Fatigue-free bipolar loop treatment to reduce imprint effect in piezoelectric device

Patent metadata

Field	Value
Publication number	US-11456330-B2
Application number	US-201916534330-A
Country	US
Kind code	B2
Filing date	Aug 7, 2019
Priority date	Aug 7, 2019
Publication date	Sep 27, 2022
Grant date	Sep 27, 2022

Abstract

In some embodiments, the present disclosure relates to a method for recovering degraded device performance of a piezoelectric device. The method includes operating the piezoelectric device in a performance mode by applying one or more voltage pulses to the piezoelectric device, and determining that a performance parameter of the piezoelectric device has a first value that has deviated from a reference value by more than a predetermined threshold value during a first time period. During a second time period, the method further includes applying a bipolar loop to the piezoelectric device, comprising positive and negative voltage biases. During a third time period, the method further includes operating the piezoelectric device in the performance mode, wherein the performance parameter has a second value. An absolute difference between the second value and the reference value is less than an absolute difference between the first value and the reference value.

First claim

What is claimed is:

1. A method for recovering degraded device performance of a piezoelectric device, the method comprising:
operating the piezoelectric device in a performance mode over a first time period by applying one or more voltage pulses greater than or equal to a first amplitude to the piezoelectric device;
determining during the first time period that a performance parameter of the piezoelectric device has a first value that has deviated from a reference value by more than a predetermined threshold value;
applying a bipolar loop to the piezoelectric device over a second time period comprising positive and negative voltage biases, the second time period being after the first time period; and
operating the piezoelectric device in the performance mode over a third time period after the second time period, wherein the performance parameter of the piezoelectric device has a second value during the third time period, and wherein an absolute difference between the second value and the reference value is less than an absolute difference between the first value and the reference value.

2. The method of claim 1 , wherein the performance parameter is a permittivity of the piezoelectric device.

3. The method of claim 1 , wherein the performance parameter corresponds to the first time period.

4. The method of claim 1 , wherein applying the bipolar loop comprises:
applying a first voltage bias to the piezoelectric device, wherein the first voltage bias has a second amplitude and a first polarity;
adjusting the first voltage bias to a second voltage bias, wherein the second voltage bias has the second amplitude and a second polarity opposite to the first polarity, wherein the second amplitude is less than the first amplitude; and
adjusting the second voltage bias to a third voltage bias that is between the first voltage bias and the second voltage bias.

5. The method of claim 4 , wherein the second amplitude is less than or equal to an electric coercive field voltage of the piezoelectric device, and wherein the first amplitude is greater than the electric coercive field voltage.

6. The method of claim 4 , wherein the third voltage bias is equal to zero.

7. A method for preventing degraded device performance of a piezoelectric device, the method comprising:
operating the piezoelectric device in a performance mode over a first time period by applying one or more voltage pulses greater than or equal to a first amplitude to the piezoelectric device, wherein the first amplitude is greater than an electric coercive field voltage of the piezoelectric device;
determining that a predetermined threshold value of the performance mode has been reached; and
performing a bipolar loop to the piezoelectric device over a second time period by:
applying a voltage bias signal across the piezoelectric device at a second amplitude at a first polarity;
adjusting the voltage bias signal across the piezoelectric device from the second amplitude to a third amplitude at a second polarity opposite to the first polarity, wherein the second amplitude is equal to the third amplitude, and wherein the second amplitude is less than or equal to the electric coercive field voltage of the piezoelectric device; and
adjusting the voltage bias signal across the piezoelectric device from the third amplitude to a fourth amplitude that is between the second amplitude and the third amplitude.

8. The method of claim 7 , wherein the predetermined threshold value corresponds to a predetermined time period, wherein the predetermined threshold value has been reached when the first time period equals the predetermined time period.

9. The method of claim 7 , wherein the predetermined threshold value corresponds to a predetermined number of pulses, wherein the predetermined threshold value has been reached when a total number of the one or more voltage pulses of the performance mode equals the predetermined number of pulses.

10. The method of claim 7 , wherein each pulse of the one or more voltage pulses has a same polarity.

11. The method of claim 7 ,
wherein before the first time period, a performance parameter of the piezoelectric device is equal to a first value;
wherein after the first time period and before the second time period, the performance parameter of the piezoelectric device is equal to a second value that has deviated from the first value by a first absolute difference; and
wherein after the second time period, the performance parameter of the piezoelectric device is equal to a third value that has deviated from the first value by a second absolute difference that is less than the first absolute difference.

12. The method of claim 7 , wherein the bipolar loop is performed a plurality of times.

13. The method of claim 7 , wherein the performance mode further comprises holding the voltage bias signal at zero for a third time period between each pulse of the one or more voltage pulses.

14. The method of claim 13 , wherein the first time period begins at a start of a first pulse of the one or more voltage pulses and ends at an end of a last pulse of the one or more voltage pulses, and wherein the second time period is after the first time period.

15. A system, the system comprising:
a piezoelectric device disposed on a semiconductor substrate, the piezoelectric device comprising a piezoelectric structure disposed between a first electrode and a second electrode;
bias circuitry electrically coupled to the first electrode and the second electrode, wherein the bias circuitry is configured to operate in a performance mode by applying a voltage bias across the piezoelectric structure;
measurement circuitry electrically coupled to the bias circuitry, wherein the measurement circuitry is configured to detect that a predetermined threshold value has been reached during the performance mode; and
wherein the bias circuitry is configured to perform a recovery operation upon detection of the predetermined threshold value by:
increasing the voltage bias from a start value to a first magnitude at a first polarity, decreasing the voltage bias from the first magnitude at the first polarity to the first magnitude at a second polarity opposite to the first polarity, and increasing the voltage bias from the first magnitude at the second polarity to an end value equal to the start value.

16. The system of claim 15 , wherein the measurement circuitry is electrically coupled to the piezoelectric device, wherein the measurement circuitry is configured to measure a performance parameter of the piezoelectric device, wherein the measurement circuitry is configured to detect when the performance parameter has reached the predetermined threshold value.

17. The system of claim 15 , wherein the measurement circuitry is configured to count a number of voltage bias pulses applied by the bias circuitry in the performance mode, and wherein the predetermined threshold value is a predetermined number of voltage bias pulses counted by the measurement circuitry.

18. The system of claim 15 , wherein the measurement circuitry is configured to measure a total time of that the bias circuitry is in the performance mode, and wherein the predetermined threshold value is a predetermined time measured by the measurement circuitry.

19. The system of claim 15 , wherein the first magnitude is less than or equal to an electric coercive field voltage of the piezoelectric structure.

20. The system of claim 15 , wherein the measurement circuitry is configured to measure a parameter value of th

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Shih Chi-Yuan
• Huang Shih-Fen
• Lin You-Ru
• Liao Yan-Jie

Classifications

• H02N2/067 Primary

  generating drive pulses · CPC title

• H02N2/04

  Constructional details · CPC title

• H01L41/314

  Electricity · mapped topic

• H01L27/20 Primary

  Electricity · mapped topic

• H01L41/0986

  Electricity · mapped topic