Nonvolatile semiconductor memory device and methods for operating and producing the same

A method for operating a nonvolatile semiconductor memory device comprising a channel forming region comprised of a first conductivity type semiconductor, two impurity regions comprised of a second conductivity type semiconductor and separated from each other across the channel forming region, a charge storing film including a plurality of stacked dielectric films and having a charge storing capability, two storage portions comprised of regions of the charge storing film overlapping with two ends of the channel forming region at the two impurity region sides, a single layer dielectric film contacting the channel forming region between the storage portions, a memory gate electrode contacting the storage portions, and a control gate electrode on the single layer dielectric film,

• said operation including a write operation comprising the steps of:
• applying a predetermined voltage between the two impurity regions so as to make the impurity region located near the storage portion side to be written the drain and to make the other the source;
• applying a specified voltage to each of the memory gate electrode and the control gate electrode to form a channel between the two impurity regions;
• and
• injecting part of the carriers injecting in the channel into the drain side storage portion.

A method for operating a nonvolatile semiconductor memory device comprising a channel forming region comprised of a first conductivity type semiconductor, two impurity regions comprised of a second conductivity type semiconductor and separated from each other across the channel forming region, a charge storing film including a plurality of stacked dielectric films and having a charge storing capability, two storage portions comprised of regions of the charge storing film overlapping with two ends of the channel forming region at the two impurity region sides, a single layer dielectric film contacting the channel forming region between the storage portions, a memory gate electrode contacting the storage portions, and a control gate electrode on the single layer dielectric film,

• said operation including a write operation comprising the steps of:
• applying a voltage between the memory gate electrode and the impurity region located at the storage portion side where the data is to be written in a direction so as to invert the impurity region;
• generating high energy charges by avalanche breakdown caused in an inversion layer of the impurity region at the time of applying the voltage;
• and
• injecting part of the generated high energy charge into the storage portion of the side where data is to be written.

A method for operating a nonvolatile semiconductor memory device comprising memory cells arranged in a matrix to form a memory cell array, each of said memory cell comprising a channel forming region comprised of a first conductivity type semiconductor, two impurity regions comprised of a second conductivity type semiconductor and separated from each other across the channel forming region, a charge storing film including a plurality of stacked dielectric films and having a charge storing capability, two storage portions comprised of regions of the charge storing film overlapping with two ends of the channel forming region at the two impurity region sides, a single layer dielectric film contacting the channel forming region between the storage portions, a memory gate electrode contacting the storage portions, and a control gate electrode on the single layer dielectric film;

• the memory gate electrode being shared among a plurality of cells in the direction of separation of the impurity regions and comprising a word line;
• each of the two impurity regions being shared among a plurality of cells in the direction perpendicular to the word line and comprising a bit line;
• and the control gate electrode being arranged in parallel to the bit line and shared among a plurality of cells in a direction perpendicular to the word line,
• said method including a read operation comprising a step of applying a voltage of a direction giving a forward bias to the channel forming region to a nonselected word line in a row not including the memory cell to be read.

A method for operating a nonvolatile semiconductor memory device comprising a plurality of memory cells arranged in a matrix to form a memory cell array, each of said memory cell comprising a channel forming region comprised of a first conductivity type semiconductor, two impurity regions comprised of a second conductivity type semiconductor and separated from each other across the channel forming region, a charge storing film including a plurality of stacked dielectric films and having a charge storing capability, two storage portions comprised of regions of the charge storing film overlapping with two ends of the channel forming region at the two impurity region sides, a single layer dielectric film contacting the channel forming region between the storage portions, a memory gate electrode contacting the storage portions, and a control gate electrode on the single layer dielectric film;

• the memory gate electrodes in the same row being connected by a word line;
• each of the two impurity regions being arranged longwise in the column direction and shared between memory cells adjoining in the row direction;
• and the control gate electrode being arranged longwise in the column direction and shared between memory cells in the same column,
• said method comprising the steps of:
• driving the control gate electrodes to divide the memory cell array electrically;
• and
• driving the impurity regions and the word lines to write, read, or erase data in parallel a plurality of cells in the divided memory cell array.

A method for operating a nonvolatile semiconductor memory device comprising a plurality of memory cells arranged in a matrix to form a memory cell array, each of said memory cell comprising a channel forming region comprised of a first conductivity type semiconductor, two impurity regions comprised of a second conductivity type semiconductor and separated from each other across the channel forming region, a charge storing film including a plurality of stacked dielectric films and having a charge storing capability, two storage portions comprised of regions of the charge storing film overlapping with two ends of the channel forming region at the two impurity region sides, a single layer dielectric film contacting the channel forming region between the storage portions, a memory gate electrode contacting the storage portions, and a control gate electrode on the single layer dielectric film;

• the memory gate electrodes in the same row being connected by a word line;
• each of the two impurity regions being arranged longwise in the column direction and shared between memory cells adjoining in the row direction;
• and the control gate electrode being arranged longwise in the column direction and shared between memory cells in the same column,
• the method including a write operation comprising the steps of:
• alternately applying a write drain voltage and a reference voltage to the impurity regions in the memory cell array;
• applying an ON voltage for shifting a channel from an OFF state to a possible ON state to the control gate electrode in combination according to the data to be written;
• selecting a storage portion located between the control gate electrode applied with the ON voltage and the impurity region applied with the write drain voltage;
• applying a specified voltage to a word line of a selected row in which the data is to be written to turn the channel on beneath the selected storage portion and injecting part of the carriers injecting in the channel in the selected storage portion;
• reapplying the write drain voltage and reference voltage to the impurity regions in the memory cell array while switching the locations of application;
• reapplying the ON voltage to the control gate electrode in combination according to the data to be written;
• selecting the remaining storage portion different from above storage portion;
• and
• reapplying the voltage to the word line and turning the channel on beneath the selected storage portion and injecting part of the carriers injecting in the channel in the selected storage portion.

A method for operating a nonvolatile semiconductor memory device comprising a plurality of memory cells arranged in a matrix to form a memory cell array, each of said memory cell comprising a channel forming region comprised of a first conductivity type semiconductor, two impurity regions comprised of a second conductivity type semiconductor and separated from each other across the channel forming region, a charge storing film including a plurality of stacked dielectric films and having a charge storing capability, two storage portions comprised of regions of the charge storing film overlapping with two ends of the channel forming region at the two impurity region sides, a single layer dielectric film contacting the channel forming region between the storage portions, a memory gate electrode contacting the storage portions, and a control gate electrode on the single layer dielectric film;

• the memory gate electrodes in the same row being connected by a word line;
• each of the two impurity regions being arranged longwise in the column direction and shared between memory cells adjoining in the row direction;
• and the control gate electrode being arranged longwise in the column direction and shared between memory cells in the same column,
• said method having a read operation comprising the steps of:
• a first reading step of reading one storage portion in the odd-numbered memory cells included in the same row of the memory cell array;
• a second reading step of reading the other storage portion of the odd-numbered memory cells included in the same row;
• a third reading step of reading one storage portion of even-numbered memory cells included in the same row;
• and
• a fourth reading step of reading the other storage portion of the even-numbered memory cells included in the same row.