Roughness optimization method and device

Abstract

The invention discloses a roughness optimization method and device, and the method comprises the following steps: providing a mask plate, depositing a protection layer on the mask plate, and enabling the protection layer to cover a light-transmitting region of the mask plate; a shading material with a first preset thickness is deposited on the side wall of a shading layer of the mask plate through atomic layer deposition, so that pits in the side wall of the shading layer are at least partially filled, and the roughness of the side wall of the shading layer is reduced; etching a shading material with a second preset thickness on the side wall of the shading layer of the mask plate through atomic layer etching so as to at least partially remove the bulges on the shading layer and reduce the roughness of the side wall of the shading layer; the roughness of the surface of the shading pattern is detected, and the detected roughness is compared with a preset roughness set value; and when the detected roughness of the surface of the shading pattern reaches a roughness set value, the protection layer is removed. According to the invention, the line edge roughness of the mask plate can be effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuit manufacturing, and in particular to a method and device for optimizing the edge roughness of a mask line. Background Art

[0002] With the development of integrated circuit technology, the critical dimension (CD) of semiconductor devices is getting smaller and smaller, and the exposure wavelength has also developed from ultraviolet (UV), deep ultraviolet (DUV) to extreme ultraviolet (EUV). Therefore, in order to meet the requirements of high-precision chip preparation, the mask for lithography needs to be precisely processed during its preparation.

[0003] At present, the characteristic dimension (CD) of the chip has been reduced to a few nanometers, but its line edge roughness (LER) does not decrease in the same proportion as the CD decreases. During the mask manufacturing process, especially during the patterning of the mask's light shielding layer, the side wall of the light shielding layer will be uneven, which is called line edge roughness (LER). If the LER of the mask is unqualified, it will be directly transferred to the wafer, thereby affecting the imaging of the wafer. Its impact on device performance is becoming more and more prominent. For example, when the gate characteristic dimension of a CMOS field effect transistor is less than 100nm, the gate line edge roughness in the range of 5nm will cause a significant change in the effective conductive channel length of the device, causing the performance of the device to degrade or fluctuate: the leakage current increases, the drive current decreases, and the turn-on voltage Vth changes. Therefore, the control of LER is one of the basic problems that urgently need to be solved in chip manufacturing. LER mainly comes from the photolithography and etching processes, such as the diversity of polymer molecular structures, fluctuations in spatial imaging, acidic diffusion of photoresists, and production and preparation process conditions (such as coating thickness, drying temperature, exposure dose, and uniformity of light intensity of the light source).

[0004] In general, in order to reduce the line edge roughness (LER) of the mask in the existing technology, the LER is mainly reduced by optimizing the electron beam and etching process. For example, using a better electron beam, a better photoresist, a better etching method and process, etc. In addition, multiple electron beam direct writing and etching can be used to gradually approach the ideal line accuracy. Although existing solutions can reduce the LER of the mask to a certain extent, these methods are often costly, inefficient, and difficult to meet the needs of higher precision in the future. In addition, these methods may be limited by physical limits when processing very fine lines, making it difficult to further improve the accuracy.

[0005] Therefore, a new technical solution is urgently needed to optimize the line edge roughness of the mask shielding layer, thereby improving the imaging accuracy on the wafer. Summary of the invention

[0006] The object of the present invention is to provide a method and device for optimizing the roughness of a mask light-shielding layer, so as to solve the technical problem of high line edge roughness of the existing mask light-shielding layer.

[0007] In order to solve the above technical problems, the present invention provides a method for optimizing the roughness of a mask light shielding layer, comprising: providing a mask; Depositing a protective layer on the mask so that the protective layer covers the light-transmitting area of ​​the mask; Depositing a light-shielding material of a first preset thickness on the sidewall of the light-shielding layer of the mask by atomic layer deposition to at least partially fill the pits on the sidewall of the light-shielding layer and reduce the roughness of the sidewall of the light-shielding layer; Etching a second preset thickness of light shielding material on the sidewall of the light shielding layer of the mask by atomic layer etching to at least partially remove protrusions on the light shielding layer and reduce the roughness of the sidewall of the light shielding layer; Detecting the roughness of the side wall of the light shielding layer, and comparing the detected roughness of the side wall of the light shielding layer with a preset roughness setting value; When the detected roughness of the side wall of the light shielding layer reaches a set roughness value, the protective layer is removed.

[0008] The above-mentioned method for optimizing the roughness of the light-shielding layer of the mask provides a mask, which includes a light-shielding layer and a light-transmitting area, deposits a protective layer on the mask so that the protective layer covers the light-transmitting area of ​​the mask, so that the protective layer protects the light-transmitting area of ​​the mask from being affected by the atomic layer deposition and atomic layer etching described below, and then deposits a light-shielding material of a first preset thickness on the side wall of the light-shielding layer of the mask by atomic layer deposition, and utilizes the physical property of conformal growth of atomic layer deposition, and the pits on the side walls of the light-shielding layer are easy to grow light-shielding material in the pits due to their inwardly concave shape, especially when the thickness of the light-shielding material grown at the pits is half of the spacing between the two sides of the pits, the pits can be completely filled, so the thickness of the light-shielding material grown at the pits is greater than the first preset thickness, and the thickness of the light-shielding material grown at the protrusions is less than the first preset thickness, so that at least part of the light-shielding material can be filled. The pits on the side walls of the light-shielding layer are partially filled to reduce the roughness of the side walls of the light-shielding layer; then, the side walls of the light-shielding layer of the mask are etched with a second preset thickness of light-shielding material by atomic layer etching, and the physical property of conformal removal of atomic layer etching is utilized. Since the protruding area protrudes outward due to its shape, it is easy to remove the light-shielding material in the protruding area. Therefore, the thickness removed at the protrusion is greater than the second preset thickness, and the thickness removed at the pit is less than the second preset thickness. Therefore, the protrusions on the light-shielding layer can be at least partially removed to reduce the roughness of the side walls of the light-shielding layer; finally, the roughness of the side walls of the light-shielding layer is detected, and the detected roughness of the side walls of the light-shielding layer is compared with a preset roughness setting value. When the detected roughness of the side walls of the light-shielding layer reaches the roughness setting value, the protective layer is removed to complete the roughness optimization of the light-shielding layer of the mask.

[0009] The above method can make the pits and protrusions on the side walls of the mask light-shielding layer gradually flat during atomic layer deposition and atomic layer etching, reduce the roughness of the side walls of the mask light-shielding layer, and effectively solve the technical problem of high line edge roughness of the mask in the prior art.

[0010] Optionally, in the roughness optimization method, a photoresist layer is reserved above the light shielding layer.

[0011] Optionally, in the roughness optimization method, before the step of depositing a light-shielding material of a first preset thickness on the sidewall of the light-shielding layer of the mask by atomic layer deposition, the following steps are further included: removing the photoresist layer on the top of the light-shielding material layer; or, The step of removing the protective layer also includes the following step: removing the photoresist layer.

[0012] Optionally, in the roughness optimization method, after the step of detecting the roughness of the side wall of the light shielding layer and comparing the detected roughness of the side wall of the light shielding layer with a preset roughness setting value, the following steps are further included: When the detected roughness of the side wall of the light-shielding layer does not reach the preset roughness setting value, repeat the steps of depositing a first preset thickness of light-shielding material on the side wall of the light-shielding layer of the mask by atomic layer deposition to the step of comparing the detected roughness of the side wall of the light-shielding layer with the preset roughness setting value.

[0013] Optionally, in the roughness optimization method, after the step of depositing a light-shielding material of a first preset thickness on the sidewall of the light-shielding layer of the mask by atomic layer deposition, the following steps are included: Detecting the roughness of the side wall of the light shielding layer, and comparing the detected roughness of the side wall of the light shielding layer with a preset roughness setting value; When the detected roughness of the side wall of the light shielding layer reaches a set roughness value, the protective layer is removed.

[0014] Optionally, in the roughness optimization method, the temperature of atomic layer deposition is not less than 100°.

[0015] Optionally, in the roughness optimization method, the temperature of atomic layer deposition is no greater than 300°.

[0016] Optionally, in the roughness optimization method, the material of the protective layer is SiNx.

[0017] Optionally, in the roughness optimization method, the thickness of the protective layer is no greater than half the thickness of the light shielding layer; and / or, The first preset thickness and the second preset thickness are both no greater than 10 nm.

[0018] Based on the same inventive concept, the present invention also provides a device for implementing any of the above roughness optimization methods, characterized in that it comprises: A transfer chamber, a deposition chamber, an etching chamber, a detection chamber and a manipulator are provided adjacent to each other in sequence. The manipulator is used to transfer the mask between the transfer chamber, the deposition chamber, the etching chamber and the detection chamber.

[0019] The above-mentioned device is used to implement the above-mentioned roughness optimization method of the mask light-shielding layer. The device reduces the roughness of the side walls of the mask light-shielding layer by making the pits and protrusions on the side walls of the mask light-shielding layer gradually flat during atomic layer deposition and atomic layer etching, thereby effectively solving the technical problem of high line edge roughness of the mask in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the process of optimizing the roughness of a mask light shielding layer according to an embodiment; Figure 2 It is a structural schematic diagram of a roughness optimization device for a mask light shielding layer according to an embodiment.

[0021] Explanation of the reference numerals: 1 - mask, 2 - transfer chamber, 3 - robot arm, 4 - deposition chamber, 5 - etching chamber, 6 - detection chamber. 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] The present invention discloses a method and device for optimizing the roughness of a mask light shielding layer, which can optimize the line edge roughness of the mask light shielding layer to meet the high-precision chip manufacturing requirements. The method and device can be used to optimize masks in semiconductor manufacturing processes, which can be, but are not limited to, binary masks, OMOG masks, etc.

[0025] See also Figure 1 A method for optimizing the roughness of a mask light shielding layer, characterized in that it comprises the following steps: Step S1: providing a mask.

[0026] Specifically, the mask base includes a transparent substrate, a light-shielding layer and a photoresist layer. The mask is formed after the mask base is subjected to electron beam direct writing, development and etching. The light-shielding layer is patterned during the manufacturing process of the mask. During the patterning process, part of the light-shielding layer is etched to expose the transparent substrate to form a light-transmitting area. Among them, due to the etching, the side wall of the light-shielding layer is easily affected by adverse factors and becomes uneven, resulting in greater line edge roughness of the side wall of the light-shielding layer.

[0027] Furthermore, the material of the transparent substrate may be a quartz glass substrate, an ultra-low expansion glass substrate, etc.; or any substrate for a mask known to those skilled in the art. The patterned light-shielding layer is composed of light-shielding patterns such as dots, lines or figures of different shapes, and the light-shielding layer is a thin film composed of a metal substance of a transition metal. Preferably, the material of the light-shielding layer may be, but is not limited to, silicon compounds, chromium compounds and chromium metals, such as MoSi, MoSiON, MoSiCON, CrN, CrO, CrCO, CrCN, Cr, etc. Of course, in other embodiments, the material of the light-shielding layer may also be selected from other light-shielding materials known to those skilled in the art, and this embodiment does not specifically limit this.

[0028] Step S2: depositing a protective layer on the mask so that the protective layer covers the light-transmitting area of ​​the mask.

[0029] Specifically, a protective layer is deposited on the mask so that the protective layer covers the light-transmitting area of ​​the mask, thereby protecting the light-transmitting area of ​​the mask from being affected by the atomic layer deposition and atomic layer etching described below.

[0030] Step S3: depositing a light-shielding material of a first preset thickness on the sidewalls of the light-shielding layer of the mask by atomic layer deposition to at least partially fill the pits on the sidewalls of the light-shielding layer and reduce the roughness of the sidewalls of the light-shielding layer.

[0031] Specifically, a light-shielding material of a first preset thickness is deposited on the side wall of the light-shielding layer of the mask through atomic layer deposition. Atomic layer deposition is a technology that deposits the light-shielding material on the surface layer by layer in the form of a single atomic film based on chemical vapor. The physical characteristics of conformal growth of atomic layer deposition are utilized. The pits on the side wall of the light-shielding layer are concave inwardly due to their shape, and it is easy for the light-shielding material to grow in the pits. In particular, when the thickness of the light-shielding material grown at the pits is half of the spacing between the two sides of the pits, the pits can be completely filled. Therefore, the thickness of the light-shielding material grown at the pits is greater than the first preset thickness, and the thickness of the light-shielding material grown at the protrusions is less than the first preset thickness. Therefore, the pits on the side wall of the light-shielding layer can be at least partially filled to reduce the roughness of the side wall of the light-shielding layer. Of course, the light-shielding material is used to repair the roughness of the side wall of the light-shielding layer. Therefore, the composition of the light-shielding material is set to perform the same function as the light-shielding layer. Preferably, for the light-shielding layer composed of chromium compounds, the light-shielding material can be metallic chromium or carbon, etc.

[0032] In a specific embodiment, the atomic layer deposition of the light-shielding material chromium has a thickness of 10 nm, 0.08 Å / cycle, a chamber pressure of 8 m bar-12 m bar, a temperature of 180° C., and is performed in an environment of 99.9995% purity of nitrogen.

[0033] Step S4: etching the sidewalls of the light shielding layer of the mask plate with a second preset thickness of light shielding material by atomic layer etching to at least partially remove the protrusions on the light shielding layer and reduce the roughness of the sidewalls of the light shielding layer.

[0034] Specifically, the side walls of the light-shielding layer of the mask are etched with a second preset thickness of light-shielding material through atomic layer etching. Atomic layer etching is a technology that uses a series of self-limiting reactions to etch thin films, which is similar to the concept of layer-by-layer growth of atomic layer deposition. As the reverse process of atomic layer deposition technology, atomic layer etching is a technology that removes material layer by layer. The physical property of conformal removal of atomic layer etching is utilized. The light-shielding material in the protruding area is easily removed due to its outward protruding shape. Therefore, the thickness removed at the protrusion is greater than the second preset thickness, and the thickness removed at the pit is less than the second preset thickness. Therefore, the protrusions on the light-shielding layer can be at least partially removed, thereby reducing the roughness of the side walls of the light-shielding layer.

[0035] In a specific embodiment, the thickness of the chromium light shielding material is 10 nm, the time is 20 s / cycle, and the background pressure of the chamber is 2.0×10 -5 Torr, the process pressure is 2.0 mTorr, and the chamber environment is 50 sccm of O2 and 50 sccm of Cl2.

[0036] Step S5: Detecting the roughness of the side wall of the light shielding layer, and comparing the detected roughness of the side wall of the light shielding layer with a preset roughness setting value.

[0037] Specifically, the line edge roughness of the side wall of the light shielding layer is detected by using a characteristic size scanning electron microscope, and the detected line edge roughness of the side wall of the light shielding layer is compared with a preset roughness setting value.

[0038] Furthermore, for the process node of 22nm chip manufacturing, the line edge roughness of the mask light shielding layer is no more than 4nm, and for the process node of 14nm chip manufacturing, the line edge roughness of the mask light shielding layer is no more than 0.5nm.

[0039] Step S6: When the detected roughness of the side wall of the light shielding layer reaches the roughness setting value, the protective layer is removed.

[0040] Specifically, when the detected line edge roughness of the side wall of the light shielding layer reaches a preset roughness setting value, the edge roughness of the light shielding layer has met the requirement, and finally the protective layer above the light-transmitting area of ​​the mask is removed.

[0041] Furthermore, the detection of the roughness of the side walls of the light-shielding layer can be added before and after the deposition of a first preset thickness of light-shielding material on the side walls of the light-shielding layer of the mask through atomic layer deposition in step S3, and can also be simultaneously added before and after the etching of a second preset thickness of light-shielding material on the side walls of the light-shielding layer of the mask through atomic layer etching in step S4. By detecting the roughness of the side walls of the light-shielding layer, the first preset thickness of the light-shielding material deposited on the side walls of the light-shielding layer in step S3 and the second preset thickness of the light-shielding material etching on the side walls of the light-shielding layer in step S4 can be set.

[0042] Furthermore, the feature size of the mask is also detected while the line edge roughness of the side wall of the light-shielding layer is detected using a feature size scanning electron microscope. If there is a deviation in the feature size of the mask, atomic layer deposition and atomic layer etching of the light-shielding material can be performed on the side wall of the light-shielding layer of the mask to make the feature size of the mask meet the requirements.

[0043] The above-mentioned method for optimizing the roughness of the light-shielding layer of the mask provides a mask, which includes a light-shielding layer and a light-transmitting area, deposits a protective layer on the mask so that the protective layer covers the light-transmitting area of ​​the mask, so that the protective layer protects the light-transmitting area of ​​the mask from being affected by the atomic layer deposition and atomic layer etching described below, and then deposits a light-shielding material of a first preset thickness on the side wall of the light-shielding layer of the mask by atomic layer deposition, and utilizes the physical property of conformal growth of atomic layer deposition, and the pits on the side walls of the light-shielding layer are easy to grow light-shielding material in the pits due to their inwardly concave shape, especially when the thickness of the light-shielding material grown at the pits is half of the spacing between the two sides of the pits, the pits can be completely filled, so the thickness of the light-shielding material grown at the pits is greater than the first preset thickness, and the thickness of the light-shielding material grown at the protrusions is less than the first preset thickness, so that at least part of the light-shielding material can be filled. The pits on the side walls of the light-shielding layer are partially filled to reduce the roughness of the side walls of the light-shielding layer; then, the side walls of the light-shielding layer of the mask are etched with a second preset thickness of light-shielding material by atomic layer etching, and the physical property of conformal removal of atomic layer etching is utilized. Since the protruding area protrudes outward due to its shape, it is easy to remove the light-shielding material in the protruding area. Therefore, the thickness removed at the protrusion is greater than the second preset thickness, and the thickness removed at the pit is less than the second preset thickness. Therefore, the protrusions on the light-shielding layer can be at least partially removed to reduce the roughness of the side walls of the light-shielding layer; finally, the roughness of the side walls of the light-shielding layer is detected, and the detected roughness of the side walls of the light-shielding layer is compared with a preset roughness setting value. When the detected roughness of the side walls of the light-shielding layer reaches the roughness setting value, the protective layer is removed to complete the roughness optimization of the light-shielding layer of the mask. The above method can make the pits and protrusions on the side walls of the mask light-shielding layer gradually flat during atomic layer deposition and atomic layer etching, reduce the roughness of the side walls of the mask light-shielding layer, and effectively solve the technical problem of high line edge roughness of the mask in the prior art.

[0044] In one embodiment, a photoresist layer is reserved above the light shielding layer.

[0045] Specifically, in the process of forming a mask from a mask base, the photoresist layer is first patterned, and then the pattern of the photoresist layer is transferred to the light-shielding layer using the patterned photoresist layer as a mask. Therefore, there is a photoresist layer above the light-shielding layer remaining on the transparent substrate. The common practice in the industry is often to remove the photoresist layer, but in this embodiment, the photoresist layer above the light-shielding layer is reserved, so that in the next step of depositing a protective layer on the mask, the protective layer is deposited on the photoresist layer above the light-shielding layer.

[0046] In one embodiment, before the step of depositing a light shielding material of a first preset thickness on the sidewall of the light shielding layer of the mask by atomic layer deposition, the following steps are also included: removing the photoresist layer on the top of the light shielding material layer; or, The step of removing the protective layer also includes the following step: removing the photoresist layer.

[0047] Specifically, a photoresist layer is reserved above the light-shielding layer. After a protective layer is deposited on the mask, the photoresist layer above the light-shielding layer is removed, so that the protective layer above the photoresist layer is removed together with the photoresist layer, so that the protective layer is only deposited on the light-transmitting area of ​​the mask. Then, a step of depositing a light-shielding material of a first preset thickness on the side wall of the light-shielding layer of the mask is performed through atomic layer deposition. This can prevent the photoresist layer remaining above the light-shielding layer from softening and flowing due to the temperature during atomic layer deposition, thereby avoiding defects.

[0048] In another embodiment, the photoresist layer reserved above the light shielding layer is removed after the light shielding layer roughness optimization is completed. Specifically, the photoresist layer reserved above the light shielding layer is formed on both the light-transmitting area of ​​the mask and the photoresist layer above the light shielding layer after the protective layer is deposited on the mask. In order to prevent the photoresist layer from being affected by the temperature during atomic layer etching, a high-temperature resistant photoresist can be used or the temperature during atomic layer etching can be controlled to simplify the process flow.

[0049] In one embodiment, after the step of detecting the roughness of the side wall of the light shielding layer and comparing the detected roughness of the side wall of the light shielding layer with a preset roughness setting value, the following steps are also included: When the detected roughness of the side wall of the light-shielding layer does not reach the preset roughness setting value, repeat the steps of depositing a first preset thickness of light-shielding material on the side wall of the light-shielding layer of the mask by atomic layer deposition to the step of comparing the detected roughness of the side wall of the light-shielding layer with the preset roughness setting value.

[0050] Specifically, when the line edge roughness of the side wall of the light-shielding layer detected by a feature-size scanning electron microscope does not reach a preset roughness setting value, steps S3, S4 and S5 are repeated to further reduce the line edge roughness of the side wall of the light-shielding layer until it meets the preset roughness setting value. More specifically, when the preset roughness setting value cannot be met after atomic layer deposition of a first preset thickness of the light-shielding material and atomic layer etching of a second preset thickness on the mask light-shielding layer, the atomic layer deposition of a first preset thickness of the light-shielding material and atomic layer etching of a second preset thickness on the mask side wall can be repeated to further reduce the roughness of the side wall of the mask layer until the detected roughness of the side wall of the mask light-shielding layer reaches the preset roughness setting value.

[0051] Furthermore, the first preset thickness of the first atomic layer deposition of light-shielding material on the sidewall of the light-shielding layer is d1, the second preset thickness of the first atomic layer etching of the light-shielding material on the sidewall of the light-shielding layer is d2, the first preset thickness of the second repetition of atomic layer deposition of light-shielding material on the sidewall of the light-shielding layer is d1', the second preset thickness of the second repetition of atomic layer etching of the light-shielding material on the sidewall of the light-shielding layer is d2', the first preset thickness of the third repetition of atomic layer deposition of light-shielding material on the sidewall of the light-shielding layer is d1'', the second preset thickness of the third repetition of atomic layer etching of the light-shielding material on the sidewall of the light-shielding layer is d2'', and so on, wherein the thicknesses of d1, d1' and d1'' may be the same or different, preferably, d1 is greater than d1', and d1' is greater than d1'', wherein the thicknesses of d2, d2' and d2'' may be the same or different, preferably, d2 is greater than d2', and d2' is greater than d2''.

[0052] Furthermore, each time the atomic layer deposition and atomic layer etching of the light shielding material are performed on the sidewall of the light shielding layer, the first preset thickness and the second preset thickness are both set so as not to affect the characteristic size of the mask.

[0053] In one embodiment, after the step of depositing a light shielding material of a first preset thickness on the sidewall of the light shielding layer of the mask by atomic layer deposition, the following steps are included: Detecting the roughness of the side wall of the light shielding layer, and comparing the detected roughness of the side wall of the light shielding layer with a preset roughness setting value; When the detected roughness of the side wall of the light shielding layer reaches a set roughness value, the protective layer is removed.

[0054] Specifically, after a first preset thickness of light-shielding material is deposited on the side wall of the light-shielding layer of the mask through atomic layer deposition, due to the physical characteristics of conformal growth of atomic layer deposition, the pits on the side wall of the light-shielding layer are easy to grow light-shielding material in the pits because of their inwardly concave shape, especially when the thickness of the light-shielding material grown at the pits is half of the spacing between the two sides of the pits, the pits can be completely filled. Therefore, the thickness of the light-shielding material grown at the pits is greater than the first preset thickness, and the thickness of the light-shielding material grown at the protrusions is less than the first preset thickness. The pits and protrusions on the side wall of the light-shielding layer gradually tend to be flat, so the roughness of the side wall of the light-shielding layer is reduced. At this time, a characteristic dimension scanning electron microscope is used to detect the roughness of the side wall of the light-shielding layer. If the detected roughness of the side wall of the light-shielding layer reaches the set value, the protective layer is removed to complete the roughness optimization of the light-shielding layer. The roughness detection is performed after the atomic layer deposition of the side wall of the light-shielding layer. If the roughness meets the requirement at this time, the protective layer can be removed, thereby simplifying the roughness optimization process and saving resources.

[0055] In one embodiment, the temperature of the atomic layer deposition is not less than 100° C. Specifically, when the temperature of the atomic layer deposition is 100° C. and above, water vapor, which is usually used as one of the reactants, evaporates quickly from the substrate and the wall, so when the temperature of 100° C. and above is used, the circulation speed between the precursors will be faster and the effect of the atomic layer deposition will be better.

[0056] In one embodiment, the temperature of the atomic layer deposition is no greater than 300° C. Specifically, a photoresist layer is left above the light shielding layer, and after depositing the protective layer, the atomic layer deposition and atomic layer etching are performed. In order to prevent the temperature during the atomic layer deposition from affecting the photoresist layer to soften and flow and cause defects, the temperature of the atomic layer deposition is no greater than 300° C.

[0057] In one embodiment, the material of the protective layer is SiNx. Specifically, the material of the protective layer needs to have a large etching selectivity with the transparent substrate, and the transparent substrate below the light-transmitting area can be unaffected during the deposition and removal of the protective layer. Since SiNx has a good etching selectivity with respect to quartz, a conventional transparent substrate material, the material of the protective layer is preferably SiNx. If there are other materials with a good etching selectivity with respect to the transparent substrate, they can also be used, which will not be described in detail here. In a specific embodiment, the method of depositing SiNx is ICPCVD (inductively coupled plasma chemical vapor deposition), the power is 800W, the pressure is 5Pa-15Pa, the temperature is 80℃-130℃, the chamber environment is 7sccm to 20sccm of NH3, 146sccm of SiH4 (doped with 5% He), 139sccm of Ar, and the time is 38nm / min-52nm / min; the method of removing SiNx is to use reactive ion etching, using 17sccm of CF4, 3sccm of H2, the chamber pressure is 10mT, and the power is 100w.

[0058] In one embodiment, the thickness of the protective layer is no greater than half the thickness of the light shielding layer; and / or, The first preset thickness and the second preset thickness are both no greater than 10 nm.

[0059] Specifically, since the protective layer is deposited on the light-transmitting area, the side walls of the protective layer deposited in the light-transmitting area are adjacent to and abut against the side walls of the light-shielding layer. Therefore, the portion of the side walls of the protective layer covering the side walls of the light-shielding layer has not been roughness optimized. In order to ensure the range of roughness optimization of the side walls of the light-shielding layer, the roughness of the side walls of the light-shielding layer is optimized as much as possible, and the thickness of the protective layer cannot be greater than half of the thickness of the light-shielding layer.

[0060] Specifically, the first preset thickness of the atomic layer deposition light-shielding material and the second preset thickness of the atomic layer etching light-shielding material are no more than 10 nm. Since the roughness optimization is performed on the side wall of the light-shielding layer, the thickness of the deposited and etched light-shielding material cannot exceed the distance between any two light-shielding layer patterns to be optimized (that is, the characteristic size of the mask). Therefore, the thickness of the deposited and etched light-shielding material is no more than 10 nm and is set according to the characteristic sizes of different light-shielding layers.

[0061] See also Figure 2 On the other hand, the present invention also provides a device for a roughness optimization method, characterized in that it includes: a transfer chamber 2, a deposition chamber 4, an etching chamber 5, a detection chamber 6 and a manipulator 3, the transfer chamber 2, the deposition chamber 4, the etching chamber 5, and the detection chamber 6 are arranged adjacent to each other in sequence, and the manipulator 3 is used to transfer the mask 1 between the transfer chamber 2, the deposition chamber 4, the etching chamber 5 and the detection chamber 6.

[0062] Specifically, the mask 1 on which the protective layer is deposited is placed in the transfer chamber 2, and the robot 3 is used to transfer the mask 1 in the transfer chamber 1 to the adjacent deposition chamber 4, etching chamber 5 and detection chamber 6. First, the robot 3 transfers the mask 1 to the deposition chamber 4 to perform atomic layer deposition of the light-shielding material on the side wall of the light-shielding layer, and then the robot 3 transfers the mask 1 to the etching chamber 5 to perform atomic layer etching of the light-shielding material on the side wall of the light-shielding layer. Then, the robot 3 transfers the mask 1 to the detection chamber 6 to perform roughness detection on the side wall of the mask light-shielding layer. If the detected roughness of the light-shielding layer reaches a preset roughness setting value, then The mask 1 is transferred to the transfer chamber 2 by the robot 3, and the protective layer is removed after the mask 1 is finally taken out; if the roughness of the light-shielding layer detected does not reach the roughness setting value, the mask 1 is transferred to the deposition chamber 4, the etching chamber 5 and the detection chamber 6 in sequence by the robot 3, and the atomic layer deposition of the light-shielding material on the side wall of the light-shielding layer, the atomic layer etching of the light-shielding material on the side wall of the light-shielding layer and the roughness detection of the side wall of the light-shielding layer are repeated until the roughness of the side wall of the light-shielding layer detected reaches the preset roughness setting value, and the mask 1 is transferred to the transfer chamber 2 by the robot 3, and the protective layer is removed after the mask 1 is finally taken out. Furthermore, the robot 3 is used to transfer the mask 1 in each adjacently arranged transfer chamber 2, deposition chamber 4, etching chamber 5 and detection chamber 6, as long as the robot 3 is set to be able to transfer in each adjacently arranged chamber, it will not be repeated here.

[0063] Furthermore, the robot 3 can be configured to add the process of transferring the mask 1 to the detection chamber 6 for roughness detection to before and after the mask 1 enters the deposition chamber 5 for atomic layer deposition of the light-shielding material and enters the etching chamber 6 for atomic layer etching of the light-shielding material. When the roughness detected by any of the above-mentioned detection chambers 6 reaches the roughness set value, the robot 3 transfers the mask 1 to the transfer chamber 2, and finally takes out the mask 1 and removes the protective layer. In this embodiment, as long as the roughness of the light-shielding layer detected by the detection chamber 6 reaches the set value, the mask 1 is transferred to the transfer chamber 2 and removed. This can simplify the roughness optimization process and help improve the roughness optimization efficiency.

[0064] The above-mentioned device is used to implement the above-mentioned roughness method of the mask light-shielding layer. The device reduces the roughness of the side walls of the mask light-shielding layer by making the pits and protrusions on the side walls of the mask light-shielding layer gradually flat during atomic layer deposition and atomic layer etching, thereby effectively solving the technical problem of high line edge roughness of the mask in the prior art.

[0065] The above description is only a description of the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any changes and 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 roughness optimization method, characterized in that: include: providing a mask; Depositing a protective layer on the mask so that the protective layer covers the light-transmitting area of ​​the mask; Depositing a light-shielding material of a first preset thickness on the sidewall of the light-shielding layer of the mask by atomic layer deposition to at least partially fill the pits on the sidewall of the light-shielding layer and reduce the roughness of the sidewall of the light-shielding layer; Etching a second preset thickness of light-shielding material on the sidewall of the light-shielding layer of the mask by atomic layer etching, so as to at least partially remove protrusions on the light-shielding layer and reduce the roughness of the sidewall of the light-shielding layer; Detecting the roughness of the side wall of the light shielding layer, and comparing the detected roughness of the side wall of the light shielding layer with a preset roughness setting value; When the detected roughness of the side wall of the light shielding layer reaches the roughness setting value, the protection layer is removed.

2. The roughness optimization method according to claim 1, characterized in that: A photoresist layer is reserved above the light shielding layer.

3. The roughness optimization method according to claim 2, characterized in that: Before the step of depositing a light-shielding material of a first preset thickness on the sidewall of the light-shielding layer of the mask by atomic layer deposition, the step further includes: removing the photoresist layer on the top of the light-shielding material layer; or, The step of removing the protective layer further comprises the following step: removing the photoresist layer.

4. The roughness optimization method according to claim 1, characterized in that: After the step of detecting the roughness of the side wall of the light shielding layer and comparing the detected roughness of the side wall of the light shielding layer with a preset roughness setting value, the following steps are also included: When the detected roughness of the side wall of the light-shielding layer does not reach the preset roughness setting value, repeat the step of depositing a first preset thickness of light-shielding material on the side wall of the light-shielding layer of the mask by atomic layer deposition to the step of comparing the detected roughness of the side wall of the light-shielding layer with the preset roughness setting value.

5. The roughness optimization method according to claim 1, characterized in that: After the step of depositing a light-shielding material of a first preset thickness on the sidewall of the light-shielding layer of the mask by atomic layer deposition, the following steps are included: Detecting the roughness of the side wall of the light shielding layer, and comparing the detected roughness of the side wall of the light shielding layer with a preset roughness setting value; When the detected roughness of the side wall of the light shielding layer reaches the roughness setting value, the protection layer is removed.

6. The roughness optimization method according to claim 1, characterized in that: The temperature of the atomic layer deposition is not less than 100°C.

7. The roughness optimization method according to claim 6, characterized in that: The temperature of the atomic layer deposition is no greater than 300°C.

8. The roughness optimization method according to claim 1, characterized in that: The material of the protection layer is SiNx.

9. The roughness optimization method according to claim 1, characterized in that: The thickness of the protective layer is no greater than half the thickness of the light shielding layer; and / or, The first preset thickness and the second preset thickness are both no greater than 10 nm.

10. A device for implementing the roughness optimization method according to any one of claims 1 to 9, characterized in that: include: A transfer chamber, a deposition chamber, an etching chamber, a detection chamber and a manipulator, wherein the transfer chamber, the deposition chamber, the etching chamber and the detection chamber are arranged adjacent to each other in sequence, and the manipulator is used to transfer the mask between the transfer chamber, the deposition chamber, the etching chamber and the detection chamber.

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