KR102486957B1 - Apparatus for Testing Oxide Semiconductor Thin Film - Google Patents

Abstract

The present invention relates to a connection portion for contacting an oxide semiconductor thin film; a voltage application unit connected to the connection unit and applying a test voltage, which is increased from a preset initial voltage to a preset maximum voltage and then lowered back to the initial voltage, to the oxide semiconductor thin film through the connection unit; a current measuring unit measuring a test current according to the application of the test voltage to the oxide semiconductor thin film; And while the test voltage is applied to the oxide semiconductor thin film while being lowered again to the initial voltage after increasing from the initial voltage to the maximum voltage, the test voltage applied by the voltage applying unit to the oxide semiconductor thin film and the test voltage for each test voltage. It relates to an oxide semiconductor thin film inspection device comprising a calculator for calculating a first electrical characteristic value for the oxide semiconductor thin film or a second electrical characteristic value different from the first electrical characteristic value by using the test current measured by the current measuring unit. .

Description

Oxide Semiconductor Thin Film Inspection Apparatus {Apparatus for Testing Oxide Semiconductor Thin Film}

The present invention relates to an oxide semiconductor thin film inspection device for inspecting electrical characteristics of an oxide semiconductor thin film.

An oxide semiconductor is made of metal oxide among semiconductors, and may be deposited on a substrate in the process of manufacturing a display device, a solar cell, and the like, and implemented as an oxide semiconductor thin film.

For example, IGZO composed of indium (In), gallium (Ga), zinc (Zn), and oxygen (O) is deposited on a substrate in the process of manufacturing a thin film transistor (TFT) of a display device, and is an oxide semiconductor thin film. can be implemented as

Conventionally, electrical characteristics of oxide semiconductor thin films were examined in a state in which thin films made of materials other than oxide semiconductor thin films were deposited. Accordingly, in the related art, due to mutual interactions between the oxide semiconductor thin film and other thin films, it is difficult to inspect the electrical characteristics of the oxide semiconductor thin film itself and the accuracy of the inspection result is low.

The present invention has been made to solve the problems described above, and to provide an oxide semiconductor thin film inspection device capable of solving the difficulty of inspecting the electrical characteristics of the oxide semiconductor thin film itself and increasing the accuracy of the inspection result. it is for

In order to solve the above problems, the present invention may include the following configuration.

An oxide semiconductor thin film inspection apparatus according to the present invention includes a connection portion for contacting an oxide semiconductor thin film; a voltage application unit connected to the connection unit and applying a test voltage, which is increased from a preset initial voltage to a preset maximum voltage and then lowered back to the initial voltage, to the oxide semiconductor thin film through the connection unit; a current measuring unit measuring a test current according to the application of the test voltage to the oxide semiconductor thin film; And while the test voltage is applied to the oxide semiconductor thin film while being lowered again to the initial voltage after increasing from the initial voltage to the maximum voltage, the test voltage applied by the voltage applying unit to the oxide semiconductor thin film and the test voltage for each test voltage. A calculation unit may be included to calculate a first electrical characteristic value of the oxide semiconductor thin film or a second electrical characteristic value different from the first electrical characteristic value by using the test current measured by the current measurement unit.

According to the present invention, the following effects can be achieved.

The present invention is implemented so that the electrical characteristics of the oxide semiconductor thin film itself can be inspected by calculating the electrical characteristic values correlated with the electrical characteristics of the oxide semiconductor thin film. Therefore, the present invention can improve the ease of testing the electrical properties of the oxide semiconductor thin film itself, and improve the accuracy of the inspection result of inspecting the electrical characteristics of the oxide semiconductor thin film itself.

1 is a schematic configuration diagram of an oxide semiconductor thin film inspection apparatus according to the present invention
2 to 4 are graphs of inspection voltage and inspection current according to the result of inspecting the oxide semiconductor thin film by the oxide semiconductor thin film inspection apparatus according to the present invention.
5 is a graph showing an enlarged portion A of FIG. 2 to explain a process of calculating a threshold voltage by an oxide semiconductor thin film inspection apparatus according to the present invention.

Hereinafter, an embodiment of an oxide semiconductor thin film inspection apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

1 to 3, the oxide semiconductor thin film inspection apparatus 1 according to the present invention is an oxide semiconductor thin film (not shown) formed on a substrate in the process of manufacturing a display device, a solar cell, and the like. to check the electrical properties. For example, the oxide semiconductor thin film may be IGZO composed of indium (In), gallium (Ga), zinc (Zn), and oxygen (O).

An oxide semiconductor thin film inspection apparatus 1 according to the present invention includes a connection part 2 for contacting the oxide semiconductor thin film 100, and a voltage for applying an inspection voltage to the oxide semiconductor thin film 100 through the connection part 2. An application unit 3, a current measurement unit 4 for measuring the inspection current according to the application of the inspection voltage to the oxide semiconductor thin film 100, and the test applied by the voltage application unit 3 to the oxide semiconductor thin film It may include a calculator 5 that calculates an electrical characteristic value for the oxide semiconductor thin film using the voltage and the test current measured by the current measurement unit 4 for each test voltage.

The voltage applying unit 3 applies a test voltage that is increased from a preset initial voltage to a preset maximum voltage and then lowered back to the initial voltage to the oxide semiconductor thin film 100 through the connection unit 2 . In this process, the current measuring unit 4 measures the inspection current for each inspection voltage. Accordingly, the oxide semiconductor thin film inspection apparatus 1 according to the present invention can derive a graph for inspection voltage and inspection current as shown in FIGS. 2 and 3 . From this, the calculator 5 may calculate electrical characteristic values of the oxide semiconductor thin film 100 .

Here, the oxide semiconductor thin film 100 may have different chargeable capacities depending on the thin film material, and even if the thin film material is the same, the chargeable capacity may be implemented differently depending on thin film formation conditions, thin film density, and the like. In this way, the oxide semiconductor thin film 100 may be implemented to have different characteristics. If the calculator 5 always calculates only the same electrical characteristic values regardless of the characteristics of the oxide semiconductor thin film 100, the oxide semiconductor thin film 100 may be implemented. The reliability of the data evaluating the quality of (100) may deteriorate.

To solve this problem, the calculator 5 may be implemented to calculate a first electrical characteristic value or a second electrical characteristic value different from the first electrical characteristic value of the oxide semiconductor thin film 100 . In this case, the calculator 5 may derive the first electrical characteristic value or the second electrical characteristic value according to the characteristics of the oxide semiconductor thin film 100 . For example, the calculator 5 may calculate at least one of a holding current change value, a section current change value, and a comparison threshold voltage as the first electrical characteristic value. The calculation unit 5 may calculate a total inspection current based on the second electrical characteristic value. The present patent applicant finds that the first electrical characteristic value and the second electrical characteristic value correlate with the oxygen (O ₂ ) partial pressure ratio with respect to the oxide semiconductor thin film 100 itself (ie, the oxide semiconductor thin film 100 monolayer film). It was derived that there is a relationship. Since there is a correlation between the oxygen partial pressure rate and the device mobility, it can be seen that the first electrical characteristic value, the second electrical characteristic value, the oxygen partial pressure rate, and the device mobility are correlated.

Among the first electrical characteristic values, the holding current change value is the initial inspection current and the maximum voltage at the time when the inspection voltage reaches the maximum voltage in a rising section (US) in which the inspection voltage increases from the initial voltage to the maximum voltage. It is a value corresponding to the difference between the final inspection current from the time of reaching to the time of elapse of the preset reference time in the state in which the maximum voltage is maintained. The holding current change value may correspond to an absolute value of a difference between the initial test current and the final test current. It can be seen that the higher the holding current change value, the lower the oxygen partial pressure rate and the lower the oxygen deficiency (O ₂ Defect), and the higher the device mobility.

Among the first electrical characteristic values, the section current change value divides a preset reference section into a plurality of unit sections according to a preset section voltage in a falling section (DS) in which the test voltage is lowered from the maximum voltage to the initial voltage. , which is the change value of the inspection current for each unit section. For example, if the reference section is 500V to 400V and the section voltage is 20V, the section current change value is the inspection current for each unit section consisting of 500V to 480V, 480V to 460V, 460V to 440V, 440V to 420V, and 420V to 400V. may be a changed value. It can be seen that the higher the section current change value, the lower the oxygen partial pressure and oxygen deficiency, and the higher the device mobility.

Among the first electrical characteristic values, the comparison threshold voltage is related to the threshold voltage calculated using the test voltage and test current in the rising section US. The threshold voltage is a value corresponding to a voltage at a time when current flows through the oxide semiconductor thin film 100 . When these threshold voltages are calculated multiple times, the comparison threshold voltage is a value corresponding to a difference between two threshold voltages selected from among the threshold voltages. For example, the comparison threshold voltage may be a value corresponding to a difference between the last calculated threshold voltage and the second calculated threshold voltage. It can be seen that the higher the comparison threshold voltage, the higher the oxygen partial pressure and the higher the oxygen deficiency, and the lower the device mobility.

Among the second electrical characteristic values, the total inspection current is a sum of all inspection currents from the initial voltage to the maximum voltage until the inspection voltage decreases to the initial voltage again. It can be seen that the higher the total test current, the lower the oxygen partial pressure and the lower the oxygen deficiency, and the higher the device mobility.

After calculating the second electrical characteristic value or the first electrical characteristic value for each of the first measurement point and the second measurement point, the quality of the oxide semiconductor thin film 100 is compared through an operation of comparing the relative difference between each other. this can be evaluated. The first measuring point and the second measuring point may be calculated for the oxide semiconductor thin film 100 formed on different substrates. For example, the first measuring point may be calculated for the oxide semiconductor thin film 100 formed on the first substrate, and the second measuring point may be calculated for the oxide semiconductor thin film 100 formed on the second substrate. In this case, the relative quality between the oxide semiconductor thin film 100 formed on the first substrate and the oxide semiconductor thin film 100 formed on the second substrate can be evaluated. Any one of the first substrate and the second substrate may be a reference specimen. In this case, a pass/fail determination is made by comparing the first or second electrical characteristic value calculated for the other substrate with the first or second electrical characteristic value calculated for the reference specimen. may be done The first measurement point and the second measurement point may be calculated for the oxide semiconductor thin film 100 formed on the same substrate. In this case, the first measuring point and the second measuring point correspond to different parts of the oxide semiconductor thin film 100, and the relative quality of the different parts of the oxide semiconductor thin film 100 can be evaluated. .

As such, the oxide semiconductor thin film inspection apparatus 1 according to the present invention calculates the first electrical characteristic value or the second electrical characteristic value correlated with the electrical characteristic of the oxide semiconductor thin film 100, thereby calculating the oxide semiconductor thin film 100. It is implemented to inspect the electrical characteristics of the semiconductor thin film 100 itself. Therefore, the oxide semiconductor thin film inspection apparatus 1 according to the present invention can improve the ease of testing the electrical characteristics of the oxide semiconductor thin film 100 itself, and the electrical characteristics of the oxide semiconductor thin film 100 itself. can improve the accuracy of the inspection results.

On the other hand, the oxide semiconductor thin film inspection apparatus 1 according to the present invention determines the first electrical characteristic value or the second electrical characteristic value in advance through a reference specimen prepared by classifying the oxide semiconductor thin film 100 according to the oxygen partial pressure ratio. The oxide semiconductor thin film 100 by calculating and storing a standard value, calculating the first electrical characteristic value or the second electrical characteristic value for the oxide semiconductor thin film 100 to be inspected, and comparing it with a pre-stored standard value It is also possible to detect the inspection result of determining the defect, uniformity, and the like.

Hereinafter, the connection unit 2, the voltage applying unit 3, the current measuring unit 4, and the calculating unit 5 will be described in detail with reference to the accompanying drawings.

Referring to FIGS. 1 to 3 , the connection part 2 is to be in contact with the oxide semiconductor thin film 100 . The connection part 2 may be electrically connected to the voltage applying part 3 and the current measuring part 4 . Accordingly, when the connection part 2 is connected to the oxide semiconductor thin film 100, the voltage applying part 3 may apply the inspection voltage to the oxide semiconductor thin film 100 through the connection part 2. there is. During this process, the current measuring unit 4 may measure the inspection current through the connection unit 2 . In a state where the oxide semiconductor thin film 100 is formed on the substrate 200 , the connection part 2 may contact the oxide semiconductor thin film 100 . The substrate 200 may be supported on a stage (not shown).

The connection part 2 may include a first connection member 21 and a second connection member 22 .

The first connecting member 21 and the second connecting member 22 may contact different portions of the oxide semiconductor thin film 100 . Accordingly, the oxide semiconductor thin film inspection apparatus 1 according to the present invention may be implemented to calculate the electrical characteristic values of the oxide semiconductor thin film 100 using a two-probe method. The connection part 2 may be implemented as a probe card. In this case, the first connecting member 21 and the second connecting member 22 may correspond to a plurality of probe pins of the probe card. The voltage applying unit 3 may apply the inspection voltage to the oxide semiconductor thin film 100 through the first connecting member 21 and the second connecting member 22 . The current measuring unit 4 may measure the test current through the first connecting member 21 and the second connecting member 22 .

Although not shown, the connection part 2 may be movably implemented by a moving part. In this case, the oxide semiconductor thin film inspection apparatus 1 according to the present invention can change the position where the oxide semiconductor thin film 100 is inspected through the connection part 2 by moving the connection part 2 through the moving part. there is. Therefore, the oxide semiconductor thin film inspection apparatus 1 according to the present invention can be implemented to calculate the electrical characteristic values for the oxide semiconductor thin film 100 implemented in a large area.

Referring to FIGS. 1 to 3 , the voltage application unit 3 applies the inspection voltage to the oxide semiconductor thin film 100 through the connection unit 2 . The voltage application unit 3 may be electrically connected to the connection unit 2 . The voltage applying unit 3 may apply a test voltage that is increased from the initial voltage to the maximum voltage and then lowered to the initial voltage again. The initial voltage and the maximum voltage may be preset by an operator. The initial voltage and the maximum voltage may be obtained in advance through a preliminary inspection of a specimen having the same material, oxygen partial pressure, and the like of the oxide semiconductor thin film 100 to be inspected.

The voltage applying unit 3 may include a voltage generating module 31 and a voltage variable module 32 .

The voltage generating module 31 generates voltage. The voltage generated by the voltage generating module 31 may be applied to the oxide semiconductor thin film 100 through the connection part 2 while being varied by the voltage variable module 32 .

The voltage varying module 32 may generate the test voltage by varying the voltage generated by the voltage generating module 31 between the initial voltage and the maximum voltage. The voltage variable module 32 converts the voltage generated by the voltage generating module 31 between the initial voltage corresponding to a negative (-) voltage and the maximum voltage corresponding to a positive (+) voltage. can also be variable. In a state where the connection part 2 is in contact with the oxide semiconductor thin film 100, the voltage variable module 32 raises the voltage generated by the voltage generating module 31 from the initial voltage to the maximum voltage, and then again. It is possible to perform a variable lowering to the initial voltage. Accordingly, a test voltage that increases from the initial voltage to the maximum voltage and then decreases to the initial voltage may be applied to the oxide semiconductor thin film 100 .

Referring to FIGS. 1 to 3 , the current measuring unit 4 measures a test current according to the application of the test voltage to the oxide semiconductor thin film 100 . The current measuring unit 4 may be electrically connected to the connection unit 2 . Accordingly, the current measurement unit 4 may measure the inspection current through the connection unit 2 . Since the test voltage is applied to the oxide semiconductor thin film 100 while varying between the initial voltage and the maximum voltage, the current measuring unit 4 may measure the test current for each test voltage. The current measuring unit 4 may be implemented as an ammeter.

Referring to FIGS. 1 to 3 , the calculator 5 calculates an electrical voltage for the oxide semiconductor thin film 100 using a test voltage applied to the oxide semiconductor thin film 100 and a test current measured for each test voltage. to calculate the characteristic value. In this case, the calculator 5 may calculate the first electrical characteristic value or the second electrical characteristic value according to the characteristics of the oxide semiconductor thin film 100 . The calculation unit 5 may receive the test voltage applied to the oxide semiconductor thin film 100 from the voltage application unit 3 . The calculator 5 may receive the test current measured for each test voltage from the current measurer 4 . Using the test voltage and test current received as described above, the calculator 5 may calculate the first electrical characteristic value or the second electrical characteristic value. The calculator 5 may calculate at least one of the holding current change value, the section current change value, and the comparison threshold voltage as the first electrical characteristic value. The calculator 5 may calculate the total inspection current using the second electrical characteristic value.

The calculation unit 5 may include a calculation module 51 .

The calculation module 51 calculates the first electrical characteristic value or the second electrical characteristic value. When it is determined which of the first electrical characteristic value and the second electrical characteristic value to be calculated according to the characteristics of the oxide semiconductor thin film 100, the calculation module 51 determines the first electrical characteristic value according to the determination result. Alternatively, the second electrical characteristic value may be calculated.

A detailed process of calculating the holding current change value, the section current change value, and the comparison threshold voltage belonging to the first electrical characteristic value by the calculation module 51 is as follows.

First, looking at the process of calculating the holding current change value with reference to FIGS. 1 and 4, the voltage applying unit 3 maintains the maximum voltage for a predetermined reference time when the voltage increases from the initial voltage to the maximum voltage. After that, a test voltage lowered to the initial voltage may be applied. The reference time may be preset by an operator. The reference time may be obtained in advance through a preliminary inspection of a specimen having the same material, oxygen partial pressure, and the like of the oxide semiconductor thin film 100 to be inspected.

The calculation module 51 extracts an initial inspection current at the time when the maximum voltage is reached and a final inspection current at the time when the reference time elapses in a state where the maximum voltage is maintained from the time when the maximum voltage is reached, The holding current change value may be calculated by calculating a difference between the initial inspection current and the final inspection current. In FIG. 4 , V _f is the maximum voltage, I _i is the initial test current, and I _f is the final test current. In this case, the holding current change value may be an absolute value obtained by calculating (I _i - I _f ).

The calculation module 51 may calculate a plurality of holding current change values for the first measurement point and may calculate a plurality of holding current change values for the second measurement point. In this case, in a state where the connection part 2 is in contact with the first measuring point, the voltage applying part 3 increases the maximum voltage from the initial voltage at the first measuring point and increases the reference time at the maximum voltage. After being maintained for a while, the test voltage lowered back to the initial voltage may be applied a plurality of times. In this process, the current measuring unit 4 may measure the test current multiple times according to the application of the test voltage to the first measurement point. Using this, the calculation module 51 may calculate a plurality of holding current change values for the first measurement point. Further, in a state in which the connection part 2 is in contact with the second measuring point, the voltage applying part 3 increases the maximum voltage from the initial voltage at the second measuring point and increases the maximum voltage at the maximum voltage for the reference time. After being maintained, the test voltage lowered back to the initial voltage may be applied a plurality of times. During this process, the current measuring unit 4 may measure the test current multiple times according to the application of the test voltage to the second measurement point. Using this, the calculation module 51 may calculate a plurality of holding current change values for the second measurement point.

In order to compare the holding current change values for the first measuring point and the holding current change values for the second measuring point, the oxide semiconductor thin film inspection apparatus 1 according to the present invention may include a comparator 6. can

The comparator 6 compares the first electrical characteristic value for the first measurement point with the first electrical characteristic value for the second measurement point. The comparator 6 may compare at least one of a calculated value, a distribution value, and an average value between the holding current change values at the first measurement point and the holding current change values at the second measurement point. The calculated value may mean a holding current change value calculated for each of the first measurement point and the second measurement point. In this case, the comparator 6 may compare holding current change values for the first measurement point and holding current change values for the second measurement point belonging to the same cycle. The scatter value is a value representing how concentrated the holding current change values are at the center of the reference value for each of the first measurement point and the second measurement point, and for each of the first measurement point and the second measurement point It can be calculated using the holding current change values of all times. The average value is an average value of the holding current change values for each of the first measurement point and the second measurement point, and the holding current change values of the entire number of times are used for each of the first measurement point and the second measurement point. can be calculated. The comparator 6 determines that, among the first measurement point and the second measurement point, the higher holding current change value has a lower oxygen partial pressure rate and oxygen deficiency (O ₂ defect) and a higher device mobility. can be judged to be

When any one of the first measuring point and the second measuring point is the oxide semiconductor thin film 100 of the reference specimen, the comparator 6 calculates the holding current change values for the first measuring point and the second measuring point. A GO/NO decision on the oxide semiconductor thin film 100 may be performed by comparing holding current change values at measurement points. When the first measurement point and the second measurement point are oxide semiconductor thin films 100 formed on two substrates to be inspected, the comparator 6 measures the holding current change values for the first measurement point. Relative quality evaluation between the oxide semiconductor thin films 100 formed on each of the two substrates may be performed through comparison between the current value and the holding current change values for the second measurement point. When the first measurement point and the second measurement point are different parts of the oxide semiconductor thin film 100 formed on one substrate to be inspected, the comparator 6 maintains the first measurement point. The uniformity of the oxide semiconductor thin film 100 formed on one substrate may be evaluated by comparing the current change values with the holding current change values for the second measurement point.

Meanwhile, the voltage applying unit 3 applies a test voltage for maintaining the maximum voltage for the reference time only when the holding current change value is calculated from among the first electrical characteristic values, and among the first electrical characteristic values When the section current change value and the comparison threshold voltage are calculated, the test voltage entering the falling section DS may be directly applied without maintaining the maximum voltage for the reference time. Even when the second electrical characteristic value is calculated, the voltage applying unit 3 may directly apply a test voltage entering the falling section DS without maintaining the maximum voltage for the reference time. The voltage applying unit 3 may apply a test voltage that maintains the maximum voltage for the reference time when calculating the section current change value, the comparison threshold voltage, and the second electrical characteristic value.

Next, referring to FIGS. 1 and 2, looking at the process of calculating the section current change value, the calculation module 51 converts a preset reference section from the falling section DS into a plurality of units according to a preset section voltage. It is divided into sections, and a section current change value in which the inspection current is changed for each unit section can be calculated. The reference section and the section voltage may be preset by an operator. The reference section and the section voltage may be obtained in advance through a preliminary inspection of a specimen having the same material, oxygen partial pressure, and the like of the oxide semiconductor thin film 100 to be inspected. Preferably, the reference period may be set as a period from the maximum voltage to a certain voltage.

For example, if the reference interval is 500V to 400V and the interval voltage is 20V, the calculation module 51 extracts unit intervals consisting of 500V to 480V, 480V to 460V, 460V to 440V, 440V to 420V, and 420V to 400V, , Section current change values in which the test current is changed for each unit section may be calculated by calculating the difference between the initial test current and the final test current for each unit section.

The calculation module 51 may calculate section current change values for the first measurement point and calculate section current change values for the second measurement point. In this case, the comparator 6 selects at least one of the maximum change value, the minimum change value, and the average change value between the section current change values for the first measurement point and the section current change values for the second measurement point. one can compare. The maximum change value may be obtained by extracting the largest value among section current change values for each of the first measurement point and the second measurement point. In this case, the comparator 6 may compare the maximum change value among the section current change values for the first measurement point and the maximum change value among the section current change values for the second measurement point. The minimum change value may be obtained by extracting the smallest value among section current change values for each of the first measurement point and the second measurement point. In this case, the comparator 6 may compare a minimum change value among section current change values for the first measurement point with a minimum change value among section current change values for the second measurement point. The average change value may be obtained by calculating an average value of section current change values for each of the first measurement point and the second measurement point. In this case, the comparator 6 may compare the average change value of the section current change values for the first measurement point with the average change value of the section current change values for the second measurement point. The comparator 6 may compare the section current change values for the first measurement point and the section current change values for the second measurement point in the same unit section. The comparator 6 may determine that, among the first measurement point and the second measurement point, the higher section current change value has a lower oxygen partial pressure rate and a lower oxygen deficiency and higher element mobility. .

When any one of the first measuring point and the second measuring point is the oxide semiconductor thin film 100 of the reference specimen, the comparator 6 calculates the section current change values for the first measuring point and the second measuring point. It is possible to perform a GO/NO decision on the oxide semiconductor thin film 100 through comparison between section current change values for measurement points. When the first measuring point and the second measuring point are oxide semiconductor thin films 100 formed on two substrates to be inspected, the comparator 6 determines the section current change values for the first measuring point. Relative quality evaluation between the oxide semiconductor thin films 100 formed on each of the two substrates may be performed through comparison between the current change values and the section current change values for the second measurement point. When the first measurement point and the second measurement point are different parts of the oxide semiconductor thin film 100 formed on one substrate to be inspected, the comparator 6 provides a section for the first measurement point. The uniformity of the oxide semiconductor thin film 100 formed on one substrate may be evaluated by comparing the current change values with the section current change values for the second measurement point.

Next, looking at the process of calculating the comparison threshold voltage with reference to FIGS. 1, 2, and 5, the calculation module 51 may calculate the threshold voltage (FVth) prior to calculating the comparison threshold voltage. there is. In order to calculate the threshold voltage (FVth), the calculation module 51 calculates the first test voltage and the first test voltage at the time when the test current increases to a predetermined increase value or more after the test current becomes larger than 0 in the rising section (US). The test current can be extracted. Further, the calculation module 51 may extract the measured second inspection current as a second inspection voltage increased by a unit voltage from the first inspection voltage is applied to the oxide semiconductor thin film 100 . The unit voltage and the rising value may be preset by an operator. The unit voltage and the rising value may be obtained in advance through a preliminary inspection of a specimen having the same material, oxygen partial pressure, and the like as the oxide semiconductor thin film 100 to be inspected.

When the first inspection voltage, the first inspection current, the second inspection current, and the inspection current are extracted, the calculation module 51 calculates a threshold voltage (FVth) corresponding to the inspection voltage when the inspection current is 0. ) can be calculated. In this case, the calculation module 51 may calculate the threshold voltage FVth using Equation 1 below.

Equation 1 is converted from an equation of a straight line connecting a measurement point for the first inspection voltage and the first inspection current and a measurement point for the second inspection voltage and the second inspection current. In Equation 1, a and b may be calculated through the operation of the calculation module 51 using Equations 2 and 3 below.

In Equations 2 and 3, V ₁ is the first inspection voltage, V ₂ is the second inspection voltage, I ₁ is the first inspection current, and I ₂ is the second inspection current. In Equation 3, a value calculated by the calculation module 51 using Equation 2 may be substituted. In Equation 3, the first inspection current and the first inspection voltage may be used instead of the second inspection current and the second inspection voltage.

Using Equations 1 to 3, the calculation unit 5 may calculate the threshold voltage FVth corresponding to the inspection voltage when the inspection current is 0, as shown in FIG. 5 . there is. In this case, the threshold voltage (FVth) may be a value corresponding to the voltage at the time when the current flows through the oxide semiconductor thin film 100.

By performing the calculation of the threshold voltage (FVth) N times (N is an integer greater than 2), the calculation module 51 can calculate N number of threshold voltages (FVth). In this case, the voltage applying unit 3 may apply a test voltage that is increased from the initial voltage to the maximum voltage and then lowered to the initial voltage N times. The current measuring unit 4 may measure the test current N times as the test voltage, which increases from the initial voltage to the maximum voltage and then decreases to the initial voltage, is applied. Through this, when N number of threshold voltages (FVth) are calculated, the calculation module 51 calculates the comparison threshold voltage by subtracting the second calculated threshold voltage (FVth) from the Nth calculated threshold voltage (FVth). can In this case, the reason for using the second threshold voltage FVth instead of the first calculated threshold voltage FVth is that the first calculated threshold voltage FVth initially applies a voltage to the oxide semiconductor thin film 100. This is because non-uniform results are derived by the charging and discharging of electrons. In consideration of this, the calculation module 51 uses the threshold voltage FVth calculated for the second time, and through this, reliability of the inspection result of the oxide semiconductor thin film 100 can be increased.

The calculation module 51 may calculate a comparison threshold voltage for the first measurement point and a comparison threshold voltage for the second measurement point. In this case, in a state where the connection part 2 is in contact with the first measuring point, the voltage applying part 3 increases from the initial voltage to the maximum voltage at the first measuring point and then lowers to the initial voltage again. The test voltage may be applied N times. In this process, the current measuring unit 4 may measure the inspection current N times as the inspection voltage is applied to the first measurement point. Using this, the calculation module 51 may calculate N threshold voltages FVth for the first measurement point and then calculate the comparison threshold voltage for the first measurement point. And, in a state where the connection part 2 is in contact with the second measuring point, the voltage applying part 3 increases from the initial voltage to the maximum voltage at the second measuring point and then lowers to the initial voltage again. The inspection voltage can be applied N times. During this process, the current measuring unit 4 may measure the inspection current N times as the inspection voltage is applied to the second measurement point. Using this, the calculation module 51 may calculate N threshold voltages FVth for the second measurement point and then calculate the comparison threshold voltage for the second measurement point. After that, the comparator 6 may compare the comparison threshold voltage for the first measurement point and the comparison threshold voltage for the second measurement point. The comparison unit 6 may determine that the comparison threshold voltage is higher among the first measurement point and the second measurement point as having a higher oxygen partial pressure and oxygen deficiency and a lower device mobility.

When any one of the first measurement point and the second measurement point is the oxide semiconductor thin film 100 of the reference specimen, the comparator 6 calculates the comparison threshold voltage for the first measurement point and the second measurement point. It is possible to perform a GO/NO decision on the oxide semiconductor thin film 100 through a comparison between the comparison threshold voltages for . When the first measurement point and the second measurement point are oxide semiconductor thin films 100 formed on two substrates to be inspected, the comparator 6 compares the comparison threshold voltage for the first measurement point with the Relative quality evaluation between the oxide semiconductor thin films 100 formed on each of the two substrates may be performed through comparison between the comparison threshold voltages at the second measurement point. When the first measurement point and the second measurement point are different parts of the oxide semiconductor thin film 100 formed on one substrate to be inspected, the comparator 6 compares the first measurement point with respect to the first measurement point. The uniformity of the oxide semiconductor thin film 100 formed on one substrate may be evaluated through comparison between the threshold voltage and the comparison threshold voltage for the second measurement point.

A process of calculating the total inspection current belonging to the second electrical characteristic value by the calculation module 51 will be described in detail with reference to FIGS. 1 and 3 .

The calculation module 51 calculates the total inspection current by extracting all inspection currents until the inspection voltage increases to the maximum voltage and then decreases to the initial voltage, and then sums all the extracted inspection currents. can

The calculation module 51 may calculate the total inspection current for the first measurement point and calculate the total inspection current for the second measurement point. In this case, the comparator 6 may compare the total inspection current for the first measurement point with the total inspection current for the second measurement point. The comparator 6 may determine that, among the first measurement point and the second measurement point, the one having the higher total test current has a lower oxygen partial pressure ratio and a lower oxygen deficiency and higher element mobility.

The calculation module 51 may calculate a plurality of total inspection currents for the first measurement point and calculate a plurality of total inspection currents for the second measurement point. In this case, in a state where the connection part 2 is in contact with the first measuring point, the voltage applying part 3 increases from the initial voltage to the maximum voltage at the first measuring point and then lowers to the initial voltage again. The test voltage may be applied multiple times. In this process, the current measuring unit 4 may measure the test current multiple times according to the application of the test voltage to the first measurement point. Using this, the calculation module 51 may calculate a plurality of total inspection currents for the first measurement point. And, in a state where the connection part 2 is in contact with the second measuring point, the voltage applying part 3 increases from the initial voltage to the maximum voltage at the second measuring point and then lowers to the initial voltage again. The test voltage may be applied multiple times. During this process, the current measuring unit 4 may measure the test current multiple times according to the application of the test voltage to the second measurement point. Using this, the calculation module 51 may calculate a plurality of total inspection currents for the second measurement point.

In this case, the comparator 6 may compare at least one of a maximum value, a minimum value, and an average value between the total inspection currents for the first measurement point and the total inspection currents for the second measurement point. The maximum value may be obtained by extracting the largest value among total inspection currents for each of the first measurement point and the second measurement point. In this case, the comparator 6 may compare a maximum value among total inspection currents for the first measurement point with a maximum value among total inspection currents for the second measurement point. The minimum value may be obtained by extracting the smallest value among total inspection currents for each of the first measurement point and the second measurement point. In this case, the comparator 6 may compare a minimum value among total inspection currents for the first measurement point with a minimum value among total inspection currents for the second measurement point. The average value may be obtained by calculating an average value of total inspection currents for each of the first measurement point and the second measurement point. In this case, the comparator 6 may compare the average value of the total inspection currents for the first measurement point with the average value of the total inspection currents for the second measurement point.

When any one of the first measurement point and the second measurement point is the oxide semiconductor thin film 100 of the reference specimen, the comparator 6 measures the total inspection current for the first measurement point and the second measurement point. A GO/NO decision may be performed on the oxide semiconductor thin film 100 through a comparison between the total inspection currents for the current. When the first measurement point and the second measurement point are oxide semiconductor thin films 100 formed on two substrates to be inspected, the comparator 6 calculates the total inspection current for the first measurement point and the first measurement point. Relative quality evaluation between the oxide semiconductor thin films 100 formed on each of the two substrates can be performed through comparison between the total inspection currents for the two measurement points. When the first measuring point and the second measuring point are different parts of the oxide semiconductor thin film 100 formed on one substrate to be inspected, the comparator 6 has a bayonet for the first measuring point. The uniformity of the oxide semiconductor thin film 100 formed on one substrate can be evaluated through comparison between the pre-current and the total inspection current for the second measurement point.

Referring to FIGS. 1 to 3 , the calculator 5 may include a decision module 52 .

The determination module 52 determines which one of the first electrical characteristic value and the second electrical characteristic value to be calculated. The determination module 52 may determine which one of the first electrical characteristic value and the second electrical characteristic value to be calculated according to characteristics such as chargeable capacity of the oxide semiconductor thin film 100 to be inspected. According to the determination result by the determination module 52, the calculation module 51 may calculate the first electrical characteristic value or the second electrical characteristic value using the test voltage and the test current. Therefore, the oxide semiconductor thin film inspection apparatus 1 according to the present invention evaluates the quality of the oxide semiconductor thin film 100 by calculating different electrical characteristic values according to the characteristics of the oxide semiconductor thin film 100 to be inspected. Data reliability can be increased.

The determination module 52 may determine which one of the first electrical characteristic value and the second electrical characteristic value to be calculated by reading previously stored thin film data of the oxide semiconductor thin film 100 . The thin film data may include at least one of thin film materials constituting the oxide semiconductor thin film 100, thin film forming conditions, thin film density, and chargeable capacity. When the substrate 200 on which the oxide semiconductor thin film 100 is formed is supported on the stage, the determination module 52 can read thin film data of the oxide semiconductor thin film 100 through a reader (not a reader). . The reader is capable of reading codes such as QR Code and Bar Code. The code may be displayed on the substrate 200 or a carrier (not shown) on which the substrate 200 is seated. The determination module 52 may receive thin film data from a carrier (not shown) that carries the substrate 200 on which the oxide semiconductor thin film 100 is formed, and may read the received thin film data.

The determination module 52 applies the inspection voltage to the oxide semiconductor thin film 100 and determines which one of the first electrical characteristic value and the second electrical characteristic value to be calculated using a result of measuring the inspection current. can In this case, the determination module 52 compares the rising current value corresponding to the preset reference voltage value in the rising section US and the falling current value corresponding to the reference voltage value in the falling section DS, Depending on the comparison result, it may be determined which of the first electrical characteristic value and the second electrical characteristic value to be calculated. The reference voltage value may be preset by an operator. The reference voltage value may be set to an intermediate value having the same difference between the maximum value of the test voltage and the minimum value of the test voltage.

As described above, the oxide semiconductor thin film inspection apparatus 1 according to the present invention uses the determination module 52 even in a state in which there is no prior information on the oxide semiconductor thin film 100 to be inspected, and the corresponding oxide semiconductor thin film 100 ), the test can be performed by determining the electrical characteristic value. Therefore, the oxide semiconductor thin film inspection apparatus 1 according to the present invention can improve the versatility of performing inspections on various oxide semiconductor thin films 100 .

As shown in FIG. 2 , the determination module 52 may determine to calculate the first electrical characteristic value when the rising current value is greater than the falling current value. Accordingly, the calculation module 51 may calculate at least one of the holding current change value, the section current change value, and the comparison threshold voltage. The comparator 6 determines GO/NO for the oxide semiconductor thin film 100 by using at least one of the holding current change value, the section current change value, and the comparison threshold voltage, relative quality evaluation, and uniformity. etc. can be evaluated.

As shown in FIG. 3 , the determination module 52 may determine to calculate the second electrical characteristic value when the rising current value is smaller than the falling current value. Accordingly, the calculation module 51 may calculate the total inspection current. The comparator 6 may perform pass/fail determination, relative quality evaluation, and evaluation of uniformity of the oxide semiconductor thin film 100 using the total inspection current.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it is common in the technical field to which the present invention belongs that various substitutions, modifications, and changes are possible without departing from the technical spirit of the present invention. It will be clear to those who have knowledge of

1: oxide semiconductor thin film inspection device 2: connection part
3: voltage application unit 4: current measurement unit
5: calculation unit 6: comparison unit
100: oxide semiconductor thin film 200: substrate

Claims (15)

a connecting portion for contacting the oxide semiconductor thin film;
a voltage application unit connected to the connection unit and applying a test voltage, which is increased from a preset initial voltage to a preset maximum voltage and then lowered back to the initial voltage, to the oxide semiconductor thin film through the connection unit;
a current measuring unit measuring a test current according to the application of the test voltage to the oxide semiconductor thin film; and
While the test voltage increases from the initial voltage to the maximum voltage and then decreases to the initial voltage and is applied to the oxide semiconductor thin film, the test voltage applied by the voltage applying unit to the oxide semiconductor thin film and the current for each test voltage A calculator for calculating a first electrical characteristic value of the oxide semiconductor thin film or a second electrical characteristic value different from the first electrical characteristic value by using the test current measured by the measuring unit;
When the calculation unit calculates the second electrical characteristic value, the total inspection current obtained by adding all inspection currents until the inspection voltage increases from the initial voltage to the maximum voltage and then decreases to the initial voltage is calculated as the second electrical characteristic value. An oxide semiconductor thin film inspection apparatus comprising a calculation module for calculating a value. According to claim 1,
The calculation unit includes a determination module for determining which one of the first electrical characteristic value and the second electrical characteristic value is to be calculated;
The oxide semiconductor thin film inspection apparatus, characterized in that the calculation module calculates the first electrical characteristic value or the second electrical characteristic value using the inspection voltage and the inspection current according to the determination result by the determination module. According to claim 2,
The determination module reads previously stored thin film data for the oxide semiconductor thin film and determines which one of the first electrical characteristic value and the second electrical characteristic value to be calculated. According to claim 2,
The determination module determines the rising current value corresponding to a preset reference voltage value in an ascending section in which the inspection voltage increases from the initial voltage to the maximum voltage, and in a falling section in which the inspection voltage decreases from the maximum voltage to the initial voltage. Oxide semiconductor thin film inspection apparatus, characterized in that comparing the falling current value corresponding to the reference voltage value, and determining which one of the first electrical characteristic value and the second electrical characteristic value to be calculated according to the comparison result. According to claim 4,
The determining module determines that the first electrical characteristic value is calculated when the rising current value is greater than the falling current value, and the second electrical characteristic value is calculated when the rising current value is smaller than the falling current value. Oxide semiconductor thin film inspection apparatus, characterized in that for determining by calculating. According to claim 1,
When the voltage is increased from the initial voltage to the maximum voltage, the voltage application unit applies a test voltage that is lowered to the initial voltage after maintaining the maximum voltage for a predetermined reference time;
When the calculation module calculates the first electrical characteristic value, the initial test current at the time of reaching the maximum voltage and the time at which the reference time elapses while the maximum voltage is maintained from the time of reaching the maximum voltage An oxide semiconductor thin film inspection apparatus, characterized in that for calculating a holding current change value between final inspection currents as the first electrical characteristic value. According to claim 6,
A comparator for comparing a first electrical characteristic value for a first measurement point and a first electrical characteristic value for a second measurement point;
The voltage application unit applies the test voltage to the first measurement point multiple times, and applies the test voltage to the second measurement point multiple times;
The current measuring unit measures a test current according to the application of the test voltage to the first measurement point multiple times, and measures a test current multiple times according to the application of the test voltage to the second measurement point;
The calculation module calculates a plurality of holding current change values for the first measurement point and calculates a plurality of holding current change values for the second measurement point;
The comparison unit compares at least one of a calculated value, a distribution value, and an average value between the holding current change values for the first measurement point and the holding current change values for the second measurement point. inspection device. According to claim 1,
When calculating the first electrical characteristic value, the calculation module divides a predetermined reference period among a falling period in which the test voltage is lowered from the maximum voltage to the initial voltage into a plurality of unit periods according to a predetermined section voltage, , Oxide semiconductor thin film inspection apparatus, characterized in that for calculating the section current change values in which the test current is changed for each unit section as the first electrical characteristic value. According to claim 8,
A comparator for comparing a first electrical characteristic value for a first measurement point and a first electrical characteristic value for a second measurement point;
The comparison unit compares at least one of a maximum change value, a minimum change value, and an average change value between the section current change values for the first measurement point and the section current change values for the second measurement point. Oxide semiconductor thin film inspection device. According to claim 1,
The calculation module calculates a threshold voltage when calculating the first electrical characteristic value;
The calculation module,
Extracting a first inspection voltage and a first inspection current at a time point when the inspection current increases to more than a predetermined rising value after the inspection current is greater than 0 in a rising section in which the inspection voltage increases from the initial voltage to the maximum voltage;
Extracting a second inspection current measured as a second inspection voltage increased by a predetermined unit voltage from the first inspection voltage is applied;
A threshold voltage corresponding to the inspection voltage when the inspection current is 0 is calculated using the first inspection voltage, the first inspection current, the second inspection voltage, and the second inspection current. Semiconductor thin film inspection equipment. According to claim 10,
The calculation module is Equation

The threshold voltage (FVth) is calculated using
In the above equation, a and b are each

class

Wherein V ₁ is the first inspection voltage, V ₂ is the second inspection voltage, I ₁ is the first inspection current, and I ₂ is the second inspection current. Device. According to claim 10 or 11,
The voltage application unit applies a test voltage that is increased from the initial voltage to the maximum voltage and then lowered to the initial voltage N times (N is an integer greater than 2),
The current measuring unit measures a test current N times as a test voltage is applied, which increases from the initial voltage to the maximum voltage and then decreases to the initial voltage again.
The calculation module, after calculating the N threshold voltages, calculates a comparison threshold voltage obtained by subtracting the second calculated threshold voltage from the Nth calculated threshold voltage as the first electrical characteristic value. Device. According to claim 10 or 11,
A comparator for comparing a first electrical characteristic value for a first measurement point and a first electrical characteristic value for a second measurement point;
The voltage applying unit applies a test voltage that is increased from the initial voltage to the maximum voltage and then lowered to the initial voltage N times (N is an integer greater than 2) to the first measuring point, and then to the second measuring point. Applying a test voltage that increases from an initial voltage to the maximum voltage and then lowers to the initial voltage N times;
The current measurement unit measures the test current N times as a test voltage, which increases from the initial voltage to the maximum voltage and then decreases to the initial voltage, is applied to the first measurement point, N times, and then measures the initial voltage at the second measurement point. Measuring the test current N times as the test voltage, which is increased to the maximum voltage and then lowered to the initial voltage, is applied,
After calculating N threshold voltages for the first measurement point, the calculation module calculates a comparison threshold voltage obtained by subtracting the second calculated threshold voltage from the Nth calculated threshold voltage, and calculates a threshold voltage for the second measurement point. After calculating N voltages, a comparison threshold voltage is calculated by subtracting the second calculated threshold voltage from the Nth calculated threshold voltage,
The comparison unit compares the comparison threshold voltage for the first measurement point and the comparison threshold voltage for the second measurement point. delete According to claim 1,
A comparison unit for comparing a second electrical characteristic value for a first measurement point and a second electrical characteristic value for a second measurement point;
The voltage application unit applies the test voltage to the first measurement point multiple times, and applies the test voltage to the second measurement point multiple times;
The current measuring unit measures a test current according to the application of the test voltage to the first measurement point multiple times, and measures a test current multiple times according to the application of the test voltage to the second measurement point;
The calculation module calculates a plurality of total inspection currents for the first measurement point and calculates a plurality of total inspection currents for the second measurement point;
The comparison unit compares at least one of a maximum value, a minimum value, and an average value between total inspection currents for the first measurement point and total inspection currents for the second measurement point.

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