Method for manufacturing OMOG mask substrate

Abstract

The invention provides a manufacturing method of an OMOG mask substrate. The manufacturing method comprises the following steps: providing a transparent substrate; sequentially and alternately depositing a silicon layer and a molybdenum layer on the transparent substrate to form a molybdenum-silicon stacked layer; heat treatment is carried out on the molybdenum-silicon stacked layer, so that Mo atoms in the molybdenum layer completely move into the silicon layer to form a molybdenum silicide layer, and the molybdenum silicide layer has a preset thickness, preset Mo and Si contents and a preset Mo atom distribution gradient; the silicon layer and the molybdenum layer are deposited through a thin film deposition technology, and the thin film deposition technology controls the thickness of the silicon layer and the thickness of the molybdenum layer according to the preset thickness, the preset Mo and Si content and the preset Mo atom distribution gradient. According to the manufacturing method of the OMOG mask substrate, the thickness of the molybdenum silicide layer can be reduced to the maximum extent, the light absorbance can be improved to the maximum extent, the development requirement of an OMOG photomask can be met, and the manufacturing cost of the OMOG photomask can be saved.

Description

Technical Field

[0001] The invention relates to the technical field of integrated circuit manufacturing, and in particular to a method for manufacturing an OMOG mask substrate. Background Art

[0002] With the introduction of ultra-large numerical aperture 193nm lithography machines, the size of the patterns on the mask is getting smaller and smaller. Studies have found that the thicker the Cr used to block light on the mask, the stronger the interaction between the light wave and Cr, causing the optimal focus value during exposure to shift with the size of the pattern. This phenomenon is called the mask three-dimensional effect. In order to reduce the mask three-dimensional effect, molybdenum silicide (MoSi) with higher optical density (OD) is used as the material for the absorption layer. This mask using high optical density MoSi material as the absorption layer is called an opaque MoSi mask (opaque MoSi on glass, OMOG).

[0003] OMOG uses MoSi as the absorption layer. The molybdenum silicide layer provides sufficient optical density and has a high extinction coefficient (k). A very thin molybdenum silicide layer can effectively block light with a wavelength of 193nm, which can reduce the three-dimensional effect of the mask that plagues ultra-large numerical aperture immersion lithography, thereby improving pattern fidelity and resolution. In addition, the MoSi material has excellent etching performance. Ion etching can well achieve vertical side walls, which helps to provide excellent CD uniformity in the final product; in addition, the MoSi film itself has very little stress, which is of great advantage in improving the flatness of the mask and reducing the offset of the pattern. In short, the OMOG photomask has finer resolution, higher fidelity, tighter CD uniformity and better alignment.

[0004] In recent years, in order to make the molybdenum silicide layer fully absorb ultraviolet light under thinner conditions, an OMOG mask substrate based on multi-layer MoSi has been developed. The multi-layer MoSi has different molybdenum and silicon contents so that each layer has different optical parameters (n, k). The reflected light between the interfaces of the multi-layer molybdenum silicide layers increases, which can improve the absorption rate, so that ultraviolet light can be fully absorbed under thinner conditions. Thinner molybdenum silicide layers can reduce edge morphology effects, effectively avoid distortion, uneven peak intensity, and unequal sidelobe width caused by edge morphology effects, and can achieve better resolution and contrast.

[0005] However, the prior art uses a sputtering deposition process to form the molybdenum silicide layer of the OMOG photomask. The molybdenum and silicon contents in the MoSi film formed by sputtering deposition are fixed and the molybdenum and silicon materials are evenly distributed. The content of the single-layer molybdenum silicide layer is fixed, and the multi-layer molybdenum silicide layer can only increase the reflected light at the interface between the layers. The ability of the multi-layer molybdenum silicide layer to increase the reflected light is limited, so that although the multi-layer molybdenum silicide layer can increase the reflected light and improve the absorptivity to a certain extent, it cannot achieve the development goal of the minimum thickness and the highest absorptivity of the molybdenum silicide layer required by the OMOG photomask. In addition, the Mo and Si contents of the MoSi target material used in the sputtering deposition process are fixed, and it is difficult to adjust the Mo and Si contents in the MoSi film formed by the sputtering deposition process by adjusting the process parameters. The MoSi film with different Mo and Si contents can only be formed by replacing the MoSi target material with different Mo and Si contents. The manufacture of the OMOG photomask requires the use of multiple MoSi targets with different Mo and Si contents, and the raw material cost is high, which seriously affects the manufacturing cost of the OMOG photomask. Therefore, the traditional OMOG mask substrate manufacturing process cannot meet the development needs of OMOG photomasks, and the process cost is high, which affects the technical problem of OMOG photomask manufacturing cost. Summary of the invention

[0006] The purpose of the present invention is to provide a method for manufacturing an OMOG mask substrate to solve the technical problems that the traditional OMOG mask substrate manufacturing process cannot meet the development needs of OMOG photomasks and the process cost is high, which affects the manufacturing cost of OMOG photomasks.

[0007] To achieve the above object, the present invention provides a method for manufacturing an OMOG mask substrate, comprising the following steps: providing a transparent substrate; Alternatingly depositing silicon layers and molybdenum layers on a transparent substrate to form a molybdenum-silicon stacked layer; Thermally treating the molybdenum-silicon stacked layer so that the Mo atoms in the molybdenum layer are completely moved into the silicon layer to form a molybdenum silicide layer, wherein the molybdenum silicide layer has a preset thickness, preset Mo and Si contents, and a preset Mo atomic distribution gradient; The silicon layer and the molybdenum layer are deposited by a thin film deposition process, and the thin film deposition process controls the thickness of the silicon layer and the molybdenum layer respectively according to a preset thickness, a preset Mo and Si content, and a preset Mo atomic distribution gradient.

[0008] The manufacturing method of the above-mentioned OMOG mask base plate first deposits a silicon layer and a molybdenum layer on a transparent substrate in sequence to form a molybdenum-silicon stacked layer. During the deposition process, the thickness of the silicon layer and the molybdenum layer is controlled according to the preset thickness of the preset molybdenum silicide layer, the preset Mo and Si content, and the preset Mo atomic distribution gradient. After the molybdenum-silicon stacked layer is deposited, the molybdenum-silicon stacked layer is subjected to rapid thermal annealing treatment so that the Mo atoms in the molybdenum layer are completely moved to the silicon layer to form a molybdenum silicide layer. This method can adjust the thickness of the finally formed molybdenum silicide layer, the content of Mo and Si in the molybdenum silicide layer, and the distribution gradient of Mo atoms by controlling the thickness of the deposited silicon layer and the molybdenum layer. The molybdenum silicide layer can form a change in the overall continuous molybdenum-silicon composition. The distribution of Mo atoms in the molybdenum silicide layer changes in a gradient, which can form a layer of internal reflection to repeatedly absorb ultraviolet light, so that the reflected light between the interfaces of the multi-layer molybdenum silicide layers can be repeatedly absorbed by each layer, and the light absorption rate can be maximized. Moreover, the manufacturing method of the above-mentioned OMOG mask substrate enables Mo atoms to completely move into the silicon layer and completely consume the molybdenum layer to form a molybdenum silicide layer. According to calculation, the thickness of the molybdenum silicide layer increased on the surface of the original silicon layer is only 1% of the thickness of the original molybdenum layer. The thickness of the final molybdenum silicide layer is almost equal to the thickness of the original silicon layer. The thickness of the molybdenum silicide layer can be well controlled by controlling the thickness of the original molybdenum layer and the silicon layer. Therefore, the manufacturing method of the above-mentioned OMOG mask substrate can reduce the thickness of the molybdenum silicide layer as much as possible while improving the absorbance, and can well achieve the development goal of the minimum thickness of the molybdenum silicide layer and the highest absorbance required by the OMOG photomask.

[0009] In addition, the above-mentioned method for manufacturing the OMOG mask substrate can form a molybdenum silicide layer with any Mo and Si content as needed. Only one elemental molybdenum target and one elemental silicon target are needed to form a plurality of molybdenum silicide layers with different Mo and Si contents. There is no need to prepare a plurality of MoSi targets with different Mo and Si contents, which can effectively reduce the cost of raw materials and greatly save the manufacturing cost of the OMOG photomask.

[0010] In summary, the above-mentioned OMOG mask substrate manufacturing method can minimize the thickness of the molybdenum silicide layer and maximize the absorbance, and can achieve the development goal of minimum thickness of the molybdenum silicide layer and maximum absorbance required for the OMOG photomask. In addition, the above-mentioned OMOG mask substrate manufacturing method can effectively reduce the process cost, which is conducive to saving the OMOG photomask manufacturing cost.

[0011] In one of the embodiments, after the step of forming the molybdenum silicide layer, the method further includes the following step: coating a photoresist on the molybdenum silicide layer.

[0012] In one embodiment, the heat treatment temperature is 400°C to 800°C.

[0013] In one embodiment, the heat treatment time is 10 min to 30 min.

[0014] In one embodiment, the step of heat treating the molybdenum-silicon stacked layer comprises: Performing a rapid thermal annealing process on the molybdenum-silicon stacked layer; or, The molybdenum-silicon stacked layer is scanned by a laser or an electron beam.

[0015] In one embodiment, the thickness of the silicon layer and the thickness of the molybdenum layer are both no greater than 30 nm.

[0016] In one embodiment, the preset Mo and Si contents are such that the content of Mo atoms is not greater than 50% of the content of Si atoms.

[0017] In one embodiment, the preset Mo and Si contents are such that the content of Mo atoms is 30% to 45% of the content of Si atoms.

[0018] In one embodiment, the thin film deposition process includes a sputtering deposition process or an atomic layer deposition process.

[0019] In one embodiment, after the step of forming a molybdenum silicide layer with a preset Mo and Si content, the step of implanting at least one of nitrogen atoms, oxygen atoms or carbon atoms into the molybdenum silicide layer is further included. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of a process for manufacturing an OMOG mask blank according to an embodiment of the present invention; Figures 2 to 6 The schematic structural diagram of an embodiment of the present invention is a schematic diagram of an OMOG photomask manufactured by using the method for manufacturing an OMOG mask blank of the present invention.

[0021] Description of reference numerals: 10 - transparent substrate, 20 - silicon layer, 30 - molybdenum layer, 40 - molybdenum silicon stacked layer, 50 - molybdenum silicide layer, 60 - photoresist layer, 70 - OMOG mask base, 80 - patterned molybdenum silicide layer, 90 - light-transmitting area, 100 - OMOG photomask. DETAILED DESCRIPTION

[0022] In the following description, a large number of specific details are given in order to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features known in the art are not described. It should be understood that the present invention can be implemented in different forms and should not be interpreted as being limited to the embodiments presented here. On the contrary, providing these embodiments will make the disclosure thorough and complete, and fully convey the scope of the present invention to those skilled in the art. The same reference numerals represent the same elements from beginning to end. It should be understood that when a layer is referred to as being formed on other layers, it can be directly formed on other layers, or there can be an intervening film layer. Among them, the orientation or positional relationship indicated by the terms "upper", "lower", "front", "back" and the like is based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention, wherein "longitudinal" can be understood as a direction perpendicular to the substrate surface, and "lateral" can be understood as a direction parallel to the substrate surface. When used herein, the singular forms "a", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "include" is used to determine the presence of features, steps, operations, elements and / or parts, but does not exclude the presence or addition of one or more other features, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items. The terms "same", "equal" and "consistent" include completely equal and identical meanings, and may also include approximately the same or approximately equal meanings under allowed process errors. The terms "first" "second" and the like in the specification are used to distinguish between similar elements, and are not necessarily used to describe a specific order or time sequence. It is to be understood that, where appropriate, these terms used in this way are interchangeable, for example, so that the embodiments of the present invention described herein can be operated in other orders different from those described or shown herein. Similarly, if the method described herein includes a series of steps, the order in which the steps are presented herein is not necessarily the only order in which the steps can be performed, and some of the steps described may be omitted and / or some other steps not described herein may be added to the method. If components in a certain figure are the same as components in other figures, although these components can be easily identified in all figures, in order to make the description of the figures clearer, this specification will not mark all the same component numbers in each figure.

[0023] The present invention is described more clearly and completely below by way of embodiments in conjunction with the accompanying drawings, but the present invention is not limited to the scope of the following embodiments.

[0024] Please also see Figures 1 to 6 The manufacturing method of the OMOG mask blank 7070 of one embodiment comprises the following steps: Step S11: providing a transparent substrate 10 .

[0025] Specifically, Figure 2 As shown, a transparent substrate 1010 is first provided. The transparent substrate 1010 includes one of a quartz substrate, a soda lime substrate, a borosilicate substrate, an aluminum silicate substrate, a silicon substrate, and a silicon carbide substrate. The radial dimension of the transparent substrate 101 is between 1 inch and 100 inches, and the thickness is between 0.1 mm and 200 mm. For example, in this embodiment, the transparent substrate 10 can be a quartz substrate, and its radial dimension can be 4 inches, 6 inches, 8 inches, 12 inches, etc.

[0026] Step S12: Alternately depositing silicon layers 20 and molybdenum layers 30 on the transparent substrate 10 in sequence to form a molybdenum-silicon stacked layer 40 .

[0027] In one embodiment, the silicon layer 20 and the molybdenum layer 30 are deposited by a thin film deposition process such as a sputtering deposition process or an atomic layer deposition process. Both the sputtering deposition process and the atomic layer deposition process have a high controllability of the thickness of the deposited film, and can accurately control the thickness of the deposited silicon layer 20 and the molybdenum layer 30. In specific practical applications, a specific thin film deposition process can be selected as needed. This embodiment is not specifically limited. For the convenience of description, this embodiment is described by taking the sputtering deposition process to deposit the silicon layer 20 and the molybdenum layer 30 as an example. Specifically, the sputtering deposition process preferably adopts a low-temperature DC magnetron sputtering process. The sputtering deposition process uses an inert gas (helium and / or argon) to bombard the corresponding silicon target material or molybdenum target material so that the material is deposited on the transparent substrate 10 to form the corresponding silicon layer 20 or molybdenum layer 30. The silicon target material uses a single silicon target material including amorphous silicon and a purity of at least 99.99%, and the molybdenum target material uses a single molybdenum target material including amorphous molybdenum and a purity of at least 99.99%. Furthermore, the preset Mo and Si contents are the ratios of the Mo content and the Si content in the molybdenum silicide layer 50 to be formed. Before the sputtering deposition process, the thicknesses of the silicon layer 20 and the molybdenum layer 30 are calculated according to the preset thickness of the molybdenum silicide layer 50 to be formed, the preset Mo and Si contents, and the preset Mo atomic distribution gradient, and the target thicknesses of the silicon layer 20 and the molybdenum layer 30 are obtained. During the sputtering deposition process, the deposition time is controlled according to the calculated thicknesses of the silicon layer 20 and the molybdenum layer 30, and the silicon layer 20 and the molybdenum layer 30 are deposited to form the target thicknesses.

[0028] Furthermore, the sputtering deposition process first deposits the silicon layer 20 on the transparent substrate 10, and then deposits the molybdenum layer 30. When only one molybdenum silicide layer 50 needs to be formed, the silicon layer 20 and the molybdenum layer 30 are sequentially deposited on the transparent substrate 10. When multiple molybdenum silicide layers 50 need to be formed, the silicon layer 20 and the molybdenum layer 30 are alternately deposited on the transparent substrate 10 to form a molybdenum-silicon stacked layer 40 having at least three layers. In the molybdenum-silicon stacked layer 40 having at least three layers, the uppermost layer and the lowermost layer are both silicon layers 20, and the molybdenum layer 30 is located between two adjacent silicon layers 20. Figure 3 As shown, in this embodiment, the need to form two layers of molybdenum silicide layers 50 is taken as an example. When the need to form two layers of molybdenum silicide layers 50 is to form a three-layer structure of molybdenum-silicon stacked layers 40 is deposited on the transparent substrate 10. In the three-layer structure, the bottom layer and the top layer are both silicon layers 20, and the molybdenum layer 30 is located between the two silicon layers 20. Specifically, the first silicon layer 20 is first deposited on the transparent substrate 10. After the film thickness of the first silicon layer 20 reaches the target thickness, the molybdenum layer 30 is deposited on the surface of the first silicon layer 20. After the film thickness of the molybdenum layer 30 reaches the target thickness, the second silicon layer 20 is deposited on the film surface. After the film thickness of the second silicon layer 20 reaches the target thickness, the deposition operation is completed, and step S13 is executed.

[0029] Step S13: heat-treating the molybdenum-silicon stacked layer 40 to completely move the Mo atoms in the molybdenum layer 30 into the silicon layer 20 to form a molybdenum silicide layer 50 having a preset thickness, preset Mo and Si contents, and a preset Mo atomic distribution gradient.

[0030] Specifically, the ratio of the Mo content to the Si content in the molybdenum silicide layer 50 depends on the relative amount of the Mo atoms in the molybdenum layer 30 and the Si atoms in the silicon layer 20, and the thickness of the molybdenum layer 30 determines the number of Mo atoms, and the thickness of the silicon layer 20 determines the number of Si atoms. In step S12, the thickness of the silicon layer 20 and the molybdenum layer 30 is first controlled according to the preset Mo and Si contents required for the molybdenum silicide layer 50 to be formed, and after the molybdenum silicon stacking layer 40 is heat-treated, the Mo atoms are completely moved to the silicon layer 20, so that the molybdenum layer 30 is completely consumed to form a molybdenum silicide layer 50 with preset Mo and Si contents. Further, after the molybdenum silicon stacking layer 40 is heat-treated, the Mo atoms in the molybdenum layer 30 move from near to far into the silicon layer 20, so that the Mo atoms are distributed in a gradient in the formed molybdenum silicide layer 50. More specifically, the preset Mo and Si contents in this embodiment are the average contents of Mo and Si in the molybdenum silicide layer 50. The Mo atoms in the molybdenum silicide layer 50 are distributed in a gradient, from the side close to the original molybdenum layer 30 to the side far away from the original molybdenum layer 30, the content of Mo atoms is distributed from high to low, the Mo atom content on the side close to the original molybdenum layer 30 is slightly higher than the Mo atom content in the preset Mo and Si contents, and the Mo atom content on the side far away from the original molybdenum layer 30 is slightly lower than the Mo atom content in the preset Mo and Si contents, and the average content of Mo atoms in the molybdenum silicide layer 50 is equal to the Mo atom content in the preset Mo and Si contents. Furthermore, it has been calculated that after the Mo atoms are completely moved into the silicon layer 20 to completely consume the molybdenum layer 30 to form the molybdenum silicide layer 50, the increased thickness of the molybdenum silicide layer 50 on the surface of the original silicon layer 20 is only 1% of the thickness of the original molybdenum layer 30. The final thickness of the molybdenum silicide layer 50 is almost equal to the thickness of the original silicon layer 20. By controlling the thickness of the original molybdenum layer 30 and the silicon layer 20, the thickness of the molybdenum silicide layer 50 can be well controlled.

[0031] The Mo atoms in the molybdenum silicide layer 50 formed by the manufacturing method of the OMOG mask substrate of this embodiment have a gradient distribution, which can form intralayer reflection and repeated absorption of ultraviolet light, and can improve the light absorption rate. The method is used to make multiple layers of molybdenum silicide layers 50 with different Mo and Si contents, which can increase the reflected light at the interlayer interface of the multiple layers of molybdenum silicide layers 50, and the repeated absorption of ultraviolet light by the intralayer reflection of each layer of molybdenum silicide layer 50 can make the reflected light between the interfaces of the multiple layers of molybdenum silicide layers 50 be repeatedly absorbed by each layer, which can maximize the light absorption rate. Figure 4As shown, in this embodiment, the molybdenum-silicon stacked layer 40 with a three-layer structure is heat-treated so that the Mo atoms in the middle molybdenum layer 30 are respectively moved to the silicon layers 20 on both sides to form two molybdenum silicide layers 50. In this embodiment, two molybdenum silicide layers 50 are formed by heat-treating the molybdenum-silicon stacked layer 40 with a three-layer structure, and the thickness of the deposited molybdenum layer 30 and the two adjacent silicon layers 20 are controlled according to the preset thickness, preset Mo and Si content, and preset Mo atomic distribution gradient of the upper and lower molybdenum silicide layers 50 to be formed, so as to ensure that the upper and lower molybdenum silicide layers 50 formed have the preset thickness, preset Mo and Si content, and preset Mo atomic distribution gradient. When more molybdenum silicide layers 50 need to be formed, the thickness of each silicon layer 20 and molybdenum layer 30 is determined according to the preset thickness, preset Mo and Si content, and preset Mo atomic distribution gradient of the multiple molybdenum silicide layers 50, so as to ensure that the formed multiple molybdenum silicide layers 50 meet the preset thickness, preset Mo and Si content, and preset Mo atomic distribution gradient requirements.

[0032] In one embodiment, in order to achieve the overall optimal light absorption rate of the multi-layer molybdenum silicide layer 50, the thickness of the silicon layer 20 on both sides of the molybdenum layer 30 is preferably opposite, that is, the thickness of the silicon layer 20 on one side of the molybdenum layer 30 is thinner, and the thickness of the silicon layer 20 on the other side of the molybdenum layer 30 is thicker. The thickness of the silicon layer 20 on both sides of the molybdenum layer 30 is different. After heat treatment, the thinner silicon layer will first reach the preset Mo and Si content level, and the entry of Mo atoms will slow down, but Mo atoms will still enter the thicker silicon layer 30 on the other side until the molybdenum layer is completely exhausted. At this time, the formation of multiple molybdenum silicide layers 50 with different Mo and Si contents increases the interlayer interface reflection light, and further superimposes the intra-layer reflection of each layer of molybdenum silicide layer 50 to repeatedly absorb ultraviolet light, which can achieve the optimal light absorption rate.

[0033] The manufacturing method of the OMOG mask substrate of the present embodiment can control the film thickness, Mo and Si content, and Mo atomic distribution gradient of the formed molybdenum silicide layer 50 by controlling the thickness of the original silicon layer 20 and the molybdenum layer 30. The film thickness, Mo and Si content, and Mo atomic distribution gradient of the molybdenum silicide layer 50 are simple and convenient to adjust.

[0034] The manufacturing method of the above-mentioned OMOG mask substrate first deposits a silicon layer 20 and a molybdenum layer 30 on a transparent substrate in sequence to form a molybdenum-silicon stacked layer 40. During the deposition process, the thickness of the silicon layer 20 and the molybdenum layer 30 are controlled according to a preset thickness of the preset molybdenum silicide layer 50, a preset Mo and Si content, and a preset Mo atomic distribution gradient. After the deposition of the molybdenum-silicon stacked layer 40 is completed, the molybdenum-silicon stacked layer 40 is subjected to a rapid thermal annealing treatment so that the Mo atoms in the molybdenum layer 30 are completely moved to the silicon layer 20 to form a molybdenum silicide layer 50. The method can adjust the thickness of the finally formed molybdenum silicide layer 50, the content of Mo and Si in the molybdenum silicide layer 50 and the distribution gradient of Mo atoms by controlling the thickness of the deposited silicon layer 20 and the molybdenum layer 30. The molybdenum silicide layer 50 can form a change in the overall continuous molybdenum-silicon composition. The distribution of Mo atoms in the molybdenum silicide layer 50 shows a gradient change, which can form intra-layer reflection and repeated absorption of ultraviolet light, so that the reflected light between the interfaces of the multi-layer molybdenum silicide layers 50 can be repeatedly absorbed by each layer, which can maximize the absorbance. Moreover, the manufacturing method of the above-mentioned OMOG mask substrate enables Mo atoms to completely move into the silicon layer 20 and completely consume the molybdenum layer to form a molybdenum silicide layer 50. The thickness of the molybdenum silicide layer 50 increased on the surface of the original silicon layer 20 is only 1% of the thickness of the original molybdenum layer 30. The thickness of the final molybdenum silicide layer 50 is almost equal to the thickness of the original silicon layer 20. The thickness of the molybdenum silicide layer 50 can be well controlled by controlling the thickness of the original molybdenum layer 30 and the silicon layer 20. Therefore, the manufacturing method of the above-mentioned OMOG mask substrate can reduce the thickness of the molybdenum silicide layer 50 as much as possible while improving the absorbance, and can well achieve the development goal of the molybdenum silicide layer 50 with the minimum thickness and the highest absorbance required by the OMOG photomask.

[0035] In addition, the above-mentioned method for manufacturing the OMOG mask substrate can control the Mo and Si contents of the formed molybdenum silicide layer 50 by adjusting the thickness of the original silicon layer 20 and the molybdenum layer 30, and can form a molybdenum silicide layer 50 with any Mo and Si content as needed. Only one elemental molybdenum target and one elemental silicon target are needed to form a plurality of molybdenum silicide layers 50 with different Mo and Si contents. There is no need to prepare a plurality of MoSi targets with different Mo and Si contents, which can effectively reduce the cost of raw materials and greatly save the manufacturing cost of the OMOG photomask.

[0036] In one embodiment, the preset Mo and Si contents are such that the content of Mo atoms is not greater than 50% of the content of Si atoms. Specifically, the preset Mo and Si contents of the molybdenum silicide layer 50 are determined in advance according to the target optical parameters of the molybdenum silicide layer of the OMOG photomask. To avoid excessive Mo atom content and increase the thickness of the molybdenum silicide layer 50, the content of Mo atoms in the molybdenum silicide layer 50 is not greater than 50% of the content of Si atoms. Further, to effectively control the thickness of the molybdenum silicide layer 50 and ensure that the content of Mo atoms in the molybdenum silicide layer 50 can meet the optical parameter requirements of the molybdenum silicide layer 50, it is preferred that the preset Mo and Si contents are such that the content of Mo atoms is 30% to 45% of the content of Si atoms.

[0037] In one embodiment, in order to reduce the edge morphology effect and effectively control the thickness of the finally formed molybdenum silicide layer 50, the thickness of the silicon layer 20 and the thickness of the molybdenum layer 30 in the molybdenum-silicon stacked layer 40 are both no greater than 30 nm. Further, in order to ensure that each layer of the multi-layer molybdenum silicide layer 50 meets the respective preset Mo and Si content requirements, the thickness of the silicon layer 20 and the thickness of the molybdenum layer 30 in the molybdenum-silicon stacked layer 40 are preferably no less than 10 nm.

[0038] In one embodiment, in order to react the molybdenum layer 30 with the silicon layer 20 and avoid evaporation of silicon and molybdenum materials, the temperature of the heat treatment is 400° C. to 800° C. At a temperature of 400° C. to 800° C., Mo atoms tend to move into the silicon layer 20 and form molybdenum silicide. Preferably, in order to ensure complete reaction of molybdenum and silicon, the temperature of the heat treatment is 500° C. to 800° C.

[0039] In one embodiment, the heat treatment time is 10min~30min. Specifically, it has been verified experimentally that after the molybdenum silicon stacking layer 40 is heat treated to consume the molybdenum layer 30, if the heating is continued for a long time, the Mo atoms in the molybdenum silicide layer 50 will be evenly distributed. Although the thickness of the molybdenum silicide layer 50 will not increase, the Mo atoms in the molybdenum silicide layer 50 will not be distributed in a gradient, and the molybdenum silicide layer 50 cannot absorb ultraviolet light by intralayer reflection, so that the optical absorption rate of the molybdenum silicide layer 50 is poor. Therefore, after the molybdenum layer 30 is consumed, the heating is stopped after adding 5%~10% of the heating time. In this embodiment, in order to ensure that the Mo atoms are completely moved to the silicon layer 20 to completely consume the molybdenum layer 30, and to ensure that the Mo atoms in the silicide layer 50 are distributed according to the preset Mo atom distribution gradient, the time for heat treatment of the molybdenum silicon stacking layer 40 is controlled to be 10min~30min.

[0040] In one embodiment, heat treating the molybdenum silicon stacking layer 40 includes heat treating the molybdenum silicon stacking layer 40 by rapid thermal annealing, wherein the rapid thermal treatment moves the Mo atoms in the molybdenum layer to the silicon layer 20 at a temperature of 400°C to 800°C and forms a molybdenum silicide layer, and the temperature of the rapid thermal annealing treatment is preferably 500°C to 800°C. Further, in one embodiment, in order to improve the activation rate and mobility of Mo atoms, the molybdenum silicon stacking layer 40 may be subjected to multiple rapid thermal annealing treatments to improve the efficiency of the rapid thermal annealing process. Preferably, in this embodiment, the molybdenum silicon stacking layer 40 is subjected to two rapid thermal annealing treatments, wherein the temperature of the first rapid thermal annealing treatment is 450°C and the temperature of the second rapid thermal annealing treatment is 550°C, and the molybdenum silicon stacking layer 40 is subjected to two thermal annealing treatments to quickly and completely move the Mo atoms to the silicon layer 20, thereby quickly forming a molybdenum silicide layer 50 having a preset Mo and Si content.

[0041] In another embodiment, the molybdenum silicon stacking layer 40 is heat treated by scanning the molybdenum silicon stacking layer with a laser or an electron beam, the energy and scanning speed of the laser or electron beam are controlled at a surface temperature of 400°C to 800°C, and the Mo atoms move to the silicon layer through the heat from the laser or electron beam to form a molybdenum silicide layer, preferably the energy and scanning speed of the laser or electron beam are controlled at a surface temperature of 500°C to 800°C. Further, in order to enable the Mo atoms to move quickly and completely to the silicon layer 20, the laser or electron beam is focused on the molybdenum layer, which helps to quickly form a molybdenum silicide layer 50 with a preset Mo and Si content. Furthermore, the scanning area of ​​the laser or electron beam is preferably not less than the area of ​​the molybdenum silicon stacking layer 40, and the laser or electron beam performs a planar scanning on the molybdenum silicon stacking layer 40 to ensure that the molybdenum silicon stacking layer 40 is heated evenly, to ensure that the molybdenum layer 30 and the silicon layer 20 react evenly, and to avoid local defects in the formed molybdenum silicide layer 50.

[0042] In one embodiment, after step S13, the following step is further included: coating a photoresist on the molybdenum silicide layer 50. Specifically, preferably, a photoresist is coated on the surface of the molybdenum silicide layer 50 by spin coating to form a photoresist layer 60, and the preparation of the OMOG mask substrate 70 is completed (eg, Figure 5 As shown). Further, after the preparation of the OMOG mask substrate 70 is completed, the OMOG photomask preparation step can be continued. First, the OMOG mask substrate 70 is exposed to form a photolithography pattern. Specifically, the photolithography pattern is written in the photoresist layer 60 by laser or electron beam, and then a part of the molybdenum silicide layer 50 is removed by development and etching processes to form a light-transmitting area 90. Finally, the photoresist layer 60 is removed to form a patterned molybdenum silicide layer 80, and the preparation of the OMOG photomask 100 is completed (as shown). Figure 6 as shown).

[0043] In one embodiment, after step S13, the following step may be further included: injecting at least one of nitrogen atoms, oxygen atoms or carbon atoms into the molybdenum silicide layer 50. In this embodiment, by injecting a small amount of at least one of nitrogen atoms, oxygen atoms or carbon atoms into the molybdenum silicide layer 50, the light absorption rate of the molybdenum silicide layer 50 can be further enhanced, and the adhesion between the molybdenum silicide layer 50 and the transparent substrate 10 interface can be enhanced.

[0044] The above-mentioned method for manufacturing the OMOG mask substrate can minimize the thickness of the molybdenum silicide layer and maximize the absorbance, and can achieve the development goal of minimizing the thickness of the molybdenum silicide layer and maximizing the absorbance required for the OMOG photomask. In addition, the above-mentioned method for manufacturing the OMOG mask substrate can effectively reduce the process cost, which is beneficial to saving the manufacturing cost of the OMOG photomask.

[0045] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of the technical solution of the present invention.

Claims

1. A method for manufacturing an OMOG mask blank, It is characterized in that The following steps are involved: providing a transparent substrate; Alternatingly depositing silicon layers and molybdenum layers on the transparent substrate in sequence to form a molybdenum-silicon stacked layer; Thermally treating the molybdenum-silicon stacked layer so that the Mo atoms in the molybdenum layer are completely moved into the silicon layer to form a molybdenum silicide layer, wherein the molybdenum silicide layer has a preset thickness, preset Mo and Si contents, and a preset Mo atomic distribution gradient; The silicon layer and the molybdenum layer are deposited by a thin film deposition process, and the thin film deposition process controls the thickness of the silicon layer and the molybdenum layer respectively according to the preset thickness, the preset Mo and Si contents, and the preset Mo atomic distribution gradient.

2. The method for manufacturing an OMOG mask blank according to claim 1, It is characterized in that After the step of forming the molybdenum silicide layer, the method further includes the following steps: coating a photoresist on the molybdenum silicide layer.

3. The method for manufacturing an OMOG mask blank according to claim 1, It is characterized in that The temperature of the heat treatment is 400°C to 800°C.

4. The method for manufacturing an OMOG mask blank according to claim 1, It is characterized in that The heat treatment time is 10 min to 30 min.

5. The method for manufacturing an OMOG mask blank according to claim 1, It is characterized in that The step of heat treating the molybdenum-silicon stacked layer comprises: Performing a rapid thermal annealing process on the molybdenum-silicon stacked layer; or, The molybdenum-silicon stacked layer is scanned by a laser or an electron beam.

6. The method for manufacturing an OMOG mask blank according to claim 1, It is characterized in that The thickness of the silicon layer and the thickness of the molybdenum layer are both no greater than 30 nm.

7. The method for manufacturing an OMOG mask blank according to claim 1, It is characterized in that The preset Mo and Si contents are such that the content of Mo atoms is not greater than 50% of the content of Si atoms.

8. The method for manufacturing an OMOG mask blank according to claim 7, It is characterized in that The preset Mo and Si contents are such that the content of Mo atoms is 30% to 45% of the content of Si atoms.

9. The method for manufacturing an OMOG mask blank according to claim 1, It is characterized in that The thin film deposition process includes a sputtering deposition process or an atomic layer deposition process.

10. The method for manufacturing an OMOG mask blank according to claim 1, It is characterized in that After the step of forming the molybdenum silicide layer with the preset Mo and Si contents, the method further includes the following step: injecting at least one of nitrogen atoms, oxygen atoms or carbon atoms into the molybdenum silicide layer.

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