Manufacturing method of metal conductive structure and manufacturing method of semiconductor device

Abstract

The invention provides a manufacturing method of a metal conductive structure and a manufacturing method of a semiconductor device, and the method comprises the steps: forming a carbon-containing organic polymer inner side wall on the side wall of an opening of a dielectric layer before the over-etching of the dielectric layer on a metal layer; the metal fluoride residue generated in the over-etching stage cannot be directly contacted with the side wall of the dielectric layer in the opening, so that the patterned photoresist layer on the dielectric layer and the carbon-containing organic polymer inner side wall at least positioned at the upper part of the side wall of the opening are removed; the gap can be formed between the metal fluoride residue and the side wall of the dielectric layer in the opening, and finally the purpose of weakening the binding force of the metal fluoride residue and the dielectric layer is achieved, so that the metal fluoride residue is easy to remove in the cleaning process after etching, and the adverse effect of the metal fluoride residue on the reliability of the device can be avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuit manufacturing, and in particular to a method for manufacturing a metal conductive structure and a method for manufacturing a semiconductor device. Background Art

[0002] Please refer to Figure 1 In the back-end process of semiconductor manufacturing, a passivation layer is usually deposited on top of the top metal layer (i.e., the last layer of metal, usually aluminum) 101, and is generally composed of an overlapping silicon oxide film 102a and a silicon nitride film 102b. It is opened through a corresponding photolithography process (for forming a patterned photoresist layer 103) and an etching process to expose the top metal layer 101 in the corresponding area to form a pad (also known as PAD, solder pad, aluminum pad, etc.) for connection to an external circuit after packaging.

[0003] Among them, when etching the passivation layer open (i.e., performing the main etching on the passivation layer, usually stopping the main etching when the silicon oxide film 102a is about to expose the top surface of the top metal 101), a plasma gas containing fluorine element is usually used for etching. This process usually forms a small amount of organic polymer 104 on the side wall of the opening. In order to ensure that the passivation layer can be completely opened to ensure the circuit connectivity after packaging, it is necessary to further perform over-etching, that is, after etching the silicon oxide film 102a of the passivation layer, continue to etch a small amount of the top metal 101 downward. The fluorine element contained in the plasma gas reacts with the gold produced during the over-etching. Metal elements are easily combined together to form metal fluoride residues (such as aluminum fluoride polymer AlFx, etc.) 105 with high boiling point and difficult to volatilize, and due to the sputtering of plasma gas etching and the vacuum pump (pump), the metal fluoride residues 105 will be deposited along the opening side walls of the passivation layer, attached to the opening side walls of the passivation layer, the surface of the pad and even the top surface of the passivation layer. After over-etching, post-etching cleaning will be performed. If these metal fluoride residues 105 cannot be well removed during the post-etching cleaning process, it will affect the reliability of the package, and the resulting high contact resistance may also cause device failure. For example, since the etching selectivity of the organic polymer 104 is usually relatively high during the post-etching cleaning process, after the organic polymer 104 is removed first, the gap between the metal fluoride residue 105 and the side wall of the passivation layer is very small. The metal fluoride residue 105 is easily broken and collapsed and adheres to the side wall of the passivation layer and the top surface of the top metal 101 exposed by the opening, resulting in poor removal effect of the metal fluoride residue 105 during the post-etching cleaning process.

[0004] There are two main methods currently used in the industry to remove the above-mentioned metal fluoride residues:

[0005] 1. After etching, use a cleaning solution containing amines and fluorides for post-etching cleaning. However, this method is expensive and not environmentally friendly, and has certain requirements for equipment, so it is not widely used.

[0006] 2. After etching, Ar and H2 plasma are used for post-etching treatment. However, a short treatment time cannot completely remove the residual by-products, while a long treatment time will cause damage to the passivation layer profile. It is difficult to find a balance between the two.

[0007] The above problem also exists in other processes in which a dielectric layer on a metal layer is overetched and opened.

[0008] Therefore, a new solution is needed that can not only effectively remove the metal fluoride residues generated after the dielectric layer on the metal layer is over-etched, but also has low cost and a wide range of applications. Summary of the Invention

[0009] The object of the present invention is to provide a method for manufacturing a metal conductive structure and a method for manufacturing a semiconductor device, which can not only effectively remove metal fluoride residues generated after over-etching of a dielectric layer, but also has low cost and a wide range of applications.

[0010] To achieve the above object, the present invention provides a method for manufacturing a metal conductive structure, which comprises:

[0011] Covering a dielectric layer on a substrate having a metal layer formed on a surface thereof and forming a patterned photoresist layer on the dielectric layer to define an area of ​​the dielectric layer to be opened;

[0012] Using the patterned photoresist layer as a mask, performing main etching on the dielectric layer to form an opening in the dielectric layer, and forming carbon-containing organic polymer inner sidewalls on the sidewalls of the opening;

[0013] Using the patterned photoresist layer and the inner sidewall of the carbon-containing organic polymer as a mask, over-etching along the opening using a fluorine-containing gas to open the dielectric layer and etch away a portion of the thickness of the metal layer, wherein metal fluoride residues generated by the over-etching are attached to the inner sidewall of the carbon-containing organic polymer;

[0014] removing the patterned photoresist layer and at least the carbon-containing organic polymer inner sidewall located on the upper portion of the sidewall of the opening, so as to form a gap between the metal fluoride residue in the opening and at least a portion of the sidewall of the dielectric layer;

[0015] A wet process is used to perform post-etching cleaning to remove the metal fluoride residue, and the metal layer exposed by the opening is formed into a metal conductive structure.

[0016] Optionally, the dielectric layer is subjected to main etching using a carbon-containing gas to synchronously form carbon-containing organic polymer inner sidewalls on the sidewalls of the opening during the main etching process; and / or, after the dielectric layer is subjected to main etching, a carbon-containing organic polymer is first deposited on the surfaces of the dielectric layer and the opening, and then the carbon-containing organic polymer is etched to form carbon-containing organic polymer inner sidewalls on the sidewalls of the opening.

[0017] Optionally, during the etching of the carbon-containing organic polymer, an etching selectivity ratio between the carbon-containing organic polymer and the patterned photoresist layer is between 0.01 and 0.3.

[0018] Optionally, the patterned photoresist layer is ashed and removed by using an oxygen-containing gas, and at least the carbon-containing organic polymer inner sidewall located at the upper portion of the opening sidewall is also removed.

[0019] Optionally, the patterned photoresist layer is ashed and removed by 120% to 200% using oxygen-containing gas to control the height of the carbon-containing organic polymer inner sidewall remaining on the lower portion of the opening sidewall to be 30% to 70% of the thickness of the dielectric layer.

[0020] Optionally, the metal layer is a topmost metal layer, the dielectric layer is a passivation layer, and the metal conductive structure is a pad; and / or the dielectric layer includes a silicon oxide film and a silicon nitride film stacked in sequence.

[0021] Optionally, if there is residual carbon-containing organic polymer at the bottom of the gap, when a wet process is used for post-etching cleaning, a solvent suitable for cleaning the inner sidewalls of the carbon-containing organic polymer is used for post-etching cleaning, and the flow rate and / or impact force of the solvent is increased during the cleaning process to clean the inner sidewalls of the carbon-containing organic polymer remaining in the gap while removing the remaining metal fluoride residues; and / or, after completing the post-etching cleaning, the dielectric layer expands relatively outward, so that a step is formed on the top of the metal layer exposed in the opening.

[0022] Optionally, the height of the step of the metal layer is And / or, the line width of the step of the metal layer is

[0023] Optionally, the manufacturing method includes at least one of the following parameters:

[0024] (1) The material of the metal layer includes at least one of Cu, Al, W, Au, Pt, Ti and Ag;

[0025] (2) The thickness of the dielectric layer is 1 μm to 1.5 μm;

[0026] (3) The thickness of the patterned photolithography layer on the dielectric layer is 3.5 μm to 5 μm;

[0027] (4) At least one opening is formed in the dielectric layer, and the area of ​​a single opening is greater than 3000 μm 2 ;

[0028] (5) at least one opening is formed in the dielectric layer, and an opening ratio of the dielectric layer is between 5% and 30%;

[0029] (6) The etching gas used in the main etching contains not only carbon but also fluorine and / or hydrogen;

[0030] (7) The thickness of the inner side wall of the carbon-containing organic polymer is 10 nm to 300 nm;

[0031] (8) The mass percentage of carbon element in the inner wall of the carbon-containing organic polymer is 30% to 60%;

[0032] (9) The over-etching depth of the metal layer is less than 30 nm;

[0033] (10) The thickness of the metal fluoride residue produced by the over-etching on the inner sidewall of the carbon-containing organic polymer is less than 50 nm;

[0034] (11) The line width of the gap is greater than 80 nm.

[0035] (11) The line width of the gap is greater than 80 nm.

[0036] Based on the same inventive concept, the present invention further provides a method for manufacturing a semiconductor device, which adopts the method for manufacturing a metal conductive structure as described in the present invention to form a desired metal conductive structure.

[0037] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0038] 1. Before over-etching the dielectric layer on the metal layer, a carbon-containing organic polymer inner sidewall is first formed on the sidewall of the opening in the dielectric layer, so that the metal fluoride residue generated during the over-etching stage cannot directly contact the sidewall of the dielectric layer in the opening. Therefore, after removing the patterned photoresist layer on the dielectric layer and the carbon-containing organic polymer inner sidewall located at least on the upper portion of the sidewall of the opening, a gap can be formed between the metal fluoride residue and at least a portion of the sidewall of the dielectric layer in the opening, thereby ultimately achieving the purpose of weakening the bonding force between the metal fluoride residue and the dielectric layer, making it easier to remove it during the post-etching cleaning process, thereby avoiding the adverse effects of the metal fluoride residue on device reliability.

[0039] 2. Use low-cost solvents suitable for cleaning carbon-containing organic polymers for post-etching cleaning, which has low cost, low equipment requirements and a wide range of applications.

[0040] 3. A carbon-containing gas is used to perform main etching on the dielectric layer on the metal layer, thereby forming an opening and covering the sidewall of the opening with a corresponding thickness of a carbon-containing organic polymer. After over-etching, the patterned photoresist layer and the carbon-containing organic polymer at least located on the upper part of the sidewall of the opening are removed by an ashing process. The process is simple and low-cost.

[0041] 4. After over-etching, when the patterned photoresist layer and most of the carbon-containing organic polymer are removed, part of the carbon-containing organic polymer can be retained at the bottom of the gap, which can ensure that the metal fluoride residue is not easy to break and collapse and adhere to the top surface of the metal layer and the side wall of the dielectric layer, thereby further reducing the difficulty of post-etching cleaning and improving the effect of post-etching cleaning. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Those skilled in the art will appreciate that the accompanying drawings are provided for a better understanding of the present invention and do not constitute any limitation on the scope of the present invention.

[0043] Figure 1 It is a schematic diagram of a device cross-sectional structure in an existing method for manufacturing a metal conductive structure (such as a pad).

[0044] Figure 2 FIG. 4 is a flow chart of a method for manufacturing a metal conductive structure according to a first embodiment of the present invention.

[0045] Figure 3 It is a schematic diagram of the cross-sectional structure of a device in the method for manufacturing a metal conductive structure according to the first embodiment of the present invention.

[0046] Figure 4 FIG. 4 is a flow chart of a method for manufacturing a metal conductive structure according to a second embodiment of the present invention.

[0047] Figure 5 It is a schematic diagram of the cross-sectional structure of a device in the method for manufacturing a metal conductive structure according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0048] In the following description, a large number of specific details are given to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, some technical features known in the art are not described to avoid confusion with the present invention. It should be understood that the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. 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 throughout represent the same elements. It should be understood that when an element is referred to as being "connected to" or "coupled to" another element, it can be directly connected to the other element, or there can be intervening elements. Conversely, when an element is referred to as being "directly connected to" another element, there are no intervening elements. When used herein, the singular forms "a," "an," and "said / the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "comprising" is used to identify the presence of certain features, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups. As used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0049] The technical solutions proposed by the present invention are further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the accompanying drawings are in a very simplified form and are not to exact scale, and are only used to facilitate and clearly illustrate the embodiments of the present invention.

[0050] The core point of the technical solution of the present invention is that, before over-etching the dielectric layer, a carbon-containing organic polymer inner sidewall is first formed on the sidewall of the opening formed after the main etching of the dielectric layer, so that the metal fluoride residue generated in the over-etching stage cannot directly contact the sidewall of the dielectric layer in the opening. Therefore, after removing the patterned photoresist layer on the dielectric layer and the carbon-containing organic polymer at least located on the upper part of the sidewall of the opening, a gap can be formed between the metal fluoride residue and at least a portion of the sidewall of the dielectric layer in the opening, thereby ultimately achieving the purpose of weakening the bonding force between the metal fluoride residue and the dielectric layer, making it easy to remove it cleanly during the post-etching cleaning process, thereby avoiding the adverse effects of the metal fluoride residue on the device reliability.

[0051] The formation of carbon-containing organic polymer inner sidewalls of a corresponding thickness on the sidewalls of the opening formed after the main etching of the dielectric layer can be achieved by any suitable method. For example, the plasma gas used in the main etching of the dielectric layer can be changed to use a carbon-containing gas (or an etching gas with a high carbon content) to perform the main etching, thereby increasing the amount of carbon-containing organic polymer generated during the main etching process, thereby forming the carbon-containing organic polymer inner sidewalls on the sidewalls of the dielectric layer in the opening. For another example, after the main etching of the dielectric layer, a carbon-containing organic polymer layer can be deposited and then etched (a sidewall etching process) to form the carbon-containing organic polymer inner sidewalls on the sidewalls of the dielectric layer in the opening.

[0052] The following is a combination of specific embodiments and the attached Figures 2 to 5 The technical solutions and effects of the present invention will be described in detail.

[0053] First embodiment

[0054] Please refer to Figure 2 This embodiment provides a method for manufacturing a metal conductive structure, which includes the following steps:

[0055] S11, covering a substrate having a metal layer formed on its surface with a dielectric layer and forming a patterned photoresist layer on the dielectric layer to define a region of the dielectric layer to be opened;

[0056] S12, using the patterned photoresist layer as a mask, performing main etching on the dielectric layer using a carbon-containing gas to form an opening in the dielectric layer and also forming carbon-containing organic polymer inner sidewalls on sidewalls of the opening;

[0057] S13, using the patterned photoresist layer and the inner sidewall of the carbon-containing organic polymer as a mask, over-etching along the opening using a fluorine-containing gas to open the dielectric layer and etch away a portion of the metal layer, wherein metal fluoride residues generated by the over-etching are attached to the inner sidewall of the carbon-containing organic polymer;

[0058] S14, removing the patterned photoresist layer and the carbon-containing organic polymer inner sidewall located at least on the upper portion of the sidewall of the opening, so that a gap is formed between the metal fluoride residue in the opening and at least a portion of the sidewall of the dielectric layer;

[0059] S15, performing post-etching cleaning using a wet process to remove the metal fluoride residue, and forming the metal layer exposed by the opening into a metal conductive structure.

[0060] Please refer to Figure 3In (A), in step S11, a substrate 100 with a metal layer 101 formed on the surface is provided. The substrate 100 can be a substrate that has completed the front-end process and part of the back-end process. The front-end process forms various active components (such as transistors, diodes, etc.), passive components (such as resistors, inductors, capacitors, etc.), component isolation structures (such as shallow trench isolation structures STI, local field oxygen isolation structures LOCOS, etc.) and ion doped regions (such as n-wells, p-wells, etc.) in the substrate 100. The intrinsic material of the substrate can be any suitable semiconductor material such as silicon, silicon on insulator (SOI), silicon germanium, silicon carbide or gallium arsenide. The back-end process is mainly used to form one or more structures such as metal interconnect structures (not shown), pads, and rewiring. Among them, the metal interconnect structure can be a copper interconnect structure, which can electrically connect the components in the substrate and electrically lead them out through the formed pads.

[0061] The metal layer 101 is usually patterned and can be formed on a portion of the surface of the substrate 100 by being embedded in the surface of the substrate 100. In this way, the bottom surface of the metal layer 101 is lower than the top surface of the substrate 100, and the top surface of the metal layer 101 is flush with or higher than the top surface of the substrate 100; it can also be formed on a portion of the surface of the substrate 100 by covering the surface of the substrate 100. In this way, the bottom surface of the metal layer 101 is in contact with the top surface of the substrate 100.

[0062] In step S11, a dielectric layer can be formed on the substrate 100 and the metal layer 101 by any suitable process such as chemical vapor deposition. The dielectric layer can be a single dielectric film or a composite structure formed by stacking multiple dielectric films of different materials. For example, the dielectric layer includes a silicon oxide film 102a and a silicon nitride film 102b sequentially stacked on the metal layer 101 and the substrate 100. Optionally, the dielectric layer has a thickness of 1 μm to 1.5 μm.

[0063] In this embodiment, metal layer 101 is the topmost metal layer in the back-end process, which is used to manufacture pads and electrically connect to the metal interconnect structure (not shown) in substrate 100. In this case, the dielectric layer serves as a passivation layer covering metal layer 101, and the portion of metal layer 101 exposed by the dielectric layer is subsequently formed into a pad. Optionally, the material of metal layer 101 includes at least one of Cu, Al, W, Au, Pt, Ti, and Ag, and can be a single metal (e.g., Al) or an alloy formed of multiple metals (e.g., an AlCu binary alloy).

[0064] In another embodiment of the present invention, the metal layer 101 may also be a metal layer in a metal interconnect structure. In this case, the dielectric layer is an intermetallic interlayer dielectric layer used to space the metal layer 101 and a metal layer to be formed above it. It may be formed of a low-k dielectric material, such as fluorosilicate glass (FSG), borosilicate glass, or phosphosilicate glass. In another embodiment of the present invention, the metal layer 101 may also be the topmost metal layer in a metal interconnect structure. In this case, the dielectric layer is an intermetallic interlayer dielectric layer used to space the metal layer 101 and a rewiring to be formed above it. It may be formed of a low-k dielectric material, such as fluorosilicate glass (FSG), borosilicate glass, or phosphosilicate glass.

[0065] Please continue to refer to Figure 3 In step (A), in step S11, a patterned photoresist layer 103 is formed on the dielectric layer through a series of photolithography steps such as spin coating of photoresist, exposure, and development. The patterned photoresist layer 103 is used to define the area of ​​the dielectric layer to be opened. Optionally, the thickness of the patterned photoresist layer 103 is in the range of 3.5 μm to 5 μm.

[0066] Please continue to refer to Figure 3 In (A), in step S12, the patterned photoresist layer 103 is used as a mask and a carbon-containing gas (which can be plasma) is used to perform main etching on the dielectric layer. The main etching can be stopped at the interface between the dielectric layer and the metal layer 101 or close to the interface between the dielectric layer and the metal layer 101. At this time, the silicon oxide film 102a in the dielectric layer has not been etched through or has just been etched through. During the main etching process of the dielectric layer, carbon-containing organic polymers (polymers, i.e., etching byproducts) are formed while etching, and the carbon-containing gas used in the main etching can increase the production of carbon-containing organic polymers. As a result, while forming the opening 106 in the dielectric layer, thicker carbon-containing organic polymer inner sidewalls 104' are formed on the sidewalls of the opening 106 (i.e., the sidewalls of the dielectric layer 106). The carbon-containing organic polymer inner sidewalls 104' can not only ensure the sidewall morphology of the formed opening 106, but also prevent metal fluoride residues generated by subsequent over-etching from directly contacting the dielectric layer sidewalls in the opening 106.

[0067] Optionally, the carbon-containing gas used in the main etching in step S12 contains not only carbon but also fluorine and / or hydrogen. For example, the carbon-containing gas includes CH4, CF4, CHF3, CH3F, CH2F2, CF3I, C2F6, C3F8, C5F8, C4F6, C4F8, C6F6, C 12 F 15 、C 15 F 18 At least one of .

[0068] In addition, the gas introduced during the main etching process may also include some auxiliary gases, such as one or a combination of N2, He, Ar, etc.

[0069] Optionally, the carbon content of the carbon-containing organic polymer inner sidewall 104' formed in step S12 is 30% to 60% (mass percentage), so that most of it can be removed by ashing together with the patterned photoresist layer 103 in the subsequent step S14, and the remaining part after step S14 can be easily removed by the solvent selected in the wet process in the subsequent step S15.

[0070] It should be understood that the thickness of the carbon-containing organic polymer inner sidewall 104' formed in step S12 will determine the line width of the gap formed between the metal fluoride residue and the sidewall of the dielectric layer after the subsequent step S14. Therefore, in step S12, the composition and flow rate of the carbon-containing gas can be controlled in combination with the thickness of the dielectric layer to control the thickness of the carbon-containing organic polymer inner sidewall 104' formed on the sidewall of the opening 106. Optionally, the thickness of the carbon-containing organic polymer inner sidewall 104' is 10nm to 300nm. As an example, the thickness of the carbon-containing organic polymer inner sidewall 104' is 150nm to 300nm. As another example, C4F8, C3F8, C5F8, C4F6, C4F8, C6F6, C 12 F 15 、C 15 F 18 A carbon-containing gas with a high carbon content is used and its flow rate is controlled to be 20 sccm to 40 sccm to perform main etching on the dielectric layer to form the required opening 106 and the carbon-containing organic polymer inner sidewall 104' with a required thickness on the sidewall of the opening.

[0071] In addition, a portion of the carbon-containing organic polymer formed in step S12 will also cover the sidewalls and top surface of the patterned photoresist layer 103. The contact area between this portion of the carbon-containing organic polymer (not shown) and the patterned photoresist layer 103 is relatively large. Therefore, when the patterned photoresist layer 103 is removed in the subsequent step S14, this portion of the carbon-containing organic polymer and the metal fluoride residue formed on this portion of the carbon-containing organic polymer will basically be easily taken away and removed cleanly along with the removal of the patterned photoresist layer 103. Therefore, this article focuses on the carbon-containing organic polymer and metal fluoride residue formed on the sidewalls of the dielectric layer in the opening, and the carbon-containing organic polymer and metal fluoride residue on the top surface of the patterned photoresist layer 103 are not removed. Figure 3 Shown in.

[0072] It should also be noted that Figure 3Only one opening 106 is shown in the figure, but this does not mean that the solution of this embodiment is only applicable to the case where one opening is made in the dielectric layer. It can also be applied to the case where two or more openings are made in the dielectric layer. The number and position of the openings are designed according to the needs of the device structure, and the present invention does not make specific restrictions on this. For example, at least one opening 106 is formed in the dielectric layer, and the area of ​​a single opening 106 is greater than 3000 μm 2 For another example, the aperture ratio of the dielectric layer is between 5% and 30%. When all openings are square openings of equal size, the ratio of the total square area of ​​all openings to the top surface area of ​​the dielectric layer before etching is the aperture ratio of the dielectric layer.

[0073] Please refer to Figure 3 In step (B), in step S13, the dielectric layer is overetched using a fluorine-containing gas using the patterned photoresist layer 103 and the carbon-containing organic polymer inner sidewalls 104' as masks. This not only completely opens the dielectric layer (i.e., the silicon oxide film 102a) at the opening 106, but also slightly etches the metal layer 101 at the bottom of the opening 106, allowing the opening 106 to penetrate to a portion of the top of the metal layer 101. During this overetching process, the fluorine element contained in the fluorine-containing gas and the metal element (e.g., aluminum Al) generated during the overetching process easily combine to form a high-boiling-point and non-volatile metal fluoride residue (e.g., aluminum fluoride polymer AlFx, etc.) 105, which adheres to the carbon-containing organic polymer inner sidewalls 104' rather than directly to the sidewalls of the dielectric layer. Among them, the etching depth of the top of the metal layer 101 can be reasonably controlled according to the original thickness of the metal layer 101 and the degree of generation of the metal fluoride residue 105. For example, the etching depth of the top of the metal layer 101 is less than 30nm, so that the thickness of the metal fluoride residue 105 generated by over-etching is less than 50nm, so that the metal fluoride residue 105 is easier to be removed subsequently, and the performance of the metal layer 101 is better.

[0074] In one example, the fluorine-containing gas used in the over-etching in step S13 may be the same as the carbon-containing gas used in the main etching in step S12 , that is, the same carbon-fluorine-containing gas is used in both steps.

[0075] In another example, the fluorine-containing gas used in the over-etching of step S13 is different from the carbon-containing gas used in the main etching of step S12. It may not contain carbon elements to avoid the re-production of carbon-containing organic polymers, or it may contain carbon elements, but the carbon content at the same gas flow rate is lower than the carbon content of the carbon-containing gas used in the main etching of step S12, thereby reducing the amount of carbon-containing organic polymers re-produced during the over-etching process of step S13 as much as possible.

[0076] Optionally, the fluorine-containing gas used for the over-etching in step S13 includes at least one of SiF4, NF3, SF6, CF4, CH4, CHF3, CF3I, C2F6, etc.

[0077] In addition, the gas introduced during the over-etching process in step S13 may also include some auxiliary gases, such as one or a combination of N2, He, Ar, etc.

[0078] Please refer to Figure 3 In step (C), in step S14, the patterned photoresist layer 103 is ashed and removed using an oxygen-containing gas (which may be oxygen plasma, oxygen, or ozone, etc.). This ashing and removal process also removes the carbon-containing organic polymer on the surface of the patterned photoresist layer 103 and the entire or upper carbon-containing organic polymer inner sidewall 104' located on the sidewall of the opening 106, thereby forming a gap 107 in at least a portion of the area between the metal fluoride residue 105 and the dielectric layer sidewall at the opening 106. The formation of this gap 107 can reduce the adhesion area of ​​the metal fluoride residue 105 and reduce its adhesion, thereby making it easier to remove in the subsequent step S15. Moreover, the ashing process is used to remove the patterned photoresist layer and the carbon-containing organic polymer, including the carbon-containing organic polymer inner sidewall 104', at the same time, which is simple and low-cost.

[0079] Optionally, the line width W of the gap 107 is greater than 80 nm.

[0080] In step S14 of this embodiment, the degree of overburning during the ashing removal of the patterned photoresist layer 103 can be controlled, thereby controlling the depth of the gap 107, that is, controlling the height of the carbon-containing organic polymer inner sidewall 104' remaining at the bottom of the gap 107. This avoids the problem that the metal fluoride residue 105 is easily broken and collapsed due to the complete removal of the carbon-containing organic polymer inner sidewall 104', and adheres to the sidewall of the dielectric layer, the exposed surface of the metal layer 101, or other locations, and is difficult to be completely removed in step S15.

[0081] Optionally, in step S14, oxygen-containing gas is used to ash the patterned photoresist layer to a degree of 120% to 200%, so as to control the height of the remaining carbon-containing organic polymer inner sidewall 104' at the bottom of the gap 107 (i.e., the lower part of the sidewall of the opening 106) to be 30% to 70% of the total thickness of the dielectric layer.

[0082] Please refer to Figure 3In (D), in step S15, any suitable low-cost solvent suitable for cleaning carbon-containing polymers can be selected for post-etch cleaning (i.e., a wet process). During the cleaning process, the cleaning impact capacity can be appropriately increased by increasing any process parameter such as the solvent flow rate, impact force, or number of cleaning times. This can clean the inner sidewalls of the carbon-containing organic polymer remaining in the gap 107 while removing the remaining metal fluoride residue 105, thereby obtaining a clean surface of the dielectric layer and the metal layer 101. Moreover, using a low-cost solvent suitable for cleaning carbon-containing organic polymers for post-etch cleaning is low-cost, has low equipment requirements, and has a wide range of applications.

[0083] Optionally, the solution used for post-etch cleaning in step S15 may include, but is not limited to, at least one of DSP, DSP+, and other cleaning solutions. The DSP cleaning solution comprises H2O, H2O2, and H2SO4. The DSP+ cleaning solution comprises HF, H2O, H2O2, and H2SO4.

[0084] After step S15 , metal materials may be deposited and chemical mechanical polishing or etching may be performed to form a desired upper metal structure at the opening 106 , such as a pad, a redistribution layer, or an upper metal line.

[0085] In this embodiment, after the post-etch cleaning in step S15 is completed, the dielectric layer expands relatively outward, forming a step 101a at the top of the metal layer 101 exposed in the opening 106. The width of this step 101a depends on the thickness of the carbon-containing organic polymer inner sidewall 104' formed in step S12, or in other words, on the width of the gap 107. The height of this step depends on the degree of overetching in step S13. The presence of this step 101a increases the contact area between the metal layer 101 and the metal structure subsequently formed in the opening 106, thereby enhancing the connection reliability between the two.

[0086] Optionally, the height h of the step 101a is

[0087] Optionally, the line width W of the step 101a is

[0088] The manufacturing method of this embodiment, by using a carbon-containing gas to perform the main etching of the dielectric layer, can simultaneously form an opening and increase the accumulation of the carbon-containing organic polymer on the sidewalls of the opening, forming an inner sidewall of the carbon-containing organic polymer. The metal fluoride residue generated during the over-etching stage cannot directly contact the sidewalls of the dielectric layer, but contacts the inner sidewalls of the carbon-containing organic polymer. Therefore, after removing the patterned photoresist layer on the dielectric layer and the inner sidewalls of the carbon-containing organic polymer located at least on the upper sidewalls of the opening, a gap can be formed between the metal fluoride residue and at least a portion of the sidewall of the dielectric layer in the opening, ultimately achieving the purpose of weakening the bonding between the metal fluoride residue and the dielectric layer, making it easier to remove it during the post-etching cleaning process, thereby avoiding the adverse effects of the metal fluoride residue on device reliability and reducing the difficulty and cost of post-etching cleaning.

[0089] Second embodiment

[0090] Please refer to Figure 4 This embodiment provides a method for manufacturing a metal conductive structure, which includes the following steps:

[0091] S21, covering a dielectric layer on a substrate having a metal layer formed on its surface and forming a patterned photoresist layer on the dielectric layer to define a region of the dielectric layer to be opened;

[0092] S22, using the patterned photoresist layer as a mask, performing main etching on the dielectric layer to form an opening in the dielectric layer;

[0093] S23, depositing a carbon-containing organic polymer, and etching the carbon-containing organic polymer to form carbon-containing organic polymer inner sidewalls on the sidewalls of the opening;

[0094] S24, using the patterned photoresist layer and the inner sidewall of the carbon-containing organic polymer as a mask, over-etching along the opening using a fluorine-containing gas to open the dielectric layer and etch away a portion of the metal layer, wherein metal fluoride residues generated by the over-etching are attached to the inner sidewall of the carbon-containing organic polymer;

[0095] S25, removing the patterned photoresist layer and the carbon-containing organic polymer inner sidewall located at least on the upper portion of the sidewall of the opening, so that a gap is formed between the metal fluoride residue in the opening and at least a portion of the sidewall of the dielectric layer;

[0096] S26, performing post-etching cleaning using a wet process to remove the metal fluoride residue, and forming the metal layer exposed by the opening into a metal conductive structure.

[0097] Please refer to Figure 5In step (A), a substrate 100 having a metal layer 101 formed on its surface is provided in step S21. One or more layers of dielectric material are deposited on the substrate 100 and the metal layer 101 to form a dielectric layer. A patterned photoresist layer 103 is then formed on the dielectric layer by a photolithography process. This step S21 is substantially the same as step S11 of the first embodiment and will not be described in detail herein.

[0098] Please continue to refer to Figure 5 In (A), in step S22, the etching process in the prior art can be used to perform main etching on the dielectric layer under the masking effect of the patterned photoresist layer 103. The carbon-containing organic polymer 104 produced by the main etching on the side wall of the opening 106 is relatively thin, which is not sufficient to ensure that the metal fluoride residue will no longer adhere to the dielectric layer on the side wall of the opening 106 after the patterned photoresist layer 103 is removed.

[0099] Please refer to Figure 5 In (B) and (C), in step S23, first, a carbon-containing organic polymer layer 108 can be deposited by any suitable process such as chemical vapor deposition (CVD) or atomic layer deposition (ALD). The deposition thickness of the carbon-containing organic polymer layer 108 is reasonable, not enough to fill the opening 106, but sufficient to meet the requirement for producing a gap of the required line width on the sidewall of the opening 106. Optionally, the thickness of the formed carbon-containing organic polymer layer 108 is between 10 nm and 300 nm. Then, the carbon-containing organic polymer layer 108 is etched by any suitable etching process such as dry etching to remove the carbon-containing organic polymer layer 108 and the carbon-containing organic polymer 104 on the top surface of the patterned photoresist layer 103 and the bottom surface of the opening 106. The remaining carbon-containing organic polymer layer 108a and the carbon-containing organic polymer 104 on the sidewall of the opening 106 together constitute the carbon-containing organic polymer inner sidewall. Compared with the first embodiment, the method for forming the carbon-containing organic polymer inner sidewall in this step has a more controllable thickness and a higher consistency.

[0100] Optionally, in step S22 , the carbon content of the formed carbon-containing organic polymer layer 108 is 30% to 60% (mass fraction) to ensure that most of the carbon-containing organic polymer layer 108 can be removed together with the patterned photoresist layer 103 in the subsequent ashing process in step S25 .

[0101] Optionally, in step S22, when etching the carbon-containing organic polymer layer 108 to form the carbon-containing organic polymer inner sidewall, the etching selectivity ratio of the carbon-containing organic polymer layer 108 to the patterned photoresist layer 103 is 0.01 to 0.3. Therefore, after etching away the carbon-containing organic polymer layer 108 on the top surface of the patterned photoresist layer 103 and the bottom surface of the opening 106, in the process of further etching the carbon-containing organic polymer layer 108 on the sidewall of the opening 106 to form the carbon-containing organic polymer inner sidewall of the required thickness, a certain thickness of the patterned photoresist layer 103 is consumed, thereby reducing the difficulty of removing the patterned photoresist layer 103 and the carbon-containing organic polymer inner sidewall in the subsequent step S25. At the same time, because the thickness of the patterned photoresist layer 103 is relatively thick, the vertical etching rate of the carbon-containing organic polymer layer 108 is much greater than its lateral etching rate. Therefore, in step S22, when the carbon-containing organic polymer layer 108 has a faster vertical etching rate, the etching selectivity can help to keep the inner side wall of the carbon-containing organic polymer and the patterned photoresist layer 103 consistent in height after etching.

[0102] Please refer to Figure 5 In step (D), in step S24, the dielectric layer is overetched using the patterned photoresist layer 103 and the carbon-containing organic polymer inner sidewalls as masks to completely open the dielectric layer. The metal layer 101 is also slightly etched to extend the opening 106 to a depth of part of the top of the metal layer 101. This step S24 is substantially the same as step S13 of the first embodiment and will not be described in detail here.

[0103] Please refer to Figure 5 In step (E), in step S25, the patterned photoresist layer 103 is ashed and removed using an oxygen-containing gas (which may be oxygen plasma, oxygen, or ozone). This ashing and removal process also removes the patterned photoresist layer 103 and all or the upper portion of the carbon-containing organic polymer inner sidewalls on the sidewalls of the opening 106 (including the upper portion of the carbon-containing organic polymer 104 on the sidewalls of the opening 106 and the upper portion of the carbon-containing organic polymer layer 108), thereby forming a gap 107 between the metal fluoride residue 105 and the dielectric layer sidewalls at the opening 106. This step S25 is substantially the same as step S14 of the first embodiment and will not be described in detail here.

[0104] Please refer to Figure 5In step (F), in step S26, any suitable solvent may be selected for post-etching cleaning (i.e., a wet process) to clean the remaining carbon-containing organic polymer 104 and carbon-containing organic polymer layer 108 (i.e., the remaining carbon-containing organic polymer inner sidewalls) in the gap 107, as well as other residues after removal of the patterned photoresist layer 103, while also removing the remaining metal fluoride residue 105, thereby obtaining a clean surface of the dielectric layer and the metal layer 101. This step S26 is substantially the same as step S15 of the first embodiment and will not be described in detail here.

[0105] The method for manufacturing the metal conductive structure of this embodiment, without changing the main etching and over-etching processes of the dielectric layer in the prior art, deposits and etches a carbon-containing organic polymer layer after the main etching of the dielectric layer and before the over-etching, thereby forming a more controllable thickness on the sidewalls of the opening of the dielectric layer. The metal fluoride residues generated during the over-etching stage cannot directly contact the sidewalls of the dielectric layer, but instead contact the inner sidewalls of the carbon-containing organic polymer. Therefore, after removing the patterned photoresist layer on the dielectric layer and the carbon-containing organic polymer located at least on the upper portion of the sidewalls of the opening, a gap can be formed between the metal fluoride residues and the sidewalls of the dielectric layer in the opening, ultimately achieving the purpose of weakening the bonding between the metal fluoride residues and the dielectric layer, making them easier to remove during the post-etching cleaning process, thereby avoiding the adverse effects of the metal fluoride residues on device reliability and reducing the difficulty and cost of post-etching cleaning.

[0106] Third embodiment

[0107] Please combine Figures 2 to 5 This embodiment provides a method for manufacturing a metal conductive structure. After a dielectric layer is covered on a substrate having a metal layer formed on its surface and a patterned photoresist layer is formed on the dielectric layer to define an area of ​​the dielectric layer to be opened (i.e., after executing step S11 of the first embodiment or step S21 of the second embodiment), the dielectric layer is first subjected to main etching using step S12 of the first embodiment to form a carbon-containing organic polymer of a corresponding thickness on the sidewalls of the opening in the dielectric layer. Then, step S23 of the second embodiment is used to deposit a carbon-containing organic polymer of a corresponding thickness and perform sidewall etching, thereby forming a carbon-containing organic polymer inner sidewall of a desired thickness on the sidewalls of the opening formed after the main etching of the dielectric layer. The total thickness of the carbon-containing organic polymer inner sidewall finally formed can actually be regarded as the sum of the thickness of the carbon-containing organic polymer generated by the main etching of the dielectric layer and the thickness of the deposited carbon-containing organic polymer.

[0108] In the method for manufacturing the metal conductive structure of this embodiment, the other steps required after forming the carbon-containing organic polymer inner sidewall have been described above. For details, see steps S13 to S15 or steps S24 to S26 of the first embodiment, and will not be repeated here.

[0109] The method for manufacturing the metal conductive structure of this embodiment can achieve the effects of both the first and second embodiments, and avoid the adverse effects of metal fluoride residues generated when over-etching the dielectric layer on device reliability.

[0110] Fourth embodiment

[0111] The method for manufacturing the metal conductive structure of the present invention can be applied to the manufacture of any suitable semiconductor device such as a power device, a microcontroller, a memory, etc.

[0112] Based on this, this embodiment provides a method for manufacturing a semiconductor device, wherein at any appropriate process node, the method for manufacturing a metal conductive structure as described in any embodiment of the present invention is used to form the metal conductive structure required for manufacturing the process node.

[0113] The process node can be a metal interconnection process node, and the metal conductive structure manufactured by it can be a metal interconnection line or through-hole in any layer of the metal interconnection structure; it can also be a passivation layer etching node on the top metal layer, and the metal conductive structure manufactured by it can be a pad; it can also be a rewiring process node, and the metal conductive structure manufactured by it can be a rewiring layer.

[0114] The method for manufacturing the semiconductor device of this embodiment adopts the method for manufacturing the metal conductive structure of the present invention, so the reliability and yield of the semiconductor device manufactured thereby are improved.

[0115] The above description is only a description of the preferred embodiment of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure are within the scope of protection of the technical solution of the present invention.

Claims

1. A method for manufacturing a metal conductive structure, characterized in that: include: Covering a dielectric layer on a substrate having a metal layer formed on a surface thereof and forming a patterned photoresist layer on the dielectric layer to define an area of ​​the dielectric layer to be opened; Using the patterned photoresist layer as a mask, performing main etching on the dielectric layer to form an opening in the dielectric layer, and forming carbon-containing organic polymer inner sidewalls on the sidewalls of the opening; Using the patterned photoresist layer and the inner sidewall of the carbon-containing organic polymer as a mask, over-etching along the opening using a fluorine-containing gas to open the dielectric layer and etch away a portion of the thickness of the metal layer, wherein metal fluoride residues generated by the over-etching are attached to the inner sidewall of the carbon-containing organic polymer; removing the patterned photoresist layer and at least the carbon-containing organic polymer inner sidewall located on the upper portion of the sidewall of the opening, so as to form a gap between the metal fluoride residue in the opening and at least a portion of the sidewall of the dielectric layer; A wet process is used to perform post-etching cleaning to remove the metal fluoride residue, and the metal layer exposed by the opening is formed into a metal conductive structure.

2. The manufacturing method according to claim 1, wherein The dielectric layer is subjected to main etching using a carbon-containing gas to synchronously form carbon-containing organic polymer inner sidewalls on the sidewalls of the opening during the main etching process; and / or, after the dielectric layer is subjected to main etching, a carbon-containing organic polymer is first deposited on the surfaces of the dielectric layer and the opening, and then the carbon-containing organic polymer is etched to form carbon-containing organic polymer inner sidewalls on the sidewalls of the opening.

3. The manufacturing method according to claim 2, wherein: During the etching of the carbon-containing organic polymer, an etching selectivity ratio between the carbon-containing organic polymer and the patterned photoresist layer is between 0.01 and 0.

3.

4. The manufacturing method according to claim 1, wherein: The patterned photoresist layer is ashed and removed by using oxygen-containing gas, and the carbon-containing organic polymer inner sidewall located at least on the upper portion of the opening sidewall is also removed.

5. The manufacturing method according to claim 4, wherein: The patterned photoresist layer is ashed and removed by 120% to 200% using oxygen-containing gas, so as to control the height of the carbon-containing organic polymer inner sidewall remaining on the lower portion of the opening sidewall to be 30% to 70% of the thickness of the dielectric layer.

6. The manufacturing method according to claim 1, wherein: The metal layer is the topmost metal layer, the dielectric layer is a passivation layer, and the metal conductive structure is a pad; and / or the dielectric layer includes a silicon oxide film and a silicon nitride film stacked in sequence.

7. The manufacturing method according to claim 1, wherein: There is still residual inner sidewall of the carbon-containing organic polymer at the bottom of the gap. When a wet process is used for post-etching cleaning, a solvent suitable for cleaning the inner sidewall of the carbon-containing organic polymer is used for post-etching cleaning, and the flow rate and / or impact force of the solvent are increased during the cleaning process to clean the remaining inner sidewall of the carbon-containing organic polymer in the gap while removing the remaining metal fluoride residue; and / or, after completing the post-etching cleaning, the dielectric layer expands relatively outward, so that a step is formed on the top of the metal layer exposed in the opening.

8. The manufacturing method according to claim 7, wherein: The height of the step of the metal layer is 100Å~50nm; and / or the line width of the step of the metal layer is 100Å~300nm.

9. The manufacturing method according to claim 1, wherein: Include at least one of the following parameters: (1) The material of the metal layer includes at least one of Cu, Al, W, Au, Pt, Ti and Ag; (2) The thickness of the dielectric layer is 1 μm to 1.5 μm; (3) The thickness of the patterned photolithography layer on the dielectric layer is 3.5 μm to 5 μm; (4) At least one opening is formed in the dielectric layer, and the area of ​​a single opening is greater than 3000 μm 2 ; (5) at least one opening is formed in the dielectric layer, and an opening ratio of the dielectric layer is between 5% and 30%; (6) The etching gas used in the main etching contains not only carbon but also fluorine and / or hydrogen; (7) The thickness of the inner side wall of the carbon-containing organic polymer is 10 nm to 300 nm; (8) The mass percentage of carbon element in the inner wall of the carbon-containing organic polymer is 30% to 60%; (9) The over-etching depth of the metal layer is less than 30 nm; (10) The thickness of the metal fluoride residue produced by the over-etching on the inner sidewall of the carbon-containing organic polymer is less than 50 nm; (11) The line width of the gap is greater than 80 nm.

10. A method for manufacturing a semiconductor device, characterized in that: The desired metal conductive structure is formed by adopting the method for manufacturing the metal conductive structure according to any one of claims 1 to 9.

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