JPH04236367A - Apparatus for inspecting substrate - Google Patents

Abstract

PURPOSE:To inspect continuity and disconnection without damaging the metal wiring pattern on a substrate to be measured by the use of laser beam. CONSTITUTION:The terminal part of the pattern 11 on a substrate 3 is irradiated with laser beam. When a transparent electrode plate 1 is set to voltage V1 by a power supply 6, the part irradiated with laser beam of a sheet 2 composed of a photoconductive material becomes a continuity state and the pattern 11 becomes V1. After the laser beam is cut off, the power supply 6 is changed over to set the transparent electrode plate 1 to V2. Herein, when the separate terminal of the pattern 11 is irradiated with laser beam, the charge corresponding to (V1-V2) flows when a continuity state is obtained across the terminals and can be detected by an ammeter 5 but, at the time of disconnection, no current flows and the continuity and disconnection of the pattern are judged.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate inspection apparatus, and more particularly to a substrate inspection apparatus used for inspecting the quality of metal wiring panns formed on an insulating substrate.

0002

2. Description of the Related Art FIG. 3 is a block diagram showing a first conventional example. The board inspection apparatus shown in FIG.
and a control section 7 that controls the resistance meter, probe, and positioning section.

[0003] This device tests continuity and non-continuity between two terminals in an arbitrary pattern. Position the probe 15 using the positioning unit 14 for an arbitrary pattern, and
A probe is brought into contact with the terminal and the resistance value is measured to determine whether or not there is continuity between the two terminals of the pattern. The probes are sequentially moved by the positioning section in the order stored in the control section 17 in advance, and all patterns are inspected.

FIG. 4 is a block diagram showing a second conventional example. The board inspection apparatus shown in FIG.
21, and a control section 117 that controls the capacitance meter, the probe, and the positioning section.

Select an arbitrary pattern using the probe 123, measure the capacitance between the probe 123 and the reference potential surface 104 (ground potential surface), and compare it with a theoretically calculated value to determine whether the pattern is good or not. Judging. The equivalent circuit between the pattern to be measured and the reference potential plane can be expressed as shown in FIG. Capacitance between the pattern to be measured and the reference potential surface 120
In addition to the insulation resistance 119, a series connection circuit of the capacitance 118 of another pattern and the insulation resistance 121 between the patterns is connected in parallel.

When the pattern to be measured is normal, the insulation resistance 1
21 and insulation resistance 119 are both sufficiently large, the value measured by the capacitance meter is almost equal to the capacitance 115, but if there is a defect in the pattern, the measured value will be a value different from the capacitance 120. . For example, if a pattern is broken in the middle, a measurement value smaller than 120 will be obtained, and if the pattern has poor insulation or short circuit with another pattern, a measurement value larger than 120 will be obtained. value. Therefore, if the theoretically calculated capacitance values differ by more than a certain level, it can be determined that the pattern is defective.

[0007]

SUMMARY OF THE INVENTION The conventional board inspection apparatus described above measures the resistance value or capacitance by bringing a probe into contact with the pattern. Since the tip of the probe is sharp, there is a drawback that the pattern may be damaged when the probe is brought into contact.

[0008]

[Means for Solving the Problems] A board inspection apparatus according to a first aspect of the invention includes a laser device that generates a laser beam that is irradiated onto a metal wiring pattern on a board to be measured, and a surface of the board to be measured that is hit by the laser beam. a sheet of photoconductive electrostatic material that is brought into close contact with the substrate, a transparent electrode plate, an electrode plate that is brought into close contact with a surface of the substrate to be inspected that is not irradiated with the laser beam, and means for vertically and horizontally transporting the substrate to be inspected sandwiched between the electrode plates. or a means for scanning a laser beam, an ammeter and a power source connected to the transparent electrode plate, and a means for sending the laser device and the substrate in the vertical and horizontal directions, or a means for scanning the laser beam, an ammeter, and a power source. The control unit is configured to include a control unit.

The board inspection device of the second invention includes a laser beam irradiated onto a metal wiring pattern on a substrate to be measured, a sheet of photoconductive material that is brought into close contact with a surface of the substrate to be measured that is hit by the laser beam, and A transparent electrode plate, an electrode plate that is closely attached to a surface of the substrate to be inspected that is not hit by the laser beam, and means for vertically and horizontally feeding the substrate to be inspected sandwiched between the electrode plates, or scanning the laser beam on the substrate to be measured. an ammeter and a power source connected to the transparent electrode plate; an optical system that focuses the laser beam onto the substrate to be measured; a shutter that continues the laser beam; and a means for sending the substrate in the vertical and horizontal directions. Alternatively, it is configured to include means for scanning a laser beam, an ammeter, a power supply, and a control section for controlling a shutter.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention. The substrate inspection apparatus shown in FIG. 1 includes a sheet 2 of photoconductive material that is closely attached to a substrate 3, a transparent electrode plate 1 that is overlapped with the sheet 2, and an electrode plate 4 that is closely attached to the back side of the substrate 3. , an X-Y stage 9 for setting the substrate 3 sandwiched between the electrodes 1 and 4, a holder 10 for holding the substrate to be inspected sandwiched between the electrode plates on the X-Y stage, and the
- A stage control unit 8 that controls the Y stage, a laser device 12 that generates a laser beam that is irradiated onto the substrate 3, an ammeter 5 that measures the current flowing through the electrode plate 1, and a voltage that is applied to the electrode plate 1. A power source 6 to control the power source 6 and a control unit 7 to control the power source 6 and the control unit 7 to control the power source 6
It is composed of:

Among these, the sheet of photoconductive material used is, for example, one used in a copying machine to which electrophotographic technology is applied. The electrode plate 4 is electrically grounded and serves as a reference potential surface.

Next, the procedure for inspecting a pattern will be explained. First, the X-Y stage is controlled so that the laser beam is selectively irradiated onto one side of the terminal portion of the pattern 11 to be inspected. Then, the electrical resistance of the portion of the photoconductive material sheet that is hit by the laser beam decreases, so that the electrode plate 1 and the pattern 15 can be electrically connected. In this state, the voltage of the power source 6 is set to a constant voltage V1, and the voltage of the electrode plate 1 is set to V1. Since the pattern 15 is electrically connected to the electrode plate 1, the pattern 15 is charged to the voltage V1. The amount of charge on the pattern 15 at this time is the product of the capacitance between the electrode plate 4 and the pattern 11 (hereinafter referred to as capacitance of the pattern 11) serving as a reference potential surface and the voltage V1.

When the pattern 15 is sufficiently charged, the laser beam irradiation is stopped. Then, the pattern 15 and the electrode plate 1 cannot be electrically connected. In this state, the voltage of the power supply 6 is set to V2, which is different from V1. Then, the electrode plate 1, which had been charged to V1, is charged and discharged and reaches a potential of V2.

Next, by controlling the X-Y stage, the substrate is moved to a position where the laser beam hits the other terminal of the pattern 11, and the laser beam is irradiated again. If there is continuity between the two terminals of the pattern 11, the terminal to which the laser beam is irradiated will also be charged to V1, and will be charged and discharged to a potential of V2 by the laser beam irradiation. The current flowing at this time is passed through the ammeter 5 to the power source 6.
Therefore, by reading the ammeter 5, the discharge of the pattern 11 can be determined. On the other hand, if there is a disconnection between the two terminals of the pattern 11, the terminal to which the laser beam is applied this time is not charged to V1, so no current flows. By this, it is possible to determine whether the pattern 11 is conductive or non-conductive.

[0016] In order to inspect the patterns on the substrate one after another, it is necessary to position the laser beams one after another on the patterns to be inspected. In this example, the substrate is
This is done by moving vertically and horizontally using a Y stage. Although not shown in this embodiment, another method may be used in which the substrate is fixed and the laser beam is scanned in the vertical and horizontal directions. Furthermore, in this embodiment, the ammeter 5 is connected between the electrodes 1 and 6, but even if it is inserted into the ground wire of the electrode 4,
Inspection can be performed by the above procedure.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

The substrate inspection apparatus shown in FIG.
02, an electrode plate 104 that is closely attached to the back side of the substrate 103, and the substrate 104 is
Roller 108 that sends the object sandwiched between 1 and 104 in the horizontal direction
, 109, a light source 112 that generates a laser beam to be irradiated onto the substrate 103, and an optical system 1 that focuses the laser beam.
16, a shutter 113 for continuing the laser beam, and a reflecting mirror 11 for scanning the laser beam on the substrate 103.
0, a motor 111 that rotates it, and an electrode plate 101
an ammeter 105 that measures the current flowing through the electrode plate 101;
The power source 106 applies a voltage to the power source 106, and the control section 107 controls the power source 106 and the control section 107.

Among these, the sheet of photoconductive material used is, for example, one used in a copying machine to which electrophotographic technology is applied. Electrode plate 104 is electrically grounded and serves as a reference potential surface. The wiring to the electrode plates 101 and 104 is as follows:
Although the connection may be made by direct soldering, etc., the electrode plate itself moves due to the rotation of the rollers 108 and 109.
Since the wiring is dragged, in this example, the wiring is
08 and 109, and the roller is made of a conductive material such as metal, thereby electrically grounding the electrode plate.

Next, the procedure for inspecting a pattern will be explained. First, the angle of the reflecting mirror 110 is controlled to selectively irradiate the pattern 115 to be inspected with a laser beam. Then, the electrical resistance of the portion of the photoconductive material sheet that is hit by the laser beam decreases, so that the electrode plate 101 and the pattern 115 can be electrically connected. In this state, power supply 10
6 is set to a constant voltage V1, and the voltage of the electrode plate 101 is set to V1. Since the pattern 115 is electrically connected to the electrode plate 101, the pattern 115 is charged to a voltage V1.

The amount of charge on the pattern 115 at this time is the product of the capacitance between the electrode plate 104 serving as a reference potential surface and the pattern 115 (hereinafter referred to as the capacitance of the pattern 115) and the voltage V1. When the pattern 115 is sufficiently charged, the laser beam irradiation is stopped. Then pattern 11
5 and the electrode plate 101 cannot be electrically connected. In this state,
The voltage of the power supply 106 is set to V2, which is different from V1. Then, the electrode plate 101 that was charged to V1 is charged and discharged, and V
The potential becomes 2.

Next, the laser beam is again irradiated onto the same location. Then, conduction between the electrode plate 101 and the pattern 115 is established again, so that the pattern 115 is charged and discharged and becomes V2. At this time, the pattern 115 is charged and discharged with an amount of charge represented by (capacitance of the pattern 115)×(V1-V2). Since this charge is supplied from the power supply 106 through the ammeter 105, it can be measured by integrating the measured value of the ammeter 105. The capacitance of the pattern 115 is calculated based on this measured value, and the quality of the pattern is determined.

[0023] In order to inspect the patterns on the substrate one after another, it is necessary to position the laser beams one after another on the patterns to be inspected. In a second embodiment, this is accomplished by scanning the laser beam only laterally and directing the substrate in a direction perpendicular to the scanning direction of the laser beam. The order in which the patterns are inspected is stored in advance in the control unit, and the patterns are inspected in order starting from the edges of the substrate, so that the laser beam positioning time is minimized. Other methods for positioning the laser beam in a pattern include fixing the substrate and scanning the laser beam in the vertical and horizontal directions, or fixing the laser beam and moving the substrate in the vertical and horizontal directions. I do not care. Further, although the ammeter 105 is connected between the electrode 101 and the power source 106, the test can be performed by the above procedure even if it is inserted into the ground wire of the electrode 104.

[0024]

Effects of the Invention The substrate inspection apparatus of the present invention has the advantage that even minute patterns can be inspected without damage.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the invention.

FIG. 3 is a block diagram showing a first conventional example.

FIG. 4 is a block diagram showing a second conventional example.

FIG. 5 is a circuit diagram for explaining the operation of the conventional example shown in FIG. 4;

[Explanation of symbols]

1 Transparent electrode plate 2 Sheet of photoconductive material 3. Board to be inspected 4 Electrode plate 5 Ammeter 6 Power supply 7 Control section 8 Stage control section 10 Holder 11 Pattern 12 Laser device 13 Resistance meter 14 Positioning section 15 Probe

Claims (2)

[Claims] 1. A laser device that generates a laser beam that irradiates a metal wiring pattern on a substrate to be measured, a sheet of photoconductive material that is brought into close contact with a surface of the substrate to be measured that is hit by the laser beam, and a transparent electrode plate. and an electrode plate that is closely attached to a surface of the substrate to be inspected that is not hit by the laser beam;
A means for vertically and horizontally feeding the substrate to be inspected sandwiched between the electrode plates, or a means for scanning a laser beam, an ammeter and a power source connected to the transparent electrode plate, and a means for feeding the laser device and the substrate in the vertical and horizontal directions, or 1. A board inspection device comprising means for scanning a laser beam, an ammeter, and a control section for controlling a power source. 2. A laser device that supplies a laser beam to a metal wiring pattern on a substrate to be measured, a sheet of photoconductive material that is brought into close contact with a surface of the substrate to be measured that is hit by the laser beam, and a transparent electrode plate. and an electrode plate that is closely attached to a surface of the substrate to be inspected that is not hit by the laser beam;
means for vertically and horizontally feeding the substrate to be inspected sandwiched between the electrode plates; or means for operating the laser beam on the substrate to be measured; an ammeter and a power source connected to the transparent electrode plate; The method includes an optical system that focuses on the substrate, a shutter that continues the laser beam, a means for sending the substrate in vertical and horizontal directions or a means for scanning the laser beam, an ammeter, a power source, and a control unit that controls the shutter. A board inspection device featuring: