TW202347011A - Phase shift mask blank, phase shift mask, and methods for manufacturing same - Google Patents

Abstract

This phase shift mask blank has: a substrate; and a first layer that is deposited on the substrate. The first layer contains zirconium (Zr), silicon (Si), and nitrogen (N). The transmittance of the first layer at a thickness at which a 180 DEG phase shift is imparted to light having a wavelength of 365 nm is 4-40%.

Description

Phase shift mask base plate, phase shift mask, and manufacturing methods thereof

The present invention relates to a phase shift mask base plate, a phase shift mask, and manufacturing methods thereof.

A phase shift mask is known in which a phase shift layer composed of chromium nitride oxide is formed on a transparent substrate (Patent Document 1). There has always been a desire to improve the quality of phase shift masks.

Currently, silicone-based phase shift films use MoSi films with i-ray (365 nm) transmittance of 5%. In addition, in order to improve the phase shift effect, films with higher penetration have also been proposed. By increasing the nitrogen content, a penetration rate of about 10% can be achieved. However, the problem with the MoSi film is that the wet etching time is long. As the etching time is extended, the etching of the glass continues, so it becomes difficult to control the amount of phase shift. Furthermore, it also leads to an increase in the consumption of etchants and a decrease in production capacity. [Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2011-013283

The first aspect provides a phase shift mask substrate, which has a substrate and a first layer formed on the substrate, where the first layer contains zirconium (Zr), silicon (Si) and nitrogen (N), and The above-mentioned first layer has a transmittance of 4% to 40% at a film thickness that causes a 180° phase shift of light with a wavelength of 365 nm.

The second aspect provides a phase shift mask substrate, which has a substrate and a first layer formed on the substrate, and the first layer has four or more layers of metal silicide containing zirconium (Zr) and silicon (Si). It is a laminate of nitrides, and the transmittance of the first layer above is 4% to 40% at a film thickness that causes a 180° phase shift of light with a wavelength of 365 nm.

A third aspect provides a phase shift mask substrate, which has a substrate and a first layer formed on the substrate. The first layer has four or more layers of metal containing zirconium (Zr) and silicon (Si). It is a lamination of silicon nitride, and the inclination angle of the first layer is 55° or more and 90° or less.

A fourth aspect provides a phase shift mask, which has a required pattern formed in the phase shift mask substrate of any one of the first to third aspects.

The fifth aspect provides a method for manufacturing a phase shift mask substrate, which has a film forming step of forming a first layer on a substrate. In the above film forming step, a metal containing zirconium and silicon is applied to the substrate four or more times. The nitride layer of silicon compound is formed into a film to form the first layer.

A sixth aspect provides a method for manufacturing a phase shift mask, which is the manufacturing method of a phase shift mask substrate of the fifth aspect and further includes a pattern forming step for forming a desired pattern.

Hereinafter, an embodiment of the present invention (hereinafter referred to as "this embodiment") will be described. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be implemented with appropriate modifications within the scope of the gist of the invention.

[Phase Shift Mask Base 100] The phase shift mask base plate 100 of this embodiment shown in FIG. 1 will be described. The phase shift mask base 100 includes a substrate 10 and a phase shift layer 20 formed on the surface 10 a of the substrate 10 (substrate surface). According to the phase shift mask substrate 100, the phase shift mask 300 can be manufactured by forming a specific pattern 50 in the phase shift layer 20 (see FIG. 3). The phase shift mask 300 is used when manufacturing display devices such as FPD (Flat Panel Display) or semiconductor devices such as LSI (Large Scale Integration).

As a material of the substrate 10, for example, synthetic quartz glass is used. Furthermore, the material of the substrate 10 is not limited to synthetic quartz glass. The substrate 10 only needs to fully transmit the exposure light of the exposure device using the phase shift mask 300 .

The phase shift layer 20 contains zirconium (Zr), silicon (Si) and nitrogen (N). As shown in FIG. 3 , in the phase shift mask 300 , a portion of the phase shift layer 20 is removed from the substrate surface 10 a by wet etching, and the removed portion forms a specific pattern 50 on the surface of the phase shift layer 20 . The pattern 50 (removed portion, recessed portion) is divided by the side surface 21 of the phase shift layer 20 exposed by wet etching, and the exposed substrate surface 10a. FIG. 3 shows a cross section of the phase shift layer 20 perpendicular to the substrate surface 10a. In the cross-section shown in FIG. 3 , the closer the inclination angle θ of the side surface 21 of the phase shift layer 20 dividing the pattern 50 from the substrate surface 10 a is to 90°, the accuracy of the pattern 50 formed in the phase shift mask 300 can be judged. The higher. The tilt angle θ is in the cross section of the phase shift layer 20 that is orthogonal to the substrate surface 10 a. The angle between the side surface 21 of the dividing pattern 50 (concave portion) of the phase shift layer 20 and the substrate surface 10 a includes the angle of the phase shift layer 20 . Therefore, the closer the tilt angle θ is to 90°, the better. Specifically, the inclination angle θ is preferably 45° to 90°, and the lower limit is more preferably 60°, and still more preferably 70°. The upper limit value can be 85° or 75°. Fig. 3 shows the state of θ=90°. The inventors of the present invention found that by forming multiple phase shift layers 20 , in the phase shift mask 300 manufactured from the phase shift mask base plate 100 , the tilt angle θ becomes larger (close to 90°), and the phase shift mask 300 The pattern accuracy is improved. Therefore, the phase shift layer 20 of this embodiment is preferably composed of multiple layers, for example, it can be a stack of 4 to 10 layers. The lower limit is 5 layers, and a better limit is 6 layers. By forming the phase shift layer 20 as a stacked layer in this manner, the tilt angle θ can be continuously increased, thereby improving the pattern accuracy by reducing the amount of undercutting. Furthermore, although the phase shift layer 20 in FIGS. 1 to 5 is illustrated as a single layer (one layer), it is illustrated in a state in which multiple layers are laminated.

The phase shift layer 20 may not contain elements other than Zr, Si and N, or may contain a small amount of impurities that do not affect the degree of effect.

In addition, the refractive index of the phase shift layer 20 of the phase shift mask base plate of this embodiment has a relatively high value. By increasing the refractive index, the following formula can be obtained: d=λ/(2(n-1)) (d: thickness of the phase shift layer 20, λ: wavelength of the exposure light, n: wavelength λ The thickness of the phase shift layer 20 derived from the refractive index of the phase shift layer 20 becomes thinner. 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 made thinner, the amount of undercutting described below can be reduced, and the pattern 50 closer to the design size can be formed (pattern accuracy is improved).

The refractive index of the phase shift layer 20 in this embodiment for light with a wavelength of 365 nm can be, for example, 2.70-2.90, and a more preferable lower limit of the refractive index is 2.75, and even more preferably 2.80. By setting the refractive index to such a high level, the film thickness can be reduced to a phase shift amount of 180°.

The phase shift layer 20 of this embodiment has an extinction coefficient of 0.13 to 0.80 for light with a wavelength of 365 nm, for example, and a more preferable upper limit of the extinction coefficient is 0.70, more preferably 0.60, and even more preferably 0.50.

The phase shift layer 20 functions as a phase shifter that locally changes the phase of the exposure light irradiated in the exposure step using the phase shift mask 300 . Therefore, the phase shift layer 20 needs to allow exposure light to penetrate to some extent. The transmittance of the phase shift layer 20 for exposure light (for example, light with a wavelength of 330 nm to 470 nm) is preferably 3% or more and 85% or less. Representative exposure lights used in the exposure step using the phase shift mask 300 include, for example, deep ultraviolet light (DUV, wavelength: 302 nm, 313 nm, 334 nm), i-light (wavelength: 365 nm) ), h light (wavelength: 405 nm), g light (wavelength: 436 nm). These can be used in the form of monochromatic light, or they can be used in the form of composite light.

Here, the phase shift layer 20 can have a transmittance of light with a wavelength of 365 nm between 4% and 40% at a film thickness at which the light with a wavelength of 365 nm undergoes a phase shift of 180°, and the lower limit is preferably 5 %, preferably 8%. Moreover, the upper limit value is preferably 38%, more preferably 37%. In addition, the transmittance of the phase shift layer 20 for light with a wavelength of 405 nm can be 5% to 50% at a film thickness at which the light of a wavelength of 405 nm undergoes a phase shift of 180°, and the lower limit is preferably 7%. The best is 8%. Furthermore, the upper limit value is preferably 49%, more preferably 48%. In addition, the transmittance of the phase shift layer 20 for light with a wavelength of 436 nm can be 8% to 65% at a film thickness at which the light of a wavelength of 436 nm undergoes a phase shift of 180°, and the lower limit is preferably 9%. The best is 10%. Moreover, the upper limit value is preferably 63%, more preferably 60%.

The phase shift layer 20 preferably changes (shifts) the phase of the exposure light irradiated in the exposure step using the phase shift mask 300 by approximately 180° (phase shift amount: approximately 180°). That is, the phase shift layer 20 is preferably such that the phase change of the exposure light (for example, light with a wavelength of 330 nm to 470 nm) passing through it is 160° to 200° (180°±20°), 170° to 190°. (180°±10°), or 175°～185° (180°±5°).

The amount of phase shift can be adjusted by changing the refractive index, thickness (film thickness), etc. of the phase shift layer 20 according to the wavelength of the light (exposure light) that penetrates the phase shift mask 300 . The thickness of the phase shift layer 20 can be designed so that the phase shift amount is about 180°, taking into account the refractive index and other characteristics of the phase shift layer 20 and the wavelength of the light that is transmitted (exposed light). 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: wavelength λ the refractive index of the phase shift layer 20). The thickness of the phase shift layer 20 is, for example, preferably 90 nm to 125 nm. The lower limit of the thickness of the phase shift layer 20 is more preferably 94 nm, and more preferably 96 nm. A more preferable upper limit of the thickness of the phase shift layer 20 is 116 nm, and more preferably, it is 110 nm. By setting this film thickness, the etching time until the 180° phase shift occurs is shortened, and damage to the glass is reduced.

The phase shift mask base plate 100 is manufactured using a method described below. For example, the phase shift mask base plate 100 can be manufactured by depositing the phase shift layer 20 on the substrate 10 using reactive sputtering as described in the embodiments described later.

[Phase Shift Mask Base 200] The phase shift mask base plate 200 shown in FIG. 2 will be described. The phase shift mask base 200 includes a substrate 10 , a phase shift layer 20 formed on the substrate surface 10 a , and an etching mask layer (chromium compound layer) 30 formed on the phase shift layer 20 and containing a chromium compound. Except for the etching mask layer 30 , the other components of the phase shift mask substrate 200 are the same as the phase shift mask substrate 100 shown in FIG. 1 . The phase shift mask substrate 200 shown in FIG. 2 exhibits the same effects as the phase shift mask substrate 100 , and further exhibits the effects described below by having the etching mask layer 30 .

Similar to the phase shift mask substrate 100 , the phase shift mask 300 can be manufactured from the phase shift mask substrate 200 by forming a specific pattern 50 in the phase shift layer 20 (see FIG. 3 ). When a specific pattern 50 is formed in the phase shift layer 20 by wet etching, a photoresist layer 40 is formed on the phase shift mask substrate 200 (refer to FIG. 4(A) ). The phase shift layer (ZrSiN based layer) 20 here has low adhesion to the photoresist layer 40 . Therefore, if the photoresist layer 40 is directly formed on the phase shift layer 20, there is a risk that the photoresist layer 40 may be peeled off during wet etching. Therefore, in the phase shift mask substrate 200, by providing the etching mask layer 30 that is in close contact with both the photoresist layer 40 and the phase shift layer 20, the peeling of the photoresist layer 40 during wet etching can be suppressed. .

The material of the etching mask layer 30 is not particularly limited as long as it is a material that improves the adhesion with the photoresist layer 40 and the phase shift layer 20. For example, chromium compounds such as chromium nitride and chromium oxide can be used. In addition, during the manufacture of the phase shift mask 300, the photoresist layer 40 is exposed with light having a wavelength of 350 nm to 450 nm. Therefore, the etching mask layer 30 provided under the photoresist layer 40 is preferably one with low reflectivity for light with a wavelength of 350 nm to 450 nm, and also functions as an anti-reflective layer. Chromium oxide is preferably used as an anti-reflective layer. By suppressing the reflection of the exposure light, multiple reflections of the exposure light in the photoresist layer 40 can be suppressed, and the pattern accuracy of the phase shift mask 300 is improved. For example, the reflectivity of the etching mask layer 30 for light with a wavelength of 413 nm is preferably less than 15%. The etching mask layer 30 may be a single layer or may be formed of multiple layers. When the etching mask layer 30 is formed of multiple layers, it is preferable that the layer directly below the photoresist layer 40 has a low reflectivity for exposure light. For example, the etching mask 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 can suppress the reflectivity of light with a wavelength of 413 nm to about 11%, for example.

The thickness of the etching mask 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 etching mask layer 30 is composed of a chromium nitride layer 31 and a chromium oxide layer 32, for example, the thickness of the etching mask layer 30 is preferably 80-120 nm, and is preferably the thickness of the chromium nitride layer 31. The film is formed at a ratio of 6:4 (3:2) to 8:2 (4:1) to the thickness of the chromium oxide layer 32 . If the etching mask layer 30 is too thin, the etching time will be shortened, and CD (critical dimension) control in the phase shift layer (ie, line width control of the pattern 50) will become difficult. In addition, if the etching mask layer 30 is too thick, the amount of side etching will increase, making it difficult to obtain the designed pattern size. When the phase shift layer 20 is wet-etched based on the etching mask layer 30 (see FIG. 4(D) ), the phase shift layer 20 is isotropically etched by the etching liquid. Therefore, in addition to etching the phase shift layer 20 in a direction perpendicular to the substrate 10 , the phase shift layer 20 is also etched in a transverse direction orthogonal to the vertical direction. This phenomenon of etching in the lateral direction is called side etching. Therefore, when the etching mask layer 30 is too thick, or when the phase shift layer 20 is too thick as described above, there is a risk of etching with a width wider than the required pattern width.

The manufacturing method of the phase shift mask base plate 200 is not particularly limited, and general methods can be used. For example, the phase shift mask base plate 200 can be manufactured by forming the phase shift layer 20 and etching the mask layer 30 on the substrate 10 using reactive sputtering as described in FIG. 6 or in the embodiment described below.

FIG. 6 is a schematic diagram showing the manufacturing device 600 of the phase shift mask substrates 100 and 200 according to this embodiment, and is a view of the inside of the manufacturing device 600 viewed from above. The film forming apparatus 600 shown in FIG. 6 is an in-line sputtering apparatus, and is provided with a loading chamber 601 for loading the substrate 10 for manufacturing the phase shift mask substrates 100 and 200, and a first sputtering device. The chamber 602, the buffer chamber 603, the second sputtering chamber 604, and the unloading chamber 605 for unloading the manufactured phase shift layer 20.

The substrate tray P is a frame-shaped tray that can place the substrate 10 for forming the phase shift layer 20, and supports and places the outer edge portion of the substrate 10. The substrate 10 is placed on the lower side (the surface on which the light-shielding film and the anti-reflection film are formed as the phase shift layer 20 (ZrSiN-based layer) and the etching mask layer 30 (chromium compound layer)) is placed on the lower side (facing downward). On the substrate tray P. In the film forming apparatus 600 , as will be described later, the substrate 10 on which the substrate 10 is placed is moved along the direction indicated by the solid arrow Q in FIG. 6 while maintaining the state in which the surface of the substrate 10 faces the target. The tray P is transported to the position of the buffer chamber 603, whereby the first phase shift layer 20 (ZrSiN-based layer) is formed on the surface of the substrate 10, and the phase shift mask base plate 100 having a single layer of the phase shift layer 20 is manufactured.

As shown by the solid arrow Q, after the first phase shift layer 20 is formed, the substrate tray P is repeatedly transported between the loading chamber 601 and the buffer chamber 603, thereby manufacturing the phase shift mask base 100 having the phase shift layer 20. , the phase shift layer 20 is composed of layers corresponding to the number of transfers. In addition, the ZrSiN-based layer can be formed in the same manner both in the case of transferring from the loading chamber 601 to the buffer chamber 603 and in the case of transferring from the buffer chamber 603 to the loading chamber 601 .

After the phase shift mask bottom plate 100 is manufactured, the substrate tray P is transported from the buffer chamber 603 to the position of the unloading chamber 605 as indicated by the dotted arrow R, thereby forming an etching mask layer on the phase shift layer 20 30 (chromium compound layer) to manufacture the phase shift mask base plate 200.

The carry-in chamber 601, the first sputtering chamber 602, the buffer chamber 603, the second sputtering chamber 604, and the carry-out chamber 605 are separated by baffles (not shown). The carry-in chamber 601, the first sputtering chamber 602, the buffer chamber 603, the second sputtering chamber 604, and the carry-out chamber 605 are respectively connected to an exhaust device (not shown) to exhaust the inside of each chamber.

The first target 606 (ZrSi) is provided inside the first sputtering chamber 602, and the second target 607 (Cr) is provided inside the second sputtering chamber 604. DC power supplies (not shown) are respectively provided in the first sputtering chamber 602 and the second sputtering chamber 604 to supply power to the first target 606 (ZrSi) and the second target 607 (Cr) respectively.

The first sputtering chamber 602 is provided with a first gas inlet 608 for introducing a sputtering gas into the first sputtering chamber 602 . The first target 606 is a sputtering target used to form a ZrSiN-based layer, and is made of a material containing zirconium (Zr) and silicon (Si). Specifically, the first target 606 is made of a material selected from zirconium, zirconium oxide, zirconium nitride, zirconium carbide, silicon, silicon oxide, silicon nitride, silicon carbide, etc. form. For example, in order to form a ZrSiN film, a mixed gas of a nitrogen-containing gas and an inert gas (argon gas, etc.) is introduced through the first gas inlet 608 .

The second sputtering chamber 604 is provided with a second gas inlet 609 for introducing a sputtering gas into the second sputtering chamber 604 . The second target 607 is a sputtering target for forming a chromium compound layer, and is made of a material containing chromium. Specifically, the second target 607 is formed of a material selected from chromium, chromium oxides, chromium nitrides, chromium carbides, and the like. For example, in order to form a CrCN film as a light-shielding film, a mixed gas of a nitrogen- or oxygen-containing gas and an inert gas (argon gas, etc.) is introduced through the second gas inlet 609 .

When the substrate 10 is transported to the first sputtering chamber 602, the first phase shift layer 20 (ZrSiN-based layer) is formed on the surface of the substrate 10 by sputtering in the first sputtering chamber 602. Furthermore, the substrate 10 on which the first phase shift layer 20 is formed can also be transported multiple times between the buffer chamber 603 and the loading chamber 601 and sputtered multiple times in the first sputtering chamber 602. The phase shift layer 20 is a built-up layer. Thereafter, the substrate 10 is transported to the second sputtering chamber 604 . In the second sputtering chamber 604, the etching layer 30 (chromium compound layer) is formed on the surface of the phase shift layer 20 by sputtering. Similar to the ZrSiN layer, the chromium compound layer can also be transported multiple times between the buffer chamber 603 and the carry-out chamber 605 and sputtered multiple times in the second sputtering chamber 604, so that the etching layer 30 can be Lamination. In this way, a ZrSiN layer and a chromium compound layer are sequentially formed on the surface of the substrate 10 to manufacture the phase shift mask base plate 200 .

Furthermore, the materials of the first and second targets 606 and 607 and the types of gases introduced from the first and second gas inlets 608 and 609 can be appropriately selected according to the materials or compositions constituting the chromium compound layer and the ZrSiN layer. . In addition, any method among DC sputtering, RF sputtering, ion beam sputtering, etc. can be used as a sputtering method.

[Phase Shift Mask] The phase shift mask 300 shown in FIG. 3 will be described. The phase shift mask 300 has a substrate 10 and a phase shift layer 20 formed on the surface 10 a of the substrate 10 . A specific pattern 50 is formed in the phase shift layer 20 . Except for the specific pattern 50 formed in the phase shift layer 20, other structures of the displacement mask 300 are the same as the phase shift mask base plate 100 shown in FIG. 1. In the cross section of the phase shift layer 20 that is orthogonal to the substrate surface 10a, the inclination angle θ of the side surface 21 of the phase shift layer 20 dividing the pattern 50 from the substrate surface 10a is preferably 45° to 90°. In addition, by forming the phase shift layer 20 as a stacked layer, the inclination angle θ can be brought closer to a right angle, thereby improving the pattern accuracy by reducing the amount of undercutting.

The manufacturing method of the phase shift mask 300 is not particularly limited, and general methods can be used. For example, the phase shift mask 300 can be manufactured using reactive sputtering and wet etching (refer to FIG. 4 ) described in the embodiments described below.

[Exposure method] Next, an exposure method using the phase shift mask 300 produced from the phase shift mask base plates 100 and 200 will be described. The exposure method using the phase shift mask 300 can be implemented as a photolithography step using an exposure device in device manufacturing of semiconductors or liquid crystal panels.

As shown in FIG. 5 , the exposure device 500 used in the exposure method includes: a light source LS; an illumination optical system 502; a mask stage 503 that holds the phase shift mask 300; a projection optical system 504; and a substrate stage 505 that holds the exposure The photosensitive substrate 515 of the object; and the driving mechanism 506 that moves the substrate stage 505 in the horizontal plane.

First, the phase shift mask 300 is placed on the mask stage 503 of the exposure device 500 . Furthermore, the photosensitive substrate 515 coated with photoresist is placed on the substrate stage 505 . Furthermore, exposure light is emitted from the light source LS. The emitted exposure light enters the illumination optical system 502 and is adjusted into a specific light beam, and is irradiated to the phase shift mask 300 held on the mask stage 503 . The light passing through the phase shift mask 300 has the same pattern as the pattern 50 of the device depicted on the phase shift mask 300, and the pattern is illuminated through the projection optical system 504 to a specific position of the photosensitive substrate 515 held on the substrate stage 505 . Thereby, the photosensitive substrate 515 is exposed at a specific magnification through the device pattern of the phase shift mask 300 .

The phase shift mask 300 manufactured from the phase shift mask base plates 100 and 200 has high pattern accuracy. Therefore, by using the phase shift mask 300 for exposure, circuit pattern defects during the exposure step can be reduced, and devices with a high integration density can be manufactured efficiently. [Example]

Hereinafter, the phase shift mask base plate and the phase shift mask will be described in detail using Examples and Comparative Examples, but the present invention is not limited to these Examples and Comparative Examples.

As Examples 1 to 5, phase shift mask substrates having five types of ZrSiN phase shift layers 20 with different nitrogen introduction ratios were manufactured. Furthermore, as a comparative example, a phase shift mask substrate having two types of MoSiN phase shift layers 20 with different nitrogen introduction ratios was manufactured.

[Production of Phase Shift Mask Base Plate 100] As the substrate 10, a circular parallel flat plate of quartz glass (size: 3 inches in diameter, 0.5 mm in thickness) was prepared. A DC magnetron sputtering device was used, a ZrSi alloy was used as a sputtering target, and Ar-N ₂ mixed gas was introduced at the introduction ratio shown in Table 2 while performing reactive sputtering to form a ZrSiN film on the substrate 10 . Thereafter, reactive sputtering using the same ZrSi alloy target as described above was repeated five times to form a ZrSiN phase shift layer 20 containing a total of six layers, and the phase shift mask base plate 100 was manufactured (Examples 1 to 5). . The composition (atomic ratio) of ZrSi alloy target is Zr:Si=1:2. Regarding each film formation condition, the total pressure of the mixed gas is 0.32 Pa, and the N ₂ introduction ratio in the mixed gas (sputtering gas) is as follows: 24% in Example 1, 26% in Example 2, and 28 in Example 3 %, 30% in Example 4, 60% in Example 5, and the DC outputs of Examples 1 to 5 are all 1.5 kw.

Comparative example: Using a MoSi alloy target (atomic ratio: Mo:Si = 1:4) as a sputtering target, one pass of Ar-N ₂ mixed gas was introduced at the introduction ratio shown in Table 2 (single layer) Reactive sputtering. The N ₂ introduction ratio in the mixed gas (sputtering gas) was as follows: 30% in Comparative Example 1 and 36% in Comparative Example 2, and the film was formed in this way. Under the above conditions, the MoSiN phase shift layer 20 is formed, and a phase shift mask base plate is manufactured.

[Manufacture of the phase shift mask base plate 200] A DC magnetron sputtering device was used on the phase shift mask base plate 100 of each embodiment and each comparative example, a Cr target was used as the sputtering target, and Ar-N was introduced on one side. ₂ mixed gas while performing reactive sputtering, and then introducing Ar-O ₂ mixed gas while performing reactive sputtering. Thereby, the etching mask layer 30 composed of the chromium nitride layer 31 and the chromium oxide layer 32 is formed on the phase shift mask base plate 100, and the phase shift mask base plate 200 is manufactured (FIG. 2). The film is formed so that the thickness of the etching mask layer 30 is within the range of 90±7nm (thickness of the chromium nitride layer 31:thickness of the chromium oxide layer 32=7:3). Next, a positive ultraviolet photoresist (GRX-M237 manufactured by Nagase Chemical Industry) is coated on the phase shift mask base plate 200 by spin coating to form the photoresist layer 40 ( FIG. 4(A) ). The thickness of the photoresist layer 40 is 660 nm.

[Evaluation of physical properties of phase shift layer 20] Determination of refractive index and extinction coefficient, and simulation of transmittance Regarding the phase shift layer 20 of each example and each comparative example, the refractive index and extinction coefficient were measured using the ellipsometry method. The results are shown in Table 1 and Figures 10 and 12. In addition, regarding the phase shift layer 20 of each example and each comparative example, based on the measurement results of the refractive index, the film thickness that causes a 180° phase shift at each of three wavelengths (365 nm, 405 nm, 436 nm) was calculated. , the transmittance of the phase shift layer 20 under this film thickness is calculated through simulation. The results are shown in Table 1 and Figures 7 and 8. The simulation was performed using the simulation software "TFCalc". Based on the measurement results of the refractive index and extinction coefficient of i-ray (365 nm) obtained by ellipsometry, three wavelengths (365 nm, 405 nm, 436 nm) were used. The film thickness at which 180° phase shift occurs at each wavelength is calculated, and the transmittance of the phase shift layer 20 at this film thickness is calculated. Here, the transmittance also takes into account the external transmittance of reflection.

[Manufacture of phase shift mask 300] The pattern 50 was formed in the phase shift layer 20 of each embodiment and each comparative example, and the phase shift mask 300 shown in FIG. 3 was produced. First, a DC magnetron sputtering device was used, and a Cr target was used as the sputtering target. Reactive sputtering was performed while introducing Ar-N ₂ mixed gas. Then, reactive sputtering was performed while introducing Ar-O ₂ mixed gas. shoot. Thereby, the etching mask layer 30 composed of the chromium nitride layer 31 and the chromium oxide layer 32 is formed on the phase shift mask base plate 100, and the phase shift mask base plate 200 is manufactured (FIG. 2). The film is formed so that the thickness of the etching mask layer 30 is within the range of 90±7 nm (thickness of the chromium nitride layer 31:thickness of the chromium oxide layer 32=7:3). Next, a positive ultraviolet photoresist (GRX-M237 manufactured by Nagase Chemical Industry) is coated on the phase shift mask base plate 200 by spin coating to form the photoresist layer 40 ( FIG. 4(A) ). The thickness of the photoresist layer 40 is 660 nm.

The photoresist layer 40 is exposed using a mask aligner using a high-pressure mercury lamp (PLA-501 manufactured by CANON) and using a light-shielding mask formed with openings corresponding to the pattern 50 . Thereby, the portion of the photoresist layer 40 corresponding to the pattern 50 is exposed. Next, the exposed phase shift mask plate 200 is immersed in an organic alkaline developer (1.83% tetramethylammonium hydroxide manufactured by Tama Chemical Industry). Thereby, the photosensitive portion of the photoresist layer 40 is dissolved and removed, and an opening corresponding to the pattern 50 is formed ( FIG. 4(B) ).

Next, the photoresist layer 40 formed with the opening corresponding to the pattern 50 is used as a mask, and the etching mask layer 30 is wet-etched using an etching solution containing cerium ammonium nitrate and nitric acid (PureEtchCR101 manufactured by Hayashi Junyaku Co., Ltd.). The etching solution temperature is 23±3°C and the etching time is 80 sec. Thereby, the exposed portion of the etching mask layer 30 that is not covered by the photoresist layer 40 is removed ( FIG. 4(C) ).

Next, using the photoresist layer 40 and the etching mask layer 30 formed with the openings corresponding to the pattern 50 as masks, the phase shift layer 20 is etched using an etching solution containing ammonium fluoride (ADEKA CHELUMICA WGM-155). Wet etching. The temperature of the etching solution is 23±3°C, and 20% over etching is performed to remove the exposed phase shift layer 20 evenly without leaving any residue. Here, 20% over-etching means that etching is performed at a time of 120% with respect to the reference time, using the time until the phase shift film 20 can be penetrated as the reference time. Thereby, the pattern 50 is formed in the phase shift layer 20 (FIG. 4(D)).

Finally, the photoresist layer 40 and the etching mask layer 30 are peeled off. Through the above steps, the phase shift mask 300 shown in Figure 4(E) is obtained from the phase shift mask base plate.

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative example 1 Comparative example 2 phase shift layer htK htK htK htK htK MoSi MoSi Transmittance (wavelength 365 nm) 5.24% 10.37% 16.37% 24.55% 35.65% 4.76% 10.35% Transmittance (wavelength 405 nm) 8.00% 15.74% 24.55% 36.55% 48.79% 7.09% 14.19% Transmittance (wavelength 436 nm) 10.48% 20.31% 31.71% 47.76% 62.46% 9.03% 17.23% Nitrogen introduction ratio of sputtering gas: N ₂ / (Ar+N ₂ ) twenty four% 26% 28% 30% 60% 30% 36% Time to 20% over etching (seconds) 113 188 377 819 466 1388 3265 Etching speed (nm/second) 0.86 0.52 0.26 0.12 0.23 0.08 0.04 Film thickness at 180° phase (nm) 98.1 97.2 98.4 100.0 107.2 111.6 121.0 Refractive index: n 2.86021 2.87767 2.85378 2.82498 2.70217 2.63603 2.50809 Extinction coefficient: k 0.77098 0.56037 0.36058 0.23134 0.16707 0.76845 0.52258 Tilt angle (°) 60.1 66.2 69.0 67.2 60.4 66.0 61.4

As shown in Table 1 and Figure 12, even if the nitrogen introduction ratio is the same, the extinction coefficients of the ZrSi layers in Examples 1 to 5 are lower than the extinction coefficients of the MoSi layers in Comparative Examples 1 and 2. There is a relationship that the larger the value of the extinction coefficient, the smaller the transmittance. Therefore, as shown in Table 1, Figure 7, and Figure 8, if the nitrogen introduction ratio of the ZrSi phase shift layers in Examples 1 to 5 and the MoSi phase shift layer in Comparative Examples 1 and 2 is increased, all phase shift layers The penetration rate (365 nm) becomes larger. In addition, even if the nitrogen introduction ratio is the same, the transmittance (365 nm) of the ZrSi phase shift layer in Example 4 is greater than that of the MoSi phase shift layer in Comparative Example 1.

As shown in Table 1 and Figure 9, the etching speed of the ZrSi phase shift layer in Examples 1 to 5 is faster than the etching speed of the MoSi phase shift layer in Comparative Examples 1 and 2. In addition, since the refractive index of the ZrSi phase shift layer in Examples 1 to 5 is higher than the refractive index of the MoSi phase shift layer in Comparative Examples 1 and 2, the ZrSi phase shift layer in Examples 1 to 5 is at phase 180 ° will be thinner than the film thickness of the MoSi phase shift layer in Comparative Examples 1 and 2.

During the manufacturing process of the phase shift mask 300, the cross-sections of the patterns 50 formed in each embodiment and each comparative example were observed. The cross-sectional observation was performed in the state before removing the etching mask layer 30 and the photoresist layer 40 (the state shown in FIG. 4(D) ). 13 shows SEM images of cross-sections orthogonal to the substrate surface 10a of each embodiment and each comparative example. According to FIG. 13 , for each embodiment and each comparative example, the inclination angle θ of the side surface 21 of the phase shift layer 20 from the substrate surface 10 a was measured. The results are shown in Table 1 and Figure 13.

It can be seen from the SEM images in Table 1 and Figure 13 that the tilt angle of the ZrSi layer in Examples 1 to 5 is larger than the tilt angle of the MoSi layer in Comparative Examples 1 and 2. Furthermore, it can be seen that in Comparative Example 2, the substrate 10 was also etched due to the long etching time. Furthermore, as shown in Table 1 and Figure 11, even if the nitrogen introduction ratio is the same, the inclination angle of the ZrSi layer in Example 4 is larger than the inclination angle of the MoSi layer in Comparative Example 1.

In addition, the tilt angle of the phase shift layer 20 of this embodiment after 20% over-etching is performed under the conditions of an etching solution containing ammonium fluoride (ADEKA CHELUMICA WGM-155 manufactured by ADEKA, the temperature of the etching solution is 23±3°C) Preferably, it is above 55° and below 90°. A preferable lower limit is 58°, more preferably 60°, and still more preferably 65°.

During the manufacturing process of the phase shift mask 300, the cross-sections of the patterns 50 formed in the ZrSiN phase shift layer 20 formed into 4, 6, and 8 layers were observed. In addition, the nitrogen introduction ratio during film formation of the ZrSiN film was the same as in Example 3, which was 28%. The cross-sectional observation was performed in the state before removing the etching mask layer 30 and the photoresist layer 40 (the state shown in FIG. 4(D) ). FIG. 14 shows an SEM image of a cross-section orthogonal to the substrate surface 10 a and a phase shift mask based on the phase shift layer 20 having (A) 4 layers, (B) 6 layers, and (C) 8 layers. SEM image depiction sketch. In addition, in FIG. 14(B) , the film was formed under the same conditions as Example 3, but the etching time was longer than that of Example 3. It can be confirmed from the side surface 21 of the phase shift layer 20 in FIGS. 14(A) to 14(C) that the phase shift layer 20 is a built-up layer. [Industrial availability]

Compared with the MoSi phase shift mask substrate, the phase shift mask substrate of this embodiment has a shorter etching time and a higher refractive index, so it can achieve a thinner film thickness when the phase shift amount is 180°. This can be achieved by The amount of side etching is reduced and pattern accuracy is improved.

10:Substrate 20: Phase shift layer 30: Etch mask layer 31:Chromium nitride layer 32:Chromium oxide layer 40: Photoresist layer 50: Pattern 100,200: Phase shift mask base plate 300: Phase shift mask 500: Exposure device LS: light source 502: Illumination optical system 504: Projection optical system 503: Masking table 505:Substrate table 600: Film forming device P:Substrate tray Q: solid arrow R: dotted arrow 601: Move into chamber 602: 1st sputtering chamber 603: Buffer chamber 604: 2nd sputtering chamber 605: Move out of chamber 606: The first target material (ZrSi) 607: 2nd target (Cr) 608: 1st gas inlet 609: Second gas inlet

[Fig. 1] is a schematic cross-sectional view showing an example of a phase shift mask chassis according to the embodiment. [Fig. 2] is a schematic cross-sectional view showing another example of the phase shift mask chassis according to the embodiment. [Fig. 3] is a schematic cross-sectional view of the phase shift mask according to the embodiment. [Fig. 4] (A) to (E) are diagrams illustrating the manufacturing method of the phase shift mask according to the embodiment. [Fig. 5] is a schematic diagram of an exposure device used in the exposure method of the embodiment. FIG. 6 is a schematic diagram showing an example of a manufacturing apparatus of a phase shift mask substrate according to the embodiment. [Fig. 7] is a graph showing the transmittance of the ZrSi phase shift mask base plate in the Example at a film thickness that causes a 180° phase shift of light with a wavelength of 300 to 600 nm. [Fig. 8] is a graph showing the transmittance of the MoSi phase shift mask base plate in the comparative example at a film thickness that causes a 180° phase shift of light with a wavelength of 300 to 600 nm. [Figure 9] shows the sputter gas introduction rate (Sputter gas ratio: N ₂ / (Ar + N ₂ )) and etching rate of the ZrSi phase shift mask substrate in the example and the MoSi phase shift mask substrate in the comparative example. (Etching Rate) relationship curve graph. [Figure 10] shows the sputter gas introduction rate (Sputter gas ratio: N ₂ / (Ar + N ₂ )) and the refractive index of the ZrSi phase shift mask base plate in the example and the MoSi phase shift mask base plate in the comparative example. (Refractive index: n). [Figure 11] shows the sputter gas introduction rate (Sputter gas ratio: N ₂ / (Ar + N ₂ )) and the tilt angle of the ZrSi phase shift mask base plate in the example and the MoSi phase shift mask base plate in the comparative example. (Cross-Section Tilt Angle) relationship graph. [Figure 12] shows the sputter gas introduction rate (Sputter gas ratio: N ₂ / (Ar + N ₂ )) and extinction coefficient of the ZrSi phase shift mask base plate in the example and the MoSi phase shift mask base plate in the comparative example. (Extinction coefficient: k) relationship curve graph. [Fig. 13] It is an SEM image of the ZrSi phase shift mask substrate in the Example and the SEM image of the MoSi phase shift mask substrate in the Comparative Example. [Figure 14] It is an SEM image of a ZrSi phase shift mask substrate composed of (A) 4 layers, (B) 6 layers, and (C) 8 layers, and a sketch based on the SEM image.

Claims (10)

A phase shift mask base plate having: substrate; and The first layer is formed on the above-mentioned substrate; The above-mentioned first layer contains zirconium (Zr), silicon (Si) and nitrogen (N), and The above-mentioned first layer has a transmittance of 4% to 40% at a film thickness that causes a 180° phase shift of light with a wavelength of 365 nm. A phase shift mask base plate having: substrate; and The first layer is formed on the above-mentioned substrate; The above-mentioned first layer is a laminate of four or more layers of metal silicide nitride containing zirconium (Zr) and silicon (Si), and The above-mentioned first layer has a transmittance of 4% to 40% at a film thickness that causes a 180° phase shift of light with a wavelength of 365 nm. A phase shift mask base plate having: substrate; and The first layer is formed on the above-mentioned substrate; The above-mentioned first layer is a laminate of four or more layers of metal silicide nitride containing zirconium (Zr) and silicon (Si), and The inclination angle of the above-mentioned first layer is not less than 55° and not more than 90°. The phase shift mask substrate according to any one of claims 1 to 3, wherein the transmittance of the first layer at a film thickness that causes a 180° phase shift of light with a wavelength of 365 nm is 4% or more and 40% or less. . The phase shift mask substrate according to any one of claims 1 to 4, wherein the above-mentioned tilt angle is that the etching liquid is ADEKA CHELUMICA WGM-155 and the first layer is treated under the condition that the temperature of the etching liquid is 23±3°C. Angle when performing 20% over-etching. For example, the phase shift mask substrate of claim 1 or 2, wherein the film thickness of the above-mentioned first layer that causes a 180° phase shift of light with a wavelength of 365 nm is the film thickness calculated from the following formula (1): d=365/(2(n-1)) (d: film thickness, n: refractive index). A phase shift mask, which has a required pattern formed in the phase shift mask base plate of any one of claims 1 to 6. A method of manufacturing a phase shift mask base plate, It has a film forming step of forming a first layer on a substrate, In the above film forming step, a nitride layer of a metal silicide containing zirconium and silicon is formed on the above substrate four or more times to form the first layer. As claimed in claim 8, the method for manufacturing a phase shift mask substrate is characterized in that, in the film forming step, the nitride layer of the metal silicon compound is formed on the substrate more than six times. A method for manufacturing a phase shift mask, which is the method for manufacturing a phase shift mask substrate according to claim 8 or 9 and further includes a pattern forming step for forming a desired pattern.