JPH11354404A - Method and apparatus for inspecting mask blank and reflecting mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine the presence of defects in a mask blank, by exposing a multi-layer film type mask blank in which a resist pattern becomes an absorbing pattern to extreme ultraviolet radiation through a specified optical system, transferring an image to a resist coated on a wafer, and comparing and inspecting the transferred pattern as the image. SOLUTION: First, a multi-layer film type mask blank is formed (S101). Next, a specified mark is formed on the multi-layer film type mask blank (S102). The multi-layer film type blank is cleaned and inspected with contamination (S103, S104). A resist pattern is formed on the multi-layer film type blank using an extreme ultraviolet radiation apparatus (EUV), etc., and visual inspection is performed (S105, S106). Further, the multi-layer film type blank formed with a pattern is transferred to a resist on a wafer by EUV and visual inspection is performed (S107, S108). The presence of defects, or the position, the size and the number of the defects if usable as a reflecting mask is recorded and the resist pattern is removed (S109, S110).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture or inspection of an optical element used for forming an image by exposure or irradiation of vacuum ultraviolet light or extreme ultraviolet light, and is particularly suitable for pattern transfer in the manufacture of semiconductor devices. The present invention relates to a reflective mask, an inspection method thereof, and a manufacturing method thereof.

[0002]

2. Description of the Related Art In order to improve the degree of integration and operating speed of LSI solid-state elements, circuit patterns have been miniaturized. At present, reduction projection exposure using ultraviolet light as an exposure light source is widely used for forming these patterns. The resolution of this method is proportional to the exposure wavelength λ and inversely proportional to the numerical aperture NA of the projection optical system on the wafer side. Improvement of resolution limit is achieved by numerical aperture N
This has been done by increasing A. However, this approach is approaching its limits due to reduced depth of focus and difficulties in refractive optics (lens) design and manufacturing techniques. For this reason, means for shortening the exposure wavelength λ has been used. For example, from the g-line (λ = 435.8 nm) of a mercury lamp to the i-line (λ =
365 nm) and a KrF excimer laser (λ = 24
8 nm), and an ArF excimer laser (λ = 193 nm).

[0003] Resolution is improved by shortening the exposure wavelength. Also, a technique called super-resolution exposure has made it possible to form a pattern having a size smaller than the wavelength used for exposure. However, due to the fundamental limit of the wavelength of the ultraviolet light used for exposure, it is 0.1 μm (100 μm).
It is very difficult to obtain sub-nm) resolution for various patterns.

On the other hand, as a method for forming a fine pattern, there is a close-to-one size X-ray lithography in which a soft X-ray having an exposure wavelength of about 0.5 nm to 2 nm is used. In this method, since the exposure wavelength is short, there is a possibility that a high resolution of 0.1 μm or less can be obtained in principle. Generally, in order to form a circuit pattern on a desired element, a pattern on a mask is transferred to a resist on a wafer. 1x magnification in proximity 1x X-ray lithography
A transmission mask called a line mask is used. 1x X
The portion of the line mask through which X-rays are transmitted is formed of a thin film having a thickness of about 2 μm, which is usually formed of a light element material called a membrane, such as Si, SiN, SiC, or C.

[0005] As a portion of an equal-magnification X-ray mask that absorbs X-rays, a thickness called an absorber on the membrane is set to be equal to 0,0.
A circuit pattern made of a heavy metal such as W, Au, Ta or the like or a compound thereof is formed at about 3 μm to 0.7 μm. Therefore, since the circuit pattern is formed on a very rigid membrane in the 1: 1 X-ray mask, the internal stress of the heavy metal of the absorber and the external force when the X-ray mask is mounted on a predetermined exposure apparatus are used. There is a problem that the pattern is distorted and a desired circuit pattern cannot be transferred to a resist at a predetermined position on a wafer. In particular, in close-to-one-size X-ray lithography, since the pattern of the one-to-one X-ray mask is transferred to the resist at a one-to-one ratio, the distortion of the pattern on the one-to-one X-ray mask is transferred to one-to-one. 1 × with low rigidity
The problem of distortion in the line mask pattern is that the
It is a major challenge in line lithography.

Based on the above background, EUV lithography using extreme ultraviolet (EUV) having a wavelength of about 5 nm to 50 nm as an exposure light source has recently been receiving attention. This is, for example, the Japanese Journal of Applied Physi
cs), 1991, No. 30, Vol. 11B, page 3051.

FIG. 1 shows an example of an exposure optical system for EUV lithography. EUV 4 is used as an exposure light source to illuminate the reflective mask 81 by obliquely incident at an incident angle 42 (θ). The angle of incidence 42 is different for various optical systems, but is approximately 1 °.
About 15 ° from On the reflective mask 81, a multilayer film 2 capable of regular reflection of EUV and a predetermined pattern (not shown) are formed. The EUV reflected from the reflective mask is reflected by the convex mirror 92, and further reflected by the concave mirror 91.
And an image is formed on the wafer 82. The reflective mirror multilayer film 7 is formed on the entire surface of the convex mirror 92 and the concave mirror 91. Here, for the substrate 1 used as an optical element such as a reflection type mask, an ultra-smooth substrate without roughness is required to obtain a high reflectance.

[0008] Conventional reflective masks for EUV are known, for example, from the Journal of Vacuum Science and Technolog.
y), B9, No. 6, 1991, p3176-p318
3. As described in the above section, a region having a high reflectivity is formed as a portion where a multilayer film is present, and a region having a low or no reflectivity is formed as a portion where a multilayer film or a multilayer structure is not present.

In FIG. 2A, the multilayer film 2 on the substrate 1 is transformed by the focused ion beam 5 in a direction perpendicular to the substrate to form a low-reflectance region or a non-reflection portion 3. , A pattern is formed in the region 21 having a high reflectance. In addition, as shown in FIG. 2B, a predetermined portion of the multilayer film 2 is removed to form a portion having no multilayer film, that is, a non-reflection portion 3. Also, as shown in FIG. 2C, a pattern of an absorber 35 having a predetermined thickness and shape is formed on the multilayer film 2 directly adhered to the ultra-smooth substrate 1, and a reflection type mask as a non-reflection portion is formed. There are examples.

When the wavelength of vacuum ultraviolet rays or X-rays used for exposure or irradiation becomes smaller, it is necessary to increase the number of multilayer films to increase the reflectance of the multilayer film to vacuum ultraviolet rays or X-rays. In order to obtain a high reflectance, for example, about 50 pairs or more at X-ray wavelength of 13 nm, about 100 pairs or more at 10 nm, and about 150 pairs or more at 7 nm.

FIG. 3 shows a typical method of manufacturing a reflection type mask. First, in order to obtain a high reflectance, a multilayer film 2 is formed on an ultra-smooth substrate 1 having almost no roughness (FIG. 3A). What formed the multilayer film 2 on the ultra-smooth substrate 1 is generally called a multilayer blank mask or multilayer blanks. The multilayer film 2 is usually formed by a physical vapor deposition method such as an ion beam sputtering vapor deposition method or a magnetron sputtering vapor deposition method, a chemical vapor deposition method (CVD), or an atomic layer deposition method (A).
LE) is used.

Next, an absorber 35 serving as a non-reflective portion of the reflective mask is formed (FIG. 3B). As in the case of the formation of the multilayer film, a physical vapor deposition method such as an ion beam sputtering vapor deposition method and a magnetron sputtering vapor deposition method, a chemical vapor deposition vapor deposition method (CVD), and the like are usually used to form the absorber 35. W, Ta, Au, Cr, T
Metals such as i, Ge, Ni, and Co, metalloids, and simple substances or compounds of semiconductor materials are used.

Next, in order to form a desired absorber pattern by patterning the absorber, a resist 38 is formed on the absorber (FIG. 3C), i-line exposure, KrF excimer laser exposure, A resist pattern 39 is formed by a lithography technique such as line beam drawing, 1: 1 exposure X-ray, ion beam exposure, and EUV exposure (FIG. 3D).

Next, the absorber is processed by reactive ion etching or the like using the resist pattern as a mask to form a pattern of the absorber 35 (FIG. 3E). Next, the resist pattern 39 is removed (FIG. 3F).

Usually, during or after manufacturing a reflective mask or the like, it is necessary to inspect the reflective mask and correct any defects found. If the defect cannot be corrected, it will be a defective product. Generally, the size of a defect on a mask that cannot be ignored is considered to be about 1/5 of the minimum processing size in a normal exposure method, as described in, for example, Monthly Semiconductor World, June 1997, p150-p154. For example, when the minimum pattern size on the mask is 0.4 μm, the minimum defect size on the mask that cannot be ignored is 80 nm. Further, when a so-called super-resolution exposure method such as a phase shift exposure method or a modified illumination exposure method is used, it is necessary to consider a size up to about 1/7 of a minimum processing dimension.
When the minimum pattern size on the mask is 0.4 μm, the smallest defect size on the mask that cannot be ignored is about 57 n.
m.

4 (a) and 4 (b), a white defect 401 (a desired absorber is missing) or a black defect 402 (the absorber has a desired shape) in the absorber portion of the reflective mask shown in FIG. Can be corrected by gas-assisted vapor deposition (correction of white defects) or ion beam etching (correction of black defects) using a conventional ion beam.

On the other hand, in the multilayer film of the reflection type mask, as the number of laminated multilayer films increases, the possibility of defects occurring in the film increases. FIG. 5 shows a defect 501 caused by a foreign substance 504 and a defect 502 caused by a scratch 503 of the substrate 11, which are examples of defects in the multilayer film of the reflection mask.
In a reflective mask manufactured from a multilayer film having a defect, a desired decrease in reflectance occurs at a defective portion, and a desired pattern may not be transferred. In addition, a desired pattern may not be transferred due to a change in the phase of the defective portion due to the defect.

As for the defect inspection of a multilayer film of a reflection type mask, an inspection apparatus using a so-called X-ray microscope is disclosed in Japanese Patent Application Laid-Open No. 6-349715. In addition,
As described in Japanese Patent Application No. 9-318330, there is disclosed an inspection apparatus that scans an object to be inspected with a laser beam of visible light or ultraviolet light, causes light scattering, and checks a light scattering state to find a defect.

[0019]

However, the above X
A defect inspection apparatus using a line microscope has a visual field area of at most several square mm at most, and it is necessary to sequentially scan the visual field area in order to inspect the entire surface of the multilayer film of the reflection type mask of 100 square cm or more, As a result, there is a problem that the inspection requires a long time. Further, since the defect inspection of the multilayer film of the reflection type mask only examines the reflectance of the multilayer film, there is a problem that it is not possible to detect all the defects that cause a change in phase. In addition, since the inspection device that scans the laser light to cause light scattering and checks the light scattering state also detects only a change in the external shape of the reflective mask surface, it also detects all defects that cause a phase change in EUV. There was a problem that could not be done. Therefore, when a reflective mask is formed from a multilayer blank having a defect that causes a phase change in the multilayer film, the reflective mask that has not been defective in the above mask inspection is used as a non-defective product in the device manufacturing process. Only when transfer is performed by exposure, the existence of a defect becomes apparent, and there has been a problem that the device manufacturing process is greatly hindered.

The present invention provides a method for easily and inexpensively inspecting any defect in a multilayer film of a reflection type mask, an inspection apparatus therefor,
It is another object of the present invention to provide a multilayer blank, a reflective mask manufactured using the same, and a device manufactured using the same.

[0021]

According to the method for inspecting a reflective mask of the present invention, a resist pattern which can be easily peeled off is formed on a multilayer blank which is an optical element, and this resist pattern becomes an absorber pattern. EU blanks
Exposure is performed with a V light through a predetermined optical system, and the image is transferred to, for example, a resist applied to a wafer. It is characterized in that the presence or absence of a defect in the blanks is determined by comparing the transfer pattern, which is the image, with the pattern formed on the multilayer blank or the data thereof.

Further, the inspection method of the reflection type mask of the present invention comprises:
A resist pattern that can be easily peeled off is formed on the multilayer film blanks that are optical elements, and the resist pattern is used to expose the multilayer film blanks that will become the absorber pattern with EUV light through a predetermined optical system, for example, to be applied to a wafer. Transferred to the resist. By comparing the transferred pattern and the pattern formed on the multilayer blank or its data, defect information such as the presence or absence of a defect in the blank and the size of the existing defect is obtained, and according to the defect information in the multilayer blank. It is characterized in that a reflective mask to be applied is determined.

Further, the inspection method of the multilayer blanks or the reflection type masks of the present invention comprises exposing the multilayer blanks whose resist pattern becomes an absorber pattern with EUV light through a predetermined optical system, so that the image blank is located at or near an image point. When transferring to a resist or the like on a certain wafer, the phase difference between the reflected wave from the resist pattern formed on the multilayer film blanks and the reflected wave from the portion where the resist pattern is not formed is almost inverted, and The intensity of the reflected wave from the resist pattern formed on the multilayer blank is approximately 3% of the intensity of the reflected wave from the portion where the resist pattern is not formed.
The thickness of the resist pattern is adjusted so as to be 10%, and the multilayer film blank in which the resist pattern having the above film thickness becomes a halftone absorber pattern is exposed and transferred with EUV light, and the transferred pattern is inspected. Alternatively, a pattern formed on the multilayer blanks or data thereof is compared.

Further, the inspection method of the reflection type mask of the present invention comprises:
Two-beam interference occurs when a multilayer film blank whose resist pattern becomes an absorber pattern is exposed to EUV light through a predetermined optical system to form an image on a resist or the like on a wafer at or near an image point and transfer it. Then, the transferred pattern is compared and inspected, or the transferred pattern is compared with the pattern formed on the multilayer blank or its data.

In the method for inspecting a multilayer blank or a reflective mask according to the present invention, the multilayer blank having a resist pattern as an absorber pattern is exposed to EUV light via a predetermined optical system and transferred to a resist or the like on a wafer. When doing
In addition to the exposure at the focal position, the exposure is performed with the focal position shifted, and the transferred pattern is compared and inspected, or the transferred pattern is compared with the pattern formed on the multilayer blank or its data.

The method for inspecting a multilayer blank or a reflection type mask according to the present invention is also directed to a method of exposing a multilayer blank having a resist pattern formed thereon to become an absorber pattern with EUV light through a predetermined optical system. In addition to the exposure at the optimal exposure amount, exposure is performed at an exposure amount shifted from the optimal value, and the transferred pattern is compared, inspected, or the transferred pattern and the pattern formed on the multilayer blanks or their data are transferred. It is characterized by comparing.

In the inspection method of a multilayer blank or a reflection type mask according to the present invention, after forming a resist pattern on the multilayer blank, the multilayer blank is exposed to EUV light via a predetermined optical system, and is exposed on a wafer. As a method of comparing a resist pattern formed by transferring to a resist or the like with a pattern formed on a multilayer blank or its data, a method of comparing data of a pattern formed on a multilayer blank with a transferred pattern, a transferred pattern The method is characterized by performing at least one of a method of comparing the same with the same transfer pattern in another place, and a method of inspecting the transferred pattern itself.

Further, the inspection apparatus of the present invention for inspecting a multilayer blank or a reflection type mask includes means for forming a resist pattern on the multilayer blank, means for inspecting the formed resist pattern, and a method for inspecting the multilayer blank with EUV light. Means for exposing through a predetermined optical system and transferring to a resist or the like on a wafer to form a resist pattern; means for transferring a defect of a resist pattern formed by transferring the multilayer blanks; and a result of the inspection. Is included.

Further, the multilayer blank or the reflective mask of the present invention is characterized by being manufactured by using the inspection method and the inspection apparatus for the multilayer blank or the reflective mask of the present invention.

The method of manufacturing a device according to the present invention is characterized in that the method includes a step of exposing and transferring a pattern to a wafer using the multilayer blank or the reflective mask of the present invention.

The device of the present invention is characterized by being manufactured by using the method for manufacturing a device of the present invention.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be disclosed with reference to the flowchart of FIG. The embodiment of the present invention includes steps S101 to S112 in FIG. In S101, a multilayer blank is formed. First, as shown in FIG. 7, an ultra-smooth substrate 1 made of quartz, BK7,
A thin film 119 such as iO ₂ is deposited by ion beam sputtering, magnetron sputtering, chemical vapor deposition, or the like. However, this thin film is not always necessary, but becomes necessary when regenerating an ultra-smooth substrate in step S1081 described later.

Next, the multilayer film 21 is deposited by an ion beam sputtering method, a magnetron sputtering method, a chemical vapor deposition method or the like to form a multilayer film blank 601.
The multilayer film 21 has a thickness of, for example, 2.6 n per layer.
m of Mo layer and a Si layer having a thickness of 4.1 nm per layer.
The layers are formed alternately in 60 layer pairs.

Next, as shown in FIG. 8, a mark 702 is formed on the multilayer blank 601. After forming a resist on the upper layer of the multilayer blank, an electron beam lithography system, a g-line exposure system, an i-line exposure system, a KrF excimer laser exposure system,
Exposure or drawing is performed using an ArF excimer laser exposure device or a laser drawing device and the like, and development is performed to form a resist pattern of a predetermined mark outside the effective area 701 of the multilayer blank. Here, the effective area is an area on which a pattern of a semiconductor integrated circuit or the like is formed and which effectively functions as a reflective mask. That is, it is a region of the integrated circuit chip 703 where the integrated circuit pattern is formed.

In FIG. 8, two chips can be mounted in the effective area of the multilayer blanks. Also, at least one mark is required,
6, Step S107, Step S108, Step S
In step 109, it is desirable to form three or more marks independently for positioning the multi-layer film blank and for locating the surface. As the resist to be used, either a negative resist or a positive resist can be used. In this case, a positive resist is desirable. The mark portion is exposed, and after development, the exposed portion becomes a space without resist. ing. Next, using this resist as a mask, a predetermined mark pattern is formed outside the integrated circuit chip by dry etching or a lift-off method. Then, unnecessary resist is stripped and removed.

Next, the multilayer blanks are washed in step S103, and dust in the multilayer blanks is inspected in step S104. If there is dust in the multilayer blanks, the process returns to step S103, and the washing is performed. Step S10
Inspection of dust of the multilayer blanks of 4 scans and irradiates the multilayer blanks with light using visible light or ultraviolet light as a light source,
By detecting the scattered light, the presence or absence of dust can be checked from the light scattering state.

Next, in step S105, a resist is formed on the multilayer film blanks, and the resist is exposed and developed to form a line and space resist pattern over the entire effective area of the multilayer film blanks. Exposure means used for forming the line and space pattern include an i-line exposure apparatus, a KrF excimer laser exposure apparatus,
An rF excimer laser exposure device, a laser scan exposure device, an electron beam lithography device, an equal-size X-ray exposure device, an EUV exposure device, or the like can be used.

Here, the size of the line and space of the resist formed on the multilayer blank depends on the size of the minimum defect that must be considered. In other words,
It depends on the minimum pattern size of the reflective mask when the multilayer blank to be inspected is used as the final reflective mask.

For example, when the multilayer blank to be inspected is used as a final reflective mask, the minimum pattern size formed by transferring the reflective mask is 0.1.
μm, and when the reduction ratio of the exposure apparatus using this reflective mask is １ ／, the minimum pattern size of the reflective mask when the multilayer blank to be inspected is used as the final reflective mask is 0.4 μm. Becomes A 0.4 μm line and space resist pattern is formed over the entire effective area of the multilayer blank to be inspected, and is transferred to the resist on the wafer by a normal exposure method using a 1/4 reduction EUV exposure apparatus. I do.

If the multilayer blanks have a thickness of 0.4 μm,
If there is a defect having a size of / 5 or 80 nm or more, a defect occurs in the resist pattern on the transferred wafer. In this case, a defect of 80 nm or more can be detected. Also, when the resist on the wafer is transferred by the super-resolution exposure method using an EUV exposure apparatus with a reduction ratio of 1/4, the multilayer film blanks have a defect of 57 nm or more which is 1/7 of 0.4 μm. If there is, a defect occurs in the resist pattern on the transferred wafer. In this case, a defect of 57 nm or more can be detected. If a smaller defect is to be detected, the line and space dimensions of the resist formed on the multilayer blanks may be reduced. Therefore, the dimension of the line and space of the resist formed on the multilayer blank to be inspected here is set to be equal to or smaller than the minimum pattern dimension of the reflective mask when the multilayer blank to be inspected is used as the final reflective mask. Good.

Next, the appearance of the resist pattern formed on the multilayer blanks in step S106 is inspected. Inspection of the pattern formed on the multilayer blanks is performed by comparing the data of the pattern formed on the multilayer blanks with the formed pattern itself, comparing the transferred pattern with the same pattern transferred from another location, the transferred pattern itself There is a method for inspecting the transferred pattern. As a means for examining the transferred pattern, a method of taking a pattern image from a microscope using light, an electron beam, etc., a method of examining the presence or absence of a defect from a light scattering state, an optical pattern filtering (OPF) Method or the like can be used.

Here, the inspection result information of the resist pattern formed on the multilayer blanks is stored in a storage device. If there is a defect in the resist pattern formed on the multilayer blank, the process proceeds to step S1061, the resist pattern is peeled off, the multilayer blank is washed, and the process returns to step S105.

However, the number of defects present in the resist pattern formed on the multilayer blank is small, and the minimum pattern size of the reflective mask when the multilayer blank to be inspected is used as the final reflective mask. If it is also smaller, it is not necessary to go to step S1061, and the position and size of the defect are stored, and the data including these defects is used as the data of the resist pattern formed on the multilayer blank, and the process proceeds to the next step.

Next, in step S107, the multilayer blanks having the line and space resist pattern formed on the entire effective area are transferred to the resist on the wafer using an EUV exposure apparatus with a reduction ratio of 1/4, and then developed. I do. Here, the reduction ratio of the EUV exposure apparatus does not need to be 1/4, and for example, a 1: 1 EUV exposure apparatus is also possible. However, it is necessary to make the size of the line and space resist pattern formed on the multilayer blanks finer.

Here, the EUV exposure apparatus 1 with a reduction ratio of 1/4
502 is shown in FIG. The multilayer blanks 81 and the wafer 82, each having a resist pattern formed on the entire effective area,
They are mounted on a mask stage 83 and a wafer stage 84, respectively. First, the relative position between the mask and the wafer is detected by using the alignment device 85, and the control device 86 performs the positioning via the driving devices 87 and 88. EUV
The EUV radiated from the light source 89 is illuminated through the illumination optical system 90, the arc-shaped aperture 98, and the long wavelength cut filter 97 to illuminate the circular arc region on the multilayer blank in which the resist pattern is formed over the entire effective area. Here, as the EUV light source, for example, a laser plasma light source or a synchrotron radiation light source (SR) that irradiates a gas jet Xe target with laser light to generate EUV can be used. The illumination optical system 90 shown in FIG.
Although only the surface is illustrated, the present invention is not limited to this case, but includes the type of light source, uniformity of illumination, uniformity of incident NA,
A plurality of reflecting mirrors for the illumination optical system may be installed as necessary to secure a work area.

The positional relationship between the multilayer blanks having a resist pattern formed on the entire surface of the effective area and the incident EUV is as follows: the short axis direction of the thinner resist pattern, the deficient direction of the incident EUV, and the long axis direction of the thinner resist pattern. The longitudinal direction of the line and space pattern was set to be the meridional direction of the incident EUV. EUV reflected by the multilayer blanks having a resist pattern formed on the entire effective area is composed of EUV having a wavelength of about 13 nm, and is formed by an imaging optical system 95 including reflecting mirrors 91, 92, 93 and 94.
As a result, an image is formed on the wafer at a magnification of 1/4. Reflector 9
In Nos. 1, 92, 93 and 94, a Mo / Si-based multilayer film similar to the multilayer blanks is deposited, and the cycle length of each multilayer film is adjusted so that the wavelength of the reflected EUV coincides. The multilayer blank and the wafer were scanned synchronously according to the magnification, and the resist pattern formed on the entire effective area of the multilayer blank was transferred to the resist applied to the wafer. By such a method, a 0.1 μm line and space resist pattern is obtained in a 26 mm square area on the wafer.

Next, in step S108, the appearance of the transferred resist pattern on the wafer is inspected. The means for comparing the pattern transferred on the wafer with the pattern formed on the multilayer blanks includes (1) comparing the data of the pattern formed on the multilayer blanks with the transferred pattern, and (2) transferring the transferred pattern to another location. And (3) inspecting the transferred pattern itself. As means for examining the transferred pattern, a method of taking a pattern image from a microscope using light, an electron beam, or the like, How to check for the presence of defects from the light scattering state,
A method using an optical pattern filtering (OPF) method or the like can be applied. Here, the inspection apparatus may use the apparatus used in step S106.

In an EUV exposure apparatus, the resist pattern on the transferred wafer may be distorted due to aberrations specific to the imaging optical system of each exposure apparatus. Is stored, and when inspecting the transferred resist pattern on the wafer, the inspection is performed by correcting the distortion due to the aberration peculiar to the imaging optical system of the exposure apparatus.

When the multilayer blank having the resist pattern formed thereon is exposed by an EUV exposure apparatus and transferred to a resist or the like on a wafer, a reflected wave from the resist pattern formed on the multilayer blank and a resist pattern are formed. The phase difference from the reflected wave from the portion not formed is almost inverted, and the intensity of the reflected wave from the resist pattern formed on the multilayer blanks is lower than the intensity of the reflected wave from the portion where the resist pattern is not formed. Almost 3% to 1
The thickness of the resist pattern may be adjusted so as to be 0%. At this time, since the resist pattern having the above film thickness becomes a halftone absorber pattern, when exposing and transferring this multilayer film blanks with EUV light, it is possible to sensitively detect defects in the multilayer film portion immediately below the resist pattern. Therefore, by comparing and inspecting the transferred resist pattern or comparing the transferred resist pattern with the pattern formed on the multilayer blank or its data, the resolution of the defect inspection of the multilayer blank is improved.

When transferring the multilayer film blanks using an EUV exposure apparatus, the mask side (multilayer film blanks side) of the projection optical system of the EUV exposure apparatus is used to improve the imaging performance of the EUV exposure apparatus. NA and N on the lighting system side
Exposure may be performed by changing the ratio with A. In normal exposure, the ratio is about 0.5 to 0.7, and in super-resolution exposure, the ratio is about 0.3 to 0.5.

Further, when the multilayer blank on which the resist pattern is formed is exposed by an EUV exposure apparatus and transferred to a resist or the like on a wafer, deformed illumination is performed. FIG.
As shown in FIG. 13, the normal exposure light source (FIG. 13 (d)) has a ring shape (FIG. 13 (a)) or a four-open shape (FIG. 13 (a)).
(B)) Alternatively, exposure is performed with a light source (FIG. 13C) in which a suitable partial aperture stop 1306 is inserted in the light source. Oblique illumination is performed by relatively inclining the multilayer blank and the optical axis incident on the multilayer blank so as to pass through a substantially symmetrical position on the pupil plane. This increases the imaging resolution when exposing and transferring the multilayer blanks with EUV light, so that small defects existing in the multilayer film can be transferred to the resist on the wafer with sensitivity. Comparison, inspection or
By comparing the transfer resist pattern with the pattern formed on the multilayer blank or its data, the resolution of the defect inspection of the multilayer blank is improved. here,
Exposure may be performed with an appropriate ratio between the NA on the mask side (multilayer film blanks side) and the NA on the illumination system side of the projection optical system of the above-described EUV exposure apparatus according to each super-resolution exposure method. .

Further, the multilayer film blank on which the resist pattern has been formed is exposed by an EUV exposure apparatus, and when transferring to a resist or the like on a wafer, exposure in which the focal position is shifted in addition to the exposure at the focal position is performed. By comparing and inspecting the transferred pattern or comparing the transferred pattern with the pattern formed on the multilayer blank or its data, the effect of the defect existing in the multilayer blank on the transferred pattern and the imaging of the EUV exposure apparatus used The influence of the distortion caused by the aberration peculiar to the optical system on the transfer pattern can be separated, and the resolution of the defect inspection of the multilayer blanks is improved.

The multilayer film blank having the resist pattern formed thereon is exposed by an EUV exposure apparatus, and is transferred to a resist or the like on a wafer. By comparing and inspecting the transfer pattern and the pattern formed on the multilayer blank or its data, the resolution of the defect inspection of the multilayer blank is improved.

If the result of step S108 is that there are too many defects in the multilayer blanks so that they cannot be used as a reflective mask, the process proceeds to step S1081, where the resist pattern is stripped, the multilayer blanks are washed, the multilayer is removed, the thin film is removed, and the substrate is washed. And regenerate the substrate. However, in step S101, a thin film 11 made of aluminum, SiO _2, or the like is deposited on the ultra-smooth substrate 11 made of quartz, BK7, or the like shown in FIG.
If the substrate 9 is not formed, the substrate cannot be reclaimed, so that the multilayer blanks having many defects that cannot be used as a reflective mask are discarded, and a new multilayer blank is started in S101.

As a result of step S108, if there is no defect present in the multilayer blank, or if the defect can be used as a reflective mask, the position, size, number, etc. of the defect existing in the multilayer blank are determined in step S109. The defect information is stored, and in step S110, the resist pattern of the multilayer blank is peeled and removed, and the multilayer blank is washed. Here, if necessary, re-inspection is performed to increase the inspection accuracy of the multilayer blanks. In this case, step S1
Return to 05. At the time of the re-inspection, the dimension of the resist pattern formed on the multilayer blank in step S105 may be different from that of the previous inspection.

In order to re-inspect the multilayer blanks, in step S105, a resist is again formed on the upper layer of the multilayer blanks, exposure or drawing is performed by a predetermined exposure device, and after development, the entire surface of the effective area of the multilayer blanks is developed. To form a line and space pattern. Usually the effective area of the multilayer blanks is more than 100 square cm, while
i-line exposure equipment, KrF excimer laser exposure equipment, ArF
A reduction projection exposure apparatus such as an excimer laser exposure apparatus and an EUV exposure apparatus and an equal-size X-ray exposure apparatus are exposure apparatuses using step-and-repeat or step-and-scan, and the exposure field per exposure is at most 10
It is about square cm. Therefore, a plurality of step-and-repeat or step-and-scan operations are required to expose the effective area of the multilayer blank over the entire surface.

FIG. 10 (a) shows a situation in which the entire surface of the effective area 701 of the multilayer blank 601 is exposed by an exposure apparatus using step-and-repeat or step-and-scan in the first multilayer blank inspection. Starting from the first exposure field 1001, exposure is performed a total of 16 times according to the arrow 1005 indicating the order of exposure, the last exposure field 1002 is exposed, and exposure of the entire effective area 701 is completed. Here, mark 70
The position of each exposure field is accurately determined by using the positioning mechanism 2 and the positioning mechanism of the exposure apparatus to avoid double exposure between each exposure field.

On the other hand, in the re-inspection, an exposure or drawing method of a line and space pattern different from the previous inspection is used. FIG. 10B shows a state in which the entire surface of the effective area 701 of the multilayer blank 601 is exposed by an exposure apparatus using step-and-repeat or step-and-scan in the re-inspection. First exposure part 100
Starting from 3, exposure is performed 25 times in total according to the arrow 1006 indicating the order of exposure, the last exposed portion 1004 is exposed, and exposure of the entire effective area 701 is completed. here,
The exposure field 1007 is exposed to include a boundary between each exposure field in the first inspection, for example, the boundary 1009, and the exposure field 1010 is included to include the boundary 1010.
08 is exposed. As a result, it is possible to avoid overlooking a defect in the multilayer blanks that may be present at the boundary between the exposure fields in the first inspection, thereby improving the resolution of the inspection.

As shown in FIG. 11, a mark 70 is placed at the position of the space of the line and space pattern 1103 in the exposure field 1101 exposed in the first inspection.
2 and the positioning mechanism of the exposure apparatus to accurately position each exposure field, and perform exposure such that the line of the line and space pattern 1104 in the exposure field 1102 in the second inspection exposure is located. As a result, it is possible to avoid overlooking a defect in the multilayer blank that may be present below the pattern position of the line and space pattern in the first inspection, thereby improving the resolution of the inspection.

In step S105, when a line and space resist pattern is formed over the entire effective area of the multilayer blank using a laser scan exposure apparatus, an electron beam lithography apparatus, or the like, as shown in FIG.
01, the position of the line and space pattern 1203 in the drawing field 1201 drawn in the first inspection is used to accurately position the drawing field using the mark 702 and the positioning mechanism of the drawing apparatus, and the drawing of the second inspection is performed. Line and space pattern 120 in
Drawing is performed so that the position of line 4 comes. As a result, it is possible to avoid overlooking a defect in the multilayer blank that may be present below the pattern position of the line and space pattern in the first inspection, thereby improving the resolution of the inspection.

If re-examination is not necessary anymore, the process proceeds to step S112. According to the defect information such as the position, size, and number of defects present in the inspected multilayer film blank, whether to use it for a normal exposure mask or a super-resolution exposure mask is determined. Is a good product.

Next, a manufacturing process of a reflective mask using the multilayer blanks according to one embodiment of the present invention will be disclosed. FIG. 14 shows a reflective mask manufacturing process including the production and inspection of a multilayer blank.

An aluminum thin film 119 is applied to an ultra-smooth substrate 1 made of quartz by ion beam sputtering to form an aluminum thin film 119.
Deposit 0 nm thickness. Next, the multilayer film 21 is deposited by ion beam sputtering, and the
Sheets were formed. The multilayer film 21 has a thickness of 2.6 n per layer.
An Mo layer of m and a Si layer having a thickness of 4.1 nm per layer were alternately formed in pairs of 60 layers (FIG. 14A).

Next, according to the flow of FIG. 6, the multilayer blanks are inspected using the multilayer blank inspection method of the present invention and the inspection apparatus shown in FIG.
No defect with a size of m or more was found, and the other two defects with a size of 70 nm were found. Therefore, a multilayer blank having no defect with a size of 40 nm or more is used as a mask for super-resolution exposure, and a multilayer blank with two defects having a size of 70 nm is used as a normal exposure mask. (FIG. 14 (b)).

Next, an absorber 35 to be a non-reflective portion of the reflective mask was formed (FIG. 14C). For forming the absorber 35, an ion beam sputtering vapor deposition method was used as in the case of forming the multilayer film. A 120 nm thick Cr film was formed as an absorber. Here, if necessary, a protective film made of a light element may be formed before and after the formation of the absorber.

Next, in order to pattern the absorber 35 and form a desired absorber pattern, a resist is formed on the absorber (FIG. 14 (d)), and an electron beam A resist pattern was formed by a lithography technique based on drawing (FIG. 14E). Where 4
For a multilayer blank having no defect of 0 nm or more in size, since it is used as a mask for super-resolution exposure, the minimum size is 32 mm.
A gate pattern of 0 nm and a hole pattern of a minimum dimension of 320 nm were formed. In addition, a wiring pattern having a minimum dimension of 440 nm was formed on a multilayer blank in which two defects having a size of 70 nm were found, for use as a normal exposure mask.

Next, the absorber is processed by reactive ion etching using the resist pattern as a mask, and the absorber 35 is processed.
(FIG. 14 (f)). Next, the resist pattern was removed (FIG. 14G). An appearance inspection of the manufactured reflective mask was performed, and it was confirmed that the formed absorber pattern had no defect.

A device was manufactured using the reflective mask manufactured as described above. FIG. 20 shows a device manufacturing process flow. First, in the oxidation step of step S2001, the surface of the wafer is oxidized. In the CVD step of step S2002, an insulating film is formed on the wafer surface. Step S2003
In the wiring step, a wiring material to be an electrode is formed on the wafer by an evaporation method. In the implantation step of step S2004, ions are implanted into the wafer. In the step of forming a resist film in step S2005, a resist is applied to the wafer and prebaked. In the exposure step in step S2006, the circuit pattern of the reflective mask manufactured as described above is transferred and exposed on the wafer by the EUV exposure apparatus shown in FIG. In the developing step of Step S2007, the wafer is developed. In the etching step of step S2008, portions other than the resist image remaining after the development are removed by dry etching. In the resist removing step of step S2009, the resist is removed. By repeating these steps, a multilayer circuit pattern is formed on the wafer.

If the device manufacturing method of the present invention is used,
Conventionally, a highly integrated semiconductor device that has been difficult to manufacture due to a defect that causes a phase change existing in a reflective mask for EUV and has a low yield can be manufactured with a high yield using a reflective mask for EUV without defects.

In the inspection method of a multilayer blank or a reflection type mask according to the present invention, after forming a resist pattern on the multilayer blank, the multilayer blank is subjected to EU.
As a means for comparing a resist pattern formed by exposing to a resist or the like on a wafer by exposure with V light and a pattern formed on a multilayer blank, a method of comparing data transferred from a pattern formed on a multilayer blank with a transferred pattern And comparing at least one of a method of comparing the transferred pattern with the same transferred pattern in another place, and a method of inspecting the transferred pattern itself.

As shown in FIG. 15, the inspection apparatus 2202 for the multilayer blanks or the reflection type mask of the present invention comprises:
Equipment for forming resist patterns on multilayer film blanks 15
01, an apparatus 1502 for exposing the multilayer blanks to EUV light and transferring the resist to a wafer or other resist, and an apparatus 15 for developing the transferred resist to form a resist pattern
03, an apparatus 1504 for inspecting a resist pattern formed on the multilayer blank and a defect of the resist pattern formed by transferring the multilayer blank. Here, reference numeral 1507 denotes a cleaning device.

FIG. 16 shows an example using a light microscope, FIG. 17 shows an example using light scattering, and FIG. 18 shows an OPF as an example of an apparatus 1504 for inspecting a resist pattern formed by transferring the above-mentioned multilayer film blanks. FIG. 19 shows an example using the electron beam microscope.

Here, reference numeral 1601 in FIG.
602, an illumination optical system; 1603, an objective lens system;
4 is a detector, 1605 is an A / D converter, 1606 is a computer and a control device and a defect information storage device and an inspection result discriminator, 1607 is a multilayer blank and a wafer, 1609 is a stage, 1610 is incident light, and 1611 is reflection. Indicates light.

Also, 1701 in FIG. 17 is a laser light source, 1702 is an illumination optical system, 1703 is a multilayer film blank and wafer, 1704 is a condenser lens, 1705 is a detector, 1708 is an A / D converter, and 1709 is a computer. And a control device, a defect information storage device and an inspection result discriminator, 1710 is a stage, 1711 is scattered light,
Reference numeral 1712 denotes a light receiver.

Also, 1801 in FIG. 18 is a coherent light source, 1802 is an illumination optical system, 1803 is a multilayer film blank and wafer, 1804 is a Fourier transform lens,
1805 is an optical filter, 1806 is an inverse Fourier transform lens, 1807 is a light receiver, 1808 is a detector,
1809 is a computer and a control device, a defect information storage device and an inspection result discriminator, 1810 is a stage,
Reference numeral 1811 denotes reflected light, 1812 denotes incident light, and 1813 denotes a reflecting mirror.

Further, reference numeral 1901 in FIG.
902 is an electron beam, 1903 is a convergent lens, 1904
Is an objective lens, 1905 is a multilayer blank or wafer having a resist pattern formed thereon, 1906 is a deflection coil, 1907 is a secondary electron, 1908 is a secondary electron detector, 19
09 is an A / D converter, 1910 is an image memory, 1911
Denotes an image processing apparatus, 1912 denotes a display, 1913 denotes a mask cassette, 1914 denotes a sample chamber, 1915 denotes an XY stage, 1916 denotes a computer and a control device and a defect information storage device, and 1917 denotes an A / D converter.

FIG. 22 shows a synchrotron radiation light source 2
1 shows an exposure system including an EUV mask inspection apparatus 2202 using an EUV exposure apparatus 201 and an EUV exposure apparatus 2203 for manufacturing a device. In the figure, reference numeral 2201 denotes a synchrotron radiation light source; 2202, an inspection apparatus for a multilayer blank or a reflective mask; 2203, an EUV exposure apparatus; and 2204, an injector. By using such a system and using a synchrotron radiation light source as an EUV light source, the light source of the mask inspection apparatus and the light source of the exposure apparatus for device fabrication can be shared.

Here, regarding the materials used for the multilayer film,
Although only the case of the Mo / Si-based multilayer film has been described, the present invention is not limited to the materials described here, and may be, for example, NiCr / C, Ni / V, Ni / Ti, W / C,
Ru / C, Rh / C, Ru / BN, Rh / BC, RhR
u / BN, Ru / BC, Mo / SiC, Pd / BN, A
g / BN, Mo / SiN, Mo / BC, Mo / C, Ru
Any material that can form a multilayer film such as / Be can be used.

[0079]

As described above, in the inspection and manufacture of multilayer film blanks, by applying the inspection method, the inspection apparatus and the manufacturing method of the present invention, the phase change existing in the EUV reflective mask can be reduced. Defects caused can be inspected in a short time, and depending on the degree of defect of the multilayer blank, it is also possible to apply the multilayer blank to a reflective mask, thereby improving the yield and cost of the multilayer blank and the reflective mask. Become. In addition, by using the device manufacturing method of the present invention, a highly integrated semiconductor device that has been difficult to manufacture and has a low yield due to a defect existing in a reflective mask for EUV that causes a phase change can be removed. It can be manufactured with a high yield using a reflective mask for EUV.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a conventional EUV exposure apparatus.

FIG. 2 is a cross-sectional view of a conventional EUV reflective mask.

FIG. 3 is a cross-sectional view showing a conventional EUV reflection mask manufacturing process.

FIG. 4 is a cross-sectional view and a plan view of a conventional reflective mask having a defect that can be corrected.

FIG. 5 is a cross-sectional view showing a conventional reflective mask having a defect in a multilayer film.

FIG. 6 is an inspection flowchart of a blank and a mask according to one embodiment of the present invention.

FIG. 7 is a sectional view showing an example of a multilayer blank.

FIG. 8 is a plan view of a multilayer blank according to one embodiment of the present invention.

FIG. 9 is an EU which is a part of the inspection apparatus according to one embodiment of the present invention.
FIG. 4 is an explanatory diagram of a V exposure apparatus.

FIG. 10 is an explanatory view of an exposure method for forming a resist pattern on blanks according to one embodiment of the present invention.

FIG. 11 is an explanatory view of an exposure method for forming a resist pattern on blanks according to one embodiment of the present invention.

FIG. 12 is an explanatory diagram of a drawing method for forming a resist pattern on blanks according to one embodiment of the present invention.

FIG. 13 is an explanatory diagram of an exposure light source used in the EUV exposure apparatus according to one embodiment of the present invention.

FIG. 14 is a cross-sectional view showing a step of manufacturing an EUV reflection mask according to one embodiment of the present invention.

FIG. 15 is a block diagram of an inspection apparatus according to one embodiment of the present invention.

FIG. 16 is a block diagram of a main part of an inspection apparatus according to one embodiment of the present invention.

FIG. 17 is a block diagram of a main part of an inspection apparatus according to one embodiment of the present invention.

FIG. 18 is a block diagram of a main part of an inspection apparatus according to one embodiment of the present invention.

FIG. 19 is a block diagram of a main part of an inspection apparatus according to one embodiment of the present invention.

FIG. 20 is a manufacturing process diagram of the semiconductor device and the like.

FIG. 21 is a block diagram of an EUV exposure apparatus using an EUV reflective mask according to one embodiment of the present invention.

FIG. 22 is a conceptual diagram of an EUV reflection type mask inspection system and a device manufacturing system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ultra smooth substrate, 2 ... Multilayer film, 3 ... Non-reflection part (or area | region with low reflectance), 4 ... Incident EUV or vacuum ultraviolet rays or X-ray, 5 ... Focused ion beam, 7 ... Multilayer film for reflecting mirrors, 11 ... substrate, 21 ... reflection part, 22 ... multilayer film pattern (high reflectance area), 35 ... absorber, 38 ... resist, 39 ... resist pattern, 41 ... reflection vacuum ultraviolet ray or X-ray, 42 ... incident angle, 381: resist pattern,
81: Reflective mask, 82: Wafer, 83: Mask stage, 84: Wafer stage, 85: Alignment device, 86: Control device, 87: Drive device, 88: Drive device, 89: X-ray source, 90: Reflecting mirror , 91 ... Reflector, 92
.. Reflecting mirror, 93 reflecting mirror, 94 reflecting mirror, 95 imaging optical system, 96 synchronous scanning direction, 119 thin film layer between substrate and multilayer film, 401 white defect, 402 black defect, 501 Defect due to foreign matter, 502 ... Defect due to scratch, 503
... foreign matter in the multilayer film, 504 ... scratch, 601 ... multilayer blank, 701 ... effective area, 702 ... mark,
703: chip area, 1101: exposure field, 11
02 exposure field, 1103 line and space pattern, 1104 line and space pattern, 1201 drawing field, 1203 line and space pattern, 1204 line and space pattern drawn in the second and subsequent inspections, 1301 optical axis , 1302... Annular zone opening, 1303.
.. 4 opening shapes, 1305... Partial opening, 1306... Partial stop (dark part), 1307... Normal light source, 1501.
03: Wafer developing device, 1504: Pattern inspection device, 15
05: Movement of multilayer blanks, 1506: Movement of wafers, 1507: Cleaning device for multilayer blanks.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tsuneo Terasawa 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo Inside Central Research Laboratory, Hitachi, Ltd.

Claims (7)

[Claims] A step of forming a peelable pattern on a blank on which a multilayer film capable of reflecting extreme ultraviolet light is formed on a substrate; and a step of forming the multilayer film blank having the pattern with extreme ultraviolet light via a predetermined optical system. A blanks inspection method comprising: a step of exposing and transferring an image to obtain an image; and a step of inspecting the image. 2. A step of forming a peelable pattern on a blank on which a multilayer film capable of reflecting extreme ultraviolet light has been formed on a substrate, and a step of forming the multilayer film blank having the above-mentioned pattern with extreme ultraviolet light via a predetermined optical system. A blanks inspection method comprising: a step of exposing and transferring an image to obtain an image; and a step of comparing the image with a pattern formed on the blanks or data thereof. 3. A step of forming a peelable pattern on a blank on which a multilayer film capable of reflecting extreme ultraviolet rays is formed on a substrate, and the step of forming the multilayer blanks having the above-mentioned pattern with extreme ultraviolet rays via a predetermined optical system. A blanks inspection method comprising: a step of exposing and transferring an image to obtain an image; a step of inspecting the image; and a step of determining a reflective mask to be applied according to an inspection result of the image. 4. An apparatus for forming a peelable pattern on a blank on which a multilayer film capable of reflecting extreme ultraviolet light is formed on a substrate, and a multilayer film blank having said pattern is exposed to extreme ultraviolet light via a predetermined optical system. An apparatus for inspecting blanks, comprising: an apparatus for obtaining an image by exposure transfer, an apparatus for inspecting the image, and an apparatus for storing a result of the inspection. 5. A reflection type mask manufactured by using the blank inspection method according to claim 3. 6. A method for manufacturing a device, comprising a step of exposing and transferring a pattern on a wafer using the reflective mask according to claim 5. 7. A device manufactured by the manufacturing method according to claim 6.