A TFT reliability test method based on characteristic curve

Abstract

The application discloses a TFT reliability test method based on characteristic curves, comprising the steps of: obtaining characteristic curves of TFT transistors prepared by using same process parameters under different waveband lights, and determining target waveband light causing characteristic drift of the TFT transistors according to differences between the characteristic curves; obtaining characteristic curves of TFT transistors prepared by using different process parameters under the target waveband light, and determining target process parameters capable of improving the characteristic drift of the TFT transistors according to differences between the characteristic curves. The TFT reliability test method can determine the target waveband light causing the characteristic drift of the TFT transistors and the target process parameters capable of improving the characteristic drift of the TFT transistors.

Description

Technical Field

[0001] This invention relates to TFT display technology, and more particularly to a TFT reliability testing method based on characteristic curves. Background Technology

[0002] As existing TFT display panels are used for a longer period of time, their display quality gradually deteriorates, eventually leading to display abnormalities. This is because TFT transistors have poor photostability. When exposed to light for extended periods, TFT transistors are prone to aging, which causes characteristic drift and a decrease in the switching ratio. Consequently, the pixels of the TFT display panel cannot turn on and off in a timely manner according to the signal voltage requirements, ultimately resulting in display abnormalities.

[0003] Therefore, determining the target wavelength of light that causes the drift of the TFT transistor characteristics, and the target process parameters that can improve the drift of the TFT transistor characteristics, is of great significance for improving the reliability of TFT display panels. Summary of the Invention

[0004] To address the shortcomings of the prior art, this invention provides a TFT reliability testing method based on characteristic curves, which can determine the target wavelength light that causes the TFT transistor characteristic drift, as well as the target process parameters that can improve the TFT transistor characteristic drift.

[0005] The technical problem to be solved by the present invention is achieved through the following technical solution: A TFT reliability testing method based on characteristic curves includes the following steps: Step 100: Obtain the characteristic curves of TFT transistors prepared using the same process parameters under different wavelengths of light, and determine the target wavelength of light that causes the characteristic drift of the TFT transistor based on the differences between the characteristic curves. Step 200: Obtain the characteristic curves of TFT transistors prepared with different process parameters under the target wavelength light, and determine the target process parameters that can improve the characteristic drift of the TFT transistor based on the differences between the characteristic curves.

[0006] This invention has the following beneficial effects: This patent compares the characteristic curves of TFT transistors prepared with the same process parameters under different wavelengths of light to determine the target wavelength of light that causes the characteristic drift of the TFT transistor. Then, it compares the characteristic curves of TFT transistors prepared with different process parameters under the target wavelength of light to determine the target process parameters that can improve the characteristic drift of the TFT transistor. After determining the target process parameters, the parameter values ​​of the target process parameters can be adjusted during the preparation of the TFT transistor to avoid the problem of aging of the TFT transistor due to light exposure after long-term use, which in turn causes characteristic drift. This is of great significance for improving the reliability of TFT display panels. Attached Figure Description

[0007] Figure 1 A flowchart illustrating the steps of the TFT reliability testing method provided by this invention.

[0008] Figure 2 for Figure 1 The flowchart of step 100 in the TFT reliability test method shown is shown.

[0009] Figure 3 for Figure 2 The flowchart of step 110 in the TFT reliability test method shown is shown.

[0010] Figure 4 for Figure 1 The flowchart shows the steps of step 200 in the TFT reliability test method.

[0011] Figure 5 for Figure 4 The flowchart of step 230 in the TFT reliability test method shown is shown. Implementation

[0012] The present invention will now be described in detail with reference to the accompanying drawings and embodiments, examples of which are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0013] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0014] Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of that feature. In the description of this invention, "multiple" means two or more, unless otherwise explicitly specified.

[0015] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," and "setting," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. Example

[0016] like Figure 1 As shown, a TFT reliability testing method based on characteristic curves includes the following steps: Step 100: Obtain the characteristic curves of TFT transistors prepared using the same process parameters under different wavelengths of light, and determine the target wavelength of light that causes the characteristic drift of the TFT transistor based on the differences between the characteristic curves.

[0017] In step 100, the TFT transistors monitored under different wavelengths of light can be the same TFT transistor, or different TFT transistors prepared using the same process parameters, such as multiple TFT transistors produced in the same batch.

[0018] Specifically, such as Figure 2 As shown, in step 100, the characteristic curves of TFT transistors fabricated using the same process parameters under different wavelengths of light are obtained, and the target wavelength of light causing the characteristic drift of the TFT transistor is determined based on the differences between the characteristic curves as follows: Step 110: Irradiate the TFT transistor with a reference light source and a test light source respectively, and monitor the characteristics of the TFT transistor to obtain the first characteristic curve and the second characteristic curve of the TFT transistor under the reference light source and the test light source respectively, wherein the test light source lacks a certain wavelength of light compared with the reference light source.

[0019] In step 110, the reference light source is preferably a full-band light source, whose wavelength range covers major bands such as infrared, visible, and ultraviolet light. The test light source can be based on the reference light source by removing one of the ultraviolet, blue, green, red, and infrared light bands to compare which band of light the test light source lacks, so as to determine whether the missing band of light in the test light source is the target band of light that causes the characteristic drift of the TFT transistor.

[0020] Specifically, such as Figure 3 As shown, in step 110, the steps for obtaining the first characteristic curve and the second characteristic curve of the TFT transistor under the reference light source and the test light source are as follows: Step 111: Drill holes at the positions corresponding to the gate, source and drain of the TFT transistor to expose the gate, source and drain of the TFT transistor respectively.

[0021] In step 111, the TFT transistor has multiple functional layers stacked together, generally including a gate metal layer, a gate insulating layer, a semiconductor layer, a source / drain metal layer, a source / drain insulating layer, a pixel electrode layer, and a planarization layer. Because the TFT transistor has multiple functional layers stacked together, its gate, source, and drain are not directly exposed. Therefore, it is necessary to perform a drilling process on the TFT transistor to expose its gate, source, and drain respectively for easy monitoring.

[0022] During drilling, a laser can be used, but is not limited to, to burn off three positions on the TFT transistor corresponding to its gate, source, and drain, respectively, in order to remove the functional film layer covering the gate, source, and drain.

[0023] Step 112: Inject electrode material into the holes corresponding to the gate, source and drain, respectively, so as to lead the gate, source and drain to the surface of the TFT transistor through the electrode material in the holes.

[0024] In step 112, the electrode material may be, but is not limited to, silver paste. The silver paste is injected into the holes corresponding to the gate, source, and drain, and then the silver paste in the holes is allowed to solidify. This allows the gate, source, and drain to be led out from the bottom of the holes to the top of the holes through the silver paste in the corresponding holes, and finally to the surface of the TFT transistor.

[0025] Step 113: Connect the TEG testing equipment to the electrode materials corresponding to the gate, source, and drain, respectively. Irradiate the TFT transistor with the reference light source and the test light source, respectively, and monitor and obtain the first characteristic curve and the second characteristic curve of the TFT transistor through the TEG testing equipment.

[0026] In step 113, the TEG (Test Element Group) testing equipment is a conventional testing equipment used in the art to test the TFT transistor in order to obtain various electrical parameters of the TFT transistor, and will not be described in detail here.

[0027] During monitoring, the three probes of the TEG testing equipment are connected to the gate, source, and drain of the TFT transistor through the electrode material in the corresponding holes, respectively. The voltage value of the source is used as a parameter to obtain the relationship curve between the voltage value of the gate and the current value of the drain as the first characteristic curve and the second characteristic curve.

[0028] Preferably, the TEG testing equipment monitors and obtains the first and second characteristic curves of the TFT transistor, sequentially outputs positive and negative bias voltages to the TFT transistor for a predetermined duration to simulate the state of the TFT transistor after long-term operation, and then acquires the first and second characteristic curves of the TFT transistor under the positive and negative bias voltages at certain time intervals. The time interval for acquiring the first and second characteristic curves can be 0s, 400s, 1000s, 2000s, and 3600s after outputting the positive and negative bias voltages, etc., to observe the characteristic drift of the TFT transistor under the reference light source using the positive and negative bias voltages at different operating times, and the characteristic drift of the TFT transistor under the test light source using the positive and negative bias voltages at different operating times.

[0029] Step 120: Compare the first characteristic curve with the second characteristic curve to determine whether there are characteristic differences of the TFT transistor under the control light source and the test light source.

[0030] In step 120, the characteristic states of the TFT transistor under the reference light source and the test light source are in three cases: the first case is that the TFT transistor does not experience characteristic drift under either the reference light source or the test light source; the second case is that the TFT transistor experiences characteristic drift under both the reference light source and the test light source; and the third case is that the TFT transistor experiences characteristic drift under the reference light source but not under the test light source. For the first two cases, the second characteristic curve is the same as or similar to the third characteristic curve, indicating that the TFT transistor does not have characteristic differences under the reference light source and the test light source. For the last case, the second characteristic curve is different from the third characteristic curve, indicating that the TFT transistor has characteristic differences under the reference light source and the test light source.

[0031] Because there are differences in optical parameters between the reference light source and the test light source, these differences can cause errors in the characteristic curves. Even if both the reference light source and the test light source cause characteristic drift in the TFT transistor, the first characteristic curve and the second characteristic curve cannot be exactly the same. Therefore, a first error range can be set. When the difference between the first characteristic curve and the second characteristic curve is within the first error range, it is determined that the TFT transistor has no characteristic difference under the reference light source and the test light source. When the difference between the first characteristic curve and the second characteristic curve is outside the first error range, it is determined that the TFT transistor has characteristic differences under the reference light source and the test light source.

[0032] Step 130: If the TFT transistor exhibits characteristic differences under the control light source and the test light source, the wavelength of light missing from the test light source is determined as the target wavelength of light. If the TFT transistor does not exhibit characteristic differences under the control light source and the test light source, another test light source is used and steps 110 to 130 are repeated, wherein the wavelength of light missing from different test light sources is different.

[0033] In step 130, if the TFT transistor does not show any characteristic difference under the control light source and the test light source, it indicates that the wavelength of light missing from the test light source is not the target wavelength of light that causes the TFT transistor to drift. Therefore, it is necessary to replace the test light source and test again to further determine the wavelength of light of the target wavelength.

[0034] Step 200: Obtain the characteristic curves of TFT transistors prepared with different process parameters under the target wavelength light, and determine the target process parameters that can improve the characteristic drift of the TFT transistor based on the differences between the characteristic curves.

[0035] In step 200, the fabrication process of the TFT transistor includes multiple process parameters, such as the film thickness, film formation rate, film formation temperature, film formation humidity, mixing ratio of film formation gases, etching rate, etching temperature, and mixing ratio of etching solution for each functional layer. Each process parameter has a corresponding value, and the values ​​of all process parameters together constitute the process parameters of the TFT transistor. Different process parameters refer to different process parameters used in the fabrication of different TFT transistors, where at least one process parameter has a different value.

[0036] Specifically, such as Figure 4 As shown, in step 200, the characteristic curves of TFT transistors fabricated using different process parameters under the target wavelength light are obtained, and the target process parameters that can improve the characteristic drift of the TFT transistor are determined based on the differences between the characteristic curves as follows: Step 210: Adjust the parameter value of one of the process parameters of the TFT transistor.

[0037] In step 210, the process parameters of the TFT transistor used in step 100 are used as the original parameters, and the value of one of the process parameters is adjusted to form a new process parameter.

[0038] Step 220: Fabricate the TFT transistor using the adjusted process parameters.

[0039] Step 230: Obtain the third characteristic curve of the newly prepared TFT transistor under the reference light source.

[0040] In step 230, the reference light source includes the target wavelength light. By using the reference light source to obtain the third characteristic curve of the newly prepared TFT transistor, it is convenient to compare the third characteristic curve with the first characteristic curve in step 100.

[0041] Specifically, such as Figure 5 As shown, in step 230, the steps for obtaining the third characteristic curve of the newly prepared TFT transistor under the reference light source are as follows: Step 231: Drill holes at the positions corresponding to the gate, source, and drain of the newly prepared TFT transistor to expose the gate, source, and drain of the newly prepared TFT transistor.

[0042] In step 231, since the newly fabricated TFT transistor has multiple functional film layers stacked on top of each other, the gate, source, and drain of the newly fabricated TFT transistor are not directly exposed. Therefore, it is necessary to perform a hole-drilling process on the newly fabricated TFT transistor to expose the gate, source, and drain of the newly fabricated TFT transistor respectively, so as to facilitate monitoring.

[0043] During drilling, a laser can be used, but is not limited to, to burn off the three positions on the newly prepared TFT transistor corresponding to its gate, source, and drain, respectively, in order to remove the functional film layer covering the gate, source, and drain.

[0044] Step 232: Inject electrode material into the holes corresponding to the gate, source and drain, respectively, so as to lead the gate, source and drain to the surface of the newly prepared TFT transistor through the electrode material in the holes.

[0045] In step 232, the electrode material may be, but is not limited to, silver paste. The silver paste is injected into the holes corresponding to the gate, source, and drain, and then the silver paste in the holes is allowed to solidify. The gate, source, and drain are then led out from the bottom of the holes to the top of the holes through the silver paste in the corresponding holes, until they reach the surface of the newly prepared TFT transistor.

[0046] Step 233: Connect the TEG testing equipment to the electrode materials corresponding to the gate, source, and drain, respectively. Irradiate the newly prepared TFT transistor with the reference light source and obtain the third characteristic curve of the newly prepared TFT transistor by monitoring with the TEG testing equipment.

[0047] In step 233, the three probes of the TEG testing equipment are connected to the gate, source, and drain of the newly prepared TFT transistor through the electrode material in the corresponding holes, respectively. The voltage value of the source is used as a parameter to obtain the relationship curve between the voltage value of the gate and the current value of the drain as the third characteristic curve.

[0048] Preferably, when the TEG testing equipment monitors and obtains the third characteristic curve of the newly prepared TFT transistor, it sequentially outputs a positive bias voltage and a negative bias voltage to the newly prepared TFT transistor for a predetermined duration to simulate the state of the newly prepared TFT transistor after long-term operation. Then, it acquires the third characteristic curve of the newly prepared TFT transistor under the positive bias voltage and the negative bias voltage at certain time intervals. The time interval for acquiring the third characteristic curve can be 0s, 400s, 1000s, 2000s, and 3600s after outputting the positive bias voltage and the negative bias voltage, etc., to observe the characteristic drift of the newly prepared TFT transistor under the reference light source when using the positive bias voltage and the negative bias voltage at different operating times.

[0049] Step 240: Compare the third characteristic curve with the first characteristic curve to determine whether the characteristic drift of the newly prepared TFT transistor has been improved.

[0050] In step 240, since different TFT transistors use different process parameters, the difference in process parameters will cause errors in the characteristic curves. Even if the characteristic drift of the TFT transistor is not improved, the third characteristic curve and the first characteristic curve cannot be exactly the same. Therefore, a second error range can be set. When the difference between the third characteristic curve and the first characteristic curve is within the second error range, it is determined that the characteristic drift of the TFT transistor has not been improved. When the difference between the third characteristic curve and the first characteristic curve is outside the second error range, it is determined that the characteristic drift of the TFT transistor has been improved.

[0051] Step 250: If the characteristic drift of the newly prepared TFT transistor is improved, the adjusted process parameters are determined as the target process parameters. If the characteristic drift of the newly prepared TFT transistor is not improved, steps 210 to 250 are repeated, wherein the adjusted process parameters are different each time.

[0052] If the characteristic drift of the newly prepared TFT transistor is improved in step 250, it indicates that the adjusted process parameters cannot improve the characteristic drift of the TFT transistor.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention and not to limit them. Although the embodiments of the present invention have been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the embodiments of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A TFT reliability testing method based on characteristic curves, characterized in that, Includes the following steps: Step 100: Obtain the characteristic curves of TFT transistors prepared using the same process parameters under different wavelengths of light, and determine the target wavelength of light that causes the characteristic drift of the TFT transistor based on the differences between the characteristic curves. Step 200: Obtain the characteristic curves of TFT transistors prepared with different process parameters under the target wavelength light, and determine the target process parameters that can improve the characteristic drift of the TFT transistor based on the differences between the characteristic curves. In step 100, the following steps are taken to obtain the characteristic curves of TFT transistors fabricated using the same process parameters under different wavelengths of light, and to determine the target wavelength of light that causes the characteristic drift of the TFT transistor based on the differences between the characteristic curves: Step 110: Irradiate the TFT transistor with a reference light source and a test light source respectively, and monitor the characteristics of the TFT transistor to obtain the first characteristic curve and the second characteristic curve of the TFT transistor under the reference light source and the test light source respectively, wherein the test light source lacks a certain wavelength of light compared with the reference light source; Step 120: Compare the first characteristic curve with the second characteristic curve to determine whether there are characteristic differences of the TFT transistor under the control light source and the test light source respectively; Step 130: If the TFT transistor has different characteristics under the reference light source and the test light source respectively, then the wavelength light missing by the test light source is determined as the target wavelength light. If the TFT transistor does not have different characteristics under the reference light source and the test light source respectively, then another test light source is replaced and steps 110 to 130 are repeated, wherein the wavelength light missing by different test light sources is different. In step 200, the characteristic curves of TFT transistors fabricated using different process parameters under the target wavelength light are obtained, and the target process parameters that can improve the characteristic drift of the TFT transistor are determined based on the differences between the characteristic curves as follows: Step 210: Adjust the parameter value of one of the process parameters of the TFT transistor; Step 220: Fabricate the TFT transistor using the adjusted process parameters: Step 230: Obtain the third characteristic curve of the newly prepared TFT transistor under the reference light source; Step 240: Compare the third characteristic curve with the first characteristic curve to determine whether the characteristic drift of the newly prepared TFT transistor has been improved; Step 250: If the characteristic drift of the newly prepared TFT transistor is improved, the adjusted process parameters are determined as the target process parameters. If the characteristic drift of the newly prepared TFT transistor is not improved, steps 210 to 250 are repeated, wherein the adjusted process parameters are different each time.

2. The TFT reliability testing method based on characteristic curves according to claim 1, characterized in that, In step 110, the steps for obtaining the first characteristic curve and the second characteristic curve of the TFT transistor under the reference light source and the test light source are as follows: Step 111: Drill holes at the positions corresponding to the gate, source, and drain of the TFT transistor to expose the gate, source, and drain of the TFT transistor respectively. Step 112: Electrode material is injected into the holes corresponding to the gate, source, and drain, respectively, so that the gate, source, and drain are respectively led out to the surface of the TFT transistor through the electrode material in the holes; Step 113: Connect the TEG testing equipment to the electrode materials corresponding to the gate, source, and drain, respectively. Irradiate the TFT transistor with the reference light source and the test light source, respectively, and monitor and obtain the first characteristic curve and the second characteristic curve of the TFT transistor through the TEG testing equipment.

3. The TFT reliability testing method based on characteristic curves according to claim 2, characterized in that, In step 113, while monitoring and obtaining the first characteristic curve and the second characteristic curve of the TFT transistor, the TEG testing equipment sequentially outputs a positive bias voltage and a negative bias voltage to the TFT transistor for a predetermined duration.

4. The TFT reliability testing method based on characteristic curves according to claim 1, characterized in that, In step 120, a first error range is set. When the difference between the first characteristic curve and the second characteristic curve is within the first error range, it is determined that the TFT transistor has no characteristic difference under the reference light source and the test light source. When the difference between the first characteristic curve and the second characteristic curve is outside the first error range, it is determined that the TFT transistor has characteristic differences under the reference light source and the test light source.

5. The TFT reliability testing method based on characteristic curves according to claim 1, characterized in that, The reference light source is a full-band light source.

6. The TFT reliability testing method based on characteristic curves according to claim 1, characterized in that, In step 230, the step of obtaining the third characteristic curve of the newly prepared TFT transistor under the reference light source is as follows: Step 231: Drill holes at the positions corresponding to the gate, source, and drain of the newly fabricated TFT transistor to expose the gate, source, and drain of the newly fabricated TFT transistor. Step 232: Electrode material is injected into the holes corresponding to the gate, source, and drain, respectively, so that the gate, source, and drain are respectively led out to the surface of the newly fabricated TFT transistor through the electrode material in the holes; Step 233: Connect the TEG testing equipment to the electrode materials corresponding to the gate, source, and drain, respectively. Irradiate the newly prepared TFT transistor with the reference light source and obtain the third characteristic curve of the newly prepared TFT transistor by monitoring with the TEG testing equipment.

7. The TFT reliability testing method based on characteristic curves according to claim 6, characterized in that, When the TEG testing equipment monitors and obtains the third characteristic curve of the newly prepared TFT transistor, it sequentially outputs positive bias voltage and negative bias voltage to the newly prepared TFT transistor for a predetermined duration.

8. The TFT reliability testing method based on characteristic curves according to claim 1, characterized in that, In step 240, a second error range is set. When the difference between the third characteristic curve and the first characteristic curve is within the second error range, it is determined that the characteristic drift of the TFT transistor has not been improved. When the difference between the third characteristic curve and the first characteristic curve is outside the second error range, it is determined that the characteristic drift of the TFT transistor has been improved.

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