Phase shift mask blank, phase shift mask, exposure method, and component manufacturing method

Abstract

The phase-shift mask blank of the present invention has a substrate and a phase-shift layer formed on the substrate, wherein the phase-shift layer comprises zirconium (Zr), silicon (Si), and nitrogen (N). The nitrogen concentration in the phase-shift layer is 51 atomic percent or more. Using the phase-shift mask blank, phase-shift masks with high pattern precision can be manufactured.

Description

[Technical Field]

[0001] This invention relates to phase-shift mask blanks, phase-shift masks, exposure methods, and component manufacturing methods. [Previous Technology]

[0002] A phase-shifting mask with a phase-shifting layer composed of chromium oxynitride formed on a transparent substrate is known (Patent Document 1). There has been a long-standing desire to improve the quality of phase-shifting masks. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2011-013283 [Summary of the Invention]

[0004] According to the first embodiment, the present invention provides a phase shift mask blank, which includes: a substrate; and a phase shift layer formed on the substrate, comprising zirconium (Zr), silicon (Si) and nitrogen (N), wherein the nitrogen concentration contained in the phase shift layer is 51 atomic percent or more.

[0005] According to the second state, the present invention provides a phase shift mask, which is formed by removing a portion of the phase shift layer of the phase shift mask blank of the first state and forming a predetermined pattern on the surface of the phase shift layer.

[0006] According to the third state, the present invention provides an exposure method in which a photosensitive substrate is exposed by a phase-shift photomask of the second state.

[0007] According to the fourth state sample, the present invention provides a component manufacturing method, which includes an exposure method for the third state sample.

Implementation Method

[0009] [Phase-Shift Mask Blank] The phase-shift mask blank 100 of this embodiment shown in FIG1 will be described. The phase-shift mask blank 100 includes a substrate 10 and a phase-shift layer (semi-transparent layer or phase-shift film) 20 formed on the surface (substrate surface) 10a of the substrate 10. A phase-shift mask 300 (see FIG3) can be fabricated from the phase-shift mask blank 100 by forming a predetermined pattern 50 on the phase-shift layer 20. The phase-shift mask 300 can be used in the manufacture of display devices such as FPD (Flat Panel Display) or semiconductor devices such as LSI (Large Scale Integration).

[0010] The material of the substrate 10 may be, for example, synthetic quartz glass. However, the material of the substrate 10 is not limited to synthetic quartz glass. The substrate 10 may be any material that allows sufficient light for exposure using the exposure apparatus employing the phase-shift mask 300 to pass through.

[0011] The phase shift layer 20 comprises zirconium (Zr), silicon (Si), and nitrogen (N). The nitrogen concentration in the phase shift layer 20 is 51 atomic percent or more, preferably 52 atomic percent or more, or 53 atomic percent or more. As shown in FIG3, in the phase shift mask 300, a portion of the phase shift layer 20 is removed from the substrate surface 10a by wet etching or the like, and the removed portion forms a predetermined pattern 50 on the surface of the phase shift layer 20. The pattern 50 (removed portion, recess) is distinguished from the side surface 21 of the phase shift layer 20 exposed by wet etching or the like by the exposed substrate surface 10a. FIG3 shows a cross-section of the phase shift layer 20 orthogonal to the substrate surface 10a. In the cross-section shown in FIG3, it can be determined that the closer the tilt angle θ of the side surface 21 of the phase shift layer 20 that distinguishes the pattern 50 is to 90° relative to the substrate surface 10a, the higher the precision of the pattern 50 formed on the phase shift mask 300. The tilt angle θ is defined in the cross-section of the phase shift layer 20 orthogonal to the substrate surface 10a, and includes the angle of the phase shift layer 20 itself within the angle formed by the side 21 of the pattern 50 (recess) of the phase shift layer 20 and the substrate surface 10a. Therefore, the closer the tilt angle θ is to 90°, the better. Specifically, the tilt angle θ is preferably 45° to 90°, with a lower limit of 60° and even more preferably 70°. The upper limit can be 85° or 75°. Figure 3 shows the state where θ = 90°. The inventors have discovered that by setting the nitrogen concentration in the phase shift layer 20 to 51 atomic percent or more, the pattern accuracy of the phase shift mask 300 fabricated from the phase shift mask blank 100 increases (approaches 90°). Furthermore, from the viewpoint of nitrogen introduction efficiency, the upper limit of nitrogen concentration in phase shift layer 20 is preferably below 56 atomic percent, and even more preferably below 55 atomic percent.

[0012] The zirconium concentration in the phase-shifted layer 20 is, for example, 20 atomic percent to 27 atomic percent, with a lower limit of 21 atomic percent, more preferably 22 atomic percent. The upper limit is preferably 25%, more preferably 24.5%. The silicon concentration in the phase-shifted layer is, for example, 20 atomic percent to 27 atomic percent, with a lower limit of 21 atomic percent, more preferably 22 atomic percent. The upper limit is preferably 26%, more preferably 25%.

[0013] The phase-shifted layer 20 may be free of elements other than Zr, Si and N, or contain a small amount of impurities that will not affect the effect. Furthermore, in this specification, the atomic concentration of the phase-shifted layer 20 may be determined using X-ray photoelectron spectroscopy (XPS) as described in the examples below.

[0014] Furthermore, in this embodiment, the phase-shifted mask blank stabilizes the refractive index and extinction coefficient of the phase-shifted layer 20 by setting the nitrogen concentration in the phase-shifted layer 20 to 51 atomic percent or more. When the nitrogen concentration in the phase-shifted layer 20 is less than 51 atomic percent, the refractive index and extinction coefficient of the phase-shifted layer 20 vary significantly depending on the nitrogen concentration. The refractive index tends to increase with higher nitrogen concentration. The extinction coefficient tends to decrease with higher nitrogen concentration. On the other hand, if the nitrogen concentration is 51 atomic percent or more, the refractive index remains stable at a higher value and the extinction coefficient remains stable at a lower value even when the nitrogen concentration is changed. That is, by setting the nitrogen concentration to 51 atomic percent or more, stable optical properties (refractive index and extinction coefficient) can be obtained. Since the optical properties are stable, optical design based on them becomes easier. Furthermore, in the formation step (film formation step) of the phase-shifted layer 20, the optical properties, including the values ​​of refractive index and extinction coefficient, are also stable, thus making it easier to control the film formation conditions.

[0015] Furthermore, if the nitrogen concentration in the phase shift layer 20 is 51 atomic percent or higher, the refractive index becomes higher and the extinction coefficient becomes lower, thus also producing the following advantages. By increasing the refractive index, the thickness of the phase shift layer 20 derived from the formula described below: d = λ / (2(n-1)) (d: thickness of phase shift layer 20, λ: wavelength of the exposure light, n: refractive index of phase shift layer 20 at wavelength λ) can be reduced. By reducing the thickness required for film formation, a film can be formed more uniformly on the substrate 10. Furthermore, if the thickness of the phase shift layer 20 can be reduced, the amount of side etching described below can be reduced, and a pattern 50 closer to the design size can be formed (pattern accuracy improved). Furthermore, by reducing the extinction coefficient, light absorption decreases, and the transmittance of the phase shift layer 20 can be increased.

[0016] The refractive index of the phase shift layer 20 of this embodiment for light with a wavelength of 365 nm can be, for example, 2.60 to 2.85, more preferably a lower limit of 2.7, and even more preferably 2.75.

[0017] The extinction coefficient of the phase shift layer 20 of this embodiment for light with a wavelength of 365 nm can be, for example, 0.13 to 0.18, and more preferably, the upper limit of the extinction coefficient is 0.17, more preferably 0.16, and even more preferably 0.15.

[0018] The phase shift layer 20 functions as a phase shifter that locally changes the phase of the exposure light irradiated during the exposure step using the phase shift mask 300. Therefore, the phase shift layer 20 needs to allow the exposure light to pass through to a certain extent. The transmittance of the phase shift layer 20 for the exposure light (e.g., light with wavelengths of 330 nm to 470 nm) is preferably 20% or more, or 30% to 40%. Similar to the refractive index and extinction coefficient mentioned above, the phase shift mask blank 100 of this embodiment achieves a stable transmittance of 20% or more for light with wavelengths in the aforementioned range by setting the nitrogen concentration in the phase shift layer 20 to 51 atomic percentages or more. Representative exposure lights used in the exposure step using the phase-shifted mask 300 include, for example, deep ultraviolet light (DUV, wavelengths: 302 nm, 313 nm, 334 nm), i-rays (wavelength: 365 nm), h-rays (wavelength: 405 nm), and g-rays (wavelength: 436 nm). These can be used in the form of monochromatic light or composite light.

[0019] Here, the transmittance of 365 nm light at a film thickness of the phase shift layer 20 with a phase shift of 180° relative to 365 nm light can be 30% to 40%, with a lower limit of preferably 33%, and more preferably 34%. Furthermore, the upper limit is preferably 38%, and more preferably 37%. Also, the transmittance of 405 nm light at a film thickness of the phase shift layer 20 with a phase shift of 180° relative to 405 nm light can be 45% to 55%, with a lower limit of preferably 47%, and more preferably 48%. Further, the upper limit is preferably 53%, and more preferably 52%. Also, the transmittance of 436 nm light at a film thickness of the phase shift layer 20 with a phase shift of 180° relative to 436 nm light can be 55% to 75%, with a lower limit of preferably 57%, and more preferably 60%. Furthermore, the upper limit is preferably 73%, and more preferably 72%.

[0020] The phase shift layer 20 preferably changes the phase (shift) of the exposure light irradiated in the exposure step using the phase shift mask 300 by about 180° (phase shift amount: about 180°). That is, the phase shift layer 20 preferably changes the phase of the exposure light (e.g., light with a wavelength of 330 nm to 470 nm) that passes through it by 160° to 200° (180° ± 20°) or 170° to 190° (180° ± 10°).

[0021] The phase shift amount can be adjusted by changing the refractive index and thickness (film thickness) of the phase shift layer 20 in accordance with the wavelength of the light (exposure light) passing through the phase shift mask 300. The thickness of the phase shift layer 20 can be designed with the phase shift amount being approximately 180°, taking into account the characteristics of the phase shift layer 20, such as its refractive index, and the wavelength of the light (exposure light) that passes through it. That is, the thickness d of the phase shift layer 20 can be designed based on the formula: d = λ / (2(n-1)) (d: thickness of the phase shift layer 20, λ: wavelength of the exposure light, n: refractive index of the phase shift layer 20 at wavelength λ). The thickness of the phase shift layer 20 is preferably 90 nm to 125 nm, more preferably 96 nm, and even more preferably 102 nm. The upper limit of the thickness of the phase shift layer 20 is more preferably 116 nm, and even more preferably 110 nm.

[0022] There is no particular limitation on the manufacturing method of the phase shift mask blank 100, and a common method can be used. For example, the phase shift mask blank 100 can be manufactured by forming a phase shift layer 20 on the substrate 10 using reactive sputtering as described in the embodiments below.

[0023] <Modification> In this modification, the phase shift mask blank 200 shown in FIG2 will be described. The phase shift mask blank 200 includes a substrate 10, a phase shift layer 20 formed on the surface 10a of the substrate, and an etch mask layer (chromium compound layer) 30 containing a chromium compound formed on the phase shift layer 20. Except for having the etch mask layer 30, the structure of the phase shift mask blank 200 is the same as that of the phase shift mask blank 100 shown in FIG1. ​​The phase shift mask blank 200 of this modification exhibits the same effects as the phase shift mask blank 100, and further, by having the etch mask layer 30, it exhibits the effects described below.

[0024] Similar to the phase-shift mask blank 100, a phase-shift mask 300 can be fabricated from the phase-shift mask blank 200 by forming a predetermined pattern 50 on the phase-shift layer 20 (see Figure 3). When the predetermined pattern 50 is formed on the phase-shift layer 20 by wet etching, a photoresist layer 40 is formed on the phase-shift mask blank 200 (see Figure 4(a)). In this modified example, the adhesion between the phase-shift layer (ZrSiN-based layer) 20 and the photoresist layer 40 is relatively low. Therefore, if the photoresist layer 40 is formed directly on the phase-shift layer 20, there is a risk of photoresist layer 40 peeling off during wet etching. Therefore, by providing an etched mask layer 30 with good adhesion between the photoresist layer 40 and the phase-shift layer 20 in the phase-shift mask blank 200, the peeling off of the photoresist layer 40 during wet etching can be suppressed.

[0025] The material of the etched photomask layer 30 is not particularly limited. Any material that improves the adhesion between the photoresist layer 40 and the phase shift layer 20 can be used, such as chromium compounds like chromium nitride and chromium oxide. Furthermore, in the fabrication of the phase shift photomask 300, the photoresist layer 40 is exposed to light with a wavelength of 350 nm to 450 nm. Therefore, the etched photomask layer 30 disposed beneath the photoresist layer 40 preferably has a low reflectivity for light with a wavelength of 350 nm to 450 nm, thus functioning as an anti-reflection layer; chromium oxide is preferred as an anti-reflection layer. By suppressing the reflection of the exposure light, multiple reflections of the exposure light within the photoresist layer 40 can be suppressed, improving the pattern accuracy of the phase shift photomask 300. For example, the reflectivity of the etched photomask layer 30 for light with a wavelength of 413 nm is preferably less than 15%. The etched photomask layer 30 can be a single layer or formed from multiple layers. When the etched photomask layer 30 is formed of multiple layers, it is preferable that the layer directly beneath the photoresist layer 40 has a lower reflectivity to the exposure light. For example, the etched photomask layer 30 may be composed of a chromium nitride layer 31 formed on the phase shift layer 20 and a chromium oxide layer 32 formed on the chromium nitride layer 31. The chromium oxide layer 32, for example, can suppress the reflectivity of light with a wavelength of 413 nm to about 11%.

[0026] The thickness of the etched photomask layer 30 is not particularly limited and can be adjusted appropriately, for example, it can be set to 10 nm to 120 nm. When the etched photomask layer 30 is composed of a chromium nitride layer 31 and a chromium oxide layer 32, for example, the thickness of the etched photomask layer 30 is preferably 80 to 120 nm, and the ratio of the thickness of the chromium nitride layer 31 to the thickness of the chromium oxide layer 32 is preferably formed in a ratio of 6:4 (3:2) to 8:2 (4:1). If the etched photomask layer 30 is too thin, the etching time is shortened, and the control of the critical dimension (CD) within the phase shift layer (i.e., the linewidth control of the pattern 50) becomes difficult. Also, if the etched photomask layer 30 is too thick, the lateral etching amount becomes large, and it is difficult to obtain the pattern size as designed. When wet etching is performed on the phase shift layer 20 based on the etched photomask layer 30 (see Figure 4(d)), the phase shift layer 20 is etched isotropically by the etching solution. Therefore, in addition to etching the phase shift layer 20 along a direction perpendicular to the substrate 10, the phase shift layer 20 is also etched along a transverse direction orthogonal to the vertical direction. This phenomenon of etching along the transverse direction is called lateral etching. Therefore, if the photomask layer 30 is etched too thickly, or if the phase shift layer 20 is etched too thickly as described above, there is a risk of etching a width wider than the desired pattern width.

[0027] There is no particular limitation on the manufacturing method of the phase shift mask blank 200, and a common method can be used. For example, the phase shift mask blank 200 can be manufactured by forming a phase shift layer 20 and etching a mask layer 30 on a substrate 10 using reactive sputtering as described in the embodiments below.

[0028] [Phase-Shift Mask] The phase-shift mask 300 shown in FIG3 will be described. The phase-shift mask 300 has a substrate 10 and a phase-shift layer 20 formed on the surface 10a of the substrate 10, on which a predetermined pattern 50 is formed. Except for the predetermined pattern 50 formed on the phase-shift layer 20, the structure of the phase-shift mask 300 is the same as that of the phase-shift mask blank 100 shown in FIG1. ​​In the cross-section of the phase-shift layer 20 orthogonal to the surface 10a of the substrate, the inclination angle θ of the side 21 of the phase-shift layer 20 that distinguishes the pattern 50 relative to the surface 10a of the substrate is preferably 45° to 90°.

[0029] There is no particular limitation on the manufacturing method of the phase shift mask 300, and general methods can be used. For example, the phase shift mask 300 can be manufactured using reactive sputtering and wet etching (see Figure 4) as described in the embodiments below.

[0030] [Exposure Method] Next, the exposure method using a phase shift mask 300 made from phase shift mask blanks 100 and 200 will be described. The exposure method using the phase shift mask 300 can be implemented in the manufacturing of components such as semiconductors or liquid crystal panels by means of a photolithography step using an exposure apparatus.

[0031] As shown in FIG5, the exposure apparatus 500 used in the exposure method includes a light source LS, an illumination optical system 502, a photomask stage 503 for holding the phase shift photomask 300, a projection optical system 504, a substrate platform 505 for holding the exposure object, i.e., the photosensitive substrate 515, and a drive mechanism 506 for moving the substrate platform 505 in a horizontal plane.

[0032] First, a phase-shift mask 300 is placed on the mask stage 503 of the exposure apparatus 500. A photosensitive substrate 515 coated with photoresist is placed on the substrate platform 505. Then, exposure light is emitted from the light source LS. The emitted exposure light is incident on the illumination optical system 502 and adjusted into a predetermined beam, illuminating the phase-shift mask 300 held by the mask stage 503. The light passing through the phase-shift mask 300 has a pattern identical to the pattern 50 of the elements drawn on the phase-shift mask 300, and this pattern is irradiated by the projection optical system 504 onto a predetermined position of the photosensitive substrate 515 held by the substrate platform 505. In this way, the photosensitive substrate 515 is exposed at a predetermined magnification by the element pattern of the phase-shift mask 300.

[0033] The phase-shift mask 300, fabricated from phase-shift mask blanks 100 and 200, has high pattern precision. Therefore, by using the phase-shift mask 300 for exposure, circuit pattern defects during the exposure step can be reduced, and components with high integration density can be manufactured efficiently. [Example]

[0034] Hereinafter, the phase shift mask blank and the phase shift mask will be specifically described by way of examples and comparative examples, but the present invention is not limited to these examples.

[0035] Preparation of test samples: As test samples 1 to 10, phase shift mask blanks 100 as shown in FIG1 were prepared. In addition, test samples 6 to 10 correspond to the embodiments, and test samples 1 to 5 correspond to the comparative examples.

[0036] [Test Sample 1] First, a circular parallel plate of quartz glass (size: 3 inches in diameter, 0.5 mm in thickness) was prepared as substrate 10. Using a DC magnetron sputtering apparatus, a ZrSi alloy target was used as the sputtering target. Reactive sputtering was performed while introducing an Ar-N2 mixed gas to form a phase-shifted layer 20 with a thickness of 101 nm on substrate 10, thus producing test sample 1. The composition (atomic ratio) of the ZrSi alloy target was set to Zr:Si = 1:2. The film formation conditions were set as follows: total pressure of mixed gas 0.32 Pa, N2 introduction ratio in mixed gas (sputtering gas): 5.0%, DC output 1.5 kW.

[0037] [Test Samples 2-10] The N2 introduction ratio in the mixed gas was changed as shown in Table 1. Otherwise, Test Samples 2-10 were prepared by the same method as Test Sample 1.

[0038] Evaluation of the physical properties of the phase-shifted layer (1) Composition analysis The composition of the phase-shifted layer 20 of test samples 1 to 10 was analyzed by X-ray photoelectron spectroscopy (XPS). The results are shown in Table 1. In addition, since the outermost surface of the phase-shifted layer is susceptible to oxidation, the composition analysis was performed after removing the oxidized portion of the outermost surface by sputtering. The analytical apparatus used was a Quantera AXM manufactured by PHI Corporation. The analytical conditions were set as follows: X-ray source: monochromatic Al (1486.6 eV), detection area: circular area with a diameter of 100 μm, detection depth: about 4 to 5 nm (take-off angle 45°), measurement spectrum: Zr3d, Si2p, N1s and O1s, sputtering conditions: Ar +2.0 kV, sputtering rate: about 5 nm / min (SiO2 conversion).

[0039] (2) Determination of refractive index and extinction coefficient, and simulation of transmittance. For the phase shift layer 20 of test samples 1 to 10, the refractive index and extinction coefficient under i-ray (365 nm) were determined by elliptic polarization. The results are shown in Table 1 and Figure 6. Furthermore, for the phase shift layer 20 of test samples 1 to 10, based on the results of the refractive index determination, the film thickness at which a phase shift of 180° is imparted at three wavelengths (365 nm, 405 nm, and 436 nm) was determined, and the transmittance of the phase shift layer 20 at that film thickness was calculated by simulation. The results are shown in Table 1 and Figure 7. The simulation was performed using the simulation software "TFCalc". Based on the refractive index and extinction coefficient measurements obtained by elliptic polarization under i-rays (365 nm), the transmittance of the phase-shifted layer 20 was calculated using film thicknesses with a phase shift of 180° at three wavelengths (365 nm, 405 nm, and 436 nm). Here, the transmittance also considers the external transmittance of reflections.

[0040] The phase-shift mask 300 shown in Figure 3 is fabricated by forming a pattern 50 on the phase-shift layer 20 of the test sample 1 (phase-shift mask blank). First, a DC magnetron sputtering apparatus is used, with a Cr target as the sputtering target, and reactive sputtering is performed while introducing an Ar-N2 mixed gas. Then, reactive sputtering is performed while introducing an Ar-O2 mixed gas. In this way, an etched mask layer 30 composed of a chromium nitride layer 31 and a chromium oxide layer 32 is formed on the phase-shift mask blank 100, and the phase-shift mask blank 200 (Figure 2) is fabricated. The thickness of the etched mask layer 30 is set to 96 nm (thickness of chromium nitride layer 31:thickness of chromium oxide layer 32 = 7:3). Next, a positive ultraviolet photoresist (GRX-M237 manufactured by Nagase ChemteX) was spin-coated onto the phase-shifted photomask blank 200 to form a photoresist layer 40 (Figure 4(a)). The thickness of the photoresist layer 40 was set to 660 nm.

[0041] Using a photomask equipped with a high-pressure mercury lamp, an exposure machine (PLA-501 manufactured by Canon) is used, and a light-shielding photomask with an opening corresponding to pattern 50 is used to expose the photoresist layer 40. This exposes the portion of the photoresist layer 40 corresponding to pattern 50. Next, the exposed phase-shift photomask blank 200 is immersed in an organic alkaline developer (1.83% tetramethylammonium hydroxide manufactured by Tama Chemical Industry). This dissolves and removes the photosensitive portion of the photoresist layer 40, forming an opening corresponding to pattern 50 (Fig. 4(b)).

[0042] Next, the photoresist layer 40 with openings corresponding to pattern 50 is used as a photomask, and the photomask layer 30 is wet-etched using an etching solution containing cerium ammonium nitrate and nitric acid (PureEtchCR101 manufactured by Lin Chun Pharmaceutical Co., Ltd.). The etching solution temperature is set to 23±3°C, and the etching time is set to 100 sec. In this way, the portion of the photomask layer 30 exposed and not covered by the photoresist layer 40 is removed (Fig. 4(c)).

[0043] Next, a photoresist layer 40 with openings corresponding to pattern 50 and an etched photomask layer 30 are used as a photomask. The phase shift layer 20 is wet-etched using an etchant containing ammonium fluoride (ADEKA CHELUMICA WGM-155 manufactured by ADEKA). The etchant temperature is set to 23±3°C, and 40% over-etching is performed to uniformly and completely remove the exposed phase shift layer 20. In this way, pattern 50 is formed on the phase shift layer 20 (Fig. 4(d)).

[0044] Finally, the photoresist layer 40 and the etched photomask layer 30 are stripped. Through the above steps, the phase shift photomask 300 shown in FIG4(e) is obtained from the test sample 1 (phase shift photomask blank).

[0045] The phase shift mask 300 shown in FIG3 was manufactured from test samples 2 to 10 (phase shift mask blanks) using the same method as test sample 1.

[0046] During the fabrication of the phase-shift mask 300, cross-sections of the patterns 50 formed on test samples 1 to 10 were observed. The cross-section observation was performed in the state before the etched mask layer 30 and the photoresist layer 40 were removed (the state shown in FIG4(d)). FIG8(a) to (j) show SEM images of cross-sections of test samples 1 to 10 orthogonal to the substrate surface 10a. According to FIG8(a) to (j), the tilt angle θ of the side surface 21 of the phase-shift layer 20 relative to the substrate surface 10a was measured in test samples 1 to 10. The results are shown in Table 1 and FIG9. In addition, θ is shown in FIG8(a), and the boundaries between the phase-shift layer 20 and the chromium nitride layer 31, and the boundaries between the chromium nitride layer 31 and the chromium oxide layer 32 are further indicated by dashed lines.

[0047] [Table 1] Test sample No. 1 2 3 4 5 6 7 8 9 10 N2 import ratio 5.0 10.0 20.0 25.0 30.0 35.0 40.0 60 80 100 composition N (at%) 14.4 24.9 41.6 48.8 50.7 51.5 51.6 52.1 53.4 53.9 Si (at%) 39.7 33.5 27.6 24.1 24.5 24.7 24.1 24.8 23.8 22.8 Zr (at%) 45.9 41.5 30.8 27.1 24.8 23.7 24.2 23.1 22.9 23.3 Refractive index (wavelength 365 nm) 2.249 2.400 2.682 2.853 2.872 2.791 2.765 2.758 2.705 2.658 Extinction coefficient (wavelength 365 nm) 2.459 2.133 1.421 0.895 0.292 0.149 0.157 0.166 0.168 0.166 Penetration rate (%) 365 nm wavelength 0.0 0.0 0.3 3.3 23.4 36.0 35.5 34.5 34.3 35.2 405 nm wavelength 0.0 0.0 0.6 5.8 35.1 51.5 50.3 49.2 49.7 48.8 436 nm wavelength 0.0 0.0 0.9 8.1 45.9 67.3 65.6 64.0 64.4 61.9 Tilt angle (°) 24.2 25.5 24.1 24.5 33.9 52.2 55.2 62.9 67.7 71.2

[0048] As shown in Table 1, Figure 8, and Figure 9, in test samples 6-10 where the nitrogen concentration in the phase shift layer 20 is 51 atomic percent or higher, in a cross-section of the phase shift layer 20 orthogonal to the substrate surface 10a, the tilt angle θ of the side 21 of the phase shift layer 20 that distinguishes the pattern 50 relative to the substrate surface 10a is 45° or higher. Therefore, it can be seen that a phase shift mask 300 with a well-formed pattern (high pattern precision) can be obtained from test samples 6-10 (phase shift mask blanks).

[0049] Furthermore, as shown in Table 1, Figure 6, and Figure 7, in test samples 6-10 where the nitrogen concentration in the phase shift layer 20 is 51 atomic percent or higher, the optical properties (refractive index, extinction coefficient, and transmittance) of the phase shift layer 20 show little difference among the test samples, being close values. That is, when the nitrogen concentration in the phase shift layer 20 is 51 atomic percent or higher, even if the nitrogen concentration in the phase shift layer 20 changes, the optical properties (refractive index, extinction coefficient, and transmittance) remain stable. Furthermore, as shown in Table 1, Figure 10, and Figure 11, test samples 6-10 were fabricated by varying the nitrogen introduction ratio in the sputtering gas within a wide range from 35% to 100% during the phase shift layer 20 formation step (film formation step). If the nitrogen introduction ratio is 35% or higher (test samples 6-10), the optical properties of the phase shift layer 20 are stable, thus making it easy to control the film formation conditions.

[0050] On the other hand, as shown in Table 1, Figures 8 and 9, the tilt angle θ of test samples 1-5, where the nitrogen concentration in the phase shift layer 20 did not reach 51 atomic percentages, did not reach 45°. This indicates that the pattern accuracy of the phase shift mask 300 fabricated from test samples 1-5 (phase shift mask blanks) is relatively low. Furthermore, as shown in Table 1, Figures 6 and 7, the optical properties (refractive index, extinction coefficient, and transmittance) of the phase shift layer 20 of test samples 1-5, where the nitrogen concentration in the phase shift layer 20 did not reach 51 atomic percentages, varied significantly depending on the nitrogen concentration. Also, as shown in Table 1, test samples 1-5 were fabricated in the phase shift layer 20 formation step (film formation step) with the nitrogen introduction ratio in the sputtering gas not reaching 35%. As shown in Figures 10 and 11, if the nitrogen introduction ratio in the sputtering gas does not reach 35% (test samples 1-5), the optical properties of the phase-shifted layer 20 change significantly depending on the nitrogen introduction ratio. Therefore, strict control of the film formation conditions is required. [Industrial Applicability]

[0051] The phase shift mask blank of this embodiment can be used to manufacture a phase shift mask with high pattern precision. The phase shift mask can be used in the manufacture of display components such as FPDs or semiconductor components such as LSIs. [Simplified Explanation of the Diagram]

[0008] [Fig. 1] is a schematic cross-sectional view of the phase-shift mask blank of the embodiment. [Fig. 2] is a schematic cross-sectional view of the phase-shift mask blank of the modified example. [Fig. 3] is a schematic cross-sectional view of the phase-shift mask of the embodiment. [Fig. 4] Figs. 4(a) to (e) are diagrams illustrating the manufacturing method of the phase-shift mask of the embodiment. [Fig. 5] is a schematic diagram of the exposure apparatus used in the exposure method of the embodiment. [Fig. 6] is a graph showing the relationship between the nitrogen concentration in the phase-shift layer of the embodiment and the refractive index and extinction coefficient of the phase-shift layer for light with a wavelength of 365 nm. [Fig. 7] is a graph showing the relationship between the nitrogen concentration in the phase-shift layer of the embodiment and the transmittance of the phase-shift layer for light with a wavelength of 365 nm. [Fig. 8] Figs. 8(a) to (j) are SEM images of the cross-section of the phase-shift layer of the embodiment. [Figure 9] is a graph showing the relationship between the nitrogen concentration in the phase-shifted layer and the tilt angle of the phase-shifted layer profile in the embodiment. [Figure 10] is a graph showing the relationship between the nitrogen introduction ratio in the sputtering gas and the refractive index and extinction coefficient of the phase-shifted layer for light with a wavelength of 365 nm in the embodiment. [Figure 11] is a graph showing the relationship between the nitrogen introduction ratio in the sputtering gas and the transmittance of the phase-shifted layer for light with a wavelength of 365 nm in the embodiment.

Claims

1. A phase-shifted photomask blank comprising: a substrate; and a phase-shifted layer formed on the substrate, comprising zirconium (Zr), silicon (Si) and nitrogen (N), wherein the nitrogen concentration in the phase-shifted layer is 51 atomic percent or more; and the extinction coefficient of the phase-shifted layer for light with a wavelength of 365 nm is 0.13 to 0.

18.

2. A phase-shifted photomask blank comprising: a substrate; and a phase-shifted layer formed on the substrate, comprising zirconium (Zr), silicon (Si) and nitrogen (N), wherein the nitrogen concentration in the phase-shifted layer is 51 atomic percent or more; and the transmittance of the phase-shifted layer at a wavelength of 365 nm is 30% to 40% for a film thickness that imparts a 180° phase shift to light at a wavelength of 365 nm.

3. The phase shift mask blank as requested in item 1 or 2, wherein the nitrogen concentration in the aforementioned phase shift layer is 51 atomic percent to 56 atomic percent.

4. The phase shift mask blank as requested in item 1 or 2, wherein the zirconium concentration in the aforementioned phase shift layer is 20 atomic percent to 27 atomic percent.

5. The phase shift mask blank as requested in item 1 or 2, wherein the silicon concentration in the aforementioned phase shift layer is 20 atomic percent to 27 atomic percent.

6. The phase-shifted photomask blank of claim 1 or 2, wherein the refractive index of the phase-shifted layer for light with a wavelength of 365 nm is 2.60 to 2.

85.

7. The phase shift mask blank of claim 1 or 2, wherein the transmittance of light with a wavelength of 330 nm to 470 nm of the aforementioned phase shift layer is 20% or more.

8. The phase-shifted photomask blank of claim 1 or 2, wherein the transmittance of the phase-shifted layer at a wavelength of 405 nm is 45% to 55% under a film thickness that imparts a 180° phase shift to light at a wavelength of 405 nm.

9. The phase-shifted photomask blank of claim 1 or 2, wherein the transmittance of the phase-shifted layer at a wavelength of 436 nm is 55% to 75% under a film thickness that imparts a 180° phase shift to light at a wavelength of 436 nm.

10. The phase-shifted photomask blank of claim 1 or 2, wherein the phase-shifted layer causes a phase shift of 160° to 200° in light passing through the phase-shifted layer.

11. The phase-shifted photomask blank of claim 10, wherein the phase-shifted layer causes a phase shift of 170° to 190° in light passing through the phase-shifted layer.

12. The phase shift mask blank of claim 1 or 2 further comprises a chromium compound layer formed on the aforementioned phase shift layer.

13. The phase shift mask blank of claim 12, wherein the chromium compound layer comprises chromium (Cr) and oxygen (O).

14. The phase shift mask blank of claim 12, wherein the chromium compound layer comprises a chromium nitride (CrN) layer formed on the phase shift layer and a chromium oxide (CrO) layer formed on the chromium nitride layer.

15. A phase-shift mask, wherein a portion of the phase-shift layer of a phase-shift mask blank as claimed in any one of claims 1 to 14 is removed, and a predetermined pattern is formed on the surface of the phase-shift layer.

16. The phase-shifted photomask of claim 15, wherein in a cross section of the phase-shifted layer orthogonal to the surface of the substrate, the angle formed by the side of the phase-shifted layer that distinguishes the pattern from the surface of the substrate, including the angle of the phase-shifted layer, i.e., the tilt angle, is 45° to 90°.

17. The phase-shifted photomask of claim 16, wherein the tilt angle is 60° to 90°.

18. An exposure method comprising exposing a photosensitive substrate via a phase-shift photomask as claimed in claim 15.

19. A method for manufacturing a component, comprising the exposure method as claimed in claim 18.

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