JP2000311924A - Method and apparatus for visual inspection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the efficiency of a method and an apparatus for visual inspection more by a method wherein respective coordinate positions are collated and the fatal defect and the nonfatal defect of an object are judged. SOLUTION: One input end of a comparison part 27 is connected to the image processing part 26 of an imaging device 25, and the output end of the comparison part 27 is connected to the other input of the comparison part 27. The output of a controller 24 is connected to another input of the comparison part 27, and a coordinate position which is being imaged at present is transmitted from the controller 14. A memory 28 which stores the coordinate position of a defect 5 specified by the comparison part 27 is connected to the output of the comparison part 27. One input of an object-to-be-inspected extraction part 29 which extracts a defect as an object, to be inspected, whose fatal defect and nonfatal defect are to be judged is connected to the output of the memory 28. The output of the object-to-be-inspected extraction part 29 is connected to one input of a judgment part 30 which judges the fatal defect or the nonfatal defect. A design-pattern-data transmission part 31 is connected to the other input of the judgment part 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visual inspection technique, and more particularly to a technique for determining whether or not an object to be inspected is a fatal defect. For example, an integrated circuit including a semiconductor element is manufactured or manufactured. The present invention relates to a technique that is effective for use in inspecting a semiconductor wafer (hereinafter, referred to as a wafer) that is being processed.

[0002]

2. Description of the Related Art Today, semiconductor integrated circuit devices (hereinafter, ICs)
That. )) And the miniaturization of circuit patterns has progressed, and the line width of the circuit patterns has been reduced to about 1 μm or less. In order to manufacture such ICs at a high yield, foreign substances and defects attached to the surface of the wafer are detected,
It is necessary to inspect the size, shape, physical properties, and the like, quantitatively grasp the cleanliness of various semiconductor manufacturing apparatuses and processes, and accurately manage the manufacturing process. Therefore, conventionally, IC
In a manufacturing factory, a wafer appearance inspection method using a wafer appearance inspection apparatus is performed on a wafer as a work in order to accurately manage a manufacturing process.

[0003] As a conventional wafer appearance inspection apparatus, there is one in which identical positions of adjacent chips on a wafer are collated with each other and a coordinate position where a difference signal is output is determined to be defective.

As an example describing a wafer visual inspection apparatus, there is “Nikkei Micro Devices March 1998”, pp. 69-97, published by Nikkei BP Co., Ltd.

[0005]

However, in the above-described wafer appearance inspection apparatus, since the positional relationship between the coordinate position of the defect and the design pattern formed in the chip becomes unknown, the specified defect becomes a fatal defect. Cannot be determined.

An object of the present invention is to provide a visual inspection technique capable of determining whether or not a fatal defect has occurred.

[0007] The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0008]

The outline of a typical invention among the inventions disclosed in the present application is as follows.

That is, the coordinate position of the object to be inspected and the coordinate position of the design pattern data are collated to determine whether the inspected object is fatal or non-fatal.

In the above-described means, if the coordinate position of the object to be inspected and the coordinate position of the design pattern data are collated, and the coordinate position of the object to be inspected is on the pattern, the object to be inspected is Since it is incorporated in the inside (burned), it is determined to be fatal. However, if the coordinate position of the object to be inspected is far from the pattern, the object to be inspected is not incorporated in the pattern, so that it is determined to be a non-fatal defect.

[0011]

FIG. 1 is a flowchart showing a visual inspection method according to an embodiment of the present invention. FIG. 2 is a perspective view showing the appearance inspection apparatus. 3 to 6 are explanatory diagrams for explaining the operation.

In the present embodiment, the visual inspection apparatus according to the present invention compares the same position of adjacent chips on a wafer and recognizes that there is a defect at the coordinate position where the difference signal is output. It is configured as a device 10.

The wafer 1 to be inspected has an I
A DRAM, which is an example of C, is in the process of being built for each chip unit 4, and the chip unit 4 is an orientation flat (hereinafter, referred to as an orientation flat) 3 cut out on the wafer 1.
Are arranged vertically and horizontally. That is,
Chip portions 4 having the same pattern are repeatedly patterned on the wafer 1. The presence of the defect 5 on the first main surface 2 of the wafer 1 causes a defect. Therefore, the defect 5 existing on the first main surface 2 of the wafer 1
And the position, number, size,
Inspection of the shape, quantitatively grasping the cleanliness of various semiconductor manufacturing apparatuses and processes, and accurate management of the manufacturing process are performed. Further, based on the position and size of the defect, the defect 5
Is determined to cause a fatal failure such as disconnection or short circuit of the chip portion 4.

The visual inspection apparatus 10 includes a stage device 11, which includes an XY table 12 for scanning the wafer 1 as an object to be inspected, a Θ table 13 for rotating in the Θ direction, and an automatic It includes a focusing mechanism (not shown) and a controller 14 for controlling them. Then, in order to inspect the entire surface of the wafer 1, the stage apparatus 11 performs XY scanning of the wafer 1. During this scanning, coordinate position information on the wafer 1 as an object to be inspected is sequentially input from the controller 14 to a comparison unit 27 described later.

In this embodiment, an epi-illumination device 20 is provided just above the stage device 11, and the epi-illumination device 20 applies white light 21 as bright-field illumination light to the wafer 1.
A white light irradiating device 22 for irradiating the white light 21, a half mirror 23 for vertically falling the white light 21, and a lens 24 for forming the white light 21 into a spot shape.
Is vertically illuminated onto the wafer 1 as an object to be inspected held on the stage device 11 to perform epi-illumination.

An image pickup device 25 is provided at a reflection position of the epi-illumination device 20. That is, the imaging device 25 is configured by a line sensor in which the solid-state imaging photoelectric conversion elements are arranged in a slender manner, and extends in the Y direction orthogonal to the stage moving direction on the optical axis of the epi-illumination device 20 on the transmission side of the half mirror 23. It is arranged to become. That is, the imaging device 25 captures an image by reflected light in a bright field. The epi-illumination device 20 and the imaging device 25 constitute an image acquisition unit.

One input terminal of the comparison unit 27 is connected to the image processing unit 26 of the imaging device 25, and the output terminal of the comparison unit 27 is connected to the other input terminal of the comparison unit 27. The output terminal of the controller 14 is connected to another input terminal of the comparison unit 27, and the coordinate position currently being imaged is transmitted from the controller 14. further,
A memory 28 that stores the coordinate position of the defect 5 specified by the comparing unit 27 is connected to an output terminal of the comparing unit 27.

At the output end of the memory 28, an inspected object extracting unit for extracting a defect (hereinafter, referred to as an inspected object) as an inspected object for judging a fatal non-fatal defect (hereinafter, referred to as fatal non-fatal). 29 one input terminal is connected,
The output terminal of the inspection object extraction unit 29 is connected to one input terminal of the determination unit 30 that determines whether or not the inspection is fatal. A setting pattern data transmission unit (hereinafter, referred to as a data transmission unit) 31 for transmitting design pattern data of a product to be formed on a wafer to be inspected is connected to another input end of the determination unit 30.

Next, an appearance inspection method according to an embodiment of the present invention using the appearance inspection apparatus 10 having the above configuration will be described with reference to FIGS.

In order to inspect the entire surface of the wafer 1, the stage apparatus 11 executes XY scanning of the wafer 1. During this scanning, coordinate position information on the wafer 1 is sequentially input from the controller 14 to the comparison unit 27. When the coordinate position of the defect 5 comes to the imaging position of the imaging device 25, that is, the incident illumination spot of the incident illumination device 20, the comparing unit 27
Captures an image signal in a bright field from the imaging device 25.
That is, the defect 5 is detected (Step S1).

At the same time, the other input end of the comparison unit 27 is provided with a coordinate position just before the coordinate position currently being imaged by one chip unit 4, that is, a chip adjacent to the chip unit 4 where the defect 5 exists. An image signal (delay signal) for the same coordinate position as the position of attachment of the defect 5 in the unit 4 is input. The comparison unit 27 calculates the difference between the signals at both input terminals. Here, since the signals at the same positions of the adjacent chip units 4 and 4 are the same, the comparing unit 27 determines that the defect 5 does not exist when there is no difference, and determines the defect 5 when there is a difference. It is determined that it exists. If it is determined that the defect 5 exists, the comparing unit 27
Indicates a defect 5 based on coordinate position information from the controller 14.
Is specified (step S2). The comparing unit 27 sequentially stores the coordinate positions of the defect 5 in the memory 28.

As described above, the defect 5 in each chip portion 4 is detected, the coordinate position is sequentially specified, and the coordinate position is sequentially stored in the memory 28. For example, the memory 28
When the defect data for one chip portion is stored in the inspection target extraction unit 29, the inspection target extraction unit 29 extracts the inspection target to be determined as fatal or non-fatal (step S3). For convenience of explanation, here, as shown in FIG.
It is assumed that a, 5b, 5c, and 5d have been extracted.

The inspection object extraction unit 29 sets the total number K of the extracted inspection objects to the reference value side of the counter (step S4).

The coordinate values (Xa, Ya) of the first inspection object 5a shown in FIG. 3B are input to one input terminal of the determination unit 30 (step S5). At the same time, "1" is added to the count value side of the counter (step S6).

On the other hand, the coordinates of the design pattern shown in FIG. 3A are input from the data transmission unit 31 to another input terminal of the determination unit 30 (step S7).

The determination unit 30 determines the coordinate value (X
It is determined whether (a, Ya) overlaps with the coordinates of the design pattern (step S8). As shown in FIG. 3C, when the coordinate value of the first inspection object 5a overlaps with the pattern coordinates, the determination unit 30 determines that the first inspection object 5a is fatal and does not overlap. In this case, the first inspection object 5a is determined to be non-fatal (step S9).

After the determination, it is compared whether or not the count value n of the counter is equal to the reference value K (step S10). If they are equal, it is determined that the fatal / non-fatal determination has been completed for all the inspected objects, and the process ends. If they are not equal,
Returning to step S5, the above-described routine is repeated.

In the example shown in FIG. 3, the first test object 5a is fatal, the second test object 5b is non-fatal, the third test object 5c is fatal, and the fourth test object 5c is fatal. 5d is determined to be fatal.

The result of non-lethality of the object to be inspected determined as described above is transmitted from the determination unit 30 to the host computer 32. The host computer 32 appropriately prepares various analysis materials shown in FIGS. 4 to 6 by using the coordinate position data of the inspection object and the fatal non-fatal data from the determination unit 30, Output in a timely manner by such an output device. The operator can accurately and quickly manage the IC manufacturing process based on the output various analysis data.

FIG. 4 is a map diagram showing the distribution of defects on the wafer, and is created from fatal non-lethal data and defect coordinate position data. FIG. 4A shows the entire defect map, and FIG.
(B) is a map for simultaneously displaying fatal and non-fatal defects, and FIG.
4 shows a fatal defect map, and FIG. 4D shows a non-fatal map.

FIGS. 5A and 5B are time series transition graphs of the fatal / non-fatal determination. FIG. 5A is a bar graph, and FIG. 5B is a line graph.

As shown in FIG. 5A, when a fatal part of the graph is designated, a fatal defect map is displayed. When a non-fatal part of the graph is designated, the non-fatal map is displayed. It is displayed.

FIGS. 6A and 6B are process tracking graphs for the non-fatal judgment, in which FIG. 6A shows all the cases of the non-fatal case, FIG. 6B shows the case of the non-fatal case, and FIG. .

As shown in FIG. 6B, when a fatal part of the graph is designated, a fatal defect map is displayed, and as shown in FIG. When a fatal part is designated, a non-fatal map is displayed.

According to the above embodiment, the following effects can be obtained.

1) By collating the coordinate position of the object to be inspected with the design pattern data, it is possible to determine whether or not the detected object to be inspected is a fatal defect, thereby contributing to an improvement in the yield at an early stage. it can.

2) By providing inspection data directly related to the defect density reduction of the yield model in the probe inspection, it is possible to judge in a short time the point of yield improvement and the right or wrong of a measure.

3) Since the yield rate and defect density of the inspection wafer can be calculated, the utilization efficiency of the appearance inspection method can be further improved.

4) By using the coordinate position data and the fatal / non-fatal data, various analytical materials can be created as desired and output in a timely manner by an output device such as a monitor or a printer. According to the various analysis data obtained, the IC manufacturing process can be managed accurately and quickly.

FIG. 7 is a flowchart showing an appearance inspection method according to the second embodiment of the present invention. FIG. 8 is an explanatory diagram for explaining the operation.

This embodiment is different from the above embodiment in that
The point is that an image signal of a normal chip pattern is used instead of the design pattern data. That is, FIG.
The image signal of the normal chip pattern shown in (a) is input from the data transmission unit to the determination unit as shown in FIG. 7 (step S7).

In step S8c, it is determined whether the coordinates of the object to be inspected are within the peak to peak of the differential signal of the normal chip pattern. If it is within peak to peak, it is determined to be fatal, and if it is not within peak to peak, it is determined to be non-fatal (step S9).

After the determination, it is compared whether or not the count value n of the counter is equal to the reference value K (step S10). If they are equal, it is determined that the fatal / non-fatal determination has been completed for all the inspected objects, and the process ends. If they are not equal,
Returning to step S5, the above-described routine is repeated.

FIG. 9 is a flowchart showing an appearance inspection method according to the third embodiment of the present invention. FIG. 10 is an explanatory diagram for explaining the operation.

This embodiment is different from the above embodiment in that
The point is that an image signal of a normal chip pattern is used instead of the design pattern data, and size data is used in addition to the position data of the inspection target. That is, FIG.
The image signal of the normal chip pattern indicated by 0 (a) is input from the data transmission unit to the determination unit as shown in FIG. 9 (step S7).

In step S8c, it is determined whether the coordinates of the object to be inspected are within the peak to peak of the differential signal of the normal chip pattern. If not within peak to peak, it is determined to be non-fatal. If it is within peak to peak, the process proceeds to step S8d.

In step S8d, d> L + 2 ×
(P−L) is determined. Here, d is the size of the defect 5 as shown in FIG. L is the pattern width, peak t as shown in FIG.
o Corresponds to the peak width. p is the pitch of the pattern.
If it is larger, it is determined to be fatal, and if it is smaller, it is determined to be non-fatal (step S9).

After the determination, it is compared whether or not the count value n of the counter is equal to the reference value K (step S10). If they are equal, it is determined that the fatal / non-fatal determination has been completed for all the inspected objects, and the process ends. If they are not equal,
Returning to step S5, the above-described routine is repeated.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments and can be variously modified without departing from the gist thereof. Needless to say, there is.

For example, when a defect is detected and a position is specified by comparing detection data at the same position in a repetitive pattern, the data for comparison is not limited to the detection data of an adjacent chip, but is stored in advance. Design pattern data or standard pattern data may be used.

The detection of defects is not limited to being performed by photographing in a bright field, but may be performed by detecting scattered light in a dark field.

The identification of the defect is not limited to the determination by comparing the detection data at the same position in the repetitive pattern, but may be performed by means for detecting the scattered light in the dark field by the light shielding element.

The imaging device is not limited to using a line sensor, but may be a photo sensor, an area sensor, an imaging tube, or the like.

In the above description, the case where the invention made by the present inventor is mainly applied to the wafer appearance inspection technique, which is the field of application as the background, has been described. The present invention can be applied to all visual inspection techniques for panels and the like.

[0055]

The effects obtained by typical aspects of the invention disclosed in the present application will be briefly described as follows.

By comparing the coordinate position of the inspection target with the coordinate position of the design pattern data to determine whether the inspection target is a fatal defect or a non-fatal defect, the efficiency of the appearance inspection method and apparatus is further improved. Can be.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a visual inspection method according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the appearance inspection apparatus.

FIG. 3 is an explanatory diagram of an action of judging fatality and non-fatality;
(A) shows the design pattern, (b) shows the position of the inspection target, and (c) shows the state after the judgment.

4A and 4B are map diagrams showing distributions on a wafer to be inspected, wherein FIG. 4A is a map of all defects, FIG. 4B is a simultaneous display map of fatal non-fatal defects, FIG. ) Indicate non-lethal maps, respectively.

FIG. 5 is a time-series transition graph of fatal non-fatal determination,
(A) is a bar graph and (b) is a line graph.

FIG. 6 is a process tracking graph of fatal non-fatal determination,
(A) shows all cases of fatal non-fatal, (b) shows the case of non-fatal, and (c) shows the case of fatal.

FIG. 7 is a flowchart illustrating an appearance inspection method according to a second embodiment of the present invention.

FIG. 8 is an explanatory diagram for explaining the operation.

FIG. 9 is a flowchart illustrating an appearance inspection method according to a third embodiment of the present invention.

FIG. 10 is an explanatory diagram for explaining the operation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wafer (inspected object), 2 ... 1st main surface, 3 ... Orifice flat, 4 ... Chip part, 5 ... Defect, 5a, 5b, 5c, 5d
... Inspection object, 10 ... Appearance inspection device, 11 ... Stage device, 12 ... XY table, 13 ... ΘTable, 14 ... Controller, 20 ... Epi-illumination device, 21 ... White light (bright field illumination light), 22 ... White Light irradiation device, 23 half mirror, 24 lens, 25 imaging device, 26 image processing unit, 27 comparison unit, 28 memory, 29 inspection object extraction unit, 30 determination unit, 31 data transmission Unit 32: Host computer.

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2G051 AA51 AB02 BB03 BB11 CA03 CB01 DA08 EA08 EA11 EA14 EB01 EB09 EC01 ED12 ED13 ED23 4M106 AA01 AA07 AB07 BA04 CA39 CA50 DA15 DB04 DB19 DB21 DB30 DJ03 DJ04 DJ06 DJ11 DJ13 5B057 AA03 CH08 DA03 DA07 DB02 DC36

Claims (10)

[Claims] 1. A visual inspection method characterized in that a coordinate position of an object to be inspected and a coordinate position of design pattern data are collated to determine a fatal defect or a non-fatal defect of the inspected object. 2. The method according to claim 1, wherein whether or not the coordinates of the design pattern data overlap with the coordinate position of the inspection target is determined to determine whether the inspection target has a fatal defect or a non-fatal defect. Appearance inspection method. 3. An appearance inspection apparatus characterized in that a coordinate position of an object to be inspected and a coordinate position of design pattern data are collated to determine a fatal defect or a non-fatal defect of the inspected object. 4. A determination unit for determining whether the coordinates of the design pattern data overlap the coordinate position of the inspection target to determine whether the inspection target is a fatal defect or a non-fatal defect. The visual inspection device according to claim 3. 5. An appearance inspection method, wherein a coordinate position of an inspection target and a coordinate position of a normal pattern are collated to determine whether the inspection target is a fatal defect or a non-fatal defect. 6. The method according to claim 5, wherein whether the coordinates of the object to be inspected are within the peak to peak of the differential signal of the normal pattern is compared to determine whether the object to be inspected is fatal or non-fatal. Visual inspection method described. 7. A comparison is made as to whether the coordinates of the inspection object are within the peak to peak of the differential signal of the normal pattern,
The appearance inspection method according to claim 5, wherein the relationship between the size of the inspection target and the width and pitch of the normal pattern is compared to determine whether the inspection target is a fatal defect or a non-fatal defect. 8. An appearance inspection apparatus characterized in that a coordinate position of an object to be inspected and a coordinate position of a normal pattern are collated to determine a fatal defect or a non-fatal defect of the inspected object. 9. A visual inspection method, wherein a coordinate position of an inspection target and a coordinate position of a pattern obtained at the time of inspection are collated to determine a fatal defect or a non-fatal defect of the inspection target. . 10. An appearance inspection apparatus characterized in that a coordinate position of an object to be inspected is collated with a coordinate position of a pattern obtained at the time of inspection to determine a fatal defect or a non-fatal defect of the inspected object.