Non-volatile memory cell
View Patent ↗A memory cell stores data permanently in a memory material that can assume a first, high-resistance state and a second, low-resistance state, that is in a phase-changeable or ovonic material. A heating device is disposed to heat the memory material at different rates to a programming temperature. The memory material either has a high resistance or a low resistance after cooling, depending on the heating rate. The heating device has a switching device and a heating element in immediate vicinity to the memory material. The switching device has a field-effect transistor and a drain region of the field-effect transistor forms the heating element. Alternatively, the heating element includes a diode or a diode chain.
1. A memory cell for permanently storing data, comprising:
a memory material capable of assuming a first, high-resistance state and a second, low-resistance state;
a heating device configured to heat said memory material at different heating rates to a programming temperature, said memory material having a relatively high resistance or a relatively low resistance after cooling, depending on the heating rate;
said heating device having a switching device and a heating element in direct proximity with said memory material, and said switching device having a field-effect transistor with a drain region formed as a heating region.
2. The memory cell according to claim 1 , wherein said drain region comprises a highly doped contact-making region for making contact with said memory material.
3. The memory cell according to claim 1 , wherein said field-effect transistor is formed vertically in a substrate, and an insulation material having low thermal conductivity surrounds said field effect transistor.
4. The memory cell according to claim 3 , wherein said insulation material contains a silicon compound.
5. The method cell according to claim 4 , wherein said insulation material is a silicon compound selected from the group consisting of silicon dioxide and silicon nitride.
6. A memory cell for permanently storing data, comprising:
a memory material capable of assuming a first, high-resistance state and a second, low-resistance state;
a heating device configured to heat said memory material at different heating rates to a programming temperature, said memory material having a relatively high resistance or a relatively low resistance after cooling, depending on the heating rate;
said heating device having a switching device and a heating element in direct proximity with said memory material, and said heating element has a diode device.
7. The memory cell according to claim 6 , wherein said diode device is a diode or a diode chain.
8. The memory cell according to claim 6 , wherein said diode device is formed by a semiconductor material exhibiting functionality at a programming temperature.
9. The memory cell according to claim 6 , wherein said switching device is a transistor.
10. The memory cell according to claim 6 , wherein said switching device is a field-effect transistor or a bipolar transistor.
11. The memory cell according to claim 6 , wherein said switching device has a field-effect transistor and said diode device is formed by a layer sequence on a drain region of said field-effect transistor.
12. The memory cell according to claim 11 , which comprises a thermal resistor formed between said layer sequence of said diode device and said drain region of said field-effect transistor.
13. The memory cell according to claim 12 , wherein said thermal resistor is a highly conductive semiconductor layer.
14. The memory cell according to claim 6 , wherein said thermal resistor is a highly doped semiconductor layer.
15. The memory cell according to claim 6 , wherein said diode device comprises one of more Zener diodes.