CN115826348B - Mask plate and preparation method thereof - Google Patents

Abstract

The invention provides a mask plate and a preparation method thereof. At least two phase shift layers are arranged in the mask, and the phase shift layers are flexibly combined and matched to form various phase shift regions with different phase shift amounts, so that the requirements of different mask patterns on the phase shift amounts are met, the contrast ratio of patterns is improved, direct change of the phase shift amounts in ultra-large spans between adjacent regions is avoided, and the problem of 'ghost shadow' caused by the direct change is solved. In addition, the difficulty of OPC correction can be reduced, and the problem that the mask pattern with small size and high density is easily limited by space and is difficult to perform OPC correction can be effectively solved.

Description

Mask plate and preparation method thereof

Technical Field

The invention relates to the technical field of semiconductors, in particular to a mask plate and a preparation method thereof.

Background

In semiconductor manufacturing technology, photolithography is an important part of realizing pattern transfer, and with the trend of miniaturization of patterns, higher requirements are put on the photolithography. For this purpose, a phase shift layer is added to the mask plate to change the phase of the light in the phase shift region by about 180 °, so that destructive interference with the light in the non-phase shift region due to the phase difference can be generated, thereby improving the edge contrast of the copied pattern.

However, the existing mask plate is single in arrangement of the phase shift layer, and the single phase shift layer has larger limitation aiming at mask patterns with different pattern shapes and different pattern densities in the mask plate, so that different requirements of various mask patterns are difficult to meet. Furthermore, the addition of a phase shift layer, while improving the optical resolution, additionally carries the risk of "ghosting". For example, as shown in fig. 1, a phase shift layer 20 is provided on the substrate 10 of the reticle to cause a phase change of approximately 180 ° in the light passing therethrough. Referring specifically to fig. 2, there is schematically shown a waveform of light intensity when light passes through a phase shift region (a region covered with a phase shift layer) and a non-phase shift region (a region not covered with a phase shift layer), where the light intensity is close to 0 due to destructive interference of light at the boundary between the phase shift region and the non-phase shift region, which will be extremely liable to cause "ghosting" to be formed on a semiconductor substrate when a photolithography process is performed.

Therefore, how to further optimize the phase shift layer on the reticle and improve the pattern accuracy of the mask pattern replication on the semiconductor substrate is a critical issue at present.

Disclosure of Invention

The invention aims to provide a mask so as to optimize a phase shift layer on the mask and improve the replication precision of mask patterns.

To this end, the invention provides a reticle comprising: the light shielding device comprises a substrate, at least two phase shift layers and a light shielding layer, wherein the at least two phase shift layers and the light shielding layer are sequentially formed on the substrate, a light shielding pattern is defined in the light shielding layer, and the phase shift layer is positioned below the light shielding pattern and extends out from the edge of the light shielding pattern. At least two phase shift layers are overlapped below at least part of the shading patterns, and the sizes of the at least two phase shift layers transversely extending from the lower part of the shading patterns are different, so that the phase shift gradient is reduced.

Optionally, in the light shielding pattern defined by the light shielding layer, only one phase shift layer is formed below a part of the light shielding pattern.

Optionally, the phase shift amount generated by the single phase shift layer is less than or equal to 135 degrees; the phase shift amount generated when at least two phase shift layers are overlapped in the thickness direction is 200 DEG or less.

Optionally, all of the phase shift layers extend only in the edge region of the light shielding pattern, and at least part of the phase shift layers have edge thicknesses gradually decreasing along the extending direction.

Optionally, the at least two phase shift layers include a partial coverage phase shift layer extending only at the edge of the light shielding pattern and a full coverage phase shift layer covering the whole substrate, and the light transmittance of the full coverage phase shift layer is greater than that of the partial coverage phase shift layer.

Optionally, the partial coverage phase shift layer is located below the full coverage phase shift layer, the thickness of the end part of the partial coverage phase shift layer gradually decreases along the extending direction, and the full coverage phase shift layer conformally covers the partial coverage phase shift layer.

Optionally, the end of the phase shift layer extending at the edge of the shading pattern is connected in an arc shape from the top surface to the side wall to form an arc surface; alternatively, the end of the phase shift layer extending at the edge of the light shielding pattern is in an oblique angle structure.

Optionally, a carbon film layer is further formed on the top surface of the substrate, and the at least two phase shift layers are formed on the carbon film layer.

The invention also provides a preparation method of the mask plate, which comprises the following steps: providing a substrate, and forming a light shielding layer on the substrate, wherein a light shielding pattern is defined in the light shielding layer. Before the light shielding layer is formed, at least two phase shift layers are formed on the substrate, wherein the phase shift layers are positioned below the light shielding pattern and extend out from the edge of the light shielding pattern.

Optionally, the preparation method of the at least two phase-shift layers includes: forming a patterned first phase shift layer, wherein the first phase shift layer is formed below the light shielding pattern and extends out of the edge of the light shielding pattern; forming a dielectric layer, wherein the dielectric layer covers the first phase shift layer and planarizes the top surface of the dielectric layer; and forming a patterned second phase shift layer on the planarized dielectric layer, wherein the second phase shift layer is also formed below the light shielding pattern and extends out of the edge of the light shielding pattern.

Optionally, the preparation method of the at least two phase-shift layers includes: forming a patterned first phase shift layer, wherein the first phase shift layer is formed below the light shielding pattern and extends out of the edge of the light shielding pattern; and depositing a second phase-shift layer, wherein the second phase-shift layer fully covers the whole substrate and conformally covers the first phase-shift layer.

Optionally, before forming the phase shift layer, the method further includes: a carbon thin film layer is formed on a top surface of the substrate.

In the mask plate provided by the invention, at least two phase shift layers are arranged, and various different phase shift areas are formed by carrying out different combination collocation on the phase shift layers, so that different requirements of different mask patterns can be met. That is, the mask provided by the invention can flexibly combine and match at least two phase shift layers aiming at different mask patterns, thereby forming a phase shift region which is matched, meeting the requirements of different mask patterns on phase shift quantity and improving the contrast of patterns.

And based on the combination of at least two phase shift layers, various phase shift amounts can be generated, so that the direct change of the ultra-large span of the phase of light from 180 degrees to 0 degrees between adjacent areas can be avoided, and the problem of 'ghosting' caused by the direct change of the phase of light is solved. For example, the phase shift amount of the phase shift layer of a single layer can be made smaller, the phase difference between the phase shift region and the blank region (region not covered with the phase shift layer) can be reduced, and the problem of "ghosting" can be improved; or, the stacking quantity of the phase shift layers is gradually decreased in the direction away from the mask pattern, so that the phase shift quantity is gradually decreased, and the problem of 'ghosting' is effectively relieved.

In addition, because the mask plate provided by the invention can realize targeted compensation of each mask pattern by utilizing the multi-layer phase shift layer, the difficulty of OPC correction can be reduced, and the problem that small-size and high-density mask patterns are easy to be limited by space and difficult to carry out OPC correction can be effectively solved.

Drawings

Fig. 1 is a schematic structural diagram of a conventional mask.

Fig. 2 is a graph of light intensity waveforms for light passing through phase shift and non-phase shift regions.

FIG. 3 is a schematic diagram of a mask blank according to an embodiment of the invention.

FIG. 4 is a schematic diagram of another mask blank according to an embodiment of the invention.

FIG. 5 is an enlarged view of a portion of the base of a reticle in accordance with one embodiment of the invention.

FIG. 6 is a schematic diagram of a mask plate with a phase shift layer having an end portion with an oblique angle structure according to an embodiment of the present invention.

Wherein, the reference numerals are as follows: 10/100-substrate; a 110-carbon thin film layer; 20/200-phase shift layer; 210-a first phase shift layer; 220-a second phase shift layer; 300-a light shielding layer; 400-dielectric layer.

Detailed Description

The invention provides a mask plate, wherein at least two phase shift layers are arranged in the mask plate, so that at least two phase shift layers can be utilized for combination and collocation to generate various different phase shift amounts, and therefore, the combination and collocation of the phase shift layers can be flexibly adjusted according to different pattern shapes, different pattern densities and the like in the mask plate, the phase shift amounts required by various mask patterns can be adjusted in a targeted manner, and the pattern transfer and replication precision is improved. In addition, based on the invention, the phase shift layer can be flexibly adjusted, which is beneficial to avoiding the direct change of the ultra-large span of the light phase from 180 degrees to 0 degrees between adjacent areas, thereby improving the problem of 'ghosting' caused by the direct change.

The mask plate and the preparation method thereof provided by the invention are further described in detail below with reference to the accompanying drawings and specific examples. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in a very simplified form and are all to a non-precise scale, merely for convenience and clarity in aiding in the description of embodiments of the invention. It will be appreciated that relative terms such as "above," "below," "top," "bottom," "above," and "below" as illustrated in the figures may be used to describe various element relationships to one another. These relative terms are intended to encompass different orientations of the element in addition to the orientation depicted in the figures. For example, if the device is inverted relative to the view in the drawings, an element described as "above" another element, for example, will now be below the element.

Fig. 3 is a schematic structural view of one mask plate according to an embodiment of the present invention, and fig. 4 is a schematic structural view of another mask plate according to an embodiment of the present invention. As shown in fig. 3 and 4, the mask includes a substrate 100 and at least two phase shift layers 200 formed on the substrate 100, for stacking one or several of the phase shift layers 200 to form at least two phase shift regions, wherein the phase shift amounts of the at least two phase shift regions are different.

Specifically, the superposition condition of the phase shift layers 200 can be adjusted according to different mask patterns of the mask so as to generate different phase shift amounts, for example, only one layer of phase shift layer 200 can be arranged at a part of the mask in the thickness direction so as to obtain smaller phase shift amounts; alternatively, at least two phase shift layers 200 may be overlapped in the thickness direction for generating a larger phase shift amount. For example, for sparse patterns, allowing lower amounts of phase shift while still meeting the pattern contrast requirements, the number of phase shift layers 200 may be reduced (e.g., only one phase shift layer 200 may be provided); when the patterns are densely arranged, the phase shift amount can be increased to improve the contrast of the patterns, and more phase shift layers 200 can be overlapped at the moment; for the graph with sharp boundary, at least two phase shift layers 200 may be overlapped to increase the phase shift amount and improve the contrast of the graph.

Further, a light shielding layer 300 is further disposed on the mask, and a light shielding pattern is defined in the light shielding layer 300. The light shielding layer 300 may be formed of a material having a high light absorption coefficient, for example, the material of the light shielding layer 300 may include chromium (Cr) and/or chromium nitride so that the transmittance of light may be less than 2%, or even may be 0%.

In one example, all of the phase shift layers 200 are extended only at the edges of the light shielding pattern to form destructive interference based on light of different phases at the edge positions of the mask pattern, thereby improving the edge contrast of the mask pattern copied onto the semiconductor substrate. Taking fig. 3 as an example, at least two phase shift layers 200 are disposed below the light shielding pattern and extend laterally, and the phase shift layers 200 are disposed only at the edges of the light shielding pattern.

Specifically, in the example of fig. 3, a first phase shift layer 210 and a second phase shift layer 220 are provided. Wherein both the first phase-shifting layer 210 and the second phase-shifting layer 220 may be used to produce the same amount of phase shift, e.g., both the first phase-shifting layer 210 and the second phase-shifting layer 220 are used to produce a phase change of 70 ° -110 °. Alternatively, the first phase-shifting layer 210 and the second phase-shifting layer 220 may be used to generate different amounts of phase shift, respectively, e.g., the first phase-shifting layer 210 is used to generate a phase change of 30 ° -60 °, and the second phase-shifting layer 220 is used to generate a phase change of 90 ° -135 °.

And, the phase shift amounts generated when at least two phase shift layers 200 are overlapped in the thickness direction may be overlapped with each other based on the phase shift amounts of the respective phase shift layers 200. In a specific example, when there is only one phase shift layer 200 in the thickness direction, the amount of phase shift generated may be 135 ° or less, and when at least two phase shift layers 200 are overlapped in the thickness direction, the amount of phase shift generated may be 200 ° or less. The phase shift regions with different phase shift amounts can be formed by combining and collocating the different phase shift layers 200.

For ease of understanding, the first phase shift layer 210 and the second phase shift layer 220 in fig. 3 are each used to produce a 90 ° phase change, and the reticle is exemplified as a transmissive reticle, so that the transmitted light produces a 90 ° phase change when only the first phase shift layer 210 is provided, a 90 ° phase change when only the second phase shift layer 220 is provided, and a 180 ° phase change when the first phase shift layer 210 and the second phase shift layer 220 are provided in an overlapping manner.

It should be appreciated that fig. 3 is merely exemplary, and that in actual practice, both the first phase-shifting layer 210 and the second phase-shifting layer 220 may have their phase-shifting amounts varied by film layer parameter adjustment. Specifically, the phase shift amount may be correspondingly increased by increasing the thickness of the phase shift layer 200; conversely, the amount of phase shift can be reduced by reducing the thickness of the phase shift layer 200.

And, each phase shift layer 200 has a certain light transmittance T, for example, the light transmittance T of a single layer of the phase shift layer 200 is 20% or more. And the light transmittance T of the phase-shift layers 200 of the different layers may be the same (e.g., 20% -60% each); alternatively, the light transmittance T of the phase-shift layer 200 may be different for different layers (e.g., the light transmittance T of a portion of the phase-shift layer 200 is 20% -50% and the light transmittance T of a portion of the phase-shift layer 200 is 50% -100%). In the example shown in fig. 3, the light transmittance T of each of the first phase shift layer 210 and the second phase shift layer 220 may be 20% to 50%, and the light transmittance T when the first phase shift layer 210 and the second phase shift layer 220 are stacked may be 4% to 25%.

Further, as described above, different phase shift layers 200 may be extended below them according to specific mask patterns. Specifically, at least two phase shift layers 200 may be disposed under at least a portion of the light shielding pattern, and the at least two phase shift layers 200 may have different dimensions extending laterally from under the light shielding pattern, so that the number of phase shift layers may be gradually reduced in a direction away from the light shielding pattern, and at least two phase shift regions having a reduced phase shift gradient may be formed.

For example, as shown in fig. 3, the light shielding pattern of the light shielding layer 300 on the right side is, for example, a pattern with sharp boundary, so that the first phase shift layer 210 and the second phase shift layer 220 can be disposed under the light shielding pattern in an extending manner to improve the pattern contrast, and the number of phase shift layers is reduced in the direction away from the light shielding pattern, so that the gradient of the phase shift amount is reduced, and the problem of "ghosting" is improved. Specifically, the second phase shift layer 220 may extend to a larger dimension than the first phase shift layer 210, or the first phase shift layer 210 may extend to a larger dimension than the second phase shift layer 220, so as to form two phase shift regions with gradient changes of phase shift amounts.

With continued reference to fig. 3, the light shielding pattern (not shown) of the light shielding layer 300 on the left side is, for example, a straight line pattern, and only the first phase shift layer 210 or only the second phase shift layer 220 can be extended to meet the contrast requirement of the light shielding pattern.

Further, in the example of fig. 3, a dielectric layer 400 may also be disposed between adjacent phase shift layers 200, the dielectric layer 400 covering the underlying phase shift layer 200, and the top surface of the dielectric layer 400 may be further planarized, and the overlying phase shift layer 200 may be formed on the planarized dielectric layer 400. In this embodiment, the dielectric layer 400 may be formed of a transparent dielectric material, for example, including silicon oxide, so as to reduce transmission loss when passing through the dielectric layer 400.

In another example, the at least two phase-shift layers 200 include a partial coverage phase-shift layer extending only around the edge of the mask pattern and a full coverage phase-shift layer covering the entire substrate 100, wherein the light transmittance T of the full coverage phase-shift layer is greater than the light transmittance T of the partial coverage phase-shift layer, e.g., the light transmittance T of the full coverage phase-shift layer is greater than 50%, and even the light transmittance T of the full coverage phase-shift layer is greater than or equal to 70%. And the total light transmittance when the full-coverage phase shift layer and the partial-coverage phase shift layer are overlapped can be between 10% and 50%.

Taking fig. 4 as an example, a first phase shift layer 210 and a second phase shift layer 220 are also provided. Wherein, the first phase shift layer 210 below can be made to partially cover the phase shift layer, that is, the first phase shift layer 210 is only disposed below the light shielding pattern and extends laterally to be only located at the edge of the light shielding pattern; and, the second phase-shift layer 220 above may constitute a full-coverage phase-shift layer, i.e., the second phase-shift layer 220 covers the entire substrate 100. Alternatively, the upper second phase shift layer 220 may be formed as a partial cover phase shift layer, and the lower first phase shift layer 210 may be formed as a full cover phase shift layer.

Thus, in the example shown in fig. 4, the edge region of the light shielding pattern may generate a larger phase shift amount (e.g., 170 ° -190 °) based on the mutual superposition of the first phase shift layer 210 and the second phase shift layer 220, and a smaller phase shift amount (e.g., 60 °) based on the single second phase shift layer 220 in the region far from the light shielding pattern. Taking fig. 4 as an example, the first phase shift layer 210 and the second phase shift layer 220 are overlapped to generate a 180 ° phase change, and a single second phase shift layer 220 may generate a 45 ° phase change.

In summary, in the mask provided in this embodiment, at least two phase shift layers 200 are disposed, so that at least two phase shift layers 200 can be utilized to obtain a plurality of different phase shift amounts according to different requirements of different patterns, so as to satisfy different requirements of different mask patterns on the phase shift amounts. The light transmittance T and the phase shift amount Φ of each phase shift layer 200 can be adjusted by adjusting the material or thickness of the phase shift layer 200. For example, the material of the phase shift layer 200 may include silicon molybdenum nitride (MoSiN), and may be further doped with other ions (e.g., oxygen, carbon, fluorine, etc.) to further adjust the optical parameters (e.g., refractive index, extinction coefficient, etc.) of the phase shift layer 200. In a specific example, the refractive index of the phase shift layer 200 may be adjusted between 2.0-3.0, the extinction coefficient of the phase shift layer 200 may be adjusted between 0.4-0.8, and the thickness of the phase shift layer 200 may range, for example, between 30nm-100 nm.

In addition, because at least two phase shift layers 200 can be combined to match a plurality of different phase shift amounts in the present embodiment, the flexible adjustment of the phase shift layers 200 is also beneficial to avoiding the abrupt decrease or increase of the phase shift amounts between adjacent areas, so as to effectively improve the problem of "ghosting" generated during the graph replication.

Continuing with the example of fig. 3, first, the phase shift amount generated by the single phase shift layer 200 may be made smaller than 180 ° (specifically, may be further smaller than 135 °), and at this time, the difference between the phase shift amount generated by the light passing through the single phase shift layer 200 and the phase shift amount generated by the light passing through the adjacent blank area (the area where the phase shift layer is not provided) is reduced, so that the problem of "ghosting" is advantageously alleviated. For example, in fig. 3, the phase difference between the amount of phase shift generated by light passing through the first phase shift layer 210 and the amount of phase shift generated by light passing through the adjacent blank region is only 90 °, and likewise, the phase difference between the amount of phase shift generated by light passing through the second phase shift layer 220 and the amount of phase shift generated by light passing through the adjacent blank region is also only 90 °, so that there is only a phase difference of 90 ° between the immediately adjacent phase shift region and the blank region. Secondly, the phase shift layers 200 may be combined to achieve gradient decreasing of the phase shift from high to low, for example, in fig. 3, in a direction gradually approaching to the blank area, the overlapping first phase shift layer 210 and second phase shift layer 220 are sequentially arranged to form a phase shift area with the phase shift of 180 ° and only the second phase shift layer 220 is arranged to form a phase shift area with the phase shift of 90 °, so that gradient change of the phase shift from 180 ° to 90 ° and further to 0 ° is achieved, and the problem of "ghosting" can be effectively relieved. Of course, in the direction from the phase shift region to the blank region in fig. 3, the phase shift layer 200 may be arranged in the following manner: the first phase shift layer 210 and the second phase shift layer 220 are sequentially provided, and only the first phase shift layer 210 is provided, and a gradient change in which the phase shift amount is reduced from 180 ° to 90 ° and further reduced to 0 ° can be formed as well.

Alternatively, the thickness of the end portion of at least part of the phase-shift layer 200 may be gradually reduced along the extending direction, for example, the thickness of the end portion of the phase-shift layer 200 furthest extending in the extending direction may be gradually reduced. In this embodiment, the end of the phase shift layer 200 is connected from the top surface to the sidewall in an arc shape to form an arc surface, so that the variation trend of the phase shift amount can be further smoothed, and the problem of "ghosting" can be better improved. Alternatively, in other embodiments, such as shown in fig. 6, the end portion of the phase shift layer 200 may be formed with an oblique angle, and the thickness of the end portion may be gradually reduced along the extending direction.

Next, referring to the example shown in fig. 4, a partial coverage phase shift layer and a full coverage phase shift layer are overlapped on an edge region of the light shielding pattern, and only the full coverage phase shift layer is provided on a region far away from the light shielding pattern, so that the phase shift amount between adjacent regions is not reduced or increased in a large range, and the problem of "ghosting" generated during pattern replication can be effectively improved.

Similar to the example in fig. 3, the thickness of the end portion of the extension end of the partially covered phase shift layer (the first phase shift layer 210) in fig. 4 is gradually reduced along the extension direction, for example, the end portion of the partially covered phase shift layer is connected in an arc shape from the top surface to the side wall to form an arc surface, and the partially covered phase shift layer (the first phase shift layer 210) below the partially covered phase shift layer (the second phase shift layer 220) is formed in a conformal manner, so that a step with smooth transition is correspondingly generated on the end portion of the fully covered phase shift layer (the second phase shift layer 220), and the variation trend of the phase shift amount can be further flattened, and the problem of "ghost" is better improved. Of course, in other examples, the end portion of the partially covered phase shift layer (the first phase shift layer 210) may be in an oblique angle structure, and when the fully covered phase shift layer (the second phase shift layer 220) covers the end portion of the partially covered phase shift layer (the first phase shift layer 210) below the end portion, a slope with gradually reduced height is correspondingly formed, so as to further optimize the problem of "ghosting".

In addition, in order to improve the pattern accuracy of the mask pattern replica on the semiconductor substrate, the pattern variation due to the optical disturbance is usually compensated for by OPC correction, however, the space for OPC correction is limited for a pattern of a small size and high density, and it is difficult to perform optical correction. However, in this embodiment, at least two phase shift layers 200 are utilized to adjust the phase shift amount in a targeted manner, so as to improve the pattern precision of each pattern, and the difficulty of OPC correction can be reduced under the compensation of a specific phase shift region when aiming at patterns with small size and high density.

In a further aspect, the top surface of the substrate 100 may further be formed with a carbon film layer 110, which is used to smooth the top surface of the substrate 100 and is beneficial to recycling the substrate 100. It should be noted that, in the mask of the present embodiment, at least two phase shift layers 200 are required to be prepared on the substrate 100, and in order to avoid damage to the substrate 100, the carbon film layer 110 is formed on the top surface of the substrate 100 before the phase shift layers are prepared, so that the substrate 100 can be protected from the process above the carbon film layer 110. In addition, the carbon film layer 110 is easily ashed and removed by oxygen plasma, so that the substrate 100 is not damaged, the quality of the substrate surface is ensured, the substrate can be reused, and the production cost is reduced.

In addition, referring to fig. 5, there are generally fine defects (e.g., fine cracks, etc.) on the top surface of the substrate 100, and the carbon thin film layer 110 has a strong gap filling ability, so that the carbon thin film layer 110 can effectively fill the fine defects on the surface of the substrate and planarize the surface. In a specific example, the substrate 100 may be quartz glass, microcrystalline glass (Zerodur), ultra low expansion coefficient quartz glass (ULE, also referred to as zero expansion glass), or the like. And, the thickness of the carbon thin film layer 110 may be controlled to be within 30nm, for example.

Based on the mask plate, the preparation method is described below, and specifically comprises the following steps: at least two phase shift layers 200 are sequentially formed on a substrate 100, so that one or more of the phase shift layers 200 are stacked and combined to form at least two phase shift regions, and the phase shift amounts of the at least two phase shift regions are different.

In a specific example, the carbon thin film layer 110 may be formed on the top surface of the substrate 100 before the phase shift layer 200 is formed, and the carbon thin film layer 110 may be formed using, for example, a spin coating process. The carbon film layer 110 has a strong gap filling capability, and can effectively fill fine defects on the surface of the substrate and planarize the surface. Thus, on one hand, the substrate 100 can be protected, the damage to the substrate 100 caused by the subsequent film preparation process is avoided, and the carbon film layer 110 can achieve higher surface flatness, and is also beneficial to improving the film quality of the phase shift layer prepared subsequently; on the other hand, the carbon film layer 110 is easily ashed and removed by oxygen plasma, so that the substrate 100 is not damaged, the quality of the substrate surface is ensured, the substrate can be reused, and the production cost is reduced.

After the carbon thin film layer 110 is formed, the phase shift layer 200, the light shielding layer 300, and the like may be sequentially prepared on the carbon thin film layer 110.

First, for the mask shown in fig. 3, the preparation method includes: a first step of forming a first phase shift layer 210, wherein the first phase shift layer 210 is a patterned phase shift layer formed only under a mask pattern (which may be defined by a light shielding layer formed later) and an edge region thereof; a second step of forming a dielectric layer 400, wherein the dielectric layer 400 covers the first phase shift layer 210 and planarizes the top surface of the dielectric layer 400; in the third step, a second phase shift layer 220 is formed on the planarized dielectric layer 400, the second phase shift layer 220 is also a patterned phase shift layer, and the second phase shift layer 220 is also formed only under the mask pattern and in the edge region thereof. In a specific example, when the first phase-shift layer 210 and the second phase-shift layer 220 are prepared, the end portions of the phase-shift layers may be further modified into an oblique angle structure or an arc structure by adjusting etching parameters of the etching process. And, after forming the second phase shift layer 220, preparing a light shielding layer 300 for defining a light shielding pattern.

Next, for the mask shown in fig. 4, the preparation method includes: a first step of forming a first phase shift layer 210, wherein the first phase shift layer 210 is a patterned phase shift layer, which is formed only under a mask pattern (the mask pattern may be defined by a light shielding layer formed later) and an edge region thereof, and the end of the first phase shift layer 210 may be modified into an oblique angle structure or an arc structure by adjusting etching parameters of an etching process when the first phase shift layer 210 is prepared; in a second step, a second phase-shift layer 220 is formed, the second phase-shift layer 220 fully covering the substrate 100 and conformally covering the first phase-shift layer 210. And, after forming the second phase shift layer 220, preparing a light shielding layer 300 for defining a light shielding pattern.

According to the mask plate and the preparation method thereof, the setting flexibility of the phase shift region is greatly improved, so that different mask patterns can be provided with corresponding phase shift amounts in a targeted manner, the pattern contrast is improved, meanwhile, the problem of 'ghosting' can be improved, and the replication precision of the mask patterns is further improved. Furthermore, the above embodiments are described by taking a transmissive reticle for DUV as an example, however, it should be appreciated that the core concept provided by the present invention is equally applicable to a reflective reticle for EUV.

It should be noted that, in the present description, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different manner from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. And, while the present invention has been disclosed in terms of preferred embodiments, the above embodiments are not intended to limit the present invention. Many possible variations and modifications of the disclosed technology can be made by anyone skilled in the art without departing from the scope of the technology, or the technology can be modified to be equivalent. Therefore, any simple modification, equivalent variation and modification of the above embodiments according to the technical substance of the present invention still fall within the scope of the technical solution of the present invention.

It should be further understood that the terms "first," "second," "third," and the like in this specification are used merely for distinguishing between various components, elements, steps, etc. in the specification and not for indicating a logical or sequential relationship between the various components, elements, steps, etc., unless otherwise indicated. It should also be recognized that, as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. For example, reference to "a step" or "an apparatus" means a reference to one or more steps or apparatuses, and may include sub-steps as well as sub-apparatuses. All conjunctions used should be understood in the broadest sense. And, the word "or" should be understood as having the definition of a logical "or" rather than a logical "exclusive or" unless the context clearly indicates the contrary. Furthermore, implementation of the methods and/or apparatus in embodiments of the invention may include performing selected tasks manually, automatically, or in combination.

Claims (11)

1. A reticle, comprising: the light shielding device comprises a substrate, at least two phase shift layers and a light shielding layer, wherein the at least two phase shift layers and the light shielding layer are sequentially formed on the substrate, a light shielding pattern is defined in the light shielding layer, and the phase shift layer is positioned below the light shielding pattern and extends out from the edge of the light shielding pattern;

at least two phase shift layers are overlapped below at least part of the shading pattern, the phase shift quantity generated by a single phase shift layer is less than or equal to 135 degrees, the phase shift quantity generated when at least two phase shift layers are overlapped along the thickness direction is less than or equal to 200 degrees, and the sizes of the at least two phase shift layers transversely extending out from the lower part of the shading pattern are different, so that the phase shift quantity is gradually decreased within the range of 200-0 degrees, and the phase shift quantity of each phase shift layer is adjusted by adjusting the material or the thickness of the phase shift layer.

2. The mask of claim 1, wherein the light shielding layer defines a light shielding pattern, and only one phase shift layer is formed under a part of the light shielding pattern.

3. The reticle of claim 1, wherein all phase shift layers extend only at an edge region of the light shielding pattern, and at least a portion of the phase shift layers have edge thicknesses that decrease stepwise along the direction of extension.

4. The reticle of claim 1, wherein the at least two phase shift layers include a partial coverage phase shift layer extending only at an edge of the light shielding pattern and a full coverage phase shift layer covering the entire substrate, the full coverage phase shift layer having a light transmittance greater than a light transmittance of the partial coverage phase shift layer.

5. The reticle of claim 4, wherein the partial coverage phase shift layer is located below the full coverage phase shift layer, an end thickness of the partial coverage phase shift layer gradually decreases along an extension direction, and the full coverage phase shift layer conformally covers the partial coverage phase shift layer.

6. The reticle of claim 3 or 5, wherein the ends of the phase shift layer extending at the edges of the light shielding pattern are connected in an arc from the top surface to the sidewalls to form an arc surface; alternatively, the end of the phase shift layer extending at the edge of the light shielding pattern is in an oblique angle structure.

7. The reticle of claim 1, wherein the substrate further has a carbon film layer formed on a top surface thereof, the at least two phase shift layers being formed on the carbon film layer.

8. The preparation method of the mask plate is characterized by comprising the following steps: providing a substrate, and forming a light shielding layer on the substrate, wherein a light shielding pattern is defined in the light shielding layer;

before the light shielding layer is formed, at least two phase shift layers are formed on the substrate, the phase shift amount generated by a single phase shift layer is less than or equal to 135 degrees, the phase shift amount generated when the at least two phase shift layers are overlapped along the thickness direction is less than or equal to 200 degrees, the phase shift layers are positioned below the light shielding pattern and extend out from the edge of the light shielding pattern, and the dimensions of the at least two phase shift layers transversely extending out from the lower part of the light shielding pattern are different, so that the phase shift amount is gradually decreased within the range of 200-0 degrees, and the phase shift amount of each phase shift layer is adjusted by adjusting the material or the thickness of the phase shift layer.

9. The method for preparing a mask according to claim 8, wherein the method for preparing at least two phase shift layers comprises:

forming a patterned first phase shift layer, wherein the first phase shift layer is positioned below the shading pattern and extends out of the edge of the shading pattern;

forming a dielectric layer, wherein the dielectric layer covers the first phase shift layer and planarizes the top surface of the dielectric layer; the method comprises the steps of,

and forming a patterned second phase shift layer on the planarized dielectric layer, wherein the second phase shift layer is also positioned below the light shielding pattern and extends out of the edge of the light shielding pattern.

10. The method for preparing a mask according to claim 8, wherein the method for preparing at least two phase shift layers comprises:

forming a patterned first phase shift layer, wherein the first phase shift layer is positioned below the shading pattern and extends out of the edge of the shading pattern; the method comprises the steps of,

and depositing a second phase shift layer, wherein the second phase shift layer fully covers the whole substrate and conformally covers the first phase shift layer.

11. The method of manufacturing a reticle according to any one of claims 8 to 10, further comprising, prior to forming the phase shift layer: a carbon thin film layer is formed on a top surface of the substrate.