Defect testing system of carbon nanotube thin film transistor and testing method thereof

Abstract

The application provides a defect testing method for a carbon nanotube thin film transistor, characterized by comprising the following steps: generating a light beam by using a light-emitting light source module; monitoring the wavelength and intensity of the light beam emitted by the light-emitting light source module in real time by using a monitoring feedback module, and feeding back to the light-emitting light source module; transmitting the light beam emitted by the light-emitting light source module to an electrical measurement module through a light splitting optical fiber, irradiating the carbon nanotube thin film transistor, and recording the corresponding electrical test results of the first stage, wherein the electrical test results of the first stage include a plurality of groups of electrical test results corresponding to different wave bands of the light beam emitted by the light-emitting light source module; and inputting the electrical test results corresponding to a plurality of stages into a front-end data converter to integrate into a defect characterization database.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device defect engineering, and specifically to a defect testing system and method for carbon nanotube thin-film transistors. Background Technology

[0002] Methods for characterizing defects in carbon nanotube thin-film transistors (CTPTs) are often limited by the device structure, resulting in inaccurate defect measurements at high frequencies. Specifically, the number of excited charge carriers in the device is insufficient to match the changes at higher frequencies, leading to generally inaccurate defect measurements at high frequencies. Furthermore, for ultrathin carbon nanotube CTPTs, various defect responses can couple during testing, affecting the test results for different defects and introducing errors into the experiment. Currently, optically assisted electrical testing methods are commonly used to address these issues.

[0003] However, the traditional fixed photocurrent defect characterization method requires multiple adjustments to the light source current during the test to ensure that the same current value is measured each time. This method is cumbersome to operate. Furthermore, since the number of tests is limited each time, it also places high demands on the control of the test equipment and the accuracy of the test to ensure the accuracy of the test data. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a defect testing system and method for carbon nanotube thin-film transistors, thereby improving the accuracy of defect testing for carbon nanotube thin-film transistors.

[0005] A first aspect of the present invention provides a method for defect testing of carbon nanotube thin-film transistors, characterized in that it includes:

[0006] A light beam is generated using a light-emitting light source module;

[0007] The wavelength and intensity of the light beam emitted by the light source module are monitored in real time using the monitoring feedback module and fed back to the light source module.

[0008] The light beam emitted by the light source module is transmitted to the electrical measurement module via a split optical fiber, irradiates the carbon nanotube thin film transistor, and records the electrical test results corresponding to the first stage. The electrical test results corresponding to the first stage include multiple sets of electrical test results corresponding to different wavelengths of the light beam emitted by the light source module.

[0009] The electrical test results corresponding to multiple stages are input into the front-end data converter and integrated into a defect characterization database. After the first stage measurement is completed in the electrical measurement module, the light source power of the light source module is adjusted according to the wavelength and intensity of the light beam fed back by the monitoring feedback module to achieve cyclic measurement. The obtained electrical measurement results are then updated to the defect characterization database.

[0010] By comparing and analyzing the electrical measurement results in the aforementioned defect characterization database, the target defect characterization results are determined.

[0011] According to an embodiment of the present invention, a light beam is generated using a light-emitting light source module, comprising:

[0012] The first program is run with the minimum light source power to enable the scanning monochromator to adjust the continuous spectrum generated by the light source in order to achieve the emission of light of a specified wavelength;

[0013] The second program is run to control the on / off state and duration of the light beam transmitted by the scanning monochromator using the shutter, so as to select the light beam of a specified wavelength and regulate the irradiation time of the carbon nanotube thin film transistor.

[0014] According to an embodiment of the present invention, the light beam emitted by the light source module is transmitted to the electrical measurement module via a beam splitter fiber to irradiate the carbon nanotube thin-film transistor and record the electrical test results corresponding to the first stage, including:

[0015] The shutter is opened, and the light beam emitted by the light source module is transmitted to the electrical measurement module through the optical fiber to irradiate the carbon nanotube thin film transistor, while a set of electrical test results are recorded at the same time.

[0016] Close the shutter until the recorded electrical test results return to the initial state; wherein the initial state corresponds to the electrical test results recorded before the carbon nanotube thin film transistor was illuminated;

[0017] The shutter is opened, and the light beam emitted by the light source module is transmitted to the electrical measurement module through the optical fiber to illuminate the carbon nanotube thin film transistor, while another set of electrical test results is recorded at the same time.

[0018] Close the shutter until the recorded electrical test results return to their initial state;

[0019] The shutter is switched on and off repeatedly until the light beam of the specified wavelength is applied to the carbon nanotube thin-film transistor.

[0020] According to an embodiment of the present invention, after the first stage measurement is completed in the above-mentioned electrical measurement module, the light source power of the light source module is adjusted according to the wavelength and intensity of the light beam fed back by the above-mentioned monitoring feedback module to achieve cyclic measurement. The measurement result is then updated to the above-mentioned defect characterization database, including:

[0021] Based on the types of light sources mentioned above, determine the minimum power of the light sources and the range of variation of the power of the light sources mentioned above;

[0022] The range of power variation of the above-mentioned light source is divided into multiple levels;

[0023] After completing the first stage of measurement, the light source power is adjusted to the next level based on the wavelength and intensity of the beam fed back by the monitoring feedback module, so as to achieve cyclic measurement.

[0024] The electrical measurement results obtained each time will be updated in the aforementioned defect characterization database.

[0025] According to an embodiment of the present invention, the electrical measurement results in the above-mentioned defect characterization database are compared and analyzed to determine the target defect characterization result, including:

[0026] The electrical measurement results corresponding to each stage are fitted into a curve;

[0027] By comparing and analyzing multiple fitted curves of the above electrical measurement results corresponding to each stage, the target defect characterization results are determined.

[0028] The above electrical test results are expressed in the form of photocurrent.

[0029] A second aspect of the present invention provides a defect testing system for carbon nanotube thin-film transistors, applied to implement the testing method described in any of the preceding claims, comprising:

[0030] A light source module suitable for generating light beams;

[0031] The monitoring feedback module is suitable for providing real-time feedback to the light source module on the wavelength and intensity of the light beam monitored by the monitoring feedback module.

[0032] An electrical testing module is used to irradiate the carbon nanotube thin-film transistor with the light beam transmitted by the light source module and record the electrical test results.

[0033] A pre-converter is suitable for integrating and analyzing the above electrical test results to obtain the target defect characterization results in the above carbon nanotube thin film transistors;

[0034] The light source module is connected to the monitoring feedback module and the electrical testing module via the optical fiber. After the monitoring feedback module detects the preset wavelength and intensity of the light beam, it feeds back to the light source module. The light source module then transmits the light beam to the electrical testing module for testing. Once the test is completed, the light source power is adjusted in the light source module to achieve cyclic testing.

[0035] According to an embodiment of the present invention, the above-mentioned light source module includes:

[0036] A light source suitable for generating a continuous spectrum from a preset wavelength band;

[0037] A scanning monochromator is suitable for adjusting the continuous spectrum generated by the above-mentioned light source, thereby controlling the light beam emitted by the light source at a specified wavelength;

[0038] The shutter is used to control the on / off state of the light beam transmitted by the aforementioned scanning monochromator and the duration of the on / off state.

[0039] According to an embodiment of the present invention, the light source includes one of a xenon lamp light source, a light-emitting diode light source, and a mercury lamp light source.

[0040] According to an embodiment of the present invention, the above-mentioned monitoring feedback module includes:

[0041] An integrating sphere is used to focus the light beam input from the aforementioned optical splitter fiber to the aforementioned monitoring feedback module.

[0042] The spectrometer is suitable for testing the intensity of the light beam focused by the integrating sphere, and the power of the light source can be adjusted based on the intensity feedback from the spectrometer.

[0043] Preferably, the integrating sphere is a hollow sphere with its inner wall coated with a white diffuse reflective material, and the spectrometer is a fixed grating.

[0044] According to an embodiment of the present invention, the above-mentioned electrical testing module includes:

[0045] The probe stage includes a base suitable for fixing the carbon nanotube thin film transistor and at least two adjustable probes disposed on the base.

[0046] An electrical testing instrument suitable for performing electrical tests on the aforementioned carbon nanotube thin-film transistors;

[0047] The aforementioned electrical testing module is configured in a shielded state to block external light sources and shield electromagnetic radiation.

[0048] The probe station is connected to the electrical testing instrument. When the probe contacts the carbon nanotube thin film transistor, the electrical testing instrument records the test results of defects present in the carbon nanotube thin film transistor.

[0049] Preferably, the probe station includes one of a manual probe station, a semi-automatic probe station, and a fully automatic probe station;

[0050] The aforementioned electrical testing instrument is a semiconductor parameter testing instrument.

[0051] According to embodiments of the present invention, a defect testing method and system for carbon nanotube thin-film transistors are proposed. By introducing a variable photocurrent method (specifically manifested by adjusting the power of the light source), the test is performed, and multiple measurement data obtained from the test are fitted and compared. Finally, the optimal value is taken as the target defect test result, thereby improving the accuracy of the test results. Attached Figure Description

[0052] The above-described features, other objects, and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0053] Figure 1 A flowchart illustrating a defect testing method for carbon nanotube thin-film transistors according to an embodiment of the present invention is shown schematically.

[0054] Figure 2 A schematic diagram of a defect testing system for carbon nanotube thin-film transistors according to an embodiment of the present invention is shown.

[0055] Figure 3 The diagram illustrates the relationship between the absorption rate and light energy of carbon nanotube thin-film transistors under different fabrication processes according to embodiments of the present invention.

[0056] Figure 4 The diagram illustrates the relationship between the absorption rate and light energy of a carbon nanotube thin-film transistor before and after annealing according to an embodiment of the present invention. Detailed Implementation

[0057] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0058] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0059] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0060] When using expressions such as "at least one of A, B, and C", the expression should generally be interpreted in accordance with the meaning commonly understood by those skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B, and C, etc.).

[0061] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0062] Figure 1 A flowchart illustrating a defect testing method for carbon nanotube thin-film transistors according to an embodiment of the present invention is shown.

[0063] like Figure 1 As shown, the defect testing method for carbon nanotube thin-film transistors provided by the exemplary embodiment of the present invention may include steps S110 to S150.

[0064] In step S110, a light beam is generated using a light source module.

[0065] According to an embodiment of the present invention, a light beam is generated using a light-emitting light source module, comprising:

[0066] The first program is run with minimum light source power to enable the scanning monochromator to adjust the continuous spectrum generated by the light source in order to achieve the emission of a light beam of a specified wavelength.

[0067] The second program is run to control the on / off state and duration of the beam transmitted by the scanning monochromator using the shutter, so as to select the beam of a specified wavelength and regulate the irradiation time of the carbon nanotube thin film transistor.

[0068] In step S120, the wavelength and intensity of the light beam emitted by the light source module are monitored in real time using the monitoring feedback module and fed back to the light source module.

[0069] In step S130, the light beam emitted by the light source module is transmitted to the electrical measurement module via a split optical fiber, irradiates the carbon nanotube thin film transistor, and records the electrical test results corresponding to the first stage. The electrical test results corresponding to the first stage include multiple sets of electrical test results corresponding to different wavelengths of the light beam emitted by the light source module.

[0070] According to an embodiment of the present invention, the light beam emitted by the light source module is transmitted to the electrical measurement module via a beam splitter fiber to irradiate the carbon nanotube thin-film transistor and record the electrical test results corresponding to the first stage, including:

[0071] The shutter is opened, and the light beam emitted by the light source module is transmitted to the electrical measurement module through the optical fiber to illuminate the carbon nanotube thin film transistor, while a set of electrical test results are recorded at the same time.

[0072] Close the shutter until the recorded electrical test results return to the initial state; where the initial state corresponds to the electrical test results recorded before the carbon nanotube thin film transistor was illuminated.

[0073] The shutter is opened, and the light beam emitted by the light source module is transmitted to the electrical measurement module through the optical fiber to illuminate the carbon nanotube thin film transistor, while another set of electrical test results is recorded at the same time.

[0074] Close the shutter until the recorded electrical test results return to their initial state;

[0075] The shutter is switched on and off repeatedly until the light beam of the specified wavelength is applied to the carbon nanotube thin-film transistor.

[0076] For example, first, a minimum power of the light source is set. The control unit controls the scanning monochromator to scan the light beam emitted by the light source from a preset long wavelength to a preset short wavelength. At each time interval t (t is a real number greater than 0), the beam moves through equally spaced wavelength bands for testing (that is, the test period for each wavelength band is consistent). When testing with a beam in the same wavelength band, the control unit controls the shutter opening and closing, thereby controlling the beam to reach the electrical measurement module through the shutter. Specifically, the shutter is opened for time t1 (t1 is a real number greater than 0 and less than t), and a portion of the beam reaches the electrical measurement module through the splitting fiber, simultaneously recording a set of electrical test results. Then, the shutter is closed (i.e., the shutter closing time is t-t1), and the set of electrical test results is saved to the defect characterization database. Simultaneously, the wavelength corresponding to the other portion of the beam is fed back to the spectrometer, and the light intensity corresponding to that wavelength band is recorded.

[0077] Subsequently, the wavelength corresponding to the beam is moved to the next wavelength at equal intervals, and the shutter is opened for time t1. Part of the beam reaches the electrical measurement module through the beam splitter fiber, while another set of electrical test results is recorded. Then, the shutter is closed (i.e., the shutter closing time is t-t1), and this set of electrical test results is updated to the defect characterization database. The wavelength corresponding to the other part of the beam is fed back to the spectrometer, and the light intensity corresponding to that wavelength is recorded. This process continues until the test beam moves from the corresponding preset long wavelength to the preset short wavelength under minimum light source power conditions, completing the first stage of the test.

[0078] According to an embodiment of the present invention, the interval time t can be set according to the dependence of the carbon nanotube thin film transistor under test on the accuracy of the test data. The smaller the interval time t, the smaller the measurement interval and the denser the measured data points.

[0079] In step S140, the electrical test results corresponding to multiple stages are input into the front-end data converter and integrated into a defect characterization database. After the first stage measurement is completed in the electrical measurement module, the light source power of the light source module is adjusted according to the wavelength and intensity of the light beam fed back by the monitoring feedback module to achieve cyclic measurement. Then, the obtained electrical measurement results are updated to the defect characterization database.

[0080] According to an embodiment of the present invention, after the first stage measurement is completed in the electrical measurement module, the light source power of the light source module is adjusted according to the wavelength and intensity of the light beam fed back by the monitoring feedback module to achieve cyclic measurement. The measurement results are then updated to the defect characterization database, including:

[0081] Determine the minimum power of the light source and the range of power variation based on the type of light source.

[0082] The range of light source power variation is divided into multiple levels;

[0083] After completing the first stage of measurement, the light source power is adjusted to the next level based on the wavelength and intensity of the beam fed back by the monitoring feedback module, so as to achieve cyclic measurement.

[0084] The electrical measurement results obtained each time are updated to the defect characterization database.

[0085] According to an embodiment of the present invention, after completing the first stage of testing, the power of the light source is adjusted to a preset second level, and the testing steps of the first stage are repeated to complete the measurement of multiple stages corresponding to the various light source powers set subsequently.

[0086] According to an embodiment of the present invention, the type of light source determines the minimum light source power and the range of light source power variation. Therefore, this power range is divided into N levels (N is an integer greater than 1; the larger the value of N, the denser the measured data points and the higher the accuracy). Each level adjustment corresponds to a stage of test data, and the test data of each stage includes multiple electrical test results measured under a fixed wavelength.

[0087] In step S150, the electrical measurement results in the defect characterization database are compared and analyzed to determine the target defect characterization result.

[0088] According to an embodiment of the present invention, the electrical measurement results in the defect characterization database are compared and analyzed to determine the target defect characterization result, including:

[0089] The electrical measurement results corresponding to each stage are fitted into a curve;

[0090] By comparing and analyzing multiple fitted curves of the electrical measurement results corresponding to each stage, the target defect characterization results are determined.

[0091] Among them, the electrical test results are represented in the form of photocurrent, and the target defect characterization results are represented by the relationship curve between light absorption rate and light energy.

[0092] Generally, the more types and numbers of defects in a semiconductor device, the more pronounced the abrupt changes in its electrical test results (i.e., the curve obtained by plotting the photocurrent over time). Furthermore, by processing the data in the pre-converter, the final value of the photoabsorption rate in the curve relating photoabsorption rate and photoenergy is determined to be larger. Based on this, after obtaining the change in photocurrent, the test data is input into the pre-converter.

[0093] According to embodiments of the present invention, by integrating and analyzing test data in a defect characterization database, a deterministic relationship between carrier mobility, quantum efficiency, and time constant can be obtained, thereby determining the relationship between absorbance and energy. It should be noted that through data analysis, the variables are transformed into deterministic variables or even constants. That is, the final correspondence between absorbance and energy is not affected by the uncertainty of the aforementioned three variables. Therefore, by comparing the analysis results, the characterization of different defects can be achieved.

[0094] According to an embodiment of the present invention, by integrating and analyzing the data in the defect characterization database, the relationship between the time constant, carrier mobility and quantum efficiency during the actual test process as a function of the light source power and wavelength can be obtained. Thus, the corresponding relationship between the absorptivity and the light energy can be calculated, thereby enabling the characterization of different defect states.

[0095] Specifically, the carrier mobility, quantum efficiency, and time constant are considered as a whole, which is a quantity related to the measured photocurrent I and light wavelength λ, denoted as f(I,λ); the other related parameters are denoted as constants C. Therefore, the absorptivity α = C * f(I,λ) * I. The photocurrent I is also related to the light source power P. L The relevant quantity, i.e., I(λ,P) L Therefore, the absorptivity can be changed by altering both the light wavelength and the light source power. A calibrated test condition P is selected. L0 After passing through the electrical testing module and the pre-converter, a set of α0 = C*f(I0,λ)*I0 is obtained. The power of the light source is changed to P. L1 This yields another set of α1 = C*f(I1,λ)*I1. By varying the power of multiple light sources, multiple curves relating absorptivity to light energy can be obtained. Light energy can characterize the location of defects in the material's energy band, while changes in absorptivity can characterize the number of defects.

[0096] In other words, after measuring the photocurrent value and storing it in the pre-converter, the data is then processed and fitted to obtain a determined f(P).L The relationship between f(P,λ) represents the overall relationship between carrier mobility, quantum efficiency, and time constant. It can be observed that during the fabrication of this carbon nanotube thin-film transistor, the obtained f(P,λ)... L Since the relationship between carrier mobility, quantum efficiency, and time constant does not change with the fabrication process, in subsequent defect testing, the influence of the overall relationship between carrier mobility, quantum efficiency, and time constant on defect testing is no longer considered. Instead, the change in absorbance relative to light energy under test conditions is directly obtained by processing the measured photocurrent, thereby characterizing the number of defects.

[0097] According to embodiments of the present invention, a light-assisted electrical testing method introduces varying photocurrents for testing and compares and fits multiple measurement data obtained from the tests, ultimately using the optimal value as the test result for the target defect. This overcomes the over-reliance on the control of testing equipment and testing accuracy caused by the single measurement data in traditional measurement methods, while also improving the accuracy of the test results. Furthermore, the testing method of this scheme only requires adjustment of the light source power before testing, making the method simple; it also avoids the cumbersome operation and impact on the accuracy of test data caused by multiple adjustments of the light source current during testing in related technologies.

[0098] In embodiments of the present invention, the defect testing method provided by this solution is particularly suitable for defect testing of carbon nanotube thin-film transistors with polymer groups on their surfaces. Preferably, taking a polycarbazole-coated carbon nanotube thin-film transistor as an example, this testing method is used to characterize its interface state defects.

[0099] For the characterization of interface states in polycarbazole-coated carbon nanotube thin-film transistors, single electrical characterization methods, such as high- and low-frequency electrochemical methods, are generally employed. However, these methods cannot be accurately measured because interface defects cannot match the frequency changes of high-frequency signals. Furthermore, traditional high- and low-frequency electrochemical methods cannot fill the interface states introduced by polycarbazole; in addition, defects introduced by polycarbazole can also transfer charge, thus causing serious interference to the measurement of defects using traditional measurement methods.

[0100] The optically assisted electrical testing method provided in this solution introduces a changing photocurrent for testing. This not only allows for optical filling of defects introduced by polycarbazole, thereby minimizing its interference with defect measurement and improving the accuracy of high-frequency electrical signal measurement, but also enables the introduction of a light source to distinguish various coupling phenomena caused by the thinness of ultrathin carbon nanotube thin-film transistors.

[0101] Specifically, on the one hand, in traditional electrical testing, when only an electrical signal is introduced, the number of charge carriers generated is insufficient to support a good match between the defect and the frequency changes of the high-frequency electrical signal, resulting in inaccurate measurement data. However, by introducing an illumination element (i.e., introducing an optical signal) into the test, more charge carriers can be excited from the defect, thereby better matching the frequency changes of the high-frequency electrical signal.

[0102] On the other hand, the polycarbazole in the polycarbazole-coated carbon nanotube thin-film transistor responds to electrical signals during testing, significantly affecting the electrical test results. Therefore, introducing an optical signal during testing—for example, a beam of light transmitted via a split optical fiber to the electrical test module—is considered to illuminate the surface of the polycarbazole-coated carbon nanotube thin-film transistor placed on the probe stage. Testing is then performed after a period of light irradiation, which can fill the defects introduced by the polycarbazole. In other words, the number of defect sites in the polycarbazole-coated carbon nanotube thin-film transistor is fixed, and these sites can respond to both electrical and optical signals. Since the electrical test results in this scheme are expressed as photocurrent values ​​(i.e., characterized by electrical signals), introducing an optical signal allows the defect sites to respond to the optical signal during testing, reducing the response to electrical signals and thus ensuring that the electrical test results are not affected.

[0103] The testing procedure for defects in polycarbazole-coated carbon nanotube thin-film transistors is as follows: Using minimum light source power, a scanning monochromator controlled by a control unit scans the emitted light beam from 600nm to 200nm, moving 10nm every 20s for testing (i.e., the testing cycle for a fixed test wavelength is 20s). When testing with a beam of the same wavelength, the control unit controls the shutter opening and closing, thereby controlling the beam to reach the electrical measurement module for testing. Specifically, the shutter is opened for 500ms, a portion of the beam reaches the electrical measurement module via a split fiber, and the electrical test result is recorded. Then, the shutter is closed (i.e., shutter closed for 19500ms), and the obtained electrical test result is saved to the defect characterization database. Simultaneously, the wavelength corresponding to the other portion of the beam is fed back to the spectrometer, and the light intensity corresponding to that wavelength is recorded.

[0104] Subsequently, the wavelength corresponding to the beam was shifted by 10 nm, and the shutter was opened for 500 ms. Part of the beam reached the electrical measurement module via the beam splitter fiber, while another electrical test result was recorded. Then, the shutter was closed (i.e., shutter closed for 19500 ms), and the electrical test data was updated to the defect characterization database. The wavelength corresponding to the other part of the beam was fed back to the spectrometer, and the light intensity corresponding to that wavelength was recorded. This process continued until the wavelength corresponding to the test beam was shifted from 600 nm to 200 nm under minimum light source power conditions, completing the first stage of the test.

[0105] The type of light source determines the minimum power and the range of power variation. For testing defects in polycarbazole-coated carbon nanotube thin-film transistors, preferably, the power range is divided into 100 levels. Each level corresponds to a stage of test data, and the test data for each stage includes multiple electrical test results measured at a fixed wavelength.

[0106] According to an embodiment of the present invention, the data points obtained from the first stage measurement are first fitted into a curve. After adjusting the power of the light source, the numerous measurement data are fitted into multiple curves. The curves corresponding to different photocurrents are compared and analyzed, and the optimal value is finally taken as the target defect test result.

[0107] Figure 2 A schematic diagram of a defect testing system for carbon nanotube thin-film transistors according to an embodiment of the present invention is shown.

[0108] like Figure 2 As shown, the defect testing system for carbon nanotube thin-film transistors includes: a light source module, a monitoring feedback module, an electrical testing module, and a front-end data converter.

[0109] The light source module is used to generate a light beam; the monitoring feedback module is used to provide real-time feedback to the light source module on the wavelength and intensity of the light beam monitored by the monitoring feedback module; the electrical testing module is used to characterize the target defects using the light beam transmitted by the light source module. The light source module is connected to both the monitoring feedback module and the electrical testing module via a splitting optical fiber. After the monitoring feedback module detects the preset wavelength and intensity of the light beam, it feeds it back to the light source module, which then transmits the light beam to the electrical testing module for testing. Once the test is complete, the light source power is adjusted within the light source module to achieve cyclic testing.

[0110] According to an embodiment of the present invention, the light source module includes: a control unit, a light source, a scanning monochromator, and a shutter. The control unit is suitable for regulating the power of the light source; the light source is suitable for generating a continuous spectrum of a preset wavelength; the scanning monochromator is suitable for adjusting the continuous spectrum generated by the light source to control the light beam emitted by the light source at a specified wavelength; the shutter is suitable for controlling the on / off state and duration of the light beam transmitted by the scanning monochromator.

[0111] According to embodiments of the present invention, the light source includes one of a xenon lamp, a light-emitting diode (LED) lamp, or a mercury lamp; it can generate a continuous spectrum from the ultraviolet band to the infrared band (220–1100 nm). Its visible light color is very close to white light, it has high energy density, and its output is stable. Therefore, the light source power can be adjusted to change the light intensity in this band.

[0112] According to embodiments of the present invention, a scanning monochromator can achieve continuous adjustment of the wavelength of a light beam. Specifically, the emission of a light beam of a specific wavelength is achieved through the combined action of grating conversion, filter replacement, and wavelength scanning.

[0113] According to an embodiment of the present invention, the shutter can be opened and closed manually or by a control unit, thereby controlling the on / off state and duration of the light beam transmitted by the scanning monochromator.

[0114] According to an embodiment of the present invention, the control unit can not only adjust the power of the light source and the wavelength of the light beam output by the scanning monochromator, but also control the opening and closing of the shutter and the duration of the opening and closing.

[0115] According to an embodiment of the present invention, the light source module is connected to the monitoring feedback module and the electrical testing module respectively via a beam splitting fiber. Preferably, the beam splitting fiber adopts a 1:9 splitting ratio and is connected to the monitoring feedback module (connected to a fiber with a splitting ratio of 0.1) and the electrical testing module (connected to a fiber with a splitting ratio of 0.9), respectively.

[0116] According to an embodiment of the present invention, the monitoring feedback module includes an integrating sphere and a spectrometer. The integrating sphere is used to focus the light beam input to the monitoring feedback module from the optical fiber; the spectrometer is used to test the intensity of the light beam focused by the integrating sphere, and the power of the light source is adjusted based on the intensity fed back by the spectrometer.

[0117] According to an embodiment of the present invention, preferably, the integrating sphere is a hollow sphere with its inner wall coated with a white diffuse reflective material, which can output a very uniform diffusely scattered beam to focus the beam and avoid beam loss before entering the spectrometer. The spectrometer is a fixed grating that can measure the wavelength of the beam in the range of 200 to 1100 nm and the intensity of the beam. Specifically, the intensity of the beam focused by the integrating sphere is tested to provide feedback and adjust the power of the light source.

[0118] According to an embodiment of the present invention, the electrical testing module includes a probe station and an electrical testing instrument. The probe station includes a base suitable for fixing a carbon nanotube thin-film transistor and at least two adjustable probes disposed on the base; the electrical testing instrument is suitable for performing electrical tests on the carbon nanotube thin-film transistor; wherein, the electrical testing module is configured in a shielded state to block external light sources and shield electromagnetic radiation; the probe station is connected to the electrical testing instrument, and when the probes contact the carbon nanotube thin-film transistor, the electrical testing instrument records the test results of defects present in the carbon nanotube thin-film transistor.

[0119] According to an embodiment of the present invention, the specific testing process of the electrical testing module is a standard electrical testing procedure. Specifically, the current-time test option is selected for continuous testing (no operation is performed during the test, and the tester automatically records the current changes), and illumination begins after 30 seconds. The reason for selecting a certain interval, such as 30 seconds, is to ensure that it is not affected by abnormal current changes when the voltage is first applied; the current becomes more stable. The electrical test is stopped after the illumination scan stops, and no further operation of the electrical testing module is required during the test.

[0120] According to embodiments of the present invention, in order to achieve shielding, the probe station and electrical tester are generally placed in a black metal box or wrapped with electromagnetic shielding cloth, or both methods are used at the same time to provide a dark room, thereby blocking external light sources and shielding electromagnetic radiation.

[0121] According to an embodiment of the present invention, preferably, the probe station includes one of a manual probe station, a semi-automatic probe station, and a fully automatic probe station; the electrical tester is configured to have sub-PA level resolution, including one or more of an inductance, capacitance, and resistance tester and a multimeter.

[0122] Figure 3 The diagram illustrates the relationship between the absorption rate and light energy of carbon nanotube thin-film transistors under different fabrication processes according to embodiments of the present invention.

[0123] Figure 4 The diagram illustrates the relationship between the absorption rate and light energy of a carbon nanotube thin-film transistor before and after annealing according to an embodiment of the present invention.

[0124] By setting a specific power for the light source and irradiating devices manufactured using different processes, the changes in various types of defects in devices manufactured using different processes can be characterized. In measuring the change of photocurrent over time, the measured photocurrent peak values ​​are extracted and processed to obtain photocurrent values ​​at different wavelengths.

[0125] Generally, the more types and quantities of defects in a semiconductor device, the more pronounced the abrupt changes in its electrical test results (i.e., the curve obtained by plotting photocurrent over time). Furthermore, by processing the data in the pre-converter, the final determined value of the light absorptivity in the light energy-light absorptivity curve is larger. Therefore, by comparing the absorptivity values, the relative number of defects in semiconductor devices fabricated using different processes can be directly obtained.

[0126] like Figure 3 As shown, the horizontal axis represents the absorptivity, and the vertical axis represents the energy value related to the wavelength. Since a higher absorptivity results in more defects, the number of defects in the polycarbazole-coated carbon nanotube thin-film transistors prepared using process two is reduced.

[0127] like Figure 4 As shown, the horizontal axis represents the absorptivity, and the vertical axis represents the energy value related to the wavelength. Since a higher absorptivity indicates more defects, the number of defects in the polycarbazole-coated carbon nanotube thin-film transistor was significantly reduced after annealing at 200°C for 30 minutes under atmospheric conditions.

[0128] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A defect testing method for carbon nanotube thin-film transistors, characterized in that, include: A light beam is generated using a light-emitting light source module; The wavelength and intensity of the light beam emitted by the light source module are monitored in real time using the monitoring feedback module, and then fed back to the light source module. The light beam emitted by the light source module is transmitted to the electrical measurement module via a beam splitter fiber, irradiates the carbon nanotube thin film transistor, and records the electrical test results corresponding to the first stage. The electrical test results corresponding to the first stage include multiple sets of electrical test results corresponding to different wavelengths of the light beam emitted by the light source module. The electrical test results corresponding to multiple stages are input into the front-end data converter and integrated into a defect characterization database. After the first stage measurement is completed in the electrical measurement module, the light source power of the light source module is adjusted according to the wavelength and intensity of the light beam fed back by the monitoring feedback module to achieve cyclic measurement. The obtained electrical test results are then updated to the defect characterization database. The electrical test results in the defect characterization database are compared and analyzed to determine the target defect characterization result.

2. The test method according to claim 1, characterized in that, The light beam is generated using a light source module, including: The first program is run with minimum light source power to enable the scanning monochromator to adjust the continuous spectrum generated by the light source in order to achieve the emission of a light beam of a specified wavelength. The second program is run to control the on / off state and duration of the light beam transmitted by the scanning monochromator using the shutter, so as to select the light beam of a specified wavelength and regulate the irradiation time of the carbon nanotube thin film transistor.

3. The test method according to claim 1, characterized in that, The light beam emitted by the light source module is transmitted to the electrical measurement module via a beam-splitting optical fiber, illuminating the carbon nanotube thin-film transistor and recording the electrical test results corresponding to the first stage, including: The shutter is opened, and the light beam emitted by the light source module is transmitted to the electrical measurement module through the optical fiber to illuminate the carbon nanotube thin film transistor, while a set of electrical test results are recorded at the same time. The shutter is closed until the recorded electrical test results return to the initial state; wherein, the initial state corresponds to the electrical test results recorded before the carbon nanotube thin film transistor was illuminated; The shutter is opened, and the light beam emitted by the light source module is transmitted to the electrical measurement module through the optical fiber to illuminate the carbon nanotube thin film transistor, while another set of electrical test results is recorded at the same time. Close the shutter until the recorded electrical test results return to the initial state of the carbon nanotube thin-film transistor; The shutter is switched on and off repeatedly until the specified wavelength of light beam is applied to the carbon nanotube thin-film transistor.

4. The test method according to claim 1, characterized in that, After completing the first stage of measurement in the electrical measurement module, the light source power of the light source module is adjusted according to the wavelength and intensity of the light beam fed back by the monitoring feedback module to achieve cyclic measurement. The measurement results are then updated to the defect characterization database, including: Based on the type of light source, determine the minimum power of the light source and the range of variation of the light source power; The range of power variation of the light source is divided into multiple levels; After completing the first stage of measurement, the light source power is adjusted to the next level based on the wavelength and intensity of the beam fed back by the monitoring feedback module, so as to achieve cyclic measurement. The electrical test results obtained each time are updated to the defect characterization database.

5. The test method according to claim 1, characterized in that, The electrical test results in the defect characterization database are compared and analyzed to determine the target defect characterization results, including: The electrical test results corresponding to each stage are fitted into a curve; By comparing and analyzing multiple fitting curves of the electrical test results corresponding to each stage, the target defect characterization results are determined. The electrical test results are expressed in the form of photocurrent.

6. A defect testing system for carbon nanotube thin-film transistors, applied to implement the testing method according to any one of claims 1 to 5, comprising: A light source module suitable for generating light beams; The monitoring feedback module is suitable for providing real-time feedback to the light source module on the wavelength and intensity of the light beam monitored by the monitoring feedback module; An electrical testing module is used to irradiate the carbon nanotube thin-film transistor with a light beam transmitted by the light source module and record the electrical test results. A pre-data converter is suitable for integrating and analyzing the electrical test results to obtain the characterization results of the target defects in the carbon nanotube thin film transistor; The light source module is connected to the monitoring feedback module and the electrical testing module via the optical fiber. After the monitoring feedback module detects the preset wavelength and intensity of the light beam, it feeds back to the light source module. The light source module then transmits the light beam to the electrical testing module for testing. Once the test is completed, the light source module adjusts the power of the light source to achieve cyclic testing.

7. The testing system according to claim 6, characterized in that, The light source module includes: A light source suitable for generating a continuous spectrum within a preset wavelength band; A scanning monochromator is suitable for adjusting the continuous spectrum generated by the light source, thereby controlling the light beam emitted by the light source at a specified wavelength. The shutter is used to control the on / off state of the light beam transmitted by the scanning monochromator and the duration of the on / off state.

8. The testing system according to claim 7, characterized in that, The light source includes one of xenon lamp light source, light-emitting diode light source, and mercury lamp light source.

9. The testing system according to claim 6, characterized in that, The monitoring feedback module includes: An integrating sphere is used to focus the light beam input from the splitting optical fiber to the monitoring feedback module. The spectrometer is suitable for testing the intensity of the light beam focused by the integrating sphere, and the power of the light source can be adjusted based on the intensity feedback from the spectrometer.

10. The testing system according to claim 9, characterized in that, The integrating sphere is a hollow sphere with its inner wall coated with a white diffuse reflective material, and the spectrometer is a fixed grating.

11. The testing system according to claim 6, characterized in that, The electrical testing module includes: The probe station includes a base suitable for fixing the carbon nanotube thin film transistor and at least two adjustable probes disposed on the base; An electrical testing instrument suitable for performing electrical tests on the carbon nanotube thin-film transistors; The electrical testing module is configured to be shielded to block external light sources and shield electromagnetic radiation. The probe station is connected to the electrical testing instrument. When the probe contacts the carbon nanotube thin film transistor, the electrical testing instrument records the test results of defects present in the carbon nanotube thin film transistor.

12. The testing system according to claim 11, characterized in that, The probe station includes one of a manual probe station, a semi-automatic probe station, and a fully automatic probe station. The electrical testing instrument is a semiconductor parameter tester.

Images