semiconductor material that is formed on the substrate and has a source region and a drain region. The layer also has a channel region that is in a recess of the substrate and adjacent to the source and drain regions. The channel is self-aligned, as are the light doped source and drain regions.

Abstract: A semiconductor device includes a gate electrode, and a semiconductor layer formed on the main surface of the gate electrode with a gate oxide film therebetween. The semiconductor layer has a channel region opposing the main surface of gate electrode and source/drain regions having the channel region therebetween, and is formed so that the bent angle in the vicinity of the boundaries of the channel region and the source/drain regions is beyond 90.degree.. Thus, the semiconductor layer formed in a thin film transistor has no orthogonal bent, and, therefore the concentration of electric fields is suppressed, improving the performance of the thin film transistor.

Abstract: A monolithic semiconductor body (26) resides in an opening (16) formed in an insulating layer (14). The monolithic semiconductor body (26) includes an elongated region (20) filling the opening (16) in the insulating layer (14) and contacting a semiconductor region (12). The monolithic semiconductor body (26) further includes a surface region (24) overlying the elongated region (20) and a portion of the surface (22) of the insulating layer (14) adjacent to the opening (16). The monolithic semiconductor body (26) is fabricated by first depositing a layer of semiconductor material into the opening (16), then planarizing the surface of the insulating layer (14). Next, a selective deposition process is carried out to form the surface region (24) using the semiconductor material in the opening (16) as a nucleation site. The radius of curvature of the surface region (24) is determined by the amount of controlled overgrowth during the selective deposition process.

Abstract: A p-well region is formed in a main surface of a semiconductor substrate. A contact electrode is electrically connected to a predetermined n-type impurity region formed in a surface of the p-well region. A diffusion preventing layer is formed between the contact electrode and a drain region of a TFT. An interconnection layer is formed on the semiconductor substrate with an interlayer insulating film therebetween. A diffusion preventing layer is also formed between the interconnection layer and a source region of the TFT. Diffusion preventing layers are further formed between a channel region of the TFT and the source/drain regions of the TFT.

Abstract: A three dimensional latch and bulk silicon pass transistor for high density field reconfigurable architectures is provided utilizing bulk silicon with a layer of polysilicon or silicon on insulator (SOI) thereover. The pass transistor, which must have very low resistance to provide a good short circuit path between the metal runs and fast switching speed, is fabricated in the bulk silicon wherein the resistivity can be made very low relative to polysilicon and because only the pass transistor is disposed in the bulk silicon, thereby permitting the dimensions thereof to be increased to provide even lower resistance. Since only the latch is fabricated in the layer of polysilicon or SOI and is disposed over the pass transistor, the amount of chip area utilized can be the same or less than required in the prior art wherein all circuitry was in the bulk silicon.

Abstract: The invention may be incorporated into a method for forming a vertically oriented semiconductor device structure, and the semiconductor structure formed thereby, by forming a first transistor over a portion of a substrate wherein the first transistor has a gate electrode and a source and drain regions. First and second interconnect regions are formed over a portion of the gate electrode and a portion of the source and drain regions of the first transistor, respectively. A source and drain region of a second transistor is formed over the second interconnect. A Vcc conductive layer is formed over a portion of the source and drain region of the second transistor which is formed over the second interconnect.

Abstract: The disclosure pertains to a bottom and top gated thin film transistor and other circuitry constructions. In the thin film transistor construction, the top gate electrode (preferably polysilicon) overlaps with the channel region, and the top gate electrode has an electrically conductive sidewall (preferably oxide). The bottom gate electrode (preferably polysilicon) has an outer surface area which includes a portion which extends outwardly beyond the top gate electrode sidewall. An electrically conductive sidewall link overlies the electrically insulated channel region sidewall and extends between the top gate sidewall and bottom gate outer surface portion to electrically interconnect the top and bottom gate electrodes. The insulated channel region sidewall is insulated by an insulating sidewall spacer. The insulating sidewall spacer partially overlaps the top gate electrode electrically conductive sidewall.

Abstract: An Electrically Erasable PROM (E.sup.2 PROM) according to the present invention includes a semiconductor substrate of a first conductivity type having a field oxide formed on a predetermined region of the main surface thereof; a memory section formed on the semiconductor substrate; and a peripheral circuit section formed in the peripheral of the memory section, wherein the peripheral circuit section has a CMOS structure in which an N-channel MOS transistor and a P-channel MOS transistor are connected to each other in a complementary manner; one of the N-channel MOS transistor and the P-channel MOS transistor is a thin film transistor formed on the field oxide and the other is a MOS transistor formed on the semiconductor substrate; and the memory section includes a plurality of non-volatile transistors formed on the semiconductor substrate.

Abstract: A silicon layer in a lower layer and an interconnection layer arranged in an upper layer are electrically connected through an opening for contact. A silicon plug layer having the same conductivity type as that of the silicon layer is embedded in the opening. The silicon plug layer is embedded in the opening by an etch back method after deposited using a CVD method. The interconnection layer in the upper layer has conductivity type different from that of the silicon plug layer. A refractory metal silicide layer is formed between the upper interconnection layer and the silicon plug layer.The refractory metal silicide layer prevents pn junction from being formed between the upper interconnection layer and the silicon plug layer.

Abstract: A depletion mode power MOSFET has a gate electrode formed of material that is refractory, or resistant, to high temperature encountered during device fabrication. A depletion channel region which is formed in a base region of a MOSFET and which interconnects the source and drain regions is formed after a high temperature drive to form the base region, but before a gate oxide and gate and source electrodes are formed at lower temperatures. The depletion channel region is thus subjected to reduced temperatures and grows only slightly in thickness, so that it can be easily depleted. The gate oxide, similarly, is subjected to reduced temperatures, and, particularly when made thin, exhibits high insensitivity to radiation exposure.