Passive device and method of forming rdl

Abstract

The application provides a passive device and a forming method of RDL. The passive device comprises a substrate, a redistribution layer arranged on a first preset area of the substrate, and a mark metal pattern arranged on a second preset area of the substrate, wherein the thickness of the mark metal pattern is less than the thickness of the redistribution layer, the second preset area is located on the same side of the substrate as the first preset area, and the second preset area is located outside the first preset area. The mark metal pattern is directly formed on the substrate. The mark metal pattern causes a protrusion on a structure layer added subsequently. Even if the mark metal pattern is covered, the mark effect of the mark metal pattern still exists, and the RDL pattern can be formed by taking the protrusion as a reference. The thickness of the mark metal pattern is less than the thickness of the redistribution layer, so that the alignment deviation caused by the thick mark pattern in the alignment process is avoided, and the alignment precision is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device manufacturing technology, and in particular to a passive device and a method for forming an RDL. Background Technology

[0002] In IPD (Integrated Passive Device) devices in the RF front end, the required capacitors and inductors can be formed by metal and dielectric layers, such as a spiral inductor formed on one side of a glass substrate. However, the Q value of such spiral inductors is relatively low, generally between 20 and 30. When a high Q value inductor is required, a three-dimensional inductor can be formed by connecting the metal layers on both surfaces of the glass substrate through a TGV (Through Glass Via), thereby improving the Q value of the inductor.

[0003] There are two approaches to filling TGV vias with Cu metal and forming the Cu metal pattern on the RDL (Redistribution Layer). The first approach involves first filling the TGV vias with Cu metal, and then fabricating the Cu metal patterns on both substrate surfaces. Because the Cu metal inside the TGV via and the Cu metal on the surface are fabricated in two separate steps, poor adhesion such as voids often exists at the interface between the two Cu metals, leading to increased resistance and ultimately affecting device performance. To improve the interface adhesion problem between the Cu metals, a second approach can be adopted: simultaneously growing the Cu metal inside the TGV via and the Cu metal on the surface. That is, the Cu metal inside the TGV via grows continuously, covering both substrate surfaces with a single layer of Cu metal. In this case, because the two Cu metals are grown in a single electroplating process, there is no interface between the two Cu layers, reducing the risk of poor interface adhesion and significantly improving device performance.

[0004] However, a problem arises in the one-step process of forming Cu metal inside and on the surface of the TGV aperture. After the Cu metal electroplating growth inside the TGV aperture is completed, the glass substrate surface is covered with a layer of Cu metal. This leads to a lack of reference marks during the subsequent exposure process when forming the Cu metal pattern of the RDL, resulting in inaccurate alignment and significant deviation between the TGV aperture and the RDL pattern, potentially causing a lack of connectivity between them. Furthermore, the Cu metal thickness on the glass substrate surface is typically above 1µm. Due to the large thickness of the alignment marks formed after etching, and the inability to form a 90° slope angle at the edges, the actual alignment marks exhibit two distinct edges under a microscope. The boundaries of the alignment marks are difficult to identify, easily causing pattern misalignment during the alignment process, resulting in poor alignment accuracy.

[0005] Therefore, a new method for forming RDL is needed to solve the above problems. Summary of the Invention

[0006] The main objective of this invention is to provide a passive device and a method for forming an RDL, so as to achieve more accurate alignment during the RDL forming process.

[0007] The present invention provides a passive device, comprising: a substrate; a redistribution layer disposed in a first preset region of the substrate; and a marking metal pattern disposed in a second preset region of the substrate, wherein the thickness of the marking metal pattern is less than the thickness of the redistribution layer, the second preset region and the first preset region are located on the same side of the substrate, and the second preset region is located outside the first preset region.

[0008] In one embodiment, the substrate includes a plurality of vias arranged in an array, and a redistribution layer is disposed at least on a surface of the substrate perpendicular to the depth direction of the plurality of vias.

[0009] In one embodiment, the etching selectivity ratio of the material of the marking metal pattern to the material of the redistribution layer is greater than a preset threshold; or, the material of the marking metal pattern is the same as the material of the redistribution layer.

[0010] In one embodiment, the material used to mark the metallic pattern is one of the following or an alloy containing at least one of the following materials: copper, platinum, gold, silver, chromium, and nickel.

[0011] In one embodiment, the ratio of the thickness of the marking metal pattern to the thickness of the redistribution layer is less than or equal to 3:10.

[0012] In one embodiment, the thickness of the marked metal pattern does not exceed 300 nm.

[0013] The present invention provides a method for forming an RDL, comprising: providing a substrate, the substrate including a plurality of through holes arranged in an array; forming a marking metal pattern on at least a surface of the substrate perpendicular to the depth direction of the plurality of through holes; forming a redistribution layer on the substrate with reference to the marking metal pattern; wherein the etching selectivity ratio of the material of the marking metal pattern to the material of the redistribution layer is greater than a preset threshold.

[0014] In one embodiment, forming a marker metal pattern on at least a surface of the substrate perpendicular to the depth direction of the plurality of vias includes: forming a marker metal layer on at least a surface of the substrate perpendicular to the depth direction of the plurality of vias; etching the marker metal layer to leave the remaining marker metal layer as the marker metal pattern.

[0015] In one embodiment, etching a marker metal layer and using the remaining marker metal layer as a marker metal pattern includes: forming a first mask layer on the side of the marker metal layer away from the substrate; etching the first mask layer to form a patterned first mask layer; using the patterned first mask layer as a mask, etching the marker metal layer; removing the patterned first mask layer; and using the remaining marker metal layer as a marker metal pattern.

[0016] In one embodiment, a redistribution layer is formed on a substrate with reference to a marking metal pattern, including: forming a redistribution metal layer on a surface of the marking metal layer away from the substrate, a surface of the exposed substrate perpendicular to the depth direction of a plurality of vias, and the inner walls of the plurality of vias; etching the redistribution metal layer with reference to a protrusion caused by the marking metal pattern on the redistribution metal layer, and using the remaining redistribution metal layer as a redistribution layer.

[0017] In one embodiment, forming a redistribution metal layer on the surface of the marking metal layer away from the substrate, the surface of the exposed substrate perpendicular to the depth direction of the plurality of vias, and the inner walls of the plurality of vias includes: forming a first metal seed layer on the surface of the marking metal layer away from the substrate, the surface of the exposed substrate perpendicular to the depth direction of the plurality of vias, and the inner walls of the plurality of vias; and epitaxially growing the redistribution metal layer from the first metal seed layer.

[0018] In one embodiment, the process of etching the redistribution metal layer with reference to the protrusions created by the marking metal pattern on the redistribution metal layer, and using the remaining redistribution metal layer as the redistribution layer, includes: forming a second mask layer on the surface of the redistribution metal layer away from the substrate; etching the second mask layer with reference to the protrusions created by the marking metal pattern on the second mask layer to form a patterned second mask layer; etching the redistribution metal layer with the patterned second mask layer as a mask; removing the patterned second mask layer; and using the remaining redistribution metal layer as the redistribution layer.

[0019] This invention provides a method for forming an RDL (Redistributed Digital Layer), comprising: providing a substrate, the substrate including a plurality of vias arranged in an array; forming a second metal seed layer on a surface of the substrate perpendicular to the depth direction of the plurality of vias and on the inner walls of the plurality of vias; forming a patterned third mask layer on a side of the second metal seed layer away from the surface of the substrate perpendicular to the depth direction of the plurality of vias, wherein the patterned third mask layer is used to define a redistribution layer region, a marking metal pattern region, and other regions on the substrate besides the redistribution layer region and the marking metal pattern region; and forming a redistribution layer and a marking metal pattern on the substrate using the patterned third mask layer as a mask.

[0020] In one embodiment, a patterned third mask layer is formed on one side of the second metal seed layer, away from the substrate and perpendicular to the depth direction of the plurality of vias. This includes: forming the third mask layer on one side of the second metal seed layer, away from the substrate and perpendicular to the depth direction of the plurality of vias; and etching the third mask layer using a photomask as a mask to form the patterned third mask layer. The photomask has a region for defining the redistribution layer region on the substrate, a region for defining other regions on the substrate besides the redistribution layer region and the marking metal pattern region, and a region for defining the marking metal pattern region on the substrate. The regions have a first transmittance, a second transmittance, and a third transmittance, respectively, with the first transmittance > the second transmittance > the third transmittance; the patterned third mask layer is used to define the redistribution layer region, the marking metal pattern region, and other regions on the substrate besides the redistribution layer region and the marking metal pattern region, including: the patterned third mask layer has three progressively increasing thicknesses in the region used to define the redistribution layer region on the substrate, the region used to define other regions on the substrate besides the redistribution layer region and the marking metal pattern region, and the region used to define the marking metal pattern region on the substrate.

[0021] In one embodiment, the first transmittance is 100%, and correspondingly, the thickness of the patterned third mask layer in the region used to define the redistribution layer region on the substrate is 0.

[0022] In one embodiment, forming a redistribution layer and a marker metal pattern on a substrate using a patterned third mask layer includes: epitaxially growing a redistribution layer from a second metal seed layer exposed on the substrate when the thickness of the region of the patterned third mask layer used to define the redistribution layer region on the substrate is 0; thinning the patterned third mask layer to expose only the second metal seed layer in regions other than the redistribution layer region and the marker metal pattern region on the substrate; removing the second metal seed layer in regions other than the redistribution layer region and the marker metal pattern region on the substrate; and removing the remaining patterned third mask layer, using the exposed second metal seed layer as the marker metal pattern.

[0023] In the passive device of this invention, the marking metal pattern is formed directly on the substrate, which causes a protrusion on the subsequent structural layer formed thereon. Even if the marking metal pattern is covered, the marking effect of the marking metal pattern still exists, and the RDL pattern can continue to be formed with the protrusion as a reference. Furthermore, the thickness of the marking metal pattern is small and less than the thickness of the redistribution layer, avoiding alignment deviation caused by the thick Mark pattern during the alignment process, which is beneficial to improving alignment accuracy.

[0024] The method of this invention enables the simultaneous fabrication of Mark patterns required for subsequent processes during the fabrication of RDL patterns, optimizes the overlap between the metal inside the TGV hole and the RDL metal, and solves the problem of inaccurate alignment in subsequent processes; at the same time, it does not require excessive additional processes, saving materials and production capacity; moreover, because the Mark is made of a thin layer of metal, it avoids the alignment deviation caused by the thick Mark pattern during the alignment process, which is conducive to improving alignment accuracy.

[0025] The method of this invention enables the simultaneous fabrication of Mark patterns required for subsequent processes during the fabrication of RDL patterns. This optimizes the overlap between the metal inside the TGV aperture and the RDL metal, solving the problem of inaccurate alignment in subsequent processes. Furthermore, by completing the exposure of the third mask layer in a single exposure step, only one metal layer needs to be prepared, eliminating the need for excessive additional processes and significantly saving materials and production capacity. Moreover, because the Mark is made of a thin metal layer, it is easy to identify, avoids multiple edges, facilitates alignment, and prevents alignment deviations caused by thick Mark patterns during alignment, thus improving alignment accuracy. Attached Figure Description

[0026] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0027] Figure 1A This is a perspective view of the structure of a three-dimensional inductor on a substrate in related technologies;

[0028] Figure 1B This is a cross-sectional schematic diagram of a three-dimensional inductor on a substrate in a related technology;

[0029] Figure 2 This is a cross-sectional schematic diagram of the metal pattern in the TGV hole and the metal pattern of RDL on the substrate formed by one electroplating in the related technology.

[0030] Figures 3A to 3G This is a cross-sectional schematic diagram of the manufacturing process of forming marking patterns and RDLs on a substrate in related technologies;

[0031] Figures 4A to 4F This is a cross-sectional schematic diagram of the manufacturing process of forming marking patterns and RDLs on a substrate in related technologies;

[0032] Figure 5 This is a top view of a marker graphic in a related technology;

[0033] Figure 6 This is a schematic diagram of the cross-sectional thickness of the marking graphic in the related technology;

[0034] Figures 7A to 7K This is a cross-sectional schematic diagram of the manufacturing process of an RDL according to an embodiment of this application;

[0035] Figures 8A to 8G This is a cross-sectional schematic diagram of the manufacturing process of an RDL according to another embodiment of this application. Detailed Implementation

[0036] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] In related technologies, a three-dimensional inductor can be formed by connecting the metal layers on both sides of a glass substrate via TGV, see reference. Figure 1A and Figure 1B It includes a substrate 003, an RDL pattern 001 located on the first surface of the substrate, and an RDL pattern 002 located on the second surface of the substrate opposite to the first surface.

[0038] In related technologies, refer to Figure 2 To complete the state after the metal inside the TGV hole 02 and the metal pattern 01 of the RDL are electroplated in one step, there is a relatively thick metal layer 01 on the surface of the glass substrate 03, which is generally more than 1 μm thick. This metal can be copper (Cu). In this case, there are generally two methods for fabricating the alignment mark and the RDL pattern.

[0039] Option 1, for reference Figures 3A to 3G :

[0040] (1) After forming a metal layer 2” in the TGV hole of the substrate 1 and on the surface of the substrate 1 perpendicular to the depth direction of the TGV hole, a protective tape 3 is applied to the area outside the alignment mark to expose the alignment mark.

[0041] (2) Etch the metal layer 2” of the alignment Mark to obtain metal layer 2', exposing the TGV hole 4 in the alignment Mark area. The TGV hole 4 can be used as the alignment Mark for subsequent alignment reference.

[0042] (3) Remove the protective tape 3;

[0043] (4) Coat the surface of the metal layer 2' with a layer of PR adhesive (Photoresist) 5';

[0044] (5) Expose and develop the PR adhesive 5' to obtain a patterned PR adhesive 5;

[0045] (6) Using the patterned PR adhesive 5 as a mask, etch the metal layer 2' to obtain the metal layer 2, i.e., the RDL pattern;

[0046] (7) Peel off the patterned PR adhesive 5 to obtain the alignment Mark (TGV hole 4) and RDL pattern 2.

[0047] Option 2, for reference Figures 4A to 4F :

[0048] (1) After forming a metal layer 7” in the TGV hole of the substrate 6 and on the surface of the substrate 6 perpendicular to the depth direction of the TGV hole, a layer of PR adhesive 8” is coated on the surface of the metal layer 7”.

[0049] (2) Visually inspect the edge of the aligned wafer and use the mask of the alignment mark pattern to expose and develop the PR adhesive 8” to obtain the patterned PR adhesive 8'.

[0050] (3) Using the patterned PR adhesive 8' as a mask, the metal layer 7” is etched to obtain the metal layer 7', so as to expose the TGV hole 9 of the alignment Mark area. The TGV hole 9 can be used as the alignment Mark for subsequent alignment reference.

[0051] (4) Use the mask of the RDL pattern to expose and develop the patterned PR adhesive 8' to obtain the patterned PR adhesive 8;

[0052] (5) Using the patterned PR adhesive 8 as a mask, the metal layer 7' is etched to obtain the metal layer 7, i.e., the RDL pattern;

[0053] (6) Peel off the patterned PR adhesive 8 to obtain the alignment Mark (TGV hole 9) and RDL pattern 7.

[0054] For Scheme 1, the TGV holes of the alignment Mark on each wafer need to be manually matched during the RDL formation process, which is inefficient, cannot be applied to mass production, and has poor alignment accuracy. For Scheme 2, an additional mask is required to protect the area other than the alignment Mark with PR adhesive before etching, which adds 5 processes: PR adhesive spraying, PR adhesive exposure, PR adhesive development, metal layer etching, and PR adhesive stripping, thus increasing the device cost.

[0055] refer to Figure 5 Both of the above schemes can be formed Figure 5 The corresponding Mark is shown. Figure 5 Figures (a), (b), and (c) show three different shapes of alignment marks. Each alignment mark consists of multiple TGV holes and their surrounding areas. Alignment marks can be of various shapes, such as the cross shape in Figure (a), the T shape in Figure (b), and the right-angle bend shape in Figure (c).

[0056] Additionally, refer to Figure 6Figure (a) shows an example of a right-angled alignment mark. On a substrate, the portion of the substrate beyond the outer edge of the alignment mark needs to be cut away. However, the metal thickness of both the alignment mark and the cut mark patterns formed by the above two methods is relatively thick, generally exceeding 1µm. Furthermore, [refer to reference]. Figure 6 In Figure (b), because the edges of the alignment mark and the cutting mark cannot form a 90° slope angle, when referencing the alignment mark or the cutting mark, the upper and lower edges of the alignment mark or the cutting mark will be seen, making it difficult to identify the edges of the pattern during the alignment process, resulting in poor alignment accuracy, pattern offset, and affecting device performance.

[0057] This embodiment provides a method for forming an RDL, referring to... Figures 7A to 7K This may include the following steps S110 to S130.

[0058] S110: A substrate 110 is provided, the substrate 110 including a plurality of through holes arranged in an array.

[0059] The substrate material can be glass, semiconductor, metal, polymer, ceramic, etc. When the substrate is glass, the through-hole can be called a TGV; when the substrate is a semiconductor such as silicon, the through-hole can be called a TSV (Through Silicon Via). When the substrate is a conductor, a dielectric layer can be formed on the substrate beforehand. Those skilled in the art can choose the substrate material as needed, and this application does not limit it.

[0060] S120: Marking metal pattern 120 is formed on at least one surface of substrate 110 perpendicular to the depth direction of the plurality of through holes.

[0061] The marking metal graphic is called the Mark graphic, and the metal can be copper, platinum, gold, silver, chromium, nickel and alloys, etc. This application does not make specific limitations on it.

[0062] In this embodiment, in addition to forming a marking metal pattern on the surface of the substrate perpendicular to the depth direction of the plurality of through holes, a marking metal pattern can also be formed on the inner wall of the through holes included in the marking metal pattern to improve the recognizability of the marking metal pattern.

[0063] In this embodiment, the surface of the substrate perpendicular to the depth direction of the plurality of through holes may include one surface of the substrate or two opposing surfaces of the substrate. Those skilled in the art can design it as needed, and this application does not impose any specific limitations on this. Correspondingly, the marking metal pattern may be formed on only one surface of the substrate, or the marking metal pattern may be formed on two opposing surfaces of the substrate, and this application does not impose any specific limitations on this.

[0064] In one embodiment, S120: forming a marking metal pattern on at least a surface of the substrate perpendicular to the depth direction of the plurality of through holes may include S121 to S122.

[0065] S121: A marking metal layer 120' is formed at least on a surface of the substrate perpendicular to the depth direction of the plurality of through holes.

[0066] In this embodiment, the methods for forming the marker metal layer include, but are not limited to, PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition), spin coating, electroplating, and electroless plating. For example, the marker metal layer can be formed using magnetron sputtering. During sputtering, the metal adheres to the substrate surface and generally does not obstruct the TGV holes, allowing for alignment during the mark pattern fabrication process using the TGV holes as a reference.

[0067] In one embodiment, the thickness of the marking metal layer is relatively thin, much smaller than the thickness of the redistribution layer subsequently formed. For example, the thickness of the redistribution layer is generally 1 μm or more, while the thickness of the marking metal layer may not exceed 300 nm.

[0068] S122: Etch the marking metal layer 120', and use the remaining marking metal layer 120' as the marking metal pattern.

[0069] In this embodiment, the method for etching the marking metal layer may include wet etching, dry etching, plasma etching, etc., and this application does not specifically limit it.

[0070] In this embodiment, the remaining marking metal layer is used as the marking metal pattern, that is, the marking metal pattern is formed directly on the substrate. The marking metal pattern will cause a protrusion on the structural layer subsequently formed on it. Even if the marking metal pattern is covered, the marking effect of the marking metal pattern still exists, and the RDL pattern can continue to be formed with the protrusion as a reference.

[0071] In one embodiment, S122: Etching the marking metal layer 120' and using the remaining marking metal layer 120' as a marking metal pattern may include S1221 to S1222.

[0072] S1221: A first mask layer 130' is formed on the side of the marking metal layer 120' away from the substrate 110.

[0073] In this embodiment, the method for forming the first mask layer may include PVD, CVD, spin coating, etc., and the material of the first mask layer may include PR adhesive, quartz, etc. This application does not specifically limit the method for forming the first mask layer or the material of the first mask layer, and those skilled in the art can choose according to their needs.

[0074] S1222: Etch the first mask layer 130' to form a patterned first mask layer 130. Using the patterned first mask layer 130 as a mask, etch the marker metal layer 120'. Remove the patterned first mask layer 130 and use the remaining marker metal layer 120' as the marker metal pattern 120.

[0075] In this embodiment, a photomask can be used as a mask to etch a first mask layer to form a patterned first mask layer, which is a first mask layer having the pattern required to form the marking metal pattern. Subsequently, the marking metal pattern is formed using this patterned first mask layer as a mask.

[0076] S130: With reference to the marked metal pattern 120, a redistribution layer 140 is formed on the substrate 110, wherein the etching selectivity ratio of the material of the marked metal pattern 120 to the material of the redistribution layer 140 is greater than a preset threshold.

[0077] In this embodiment, forming a redistribution layer on the substrate may include forming a redistribution layer on one surface of the substrate or forming a redistribution layer on both surfaces of the substrate. Those skilled in the art can configure it as needed, and this application does not make any specific limitations in this regard.

[0078] In this embodiment, the etching selectivity ratio of the material of the marking metal layer to the material of the redistribution layer is greater than a preset threshold, which can prevent accidental etching of the marking metal pattern during the formation of the redistribution layer on top of the marking metal pattern. For example, the material of the marking metal pattern can be chromium, nickel, etc., while the material of the redistribution layer can be copper, titanium, copper-titanium alloy, etc. The preset threshold can be, for example, 1:10, 1:30, etc., and this application does not specifically limit it.

[0079] In this embodiment, the marking metal pattern is formed directly on the substrate. The marking metal pattern will cause a protrusion on the subsequent structural layer added on it. Even if the marking metal pattern is covered, the marking effect of the marking metal pattern still exists, and the RDL pattern can continue to be formed with the protrusion as a reference.

[0080] In one embodiment, S130: with reference to the marked metal pattern 120, a redistribution layer 140 is formed on the substrate 110, which may include S131 to S132.

[0081] S131: A redistribution metal layer 140' is formed on the surface of the marking metal pattern 120 away from the substrate 110, the exposed surface of the substrate 110 perpendicular to the depth direction of the plurality of vias, and the inner wall of the plurality of vias 160.

[0082] In this embodiment, the material of the redistribution metal layer can be copper, platinum, gold, silver, chromium, nickel, and alloys, etc.

[0083] S132: Using the protrusion created by the marking metal pattern 120 on the redistribution metal layer as a reference, etch the redistribution metal layer 140' and use the remaining redistribution metal layer 140' as the redistribution layer 140.

[0084] In one embodiment, S131: forming a redistribution metal layer 140' on the surface of the marking metal pattern 120 away from the substrate 110, the exposed surface of the substrate 110 perpendicular to the depth direction of the plurality of vias, and the inner wall of the plurality of vias 160 may include S1311 to S1312.

[0085] S1311: A first metal seed layer 140 is formed on the surface of the marked metal pattern 120 away from the substrate 110, the exposed surface of the substrate 110 perpendicular to the depth direction of the plurality of through holes, and the inner wall of the plurality of through holes 160.

[0086] In this embodiment, the method for forming the first metal seed layer may include vapor deposition, water plating, sputtering, etc., and this application does not specifically limit the method. The material of the first metal seed layer may be copper, platinum, gold, silver, chromium, nickel, and alloys, etc.

[0087] S1312: A redistribution metal layer 140' is formed by epitaxial growth of the first metal seed layer 140".

[0088] In this embodiment, after forming the first metal seed layer, electroplating or electroless plating can be used to form the redistribution metal layer. The redistribution metal layer can be formed in one step or in stages; this application does not specifically limit this. The thickness of the redistribution metal layer can be selected by those skilled in the art as needed; this application does not specifically limit this.

[0089] In one embodiment, the material of the redistribution metal layer can be the same as the material of the first metal seed layer. For example, the material of the redistribution metal layer and the material of the first metal seed layer can both be silver or both be copper, etc.

[0090] In one embodiment, S132: Taking the protrusion created by the marking metal pattern 120 on the redistribution metal layer as a reference, the redistribution metal layer 140' is etched, and the remaining redistribution metal layer 140' is used as the redistribution layer 140, which may include S1321 to S1322.

[0091] S1321: A second mask layer 150' is formed on the surface of the redistribution metal layer 140' away from the substrate 110.

[0092] S1322: Using the protrusion created by the marking metal pattern 120 on the second mask layer 150' as a reference, etch the second mask layer 150' to form a patterned second mask layer 150. Using the patterned second mask layer 150 as a mask, etch the redistribution metal layer 140', remove the patterned second mask layer 150, and use the remaining redistribution metal layer 140' as the redistribution layer 140.

[0093] The method in this embodiment enables the simultaneous fabrication of Mark graphics required for subsequent processes during the fabrication of RDL graphics. This optimizes the overlap between the metal inside the TGV hole and the RDL metal, solving the problem of inaccurate alignment in subsequent processes. At the same time, it eliminates the need for excessive additional steps, saving materials and production capacity. Furthermore, because the Mark is made of a thin layer of metal, it avoids alignment deviations caused by thick Mark graphics during alignment, which helps improve alignment accuracy.

[0094] This embodiment provides a method for forming an RDL, referring to... Figures 8A to 8G It may include the following steps S210 to S240.

[0095] S210: Provides a substrate 210, which includes a plurality of through holes arranged in an array.

[0096] The substrate material can be glass, semiconductor, metal, polymer, ceramic, etc. When the substrate is glass, the through-hole can be called a TGV; when the substrate is a semiconductor such as silicon, the through-hole can be called a TSV (Through Silicon Via). When the substrate is a conductor, a dielectric layer can be formed on the substrate beforehand. Those skilled in the art can choose the substrate material as needed, and this application does not limit it.

[0097] S220: A second metal seed layer 220 is formed on the surface of the substrate 210 perpendicular to the depth direction of the plurality of through holes and on the inner wall of the plurality of through holes.

[0098] In this embodiment, the methods for forming the second metal seed layer include, but are not limited to, PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition), spin coating, evaporation, water plating, sputtering, etc. For example, magnetron sputtering can be used to form the second metal seed layer. During sputtering, the metal adheres to the substrate surface and generally does not block the TGV holes, allowing for alignment during fabrication using the TGV holes as a reference. The material of the second metal seed layer can be copper, platinum, gold, silver, chromium, nickel, and alloys, etc., and this application does not specifically limit its application.

[0099] In this embodiment, the surface of the substrate perpendicular to the depth direction of the plurality of vias may include one surface of the substrate or two opposing surfaces of the substrate. Those skilled in the art can design it as needed, and this application does not impose any specific limitations on this. Correspondingly, the second metal seed layer may be formed on only one surface of the substrate or on two opposing surfaces of the substrate, and this application does not impose any specific limitations on this.

[0100] In this embodiment, the thickness of the second metal seed layer is relatively thin, much smaller than the thickness of the redistribution layer formed subsequently, so that the thickness of the final formed marker metal layer is much smaller than the thickness of the redistribution layer. For example, the thickness of the redistribution layer is generally more than 1 μm, and the thickness of the second metal seed layer can not exceed 300 nm.

[0101] S230: A patterned third mask layer 230 is formed on one side of the second metal seed layer 220 away from the substrate 210 and perpendicular to the depth direction of the plurality of vias. The patterned third mask layer 230 is used to define the redistribution layer region, the marking metal pattern region, and other regions on the substrate 210 besides the redistribution layer region and the marking metal pattern region.

[0102] In this embodiment, the patterned third mask layer is used to define the redistribution layer region, the marking metal pattern region, and other regions on the substrate besides the redistribution layer region and the marking metal pattern region. The patterned third mask layer may delineate the boundaries of the redistribution layer region, the marking metal pattern region, and other regions on the substrate besides the redistribution layer region and the marking metal pattern region, or the above definition may be achieved in other ways.

[0103] In one embodiment, S230: A patterned third mask layer 230 is formed on one side of the second metal seed layer 220 away from the substrate 210 and perpendicular to the depth direction of the plurality of vias, which may include the following S231 to S240.

[0104] S231: A third mask layer 230' is formed on one side of the second metal seed layer 220 away from the substrate 210 and perpendicular to the depth direction of the plurality of through holes.

[0105] In this embodiment, the method for forming the third mask layer may include PVD, CVD, spin coating, etc., and the material of the third mask layer may include PR adhesive, quartz, etc. This application does not specifically limit the method for forming the third mask layer or the material of the third mask layer, and those skilled in the art can choose according to their needs.

[0106] S232: Using the photomask 300 as a mask, the third mask layer 230' is etched to form a patterned third mask layer 230. The photomask 300 has a first transmittance, a second transmittance, and a third transmittance in the area used to define the redistribution layer area on the substrate, the area used to define other areas on the substrate besides the redistribution layer area and the marking metal pattern area, and the area used to define the marking metal pattern area on the substrate, respectively. The first transmittance > the second transmittance > the third transmittance.

[0107] Thus, the patterned third mask layer 230 is used to define the redistribution layer region, the marking metal pattern region, and other regions on the substrate 210, and may include: the patterned third mask layer 230 having three progressively increasing thicknesses in the region for defining the redistribution layer region on the substrate, the region for defining other regions on the substrate besides the redistribution layer region and the marking metal pattern region, and the region for defining the marking metal pattern region on the substrate.

[0108] In one embodiment, the first transmittance is 100%, and correspondingly, the patterned third mask layer 230 has a thickness of 0 in the region used to define the redistribution layer region on the substrate.

[0109] In one embodiment, the first transmittance can be 100%, the second transmittance can be 50%, and the third transmittance can be 0. Accordingly, the patterned third mask layer has a thickness of 0 in the region used to define the redistribution layer region on the substrate, a thickness of 50% in the region used to define other regions besides the redistribution layer region and the marking metal pattern region, and a thickness of 100% in the region used to define the marking metal pattern region on the substrate.

[0110] S240: Using the patterned third mask layer 230 as a mask, a redistribution layer 221 and a marking metal pattern 223 are formed on the substrate 210.

[0111] In one embodiment, S240: using a patterned third mask layer 230 as a mask, a redistribution layer 221 and a marking metal pattern 223 are formed on a substrate 210, which may include the following S241 to S243.

[0112] S241: When the thickness of the region of the patterned third mask layer 230 used to define the redistribution layer region on the substrate is 0, the redistribution layer 221 is formed by epitaxial growth of the second metal seed layer exposed on the substrate 210.

[0113] In this embodiment, the redistribution metal layer can be formed using electroplating or chemical plating methods based on the second metal seed layer. The redistribution metal layer can be formed in one step or in stages; this application does not impose a specific limitation on this. The thickness of the redistribution metal layer can be selected by those skilled in the art as needed; this application does not impose a specific limitation on this.

[0114] In one embodiment, the material of the redistribution layer can be copper, platinum, gold, silver, chromium, nickel, and alloys. In another embodiment, the metal material epitaxially grown on the second metal seed layer can be the same as the second metal seed layer, that is, the redistribution layer can contain a single metal material.

[0115] S242: Thin the patterned third mask layer to expose only the second metal seed layer 222 in areas other than the redistribution layer area and the marking metal pattern area on the substrate, and remove the second metal seed layer 222 in areas other than the redistribution layer area and the marking metal pattern area on the substrate.

[0116] In one embodiment, when the thickness of the patterned third mask layer is 0% in the area defining the redistribution layer region on the substrate, 50% in the area defining other regions besides the redistribution layer region and the marker metal pattern region, and 100% in the area defining the marker metal pattern region on the substrate, the patterned third mask layer can be thinned to half its remaining thickness. At this point, the area defining other regions besides the redistribution layer region and the marker metal pattern region is completely etched away, leaving only the area defining the marker metal pattern region, exposing the second metal seed layer on the substrate for other regions besides the redistribution layer region and the marker metal pattern region. This portion of the metal seed layer is then etched away. The thinning process may include an ashing process, and the thickness of the remaining patterned third mask layer can be controlled by controlling the ashing process duration. In this embodiment, the method for removing the second metal seed layer may include wet etching, dry etching, plasma etching, etc., and this application does not specifically limit this method.

[0117] S243: Remove the remaining patterned third mask layer 230a and use the exposed second metal seed layer 223 as the marker metal pattern.

[0118] In this embodiment, the exposed second metal seed layer is used as a marker metal pattern, that is, the marker metal pattern is formed directly on the substrate. The marker metal pattern will cause a protrusion on the subsequent structural layer added on it. Even if the marker metal pattern is covered, the marking effect of the marker metal pattern still exists, and the protrusion can continue to be used as a reference to form an RDL pattern.

[0119] The method in this embodiment enables the simultaneous fabrication of Mark patterns required for subsequent processes during the fabrication of RDL patterns. This optimizes the overlap between the metal inside the TGV aperture and the RDL metal, solving the problem of inaccurate alignment in subsequent processes. Furthermore, by completing the exposure of the third mask layer in a single exposure step, only one metal layer needs to be prepared, eliminating the need for excessive additional processes and significantly saving materials and production capacity. Moreover, because the Mark is made of a thin metal layer, it is easy to identify, avoids multiple edges, facilitates alignment, and prevents alignment deviations caused by thick Mark patterns during alignment, thus improving alignment accuracy.

[0120] This embodiment provides a passive device, referenced... Figure 7K and Figure 8G The passive device may include: a substrate ( Figure 7K The middle value is 110. Figure 8G (210 in the middle); redistribution layer, the redistribution layer is disposed in the first preset area of ​​the substrate; marking metal pattern ( Figure 7K The middle is 120. Figure 8G (223) A marking metal pattern is disposed in a second preset area of ​​the substrate, wherein the thickness of the marking metal pattern is less than the thickness of the redistribution layer, the second preset area and the first preset area are located on the same side of the substrate, and the second preset area is located outside the first preset area.

[0121] In one embodiment, the first preset area may include a redistribution layer area, and the second preset area may include a marked metal graphic area.

[0122] In one embodiment, the substrate may include an array of through-holes (...). Figure 7K (160 in the middle), the redistribution layer can be disposed at least on the surface of the substrate perpendicular to the depth direction of the plurality of vias.

[0123] In one embodiment, reference Figure 7K The etching selectivity ratio between the material of the marking metal pattern 120 and the material of the redistribution layer 140 is greater than a preset threshold. In another embodiment, reference... Figure 8GThe material of the marking metal graphic 223 can be the same as the material of the redistribution layer 221.

[0124] In one embodiment, the material used to mark the metallic pattern can be one of the following or an alloy containing at least one of the following materials: copper, platinum, gold, silver, chromium, and nickel.

[0125] In one embodiment, the ratio of the thickness of the marking metal pattern to the thickness of the redistribution layer may be less than or equal to 3:10.

[0126] In one embodiment, the thickness of the marked metal pattern may not exceed 300 nm.

[0127] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. When the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0128] It should be noted that the terms "marked", "second", etc., used in the specification, claims, and drawings of this application are used to distinguish similar objects and are not used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate.

[0129] It should be understood that the exemplary embodiments described herein can be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps. These embodiments are provided so that the disclosure of this application is thorough and complete, and that the concept of these exemplary embodiments is fully conveyed to those skilled in the art, and should not be construed as limiting the invention.

[0130] While the spirit and principles of the invention have been described with reference to several specific embodiments, it should be understood that the invention is not limited to the disclosed specific embodiments, and the division of aspects does not imply that features in these aspects cannot be combined for benefit; such division is merely for ease of description. The invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A method for forming an RDL, characterized in that, include: A substrate is provided, the substrate including a plurality of through holes arranged in an array; A marking metal pattern is formed on at least one surface of the substrate perpendicular to the depth direction of the plurality of through holes; A redistribution layer is formed on the substrate with reference to the marked metal pattern; Referring to the marked metal pattern, a redistribution layer is formed on the substrate, comprising: A redistribution metal layer is formed on the surface of the marked metal pattern away from the substrate, on the exposed surface of the substrate perpendicular to the depth direction of the plurality of through holes, and on the inner wall of the plurality of through holes. Using the protrusions created by the marked metal pattern on the redistribution metal layer as a reference, the redistribution metal layer is etched, and the remaining redistribution metal layer is used as the redistribution layer. Wherein, the etching selectivity ratio of the material of the marked metal pattern to the material of the redistribution layer is greater than a preset threshold.

2. The RDL forming method according to claim 1, characterized in that, A marking metal pattern is formed at least on a surface of the substrate perpendicular to the depth direction of the plurality of through holes, including: A marking metal layer is formed at least on the surface of the substrate perpendicular to the depth direction of the plurality of through holes; The marking metal layer is etched, and the remaining marking metal layer is used as the marking metal pattern.

3. The RDL forming method according to claim 2, characterized in that, Etching the marking metal layer to obtain the remaining marking metal layer as the marking metal pattern includes: A first mask layer is formed on the side of the marked metal layer away from the substrate; The first mask layer is etched to form a patterned first mask layer. Using the patterned first mask layer as a mask, the marking metal layer is etched to remove the patterned first mask layer, and the remaining marking metal layer is used as the marking metal pattern.

4. The RDL forming method according to claim 1, characterized in that, A redistribution metal layer is formed on the surface of the marked metal pattern away from the substrate, on the exposed surface of the substrate perpendicular to the depth direction of the plurality of vias, and on the inner walls of the plurality of vias, comprising: A first metal seed layer is formed on the surface of the marked metal pattern away from the substrate, on the exposed surface of the substrate perpendicular to the depth direction of the plurality of through holes, and on the inner wall of the plurality of through holes. A redistribution metal layer is formed by epitaxial growth from the first metal seed layer.

5. The RDL forming method according to claim 1, characterized in that, Using the protrusion created by the marked metal pattern on the redistribution metal layer as a reference, the redistribution metal layer is etched, and the remaining redistribution metal layer is used as the redistribution layer, including: A second mask layer is formed on the surface of the redistribution metal layer away from the substrate; Using the protrusions created by the marked metal pattern on the second mask layer as a reference, the second mask layer is etched to form a patterned second mask layer. Using the patterned second mask layer as a mask, the redistribution metal layer is etched to remove the patterned second mask layer, and the remaining redistribution metal layer is used as the redistribution layer.

6. A method for forming an RDL, characterized in that, include: A substrate is provided, the substrate including a plurality of through holes arranged in an array; A second metal seed layer is formed on the surface of the substrate perpendicular to the depth direction of the plurality of through holes and on the inner wall of the plurality of through holes; A patterned third mask layer is formed on one side of the second metal seed layer away from the substrate and perpendicular to the depth direction of the plurality of vias, wherein the patterned third mask layer is used to define the redistribution layer region, the marking metal pattern region, and other regions on the substrate besides the redistribution layer region and the marking metal pattern region. Using the patterned third mask layer as a mask, a redistribution layer and a marking metal pattern are formed on the substrate; A patterned third mask layer is formed on one side of the second metal seed layer, away from the substrate and perpendicular to the depth direction of the plurality of vias, comprising: A third mask layer is formed on the side of the second metal seed layer away from the substrate, on the side perpendicular to the depth direction of the plurality of vias; Using a photomask as a mask, a third mask layer is etched to form a patterned third mask layer. The photomask has a first transmittance, a second transmittance, and a third transmittance in the area used to define the redistribution layer area on the substrate, the area used to define other areas on the substrate besides the redistribution layer area and the marking metal pattern area, and the area used to define the marking metal pattern area on the substrate, respectively. The first transmittance > the second transmittance > the third transmittance. The patterned third mask layer is used to define the redistribution layer region, the marker metal pattern region, and other regions on the substrate besides the redistribution layer region and the marker metal pattern region, including: The patterned third mask layer has three progressively increasing thicknesses in the regions used to define the redistribution layer region on the substrate, the regions used to define other regions on the substrate besides the redistribution layer region and the marked metal pattern region, and the regions used to define the marked metal pattern region on the substrate.

7. The RDL forming method according to claim 6, characterized in that, The first transmittance is 100%, and correspondingly, the thickness of the patterned third mask layer in the region used to define the redistribution layer region on the substrate is 0.

8. The method for forming an RDL according to claim 7, characterized in that, Using the patterned third mask layer as a mask, a redistribution layer and a marking metal pattern are formed on the substrate, including: When the thickness of the region of the patterned third mask layer used to define the redistribution layer region on the substrate is 0, the redistribution layer is epitaxially grown from the second metal seed layer exposed on the substrate to form the redistribution layer. The patterned third mask layer is thinned to expose only the second metal seed layer in areas other than the redistribution layer area and the marked metal pattern area on the substrate, and the second metal seed layer in areas other than the redistribution layer area and the marked metal pattern area on the substrate is removed. Remove the remaining patterned third mask layer and use the exposed second metal seed layer as the marker metal pattern.

9. A structure of a passive device prepared by the molding method of the RDL according to any one of claims 1 to 8, characterized in that, include: A substrate, the substrate including a plurality of through holes arranged in an array; A redistribution layer is disposed in a first predetermined area of ​​the substrate; A marking metal pattern is disposed in a second preset area of ​​the substrate, wherein the thickness of the marking metal pattern is less than the thickness of the redistribution layer, the second preset area and the first preset area are located on the same side of the substrate, and the second preset area is located outside the first preset area; the marking metal pattern is disposed at least on a surface of the substrate perpendicular to the depth direction of the plurality of vias; the redistribution layer is disposed at least on a surface of the substrate perpendicular to the depth direction of the plurality of vias.

10. The structure of the passive device according to claim 9, characterized in that, The etching selectivity ratio of the material of the marked metal pattern to the material of the redistribution layer is greater than a preset threshold; or The material of the marked metal pattern is the same as the material of the redistribution layer.

11. The structure of the passive device according to claim 9, characterized in that, The material of the marked metal pattern is one of the following or an alloy containing at least one of the following materials: copper, platinum, gold, silver, chromium, and nickel.

12. The structure of the passive device according to claim 9, characterized in that, The ratio of the thickness of the marked metal pattern to the thickness of the redistribution layer is less than or equal to 3:

10.

13. The structure of the passive device according to claim 9, characterized in that, The thickness of the marked metal pattern does not exceed 300 nm.

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