REDUCING NOISE IN SEMICONDUCTOR DEVICES

• US 20090067251A1
• Filed: 09/11/2007
• Published: 03/12/2009
• Est. Priority Date: 09/11/2007
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Hoei, Jung Sheng, Roohparvar, Frankie F., Sarin, Vishal
• Granted Patent: US 8,085,596 B2
• Time in Patent Office: Days
• US Class Current: 365/185.190
• CPC Class Codes: G11C 11/5642 Sensing or reading circuits; Data output circuits
• CPC Class Codes: G11C 16/26 Sensing or reading circuits; Data output circuits
• CPC Class Codes: G11C 16/3418 Disturbance prevention or evaluation; Refreshing of disturbed memory data

Abstract

The present disclosure includes methods, devices, modules, and systems for reducing noise in semiconductor devices. One method embodiment includes applying a reset voltage to a control gate of a semiconductor device for a period of time. The method further includes sensing the state of the semiconductor device after applying the reset voltage.

Claims

1. A method for reducing noise in a semiconductor device, comprising:

applying a reset voltage to a control gate of the semiconductor device for a period of time; and

sensing a state of the semiconductor device after applying the reset voltage.

2. The method of claim 1, wherein the method includes applying the reset voltage for a period of time sufficiently long to allow for charge detrapping in a dielectric interface of the semiconductor device.

3. The method of claim 1, wherein the method includes applying a reset voltage that is equal to or less than a sensing voltage used to sense a lowermost state of the semiconductor device.

4. The method of claim 1, wherein the method includes applying a voltage ramp to a control gate of the semiconductor device for an amount of time that is substantially less than an amount of time associated with RTS due to charge trapping and detrapping in a dielectric interface in order to sense a state of the semiconductor device.

5. The method of claim 4, wherein the method includes starting the voltage ramp at a voltage low enough to initiate transition of the semiconductor device from accumulation to inversion when the semiconductor device is programmed to a lowermost state.

6. The method of claim 4, wherein the method includes sensing a state of the semiconductor device according to a voltage level of the voltage ramp when a drain current for the at least one semiconductor device reaches a particular reference current for the sensed state.

7. The method of claim 6, wherein the method includes sensing the state of the semiconductor device by reading the voltage level of the ramp as an analog value.

8. The method of claim 6, wherein the method includes sensing the state of the semiconductor device by reading the voltage level of the ramp using an analog to digital converter.

9. The method of claim 1, wherein sensing a state of the semiconductor device includes:

applying a series of discrete sensing voltages; and

applying the reset voltage before applying each of the series of discrete sensing voltages.

22. The device of claim 15, wherein the control circuitry is operable to read the sensing voltage ramp by using an analog to digital converter.

10. A method for reducing noise in a semiconductor device, comprising:

exposing the semiconductor device to a field such that the semiconductor device is in a state of accumulation to facilitate detrapping of dielectric interface traps;

transitioning the semiconductor device from a state of accumulation to inversion in a period of time substantially less than a period of time associated with 1/f noise; and

sensing a state of the semiconductor device.

11. The method of claim 10, wherein the method includes sensing the semiconductor device before significant charge trapping and detrapping can occur in the dielectric interface of the semiconductor device.

12. The method of claim 10, wherein the method includes:

sensing the state of the semiconductor device using a voltage ramp;

using the voltage ramp to induce the semiconductor device from accumulation to inversion; and

starting the voltage ramp at a voltage below the threshold voltage (Vt) of the lowermost state of the semiconductor device.

13. The method of claim 10, wherein the method includes:

sensing a state of the semiconductor device by applying discrete sensing voltages; and

exposing the semiconductor device to a field such that the semiconductor device is in a state of accumulation before applying each discrete sensing voltage.

14. The method of claim 13, wherein the method includes sensing a state of the semiconductor device by:

applying a first sensing voltage that is less than a second sensing voltage used to sense a higher state than the first sensing voltage, and is greater than a third sensing voltage used to sense a lowermost state;

applying the second sensing voltage after the first sensing voltage when the first sensing voltage does not cause the semiconductor device to conduct; and

applying the third sensing voltage after the first sensing voltage when the first sensing voltage causes the semiconductor device to conduct.

15. A semiconductor device comprising:

an array of memory cells arranged in rows and columns, wherein the cells arranged in at least one of the rows are coupled by a select line and wherein the cells arranged in at least one of the columns are coupled by a sense line; and

control circuitry coupled to the array, wherein the control circuitry is operable to;

apply a reset voltage to a control gate of at least one selected memory cell for a time prior to sensing a state of the at least one selected memory cell; and

apply a sensing voltage ramp to the control gate of the at least one selected memory cell.

16. The device of claim 15, wherein the time is sufficiently long to allow for charge detrapping in a dielectric interface of the at least one selected memory cell such that the at least one selected memory cell is in a state of accumulation.

17. The device of claim 15, wherein the particular reset voltage is sufficient to allow for charge detrapping in a dielectric interface of the at least one selected memory cell.

18. The device of claim 15, wherein the control circuitry is operable to apply a reset voltage that is equal to or less than a sensing voltage for a lowermost state of the at least one selected memory cell.

19. The device of claim 15, wherein the control circuitry is operable to apply a sensing voltage ramp to induce the at least one selected memory cell from accumulation to inversion.

20. The device of claim 15, wherein the control circuitry is operable to apply the sensing voltage ramp from a start voltage to a stop voltage, and wherein the start voltage is greater than or equal to the reset voltage, and the stop voltage is equal to or greater than a sensing voltage used to sense an uppermost state of the at least one selected memory cell.

21. The device of claim 15, wherein the control circuitry is operable to sense the state of the at least one selected memory cell according to a voltage of the sensing voltage ramp when a drain current reaches a particular reference current.

23. A semiconductor device comprising:

an array of memory cells arranged in rows and columns, wherein the cells arranged in at least one of the rows are coupled by a select line and wherein the cells arranged in at least one of the columns are coupled by a sense line; and

control circuitry coupled to the array, wherein the control circuitry is operable to;

apply a reset voltage to a control gate of at least one selected memory cell for a time prior to applying each of a number of discrete sensing voltages to the control gate to sense the state of the at least one selected memory cell; and

apply a first discrete sensing voltage, which is less than a second discrete sensing voltage used to sense a higher state than the first discrete sensing voltage, and greater than a third discrete sensing voltage used to sense a lowermost state;

apply the second discrete sensing voltage after the first discrete sensing voltage; and

apply the third discrete sensing voltage after the first discrete sensing voltage.

24. The device of claim 23, wherein the control circuitry is operable to apply the reset voltage before applying each discrete sensing voltage.

25. The device of claim 23, wherein the control circuitry is operable to apply a reset voltage that is lower than a discrete sensing voltage used to sense a lowermost state of the at least one selected memory cell.