Scalable embedded DRAM array
View Patent ↗A method and apparatus for scaling an embedded DRAM array from a first process to a second process, wherein the scaling involves reducing the linear dimensions of features by a constant scale factor. From the first process to the second process, DRAM cell capacitor layout area is reduced by the square of the scale factor, while cell capacitance is reduced by the scale factor. The voltage used to supply the logic transistors is scaled down from the first process to the second process. However, the voltage used to supply the sense amplifiers remains constant in both processes. Thus, in an embedded DRAM array of the second process, sense amplifiers are supplied by a greater voltage than the logic transistors. This allows the sensing voltage of DRAM cells to be maintained from one process generation to another, while allowing memory size to scale with the square of the process scale factor.
1. An integrated circuit comprising:
a first voltage supply terminal configured to receive a first supply voltage;
logic circuitry configured to operate in response to the first supply voltage;
a second voltage supply terminal configured to receive a second supply voltage, which is greater than the first supply voltage; and
a dynamic random access memory (DRAM) array having a plurality of sense amplifiers, wherein the sense amplifiers are configured to operate in response to the second supply voltage;
a dynamic random access memory (DRAM) array having a plurality of bit lines, circuitry that precharges the bit lines to a voltage equal to half the second supply voltage when the DRAM array is not accessed, and a plurality of sense amplifiers coupled to the bit lines, wherein the second supply voltage is coupled to supply the sense amplifiers when the DRAM array is accessed.
2. The integrated circuit of claim 1 , wherein the DRAM array has 64 rows or less.
3. The integrated circuit of claim 1 , wherein the DRAM array includes a plurality of DRAM cells, each having a cell capacitor with a capacitance of 6 femto-Farads or less.
4. The integrated circuit of claim 1 , wherein the DRAM array includes a plurality of DRAM cells, each having a cell capacitor with a folded capacitor structure.
5. The integrated circuit of claim 1 , wherein the DRAM array includes a plurality of DRAM cells, each having a cell capacitor with a trench capacitor structure.
6. The integrated circuit of claim 1 , wherein the DRAM array includes a plurality of DRAM cells, each having a cell capacitor with a stacked capacitor structure.
7. The integrated circuit of claim 6 , wherein the stacked capacitor structure comprises a metal-insulator-metal (MIM) structure.
8. The integrated circuit of claim 1 , wherein the DRAM array has 700 columns or less.
9. The integrated circuit of claim 1 , further comprising a boosted voltage generator configured to generate the second supply voltage in response to the first supply voltage.
10. An integrated circuit comprising:
a first voltage supply terminal configured to receive a first supply voltage;
logic circuitry configured to operate in response to the first supply voltage wherein the logic circuitry includes logic transistors having a gate oxide with a first thickness;
a second voltage supply terminal configured to receive a second supply voltage, which is greater than the first supply voltage; and
a dynamic random access memory (DRAM) array having a plurality of sense amplifiers, wherein the sense amplifiers are configured to operate in response to the second supply voltage, wherein the DRAM array includes a plurality of DRAM cells, each having a cell capacitor with an oxide layer of a second thickness, wherein the second thickness is greater than the first thickness.
11. The integrated circuit of claim 10 , wherein the second thickness is about 26 Angstroms.
12. An integrated circuit comprising:
a first voltage supply terminal configured to receive a first supply voltage;
logic circuitry configured to operate in response to the first supply voltage wherein the logic circuitry includes logic transistors having a gate oxide with a first thickness;
a second voltage supply terminal configured to receive a second supply voltage, which is greater than the first supply voltage; and
a dynamic random access memory (DRAM) array having a plurality of sense amplifiers, wherein the sense amplifiers are configured to operate in response to the second supply voltage, and wherein each of the sense amplifiers includes a plurality of sense amplifier transistors having a gate oxide with a second thickness, wherein the second thickness is greater than the first thickness.
13. The integrated circuit of claim 12 , wherein the logic transistors have a first channel length and the sense amplifier transistors have a second channel length, wherein the second channel length is greater than the first channel length.
14. An integrated circuit comprising:
a first voltage supply terminal configured to receive a first supply voltage;
logic circuitry configured to operate in response to the first supply voltage wherein the logic circuitry includes logic transistors having a gate oxide with a first thickness;
a second voltage supply terminal configured to receive a second supply voltage, which is greater than the first supply voltage; and
a dynamic random access memory (DRAM) array having a plurality of sense amplifiers, wherein the sense amplifiers are configured to operate in response to the second supply voltage, and wherein each of the sense amplifiers includes a plurality of transistors having a gate oxide with a second thickness, wherein the second thickness is equal to the first thickness.
15. The integrated circuit of claim 14 , wherein the logic transistors have a first channel length and the sense amplifier transistors have a second channel length, wherein the second channel length is greater than the first channel length.
16. The integrated circuit of claim 14 , wherein the second supply voltage is at least about 20 percent greater than the first supply voltage.
17. The integrated circuit of claim 16 , wherein the second supply voltage is at least about twice the first supply voltage.
18. A method of operating a dynamic random access memory (DRAM) array having a plurality of bit lines and a plurality of sense amplifiers embedded on the same chip as a logic circuit, the method comprising:
operating the logic circuit in response to a first supply voltage; and
coupling the sense amplifiers to receive a second supply voltage when the DRAM array is being accessed, whereby the sense amplifiers are supplied from the second supply voltage, wherein the second supply voltage is greater than the first supply voltage; and
precharging the bit lines to a voltage equal to half the second supply voltage when the DRAM array is not being accessed.
19. The method of claim 18 , further comprising generating the second supply voltage in response to the first supply voltage.
20. A method of operating a dynamic random access memory (DRAM) array having a plurality of sense amplifiers embedded on the same chip as a logic circuit, the method comprising:
operating the logic circuit in response to a first supply voltage;
generating a second supply voltage in response to the first supply voltage, wherein the second supply voltage is at least about 20 percent greater than the first supply voltage; and
operating the sense amplifiers of the DRAM array in response to the second supply voltage.
21. A method of operating a dynamic random access memory (DRAM) array having a plurality of sense amplifiers embedded on the same chip as a logic circuit, the method comprising:
operating the logic circuit in response to a first supply voltage;
generating a second supply voltage in response to the first supply voltage, wherein the second supply voltage is at least about twice the first supply voltage; and
operating the sense amplifiers of the DRAM array in response to the second supply voltage.
22. A method of operating a dynamic random access memory (DRAM) array having a plurality of sense amplifiers embedded on the same chip as a logic circuit, the method comprising:
fabricating transistor and capacitor structures in the DRAM array with gate oxide having a first thickness; and
fabricating transistors in the logic circuit with gate oxide having a second thickness, wherein the first thickness is greater than the second thickness;
operating the logic circuit in response to a first supply voltage; and
operating the sense amplifiers of the DRAM array in response to a second supply voltage, which is greater than the first supply voltage.