JPS61102736A - Method and apparatus for correcting pattern - Google Patents

Abstract

PURPOSE:To correct a pattern easily and precisely by detecting one pattern and an object pattern as different color pictures, recognizing a defect from a picture obtained through synthesis and correcting the defect. CONSTITUTION:A pattern for a reference chip is scaled up and picked up by a TV camera 11, a pattern picture acquired is compared with a MT data 17 in a comparator 18, the discordance section of the pattern picture to the MT data 17 is detected, and the XY coordinates and form and size of the discordance section are each outputted from a computing element 19 as XY signals Sa1 and form-size signals Sa2. The kind of a white point defect or a black point defect is outputted as kind signals Sa3 at that time, the XY signals Sa1 control an XY table 1 in an XY control section section 2, and set a pattern defect at the position of an optical axis, and the form-size signals Sa2 operate an aperture control section 15 to drive a blade 13a, and control a defect 6x so as to be surrounded by an aperture 13. When the defect 6x represents a black point, laser beams from a laser beam source 14 are projected, and a Cr film as the defect is burnt out, thus correcting the defect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method and apparatus for correcting defects in fine patterns formed on photomasks and reticles.

[Background technology]

Photomasks and reticles used in the manufacture of semiconductor devices are formed by patterning a light-opaque film such as a Cr film on the surface of a transparent substrate. However, since phosphorography technology is used to form the mask pattern itself, dust adhering to the mask surface or poor development may cause white spot defects where no pattern is formed or black spot defects where an unnecessary pattern is formed. are likely to occur and require correction of these patterns.

By the way, it is necessary to inspect pattern defects prior to pattern correction, and conventional methods for this inspection include comparing the inspected pattern with design data (M'1' data), and In this case, methods such as mutual comparison of chip patterns have been put into practical use. The former method, which involves comparison with design data, can accurately detect the location, shape, and size of defects, but it takes time to compare the binary signals of the patterns, and requires inspection of a large number of chip patterns. is not valid. On the other hand, the method based on comparison between chip patterns allows short-time inspection because the patterns are directly compared, but it is difficult to accurately recognize defects.

For this reason, in general, after roughly determining the location of the defect by mutual comparison of chip patterns, an operator visually checks the target chip pattern using a TV screen or a microscope, and based on his experience. Methods are being used to find defects. When correcting this defect, as shown in FIG. 5, a normal pattern is estimated from the target pattern P, and based on this estimation, the correction range (defect P
x) is limited by an aperture A or the like, and then the defect Px is corrected by a known method using laser light.

However, in the case of a pattern shape for which it is difficult to estimate a normal pattern using this method, for example, as shown in FIG. 6, the pattern PY to be formed may completely disappear and its shape cannot be determined from the surrounding patterns P. It cannot be applied in such cases and therefore no modification is possible. Therefore, a chip pattern or a mask with this kind of defect becomes a defective product, and especially if this mask is used to form a semiconductor element chip, a chip defect will occur and the chip yield will decrease. .

Note that as an example of mask correction technology, rSemi-c
onductor WorldJ Press Journal Company 1
There is a description on pages 95-99 of the January 1984 issue.

[Purpose of the invention]

The purpose of the present invention is to recognize pattern shapes and correct pattern defects based on the recognition easily and accurately, thereby eliminating the drop in chip manufacturing yield caused by pattern defects and achieving high accuracy. An object of the present invention is to provide a pattern correction method that enables the formation of patterned chips.

Another object of the present invention is to provide a pattern correction method that detects and determines white spot defects, black spot defects, etc. in a pattern and makes it possible to automate pattern correction.

Furthermore, another object of the present invention is to display pattern defects with force 2- so that the position, shape, size, etc. thereof can be easily recognized.
It is an object of the present invention to provide a pattern defect repair device that can automatically repair defects while checking the repair location on the display screen.

Another object of the present invention is to provide a pattern correction device that can display white spot defects and black spot defects in different colors and can appropriately correct these defects.

The above and other objects and novel features of the present invention include:
It will become clear from the second description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this Ni is as follows.

That is, the one color is detected from the image obtained by detecting one pattern and the target pattern as color images of one color and another color between them, and combining them.

By detecting parts of other colors as defects and correcting the defects by recognizing the position, shape, size, etc. of these defects, pattern defects can be easily recognized and corrections can be made easily and easily. Can be done accurately.

First, by simply surrounding the area with the color indicating the defect with an aperture, the setting of the correct range can be completed, and furthermore, the white and black points can be immediately recognized depending on the color indicating the defect.

Is it possible to automatically make appropriate corrections for each defect?

On the other hand, a coloring means for forming one pattern and a target pattern into color images of one color and another color, respectively, a compositing means for composing these different color images, and a coloring means for composing the one color from the composite image,
Defects can be detected by detecting other colors and determining the defect position, shape, and dimensions from the defect, surrounding the defect with an aperture, and correcting the defect by projecting a laser beam or the like into the aperture. By displaying in color, it is possible to easily set and confirm the location to be modified using the aperture, and the modification can be performed automatically and accurately.

Further, by providing a means for distinguishing between the one color and the other color, the defect can be distinguished as a white spot defect or a black spot defect, and the defect correcting means can perform corrections corresponding to each defect. can be controlled.

〔Example〕

FIG. 1 shows an embodiment in which the present invention is applied to the correction of a 7-oto-mask pattern, and shows the overall configuration of an apparatus for correcting white dots and black dot defects in a pattern formed of a Cr (chromium) film or the like on a glass substrate. ing. In the figure, 1&'! , an XY table, which can be moved in plane XY directions by an XY control unit 2 and an XY drive mechanism 3, and can move the plane position of a photomask 4 as an object to be corrected mounted thereon. The photomask 4 has a pattern 6 such as a Cr film formed on the surface of a transparent glass substrate 50, and is placed on an XY table 1 with the pattern 6 facing upward.

Above the XY table 1, there are provided an inspection system 7 for inspecting the pattern 6 of the photomask 4, and a correction system 8 for correcting defective patterns.

The inspection system 7 includes an objective lens 9. Imaging lens 10 and T
It has a V-right camera 1, which can enlarge and image the pattern 6 of the mask. The correction system 8 has a half mirror 12 provided in the inspection system 7, an aperture 13 provided facing the half mirror 12, and a laser light source 14. The light is reflected by the half mirror 12 and focused onto the surface of the mask 40 using the objective lens 9. Aperture 13 is 4
The aperture shape and size of the blades 13a can be set by driving these blades 13a with an aperture control section 15.

On the other hand, a signal processing section 16 is connected to the inspection system 7, and a TV
K is set so that defects can be detected from the image signal of the right camera 1. That is, the signal processing unit 16 has a comparator 18 that performs a pairwise comparison between MT (master tape) data 17 storing pattern design data and pattern data detected by the TV right camera 1, and detects a mismatch between the two data. It is possible to output the defect of the pattern obtained from the above through the arithmetic unit 19 as an XY (coordinate) signal Sat and a shape/dimension signal Saz. The signal processing unit 16 also includes a coloring device 20 that displays the imaged pattern of the TV camera 211 using any of the three primary colors (R, G, and B). (Red) It has a memory 21 that stores only signals.

A synthesizer 22 superimposes the R signal output from the memory 21 and the Cy (cyan) signal, which is a mixed signal of G (green) and B (blue) signals from the colorizer 20.
is provided, and the pattern image synthesized by this synthesizer 22 is CR
The configuration is such that an image can be displayed at T23.

Further, an RC filter 24 and an arithmetic unit 25 are connected in series to the synthesizer 22, and only the image portion of R'PCy is drawn by an RC74 router 24 from among the pattern images obtained by the synthesizer 22. In addition, the calculation unit 25 is configured to output an XY (coordinate) signal Sb+ and a shape/dimension signal Sbz of that portion.

In addition, each of the XY signals S of the arithmetic units 19 and 25
a1 and Sb+ can be sent to the XY control section 2 to form a first key, and the shape/dimension signals Sat and Sb2 of the respective computing units 19 and 25 can be sent to the aperture control section 15. I'm running a 5K. Further, the XY control section 2 is also configured to receive an XY signal Sc which is also output from the inspected data memory section 26. This inspected data memory section 26 inputs and stores pattern defect data (mainly XY position data) of the photomask 4 that has already been inspected in the previous process.

On the other hand, a pattern correction tape 27 made of resin containing Cr or the like is placed directly above the XY table l so that it can move forward and backward on the mask surface. The configuration is such that Sbx is input.

The type signal Sb3 outputs the types of white spot defects and black spot defects, and masks 4 the pattern correction tape 27 that causes white spot defects.
advance to the top. Note that the pattern correction tape 27 and the drive unit 28 are configured as part of the correction system 8 as necessary. Furthermore, the arithmetic unit 190 of the comparator 18 may be driven by the type signal Sa3.

Next, a first pattern correction method using the correction apparatus having the above configuration will be explained.

First, any one of the multiple chip patterns 6 formed on the photomask 4 is detected as a reference chip pattern. In other words, the pattern of this reference chip is transferred to the objective lens 9. The pattern image is magnified with the lens 10 and taken with the TV left camera 1, and the resulting pattern image is sent to the comparator 18.
Compare with T data 17. As a result of comparison, MT data 17
Detects mismatched parts of the pattern image, that is, pattern defects, and transmits the XY coordinates, shape, and dimensions to the XY signal S.
The arithmetic unit 19 also outputs the a++ shape/dimension signal Sa2. Further, at this time, the type of the defect, whether it is a white spot defect or a black spot defect, is also output as a type signal Sas.

As a result, the XY signal Sa1 controls the XY table l in the XY control unit 2 to set the pattern defect at a predetermined position (generally at the optical axis position WL), and the shape/dimension signal Saz operates the aperture control unit 15. The blade 13a is controlled so that the defect 6x is surrounded by the aperture 13 as shown in FIG. However, if the defect 6x is a black spot as shown in the figure, the laser light source 1 is turned on in that state.
If the laser beam of 4 is projected, the laser beam will have an aperture of 1.
3 and then the objective lens 9 as shown in Fig. 3 (
A) is focused on the defect 6x, and C' as a defect.
Correct the defect by burning out the membrane. On the other hand, the defect is shown in Figure 3 (B
), in the case of a white spot defect 6y, the type signal Sas operates the drive unit 28 to move the pattern correction tape 27 to the defect 6y.
The laser beam is focused and projected from above.

The laser beam elutes Cr and resin contained in the pattern correction tape 27 from the tape 27 and deposits it on the white spot defect 6y to form a light-opaque pattern similar to the surrounding Cr film 6 and complete the correction. .

After the reference chip pattern is corrected to a normal pattern as described above, the next chip pattern is compared with this reference chip pattern to inspect for defects and correct them.

First, as shown in FIG. 4(A), a normalized reference chip pattern 6A as one pattern is detected by the inspection system 7, and the pattern is imaged by the TV left camera 1. Then, the pattern portion of this captured image is configured as an R (red) signal SR of one color through the colorizer 20, and pattern information as this R signal SR is stored in the memory 21.

Next, the next chip pattern 6B as the target pattern
is detected in the same manner as shown in FIG. 2B, and the pattern portion of the pattern image obtained from the TV left camera 1 is passed through the colorizer 20 to form a mixture of B and G of other colors, that is, a Cy (cyan) signal S. , configured as .

Then, the pattern information in the form of this Cy signal Sc is sent to the synthesizer 22, where the above-mentioned R signal SR extracted from the memory 21 and the image are superimposed and synthesized.

Then, as shown in FIG. 3C, the parts where the R signal SR and the Cy signal Sc overlap are made white by adding red and cyan, but the parts where they do not match appear as red or cyan images. Therefore, these red or cyan parts 6 R, 5
(It turns out that y is a defect in the chip pattern 6B, and the red part 6R is a white dot defect because the chip pattern is missing, and the cyan part 6cy is a black dot defect where the chip pattern is redundant.) It turns out that there is something.

These red portion 6R and cyan portion 6cy are detected by the RC filter 24, and their XY positions, shapes and dimensions are calculated and outputted from the calculator 25 as an XY signal Sb+ and a shape and dimension signal Sbz. At the same time, it detects whether the defect is red or cyan, determines whether it is a white spot or a black spot, and outputs the type signal Sb3. As a result, the XY signal Sb+ operates the XY table l in the XY control section 2 to set one defect of the chip pattern 6B at a predetermined position fftK, and the shape/dimension signal Sbz is transmitted by the averty r control section 15 to set the defect in the aperture 13 at a predetermined position fftK. Set to surround. In this case, when the defect exists within the field of view of the TV left camera 1, there is no need to move the position using the XY table IK, and the defect can be surrounded only by controlling the aperture 13.

If the defect is a sunspot, the laser beam is focused on the defect in that state to correct the pattern as shown in FIG. 3(A),
If the defect is a white spot, the pattern correction tape 27 is set on the mask 4 as shown in CB in the same figure, and the defect is corrected in the same manner as described above. This (defects can be corrected completely automatically regardless of whether they are white or black points, and this condition is CRT2
Red, cyan, white and black (non-pattern area) on the screen of 3
This color image allows you to check not only the shape of the defect but also the correction.

After completing the correction of the target chip pattern, inspect and correct the next chip pattern in exactly the same way. In this way, the pattern inspection and correction method based on two-chip comparison can achieve inspection and correction at higher speed and in a shorter time than the method using the MT data 17.

On the other hand, the second pattern correction method is a method that targets a mask in which a pattern defect has already been detected in a separate inspection device, and the XY position of the defect of each chip pattern is stored in the inspection data memory 26. .

Therefore, by moving the XY table 1 based on the defect data to be output based on the information in the inspection data memory 26, the defects of each chip pattern are set within the field of view of the TV left camera 1.

Then, in this state, patterns between adjacent chips are detected as R signals and Cy multiplied signals, respectively, and by combining these signals, it is possible to immediately recognize defects in red or cyan. In this case, the memory 22 for the R signal may not be used. Hereinafter, the aperture 13 can be set in the same manner as described above or manually, and the pattern can be corrected using laser light.

In this case, there is a possibility that each of the chip patterns being compared has a defect, so even if red and cyan parts are generated by simply combining the two patterns, this part is not part of either chip pattern. It is unknown whether this is a defect. That is, when it is red, it is either a black dot defect on the R side pattern or a white dot defect on the Cy side pattern. However, in the case of the fifth example, since the defect position of the corresponding chip pattern is stored in advance in the inspection data memory 26, there is little possibility that such confusion will occur.

〔effect〕

(i) One pattern and the target pattern are detected as color images of one color and another color, respectively, and the parts of the one color and the other color are determined as defects from the image obtained by combining them. Detect and measure these defects.

5. Defects are corrected by recognizing the shape, dimensions, etc.
Even if there is a defect for which it is difficult to estimate a normal pattern, the defect can be easily recognized and repaired easily and accurately. 7 (2) If a normal pattern is used as the first pattern, one Color defects and other color defects respectively white spots,
They can be recognized as black spot defects, and both white and black spot defects can be corrected appropriately, and the correction can be automated.

(3) If each pattern is inspected in advance and defect information is memorized, any adjacent chip patterns can be used as the first pattern and the target pattern, and defects can be detected in one color or in another. Since it is displayed in this color, it is easy to make corrections, and corrections can be made quickly and in a short time.

(4) Since all defects can be corrected accurately and easily, mask defects can be completely eliminated, and the yield of chips formed using this mask can be improved.

(5) a coloring means for forming one pattern and a target pattern into one color image and another color image, respectively, a compositing means for composing these different color images, and a coloring means for composing the one color from the composite image;
By providing means for detecting other colors, determining the defect position, shape, and size from this and surrounding the defect with an aperture, and means for correcting the defect by projecting a laser beam or the like into the aperture.

By displaying pattern defects in color, it is possible to clearly confirm the location and state of the correction by the aperture, and it is possible to automate the correction and achieve accurate correction.

(6) Since it is equipped with a means to distinguish between one color and another color in the composite image, white spot defects and black spot defects can be automatically distinguished based on the difference in color, and appropriate corrections can be made accordingly. be able to.

(7) Since a memory is provided to store inspection data for one pattern, one pattern only needs to be inspected once when comparing chips, and inspection efficiency and correction efficiency can be improved.

(8) Since the device is provided with a memory means for storing inspection data obtained by performing pattern inspection in advance, it is possible to easily and quickly correct only the pattern by comparing the chips with each other.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor. For example, various combinations of colors for displaying one pattern and the target pattern can be adopted. Furthermore, the configurations of the optical systems for inspection and correction can be changed in various ways.

Furthermore, the configuration of the signal processing section can also be changed as appropriate.

[Application field]

In the above explanation, the invention made by the present inventor has mainly been explained in terms of the field of application which is the background thereof, which is the 1000-knob pattern correction technique for photomasks, and is not limited thereto (for example, reticles and It can be applied to correction techniques for fine patterns such as masks.

1h1 simple explanation of the drawing FIG. 1 is an overall configuration diagram of a correction device according to the present invention.

Figure 2 is a cross-sectional plan view showing a method for limiting the repair area; Figures 3 (A) and (B) are cross-sectional views showing a method for repairing black spot defects and white spot defects, respectively; Figure 4 (A) ), (B), and (C) are pattern plan views for explaining the repair method of the present invention, and FIGS. 5 and 6 are pattern plan views for explaining the conventional method and its defects.

1...XY table, 2...XY control section,
4...Photomask, 6...Pattern, 6 people...
Reference chip pattern (first pattern), 6B...Target chip pattern (target pattern), 6X...Black spot defect, 6y...White spot defect, 6R...R (signal) part, 6c
y: Cy (signal) section, 7: Inspection system, 8: Correction system, 11: TV camera, 13: Aperture, 1
4... Laser light source, 16... Signal processing unit, 17...
・MT data, 18... Comparator, 19... Arithmetic unit,
20... Colorizer, 21... Memory, 22... Synthesizer, 23... CRT, 24... RC filter, 25
...Arithmetic unit, 26...Verified data memory, Sas
, Sb+, 5c-XY position signal-8az+Sb
2... Shape/dimension signal, Sas + Sbs°°° type signal.

ゝ-1in Figure 1 Figure 2 Figure 3 ・A)

Claims (1)

[Scope of Claims] 1. Detecting one pattern and a target pattern as color images of one color and another color, which are different from each other, and synthesizing these images. A pattern correction method characterized by detecting a colored part as a defect, recognizing the position, shape, and size of the defect, limiting a correction part, and correcting the part. 2. The pattern correction method according to claim 1, wherein the one color and the other color are discriminated, the defect is recognized as a white spot defect or a black spot defect, and a corresponding correction is made. 3. The pattern correction method according to claim 2, wherein one pattern is a normal pattern, and one color and other colors of the composite image are determined as white spot defects and black spot defects of the target pattern, respectively. 4. Claims 1 to 3, wherein inspection data of one pattern is stored, and image synthesis of the stored one pattern inspection data and the target pattern is performed while sequentially changing the target pattern. The pattern modification method described in any of the sections. 5. Inspect the patterns for defects in advance and store the data, and based on this data, obtain a composite image of an arbitrarily selected pattern and the target pattern and perform correction. The pattern correction method described in Section 1. 6. Coloring means for forming a detected pattern and a target pattern into color images of one color and another color, respectively, a compositing means for composing these different color images, and a coloring means for composing the one color from the composite image. , a pattern correction device comprising: means for detecting parts of other colors and calculating their positions, shapes, and dimensions; and means for limiting correction points based on signals of the positions, shapes, and dimensions. 7. The pattern correction device according to claim 6, comprising memory means for storing one pattern, and configured to perform image synthesis of pattern data of the memory means and the target pattern. 8. Having means for distinguishing one color from another color, one color;
8. A pattern correction device according to claim 6, which is configured to be able to distinguish defects displayed in other colors as white dot defects and black dot defects. 9. A pattern correction apparatus according to any one of claims 6 to 8, comprising a memory means for storing inspection data obtained by performing pattern inspection in advance.