JPH09113220A - Inspection point marking method for fine processed product, and method device for automatic dimensional inspection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To point-measure a fine pattern with high efficiency and accuracy with the use of CAD(computer aided design) data. SOLUTION: When a part of an actual thing pattern of the product processed from the CAD data of a product design dimension pattern (lead frame) is optically taken in for dimensional inspection, the inspection point marker for specifying an inspection point P2 of the actual thing pattern is set with, for example, points, 1-4, on the CAD data on the tip of an inner lead. And further, the field of view of an image input means corresponds to the inspection point P2 of the actual thing pattern specified with the set inspection point markers 1-4, and a part of the actual thing pattern is optically taken in.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention designs a two-dimensional pattern by using a CAD such as a lead frame, and measures dimensions of a fine pattern of a product manufactured by etching or pressing based on the design data. The present invention relates to an inspection point marking method, an automatic dimension inspection method, and an automatic dimension inspection device that are suitable for application in cases and can be effectively used for dimension inspection of prototypes and sampling dimension inspection of shipped products.

[0002]

2. Description of the Related Art CAD (Computer Aided Design)
Etching products have a two-dimensional fine pattern designed and manufactured by using a lead frame used to electrically connect to an IC (integrated circuit) chip to be mounted.

FIG. 22 shows an example of a lead frame for one chip as viewed from one side. A die pad (island) 10 for mounting a chip (not shown) is located at the center of the lead frame. The die pad 10 is supported by an outer frame 12 via a tab suspension bar 14, and an inner lead 16 is arranged around the die pad 10 with its tip close to the die pad 10, and an outer lead continuous with the inner lead 16 is provided. 18 is the above-mentioned outer frame 1 via the dam bar 20 etc.
Supported by 2. Also, the inner lead 16 has
A fixing tape 22 made of plastic is attached to prevent deformation of the leads 16. The broken line in the figure is the mold line.

Taking the lead frame as an example, an outline of the steps from etching product design to product completion is shown in FIG.
It looks like 3.

As described above, the pattern design of the lead frame is performed using CAD. First, in the product pattern design process of CAD1, (A) product dimension CAD data identical to the target product dimension is created, and then CAD2. In the etching correction process of (1), the correction allowance for the side etching, which is excessively removed from the width of the resist pattern in the actual etching process, is added to the (A) product dimension CAD data to form a resist pattern prototype (B). ) Create machining dimension CAD data, and use this machining dimension C in the next pattern manufacturing process.
AD data is drawn on a glass plate by a laser plotter to create a (C) glass original plate pattern. This original plate pattern is created for both the front and back surfaces of the lead frame.

Then, using the glass original plate as a mask, the resist coated on the metal material such as the copper plate which is the base material of the lead frame is exposed (baked),
By developing and burning (curing) (D) to form a plate-making pattern (resist pattern), etching for removing the metal material in the exposed portion is performed, and then the adhering resist is peeled off. A lead frame, or (E) product pattern is obtained.

In the manufacturing process of the lead frame,
The (E) product pattern is preferably the same as the (A) product dimension CAD data which is the design pattern. Therefore, (B) processing dimension CAD data (this is (C) glass original plate pattern, which is designed by adding a correction allowance to this (A),
The size difference between (D) the pattern having the same size as the plate-making pattern) and (E) above is large, and usually has a difference of several tens of μm.

Similarly, as another etching product to be microfabricated, there is a shadow mask for a color television. In comparison with this, the lead frame has an irregular shape and the post-process performed after the etching is complicated. It has the feature of being

Further, as a feature of the lead frame, there is a gap (space to be removed by etching) between the island 10 to which the chip is attached and the tip of the inner lead to be wire-bonded, and the etching liquid easily enters there. The etching of the tip portion of the inner lead is likely to proceed and the tip tends to be tapered, but a sufficient tip width is required for wire bonding.

As described above, the CAD data (B) for forming the plate-making pattern (D), which serves as a mask for etching a lead frame which is difficult to process, is side-etched in excess of the resist pattern as described above. It is created by performing a correction for adding the size to be added to the product size CAD data of (A) as a correction margin. Conventionally, the correction allowance used for the above-mentioned etching correction has been set based on experience.

Further, it is necessary to measure the dimension of the actually manufactured product, for example, in order to certify that the dimension of the inner lead tip is within the tolerance (allowable range from the target value). In this case, conventionally, local dimensional measurement was often performed on some leads, but there is also a request for all leads.

In order to measure the size of a fine pattern of an etching product such as a lead frame, there are manual measurement (1) a measuring method using a magnifying projector, (2) a measuring method using an optical microscope with a scale, and automatic measurement. A possible digital method (3) measuring method using a measuring microscope (optical automatic dimension measuring machine) is known.

Specifically, the above (1) is a method of enlarging and projecting an actual physical pattern with transmitted light, and applying a ruler to the projected view to measure the dimensions. The above (2) is a method in which a scale is attached. This is a method of combining a conventional optical microscope and simple image processing to measure a pattern image while enlarging it. Further, the above (3) is a method in which the optical microscope and the XY stage are interlocked with each other, and the captured enlarged image is image-processed to perform digital measurement. The area can be image-measured.

[0014]

However, in the case of the analog measurement methods of the above (1) and (2), the measurement accuracy is poor, and the operator manually sets and moves the sample to set the visual field as a target. Since the positions must be matched, the work efficiency is poor, and if all pins of a multi-pin lead frame such as 208 pins are measured, it will take a day's work.

Further, the optical automatic dimension measuring machine of the above (3),
It is possible to perform automatic measurement by instructing and teaching the point to be measured, but for that purpose, it is necessary to program in advance, and since this programming is very difficult, automatic measurement is currently not functioning sufficiently. is there.
In addition to the above inspection, CAD of measurement data and design dimensions
There is also a problem that the work load is extremely large because it is necessary to manually check whether or not the measurement data of each lead is within the tolerance (allowable dimension) by performing collation by superimposing it on the drawing.

The present invention has been made to solve the above-mentioned conventional problems, and provides an inspection point marking method for a microfabricated product, which is capable of efficiently measuring the dimension of a fine pattern with high accuracy. An object of the present invention is to provide an automatic dimension inspection method that is used and an automatic dimension inspection device that can be used in the method.

[0017]

According to the present invention, as described in claim 1, a part of the actual pattern of the product processed based on the CAD data of the product design size pattern is optically photographed and the size is inspected. At this time, by providing an inspection point marker for specifying an inspection point of the actual pattern at one or more points on the CAD data, by providing an inspection point marking method for a microfabricated product, This is a solution to the above problem.

According to a third aspect of the present invention, when a part of the actual pattern of the product processed based on the CAD data of the product design dimension pattern is optically photographed and the dimension inspection is performed, An inspection point marker for specifying the inspection point of the physical pattern is set at one or more points on the CAD data, and based on the inspection point of the physical pattern specified by the set inspection point marker,
A microfabricated product characterized in that a part of the physical pattern is optically photographed, and the dimension is inspected based on the inspection point marker set on the CAD data and the marker corresponding point on the physical pattern image-inputted. The above-mentioned problems are similarly solved by providing the automatic dimension inspection method (1).

According to a fourth aspect of the present invention, image input means for inputting an image of a physical pattern of a product processed based on CAD data of a product design dimension pattern, and image data of the input physical pattern. Is an actual size collating means for superposing and collating with the CAD data, and calculating a reference point of an actual pattern corresponding to the reference point defined in the CAD data. And a means for setting an inspection point marker for specifying an inspection point of the actual pattern at one or more points on the CAD data, and the inspection point marker set with reference to both the reference points. At a position where you can capture the inspection point of the actual pattern specified by
Navigation means for moving the field of view of the image input means, and the field of view moved by the navigation means,
In the same manner, the above-mentioned problem can be solved by providing an image measuring unit that fixes the inspection point at a position where the physical image can be captured, and image-processes the input image to measure the size of the actual pattern. Is the solution.

That is, in the inspection point marking method according to the first aspect of the present invention, when a part of the actual product (product) pattern is optically photographed and the size is inspected, the CAD data which is the design data of the actual pattern is added. Since the inspection point marker for specifying the inspection point (inspection point) desired to be inspected for the actual product is set, when the CAD data in which the marker is set is taken in order to inspect the actual pattern, It can be used as a guide.

Therefore, by setting the inspection point marker on the CAD data as described above, the conventional optical automatic dimension measuring machine shown in the above (3) can be obtained only by performing a simple process such as format conversion on the data. Since it can be used as teaching data for automation of an existing measuring device such as, it is possible to eliminate the conventional troublesome programming work for automation.

Further, in the automatic dimension inspection method according to the third aspect, the CAD data in which the inspection point markers are set by the method according to the first aspect is used as a navigator when optically inspecting the inspection point of the actual pattern. Since it can be used, it is possible to automatically perform dimension inspection only on a desired portion.

Further, in the automatic dimension inspection apparatus of the sixth aspect, the automatic dimension inspection method of the third aspect can be surely executed.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a CAD of one embodiment according to the present invention.
It is a block diagram showing a schematic structure of a system (automatic dimension inspection device).

The CAD system is a sample (actual product).
A sample mounting device 30 for mounting a sample, an optical microscope 32 for enlarging a sample set in the mounting device 30, a CCD camera 34 for receiving an image observed by the microscope 32 and converting it into a color video signal, and the CCD An image processing device 36 for processing a color video signal from the camera 34,
A TV monitor 38 capable of color-displaying image data processed by the image processing device 36, and a raster / vector conversion function for generating CAD data from image data input from the image processing device 36 in addition to a normal drawing function. Or 2
An engineering workstation (EW) that constitutes a CAD device having the functions of superposing the above CAD data, mutual positional movement (shift) between them, and dimension measurement.
S) 40.

Further, in the above CAD system, the sample mounting device 30 includes a manual rotary stage 42 having a sample mounting portion (not shown), an XY stage 44 for moving the sample in the plane direction, and a sample in the vertical direction. The XY stage 44 and the Z stage 46 are configured to move, and the XY stage 44 and the Z stage 46 operate by receiving a command from the workstation 40 via the interface RS232C.
The Y stage controller 48 and the auto focus controller 50 are driven and controlled respectively. Further, a laser position detector is attached to the XY stage 44, and the position measurement in the XY directions is performed by a laser scale counter 52 which is also operated by a command from the workstation 40, and the measured value is fed back to the workstation 40. Then, the position measurement value of the XY stage 44 is corrected by the XY stage controller 48.

Further, the autofocus controller 5 described above
An image signal used for autofocus is directly input to CCD 0 from the CCD camera 34, and an autofocus monitor (not shown) separately provided with an image captured through the microscope 32. It is possible to directly view the image on the TV monitor 38 from the autofocus controller 50 by using the monochrome (B /
The video signal of W) is input.

FIG. 2 shows the mounting device 30 and the optical microscope 3.
2 is a perspective view showing the appearance of the CCD camera 34 and the CCD camera 34,
The XY stage 44 shown in FIG.
An X drive motor 54 which is composed of an A stage and a Y stage 44B and is connected to the stage controller 48.
The A and Y drive motors 54B are movable in the X and Y directions, and the rotary stage 42 for mounting the sample is mounted on the Y stage 44B so that it can be manually rotated.

In addition, the X stage 44A and the Y stage 44
Scale patterns 56A and 56B each made up of a fine diffraction grating are attached to the side surface of B, and laser light is used to scale the positions of both stages 44A and 44B moved by the X drive motor 54A and Y drive motor 54B. , 56B are provided with an X position detector 58A and a Y position detector 58B for irradiating and detecting the laser scale counter 5B.
2 are connected.

Further, the Z stage 46 is arranged below the X stage 44A, and the Z stage 46 can be moved back and forth in the vertical direction by a Z drive motor 54C. It is connected to the auto focus controller 50, and the distance between the objective lens 32A of the optical microscope 32 and the sample is increased or decreased based on a control signal from the controller 50 to perform auto focus on the microscope 32. There is.

Below the Z stage 46, a transmissive light source unit 60 which also serves as a support is arranged.
0 has a built-in transmissive light source (not shown) that projects light from below onto the microscope 32, and a transmissive light source switch 60A and a light amount adjusting volume 60B are attached to its side wall.

Further, an epi-illumination light source unit 62 is attached to the microscope 32, an epi-illumination light source (not shown) is built in the unit 62, and an epi-illumination light source switch 62A and a light quantity adjusting volume 62B are provided on a side wall of the unit 62. And are attached.

Therefore, when capturing the microscopic image of the sample with the CCD camera 34, it is possible to use at least one of the light source of transmission and epi-illumination.

Next, the image processing device 36 will be described with reference to FIG.
The features of the configuration and the processing function will be described. The processing device 36 has an image input / processing / binarization processing function, for example, S manufactured by Seiko Denshi Kogyo Co., Ltd.
V-2110 (trade name) can be used.

The image processing device 36 is a CCD camera 3
Each of the R (red), G (green), and B (blue) signals input from 4 can be stored for each screen, and 3 for R image, G image, and B image each surrounded by a rectangle are stored. Monochrome memory for storing one frame memory and Y (luminance) signal
One frame memory for W image and H obtained by processing the R, G, B signals by a 3 × 3 matrix operation unit
(Hue), S (saturation), and V (luminance) image data are stored in the three frame memories for each image of H, S, and V, and the R signal and B signal are processed by the image arithmetic operation unit. A total of eight frame memories of the RB difference image frame memory that stores the difference image data of both obtained as described above are provided.

The reason why such different color signals are used is as shown in the table of FIG. 4 for the actual sample (actual pattern).
Depending on the material used and the type of image required, the type of light source suitable for use and the optimum color signal may differ.

That is, there are two types of original patterns, one for the front and the other for the lead frame, both of which are glass dry plates (the pattern is formed of an opaque film on the glass plate), so that a black and white transmission image is obtained. The frame memory of the B / W image is the optimum plane because it can be obtained with good contrast.

Further, since the plate making pattern is a resist pattern formed on the front and back surfaces of the lead frame,
It depends on the type of metal material and the type of resist, and it is necessary to use a reflected light source to receive the reflected image.

When casein is used as the resist, since the resist has a reddish color at the stage of heat-curing after development, the 42-alloy material of silver-white is used as an optimal plane for the B image frame. Although a memory can be used, the copper (Cu) material itself has a reddish color, and the difference is not clear in the B image. Therefore, the frame memory of the V image is the optimum plane.

When a blue-based dry film is used as the resist, the R image is optimal for 42 alloy, but the frame memory for the RB difference image is optimal for copper material.

In the case of the product pattern after the etching is completed and the resist film is removed, it is possible to receive the penetrating transmission image and the reflection images of both the front and back surfaces, and the transmission image is black and white as described above. / W when the image is a reflection image, H
(Hue) The image becomes the optimum plane.

Further, among the product patterns, when the fixing tape 22 (referred to as TP in the table) made of a polyimide resin is attached to the inner lead as shown in FIG. 22, the tape is red. Since the transparency is high in the system, in order to obtain a completely transparent image where the image is not input on the tape, B
The / W image becomes the optimum plane. However, it is necessary to appropriately set a threshold value for binarization described later.

On the other hand, in order to capture a transmission image including the tape, blue which is opaque to the tape is suitable, so the B image becomes the optimum plane.

Furthermore, when only the tape portion is desired to be photographed, the H image becomes the optimum plane for the reflection image using the epi-illumination light source.

As described above, when the optimum plane to be used is selected according to the object to be captured as an image, the corresponding image signal is input from the eight frame memories to the binarization processing section. Binarization processing is performed on the image data input by the binarization processing unit. The threshold value set at that time can be arbitrarily set from the gradation values of 0 to 255, for example.

Morphology processing for removing black spots or white spots on the image, which are caused by fine roughness of the surface of the actual pattern, etc., on the image data binarized by the binarization processing section. I do. However, in the case of a transmission image, such a spot does not occur, so that it is not necessary to perform it.

Whether the spot to be removed is white or black is set, a predetermined number of morphologies is set, and the image is expanded / contracted the number of times to remove the spot.

Next, the binary image obtained by performing the above processing is the workstation 4 which functions as a CAD device.
0, where the binary image is processed by the raster / vector conversion unit and converted into CAD data. As the workstation 40, normal CAD software (for example, CAD software Medusa (trade name) manufactured by Computer Vision Co., Ltd.) and actual matching CAD software (proposed by Japanese Patent Application No. 7-5340) operate, for example, by Sun Microsystems. Sparc Station 10 (trade name) can be used.

The raster / vector conversion section converts a general outline of CAD data and a method of converting image data in a white or black area into CAD data in a trapezoidal area, although detailed description thereof will be omitted. There is. When the signal conversion processing is performed by this raster / vector conversion unit, the RV vertex thinning coefficient for determining the accuracy of linear approximation is set. The smaller this coefficient is, the less jagged the line is in the case of the outline, and the finer the trapezoid can be extracted in the case of the trapezoid area.

When selecting either of the above two conversion methods and the trapezoidal area conversion method,
It is necessary to select either white or black and determine the target area for trapezoidal area processing.

Further, as described above, the CAD system of this embodiment enhances the actual pattern of the product processed based on the CAD data of the product design dimension pattern, which is composed of the hardware mechanism shown in FIGS. 1 and 2. The workstation 40 is provided with an image input means for inputting an image with high accuracy and a physical collation means for collating the image data of the input physical pattern with the CAD data so as to collate them. Means for setting an inspection point marker for specifying the inspection point at one or more points on the CAD data, and an inspection point of the physical pattern specified by the inspection point marker set with reference to the reference points. Navigation means for moving the field of view of the image input means to a position where the The field of view, the actual pattern image input fixed in a position put take a test point, the image measurement means for performing dimensional measurement of actual pattern by image processing the input image is constructed.

Further, in the present embodiment, the navigation means built in the workstation 40 has a function of making the center of the visual field of the image input means coincide with the centers of gravity of a plurality of inspection point markers, and also the image. A measuring means for converting the marker coordinates of the CAD coordinate system of the inspection point marker set on the CAD data into a visual field coordinate system with the visual field center of the image input means as a reference;
It corresponds to a means for converting an image of the physical pattern in the visual field, which has been input as an image, into a binary image in a state where the center of the visual field coincides with the center of gravity of the inspection point marker, and an actual object existing in the converted binary image. Means for selecting a closed region closest to the visual field center from the closed regions, and extracting a contour of the selected closed region and corresponding a marker on the contour corresponding to the marker coordinates converted into the visual field coordinate system. Means for calculating points,
A means for inversely converting the coordinates of the marker corresponding points in the visual field coordinate system into the CAD coordinate system, the marker coordinates set on the CAD data, and the coordinates of the marker corresponding points inversely converted into the CAD coordinate system are compared. And means for performing dimension measurement.

Further, in the present embodiment, when the navigation means moves the visual field center of the image input means and matches the visual field center with the centers of gravity of a plurality of inspection point markers, based on the actual measurement value of the physical movement amount. The marker coordinates converted into the visual field coordinate system can be corrected.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG. 5 and the like, which shows the overall flow.

First, before starting a specific operation, basic setting and adjustment of system functions are performed. In particular, when the lens of the microscope 32 or the camera 34 is replaced, it is necessary to perform orthogonal adjustment of the camera 34 and the XY stage 44. This is done by manually rotating the camera mount. In this orthogonal adjustment, as shown in the monitor screen in FIG. 6, a small mark (may be a small dust) indicated by an X mark on the sample mounting portion is used as a reference point, and this range does not deviate from the monitor screen. If the reference point does not deviate from the reference line (horizontal line) on the monitor when it is horizontally moved in the left and right X directions, it can be performed by setting OK.

Further, in order to provide the image measuring function, it is necessary to measure the size per pixel and the screen feed pitch. This is one screen size (512 ×
In measuring the stage feed value corresponding to 480 pixels), specifically, FIG.
As shown in, the reference points indicated by X are moved to four points on the reference line at positions of ¼ and 3/4 in both the X direction and the Y direction on the screen, and the X direction at that time, The stage moving distance in the Y direction is determined by the laser scale counter 5
It is possible to measure with high accuracy by using the count value of 2. In this case, the size per pixel is Xs /
256, Ys / 240, and the screen feed pitches in the X and Y directions are calculated as 2Xa and 2Ys.
For the measurement of the above dimensions and pitch, a laser scale counter is not used, and the feed amount by the XY stage drive motor (step motor) (the minimum unit is, for example, 1 μm).
m) may be used.

Assuming that the above preparatory operation has been completed, the following processing is executed according to the flow chart of FIG.

First, in step S10, image processing conditions are set. Here, operations such as (1) material setting, orthogonal correction, (2) island center measurement, (3) AF condition, and image processing condition setting are executed, and the results are stored in setting files XY, SV, and AF, respectively. .

Then, in step S20, the inspection point is marked. Here, on the CAD data of the product design dimension pattern corresponding to the design drawing of the lead frame (hereinafter, also simply referred to as CAD data), 4 is set for each inspection point.
One point is set as an inspection point marker, and its coordinates are stored in the setting file PNT.

Then, in step S30, automatic dimension inspection is performed. Here, the camera visual field is navigated with the inspection point specified by the marker set in step S20 as the target position, and while inputting the image, the dimensional inspection for each inspection point is automatically executed, and the result is displayed. It is stored in the setting file INS and is output as a table or graph.

The process of steps S10 to S30 will be described in more detail. Setting the image processing conditions in step S10 is as follows.
It is executed according to the flowchart of steps S1 to S6 shown in FIG.

That is, the sample is set in step S1. Specifically, as shown in FIG. 2, the sample (lead frame) is attached to a predetermined position of the rotary stage 42, and an image of the sample taken by the operator from the camera 34 displayed on the monitor 38 is displayed. While watching, the rotary stage 42 is operated to perform orthogonal adjustment of the sample.

If the monitor screen displaying the horizontal edge of the sample input by the CCD camera 34 whose orthogonal adjustment with the XY stage 44 has already been completed is as shown in FIG. When the rotary stage 42 is manually rotated to a position where the above-mentioned edge does not deviate from the horizontal reference line even when largely moved in the X-axis direction,
The orthogonal adjustment between the sample and the XY stage 44 is performed.

Then, in step S2, the light source to be used is selected and its light amount is adjusted. That is, the switch 60A or 6
A transmission light source or an epi-illumination light source is selected by turning on any of 2A. The desired light source is selected, and the light amount is adjusted by the light amount volume of 60B or 62B so that the brightness signal falls within the specified range by looking at the monitor of the autofocus device. In some cases, both light sources can be used at the same time.

Next, in step S3, the orthogonality of the sample is measured in order to make a more accurate correction based on the measured value. Here, similarly to the island center measurement described below, the coordinates of two points that are considered to be horizontal and two points that are considered to be vertical are measured.

FIG. 10 shows the above two measurement points H1 and H.
2, V1, V2 and the field of view of the CCD camera 34 at the time of capturing the image of each point, and the shaded portion corresponds to the frame (actual). Here, two horizontal points H1 and H
The point on the edge of the frame is set to 2 and the vertical two points V
1 and V2, points on the edge of the vertical groove provided to promote etching are used. In this step, it is premised that the orthogonality of the material is already adjusted as much as possible by operating the rotary stage or the like in step S31. That is, the edge that was seen near the center of the field of view at the point H1 is seen almost at the center when the stage is moved in the horizontal direction and the field of view is moved to the point H2. Keep it down. Although it corrects, it is not preferable that the orthogonality deviates from the field of view.

The coordinates of the four points measured under the above conditions are H1 (X _H1 , Y _H1 ), H2 (X _H2 , Y _H2 ) V1 (X _V1 , Y _V1 ), V2 (X _V2 , Y _V2 ) and the coordinates of the center of the island to be calculated next are (Xc,
Yc), the measurement coordinates (x, y) of the point represented by P in FIG. 10 are obtained as (x ', y') corrected by the following equations (1) and (2).

X ′ = − {(X _V2 −X _V1 ) / (Y _V2 −Y _V1 )} × (y−Yc) + x (1) y ′ = − {(Y _H2 −Y _H1 ) / (X _H2− X _H1 )} × (x−Xc) + y ... (2)

After the measurement for orthogonal correction in step S33 described above is completed, the island center is designated in step S4, the AF condition is set in step S5, and the image processing condition is set in step S6.

In steps S4 to S6, a menu is selected on the menu screen displayed on the monitor screen (each can be displayed on the same screen as a window) as schematically shown in FIGS. 11 to 13, for example. It is executed by

First, in step S4, the center of the island (die pad) captured as an image is designated (origin calculation) using the origin calculation function of the apparatus of this embodiment.

In this embodiment, the island 10 is shown in FIG.
And the monitor screen on the right side thereof, the point P _{T at} the upper end of the island 10 and the point P _B at the lower end of the island 10 should be input so as to coincide with the center of the camera input screen in the Y-axis direction. According to the respective Y coordinate values Y _T , Y
_B is calculated, and by inputting the point P _L on the left end and the point P _R on the right end at the center of the screen in the X direction, the X coordinate values X _L and X _R are calculated. ing. Therefore, from the coordinate values of the edge positions corresponding to the boundaries of these four black and white areas (the black parts are indicated by diagonal lines),
Coordinates of the center of the island (Xc, Y
c) is calculated by the following equation.

Xc = (X _R + X _L ) / 2, Yc = (Y _T + Y _B ) / 2 (3)

Since the CAD system of this embodiment has an edge detection function and is capable of automatically recognizing edges, the edges of the black and white borders on the left, right, top, and bottom are defined as the X coordinate and the Y on the screen as described above. Even if it does not match the center of the coordinates, simply capture each edge part in the screen, the coordinate value of each edge is detected, the calculation is automatically executed by the above formula,
Similar center designations can be made. By specifying the center of the island of the input image in this way, the center of the island of the design pattern of the CAD data can be aligned with the center of the island, so that the overlay display can be accurately performed.

Normally, the lead frame for one chip is basically symmetrically designed with the center of the island as the origin, so the CAD data is described (designed) with the center of the island as the origin, or Since the coordinates are clearly shown in the data, by making the origin calculated by the above-mentioned method coincide with the center of the island of the CAD data on the CAD device, the dimensional difference is large, for example, the processing size pattern and the etching pattern, It becomes possible to perform accurate alignment automatically.

Information about the center of the island and the shooting area on the image designated in steps S3 and S4 is stored in the setting file XY.

Then, in step S5, conditions for autofocus (AF) are set. Here, the mode is selected and the limit value is set. In this mode, one reference point (position) is determined in the Z-axis direction applied to a flat sample, and the 2WAY method in which the Z stage 46 is finely moved vertically to focus on the reference point, and a surface with large unevenness is used. Z stage 4 up to a predetermined lower position beyond the focal point to be applied
From the state where 6 is lowered, the stage 46 is gradually raised to bring the sample closer to the lens and focus 1 WAY
There is a system and selection of a lens to be used from objective lenses (five types in this embodiment).

The limit is an approach limit distance set to prevent a collision between the lens and the sample during autofocus. In addition, here, 1 WAY is used for the product sample with severe unevenness as the mode, and 2 W when it is not.
Select AY, use a 20x objective lens as a lens to capture with a resolution of 1 μm / 1 pixel, and use a focus parameter setting file for that. 2 mm from the origin as the limit value, the maximum value of the focus working distance is 1 limit. Set a normal default value such as "/ 2". The conditions set in this step are stored in the setting file AF.

When the 2WAY method is selected as the AF mode, the edge portion (flat portion) of the sample is brought into the screen, and the auto focus is activated or the Z stage 46 is manually moved to determine the focus origin. (Z coordinate value of the reference point) is also set. The autofocus is executed by moving the Z stage 46 up and down slightly with reference to this position as described above.

In the next step S6, conditions for image processing are set. The contents of the selection are the selection of the input plane to be used from the eight types of image frame memories shown in FIG. 3 that use different colors, the setting of the binarization threshold value when creating a binary image, white or black. Is a morphological condition for removing unnecessary points in the image data. The conditions set in this step are stored in the setting file SV.

Next, marking of inspection points (inspection points) executed in step S20 will be described with reference to FIG. FIG. 15 is a CAD screen in which the design CAD data of the lead frame is enlarged and displayed, and P1 and P2 in the figure are shown.
Indicates an inspection point at the tip of the inner lead on the CAD data.

In this embodiment, only the inner lead tip portion is used as an inspection point, and four inspection point markers 1 to 4 are set to specify the inspection point. Do this for as many pins as you need.

In the case of the inner lead, the vertex data on the CAD data can be used as it is for the two leading ends of the points 1 and 2. Points 3 and 4 are intersections of both edges of the lead and a straight line that passes through the bonding position (BP) at the center of both and is parallel to the tip side passing points 1 and 2. Since the bonding position is known information specified on the CAD drawing, each of the points 3 and 4 can be easily obtained.
Therefore, the above four points on the lead tip can be automatically marked.

Next, the automatic dimension inspection in step S30 performed after the above-mentioned marking is completed will be described by taking the case where the inspection point is P2 shown in FIG. 15 as an example.
In the following description, x and y are CAD coordinate systems with the center of the island as the origin, X and Y are stage coordinate systems on the XY stage, and U and V are the horizontal and vertical directions of the visual field of the camera. The dimensions u and v respectively represent the visual field coordinate system with the origin of the visual field center of the camera.

First, in the CAD coordinate system, the coordinates (x ₁ ,
y ₁ ), (x ₂ , y ₂ ), (x ₃ , y ₃ ), (x ₄ , y
The center of gravity (x _G , y _G ) of the inspection point is obtained from ₄ ) by the following equations (4) and (5).

X _G = (x ₁ + x ₂ + x ₃ + x ₄ ) / 4 (4) y _G = (y ₁ + y ₂ + y ₃ + y ₄ ) / 4 (5)

Next, the navigation for moving the XY stage is executed so that the center of the visual field of the camera 34 coincides with the center of gravity (x _G , y _G ) and the image of the actual pattern is input in a state where the two coincide. This allows the marker 1
All of ~ 4 can be put in the screen surely.

FIG. 16 shows an actual pattern in which an image is input with the center of the field of view coinciding with the center of gravity (x _G , y _G ) and the field of view of the camera is U × V. The stage movement coordinates (X, Y) corresponding to the center of the visual field at this time are given by the following equation (6) using the island center coordinates (Xc, Yc).

X = Xc + x _G , Y = Yc + y _G (6)

Next, the marker coordinates of each of the points 1 to 4 in the CAD coordinate system are converted into a visual field coordinate system set with the visual field center of the camera as the origin. The coordinates of the visual field coordinate system of the points 1 to 4 are (u ₁ , v ₁ ), (u ₂ , v ₂ ), (u ₃ , v
₃ ) and (u ₄ , v ₄ ).

In the actual coordinate conversion, if an error occurs when the stage is moved, the correction is also performed at the same time. That is, after the stage is moved, coordinates are measured by the laser scale counter 52 and orthogonal correction is performed. As a result, as shown in FIG. 17, the center coordinates (X, Y) on the stage shown in the equation (6) are actually calculated. Is (X ', Y'), the marker coordinate (x ₁ , y ₁ ) of the above point 1 in the CAD coordinate system is expressed by the following equations (7) and (8) in the visual field coordinate system. By converting with
It can be corrected at the same time. Note that M is the number of pixels in the horizontal direction of the camera 34, and N is the number of pixels in the vertical direction. Here, M = 512, N = 480, V = 496 mm, V = 464.
mm.

U ₁ = (M / U) {x ₁ −x _G − (X′−X)} + M / 2 (7) v ₁ = − (N / V) {y ₁ −y _G − (Y ′ −Y)} + N / 2 (8) (Y-axis upside down) (u ₂ , v ₂ ), (u ₃ , v ₃ ), and (u ₄ , v ₄ ) have the coordinates (7) above. , (8) can be obtained by the same formula.

Note that the Y-axis upside-down of the above equation (8) is generally the same as the CAD system even though the upper side is the origin in the pixel system in a camera.
In the coordinate system, the bottom is for the origin, so in the Y-axis direction −
This means that the image is multiplied by 1 and inverted.

Next, the input image is a binary image (not shown).
And selecting only the closed region (non-hole part of the actual pattern) having the center of gravity closest to the center of the visual field from the binary image, and the upper and lower parts partially displayed in FIG. The physical pattern in is removed, and contour extraction is executed only for the selected central closed region. FIG. 18 shows the contour of the closed region thus extracted.

The center of gravity of the closed region is calculated as an average value of all black dots forming the closed region by using the center of gravity calculation processor of the image processing device 36. However, if the contour line is obtained, it may be obtained as an average of points on the line.

Next, it corresponds to the marker on the CAD data.
The minimum distance from four points 1 to 4 in the visual field coordinate system
1'to 4'on the contour are obtained as the marker corresponding points, and each coordinate is
(U ₁', V₁′), (U_Two', V_Two′) 、 (U_Three′,
v_Three′), (U_Four', V_Four′) This calculation is
It can be automatically executed by image processing.

Then, the coordinates of the marker corresponding points 1'to 4'are inversely transformed from the visual field coordinate system to the CAD coordinate system.
This inverse transformation transforms (u ₁ ′, v ₁ ′) into (x ₁ ′,
y ₁ ′), the above (7), (8)
Can be performed by the following equations (9) and (10) corresponding to the modified equation. Other (u ₂ ′, v ₂ ′) to (u ₄ ′, v
₄ ′) is also inversely transformed by the same formula, and the corresponding (x ₂ ′,
Each coordinate of y ₂ ′) to (x ₄ ′, y ₄ ′) can be obtained.

X ₁ ′ = (U / M) (u ₁ ′ −M / 2) + x _G + X′−X−Xc (9) y ₁ ′ = (V / N) (N / 2−v ₁ ′) ) + Y _G + Y'-Y-Yc ... (10)

FIG. 19 shows (x ₁ ′, y ₁ ′) to
Marker corresponding points ₁ ′ to ₄ ′ having coordinates (x ₄ ′, y ₄ ′) are replaced with 1 to 4 having coordinates (x ₁ , y ₁ ) to (x ₄ , y ₄ ). FIG. 1 shown with the marker coordinates.
5 is a CAD screen corresponding to 5.

When the coordinates are obtained on the CAD coordinates in this way, the markers 1 to 4 and the marker corresponding points 1'to
The distances L _{1 to} L ₄ with 4 ′ are calculated. L ₁ can be calculated by the following equation (11), and L _{2 to} L ₄ can be calculated by the same equation.

[0102] _{L 1 = {(x 1 '} -x 1) 2 + (y 1' -y 1) 2} 1/2 ... (11)

When the calculation of L _{1 to} L ₄ is completed as described above, the measurement data as shown in the following Table 1 is created for the inspection point No. 2, and this is output to a file. In addition,
In the table, the Z value is the Z coordinate value based on the center of the island, which is obtained by the autofocus executed when the image is input.

[0104]

[Table 1]

With respect to other inspection points designated in advance, the dimension inspection is sequentially performed by the method described above, and the inspection results are output. The inspection items include the following.

(1) Bonding position CAD: {(x ₃ + x ₄ ) / 2, (y ₃ + y ₄ ) /
2} Physical: {(x ₃ ′ + x ₄ ′) / 2, (y ₃ ′ + y ₄ ′)
/ 2} _{error: (1/2) {(x 3} + x 4 -x 3 '-x 4') 2
_{+ (Y 3 + y 4 -y} 3 '-y 4') 2} 1/2 (2) End width _{CAD: {(x 3 -x 4} ) 2 + (y 3 -y 4) 2} 1/2 in kind _{: {(x 3 '-x 4} ') 2 + (y 3 '-
y ₄ ') ^{2} 1/2} error: the difference between both the (3) the tip _{R {(x 1' -x 1} ) 2 + (y 1 '-y 1) 2} 1/2 {(x 2' - ^{_{x 2) 2 + (y 2}} '-y 2) 2} 1/2 (4) tip top position _{CAD: {(x 1 + x} 2) / 2, (y 1 + y 2) / 2} kind: {(x _{1 '+ x 2') /} 2, (y 1 '+ y 2')
/ 2} _{error: {(x 1 + x 2} -x 1 '-x 2') 2 + (y 1 +
_{y 2 -y 1 '-y 2'} ) 2} 1/2 (5) Z coordinates relative to the floating island center of the lead tip

Regarding the (1) bonding position, the error is represented by the graph of FIG. 20 in which the pin number is plotted on the horizontal axis for all pins, and the graph of FIG. 21 in which the pin number is expressed in a radial pattern of 360 °. Can be output.
In this way, when it is possible to display the error (deviation) of the actual bonding position from the position on the design drawing for all pins, it is necessary to check whether the error is within the allowable position for automatic wire bonding. Can be accurately determined.

The bonding position accuracy affects the load of the wire bonding work which is conventionally performed while performing image processing for each pin, and when the accuracy is high, the image processing can be omitted. It becomes possible to fully automate the work. Therefore, if the accuracy can be guaranteed for all the pins, the efficiency of the bonding work can be significantly improved.

As described in detail above, in this embodiment, an environment capable of image processing in cooperation with CAD is realized,
In the case of a lead frame, CAD based on the center of the island
The data and the actual pattern are positioned, the inspection points are taught on the CAD so that an image can be input, and the inspection points are selectively image-processed by the CAD.
The inspection data can be output while matching the data with the points.

Therefore, according to the present embodiment, the inspection points can be taught by CAD and the CAD data and the image-inspected inspection points can be compared, which improves the efficiency of the teaching work. The quality of the product can be promptly determined from the inspection result.

Further, since the image processing can be selectively performed only at the points necessary for the inspection, as compared with the case where the image is input by designating the area and the whole one visual field is processed.
Greatly improve efficiency.

Further, since the image processing is not performed for all the patterns (closed areas) in the visual field but only the area necessary for the inspection is selected, the processing time can be greatly shortened. .

Further, the teaching data consisting of the inspection point markers set on the CAD data can be converted into a format for the existing optical automatic dimension measuring instrument, for example, to improve the operation rate of the existing machine.

Although the present invention has been specifically described above, the present invention is not limited to the one shown in the above embodiment, and various modifications can be made without departing from the gist thereof.

For example, the product is not limited to the lead frame, and is not particularly limited as long as it is a product manufactured by designing a two-dimensional pattern by CAD.

Further, the marker corresponding point is not limited to the point on the contour which is the shortest distance from the inspection point marker, and may be obtained as a point where a straight line passing through the marker is orthogonal.

[0117]

As described above, according to the present invention,
Since the inspection point marker set on the CAD data can be used as teaching information for inputting a necessary inspection point as an image, point measurement can be performed efficiently, accurately, and automatically.

Further, since accurate dimension measurement can be performed based on the comparison between the inspection point marker set in the CAD data and the actual pattern of the corresponding inspection point input as an image, an accurate error from the design target value can be obtained. Inspection data can be obtained based on the information.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a CAD system according to an embodiment of the present invention.

FIG. 2 is a CAD system sample mounting device, a microscope,
Oblique view showing a CCD camera

FIG. 3 is a block diagram showing a frame memory and a processing function of the image processing device of the CAD system.

FIG. 4 is a diagram showing an optimum input plane for each sample.

FIG. 5 is a flowchart showing the flow of the entire operation of the embodiment.

FIG. 6 is an explanatory diagram showing a monitor screen when the camera and the XY stage are orthogonally adjusted.

FIG. 7 is an explanatory diagram showing a monitor screen when the dimensions per pixel and the screen feed pitch are calculated.

FIG. 8 is a flowchart showing a processing procedure for setting image processing conditions.

FIG. 9 is an explanatory diagram showing a monitor screen at the time of orthogonal adjustment of the sample and the XY stage.

FIG. 10 is an explanatory diagram showing an orthogonal correction method for a sample.

FIG. 11 is an explanatory diagram illustrating a CAD system menu screen.

FIG. 12 is another explanatory diagram illustrating the menu screen of the CAD system.

FIG. 13 is still another explanatory diagram illustrating the menu screen of the CAD system.

FIG. 14 is an explanatory diagram showing an example of a method of designating the center of an island.

FIG. 15 is an explanatory diagram showing a method of setting an inspection point marker.

FIG. 16 is an explanatory diagram showing a state in which an inspection point is input as an image.

FIG. 17 is an explanatory diagram showing a method of converting a CAD coordinate system into a visual field coordinate system.

FIG. 18 is an explanatory diagram showing a method of selecting a closed region and determining a shortest distance point.

FIG. 19 is an explanatory diagram showing a state in which the shortest distance point is inversely transformed into a CAD coordinate system.

FIG. 20 is an explanatory diagram showing a graph display example of a bonding position shift.

FIG. 21 is another explanatory diagram showing a graph display example of the bonding position deviation.

FIG. 22 is a plan view showing an example of a lead frame.

FIG. 23 is an explanatory view conceptually showing the manufacturing process of the lead frame.

[Explanation of symbols]

 30 ... Sample mounting device 32 ... Optical microscope 34 ... CCD camera 36 ... Image processing device 38 ... TV monitor 40 ... Workstation (EWS) 42 ... Rotation stage 44 ... XY stage 44A ... X stage 44B ... Y stage 46 ... Z stage 48 ... XY stage controller 50 ... Auto focus controller 52 ... Laser scale counter 54A ... X drive motor 54B ... Y drive motor 54C ... Z drive motor 56A, 56B ... Scale pattern 58A ... X position detector 58B ... Y position detector 60 ... Transmission Light source unit 60A ... Transmissive light source switch 60B ... Light intensity adjustment volume 62 ... Epi-illumination light source unit 62A ... Epi-illumination light switch 62B ... Light intensity adjustment volume

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Teruaki Iinuma 1-1-1, Ichigaya-Kagacho, Shinjuku-ku, Tokyo Dai Nippon Printing Co., Ltd. (72) Inventor Masataka Yamaji 1-chome, Ichigaya-Kagacho, Shinjuku-ku, Tokyo No. 1 within Dai Nippon Printing Co., Ltd. (72) Inventor Satoshi Watanabe 1-1-1 Ichigayaka-cho, Shinjuku-ku, Tokyo Within Dai Nippon Printing Co., Ltd.

Claims (6)

[Claims] 1. An inspection for specifying an inspection point of an actual pattern when optically inspecting a part of an actual pattern of a product processed based on CAD data of a product design dimension pattern and inspecting the actual pattern. Set the point marker to C above
An inspection point marking method for a microfabricated product, characterized by setting at least one point on AD data. 2. When the product is a lead frame and the inspection location is the inner lead tip, the inspection point marker passes through the two apexes of the CAD data and the bonding position. An inspection point marking method for a microfabricated product, characterized in that a straight line parallel to is set at a total of 4 points including two intersection points intersecting both edges. 3. An inspection for identifying an inspection point of the actual pattern when optically inspecting a part of the actual pattern of the product processed based on the CAD data of the product design dimension pattern and performing the size inspection. Set the point marker to C above
It is set at one or more points on the AD data, and based on the inspection points of the physical pattern specified by the set inspection point markers, a part of the physical pattern is optically photographed and set on the CAD data. An automatic dimension inspection method for a microfabricated product, characterized by performing a dimension inspection based on the inspection point marker and a marker corresponding point on the actual pattern that is input as an image. 4. An image input means for inputting an image of a physical pattern of a product processed based on CAD data of a product design dimension pattern, and an actual product for collating the input image data of the physical pattern with the CAD data. An automatic dimension inspection device for microfabricated products, comprising: collating means; means for calculating a reference point of an actual pattern corresponding to a reference point defined in CAD data; and an inspection point of the actual pattern specified. Means for setting the inspection point marker for the CAD data at one or more points on the CAD data, and the inspection point of the actual pattern specified by the set inspection point marker is photographed with reference to both reference points. The navigation means for moving the visual field of the image input means to the position where the image can be put in, and the visual field moved by the navigation means. An image measuring means for fixing the inspection point to a position where the image can be captured and inputting an image of the actual pattern, and image-processing the input image to measure the dimension of the actual pattern. Automatic dimension inspection device. 5. The navigation means according to claim 4, wherein the navigation means has a function of causing the center of the visual field of the image input means to coincide with the centers of gravity of a plurality of inspection point markers, and the image measurement means sets on the CAD data. In the state where the center of the visual field coincides with the center of gravity of the inspection point marker, the means for converting the marker coordinates of the CAD coordinate system of the existing inspection point marker into the visual field coordinate system with the center of the visual field of the image input means as a reference. , A means for converting the image of the actual pattern in the field of view into the binary image, and selecting the closed region closest to the center of the field of view from the closed regions corresponding to the actual object existing in the converted binary image Means for extracting a contour of the selected closed region and calculating a marker corresponding point on the contour corresponding to the marker coordinates converted into the visual field coordinate system; A means for inversely converting the coordinates of the marker corresponding points of the standard system to the CAD coordinate system, the marker coordinates set on the CAD data, and the coordinates of the marker corresponding points inversely converted to the CAD coordinate system are compared. An automatic dimension inspection device for microfabricated products, comprising: a means for performing dimension measurement. 6. The navigation device according to claim 5, wherein when the navigation means moves the center of the visual field of the image input means and matches the center of the visual field with the centers of gravity of a plurality of inspection point markers, based on the measured value of the physical movement amount, An automatic dimension inspection apparatus for a microfabricated product, comprising means for correcting the marker coordinates converted into a visual field coordinate system.