Metal wire and method of making the same

Abstract

The application provides a metal wire and a manufacturing method thereof. The manufacturing method comprises the following steps: forming a metal strip on a substrate; forming a mask above the metal strip, wherein the width of the mask is smaller than the width of the metal strip, and the orthographic projection of the mask on the substrate is located in the orthographic projection of the metal strip on the substrate; and wet etching the metal strip to a saturation state under the protection of the mask to form a metal wire, wherein the width of the metal wire is smaller than the width of the mask. The manufacturing method can form a metal wire with high thickness and narrow line width.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to a metal wire and a method for manufacturing the same. Background Technology

[0002] With the increasing miniaturization of semiconductor devices, a common challenge in the field is fabricating thick, narrow-linewidth metal lines for signal transmission. The materials for these metal lines are typically aluminum (Al) and copper (Cu), and during etching, their profile is approximately 45 degrees. For metal lines designed to be 1.5 micrometers (μm) or thicker, conventional etching processes cannot guarantee uniform etching.

[0003] Commonly used exposure machines have linewidths of 3 micrometers (μm) or higher. High-thickness, narrow-linewidth metal lines obtained by directly increasing overcutting cannot guarantee linewidth uniformity. Processes involving two metal depositions and two patterning steps result in irregular and uneven metal cross-sections, and severe photoresist detachment problems. Using small trench epitaxial inorganic materials, such as silicon nitride (SiN) or silicon oxide (SiO), followed by evaporation or electroplating of metal materials into the small trenches, leads to severe linewidth and thickness inhomogeneities.

[0004] Therefore, it is necessary to improve the aforementioned defects and problems. Summary of the Invention

[0005] According to a first aspect of the embodiments of this application, a method for manufacturing a metal wire is provided, comprising:

[0006] Metal strips are formed on the substrate;

[0007] A mask is formed above a metal strip, the width of the mask being smaller than the width of the metal strip, and the orthographic projection of the mask onto the substrate lies within the orthographic projection of the metal strip onto the substrate;

[0008] Under the protection of the mask, the metal strip is wet-etched to a saturated state to form a metal line, the width of which is smaller than the width of the mask.

[0009] In one embodiment, forming metal strips on a substrate includes:

[0010] A sacrificial layer is formed on a substrate, and trenches are formed within the sacrificial layer;

[0011] The trench is filled with metallic material;

[0012] Remove the sacrificial layer.

[0013] In one embodiment, the sacrificial layer is made of a light-sensitive organic material, the trenches are formed by photolithography on the sacrificial layer, and the sacrificial layer is removed by ashing.

[0014] In one embodiment, the trench has a first cross-section perpendicular to the substrate along the width direction, and the first cross-section is generally wider at the top and narrower at the bottom.

[0015] In one embodiment, the first cross-section of the trench is an isosceles trapezoid.

[0016] In one embodiment, the trench is filled with a metallic material, including:

[0017] Deposit metallic material on the sacrificial layer and within the trench;

[0018] A photoresist pattern is formed, which covers the metal material inside the trench and exposes the metal material outside the trench;

[0019] The metal material is etched under the protection of the photoresist pattern to remove the metal material outside the trench.

[0020] In one embodiment, the mask has a second cross-section perpendicular to the substrate along the width direction, and the second cross-section is generally narrower at the top and wider at the bottom.

[0021] In one embodiment, the second cross-section of the mask is an isosceles trapezoid.

[0022] In one embodiment, the substrate comprises a COP optical material;

[0023] Before forming a sacrificial layer on the substrate, an ashing barrier layer is first formed on the substrate, and the sacrificial layer is formed on the ashing barrier layer.

[0024] In one embodiment, the material of the ashing barrier layer includes silicon nitride or silicon oxide.

[0025] In one embodiment, a metal seed layer is first formed on the substrate before a sacrificial layer is formed on the substrate, the sacrificial layer is formed on the metal seed layer, and the trench formed in the sacrificial layer exposes the metal seed layer;

[0026] Metal material is filled into the trench by electroplating, and the metal material is not formed outside the trench.

[0027] In one embodiment, during the wet etching of the metal strip to form a metal wire, the exposed portion of the metal seed layer is either removed synchronously or not.

[0028] In one embodiment, forming metal strips on a substrate includes:

[0029] A sacrificial layer is formed on the substrate;

[0030] A first trench and a second trench are formed within the sacrificial layer, the first trench and the second trench being isolated from each other and arranged along the width direction;

[0031] Depositing metallic material, wherein the metallic material formed above the sacrificial layer between the first trench and the second trench serves as the metallic strip.

[0032] In one embodiment, the sacrificial layer is made of a light-sensitive organic material, and the first trench and the second trench are formed by photolithography on the sacrificial layer.

[0033] In one embodiment, the width of the first trench and / or the second trench is greater than or equal to 2 micrometers, and the slope of the sidewalls of the first trench and / or the second trench is greater than or equal to 80 degrees and less than or equal to 90 degrees.

[0034] In one embodiment, before forming the first trench and the second trench, a hard mask is first formed on the sacrificial layer, the hard mask having openings corresponding to the first trench and the second trench;

[0035] The sacrificial layer is dry-etched using the hard mask to form a first trench and a second trench within the sacrificial layer.

[0036] In one embodiment, the hard mask is removed before depositing the metallic material.

[0037] In one embodiment, the hard mask is made of molybdenum, aluminum, indium tin oxide, or indium gallium zinc oxide.

[0038] According to a second aspect of the embodiments of this application, a metal wire manufactured according to the above-described manufacturing method is provided.

[0039] The main technical effects achieved by the embodiments of this application are:

[0040] By first forming a specific mask above the metal strip, and then wet etching the metal strip to a saturated state to form a metal line, it is possible to form a metal line with high thickness and narrow linewidth, while ensuring the uniformity of the formed metal line in all places. Attached Figure Description

[0041] Figure 1 This is a flowchart illustrating a method for manufacturing a metal wire according to this application;

[0042] Figures 2 to 9This is a schematic diagram of the manufacturing method provided in one embodiment of this application;

[0043] Figures 10 to 12 This is a schematic diagram of the manufacturing method provided in another embodiment of this application;

[0044] Figures 13 to 17 This is a schematic diagram of the manufacturing method provided in another embodiment of this application;

[0045] Figures 18 to 20 This is a schematic diagram of the manufacturing method provided in another embodiment of this application;

[0046] Figures 21 to 24 This is a schematic diagram of the manufacturing method provided in another embodiment of this application;

[0047] Figures 25 to 27 This is a schematic diagram of the manufacturing method provided in another embodiment of this application. Detailed Implementation

[0048] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0049] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0050] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0051] The embodiments of this application will now be described in detail with reference to the accompanying drawings. Unless otherwise specified, the features in the following embodiments may complement or combine with each other.

[0052] This application provides a method for manufacturing a metal wire. For example... Figure 1 As shown, the manufacturing method may include the following steps:

[0053] S10: Forming metal strips on the substrate;

[0054] S20: A mask is formed above the metal strip, the width of the mask being smaller than the width of the metal strip, and along the width direction, the mask covers the upper surface of the middle region of the metal strip while exposing the upper surface of the edge region of the metal strip;

[0055] S30: Under the protection of the mask, the metal strip is wet-etched to a saturated state to form a metal line, the width of which is smaller than the width of the mask.

[0056] In the above etching process, as the etching continues, an etching saturation state will occur. Once etching saturation is reached, even if the etching time is significantly increased, the etching result on the metal strip cannot be significantly changed, and a smaller linewidth cannot be obtained.

[0057] In the above etching process, the occurrence of etching saturation is due to the combined effect of the special positional relationship between the mask and the metal strip, as well as the slowing of lateral etching caused by the surface tension and diffusion of the etching solution. Furthermore, the process is relatively stable; that is, after reaching etching saturation, the linewidth of the metal line remains essentially at a production-ready level, and the etching results obtained from different batches are also basically stable. Utilizing this characteristic, the above method can obtain metal strips with high thickness, narrow linewidth, and high linewidth uniformity.

[0058] It's important to note that reaching saturation doesn't mean that further etching will completely stop consuming the metal strip. It simply means that the etching rate achievable with continued etching will be significantly lower than the rate during the previous stable etching phase. Therefore, even a limited period of continued etching will have a negligible impact on the final etching result of the metal strip. For example, when the etching rate is significantly lower than the rate or average rate during the previous stable etching phase—say, less than one-third of the average rate during the stable etching phase—it can be considered that etching saturation has been reached.

[0059] In a specific implementation, step S10 of forming metal strips on the substrate may include the following steps: forming a sacrificial layer on the substrate, wherein a trench is formed in the sacrificial layer; filling the trench with metal material; and removing the sacrificial layer.

[0060] Figures 2 to 9 A specific embodiment of the above-mentioned method for manufacturing metal wire is disclosed.

[0061] like Figure 2A substrate 1 is provided, which is glass. In other embodiments, the substrate may also be other rigid or flexible substrates. A sacrificial layer 2 is formed on the substrate 1, and a trench G is formed within the sacrificial layer 2. The sacrificial layer 2 is made of a photosensitive organic material, and the trench G can be formed within it by photolithography (including exposure, development, etc.). The trench G penetrates the sacrificial layer in the thickness direction. In other embodiments, the sacrificial layer may also be made of other organic or inorganic materials, as long as it is convenient to form the trench G within it and to remove the sacrificial layer in subsequent processes. The first cross-sectional shape of the formed trench G is an isosceles trapezoid that is wider at the top and narrower at the bottom. The first cross-section extends along the width direction of the trench G and is perpendicular to the upper surface of the substrate 1. In other embodiments, the first cross-section of the trench may also have other morphologies, but when it has an overall morphology that is wider at the top and narrower at the bottom, the final metal strip has better performance in terms of morphological stability and narrow linewidth. In the embodiment shown in the figure, the width of the top of the trench G (i.e., the width at its widest point) is approximately 7 micrometers (μm), the width of the bottom of the trench G (i.e., the width at its narrowest point) is approximately 4.5 micrometers (μm), and the thickness (i.e., the depth) of the trench G is approximately 5 micrometers (μm). Of course, this application is not limited to this, as long as the thickness of the trench G is greater than the thickness of the final required metal wire.

[0062] The groove with the first cross-section in the shape of an isosceles trapezoid can be formed by photolithography and precise control of the photolithography parameters. Alternatively, the groove can be formed by die-pressing. For example, a die can be designed with protrusions whose shape is the same as that of the groove; then, the protrusions of the die are pressed into a sacrificial layer and then pulled out, thus forming a groove with the corresponding shape within the sacrificial layer.

[0063] A metallic material is deposited on sacrificial layer 2, with a thickness meeting design and production requirements. Deposition can be achieved using direct current sputtering or evaporation, and the deposited metal can be a high-conductivity metal such as aluminum (Al), copper (Cu), or silver (Ag). In the embodiment shown in the figure, the deposited metal is aluminum, with a thickness of approximately 2 micrometers (μm). Figure 2 As shown, the deposited metallic material layer 3 is formed both on the sacrificial layer 2 and fills the trench G, but does not completely fill the trench G.

[0064] like Figure 3 The trench G is filled with photoresist 4, and any excess photoresist 4 forms on the metal layer 3 outside the trench G. The upper surface of the photoresist 4 is entirely flat. Subsequently, the entire surface of the photoresist 4 is ashed using oxygen plasma (O2 plasma). By controlling the ashing time, the photoresist 4 outside the trench G is completely removed, but the photoresist 4 (photoresist pattern) remains on the metal layer 3 inside the trench G. The resulting structure is as follows. Figure 4 As shown.

[0065] like Figure 5 Wet etching is performed to remove the metal material outside the trench G. Taking a 2-micrometer-thick aluminum metal as an example in the embodiment shown in the figure, all the metal material outside the trench G can be removed in approximately 360 seconds. In other embodiments, other methods can also be used to remove the metal material outside the trench G, such as dry etching, chemical mechanical polishing (CMP), etc.

[0066] The photoresist 4 remaining above the metal material in the trench G can then be removed. The metal material still remaining in the trench G at this point can be referred to as metal strip 34 for ease of description. In the embodiment shown in the figure, due to the presence of the trench G, the cross-sectional shape of the metal strip 34 is generally wider at the top and narrower at the bottom, specifically an isosceles trapezoid.

[0067] like Figure 6 The sacrificial layer 2 can be removed by ashing with oxygen plasma (O2 plasma). After the sacrificial layer 2 is removed, the sidewalls of the metal strip 34 are exposed. The width of the upper surface of the metal strip 34 is slightly smaller than the width of the upper end of the trench G, slightly smaller than 7 micrometers (μm). The resulting structure is as follows... Figure 7 As shown.

[0068] like Figure 8 A mask 5 is formed on the metal strip 34. The width of the mask 5 is smaller than the width of the metal strip 34, and the orthographic projection of the mask 5 onto the substrate 1 lies within the orthographic projection of the metal strip 34 onto the substrate 1, such that along the width direction, the mask 5 covers the upper surface of the middle region of the metal strip 34, while exposing the upper surface of the edge region of the metal strip 34. In a specific implementation, the width of the mask 5 can be designed to be 4 to 6 micrometers larger than the width of the final required metal line, that is, both sidewalls of the mask 5 in the width direction protrude outward by 2 to 3 micrometers more than the sidewalls of the final required metal line.

[0069] The statement "the width of the mask is less than the width of the metal strip" mainly refers to the comparison of the width of the contact surface or adjacent surfaces of the two. Since the width of the mask (or metal strip) varies throughout the implementation process, it is not required that the width of the mask at every point be less than the width of the metal strip at every point. For example, as long as the width of the lower surface of the mask is less than the width of the upper surface of the metal strip, the requirement that "the width of the mask is less than the width of the metal strip" can be considered satisfied.

[0070] The mask 5 is a photoresist pattern formed after photoresist exposure and development (i.e., photolithography). In other embodiments, the mask can also be a hard mask or other film layers, as long as it can provide a certain degree of protection to the upper surface of the metal strip 34 in the subsequent wet etching process.

[0071] In the embodiment shown in the figure, the second cross-section of the mask 5 is an isosceles trapezoid that is narrower at the top and wider at the bottom. The second cross-section extends along the width direction of the mask 5 and is perpendicular to the upper surface of the substrate 1. Of course, the shape of the second cross-section of the mask 5 is not limited to this. For example, it can be rectangular, non-isosceles trapezoidal, etc. However, when the second cross-section of the mask 5 adopts a shape that is narrower at the top and wider at the bottom, it is more advantageous to obtain narrower linewidth metal strips in subsequent wet etching processes. The mask 5 with the isosceles trapezoidal second cross-section can be formed by photolithography and precise control of the photolithography parameters. Alternatively, the mask 5 with the isosceles trapezoidal second cross-section can be formed by pressing and imprinting. For example, a mold can be designed with a recessed surface on its pressing surface, the shape of which is the same as the shape of the mask 5; then, the pressing surface of the mold is pressed into the photoresist and then pulled out, thus pressing the photoresist to form the mask 5.

[0072] Then, under the protection of the mask 5, please refer to... Figure 8 and Figure 9 The metal strip 34 is wet-etched to a saturated state to form a metal line 36, the width of which is smaller than the width of the mask 5. The final width (i.e., linewidth) of the metal line 36 is approximately 1.5 micrometers (μm).

[0073] In the above etching process, as the etching continues, an etching saturation state will occur. Once the etching saturation state is reached, even if the etching time is significantly increased, the etching result of the metal strip 34 cannot be significantly changed, and a smaller linewidth cannot be obtained.

[0074] In the above etching process, the occurrence of etching saturation is due to the special positional relationship between the mask 5 and the metal strip 34, as well as the combined effect of the surface tension and diffusion of the etching solution causing a slowdown in lateral etching. Furthermore, the process is relatively stable; that is, after reaching etching saturation, the linewidth of the metal line remains essentially at the same production-ready level, and the etching results obtained from different batches are also basically stable. Utilizing this characteristic, the above method can obtain metal lines 36 with high thickness and narrow linewidth, and the linewidth uniformity of the metal lines 36 is high.

[0075] It's important to note that reaching saturation doesn't mean that further etching will completely eliminate the metal strip 34. It simply means that the etching rate achievable with continued etching will be significantly lower than the etching rate during the previous stable etching phase. Therefore, even a limited period of continued etching will have a negligible impact on the final etching result of the metal strip 34. For example, when the etching rate is significantly lower than the rate or average rate of the previous stable etching phase, such as less than one-third of the average rate during the stable etching phase, it can be considered that etching saturation has been reached.

[0076] In related technologies for etching metal materials, the etching slope on the side of the metal material is approximately 45 degrees, which is due to the difference in etching rates between the upper and lower surfaces of the metal material. However, in the process described in this application, for the metal strip originally located in the trench, the contact between the upper and lower parts of its side surface and the etching solution is basically consistent. Therefore, the difference in etching rates between the upper and lower parts of the side surface is small, ultimately achieving a narrow linewidth and large thickness metal line structure.

[0077] Figures 10 to 12 Another specific embodiment of the above-described method for manufacturing metal wire is disclosed. This embodiment is similar to... Figures 2 to 9 The embodiments are similar, except that different substrate materials are used and the substrate is treated accordingly before the sacrificial layer is formed.

[0078] like Figure 10 The substrate is made of COP optical material. That is, the substrate is COP substrate 7. COP optical material has the following characteristics: high transparency, low birefringence, low water absorption, high rigidity, high heat resistance, good water vapor tightness, and meets FDA (U.S. Food and Drug Administration) standards.

[0079] Before forming the sacrificial layer 2, an ashing barrier layer 6 can be formed on the COP substrate 7. The ashing barrier layer 6 can be made of silicon nitride (SiN) or silicon oxide (SiO), etc. The thickness of the ashing barrier layer 6 can be 100 nanometers (nm). The ashing barrier layer 6 can be deposited using plasma-enhanced chemical vapor deposition (PECVD). Of course, the material, thickness, and formation process of the ashing barrier layer are not limited to these, as long as they can protect the underlying COP substrate 7 during the subsequent ashing removal of the sacrificial layer 2.

[0080] Then, a sacrificial layer 2 is formed on the ashing barrier layer 6, and trenches are formed within the sacrificial layer 2. Metal material is deposited on the sacrificial layer 2, and the resulting metal material layer 3 is formed both on the sacrificial layer 2 and fills the trenches, but does not completely fill them. Next, photoresist 4 is used to fill the trenches, and excess photoresist 4 also forms on the metal material layer 3 outside the trenches. The upper surface of the photoresist 4 is entirely flat. The entire surface of the photoresist 4 is ashed using oxygen plasma (O2 plasma).

[0081] like Figure 11 By controlling the ashing process time, the photoresist 4 outside the trench is completely removed, but the photoresist 4 (photoresist pattern) remains on the metal material layer 3 inside the trench. Then, wet etching is performed to remove the metal material outside the trench and remove the photoresist 4 remaining on the metal material inside the trench. The metal material still remaining in the trench at this point is the metal strip 34 to be further etched later.

[0082] like Figure 12 The sacrificial layer 2 is removed by ashing, exposing the sidewalls of the metal strip 34. A mask 5 is formed on the metal strip 34. Under the protection of the mask 5, the metal strip 34 is wet-etched to a saturated state to form metal lines 36.

[0083] The above-mentioned formation of sacrificial layer 2 and subsequent processing steps are all related to Figures 2 to 9 The implementation methods are the same and will not be described in detail here; please refer to the preceding text.

[0084] Figures 13 to 17 Another specific embodiment of the above-mentioned method for manufacturing metal wire is disclosed.

[0085] like Figure 13 A substrate 1 is provided, which is glass. In other embodiments, the substrate may also be other rigid or flexible substrates. A metal seed layer 8 is first deposited on the substrate 1. The metal seed layer 8 may be made of copper and may have a thickness of 4000 angstroms. The pre-formed metal seed layer 8 facilitates subsequent electroplating processes.

[0086] A sacrificial layer 2 is formed on a metal seed layer 8, and trenches are formed within the sacrificial layer 2. The sacrificial layer 2 is made of a photosensitive organic material, and trenches can be formed within it by photolithography (including exposure, development, etc.). The trenches penetrate the sacrificial layer in the thickness direction and expose the metal seed layer. In other embodiments, the sacrificial layer can also be made of other organic or inorganic materials, as long as it is convenient to form trenches within it and to remove the sacrificial layer in subsequent processes. The first cross-sectional shape of the formed trench is an isosceles trapezoid that is wider at the top and narrower at the bottom. In other embodiments, the first cross-section of the trench can also have other morphologies, but when it has an overall morphology that is wider at the top and narrower at the bottom, the final metal strip has better performance in terms of morphological stability and narrow linewidth. In the embodiment shown in the figure, the width of the top of the trench (i.e., the width at its widest point) is approximately 7 micrometers (μm), the width of the bottom of the trench (i.e., the width at its narrowest point) is approximately 4.5 micrometers (μm), and the thickness (i.e., the depth) of the trench is approximately 5 micrometers (μm). Of course, this application is not limited to these.

[0087] Metal material is formed within the trench by electroplating. Due to the influence of the metal seed layer 8 and the sacrificial layer 2, the metal material does not form outside the trench. The metal material can be a high-conductivity metal such as aluminum (Al), copper (Cu), or silver (Ag). In the embodiment shown in the figure, the metal material is copper with a thickness of approximately 2 micrometers (μm). The electroplated metal material is a metal strip 34, whose cross-sectional shape is the same as or substantially the same as the first cross-sectional shape of the trench.

[0088] like Figure 14The sacrificial layer 2 can be removed by ashing with oxygen plasma (O2 plasma). After the sacrificial layer 2 is removed, the sidewalls of the metal strip 34 are exposed. The width of the upper surface of the metal strip 34 is slightly smaller than the width of the upper end of the trench G, slightly smaller than 7 micrometers (μm). The resulting structure is as follows... Figure 15 As shown.

[0089] like Figure 16 A mask 5 is formed on the metal strip 34. The width of the mask 5 is smaller than the width of the metal strip 34, and the orthographic projection of the mask 5 onto the substrate 1 lies within the orthographic projection of the metal strip 34 onto the substrate 1, such that along the width direction, the mask 5 covers the upper surface of the middle region of the metal strip 34, while exposing the upper surface of the edge region of the metal strip 34. In a specific implementation, the width of the mask 5 can be designed to be 4 to 6 micrometers larger than the width of the final required metal line, that is, both sidewalls of the mask 5 in the width direction protrude outward by 2 to 3 micrometers more than the sidewalls of the final required metal line.

[0090] The mask 5 is a photoresist pattern formed after photoresist exposure and development (i.e., photolithography). In other embodiments, the mask can also be a hard mask or other film layers, as long as it can provide a certain degree of protection to the upper surface of the metal strip 34 in the subsequent wet etching process.

[0091] In the embodiment shown in the figure, the second cross-section of the mask 5 is an isosceles trapezoid that is narrower at the top and wider at the bottom. The second cross-section extends along the width direction of the mask 5 and is perpendicular to the upper surface of the substrate 1. Of course, the shape of the second cross-section of the mask 5 is not limited to this. For example, it can be rectangular, non-isosceles trapezoidal, etc. However, when the second cross-section of the mask 5 adopts a shape that is narrower at the top and wider at the bottom, it is more advantageous to obtain narrower linewidth metal strips in subsequent wet etching processes.

[0092] Then, under the protection of the mask 5, please refer to... Figure 17 The metal strip 34 is wet-etched to a saturated state to form a metal line 36, the width of which is smaller than the width of the mask 5. The final width (i.e., linewidth) of the metal line 36 is approximately 1.5 micrometers (μm).

[0093] In the above etching process, as the etching continues, an etching saturation state will occur. Once the etching saturation state is reached, even if the etching time is significantly increased, the etching result of the metal strip 34 cannot be significantly changed, and a smaller linewidth cannot be obtained.

[0094] In the above etching process, the occurrence of etching saturation is due to the special positional relationship between the mask 5 and the metal strip 34, as well as the combined effect of the surface tension and diffusion of the etching solution causing a slowdown in lateral etching. Furthermore, the process is relatively stable; that is, after reaching etching saturation, the linewidth of the metal line remains essentially at the same production-ready level, and the etching results obtained from different batches are also basically stable. Utilizing this characteristic, the above method can obtain metal lines 36 with high thickness and narrow linewidth, and the linewidth uniformity of the metal lines 36 is high.

[0095] It's important to note that reaching saturation doesn't mean that further etching will completely eliminate the metal strip 34. It simply means that the etching rate achievable with continued etching will be significantly lower than the etching rate during the previous stable etching phase. Therefore, even a limited period of continued etching will have a negligible impact on the final etching result of the metal strip 34. For example, when the etching rate is significantly lower than the rate or average rate of the previous stable etching phase, such as less than one-third of the average rate during the stable etching phase, it can be considered that etching saturation has been reached.

[0096] During the wet etching process described above, where the metal strip 34 is saturated to form the metal line 36, the exposed portion of the metal seed layer 8 is simultaneously etched away. The resulting structure is as follows: Figure 17 As shown.

[0097] In other embodiments, if the metal seed layer 8 cannot be removed simultaneously by the above-described wet etching process, the area of ​​the metal seed layer 8 that is not in close contact with the metal line 36 can be removed by a separate step. Specific processes are as follows: Figures 18 to 20 As shown. Figure 18 and Figure 19 First, the mask 5 above the metal line 36 can be stripped. The stripping method can be oxygen plasma ashing treatment. Then, as... Figure 20 The metal seed layer 8 outside the region of metal line 36 is removed using a dry etching process. In the above dry etching process, metal line 36 or a separately formed photoresist pattern can be used as a mask. The etching process used can be reactive ion etching (RIE), inductively coupled plasma etching (ICP), or ion beam etching (IBE), etc.

[0098] Figures 21 to 24 Another specific embodiment of the above-mentioned method for manufacturing metal wire is disclosed.

[0099] like Figure 21 A substrate 1 is provided, which is glass. In other embodiments, the substrate may also be other rigid substrates or flexible substrates.

[0100] A sacrificial layer 2 is formed on a substrate 1, and a first trench T1 and a second trench T2 are formed within the sacrificial layer 2, wherein the first trench T1 and the second trench T2 are isolated from each other. The sacrificial layer 2 is made of a photosensitive organic material, and the first trench T1 and the second trench T2 can be formed simultaneously within it by photolithography (including exposure, development, etc.). The first trench T1 and the second trench T2 penetrate the sacrificial layer in the thickness direction. In other embodiments, the sacrificial layer can also be made of other organic or inorganic materials, as long as it is convenient to form the first trench T1 and the second trench T2 within it and to easily remove the sacrificial layer in subsequent processes.

[0101] The cross-sectional shape of the formed first groove T1 and second groove T2 can be rectangular, and the slope of the sidewalls of the first groove T1 and second groove T2 is relatively steep, between 80 degrees (inclusive) and 90 degrees (inclusive). A steeper slope can be achieved by underdevelopment after exposure. Alternatively, the first groove and second groove can be formed by molding, ensuring their slope.

[0102] In practice, when the width of the first trench T1 and the second trench T2 is 2 micrometers (μm) or more (including 2 micrometers) and the thickness (depth) is 1 micrometer or more (including 1 micrometer), it is beneficial to ensure that the metal deposited in the first trench and the second trench does not adhere to the metal outside the first trench and the second trench, which is beneficial to the quality of the final metal wire formed.

[0103] like Figure 22 Metal material is deposited on the sacrificial layer 2, with the thickness meeting design and production requirements. Deposition can be performed using direct current sputtering or evaporation, and the deposited metal can be a high-conductivity metal such as aluminum (Al), copper (Cu), or silver (Ag). In the embodiment shown in the figure, the deposited metal material is aluminum, with a thickness of approximately 2 micrometers (μm). The deposited metal material layer 9 is formed both on the sacrificial layer 2 and fills the first trench T1 and the second trench T2. Preferably, the metal material layer 9 does not completely fill the first trench T1 and the second trench T2. Due to the steep slope, the metal material is not adhered to or is almost not adhered to the sidewalls of the first trench T1 and the second trench T2. The metal material located above the sacrificial layer 2 between the first trench T1 and the second trench T2 serves as a metal strip 34, such as... Figure 22 As shown, the metal strip 34 is not bonded to the metal material layer 9 in other areas.

[0104] like Figure 23A mask 5 is formed on the metal strip 34. The width of the mask 5 is smaller than the width of the metal strip 34, and the orthographic projection of the mask 5 onto the substrate 1 lies within the orthographic projection of the metal strip 34 onto the substrate 1, such that along the width direction, the mask 5 covers the upper surface of the middle region of the metal strip 34, while exposing the upper surface of the edge region of the metal strip 34. In a specific implementation, the width of the mask 5 can be designed to be 4 to 6 micrometers larger than the width of the final required metal line, that is, both sidewalls of the mask 5 in the width direction protrude outward by 2 to 3 micrometers more than the sidewalls of the final required metal line.

[0105] The mask 5 is a photoresist pattern formed after photoresist exposure and development (i.e., photolithography). In other embodiments, the mask can also be a hard mask or other film layers, as long as it can provide a certain degree of protection to the upper surface of the metal strip 34 in the subsequent wet etching process.

[0106] In the embodiment shown in the figure, the second cross-section of the mask 5 is an isosceles trapezoid that is narrower at the top and wider at the bottom. The second cross-section extends along the width direction of the mask 5 and is perpendicular to the upper surface of the substrate 1. Of course, the shape of the second cross-section of the mask 5 is not limited to this. For example, it can be rectangular, non-isosceles trapezoidal, etc. However, when the second cross-section of the mask 5 adopts a shape that is narrower at the top and wider at the bottom, it is more advantageous to obtain narrower linewidth metal strips in subsequent wet etching processes.

[0107] like Figure 24 Under the protection of the mask 5, the metal strip 34 and other areas of the metal material layer 9 are wet-etched to a saturated state to form a metal line 36. The width of the metal line 36 is smaller than the width of the mask 5. The final width (i.e., linewidth) of the metal line 36 is approximately 1.5 micrometers (μm).

[0108] In the above etching process, as the etching continues, an etching saturation state will occur. Once the etching saturation state is reached, even if the etching time is significantly increased, the etching result of the metal strip 34 cannot be significantly changed, and a smaller linewidth cannot be obtained.

[0109] In the above etching process, the occurrence of etching saturation is due to the special positional relationship between the mask 5 and the metal strip 34, as well as the combined effect of the surface tension and diffusion of the etching solution causing a slowdown in lateral etching. Furthermore, the process is relatively stable; that is, after reaching etching saturation, the linewidth of the metal line remains essentially at the same production-ready level, and the etching results obtained from different batches are also basically stable. Utilizing this characteristic, the above method can obtain metal lines 36 with high thickness and narrow linewidth, and the linewidth uniformity of the metal lines 36 is high.

[0110] It's important to note that reaching saturation doesn't mean that further etching will completely eliminate the metal strip 34. It simply means that the etching rate achievable with continued etching will be significantly lower than the etching rate during the previous stable etching phase. Therefore, even a limited period of continued etching will have a negligible impact on the final etching result of the metal strip 34. For example, when the etching rate is significantly lower than the rate or average rate of the previous stable etching phase, such as less than one-third of the average rate during the stable etching phase, it can be considered that etching saturation has been reached.

[0111] In related technologies for etching metal materials, the etching slope on the side of the metal material is approximately 45 degrees, which is due to the difference in etching rates between the upper and lower surfaces of the metal material. However, in the process described in this application, for the metal strip between the first and second trenches, the contact between the metal strip and the etching solution is basically consistent at all points on its side. Therefore, the difference in etching rates at all points on the side is small, ultimately achieving a narrow linewidth and large thickness metal line structure.

[0112] Figures 25 to 27 Another specific embodiment of the above-mentioned method for manufacturing metal wire is disclosed. This embodiment is similar to... Figures 21 to 24 The embodiments are basically the same, the only difference being the method of forming the first and second trenches; the other steps are exactly the same.

[0113] like Figure 25 After forming a full-layer sacrificial layer 2 on the substrate 1, a hard mask 10 is first formed on the sacrificial layer 2. The hard mask 10 has openings corresponding to the first trench and the second trench. The hard mask 10 can be made of molybdenum (Mo), aluminum (Al), indium tin oxide (ITO), or indium gallium zinc oxide (IGZO), etc. The hard mask 10 and the sacrificial layer 2 have a large etching selectivity. In the embodiment shown in the figure, the hard mask 10 is an indium tin oxide film with a thickness of 1350 angstroms.

[0114] like Figure 26 The sacrificial layer 2 is dry-etched using the hard mask 10 to form a first trench T1 and a second trench T2 within the sacrificial layer 2. Because the etching options are relatively wide, the first trench T1 and the second trench T2 can be guaranteed to have excellent precision in the aforementioned dry etching process, and the slope of the sidewalls of the first trench T1 and the second trench T2 can be well achieved.

[0115] like Figure 27 Before depositing the metal material, the hard mask 10 can be removed. Subsequent process steps (e.g., depositing the metal material, forming a mask on the metal strip, and wet etching the metal strip to saturation under the protection of the mask) are similar to... Figures 21 to 24 The implementation methods are the same.

[0116] Although the above embodiments only illustrate a single metal strip and describe how to process it to create a high-thickness, narrow-linewidth metal wire, those skilled in the art will readily understand that the above manufacturing methods are also applicable to processing multiple independent or non-independent metal strips simultaneously or asynchronously, thereby obtaining multiple independent or non-independent high-thickness, narrow-linewidth metal strips. That is, the above-described simple modifications to the embodiments of this application are still within the scope of protection of this application.

[0117] This application also provides a metal wire, which can be manufactured by any of the above-described methods. The metal wire can be applied to on-screen antennas, photonic chips, gratings, polarization devices, etc., in display devices and mobile terminals.

[0118] It should be noted that the dimensions of layers and regions may be exaggerated in the accompanying drawings for clarity. Furthermore, it is understood that when an element or layer is referred to as being "on" another element or layer, it can be directly on the other element, or there may be intermediate layers. Additionally, it is understood that when an element or layer is referred to as being "below" another element or layer, it can be directly below the other element, or there may be more than one intermediate layer or element. Furthermore, it is also understood that when a layer or element is referred to as being "between" two layers or two elements, it can be the only layer between the two layers or two elements, or there may be more than one intermediate layer or element. Similar reference numerals throughout indicate similar elements.

[0119] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0120] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A method for manufacturing a metal wire, characterized in that, The manufacturing method includes: A sacrificial layer is formed on a substrate, and a trench is formed within the sacrificial layer; the trench has a first cross-section perpendicular to the substrate along its width direction, and the first cross-section is generally wider at the top and narrower at the bottom; a metal material is filled into the trench; the sacrificial layer is removed, and a metal strip is formed on the substrate; A mask is formed above the metal strip, the width of the mask being smaller than the width of the metal strip, and the orthographic projection of the mask on the substrate is located within the orthographic projection of the metal strip on the substrate; Under the protection of the mask, the metal strip is wet-etched to a saturated state to form a metal line, the width of which is smaller than the width of the mask.

2. The manufacturing method according to claim 1, characterized in that, The sacrificial layer is made of a light-sensitive organic material. The trenches are formed by photolithography on the sacrificial layer, and the sacrificial layer is removed by ashing.

3. The manufacturing method according to claim 1, characterized in that, The first cross-section of the trench is an isosceles trapezoid.

4. The manufacturing method according to claim 1, characterized in that, The trench is filled with a metallic material, including: Deposit metallic material on the sacrificial layer and within the trench; A photoresist pattern is formed, which covers the metal material inside the trench and exposes the metal material outside the trench; The metal material is etched under the protection of the photoresist pattern to remove the metal material outside the trench.

5. The manufacturing method according to claim 1, characterized in that, The mask has a second cross section perpendicular to the substrate along the width direction, and the second cross section is generally narrower at the top and wider at the bottom.

6. The manufacturing method according to claim 5, characterized in that, The second cross-section of the mask is an isosceles trapezoid.

7. The manufacturing method according to claim 1, characterized in that, The substrate includes COP optical material; Before forming a sacrificial layer on the substrate, an ashing barrier layer is first formed on the substrate, and the sacrificial layer is formed on the ashing barrier layer.

8. The manufacturing method according to claim 7, characterized in that, The material of the ashing barrier layer includes silicon nitride or silicon oxide.

9. The manufacturing method according to claim 1, characterized in that, Before forming a sacrificial layer on the substrate, a metal seed layer is first formed on the substrate, the sacrificial layer is formed on the metal seed layer, and the trenches formed in the sacrificial layer expose the metal seed layer. Metal material is filled into the trench by electroplating, and the metal material is not formed outside the trench.

10. The manufacturing method according to claim 9, characterized in that, During the wet etching process of the metal strip to form a metal line, the exposed portion of the metal seed layer may or may not be removed simultaneously.

11. The manufacturing method according to claim 1, characterized in that, Forming metal strips on a substrate includes: A sacrificial layer is formed on the substrate; A first trench and a second trench are formed within the sacrificial layer, the first trench and the second trench being isolated from each other and arranged along the width direction; Depositing metallic material, wherein the metallic material formed above the sacrificial layer between the first trench and the second trench serves as the metallic strip.

12. The manufacturing method according to claim 11, characterized in that, The sacrificial layer is made of a light-sensitive organic material, and the first trench and the second trench are formed by photolithography on the sacrificial layer.

13. The manufacturing method according to claim 11, characterized in that, The width of the first trench and / or the second trench is greater than or equal to 2 micrometers, and the slope of the sidewalls of the first trench and / or the second trench is greater than or equal to 80 degrees and less than or equal to 90 degrees.

14. The manufacturing method according to claim 11, characterized in that, Before forming the first trench and the second trench, a hard mask is first formed on the sacrificial layer, and the hard mask has openings at the corresponding first trench and the second trench; The sacrificial layer is dry-etched using the hard mask to form a first trench and a second trench within the sacrificial layer.

15. The manufacturing method according to claim 14, characterized in that, The hard mask is removed before depositing the metallic material.

16. The manufacturing method according to claim 14, characterized in that, The hard mask is made of materials including molybdenum, aluminum, indium tin oxide, or indium gallium zinc oxide.

17. A metal wire manufactured by the method according to any one of claims 1-16.

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