KR20190126725A - EUV lithography mask, and fabricating method of the same - Google Patents

Abstract

The present invention relates to a mask for EUV lithography. The mask for EUV lithography comprises: a substrate; a reflective structure disposed on the substrate and having a plurality of unit films stacked thereon; and an absorbent structure including a first absorbing layer disposed on the reflective structure and having a first width and a second absorbent layer stacked on the first absorbing layer and having a second width narrower than the first width, wherein the phase difference between zeroth order diffracted light and first order diffracted light of the light incident toward the absorbent structure may be controlled according to the width difference between the first absorbing layer and the second absorbing layer.

Description

EUV lithography mask and manufacturing method thereof {EUV lithography mask, and fabricating method of the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mask for EUV lithography and a method for manufacturing the same, and more particularly, to a mask for EUV lithography including an absorbent structure in which a first absorption layer and a second absorption layer are laminated.

Lithography is a process directly connected to the miniaturization and integration of semiconductor devices. IC chips with 38nm linewidth were mass produced in 2008, and devices with 30nm linewidth have been mass produced since 2010. To produce a semiconductor device having such a fine line width, there is an extreme ultraviolet (EUV) exposure technology.

The extreme ultraviolet exposure process is the next generation semiconductor exposure technology that is most likely to be applied to the mass production process of memory semiconductors below 20 nm after the 193 nm immersion double patterning technology. Since the extreme ultraviolet exposure process uses light having a wavelength of 13.5 nm, a reflective mask is used instead of a transmissive mask. In the case of the conventional mask for the extreme ultraviolet exposure process, in order to maximize the contrast ratio between the reflection area and the absorption area An absorber is used for the Ta (tantalum) series having a thickness of 70 nm.

However, in the case of implementing a 10 nm-class fine pattern using a conventional mask, it is difficult to form a pattern on the wafer due to the lack of processing capability of the exposure process due to the thick absorbent structure. The effect that the mask imaging performance is reduced due to the absorber structure is called a mask three-dimensional effect, and various studies have been continuously conducted to solve this problem.

One technical problem to be solved by the present invention is to provide a mask for EUV lithography and a method of manufacturing the same, the mask three-dimensional effect is reduced.

Another technical problem to be solved by the present invention is to provide a mask for EUV lithography with improved mask imaging performance and a method of manufacturing the same.

Another technical problem to be solved by the present invention is to provide a mask for EUV lithography in which the phase difference between the zeroth order diffraction light and the first order diffraction light is controlled, and a method of manufacturing the same.

The technical problem to be solved by the present invention is not limited to the above.

In order to solve the above technical problem, the present invention provides a mask for EUV lithography.

According to an embodiment, the EUV lithography mask may include a substrate, a reflective structure disposed on the substrate, and a plurality of unit layers stacked thereon, and disposed on the reflective structure, and having a first width. And an absorbent structure including a first absorbent layer having a second absorbent layer, and a second absorbent layer stacked on the first absorbent layer and having a second width narrower than the first width, wherein the first absorbent layer and the second absorbent layer According to the width difference, the phase difference between the zeroth order diffracted light and the first order diffracted light of the light incident toward the absorbing structure may be controlled.

According to an embodiment, the difference in width between the first absorbing layer and the second absorbing layer may include more than 10 nm and less than 20 nm.

According to an embodiment, a distance between one end of the first absorbing layer adjacent to each other and one end of the second absorbing layer disposed on the first absorbing layer, or the other end of the first absorbing layer adjacent to each other and the first absorbing layer The distance between the other ends of the second absorbing layer disposed on the layer may include more than 5 nm and less than 10 nm.

According to an embodiment, the phase difference between the zeroth order diffracted light and the first order diffracted light may include 180 °.

According to an embodiment, the thickness of the absorbent structure may be controlled according to a refractive index and an extinction coefficient of the absorbent structure.

According to an embodiment, when the refractive index of the absorbent structure is 0.85 to 0.95 and the extinction coefficient of the absorbent structure is 0.3 to 0.7, the thickness of the absorbent structure may include 10 nm to 60 nm.

According to an embodiment, the mask for EUV lithography may further include an etch stop layer disposed between the first absorbing layer and the second absorbing layer.

According to an embodiment, the capping layer may further include a capping layer disposed between the reflective structure and the absorbent structure.

According to an embodiment, the first absorbing layer and the second absorbing layer may include different materials.

According to an embodiment, the first absorbing layer and the second absorbing layer may include the same material.

In order to solve the above technical problem, the present invention provides a method of manufacturing a mask for EUV lithography.

According to an embodiment of the present disclosure, a method of manufacturing a mask for EUV lithography may include preparing a substrate, stacking a plurality of unit layers on the substrate, forming a reflective structure, and forming a first width on the reflective structure. and an absorbent structure including a first absorbent layer having a width) and a second absorbent layer stacked on the first absorbent layer and having a second width narrower than the first width.

According to an embodiment, the forming of the absorbent structure may include preliminary stacking of the first absorbent layer, an etch stop layer, the second absorbent layer, and a hard mask layer on the reflective structure. Forming an absorbent structure, forming a masking layer on the reflective structure, the masking layer covering the preliminary absorbent structure, etching the masking layer so that the masking layer has a narrower width than the preliminary absorbent structure; Forming a masking layer pattern on a structure, etching the hard mask layer using the masking layer pattern as a mask, and removing the masking layer pattern, using the etched hard mask layer, the preliminary Etching the second absorbing layer such that the etch stop layer of the absorbent structure is exposed, and removing the etched hard mask layer. It can hamhal.

The forming of the absorbing structure may include controlling the phase difference between the zeroth order diffracted light and the first order diffracted light of the light incident toward the absorbent structure by controlling the width of the second absorbing layer.

In example embodiments, in the forming of the absorbent structure, for the etching source provided to the preliminary absorbent structure, the etch stop layer has an etch selectivity compared to the first absorbing layer and the second absorbing layer. It may include.

A mask for EUV lithography according to an embodiment of the present invention is disposed on a substrate, a reflective structure on which the plurality of unit layers are stacked, and a reflective structure on the reflective structure, and having a first width. And an absorbent structure including a first absorbent layer having a second absorbent layer, and a second absorbent layer stacked on the first absorbent layer and having a second width narrower than the first width, wherein the first absorbent layer and the second absorbent layer According to the width difference, the phase difference between the zeroth order diffracted light and the first order diffracted light of the light incident toward the absorbing structure may be controlled. Accordingly, the imaging performance of the mask for EUV lithography can be improved.

1 is a view showing a mask for EUV lithography according to an embodiment of the present invention.
2 is a view showing in detail the absorbent structure included in the mask for EUV lithography according to an embodiment of the present invention.
3 is a diagram illustrating an EUV lithography process through a mask for EUV lithography according to an embodiment of the present invention.
4 is a flowchart illustrating a method of manufacturing a mask for EUV lithography according to an embodiment of the present invention.
5 and 6 illustrate a step of preparing a first preliminary absorption structure in a method of manufacturing a mask for EUV lithography according to an embodiment of the present invention.
FIG. 7 is a view showing a second preliminary absorption structure preparing step of a method of manufacturing a mask for EUV lithography according to an embodiment of the present invention.
8 to 13 are views illustrating an absorbent structure manufacturing step in a method of manufacturing a mask for EUV lithography according to an embodiment of the present invention.
14 and 15 are graphs showing factors influencing the imaging performance of a mask for EUV lithography according to an embodiment of the present invention.
16 and 17 are graphs showing imaging performance according to the structure of an absorbing structure included in a mask for EUV lithography according to an embodiment of the present invention.
18 and 19 are tables showing imaging performance according to the structure of an absorbing structure included in a mask for EUV lithography according to an embodiment of the present invention.
20 to 23 are graphs showing characteristic changes according to refractive index and extinction coefficient of an absorbent structure included in an EUV lithography mask according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical idea of the present invention is not limited to the exemplary embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed contents are thorough and complete, and that the spirit of the present invention can be sufficiently delivered to those skilled in the art.

In the present specification, when a component is mentioned to be on another component, it means that it may be formed directly on the other component or a third component may be interposed therebetween. In addition, in the drawings, the thicknesses of films and regions are exaggerated for effective explanation of technical contents.

In addition, in various embodiments of the present specification, terms such as first, second, and third are used to describe various components, but these components should not be limited by these terms. These terms are only used to distinguish one component from another. Thus, what is referred to as a first component in one embodiment may be referred to as a second component in another embodiment. Each embodiment described and illustrated herein also includes its complementary embodiment. In addition, the term 'and / or' is used herein to include at least one of the components listed before and after.

In the specification, the singular encompasses the plural unless the context clearly indicates otherwise. In addition, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, element, or combination thereof described in the specification, and one or more other features or numbers, steps, configurations It should not be understood to exclude the possibility of the presence or the addition of elements or combinations thereof. In addition, the term "connection" is used herein to mean both indirectly connecting a plurality of components, and directly connecting.

In addition, in the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

1 is a view showing a mask for EUV lithography according to an embodiment of the present invention, Figure 2 is a view showing in detail the absorbent structure included in the mask for EUV lithography according to an embodiment of the present invention, Figure 3 is a present invention A diagram illustrating an EUV lithography process through a mask for EUV lithography according to an embodiment of the invention.

1 to 3, a mask 10 for extreme ultraviolet (EUV) lithography according to an embodiment of the present invention may include a substrate 100, a reflective structure 200, a capping film 300, and an absorbent structure ( AS). Hereinafter, each structure is explained concretely.

According to an embodiment, the substrate 100 may include silicon oxide. For example, the substrate 100 may include SiO ₂ . In addition, the substrate 100 may further include titanium oxide in addition to silicon oxide. For example, the substrate 100 may include SiO ₂ doped with TiO ₂ . In this case, due to the low thermal expansion of TiO ₂ , it is possible to minimize image distortion due to mask heating in the EUV lithography process.

The reflective structure 200 may be disposed on the substrate 100. According to an embodiment, the reflective structure 200 may include a plurality of unit layers. The unit layer may include a first material layer 210 and a second material layer 220 stacked on the first material layer 210. Accordingly, the reflective structure 200 may be stacked alternately and repeatedly the first material film 210 and the second material film 220. For example, the first material layer 210 may include molybdenum (Mo). For example, the second material layer 220 may include silicon (Si).

The capping layer 300 may be disposed on the reflective structure 200. In detail, the capping layer 300 may be disposed on a unit layer disposed on the top of the plurality of unit layers. The capping layer 300 may prevent oxidation of the reflective structure 200. For example, the capping layer 300 may include any one of ruthenium (Ru), niobium oxide (NbO), ruthenium oxide (RuO), and titanium oxide (TiO).

The absorbent structure AS may be disposed on the capping layer 300. According to an embodiment, the absorbent structure AS may include a first absorbing layer 410, an etch stop layer 420, and a second absorbing layer 430. The first absorbing layer 410, the etch stop layer 420, and the second absorbing layer 430 may be sequentially stacked. That is, the etch stop layer 420 may be disposed between the first absorbing layer 410 and the second absorbing layer 430. The etch stop layer 420 is described in more detail in a method of manufacturing a mask for EUV lithography, which will be described later.

According to an embodiment, the first absorbing layer 410 and the second absorbing layer 430 may include the same material. According to another embodiment, the first absorbing layer 410 and the second absorbing layer 430 may include different materials. For example, the first and second absorbent layers 410 and 430 may include chromium, chromium oxide, chromium nitride, titanium, titanium oxide, titanium nitride, tantalum, tantalum oxide, tantalum nitride, tantalum oxynitride, tantalum boron oxide, Tantalum boron nitride, tantalum boron oxynitride, aluminum, aluminum oxide, silver, silver oxide, palladium, copper, ruthenium, molybdenum, and platinum.

The absorption structure AS may control a phase difference between the zero-order diffraction light DL ₀ and the first-order diffraction light DL ₁ of the light incident toward the absorption structure AS. Specifically, the phase difference between the zeroth order diffracted light DL ₀ and the first order diffracted light DL ₁ may be controlled to be substantially 180 °. Accordingly, the imaging performance of the mask 10 for EUV lithography can be improved. That is, as the phase difference between the zeroth order diffraction light DL ₀ and the first order diffraction light DL ₁ approaches 180 °, the imaging performance of the mask 10 for EUV lithography may be improved.

Specifically, in the general EUV lithography process, as shown in FIG. 3, the light incident on the mask 10 for EUV lithography includes the zero-order diffraction light DL ₀ , the first-order diffraction light DL ₁ , and − Diffracted with the primary diffracted light DL ₂ , the diffracted light may be collected in the lens 20. Thereafter, diffracted light collected by the lens 20 is provided on the wafer 30 so that the image of the mask 10 can be scanned on the wafer 30.

In the above-described process, when the phase difference between the zeroth order diffracted light DL ₀ and the first order diffracted light DL ₁ is 180 °, or close to 180 °, the zeroth order diffracted light DL ₀ and the Unnecessary lights of the first order diffracted light DL ₁ may be removed by destructive interference. Accordingly, the imaging performance of the mask 10 for EUV lithography can be improved.

The phase difference between the zeroth order diffracted light DL ₀ and the first order diffracted light DL ₁ may be controlled according to the structure of the absorbing structure AS. According to an embodiment, the zeroth-order diffracted light DL ₀ and the first-order diffraction are generated according to a difference in width between the first and second absorbing layers 410 and 430 included in the absorbing structure AS. The phase difference between the lights DL ₁ may be controlled.

In detail, the first absorbing layer 410 may have a first width W ₁ . In contrast, the second absorption layer 430 may have a second width W ₂ . The second width W ₂ may be smaller than the first width W ₁ . For example, the width difference between the first absorbing layer 410 and the second absorbing layer 430 may be greater than 10 nm and less than 20 nm. In addition, the distance d ₁ between one end of the first absorbing layer 410 and one end of the second absorbing layer 430 may be greater than 5 nm and less than 10 nm. In addition, the distance d ₂ between the other end of the first absorbing layer 410 and the other end of the second absorbing layer 430 may be greater than 5 nm and less than 10 nm. In this case, the phase difference between the zeroth order diffracted light DL ₀ and the first order diffracted light DL ₁ may be controlled to be close to 180 °.

According to an embodiment, the thickness t of the absorbent structure AS may be controlled according to the refractive index and extinction coefficient of the absorbent structure AS. For example, when the refractive index of the absorbent structure is 0.85 to 0.95 and the extinction coefficient of the absorbent structure is 0.3 to 0.7, the thickness of the absorbent structure may be controlled to 10 nm to 60 nm. Specifically, when the refractive index of the absorbent structure is 0.85 and the extinction coefficient is 0.3 to 0.7, the thickness of the absorbent structure may be controlled to 10 nm to 25 nm. In addition, when the refractive index of the absorbent structure is 0.90 and the extinction coefficient is 0.3 to 0.7, the thickness of the absorbent structure may be controlled to 10 nm to 30 nm. In addition, when the refractive index of the absorbent structure is 0.95 and the extinction coefficient is 0.3 to 0.7, the thickness of the absorbent structure may be controlled to 10 nm to 60 nm.

As described above, when the thickness t of the absorbent structure AS is controlled according to the refractive index and extinction coefficient of the absorbent structure AS, in the image performance of the mask 10 for EUV lithography, The phase difference between the zeroth order diffracted light DL ₀ and the first order diffracted light DL ₁ may have a large influence.

That is, when the refractive index of the absorbent structure is 0.85 to 0.95, the extinction coefficient is 0.3 to 0.7, and the thickness is 10 nm to 60 nm, the zero-order diffraction light DL ₀ and the first-order diffraction light DL ₁ By controlling the phase difference between 180 °), the image performance improvement efficiency can be further increased.

A mask for EUV lithography according to an embodiment of the present invention, the reflective structure 200 is disposed on the substrate 100, the substrate 100, a plurality of unit layers are stacked, and the reflection A first width layer 410 disposed on the structure, having a first width W ₁ , stacked on the first absorption layer 410, and having a second width narrower than the first width W ₁ ( W ₂ ) including the absorbent structure (AS) including the second absorbent layer 430 having a width difference between the first absorbent layer 410 and the second absorbent layer 430. The phase difference between the zeroth order diffracted light DL ₀ and the first order diffracted light DL ₁ of the light incident toward AS may be controlled. Accordingly, the imaging performance of the mask for EUV lithography can be improved.

In the above, a mask for EUV lithography according to an embodiment of the present invention has been described. Hereinafter, a method of manufacturing a mask for EUV lithography according to an embodiment of the present invention will be described with reference to FIGS. 4 to 13. In addition, in describing the method for manufacturing a mask for EUV lithography according to the embodiment, the mask for EUV lithography according to the embodiment described with reference to FIGS. 1 to 3 will be described as an example.

4 is a flowchart illustrating a method of manufacturing a mask for EUV lithography according to an embodiment of the present invention, and FIGS. 5 and 6 are a first preliminary absorption structure of a method of manufacturing a mask for EUV lithography according to an embodiment of the present invention. FIG. 7 is a view showing a second preliminary absorption structure preparing step of the method for manufacturing a mask for EUV lithography according to an embodiment of the present invention, Figures 8 to 13 are EUV according to an embodiment of the present invention It is a figure which shows the absorption structure manufacturing step among the manufacturing methods of the mask for lithography.

Referring to FIG. 4, a method of manufacturing a mask for EUV lithography according to an embodiment of the present invention may include a substrate preparation step S100, a reflective structure forming step S200, and an absorbing structure forming step S300. . Hereinafter, each step will be described in more detail.

Referring to FIG. 5, the reflective structure 200 and the capping layer 300 may be sequentially formed on the substrate 100. The substrate 100, the reflective structure 200, and the capping layer 300 may be formed of the substrate 10 included in the EUV lithography mask 10 according to the embodiment described with reference to FIGS. 1 to 3. 100), the reflective structure 200, and the capping layer 300 may be the same. Accordingly, detailed description is omitted.

6 and 7, the first preliminary absorption structure PAS ₁ may be formed on the capping layer 300. The first preliminary absorption structure PAS ₁ may include a first absorption layer 410, an etch stop layer 420, a second absorption layer 430, and a hard mask layer 440. As illustrated in FIG. 6, the first absorbing layer 410, the etch stop layer 420, the second absorbing layer 430, and the hard mask layer 440 are sequentially formed on the capping layer 300. It can be formed to be stacked.

In example embodiments, the etch stop layer 420 may have an etching selectivity compared to the first absorbing layer 410 and the second absorbing layer 430. That is, in the step of forming an absorbent structure, which will be described later, the first absorbing layer 410 and the second absorbing layer 430 may be etched by reacting with an etching source. On the other hand, the etch stop layer 420 may not react with the etch source and may not be etched substantially. Accordingly, in the absorbing structure forming step to be described later, the second absorbing layer 430 disposed on the upper surface of the etch stop layer 420 is etched, whereas the second absorbing layer 430 is disposed on the lower surface of the etch stop layer 420. The first absorbing layer 410 may not be etched. For example, the etch stop layer 420 may include SiO 2 or SiO _N.

A resist layer 500 may be formed on the first preliminary absorption structure PAS ₁ . After the resist layer 500 is formed, at least one region of the resist layer 500 and the first preliminary absorption structure PAS ₁ may be etched. For example, the first preliminary absorption structure PAS ₁ may be etched through the E-beam.

After the first preliminary absorption structure PAS1 is etched, the resist layer 500 may be removed. Accordingly, as illustrated in FIG. 7, the second preliminary absorption structure PAS ₂ may be formed.

8 to 13, a masking layer 600 may be formed to cover the second preliminary absorption structure PAS ₂ . At least one region of the masking layer 600 may be etched by an e-beam. In detail, the masking layer 600 may be etched to have a narrower width than the second preliminary absorption structure PAS2. Accordingly, as shown in FIG. 9, a masking layer pattern 600 may be formed on the second preliminary absorption structure PAS ₂ . That is, all of the remaining masking layers 600 except for at least one region of the masking layer 600 disposed on the hard mask layer 440 may be removed.

After the masking layer pattern 600 is formed, the hard mask layer 440 and the second absorbing layer 430 may be etched. According to an embodiment, the hard mask layer 440 may be etched using the masking layer pattern 600 as a mask. After the hard mask layer 400 is etched, the masking layer pattern 600 may be removed.

Subsequently, the second absorbing layer 430 may be etched using the etched hard mask layer 440 to expose the etch stop layer 420 of the second preliminary absorbing structure PAS ₂ . According to an embodiment, the second absorbing layer 430 may be etched by providing an etching source to the second preliminary absorption structure PAS ₂ . As described above, when an etching solution is provided to the second preliminary absorption structure PAS ₂ , the first absorption layer 410 may not be etched by the etch stop layer 420.

According to one embodiment, by controlling the width of the second absorbing layer 430, it is possible to control the phase difference between the zero-order diffraction light and the first-order diffraction light of the light incident toward the absorption structure to be described later. Specifically, the width of the second absorbing layer 430 may be controlled so that the difference between the widths of the first absorbing layer 410 and the second absorbing layer 430 is greater than 10 nm and less than 20 nm. In addition, the width of the second absorbing layer 430 may be controlled such that a distance between one end of the first absorbing layer 410 and one end of the second absorbing layer 430 is greater than 5 nm and less than 10 nm. . In addition, the width of the second absorbing layer 430 may be controlled such that a distance between the other end of the first absorbing layer 410 and the other end of the second absorbing layer 430 is greater than 5 nm and less than 10 nm. . In this case, the phase difference between the zeroth order diffracted light and the first order diffracted light is controlled to be close to 180 °, so that the imaging performance of the mask for EUV lithography can be improved. The related description may be the same as the method for improving image performance of the mask for EUV lithography described with reference to FIGS. 1 to 3. Accordingly, detailed description is omitted.

After the second absorbing layer 430 is etched, the etched hard mask layer 440 may be removed. Accordingly, a mask for EUV lithography according to the embodiment can be manufactured.

In the mask manufacturing method for EUV lithography according to an embodiment of the present invention, the first absorption layer 410, the etch stop layer 420, the second absorption layer 430, and the hard mask layer 440 sequentially The method may include preparing a stacked preliminary absorbing structure, and forming a width of the second absorbing layer 420 smaller than a width of the first absorbing layer 410 to manufacture the absorbing structure. Accordingly, a method of manufacturing a mask for EUV lithography with improved imaging performance can be provided.

In the above, a mask for EUV lithography and a method of manufacturing the same according to an embodiment of the present invention have been described. Hereinafter, specific experimental examples and characteristics evaluation results of the EUV lithography mask and its manufacturing method according to an embodiment of the present invention will be described.

14 and 15 are graphs showing factors influencing the imaging performance of a mask for EUV lithography according to an embodiment of the present invention.

Referring to FIG. 14, a mask for EUV lithography according to an embodiment including a SiO ₂ substrate, a Mo-Si reflective structure, a Ru capping film, and an absorbing structure is prepared. An absorbent structure included in the mask for EUV lithography according to the embodiment is composed of a single layer of Pt or Pd. After preparing a mask for EUV lithography according to the embodiment, the image contrast according to the ratio of the diffraction efficiency (Ratio of 0th / 1st order diffraction efficiency) %) Was measured and shown. Image contrast is an index indicating the imaging performance of a mask for EUV lithography. The higher the image contrast value, the higher the imaging performance.

As can be seen in FIG. 14, it can be seen that the image contras (%) values vary depending on the ratio of diffraction efficiency between the 0th diffracted light and the 1st diffracted light. That is, in improving the imaging performance of the mask for EUV lithography, it was confirmed that the ratio of diffraction efficiency between the 0th diffraction light and the first diffraction light does not affect.

Referring to FIG. 15, a mask for EUV lithography according to the embodiment described in FIG. 14 is prepared. Thereafter, the image contrast (%) according to the phase difference between the zeroth order diffracted light and the first order diffracted light of the light incident toward the mask was measured.

As can be seen in FIG. 15, it can be seen that the image contrast (%) value decreases as the phase difference between the 0th diffracted light and the first diffracted light increases from 180 °. In addition, as the phase difference between the 0th diffracted light and the 1st diffracted light approaches 180 °, it was confirmed that the image contrast (%) value increased. Accordingly, it can be seen that the mask for EUV lithography according to the embodiment can improve imaging performance by controlling the phase difference between the 0th diffraction light and the 1st diffraction light to about 180 °.

In addition to the results shown in FIGS. 14 and 15, the characteristics according to the structure of the absorbent structure are summarized in Table 1 below.

Absorbent Structure Structure Zero-order diffraction light intensity 1st diffraction light intensity Ratio (1 / 0th diffracted light) Zeroth order diffracted light phase 1st order diffracted light phase Phase difference
(0-1st diffraction light) Phase difference
(0-1st diffraction light)> 0 Pt_31nm 0.411736 0.403111 0.979052111 36.1476 -148.394 184.5416 184.5416 Pt_25nm 0.427012 0.410669 0.961727071 29.1226 -165.616 194.7386 194.7386 Pd_23nm 0.435231 0.437954 1.006256448 112.143 -95.8937 208.0367 208.0367 Pd_26nm 0.420736 0.421469 1.001742185 -67.5536 112.635 -180.189 179.8114 Pd_30nm 0.415264 0.416466 1.002894544 98.2155 -90.3112 188.5267 188.5267 Pd_32nm 0.41373 0.411754 0.995223938 -35.0579 156.754 -191.812 168.1881

16 and 17 are graphs showing imaging performance according to the structure of an absorbing structure included in a mask for EUV lithography according to an embodiment of the present invention.

Referring to FIG. 16, a mask for EUV lithography according to an embodiment including a SiO ₂ substrate, a Mo-Si reflective structure, a Ru capping film, and an absorbing structure is prepared. The absorbent structure included in the EUV lithography mask according to the embodiment has a structure in which a second absorbent layer is stacked on the first absorbent layer. In addition, the width of the first absorbing layer and the width of the second absorbing layer are prepared to be different from each other. Then, the phase difference between the 0th order diffracted light and the 1st order diffracted light according to the difference between the width of the first absorbing layer and the width of the second absorbing layer is measured and shown. Bias on layer 2 illustrated in FIG. 13 represents a distance between one end of the first absorption layer and one end of the second absorption layer.

As can be seen in FIG. 16, when the width of the first absorbing layer is narrower than the width of the second absorbing layer (Bias on layer 2 has a -value), the phase difference between the zeroth order diffracted light and the first order diffracted light is relatively high. It was confirmed that it appeared small. On the other hand, when the width of the second absorption layer is narrower than the width of the first absorption layer (Bias on layer 2 has a + value), it can be seen that the phase difference between the 0th diffraction light and the first diffraction light is relatively large. there was. In particular, it is confirmed that the phase difference between the 0th order diffracted light and the 1st order diffracted light gradually increases and then decreases based on a section in which the distance between one end of the first absorbing layer and one end of the second absorbing layer is 5 nm to 10 nm. Could.

Referring to FIG. 17, a mask for EUV lithography according to an embodiment including a SiO ₂ substrate, a Mo-Si reflective structure, a Ru capping film, and an absorbing structure is prepared. The absorbent structure included in the EUV lithography mask according to the embodiment has a structure in which a second absorbent layer is stacked on the first absorbent layer. In addition, the width of the first absorbing layer and the width of the second absorbing layer are prepared to be different from each other. Thereafter, the image contrast (%) of the mask according to the difference between the width of the first absorbing layer and the width of the second absorbing layer is measured and shown. Bias on layer 2 illustrated in FIG. 14 represents a distance between one end of the first absorption layer and one end of the second absorption layer.

As can be seen in FIG. 17, when the width of the first absorbing layer is narrower than the width of the second absorbing layer (Bias on layer 2 has a negative value), it can be seen that the image contrast value is relatively small. On the other hand, when the width of the second absorbing layer is narrower than the width of the first absorbing layer (when Bias on layer 2 has a + value), it was confirmed that the image contrast value is relatively large. In particular, it was confirmed that the image contrast value gradually increased and decreased from the interval of 5 nm to 10 nm between one end of the first absorbing layer and one end of the second absorbing layer.

As can be seen from FIGS. 16 and 17, it can be seen that the phase difference between the zero-order diffraction light and the first-order diffraction light of light incident toward the absorbing structure can be controlled according to the width difference between the first absorption layer and the second absorption layer. Could. In addition, it was found that the imaging performance of the mask may be improved according to the difference in width between the first absorbing layer and the second absorbing layer.

18 and 19 are tables showing imaging performance according to the structure of an absorbing structure included in a mask for EUV lithography according to an embodiment of the present invention.

Referring to FIG. 18, a mask for EUV lithography according to an embodiment including a SiO ₂ substrate, a Mo-Si reflective structure, a Ru capping film, and an absorbing structure is prepared. The absorbent structure included in the EUV lithography mask according to the embodiment has a structure in which a second absorbent layer is stacked on the first absorbent layer. The first absorbing layer or the second absorbing layer includes TaBN. The phase difference between the zeroth order diffraction light and the first order diffraction light is shown according to the refractive index and extinction coefficient of the absorbent structure included in the mask for EUV lithography according to the embodiment.

As can be seen from FIG. 18, when the first absorption layer or the second absorption layer contains TaBN, the refractive index is 0.9 to 0.92, and when the extinction coefficient is 0.06 or more, the phase difference between the 0th diffracted light and the first diffracted light is 180. It was confirmed that it is getting close to °.

Referring to FIG. 19, a mask for EUV lithography according to an embodiment including a SiO ₂ substrate, a Mo-Si reflective structure, a Ru capping film, and an absorbing structure is prepared. The absorbent structure included in the EUV lithography mask according to the embodiment has a structure in which a second absorbent layer is stacked on the first absorbent layer. The phase difference between the zeroth order diffracted light and the first order diffracted light is shown according to the thickness of the first absorbing layer (layer 1 thickness) and the thickness of the second absorbing layer (layer 2 thickness).

As can be seen in FIG. 19, when the sum of the thicknesses of the first absorbing layer and the second absorbing layer is 40 nm, 48 nm, 56 nm, 58 nm, 62 nm, 64 nm, and 70 nm, the zero-order diffracted light and the first-order It was confirmed that the phase difference between the diffracted lights approaches 180 °.

20 to 23 are graphs showing characteristic changes according to refractive index and extinction coefficient of an absorbent structure included in an EUV lithography mask according to an embodiment of the present invention.

Referring to FIG. 20, a mask for EUV lithography according to an embodiment including a SiO ₂ substrate, a Mo-Si reflective structure, a Ru capping layer, and an absorbing structure is prepared, and the refractive index n of the absorbing structure is 1, A mask having an extinction coefficient k of 0.03, a refractive index n of 1, a extinction coefficient k of 0.07, and a refractive index n of 1 and a extinction coefficient k of 0.07 are prepared. It was. Then, for each mask, the diffraction efficiency (Ratio of 1st / 0th diffraction efficiency) between the 0th order diffracted light and the 1st order diffracted light according to the thickness of the absorbent structure (Absorber thickness, nm) is measured to be shown in FIG. (Phase difference between 1st & 0th order, °) according to the thickness of the absorbing structure (Absorber thickness, nm) and the first-order diffracted light and the first-order diffracted light were measured in FIG. In FIG. 20, normalized image log slope (NILS) according to the thickness of the absorbent structure (Absorber thickness, nm) was measured and illustrated in FIG. 20C.

As can be seen from (a) to (c) of FIG. 20, when the refractive index n of the absorbent structure is 1, the phase difference between the 0th order diffracted light and the 1st order diffracted light substantially depends on the extinction coefficient k. It was confirmed that it appears constantly. Accordingly, when the refraction coefficient of the absorbing structure is 1, the phase difference between the zeroth order diffracted light and the first order diffracted light has a very small influence on the NILS value indicating the imaging performance, and between the zeroth order diffracted light and the first diffracted light. It can be seen that the phase difference of dominantly affects the NILS value.

Referring to FIG. 21, a mask for EUV lithography according to an embodiment including a SiO ₂ substrate, a Mo-Si reflective structure, a Ru capping film, and an absorbing structure is prepared, wherein the refractive index n of the absorbing structure is 0.95, A mask having an extinction coefficient k of 0.03, a refractive index n of 1, a extinction coefficient k of 0.07, and a refractive index n of 1 and a extinction coefficient k of 0.07 are prepared. It was. Then, for each mask, the diffraction efficiency between the 0th and 1st diffraction light according to the thickness of the absorbent structure (Absorber thickness, nm) is measured to measure the ratio of 1st / 0th diffraction efficiency of FIG. (Phase difference between 1st & 0th order, °) according to the thickness of the absorbing structure (Absorber thickness, nm) and the first-order diffracted light and the first-order diffracted light are measured in (b) of FIG. In FIG. 21, a normalized image log slope (NILS) according to an absorber thickness (nm) is measured and illustrated in FIG. 21C.

As can be seen from (a) to (c) of FIG. 21, when the refractive index n of the absorbent structure is 0.95, the diffraction efficiency between the 0th order diffracted light and the 1st order diffracted light according to the extinction coefficient k is substantially It could be confirmed that it appears as a constant. Accordingly, when the refractive index of the absorbing structure is 0.95, the diffraction efficiency between the zeroth diffraction light and the first diffraction light has a very small influence on the NILS value indicating the imaging performance, and the zeroth order diffraction light and the first diffraction light It can be seen that the phase difference between dominates the NILS value.

Referring to FIG. 22, a mask for EUV lithography according to an embodiment including a SiO ₂ substrate, a Mo-Si reflective structure, a Ru capping film, and an absorbing structure is prepared, wherein the refractive index n of the absorbing structure is 0.90, A mask having an extinction coefficient k of 0.03, a refractive index n of 1, a extinction coefficient k of 0.07, and a refractive index n of 1 and a extinction coefficient k of 0.07 are prepared. It was. Subsequently, for each mask, the diffraction efficiency between the zeroth order diffraction light and the first order diffraction light according to the thickness of the absorbent structure (Absorber thickness, nm) is measured, and FIG. ), And a phase difference between 1st & 0th order (°) according to the thickness of the absorbent structure (Absorber thickness, nm) and measured in (b) of FIG. As shown in FIG. 22C, a normalized image log slope (NILS) was measured according to an absorber thickness (nm).

As can be seen from (a) to (c) of FIG. 22, when the refractive index n of the absorbent structure is 0.95, the diffraction efficiency between the zeroth order diffracted light and the first order diffracted light according to the extinction coefficient k is substantially It could be confirmed that it appears as a constant. Accordingly, when the refractive index of the absorbing structure is 0.90, the diffraction efficiency between the zeroth diffraction light and the first diffraction light has a very small influence on the NILS value indicating the imaging performance, and the zeroth order diffraction light and the first diffraction light It can be seen that the phase difference between dominates the NILS value.

Referring to FIG. 23, a mask for EUV lithography according to an embodiment including a SiO ₂ substrate, a Mo-Si reflective structure, a Ru capping film, and an absorbing structure is prepared, and the refractive index n of the absorbing structure is 0.85, A mask having an extinction coefficient k of 0.03, a refractive index n of 1, a extinction coefficient k of 0.07, and a refractive index n of 1 and a extinction coefficient k of 0.07 are prepared. It was. Then, for each mask, the diffraction efficiency between the 0th and 1st diffraction light according to the thickness of the absorbent structure (Absorber thickness, nm) is measured to measure the ratio of 1st / 0th diffraction efficiency of FIG. ), And a phase difference between 1st & 0th order (°) according to the thickness of the absorbent structure (Absorber thickness, nm) and measured in (b) of FIG. As shown in FIG. 23C, a normalized image log slope (NILS) was measured according to an absorber thickness (nm).

As can be seen from (a) to (c) of FIG. 23, when the refractive index n of the absorbent structure is 0.85, the diffraction efficiency between the zeroth order diffracted light and the first order diffracted light according to the extinction coefficient k is substantially It could be confirmed that it appears as a constant. Accordingly, when the refractive index of the absorbent structure is 0.85, the diffraction efficiency between the zeroth diffraction light and the first diffraction light has a very small influence on the NILS value indicating the imaging performance, and the zeroth order diffraction light and the first diffraction light It can be seen that the phase difference between dominates the NILS value.

21 to 23, when the refractive indices of the absorbent structures are 0.95, 0.90, and 0.85, the effect of the phase difference between the zeroth order diffracted light and the first order diffracted light on the NILS value for each thickness section of the absorbent structure. It was confirmed that the degree is different. Specifically, as can be seen in Figure 21, when the refractive index of the absorbent structure is 0.95, it was confirmed that the phase difference predominantly affects the NILS value in the interval of 10 nm to 60 nm thickness of the absorbent structure. In addition, as can be seen in Figure 22, when the refractive index of the absorbent structure is 0.90, it was confirmed that the phase difference predominantly affects the NILS value in the interval of 10 nm to 30 nm thickness of the absorbent structure. In addition, as can be seen in Figure 23, when the refractive index of the absorbent structure is 0.85, it was confirmed that the phase difference predominantly affects the NILS value in the interval of 10 nm to 25 nm thickness of the absorbent structure.

As mentioned above, although this invention was demonstrated in detail using the preferable embodiment, the scope of the present invention is not limited to a specific embodiment, Comprising: It should be interpreted by the attached Claim. In addition, those skilled in the art should understand that many modifications and variations are possible without departing from the scope of the present invention.

10: mask for EUV lithography
20: lens
30: wafer
100: substrate
200: reflective structure
300: capping film
410: first absorbing layer
420: etch stop
430: second absorbing layer
440: hard mask layer
500: resist layer
600: masking layer

Claims (14)

Board;
A reflective structure disposed on the substrate and having a plurality of unit layers stacked thereon; And
An absorbent structure disposed on the reflective structure, the absorbent structure including a first absorbent layer having a first width, and a second absorbent layer stacked on the first absorbent layer and having a second width narrower than the first width; Including,
And a phase difference between zero-order diffraction light and first-order diffraction light of light incident toward the absorbing structure is controlled according to a difference in width between the first absorption layer and the second absorption layer.
According to claim 1,
A width difference between the first absorbing layer and the second absorbing layer is greater than 10 nm and less than 20 nm.
The method of claim 2,
A distance between one end of the first absorbent layer adjacent to each other and one end of the second absorbent layer disposed on the first absorbent layer, or the other end of the first absorbent layer adjacent to each other and the first disposed on the first absorbent layer 2 A mask for EUV lithography, wherein the distance between the other ends of the absorbing layers is greater than 5 nm and less than 10 nm.
According to claim 1,
And a phase difference between said zeroth order diffracted light and said first order diffracted light is 180 degrees.
According to claim 1,
And a thickness of the absorbent structure is controlled in accordance with a refractive index and an extinction coefficient of the absorbent structure.
The method of claim 5,
When the refractive index of the absorbent structure is 0.85 to 0.95, and the extinction coefficient of the absorbent structure is 0.3 to 0.7, the thickness of the absorbent structure is 10 nm to 60 nm comprising a mask for EUV lithography.
According to claim 1,
And a etch stop layer disposed between the first absorbing layer and the second absorbing layer.
According to claim 1,
And a capping layer disposed between the reflective structure and the absorbent structure.
According to claim 1,
And the first absorbing layer and the second absorbing layer comprise different materials.
According to claim 1,
And the first absorbing layer and the second absorbing layer comprise the same material as each other.
Preparing a substrate;
Stacking a plurality of unit films on the substrate to form a reflective structure; And
Forming an absorbent structure on the reflective structure, the first absorbent layer having a first width and a second absorbent layer laminated on the first absorbent layer and having a second width narrower than the first width; A method for manufacturing a mask for EUV lithography comprising the step.
The method of claim 11, wherein
Forming the absorbent structure,
Forming a preliminary absorbing structure in which the first absorbing layer, the etch stop layer, the second absorbing layer, and the hard mask layer are sequentially stacked on the reflective structure;
Forming a masking layer on the reflective structure, the masking layer covering the preliminary absorbing structure;
Etching the masking layer to form a masking layer pattern on the preliminary absorbent structure such that the masking layer has a narrower width than the preliminary absorbent structure;
Etching the hard mask layer by using the masking layer pattern as a mask and removing the masking layer pattern;
Etching the second absorbing layer using the etched hard mask layer to expose an etch stop layer of the preliminary absorbing structure; And
Removing the etched hard mask layer.
The method of claim 12,
Controlling the width of the second absorbing layer to control the phase difference between the zeroth order diffracted light and the first order diffracted light of the light incident toward the absorbent structure.
The method of claim 12,
In the step of forming the absorbent structure, for the etching source provided to the preliminary absorbent structure,
And the etch stop layer has an etch selectivity compared to the first absorbing layer and the second absorbing layer.

Images