Ballistic injection NROM flash memory

A non-volatile memory cell array, comprising:

• a plurality of non-volatile memory cells coupled together through wordlines and bitlines, each cell comprising:
• a substrate having a pair of source/drain regions, the pair of source/drain regions being linked by a channel in the substrate, the channel comprising a vertical section and a planar section;
• a first and a second nitride storage element each located over the channel, the first and the second nitride storage elements being separated from each other, the first nitride charge storage element establishing a virtual source/drain region in the channel;
• and
• a control gate formed over the first and the second separated nitride charge storage elements and the control gate further comprising a section formed between the first and the second nitride storage elements such that the depression electrically isolates the pair of nitride storage elements.

An electronic system comprising:

• a processor that generates memory control signals;
• and
• an NROM non-volatile memory cell array coupled to the processor and comprising a plurality of NROM non-volatile memory cells coupled together through wordlines and bitlines, each cell comprising:
• a substrate having a pair of source/drain regions, the pair of source/drain regions being linked by a channel in the substrate, the channel comprising a vertical section and a planar section;
• first and a second nitride storage element each located over the channel, the first and the second nitride storage elements being separated from each other, the first nitride charge storage element establishing a virtual source/drain region in the channel;
• and
• a control gate formed over the first and the second separated nitride charge storage elements and the control gate further comprising a section formed between the first and the second nitride storage elements such that the depression electrically isolates the pair of nitride storage elements.

A method of fabricating a non-volatile memory cell, comprising:

• doping a substrate with a plurality of source/drain regions;
• forming an oxide layer on a surface of the substrate;
• depositing a nitride layer on the oxide layer;
• etching the nitride layer to form a plurality of separated nitride storage elements;
• forming a second oxide over the separated nitride storage elements, the second oxide layer having a depression therein between the separated nitride storage elements;
• and
• depositing a control gate over the second oxide layer, the control gate having a section deposited between the separated nitride storage elements to electrically isolate the nitride storage elements.

A method of programming a non-volatile memory cell comprising a plurality of nitride charge storage regions located between a substrate having two source/drain regions and a control gate, the two source/drain regions linked by a channel region in the substrate, the channel region having both a vertical and a horizontal portion, the method comprising:

• applying a drain bias to one of the source/drain regions to cause the channel region nearest the drain to pinch off;
• biasing the control gate;
• and
• biasing the second source/drain region to accelerate hot electrons in a narrow virtual source/drain region near the drain to inject the hot electrons directly onto the nitride storage region nearest the drain.

A method of ballistic direction injection in a non-volatile memory cell having a pair of source/drain regions linked by a channel in a substrate, the channel having a vertical section and a planar section, a pair of nitride storage elements located over the channel and separated from each other, the first nitride charge storage element establishing a virtual source/drain region in the channel, and a control gate over the nitride storage elements having a section formed between nitride storage elements to electrically isolate the pair of nitride storage elements, the method comprising:

• over-erasing the cell to leave the separated nitride storage regions with an absence of electrons;
• applying a drain voltage to one of the source/drain regions to pinch off the channel away from the drain region by causing a high density of electrons near the other of the source/drain regions;
• and
• injecting hot electrons directly onto the nitride storage region near the drain.