Abstract: A method is disclosed for fabricating patterned conductive lines which are self-aligned with underlying contacts windows. A layer of a photosensitive material such photoresist is formed over a dielectric layer. The photoresist layer is processed to have fully developed areas corresponding to contact windows, partially developed areas corresponding to the patterned conductive lines and undeveloped areas which correspond to field areas where the entire dielectric layer is maintained. The dielectric layer is preferably a compound dielectric layer to reduce interlevel shorts. Through the use of selective etch steps, the compound dielectric layers aid in the formation of the patterned conductive line and contact window structure. A series of reactive ion etch (RIE) steps are performed. The first RIE step, highly selective to dielectric material as compared to photoresist, etches the fully developed areas at least partially through the dielectric thickness.

Abstract: A method for providing increased dopant concentration in selected regions of semiconductors by providing field implant dopant in the transition region located below the "bird's beak" region and between the field and active regions of a semiconductor. The method comprises the steps of: forming a thin insulating layer on the surface of a semiconductor substrate; depositing a thin anti-oxidant layer on the insulating layer; depositing a layer of photoresist on the anti-oxidant layer; selectively etching the anti-oxidant layer; ion-implanting the field region of the semiconductor substrate; providing spacers on the sides of the anti-oxidant layer; and oxidizing the semiconductor substrate.

Abstract: A read/write memory cell is disclosed in which multiple ROM data states can be stored. Independent sensing of the resistance values of each of two resistors accounts for the storage of multiple ROM data states. The resistors are encompassed in a pair of cross-coupled resistive gate devices forming branch circuits, thereby allowing each branch circuit to control the conduction of current in the other branch circuit. This allows for read/write data storage in flip-flop-like fashion. In addition, since resistive gate devices are used, the ROM data may be programmed during the later stages of manufacturing.

Abstract: A resistor personalized memory cell consisting of a resistive gate field effect transistor. One end of the gate electrode is connected to the memory cell access line, the other end to one of its source or drain regions. The source or drain region not connected to the gate electrode is connected to the memory cell bit line. Memory cell personalization is accomplished by selecting the resistance of the resistive gate. Memory cell data is read by detecting the current flow through the cell, the magnitude of the current flow being proportional to the gate resistance.

Abstract: A method making self-aligned semiconductors utilizing two resist masking steps to form a device; making one of the masks insoluable with respect to the other so that when a first part of the device is formed by a first mask, and a second part of the device is formed by the second masks, the parts are self-aligned when the first resist is dissolved.

Abstract: The process sequence is disclosed which applies a polycrystalline silicon gate material, then applies a chemical vapor deposition oxide over all surfaces, forming an effective sidewall on each of the polycrystalline silicon gate structures. An ion implantation step is then carried out to implant source and drain regions whose proximate edges are not aligned with the edges of the polycrystalline silicon gate material itself, due to the masking effect of the sidewall portion of the chemical vapor deposition oxide layer. Thereafter, the chemical vapor deposition oxide sidewall material is selectively removed for those FET device locations where an active FET device is desired to be formed in the operation of personalizing the read only storage or PLA product. Those locations are then ion implanted for source and drain extensions which are then self-aligned with the respective edges of the respective polycrystalline silicon gate electrodes.

Abstract: A combined read-only storage (ROS) and read/write random access memory (RAM) integrated circuit memory cell is disclosed. In a first cell embodiment, a ROS FET device and a RAM FET device are connected in common to a bit sensing line connected to a sense amplifier which senses if the ROS FET device has discharged the bit sensing line indicating that a gate is present on the ROS FET device. A write driver circuit is also connected to the bit sensing line, for providing current through the RAM FET device to the charge storage element for writing a one or a zero therein. In a second cell embodiment, a combined two-bit read-only storage and one-bit read/write random access memory integrated circuit cell is disclosed. The bit sensing line is shared by two ROS FET devices and one RAM FET device. In a third cell embodiment of the invention, a single binary bit is stored for read-only storage and a single binary bit is stored for read/write random access memory storage.

Abstract: A two carrier dual injector semiconductor apparatus utilizing a pair of injector gates for simultaneously injecting holes and electrons into a series stack of insulator layers. The stacked insulator layers which may be arranged in a MIM or MIS configuration have injecting layers near opposing metal gates for injecting either electrons as holes into the insulator layers depending upon the polarity of the applied bias voltage. The apparatus is capable of high-current low-voltage carrier injection while maintaining a stable trapped spaced charge within the stack of insulator layers.

Abstract: This invention provides improved non-volatile semiconductor memories which include a volatile latch circuit having a data node and first and second cross-coupled transistors, at least one of the transistors has first and second control gates, a floating gate and an enhanced conduction insulator or dual electron injector structure disposed between the first control gate and the floating gate. The second control gate is connected to the storage node. A control voltage source is connected to the first control gate for transferring charge between the enhanced conduction insulator or dual electron injector structure and the data node.

Abstract: This invention provides improved non-volatile semiconductor memories which include a volatile circuit coupled to a non-volatile device having a floating gate and first and second control gates capacitively coupled to the floating gate with a charge injector structure disposed between the floating gate and one of the two control gates. The volatile circuit may be a dynamic one-device cell or a static cell such as a conventional flip-flop or latch cell.

Abstract: An electrically alterable double dense memory is provided which includes a field effect transistor having first and second spaced apart diffusion regions of a first conductivity defining a channel region at the surface of a semiconductor substrate having a second conductivity. First and second floating gates are disposed over the first and second diffusion regions, respectively, and each extends over an end of the channel region. First and second dual charge injector structures or enhanced conduction insulators are disposed between the first and second floating gates and a common control gate of the transistor. A word line is connected to the control gate and first and second bit lines are connected to the first and second diffusion regions. By applying appropriate pulses to the word and bit lines, a selected floating gate can be charged to alter the conductivity of the end of the channel region associated with the selected floating gate and then discharged at will.

Abstract: This invention provides improved non-volatile semiconductor memories which include a one device dynamic volatile memory circuit having a storage capacitor with a plate and a storage node coupled to a non-volatile device having a floating gate, a control gate and a voltage divider having first and second serially-connected capacitors, with the floating gate being disposed at the common point between the first and second capacitors. The plate of the storage capacitor is connected to a reference voltage source. The control gate is preferably capacitively coupled to the floating gate through the first capacitor which includesa dual charge or electron injector structure. The capacitance of the first capacitor has a value substantially less than that of the second capacitor.

Abstract: The invention is the structure and process for making a bucket brigade device which comprises the merger of an MOS capacitor with an MOSFET device to form the charge transfer cell. A first thin N-type region is implanted at a first concentration in a portion of the P-type channel region of an FET device adjacent to the drain diffusion. A second region is implanted with N-type dopant at a second concentration less than the first concentration, adjacent to and continuous with the first implanted region. The N-type concentration in the second region is just sufficient to compensate for the P-type background doping in the channel region. This structure increases the charge transfer efficiency for the cell and reduces its sensitivity of the threshold voltage to the source-drain voltage. The gate for the device has a substantial overlap over the drain and a minimal overlap over the source and the gate to drain capacitance per unit area is maximized by maintaining a uniformly thin oxide layer across the gate region.

Abstract: A memory system is provided for charging and discharging small cells each of which has only three terminals with a charge injector controlled by a low single polarity voltage. Each of the cells includes a transistor having a current carrying electrode and a floating gate, with a control gate arranged so that a first capacitor is serially connected with a second capacitor between the current carrying electrode and the control gate, with one of the capacitors having a substantially larger capacitance than that of the other capacitor and with the other capacitor including a charge injector. The common point between the first and second capacitors is connected to the floating gate. The charge injector may include a single graded or stepped composition region or two such regions disposed near opposite faces or plates of the other capacitor, or more particularly the injector may include silicon rich regions near one or both faces of a layer of silicon dioxide.

Abstract: An improved memory system is provided for charging and discharging a conductive plate such as a floating gate of a field effect transistor with a charge injector controlled by a low single polarity voltage pulse. In the system of the invention, the conductive plate may be a floating gate of a field effect transistor which also includes first and second or dual control gates. A single or double graded band gap layer, such as a silicon rich layer of silicon dioxide is disposed only between the floating gate and the first control gate forming a capacitor having a given capacitance with a larger capacitor disposed between the second control gate and the floating gate. These cells or transistors may be used in an array for storing for long periods of time, on the order of 10 years or more, binary digits of information representing a 0 or a 1 depending upon whether a charge is stored on the floating gate.

Abstract: A semiconductor fabrication process and the resulting structure is disclosed for an FET device with a precisely defined channel length. Two process embodiments are described to make a diffused MOS device which does not require the use of p-type diffusions to obtain 1 micron channel length. Instead, to accurately define such micron-range channel lengths, a lateral etching technique is employed. To obtain well controlled threshold voltages, the channels are ion implanted. Thus the enhancement portion of the diffused MOS device channel is defined by an etching step instead of a diffusion step, thereby producing a channel having a length which is shorter and a threshold voltage which is better controlled than those which have been available in the prior art.

Abstract: A MOSFET device structure is disclosed where the channel region has formed therein a buried layer of dopant of the same conductivity type as the source and drain, so that the depletion layers for the PN junctions at the upper and lower boundaries thereof intersect in the middle of the implanted region, effectively forming a buried insulator layer between the source and drain. The presence of this layer increases the distance between the mirrored electrostatic charges in the gate and in the bulk of the substrate beneath the MOSFET, thereby reducing the sensitivity of the threshold voltage of the device to variations in the source to substrate voltage.

Abstract: A quaternary FET read only memory is disclosed wherein each FET storage element in the array has its threshold adjusted by ion-implantation to one of four values. Each FET element in the array has its drain connected to a drain potential V.sub.DD. A binary input signal from a conventional binary, true/complement generator will then enable the gate of a selected FET storage cell and the output potential at the source of that selected storage cell will be V.sub.DD minus the customized threshold voltage of that storage cell, which is output at an output node. The signal on the output node is a quaternary signal which may be amplified by a quaternary sense amplifier circuit and then converted from quaternary to binary signal by means of a converter. The quaternary read only memory is capable of storing twice as much information per unit area as is a conventional FET binary read only memory. The concept may be expanded to N levels of information storage, using FET array devices with N different threshold voltages.

Abstract: An insulated gate field effect transistor (IGFET) static inverter having an improved load line characteristic is disclosed. The inverter comprises an enhancement mode IGFET active device in a first portion of a semiconductor substrate, having its drain connected to an output node, its source connected to a source potential and its gate connected to an input signal source. The first portion of the substrate is connected to a first substrate potential. A depletion mode IGFET load device is located in a second portion of the semiconductor substrate which is electrically isolated from the first portion. The depletion mode load device has its drain connected to a drain potential and its source, gate and the second portion of the semiconductor substrate all connected to the output node. In this manner, the rise in the source-to-substrate voltage bias during the turn-off transition is eliminated in the depletion mode load device, providing an improved load current characteristic for the inverter.

Abstract: A quaternary FET read only memory is disclosed wherein each FET storage element in the array has its threshold adjusted by ion-implantation to one of four values. Each FET element in the array has its drain connected to a drain potential V.sub.DD. A binary input signal from a conventional binary, true/complement generator will then enable the gate of a selected FET storage cell and the output potential at the source of that selected storage cell will be V.sub.DD minus the customized threshold voltage of that storage cell, which is output at an output node. The signal on the output node is a quaternary signal which may be amplified by a quaternary sense amplifier circuit and then converted from quaternary to binary signal by means of a converter. The quaternary read only memory is capable of storing twice as much information per unit area as is a conventional FET binary read only memory. The concept may be expanded to N levels of information storage, using FET array devices with N different threshold voltages.