Aluminum pad structure and method of making same

Abstract

The application provides an aluminum pad structure and a manufacturing method thereof. The manufacturing method of the aluminum pad structure comprises the following steps: sequentially forming a first aluminum layer, a protective layer and a passivation layer on a substrate; performing dry etching on the passivation layer by using a plasma containing fluoride ions to form a passivation layer opening, wherein the passivation layer opening is located above a preset region of the first aluminum layer and the bottom surface of the passivation layer opening stays on the surface of the protective layer; then forming a second aluminum layer on the protective layer and removing the part of the second aluminum layer which is higher than the passivation layer, thereby obtaining a sandwich-type aluminum pad structure composed of the first aluminum layer, the protective layer and the second aluminum layer. The manufacturing method of the aluminum pad structure can avoid the direct contact of the etching process with the aluminum pad, thereby eliminating the generation of aluminum fluoride compound residues and fluoride ion residues on the surface of the aluminum pad from the root. The aluminum pad structure is in a sandwich type, has less aluminum fluoride compound residues and fluoride ion residues, is beneficial to improve the bonding and yield test results, and reduces fluorine precipitation.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology and relates to an aluminum pad structure and its manufacturing method. Background Technology

[0002] Due to its low melting point, good electrical conductivity, and excellent air stability, aluminum (Al) is commonly used as a bonding pad in wafer fabrication. The aluminum pad serves as the interconnect interface between the wafer and the external environment, and is also the final step in the integrated circuit manufacturing process. It is typically formed by physical vapor deposition (PVD) to create a thin aluminum film on the top metal surface of the wafer. Furthermore, to protect the semiconductor surface from environmental damage such as chemical contamination, harmful particles, or moisture, a passivation layer, usually silicon nitride or silicon oxide, is deposited on the aluminum pad. Then, photolithography and etching processes are used to selectively expose portions of the passivation layer to reveal the aluminum pad, which serves as leads for electrical testing and packaging, preparing for subsequent packaging work. The passivation layer opening process requires a dry etching process using fluorine (F) plasma. The use of fluorine plasma has two problems: First, it is difficult to avoid the fluorine plasma coming into contact with the aluminum pad surface. When the fluorine plasma comes into contact with the aluminum pad surface, it will generate aluminum fluoride compounds (AlFx) that are difficult to remove, affecting subsequent bonding and yield test results. Second, fluoride ions are difficult to remove completely. When wafer shipment batches (lots) are left for a long time and in poor environment, fluorine precipitation and crystallization are likely to occur.

[0003] One method for removing aluminum fluoride compound residues is to use multiple ashing processes combined with wet cleaning. However, when there are a lot of aluminum fluoride compound residues, it is difficult to remove them completely, and multiple cleaning processes will aggravate the damage and electrochemical corrosion of the aluminum pads.

[0004] To avoid the formation of AlFx residues, one approach is to use non-metallic films such as silicon nitride films or silicon oxide films as sacrificial layers to protect the aluminum pads. However, these non-metallic films are difficult to remove and can easily damage the passivation layer and the surface of the aluminum pads that the process itself is intended to retain.

[0005] To reduce fluoride ion residue, one approach is to reduce the proportion of fluoride ions used in dry etching or reduce the introduction of fluoride into wet cleaning solutions, but this will reduce etching and cleaning capabilities to some extent. Another approach is to use a large amount of deionized water (DI) in the wet cleaning process, but this still cannot completely remove fluoride ion residue.

[0006] Therefore, how to provide an aluminum pad structure and its manufacturing method to reduce aluminum fluoride compound residue and fluoride ion residue has become an important technical problem that urgently needs to be solved by those skilled in the art.

[0007] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of this application and facilitating understanding by those skilled in the art. It should not be assumed that these technical solutions are known to those skilled in the art simply because they have been described in the background section of this application. Summary of the Invention

[0008] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide an aluminum pad structure and its manufacturing method, which solves the problems in the prior art where residual aluminum fluoride compounds affect bonding and yield test results, and residual fluoride ions affect wafer quality.

[0009] To achieve the above and other related objectives, the present invention provides a method for manufacturing an aluminum pad structure, comprising the following steps:

[0010] A substrate is provided, and a first aluminum layer is formed on the substrate;

[0011] A protective layer is formed on the first aluminum layer;

[0012] A passivation layer is formed on the protective layer;

[0013] A passivation layer opening is formed in the passivation layer by dry etching. The plasma used in the dry etching contains fluorine ions. The passivation layer opening is located above a preset area of ​​the first aluminum layer, and the bottom surface of the passivation layer opening rests on the surface of the protective layer.

[0014] A second aluminum layer is formed on the protective layer;

[0015] The portion of the second aluminum layer above the passivation layer is removed to obtain a sandwich-type aluminum pad structure composed of the first aluminum layer, the protective layer, and the second aluminum layer.

[0016] Optionally, before forming the first aluminum layer on the substrate, the method further includes the step of forming a diffusion barrier layer on the surface of the substrate, wherein the first aluminum layer is formed on the surface of the diffusion barrier layer.

[0017] Optionally, the protective layer includes a titanium nitride layer.

[0018] Optionally, in the sandwich-type aluminum pad structure, the thickness of the second aluminum layer is greater than the thickness of the first aluminum layer.

[0019] Optionally, the method for removing the portion of the second aluminum layer above the passivation layer includes chemical mechanical polishing.

[0020] Optionally, before forming the second aluminum layer on the protective layer, the method further includes the step of performing wet cleaning to remove dry etching byproducts.

[0021] Optionally, before forming the second aluminum layer on the protective layer, the method further includes the step of forming a diffusion barrier layer on the sidewall of the passivation layer opening.

[0022] Optionally, the passivation layer may have a single-layer or multi-layer structure.

[0023] Optionally, the upper surface of the substrate is provided with through holes, and the first aluminum layer is also filled into the through holes.

[0024] The present invention also provides an aluminum pad structure, comprising:

[0025] Base;

[0026] A passivation layer is located on the substrate, and the passivation layer has an opening;

[0027] The sandwich-type aluminum pad structure includes a first aluminum layer, a protective layer, and a second aluminum layer arranged sequentially from bottom to top. The second aluminum layer is located in the opening of the passivation layer. The stacked structure composed of the first aluminum layer and the protective layer includes a functional portion located below the second aluminum layer and an extension portion extending into the interface between the substrate and the passivation layer.

[0028] As described above, the method for fabricating the aluminum pad structure of the present invention first involves sequentially forming a first aluminum layer, a protective layer, and a passivation layer on a substrate. Then, a plasma containing fluorine ions is used to dry-etch the passivation layer to form an opening. This opening is located above a predetermined area of ​​the first aluminum layer, and the bottom surface of the passivation layer opening rests on the surface of the protective layer. Next, a second aluminum layer is formed on the protective layer, and the portion of the second aluminum layer above the passivation layer is removed, resulting in a sandwich-type aluminum pad structure composed of the first aluminum layer, the protective layer, and the second aluminum layer. The method for fabricating the aluminum pad structure of the present invention avoids direct contact between the etching process and the aluminum pad, fundamentally eliminating the generation of aluminum fluoride compound residues and fluorine ion residues on the surface of the aluminum pad. The sandwich-type aluminum pad structure of the present invention has fewer aluminum fluoride compound residues and fluorine ion residues, which is beneficial for improving bonding and yield test results, and reducing fluorine precipitation. Attached Figure Description

[0029] Figure 1 The diagram shows the structure obtained after the aluminum pad, passivation layer and photoresist layer are formed on the substrate during the formation of an aluminum pad, and after exposure and development to obtain the opening of the photoresist layer.

[0030] Figure 2 The diagram shows the structure obtained after dry etching of the passivation layer based on the opening of the photoresist layer during the formation of an aluminum pad, revealing the aluminum pad.

[0031] Figure 3 This diagram shows the structure obtained after removing the photoresist layer during the formation of an aluminum pad.

[0032] Figure 4 The diagram shows that aluminum fluoride compounds remain on the sidewalls and bottom of the opened area.

[0033] Figure 5 The diagram shown illustrates the process flow of the method for manufacturing the aluminum pad structure of the present invention.

[0034] Figure 6 The diagram shown is a schematic diagram of the structure obtained after forming the first aluminum layer on the substrate, which is a method for manufacturing the aluminum pad structure of the present invention.

[0035] Figure 7 The diagram shown illustrates the structure obtained after forming a protective layer on the first aluminum layer, as described in the method for manufacturing the aluminum pad structure of the present invention.

[0036] Figure 8 The diagram shown illustrates the structure obtained after forming a passivation layer on a protective layer, as described in the method for manufacturing the aluminum pad structure of the present invention.

[0037] Figure 9 The diagram shown is a schematic diagram of the structure obtained after forming an opening in the passivation layer, which is the method for manufacturing the aluminum pad structure of the present invention.

[0038] Figure 10 The diagram shown is a schematic diagram of the structure obtained after forming a second aluminum layer on a protective layer, as described in the method for manufacturing the aluminum pad structure of the present invention.

[0039] Figure 11 The diagram shown is a schematic of the structure obtained after removing the portion of the second aluminum layer above the passivation layer, which is a method for manufacturing the aluminum pad structure of the present invention.

[0040] Explanation of reference numerals in the attached figures

[0041] 101 base

[0042] 102 Aluminum Pad

[0043] 103 Passivation layer

[0044] 104 Photoresist layer

[0045] 105 Openings in the photoresist layer

[0046] 106 Aluminum Fluorine Compounds

[0047] Steps S1 to S6

[0048] 201 base

[0049] 2011 Silicon nitride layer

[0050] 2012 Low-K dielectric layer

[0051] 2013 Through Hole

[0052] 202 First aluminum layer

[0053] 203 Diffusion Barrier Layer

[0054] 204 protective layer

[0055] 205 passivation layer

[0056] 2051 silicon oxide layer

[0057] 2052 silicon nitride layer

[0058] 206 Passivation layer opening

[0059] 207 Second aluminum layer

[0060] 208 Diffusion Barrier Layer Detailed Implementation

[0061] Please see Figures 1 to 3 The diagram shows the structural features of an aluminum pad formed through various steps, where:

[0062] (1) As Figure 1 As shown, an aluminum pad 102, a passivation layer 103 and a photoresist layer 104 are first formed on a substrate 101, and then exposure and development are performed to obtain an opening 105 in the photoresist layer.

[0063] (2) Figure 2 As shown, the passivation layer 103 is dry-etched based on the photoresist layer opening 105 to expose the aluminum pad 102;

[0064] (3) Figure 3 As shown, dry cleaning is performed to remove the photoresist layer 104, followed by wet cleaning.

[0065] In the above steps, during the process of dry etching the passivation layer 103 based on the photoresist layer opening 105 to expose the aluminum pad 102, it is easy to over-etch the aluminum pad 102 to the bottom, causing the dry etching gas to contact the bottom aluminum layer, resulting in the generation of a large amount of aluminum fluoride compound residue. These aluminum fluoride compound residues are difficult to remove, making the open area prone to severe pitting defects and aluminum fluoride compound residue defects.

[0066] For example, please refer to Figure 4 The diagram shows that after the dry cleaning and wet cleaning steps, aluminum fluoride compound 106 remains on the sidewalls and bottom of the opened area.

[0067] Through extensive analysis, research and experimentation, the inventors of this application have improved the manufacturing process of aluminum pads, which can help reduce the residual aluminum fluoride compounds and fluoride ions on the surface of aluminum pads and improve structural stability.

[0068] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0069] It should be emphasized that the term "including / comprises" as used herein refers to the presence of a feature, whole, step, or component, but does not exclude the presence or addition of one or more other features, wholes, steps, or components.

[0070] Features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0071] In the detailed description of embodiments of the present invention, for ease of explanation, the schematic diagrams illustrating the device structure may be partially enlarged without adhering to the general scale, and the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. Furthermore, in actual manufacturing, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0072] For ease of description, spatial relation terms such as “below,” “under,” “lower than,” “below,” “above,” and “upper” may be used herein to describe the relationship between one element or feature shown in the accompanying drawings and other elements or features. It will be understood that these spatial relation terms are intended to include directions other than those depicted in the drawings for devices in use or operation. Furthermore, when a layer is referred to as being “between” two layers, it may be the only layer between the two layers, or there may be one or more layers in between.

[0073] In the context of this application, the structure described above the first feature may include embodiments in which the first and second features are in direct contact, or embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0074] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0075] This invention provides a method for manufacturing an aluminum pad structure; please refer to [link / reference]. Figure 5The diagram shows the process flow of this method, which includes the following steps:

[0076] S1: Provide a substrate and form a first aluminum layer on the substrate;

[0077] S2: A protective layer is formed on the first aluminum layer;

[0078] S3: Form a passivation layer on the protective layer;

[0079] S4: A passivation layer opening is formed in the passivation layer by dry etching. The plasma used in the dry etching contains fluorine ions. The passivation layer opening is located above a preset area of ​​the first aluminum layer, and the bottom surface of the passivation layer opening rests on the surface of the protective layer.

[0080] S5: Form a second aluminum layer on the protective layer;

[0081] S6: Remove the portion of the second aluminum layer above the passivation layer to obtain a sandwich-type aluminum pad structure composed of the first aluminum layer, the protective layer and the second aluminum layer.

[0082] The following section will detail each of the above steps in conjunction with the structural diagram.

[0083] Please refer to the following first. Figure 6 Perform step S1: Provide a substrate 201 and form a first aluminum layer 202 on the substrate 201.

[0084] As an example, the substrate 201 can be a silicon substrate, germanium substrate, germanium-silicon substrate, silicon carbide substrate, or a III-V compound substrate (such as gallium nitride, gallium arsenide, etc.), or a composite substrate such as silicon-on-insulator (SOI), germanium-on-insulator (GOI), or germanium-silicon-on-insulator. The substrate 201 can be doped or undoped, and can contain doped regions of various concentrations or electrical types to achieve different functions. A semiconductor device (not shown), such as a MOS transistor, can be formed in the substrate 201, and the substrate 201 can include an interconnect layer electrically connected to the semiconductor device. The interconnect layer includes at least one metal interconnect line, and includes interlayer vias and interlayer dielectric layers.

[0085] In one embodiment, for example Figure 6 As shown, the substrate 201 includes a silicon nitride layer 2011 on an interconnect layer (not shown) and a low-k dielectric layer 2012 on the silicon nitride layer 2011. A via 2013 is provided on the upper surface of the substrate 201, the via 2013 penetrating the low-k dielectric layer 2012 and the silicon nitride layer 2011. The first aluminum layer 202 is also filled into the via 2013 to electrically connect with the underlying interconnect layer.

[0086] As an example, the first aluminum layer 202 can be formed using physical vapor deposition (PVD), chemical vapor deposition (CVD), or other suitable methods.

[0087] As an example, in order to prevent aluminum from diffusing into the underlying material layer, before forming the first aluminum layer 202 on the substrate 201, a diffusion barrier layer 203 is formed on the surface of the substrate 201, wherein the first aluminum layer 202 is formed on the surface of the diffusion barrier layer 203.

[0088] As an example, the diffusion barrier layer 203 may be selected from one or more of titanium (Ti) layer, titanium nitride (TiN) layer, tantalum (Ta) layer, and tantalum nitride (TaN) layer, or other suitable material layers.

[0089] As an example, the surface of the first aluminum layer 202 can be a flat surface or it can have a certain depression at the through hole.

[0090] As an example, after the first aluminum layer 202 is formed, it can be patterned as needed. The specific pattern can be designed according to the actual interconnection requirements, and no specific limitations are imposed in this invention.

[0091] Please see again Figure 7 Step S2 is performed: a protective layer 204 is formed on the first aluminum layer 202.

[0092] Specifically, the main purpose of forming the protective layer 204 is to protect the surface of the first aluminum layer 202 from direct contact with the dry etching plasma during the subsequent dry etching process of opening the passivation layer, especially from direct contact with F ions, thereby eliminating the generation of aluminum fluoride compound residues and fluoride ion residues on the surface of the aluminum pad from the root.

[0093] In addition, the protective layer 204 serves as a protective layer for the first aluminum layer 202, and also as a diffusion barrier layer for the second aluminum layer to be formed subsequently, reducing the diffusion of aluminum.

[0094] Furthermore, the protective layer 204 also serves as an etching stop layer during subsequent etching of the passivation layer. It is necessary to prevent the protective layer 204 from being etched through, which would allow the dry etching plasma to come into contact with the first aluminum layer 202.

[0095] As an example, the protective layer 204 may include a titanium nitride layer, which may be formed using physical vapor deposition (PVD), chemical vapor deposition (CVD) or other suitable methods.

[0096] Please see again Figure 8Then, perform step S3: form a passivation layer 205 on the protective layer 204.

[0097] As an example, the passivation layer 205 can be a single-layer structure or a multi-layer structure.

[0098] As an example, the passivation layer 205 includes one or more of a silicon oxide layer and a silicon nitride layer. In one embodiment, for example... Figure 8 As shown, the passivation layer 205 includes a silicon oxide layer 2051 and a silicon nitride layer 2052 deposited sequentially.

[0099] Please see again Figure 9 Step S4 is performed: a passivation layer opening 206 is formed in the passivation layer 205 by dry etching. The plasma used in the dry etching contains fluorine ions. The passivation layer opening 206 is located above a preset area of ​​the first aluminum layer 202. The bottom surface of the passivation layer opening 206 rests on the surface of the protective layer.

[0100] Specifically, the open area of ​​the passivation layer 205 (i.e., the area where the passivation layer opening 206 is located) is determined by the area that actually needs to be bonded, and the open area can be defined in advance by the mask.

[0101] As an example, forming the passivation layer opening 206 in the passivation layer 205 using dry etching includes the following steps:

[0102] (1) A photoresist layer (not shown) is formed on the passivation layer 205 by spin coating or other suitable methods, and the photoresist layer is patterned by photolithography processes such as exposure and development.

[0103] (2) Using the patterned photoresist layer as a mask and the protective layer 204 as an etching stop layer, the passivation layer 205 is dry etched to obtain the passivation layer opening 206.

[0104] As an example, the etching gas used in the dry etching process includes, but is not limited to, fluorine-containing compounds such as CF4, CHF3, C3F8, and C4F8, which can be ionized to generate fluorine ions that bombard the surface of the passivation layer 205 to achieve etching.

[0105] Specifically, the dry etching stopping on the protective layer 204 can reduce the effect of plasma on the first aluminum layer 202, avoid severe pitting defects in the passivation layer opening area, and reduce aluminum fluoride (AlF) compounds. xThe formation of residual fluoride ions and voids refers to the formation of tiny holes or pits on the surface of the film, while aluminum fluoride compound residual defects refer to aluminum fluoride compound particles attached to the sidewalls and bottom of the open area. Both void and aluminum fluoride compound residual defects have a serious impact on device performance, such as affecting subsequent bonding and yield test results. Under certain conditions, such as when the shipment lot is left for a long time in a poor environment, fluoride ion residual can easily precipitate and crystallize, affecting product quality.

[0106] As an example, after forming the passivation layer opening 206, a dry stripping step is included to remove the photoresist layer and dry etching residues. The dry stripping uses plasma or chemical gases to remove the photoresist layer and dry etching residues, typically performed in a low-pressure plasma environment. Advantages of dry stripping include better directional control and linewidth control.

[0107] As an example, the invention also includes a step of performing a wet strip to remove dry etching byproducts. The wet strip may use a hydrofluoric acid solution. The present invention utilizes the protective layer 204 to protect the first aluminum layer 202, and the thickness of the first aluminum layer 202 is only a portion of the thickness of the final formed aluminum pad. There are few or no aluminum fluoride compounds remaining. The hydrofluoric acid solution may be used at a lower concentration, which can reduce the introduction of fluorine in the cleaning process without reducing the cleaning capacity, further reducing fluoride ion residue and reducing the probability of fluorine precipitation from wafer storage devices.

[0108] Please see again Figure 10 Then, perform step S5: form a second aluminum layer 207 on the protective layer 204.

[0109] As an example, before forming the second aluminum layer 207 on the protective layer 204, the method further includes forming a diffusion barrier layer 208 on the sidewall of the passivation layer opening 206. The diffusion barrier layer 208 may include a titanium nitride layer and may be formed using physical vapor deposition (PVD), chemical vapor deposition (CVD), or other suitable methods.

[0110] As an example, the second aluminum layer 207 can be formed using physical vapor deposition (PVD), chemical vapor deposition (CVD), or other suitable methods. The second aluminum layer 207 fills the passivation layer opening 206 to cover the exposed protective layer 204 and the upper surface of the passivation layer 205.

[0111] Specifically, the protective layer 204 can serve as a diffusion barrier layer for the second aluminum layer 207, reducing the diffusion of aluminum.

[0112] Please see again Figure 11 Then, perform step S6: remove the portion of the second aluminum layer 207 that is higher than the passivation layer 205 to obtain a sandwich-type aluminum pad structure composed of the first aluminum layer 202, the protective layer 204 and the second aluminum layer 207.

[0113] As an example, a method for removing the portion of the second aluminum layer 207 above the passivation layer 205 includes chemical mechanical polishing (CMP), after which the upper surface of the passivation layer 205 is exposed.

[0114] As an example, the second aluminum layer 207 in the passivation layer opening 206 can be thinned to the required thickness as needed.

[0115] Specifically, the thickness of the first aluminum layer 202 and the second aluminum layer 207 in the sandwich-type aluminum pad structure can be adjusted according to actual testing needs. In some embodiments, in the sandwich-type aluminum pad structure, the thickness of the second aluminum layer 207 is greater than the thickness of the first aluminum layer 202.

[0116] Specifically, in the sandwich-type aluminum pad structure, the second aluminum layer 207 is deposited after the step of opening the passivation layer 205, and is not affected by the dry etching plasma (especially F plasma) when opening the passivation layer 205. The dry etching plasma when opening the passivation layer 205 does not have the opportunity to directly contact the second aluminum layer 207. Therefore, setting the thickness of the second aluminum layer 207 to be greater than the thickness of the first aluminum layer 202, that is, the process of thinning the aluminum layer first and then the aluminum layer later, can better reflect the advantages of the aluminum pad structure manufacturing method of the present invention. Without reducing the performance of the aluminum pad, it reduces or eliminates the generation of aluminum fluoride compound residues and fluoride ion residues on the surface of the aluminum pad.

[0117] In some embodiments of the present invention, an aluminum pad structure is also provided. This aluminum pad structure is sandwich-shaped, with less residual aluminum fluoride compounds and fluoride ions, which is beneficial for improving bonding and yield test results, and reducing fluoride precipitation. Please refer to [link to relevant documentation]. Figure 11 The diagram shows a schematic of the aluminum pad structure, including a substrate 201, a passivation layer 205, and a sandwich-type aluminum pad structure. The passivation layer 205 is located on the substrate 201 and has a passivation layer opening 2061. The sandwich-type aluminum pad structure includes a first aluminum layer 202, a protective layer 204, and a second aluminum layer 207 arranged sequentially from bottom to top. The second aluminum layer 207 is located in the passivation layer opening 2061. The stacked structure composed of the first aluminum layer 202 and the protective layer 207 includes a functional portion located below the second aluminum layer 207 and an extension portion extending into the interface between the substrate 201 and the passivation layer 205.

[0118] Specifically, the functional portion is located in the opening area of ​​the passivation layer opening 2061. Together with the second aluminum layer 207 in the passivation layer opening 2061, it realizes the functions of bonding and testing. The extension portion can expand the electrical connection area of ​​the sandwich-type aluminum pad structure based on the bonding area to achieve better interconnection effect. Moreover, the extension portion is buried under the passivation layer 205 and does not come into contact with the outside world, which helps to improve the reliability of the aluminum pad.

[0119] In summary, the method for fabricating the aluminum pad structure of the present invention first involves sequentially forming a first aluminum layer, a protective layer, and a passivation layer on a substrate. Then, a plasma containing fluorine ions is used to dry-etch the passivation layer to form an opening. This opening is located above a predetermined area of ​​the first aluminum layer, and its bottom surface rests on the surface of the protective layer. Next, a second aluminum layer is formed on the protective layer, and the portion of the second aluminum layer above the passivation layer is removed, resulting in a sandwich-type aluminum pad structure composed of the first aluminum layer, the protective layer, and the second aluminum layer. This method avoids direct contact between the aluminum pad and the etching process, eliminating the generation of aluminum fluoride compound residues and fluorine ion residues on the aluminum pad surface at the source. The sandwich-type aluminum pad structure of the present invention has fewer aluminum fluoride compound residues and fluorine ion residues, which is beneficial for improving bonding and yield test results and reducing fluorine precipitation. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial applicability.

[0120] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method of making an aluminum gasket structure, comprising: Includes the following steps: A substrate is provided, and a first aluminum layer is formed on the substrate; A protective layer is formed on the first aluminum layer; A passivation layer is formed on the protective layer; A passivation layer opening is formed in the passivation layer by dry etching. The plasma used in the dry etching contains fluorine ions. The passivation layer opening is located above a preset area of ​​the first aluminum layer, and the bottom surface of the passivation layer opening rests on the surface of the protective layer. A second aluminum layer is formed on the protective layer; The portion of the second aluminum layer above the passivation layer is removed to obtain a sandwich-type aluminum pad structure composed of the first aluminum layer, the protective layer, and the second aluminum layer.

2. The method of claim 1, wherein: Before forming the first aluminum layer on the substrate, the method further includes the step of forming a diffusion barrier layer on the surface of the substrate, wherein the first aluminum layer is formed on the surface of the diffusion barrier layer.

3. The method of manufacturing an aluminum gasket structure according to claim 1 or 2, characterized by: The protective layer includes a titanium nitride layer.

4. The method of making an aluminum gasket structure of claim 1, wherein: In the sandwich-type aluminum pad structure, the thickness of the second aluminum layer is greater than the thickness of the first aluminum layer.

5. The method for manufacturing the aluminum pad structure according to any one of claims 1, 2, or 4, characterized in that: Methods for removing the portion of the second aluminum layer above the passivation layer include chemical mechanical polishing.

6. The method for manufacturing the aluminum pad structure according to any one of claims 1, 2, or 4, characterized in that, Before forming the second aluminum layer on the protective layer, the method further includes the following steps: performing wet cleaning to remove dry etching byproducts.

7. The method for manufacturing the aluminum pad structure according to any one of claims 1, 2, or 4, characterized in that, Before forming the second aluminum layer on the protective layer, the method further includes the step of forming a diffusion barrier layer on the sidewall of the passivation layer opening.

8. The method for manufacturing the aluminum pad structure according to any one of claims 1, 2, or 4, characterized in that: The passivation layer can be a single-layer or multi-layer structure.

9. The method for manufacturing the aluminum pad structure according to claim 1, characterized in that: The upper surface of the substrate is provided with through holes, and the first aluminum layer is also filled into the through holes.

10. An aluminum pad structure, characterized in that, include: Base; A passivation layer is located on the substrate, and the passivation layer has an opening; The sandwich-type aluminum pad structure includes a first aluminum layer, a protective layer, and a second aluminum layer arranged sequentially from bottom to top. The second aluminum layer is located in the opening of the passivation layer. The stacked structure composed of the first aluminum layer and the protective layer includes a functional portion located below the second aluminum layer and an extension portion extending into the interface between the substrate and the passivation layer.

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