| 摘要 |
Memory cells 10, according to the present invention, are comprised of a semiconductor substrate 2, and device isolating/insulating films 3 on the semiconductor substrate 2. A source region 4 and drain regions 5 are formed on the surface of the semiconductor substrate 2 within the device fabricating region, which is enclosed with the device isolating/insulating films 3. Floating gate electrodes 24 are formed above the semiconductor substrate 2. Each channel/gate insulating film 14a is formed between each channel region 23 and its corresponding floating gate electrode 24. Wherein, each channel region 23 is located between the source region 4 and one of the drain regions 5. Each tunnel oxide film 15, which is thinner than each channel/gate insulating film 14a, is formed between part of each drain region 5 and its corresponding floating gate electrode 24. Wherein the part is located far away from the depletion layer, which exists between each drain region 5 and its adjacent channel region 23. Each floating gate electrode 24 is insulated by an ONO (oxide/nitride/oxide) film 22, on which a control gate 6 is formed.
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