JP2012134372A - Contamination prevention device, contamination prevention method, exposure device, and method of manufacturing patterned wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contamination prevention device and contamination prevention method capable of preventing contamination of an EUV mask conveniently, and to provide an exposure device using it, and a method of manufacturing a patterned wafer.SOLUTION: The contamination prevention device comprises a light source generating vacuum ultraviolet light having a wavelength of 166 nm or shorter, and an optical system (mirrors 104a, 104b, and the like) through which an EUV mask 108 housed in an EUV exposure device 101 is irradiated with vacuum ultraviolet light from the light source. As the light source may be used a laser oscillator 110 emitting fluorine molecule laser, an argon dimer, a krypton dimer, or a VUV-ASE generator 210 emitting amplified spontaneous emission light.

Description

  The present invention relates to a contamination prevention apparatus, a contamination prevention method, an exposure apparatus, and a method for manufacturing a patterned wafer. More particularly, the present invention relates to a contamination prevention apparatus, a pollution prevention method, and a method for preventing contamination of an EUV (Extremely UltraViolet) mask. The present invention relates to an exposure apparatus used and a method for producing a patterned wafer.

  With regard to lithography technology for miniaturization of semiconductors, ArF lithography using an ArF excimer laser with an exposure wavelength of 193 nm as an exposure light source is currently being mass-produced. In addition, an immersion technique (called ArF immersion lithography) that fills the space between the objective lens of the exposure apparatus and the wafer with water to increase the resolution has begun to be used for mass production. In order to realize further miniaturization, various technical developments have been carried out for practical use of EUVL (Extremely UltraViolet Lithography) having an exposure wavelength of 13.5 nm.

  The structure of the EUV mask will be described with reference to FIG. As shown in FIG. 6, a multilayer film 12 for reflecting EUV light is attached on a substrate 11 made of thermally expandable glass. The multilayer film 12 usually has a structure in which several tens of layers of molybdenum and silicon are alternately stacked. As a result, EUV light having a wavelength of 13.5 nm can be reflected approximately 65% vertically. An absorber 14 that absorbs EUV light is attached on the multilayer film 12. Depending on the presence or absence of the absorber 14, a part that reflects EUV light and a part that does not reflect it are formed. Therefore, pattern exposure can be performed on the wafer. However, a protective film (a film called a buffer layer and a capping layer) 13 is attached between the absorber 14 and the multilayer film 12. This patterned EUV mask is simply referred to as an EUV mask in the present invention.

  One of the practical problems in EUVL is that carbon lumps adhere to the pattern surface of the EUV mask during exposure in the EUV exposure apparatus. This is called carbon contamination or carbon contamination. This cause will be described. There is a case in which a polymer containing carbon slightly remaining in the EUV exposure apparatus whose inside is evacuated is present in the vicinity of the pattern surface of the EUV mask. In this case, the polymer is carbonized by irradiation with EUV light, and becomes a carbon lump (referred to as a carbon lump). And it is thought that this carbon block adheres and accumulates on a pattern surface. Since the polymer is thought to be mainly generated from the resist, it is difficult to suppress this generation.

  Then, the method of removing adhering carbon is examined (nonpatent literature 1 and nonpatent literature 2). Non-Patent Document 1 discloses a method of decomposing and removing an EUV mask with atomic hydrogen (also referred to as hydrogen radical). Non-Patent Document 2 discloses a method in which an EUV mask is disposed in an oxygen atmosphere and irradiated with VUV light having a wavelength of 172 nm. Ozone is generated from oxygen by irradiation with VUV light having a wavelength of 172 nm. This ozone produces and removes carbon dioxide from carbon. VUV is an abbreviation for Vacuum UltraViolet and means vacuum ultraviolet light having a wavelength of less than 200 nm.

  Furthermore, an apparatus capable of cleaning a mirror or the like using a VUV light having a wavelength of 126 nm generated by silent discharge of argon is commercially available. This apparatus uses an elongated cylindrical lamp. VUV light having a wavelength of 126 nm is spontaneous emission light from an argon dimer (hereinafter referred to as Ar2). In this regard, for example, it is introduced as an argon excimer lamp on the website of a manufacturer that commercializes a VUV irradiation apparatus (Non-patent Document 3).

2008 Semiconductor MIRAI Project Results Report Meeting "A study of cleaning charactaristics for EUV mask blanks," 2007 International EUV Symposium, 29-31 Oct, Sapporo, Japan http://www.ntp-vuv.com/index.html [searched on December 17, 2010] Internet

  In the EUV mask cleaning method based on the carbon removal method of Non-Patent Documents 1 and 2, it is necessary to arrange the EUV mask in a hydrogen or oxygen atmosphere. When cleaning the EUV mask, the EUV mask is taken out from the EUV exposure apparatus. And it is necessary to insert in the exclusive cleaning apparatus, and to raise | generate the chemical reaction mentioned above in it.

  However, in particular, if the EUV light power is increased in order to increase the exposure processing speed of the EUV exposure apparatus, the rate at which carbon is deposited also increases. For this reason, it is necessary to frequently remove the EUV mask from the EUV exposure apparatus and clean it. That is, since exposure is frequently interrupted, there is a concern that the throughput of exposure will be significantly reduced. It is known that when exposed for 8 hours with a current low-power exposure machine, the contrast is reduced by about 5% due to carbon contamination. In the future, it is necessary to clean the exposure apparatus with EUV light power exceeding 100 W very frequently.

  Further, the EUV mask frequently goes back and forth between the EUV exposure apparatus and the cleaning apparatus. Since EUV masks do not have a pellicle that prevents particle adhesion, the possibility of particle adhesion is also a serious problem.

  On the other hand, if the VUV irradiation apparatus described above is used, VUV light having a wavelength of 126 nm from Ar2 is generated. As shown in Tables 1 and 2, VUV light having a wavelength of 126 nm is higher than the bond energy between carbons. Table 1 is a table showing an example of bond dissociation energy of carbon, and Table 2 is a table showing photon energy by various VUV light sources.

  It is considered that carbon is easily decomposed and removed by irradiating with VUV light having a wavelength of 126 nm. However, the intensity of the VUV light extracted from the conventional VUV irradiation apparatus is as low as several mW per unit square centimeter area. Moreover, since the generated VUV light spreads from the lamp and travels, the light intensity further decreases as the distance from the lamp increases. For this reason, if it is applied to the cleaning of the EUV mask, it is necessary to carry the EUV mask to just below the lamp in the VUV irradiation apparatus. Therefore, similarly to the above, problems such as a decrease in throughput and adhesion of particles occur.

  The present invention has been made in view of the above-described problems. A contamination prevention apparatus, a contamination prevention method, and an exposure apparatus and a patterned wafer using the contamination prevention apparatus and the contamination prevention method that can easily prevent contamination of the EUV mask. An object is to provide a manufacturing method.

  The contamination prevention apparatus according to the first aspect of the present invention is directed to a light source that generates vacuum ultraviolet light having a wavelength of 166 nm or less, and an EUV mask that accommodates a vacuum ultraviolet light beam from the light source in an EUV exposure apparatus. And an optical system to be irradiated. With this configuration, contamination of the EUV mask can be easily prevented.

  A pollution control apparatus according to a second aspect of the present invention is the pollution control apparatus described above, wherein the vacuum ultraviolet light is laser light from a fluorine molecular laser. Thereby, the vacuum ultraviolet light suitable for contamination prevention can be supplied.

  A pollution control apparatus according to a third aspect of the present invention is the pollution control apparatus described above, wherein the vacuum ultraviolet light is an argon dimer, krypton dimer, or spontaneous emission amplified light from fluorine molecules. Is. Thereby, the vacuum ultraviolet light suitable for contamination prevention can be supplied.

  An exposure apparatus according to a fourth aspect of the present invention includes the above contamination prevention apparatus, a chamber in which the EUV mask is accommodated, and a window provided in the chamber, and a vacuum ultraviolet ray from the contamination prevention apparatus. The EUV mask is irradiated with a beam of light through the window. Thereby, it is possible to prevent a decrease in throughput due to contamination and improve productivity.

  An exposure apparatus according to a fifth aspect of the present invention is the exposure apparatus described above, wherein the vacuum ultraviolet light is incident on a mirror that guides exposure light to a substrate to be exposed to prevent contamination of the mirror. It is characterized by. Thereby, productivity can be improved.

  The contamination prevention method according to the sixth aspect of the present invention includes a step of generating vacuum ultraviolet light having a wavelength of 166 nm or less, and a step of irradiating the EUV mask accommodated in the EUV exposure apparatus with the vacuum ultraviolet light beam. Are provided. With this configuration, contamination of the EUV mask can be easily prevented.

  A contamination prevention method according to a seventh aspect of the present invention is the contamination prevention method described above, wherein the vacuum ultraviolet light is laser light from a fluorine molecular laser. Thereby, the vacuum ultraviolet light suitable for contamination prevention can be supplied.

  The pollution prevention method according to an eighth aspect of the present invention is the pollution prevention method described above, wherein the vacuum ultraviolet light is spontaneous emission amplified light from an argon dimer, krypton dimer, or fluorine molecule. Is. Thereby, the vacuum ultraviolet light suitable for contamination prevention can be supplied.

  A contamination prevention method according to a ninth aspect of the present invention is the contamination prevention method described above, wherein the EUV mask is irradiated with the vacuum ultraviolet light during an exposure process using the EUV mask. is there. Thereby, it is possible to prevent a decrease in throughput due to contamination and improve productivity.

  A contamination prevention method according to a tenth aspect of the present invention includes a step of exposing a resist using the EUV mask that is prevented from being contaminated by the contamination prevention method, and a step of exposing the resist exposed using the EUV mask. And a developing step. Thereby, productivity can be improved.

  According to the present invention, it is possible to provide a contamination prevention apparatus, a contamination prevention method, an exposure apparatus using the same, and a method for manufacturing a patterned wafer, which can easily prevent contamination of an EUV mask.

It is a figure which shows a part of molecular structure example of a carbon lump. 1 is a diagram showing a configuration of an exposure apparatus according to a first embodiment. 1 is a view showing a configuration of an optical system of an exposure apparatus according to a first embodiment. It is a figure which shows the structure of the exposure apparatus concerning this Embodiment 2. FIG. It is a figure which shows the structure of the light source used for the pollution control apparatus concerning this Embodiment 2. FIG. It is sectional drawing which shows the structural example of an EUV mask.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description shows preferred embodiments of the present invention, and the scope of the present invention is not limited to the following embodiments. In the following description, the same reference numerals indicate substantially the same contents.

  In the present invention, in order to achieve the above-described object, the EUV mask is irradiated with a beam of vacuum ultraviolet light having a wavelength of 166 nm or less. Specifically, a light source outside the exposure apparatus is arranged to irradiate the EUV mask in the exposure apparatus with a directional vacuum ultraviolet light beam. The photon energy of light with a wavelength of 166 nm corresponds to 718 kJ per mole (see Table 2). On the other hand, according to the example of the dissociation energy of the carbon double bond shown in Table 1, the carbon double bond can be cut by photons having a wavelength of 166 nm or less. Of course, carbon single bonds can also be broken by photons having a wavelength of 166 nm or less. However, the bond dissociation energy of the carbon triple bond is 960 kJ per mole. For this reason, in order to cut | disconnect this, it is necessary to irradiate the vacuum ultraviolet light with a wavelength of 124 nm or less. However, the bond dissociation energy shown in Table 1 is merely an example, and it is known that the bond dissociation energy varies somewhat depending on the difference in molecular structure. In some cases, the triple bond of carbon can be broken by vacuum ultraviolet light having a wavelength of 126 nm.

  On the other hand, the carbon mass attached on the EUV mask is a polymer in which many carbons are bonded. For this reason, it is thought that it has the molecular structure as shown in FIG. 1, for example. That is, it is composed of a double bond between carbons, a single bond between carbons, or a single bond between carbon and hydrogen. For this reason, when these bonds are cleaved, simple carbon or a low molecular weight carbon mass is released. At that time, since the pattern surface of the EUV mask faces downward, the liberated carbon lump is dropped and removed.

  If the carbon block has a carbon triple bond, the other bond is a single bond. As a result, VUV light having a wavelength of 166 nm or less is irradiated, and the single bond is broken. Then, it is decomposed into a very low molecular weight carbon compound containing only one triple bond. From this, the low molecular weight carbon compound is released from the remaining polymer. Therefore, it is not necessary for the VUV light used in the present invention to have a short wavelength that can directly break the carbon triple bond.

  As described above, carbon is decomposed by irradiating VUV light from Ar 2, Kr 2, or F 2 corresponding to a wavelength of 166 nm or less among various VUV light sources. For this reason, it is thought that carbon contamination can be prevented.

  In particular, in the present invention, the use of beam-like VUV light is one of the major features. Thereby, VUV light can propagate several meters. As a result, even if VUV light is generated outside the EUV exposure apparatus, it is easy to guide it to an EUV mask arranged at a predetermined position in the EUV exposure apparatus. Therefore, the EUV exposure apparatus can continue to irradiate the EUV mask with VUV light even during EUV exposure.

  On the other hand, in order to specifically supply beam-shaped VUV light with a wavelength of 166 nm or less, for example, laser light with a wavelength of 157 nm extracted from a fluorine molecular laser oscillator (hereinafter referred to as F2 laser oscillator) can be used. . Since the laser beam has high directivity, there is almost no loss and it can be propagated into the exposure apparatus.

  Further, it is known that laser oscillation is difficult for Ar2 or Kr2 (krypton dimer) VUV light by discharge. That is, it is possible to generate Ar2 and Kr2 as laser light by an electron beam excitation method, but in that case, the apparatus becomes large and the repetition rate is as low as about 1 Hz.

  Therefore, in the present invention, spontaneous emission amplification (hereinafter referred to as ASE) extracted from the longitudinal direction when a gas containing argon or krypton is discharged in a shape that is long in one direction can also be used.

  ASE is known to be a highly directional beam. As a result, even if the apparatus for generating ASE is arranged outside the EUV exposure apparatus, only the ASE can be propagated and irradiated to the EUV mask arranged in the EUV exposure apparatus.

  As described above, in the present invention, by irradiating the EUV mask with a beam of VUV light having a wavelength of 157 nm, 147 nm, or 126 nm, carbon is not deposited on the EUV mask, and carbon contamination can be suppressed. It is not necessary to remove the EUV mask from the EUV exposure apparatus for cleaning due to carbon contamination. Therefore, the possibility that particles adhere to the EUV mask can be greatly reduced. In particular, the use of Kr2 or F2 VUV light facilitates handling of the light source.

Embodiment 1 FIG.
The contamination prevention apparatus and exposure apparatus according to this embodiment will be described with reference to FIG. FIG. 2 is a view showing the overall configuration of the exposure apparatus 101 having the contamination prevention apparatus 100. The exposure apparatus 101 includes a chamber 101a that houses a reduction projection optical system, and a contamination prevention apparatus 100 that is attached to the chamber 101a. In FIG. 2, the reduction projection optical system and the like of the EUV exposure apparatus 101 are omitted.

In the chamber 101a of the exposure apparatus 101, an EUV mask 108, a mask stage 107, a wafer 109, and a wafer stage 102 are provided. In addition, a convex mirror 106 and a movable mirror 112 are provided in the chamber 101a. The convex mirror 106 is used to prevent carbon contamination of the EUV mask 108. The movable mirror 112 is used to prevent carbon contamination of the mirror used in the reduction projection optical system of the exposure apparatus. A window 105 is attached to the side surface of the chamber 101a. The window 105 is made of MgF ₂ and transmits VUV light.

  The EUV mask 108 is held by a mask stage 107. The EUV mask 108 is fixed to the mask stage 107 with the pattern surface facing downward. The wafer 109 to be exposed is placed on the wafer stage 102. A resist (not shown) that causes carbon contamination is formed on the wafer 109. The wafer 109 faces upward and is placed on the wafer stage 102. The wafer stage 102 is disposed below the mask stage 107.

  In addition, the maximum size of the pattern surface of the semiconductor mask including the EUV mask 108 is usually rectangular, and specifically, the width is 104 mm and the length is 132 mm. During the exposure in the scanning exposure apparatus, scanning is performed in the longitudinal direction of 132 mm. In the present embodiment, the scanning direction is a direction perpendicular to the paper surface of FIG.

  The exposure apparatus 101 is provided with a contamination prevention apparatus 100. The contamination prevention apparatus 100 is provided with a laser oscillator 110 serving as an EUV light source. The laser oscillator 110 is installed near the outside of the EUV exposure apparatus 101. The laser oscillator 110 is an F2 laser oscillator. Therefore, the laser beam L1 becomes a laser beam having directivity.

  The laser oscillator 110 is connected to one end of the pipe 103. Laser light L1 having a wavelength of 157 nm extracted from the laser oscillator 110 propagates through the stainless steel pipe 103. In the pipe 103, mirrors 104a and 104b are provided. The other end of the pipe 103 is connected to the chamber 110 a at the position of the window 105.

  The laser beam L1 from the laser oscillator 110 is turned back by the mirrors 104a and 104b and enters the window 105. The window 105 is attached to the chamber 101a of the exposure apparatus 101. The laser beam L1 passes through the window 105 and proceeds into the chamber 101a of the EUV exposure apparatus 101. The chamber 110a is evacuated. Further, the pipe 103 is filled with nitrogen gas.

  The laser light L2 that has traveled into the chamber 101a enters the convex mirror 106. The laser beam L3 reflected by the convex mirror 106 is incident on the pattern surface of the EUV mask 108. Here, since the convex mirror 106 is used, the laser light L3 travels while spreading and enters the EUV mask 108. However, what is irradiated is a rectangular region in the entire pattern surface of the EUV mask 108. That is, in the longitudinal direction of the EUV mask 108, only a part of the EUV mask 108 is irradiated with the laser light L3. In the short direction of the EUV mask 108, the laser beam L3 is irradiated on substantially the entire EUV mask 108. With respect to the longitudinal direction of the EUV mask 108 (perpendicular to the paper surface), a rectangular region where the laser light L2 is incident is a part of the EUV mask 108. The short side direction of the rectangular region corresponds to the longitudinal direction of the EUV mask 108. By scanning the EUV mask 108 with the mask stage 107, the laser beam L3 can irradiate the entire surface of the EUV mask 108. By using the scanning of the exposure apparatus, the EUV mask can be easily irradiated with the laser light L3 even during the exposure process. As a result, the EUV mask 108 can be processed without being taken out of the chamber 110a.

  As described above, even if carbon adheres to the pattern surface of the EUV mask 108, it immediately decomposes and falls. It is possible to suppress the deposition of carbon on the pattern surface (surface facing downward) of the EUV mask 108. That is, the carbon bonds break down before the carbon grows into a carbon mass that affects exposure. Therefore, carbon contamination can be easily prevented. Further, it is not necessary to move the EUV mask from the exposure apparatus 101 to the cleaning apparatus. Thereby, it can prevent that a particle adheres at the time of conveyance. Even during the exposure process, the laser beam L3 can be incident on the EUV mask 108. That is, the EUV light of the EUV exposure is irradiated, and at the same time, the VUV light is irradiated to a position different from the position where the EUV light is incident. By doing so, the exposure process and the contamination prevention process can be performed in parallel. A reduction in throughput can be prevented and productivity can be improved.

  Next, the reduction projection optical system of the exposure apparatus 101 will be described with reference to FIG. FIG. 3 is a side view showing the configuration of the reduction projection optical system 111 of the exposure apparatus 101. Specifically, FIG. 3 is a view seen from the side where the window 105 is provided. The reduction projection optical system 111 is for a general EUV exposure apparatus including six mirrors (M1 to M6). Therefore, the reduction projection optical system 111 includes mirrors M1 to M6. The reduction projection optical system 111 is provided in the chamber 101a.

  The exposure light EUV 1 is incident on the EUV mask 108. The light EUV1 is reflected according to the pattern of the EUV mask 108 (see FIG. 6). The light EUV2 reflected by the EUV mask 108 is sequentially reflected by the mirrors M1 to M6 and enters the wafer 109. Thereby, the resist on the wafer 109 is irradiated with the light EUV2. That is, the pattern of the EUV mask 108 is reduced and projected onto the wafer 109.

  Here, the mirror M1, the mirror M3, and the mirror M5 have reflection surfaces facing upward, and the mirror M2, the mirror M4, and the mirror M6 have reflection surfaces facing downward. Further, the convex mirror 106 is disposed above the mirror M2. The mirrors M1 to M6 are, for example, concave mirrors or convex mirrors.

  The convex mirror 106 used in the present embodiment does not interfere with the EUV reduction projection optical system 111. The convex mirror 106 is disposed between the uppermost mirror M 2 of the reduction projection optical system 111 of the EUV exposure apparatus 101 and the EUV mask 108. In the direction perpendicular to the paper surface of FIG. 2, the convex mirror 106 is disposed at a location that does not block the light EUV1 and the light EUV2. . Therefore, as shown in FIG. 2, the laser beam L2 can be incident on the convex mirror 106 from below. Contamination can be prevented even during the exposure process. That is, since the convex mirror 106 does not interfere with exposure, a contamination prevention process during exposure is possible.

  The laser beam L2 from the laser oscillator 110 may be used to prevent carbon contamination of the mirror of the reduction projection optical system 111. For example, in a state where the exposure by the reduction projection optical system 111 is interrupted, the movable mirror 112 is moved below the mirror M2, M4, or M6. For example, the movable mirror 112 is slid and moved directly below the mirror M2, that is, between the mirror M2 and the mirror M3. Then, the mirror M2 is irradiated with the laser light L2 from the laser oscillator 110 via the movable mirror 112. Thereby, the carbon block adhering to the mirror M2 can be decomposed. The decomposed carbon mass falls from the reflecting surface of the mirror M2. By doing in this way, the carbon contamination of the mirror M2 can be prevented. In order to make the laser beam L2 incident on the movable mirror 112, for example, the angle of the mirror 104b may be changed. That is, it is only necessary to adjust the mirror 104b to be inclined so that the laser light L2 advances obliquely downward. Alternatively, another window or mirror may be provided in the pipe 103 or the chamber 108a. A plurality of movable mirrors 112 may be prepared according to the mirror to be cleaned. The configuration in which the laser beam L2 is incident on the mirrors M2, M4, and M6 is not particularly limited.

  Similarly, when the laser beam L2 is irradiated to the mirror M4 and the mirror M6, the movable mirror 112 may be moved directly below the mirror M4 and the mirror M6. Specifically, when the mirror M4 is irradiated with the laser light L2, the movable mirror 112 is slid between the mirror M4 and the mirror M5. When the laser beam L2 is irradiated onto the mirror M6, the movable mirror 112 is slid between the mirror M4 and the wafer 109. As a result, it is possible to irradiate the downward mirrors M2 and M4 and the mirror M6 with laser light. Therefore, this makes it possible to decompose the carbon masses on the surfaces of the mirrors M2, M4, and M6. The decomposed carbon mass falls from the reflecting surfaces of the mirrors M4 and M6. By doing in this way, the carbon contamination of the mirror M4 and the mirror M6 can be prevented. Therefore, it is possible to prevent a decrease in the reflectance of the mirror.

  The reflective surfaces of the downward mirrors M2, M4, and M6 face the wafer 109. Therefore, the progress of carbon contamination due to the resist on the wafer 109 is fast. That is, in the mirrors M2, M4, and M6, the carbon contained in the resist is more likely to adhere to the reflective surface than the mirrors M1, M3, and M5 whose reflective surfaces face upward. However, irradiating the mirrors M2, M4, and M6 with the laser beam L2 using the movable mirror 112 can prevent carbon contamination.

Embodiment 2. FIG.
A second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a diagram showing the configuration of the contamination prevention apparatus and the exposure apparatus. In the second embodiment, a light source different from that in the first embodiment is used. Specifically, the pollution prevention apparatus 200 uses the VUV-ASE generator 210 as a light source. The detailed structure of the VUV-ASE generator 210 will be described later. Other configurations are basically the same as those in the first embodiment, and thus description thereof is omitted.

The light ASE 1 having a wavelength of 147 nm extracted from the VUV-ASE generator 210 is folded back by mirrors 204 a and 204 b in the stainless steel pipe 203. Then, the light ASE 1 passes through the window 205 made of MgF ₂ attached to the chamber 201 a of the exposure apparatus 201 and proceeds into the exposure apparatus 201. The light ASE2 that has entered the exposure apparatus 201 directly irradiates the EUV mask 208 from an oblique direction. That is, in the present embodiment, the convex mirror 106 shown in the first embodiment is not provided. The pipe 203 is filled with helium gas.

  As described above, the contamination prevention apparatus 200 guides the ASE to the EUV mask 208. For this reason, the ASE can be irradiated to the EUV mask 208 without arranging a mirror or the like directly under the EUV mask 208. Even if carbon is to be deposited on the pattern surface of the EUV mask 208, the carbon is not deposited because it is immediately separated.

  Here, details of the VUV-ASE generator 210 will be described with reference to FIG. The VUV-ASE generator 210 uses a gas chamber 212 similar to a general laser chamber of a gas laser. A pair of elongated electrodes 213a and 213b are disposed in the gas chamber 212. One electrode 213 a is electrically connected to the high voltage power source 214, and the other electrode 213 b is connected to the ground 215. The pair of elongated electrodes 213a and 213b is as long as about 1 m, and the distance between the electrodes is as narrow as about 2 to 5 mm.

  Note that the high voltage power supply 214 is actually connected to a capacitor applied with a high voltage, and a pulsed large current flows from the capacitor by a switch operation not shown. ing.

On the left side of the gas chamber 212, a mirror 216 is attached perpendicular to the optical axis (the optical axis is an axis positioned in the middle of the pair of elongated electrodes 213a and 213b). Yes. A window 217 is attached to the right side of the gas chamber 212. The mirror 216 is preferably an aluminum mirror having a high reflectance at a wavelength of 147 nm or a multilayer mirror. On the other hand, the window 217 is preferably a magnesium fluoride (MgF ₂ ) flat plate having high transmittance at a wavelength of 147 nm. In FIG. 5, the window 217 is attached with a slight inclination with respect to the optical axis, but is drawn with an inclination in order to emphasize that it is not a laser device. Therefore, in practice, the window 217 may be arranged perpendicular to the optical axis in the same manner as the mirror 216.

  The gas chamber 212 is filled with about 8 atmospheres of krypton and about 1 atmosphere of helium as a buffer gas. Then, a high voltage pulse from the high voltage power source 214 is applied to the electrode 213a. By doing so, a strong pulse discharge is generated between the pair of electrodes 213a and 213b. In the longitudinal direction of the electrodes 213a and 213b, light ASE1 having a wavelength of 147 nm from the krypton dimer (Kr2) is generated. The light ASE 1 is extracted from the window 217. The light ASE 1 generated by the ASEI generator 210 travels into the exposure apparatus 201 through the window 205.

  In this embodiment, an apparatus for generating VUV light having a wavelength of 147 nm generated from Kr2 as ASE is shown, but an ASE generator having a different wavelength may be used. For example, the gas chamber 212 may be operated by being filled with argon. In this case, VUV light having a wavelength of 126 nm is obtained as ASE. By using argon gas, there is an advantage that the gas can be used at low cost.

  Alternatively, the gas chamber 212 may be filled with fluorine gas and operated. In this case, VUV light having the same wavelength 157 nm as the laser oscillator 110 shown in the first embodiment is generated as ASE. The advantage is that ASE having higher power than ASE light of Kr2 or Ar2 can be extracted relatively easily. Further, as an advantage of emitting ASE light instead of laser light, a laser resonator is unnecessary, so the number of parts is reduced and strict alignment is not required.

  As described above, the EUV mask contamination prevention apparatus not only needs to take out the EUV mask from the exposure apparatus for cleaning by carbon contamination, so that not only the exposure throughput is greatly improved, but also the particles are removed. The possibility of adhesion could be greatly reduced. Then, the resist on the wafers 109 and 209 is exposed using the EUV masks 108 and 208 described above. Then, the resist can be developed and an etching process can be performed to form a pattern on the wafer. By doing in this way, a wafer with a pattern can be manufactured with high productivity.

  Further, the first and second embodiments may be appropriately combined. For example, in the configuration of the second embodiment, carbon contamination of the exposure mirror may be prevented. Furthermore, in the configuration of the first embodiment, the ASE of the VUV-ASE generator 210 may be used for preventing carbon contamination. In the configuration of the second embodiment, the laser light from the laser oscillator 110 may be used for preventing carbon contamination. Further, the contamination preventing apparatus according to the present embodiment can be attached later to the exposure apparatus.

DESCRIPTION OF SYMBOLS 11 Substrate 12 Multilayer film 13 Protective film 14 Absorber 101 EUV exposure apparatus 101a Chamber 102 Wafer stage 103 Pipe 104a Mirror 104b Mirror 105 Window 106 Convex mirror 107 Mask stage 108 EUV mask 109 Wafer 110 Laser oscillator 112 Movable mirror 201 EUV exposure apparatus 201a chamber 202 wafer stage 203 pipe 204a mirror 204b mirror 205 window 206 convex mirror 207 mask stage 208 EUV mask 209 wafer 212 gas chamber 213a, 213b electrode 214 high voltage power supply 215 earth 216 mirror 217 window

Claims (10)

A light source that generates vacuum ultraviolet light having a wavelength of 166 nm or less;
An EUV mask contamination prevention apparatus, comprising: an optical system that irradiates a vacuum ultraviolet light beam from the light source to an EUV mask housed in an EUV exposure apparatus.   The contamination preventing apparatus according to claim 1, wherein the vacuum ultraviolet light is laser light from a fluorine molecular laser.   The contamination preventing apparatus according to claim 1, wherein the vacuum ultraviolet light is spontaneous emission amplified light from argon dimer, krypton dimer, or fluorine molecule. The pollution control device according to any one of claims 1 to 3,
A chamber in which the EUV mask is accommodated;
A window provided in the chamber,
An exposure apparatus in which a vacuum ultraviolet light beam from the contamination prevention apparatus is irradiated onto the EUV mask through the window.   5. The exposure apparatus according to claim 4, wherein the vacuum ultraviolet light is incident on a mirror that guides exposure light to a substrate to be exposed to prevent contamination of the mirror. Generating vacuum ultraviolet light having a wavelength of 166 nm or less;
Irradiating the EUV mask housed in an EUV exposure apparatus with the vacuum ultraviolet light beam.   The contamination prevention method according to claim 6, wherein the vacuum ultraviolet light is laser light from a fluorine molecular laser.   The contamination preventing method according to claim 6, wherein the vacuum ultraviolet light is spontaneous emission amplified light from argon dimer, krypton dimer, or fluorine molecule.   The contamination prevention method according to any one of claims 6 to 8, wherein the vacuum ultraviolet light is irradiated on the EUV mask during an exposure process using the EUV mask. A method for exposing a resist using an EUV mask that is prevented from being contaminated by the contamination preventing method according to claim 6,
And developing a resist exposed using the EUV mask.

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