JP2002198406A - Appearance inspecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a pattern inspection and to improve a work efficiency. SOLUTION: A region where a repeated pattern 6b exists is calculated based on the information of the pitches PX, PY of the repeated pattern 6b, and two image signals of the repeated pattern 6b are compared with each other in the calculated region to thereby inspect the appearance of the repeated pattern 6b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pattern inspection technique, and more particularly to a technique effective when applied to a pattern inspection technique for a semiconductor integrated circuit device.

[0002]

2. Description of the Related Art For example, a pattern inspection technique for inspecting the appearance of a predetermined pattern formed on a semiconductor integrated circuit device is described in "CAD AS THE FOUNDATION for Quality Assurance in VSI Fabrication (CAD AS THE)".
FOUNDATION FOR QUALITY AS
SURANCE IN VLSI FABLICATI
ON) "(Conference on Microlol)
itography of the interna
Tional Society for Optica
l Engineering, March 1984)
There is a description.

As described in the above-mentioned literature, a conventional pattern inspection method is based on CAD data used for constructing a semiconductor integrated circuit device, for example, prior to an appearance inspection of a pattern formed on a semiconductor wafer. After automatically creating inspection data for the entire area of the semiconductor integrated circuit device, the pattern is subjected to image processing while referring to the inspection data to inspect the appearance.

Incidentally, in the method of inspecting the pattern appearance of each semiconductor chip formed on a semiconductor wafer, a two-chip comparative inspection and a two-cell comparative inspection are sometimes combined, for example, from the viewpoint of improving inspection accuracy. The two-chip comparison inspection is an inspection method for comparing patterns in different semiconductor chips, and the two-cell comparison inspection is an inspection method for comparing adjacent patterns in a predetermined region in each semiconductor chip. For example, in a region such as a memory cell array in which a pattern having the same shape is repeatedly arranged (hereinafter, referred to as a repeated region), the appearance of the pattern may be inspected by a two-cell comparison inspection. This is because the adjacent patterns in the repetition area have very similar patterns, and thus the inspection accuracy can be made better than the two-chip comparison inspection. Therefore, such pattern inspection requires inspection data such as the position coordinates of the repetitive area in the semiconductor chip and the pattern pitch in the repetitive area. That is, such pattern inspection requires inspection data of a repetition area.

[0005]

However, the present inventor has found that the above-mentioned prior art has the following problems.

That is, in the past, sufficient consideration was not given to creating only inspection data for a predetermined area when creating pattern inspection data. For example, when creating inspection data only for a repetitive area, , CAD
There is a problem that it is necessary to search for the data of the repetition area from the huge test data of the whole area of the semiconductor integrated circuit device created based on the data, and the creation thereof requires a lot of time and labor.

It is also conceivable to incorporate a program for extracting inspection data of only a predetermined area into a program for creating inspection data from CAD data. However, since CAD systems differ from one company to another, for example, CAD systems of other companies are used. There is a problem that it is impossible to incorporate a data extraction program into the system.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique capable of greatly reducing the inspection time of a pattern formed on an inspection object.

Another object of the present invention is to provide a technique capable of greatly improving the work efficiency of the above pattern inspection.

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

[0011]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

That is, according to the first aspect of the present invention, prior to the appearance inspection of the pattern formed in the inspection area of the inspection object, the pattern for generating the pattern inspection data of the repetition area arranged in the inspection area is provided. Inspection data creation method, captures images of arbitrary detection points at a plurality of locations in the inspection area, investigates the periodicity of the pattern in the detection points for each of the detection points, to detect the detection points having the periodicity Determined as a repeat area inside point, and automatically extract the pattern pitch of the repeat area inside point as a pattern repeat pitch, set a representative point from among the repeat area inside points, and pass through the representative point By inspecting the periodicity of the pattern on the line extending in the two-dimensional direction, the pattern coordinates for automatically extracting the position coordinates of the entire repeating area are used. It is over data creation method.

According to the above-described invention, only the inspection data of the repetition area is automatically extracted from the inspection object itself.
For example, there is no need to investigate pattern design data such as CAD data, and there is no need to create a data extraction program for extracting inspection data only for repetitive regions.

[0014]

(Embodiment 1) FIG. 1 is a configuration diagram of a pattern inspection apparatus according to an embodiment of the present invention, FIG. 2 is a plan view of a main part showing a repetitive region of an inspection object, and FIG. Figure 2
4 (a) and 4 (b) are plan views of a main part of an object to be inspected showing a step of automatically extracting inspection data of the repeated area, and FIGS.
6A and 6B are explanatory diagrams illustrating automatic extraction of a pattern repetition pitch, and FIGS. 6A to 6G are explanatory diagrams illustrating automatic extraction of position coordinates of the entire repetition area.

FIG. 1 shows a pattern inspection apparatus 1 according to the first embodiment.

On the base 2, XY stages 3a and 3b movable in directions orthogonal to each other are provided. A mounting table 4 is installed on the Y stage 3b, and a semiconductor wafer (inspected object) 5 is held on the mounting table 4 with its main surface facing upward.

On the semiconductor wafer 5, for example, a plurality of semiconductor chips (inspection areas) 6 as shown in FIG. 2 are formed. In each semiconductor chip 6, for example, two memory cell arrays (repeated regions) 6a ₁ and 6a ₂ are arranged.
The coordinates (XS ₁ , YS ₁ ), (XS ₁ , YE ₂ ), (X
E ₁ , YS ₁ ), (XE ₁ , YE ₂ ), etc. indicate the position coordinates (test data) of the memory cell array 6 a ₁ , and the coordinates (X
(S ₂ , YS ₁ ), (XS ₂ , YE ₂ ), (XE ₂ , YE ₂ ), etc. indicate the position coordinates (inspection data) of the memory cell array 6 a ₂ .

In the memory cell arrays 6a ₁ and 6a ₂ , as shown in FIG. 3, a pattern 6b having the same shape is formed as shown in FIG.
They are arranged at a repetition pitch (inspection data) PX in the direction and at a Y-direction repetition pitch (inspection data) PY. However, the pattern in the area A surrounded by the dashed line is a repeated basic pattern of the pattern 6b.

An optical system 7 for taking in the state of the main surface of the semiconductor wafer 5 as image data is arranged above the mounting table 4 of the pattern inspection apparatus 1. The optical system 7
An illumination light source 7a, a condenser lens 7b for condensing illumination light,
A half mirror 7c for separating the illumination light from the reflected light from the semiconductor wafer, an objective lens 7d for projecting the illumination light onto the main surface of the semiconductor wafer 5 and expanding the reflected light, and receiving the reflected light to emit light. Light receiving unit 7 for converting a signal into an electric signal
e.

The light receiving section 7e is, for example, a CCD (Charge).
e Coupled Device). The image signal detected by the light receiving unit 7e is transmitted to the signal processing unit 8. The signal processing unit 8 is a processing unit that performs amplification and level conversion (eg, signal correction and A / D conversion pre-processing) of the transmitted image signal. The image signal output from the signal processing unit 8 is transmitted to an A / D conversion unit 9 that converts an analog signal into multiple gradations. The image signal output from the A / D converter 9 is transmitted to each of the defect detector 10, the delay memory 11, the shift detector 12, and the image memory 13.

The image signal output from the delay memory unit 11 is transmitted to the defect detection unit 10 via the deviation correction unit 14 and is transmitted to the deviation correction unit 14 via the deviation detection unit 12. ing. The delay memory unit 11
This is a memory unit for temporarily storing the image signal output from the / D conversion unit 9, and the output thereof is controlled so that the image signal before the input by the repetition pitch is output.

The shift detecting unit 12 compares the image signal of the pattern transmitted from the A / D converter 9 with the image signal of the pattern transmitted from the delay memory unit 11, that is,
A detection unit that compares image signals of patterns adjacent to each other and detects a relative positional shift amount between the two images.

The shift correcting unit 14 is a correcting unit that performs fine adjustment so as to delay or speed up the image signal transmitted from the delay memory unit 11 in accordance with the output signal of the shift detecting unit 12 to perform shift correction.

The defect detector 10 compares the image signal of the pattern transmitted from the A / D converter 9 with the image signal of the pattern transmitted from the shift corrector 14, that is, each of the patterns adjacent to each other. A detection unit that compares the image signals and, when there is a difference, outputs it as a defect candidate.

The image memory section 13 is a memory section for storing the image signal transmitted from the A / D conversion section 9 and is electrically connected to the main control section 15.

The main control unit 15 automatically extracts inspection data such as the repetition pitch of the pattern of the memory cell array and the position coordinates of the memory cell array from the image data of the detection points stored in the image memory unit 13 by a method described later. And is constituted by, for example, a microcomputer system.

Next, a method for generating data for pattern inspection according to the first embodiment will be described with reference to FIGS.

First, a semiconductor wafer 5 to be inspected is held on a mounting table 4 of the pattern inspection apparatus 1 shown in FIG. 1 with its main surface facing upward. Subsequently, as shown in FIG. 4A, for example, any detection points D _{1 to} D ₁₀ are designated along a diagonal line of the semiconductor chip 6. The method of designating the detection points D _{1 to} D ₁₀ may be automatic input or manual input from a keyboard (not shown) or the like. Then, each detection point D ₁
ＤD ₁₀ , the image is captured by the optical system 7, and each captured image signal is processed by the signal processing unit 8 and the A / D
The image data is stored in the image memory unit 13 via the conversion unit 9.

The main control unit 15 determines the periodicity of the pattern in the X and Y directions for each image signal of each of the detection points D _{1 to} D ₁₀ stored in the image memory unit 13 by, for example, the Fourier transform or the autocorrelation function. Investigate by a mathematical method suitable for determining gender. At this time, if the detected detection points exist in the memory cell arrays 6a ₁ and 6a ₂ and the pattern in the detection points has a periodicity as shown in FIG. As shown in FIG. 5B, a curve having a clear maximum value is obtained at a cycle of an integral multiple of the repetition pitch PX.

On the other hand, when the detected detection point does not exist in the memory cell arrays 6a ₁ and 6a ₂ ,
The curve having the clear maximum value shown in (b) cannot be obtained. The same applies to the Y direction.

According to such an investigation, the main control unit 15
Each of the detection points D _{1 to} D ₁₀ is a memory cell array 6 a ₁ , 6
It determines whether a ₂ inside point. In the example of FIG. 4A, the main control unit 15 determines the detection points D ₂ , D ₃ , D ₄ , D ₆ , D ₇ , D ₈ , D
₉ , in each of the XY directions, the substantially same repetition pitch P
Check the periodicity of X and PY, and check each point D ₂ , D ₃ , D ₄ , D ₆ ,
It is determined that D ₇ , D ₈ , and D ₉ are inside the memory cell arrays 6a ₁ and 6a ₂ . Then, the main controller 15 automatically extracts the pitches of the pattern 6b in the XY directions at the inner points of the memory cell arrays 6a ₁ and 6a _{2 as} the repetition pitches PX and PY of the pattern 6b.

Next, the main control unit 15 detects the detection points D ₂ , D ₃ , D ₄ , D ₆ , D ₇ , D ₇ in the memory cell arrays 6 a ₁ , 6 a ₂ .
One point out of D ₈ and D ₉ is set as a representative point. In the first embodiment, for example, as shown in FIG.
The detection point D ₄ as the representative point.

Subsequently, the main control unit 15 sequentially inputs the image of the pattern on the XX line and the YY line passing through the representative point and extending in the XY direction along each of the lines, Investigate gender. As a result, the main control unit 15
A memory cell array 6a ₁ whole coordinates (XS _1, Y
S ₁ ), (XS ₁ , YE ₁ ), (XE ₁ , YS ₁ ), (X
E _1, YE ₁₎ and the memory cell array 6a ₂ whole coordinates _{(XS 2, YS 1),} (XS 2, YE 1), (XE 2,
YS ₁ ) and (XE ₂ , YE ₁ ) are automatically extracted.

To automatically extract the position coordinates of the entire memory cell arrays 6a ₁ and 6a ₂ , for example, FIGS.
(G). Here, for the sake of simplicity, a method of extracting coordinates in the X direction will be described.
The coordinates of the direction can be similarly extracted.

FIG. 6A shows a part of the original image signal on the line XX shown in FIG. 4B, and FIG. 6B shows an image obtained by delaying the image signal by the repetition pitch PX. Signal. B indicates a non-repeated area, and C indicates an area of the memory cell arrays 6a ₁ and 6a ₂ .

First, by taking the difference between the two image signals shown in FIGS. 6A and 6B, a signal waveform as shown in FIG. 6C is obtained.

Subsequently, a region where the absolute value of the difference value is equal to or more than a predetermined value is obtained, and a rectangular binary digital signal as shown in FIG. 6D is obtained.

Here, in FIG. 6D, since the non-repeated area B shown in FIG. 6A is not accurately obtained,
The binary digital signal shown in FIG. 6D is enlarged, and the divided signal regions are combined as shown in FIG. 6E.
Thereafter, the signal area is reduced by the same amount as the enlargement amount, and FIG.
The signal shown in (f) is obtained. Further, in the signal of FIG. 6F, the non-repeated area B has a repetition pitch PX more than the actual one.
6 (g) is obtained by sandwiching the signal area by the repetition pitch PX. As a result, the discrimination of the area C of the memory cell array 6a _1, 6a ₂ and the non-repeat region B can be carried out, it is possible to obtain the X-direction coordinate of the memory cell array 6a _1, 6a _2.

The pattern inspection apparatus 1 is based on the inspection data of the memory cell arrays 6a ₁ and 6a ₂ thus obtained, and is adjacent to each other in the memory cell arrays 6a ₁ and 6a ₂ formed on the semiconductor chip 6, for example. Pattern 6
b and 6b are compared to inspect the appearance of the pattern.

As described above, according to the first embodiment, prior to the pattern inspection, the inspection data of the memory cell arrays 6a ₁ and 6a ₂ is automatically extracted from the semiconductor wafer 5 itself, so that the memory cell arrays 6a ₁ and 6a ₁ are extracted. upon creation of the test data for 6a ₂ only, for example, neither need to investigate the pattern design data such as CAD data, create a data extraction program for extracting test data for only the memory cell array 6a _1, 6a ₂ Since there is no need to perform the pattern inspection, the pattern inspection time can be greatly reduced, and the work efficiency of the pattern inspection can be greatly improved. As a result, the development period of the semiconductor integrated circuit device can be significantly reduced.

(Embodiment 2) By the way, in the first embodiment, the case where the coordinates of the points in the memory cell array are automatically searched has been described. For example, when the coordinates of the points in the memory cell array are obtained. May be performed as follows.

That is, first, the coordinates of the points in the memory cell array are manually input from a keyboard (not shown) or the like, and the image is captured by the optical system 7 of the pattern inspection apparatus 1 shown in FIG. Then, the captured image signal is stored in the image memory unit 13 via the signal processing unit 8 and the A / D conversion unit 9. The main controller 15 automatically extracts the pattern repetition pitches PX and PY from the image data of the points in the memory cell array stored in the image memory 13. In addition, the main control unit 15 automatically extracts the position coordinates of the entire memory cell arrays 6a ₁ and 6a ₂ by checking the periodicity of the pattern on the line extending in the XY direction passing through the points inside the memory cell array.

Therefore, according to the second embodiment, the same effect as that of the first embodiment can be obtained.

[0044] (Embodiment 3) By the way, in the first and second embodiments have been described as being automatically extract the memory cell array 6a _1, 6a ₂ whole coordinates, for example, a memory cell array 6a _1, 6a ₂ when the position coordinates of the entire are been obtained may be as follows.

That is, first, the memory cell array 6
The position coordinates of a ₁ and 6a ₂ are manually input from a keyboard (not shown) or the like, and an image of the coordinate points is captured by the optical system 7 of the pattern inspection apparatus 1 shown in FIG. Then, the captured image data is converted into a signal processing unit 8 and an A / D conversion unit 9.
Through the image memory unit 13. Main control unit 15
Automatically extracts the pattern repetition pitches PX and PY from the image data stored in the image memory unit 13.

Therefore, according to the third embodiment, the same effect as that of the first embodiment can be obtained.

(Embodiment 4) A method for automatically extracting inspection data of a memory cell array may be as follows.

That is, first, a semiconductor wafer (hereinafter, referred to as a reference wafer) on which a memory cell array serving as a reference is formed is held on the mounting table 4 of the pattern inspection apparatus 1 shown in FIG. An entire image of a memory cell array (not shown) is captured, and the image data is stored in a predetermined area of the image memory unit 13 as reference image data.

Next, after the semiconductor wafer to be inspected is held on the mounting table 4 instead of the reference wafer, the entire image of the semiconductor chip 6 is fetched by, for example, the optical system 7 and the image data is stored in the image memory unit 13 in a predetermined manner. Store in area. The main control unit 15 automatically searches the entire image data of the semiconductor chip 6 for an area having the same image as the reference image, and uses the image data of the searched area for inspection such as repetition pitch and position coordinates of the repetition area. Extract data automatically.

Therefore, according to the fourth embodiment, the same effect as that of the first embodiment can be obtained.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the first to fourth embodiments, and the present invention is not limited thereto. It goes without saying that various changes can be made.

For example, in the first to fourth embodiments, the case where the repetition area is a memory cell array has been described. However, the present invention is not limited to this, and various changes can be made. An element array may be used.

In the first to fourth embodiments,
For the sake of simplicity, the case where the number of memory cell arrays is two has been described. However, the present invention is not limited to this, and various changes can be made.

In the above description, the case where the invention made by the present inventor is mainly applied to the pattern inspection technique of a semiconductor integrated circuit device, which is the field of application as the background, has been described. And
For example, the present invention can be applied to a pattern inspection technology of another product such as a mask or a reticle.

[0055]

Advantageous effects obtained by typical ones of the inventions disclosed in the present application will be briefly described.
It is as follows.

That is, according to the present invention, the inspection data of the repetition area is automatically created from the inspection object itself. There is no need to investigate the data, and there is no need to create a data extraction program to extract the inspection data only for the repetitive area, so that the pattern inspection time can be greatly reduced and the pattern inspection work efficiency can be reduced. Can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a pattern inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view of a main part showing a repetition area of an inspection object.

FIG. 3 is an enlarged partial plan view showing a pattern in a repeating area shown in FIG. 2;

FIGS. 4 (a) and 4 (b) are plan views of main parts of the inspection object showing a process of automatically extracting inspection data of a repetition area.

FIGS. 5A and 5B are explanatory diagrams illustrating automatic extraction of a pattern repetition pitch.

FIGS. 6A to 6G are explanatory diagrams illustrating automatic extraction of position coordinates of the entire repetition area.

[Explanation of symbols]

1 pattern inspection apparatus 2 base plate 3a X stage 3b Y stage 4 mounting base 5 semiconductor wafer (inspection object) 6 semiconductor chip (inspection region) 6a _1, 6a ₂ memory cell array (repeat region) 6b pattern 7 optics 7a illumination Light source 7b Condensing lens 7c Half mirror 7d Objective lens 7e Light receiving unit 8 Signal processing unit 9 A / D conversion unit 10 Defect detection unit 11 Delay memory unit 12 Deviation detection unit 13 Image memory unit 14 Deviation correction unit 15 Main control unit A, B area C Non-repetitive area D _{1 to} D ₁₀ detection points PX, PY Repetition pitch

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission Date] November 14, 2001 (2001.11.
14)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

[Title of the Invention] Appearance inspection method

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

9. The information of the pitch of the repeating pattern is:
8. The information according to claim 7, wherein the information is preset.
Appearance inspection method .

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

That is, the invention according to claim 1 is a method for inspecting the appearance of a repetitive pattern formed on an object to be inspected, wherein the image of the object to be inspected is obtained to obtain an image of the object to be inspected. From the image of the object to be inspected, determine an area where the repetitive pattern formed on the object is present, and process an image obtained by imaging the object in the area where the obtained repetitive pattern is present. An appearance inspection method characterized by inspecting the appearance of the repeating pattern.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiko Yoshizawa 3-3-2 Fujibashi, Ome-shi, Tokyo F-term in Hitachi Tokyo Electronics Co., Ltd. 4M106 AA01 AB07 BA04 CA39 DB12 DB13 DB19 DJ04 DJ12 DJ19 DJ21 5B057 AA03 BA02 DA03 DB02 DB09 5L096 AA06 BA03 CA14 CA24 DA02 FA23 FA46

Claims (5)

[Claims] 1. A pattern inspection data creating method for creating pattern inspection data of a repetitive area arranged in an inspection area prior to appearance inspection of a pattern formed in the inspection area of the inspection object. Incorporating images of arbitrary detection points at a plurality of points in the inspection area, determining the periodicity of the detection points having periodicity by examining the periodicity of the pattern in the detection points for each of the detection points, A pattern pitch on the line extending in the two-dimensional direction passing through the representative point is set by automatically extracting the pattern pitch of the point in the repeating area as the pattern pitch, and setting a representative point from the points in the repeating area. A pattern inspection data generating method for automatically extracting position coordinates of the entire repetition area by examining periodicity of the pattern. 2. A pattern inspection data creating method for creating pattern inspection data of a repetitive area arranged in the inspection area prior to an appearance inspection of a pattern formed in the inspection area of the inspection object. When a coordinate point located in the repetition area is determined, an image of the coordinate point is fetched from the beginning, and a pattern pitch in the coordinate point is automatically extracted as a pattern repetition pitch, and the coordinate point is extracted. A pattern inspection data creating method, wherein the position coordinates of the entire repeating area are automatically extracted by examining the periodicity of a pattern on a line extending in a two-dimensional direction after passing through the pattern. 3. A pattern inspection data creating method for creating pattern inspection data of a repetitive area arranged in the inspection area prior to an appearance inspection of a pattern formed in the inspection area of the inspection object. When the position coordinates of the entire repetition area are determined, an image at the coordinate point is fetched, and a pattern pitch within the coordinate point is automatically extracted as a pattern repetition pitch. Data creation method. 4. A pattern inspection data creating method for creating pattern inspection data of a repetitive area arranged in the inspection area prior to an appearance inspection of a pattern formed in the inspection area of the inspection object. The image of the reference repetition area is stored in advance as reference image data,
A pattern in which an area having the same image as the reference image data is searched from the inspection area, and a pattern repetition pitch and position coordinates of the entire repetition area are automatically extracted from the image data of the searched area. Inspection data creation method. 5. A pattern inspection apparatus for inspecting the appearance of a pattern formed in an inspection area while referring to pattern inspection data of a repetitive area arranged in the inspection area of an inspection object, wherein An optical system that captures an image of an arbitrary detection point in the inspection area, an image memory unit that stores image data captured by the optical system, and a period of a pattern in the detection point from the image data stored in the image memory unit The detection points having periodicity are examined to determine the repetition area points, and the pattern pitch of the repetition area points is automatically extracted as the pattern repetition pitch, and the representative point is selected from the repetition area points. After setting, the periodicity of the pattern on the line extending in the two-dimensional direction passing through the representative point is investigated, and the position coordinates of the entire repeating area are automatically calculated. A pattern inspection apparatus comprising: a main control unit that extracts a target;