JPH0687169B2 - Mask inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an inspection apparatus for a large mask which is an original plate for a shadow mask, a liquid crystal display, a printed circuit board and the like.

(Prior Art) In order to inspect whether a pattern drawn on a mask such as a printed circuit board has a defect, an inspector visually inspects the pattern surface of the mask with a microscope to check for the presence of the defect. When there was a defect, a mark was put on the back of the part with a felt-tip pen, and the mask was handed to a repair worker after the inspection.

However, such a visual inspection with a microscope not only puts a large mental burden on the inspector but also requires a lot of time, so that the work efficiency is poor, and moreover, there is a problem in that a missed portion of a defective portion is likely to be missed. there were.

Therefore, recently, the automatic inspection is performed by optically inspecting the pattern drawn on the mask for the presence of defects, storing the coordinates of defective portions if any, and outputting the coordinates of the defective portions after the inspection. A mask inspection device is used.

FIG. 5 shows a configuration example of such a mask inspection device. That is, as shown in FIG. 5, in the frame 2 supported by the support frame 1, from the X-axis moving table 3a moving in the X-axis direction of the XY coordinates and the Y-axis moving table 3b moving in the Y-axis direction. The table 3 is provided, and the mask 4 placed on the table 3 can be moved on the XY coordinate plane by the X-axis moving table 3a and the Y-axis moving table 3b. In this case, X-axis moving table 3a, Y-axis moving table 3b
Although not shown, each can be moved by rotation of the feed screw and the motor directly connected thereto. An illumination lens barrel 5 is attached to the support base 1 with a cylindrical portion serving as an optical path penetrating the central portion of the bottom surface of the frame 2, and the light emitted from a lamp 6 provided inside is passed through a lens 7 to a mask 4. It can be irradiated. Further, an objective lens barrel 8 is attached to the frame 2 with its tubular portion penetrating through the central portion of the upper surface corresponding to the illumination lens barrel 5, and the pattern of the upper surface of the mask 4 is imaged through a lens 9 provided inside. An image can be formed on the sensor 10.

In the figure, reference numeral 15 denotes a mirror which is a part of the laser measuring system mounted on the X-axis moving table 3a, but illustration of a laser oscillator, a receiver and the like is omitted.

In the automatic inspection apparatus having such a configuration, when inspecting whether or not the pattern drawn on the mask 4 has a defect, the pattern data of the mask 4 prepared in advance is shown in correspondence with each coordinate position. The image signal at each coordinate is fetched from the image sensor 10 while the table 3 is moved in the X-axis direction and the Y-axis direction by the control of the control computer, and the image signal and the storage device are stored. There is no defect if the pattern data corresponding to the same coordinate position is compared and they match,
If they do not match, it is determined that there is a defect, and the imaging pattern at that position,
The defect pattern is stored in the storage device together with its coordinates as defect data. When the series of operations is completed, the defect data is read from the storage device, the table 3 is driven to position the mask 4 at the coordinates with the defect, and the image pickup pattern and the defect pattern are color-coded and displayed on the pattern monitor. Does the following while looking at the microscope.

(B) Cancel defects such as dust that need not be corrected.

(B) The table 3 is manually fed so that the defect position becomes the cursor position of the microscope, and the coordinates are read by the control computer.

(C) When there are a plurality of defects at the same coordinate position, the operation of (B) is performed so that one defect-one coordinate.

When such a visual check is performed and the defect data stored in the storage device is corrected, these are collectively output by the printer, and then the mask 4 is placed on the desk and each coordinate of the printer output is placed using an orthogonal scale. I am trying to put a mark on that position with a felt-tip pen.

(Problems to be Solved by the Invention) Thus, in the conventional mask inspection apparatus, the presence or absence of a defect in the pattern drawn on the mask is automatically searched, and if there is a defect, the imaging pattern and the defect pattern are detected. The defect data is stored in a storage device together with the coordinates, and then all the defect data is read from the storage device and the coordinates are output by a printer. Therefore,
The inspector needs to manually find the defect coordinate position of the mask on the scale based on the coordinates of the defect data output by the printer, and to mark the position with a felt-tip pen. There's a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a mask inspection apparatus capable of adding a function of automatically marking a defect position of a mask to significantly reduce the inspection process and improve productivity.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a mask placed on a table, and a pair of masks provided on the back surface and the front surface of the mask, respectively. And an objective lens barrel that form an optical microscope, and the pattern detecting means for optically detecting the pattern drawn on the mask, and either the mask or the pattern detecting means are centered around a predetermined reference position X-. The moving means for moving the Y coordinate in the X-axis direction and the Y-axis direction is compared with the detection signal at each coordinate position detected by the pattern detecting means and the pattern signal at the corresponding coordinate position of the previously prepared reference pattern. Determination means for determining the presence / absence of a defect based on whether or not there is a match, and a storage means for storing the defect coordinates when the determination means determines that there is a defect. Positioning means for giving a drive command to the moving means to position the mask at the defect coordinates when the defect coordinates stored in the means are taken in, and provided at the tip of the lens barrel arranged on the back side of the mask. And a marking means for marking the back surface of the mask at a position corresponding to the defect coordinate position positioned by the positioning means, wherein the marking means is a lens shutter attached to the tip of the lens barrel, and the same mirror. The nozzle is configured to be capable of ejecting ink to a marking position on the back surface of the mask corresponding to the defect coordinate position while being attached to the tip of the cylinder so as to be rotatable in the radial direction and having the lens shutter closed.

(Operation) In the mask inspection apparatus having such a configuration, either the mask mounted on the table or the detecting means is centered on a predetermined reference position and the X-axis direction of the XY coordinate and the Y-axis.
When the pattern drawn on the mask is detected by the detecting means while moving in the axial direction, the detection signal at each coordinate position is compared with the corresponding pattern signal of the reference pattern prepared in advance, and both signals match. Whether or not there is a defect is determined by whether or not there is, and if there is a defect, the defect coordinate position is stored in the storage means. Then, when the defect coordinates are fetched from the storage means, the mask is positioned at the defect coordinates and the marking means marks the corresponding surface of the corresponding coordinate position of the mask.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

First, FIGS. 2 and 3 show the mechanical structure of the present invention.
It will be described with reference to the drawings.

In this embodiment, in the mask inspection apparatus having the structure shown in FIG. 5, a marker head 11 is provided at the opening of the tubular portion of the illumination lens barrel 5 as shown in FIG.
The tube from the ink pump 12 which is attached to the tubular part 11
The structure is such that ink can be supplied through 13, and the other structures are the same as those in FIG. 5, so description thereof will be omitted here.

As shown in FIG. 3, the marker head 11 has a lens shutter 11b which is opened and closed by a drive mechanism 11a, and a nozzle which moves between the shutter diaphragm center position and the shutter frame in conjunction with the opening and closing operation of the lens shutter 11b. The nozzle 11c is connected to the tube 13 and ejects the ink supplied from the ink pump 12.

Next, a configuration example of the control circuit of the mask inspection apparatus according to the present invention will be described with reference to FIG. In FIG. 1, 21
Is a control computer for centralized control of the entire device, 22 is a magnetic tape device that inputs each design data used for manufacturing various masks, and 23 is design data corresponding to the corresponding mask from this magnetic tape device 22. The magnetic taper device 22 and the magnetic disk device 23 are magnetic disk devices for inputting and storing the data.
It is connected to the. A pattern monitor 25 and a console 26 as an operation terminal are connected to the data bus 24, and the console 26 is also provided with a printer 27. On the other hand, 28 is a control computer via the data bus 24.
The interface 28 is connected to 21. This interface 28 is a dedicated interface mainly for electronic circuits required for automatic inspection control based on information input from the inspection device main body 29 and commands from the control computer 21. It is composed of a circuit. That is, the interface 28 includes a reference pattern generation circuit 28-1, a position counter 28-2, an image input circuit 28-
3, a comparison circuit 28-4, a table control unit 28-5 and a marker driver 28-6. The reference pattern generation circuit 28-1 converts design data (geometric expression format) transferred from the magnetic disk device 23 via the main memory of the control computer 21 into a bitmap in response to the progress of the inspection, It is output to the comparison circuit 28-4. The position counter 28-2 counts up / down pulses proportional to the table displacement sent from the laser measuring system on the inspection device main body 29 side to grasp the current position of the table, and the control computer 21 and the comparison circuit 28-4. Is output to. The image input circuit 28-3 receives the image signal from the image sensor 10 on the inspection apparatus main body 29 side and receives a comparison circuit 28-4.
In order to perform a one-to-one comparison with the data on the side of the reference pattern, the image signal is converted into a digital image and arranged. The comparison circuit 28-4 is a reference pattern generation circuit
28-1 and the pattern data input from the image input circuit 28-3 are compared, and if there is a mismatched portion, it is judged as a defect, and the image data of the small area including this defect pattern and the position counter 28-2 are read. The coordinates are transferred to the control computer 21. The table control unit 28-5 positions the table at arbitrary coordinates at a speed according to a command issued from the control computer 21. Marker driver 28
-6 is a marker set (nozzle set and lens shutter close) and reset (nozzle reset and lens shutter
Open) and the operation of the inkjet.

Next, the operation of the mask inspection apparatus configured as described above will be described.

Now, assume that a mask 4 having a general shape as shown in FIG. 4 is placed at a predetermined position on the disk 3 shown in FIG. 5 as an inspection target. On the mask 4, four alignment marks 4a and a main pattern are formed.
4 as the design data stored in the magnetic disk 23
There are coordinates of each alignment mark, coordinates O of the main pattern, size of the main pattern, and data of the main pattern. When the table control unit 28-5 operates according to a command from the control computer 21, the mask 4 is sequentially positioned at four alignment positions by the movement of the table 3, and the image input to the image input circuit 28-3 at that time is displayed. Image signal picked up by sensor 10 and position counter 28
The current position and the current position grasped at -4 are taken into the control computer 21 and the center coordinates of each mark are measured. Then, the rotation, shift and expansion / contraction of the mask are calculated from this measurement result, and the rotation, shift and size of the main pattern are calibrated.

Next, when each calibration for the mask 4 is completed, the table control unit 28-5 causes the table 3 to travel in the zigzag direction in the direction and order shown by the dotted line in FIG. Therefore, the pattern surface of the mask 4 is imaged by the image sensor 10 while being continuously scanned in the Y direction in the X direction.
The image signal thus picked up by the image sensor 10 is processed as a digital image by the image input circuit 28-3 and then added to the comparison circuit 28-4, where it is taken in from the reference pattern generation circuit 28-3. It is compared with the pattern data. In the comparison circuit 28-4, if there is a mismatch between the digital image and the pattern data, the digital image of a small area including the defective pattern and the position counter 28
The coordinates read from -2 are transferred to the control computer 21.
In this case, a strip-shaped area that can be inspected by one table traveling is called a frame. The presence / absence of defects is in small area units called cells. That is, when a defect is detected in a cell, the control computer 21 captures the imaging pattern of the cell, the defect pattern, and the center coordinates of the cell,
The frame number and the cell number are added to this and stored in the magnetic disk device 23.

Thus, the mask 4 is automatically inspected while being compared with the design data, and if there is a defect, its coordinates, the image pickup pattern and the defect pattern are stored in the magnetic disk device 23 as defect data. The visual check recognizes the presence or absence of defects and confirms the defect coordinates.

First, the control computer 21 reads out the defect data stored in the magnetic disk device 23, and the table control unit 28
A command is given to -5, and the mask is sequentially positioned at the defect coordinates by the movement control of the table 3. Next, the operator observes the monitor and the microscope to recognize the defects and confirm the defect coordinates, and when the calibration is necessary, the defect coordinates stored in the magnetic disk device 23 are updated.

When the visual check is completed based on the defect data stored in the magnetic disk device 23, the marking operation is started. Table control unit 28 from control computer 21 again
-5 is given a command to control the movement of the table 3 and the mask 4
Is positioned at the defect coordinates, the marker driver 28-6 is driven, and ink jetting is performed on the back surface of the mask 4 corresponding to the defect coordinate positions.

The operation at this time will be described with reference to FIGS. 2 and 3. When a setting command is given to the marker driver 28-6, the driving mechanism 11a causes the lens shutter 11b to move from the state of FIG. Nozzle 11 with closing as in b)
c is rotated to the center position of the shutter, and preparation is completed. Then, each time the mask is positioned at the defect coordinates, a mark command is given to the marker driver 28-6, and the ink is ejected from the nozzle 11c toward the back surface of the mask through the tube 13 by the operation of the ink pump 12 shown in FIG. , Is marked.

As described above, in this embodiment, the mask is placed on the table 3 by the image sensor 10 while moving the mask 4 in the X-axis direction and the Y-axis direction of the XY coordinates around the predetermined reference position. The drawn pattern is imaged and input to the image input circuit 28-3, and at the same time, the image input circuit 28-3 is input.
Of the digital image data at each coordinate position output from the magnetic disk device 23 and the pattern signal at the same coordinate position output from the reference generation circuit 28-1 by fetching the design data previously stored in the magnetic disk device 23. If there is a defect, the coordinates, the image pickup pattern, and the defect pattern are stored in the magnetic disk device 23 as defect data. After further recognizing and calibrating the defect coordinates by visual check, the magnetic disk drive
The defect coordinates are taken from 23, the mask 4 is positioned at the defect coordinates, and a mark is attached to the back surface corresponding to the coordinate position of the mask 4 by the ink jet method by the marker head 11 attached to the illumination lens barrel 5. Is.

Therefore, since it is possible to automatically mark the defect position of the mask, the inspector uses the scale of the defect coordinate position of the mask based on the coordinate of the defect data output by the printer as in the conventional case. It is not necessary to perform the manual work of marking the position with a felt-tip pen, and it is possible to greatly save labor in the inspection process and improve productivity. Further, as is apparent from FIG. 3, the marker head 11 attached to the illumination lens barrel 5 has the lens shutter 11b opened during the inspection, and the lens shutter 11b is closed during the marking operation to eject ink from the nozzle 11c. Therefore, the lens 7 and the like of the illumination barrel 5 are not contaminated by the ink scattering.

Although the database comparison type inspection apparatus has been described in the above-described embodiment, even a die comparison or mask comparison type inspection apparatus incorporates a marking means similar to the above, and the mask corresponding to the defect coordinate position is similar to the above. It is possible to automatically put a mark on the back side of.

[Effects of the Invention] As described above, according to the present invention, either the mask mounted on the table or the detection means is centered on a predetermined reference position and the X-axis direction of the XY coordinates and the Y-axis. The pattern drawn on the mask is detected by the detecting means while moving in the axial direction, and the presence or absence of a defect is determined by comparing the detection signal at each coordinate position with the corresponding pattern signal of the reference pattern prepared in advance, When there is a defect, in the mask inspection apparatus which stores the defect coordinate position in the storage means, the defect coordinate is fetched from the storage means, the mask is positioned at the defect coordinate, and the corresponding coordinate position of the mask is corresponded. Since the surface to be marked has a function of automatically attaching a mark, it is possible to provide a mask inspection apparatus capable of significantly saving labor in the inspection process and improving productivity. In addition, the function to automatically add a mark is used when the lens shutter is attached to the tip of the lens barrel for pattern detection and the lens shutter is also attached to the tip of the lens barrel so as to be rotatable in the radial direction. It is composed of a nozzle capable of ejecting ink at the marking position on the back surface of the mask corresponding to the defect coordinate position. Therefore, the above-described effects can be achieved with a relatively simple device configuration and without adversely affecting the device. As a result, the entire device can be made smaller and lighter and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing an embodiment of a mask inspection device according to the present invention, FIG. 2 is a diagram showing a state in which a marker unit is attached to an illumination lens barrel of the mask inspection device, and FIG.
FIG. 4 is a configuration diagram showing the marker head of the marker unit in detail, FIG. 4 is a diagram for explaining an inspection sequence for a mask having a general shape, and FIG. 5 is a configuration explanatory diagram of a conventional mask inspection apparatus main body. 3 ... table, 4 ... mask, 5 ... illumination lens barrel, 8 ...
… Objective barrel, 10 …… Image sensor, 11 …… Marker head, 12 …… Ink pump, 13 …… Tube, 21 …… Control computer, 23 …… Magnetic disk unit, 28 …… Interface, 28-1 …… Reference pattern generation circuit, 28-2 ……
Position counter, 28-3 ... image input circuit, 28-4 ... comparison circuit, 28-5 ... table control unit, 28-6 ...
Marker driver.

Claims (1)

[Claims] 1. A mask placed on a table, and a pair of an illumination lens barrel and an objective lens barrel which are provided so as to face the back surface and the front surface of the mask, respectively. Pattern detection means for optically detecting,
Moving means for moving either the mask or the pattern detecting means in the X-axis direction and the Y-axis direction of the XY coordinate centering on a predetermined reference position, and at each coordinate position detected by the pattern detecting means. Judgment means for judging the presence or absence of a defect by comparing the detection signal with the pattern signal of the corresponding coordinate position of the reference pattern prepared in advance to determine whether there is a defect, and this judgment means determines that there is a defect. Then, storage means for storing the defect coordinates, positioning means for giving a drive command to the moving means to position the mask at the defect coordinates when the defect coordinates stored in the storage means are fetched, and the mask On the back surface of the mask provided at the front end of the lens barrel disposed on the back surface side of the The marking means comprises a lens shutter attached to the front end of the lens barrel, and the lens shutter attached to the front end of the lens barrel so as to be rotatable in the radial direction. A mask inspection device comprising a nozzle capable of ejecting ink at a marking position on the back surface of the mask corresponding to a coordinate position.