JP2009265058A - Tft array inspection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make uniform the collection efficiency of secondary electrons of a secondary electron detector within an electron beam scanning region. <P>SOLUTION: A voltage to be applied to a collecting electrode is changed instead of a prescribed fixed voltage according to the scanning position of an electron beam to heighten collection efficiency at a position at which the collection efficiency of secondary electrons is lowered and make uniform the collection efficiency of secondary electrons within the scanning region. A TFT array inspection apparatus 1 includes: an electron beam source (an electron gun part 2) for discharging an electron beam; a deflecting electrode 4 for performing scanning over a substrate by deflecting the electron beam; a deflection power supply 7 for applying a deflecting voltage for the deflecting electrode; a secondary electron detector 9 for detecting secondary electrons; the collecting electrode 10 provided for a preceding stage of the secondary electron detector; and a collecting electrode power supply 8 for applying a collecting electrode voltage to the collecting electrode 10. The collecting electrode power supply 8 changes the collecting electrode voltage to be applied to the collecting electrode 10 according to the scanning position of the electron beam within an electron beam scanning region 22 and thereby makes uniform the collection efficiency of secondary electrons within the scanning region. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a TFT array inspection apparatus used for inspecting a TFT array substrate used for a liquid crystal display, an organic EL display, and the like, and more particularly, a TFT for detecting a defect of a substrate by measuring the potential of a sample using an electron beam. The present invention relates to a secondary electron collecting electrode that collects secondary electrons in an array inspection apparatus.

  An inspection method using a potential contrast is known as a technique for measuring the potential of a sample without contact. According to this potential contrast, the potential of the sample can be measured by measuring the energy of secondary electrons emitted from the sample surface by irradiating the sample with an electron beam.

  There has been proposed a TFT inspection apparatus that performs inspection by non-contact measurement by applying the above-described inspection method using potential contrast in inspection of defective pixels on a TFT array substrate. In this TFT array inspection apparatus, a predetermined voltage is applied to the TFT substrate by a signal obtained by irradiating an electron beam to a TFT array substrate used for a liquid crystal display or an organic EL display and measuring secondary electrons generated from the TFT substrate. Is applied, and a defective cell such as a short circuit is determined based on the measurement result. For example, Patent Documents 1, 2, and 3 are known as such TFT array inspection apparatuses.

  FIG. 4 is a diagram for explaining the outline of a conventional TFT array inspection apparatus 101. As shown in FIG. The TFT array inspection apparatus 101 squeezes the electron beam generated by the electron gun unit 102 with the condenser lens 103, and then irradiates the TFT array substrate 130 placed on the substrate mounting table 106 through the objective lens 105.

  The incident electron beam 121 is deflected by the deflection electrode 104 provided between the condenser lens 103 and the objective lens 105, and scans on the TFT array substrate 130. The incident electron beam 121 is deflected by a deflection voltage applied by the deflection power source 107. The incident electron beam 121 scans the electron beam scanning region 122 two-dimensionally on the TFT array substrate 130 by scanning the incident electron beam 121 by the deflection electrode 104 and moving the substrate mounting table 106.

  The TFT array substrate 130 emits secondary electrons 123 when irradiated with the incident electron beam 121. The secondary electron detector 109 detects the emitted secondary electrons 123. The detection signal detected by the secondary electron detector 109 is amplified by the amplifier 111 and then displayed on the image display 112, for example.

The secondary electron detector 109 includes a collecting electrode 110 that collects the secondary electrons 123 at the front stage. A constant positive fixed voltage is applied to the collecting electrode 110 from the collecting electrode power supply 108, and thereby the emitted secondary electrons 123 are efficiently collected by the secondary electron detector 109.
Japanese Patent Laid-Open No. 11-265678 (FIGS. 2 and 20) Japanese Unexamined Patent Publication No. 2000-3142 (FIGS. 1, 5, 29) JP 2004-228431 A

  In the conventional TFT array substrate inspection apparatus, a constant voltage is applied to the secondary electron collecting electrode provided in the front stage of the secondary electron detector. In the configuration in which the voltage applied to the secondary electron electrode is a fixed voltage, if the electron beam scanning region 122 is expanded (for example, 40 mm or more), the collection efficiency of the secondary electrons is not constant in the scanning region. Even when secondary electrons having a uniform intensity are emitted from the line scanning region 122, there arises a problem that a difference in secondary electron intensity occurs between the central portion and the peripheral portion of the scanning region.

  FIG. 5 is a diagram for explaining the relationship between the scanning region and the secondary electron collection efficiency. FIG. 5A shows an example of the scanning region of the electron beam, and FIG. 5B shows one direction of the scanning region. The relationship between the position of (x direction) and secondary electron collection efficiency is shown.

  According to FIG. 5B, the secondary electron collection efficiency is lower than the secondary electron collection efficiency near the center in the x-direction scanning range. Therefore, even if secondary electrons are emitted uniformly from the electron beam scanning region, there is a difference in the amount of secondary electrons incident on the secondary electron detector, and there is a difference in detected secondary electron intensity. Become.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above problems and make the secondary electron collection efficiency of the secondary electron detector uniform within the electron beam scanning region.
It is another object of the present invention to compensate for a decrease in secondary electron collection efficiency at the end of the electron beam scanning region.

  The TFT array inspection apparatus according to the present invention changes the voltage applied to the collection electrode according to the scanning position of the electron beam instead of a fixed voltage, thereby reducing the collection efficiency of secondary electrons. The collection efficiency is increased, and the collection efficiency of secondary electrons in the scanning region is made uniform.

  The TFT array inspection apparatus of the present invention is a TFT array inspection apparatus that inspects a TFT array by detecting secondary electrons obtained by scanning an electron beam on a substrate. An electron beam source that emits an electron beam, A deflection electrode that deflects a line and scans the substrate, a deflection power source that applies a deflection voltage to the deflection electrode, a secondary electron detector that detects secondary electrons, and a front stage of the secondary electron detector A collecting electrode and a collecting electrode power source for applying a collecting electrode voltage to the collecting electrode are provided.

  The collection electrode power supply of the present invention changes the collection electrode voltage applied to the collection electrode in accordance with the scanning position of the electron beam in the electron beam scanning region. When the scanning position of the electron beam is a position where the collection efficiency of secondary electrons decreases, the collection electrode voltage is compensated by increasing the collection electrode voltage applied to the collection electrode. As a result, the collection efficiency of secondary electrons in the scanning region is made uniform.

  The collecting electrode power supply of the present invention applies a relatively high collecting electrode voltage when the electron beam scans the periphery of the scanning region, and relatively low collecting electrode voltage when the electron beam scans the central portion of the scanning region. Apply.

  In one configuration in which the collection electrode voltage is changed according to the scanning position of the electron beam in the scanning region, the collection electrode power source changes the collection electrode voltage in synchronization with the deflection voltage of the deflection power source. Thereby, the collecting electrode voltage can be changed in accordance with the scanning position of the electron beam in the electron beam scanning region.

  According to the TFT array inspection apparatus of the present invention, the secondary electron collection efficiency of the secondary electron detector can be made uniform in the electron beam scanning region. In addition, it is possible to compensate for a decrease in secondary electron collection efficiency at the end of the electron beam scanning region.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic view for explaining the configuration of a TFT array inspection apparatus according to the present invention. Here, the configuration of the TFT array inspection apparatus shown in FIG. 4 will be described as an example.

  The TFT array inspection apparatus 1 irradiates the electron beam generated from the electron gun unit 2 with the condenser lens 3 and then irradiates the TFT array substrate 30 placed on the substrate mounting table 6 through the objective lens 5. The electron gun unit 2 includes, for example, a wellate filament unit 2a that emits thermoelectrons and an anode 2b that extracts the emitted thermoelectrons to the TFT array substrate 30 side.

  The incident electron beam 21 is deflected by the deflection electrode 4 provided between the condenser lens 3 and the objective lens 5 and scans on the TFT array substrate 30. A deflection voltage is applied to the deflection electrode 4 from the deflection power source 7, and by changing the deflection voltage, the incident electron beam 21 is scanned while changing the degree of deflection of the incident electron beam 21 by the deflection electrode 4.

  The incident electron beam 21 scans the electron beam scanning region 22 two-dimensionally on the TFT array substrate 30 by scanning the incident electron beam 21 by the deflection electrode 4 and moving the substrate mounting table 6.

  The TFT array substrate 30 emits secondary electrons 23 by irradiation of the incident electron beam 21. The secondary electron detector 9 detects the emitted secondary electrons 23. After the detection signal detected by the secondary electron detector 9 is amplified by the amplifier 111, it is displayed on the image display 112, for example, and defect detection is performed by signal processing. In FIG. 1, a signal processing unit that performs defect detection is not shown. The secondary electron detector 9 includes a collecting electrode 10 that collects the secondary electrons 23 at the front stage. By applying a collecting electrode voltage from the collecting electrode power supply 8 to the collecting electrode 10, the emitted secondary electrons 23 are efficiently collected by the secondary electron detector 9.

  The collection electrode power supply 8 makes the collection electrode voltage applied to the collection electrode 10 variable. The collection electrode power supply 8 receives a deflection voltage signal from the deflection power supply 7 and changes the collection electrode voltage in synchronization with the deflection voltage.

  The collecting electrode power supply 8 prepares in advance a voltage pattern that changes along the scanning direction, changes the collecting electrode voltage in accordance with this voltage pattern, and applies it to the collecting electrode 10. The voltage pattern has a voltage characteristic in which the voltage on the peripheral side of the scanning region is relatively high and the voltage in the central portion is relatively low. For example, at the scanning position in the x direction, the voltage characteristics are such that the voltage at both ends in the x direction of the scanning region is relatively high and the voltage at the center is relatively low.

  The voltage characteristics of the collecting electrode power supply 8 can be a voltage pattern that changes linearly, or a voltage pattern that changes non-linearly. In the non-linear voltage pattern, for example, a voltage pattern that changes in a curve or a voltage pattern that changes in a staircase pattern can be used.

  The collection electrode power supply 8 records these voltage patterns in, for example, a recording means (not shown), reads out the applied voltage pattern, changes the voltage in synchronization with the deflection voltage sent from the deflection power supply 7, and applies it to the collection electrode 10. To do.

  Since the secondary electrons 23 taken into the secondary electron detector 9 change depending on the potential of the collecting electrode 10, the secondary electron collecting efficiency can be changed by changing the collecting electrode voltage applied to the collecting electrode 10. At this time, by changing the collection electrode voltage in synchronization with the deflection voltage, the collection electrode voltage of the collection electrode 10 and the secondary electron collection efficiency can be changed according to the scanning position of the electron beam.

  The collection electrode voltage is increased at the periphery of the scanning region where the collection efficiency of secondary electrons is reduced. The voltage compensation of the collection electrode voltage makes the collection efficiency uniform over the entire scanning region, and prevents the signal intensity of the detection signal detected by the secondary electron detector 9 from being lowered when the peripheral portion of the scanning region is scanned.

  Hereinafter, an example in which the collection electrode voltage is changed in synchronization with the deflection electrode voltage will be described with reference to FIGS. FIG. 2 shows an example in which the collecting electrode voltage is changed linearly, and FIG. 3 shows an example in which the collecting electrode voltage is changed non-linearly, showing an example in which the collecting electrode voltage is changed and a stepwise changing example. Yes. Here, scanning in the x direction will be described.

  In FIG. 2A, the horizontal axis represents the scanning position in the x direction, and the vertical axis represents the deflection electrode voltage. When a deflection electrode voltage is applied to the deflection electrode 4, the incident electron beam 21 irradiated from the electron gun unit 2 is deflected by an electric field formed by the deflection electrode 4. The magnitude of deflection depends on the magnitude of the deflection electrode voltage applied to the deflection electrode 4, and the scanning position of the incident electron beam 21 on the TFT array substrate 30 moves in the x direction as the deflection electrode voltage increases. Both ends in the x direction in FIG. 2A correspond to the end portions in the x direction of the scanning range.

  In FIG. 2B, the horizontal axis represents the scanning position in the x direction, and the vertical axis represents the collection electrode voltage. The collection electrode power supply 8 receives a signal synchronized with the deflection electrode voltage from the deflection power supply 7 and changes the collection electrode voltage applied to the collection electrode 10. Here, as shown in FIG. 2B, within the scanning range, the collecting electrode voltage at both ends is set high, the collecting electrode voltage at the central portion is set low, and the interval is changed linearly. . The absolute value of the collecting electrode voltage is determined by various conditions such as the characteristics of the secondary electron detector 9 and the positional relationship between the secondary electron detector 9 and the TFT array substrate 30.

  As shown in FIG. 2B, by setting the collecting electrode voltage on the end side of the scanning range high and setting the collecting electrode voltage in the central part low, the scanning region in which the collection efficiency of secondary electrons decreases is reduced. The collection electrode voltage in the peripheral portion is increased, thereby making the collection efficiency of the entire scanning region uniform. In FIG. 2C, the horizontal axis indicates the scanning position in the x direction, and the vertical axis indicates the secondary electron collection efficiency. The broken line in FIG. 2 (c) shows the secondary electron collection efficiency when the collecting electrode voltage is constant regardless of the scanning position in the x direction, and the solid line in FIG. 2 (c) shows the FIG. 2 (b). Both the secondary electron collection efficiencies are schematically shown when the collection electrode voltage shown in FIG. As shown by the solid line secondary electron collection efficiency in FIG. 2C, the collection electrode voltage is changed to increase the collection electrode voltage at the periphery of the scan area where the collection efficiency of the secondary electrons is reduced. The overall collection efficiency can be made uniform.

  3A, similarly to FIG. 2A, the horizontal axis indicates the scanning position in the x direction, and the vertical axis indicates the deflection electrode voltage.

  3B and 3C, the horizontal axis indicates the scanning position in the x direction, and the vertical axis indicates the collection electrode voltage. The collection electrode power supply 8 receives a signal synchronized with the deflection electrode voltage from the deflection power supply 7 and changes the collection electrode voltage applied to the collection electrode 10.

  In the scanning electrode, the collecting electrode voltage shown in FIG. 3B is set so that the collecting electrode voltage at both ends is set high and the collecting electrode voltage at the center is set low, and the interval is changed in a curved line. In addition, the collection electrode voltage shown in FIG. 3C is set so that the collection electrode voltage at both ends is set high and the collection electrode voltage at the center portion is set low within the scanning range, and the interval is changed stepwise. Yes.

  The absolute value of the collecting electrode voltage is determined by various conditions such as the characteristics of the secondary electron detector 9 and the positional relationship between the secondary electron detector 9 and the TFT array substrate 30.

  As shown in FIG. 3B and FIG. 3C, the collection efficiency of secondary electrons is set by setting the collection electrode voltage at the end of the scanning range high and setting the collection electrode voltage at the central portion low. The collection electrode voltage at the periphery of the scanning region where the decrease in the voltage is increased, thereby making the collection efficiency of the entire scanning region uniform.

  The collecting electrode voltage characteristic changing linearly as shown in FIG. 2B, the collecting electrode voltage characteristic changing like a curve shown in FIG. 3B, and the collecting electrode voltage changing like a step shown in FIG. 3C. Which collection electrode voltage characteristic is used to change the collection electrode voltage is selected according to the characteristics of the secondary electron detector and the spatial conditions such as the arrangement of the secondary electron detector and the TFT array substrate. At the same time, each collector electrode voltage characteristic is set.

  According to the TFT array inspection apparatus of the present invention, the following effects can be obtained in addition to the effect of making the secondary electron collecting efficiency uniform over the entire scanning region.

  The S / N of the scanning image of secondary electrons can be improved, and the inspection performance of the TFT array inspection apparatus can be improved.

  In the configuration including a plurality of electron guns, the secondary electron intensity at the boundary portion of the scanning region of each electron gun can be made uniform, and erroneous detection can be reduced.

  Since the electron beam scanning area can be expanded, the number of electron guns can be reduced.

  By expanding the scanning area of the electron beam, the inspection time can be shortened.

  The present invention can be applied to a repair device that repairs a detected defect in addition to detecting the presence or absence of a defect on a substrate and detecting a defect type.

It is the schematic for demonstrating the structure of the TFT array test | inspection apparatus of this invention. It is a figure for demonstrating the example of a deflection electrode voltage applied to the deflection electrode of this invention. It is a figure for demonstrating the example of a deflection electrode voltage applied to the deflection electrode of this invention. It is a figure for demonstrating the outline of the detection part used for the conventional TFT array test | inspection apparatus. It is a figure for demonstrating the relationship between a scanning area | region and secondary electron collection efficiency.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... TFT array inspection apparatus, 2 ... Electron gun part, 2a ... Wehnelt filament part, 2b ... Anode, 3 ... Condenser lens, 4 ... Deflection electrode, 5 ... Objective lens, 6 ... Substrate installation stand, 7 ... Deflection power supply, 8 ... Collection electrode power supply, 9 ... Secondary electron detector, 10 ... Collection electrode, 11 ... Amplifier, 12 ... Image display, 21 ... Incident electrode, 22 ... Electron beam scanning region, 23 ... Secondary electron, 30 ... TFT Array substrate 101 ... TFT array inspection device 102 ... Electron gun unit 102a ... Wehnelt filament unit 102b ... Anode 103 ... Condenser lens 104 ... Deflection electrode 105 ... Objective lens 106 ... Substrate mounting table 107 ... Deflection power supply 108... Collection electrode power supply 109. Secondary electron detector 110. Collection electrode 111 111 Amplifier 112 Image display 121 Incident electrode 12 ... electron beam scanning area, 123 ... secondary electrons, 130 ... TFT array substrate.

Claims (3)

In a TFT array inspection apparatus that inspects a TFT array by detecting secondary electrons obtained by scanning an electron beam on a substrate,
An electron beam source that emits an electron beam;
A deflection electrode that deflects the electron beam to scan on the substrate;
A deflection power source for applying a deflection voltage to the deflection electrode;
A secondary electron detector for detecting secondary electrons;
A collecting electrode provided in front of the secondary electron detector;
A collecting electrode power source for applying a collecting electrode voltage to the collecting electrode;
The TFT array inspection apparatus, wherein the collection electrode power source changes a collection electrode voltage applied to the collection electrode in accordance with a scanning position of the electron beam in an electron beam scanning region.   The collecting electrode power supply applies a relatively high collecting electrode voltage when the electron beam scans the periphery of the scanning region, and applies a relatively low collecting electrode voltage when the electron beam scans the central portion of the scanning region. The TFT array inspection apparatus according to claim 1, wherein:   The collection electrode power supply changes the collection electrode voltage in accordance with the scanning position of the electron beam in the electron beam scanning region by changing the collection electrode voltage in synchronization with the deflection voltage of the deflection power supply. The TFT array inspection apparatus according to claim 1 or 2.

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