JPH06273916A - Phase shift mask inspection method and apparatus - Google Patents

Abstract

(57) [Abstract] [Purpose] Regarding inspection method and device for phase shift mask,
(EN) A means for rapidly inspecting the contour portion and the depth of a pattern step of a phase shift mask with precise dimensional accuracy. [Structure] Composite light including lights of different wavelengths emitted from a light source 4 which is focused in a spot by a pinhole plate 4 ₁ is condensed by an optical system (condensing lens 5), and chromatic aberration of this optical system causes The dispersed light of different wavelengths (first wavelength light 9 and second wavelength light 10) is incident on the phase shift mask 1 having the pattern step 3 and is transmitted through the phase shift mask 1 or reflected from the phase shift mask 1. the light intensity of different wavelengths, selectively detected by a photodetector 7 through the pinhole of the pinhole plate _71, and the reference signals corresponding to the thus detected contour portion and the depth of the pattern step 3 that And the signal corresponding to the contour portion and the depth obtained from a plurality of pattern steps formed on the same phase shift mask 1 are compared with each other for inspection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for inspecting a phase shift photomask used in a semiconductor device manufacturing process.

In recent years, the degree of integration of integrated circuit devices has become higher and higher, and it is inevitable to use a phase shift mask when a circuit pattern is exposed by using a high resolution photolithography technique in the manufacturing process. Several types of phase shift masks have been proposed, but in any case, since the phase relationship between the exposure light passing through the transparent phase shift mask and the exposure light passing through the pattern step is used. , In addition to forming the circuit pattern formed on the phase shift mask in a precise shape, it is necessary to set the contour and depth of the step formed on the phase shift mask to values that have a fixed relationship with the wavelength of the light source. Therefore, various methods for inspecting this pattern step have been conventionally proposed.

[0003]

2. Description of the Related Art FIG. 7 is an explanatory view of a conventional phase shift mask inspection apparatus. In this figure, 31 is a phase shift mask, 32 is a pattern light-shielding film, 33 is a pattern step, 34 is a light source, 35 ₁ is a collimating lens, 35 ₂ is a condenser lens, 36 is an objective lens, 37 is a photodetector, 38
Indicates a compound wavelength light, 39 indicates a first wavelength light, and 40 indicates a second wavelength light.

In this conventional phase shift mask inspection apparatus, a circuit pattern is formed by the pattern light-shielding film 32, and the phase shift mask 31 having a pattern step 33 is set on the XY stage (not shown) and is moved in the horizontal direction. , A light source 34 is arranged on the light source 34, and the compound wavelength light 38 emitted from the light source 34 is collimated by a collimating lens 35 ₁ and condensed by a condenser lens 35 ₂ to form a phase shift mask 31. The compound wavelength light 38 after being made incident on the phase shift mask 31 and transmitted through the phase shift mask 31 is condensed by the objective lens 36 and detected by the photodetector 37.

In this inspection apparatus, the phase shift mask 31 set on the XY stage is moved in the horizontal direction and the light passing through the phase shift mask 31 is observed by the photodetector 37, whereby the phase shift mask 31 It is intended to inspect the contour portion of the pattern step.

FIG. 8 shows an observation result (1) by a conventional phase shift mask inspection apparatus. The reference numerals in this figure are the same as those in FIG. According to this conventional phase shift mask inspection apparatus, the light source 34
The complex wavelength light 38 emitted from the collimator lens 35 ₁ is collimated by the collimator lens 35 ₁ and condensed by the condenser lens 35 _{2 to} enter the phase shift mask 31, which is the surface to be inspected, and is condensed by the objective lens 36. Photo detector 3
7, the compound wavelength light 38 is dispersed by the chromatic aberration of the optical system in the process, so that the photodetector 37
In addition to the strong first wavelength light 39 focused on the surface of the phase shift mask 31, the compound wavelength light 38 is an optical system such as a collimating lens 35 ₁ condenser lens 35 ₂ or a phase shift mask. The weak second wavelength light 40 dispersed by 31 is synthesized (the description of light of other wavelengths dispersed by the optical system is omitted).

As a result, the transmitted light intensity distribution detected by the photodetector 37 is as shown in this figure.
That is, in this transmitted light intensity distribution, the transmitted light intensity of the portion of the phase shift mask 31 where the pattern light-shielding film 32 is formed shows a slight level due to scattered light due to dust and the like in the atmosphere and the influence of the background. However, the intensity of the transmitted light shows a high level in the portion where the pattern light shielding film 32 is not formed.

Further, since the light incident on the contour portion of the pattern step 33 of the phase shift mask 31 is diffusely reflected and not transmitted through this portion, the portion corresponding to the contour portion of the pattern step 33 shows a low level. . Therefore, the shape of the contour portion of the pattern step 33 can be inspected by comparing the shape of the low-level pattern corresponding to the contour portion of the pattern step 33 with the reference signal or by comparing the repeated patterns with each other. it can.

[0009]

However, as shown in FIG. 7, the optical image transmitted through the vicinity of the pattern step 33 of the phase shift mask 31 and reaching the photodetector 37 is the surface of the phase shift mask 31. Since the first wavelength light 39 focused on the above and the weak second wavelength light 40 not focused on the surface of the phase shift mask 31 are combined, this transmitted light intensity distribution is not clear. . For example, when focusing on the upper surface of the step 33 of the phase shift mask, the image of the bottom of the step also enters the photodetector 37.

FIG. 9 shows an observation result (2) by a conventional phase shift mask inspection apparatus, and (A) and (B) show transmitted light intensity distributions of two pattern steps. In this figure, 31 is a phase shift mask, 32 ₁ and 32 ₂ are pattern light-shielding films, and 33 ₁ and 33 ₂ are pattern steps.

This figure shows a deep pattern step 33 ₁ formed on one phase shift mask 31 and a transmitted light intensity distribution transmitted through the pattern light-shielding film 32 ₁ by a conventional phase shift mask inspection apparatus, and a shallow pattern step. 33 ₂ shows the transmitted light intensity distribution transmitted through the pattern light-shielding film 32 _2, and the transmitted light intensity distribution obtained by this inspection method is the difference of the light diffusedly reflected by the contour portions of the pattern steps 33 ₁ , 33 ₂ . Since it does not appear, the pattern step 33 ₁ ,
Even if the depth of 33 ₂ is different, the transmitted light intensity distribution of almost the same shape can be obtained.

Therefore, even if the depths of the pattern steps 33 ₁ and 33 ₂ formed on the phase shift mask 31 are not uniform, the defect cannot be inspected and the pattern steps 3 3
3 using _1, 33 low-level patterns transmitted light intensity caused by light is irregularly reflected by the _second contour portion, or compared to the shape of the contour of the reference pattern, which is formed in the same phase shift in the mask Same pattern step 33 ₁ , 33
Only the shapes of the _two contours can be compared with each other.

Originally, in the process of manufacturing an integrated circuit device, when a circuit pattern is reduced and projected by using a phase shift mask to expose a photosensitive resist film, interference of exposure light occurs at the pattern step. In the method of inspecting the phase shift mask, which is a problem here, since reduction projection is not performed, interference of light used for the inspection hardly occurs.

Further, the pattern step 33 is formed by the probe.₁，
33₂The surface of the phase shift mask including
Although a method of measuring the depth of the turn step has been proposed,
Even if the diameter of the typical probe is thin, it is about 5 μm.
Therefore, the fine pattern step 33 ₁, 33₂You can get inside
And the step 33 of the fine pattern₁, 33₂Contour of
The part and depth cannot be measured accurately.

An object of the present invention is to provide a phase shift mask inspecting method and apparatus capable of inspecting a contour portion and a depth of a pattern step of the phase shift mask rapidly with precise dimensional accuracy.

[0016]

In the method of inspecting a phase shift mask according to the present invention, a composite wavelength light containing light of different wavelengths is condensed by an optical system, and different wavelengths of different wavelengths dispersed by chromatic aberration of the optical system are condensed. A process is adopted in which light is incident on a phase shift mask having a pattern step, and light of different wavelengths that are transmitted or reflected by the phase shift mask is selectively detected.

In this case, a point light source and a point detector can be used to selectively detect light of different wavelengths that are transmitted or reflected by the phase shift mask.

Further, in this case, chromatic aberration such that light having a longer wavelength is focused from the surface of the phase shift mask to the bottom surface of the pattern step or vice versa from the bottom surface of the pattern step to the surface of the phase shift mask. An optical system having a can be used.

Further, in this case, the inspection signal corresponding to the contour portion or depth of the pattern step is compared with the reference signal to inspect the contour portion or depth, or a plurality of patterns formed on the phase shift mask. It is possible to inspect the contour portion or the depth of the pattern step by comparing the inspection signals corresponding to the contour portion or the depth of the step with each other.

In addition, in the phase shift mask inspection apparatus according to the present invention, a light source that emits a composite wavelength light containing lights of different wavelengths and a light of a different wavelength due to chromatic aberration in the process of condensing the composite wavelength light is generated. An optical system that is dispersed and is incident on a phase shift mask having a pattern step, and a photodetector that selectively detects light of different wavelengths that are transmitted or reflected by the phase shift mask are adopted.

In this case, a point light source is used as a light source that emits compound wavelength light containing lights of different wavelengths, and a point detector is used as a photodetector that selectively detects light of different wavelengths that are transmitted or reflected by the phase shift mask. A detector can be used.

Further, in this case, as the optical system, light having a longer wavelength is focused from the surface of the phase shift mask to the bottom surface of the pattern step, or vice versa, from the bottom surface of the pattern step to the surface of the phase shift mask. It is possible to use an optical system having a chromatic aberration that results in connection.

Further, in this case, means for inspecting the contour portion or the depth of the pattern step by comparing the inspection signal corresponding to the contour portion or the depth of the pattern step with the reference signal, or
A means for inspecting the contour portion or the depth of the pattern step can be provided by mutually comparing the inspection signals corresponding to the contour portion or the depth of the plurality of pattern steps formed on the phase shift mask.

[0024]

1 and 2 are explanatory views of a phase shift mask inspecting apparatus of the present invention. In these drawings, 1 is a phase shift mask 2 pattern shading film, 3 is the pattern step, a light source 4, 4 _1, 7 ₁ pinhole plate, 5 a condenser lens, 6 denotes an objective lens, 7 an optical A detector, 8 is a compound wavelength light, 9 is a first wavelength light, and 10 is a second wavelength light.

In the phase shift mask inspection apparatus of the present invention shown in this figure, the circuit pattern is formed by the pattern light-shielding film 2 and the phase shift mask 1 having the pattern steps 3 is mounted on an XY stage (not shown). It is set so that it can be moved in the horizontal direction, a light source 4 that emits the composite wavelength light 8 is arranged on it, and the composite wavelength light 8 emitted from this light source 4 is made into a point light source by a pinhole plate 4 ₁ . The composite lens 5 collects the compound wavelength light 8 which is made incident on the phase shift mask 1 and transmitted through the phase shift mask 1, and is condensed by the objective lens 6, and is made by the pinhole plate 7 ₁ . The first wavelength light 9 or the second wavelength light 10 is detected by a photodetector 7 (point photodetector) having a function of blocking light other than the detection target.

With reference to these figures, a phase shift mask inspecting apparatus of the present invention and a phase shift mask inspecting method using the apparatus will be described. [First stage] The pattern light-shielding film 2 is driven by driving the XY stage.
And the pattern step 3 of the phase shift mask 1 having the pattern step 3 are removed from the optical axis, the focus of the condenser lens 5 is adjusted, and the focus of the first wavelength light 9 of the composite wavelength light 8 emitted from the light source 4 is adjusted. To the upper surface of the pattern step 3 which is the surface of the phase shift mask 1.

Then, in this state, the objective lens 6 is adjusted so that the first wavelength light 9 transmitted through the phase shift mask 1 passes through the pinhole of the pinhole plate 7 ₁ and is focused on the surface of the photodetector 7. To do. At this time, the second wavelength light 10 is not focused on the upper surface of the pattern step 3 of the phase shift mask 1, is focused on the vicinity of the bottom surface of the pattern step 3, and is not focused on the surface of the photodetector 7 ( (See FIG. 1).

3A and 3B are characteristic diagrams of transmitted light intensity distribution after passing through the phase shift mask. FIG. 3A shows a state in which the optical axis is on the upper surface of the pattern step, and FIG. 3B shows the optical axis in the pattern step. It shows the state. In this figure, 7 ₁ indicates a pinhole plate, 9 ₀ indicates a transmitted light intensity distribution of wavelength light, and 10 ₀ indicates a transmitted light intensity distribution of wavelength light. The pattern step 3 of the phase shift mask 1 is deviated from the optical axis, and the first wavelength light 9 of the compound wavelength light 8 emitted from the light source 4 is focused on the upper surface of the pattern step 3 and transmitted through the phase shift mask 1. In the state where the first-wavelength light 9 is adjusted so as to pass through the pinhole of the pinhole plate 7 ₁ and focus on the surface of the photodetector 7 (see FIG. 1), the first wavelength in FIG. As shown in the transmitted light intensity distribution 9 ₀ of the wavelength light, the intensity of the first wavelength light 9 is dominant, and the second is the optical intensity as shown in the transmitted light intensity distribution 10 ₀ of the wavelength light. The intensity of the second wavelength light 10 that is not focused on the surface of the detector 7 remains at a low level.

[Second Step] Next, a state in which the condenser lens 5 and the objective lens 6 are made to focus the first wavelength light 9 of the composite wavelength light 8 emitted from the light source 4 on the upper surface of the pattern step 3 While maintaining, the XY stage is driven to move the pattern step 3 of the phase shift mask 1 to the optical axis (see FIG. 2).
In this state, the first wavelength light 9 of the composite wavelength light 8 emitted from the light source 4 is the pattern step 3 of the phase shift mask 1.
The light path changes because it passes through the bottom surface of the photodetector, and when it enters the surface of the photodetector 7, it has a large cross section as shown by the solid line, but most of it is blocked by the pinhole plate 7 ₁ for detection. It does not fit in vessel 7.

However, the second wavelength light 10 of the composite wavelength light 8 emitted from the light source 4 has its optical path changed because it passes through the phase shift mask 1 and the objective lens 6, as shown by the broken line. The light is focused on the surface of the detector 7 through the pinhole of the pinhole plate 7 ₁ .

[0031] In this state, as the second FIG. 3 (B) are shown in the transmitted light intensity distribution 10 ₀ wavelength light, the intensity of the second wavelength 10 becomes dominant, first wavelength as shown in the transmitted light intensity distribution 9 ₀ of the light, the intensity of the first wavelength light 9 not focused on the surface of the photodetector 7 is stopped at a low level.

According to the phase shift mask inspection method or its apparatus of the present invention described above, the first wavelength light 9 or the second wavelength light 10 having a sharp peak is identified by the interference filter or the like and detected by the photodetector 7. However, since it can be converted into a color coordinate system and quantified as a vector of hue and brightness, for example, the transmitted light of the first wavelength light 9 is converted into an electric signal and compared with a reference pattern signal, or
By comparing the electric signals of the transmitted light signals of the plurality of pattern steps 3 formed on the same phase shift mask with each other, the contour portion of the pattern steps 3 of the phase shift mask can be accurately and automatically inspected. it can.

When the depth of the pattern step 3 is different, the level of the transmitted light passing through the pinhole of the pinhole plate 7 ₁ and reaching the surface of the photodetector 7 (dotted photodetector) is different. Similarly, for example, the signal of the photodetector 7 corresponding to the transmitted light of the first wavelength light 9 is compared with the reference pattern signal,
Alternatively, the depth of the pattern step 3 of the phase shift mask can be inspected by comparing the transmitted lights of the plurality of pattern steps 3 formed on the same phase shift mask with each other.

FIG. 4 shows the results of observation by the phase shift mask inspection apparatus of the present invention. FIGS. 4A and 4B show transmitted light intensity distributions of two pattern steps. In this figure, 1 is a phase shift mask, 2 ₁ and 2 ₂ are pattern light-shielding films, 3 ₁ and 3 ₂ are pattern steps, 9 ₁ and 9 ₂ are transmitted light intensity distributions of the first wavelength light, 10 ₁ and 10 ₂ Shows the transmitted light intensity distribution of the second wavelength light.

In this figure, a deep pattern step 3 ₁ and a pattern light-shielding film 2 ₁ formed on one phase shift mask 1 are shown.
Transmitted light intensity distribution 9 ₁ of the first wavelength light and the transmitted light intensity distribution 10 _{1 of} the second wavelength light, and transmitted light of the first wavelength light transmitted through shallow pattern step 3 ₂ and pattern light-shielding film 2 _2. An intensity 9 ₂ and a transmitted light intensity distribution 10 _{2 of} the second wavelength light are schematically shown.

Transmitted light intensity distribution of the first wavelength light in this figure
9₁, 9₂, Intensity distribution of transmitted light of second wavelength light 10₁, 10
₂As shown in, the pattern of the phase shift mask 1 is
Step 3 ₁, 3₂First wave due to changes in depth
Long light transmitted light intensity 9₁, 9₂And the transmitted light intensity of the second wavelength light
10 degrees₁, 10₂The first wave because the trends of increase and decrease of
Long light transmitted light intensity 9₁, 9₂And the transmitted light intensity of the second wavelength light
10 degrees₁, 10₂By calculating the difference of and comparing
Pattern step 3 of phase shift mask 1₁, 3₂The depth of
It becomes possible to measure with high accuracy.

This point is the same when comparing the depths of the pattern steps 3 ₁ and 3 ₂ of the phase shift mask 1 with the reference signal. Although the above description is for detecting the inspection light transmitted through the phase shift mask 1, the principle of the present invention is to detect the inspection light that is incident on the upper surface of the phase shift mask and reflected in the vicinity of the pattern step. The same applies when detecting.

[0038]

EXAMPLES Examples of the present invention will be described below. (First Embodiment) FIG. 5 is a diagram showing the construction of a phase shift mask inspection apparatus according to the first embodiment. In this figure, 11
Is a point light source optical system, 12 is a phase shift mask, 13 is XY
A stage, 14 is a focus adjustment mechanism, 15 is a focus adjustment control device, 16 is a point light detector, 17 is a pattern data image processing device, 18 is an image comparison device, and 19 is a pattern defect information storage device. The point light source optical system 11 is, for example, the light source and the pinhole plate which are shown in principle in FIG. 1 and the like, and the point light detector 16 is the light which is shown in principle in FIG. 1 and the like. It is similar to the detector and pinhole plate.

In the phase shift mask inspection apparatus of this embodiment, the compound wavelength light emitted from the point light source optical system 11 is applied to the phase shift mask 12 mounted on the XY stage 13 moving in the XY plane, The light transmitted through the phase shift mask 12 is detected by the spot light detector 16 by identifying the light of each wavelength.

The XY stage 13 is controlled by a focus adjustment control device 15 to which a signal detected by the point photodetector 16 is input, and is controlled by a focus adjustment mechanism 14 which drives the XY stage 13 up and down. It
In addition, the signal detected by the point photodetector 16 passes through the image comparison device 18 and the pattern data image processing device 17
And is stored in the pattern defect information storage device 19.

A method of comparing the signal of the pattern step of the phase shift mask with the reference signal by the phase shift mask inspection apparatus of this embodiment will be described. The point light source optical system which moves in the horizontal direction by the XY stage 13 so that the portion to be inspected of the phase shift mask is directly below the point light source optical system 11 and has optimum chromatic aberration according to the depth of the pattern step of the phase shift mask 12. Under the system 11, the focus adjustment mechanism 1 that can be finely adjusted so that the light having a specific wavelength of the inspection light used for the inspection is focused on the upper surface of the phase shift mask 12.
4, the XY stage 13 is moved in the vertical direction. In this state, the XY stage 13 is moved so that the entire inspection target area is directly below the optical axis.

Even if the reference is determined so that the light having a specific wavelength of the inspection light is focused on the bottom surface of the step of the phase shift mask 12, the pattern abnormality can be detected by the same principle. Defects in the pattern light-shielding film 2 can be detected more accurately when the reference is set on the upper surface.

The image obtained by the point photodetector 16 is compared with required design data by the image comparison device 18 in advance by the pattern data image processing device 17.
Is compared with the data converted to an image by. The comparison is performed for each field of view of the microscope. At that time, when a mismatch point is detected, the coordinates and the shape thereof are stored in the pattern defect information storage device 19. After all the inspections in the phase shift mask are completed, the pattern defect is confirmed by the information stored in the pattern defect information storage device 19 in the same manner as the conventional inspection method. The same applies to the case of comparing and inspecting a plurality of pattern steps formed on the same phase shift mask.

As the light source of the phase shift mask inspection apparatus of this embodiment, a low-pressure mercury lamp (584 nm), a high-pressure mercury lamp, a tank stainless lamp, a sodium lamp (589 nm), or a cadmium lamp (644n) was used.
m), a helium discharge tube (588 nm), a thallium lamp (535 nm), or the like, or a plurality of light sources are used in combination by, for example, an optical system using a semitransparent mirror.

(Second Embodiment) FIG. 6 is a diagram showing the construction of a phase shift mask inspection apparatus according to the second embodiment. In this figure, 21 is a phase shift mask, 22 is a pattern light-shielding film, 23 is a pattern step, 24 is a laser light source, 25 is a diverging lens, 26 is a condenser lens, 27 is an objective lens, 28
Indicates a pinhole plate, and 29 indicates a photodetector.

In the phase shift mask inspection apparatus of this embodiment, a laser light source (He-Ne, 633 nm) 24 that emits light of a plurality of wavelengths is used as the light source of the phase shift mask inspection apparatus described above with reference to FIG. Is used. In this case, a pinhole plate or slit for making a point light source is not necessary, but instead, for example, a diverging lens 25 is attached to spread the laser light and cause chromatic aberration by the condenser lens 26.

The structure and operating method of the phase shift mask inspecting device of this embodiment are the same as those of the first embodiment, and therefore their explanations are omitted. Note that a plurality of laser light sources are used in combination by an optical system as in the above.

In the case where the inspection patterns of the phase shift mask of each of the above-described embodiments are used to compare and inspect repeated patterns formed in one phase shift mask substrate, the detection results are stored and stored. It is also possible to make a comparison with the above-mentioned two optical systems, and it is also possible to use two of the above-mentioned optical systems and set an optical system that allows the inspection light to pass through the two selected patterns for simultaneous comparison. Further, in order to impart chromatic aberration to an optical system such as an objective lens, this optical system may be constructed by combining glass lenses having an appropriate refractive index.

[0049]

As described above, when the method for inspecting a phase shift mask or the apparatus thereof according to the present invention is used, a clear image is obtained by selectively using light of a specific wavelength and the contour portion of the pattern step is removed. Since it is possible to inspect with precise dimensional accuracy, and it is possible to collectively inspect the shape and depth of the contour portion of the pattern step by identifying and using a plurality of lights having different wavelengths. The highly demanded inspection of a fine phase shift mask can be performed with high accuracy and speed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram (1) of a phase shift mask inspection apparatus of the present invention.

FIG. 2 is an explanatory diagram (2) of the phase shift mask inspection apparatus of the present invention.

3A and 3B are characteristic diagrams of transmitted light intensity distribution after passing through a phase shift mask, in which FIG. 3A shows a state where the optical axis is on the upper surface of the pattern step, and FIG. 3B shows a state where the optical axis is inside the pattern step. ing.

4A and 4B are observation results obtained by the phase shift mask inspection apparatus of the present invention, and FIGS. 4A and 4B show transmitted light intensity distributions of two pattern steps.

FIG. 5 is a configuration explanatory diagram of a phase shift mask inspection apparatus according to the first embodiment.

FIG. 6 is a structural explanatory view of a phase shift mask inspection apparatus of a second embodiment.

FIG. 7 is an explanatory diagram of a conventional phase shift mask inspection apparatus.

FIG. 8 is an observation result (1) by a conventional phase shift mask inspection apparatus.

9A and 9B show observation results (2) by a conventional phase shift mask inspection apparatus, and FIGS. 9A and 9B show transmitted light intensity distributions of two pattern steps.

[Explanation of symbols]

1 Phase shift mask 2 Pattern light-shielding film 2 ₁ , 2 ₂ Pattern light-shielding film 3 Pattern step 3 ₁ , 3 ₂ Pattern step 4 Light source 4 ₁ Pinhole plate 5 Condenser lens 6 Objective lens 7 Photodetector 7 ₁ Pinhole plate 8 Compound wavelength light 9 First wavelength light 9 ₀ , 9 ₁ , 9 ₂ Transmitted light intensity distribution of first wavelength light 10 Second wavelength light 10 ₀ , 10 ₁ , 10 ₂ Transmitted light intensity distribution of second wavelength light 11 Point light source Optical system 12 Phase shift mask 13 XY stage 14 Focus adjustment mechanism 15 Focus adjustment control device 16 Point photodetector 17 Pattern data image processing device 18 Image comparison device 19 Pattern defect information storage device 21 Phase shift mask 22 Pattern light-shielding film 23 pattern Step 24 Laser light source 25 Divergence lens 26 Condensing lens 27 Objective lens 28 Pinhole plate 29 Photodetector

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazumasa Doi 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (10)

[Claims] 1. A compound wavelength light containing lights of different wavelengths is condensed by an optical system, and lights of different wavelengths dispersed by chromatic aberration of the optical system are incident on a phase shift mask having a pattern step, and the phase shift is performed. A method for inspecting a phase shift mask, which selectively detects light having different wavelengths that are transmitted or reflected by the mask. 2. The phase shifter according to claim 1, wherein a point light source and a point detector are used to selectively detect light having different wavelengths that are transmitted or reflected by the phase shift mask. Mask inspection method. 3. A chromatic aberration in which light of a longer wavelength is focused from the surface of the phase shift mask to the bottom surface of the pattern step or vice versa from the bottom surface of the pattern step to the surface of the phase shift mask. An optical system is used, The inspection method of the phase shift mask of Claim 1 or Claim 2 characterized by the above-mentioned. 4. The contour portion or depth of the pattern step is inspected by comparing an inspection signal corresponding to the contour portion or depth of the pattern step with a reference signal. The method for inspecting the phase shift mask according to any one of items. 5. The contour portion or the depth of the pattern step is inspected by mutually comparing inspection signals corresponding to the contour portion or the depth of the plurality of pattern steps formed on the phase shift mask. The method for inspecting the phase shift mask according to any one of claims 1 to 3. 6. A light source that emits compound wavelength light containing lights of different wavelengths, and the light having different wavelengths is dispersed by chromatic aberration in the process of condensing the compound wavelength light and is incident on a phase shift mask having a pattern step. And a photodetector that selectively detects light of different wavelengths that are transmitted or reflected by the phase shift mask. 7. A point light source is a light source that emits compound wavelength light containing lights of different wavelengths, and a point detector is a photodetector that selectively detects light of different wavelengths that is transmitted or reflected by a phase shift mask. 7. The phase shift mask inspection device according to claim 6, wherein the inspection device is a device. 8. A chromatic aberration such that light having a longer wavelength is focused from the surface of the phase shift mask to the bottom surface of the pattern step or vice versa from the bottom surface of the pattern step toward the surface of the phase shift mask. The phase shift mask inspection apparatus according to claim 6 or 7, further comprising an optical system. 9. The method according to claim 6, further comprising means for inspecting the contour portion or the depth of the pattern step by comparing an inspection signal corresponding to the contour portion or the depth of the pattern step with a reference signal. The inspection device of the phase shift mask described in any one of items 8 to 8. 10. A means for inspecting the contour portion or the depth of the pattern step by comparing the inspection signals corresponding to the contour portion or the depth of the plurality of pattern steps formed on the phase shift mask with each other. The phase shift mask inspection device according to any one of claims 6 to 8.