JP2005189838A - Active matrix substrate, liquid crystal device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To establish an inspection technique of an active matrix substrate mounting a digital driver. <P>SOLUTION: There are provided a digital driver (330) for driving a data line which has a function capable of bringing an output terminal into a high impedance state, and a test circuit (340) of the data line which is arranged on an edge of the opposite side to the digital driver. The test circuit (340) has a bidirectional switch arranged at each of multiple data lines and a control means for controlling switching of the switch. By using the test circuit arranged at the opposite side of the data lines, even the presence of point defects can be determined in addition to the inspections such as disconnection of the data lines and digital driver output. Also, the circuit is dedicated to exclusive use for inspections, so that the circuit is extremely small and can be disposed in a dead space. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an inspection method for an active matrix substrate, an active matrix substrate, a liquid crystal device, and an electronic apparatus. In particular, a digital data line driver (digital signal is input and D / A conversion is performed on an analog signal on the substrate. The present invention relates to an inspection technique for an active matrix substrate of a type in which a driver that outputs and drives a data line thereby (hereinafter referred to as a digital driver) is formed.

  In recent years, active research has been conducted on an active matrix substrate with a built-in driver in which driving circuits (drivers) for scanning lines and data lines are formed on a substrate, and a liquid crystal display device using the same. Such an active matrix substrate is manufactured using, for example, a low-temperature polysilicon technique.

  In order to actually put a product using the above-described active matrix substrate into the market, it is necessary to accurately inspect non-defective / defective products after the substrate formation and before the panel assembly from the viewpoint of reliability assurance. .

  According to the study by the present inventor, the above-described inspection is roughly classified into basic inspection such as output capability check of the driver itself and detection of disconnection of the data line, characteristics of the switching elements (TFT, MIM, etc.) constituting the pixel, It is necessary to inspect point defects in the active matrix portion such as storage capacitor leakage characteristics.

  In the case of a digital driver for driving a data line (that is, a digital data line driver), a method of collectively driving at a predetermined timing with a focus on the ease of storing (storing) digital data (line sequential driving method) Is adopted.

  A display device incorporating such a digital line sequential drive driver has not been put into practical use at present, and it is unclear how to perform such a highly reliable inspection.

  Therefore, one of the objects of the present invention is to establish an inspection technique for an active matrix substrate on which a digital driver is mounted so that a highly reliable substrate, display device, or the like can be put on the market.

  The present invention for solving the above-described problems has the following configuration.

(1) The present invention described in claim 1 includes a plurality of scanning lines and a plurality of data lines,
A digital driver for driving the plurality of data lines, having a function capable of setting an output terminal in a high impedance state;
A switch element connected to one scan line and one data line;
A capacitor connected to each of the switch elements;
An inspection circuit provided at an end of the data line opposite to the digital driver,
The inspection circuit includes a bidirectional switch provided for each of the plurality of data lines, and control means for controlling opening and closing of the switch.

  Since the digital driver of the data line has a D / A converter in the output unit, the signal once output cannot be read again through a common path to inspect the active matrix unit (measurement of point defects). .

  However, in the invention of this claim, since the inspection circuit is provided at the opposite end of the data line to the digital driver, the data line is driven by the digital driver to obtain the capacity (storage capacity) of the active matrix portion. A signal can be written, and the written signal can be read out via an inspection circuit. Therefore, it is possible to determine the presence or absence of point defects in the active matrix portion.

  If the output of the digital driver (A / D conversion output) is on when reading the signal using the inspection circuit, the defect determination based on the signal read from the storage capacitor is not guaranteed, so the point defect determination In the basic signal acquisition step, it is necessary to turn off the output of the inspection circuit (high impedance). Therefore, the digital driver according to the present invention has a function capable of setting the output to a high impedance state.

  In addition, since the inspection circuit is a circuit used for inspection, high-speed operation like that of a digital driver is unnecessary, and for example, it is only necessary to have a minimum function that can be inspected. Therefore, in the invention of this claim, the digital driver has a configuration including a bidirectional switch (for example, an analog switch) and control means for controlling opening and closing of the switch. Since the circuit configuration is simple and high operating characteristics are not required, the size of the transistor can be small, which is suitable for space saving. Therefore, it is possible to mount the inspection circuit on the active matrix substrate.

  The meaning of “inspection circuit” is a circuit used mainly for inspection, and means that it does not have a function of driving a data line like a data line driver. It does not mean that it is used or includes a configuration that can be used for purposes other than inspection.

(2) The present invention as set forth in claim 2 is characterized in that, in claim 1,
The elements constituting the inspection circuit are manufactured by the same manufacturing process together with the elements constituting the digital driver.

  A digital driver and a test circuit are manufactured by the same process on one active matrix substrate. For example, it can be manufactured using low temperature polysilicon thin film transistor (TFT) technology.

(3) The present invention described in claim 3 provides the method according to claim 1 or 2,
The digital driver includes a switch at an output portion thereof, and the output terminal is set to a high impedance state by opening the switch.

  In order to put the output of the digital driver into a high impedance state, a switch is provided in the output section.

(4) The present invention according to claim 4 is the method according to any one of claims 1 to 3,
The digital driver includes any one of a capacitance division type D / A converter, a resistance division type D / A converter, and a PWM type D / A converter.

  2 shows an example of a D / A converter that can be mounted on an active matrix substrate of the present invention.

  For example, the capacitance division type D / A converter is provided with a switch for each weighted capacitor, and generates a converted voltage by combining the charge of each capacitor with the coupling capacitor by switching control of the switch.

  The resistance division type D / A converter, for example, selectively extracts a voltage divided by resistance by controlling opening and closing of a switch interposed in the output path, and generates a converted voltage.

  The PWM D / A converter generates a conversion voltage by controlling, for example, the ON time of a switch connected to a voltage source whose voltage value changes with time (ramp wave) according to a digital data value.

(5) The present invention described in claim 5 provides the method according to any one of claims 1 to 4.
The control means of the inspection circuit scans the bidirectional switch dot-sequentially.

  The inspection circuit has, for example, a dot sequential data line scanning mechanism using a shift register or the like, and performs inspection by reading out data in a dot sequential manner.

(6) The present invention as set forth in any one of claims 1 to 5,
When the number of the bidirectional switches is M (M is a natural number of 2 or more), the control means of the inspection circuit performs a collective drive of P bidirectional switches (P is a natural number). It is characterized by driving a total of M (M = P × Q) bidirectional switches by repeating (Q is a natural number) times.

  This is an inspection circuit of a different method from the dot sequential scanning.

(7) The present invention described in claim 7 is the method according to any one of claims 1 to 6,
At least a part of the inspection circuit is arranged in a space of the active matrix substrate that does not contribute to realization of essential functions such as image display.

  Since the inspection circuit has a small transistor size and a small occupation area as described above, at least a part of the inspection circuit is a space that does not contribute to the realization of an essential function such as image display of the active matrix substrate, that is, a so-called inspection circuit. It is also possible to arrange in a dead space. Therefore, the increase in size of the active matrix substrate and the liquid crystal display device can be suppressed.

(8) The present invention according to claim 8 is the invention according to claim 7,
The inspection circuit is arranged at a sealing position by a sealing material in a panel process.

  In the panel process, the position that will be sealed by the sealing material is a dead space that inevitably occurs in the active matrix substrate. An inspection circuit is arranged in this space to make effective use of the space.

(9) The present invention according to claim 9 is the invention according to any one of claims 1 to 8,
Each of the inspection circuit and the digital driver is divided into a plurality of parts on the active matrix substrate.

  In some cases, the dead space can be used more effectively by dividing the circuit. Further, the number of elements in one block is reduced by the amount of division, and a spacious layout design becomes possible. In addition, the operating frequency of a circuit that operates in series such as a shift register can be reduced by the amount of reduction in the number of elements.

(10) The present invention according to claim 10 is the invention according to claim 9,
The inspection circuit is divided into at least a first inspection circuit and a second inspection circuit, and the digital driver is divided into at least a first digital driver and a second digital driver,
The first digital driver and the first inspection circuit are arranged opposite to each other across the data line, and the second digital driver and the second inspection circuit are opposed to each other across the data line. Arranged,
In addition, the first digital driver and the second inspection circuit are disposed on the same side of the data line, and the second digital driver and the first inspection circuit are on the same side of the data line. It is arrange | positioned at the edge part, It is characterized by the above-mentioned.

  Each of the divided same-type circuits (the first circuit and the second circuit) is arranged on the opposite side via the data line.

  Since circuits are distributed above and below the surface of the active matrix substrate, it becomes easy to effectively use the dead space existing around the display area. In particular, since the dead space at the sealing position exists evenly (upper and lower) around the substrate, it is advantageous when the space is used effectively.

  Further, since the circuit is divided, the number of elements in one circuit block is reduced according to the number of divisions, and a layout with a margin can be realized. In addition, the operating frequency of a circuit that operates in series such as a shift register can be reduced by the amount of reduction in the number of elements.

(11) The present invention according to claim 11 is an inspection method of an active matrix substrate according to any one of claims 1 to 10,
Driving the data line by the digital driver to write a signal to the capacitor connected to the switch element;
Bringing the output of the digital driver into a high impedance state;
The signal written in the capacitor by the inspection circuit is read to obtain a basic signal as a basis for the inspection, and the active matrix portion is inspected based on the acquired basic signal.

  This is a basic method for inspecting an active matrix portion using the active matrix substrate according to claim 1.

(12) The invention according to claim 12 is the invention according to claim 11,
Prior to execution of the steps according to claim 11, the digital driver itself is inspected and the data line is inspected for disconnection.

  Before the inspection of the active matrix portion, the output characteristics of the digital driver itself and the disconnection of the data line are inspected (preliminary inspection).

  In the above-described active matrix substrate of the present invention, the inspection circuit is provided opposite to the digital driver with the data line interposed therebetween, so that each data line is driven line-sequentially by the digital driver only once, for the scanning. If the inspection circuit is scanned line-sequentially or dot-sequentially in synchronization and a signal transmitted via the data line is received, a preliminary inspection can be easily performed depending on the presence / absence of reception and the amplitude of the received signal.

(13) The invention according to claim 13 is the invention according to claim 11,
The step of inspecting the active matrix portion based on the acquired basic signal includes a step of considering a two-dimensional distribution in the active matrix portion of the characteristic of the basic signal.

  In many cases, the basic signal acquired for the inspection of the active matrix portion contains a considerable amount of noise. Therefore, the relative inspection should be performed in consideration of not only the absolute value of the signal characteristics but also the abnormal distribution of the signal characteristics (for example, there are specific parts that show abnormalities in comparison with the surroundings). Is effective.

(14) The present invention according to claim 14 is the invention according to claim 11,
The step of inspecting the active matrix portion based on the acquired basic signal includes a step of comparing the acquired basic signal with a sample signal prepared in advance.

  In this method, inspection is performed by comparison with a sample signal.

  (15) The present invention according to claim 15 is a liquid crystal device configured by using the active matrix substrate according to any one of claims 1 to 10.

  This is a highly reliable liquid crystal device that has passed a predetermined inspection.

  (16) The present invention according to claim 16 is an electronic apparatus configured using the liquid crystal device according to claim 15.

  Since the reliability of the liquid crystal device is high, the reliability of the electronic device is also improved.

  Next, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
(1) Outline of Inspection System and Its Operation FIG. 1 is a diagram showing an overall configuration of an apparatus for executing an inspection method for an active matrix substrate of the present invention.

  In this embodiment mode, a case where an active matrix substrate (hereinafter referred to as a TFT substrate) in which a switching element in a pixel portion is formed of a thin film transistor (TFT) is inspected will be described.

  In FIG. 1, a TFT substrate tester 100 includes a test system controller 10 that comprehensively controls an inspection operation, a timing generator 20 that generates various timing signals, a data generator 30 that outputs inspection data, and a high-speed operation. An amplifier and an A / D converter 50 and a data analyzer 50 that performs a predetermined analysis using data output from the A / D converter as input.

  The full auto prober 200 has a prober controller 210 and a DUT board 220 that serves as an interface for various signals.

  The TFT substrate 300 includes an active matrix portion, a scanning line driver 320, a digital data line driver with an output off function (hereinafter simply referred to as a digital data line driver) 330, and an inspection circuit 340. The output off function is a function that can force the output to a high impedance state. At the time of inspection, a probe of a full auto prober (inspection terminal, not shown in FIG. 1) is connected to a predetermined terminal (not shown in FIG. 1) exposed on the TFT substrate 300.

  Then, under the overall control of the test system controller 10, timing signals and inspection data are output from the timing generator 20 and the data generator 30 in the TFT substrate tester 100. These are sent to the TFT substrate 300 via the DUT board 220 of the full auto prober 200.

  The timing signal is input to the scanning line driver 320, the digital data line driver 330, and the inspection circuit 340 in the TFT substrate 300, respectively, and the inspection data is input to the digital data line driver 330.

  After a predetermined inspection process (details of the inspection operation will be described later), an analog signal (hereinafter referred to as a basic signal) that is the basis of the acquired inspection is output from the inspection circuit 340. And sent to the TFT tester 100 via the DUT board 220 in the full auto prober 200. Then, it is amplified and A / D converted by the high-speed amplifier and A / D converter 50 in the TFT tester 10, and the converted data is input to the data analyzer 50 and subjected to a predetermined analysis.

(2) Outline of Circuit Configured on TFT Substrate 300 FIG. 2 shows a specific configuration example of the TFT substrate 300 shown in FIG. In order to enable the inspection using the inspection system shown in FIG. 1, the TFT substrate 300 also needs to have some requirements.

  In other words, it is an essential requirement that the digital data line driver has an output off function (a function for setting the output in a high impedance state) and that each pixel portion has a capacitance in the substrate state.

  As shown in FIG. 2, the digital data line driver 330 built in the TFT substrate 300 includes an m-bit shift register 400, u-bit data input terminals (D1 to Du, and u × m switches SW1 to SW1. SWum, u × m-bit latch A (reference number 410) and latch B (reference number 420), and m-bit D / A converter 430. In this embodiment, D / A converter 430 outputs Has an off function.

  In addition, the scanning line driver 320 includes an n-bit shift register 322.

The active matrix section includes a plurality of data lines X1 to Xm, a plurality of scanning lines Y1 to Yn, a TFT (M1) disposed at the intersection of each scanning line and each data line, and a storage capacitor ( Holding capacity) C _S1 . The presence of the storage capacitor C _S1 makes it possible to measure point defects in the substrate state.

In a state of the TFT substrate is not present liquid crystal capacitance C _LC, for convenience and for ease of understanding, FIG. 2, are described the liquid crystal capacitance C _LC. Further, the end of the storage capacitor C _S1 opposite to the connection end to the TFT (M1) is held at a common potential V _COM .

(3) Specific Configuration Example (3-1) Configuration of Storage Capacitor Section FIGS. 9A and 9B show the configuration of one pixel of the active matrix section in FIG.
FIG. 9A shows a layout configuration, and FIG. 9B shows an equivalent circuit thereof. FIG. 30A shows a cross-sectional structure of the device along the line AA in FIG.

  In FIG. 9A, reference numbers 5000 and 5100 indicate scanning lines, and reference numbers 5200 and 5300 indicate data lines. Reference numeral 5400 is a capacitance line, and reference numeral 5500 is a pixel electrode.

As apparent from FIG. 30A, the gate insulating film 5510 and the extension 5505 of the drain of the TFT and the capacitor line 5400 formed at the same time using the process of forming the scanning line (gate electrode) 5000 The same insulating film 5520 is formed, and an interlayer insulating film 5530 is formed between the capacitor line 5400 and the pixel electrode 5500, and thereby a storage capacitor (C _S1 ) 5410 is formed. Reference numeral 5600 is an opening (a region through which light is transmitted), and K1 and K2 are contact regions.

The storage capacitor (C _S1 ) can also be formed by a configuration as shown in FIGS. FIG. 30B shows a cross-sectional structure of the device along the line AA in FIG.

  In FIG. 9, the capacitor line is provided separately, but in FIG. 10, the storage capacitor is formed by overlapping the extension of the drain of the TFT with the adjacent scanning line (gate electrode).

  That is, as shown in FIGS. 10A and 30B, the same insulating film 5130 as the gate insulating film 5120 is formed between the drain extension 5700 made of polysilicon and the adjacent scanning line (gate electrode) 5100. In addition, an interlayer insulating film 5140 is formed between the adjacent scanning line 5100 and the pixel electrode 5500, thereby forming a storage capacitor 5420. In FIG. 10 (a), the same reference numerals are assigned to the same parts as in FIG. 9 (a).

(3-2) Configuration of D / A Converter As the m-bit D / A converter 430 in FIG. 2, the configuration shown in FIGS. 11 to 14 can be used.

  When inspecting point defects, it is necessary to turn off the output of the D / A converter after writing a signal to the capacitor of the pixel portion. Therefore, all of the D / A converters of FIGS. It has an output off function (function that puts the output in a high impedance state). This will be specifically described below.

Capacitance Division D / A Converter A D / A converter 430 in FIG. 11 is a capacitance division D / A converter with an output off function. This converter stores charges in weighted capacitors (binary load capacitors) C1 to C8, and when the 8-bit input data D1 to D8 is “1”, the corresponding switch (SW20 to SW28). Is closed to cause charge transfer between each of the weighted capacitors (C1 to C8) and the coupling capacitor C30, and a conversion voltage corresponding to 8-bit input data D1 to D8 is generated at the output terminal _VOUT . It is something to be made. In FIG. 11, switches (SW1 to SW8) are reset switches for capacitors C1 to C8, and V0 is a reset voltage. The switch C40 is a reset switch for the coupling capacitor C30.

The switch control circuit 6000 is provided for forcibly opening the switches SW20 to SW28 and setting the output terminal _VOUT to a floating state (high impedance state).

  FIG. 12 shows a specific configuration of the switch SW20. The switch SW20 includes a transfer gate including an nMOS transistor M10, a pMOS transistor M20 and an inverter INV1, and an nMOS transistor M30 connected in series to the transfer gate. The switch control circuit 6000 sets the output corresponding to the input data D1 to a high impedance state by turning off the nMOS transistor M30. Similarly, other switches corresponding to other input data can be in a high impedance state.

  11 and 12, the switch control circuit 6000 is provided independently. In FIG. 12, a dedicated transistor (M30) for providing high impedance is provided. However, the present invention is not limited to this. For example, in FIGS. 11 and 12, the input data D1 to D8 are forcibly fixed to “0” by using a reset signal or the like, so that the switch (SW20) in FIG. 11 or the transfer gate (M10, M20 in FIG. 12). ) Can be turned off to place the output in a high impedance state.

Resistance-dividing D / A Converter A D / A converter 430 shown in FIG. 13 selects a divided voltage obtained from each common connection point of resistors R1 to R8 connected in series by opening / closing control of the switches SW100 to SW108. To obtain a converted output _VOUT .

  The opening / closing of the switches SW100 to SW108 is determined by the output of the decoder 7000. The switches SW100 to SW108 (switch group 7100) are collectively opened under the control of the switch control circuit 7200, and the output can be set to a high impedance state.

PWM D / A Converter A D / A converter 430 shown in FIG. 14 generates a pulse signal having a pulse width corresponding to an input data value by a PWM circuit 7502, and the switch 7506 is turned on (closed) by the pulse width. The conversion output V _OUT is obtained. Reference numeral 7504 is a ramp wave power source, and reference numeral 7400 is a latch circuit for temporarily storing image data. In addition, the switch 7506 can be forcibly opened to set the output to a high impedance state under the control of the switch control circuit 7508.

(3-3) Configuration of Inspection Circuit As the inspection circuit 340 shown in FIG. 2, those shown in FIGS. 15A, 15B, and 16 can be used. The term “inspection circuit” means that it is used for inspection and does not aim to drive a data line like a data line driver, and includes a configuration used for other purposes or the entire circuit. Is not excluded to use for any other purpose.

The inspection circuit 342 in FIG. 15A includes analog switches SW _{X1 to} SW _Xm using MOS transistors corresponding to the data lines _{X1 to Xm} , and the analog switches SW _{X1 to} SW _Xm are connected to the shift register 7600. Are scanned in a dot-sequential manner, and basic signals that are the basis of inspection are sequentially obtained from the output terminal T _OUT . The basic signal is sent to the DUT board 220 in the full auto prober 200.

In FIG. 15B, two analog switches (SW _{X1 to} SW _Xm ) are driven by one output of the shift register 7602, and basically a dot sequential scanning method is adopted. This is common with FIG. Since two analog switches are driven simultaneously, the number of bits (number of stages) of the shift register is m / 2 bits. The basic signal is obtained from two terminals T _OUT1 and T _OUT2 .

The inspection circuit 342 in FIG. 16 employs a method different from the dot sequential scanning. That is, when driving the m analog switches SW _{X1 to} SW _Xm , p analog switches are collectively driven, and the driving is repeated q times, so that a total of m (m = p × q ) Analog switch driving method.

  The switch control circuit 7300 sequentially turns on the control lines G1 to Gq, and a basic signal is simultaneously obtained from each of the output lines L1 to Lp each time each control line is turned on once.

  None of the inspection circuits described above require the drive capability of the data line, and there is no requirement for high-speed driving for image display. Therefore, the transistor size may be small and basically operable. You only need to have the minimum ability. Therefore, the occupied area can be made extremely small and can be formed on the TFT substrate.

  FIG. 3 shows the size of the MOS transistor at the output stage of the D / A converter and the size of the MOS transistor constituting the inspection circuit 342 when the D / A converter 430 is a driver that can also be driven in a dot sequential manner. It is a figure shown in comparison.

That is, the channel width (W) of the MOS transistor M ₂₀₀ that constitutes the D / A converter 430 that can also be dot-sequentially driven is required to be at least 1000 μm, whereas the channel of the MOS transistor M ₃₀₀ that constitutes the inspection circuit 342 The width (W) may be 100 μm or less. In other words, the transistor size of the inspection circuit may be 1/10 or less.

  Since the size of the transistor is small and the occupied area is small in this way, at least a part of the inspection circuit 342 is in a space that does not contribute to the realization of the essential functions of the TFT substrate such as image display, that is, a so-called dead space. It can also be arranged. Therefore, the enlargement of the TFT substrate or the liquid crystal display device can be suppressed.

  For example, as shown in FIG. 4, the inspection circuit 342 can be disposed at a sealing position by a sealing material (sealing material) in the panel process of the TFT substrate. In FIG. 4, the cross-sectional structure of the completed liquid crystal display device is drawn for easy understanding.

In FIG. 4, reference numeral 500 is a glass substrate, reference numeral 510 is a SiO ₂ film, reference numeral 520 is a gate insulating film, reference numerals 530 and 540 are interlayer insulating films, and reference numerals 522 and 524. Is a source / drain layer, and reference numeral 526 is a gate electrode.

The MOS transistor M ₃₀₀ constituting the inspection circuit is arranged in a sealing region A1 by a sealing material (sealing material) 550. The sealing position by the sealing material is a dead space that inevitably occurs in the active matrix substrate, and the space can be effectively utilized by arranging the inspection circuit in this space.

  In FIG. 4, reference numeral 560 is a counter substrate, reference numerals 570 and 572 are alignment films, and reference numeral 574 is a liquid crystal.

(4) TFT substrate inspection procedure (4-1) Outline As shown in FIG. 5, the TFT substrate inspection is roughly divided into signal line disconnection detection and D / A converter output inspection process (preliminary inspection process). , Step 600) and a point defect inspection process (step 610).

  The basics of the active matrix substrate (FIGS. 1 and 2) of the present embodiment in which the disconnection of the signal lines and the output inspection of the D / A converter (step 600) are provided with an inspection circuit facing the digital data line driver. This is a test that can be performed by a general configuration, and by turning on all the outputs of the digital data line driver 330 shown in FIGS. 1 and 2 and receiving the output by the test circuit 340, in principle, in one scan. Can be easily inspected.

  For example, when no output signal of the data line driver is transmitted via the data line, the data line is disconnected or the data line driver itself is defective. The point defect inspection process (step 610) will be described later.

(4-2) Specific Inspection Procedure FIG. 6 shows an example of a specific inspection procedure.

  In the flowchart of FIG. 6, a method of inspecting in order from the one with the shortest inspection time is adopted, and all necessary processes are inspected. However, the present invention is not limited to this, and it is possible to stop the subsequent inspection when a defect is found.

  Hereinafter, the inspection procedure of FIG. 6 will be described in order.

  First, the presence / absence of an uninspected TFT substrate is checked (step 700). If there is an uninspected TFT substrate, the substrate is aligned (attached) to the system of FIG. 1 (step 710), and the full auto prober 220 of FIG. Probing is performed (step 720).

  First, driver current consumption is measured (step 730). In this step, it is determined whether or not the consumption current flowing through the power supply of the data line and scanning line driver (and the inspection circuit) is in a normal range. If there is a short circuit between the power supplies, an excessive current flows, which can be determined.

  Next, the end pulse of the scanning line driver is measured (step 740). That is, a pulse is input to the first stage of the shift register, and it is determined whether the pulse is output from the last stage at a predetermined timing. Since it is a digital signal, it can be determined instantaneously.

  Next, the end pulse of the data line driver is measured as in the case of the scanning line driver (step 750).

  Next, a short circuit inspection of the data line (signal line) and the scanning line is performed (step 760).

  That is, all the outputs of the scanning driver are set to the high level, each switch of the inspection circuit is also turned on, and the current flowing from the scanning line driver to the inspection circuit is measured. If there is a short circuit between the wires, an excessive current will flow.

  Next, a disconnection inspection of the data line (signal line) and the scanning line is executed (step 770).

  That is, all the outputs of the digital driver are set to high level, and the switches of the inspection circuit are closed in order to detect a change in current. If there is a disconnection, the current that flows is reduced, so it can be determined.

  Next, the output of the D / A converter is measured (step 780).

  Before the point defect is inspected, all the outputs of the D / A converter are inspected. In this inspection, in order to increase the accuracy, it is desirable to check whether or not the output level is appropriate for signals of a plurality of gradations such as white, black, and halftone.

  Specifically, the voltage of the set level is output to all the data lines (signal lines), the output of the D / A converter is set in a high impedance state after a certain time, and each data line (signal line) is set using a test circuit. The voltage of is detected.

  Next, a point defect is measured (step 790).

  More specifically, the measurement of the point defect is performed by a procedure as shown in FIG. That is, first, all outputs of the digital data line driver are turned on, a voltage of a set level is output to all the data lines (signal lines), and a signal is written in the storage capacitor of the pixel portion (step 900). Next, the output of the D / A converter of the digital data line driver is set to a high impedance state (step 910). Next, scanning lines are selected one by one with the inspection circuit switch closed, and the amount of potential fluctuation for each pixel is detected (step 920). If necessary, detection is performed a plurality of times (step 930) and detection is performed with different writing conditions (step 940).

  If an abnormality (failure) is found in each of the above steps, a defective address is detected as necessary and used as basic data for pass / fail judgment (step 800 in FIG. 6).

  Since the basic data that is the basis of the inspection is obtained through the above steps, finally, the quality is determined based on the basic data (step 810 in FIG. 6).

  For example, as shown in FIG. 8, the pass / fail judgment is made by examining the two-dimensional distribution of the basic data on the TFT substrate surface, and examining whether there are any locations (singular points) that show extremely different values with respect to the surroundings. A comprehensive judgment is made by (step 960), examining abnormalities by comparison with sample data (step 970), and the like.

  Then, the above inspection process is sequentially performed on other uninspected chips (steps 820 and 830 in FIG. 6).

  As described above, according to the present embodiment, the non-defective product inspection of the active matrix substrate on which the digital data line driver is mounted can be performed with high accuracy in a short time.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIG.

  The feature of this embodiment is that the digital data line driver and the inspection circuit are divided into two parts in the vertical direction, and the circuits divided in the vertical direction are arranged in a complicated manner to form a compact configuration. is there.

  That is, as clearly shown in FIG. 17, the digital data line driver is divided into two parts, a first driver 8000A and a second driver 8000B. The configuration of the data line driver itself is the same as that in FIG. 2, but the number of bits of each driver is ½ of that in FIG.

  The inspection circuit is also divided into two parts, a first circuit 8100A and a second circuit 8100B. The first circuit 8100A is connected to even-numbered data lines (X2, X4... Xm), and the second circuit 8100B is connected to odd-numbered data lines (X1, X3... Xm−). 1). In FIG. 17, reference numbers S1, S2, S3, S4, Sm, and Sm-1 indicate analog switches, and reference numbers 8102 and 8104 indicate the structure of one stage of the shift register.

  By dividing the driver and the inspection circuit as in this embodiment, the following various effects can be obtained.

  That is, by dividing the driver and the inspection circuit, the number of elements constituting each circuit is halved, the occupied area is reduced accordingly, and elements can be arranged with a margin.

  Further, since the number of shift register stages is halved, the operating frequency can be halved, which is advantageous in terms of circuit design.

  Furthermore, the division of the circuit leads to the circuit being evenly arranged around the pixel portion, thereby enabling effective use of the dead space. For example, this is advantageous when utilizing the dead space directly under the sealing material (sealing material) described in FIG.

  In other words, the sealing material (sealing material) is provided so as to be in contact with the periphery of the substrate surface with an equal width so as not to give excessive stress to the substrate, and thus the circuit is divided and each circuit is provided. This is because the reduction in the number of elements helps increase the utilization efficiency of the dead space directly under the sealing material.

  Particularly, since the element size of the inspection circuit is smaller than the element size of the driver, the division of the inspection circuit further saves space, which is advantageous in layout design.

  FIG. 19 shows an arrangement example of inspection circuits and the like on the active matrix substrate (on the TFT substrate). FIG. 19 shows not only the layout of drivers and the like on the active matrix substrate, but also the vertical and horizontal cross sections of a liquid crystal panel manufactured using the TFT substrate.

  In FIG. 19, reference numeral 9100 is an active matrix substrate (TFT substrate), reference numerals 8000A and 8000B are digital data line drivers and inspection circuits, and reference numeral 320 is a scanning line driver. Reference numeral 8300 indicates a light shielding pattern, and the inside of the pattern is an active matrix portion (pixel portion). Reference numeral 8400 is a mounting terminal portion, reference numeral 9200 is a sealing material (sealing material), reference numeral 574 is a liquid crystal, and reference numeral 9000 is a counter substrate (color filter substrate).

  As apparent from FIG. 19, the scanning line driver, the data line driver, and the inspection circuit are all arranged by effectively using the dead space around the active matrix substrate. Therefore, it is suitable for effectively utilizing the dead space at the sealing position by the sealing material.

  The liquid crystal panel (active matrix substrate 9100) shown in FIG. 19 is manufactured through a cutting process as shown in FIG.

  In other words, in FIG. 18, an active matrix substrate (TFT substrate) 9100 and a counter substrate (color filter substrate) 9000 are bonded together by a large bonding method, and then cut to manufacture six panels. In FIG. 18, cutting lines (L10, L11, L30, L31, L32, L33) indicated by one-dot chain lines are lines that simultaneously cut the active matrix substrate and the counter substrate. In addition, cutting lines (L20, L21, indicated by dotted lines are lines that cut only the counter substrate.

(Third embodiment)
In this embodiment, a method for manufacturing a thin film transistor (TFT) on an active matrix substrate (a manufacturing method using a low-temperature polysilicon technique) will be described with reference to FIGS.

  20 to 26, a capacitor (capacitor) is also manufactured. Therefore, this process can be used not only in the manufacture of the inspection circuit and the shift register of the driver, but also in the case of manufacturing the capacity division type D / A converter of FIG.

Process 1
First, as shown in FIG. 20, a buffer layer 4100 is provided on a substrate 4000, and an amorphous silicon layer 4200 is formed on the buffer layer 4100.

Process 2
Next, as shown in FIG. 21, the entire surface of the amorphous silicon layer 4200 is irradiated with laser light and annealed to polycrystallize the amorphous silicon to form a polycrystalline silicon layer 4220.

Process 3
Next, as shown in FIG. 22, the polycrystalline silicon layer 4220 is patterned to form island regions 4230, 4240, and 4250. The island regions 4230 and 4240 are layers in which active regions (sources and drains) of MOS transistors are formed. The island region 4250 is a layer that serves as a pole of the thin film capacitor.

Process 4
Next, as shown in FIG. 23, a mask layer 4300 is formed, and phosphorus (P) ions are implanted only into the island region 4250 to reduce the resistance.

Process 5
Next, as shown in FIG. 24, a gate insulating film 4400 is formed, and TaN layers 4500, 4510, and 4520 are formed on the gate insulating film. The TaN layers 4500 and 4510 are layers serving as gates of MOS transistors, and the TaN layer 4520 is a layer serving as the other electrode of the thin film capacitor. Thereafter, a mask layer 4600 is formed, and phosphorus (P) is ion-implanted by self-alignment using the gate TaN layer 4500 as a mask to form an n-type source layer 4231 and drain layer 4232.

Step 6
Next, as shown in FIG. 25, mask layers 4700a and 4700b are formed, boron (B) is ion-implanted by self-alignment using the gate TaN layer 4510 as a mask, and a p-type source layer 4241 and drain layer 4242 are formed. Form.

Step 7
Thereafter, as shown in FIG. 26, an interlayer insulating film 4800 is formed, contact holes are formed in the interlayer insulating film, and electrode layers 4900, 4910, 4920, and 4930 made of ITO or Al are then formed. Although not shown in FIG. 26, electrodes are also connected to the TaN layers 4500, 4510, 4520 and the polycrystalline silicon layer 4250 through contact holes. Thereby, an n-channel TFT, a p-channel TFT and a MOS capacitor are completed.

  Manufacturing is facilitated by using a manufacturing process with a common process as described above, which is advantageous in terms of cost. In addition, since polysilicon has a much higher carrier mobility than amorphous silicon, it can operate at high speed, which is advantageous in terms of speeding up the circuit.

  In addition, since the non-defective product determination is reliably performed using the above-described inspection method, the reliability of the finished product can be extremely high, and therefore, a high-quality product can be introduced into the market.

  Although the low-temperature polysilicon TFT technology is used in the above manufacturing process, the manufacturing method is not necessarily limited to this. For example, if a predetermined operation speed of the circuit is guaranteed, a process using amorphous silicon can be used. In addition to the TFT, a two-terminal element such as MIM can also be used as the switching element of the pixel portion.

(Fourth embodiment)
In this embodiment, examples of a liquid crystal panel manufactured using the active matrix substrate of the present invention and an electronic device using the panel or the like will be described. Both are high-quality devices.

(1) Liquid crystal display device (FIG. 27)
The liquid crystal display device includes, for example, a backlight 2000, a polarizing plate 2200, a TFT substrate 2300, a liquid crystal 2400, a counter substrate (color filter substrate) 2500, and a polarizing plate 2600, as shown in FIG. In this embodiment mode, the driver circuit 2310 (and the inspection circuit) is formed over the TFT substrate 1300 as described above.

(2) Personal computer (FIG. 28)
A personal computer 1200 illustrated in FIG. 28 includes a main body 1204 provided with a keyboard 1202 and a liquid crystal display screen 1206.

(3) Liquid crystal projector (Fig. 29)
A liquid crystal projector 1100 shown in FIG. 29 is a projection type projector using a transmissive liquid crystal panel as a light valve, and uses, for example, a three-plate prism type optical system.

  In FIG. 29, in the projector 1100, the projection light emitted from the lamp unit 1102 of the white light source is divided into the three primary colors R, G, and B by a plurality of mirrors 1106 and two dichroic mirrors 1108 inside the light guide 1104. Are guided to the three liquid crystal panels 1110R, 1110G, and 1110B that display images of the respective colors. The light modulated by the respective liquid crystal panels 1110R, 1110G, and 1110B is incident on the dichroic prism 1112 from three directions. In the dichroic prism 1112, the red R and blue B lights are bent by 90 °, and the green G light travels straight, so that images of the respective colors are synthesized, and a color image is projected onto a screen or the like through the projection lens 1114.

  Other electronic devices to which the present invention can be applied include engineering workstations (EWS), pagers or mobile phones, word processors, televisions, viewfinder type or monitor direct view type video tape recorders, electronic notebooks, electronic desk calculators, cars Examples thereof include a navigation device, a POS terminal, and a device provided with a touch panel.

It is a figure which shows the whole structure of the apparatus for performing an example of the inspection method of the active matrix substrate of this invention. It is a figure which shows the structural example of the circuit mounted in the active matrix substrate of this invention. FIG. 3 is a diagram schematically showing a comparison between a size of a transistor constituting the D / A converter in FIG. 2 and a size of a transistor constituting the inspection circuit. It is sectional drawing of the principal part of a liquid crystal display device which shows the example which has arrange | positioned the test | inspection circuit under the sealing material. It is a flowchart which shows the outline | summary of one Example of the inspection method of the active matrix substrate of this invention. It is a flowchart for demonstrating the more concrete content of one Example of the inspection method of the active-matrix board | substrate of this invention. It is a flowchart which shows the content of the point defect measurement in FIG. 6 more concretely. It is a flowchart which shows the content of the necessity determination in FIG. 6 more concretely. (A) is a top view which shows an example of a structure of one pixel of an active matrix part, (b) is an equivalent circuit schematic of (a). (A) is a top view which shows the other example of a structure of one pixel of an active matrix part, (b) is an equivalent circuit schematic of (a). It is a figure for demonstrating the outline | summary of the structural example of the D / A converter of the capacity | capacitance division system which can be used by this invention. FIG. 12 is a diagram illustrating a circuit configuration example of a main part of the capacitance-division D / A converter of FIG. 11. It is a figure for demonstrating the outline | summary of the structural example of the D / A converter of the resistance division system which can be used by this invention. It is a figure for demonstrating the outline | summary of the structural example of the D / A converter of the PWM system which can be used by this invention. (A), (b) is a figure for demonstrating the outline | summary of an example of the test | inspection circuit shown by FIG. 1, FIG. 2, respectively. It is a figure for demonstrating the outline | summary of the other example of a structure of the test | inspection circuit shown by FIG. 1, FIG. It is a figure which shows the other structural example of the circuit mounted in the active matrix substrate of this invention. It is a figure which shows the position in the case of cut | disconnecting a glass substrate for manufacture of an active matrix substrate. It is a figure which shows an example of layouts, such as a scanning line drive circuit, a data line drive circuit, and an inspection circuit. It is a figure which shows the 1st process of an example of the manufacturing method of the active matrix substrate of this invention. It is a figure which shows the 2nd process of an example of the manufacturing method of the active matrix substrate of this invention. It is a figure which shows the 3rd process of an example of the manufacturing method of the active matrix substrate of this invention. It is a figure which shows the 4th process of an example of the manufacturing method of the active matrix substrate of this invention. It is a figure which shows the 5th process of an example of the manufacturing method of the active matrix substrate of this invention. It is a figure which shows the 6th process of an example of the manufacturing method of the active matrix substrate of this invention. It is a figure which shows the 7th process of an example of the manufacturing method of the active matrix substrate of this invention. It is a figure which shows the structure of the liquid crystal display device using the active matrix substrate of this invention. It is a figure which shows the structure of an example (laptop computer) of the electronic device using the active matrix substrate of this invention. It is a figure which shows the structure of the other example (liquid crystal projector) of the electronic device using the active matrix substrate of this invention. (A) is a figure which shows the cross-sectional structure which follows the AA line of the device shown by Fig.9 (a), (b) is the cross-sectional structure which follows the AA line of the device shown by Fig.10 (a). FIG.

Explanation of symbols

10 test system controller, 20 timing generator,
30 data generator, 40 high-speed amplifier, A / D converter,
100 active matrix substrate tester, 200 full auto prober 210 prober controller, 220 DUT board,
300 active matrix substrate, 310 active matrix section,
320 Scan Line Driver, 330 Digital Data Line Driver with Output Off Function 340 Inspection Circuit

Claims (16)

A plurality of scan lines and a plurality of data lines;
A digital driver for driving the plurality of data lines, having a function capable of setting an output terminal in a high impedance state;
A switch element connected to one scan line and one data line;
A capacitor connected to each of the switch elements;
An inspection circuit provided at an end of the data line opposite to the digital driver,
The inspection circuit includes a bidirectional switch provided for each of the plurality of data lines, and a control means for controlling opening and closing of the switch. In claim 1,
The active matrix substrate, wherein the elements constituting the inspection circuit are manufactured by the same manufacturing process together with the elements constituting the digital driver. In claim 1 or claim 2,
The digital driver includes a switch at an output portion thereof, and an open state of the output terminal is set to a high impedance state by opening the switch. In any one of Claims 1-3,
The digital driver includes any one of a capacitance division type D / A converter, a resistance division type D / A converter, and a PWM type D / A converter. In any one of Claims 1-4,
The active matrix substrate according to claim 1, wherein the control means of the inspection circuit scans the bidirectional switch dot-sequentially. In any one of Claims 1-4,
When the number of the bidirectional switches is M (M is a natural number of 2 or more), the control means of the inspection circuit performs a collective drive of P bidirectional switches (P is a natural number). An active matrix substrate characterized in that a total of M (M = P × Q) bidirectional switches are driven repeatedly (Q is a natural number). In any one of Claims 1-6,
At least a part of the inspection circuit is arranged in a space that does not contribute to realization of an essential function such as image display of the active matrix substrate. In claim 7,
An active matrix substrate, wherein the inspection circuit is disposed at a sealing position by a sealing material in a panel process. In any one of Claims 1-8,
An active matrix substrate, wherein the inspection circuit and the digital driver are each divided and arranged on the active matrix substrate. In claim 9,
The inspection circuit is divided into at least a first inspection circuit and a second inspection circuit, and the digital driver is divided into at least a first digital driver and a second digital driver,
The first digital driver and the first inspection circuit are arranged opposite to each other across the data line, and the second digital driver and the second inspection circuit are opposed to each other across the data line. Arranged,
In addition, the first digital driver and the second inspection circuit are disposed on the same side of the data line, and the second digital driver and the first inspection circuit are on the same side of the data line. An active matrix substrate, which is disposed at an end. An inspection method for an active matrix substrate according to any one of claims 1 to 10,
Driving the data line by the digital driver to write a signal to the capacitor connected to the switch element;
Bringing the output of the digital driver into a high impedance state;
An active matrix substrate that reads out the signal written in the capacitor by the inspection circuit to obtain a basic signal as a basis of the inspection and inspects an active matrix portion based on the acquired basic signal Inspection method. In claim 11,
12. An inspection method for an active matrix substrate, comprising: performing an inspection of the digital driver itself and a disconnection inspection of the data lines prior to execution of each step according to claim 11. In claim 11,
The method of inspecting an active matrix substrate based on the acquired basic signal includes a step of considering a two-dimensional distribution of the characteristics of the basic signal in the active matrix portion. . In claim 11,
The method of inspecting an active matrix substrate, wherein the step of inspecting the active matrix portion based on the acquired basic signal includes a step of comparing the acquired basic signal with a sample signal prepared in advance.   A liquid crystal device configured using the active matrix substrate according to claim 1.   An electronic apparatus configured using the liquid crystal device according to claim 15.

Images