Methods to improve the identification of bottom metal and pad

Abstract

The present invention provides a method for improving the identification of bottom metal and pad, the method comprising: providing a substrate, forming a first mask layer with a first window and bottom metal, removing the first mask layer, forming a second mask layer with a second window, forming a pad, removing the second mask layer, performing a roughening etching process on the bottom metal around the pad, and then forming a metal wire on the pad. The bottom metal around the pad can be roughened and etched to increase the roughness of this part of the bottom metal, thereby increasing the roughness difference between the pad and the bottom metal around it that is roughened and etched, making the two easier to identify and distinguish, thereby facilitating accurate and effective preparation of metal wires on the pad and improving the yield of metal wire preparation.

Description

Technical Field

[0001] The invention belongs to the field of packaging, and in particular relates to a method for improving the recognition of bottom metal and welding pad. Background Art

[0002] The general definition of wafer level packaging (WLP) is: most or all packaging and testing procedures are performed directly on the wafer, and then cut (Singulation) into a single chip (Chip). Due to WLP's high packaging density, fast packaging speed and low packaging cost, it has become one of the more advanced packaging methods and has been widely used.

[0003] In the existing packaging process, it is necessary to identify and distinguish the metal layer and the lead-out pad formed on this metal layer, and there is a problem that it is difficult to effectively distinguish between the two. For example, in the packaging process, after the pad metal is formed on the grounding metal (such as GND Cu), the two often need to be identified so that metal wires can be prepared on the pad metal. If the morphology, roughness and other factors affecting the identification between the two are similar, it is difficult to effectively distinguish the two, which will inevitably affect the yield of subsequent metal wire preparation and the yield of the product.

[0004] Therefore, it is necessary to provide a method for improving the identification of the bottom metal and the pad to solve the above problems. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a method for improving the identification of bottom metal and welding pad, so as to solve the problem that the welding pad and the bottom metal around it are difficult to effectively distinguish in the prior art.

[0006] To achieve the above objectives and other related objectives, the present invention provides a method for improving the identification of bottom metal and pad, the method comprising:

[0007] providing a substrate;

[0008] forming a first mask layer on the substrate, wherein the first mask layer includes a first window defining a bottom metal position;

[0009] forming the bottom metal in the first window;

[0010] removing the first mask layer;

[0011] forming a second mask layer on the substrate, wherein the second mask layer surrounds the bottom metal and comprises a second window defining a pad, wherein the second window exposes the bottom metal;

[0012] forming a welding pad in the second window;

[0013] removing the second mask layer to expose the pad and the bottom metal around the pad;

[0014] Performing a roughening etching process on the exposed bottom metal to increase the roughness of the bottom metal; and

[0015] A metal line is formed on the bonding pad.

[0016] Optionally, the pad includes a buffer barrier layer and a metal layer sequentially formed on the bottom metal surface in the second window.

[0017] Optionally, the buffer barrier layer includes a Ni layer; the metal layer includes an Au layer; and the bottom metal material includes Cu.

[0018] Optionally, the thickness of the buffer barrier layer is between 1.8 μm and 2.2 μm; the thickness of the metal layer is between 0.1 μm and 1 μm; and the thickness of the bottom metal is between 3 μm and 6 μm.

[0019] Optionally, a seed layer is further formed on the substrate, the first window exposes the seed layer, the first mask layer and the bottom metal are both formed on the seed layer, and the seed layer is removed after the second mask layer is removed.

[0020] Optionally, the seed layer includes an adhesion layer and an upper metal layer sequentially formed on the substrate, the material of the upper metal layer is consistent with the material of the bottom metal, and the roughening etching process is performed during the removal of the upper metal layer.

[0021] Optionally, the substrate includes a supporting layer, a peeling layer formed on the supporting layer, and a dielectric layer formed on the peeling layer, wherein the bottom metal is formed on the dielectric layer based on the first window.

[0022] Optionally, the process of forming the metal wire includes a wire bonding process.

[0023] Optionally, the thickness of the bottom metal etched and removed by the roughening etching process is between 0.1 μm and 2 μm.

[0024] Optionally, the temperature of the etching solution for the roughening etching process is between 21-25°C.

[0025] The present invention also provides another method for improving the identification of the bottom metal and the pad, the method comprising:

[0026] providing a substrate;

[0027] forming a first mask layer on the substrate, wherein the first mask layer includes a first window defining a bottom metal position;

[0028] forming the bottom metal in the first window;

[0029] forming a pad mask layer on the structure formed with the bottom metal and the first mask layer, wherein the pad mask layer comprises a second window defining a pad, and the second window exposes the bottom metal;

[0030] forming a welding pad in the second window;

[0031] Removing the pad mask layer and the first mask layer to expose the pad and the bottom metal around it;

[0032] Performing a roughening etching process on the exposed bottom metal to increase the roughness of the bottom metal; and

[0033] A metal line is formed on the bonding pad.

[0034] Optionally, the area of ​​the pad is between 1% and 10% of the bottom metal area.

[0035] As described above, the method of improving the identification of the bottom metal and the welding pad of the present invention can increase the roughness of this part of the bottom metal by roughening and etching the bottom metal around the welding pad, thereby increasing the roughness difference between the welding pad and the bottom metal around it that has been roughened and etched, making the two easier to identify and distinguish, which is beneficial to accurately and effectively prepare metal wires on the welding pad and improve the yield of metal wire preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The flowchart of the method for improving the identification of the bottom metal and the bonding pad according to the first embodiment is shown.

[0037] Figure 2 It is a schematic diagram showing the structure of a substrate provided in the process of the method for improving the identification of the bottom metal and the pad in the first embodiment.

[0038] Figure 3 It is a schematic diagram showing the formation of a first mask layer in the process of the method for improving the identification of the bottom metal and the bonding pad according to the first embodiment.

[0039] Figure 4 It is a schematic diagram showing the formation of bottom metal in the process of the method for improving the identification between bottom metal and bonding pad according to the first embodiment.

[0040] Figure 5 It is a schematic diagram showing the removal of the first mask layer during the method for improving the identification of the bottom metal and the bonding pad according to the first embodiment.

[0041] Figure 6 It is a schematic diagram showing the formation of a second mask layer in the process of the method for improving the identification of the bottom metal and the bonding pad according to the first embodiment.

[0042] Figure 7 It is a schematic diagram showing the formation of a bonding pad in the process of the method for improving the identification between the bottom metal and the bonding pad according to the first embodiment.

[0043] Figure 8 It is a schematic diagram showing the removal of the second mask layer during the method for improving the identification of the bottom metal and the bonding pad according to the first embodiment.

[0044] Fig. 9 It is a schematic diagram showing the formation of metal lines in the process of the method for improving the identification between the bottom metal and the bonding pad according to the first embodiment.

[0045] FIG10 shows the difference in roughness between the bonding pad and the bottom metal around it in Example 1, wherein FIG10( a) shows the difference in roughness between the two before the roughening etching treatment is performed, and FIG10( b) shows the difference in roughness between the two after the roughening etching treatment is performed.

[0046] Fig.11 It is a schematic diagram showing the formation of a pad mask layer in the process of the method for improving the identification between the bottom metal and the pad according to the second embodiment.

[0047] Component number description

[0048] 101 Base

[0049] 101a Support layer

[0050] 101b Peeling layer

[0051] 101c Dielectric Layer

[0052] 102 first mask layer

[0053] 102a First Window

[0054] 103 Bottom Metal

[0055] 104 Second mask layer

[0056] 104a Second Window

[0057] 105 Solder pad

[0058] 105a Buffer barrier layer

[0059] 105b Metal layer

[0060] 106 Metal Wire

[0061] 200 Pad mask layer

[0062] 200a Second Window

[0063] Steps S1 to S9 DETAILED DESCRIPTION

[0064] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0065] For example, when describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional view showing the device structure will not be partially enlarged according to the general scale, and the schematic view is only an example, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional space dimensions of length, width and depth should be included.

[0066] For ease of description, spatially relative terms such as "under", "below", "below", "below", "above", "on", etc. may be used herein to describe the relationship of one element or feature shown in the drawings to other elements or features. It will be understood that these spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the drawings. In addition, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

[0067] In the context of the present application, a structure in which a first feature is described as being "above" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include 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.

[0068] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and therefore the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0069] like Figure 1-1 0, the present invention provides a method for improving the identification of bottom metal and pad, the method comprising:

[0070] providing a substrate;

[0071] forming a first mask layer on the substrate, wherein the first mask layer includes a first window defining a bottom metal position;

[0072] forming the bottom metal in the first window;

[0073] removing the first mask layer;

[0074] forming a second mask layer on the substrate, wherein the second mask layer surrounds the bottom metal and comprises a second window defining a pad, wherein the second window exposes the bottom metal;

[0075] forming a welding pad in the second window;

[0076] removing the second mask layer to expose the pad and the bottom metal around the pad;

[0077] Performing a roughening etching process on the exposed bottom metal to increase the roughness of the bottom metal; and

[0078] A metal line is formed on the bonding pad.

[0079] The scheme of the present invention will be described in detail below with reference to the accompanying drawings.

[0080] like Figure 1 S1 and Figure 2 As shown, a substrate 101 is provided. The substrate 101 may be any structure on which a subsequent bottom metal 103 is formed. The substrate 101 may be a single material layer or a stacked structure composed of multiple material layers.

[0081] In one example, the substrate 101 includes a supporting layer 101a, a peeling layer 101b formed on the supporting layer 101a, and a dielectric layer 101c formed on the peeling layer 101b, wherein the supporting layer 101a can be selected to be glass, and the peeling layer 101b can separate the supporting layer 101a and the structure above the peeling layer 101b in a subsequent process. Optionally, the peeling layer 101b can be selected to be a light-to-heat conversion layer (LTHC), which is formed on the supporting layer 101a by a spin coating process and is cured and formed by a curing process. The light-to-heat conversion layer (LTHC) has stable performance and a smooth surface, which is conducive to obtaining a flat surface. In the subsequent peeling process, the peeling difficulty is relatively low. The dielectric layer 101c includes but is not limited to a silicon oxide layer. The subsequent bottom metal 103 is formed on the dielectric layer 101c. Of course, the substrate 101 may also include other structures, such as a structure electrically connected to the bottom metal 103 via the dielectric layer 101c.

[0082] like Figure 1 S2 and Figure 3 As shown, a first mask layer 102 is formed on the substrate 101, and the first mask layer includes a first window 102a for defining the position of the bottom metal 103, wherein the number and arrangement of the first windows 102a are selected according to actual requirements for the bottom metal 103, and optionally, the material of the first mask layer 102 can be photoresist, which can be prepared by photoresist coating, exposure and development processes.

[0083] like Figure 1 S3 and Figure 4 As shown, the bottom metal 103 is formed in the first window 102a. The bottom metal 103 is formed on the substrate 101 defined by the first window 102a. The material of the bottom metal 103 may be Cu, which may be prepared by an electroplating process. In one example, it may be a metal Cu (GND Cu) used as a ground connection. Optionally, the thickness of the bottom metal is between 3μm and 6μm, such as 4μm and 5μm. In one example, the thickness of the grounding metal Cu may be 3μm or 6μm. The thickness of the bottom metal 103 is set according to actual conditions.

[0084] like Figure 1 S4 and Figure 5 As shown, the first mask layer 102 is removed. In one example, the material of the first mask layer 102 can be selected as photoresist, and a degumming solution can be used to remove the first mask layer 102, thereby facilitating the subsequent preparation of a patterned second mask layer 104 to form a pad 105 on the bottom metal 103 based thereon.

[0085] like Figure 1 S5 and Figure 6 As shown, a second mask layer 104 is formed on the substrate 101, the second mask layer 104 surrounds the bottom metal 103 and the second mask layer 104 includes a second window 104a defining a pad 105, and the second window 104a exposes the bottom metal 103. In one example, the second window 104a corresponds to the bottom metal 103 one by one, so as to prepare a pad on the bottom metal 103 defined by the second window 104a, so as to electrically lead out the bottom metal 103. Optionally, the material of the second mask layer 104 can be a photoresist, which can be prepared by a process of photoresist coating, exposure and development. In the present invention, after the bottom metal 103 is formed, the first mask layer 102 is removed, and then the second mask layer 104 is directly formed on the substrate 101, and the second window 104a required for forming the pad 105 is obtained.

[0086] like Figure 1 S6 and Figure 7 As shown, a pad 105 is formed in the second window 104a, wherein the pad 105 is formed on the bottom metal 103 defined by the second window 104a, and can be formed by electroplating. As an example, the pad 105 includes a buffer barrier layer 105a and a metal layer 105b sequentially formed on the surface of the bottom metal 103 in the second window 104a. The buffer barrier layer 105a has the functions of buffering and blocking. In an example, the buffer barrier layer is selected as a Ni layer, and the metal layer is selected as an Au layer. Of course, the materials of the two can also be selected and set according to actual conditions. In a further optional example, the thickness of the buffer barrier layer is between 1.8μm-2.2μm, such as 2μm; the thickness of the metal layer is between 0.1μm-1μm, such as 0.5μm; the thickness of the bottom metal is between 3μm-6μm, such as 3μm, 4μm, 5μm, 6μm. This helps to further improve the difference in roughness between the pad 105 and the surrounding bottom metal 103 , thereby improving the recognition between the two.

[0087] like Figure 1 S7 and Figure 8 As shown, the second mask layer 104 is removed to expose the pad 105 and the bottom metal 103 around the pad 105. As an example, the material of the second mask layer includes photoresist. Optionally, the second mask layer 104 is removed using a photoresist remover.

[0088] like Figure 1 As shown in S8, the exposed bottom metal 103 is subjected to a roughening etching process to increase the roughness of the bottom metal 103, that is, the bottom metal 103 exposed around the pad 105 is etched, and the surface of the bottom metal 103 becomes rough after etching, so that the recognition between the subsequently formed pad and the etched bottom metal around it can be increased. The scanning image of the pad and the bottom metal around it obtained by the roughening etching process is shown in Figure 10, wherein Figure 10 (a) shows the difference in roughness between the two without the roughening etching process, and the recognition is small, and Figure 10 (b) shows the difference in roughness between the two after the roughening etching process, and the recognition is large. As an example, the thickness of the bottom metal etched and removed by the roughening etching process is between 0.1μm-2μm, which is conducive to improving the uniformity of the bottom metal after etching and does not affect the overall thickness of the bottom metal. In one example, the roughening etching process may be performed by a wet etching process, and the temperature of the etching solution is between 21-25° C., and may be 22° C. Figure 1 S9 and Fig. 9As shown, a metal wire 106 is formed on the pad 105. Optionally, the process for forming the metal wire 106 includes a wire bone process, and the material thereof can be selected according to actual conditions. It can be seen from the above description that the process of the present invention can increase the roughness of the subsequent surface of the pad 105, thereby increasing the difference in roughness between the surface of the pad 105 and the surface of the bottom metal 103 around the pad 105, making the two easier to identify and distinguish. For example, in the process of forming the metal wire 106, the wire bone machine needs to automatically identify the pad 105 (Pad) when automatically bonding. If it cannot be identified, manual adjustment is required, which affects the efficiency. The solution of the present invention can provide a difference in roughness between the pad 105 and the bottom metal 103 around it, thereby facilitating identification during the preparation of the metal wire 106, thereby facilitating accurate and effective preparation of the metal wire 106 on the pad 105, thereby improving the yield of metal wire preparation.

[0089] As an example, a seed layer (not shown in the figure) is also formed on the substrate 101, the first window 102a exposes the seed layer, the first mask layer 102 and the bottom metal 103 are both formed on the seed layer, wherein the seed layer is also removed after removing the second mask layer 104. In an optional example, the seed layer includes an adhesion layer and an upper metal layer sequentially formed on the substrate, in an example, the adhesion layer includes a Ti layer, but is not limited thereto, the material of the upper metal layer is the same as that of the bottom metal 103, which is conducive to maintaining the consistency of the materials, such as Cu can be selected. Among them, the seed layer can be removed by an etching process. In one example, the roughening etching process can be performed during the removal of the upper metal layer in the seed layer. In a specific example, the material of the upper metal layer and the material of the bottom metal 103 are Cu, and the material of the adhesion layer is Ti. Cu etching is performed by a wet method. Compared with the process of only removing the seed layer, the etching time is increased to perform the roughening etching treatment at the same time. In one example, the increased etching time can be 6-18s. In addition, optionally, the temperature of the Cu etching solution is: 21-25°C; the temperature of the Ti etching solution is: 26-40°C.

[0090] Embodiment 2:

[0091] like Fig.11 As shown, the present invention also provides another method for improving the identification of the bottom metal and the pad, the method comprising:

[0092] Providing a substrate 101;

[0093] A first mask layer 102 is formed on the substrate 101 , wherein the first mask layer 102 includes a first window 102 a defining a position of a bottom metal 103 ;

[0094] forming the bottom metal 103 in the first window 102a;

[0095] Forming a pad mask layer 200 on the structure formed with the bottom metal 103 and the first mask layer 102, wherein the pad mask layer 200 includes a second window 200a for defining a pad, and the second window 200a exposes the bottom metal 103;

[0096] forming a bonding pad 105 in the second window;

[0097] The pad mask layer 200 and the first mask layer 102 are removed to expose the pad 105 and the bottom metal 103 around it;

[0098] Performing a roughening etching process on the exposed bottom metal 103 to increase the roughness of the bottom metal 103;

[0099] A metal line is formed on the bonding pad 105 .

[0100] As an example, the area of ​​the pad 105 is between 1% and 10% of the area of ​​the bottom metal 103 .

[0101] The difference between this method and the method of the first embodiment is that the method does not remove the first mask layer 102 after forming the bottom metal 103, but forms a pad mask layer 200 on the structure formed with the bottom metal 103 and the first mask layer 102 to obtain the second window 200a for forming the pad 105, wherein the first mask layer 102 and the pad mask layer 200 in this embodiment ultimately constitute a mask layer for forming the pad 105, which can be equivalent to the second mask layer 104 of the first embodiment. Not removing the first mask layer 102 can prevent the surface of the bottom metal 103 from being affected during the removal of the layer. The description of the relevant structure and method can refer to the first embodiment.

[0102] In summary, the method of improving the identification of the bottom metal and the pad of the present invention can increase the roughness of the bottom metal around the pad by roughening and etching the bottom metal, thereby increasing the roughness difference between the pad and the bottom metal around it that has been roughened and etched, making the two easier to identify and distinguish, thereby facilitating accurate and effective preparation of metal wires on the pad and improving the yield of metal wire preparation. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0103] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may 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 a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for improving the identification of bottom metal and pad, characterized in that: The method comprises: Providing a substrate, on which a seed layer is also formed; the seed layer comprises an adhesion layer and an upper metal layer sequentially formed on the substrate; forming a first mask layer on the substrate, wherein the first mask layer comprises a first window defining a bottom metal position; and forming the bottom metal in the first window; removing the first mask layer; forming a second mask layer on the substrate, wherein the second mask layer surrounds the bottom metal and comprises a second window defining a pad, wherein the second window exposes the bottom metal; forming a pad in the second window, wherein the area of ​​the pad is between 1% and 10% of the area of ​​the bottom metal; removing the second mask layer to expose the pad and the bottom metal around the pad; The seed layer is removed, the material of the upper metal layer is consistent with the material of the bottom metal, and a roughening etching process is performed during the removal of the upper metal layer to increase the roughness of the bottom metal; the thickness of the bottom metal etched and removed by the roughening etching process is between 0.1 μm and 2 μm; A metal wire is prepared on the bonding pad.

2. The method for improving the identification of bottom metal and pad according to claim 1, characterized in that: The pad includes a buffer barrier layer and a metal layer sequentially formed on the bottom metal surface in the second window.

3. The method for improving the identification of bottom metal and pad according to claim 2, characterized in that: The buffer barrier layer includes a Ni layer; the metal layer includes an Au layer; and the material of the bottom metal includes Cu.

4. The method for improving the identification of bottom metal and pad according to claim 2, characterized in that: The thickness of the buffer barrier layer is between 1.8 μm and 2.2 μm; the thickness of the metal layer is between 0.1 μm and 1 μm; and the thickness of the bottom metal is between 3 μm and 6 μm.

5. The method for improving the identification of bottom metal and pad according to claim 1, characterized in that: The first window exposes the seed layer, and the first mask layer and the bottom metal are both formed on the seed layer.

6. The method for improving the identification of bottom metal and pad according to claim 1, characterized in that: The substrate includes a supporting layer, a peeling layer formed on the supporting layer, and a dielectric layer formed on the peeling layer, wherein the bottom metal is formed on the dielectric layer based on the first window.

7. The method for improving the identification of bottom metal and pad according to claim 1, characterized in that: The process of forming the metal wire includes a wire bonding process.

8. The method for improving the identification of bottom metal and pad according to any one of claims 1 to 7, characterized in that: The temperature of the etching solution for the roughening etching process is between 21-25°C.

9. A method for improving the identification of bottom metal and pad, characterized in that: The method comprises: Providing a substrate, on which a seed layer is also formed; the seed layer comprises an adhesion layer and an upper metal layer sequentially formed on the substrate; forming a first mask layer on the substrate, wherein the first mask layer comprises a first window defining a bottom metal position; and forming the bottom metal in the first window; forming a pad mask layer on the structure formed with the bottom metal and the first mask layer, wherein the pad mask layer comprises a second window defining a pad, and the second window exposes the bottom metal; forming a pad in the second window, wherein the area of ​​the pad is between 1% and 10% of the area of ​​the bottom metal; The pad mask layer and the first mask layer are removed to expose the pad and the bottom metal around it; the seed layer is removed, the material of the upper metal layer is consistent with the material of the bottom metal, and a roughening etching process is performed during the removal of the upper metal layer to increase the roughness of the bottom metal; the thickness of the bottom metal etched and removed by the roughening etching process is between 0.1 μm and 2 μm; A metal line is formed on the bonding pad.

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