JP2004004791A - Halftone phase shift mask blank and halftone phase shift mask - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a halftone phase shift mask etc., which copes with different two inspection wavelengths in inspection using reflection and make it possible to obtain sufficient inspection accuracy even when either of the inspection wavelengths is used. <P>SOLUTION: The phase shifter films of the halftone phase shift mask blank consist of multilayered films laminated with at least two or more layers including the upper layer formed on the most surface side and the lower layer formed thereunder and is adjusted in the film thickness of the upper layer in such a manner that the refractive index of the film of the upper layer for the wavelength of the inspection light used for the halftone phase shift mask manufactured by using the halftone phase shift mask blank is smaller than the refractive index of the film of the lower layer and that the surface reflectivity for the inspection light of the phase shifter films turns to the desired reflectivity for the different two or more inspection wavelengths. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a phase shift mask capable of improving the resolution of a transfer pattern by utilizing the interference effect of light by a phase shifter, a phase shift mask blank as a material thereof, and more particularly to a halftone type phase shift mask and mask Related to blanks and the like.
[0002]
[Prior art]
One of the realizations of the super-resolution technology in recent photolithography is a phase shift mask. Among them, a halftone phase shift mask has been widely used as a main application mainly for forming a contact hole, since pattern processing at the time of manufacturing the mask is relatively easy. More recently, application to repetitive patterns such as line and space (L & S) and isolated patterns in DRAMs and the like has been advanced.
As shown in FIG. 7, the halftone type phase shift mask has at least a light transmitting portion 7 and a halftone phase shifter portion 8 having a light semi-transmitting property and a phase shifting function on a transparent substrate 2. However, from the aspect of the configuration of the halftone phase shifter section 8, it can be roughly classified into a single-layer type and a multilayer type. The single-layer type is currently the mainstream because of its easy workability, and most of the half-tone phase shifters are composed of a single-layer film made of MoSiN or MoSiON. On the other hand, in the multi-layer type, the halftone phase shifter section is composed of a combination of a layer that mainly controls transmittance and a layer that mainly controls the amount of phase shift. The amount (phase angle) can be controlled independently.
Meanwhile, with miniaturization of an LSI pattern, the wavelength of an exposure light source (exposure light wavelength), the current KrF excimer laser (248 nm), the ArF excimer laser (193 nm), and more future _{F 2} excimer laser (157 nm ) Is expected to be shorter. As the wavelength of the exposure light source becomes shorter, the range of selection of materials for the halftone phase shifter portion that satisfies a predetermined transmittance and a phase shift amount tends to be narrowed. Also, with the shortening of the wavelength of the exposure light source, a material having a high light transmittance is required when viewed at a conventional wavelength, and as a result, the etching selectivity with a quartz substrate during pattern processing is reduced. is there. The multi-layer (two-layer film) halftone phase shifter has the advantage that the phase difference and transmittance can be controlled by the combination of the two-layer film and the material selection is easy, and the material that plays the role of the upper layer etching stopper is used. Since there is an advantage that it can be selected as a lower layer (Patent Document 1: Japanese Patent Application No. 2001-174973), a multi-layer (two-layer) halftone phase shifter is being developed.
[0003]
[Patent Document 1] Japanese Patent Application No. 2001-174973
[0004]
[Problems to be solved by the invention]
By the way, in a photomask, a reflection optical system has been conventionally used for foreign matter / defect inspection. In addition, in recent years, not only conventional transmission optical systems but also reflection optical systems have been used in mask pattern appearance inspection, and in order to obtain sufficient inspection sensitivity, light semi-transmission at the light source wavelength of the device is required. The reflection contrast between the part and the substrate has become necessary.
Further, when inspecting a so-called tritone type halftone type phase shift mask having a light transmitting part, a light semi transmitting part, and a light shielding part on the light semi transmitting part, the light transmitting part / light semi transmitting part, light half A reflection contrast is required for each of the transmission part / light shielding part and the light transmission part / light shielding part. Specifically, when the light reflectance at the light source wavelength of the light transmitting portion, the light semi-transmitting portion, and the light shielding portion is R1, R2, and R3, respectively,
R1 <R2 <R3
Needs to be
By the way, in order to detect a small defect of 0.1 μm or less and a finer pattern, the light source of the inspection device is expected to have a shorter wavelength from i-line (365 nm) to around 200 to 300 nm which is a DUV (deep ultraviolet) region. However, since it is currently in a transition period, it is desired that the mask and the mask blank have optical characteristics corresponding to both the i-ray light source and the DUV light source inspection apparatus. In addition, 266 nm, 257 nm, etc. are currently considered as DUV light sources.
However, in the two-layer halftone type phase shift mask including the transmittance adjusting layer and the phase adjusting layer, the light reflectance greatly fluctuates in a range including the above-described wavelength, and therefore, one inspection wavelength (for example, i-line wavelength). However, even if sufficient reflection characteristics can be obtained by using the above method, there is a problem that it cannot be obtained at the other inspection wavelength (DUV wavelength). For this reason, the design of the halftone film has to be changed in accordance with the wavelength of the light source of the inspection apparatus, which has been a heavy burden in development.
[0005]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has a halftone which, in an inspection using reflection, can cope with two different inspection wavelengths and can obtain sufficient inspection accuracy even when any of the inspection wavelengths is used. It is an object to provide a phase shift mask blank and a halftone type phase shift mask.
It is another object of the present invention to provide a halftone phase shift mask blank and a halftone type phase shift mask which can obtain sufficient inspection accuracy with a light source of an inspection apparatus in both the i-line wavelength and the DUV region. .
[0006]
[Means for Solving the Problems]
The present invention has the following configuration.
(Structure 1) The light transmitting section, comprising a light transmitting section for transmitting exposure light and a phase shifter section for transmitting a part of the exposure light and simultaneously shifting the phase of the transmitted light by a predetermined amount on a transparent substrate. By designing the optical characteristics so that the light transmitted through each other near the boundary of the phase shifter and the phase shifter cancel each other, the contrast at the boundary of the exposure pattern transferred to the surface of the object to be exposed can be maintained and improved satisfactorily. A halftone type phase shift mask blank used for manufacturing the halftone type phase shift mask as described above, wherein the halftone type phase shift mask blank has a phase shifter film for forming the phase shifter part on a transparent substrate At
The phase shifter film is a multilayer film in which at least two or more layers including an upper layer formed on the most surface side and a lower layer formed thereunder are laminated, and the halftone type phase shift mask blank is used. The refractive index of the upper layer film with respect to the wavelength of the inspection light used for inspection of the halftone type phase shift mask manufactured by the above is smaller than the refractive index of the lower layer film, and the surface reflectance of the phase shifter film with respect to the inspection light is lower. A halftone phase shift mask blank characterized in that the thickness of the upper layer is adjusted so that a desired reflectance is obtained for two or more different inspection wavelengths.
(Structure 2) The halftone type according to Structure 1, wherein the exposure light has a wavelength selected from a wavelength of 140 nm to 200 nm, and the two or more different inspection wavelengths are selected from a wavelength of 240 to 370 nm. Phase shift mask blank.
(Structure 3) The halftone according to Structure 2, wherein the thickness of the upper layer is adjusted so that the surface reflectance of the phase shifter film is maximized at a wavelength selected from a wavelength of 220 nm to 340 nm. Type phase shift mask blank.
(Configuration 4) exposure light, halftone phase shift mask blank according to any of the 1-3, which is a F ₂ excimer laser.
(Configuration 5) The halftone type according to any one of Configurations 1 to 3, wherein the exposure light is an ArF excimer laser, and the transmittance of the phase shifter film is adjusted to 8 to 30%. Phase shift mask blank.
(Structure 6) The phase shifter film is formed of a two-layer film in which the phase angle of the exposure light is changed by approximately 180 ° and the transmittance for the exposure light is adjusted to 3 to 40%. The phase adjustment layer mainly having a function of adjusting a phase angle, and the lower layer is a transmittance adjustment layer mainly having a function of reducing transmittance. Halftone phase shift mask blank.
(Structure 7) A half, wherein a light transmitting portion and a halftone phase shifter portion are formed by patterning a phase shifter film in the halftone phase shift mask blank according to any one of Structures 1 to 6. Tone type phase shift mask.
(Structure 8) The halftone phase shift mask according to Structure 7, wherein a light-shielding layer is formed in a desired region excluding the vicinity of a boundary between the halftone phase shifter portion and the light transmitting portion.
(Configuration 9) A method for manufacturing a halftone phase shift mask, comprising a step of performing a pattern appearance inspection of the halftone phase shift mask according to configuration 7 or 8.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
The present invention provides a halftone type phase shift mask blank, in which a phase shifter film is a multilayer film in which at least two or more films including an upper layer formed on the most surface side and a lower layer formed thereunder are laminated. The refractive index of the upper layer film with respect to the wavelength of the inspection light used for inspection of the halftone phase shift mask manufactured using the halftone type phase shift mask blank is smaller than the refractive index of the lower layer film, and The film thickness of the upper layer is adjusted so that the surface reflectance of the phase shifter film with respect to the inspection light has a desired reflectance with respect to two or more different inspection wavelengths.
That is, according to the present invention, the phase shifter film is formed of a multilayer film in which at least two or more films are stacked, and the refractive index of the upper layer film at the inspection wavelength is made smaller than the refractive index of the lower film. The reflectance with respect to the inspection light can be adjusted. Also at the exposure wavelength, by making the refractive index of the upper layer film smaller than the refractive index of the lower layer film, the reflectivity to the exposure light can be adjusted so as to be less than a required value. When a two-layer halftone phase shifter film having a high refractive index for the upper layer and a low refractive index for the lower layer is used, the reflected light of the lower layer and the reflected light of the upper layer cause interference, and the reflectance of the entire two-layer film is reduced to a wavelength. On the other hand, a curve (reflection spectrum) of the interference wave is drawn. Thus, the present invention adjusts the film thickness of the upper layer so that the maximum value of the reflection spectrum is at a predetermined wavelength, that is, between two different inspection wavelengths, so that the desired value is obtained at two different inspection wavelengths. Reflectivity can be realized.
Note that the inspection here includes inspection of pattern defects of mask blanks or masks and inspection of foreign matter and appearance.
The reflectance that can be used in these tests is 5 to 40%, and preferably 10 to 30%, from the viewpoint of reflectance detection sensitivity.
[0008]
Hereinafter, a half-tone type phase shift mask blank having a two-layer structure for responding to both the inspection light having the wavelength of i-line (365 nm) and the wavelength of DUV (240 to 300 nm, for example, 257 nm) will be described.
The reflectance of the halftone phase shifter portion with respect to the inspection light having the wavelength λ is d = λ / (2n) (1)
It becomes maximum at the time. Here, n is the refractive index of the upper layer with respect to light of wavelength λ.
In the present invention, by setting the above-mentioned λ between 220 nm and 340 nm, a desired reflectance can be obtained in both i-line and DUV, so that inspection using i-line and inspection using DUV can be performed. In both cases, inspection is possible.
In the present invention, the phase shifter film is a two-layer film in which the phase angle of the exposure light is changed by approximately 180 ° and the transmittance for the exposure light is adjusted to 3 to 40%. It is a phase adjustment layer mainly having a function of adjusting the phase angle, and the lower layer is a transmittance adjustment layer mainly having a function of lowering the transmittance. specifically, the preferable for obtaining a blank suitably used in 193 nm (particularly transmittance 8% and 30% of high transmittance article) is the wavelength of 157nm and ArF excimer laser with a wavelength of _{F 2} excimer laser.
The phase adjustment layer mainly has a function of adjusting the phase, but also has a function of adjusting the transmittance. On the other hand, the transmittance adjusting layer mainly has a function of adjusting the transmittance, but also has a function of adjusting the phase.
That is, when the phase shift angle of the exposure light required as the phase shifter film in the halftone type phase shift mask blank (halftone type phase shift mask) is A (deg), the phase shift amount of the exposure light by the phase adjustment layer Is φ1 and the phase shift amount of the exposure light by the transmittance adjusting layer is φ2,
0 <φ2 <φ1 <A (deg) (Equation 1)
It becomes the relationship.
Further, a two-layer structure in which the upper layer is a layer (phase adjustment layer) that mainly functions to adjust the amount of phase shift, and the lower layer is a layer (transmittance adjustment layer) that mainly functions to adjust the transmittance. In this case, for example, the film is designed as follows.
That is, assuming that the phase shift amount φ (deg) of the exposure light having the wavelength λ that passes through the upper layer (phase adjustment layer) is φ1, the thickness d of the phase adjustment layer is as follows.
d = (φ1 / 360) × λ / (n−1) (formula 2)
Is represented by Here, n is the refractive index of the phase adjustment layer with respect to the light having the wavelength λ.
The phase shift amount Φ of the halftone phase shifter portion is, when the phase shift amount of the lower layer (transmittance adjusting layer) is φ2,
Φ = φ1 + φ2 = A (deg) (Equation 3)
It is necessary to design so that The value of φ2 is generally in the range of −20 ° ≦ φ2 ≦ 20 °. That is, if the thickness is out of this range, the thickness of the lower layer is too large, so that the transmittance of the exposure light cannot be increased. Therefore, the thickness d of the upper layer is 0.44 × λ / (n−1) ≦ d ≦ 0.56 × λ / (n−1) (Equation 4)
Designed in the range.
Note that the phase shift amount of the halftone phase shifter film is ideally 180 °, but may be in the range of 180 ° ± 5 ° in practical use.
Further, the transmittance of exposure light is preferably 3 to 20%, preferably 6 to 20%, and the exposure light reflectance is preferably 40% or less, preferably 30% or less, and more preferably 20% or less, from the viewpoint of pattern transfer. .
[0009]
As the material of the transmittance adjusting layer, a film made of one or more kinds selected from metal or silicon, or an oxide or nitride thereof can be used.Specifically, aluminum, titanium, vanadium, A film made of one or more materials selected from chromium, zirconium, niobium, molybdenum, lanthanum, tantalum, tungsten, silicon, and hafnium, or a nitride thereof is used.
Further, as the phase adjustment layer, a thin film containing silicon as a base such as silicon oxide, silicon nitride, or silicon oxynitride is preferable because a relatively high transmittance to exposure light in an ultraviolet region is easily obtained. Furthermore, since these materials can easily control the refractive index, they are also excellent in controllability of the phase shift angle, which is a key point of the phase shifter. Further, since the main skeleton as the film material is silicon oxide or silicon nitride, it has excellent chemical durability. Specifically, a material containing silicon, oxygen and / or nitrogen, or a material containing one or more selected from phosphorus, boron, and carbon may be contained therein.
Such a phase adjustment layer can be usually etched by dry etching using a fluorine-based gas. As the fluorine-based gas, for example, C _x F _y (for example, CF ₄ , C ₂ F ₆ , C ₃ F ₈ ), CHF ₃ , SF _6, a mixed gas thereof, or O _{2 or} a rare gas (He) , Ar, Xe).
The transmittance adjusting layer is preferably a film that functions as an etching stopper when etching the phase adjusting layer. The etching stopper referred to here is a film made of a material having a function of inhibiting the progress of etching of the phase adjustment layer, a function of facilitating the detection of the end point of the etching of the phase shifter film, or a material having both functions. Film.
When the transmittance adjusting layer is a film made of a material having a function of preventing the progress of etching of the phase adjusting layer as in the former, the transmittance adjusting layer has resistance to a fluorine-based gas and the fluorine It is necessary to form a film that can be etched using a gas different from the system gas.
As the gas different from the fluorine-based gas, it is preferable to use a chlorine-based gas from the viewpoint that damage to the transparent substrate can be reduced. Examples of the chlorine-based gas include Cl ₂ , BCl ₃ , HCl, a mixed gas thereof, or a gas containing a rare gas (He, Ar, Xe) as an additional gas. It should be noted that a gas containing both fluorine and a gas other than fluorine can be used at the same time, but in that case, the one in which the ratio of the excited species in the active species in the plasma is large is predominant. Defined as chlorine-based gas when there are many chlorine-excited species. In the case where fluorine and other halogen elements are contained in the single gas composition (for example, ClF ₃ or the like), a fluorine-based gas is used.
In addition, it is preferable that the etching selectivity of the transmittance adjusting layer to the transparent substrate is 5 or more in order to enable substantial CD control by etching the phase adjusting layer. That is, by increasing the etching rate of the lower layer, the over-etching time can be shortened, and thus the influence of the etching of the lower layer on the phase adjustment layer can be suppressed as much as possible.
As a material that can have an etching selectivity to a transparent substrate of 5 or more when performing dry etching using a chlorine-based gas, the material of the lower layer includes Al, Ga, Hf, Ti, V, and Zr. Consisting of a single metal selected from the first group or a material containing two or more of these metals (first material), or the material of the lower layer is Cr, Ge, Pd, Si, Ta, Nb, Sb A material (second material) obtained by adding at least one kind selected from the first group to a kind of metal selected from the second group consisting of Pt, Au, Po, Mo, and W, or the lower layer Is a material in which nitrogen and / or carbon is added to the metal simple substance, the first material, or the second material.
In particular, with respect to chlorine gas, Zr, Hf, TaZr, TaHf, and HfSi are preferable because the etching selectivity is 5 or more, so that the over-etching time can be reduced.
[0010]
Further, according to the present invention, a so-called tritone type in which pattern transfer with high precision can be performed by forming a light shielding layer in a desired region except for the vicinity of a boundary between the halftone phase shifter portion and the light transmitting portion. Can be obtained. More specifically, in the halftone phase shifter portion of the halftone type phase shift mask, a strong light intensity region (side lobe image) is generated around the halftone phase shifter portion (FIG. 4), and the resist on the transfer target substrate is exposed. May be lost. The resulting reduction in the thickness of the resist on the transfer-receiving substrate leads to a deterioration in the precision of the formed pattern. In particular, in recent years, the transmittance of the halftone phase shifter tends to increase in order to sufficiently obtain the phase shift effect. In this case, the side lobe image is a particularly serious problem. Therefore, as shown in FIG. 5, the halftone phase shifter section 5 on the transparent substrate 2 has a desired area excluding the vicinity 5a of the boundary with the light transmitting section 7, that is, an area where the intensity of the side lobe image can be reduced. By providing the light-shielding layer 9a, it is possible to obtain a high-accuracy transfer pattern in which the phase shift effect is sufficiently obtained and the resist on the substrate to be transferred is prevented from being reduced in film thickness. This configuration is particularly effective for a halftone phase shift mask having a transmittance of 8 to 30%, preferably 9 to 25% of a halftone phase shifter film which is a high transmittance product.
Further, as shown in FIG. 5, the halftone phase shift mask preferably has a light-shielding band 9b in a non-transfer area except for the transfer area I. When the light-shielding band is exposed to a plurality of locations on the substrate using a single mask, the resist on the substrate is reduced due to the multiple exposure of the object to be transferred in the overlapping portion of the exposure area. Is to prevent the occurrence of
[0011]
In addition, as the transparent substrate in the present invention, a synthetic quartz substrate or the like can be used. In particular, when an F ₂ excimer laser is used as exposure light, an F-doped synthetic quartz substrate, a calcium fluoride substrate, or the like can be used.
[0012]
【Example】
(Example 1)
In this embodiment, a method of manufacturing a halftone phase shift mask of the present invention which is compatible with both an inspection wavelength of 257 nm and an i-line (364 nm) by ArF excimer laser exposure will be described.
Using a Ta-Hf alloy target, a film of Ta-Hf is formed to a thickness of 65 Å on a synthetic quartz substrate using Ar as a sputtering gas. Next, using a Si target, Ar, O ₂ , and N ₂ were used as sputtering gases, and the gas flow rate was adjusted so that the refractive index n = 2.1 and the extinction coefficient k = 0.12 at a wavelength of 193 nm. An SiON film is formed with a thickness of 840 angstroms to obtain a phase shifter film.
FIG. 1 shows transmission / reflection spectra of the phase shifter film formed by the above film forming method. The wavelength satisfying Equation 1 was set to λ = 310 nm. The light reflectances at the wavelengths of 257 nm and 364 nm were 12.0% and 23.6%, respectively, which were in the range that could be inspected for both inspection wavelengths. The light transmittance of the ArF excimer laser at a wavelength of 193 nm was 15.2%.
Next, as shown in FIG. 6A, on a transparent substrate 2 made of a synthetic quartz substrate, a transmittance adjustment layer 3 made of Ta-Hf and a phase adjustment layer 4 made of SiON are obtained. A light-shielding band film 9 mainly composed of chromium and an electron beam drawing resist 10 are sequentially laminated on the phase shifter film 5 (FIG. 6 (2)). Then, after a pattern is drawn on the resist 10 by an electron beam, the resist pattern 10 'is formed by immersing in a developer and baking (FIG. 6 (3)). Subsequently, using the resist pattern 10 'as a mask, a pattern of the light-shielding band film 9 is formed by dry etching with Cl ₂ + O ₂ gas or the like (FIG. 6D). Further, the gas is changed, and a pattern of the phase shifter film is formed using the light-shielding band film as a mask (FIG. 6D). In this embodiment, the etching of the phase adjustment layer 4 was performed with CF ₄ + O ₂ , and subsequently, the etching of the transmittance adjustment layer 3 was performed with Cl ₂ gas. The end point of the etching was detected by a reflection optical system, and the end point of each layer was determined by the inflection point of the reflected light intensity profile. When the cross-sectional shape of the patterned phase shifter film was observed, a vertical cross-section was observed.
Next, the resist on the formed pattern is peeled off, and the resist is applied again on the entire surface. Then, through a drawing / developing process, the light-shielding band pattern 9a and the light transmitting portions 7 of the halftone phase shifter portion 5 are formed around the mask pattern. A resist pattern (not shown) is formed such that the light-shielding layer 9a is formed in a desired region except for the vicinity of the boundary with (FIG. 5). Then, Cr other than the light shielding band pattern 9b and the light shielding layer 9a is removed by wet etching or dry etching to obtain a halftone type phase shift mask (see FIG. 5). When the phase difference between the light transmitting portion and the halftone phase shifter portion of the mask was measured using a phase difference meter, it was 180 ° at the exposure wavelength.
The halftone phase shift mask obtained in Example 1 was subjected to defect / contamination inspection and pattern appearance inspection (Starlight, Terascan, etc.) at the light source wavelengths of 257 nm and 364 nm, and all showed good measurement sensitivity and measurement reproducibility. was gotten.
[0013]
(Example 2)
In this embodiment, of the halftone phase shift mask according to the present invention, illustrating a method for manufacturing a mask corresponding to the F ₂ excimer laser exposure.
Using a Ta-Hf alloy target, a film of Ta-Hf is formed to a thickness of 70 Å on a synthetic quartz substrate using Ar as a sputtering gas. Next, using a Si target, Ar, O ₂ , and N ₂ were used as sputtering gases, and the gas flow rate was adjusted so that the refractive index n = 2.1 and the extinction coefficient k = 0.25 at a wavelength of 157 nm. An SiON film is formed with a thickness of 780 Å to obtain a phase shifter film.
FIG. 2 shows transmission / reflection spectra of the phase shifter film formed by the above film forming method. The wavelength satisfying Equation 1 was set to λ = 260 nm. The light reflectances at the wavelengths of 257 nm and 364 nm were 26.7% and 15.7%, respectively, which were in the range that could be inspected for both inspection wavelengths.
Further, the light transmittance at a wavelength of 157.6nm of _{F 2} excimer laser was 6.1%.
Thereafter, a mask pattern and a light-shielding band are formed in the same manner as in the first embodiment to obtain a halftone phase shift mask. When the phase difference between the light transmitting portion and the halftone phase shifter portion of the mask was measured using a phase difference meter, it was 180 ° at the exposure wavelength.
The halftone phase shift mask obtained in Example 2 was subjected to defect / contamination inspection and pattern appearance inspection (Starlight, Terascan, etc.) at light source wavelengths of 257 nm and 364 nm. was gotten.
[0014]
(Comparative example)
On the other hand, the transmittance adjusting layer has a thickness of 100 angstroms of the Ta-Hf film, and the phase adjusting layer has a thickness of 1000 angstroms of the SiON film having a refractive index n = 1.9 and an extinction coefficient k = 0.03 at a wavelength of 193 nm. FIG. 3 shows the transmission / reflection spectrum of the shifter film. The wavelength satisfying Expression 1 was set to λ = 364 nm. The light reflectance at wavelengths of 257 nm and 364 nm is 2.3% and 35.2%, respectively, and the reflectance at 257 nm is very small. The light transmittance of the phase shifter film at a wavelength of 193 nm of an ArF excimer laser was 15.2%. Further, for a halftone phase shift mask obtained by patterning the phase shifter film by the same process as in Example 1, the phase difference between the light transmitting portion and the halftone phase shifter portion of the mask is measured by a phase difference meter. As a result, it was 180 ° at a wavelength of 193 nm of the ArF excimer laser.
With respect to the obtained halftone phase shift mask, a defect / contamination inspection and a pattern appearance inspection (Starlight, Terascan, etc.) were performed a plurality of times at light source wavelengths of 257 nm and 364 nm, and good inspection sensitivity and measurement reproducibility were obtained at 364 nm. Was done. In the pattern appearance inspection at 257 nm, the pattern could not be imaged because the reflection contrast with the light transmitting portion was insufficient. In the defect / foreign matter inspection at 257 nm, the reproducibility of the particle size distribution was insufficient.
[0015]
【The invention's effect】
According to the present invention, in inspection using reflection, a halftone phase shift mask blank and a halftone type phase shift that can respond to two different inspection wavelengths and obtain sufficient inspection accuracy even when using any one of the inspection wavelengths A mask can be obtained.
Further, according to the present invention, it is possible to obtain a halftone phase shift mask blank and a halftone type phase shift mask which can obtain sufficient inspection accuracy with the light sources of the inspection apparatus in both the i-line wavelength and the DUV region.
[Brief description of the drawings]
FIG. 1 is a diagram showing transmission / reflection spectra of a halftone type phase shift mask blank prepared in Example 1.
FIG. 2 is a diagram showing transmission / reflection spectra of a halftone type phase shift mask blank prepared in Example 2.
FIG. 3 is a diagram showing a transmission / reflection spectrum of a halftone type phase shift mask blank prepared in Comparative Example 1.
FIG. 4 is a diagram for explaining a problem of a side lobe image.
FIG. 5 is a schematic diagram illustrating one embodiment of a halftone phase shift mask.
FIG. 6 is a manufacturing process diagram of a halftone type phase shift mask blank and a halftone type phase shift mask according to an embodiment of the present invention.
FIG. 7 is a schematic cross-sectional view showing one embodiment of a halftone type phase shift mask.
[Explanation of symbols]
Reference Signs List 1 halftone type phase shift mask blank 1 'halftone type phase shift mask 2 transparent substrate 3 transmittance adjusting layer 4 phase adjusting layer 5 halftone phase shifter film (halftone phase shifter part)
7 light transmitting part 8 halftone phase shifter part 9a light shielding layer 9b light shielding band

Claims (9)

On a transparent substrate, a light transmitting portion that transmits exposure light, and a phase shifter portion that transmits a part of the exposure light and simultaneously shifts the phase of the transmitted light by a predetermined amount, the light transmitting portion and the phase shifter portion By designing the optical characteristics so that the lights transmitted through each other in the vicinity of the boundary of each other cancel each other, the contrast of the boundary of the exposure pattern transferred to the surface of the exposure object can be maintained and improved satisfactorily. A halftone type phase shift mask blank used for manufacturing a tone type phase shift mask, in a halftone type phase shift mask blank having a phase shifter film for forming the phase shifter portion on a transparent substrate,
The phase shifter film is a multilayer film in which at least two or more layers including an upper layer formed on the most surface side and a lower layer formed thereunder are laminated, and the halftone type phase shift mask blank is used. The refractive index of the upper layer film with respect to the wavelength of the inspection light used for inspection of the halftone phase shift mask manufactured by the above is smaller than the refractive index of the lower layer film, and the surface reflectance of the phase shifter film with respect to the inspection light is smaller than that of the lower layer film. A halftone phase shift mask blank characterized in that the thickness of the upper layer is adjusted so that a desired reflectance is obtained for two or more different inspection wavelengths. The halftone phase shift mask according to claim 1, wherein the exposure light has a wavelength selected from a wavelength of 140 nm to 200 nm, and the two or more different inspection wavelengths are selected from a wavelength of 240 to 370 nm. blank. The halftone phase shift according to claim 2, wherein the thickness of the upper layer is adjusted so that the surface reflectance of the phase shifter film is maximized at a wavelength selected from a wavelength of 220 nm to 340 nm. Mask blank. Exposure light, F ₂ halftone type phase shift mask blank according to claim 1, characterized in that an excimer laser. 4. The halftone phase shift mask according to claim 1, wherein the exposure light is an ArF excimer laser, and the transmittance of the phase shifter film is adjusted to 8 to 30%. blank. The phase shifter film is formed of a two-layer film in which the phase angle of the exposure light is changed by approximately 180 ° and the transmittance for the exposure light is adjusted to 3 to 40%. The halftone type according to any one of claims 1 to 5, wherein the halftone type is a phase adjustment layer having a function of adjusting an angle, and the lower layer is a transmittance adjustment layer mainly having a function of reducing transmittance. Phase shift mask blank. 7. A halftone type phase shift mask blank according to claim 1, wherein a light transmitting part and a halftone phase shifter part are formed by patterning the phase shifter film. Shift mask. The halftone type phase shift mask according to claim 7, wherein a light shielding layer is formed in a desired region except for a vicinity of a boundary between the halftone phase shifter portion and the light transmitting portion. A method for manufacturing a halftone phase shift mask, comprising a step of performing a pattern appearance inspection of the halftone phase shift mask according to claim 7.

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