Abstract: A floating-gate non-volatile memory (30) uses a relatively-low threshold voltage to define a programmed state. The memory (30) compensates for fast program cells by providing program pulses which increase in length and magnitude while the cells are being programmed. Between each program pulse the memory (30) determines whether selected cells have been adequately programmed. The memory (30) ceases applying the series of pulses to each cell when it has been adequately programmed. Thus the memory (30) avoids the over-program condition instead of compensating for it.

Abstract: A memory circuit and method of formation uses a transmission gate (24) as a select gate. The transmission gate (24) contains a transistor (30) which is an N-channel transistor and a transistor (28) which is a P-channel transistor. The transistors (28 and 30) are electrically connected in parallel. The use of the transmission gate (24) as a select gate allows reads and writes to occur to a memory cell storage device (i.e. a capacitor (32), a floating gate (22), etc.) without a significant voltage drop occurring across the transmission gate. In addition, EEPROM technology is more compatible with EPROM/flash technology when using a transmission gate as a select gate within EEPROM devices.

Abstract: A memory circuit and method of formation uses a transmission gate (24) as a select gate. The transmission gate (24) contains a transistor (30) which is an N-channel transistor and a transistor (28) which is a P-channel transistor. The transistors (28 and 30) are electrically connected in parallel. The use of the transmission gate (24) as a select gate allows reads and writes to occur to a memory cell storage device (i.e. a capacitor (32), a floating gate (22), etc.) without a significant voltage drop occurring across the transmission gate. In addition, EEPROM technology is more compatible with EPROM/flash technology when using a transmission gate as a select gate within EEPROM devices.

Abstract: A process for fabricating an improved nonvolatile memory device includes the formation of a control gate electrode (70) which overlies a floating gate electrode (42) and is separated therefrom by an inter-level-dielectric layer (62). The control gate electrode (70) and the underlying floating gate electrode (42) form a stacked gate structure (72) located in the active region (44) of a semiconductor substrate (40). An electrically insulating sidewall spacer (54) is formed at the edges of the floating gate electrode (42) and electrically isolates the control gate (70) from the semiconductor substrate (40). During the fabrication process, implanted memory regions (56, 58) are formed in the active region (44) prior to the formation of control gate electrode (70). A word-line (68) and the control gate (70) are formed by anisotropic etching of a semiconductor layer (66), which is deposited to overlie inter-level-dielectric layer (62).

Abstract: A static RAM includes test features which provide for the detection of soft defects which may cause a defective SRAM cell to behave as a functional DRAM cell. Provision is made for writing either a high or a low logic state to each bit line of the SRAM while not writing any value to its complementary bit line and for sensing the state of each bit line independently of the state of its complementary bit line. In addition, a current test is provided which detects soft defects by means of the increased inverter leakage current caused thereby. It is possible, by properly combining these tests, to reliably detect all soft defects, thereby assuring the data retention capability of the SRAM. This technique avoids the long hold time and/or high temperature test techniques used in the prior art.

Abstract: A flash EEPROM array (22) is erased and a threshold voltage distribution of the erased flash EEPROM cells (36, 39-46) is converged to within a predetermined voltage range by using a two-step erasing procedure. In the first step, flash EEPROM array (22) is electrically bulk erased using a conventional bulk erase procedure. Electrons are tunneled from the floating gate (38) to the source, causing cells (36, 39-46) to have a relatively low threshold voltage. In the second step, the threshold voltage distribution of the array (22) is converged to within the predetermined voltage range by grounding the source and drain of each cell (36, 39-46), while concurrently applying a high positive voltage to the control gate (27) of each cell (36, 39-46). Some electrons are tunneled back to the floating gate (38), thus converging the threshold voltage distribution to within a predetermined range.

Abstract: A block erasable flash EEPROM (22) having a single array (68) which can be partitioned into one or more blocks (50-57). The same column decode/block select circuitry (66) is used to provide both column select signals (71) and block select signals (73). The number of blocks (50-57) and the size of each block (50-57) can be determined by the manufacturer during the manufacturing process. Each block (50-57) has a corresponding charge pump (80-87). Each charge pump (80-87) is capable of erasing a single block within the array (68). Each charge pump (80-87) has a variable capacitor (90-97). Each of the variable capacitors (90-97) can be sized according to the size of its corresponding block (50-57).

Abstract: An EEPROM cell (10) has a tunnel opening (28) which overlaps both an active region (12) and field isolation regions (14). A tunnel area (30), which is that portion of the cell in which electrons tunnel through a tunnel dielectric (32) to charge or discharge a floating gate (22) during device operation, is defined as the overlapped portion of the tunnel opening (28) and the active region (12). By having the tunnel opening (28) larger than the tunnel area (30), etch processes used to pattern the opening in a gate dielectric (26) are more easily controlled and the active region area beneath the floating gate is reduced. The EEPROM cell (10) has a tunnel area which is limited in size by lithographic resolution capabilities rather than by limitations in dielectric etch processes. The tunnel features increase a capacitance coupling ratio of the cell.

Abstract: A floating gate is utilized which has two portions. A first portion overlies the channel region formed between the source and drain. The control gate overlies this portion of the floating gate and the remaining portion of the channel region forming an enhancement transistor. The second portion of the floating gate extends from the first portion over a thin oxide tunnel area of the source. An additional diode implant forming a junction with the drain region is provided to regulate the current flow through the drain, particularly during erasure.

Abstract: A static RAM includes test features which provide for the detection of soft defects which may cause a defective SRAM cell to behave as a functional DRAM cell. Provision is made for writing either a high or a low logic state to each bit line of the SRAM while not writing any value to its complementary bit line and for sensing the state of each bit line independently of the state of its complementary bit line. In addition, a current test is provided which detects soft defects by means of the increased inverter leakage current caused thereby. It is possible, by properly combining these tests, to reliably detect all soft defects, thereby assuring the data retention capability of the SRAM. This technique avoids the long hold time and/or high temperature test techniques used in the prior art.

Abstract: A memory has a programmable circuit which allows a user to select an amount of redundancy the memory has varying from zero percent to one-hundred percent. A received address is compared by the circuit with a redundancy percentage control signal to determine if the address falls within a redundant portion of the memory. If so, a redundancy enable signal is asserted to allow the memory to utilize the redundant circuitry.

Abstract: A single transistor EEPROM cell comprises a source, a channel, a drain, a floating gate and a control gate. The control gate and the floating gate are co-extensive over the channel. Programming is achieved by charge injection from the channel and erasing is achieved by tunneling to the source. An array organization is disclosed which features a source/erase control line shared between two adjacent rows of the array, providing efficient byte-at-a-time erasing. An erasure scheme is disclosed which involves repetitive erase pulse-read-erase pulse cycles together with means for assuring complete erasure while preventing over-erasure from driving any cell in the array into depletion mode.

Abstract: A single transistor EEPROM cell comprises a source, a channel, a drain, a floating gate and a control gate. The control gate and the floating gate are co-extensive over the channel. Programming is achieved by charge injection from the channel and erasing is achieved by tunneling to the source. An array organization is disclosed which features a source/erase control line shared between two adjacent rows of the array, providing efficient byte-at-a-time erasing. An erasure scheme is disclosed which involves repetitive erase pulse-read-erase pulse cycles together with means for assuring complete erasure while preventing over-erasure from driving any cell in the array into depletion mode.

Abstract: An EEPROM has two arrays which provide data in response to an address. The EEPROM can be programmed to function in one of two modes. The EEPROM can supply data from a selected one of the arrays or can simultaneously supply data from both arrays. In the mode in which data is supplied simultaneously from both arrays, the data from both arrays is coupled to a common data line where the data is sensed by a sense amplifier.

Abstract: A high voltage circuit provides a high voltage signal output in response to receiving a logic signal. The high voltage circuit includes a regenerative circuit which is coupled to a high voltage terminal and a 5 volt power supply terminal. An inverting push-pull buffer responsive to the logic signal provides a signal which is regenerated to the high voltage by the regenerative circuit when the logic signal is in a first state and maintains the signal at ground potential when the logic signal is in a second logic state.

Abstract: An oscillator with inverter and delay stages is coupled between first and second reference terminals. In one aspect a depletion transistor is connected between a power supply terminal and the first reference terminal to provide a reference voltage thereat. In another aspect the delay stages each have a control terminal for controlling the delay thereof. A temperature compensation circuit has a control transistor which provides a voltage to the control terminals of the delay stages which is inversely proportional to the threshold voltage of the control transistor.

Abstract: An electrically erasable programmable read only memory (EEPROM) cell has a floating gate transistor and a select transistor in series. A control gate of the select transistor extends to an area which overlies an extended portion of a floating gate of the floating gate transistor to form an erase window so that the EEPROM cell can be erased by application of an erase signal to the control gate of the select transistor.

Abstract: A sense amplifier quickly charges a column line to a first predetermined voltage level with first, second and third transistors and then charges the column to a second predetermined voltage by using only the second and third transistors. The second and third transistors continue charging to the second predetermined voltage by virtue of having a lower threshold voltage than the first transistor. If a selected memory cell in the column is in a conducting state, the column charges to only the first predetermined voltage for detection as a logic "0". If the selected memory cell in the column is in a non-conducting state, the column continues charging to the second predetermined voltage for detection as a logic "1".

Abstract: A fusible link is selectively opened by selectively applying a high voltage signal to a transistor in series with the fusible link while the high voltage signal is applied to the fusible link. A grounding circuit ensures that one terminal of the fusible link is coupled to ground in the absence of the high voltage signal. The grounding circuit can be used in conjunction with a plurality of means for selectively opening fusible links.

Abstract: An EEPROM which can erase an array of memory cells to all "1"s is capable of causing all of the cells of the array to assume all "0"s, also. The array of memory cells is arranged with one of said memory elements at the intersection of each of a plurality of rows and columns. The memory elements are characterized as assuming relatively high threshold voltage states in response to an erase voltage and relatively low threshold voltage states in response to a program voltage. All columns and rows are selected in order to apply the program voltage to all of the memory elements.