Semiconductor device and method of forming vias thereof

Abstract

The present invention provides a semiconductor device and a method for forming a via hole thereof. The method includes: providing a first mask plate having a square hole pattern and a substrate including a substrate, a dielectric layer, and a photoresist layer stacked in sequence; processing the photoresist layer based on the first mask plate to form a first via hole in the photoresist layer, wherein one end of the first via hole away from the dielectric layer is circular and one end close to the dielectric layer is square; etching the dielectric layer using the photoresist layer as a second mask plate to form a cylindrical second via hole in the dielectric layer. The above technical solution avoids the problem of poor product reliability, especially the problem of electromigration performance failure, caused by the sharp corners of the rectangular holes of the large-size via hole pattern formed during the photolithography process due to the square hole pattern of the mask plate, improves the yield of the product, and saves the manufacturing cost.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and particularly to a semiconductor device and a method for forming a via thereof. Background Art

[0002] Chip designers generally prefer to draw the pattern of the mask plate in the shape of a square hole. During the photolithography process, it is necessary to ensure the fidelity of the mask plate pattern. Therefore, the top and bottom patterns of the photoresist after exposure and development are also in the shape of square holes. Then, through etching, the photoresist pattern is transferred to the dielectric layer, and finally a through hole in the shape of a cuboid is presented.

[0003] For the case of relatively small vias, the current mainstream technology is to use optical proximity correction to modify the designer's square hole pattern into a round hole shape and then manufacture the mask plate, so that the pattern of the mask plate is a round hole shape. However, for large-size via patterns (patterns with a size greater than 0.5 microns), generally no optical proximity correction scheme has been established. Therefore, the pattern on the mask plate is still in the shape of a square hole. However, the hole corners of the cuboid-shaped through hole are relatively sharp, which easily leads to poor product reliability, especially the problem of electromigration performance failure.

[0004] Therefore, it is an urgent technical problem to be solved to provide a semiconductor device and a method for forming a via thereof, which can form a circular via on the dielectric layer based on a mask plate with a square hole pattern to improve the product reliability. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a semiconductor device and a method for forming a via thereof, which can form a circular via on the dielectric layer based on a mask plate with a square hole pattern to improve the product reliability, which is an urgent technical problem to be solved.

[0006] To solve the above problems, the present invention provides a method for forming a via of a semiconductor device, the method comprising: providing a first mask plate with a square hole pattern and a substrate including a substrate, a dielectric layer and a photoresist layer stacked in sequence; processing the photoresist layer based on the first mask plate to form a first via in the photoresist layer, one end of the first via far from the dielectric layer being circular and one end close to the dielectric layer being square; etching the dielectric layer using the photoresist layer as a second mask plate to form a cylindrical second via in the dielectric layer.

[0007] In some embodiments, the step of processing the photoresist layer based on the first mask to form a first through-hole in the photoresist layer further includes: providing an objective lens and placing the objective lens between the first mask and the photoresist layer; adjusting the distance between the objective lens and the photoresist layer so that the focal point of the objective lens is located on the surface of the photoresist layer close to the dielectric layer, so as to form a first circular pattern on the surface of the photoresist layer away from the dielectric layer during development, thereby forming the first through-hole in the photoresist layer.

[0008] In some embodiments, the distance between the objective lens and the first mask is greater than the distance between the objective lens and the photoresist layer.

[0009] In some embodiments, the first circular pattern is the circumscribed circle of the orthographic projection of the square hole pattern on the first mask on the photoresist layer.

[0010] In some embodiments, the step of processing the photoresist layer based on the first mask to form a first through-hole in the photoresist layer further includes: increasing the thickness of the photoresist layer; performing photolithography on the photoresist layer with increased thickness using the first mask to form a third through-hole in the photoresist layer that matches the square hole pattern of the first mask; preprocessing the third through-hole with argon ions to form a second circular pattern on the surface of the photoresist layer away from the dielectric layer, thereby forming the first through-hole in the photoresist layer.

[0011] In some embodiments, the step of increasing the thickness of the photoresist layer further includes: using a spin-coating method for the photoresist to increase the thickness of the photoresist layer by 0.5 to 1.5 microns.

[0012] In some embodiments, the step of preprocessing the third through-hole with argon ions further includes: bombarding the surface of the photoresist layer away from the dielectric layer with argon ions using an argon ion gun to passivate one end of the third through-hole away from the dielectric layer, thereby forming the second circular pattern on the surface of the photoresist layer away from the dielectric layer.

[0013] In some embodiments, the second circular pattern is the circumscribed circle of the orthographic projection of the square hole pattern on the first mask on the photoresist layer.

[0014] In some embodiments, the diameter of the second through-hole is greater than 0.5 microns.

[0015] To solve the above problems, the present invention also provides a semiconductor device, including a dielectric layer, the dielectric layer having at least one cylindrical through-hole, and the through-hole is formed by using the method of the present invention.

[0016] In the above technical solution, the first photomask with a square hole pattern is used to process the photoresist layer, so as to form a first through hole with a circular shape at the end far from the dielectric layer and a square shape at the end close to the dielectric layer in the photoresist layer, and the dielectric layer is etched using the photoresist layer as a second photomask to form a cylindrical second through hole in the dielectric layer. This avoids the problem of poor product reliability, especially the problem of electromigration performance failure, caused by the sharp corners of the rectangular holes in the large-sized through hole pattern formed during the photolithography process due to the square hole pattern of the photomask, improves the yield of the product, and saves the manufacturing cost.

[0017] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present invention. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the said technologies, methods, and devices should be regarded as part of the authorization specification. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 Schematic diagram of the steps of a method for forming a through hole of a semiconductor device in an embodiment of the present invention;

[0020] Figure 2 Schematic diagram of a substrate in an embodiment of the present invention;

[0021] Figure 3 Schematic diagram of an objective lens in an embodiment of the present invention;

[0022] Figure 4 Schematic diagram of a formed semiconductor device in an embodiment of the present invention;

[0023] Figure 5 Schematic diagram of the steps of forming a first through hole in a photoresist layer in an embodiment of the present invention;

[0024] Figures 6 to 7 Schematic diagram of the device structure formed by the main steps in an embodiment of the present invention. Detailed Embodiments

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0026] In order to solve the problem that in the prior art, due to the square hole pattern of the mask plate, the rectangular hole corners of the large-size through-hole pattern (pattern with a size greater than 0.5 microns) formed during the lithography process are relatively sharp, resulting in poor product reliability, especially the failure of the electromigration performance. Embodiments of the present invention provide a semiconductor device and a method for forming a through hole thereof.

[0027] First, a method for forming a through hole of a semiconductor device provided in an embodiment of the present invention will be introduced below.

[0028] Please refer to Figure 1 , which is a schematic diagram of the steps of a method for forming a through hole of a semiconductor device in an embodiment of the present invention. As Figure 1 shown, the method for forming a through hole of the semiconductor device in this embodiment includes: Step S11, providing a first mask plate with a square hole pattern and a substrate including a substrate, a dielectric layer, and a photoresist layer stacked in sequence; Step S12, processing the photoresist layer based on the first mask plate to form a first through hole in the photoresist layer, one end of the first through hole away from the dielectric layer is circular, and one end close to the dielectric layer is square; Step S13, etching the dielectric layer using the photoresist layer as a second mask plate to form a cylindrical second through hole in the dielectric layer.

[0029] Please refer to Step S11 and Figure 2 , Figure 2 is a schematic diagram of a substrate in an embodiment of the present invention. In this embodiment, the substrate includes a substrate 21, a dielectric layer 31, and a photoresist layer 41. The material of the substrate 21 can be single crystal silicon (Si), single crystal germanium (Ge), or silicon germanium (GeSi), silicon carbide (SiC); it can also be silicon on insulator (SOI), germanium on insulator (GOI); or it can also be other materials, such as group III-V compounds such as gallium arsenide. In some other embodiments, the substrate further includes an oxide layer disposed between the photoresist layer 41 and the dielectric layer 31 and / or an oxide layer disposed between the substrate 21 and the dielectric layer 31.

[0030] Please refer to Step S12 and Figure 3 , Figure 3Schematic diagram of an objective lens in an embodiment of the present invention. In this embodiment, the step of processing the photoresist layer based on the first mask plate in step S12 to form a first through hole in the photoresist layer further includes: providing an objective lens 51 and placing the objective lens 51 between the first mask plate 61 and the photoresist layer 41; adjusting the distance between the objective lens 51 and the photoresist layer 41 so that the focal point of the objective lens 51 is located on the surface of the photoresist layer 41 close to the dielectric layer 31, so as to form a first circular pattern 71 on the surface of the photoresist layer 41 away from the dielectric layer 31 during development, thereby forming the first through hole 72 in the photoresist layer 41. Specifically, when the distance between the objective lens 51 and the first mask plate 61 is c, the focal point of the objective lens 51 is located on the surface of the photoresist layer 41 away from the dielectric layer 31; moving the objective lens 51 towards the first mask plate 61, when the distance between the objective lens 51 and the first mask plate 61 is a, the focal point of the objective lens 51 is located on the surface of the photoresist layer 41 close to the dielectric layer 31. During the development of the photoresist layer 41, a first circular pattern 71 will be formed on the surface of the photoresist layer 41 away from the dielectric layer 31, thereby forming a first through hole 72 with a circular top and a square bottom on the photoresist layer 41.

[0031] An object space is formed between the first mask plate 61 and the objective lens 51, and an image space is formed between the photoresist layer 41 and the objective lens 51. In this embodiment, the distance a between the objective lens 51 and the first mask plate 61 is greater than the distance b between the objective lens 51 and the photoresist layer 41. By adjusting the focal plane of the lithography process, the objective lens 51 is closer to the first mask plate 61, so the focal length becomes longer, and the best focus is closer to the bottom of the photoresist layer 41 (i.e., the focal point is located on the surface of the photoresist layer 41 close to the dielectric layer 31); based on the imaging principle, the top of the photoresist layer 41 (the surface of the photoresist layer 41 away from the dielectric layer 31) will be blurred, so the top of the photoresist layer 41 will be circular during the development process.

[0032] In this embodiment, the first circular pattern 71 is the circumscribed circle of the orthographic projection of the square hole pattern on the first mask plate 61 on the photoresist layer 41.

[0033] Please refer to step S13 and Figure 4 , Figure 4 Schematic diagram of a semiconductor device formed in an embodiment of the present invention. In this embodiment, the dielectric layer 31 is etched using the photoresist layer 41 as a second mask plate to form a cylindrical second through hole 81 in the dielectric layer 31. The diameter of the second through hole is greater than 0.5 microns.

[0034] The formation method of the through hole of the semiconductor device provided by another embodiment of the present invention will be introduced below. Please refer to step S12, Figures 5 to 7 , Figure 5 is a schematic diagram of the step of forming the first through hole in the photoresist layer in an embodiment of the present invention, Figures 6 to 7 is a schematic diagram of the device structure formed by the main steps in an embodiment of the present invention. In this embodiment, the step of processing the photoresist layer based on the first mask plate in step S12 to form the first through hole in the photoresist layer further includes: step S51, increasing the thickness of the photoresist layer 41; step S52, performing photolithography on the photoresist layer 41 with increased thickness using the first mask plate 61 to form a third through hole 91 in the photoresist layer 41 that matches the square hole pattern of the first mask plate; step S53, preprocessing the third through hole 91 with argon ions to form a second circular pattern 93 on the surface of the photoresist layer 41 away from the dielectric layer 31, thereby forming the first through hole 92 in the photoresist layer 41.

[0035] In this embodiment, the step of increasing the thickness of the photoresist layer 41 in step S51 further includes: using the spin coating photoresist method to increase the thickness of the photoresist layer 41 by 0.5 micrometer to 1.5 micrometers.

[0036] In this embodiment, the step of preprocessing the third through hole with argon ions in step S53 further includes: bombarding the surface of the photoresist layer 41 away from the dielectric layer 31 with an argon ion gun to passivate one end of the third through hole 91 away from the dielectric layer 31, thereby forming the second circular pattern 93 on the surface of the photoresist layer 41 away from the dielectric layer 31. In this embodiment, the second circular pattern 93 is the circumscribed circle of the orthographic projection of the square hole pattern on the first mask plate 61 on the photoresist layer 41.

[0037] Please continue to refer to step S13 and Figure 4 , in this embodiment, etching the dielectric layer 31 using the photoresist layer 41 as the second mask plate to form a cylindrical second through hole 81 in the dielectric layer 31. The diameter of the second through hole is greater than 0.5 micrometers.

[0038] In the above technical solution, the photoresist layer 41 is processed by the first mask plate 61 having a square hole pattern, so as to form a first through hole with a circular shape at the end far from the dielectric layer 31 and a square shape at the end close to the dielectric layer 31 in the photoresist layer 41, and the dielectric layer 31 is etched using the photoresist layer 41 as a second mask plate, so as to form a cylindrical second through hole in the dielectric layer 31. This avoids the problem of poor product reliability caused by the sharp corners of the rectangular holes of the large-size through hole pattern formed during the photolithography process due to the square hole pattern of the mask plate, especially the problem of electromigration performance failure, improves the yield of the product, and saves the manufacturing cost.

[0039] Based on the same inventive concept, the present invention also provides a semiconductor device. The semiconductor device includes a dielectric layer having at least one cylindrical through hole formed by the method of the present invention. That is, the photoresist layer 41 is processed by the first mask plate 61 having a square hole pattern, so as to form a first through hole with a circular shape at the end far from the dielectric layer 31 and a square shape at the end close to the dielectric layer 31 in the photoresist layer 41, and the dielectric layer 31 is etched using the photoresist layer 41 as a second mask plate, so as to form a cylindrical second through hole in the dielectric layer 31. For the specific steps, please refer to Figures 1 to 6 and will not be elaborated here.

[0040] It should be noted that in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "further includes one..." does not exclude the existence of another identical element in the process, method, article or device including the element.

[0041] Each embodiment in this specification is described in a related manner. The same or similar parts between the embodiments can be referred to each other, and the differences between each embodiment and other embodiments are emphasized.

[0042] The above is only the preferred embodiment of the present invention and is not used to limit the protection scope of the present invention. It should be pointed out that for those of ordinary skill in the art in the technical field, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for forming a via hole in a semiconductor device, characterized in that, The method includes: providing a first mask plate with a square hole pattern and a substrate including a substrate, a dielectric layer, and a photoresist layer stacked in sequence; processing the photoresist layer based on the first mask plate to form a first through hole in the photoresist layer, one end of the first through hole away from the dielectric layer being circular and the end close to the dielectric layer being square; etching the dielectric layer using the photoresist layer as a second mask plate to form a cylindrical second through hole in the dielectric layer.

2. The method according to claim 1, characterized in that, The step of processing the photoresist layer based on the first mask plate to form a first through hole in the photoresist layer further includes: providing an objective lens and placing the objective lens between the first mask plate and the photoresist layer; adjusting the distance between the objective lens and the photoresist layer so that the focal point of the objective lens is located on the surface of the photoresist layer close to the dielectric layer to form a first circular pattern on the surface of the photoresist layer away from the dielectric layer during development, thereby forming the first through hole in the photoresist layer.

3. The method according to claim 2, characterized in that, The distance between the objective lens and the first mask plate is greater than the distance between the objective lens and the photoresist layer.

4. The method according to claim 2, wherein The first circular pattern is the circumscribed circle of the orthographic projection of the square hole pattern on the first mask plate on the photoresist layer.

5. The method according to claim 1, wherein The step of processing the photoresist layer based on the first mask plate to form a first through hole in the photoresist layer further includes: increasing the thickness of the photoresist layer; lithographing the photoresist layer with increased thickness using the first mask plate to form a third through hole in the photoresist layer adapted to the square hole pattern of the first mask plate; performing pretreatment on the third through hole using argon ions to form a second circular pattern on the surface of the photoresist layer away from the dielectric layer, thereby forming the first through hole in the photoresist layer.

6. The method according to claim 5, characterized in that, The step of increasing the thickness of the photoresist layer further includes: increasing the thickness of the photoresist layer by 0.5 to 1.5 microns by means of spin coating photoresist.

7. The method according to claim 5, wherein The step of performing pretreatment on the third through hole using argon ions further includes: bombarding the surface of the photoresist layer away from the dielectric layer with an argon ion gun to passivate one end of the third through hole away from the dielectric layer, thereby forming the second circular pattern on the surface of the photoresist layer away from the dielectric layer.

8. The method according to claim 7, wherein The second circular pattern is the circumscribed circle of the orthographic projection of the square hole pattern on the first mask plate on the photoresist layer.

9. The method according to claim 1, wherein The diameter of the second through hole is greater than 0.5 microns.

10. A semiconductor device, characterized in that, including a dielectric layer having at least one cylindrical through hole formed by the method according to any one of claims 1 to 9.

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