Charge trapping memory cell and fabrication method
First Claim
1. A charge trapping memory cell comprising:
- a well in a semiconductor body, said well being doped to a first conductivity type,a source region and a drain region formed at a top side of the semiconductor body and doped to a second conductivity type tat is opposite the first conductivity type;
a trench formed in the semiconductor body, said trench extending into the doped well below the source and drain regions;
a first gate electrode located at least in a bottom portion of the trench, said first gate electrode electrically insulated from the well by a gate dielectric;
a second gate electrode extending into the trench toward said first gate electrode and arranged in the trench above the first gate electrode and electrically insulated from the first gate electrode; and
a storage layer sequence comprising first and second boundary layers and a storage layer, said storage layer provided for charge trapping being sandwiched between said first and second boundary layers, and at least portions of the storage layer sequence being arranged between the second gate electrode and the doped well and/or between the second gate electrode and the source and drain regions.
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Accused Products
Abstract
A memory cell patterned as a trench transistor is provided with a first gate electrode (4) as auxiliary gate for source-side injection and a second gate electrode (5) electrically insulated therefrom, which are arranged in the trench, and has, at the trench walls, a storage layer sequence (10) provided for charge trapping and comprising a storage layer (12) between boundary layers (11, 13). The first gate electrode (4) and the second gate electrode (5) are electrically insulated from one another, which can be effected by means of a portion of the storage layer sequence (10). Source/drain regions (3) are arranged on the top side laterally with respect to the trenches. Word lines (6), source/drain lines and control gate lines are present for the electrical driving.
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Citations
20 Claims
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1. A charge trapping memory cell comprising:
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a well in a semiconductor body, said well being doped to a first conductivity type, a source region and a drain region formed at a top side of the semiconductor body and doped to a second conductivity type tat is opposite the first conductivity type; a trench formed in the semiconductor body, said trench extending into the doped well below the source and drain regions; a first gate electrode located at least in a bottom portion of the trench, said first gate electrode electrically insulated from the well by a gate dielectric; a second gate electrode extending into the trench toward said first gate electrode and arranged in the trench above the first gate electrode and electrically insulated from the first gate electrode; and a storage layer sequence comprising first and second boundary layers and a storage layer, said storage layer provided for charge trapping being sandwiched between said first and second boundary layers, and at least portions of the storage layer sequence being arranged between the second gate electrode and the doped well and/or between the second gate electrode and the source and drain regions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A charge trapping memory cell comprising:
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a well in a semiconductor body, said well being doped to a first conductivity type, a source region and a drain region formed at a top side of the semiconductor body and doped to a second conductivity type that is opposite the first conductivity type; a trench formed in the semiconductor body, said trench extending into the doped well below the source and drain regions; a gate electrode, which is electrically insulated from the well by a gate dielectric, the gate electrode being arranged as a first gate electrode in the trench and at least in a bottom portion of the trench; a second gate electrode arranged in the trench above the first gate electrode and electrically insulated from the first gate electrode; and a storage layer sequence comprising first and second boundary layers and a storage layer, said storage layer provided for charge trapping being sandwiched between said first and second boundary layers, and at least portions of the storage layer sequence being arranged between the second gate electrode and the doped well and other portions being arranged between the second gate electrode and the source and drain regions.
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12. A charge trapping memory cell comprising:
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a well in a semi conductor body, said well being doped to a first conductivity type, a source region and a drain region formed at a top side of the semiconductor body and doped to a second conductivity type that is opposite the first conductivity type; a trench formed in the semiconductor body, said trench extending into the doped well below the source and drain regions; a gate electrode, which is electrically insulated from the well by a gate dielectric, the gate electrode being arranged as a first gate electrode in the trench and at least in a bottom portion of the trench; a second gate electrode arranged in the trench above the first gate electrode and electrically insulated from the first gate electrode; and a storage layer sequence comprising first and second boundary layers and a storage layer, said storage layer provided for charge trapping being sandwiched between said first and second boundary layers, and at least a portion of the storage layer sequence providing said electrical insulation between said first gate electrode and said second electrode, and another portion being arranged between the second gate electrode and the doped well and/or between the second gate electrode and the source and drain regions. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification