JP4766507B2 - Phase shift mask blank and method of manufacturing phase shift mask - Google Patents

Description

  The present invention relates to a phase shift mask blank and a phase shift mask, and in particular, is an attenuation type (halftone type) that attenuates light having an exposure wavelength, and is particularly suitable for a short wavelength having an exposure wavelength of 200 nm or less. The present invention relates to a mask blank, a method of manufacturing a phase shift mask, and the like.

Formation of a transfer pattern in the manufacture of a semiconductor device is performed by irradiating a pattern to be transferred with an exposure light on a transfer substrate via a photomask (including a reticle) that is a pattern transfer master.
As such a photomask, a light-shielding film pattern formed on a transparent substrate has been conventionally used. The material of the light-shielding film is a chromium-based material (chromium alone or chromium, nitrogen, oxygen, carbon, etc. In general, or a laminated film of these material films) is generally used.
Furthermore, in recent years, a phase shift mask has been developed as one that can improve the resolution of a transfer pattern. Various types of phase shift masks (Levenson type, auxiliary pattern type, self-aligned type, etc.) are known, and one of them is suitable for transferring high resolution patterns such as holes and dots. Halftone phase shift masks are known. This halftone phase shift mask has a predetermined phase shift amount (usually about 180 °) and a translucent film pattern having a predetermined transmittance (usually about 3 to 20%) on a transparent substrate. There are some in which the light semi-transmissive film is formed in a single layer or in a multilayer.
As such a halftone phase shift mask, for example, in Patent Document 1, a film (MoSiON film) having molybdenum, silicon, oxygen, and nitrogen as constituent elements was first developed as a single-layer light semi-transmissive film. Then, the background of the development of a film (MoSiN film) containing molybdenum, silicon, and nitrogen as constituent elements in the course of shortening the exposure wavelength is described. In the MoSiON film, the target of Mo: Si = 1: 2 (stoichiometric ratio) is used, and the optical characteristics are adjusted by the amount of O and N in the sputtering atmosphere (in the film), and in particular, the transmission by the amount of O Since the rate is adjusted, O is basically relatively contained in the film. On the other hand, in the MoSiN film, a target of Mo: Si = 1: 4 (silicon rich) is used, and the silicon amount in the film is controlled to be silicon rich by the silicon rich target, and also depending on the amount of N in the sputtering atmosphere. The amount of N in the film is controlled to adjust the optical characteristics (transmittance, refractive index (film thickness / phase difference)). As described above, the two are films having different main elements (methods) for transmittance control and different films having different main elements (methods) for optical design, and the MoSiN film is a film developed starting from the MoSiON film. However, it is not a film developed by adjusting the composition of the MoSiON film. The MoSiN film has many advantages over the MoSiON film (for example, there is no problem of the occurrence of foreign matter defects due to abnormal discharge due to O in the sputtering atmosphere, and the film contains O. It is not known (as a result, the refractive index becomes large), so that the film thickness can be reduced). Such a MoSiN film is excellent in characteristics such as acid resistance, light resistance, etching selectivity, low aspect ratio (small film thickness), etc. in addition to being able to control a predetermined phase shift amount and transmittance with a single layer. can get.
Japanese Patent No. 2966369 [0010], [0063], [0071] columns, etc.

By the way, when pattern transfer is performed using a photomask (reticle), the photomask is irradiated with laser light, so that residual materials on the photomask and substances contained in the atmosphere around the photomask are exposed by laser irradiation. There is a problem that the reaction is excited and promoted, and the precipitate of the reaction product becomes a foreign substance and adheres to the photomask. As one of such precipitates, it has been confirmed that there are crystalline foreign matters such as ammonium sulfate.
A photomask is manufactured through a cleaning process at the time of manufacturing the mask, and after the mask is manufactured, the mask is repeatedly cleaned and used. In these cleaning processes, cleaning using a sulfuric acid-based cleaning agent is generally performed. Therefore, it is considered that sulfuric acid or sulfate ions derived from the sulfuric acid-based detergent used in these cleaning processes often remain in the photomask after cleaning. Therefore, ammonium ions generated due to this sulfate ion and some other cause It is considered that the reaction with ions is promoted by laser irradiation.
The problem of precipitation of crystalline foreign matters on the mask when such a mask is used becomes particularly problematic with a short wavelength mask having an exposure wavelength of 200 nm or less. This is because it is considered that the precipitation of crystalline foreign substances is excited and promoted energetically (in terms of wavelength) at a shorter wavelength of 200 nm or less, and the pattern is used for a short wavelength mask having an exposure wavelength of 200 nm or less. This is because, as a result of further miniaturization, a crystalline foreign material having a smaller size becomes a problem (a crystalline foreign material having a size that has not been a problem until now).
Therefore, for the purpose of surely removing the sulfuric acid-based cleaning agent used in the mask cleaning process and reducing the precipitation of the crystalline foreign matter described above, hot water cleaning at 50 to 60 ° C. is performed after the sulfuric acid cleaning, and the exposure wavelength is The necessity is especially high in the mask for short wavelengths of 200 nm or less.
However, the MoSiN film disclosed in Patent Document 1 cannot be said to have sufficient resistance to hot water at 50 to 60 ° C. for the reason described later, and optical due to damage (erosion in the thickness direction) of the thin film surface. There are concerns about changes in transfer pattern dimensions due to changes in characteristics (transmittance, phase difference) and damage to the thin film pattern cross section (erosion in the width direction).
The present invention has been made in view of the above-described background, and suppresses film damage with respect to hot water cleaning performed in a mask cleaning process, has a small change in optical characteristics, and a phase shift with a small change in transfer pattern dimension. It aims at providing the manufacturing method of a mask blank and a phase shift mask.

In response to the problem of improving the warm water resistance of the above-described MoSiN film (especially, a short wavelength mask having an exposure wavelength of 200 nm or less), the present inventors aim to achieve resistance to high-temperature water at 80 ° C. in the MoSiN film. Improved high temperature water resistance by changing the baking temperature after film (improving film quality), improving high temperature water resistance by changing the ratio of Mo and Si in the film, and improving high temperature water resistance by changing the ratio of N in the film I tried to improve. However, satisfactory results were not obtained for the goal of achieving resistance to high temperature water at 80 ° C.
Surprisingly, it was found that putting a small amount of O (preferably in the form of Si—Ox bonds) in the MoSiN film is most effective in achieving the problem of achieving resistance to high-temperature water at 80 ° C.
While the present invention basically maintains various characteristics of the MoSiN film, various characteristics of the MoSiN film (optical characteristics (transmittance, refractive index (film thickness / phase difference), acid resistance, light resistance, etching selectivity) In the category in which the low aspect ratio (small film thickness) is not basically changed, in other words, within the range in which the various characteristics of the MoSiN film can be fully utilized while maintaining the various characteristics of the MoSiN film] in the MoSiN film By adding a small amount of O, resistance to high-temperature water at 80 ° C. is realized.
In the present invention, since a small amount of O is added to the MoSiN film, it is labeled as a MoSiON film. However, in the present invention, O is not included for the purpose of controlling the transmittance as in the case of a known MoSiON film. Basic design (main design) of optical characteristics (transmittance, refractive index (film thickness / phase difference)) is made mainly with three elements of MoSiN excluding.
Thus, the present invention has not been developed starting from a known MoSiON film, and the present invention is not an invention made on the extension of composition adjustment of a known MoSiON film. In addition, the MoSiON film of the present invention is a film conceptually (technological and physical) that is (rather) close to a MoSiN film, unlike known MoSiON.
Furthermore, the development of semi-transparent films begins with whether or not basic characteristics of optical characteristics (transmittance, refractive index (film thickness / phase difference)) are satisfied, and then various characteristics such as acid resistance and light resistance are improved. However, the optical transflective film, which has been in the development stage, is focused on only one characteristic of high-temperature water resistance, and the basic optical characteristics and other characteristics can be maintained. Therefore, development from the viewpoint of improving only the high temperature water resistance has not been attempted yet.

The reason why the MoSiN film is not sufficiently resistant to hot water at 50 to 60 ° C. is that the Si—N bond in the MoSiN film is attacked by OH ⁻ or H ^{+ in} hot water at 50 to 60 ° C. This is considered to be due to dissolution in warm water of 50 to 60 ° C. In the present invention, although a relatively large amount of Si—N is contained in the film, the Si—N bond is unexpectedly converted into high-temperature water at 80 ° C. by containing a relatively small amount of Si—Ox bonds in the film. Even when subjected to the attack of OH ⁻ or H ⁺ and the influence of high temperature, it is considered that dissolution into high temperature water at 80 ° C. can be substantially avoided.

The present invention has the following configuration.
(Configuration 1) A phase shift mask blank in which a light translucent film having a predetermined transmittance with respect to an exposure wavelength and optically designed with nitrogen, metal, and silicon as main components is formed on a transparent substrate. And
Oxygen is contained in the light translucent film containing nitrogen, metal, and silicon as main components within a range in which the optical characteristics that are optically designed with nitrogen, metal, and silicon as main components can be maintained, and the nitrogen, A phase shift mask blank characterized by improving the high-temperature water resistance of a light semi-transmissive film containing metal and silicon as main components.
(Structure 2) The phase shift mask blank according to Structure 1, wherein the content of oxygen in the light-semitransmissive film is 2 atomic% or more and less than 20 atomic%.
(Configuration 3) The light translucent film contains oxygen uniformly in the film thickness direction of the film, and has a film thickness direction excluding the surface layer of the light translucent film and the interface adjacent to the transparent substrate. The phase shift mask blank according to Configuration 1 or 2, wherein the variation in oxygen concentration distribution is within ± 1.5 atomic%.
(Structure 4) The phase shift mask blank according to any one of Structures 1 to 3, wherein the light-semitransmissive film contains Si—Ox in which silicon and oxygen are combined.
(Structure 5) The phase shift mask blank according to Structure 4, wherein the Si-Ox is uniformly contained in the depth direction of the light semitransmissive film.
(Structure 6) The phase according to Structure 4 or 5, wherein the content of Si-Ox is 1 to 15 atomic% of silicon (Si) contained in the light-semitransmissive film. Shift mask blank.
(Structure 7) The phase shift mask blank according to any one of Structures 1 to 6, wherein the exposure wavelength is 200 nm or less.
(Configuration 8) Manufacturing of a phase shift mask characterized in that the light semi-transmissive film of the phase shift mask blank according to any one of configurations 1 to 7 is patterned to form a light semi-transmissive portion on a transparent substrate. Method.
(Structure 9) A method of manufacturing a phase shift mask according to Structure 8, wherein the light semi-transmissive portion formed on the transparent substrate is washed with warm water.

ADVANTAGE OF THE INVENTION According to this invention, the tolerance with respect to 80 degreeC high temperature water is realizable regarding the light semipermeable membrane by which an optical design is made by making nitrogen, a metal, and a silicon into a main component.
In addition, since it is a film resistant to high temperature water at 80 ° C. and strong against hot water cleaning, film damage is suppressed with respect to hot water cleaning performed in the mask cleaning process, there is little change in optical characteristics, and A phase shift mask blank and a phase shift mask with little change can be realized. As a result, the mask life for repeated hot water cleaning (the number of times the mask is repeatedly used for cleaning) is greatly increased as a phase shift mask blank and phase shift mask that are used by cleaning with warm water, particularly cleaning with high temperature water of 80 ° C or higher. Can be extended.
Furthermore, with respect to 50 to 60 ° C. warm water cleaning after sulfuric acid cleaning performed for the purpose of surely removing the sulfuric acid-based cleaning agent used in the mask cleaning process and reducing the precipitation of the crystalline foreign matter described above, a higher temperature, Longer warm water cleaning is possible, and as a result, the removal level of the sulfuric acid-based cleaning agent is improved, so that the cleaning frequency when using the mask can be reduced (the mask use cycle can be lengthened).
As described above, the problem of precipitation of crystalline foreign matters on the mask when the mask is used becomes a problem particularly in the case of a short wavelength mask having an exposure wavelength of 200 nm or less, and the present invention has a short exposure wavelength of 200 nm or less. Particularly useful as a phase shift mask blank and a phase shift mask for phase shift mask blanks and phase shift masks for wavelength, which are used by performing cleaning with warm water, particularly cleaning with high temperature water of 80 ° C. or higher. High (Configuration 7).

Hereinafter, the present invention will be described in detail.
While the present invention basically maintains various characteristics of the MoSiN film, various characteristics of the MoSiN film (optical characteristics (transmittance, refractive index (film thickness / phase difference), acid resistance, light resistance, etching selectivity) In the category in which the low aspect ratio (small film thickness) is not basically changed, in other words, within the range in which the various characteristics of the MoSiN film can be fully utilized while maintaining the various characteristics of the MoSiN film] in the MoSiN film By adding a small amount of O (preferably in the form of Si—Ox bond), resistance to high-temperature water at 80 ° C. is realized (Configuration 1).
In the present invention, it is important to satisfy both the requirements for maintaining the various characteristics of the MoSiN film and the requirements for realizing resistance to high-temperature water at 80 ° C.
For this purpose, O (preferably Si—Ox bond) is formed in the MoSiN film in cooperation with the control by the film forming conditions (film forming apparatus, target composition, gas pressure (collision frequency), atmosphere temperature during film forming, etc.). It is important to include an amount that satisfies both of the above requirements. Specifically, in cooperation with control by the film formation conditions (film formation apparatus, target composition, gas pressure (collision frequency), atmosphere temperature during film formation), the amount of O in the film is N ₂ (nitrogen ) and _{O 2} (oxygen) gas mixing ratio, and is controllable by the flow rate of _{N 2} and _{O 2} gas, also the _{N 2} and _{O 2,} NO (nitrogen monoxide) and _N 2 O (nitrous oxide Control is possible even if it is replaced with (nitrogen).

In the present invention, the content of oxygen in the light-semitransmissive film is preferably 2 atomic% or more and less than 20 atomic% (Configuration 2).
From FIG. 1 obtained by accelerated hot water resistance evaluation (80 ° C., hot water washing for 60 minutes) for the films obtained in the examples, the requirement for realizing resistance to high temperature water at 80 ° C., ie, phase difference From the requirement that the change amount ΔΦ is not less than “−10.0 °” and the change amount ΔT in transmittance is not more than “+ 1.0% T”, the lower limit of O ₂ is 2 atomic%.
Similarly, with respect to the films obtained in the examples, tests conducted from the viewpoint of satisfying the requirements of basically maintaining the various characteristics of the MoSiN film, that is, the etching time increases as the film thickness increases as the O content increases. In FIG. 2 showing the test results of amounts (one of the tests that can determine whether or not the various characteristics of the MoSiN film can be maintained), substantially no O is produced without introducing O ₂ gas into the sputtering atmosphere. When the etching time of the MoSiN film is 1.0, the etching time ratio of the MoSiN film produced by introducing O ₂ gas into the sputtering atmosphere is kept within a range not exceeding 1.1 (in the sputtering atmosphere). from O ₂ suppress etching time increment for MoSiN film does not contain substantially O produced without introducing a gas within 10%) that requirement, O ₂ The upper limit of is less than 20 atomic%. Preferably, when the etching time of a MoSiN film that is substantially free of O produced without introducing O ₂ gas into the sputtering atmosphere is 1.0, O ₂ gas is introduced into the sputtering atmosphere for the etching time. It is desirable to keep the etching time ratio of the manufactured MoSiN film within a range not exceeding 1.05, and the upper limit of O ₂ is desirably less than 15 atomic%. From the viewpoint of satisfying the requirement that the various characteristics of the MoSiN film are basically maintained at substantially the same level, the etching of the MoSiN film substantially free of O produced without introducing O ₂ gas into the sputtering atmosphere. When the time is 1.0, the etching time ratio of the MoSiN film produced by introducing O ₂ gas into the sputtering atmosphere is within the range of 1.0, and the upper limit of O ₂ is less than 10 atomic%. It is more desirable to do.

In the present invention, the light semi-transmissive film contains oxygen uniformly in the film thickness direction of the film, and the oxygen in the film thickness direction excluding the surface layer of the light semi-transmissive film and the interface adjacent to the transparent substrate. It is preferable that the variation of the concentration distribution is within ± 1.5 atomic% (Configuration 3).
This is because oxygen is uniformly contained in the film thickness direction of the light-semitransmissive film, so that damage (erosion in the width direction) to the thin film pattern cross section with high-temperature water at 80 ° C. is uniform over the entire thin film pattern cross section. This is to prevent it. In addition, the variation of the oxygen concentration distribution in the film thickness direction excluding the surface layer of the light translucent film and the interface adjacent to the transparent substrate is within ± 1.5 atomic%, thereby causing damage to the thin film pattern cross section against high temperature water at 80 ° C. This is because (erosion in the width direction) is more strictly and uniformly prevented over the entire cross-section of the thin film pattern, thereby strictly preventing changes in pattern dimensions.
Note that a film that satisfies the requirements of the above-described configuration 3 can be realized by a configuration in which a single-wafer apparatus is used and a film is formed by rotating a substrate. On the other hand, when an inline type apparatus is used or an apparatus using a method that does not rotate the substrate, a film that satisfies the requirements of the above configuration 3 cannot be realized.

In the present invention, the light-semitransmissive film preferably contains Si—Ox in which silicon and oxygen are bonded (Configuration 4).
From the results of analysis by an X-ray photoelectron spectroscopy (ESCA, XPS) apparatus in an example to be described later, in order to realize resistance to high temperature water at 80 ° C., O is contained in the MoSiN film as much as possible in the form of Si—Ox bonds. This is because it is considered to be preferable (estimated).
In the present invention, the Si—Ox is preferably contained uniformly in the depth direction of the light semitransmissive film (Configuration 5).
This effectively prevents damage (erosion in the width direction) to the thin film pattern cross section with high temperature water at 80 ° C. over the entire surface of the thin film pattern cross section, thereby preventing changes in the transfer pattern dimension more effectively. It is to do.
In the present invention, the content of Si—Ox is preferably 1 to 15 atomic% of silicon (Si) contained in the light semi-transmissive film (Configuration 6). The lower limit of 1 atomic% and the upper limit of 15 atomic% are contained in the light semi-transmissive film when O is contained in the lower limit of 2 atomic% from the XPS analysis peak separation result of the light semi-transmissive film containing O. When 1 atomic% of Si is contained in an upper limit of 20 atomic%, when 15 atomic% of Si contained in the light-semitransmissive film is bonded to O This is because it is estimated.
It can be estimated by using the Si2p peak obtained by XPS analysis how much Si contained in the light semi-transmissive film is bonded to O. In XPS, the Si 2p peak of Si bonded to O or N appears in the vicinity of an energy value of 101.3 eV. In this peak, Si—Ox, Si—Ny and their unstable states, Si—Ox2Ny2 and their unstable states are mixed. When there are many bonds with O, the peak shifts to the high energy side, and when there are many bonds with N, the peak shifts to the low energy side.
XPS analysis was performed on the surface layer of the light translucent film of Example 1 to be described later, and the obtained Si2p peak was separated (divided into two parts). As a result, Si-Ox A possible peak was obtained. This peak cannot be determined to be the peak of SiO ₂ formed by stoichiometrically combining Si and O, but X of Si—Ox is considered to be close to 2. When separating the Si2p peak obtained by XPS analysis of the light translucent films (Comparative Examples 1 to 3) with different O contents, the energy value of one peak was fixed at 103.20 eV. When peak separation was performed so that the half-value widths of the two peaks were equal, the peak at 103.20 eV as an index of the Si—Ox bond increased as the oxygen content increased. On the other hand, the peak of the other peak was predicted to shift to the higher energy side as the oxygen content increased, and the contribution of Si—O bonds increased. The peak on the low energy side includes the unstable bond of Si and O and the case where N and O are simultaneously bonded to Si. Therefore, only the 103.20 eV peak does not indicate the Si—O bond. Since it is considered that the Si—Ox bond greatly contributes to the high temperature water resistance, the 103.20 eV peak may be noted.
From the above results, FIG. 3 shows the relationship between the area ratio of the 103.20 eV peak to the Si2p peak and the oxygen content of the light semitransmissive film. When the lower limit of O is 2 atomic%, the area ratio of the 103.20 eV peak is approximately 1%, and it is estimated that 1% of Si contained is bonded to O. Similarly, the upper limit of O is 20 atomic%. In some cases, it is estimated that 15% of the contained Si is bonded to O.

Example 1
(Production of phase shift mask blank)
Using the sputtering apparatus (sheet format, substrate rotation, oblique sputtering) shown in FIG. 8, Mo: Si = 10: 90 as a sputtering target, argon, helium and nitrogen as sputtering gases (gas flow rate: Ar: 10 sccm, He: 80 sccm, N ₂ : 86 sccm, O ₂ : 4 sccm), film-forming pressure: 0.4 Pa, atmosphere temperature during film-forming: 100 ° C.) and oxynitrided on the transparent substrate by reactive sputtering (DC sputtering) A light translucent film (film thickness: 74 nm) of molybdenum and silicon (MoSiON) was formed to obtain a phase shift mask blank.
The obtained phase shift mask blank had an transmittance of 7.2% and a phase angle of 179.8 ° in an ArF excimer laser (wavelength: 193 nm).

In addition, the distribution of atoms from the film surface of molybdenum oxynitride and silicon (MoSiON) formed on a transparent substrate in the depth direction (film thickness direction) is measured by AES (Auger Electron Spectroscopy). analyzed. The analysis result of AES is shown in FIG.
From FIG. 4, the light semi-transmissive film formed on the transparent substrate is Mo: 7 atomic%, Si: 25 atomic%, O: 10 atomic%, N: 58 atomic%, and the surface layer of the light semi-transmissive film and It can be seen that oxygen is uniformly contained in the film thickness direction except for the interface (approximately 8 nm) adjacent to the transparent substrate. The variation in the oxygen concentration distribution in the film thickness direction was O: 10 atomic% ± 1.3 atomic%.

(Production of phase shift mask)
Next, a resist film was formed on the light translucent film made of oxynitrided molybdenum and silicon (MoSiON) of the phase shift mask blank, and a resist pattern was formed by pattern exposure and development.
Next, the exposed portion of the thin film made of oxynitrided molybdenum and silicon was removed by dry etching (SF ₆ + He gas) to obtain a thin film pattern (light semi-transmissive portion) made of oxynitrided molybdenum and silicon. .
After the resist film was peeled off, it was immersed in 98% sulfuric acid (H ₂ SO ₄ ) at 100 ° C. for 15 minutes and washed with sulfuric acid, and then washed with warm water at 80 ° C. for 60 minutes to obtain a phase shift mask for ArF excimer laser exposure.
When the transmittance and phase difference of the obtained phase shift mask were measured and compared with the transmittance and phase difference in the phase shift mask blank, the transmittance was + 0.5% and the phase difference was −4.8 °. The amount of change in both was small. Further, the cross section of the pattern (light semi-transmissive portion) was good without any damage caused by hot water.

  In the present embodiment, the sputtering target 2 and the substrate 6 are configured such that the target and the substrate are arranged so that the surfaces of the substrate and the target facing each other have a predetermined angle. Note that the offset distance between the sputtering target and the substrate, the target-substrate vertical distance (T / S), and the target tilt angle are the film thickness of the light semi-transmissive film, optical characteristics (transmittance, phase difference), etc. within the substrate plane. Was adjusted as appropriate so as to be uniform.

(Comparative Example 1)
Using the sputtering apparatus of FIG. 8, as a sputtering target, Mo: Si = 10: 90, sputtering gas with argon, helium and nitrogen (gas flow rate: Ar: 10 sccm, He: 80 sccm, N ₂ : 80 sccm), film forming pressure : 0.4 Pa, atmospheric temperature during film formation: normal temperature 22 ° C., light translucent film (film thickness: 69 nm) of molybdenum and silicon (MoSiN) nitrided on a transparent substrate by reactive sputtering (DC sputtering) ) To obtain a phase shift mask blank.
The obtained phase shift mask blank had an transmittance of 5.4% and a phase angle of 180.2 ° in an ArF excimer laser (wavelength 193 nm).
Further, the distribution of atoms in the depth direction (thickness direction) from the film surface of nitrided molybdenum and silicon (MoSiN) substantially free of oxygen (O) formed on the transparent substrate is represented by AES (Auger Electron). The result of analysis by Spectroscopy is shown in FIG.
From FIG. 5, the light semi-transmissive film formed on the transparent substrate has Mo: 4 atomic%, Si: 29 atomic%, N, except for the surface layer of the light semi-transmissive film and the interface (approximately 10 nm) adjacent to the transparent substrate. : 66 atomic%, O: 1 atomic%. Note that it is considered that a slight amount of oxygen is contained in the region excluding the surface layer of the light semi-transmissive film and the interface adjacent to the transparent substrate due to the gas released from the substrate holder or the like (so-called outgas).

(Production of phase shift mask)
Next, a phase shift mask for ArF excimer laser exposure is prepared in the same manner as in the above-described embodiment, the transmittance and phase difference of the obtained phase shift mask are measured, and compared with the transmittance and phase difference of the phase shift mask blank. As a result, the transmittance was + 4.8% and the phase difference was −14.2 ° by washing with warm water at 80 ° C. for 60 minutes. Both of these changes were large.
In addition, about the mask obtained in Example 1 and the mask obtained in Comparative Example 1, when the number of repeated use (life) by repeated cleaning of the mask was examined, it was confirmed that the former life was about twice as long. did.

(Comparative Examples 2-3)
A film (Comparative Examples 2 and 3) produced in the same manner as in Example 1 except that the contents of oxygen and other elements were changed as shown in FIG. FIG. 7 shows the result of analyzing the film produced in Comparative Example 1 using an X-ray photoelectron spectroscopy (ESCA, XPS) apparatus capable of analyzing a surface micro-part relating to an element / functional group (that is, relating to the bonding state of the element). .
In FIG. 7, the horizontal axis of the spectrum is displayed as electron binding energy, and the vertical axis is displayed as a count value (C / S: Count / Second).
The analysis is depth direction analysis by Ar ion etching (weak etching with little influence on the bonding state change), and evaluation is made at a value at a depth of 10 nm (a value at the deepest position, about 1/3 of the film thickness). Went. The reason why the evaluation was made at a depth of 10 nm is that there is a possibility that data may be distorted due to the influence of surface oxidation or surface contamination at a position shallower than this.
As a result, as shown in FIG. 7, based on the existence of an unstable state of Si—Ox, Si—N, Si—Ox, and an unstable state of SiON (that is, chemical bond species related to Si). -A mountain-shaped signal that is expressed in an integrated manner (based on the bonding state (including oxidation state and nitriding state)) (This mountain-shaped signal is thought to be generated by overlapping various signals based on the binding energy of the 2P orbital of Si) A peak having a binding energy peak value in the range of 101.6 to 102.2 eV, and a half-value width of the peak signal in a range of about 2.0 eV or less. It can be seen that (Example 1) is preferable. On the other hand, in the films of Comparative Examples 1 to 3 exceeding the above range, the O content in the film exceeds the upper limit or lower limit of the present invention, and as a result, the above-mentioned peak signal is different (that is, related to Si). It is not preferable because it becomes a film having a different chemical bond type and bond state (including oxidation state and nitridation state).

As described above, in the present invention, both the requirement for maintaining the various characteristics of the MoSiN film and the requirement for realizing resistance to high-temperature water at 80 ° C. are important. Cooperating with the control by the film device, target composition, gas pressure (collision frequency, ambient temperature during film formation, etc.), O (preferably in the form of Si-Ox bond) in the MoSiN film meets the above requirements. It is important to include a sufficient amount.
From the above viewpoint, the target composition is preferably in the range of Mo: Si (mole% ratio) = 5: 95 to 20:80.
The gas pressure is preferably in the range of 0.01 Pa to 0.5 Pa.
Hereinafter, a DC magnetron sputtering apparatus particularly suitable for the photomask blank manufacturing method of the present invention will be described in detail.
The DC magnetron sputtering apparatus shown in FIG. 8 has a vacuum chamber 1, and a sputtering target 2 and a substrate holder 3 are arranged inside the vacuum chamber 1. The sputtering target 2 employs an oblique sputtering method in which the target surface is disposed obliquely downward. The sputtering target 2 is formed by joining a target material 4 and a backing plate 5 with an indium-based bonding agent. A full surface erosion magnetron cathode (not shown) is mounted behind the sputtering target 2. The backing plate 5 is cooled directly or indirectly by a water cooling mechanism. A magnetron cathode (not shown), the backing plate 5 and the target material 4 are electrically coupled. The exposed backing plate surfaces 5A, 5B, and 5C are roughened by using a method such as blasting (mechanically and physically roughening the surface). The target material side surface 4B is roughened using a method such as blasting. A transparent substrate 6 is mounted on the rotatable substrate holder 3.
On the inner wall of the vacuum chamber 1, a shield 20 (having a temperature controllable structure) that is a removable film adhesion prevention component is installed. The portion of the earth shield 21 in the shield 20 is electrically grounded to the target 2. The earth shield 21 is arranged above the target surface 4A (on the backing plate 5 side).
The vacuum chamber 1 is exhausted by a vacuum pump through an exhaust port 7. After reaching the degree of vacuum that does not affect the characteristics of the film formed by the atmosphere in the vacuum chamber, a mixed gas containing nitrogen is introduced from the gas inlet 8 and the entire surface erosion magnetron cathode (not shown) using the DC power source 9 is introduced. A negative voltage is applied to and sputtering is performed. The DC power source 9 has an arc detection function and can monitor the discharge state during sputtering. The pressure inside the vacuum chamber 1 is measured by a pressure gauge 10.
The transmittance of the light semi-transmissive film formed on the transparent substrate is adjusted by the type and mixing ratio of the gas introduced from the gas inlet 8.
It should be noted that in order to suppress the concentration distribution variation in the depth direction of O within ± 1.5%, it is necessary to perform film formation while rotating the transparent substrate.
In addition, the gas pressure during sputtering to form a thin film such as a light semi-transmissive film and the sputtering time directly affect the transmittance and the phase angle. It is necessary to improve the accuracy of the setting signal transmitted from. Since the gas pressure during sputtering is also affected by the exhaust conductance of the apparatus, a mechanism capable of accurately determining the opening of the exhaust valve and the position of the shield is also required.
In addition, in the film containing silicon nitride, gas such as moisture generated from the inner wall of the vacuum chamber has a great influence on the optical characteristics of the film. It is necessary to provide a mechanism that can. The degree of vacuum in the vacuum chamber is generally 2 × 10 ⁻⁵ pa or less when the film formation rate is 10 nm / min, and 1 × 10 ⁻⁵ pa or less when the film formation rate is 5 nm / min. is there.

Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to the above embodiments.
For example, in the above embodiment, molybdenum is used as the metal constituting the light translucent film, but the metal is not limited to this, and zirconium, titanium, vanadium, niobium, tantalum, tungsten, nickel, palladium, or the like can be used.
Further, although a target made of molybdenum and silicon is used as a target containing metal and silicon, the present invention is not limited to this. In the target containing metal and silicon, molybdenum has high controllability of transmittance and high target density when using a sputtering target containing metal and silicon, and reduces particles in the film. It is excellent in that it can. Titanium, vanadium, and niobium have excellent durability against alkaline solutions, but are slightly inferior to molybdenum in target density. Tantalum is superior in durability to alkaline solutions and target density, but slightly inferior to molybdenum in controllability of transmittance. Tungsten has similar properties to molybdenum, but is slightly inferior to molybdenum in the discharge characteristics during sputtering. Nickel and palladium are excellent in terms of optical properties and durability against alkaline solutions, but are somewhat difficult to dry etch. Zirconium is excellent in durability against an alkaline solution, but is inferior to molybdenum in target density, and dry etching is somewhat difficult. Taking these into account, molybdenum is currently most preferred. The nitrided molybdenum and silicon (MoSiN) thin film (light semi-transmissive film) is preferably molybdenum from the viewpoint of excellent chemical resistance such as acid resistance and alkali resistance.

In accelerative hot water evaluation is a diagram showing the O ₂ content in the semi-transmission film, a phase difference change amount .DELTA..PHI, the relationship between the change amount ΔT in transmittance. It is a diagram showing the relationship between O ₂ content in the semi-transmission film and the etching time ratio. It is a figure which shows the relationship between the area ratio of the 103.20 eV peak with respect to a Si2p peak, and the oxygen content of a light semi-transmissive film | membrane. It is a figure which shows the analysis result by AES (Auger Electron Spectroscopy) of the light semipermeable film obtained in Example 1. FIG. It is a figure which shows the analysis result by AES (Auger Electron Spectroscopy) of the light semipermeable film obtained in the comparative example 1. It is a figure which shows the composition etc. of the light semipermeable film produced in Example 1 and Comparative Examples 1-3. It is a figure which shows the analysis result by the X-ray photoelectron spectroscopy (ESCA, XPS) apparatus of the light semipermeable film obtained in Example 1 and Comparative Examples 1-3. It is a schematic diagram of the sputtering chamber in the DC magnetron sputtering apparatus used in the examples.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Sputtering target 3 Substrate holder 4 Target material 5 Backing plate 6 Transparent substrate

Claims (8)

A phase shift mask blank in which a light translucent film having a predetermined transmittance with respect to an exposure wavelength and having an optical design as a main component is formed on a transparent substrate,
The oxygen content in the light semitransmissive film is 2 atomic% or more and less than 20 atomic%,
The oxygen is uniformly contained in the film thickness direction of the light semi-transmissive film, and the variation of the oxygen concentration distribution in the film thickness direction excluding the surface layer of the light semi-transmissive film and the interface adjacent to the transparent substrate is ± 1. A phase shift mask blank characterized by being within 5 atomic% . The light semi-transmitting film, the phase shift mask blank of claim 1, wherein it contains the Si-Ox which silicon and oxygen are bonded. The phase shift mask blank according to claim 2 , wherein the Si—Ox is uniformly contained in a depth direction of the light semitransmissive film. 4. The phase shift mask blank according to claim 2 , wherein the content of Si—Ox is 1 to 15 atomic% of silicon (Si) contained in the light-semitransmissive film. . The phase shift mask blank according to any one of claims 1 to 4 , wherein the exposure wavelength is 200 nm or less.   The phase shift mask blank according to any one of claims 1 to 5, wherein the transmittance of the light semi-transmissive film with respect to the exposure wavelength is 3 to 20%. A method of manufacturing a phase shift mask, comprising: patterning the light semitransmissive film of the phase shift mask blank according to any one of claims 1 to 6 to form a light semitransmissive part on a transparent substrate. 8. The method of manufacturing a phase shift mask according to claim 7 , wherein the light semi-transmissive portion formed on the transparent substrate is washed with warm water.

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