JP2006324124A - Electron beam generating device and tft array substrate inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically control the beam current of an electron beam irradiated from a filament to a constant value, and to control the beam current to the constant value without stopping a production line in a TFT array substrate inspection device incorporated in the production line. <P>SOLUTION: In this electron beam generating device 1 which emits the electron beam from the filament by thermionic emission, filament current control means 4, 5 to control a filment current flowing in the filament 3 are provided, and the beam current is controlled to the constant value by detecting the beam current of the electron beam and feeding back the detected value to the filament current control means. The filament current control means 5 more effectively control the beam current of the electron beam to the constant value by feeding back the detected value of the beam current irradiated toward the TFT array substrate 10 from the filament 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electron beam generator for generating an electron beam from a filament, and a TFT array substrate inspection apparatus for inspecting a TFT array substrate with an electron beam, and more particularly to automatic control of an electron beam current.

  The TFT array substrate inspection device drives the TFT substrate with a defect detection signal pattern, and as a result, detects the ITO voltage generated on the TFT substrate by the intensity of secondary electrons generated by electron beam irradiation, and determines the quality of the entire array. is doing.

  In such a TFT array substrate inspection apparatus, the beam current of the electron beam applied to the TFT array substrate needs to be constant in order to make a good determination of the quality of the TFT array substrate. It varies depending on various factors such as the resistance of the filament generating the beam.

  In the TFT array substrate inspection apparatus, adjustment of the beam current is usually performed manually as necessary.

  On the other hand, the applicant of the present invention has proposed a filament lighting power supply circuit in which the filament current and the emission current do not exceed the set values by making the emission current that the filament emits thermoelectrons constant. .

  FIG. 4 is a block diagram for explaining the outline of the filament lighting power supply circuit 101. The filament lighting power supply circuit 101 includes an inner loop composed of a filament 103, a filament current monitor 104, and a filament lighting circuit 102, and an outer loop composed of a filament 103, an emission current monitor 105, a CPU 106, and a filament lighting circuit 102 on the outer side. The control circuit is configured by the two control systems, and the filament current is monitored and fed back to the lighting circuit. The filament current is controlled to the set value, and at the same time, the emission current is monitored and the emission current is kept constant by CPU processing. By controlling so that the excess current of the filament is suppressed (see Patent Document 1).

  In general, since the filament has a low electrical resistance in a room temperature state, the filament current rises rapidly at the time of lighting of the filament, and the filament current becomes stable when the filament is heated to increase the electrical resistance. When the filament current becomes stable, the emission current is also stabilized. Therefore, the emission current can be controlled to be constant by detecting and feeding back the emission current.

In addition, in this emission current control, since it takes time for the filament temperature to rise, there is a problem that the emission current is insufficient at the start-up of the power supply and the filament current exceeds the set value, causing damage to the filament. It has been proposed that the emission current and the filament current are controlled to set values by monitoring the current and the filament current and fed back to the filament lighting power supply circuit to solve the problems at the time of starting up the power supply.
JP 2000-77020 A

  Since the TFT array substrate inspection apparatus is an apparatus used in a production line on the premise of automatic operation, automatic adjustment is also required for substrate inspection of the TFT array substrate. Accordingly, automatic adjustment is also required for the electron beam generator provided in the TFT array substrate inspection apparatus. However, as described above, the conventional electron beam generator must manually adjust the beam current. There is a problem that the inspection apparatus needs to be in an off-line state with respect to the production line, and the production line must be temporarily stopped.

  In addition, it is conceivable to apply a technique for controlling the emission current to be constant by feeding back the emission current in a steady state, as described in the above-mentioned document, to the electron beam generator.

  However, in the TFT array substrate inspection apparatus, the beam current of the electron beam applied to the TFT array substrate is required to be constant, whereas in the conventionally proposed technique, the electrons actually applied to the TFT array substrate are required. Since the control is performed so that the emission current emitted from the filament is constant, not the beam current of the beam, there is a problem in terms of stability of the beam current.

  This is because in the TFT array substrate inspection apparatus, the ratio of the current amount of the beam current of the electron beam irradiated from the filament to the TFT array substrate and the current amount of the emission current emitted from the filament is about 1: 1000. is there. Since the amount of emission current is 1000 times as large as the amount of beam current, the variation in beam current is about 1/1000 relative to the variation in emission current. Therefore, when the fluctuation of the beam current is controlled based on the fluctuation of the emission current having an amount 1000 times that of the beam current, the sensitivity of the beam current will be about 1/1000. This is because it is impossible to control the current, and stable control becomes difficult.

  SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-described problems and to automatically control the beam current of an electron beam emitted from a filament to a constant value. In a TFT array substrate inspection apparatus incorporated in a production line, The purpose is to perform constant value control of the current without stopping the production line.

  In order to solve the above-described object, the present invention provides an electron beam generator for emitting an electron beam from a filament by thermionic emission, comprising filament current control means for controlling the filament current flowing through the filament, and the beam current of the electron beam is reduced. The beam current is controlled to a constant value by detecting and feeding back the detected value to the filament current control means.

  The filament current control means feeds back a detection value of the beam current irradiated from the filament toward the TFT array substrate, thereby more effectively performing a constant value control of the beam current of the electron beam.

  The electron beam generator of the present invention includes a current detection plate for detecting a beam current as a mechanism for detecting the beam current. This current detection plate detects the beam current, detects the amount of beam current, and feeds it back to the filament current control means. The filament current control means obtains a difference between the current amount of the fed back beam current and a preset reference current, calculates a correction value for correcting the beam current from the difference current amount, and calculates the correction value. To increase or decrease the filament current. Thereby, the beam current is automatically controlled to a constant value.

  In another aspect of the electron beam generator of the present invention, in addition to the configuration in which the beam current of the electron beam is detected and fed back, the emission current due to the electron beam emission and the filament current flowing in the filament are detected, The detected value is fed back to the filament current control means to suppress fluctuations in the electron beam due to fluctuations in the emission current and filament current.

  The electron beam generator of the present invention can be applied to a TFT array substrate inspection apparatus. In this TFT array substrate inspection apparatus, an electron beam is emitted from the electron beam generator to the TFT array substrate, and is generated by this electron beam irradiation. The secondary electron intensity is detected by a secondary electron detector, and the TFT array substrate is inspected by the detected secondary electron intensity.

  The TFT array substrate inspection apparatus according to the present invention includes an electron beam generator, a current detection plate that detects a beam current, an electron beam deflecting unit that deflects the electron beam between the TFT array substrate and the current detection plate, and a filament. It is set as the structure provided with the filament current control means which controls the flowing filament current.

  The electron beam deflection means deflects the electron beam emitted from the filament and irradiates the current detection plate, and the current detection plate detects the irradiated beam current. The filament current control means uses the detection value of the current detected by the current detection plate as a beam current feedback value, and controls the beam current to a constant value.

  The interval at which the electron beam deflecting means irradiates the current detection plate with the electron beam can be arbitrarily determined in units of a TFT array substrate, in addition to a preset time unit.

  The beam current adjustment can be automated by performing the operations of the current beam deflecting means and the filament current control means according to a preset schedule, and the beam current amount of the electron beam is detected by the electron beam deflecting means. The electron beam is simply deflected and shaken on the current detection plate, and the deflection time of the electron beam is shorter than the substrate inspection time of the TFT array substrate. This can be done without stopping while in the operating state.

  According to the electron beam generator of the present invention, the beam current of the electron beam irradiated from the filament can be automatically controlled to a constant value.

  In addition, according to the TFT array substrate inspection apparatus of the present invention, it is possible to suppress the occurrence of erroneous defect detection accompanying the fluctuation of the beam current by keeping the beam current constant.

  In addition, in the TFT array substrate inspection apparatus incorporated in the production line, a constant value control of the beam current can be performed without stopping the production line.

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

  FIG. 1 is a block diagram for explaining a schematic configuration of an electron beam generator 1 according to the present invention.

  The electron beam generator 1 causes a filament current to flow from the filament power supply circuit 2 to the filament 3 and heats the filament 3 to emit thermoelectrons. The electron beam 21 emitted from the filament 3 is irradiated to the object. In the TFT array substrate inspection apparatus, this object is the TFT array substrate 10 to be inspected, and defects in the TFT array substrate 10 are detected by detecting secondary electrons obtained by irradiating the electron beam 21 of the TFT array substrate 10. Inspection can be performed.

  The filament power supply circuit 2 is a power supply circuit that supplies a filament current to the filament 3, and this filament current is controlled by the filament current control circuit 5 so as to have a constant value.

  The filament current control circuit 5 of the present invention controls the beam current to be constant by feeding back the beam current of the electron beam 21 irradiated from the filament 3 toward, for example, the TFT array substrate 10.

  The amount of current flowing through the filament power supply circuit 2 is the amount of emission current corresponding to the sum of all electrons emitted from the filament 3, and this emission current includes the beam current irradiated to the TFT array substrate 10. ing. The ratio of the current amount of the beam current and the current amount of the emission current is about 1: 1000, and the filament power supply circuit 2 of the present invention feeds back the current amount of the beam current instead of the current amount of the emission current, The amount of beam current is directly controlled.

  In order to feed back the amount of beam current to the filament power supply circuit 2, the electron beam generator 1 of the present invention includes a beam current monitor 4 that detects an electron beam irradiated from the filament 3. The beam current monitor 4 does not normally monitor the electron beam 21, but takes in the electron beam 21 at a predetermined interval such as a predetermined time unit or a lot unit of the TFT array substrate and detects the current amount of the beam current to detect the filament current. Feedback is made to the control circuit 5.

  FIG. 2 is a block diagram for explaining a schematic configuration of the electron beam generator 1 of the present invention and the TFT array substrate inspection apparatus 20 having the electron beam generator.

  The TFT array substrate inspection device 20 applies a predetermined pattern of inspection voltage to the TFT array substrate 10, and irradiates the TFT array substrate 10 with the electron beam 21 a from the filament 3 of the electron beam generator 1. The secondary electrons 22 obtained from the above are detected by the secondary electron detector 23, and the detected signal is processed by the defect inspection means 24, whereby the TFT array substrate 10 is inspected for defects.

  Therefore, the TFT array substrate inspection apparatus 20 irradiates the TFT array substrate 10 with the electron beam 21a during the inspection.

  Filament current is supplied to the filament 3 from the filament power supply circuit 2. The filament power supply circuit 2 includes a power supply 2a and a current adjustment circuit 2b connected to the power supply 2a. The current adjustment circuit 2b adjusts the amount of current flowing through the filament 3. The filament current control circuit 5 adjusts the amount of filament current by the current adjustment circuit 2b.

  The filament current control circuit 5 detects the beam current irradiated from the filament 3 and feeds back the current amount. The configuration example shown in FIG. 2 feeds back the current amount of the beam current to the filament current control circuit 5, and also feeds back the filament current and the emission current flowing in the filament 3, and based on the fluctuations in these current amounts. The filament current is controlled to be a constant value.

  Feedback of the current amount of the beam current can be performed by the beam current monitor 4. The beam current monitor 4 includes a current detection plate 4a for detecting the beam current irradiated from the filament 3, an amplifier 4b for detecting the beam current by the current detection plate 4a and amplifying the beam current, and an analog beam current amplified by the amplifier 4b as a digital signal. The A / D converter 4c that converts the current to the beam current is compared with a preset reference current value to obtain a difference, and the beam current is determined based on the difference. A calculation means 4e for calculating a correction value for returning to the current amount and a D / A converter 4f for converting the correction value calculated by the calculation means 4e into an analog signal are provided.

  The filament current control circuit 5 calculates the beam current monitor 4 and inputs a correction value as a beam current feedback value to control the current adjustment circuit 2b of the filament power supply circuit 2.

  As a mechanism for irradiating the current detection plate 4a with the electron beam 21a from the filament 3 instead of the TFT array substrate 10, the electron beam generator 1 of the present invention can use the deflecting means 6 for deflecting the electron beam. The deflection means 6 is a means for deflecting the electron beam 21b emitted from the filament 3 toward the current detection plate 4a. For example, the lens system 6a and the lens control means 6b provided in the scanning means of the TFT array substrate inspection apparatus 20 are provided. Can be used.

  The lens 6a included in the TFT array substrate inspection apparatus 20 may be configured to provide a dedicated lens for directing the electron beam 21b toward the current detection plate 4a in addition to the scanning lens system that scans the electron beam on the TFT array substrate 10. Good.

  The amount of filament current fed back to the filament current control circuit 5 can be obtained from a voltage value obtained by connecting the reference resistor 2 c to the filament 3. The amount of emission current to be fed back can be obtained from the voltage value obtained by the resistor 2d from the current of the power source 2a.

  FIG. 3 is a schematic diagram for explaining a configuration example of the filament power supply circuit 2 and the filament current control circuit 5 of the present invention.

  The filament power supply circuit 2 is configured by connecting a current adjusting element 2b such as a power transistor to a power supply 2e and connecting it to one end of the filament 3, and grounding the other end of the filament 3 via a reference resistor 2c. The current adjusting element 2 b adjusts the amount of current that flows through the filament 3 according to the control signal of the filament current control circuit 5. For example, in the case of a power transistor, the amount of current is adjusted by applying a control signal to the gate.

  The filament current control circuit 5 includes an integration circuit formed by an operational amplifier 5d and a capacitor 5e. The voltage corresponding to the beam current correction, the emission current feedback, and the filament current are input to the input terminal of the integration circuit via the resistors 5a, 5b, and 5c, respectively, and these current fluctuations are added. The integrated value is output to the current adjustment element 2b as a control signal.

  Here, the correction amount of the beam current is a value obtained by the beam current monitor 4 shown in FIG. 2 and is a correction value for returning the fluctuation of the beam current to the reference value and keeping it constant. Is a reference value of the current flowing through the power supply 2a of the filament power supply circuit.

  According to the electron beam generator of the present invention, the beam current is read at regular intervals, the difference between the detected value and a preset reference value is obtained, and the current amount of the beam current is corrected by this difference. Thus, the beam current can be controlled to be constant by setting the reference value.

  When this electron beam generator is used in a TFT array substrate inspection apparatus, the beam current can be read at a time that does not affect the substrate inspection of the TFT array substrate. The beam current can always be kept constant without stopping the production line.

  The electron beam generator of the present invention is not limited to a TFT array substrate inspection apparatus, but can be applied to a processing apparatus using an electron beam in addition to an inspection apparatus using an electron beam.

It is a block diagram for demonstrating schematic structure of the electron beam generator 1 of this invention. It is a block diagram for demonstrating schematic structure of the electron beam generator of this invention, and the TFT array board | substrate test | inspection apparatus which has this electron beam generator. It is the schematic for demonstrating the example of a structure of the filament power supply circuit and filament current control circuit of this invention. It is a block block diagram for demonstrating the outline of a filament lighting power supply circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electron beam generator, 2 ... Filament power supply circuit, 2a ... Power supply, 2b ... Current adjustment circuit, 2c ... Reference resistance, 2d, 2d ... Resistance, 2e ... Power supply, 3 ... Filament, 4 ... Beam current monitor, 4a ... Current detection plate, 4b ... amplifier, 4c ... A / D converter, 4d ... reference current value, 4e ... calculation means, 4f ... D / A converter, 5 ... filament current control circuit, 5a, 5b, 5c ... resistance, 5d, operational amplifier, 5e, condenser, 6 ... deflection means, 6a ... lens, 6b ... lens control means, 10 ... TFT array substrate, 20 ... TFT array substrate inspection device, 21a, 21b ... beam current, 22 ... secondary electrons, DESCRIPTION OF SYMBOLS 23 ... Secondary electron detector, 24 ... Defect inspection means, 101 ... Filament lighting power supply circuit, 102 ... Filament lighting circuit, 103 ... Filament, 104 ... Filament current Nita, 105 ... emission current monitor, 106 ... CPU.

Claims (4)

In an electron beam generator for emitting an electron beam from a filament by thermionic emission,
Filament current control means for controlling a filament current flowing through the filament,
An electron beam generator comprising: detecting a beam current of the electron beam; and feeding back the detected value to the filament current control means to control the beam current to a constant value. In an electron beam generator for emitting an electron beam from a filament by thermionic emission,
Filament current control means for controlling a filament current flowing through the filament,
The beam current of the electron beam, the emission current due to the emission of the electron beam, and the filament current flowing in the filament are detected, and each detected value is fed back to the filament current control means to automatically control the beam current to a constant value. An electron beam generator. A current detection plate for detecting the beam current;
This current detection plate detects the beam current, detects the amount of beam current,
The filament current control means calculates a correction value for correcting the beam current from a difference between a current amount of the beam current and a reference current, and increases or decreases the filament current by the correction value. 3. The electron beam generator according to 2. A TFT that irradiates a TFT array substrate with an electron beam from an electron beam generator, detects the intensity of secondary electrons generated by the electron beam irradiation with a secondary electron detector, and inspects the TFT array substrate with the secondary electron intensity In array substrate inspection equipment,
The electron beam generator is
A current detection plate for detecting the beam current;
An electron beam deflecting means for deflecting the electron beam between the TFT array substrate and the current detection plate;
Filament current control means for controlling the filament current flowing through the filament,
The current beam deflection means deflects the electron beam emitted from the filament and irradiates the current detection plate,
The current detection plate detects an irradiated beam current,
The TFT array substrate inspection apparatus, wherein the filament current control means controls the beam current to a constant value by using a detected value of the current detected by the current detection plate as a beam current feedback value.

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