Mask absorption layer preparation method, mask and preparation method thereof

Abstract

The invention provides a preparation method of a mask plate absorption layer, a mask plate and a preparation method thereof, and relates to the technical field of photoetching, and the preparation method of the mask plate absorption layer comprises the following steps: obtaining a mask substrate; according to the method, an actual absorption layer is prepared on the surface of a mask substrate through ion beam deposition, the inclination angle between the incident direction of target particles needed for preparing the actual absorption layer and the direction perpendicular to the surface of the mask substrate is adjusted by changing the relative angle of the mask substrate and a target material during ion beam deposition, and the stress of the actual absorption layer is adjusted and controlled; the deformation quantity and / or the surface shape PV of the surface of the mask substrate are / is controlled.

Description

Technical Field

[0001] The present disclosure relates to the field of photolithography technology, and in particular to a method for preparing a mask absorption layer, a mask and a method for preparing the same. Background Art

[0002] In the manufacturing process of micro-nano lithography masks, the deposition of the absorption layer is a very important step and the basis of mask pattern processing. Magnetron sputtering is a commonly used method for preparing the absorption layer, which can obtain a relatively dense film layer. However, when the metal material is sputtered and deposited by the RF power supply, the power of the RF power supply cannot be too large, otherwise it will cause voltage instability and the glow will flicker. It is more difficult to obtain a denser film layer by the magnetron sputtering method. At this time, ion beam deposition (IBD) is required to prepare the absorption layer.

[0003] When ion beam deposition is used to prepare a metal absorption layer, due to the high energy of the deposited particles and the large surface migration ability, a high-density film close to the bulk material can be obtained, and the optical and mechanical properties of the prepared film are excellent. However, the prepared film also has an ultra-high bulk density, so that the film layer usually presents a high stress state, and as the thickness of the film layer increases, the stress accumulated in the film layer will cause serious surface distortion on the mask surface, introduce large errors, and affect the exposure uniformity and overlay accuracy. When the stress accumulates to a certain extent or reaches a certain threshold, the film may even fail due to warping, cracking, falling off, etc., which greatly affects the subsequent processing and use as a mask absorption layer. Summary of the invention

[0004] In view of this, a first aspect of an embodiment of the present disclosure provides a method for preparing a mask absorption layer, comprising: obtaining a mask substrate; preparing an actual absorption layer on the surface of the mask substrate by ion beam deposition, wherein the relative angle between the mask substrate and the target material during ion beam deposition is changed to adjust the inclination angle between the incident direction of the target particles required for preparing the actual absorption layer and the direction perpendicular to the surface of the mask substrate, so as to regulate the stress of the actual absorption layer and control the deformation amount and / or surface shape PV of the mask substrate surface.

[0005] According to an embodiment of the present disclosure, the method also includes: obtaining a first surface shape of a mask substrate on which no predetermined absorption layer is formed; preparing predetermined absorption layers of different predetermined deposition thicknesses on the mask substrate at multiple predetermined relative angles to obtain second surface shapes of mask substrates on which predetermined absorption layers of respective predetermined deposition thicknesses are formed; calculating the stress magnitude of the predetermined absorption layer of the corresponding predetermined deposition thickness on the mask substrate surface according to the amount of change in surface curvature between the second surface shape corresponding to the predetermined absorption layer of each predetermined deposition thickness and the first surface shape; fitting the stress magnitude of the predetermined absorption layer of each predetermined deposition thickness on the mask substrate surface at multiple predetermined relative angles to form stress-inclination curves corresponding to the predetermined absorption layers of different deposition thicknesses; repeating the above operations to obtain stress-inclination curves of predetermined absorption layers of different material types at different deposition thicknesses.

[0006] According to an embodiment of the present disclosure, a first surface shape of a mask substrate on which no predetermined absorption layer is formed is obtained; predetermined absorption layers of different material types are prepared on the mask substrate at multiple predetermined relative angles to obtain second surface shapes of mask substrates on which predetermined absorption layers of respective predetermined material types are formed; the stress of the predetermined absorption layer of the corresponding predetermined material type on the surface of the mask substrate is calculated based on the amount of change in surface curvature between the second surface shape corresponding to the predetermined absorption layer of each predetermined material type and the first surface shape; the stress of the predetermined absorption layer of each predetermined material type on the surface of the mask substrate at multiple predetermined relative angles is fitted to form stress-inclination curves corresponding to the predetermined absorption layers of different material types; the above operation is repeated to obtain stress-inclination curves of predetermined absorption layers of different deposition thicknesses under different material types.

[0007] According to an embodiment of the present disclosure, the relative angle between the mask substrate and the target material during ion beam deposition is changed to adjust the inclination angle between the incident direction of the target particles required for preparing the absorption layer and the surface of the mask substrate, including: based on the stress-inclination curve, according to the material type of the actual absorption layer and the deposition thickness of the actual absorption layer, selecting the inclination angle corresponding to the predetermined stress range and depositing the actual absorption layer on the surface of the mask substrate at the inclination angle corresponding to the predetermined stress range.

[0008] According to an embodiment of the present disclosure, it is characterized in that the material of the actual absorption layer includes one of Cr, Ta, Mo, MoSi and MoTa.

[0009] According to an embodiment of the present disclosure, the actual thickness of the absorption layer is 38 nm to 42 nm.

[0010] According to an embodiment of the present disclosure, the predetermined inclination angle is between 10° and 60°.

[0011] According to an embodiment of the present disclosure, the material of the mask substrate includes sapphire or fused quartz.

[0012] A second aspect of the disclosed embodiments provides a method for preparing a mask, comprising: preparing an absorption layer of the mask by the above-mentioned preparation method; and preparing the mask when the deformation amount and / or surface shape PV of the mask substrate surface meets preset conditions.

[0013] A third aspect of the embodiments of the present disclosure provides a mask, which is prepared by the above-mentioned preparation method.

[0014] The mask absorption layer preparation method, mask and preparation method thereof provided by the embodiments of the present disclosure have at least the following technical effects:

[0015] In the process of preparing the absorption layer by ion beam deposition, the relative angle between the mask substrate and the target material during ion beam deposition is changed to adjust the inclination angle between the incident direction of the target particles required for preparing the absorption layer and the surface of the mask substrate to control the stress of the absorption layer, thereby offsetting the influence of the stress of the absorption layer on the mask plate shape, greatly reducing the change in the mask plate shape before and after the absorption layer is coated, and avoiding the influence of the deformation of the mask substrate on the pattern processing uniformity, position error and subsequent pattern replication process of the photomask.

[0016] This method is universal and is not limited to the regulation of mask absorption layer stress and mask surface shape control. This method can also be applied to surface shape control for a wider range of substrate deformation control needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0018] Figure 1 The flowchart of the method for preparing the mask absorption layer according to the embodiment of the present disclosure is schematically shown.

[0019] Figure 2 The principle diagram of the method for preparing the mask absorption layer according to the embodiment of the present disclosure is schematically shown.

[0020] Figure 3 The stress-inclination curve diagram corresponding to the absorption layer formed by different types of materials with the same predetermined deposition thickness in the embodiment of the present disclosure is schematically shown.

[0021] Figure 4A The stress diagram of the Cr film layer when the deposition tilt angle is 60° according to an embodiment of the present disclosure is schematically shown.

[0022] Figure 4BThe stress diagram of the Cr film layer when the deposition tilt angle is 48° according to an embodiment of the present disclosure is schematically shown.

[0023] Figure 4C The stress diagram of the Cr film layer when the deposition tilt angle is 30° according to an embodiment of the present disclosure is schematically shown.

[0024] Figure 4D The stress diagram of the Cr film layer when the deposition tilt angle is 20° according to an embodiment of the present disclosure is schematically shown.

[0025] Figure 4E The stress diagram of the Cr film layer when the deposition tilt angle is 10° according to an embodiment of the present disclosure is schematically shown.

[0026] Figure 5 The diagram schematically shows the result of repeatability verification of the Cr film stress control process according to an embodiment of the present disclosure.

[0027] Fig. 6A The figure schematically shows the surface shape of the mask substrate when the deposition inclination angle is 60° according to an embodiment of the present disclosure.

[0028] Figure 6B The figure schematically shows the surface shape of the mask substrate when the deposition inclination angle is 48° according to an embodiment of the present disclosure.

[0029] Figure 6C The figure schematically shows the surface shape of the mask substrate when the deposition inclination angle is 30° according to an embodiment of the present disclosure.

[0030] Fig.6D The figure schematically shows the surface shape of the mask substrate when the deposition inclination angle is 20° according to an embodiment of the present disclosure.

[0031] Fig. 6E The figure schematically shows the surface shape of the mask substrate when the deposition inclination angle is 10° according to an embodiment of the present disclosure.

[0032] Fig. 7A The initial surface shape of a whole 6-inch center-thinned mask substrate before coating according to an embodiment of the present disclosure is schematically shown.

[0033] Figure 7B The figure schematically shows the topography of a whole 6-inch center-thinned mask substrate after coating according to an embodiment of the present disclosure.

[0034] Fig. 8A The initial surface diagram of a 26×33 mm standard field of a 6-inch center-thinned mask substrate before coating according to an embodiment of the present disclosure is schematically shown.

[0035] Figure 8BThe figure schematically shows the post-coating topography of a 26×33 mm standard field of a 6-inch center-thinned mask substrate according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present disclosure.

[0037] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0038] Similarly, in order to simplify the present disclosure and help understand one or more of the various disclosed aspects, in the above description of the exemplary embodiments of the present disclosure, the various features of the present disclosure are sometimes grouped together into a single embodiment, figure, or description thereof. The description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0039] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the feature. In the description of the present disclosure, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0040] In the process of realizing the present disclosure, it was found that the Cr film layer has a high absorption rate for light in a specific wavelength range and has a high adhesion to a transparent substrate, so it can be used as a photomask absorption layer material. When using ion beam sputtering to prepare the Cr film layer, it is necessary to perform sputtering deposition under a high ion source voltage and a low chamber pressure. The Cr film layer prepared in this way has a large residual stress, which will cause deformation of the substrate, and adversely affect the pattern processing uniformity, position error and subsequent pattern replication process of the photomask.

[0041] Ion beam deposition can reduce the internal stress of the deposited Cr film by adjusting the sputtering chamber pressure and changing the process gas, but this method has certain limitations in adjusting stress and cannot fully meet the surface shape requirements of the mask absorption layer. In addition, the absorption rate of the Cr film at a specific wavelength will also be reduced to a certain extent, affecting the subsequent processing of the mask. Similar problems also exist in other absorption layers.

[0042] In view of this, the embodiments of the present disclosure aim to provide a method for preparing a mask absorption layer, a mask and a method for preparing the same, which, under the premise of ensuring that the absorption rate of the absorption layer remains unchanged, reduces the influence of the stress of the absorption layer on the deformation of the substrate before and after coating, and provides a new technical route for effectively suppressing the influence of the stress of the absorption layer on the surface shape of the mask substrate. The following is a detailed introduction in conjunction with specific embodiments.

[0043] Figure 1 The flowchart of the method for preparing the mask absorption layer according to the embodiment of the present disclosure is schematically shown.

[0044] like Figure 1 As shown, the method for preparing a mask absorption layer in this embodiment may include operations S110 to S140.

[0045] In operation S110, a mask substrate is obtained.

[0046] In operation S120, an actual absorption layer is prepared on the surface of a mask substrate by ion beam deposition, wherein the relative angle between the mask substrate and the target material during ion beam deposition is changed to adjust the inclination angle between the incident direction of the target particles required for preparing the actual absorption layer and the direction perpendicular to the surface of the mask substrate, thereby regulating the stress of the actual absorption layer and controlling the deformation amount and / or surface shape PV of the mask substrate surface.

[0047] In some embodiments of the present disclosure, the mask substrate may include, for example, sapphire or fused quartz of any surface shape. The specific type of the mask substrate may be selected according to actual application requirements, and the present disclosure does not limit it. The actual absorption layer may be understood as the absorption layer that needs to be prepared in the process of preparing the finished mask.

[0048] Figure 2 The principle diagram of the method for preparing the mask absorption layer according to the embodiment of the present disclosure is schematically shown.

[0049] like Figure 2As shown in the figure, the ion beam deposition adopts the inclined deposition (tilt angle α), and the anisotropic microstructure of the inclined deposited film will lead to the corresponding film stress anisotropy, and this anisotropic stress behavior can be attributed to the anisotropic shadow and column fan effect. For example, along the incident flux direction (such as the y direction), the ballistic shadow increases the column separation and allows the structure to relax. In contrast, there is no shadow in the orthogonal direction to restrict growth. Therefore, these columns can fan out in the x direction and are more inclined to chain together, thereby reducing the stress level of the film. Since the deposition with an inclined angle increases the porosity of the film layer, the columnar microstructure is decoupled and the structure is relaxed on a short length scale. Therefore, as the deposition angle increases, the total film stress tends to decrease.

[0050] According to the embodiments of the present disclosure, the stress magnitudes and types corresponding to absorption layers of different materials and absorption layers of different thicknesses may be different, and the corresponding inclination angles may also be different. In order to accurately select the inclination angles for absorption layers of different materials and absorption layers of different thicknesses during the preparation of the absorption layers, it is preferably necessary to predetermine the optimal inclination angle range corresponding to absorption layers of different materials and absorption layers of different thicknesses.

[0051] Based on this, in some embodiments of the present disclosure, the preparation method may further include:

[0052] A first surface shape of the mask substrate having no predetermined absorption layer formed on the surface is obtained.

[0053] Predetermined absorption layers with different predetermined deposition thicknesses are prepared on the mask substrate at a plurality of predetermined relative angles, respectively, to obtain the second surface shapes of the mask substrates each having a predetermined absorption layer with each predetermined deposition thickness formed on the surface.

[0054] The stress magnitude of the predetermined absorption layer corresponding to the predetermined deposition thickness on the surface of the mask substrate is calculated according to the surface curvature variation between the second surface shape and the first surface shape corresponding to each predetermined absorption layer with the predetermined deposition thickness.

[0055] The stress magnitude of the predetermined absorption layer with each predetermined deposition thickness on the surface of the mask substrate is fitted under multiple predetermined relative angles to form stress-inclination curves corresponding to the predetermined absorption layers with different deposition thicknesses.

[0056] The above operation is repeated to obtain stress-inclination curves of predetermined absorption layers of different material types at different deposition thicknesses.

[0057] Similarly, in some other embodiments of the present disclosure, the preparation method may further include:

[0058] Obtaining a first surface shape of a mask substrate having no predetermined absorption layer formed on the surface;

[0059] Predetermined absorption layers of different material types are prepared on the mask substrate at a plurality of predetermined relative angles, respectively, to obtain second surface shapes of the mask substrates each having a predetermined absorption layer of each predetermined material type formed on the surface;

[0060] Calculating the stress of the predetermined absorption layer of the predetermined material type on the surface of the mask substrate according to the curvature change between the second surface shape corresponding to the predetermined absorption layer of each predetermined material type and the first surface shape;

[0061] Fitting the stress magnitude of the predetermined absorption layer of each predetermined material type on the surface of the mask substrate at multiple predetermined relative angles to form stress-inclination curves corresponding to the predetermined absorption layers of different material types;

[0062] The above operation is repeated to obtain stress-inclination curves of predetermined absorption layers with different deposition thicknesses under different material types.

[0063] For example, for the absorption layer of the same material, a predetermined absorption layer of different deposition thicknesses can be plated on the mask substrate at multiple predetermined angles. The stress meter is used to measure the surface shape of the mask before and after the predetermined absorption layer is plated. The stress meter will calculate the stress of the plated layer on the substrate according to the change in the curvature of the mask surface before and after the coating. Then, the stress of the required absorption layer is fitted to obtain the stress-inclination curve, and then the corresponding stress control route is formulated: the relative angle between the mask substrate and the target material is changed during ion beam deposition sputtering, so that the incident direction of the target particles and the mask substrate present a certain inclination angle to offset the influence of the absorption layer stress on the mask surface shape.

[0064] Based on the above operations, for different materials, the stress-tilt curve of the predetermined absorption layer of different material types at different thicknesses can be obtained. Subsequently, based on the stress-tilt curve, the sputtering tilt angle corresponding to different materials or different thicknesses can be quickly determined. Different materials may have different stress types. The appropriate sputtering tilt angle can be selected according to the absorption layer material and thickness to achieve the preparation of a high-density, low-stress mask absorption layer.

[0065] In some embodiments of the present disclosure, the size of the predetermined inclination angle may be 10° to 60°. The angle step may be preset at intervals, and different inclination angles may be selected for inclined deposition. For example, the angle step is 5°, and the selected predetermined angles are 5°, 10°, 15°, 20°, etc. The size of the predetermined angle may be selected in advance according to the material of the absorption layer.

[0066] In some embodiments of the present disclosure, the material of the actual absorption layer may include one of Cr, Ta, Mo, MoSi and MoTa, that is, the material of the predetermined absorption layer may include one of Cr, Ta, Mo, MoSi and MoTa.

[0067] In some embodiments of the present disclosure, the actual absorption layer thickness may be 38 nm to 42 nm, that is, the predetermined absorption layer thickness may be in the range of 38 nm to 42 nm, such as 38 nm, 39 nm, 40 nm, 41 nm, 42 nm, preferably 40 nm.

[0068] The embodiment of the present disclosure also provides a method for preparing a mask, which may include:

[0069] The absorption layer of the mask is prepared by adopting the method for preparing the absorption layer of the mask.

[0070] When the deformation amount and / or the surface shape PV of the mask substrate surface meets the preset conditions, the mask plate is prepared.

[0071] The specific details of preparing the absorption layer of the mask are not described here. After the preparation of the absorption layer is completed, the actual stress of the absorption layer on the mask substrate and the surface deformation or surface shape PV of the mask substrate are verified. If they meet the requirements, other subsequent processing is performed to obtain a mask that meets the requirements in terms of stress and surface shape.

[0072] An embodiment of the present disclosure further provides a mask plate, which is prepared by the above-mentioned mask plate preparation method. The implementation details of this embodiment can be found in the aforementioned embodiment part and will not be repeated here.

[0073] In order to more clearly illustrate the effectiveness of the above-mentioned method for preparing the mask absorption layer, some specific examples are given below for illustration.

[0074] Embodiment 1

[0075] In this embodiment, stress-inclination curves of different material types are obtained at a predetermined deposition thickness.

[0076] In this embodiment, the predetermined deposition thickness of the absorption layer is set to 40 nm, and Cr, Ta, and Mo are used as the materials of the absorption layer to deposit the absorption layer on the mask substrate, and the stress-inclination curves corresponding to Cr, Ta, and Mo are obtained respectively when the predetermined deposition thickness of the absorption layer is 40 nm.

[0077] The absorption layer is deposited on the mask substrate by an ion beam assisted deposition method, and the auxiliary gas used may include Ar or Xe.

[0078] Figure 3 The stress-inclination curve diagram corresponding to the absorption layer formed by different types of materials with the same predetermined deposition thickness in the embodiment of the present disclosure is schematically shown.

[0079] like Figure 3As shown in the figure, for the same predetermined deposition thickness, the stress-inclination curves corresponding to the absorption layer formed by different types of materials can be different; when the material type of the absorption layer is the same, but the auxiliary gas used is different, the obtained stress-inclination curves can be different. As the deposition inclination angle increases, the stress of the absorption layer generally shows an increasing trend.

[0080] For example, for the same deposition inclination angle, the stress magnitude of the absorption layer formed by Cr is greater than that of the absorption layer formed by Mo, and the stress magnitude of the absorption layer formed by Mo is greater than that of the absorption layer formed by Ta.

[0081] For another example, for the absorption layer formed by Cr and Mo, under the same deposition inclination angle, the stress magnitude of the absorption layer formed by deposition using Xe as the auxiliary gas is greater than the stress magnitude of the absorption layer formed by deposition using Ar as the auxiliary gas. For the absorption layer formed by Ta, under the same deposition inclination angle, the stress magnitude of the absorption layer formed by deposition using Xe as the auxiliary gas is less than the stress magnitude of the absorption layer formed by deposition using Ar as the auxiliary gas.

[0082] Based on the stress-tilt curve, the inclination angle corresponding to the predetermined stress range can be quickly and accurately selected according to the material type of the actual absorption layer and the deposition thickness of the actual absorption layer, and the actual absorption layer can be deposited on the surface of the mask substrate at the inclination angle corresponding to the predetermined stress range, thereby accurately regulating the stress size of the actual absorption layer, and further controlling the deformation amount and / or surface shape PV of the mask substrate surface.

[0083] Embodiment 2

[0084] In this embodiment, in order to solve the problem of mask shape change caused by the stress of the Cr layer (absorption layer), the results of Example 1 can be used to select a suitable sputtering inclination angle to reduce the stress of the film layer, and the stress value of the deposited Cr layer at different angles can be measured by adjusting the relative angle between the substrate and the target material.

[0085] Table 1 shows the stress measurement values ​​of the Cr film layer at different sputtering tilt angles.

[0086] Table 1

[0087]

[0088] Figure 4A The stress diagram of the Cr film layer when the deposition inclination angle is 60° according to an embodiment of the present disclosure is schematically shown. Figure 4B The stress diagram of the Cr film layer when the deposition inclination angle is 48° according to an embodiment of the present disclosure is schematically shown. Figure 4C The stress diagram of the Cr film layer when the deposition inclination angle is 30° according to an embodiment of the present disclosure is schematically shown. Figure 4DThe stress diagram of the Cr film layer when the deposition inclination angle is 20° according to an embodiment of the present disclosure is schematically shown. Figure 4E The stress diagram of the Cr film layer when the deposition tilt angle is 10° according to an embodiment of the present disclosure is schematically shown.

[0089] As shown in Table 1 and Figure 4A-4E As shown, when the deposition inclination angle is 20°, the stress value of the Cr layer drops to +93.81MPa, meeting the stress index requirements of +50MPa~+200MPa.

[0090] Embodiment 3

[0091] On the basis of the first and second embodiments, the same process is used to perform stress control on the mask substrate for multiple times.

[0092] Figure 5 The diagram schematically shows the result of repeatability verification of the Cr film stress control process according to an embodiment of the present disclosure.

[0093] like Figure 5 As shown, the method for preparing the mask absorption layer provided in the embodiment of the present disclosure has a certain process stability, and the film layers prepared in different batches can meet the stress index requirements of +50 MPa~+200 MPa.

[0094] Embodiment 4

[0095] In this embodiment, a 40 nm Cr film layer needs to be deposited on a 3-inch square quartz mask substrate as an absorption layer, and the PV variation in the central 10×10 mm area needs to be small.

[0096] Table 2 shows the effect of the stress control scheme on the change of PV of the 3-inch mask surface before and after coating.

[0097] Table 2

[0098]

[0099] Fig. 6A The figure schematically shows the surface shape of the mask substrate when the deposition inclination angle is 60° according to an embodiment of the present disclosure. Figure 6B The figure schematically shows the surface shape of the mask substrate when the deposition inclination angle is 48° according to an embodiment of the present disclosure. Figure 6C The figure schematically shows the surface shape of the mask substrate when the deposition inclination angle is 30° according to an embodiment of the present disclosure. Fig.6D The figure schematically shows the surface shape of the mask substrate when the deposition inclination angle is 20° according to an embodiment of the present disclosure. Fig. 6E The figure schematically shows the surface shape of the mask substrate when the deposition inclination angle is 10° according to an embodiment of the present disclosure.

[0100] As shown in Table 2 and Figure 6A-6EAs shown, the mask absorption layer preparation method of the disclosed embodiment suppresses the influence of Cr film stress on the deformation of the 3-inch mask, and the substrate PV change before and after coating at each angle is controlled at about 5nm. When the deposition inclination angle is 20°, the minimum substrate PV change can be controlled at about 3nm, which can meet the subsequent processing requirements.

[0101] Embodiment 5

[0102] In this embodiment, a 6-inch square quartz mask substrate thinned at the center needs to deposit a 40 nm Cr absorption layer. Because the center of the substrate is thin, it is necessary to ensure that the PV change before and after the coating is small to prevent the substrate from deformation and damage. Among them, the film stress range is required to be +50 MPa ~ +200 MPa, the deposition tilt angle range is preferably 15°~25°, and the actual process uses 20°, and the process gas is Ar.

[0103] Table 3 schematically shows the effect of the above stress control scheme on the change of the PV of the 6-inch center-thinned mask surface before and after coating.

[0104] Table 3

[0105]

[0106] Fig. 7A The initial surface shape of a whole 6-inch center-thinned mask substrate before coating according to an embodiment of the present disclosure is schematically shown. Figure 7B The figure schematically shows the topography of a whole 6-inch center-thinned mask substrate after coating according to an embodiment of the present disclosure. Fig. 8A The initial surface diagram of the 26 mm×33 mm standard field of the 6-inch center-thinned mask substrate before coating according to the embodiment of the present disclosure is schematically shown. Figure 8B The figure schematically shows the post-coating topography of a 26 mm×33 mm standard field of a 6-inch center-thinned mask substrate according to an embodiment of the present disclosure.

[0107] As shown in Table 3, Fig. 7A , Figure 7B , Fig. 8A , Figure 8B As shown, the mask absorption layer preparation method of the disclosed embodiment suppresses the deformation of the 6-inch center-thinned mask caused by the stress of the Cr film layer, and the PV change of the entire substrate before and after coating is controlled to be about 20 nm, and the PV of the 26 mm×33 mm standard field in the center of the front side can be controlled to be about 2 nm. The influence of the absorption layer deposition step on the position error accuracy of the mask and the line width uniformity of the high-resolution pattern is reduced to a negligible level.

[0108] In summary, the above experimental data fully verify that angle sputtering can effectively reduce the stress of the Cr film layer and reduce the change of mask surface shape caused by the stress of the Cr film layer, providing a good foundation for technical indicators such as mask direct writing pattern position error and CDU control.

[0109] The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present disclosure in detail. It should be understood that the above are only preferred embodiments of the present disclosure and the technical principles used. Those skilled in the art will understand that the present disclosure is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present disclosure. Therefore, although the present disclosure is described in more detail through the above embodiments, the present disclosure is not limited to the above embodiments, and may also include more other equivalent embodiments without departing from the concept of the present disclosure, all of which belong to the protection scope of the present disclosure.

Claims

1. A method for preparing a mask absorption layer, characterized in that: include: obtaining a mask substrate; An actual absorption layer is prepared on the surface of the mask substrate by ion beam deposition, wherein the relative angle between the mask substrate and the target material during ion beam deposition is changed to adjust the inclination angle between the incident direction of the target particles required for preparing the actual absorption layer and the direction perpendicular to the surface of the mask substrate, thereby regulating the stress of the actual absorption layer and controlling the deformation amount and / or surface shape PV of the mask substrate surface.

2. The method according to claim 1, characterized in that Also includes: Obtaining a first surface shape of a mask substrate having no predetermined absorption layer formed on the surface; Predetermined absorption layers with different predetermined deposition thicknesses are prepared on the mask substrate at a plurality of predetermined relative angles, respectively, to obtain second surface shapes of respective mask substrates with predetermined absorption layers with respective predetermined deposition thicknesses formed on the surface; Calculating the stress of the predetermined absorption layer corresponding to the predetermined deposition thickness on the surface of the mask substrate according to the curvature change between the second surface shape corresponding to each predetermined absorption layer of the predetermined deposition thickness and the first surface shape; Fitting the stress magnitude of the predetermined absorption layer with each predetermined deposition thickness on the surface of the mask substrate at a plurality of predetermined relative angles to form stress-inclination curves corresponding to the predetermined absorption layers with different deposition thicknesses; The above operation is repeated to obtain stress-inclination curves of predetermined absorption layers of different material types at different deposition thicknesses.

3. The method according to claim 1, characterized in that Also includes: Obtaining a first surface shape of a mask substrate having no predetermined absorption layer formed on the surface; Predetermined absorption layers of different material types are prepared on the mask substrate at a plurality of predetermined relative angles, respectively, to obtain second surface shapes of the mask substrates each having a predetermined absorption layer of each predetermined material type formed on the surface; Calculating the stress of the predetermined absorption layer of the predetermined material type on the surface of the mask substrate according to the curvature change between the second surface shape corresponding to the predetermined absorption layer of each predetermined material type and the first surface shape; Fitting the stress magnitude of the predetermined absorption layer of each predetermined material type on the surface of the mask substrate at a plurality of predetermined relative angles to form stress-inclination curves corresponding to the predetermined absorption layers of different material types; The above operation is repeated to obtain stress-inclination curves of predetermined absorption layers with different deposition thicknesses under different material types.

4. The method according to claim 2 or 3, characterized in that: By changing the relative angle between the mask substrate and the target material during ion beam deposition, the inclination angle between the incident direction of the target particles required for preparing the absorption layer and the surface of the mask substrate is adjusted, including: Based on the stress-tilt curve, according to the material type of the actual absorption layer and the deposition thickness of the actual absorption layer, the tilt angle corresponding to the predetermined stress range is selected and the actual absorption layer is deposited on the surface of the mask substrate at the tilt angle corresponding to the predetermined stress range to form the actual absorption layer.

5. The method according to claim 2 or 3, characterized in that: The material of the actual absorption layer includes one of Cr, Ta, Mo, MoSi and MoTa.

6. The method according to claim 2 or 3, characterized in that: The actual absorption layer has a thickness of 38 nm to 42 nm.

7. The method according to claim 2 or 3, characterized in that: The predetermined inclination angle is between 10° and 60°.

8. The method according to any one of claims 1 to 3, characterized in that: The material of the mask substrate includes sapphire or fused quartz.

9. A method for preparing a mask, characterized in that: The absorption layer of the mask is prepared by the preparation method according to any one of claims 1 to 8; When the deformation amount and / or the surface shape PV of the mask substrate surface meets the preset conditions, the mask plate is prepared.

10. A mask, characterized in that: The mask is prepared by the preparation method according to claim 9.

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