Pseudo-inverter circuit on SeOI

• US 8,654,602 B2
• Filed: 06/13/2012
• Issued: 02/18/2014
• Est. Priority Date: 04/02/2010
• Status: Active Grant

• Current Assignee: Soitec S.A.
• Original Assignee: Soitec S.A.
• Inventors: Mazure, Carlos, Ferrant, Richard, Nguyen, Bich-Yen
• Primary Examiner(s): DINH, SON T
• Application Number:
  US13/495,632
• Publication Number:
  US 20120250444A1
• Time in Patent Office: 615 Days
• Field of Search: 365/230.06, 365/189.08
• US Class Current: 365/230.08
• CPC Class Codes: G11C 11/4085 Word line control circuits, e.g. word line drivers, - boosters, - pull-up, - pull-down, - precharge
• CPC Class Codes: G11C 2211/4016 Memory devices with silicon-on-insulator cells
• CPC Class Codes: G11C 8/08 Word line control circuits, e.g. drivers, boosters, pull-up circuits, pull-down circuits, precharging circuits, for word lines

Abstract

A circuit made on a semiconductor-on-insulator substrate. The circuit includes a first transistor having a first channel, a second transistor having a second channel, with the transistors provided in serial association between first and second terminals for applying a power supply potential, each of the transistors comprising a drain region and a source region in the thin layer, a channel extending between the source region and the drain region, and a front control gate located above the channel. Each transistor has a back control gate formed in the base substrate below the channel of the transistor and capable of being biased in order to modulate the threshold voltage of the transistor. At least one of the transistors is configured for operating in a depletion mode under the action of a back gate signal which will sufficiently modulate its threshold voltage.

Claims

1. A circuit made on a semiconductor-on-insulator substrate comprising a thin layer of semiconducting material separated from a base substrate by an insulating layer that extends through the entire substrate;

the circuit comprising;

a first transistor having a first channel, a second transistor having a second channel, with the transistors provided in serial association between first and second terminals for applying a power supply potential, each of the transistors comprising a drain region and a source region in the thin layer, a channel extending between the source region and the drain region, and a front control gate located above the channel,

wherein each transistor has a back control gate formed in the base substrate below the channel of the transistor and capable of being biased in order to modulate the threshold voltage of the transistor, and

wherein at least one of the transistors is configured for operating in a depletion mode under the action of a back gate signal which will sufficiently modulate its threshold voltage.

2. The circuit according to claim 1, wherein each transistor has a separate back control gate formed in the base substrate that also underlies the insulating layer.

3. The circuit according to claim 1, wherein the back control gates are biased by a same back gate signal.

4. The circuit according to claim 3, wherein the first terminal for application of a power supply potential is biased by the complementary signal of the back gate signal, whereas the second terminal for application of a power supply potential is biased at an OFF state.

5. The circuit according to claim 4, wherein the second transistor is configured in order to operate in a depletion mode when the back gate signal is in an ON state.

6. The circuit according to claim 3, wherein the second terminal for application of a power supply potential is biased by the complementary signal of the back gate signal, while the first terminal for application of a power supply potential is biased to an ON state.

7. The circuit according to claim 6, wherein the first transistor is configured in order to operate in a depletion mode when the back gate signal is in an OFF state.

8. The circuit according to claim 1, wherein the first terminal for application of a power supply potential is biased at an ON state, whereas the second terminal for application of a power supply potential is biased at an OFF state.

9. The circuit according to claim 1, wherein the first and second transistors each have a front control gate and which further comprises an input node connected to the front control gate of each transistor and an output node connected to a middle point of the serial association of the transistors.

10. The circuit according to claim 1, wherein the first transistor is a PFET transistor and wherein the second transistor is a NFET transistor.

11. The circuit according to claim 1, wherein the transistors are fully depleted.

12. A wordline driver circuit comprising at least one pair of circuits according to claim 1 laid out in parallel, each circuit of the pair being intended to receive an input signal from a row address decoder and providing at the output a signal intended to be used as a local wordline for a plurality of memory cells laid out as a row.

13. A memory incorporating a wordline driver circuit according to claim 12.

14. A method for controlling a driver circuit according to claim 12, wherein:

in the active mode, the signal for biasing the back gates of the first circuit of a pair of circuits is complementary of the signal for biasing the back gates of the second circuit of the pair of circuits; and

in the inactive mode, the first terminal for application of a power supply potential and the signals for biasing the back gates of each of the circuits of the pair are in the OFF state.