Packaging structure and its formation method

Abstract

This disclosure provides a packaging structure and a method for forming the same. The packaging structure includes a substrate, a first passivation layer, a metal layer, a second passivation layer, and a polymer layer. The first passivation layer is formed on the substrate. The metal layer is conformally formed on the first passivation layer. The second passivation layer is conformally formed on the first passivation layer and the metal layer. A stepped structure is formed on the top surface of the second passivation layer and includes at least one lower portion below the other portions of the stepped structure. The polymer layer is formed on the second passivation layer. A portion of the polymer layer extends into the lower portion of the stepped structure to engage with the stepped structure.

Description

Technical Field

[0001] This invention relates to a semiconductor manufacturing technology, and more particularly to a packaging structure with a polymer layer delamination design and a method for forming the same. Background Technology

[0002] The semiconductor industry continuously increases the integration density of various electronic components (such as transistors, diodes, resistors, capacitors, etc.) by constantly reducing the minimum feature size, thereby allowing more components to be integrated into a given area. With the ever-growing demand for smaller electronic devices, there is an increasing need for smaller and more innovative semiconductor die packaging technologies.

[0003] Traditional packaging technology divides a chip into multiple individual dies and packages each individual die in the following order: placing the individual die on a packaging substrate, forming first-level interconnects typically through wire bonding or flip-chip bonding, sealing, testing, inspection, and second-level interconnection with the circuit board in the final assembly. These technologies and processes are very time-consuming.

[0004] Wafer-level packaging (WLP) is a technology that packages bare dies at the wafer level. WLP technology can produce small dies with good electrical performance and is currently widely used due to its low cost and relatively simple process. WLP technology basically includes device interconnect and device protection processes. In WLP technology, the back-end-of-line (BEOL) process involves several mask layers, starting from the polymer dielectric layer, redistribution layer, under-bump metallization layer, and wafer bumps, all of which are performed before dicing.

[0005] While existing wafer-level packaging technologies are generally sufficient to meet their intended purpose, they are not entirely satisfactory in all aspects. Summary of the Invention

[0006] This disclosure provides a packaging structure including a substrate, a first passivation layer, a metal layer, a second passivation layer, and a polymer layer. The first passivation layer is formed on the substrate. The metal layer is conformally formed on the first passivation layer. The second passivation layer is conformally formed on both the first passivation layer and the metal layer. A stepped structure is formed on the top surface of the second passivation layer and includes at least one lower portion, said at least one lower portion being lower than other portions of the stepped structure. The polymer layer is formed on the second passivation layer. A portion of the polymer layer extends into said at least one lower portion of the stepped structure to engage with the stepped structure.

[0007] This disclosure provides a packaging structure including a substrate, a first passivation layer, a metal layer, a second passivation layer, and a polymer layer. The first passivation layer is formed on the substrate. The metal layer is formed on the first passivation layer, and at least a portion of the metal layer extends into the first passivation layer. The second passivation layer is conformally formed on the first passivation layer and the metal layer. A stepped structure is formed on the top surface of the second passivation layer and includes at least one lower portion, said at least one lower portion being lower than other portions of the stepped structure. The at least one lower portion of the stepped structure corresponds to said at least one portion of the metal layer in the first passivation layer. The polymer layer is formed on the second passivation layer. A peripheral portion of the polymer layer extends into said at least one lower portion of the stepped structure.

[0008] This disclosure provides a method for forming a package structure. The method includes forming a first passivation layer on a substrate. The method also includes conformally forming a metal layer on the first passivation layer. The method further includes conformally forming a second passivation layer on the first passivation layer and the metal layer, such that a stepped structure is formed on the top surface of the second passivation layer, wherein the stepped structure has at least one lower portion that is lower than other portions of the stepped structure. Furthermore, the method includes forming a polymer layer on the second passivation layer, wherein a peripheral portion of the polymer layer extends into the at least one lower portion of the stepped structure to engage with the stepped structure. Attached Figure Description

[0009] The complete disclosure is based on the following detailed description and accompanying drawings. It should be emphasized that, in accordance with the general practice of the industry, the illustrations are not necessarily drawn to scale. In fact, the dimensions of components may be arbitrarily enlarged or reduced for clarity.

[0010] Figures 1A to 1B This is a top view of a wafer-level package (WLP) comprising multiple bare dies covered by molding compound, according to some embodiments.

[0011] Figure 2 This is a cross-sectional view of a portion of a wafer-level package structure according to some embodiments.

[0012] Figure 3 This is a cross-sectional view of a portion of a wafer-level package structure according to some embodiments.

[0013] Figure 4 This is a simplified flowchart of a method for forming a wafer-level package structure according to some embodiments.

[0014] The attached figures are labeled as follows:

[0015] 10: Chip-level packaging

[0016] 11: Nude Film

[0017] 11A: Active region

[0018] 11B: Surrounding Area

[0019] 12: Chip

[0020] 13: Molding compound

[0021] 14: Line drawing

[0022] 15: Sealing ring structure

[0023] 151: Inner sealing ring

[0024] 152: Outer sealing ring

[0025] 20:Substrate

[0026] 21: Apparatus

[0027] 22: Interconnection Structure

[0028] 22A, 22B: Surface

[0029] 221: Insulation layer

[0030] 222: Conductive layer

[0031] 222A, 222B: Contacts

[0032] 223, 224: Conductive layer

[0033] 23: Passivation layer

[0034] 231,232,233: Opening

[0035] 24: Metal layer

[0036] 241: Metal pad / joint pad

[0037] 241A, 241B: Partial

[0038] 242: Metal gasket / sealing ring gasket

[0039] 242A, 242B: Partial

[0040] 243: Metal gasket / sealing ring gasket

[0041] 243A, 243B: Partial

[0042] 25: Passivation layer

[0043] 25A: Top surface

[0044] 251: Opening

[0045] 26: Polymer layer

[0046] 27: Post-passivation interconnect layer

[0047] 28: Polymer layer

[0048] 280: Surrounding Area

[0049] 29: Under-bump metallization layer

[0050] 291: Under-bump metallized components

[0051] 30: Electrical connectors

[0052] 400: Method

[0053] 401, 402, 403, 404, 405: Operations

[0054] D1: Horizontal direction

[0055] D2: Vertical direction

[0056] W1, W2: Width

[0057] SS: Stepped structure

[0058] SS1: Higher section

[0059] SS2: Lower section (groove) Detailed Implementation

[0060] The following disclosure provides many different embodiments or examples to implement different features of this application. Specific examples of components and their arrangements are described below to illustrate this disclosure. Of course, these embodiments are merely examples and should not be construed as limiting the scope of this disclosure. For example, the specification may describe a first feature formed on or above a second feature, which may include embodiments where the first and second features are in direct contact, or embodiments where an additional feature is formed between the first and second features, such that the first and second features may not be in direct contact. Furthermore, repeated reference numerals and / or designations may be used in different examples of this disclosure; this repetition is for simplification and clarity and is not intended to limit any specific relationship between the various embodiments and / or structures discussed.

[0061] Furthermore, spatial terms such as "below," "below," "lower," "above," "higher," and similar terms are used to facilitate the description of the relationship between one element or feature and another element(s) in the accompanying drawings. In addition to the orientations shown in the drawings, these spatial terms are intended to encompass different orientations of the device in use or operation. The device may be rotated to different orientations (90 degrees or other orientations), and the spatial terms used herein can be interpreted in the same way.

[0062] The use of the term "substantially" in the specification, such as "substantially flat" or "substantially coplanar," is as understood by those skilled in the art. In some embodiments, the adjective "substantially" may be omitted. Where applicable, the term "substantially" may also include embodiments of "entirely," "completely," "all," etc. Where applicable, the term "substantially" may also refer to 90% or higher, such as 95% or higher, particularly 99% or higher, including 100%. Furthermore, terms such as "substantially parallel" or "substantially perpendicular" should be interpreted as not excluding minor deviations from a particular arrangement, and may include, for example, deviations of up to 10°. The term "substantially" does not exclude "completely," for example, a composition "substantially free" of Y may be completely free of Y.

[0063] Terms used in conjunction with a specific distance or size, such as “about,” should be interpreted as not excluding minor deviations relative to the specific distance or size, and may include, for example, deviations of up to 10%. The term “about” used with the numerical value x may mean x ± 5 or 10%.

[0064] A semiconductor device package (structure) and a method of forming the same are provided according to various exemplary embodiments of the present disclosure. Variations of some embodiments are also discussed. In the various views and illustrative embodiments, the same reference numerals are used to denote the same elements. According to some embodiments, a package structure has a polymer layer delamination prevention design to increase the adhesion between the polymer layer and the underlying structure. Therefore, the reliability of the package structure is improved.

[0065] The embodiments described below are for the specific context of wafer-level packaging (WLP) technology. Other embodiments may be contemplated for other applications, such as different package types or different configurations, as will be apparent to those skilled in the art upon reading this disclosure. It should be noted that the embodiments discussed herein do not necessarily illustrate every component or feature that may be present in the structure. Furthermore, the method embodiments discussed herein may be discussed as being performed in a particular order; however, other method embodiments may be performed in any logical order.

[0066] Figure 1AA top view of a wafer-level package (WLP) 10 according to some embodiments is shown, comprising a plurality of dies 11 fabricated on a wafer 12 and covered by a molding compound 13. Further details of the dies 11 are shown below. Figure 1B middle.

[0067] The wafer-level package 10 can be a wafer-level chip scale package (WLCSP), a fan-out wafer-level package (FO-WLP), an embedded wafer-level package (WLP), a three-dimensional wafer-level package (3D WLP), or a wafer-level microelectromechanical system (MEMS). The wafer-level package 10 can also be any other wafer-level package developed using various other technologies and used in various applications.

[0068] Each die 11 can be a chip made using various technologies, such as a complementary metal-oxide-semiconductor (CMOS) chip, a GaAs chip, a SiGe chip, or an integrated passive device (IPD). Die 11 can be used to perform any function, such as a processor, a memory chip, a power amplifier, an optoelectronic device such as an image sensor, an analog-to-digital (A / D) converter, etc.

[0069] The wafer-level package 10 includes a plurality of identical dies 11 formed on a wafer 12, separated by scribe lines 14. The wafer 12 serves as a manufacturing carrier during the production of the dies 11. After the semiconductor manufacturing process is completed, a plurality of dies 11 are formed. The manufacturing process of the dies 11 is well known in the art and will not be described here. These dies 11 are then separated by a die dicing or singulation process, in which a mechanical or laser saw is used to cut through the wafer 12 between the individual dies 11. To facilitate the die dicing process, relatively narrow scribe lines 14 are provided on the wafer 12, along which cuts are made to separate the dies 11. Each scribe line 14 may be a region located between two dies 11. The scribe lines 14 surround the edges of the dies 11.

[0070] Molding compound 13 covers the top of the die 11 and the scribe line 14. In some instances, molding compound 13 is an insulating material, such as an epoxy resin in which filler is dispersed. Molding compound 13 may be configured to provide lateral support for structures formed on the die 11, such as electrical connections (e.g., Figure 2(Electrical connector 30 shown). Molding material 13 can be molded or molded using a mold. A release material can be applied to the mold to prevent molding material 13 from sticking to the mold. In some cases, molding material 13 can be omitted.

[0071] like Figure 1B As shown, multiple bond pads 241 are located within the active region 11A of the die 11. The active region 11A can consist of numerous electronic components on a substrate, such as active and passive devices. The active region 11A contains most of the high-density active circuitry of the die 11. These components may initially be isolated from each other, formed on the underlying substrate, and then interconnected by metal interconnects to form functional circuitry. Typical interconnect structures include lateral interconnects (e.g., metal lines or wiring) and vertical interconnects (e.g., vias and contacts).

[0072] Bonding pads 241 can be used to provide voltage signals to the circuitry within active region 11A. These voltage signals are supplied to bonding pads 241 via a package containing an integrated circuit device. Generally, after device fabrication, bonding pads 241 are located beneath the dielectric layer and exposed for testing and bonding to a suitable package. Electrical signals from active region 11A are routed through a network of metal layers to one or more bonding pads 241, which are further connected to solder bumps or other electrical connections depending on the function of the semiconductor device. (See below for further details.) Figure 2 A detailed example of the above packaging structure is provided.

[0073] Each die 11 may include a sealing ring structure 15 located in a peripheral region 11B (sometimes also referred to as the sealing ring region) adjacent to and surrounding the corresponding active region 11A. In some embodiments, the sealing ring structure 15 is formed of a conductive material, such as aluminum (Al), aluminum-copper (Al-Cu) alloy, aluminum-copper-silicon (Al-Cu-Si) alloy, etc. The sealing ring structure 15 can prevent unwanted moisture and mobile ion contaminants from reaching the circuitry within the active region 11A, thereby improving the reliability of the package structure. It should be understood that, although Figure 1B Only one sealing ring of the sealing ring structure 15 is shown in the figure, but in some embodiments, each bare piece 11 may also include more sealing rings, including an outer sealing ring surrounding an inner sealing ring.

[0074] like Figure 1BAs shown, the sealing ring structure 15 in the top view has a rectangular or square shape and extends in a continuous closed loop. However, the configuration of the sealing ring structure 15 is not limited to this. In some other embodiments, the sealing ring structure 15 has at least one slit portion (not shown) for cutting the sealing ring structure 15 (i.e., in the top view, it consists of multiple discontinuous portions) to prevent current from being induced in the sealing ring structure 15. In different embodiments, the sealing ring structure 15 may also extend in a curved or circular shape. More details of the sealing ring structure 15 (e.g., construction and formation steps) will be described below.

[0075] Figure 2 This is a cross-sectional view of a portion of a wafer-level package (WLP) structure (i.e., a die 11) according to some embodiments. As described above, the wafer-level package structure has an active region 11A and a peripheral region 11B surrounding the active region 11A. Figure 2 In this wafer-level packaging structure, a substrate 20 is included. The substrate 20 is a semiconductor substrate, which may be a bulk semiconductor substrate, a silicon-on-insulator (SOI) substrate, a germanium-on-insulator (GOI) substrate, etc. The semiconductor material of the substrate 20 may include silicon, germanium, compound semiconductors (including silicon-germanium, silicon carbide, gallium arsenide, gallium phosphide, indium phosphide, indium arsenide, and / or indium antimonide), alloy semiconductors (including SiGe, GaAsP, AlInAs, AlGaAs, GaInAs, GaInP, and / or GaInAsP), or combinations thereof. The substrate 20 may be doped or undoped. Other substrates, such as multilayer or gradient substrates, may also be used.

[0076] According to some embodiments, a device 21, such as an active or passive device (for simplicity, only one device 21 is depicted), is formed within the active region 11A of the substrate 20. As those skilled in the art will appreciate, various active and passive devices, such as transistors, diodes, capacitors, resistors, inductors, etc., can be used to generate the desired structural and functional design of the die 11. The device 21 can be formed in or on the surface of the substrate 20 using any suitable process. In some alternative embodiments, the substrate 20 may be an interposer substrate or a package substrate, which substantially does not contain integrated circuit devices.

[0077] According to some embodiments, an interconnect structure 22 is formed on the substrate 20 and electrically coupled to the device 21, such as... Figure 2 As shown. The interconnect structure 22 has opposing surfaces 22A and 22B, with surface 22A facing and directly contacting the substrate 20. The interconnect structure 22 includes a plurality of laminated insulating layers 221 and a plurality of conductive layers 222 surrounded by the insulating layers 221.

[0078] The conductive layer 222 may include conductive lines providing electrical connections in the horizontal direction and conductive vias providing electrical connections in the vertical direction. Furthermore, the conductive layer 222 includes contacts 222A exposed from surface 22A and in direct contact with the device 21, and contacts 222B exposed from surface 22B for connection to subsequently formed bonding pads (for simplicity, only one contact 222B is depicted). The device 21 is interconnected via one or more conductive layers 222 to form the functional circuitry required for the die 11.

[0079] The material of the insulating layer 221 may include silicon dioxide, undoped silicate glass (USG), phosphosilicate glass (PSG), etc., but other suitable insulating materials may also be used. According to some embodiments, the material used to form the insulating layer 221 is photosensitive, thus allowing the formation of openings with the desired pattern in the insulating layer 221 using photolithography. The material of the conductive layer 222 may include copper (Cu), aluminum (Al), tungsten (W), cobalt (Co), other metals or metal alloys, but other suitable conductive materials may also be used.

[0080] The formation of interconnect structure 22 may involve multiple deposition or coating processes, multiple patterning processes and / or multiple planarization processes.

[0081] Deposition or coating processes can be used to form the insulating layer and / or conductive layer. Deposition or coating processes may include spin coating, electroplating, electroless plating, mosaic plating, dual mosaic plating, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), one or more other suitable processes, or combinations thereof.

[0082] Patterning processes can be used to pattern insulating layers and / or conductive layers. Patterning processes may include photolithography, energy beam drilling (e.g., laser beam drilling, ion beam drilling, or electron beam drilling), etching, mechanical drilling, one or more other suitable processes, or combinations thereof.

[0083] Planarization processes can be used to provide a flat top surface for the formed insulating layer and / or conductive layer to facilitate subsequent processes. Planarization processes may include mechanical polishing, chemical mechanical polishing (CMP), one or more other suitable processes, or combinations thereof.

[0084] According to some embodiments, a passivation layer 23 is further formed on the substrate 20. In some embodiments, such as Figure 2 As shown, a passivation layer 23 is formed on the surface 22B of the interconnect structure 22 and is patterned to form an opening 231 (for simplicity, only one opening 231 is depicted) to partially expose the underlying contact 222B. The passivation layer 23 may include or be made of silicon nitride (SiN), silicon dioxide (SiO2), silicon oxynitride (SiON), polyimide (PI), benzocyclobutene (BCB), polybenzoxazole (PBO), or other suitable insulating materials, and may be formed using a deposition process, such as chemical vapor deposition. The opening 231 in the passivation layer 23 may be formed by removing a portion of the passivation layer 23 using a photoresist etching process defined by a mask.

[0085] According to some embodiments, a metal layer 24 is conformally formed on the passivation layer 23. In some embodiments, such as Figure 2 As shown, the metal layer 24 includes a plurality of metal pads 241 (for simplicity, only one metal pad 241 is depicted). Each metal pad 241 includes a plurality (e.g., two) portions 241A located above the passivation layer 23 and a portion 241B located between the portions 241A and extending into an opening 231 of the passivation layer 23. The metal pads 241 are in direct contact with the contacts 222B through the openings 231 and are interconnected to the device 21 through the conductive layer 222 of the interconnection structure 22. The metal pads 241 can be used to provide voltage signals to the device 21 and are therefore sometimes referred to as bonding pads 241.

[0086] The metal layer 24 (and the metal pad 241) may include or be made of aluminum (Al), copper (Cu), tin (Sn), nickel (Ni), gold (Au), silver (Ag), or other suitable metallic materials. The metal pad 241 may be formed by depositing a metal layer (i.e., metal layer 24) on the passivation layer 23 and in its openings 231 using a deposition process such as electroplating, and then removing a portion of the metal layer above the passivation layer 23 using a suitable process (e.g., photolithography and etching). However, any other suitable process may be used to form the metal pad 241.

[0087] According to some embodiments, such as Figure 2As shown, a passivation layer 25 is conformally formed on the passivation layer 23 and the metal layer 24. In some embodiments, the passivation layer 25 is further patterned to form an opening 251 (for simplicity, only one opening 251 is depicted) to partially expose the underlying metal pad 241, which will be further connected to the subsequently formed electrical connector. The material and formation method of the passivation layer 25 may be the same as or similar to the material and formation method of the passivation layer 23, and therefore will not be described in detail here. Figure 2 As shown, the top surface 25A of the formed passivation layer 25 is substantially parallel to the surface 22B of the underlying interconnect structure 22.

[0088] According to some embodiments, the wafer-level package further includes a (dual) sealing ring structure 15, which includes an inner sealing ring 151 formed within a peripheral region 11B of the die 11 and an outer sealing ring 152 surrounding the inner sealing ring 151, such as Figure 2 As shown. The outer sealing ring 152 can be used to protect the inner sealing ring 151, but in some cases the outer sealing ring 152 can be omitted. The configuration of the inner sealing ring 151 and the outer sealing ring 152 (in the top view) can be compared with... Figure 1B The sealing ring structure 15 shown has the same or similar configuration.

[0089] According to some embodiments, in order to protect the device 21 and circuitry (including conductive layer 222 and metal pad 241) within the active region 11A of the die 11, a sealing ring structure 15 is arranged to surround the active region 11A and extend from the top surface of the substrate 20 on which the device 21 is fixed to the same horizontal height as the metal pad 241.

[0090] For example, in Figure 2 In the sealing ring structure 15, the inner sealing ring 151 includes multiple stacked conductive layers 223 within the interconnect structure 22 and a metal pad 242 (also referred to as sealing ring pad 242) on the passivation layer 23. The structure of the conductive layer 223 may be the same as or similar to the structure of the aforementioned conductive layer 222, but the conductive layer 223 (and the entire inner sealing ring 151) is insulated from the device 21.

[0091] The metal pad 242, separate from the metal pad 241, includes a plurality (e.g., two) portions 242A located on the passivation layer 23 and a portion 242B located between the portions 242A and extending into an opening 232 of the passivation layer 23. The portion 242B of the metal pad 242 is in direct contact with the top of the conductive layer 223 (e.g., a contact point) through the opening 232. According to some embodiments, the opening 232 is formed in the passivation layer 23 before the metal pad 242 is formed on the passivation layer 23. The method of forming the opening 232 can be the same as or similar to the method of forming the opening 231. In some embodiments, the opening 232 and the opening 231 are formed in the same step. The material and formation method of the metal pad 242 (e.g., by patterning the metal layer 24) can be the same as or similar to the material and formation method of the metal pad 241. In some embodiments, the metal pad 242 and the metal pad 241 are formed in the same step.

[0092] Similarly, the outer sealing ring 152 of the sealing ring structure 15 consists of multiple stacked conductive layers 224 within the interconnect structure 22 and a metal pad 243 (also referred to as the sealing ring pad 243) on the passivation layer 23, as shown. Figure 2 As shown. The structure of conductive layer 224 may be the same as or similar to that of conductive layer 222, but conductive layer 224 (and the entire outer sealing ring 152) is insulated from device 21.

[0093] Separated from metal pads 241 and 242, metal pad 243 comprises a plurality (e.g., two) portions 243A situated on passivation layer 23 and a portion 243B situated between the portions 243A and extending into an opening 233 of passivation layer 23. The portion 243B of metal pad 243 is in direct contact with the top of conductive layer 224 (e.g., a contact point) through opening 233. According to some embodiments, opening 233 is formed in passivation layer 23 before metal pad 243 is formed on passivation layer 23. The method of forming opening 233 may be the same as or similar to the method of forming opening 231. In some embodiments, openings 233, 232, and 231 are formed in the same step. The material and formation method of metal pad 243 (e.g., by patterning metal layer 24) may be the same as or similar to the material and formation method of metal pad 241. In some embodiments, metal pads 243, 242, and 241 are formed in the same step.

[0094] According to some embodiments, such as Figure 2As shown, the width W1 (equal to the width of the opening 232 of the passivation layer 23) of portion 242B of the metal pad 242 in a horizontal direction D1 substantially parallel to the top surface 25A of the passivation layer 25 is greater than the width W2 (equal to the width of the opening 233 of the passivation layer 23) of portion 243B of the metal pad 243 in the horizontal direction D1. In some embodiments, the width W1 may be approximately twice the width W2, for example, the width W2 is approximately 2 micrometers and the width W1 is approximately 4 micrometers. However, other suitable values ​​may also be used.

[0095] Therefore, a stepped structure SS is formed on the top surface 25A of the passivation layer 25, and the stepped structure SS corresponds to the metal pad 242 below having a stepped structure (composed of a portion 242A on the passivation layer 23 and a portion 242B recessed into the passivation layer 23). According to some embodiments, such as Figure 2 As shown, the stepped structure SS includes a plurality of (e.g., two) higher portions SS1 above and corresponding to portion 242A of the metal pad 242, and a lower portion SS2 above and corresponding to portion 242B of the metal pad 242 (lower than the higher portions SS1 in a vertical direction D2 perpendicular to the horizontal direction D1). The lower portion SS2 has a groove structure.

[0096] As described above, since the metal pad 242 (especially portion 242B) has a relatively large width, a correspondingly wider stepped structure SS is implemented on the metal pad 242 (because the lower portion SS2 has a larger width). The stepped structure SS facilitates the stable landing of subsequent polymer layers on the passivation layer 25, which will be further described below.

[0097] According to some embodiments, the wafer-level packaging structure also includes a polymer layer 26 on the passivation layer 25 that partially exposes the metal pad 241 (i.e., the bonding pad 241), such as Figure 2 As shown. In some embodiments, polymer layer 26 is formed over active region 11A and terminates before peripheral region 11B. Polymer layer 26 may include or be made of polymeric materials such as epoxy resin, polyimide, benzocyclobutene (BCB), polybenzoxazole (PBO), etc., although other relatively soft, typically organic dielectric materials may also be used. Formation methods include spin coating or other suitable methods. Openings in polymer layer 26 for exposing metal pad 241 can be formed by removing a portion of polymer layer 26 using a photoresist etching process defined by a mask.

[0098] According to some embodiments, the wafer-level package structure also includes a post-passivation interconnect (PPI) layer 27 over the polymer layer 26 and in contact with the metal pad 241. The PPI layer 27 may also be referred to as a redistribution layer. The PPI layer 27 may include or be made of aluminum (Al), copper (Cu), copper alloys, or other suitable metallic materials, and may be formed by electroplating, electroless plating, damascene plating, dual damascene plating, sputtering, physical vapor deposition, and combinations thereof. It should be understood that the wafer-level package structure may also include several PPI layers 27 to form an interlayer interconnect network, which may be electrically connected to the metal pad 241 according to the function of the die 11.

[0099] According to some embodiments, the wafer-level package structure further includes a polymer layer 28 on the polymer layer 26, the post-passivation interconnect layer 27, and the passivation layer 25. In some embodiments, the polymer layer 28 is formed over the active region 11A and extends into the peripheral region 11B to cover the stepped structure SS over the metal pad 242 of the inner sealing ring 151. In some embodiments, the polymer layer 28 terminates before the portion of the passivation layer 25 over the metal pad 243 of the outer sealing ring 152. The material and formation method of the polymer layer 28 may be the same as or similar to the material and formation method of the polymer layer 26, and therefore will not be described again here.

[0100] As described above, the stepped structure SS (particularly the lower portion SS2) has a larger width, so a portion of the polymer layer 28 below its periphery (i.e., the peripheral portion 280) can extend into the lower portion SS2 of the stepped structure SS to engage with it (it should be understood that although the peripheral portion 280 is shown as filling only a part of the lower portion SS2, it can also fill the entire lower portion SS2). As a result, the adhesion between the polymer layer 28 and the passivation layer 25 is improved, thereby reducing the risk of delamination of the polymer layer 28. Therefore, the reliability of the entire encapsulation structure is enhanced.

[0101] According to some embodiments, such as Figure 2As shown, the polymer layer 28 also has openings to expose a portion of the underlying passivation interconnect layer 27. The wafer-level package structure also includes an under-bump metallization (UBM) layer 29 formed on the polymer layer 28 and contacting the passivation interconnect layer 27 through the openings in the polymer layer 28. The UBM layer 29 can be patterned (e.g., using a photoresist etching process defined by a mask) to form multiple individual UBM elements 291. Multiple electrical connections 30 (e.g., solder balls) are formed on the UBM elements 291 and electrically connected to them. The electrical connections 30 are interconnected to a metal pad 241 through the UBM elements 291 and the passivation interconnect layer 27. The electrical connections 30 allow the fabricated package structure to be further connected to an external electronic component, such as a printed circuit board (PCB).

[0102] Figure 3 This is a cross-sectional view of a portion of a wafer-level package (WLP) structure (i.e., a die 11) according to some embodiments. It should be understood that... Figure 3 Most of the structures in Figure 2 Since the parts are the same as those in the original text, only the differences will be described here. Figure 3 In the inner sealing ring 151, the metal pad 242 includes a plurality of (e.g., three) portions 242A located above the passivation layer 23 and a plurality of (e.g., two) portions 242B located between the portions 242A and extending into the passivation layer 232. In some embodiments, each portion 242B is located between two portions 242A, and the middle portion 242A is located between two portions 242B.

[0103] Before forming the metal pad 242, an opening 232 is formed in the passivation layer 23. In some embodiments, one opening 231 is located directly above the top contact of the conductive layer 223, and another opening 231 is offset relative to the top contact. Furthermore, a portion 242B of the metal pad 242 is located directly above the top contact of the conductive layer 223, and another portion 242B is offset relative to the top contact.

[0104] like Figure 3As shown, the width W1 of the portion 242B of the metal pad 242 in the horizontal direction D1 (equal to the width of the opening 232 of the passivation layer 23) is the same, and the width W1 may be equal to or greater than the width W2 of the portion 243B of the metal pad 243 in the horizontal direction D1 (equal to the width of the opening 233 of the passivation layer 23). In some other embodiments, the portions 242B of the metal pad 242 (and the opening 232 of the passivation layer 23) may have different widths, and the width W1 of each portion 242B in the horizontal direction D1 may be equal to or greater than the width W2 of the portion 243B of the metal pad 243 in the horizontal direction D1 (equal to the width of the opening 233 of the passivation layer 23).

[0105] The passivation layer 25 is conformally formed on a metal pad 242 having a stepped structure (consisting of the portion 242A on the passivation layer 23 and the portion 242B recessed into the passivation layer 23), thus a stepped structure SS is also formed on the top surface 25A of the passivation layer 25. According to some embodiments, such as... Figure 3 As shown, the stepped structure SS includes a plurality of (e.g., three) higher portions SS1 above and corresponding to the portion 242A of the metal pad 242, and a plurality of (e.g., two) lower portions SS2 above and corresponding to the portion 242B of the metal pad 242 (lower than the higher portions SS1 in the vertical direction D2). The width of each lower portion SS2 in the horizontal direction D1 can be determined according to the width W1 of the corresponding portion 242B.

[0106] As described above, due to the larger width of the portion 242B of the metal pad 242 and / or the increased number of portions 242B (in some cases, two or more), a correspondingly wider stepped structure SS is achieved on the metal pad 242. In this way, the peripheral portion 280 of the polymer layer 28 above the passivation layer 25 can extend into one or more lower portions SS2 of the stepped structure SS to engage with the stepped structure SS (it should be understood that although the peripheral portion 280 is shown as filling one of the lower portions SS2, it can also fill multiple lower portions SS2). As a result, the adhesion between the polymer layer 28 and the passivation layer 25 is improved, thereby reducing the risk of delamination of the polymer layer 28. Therefore, the reliability of the entire packaging structure is improved.

[0107] Figure 4 It is to form a wafer-level package structure according to some embodiments (e.g.) Figure 2 or Figure 3 A simplified flowchart of method 400 (shown as a chip-level packaging structure) is provided. For illustration, the flowchart will be compared with... Figure 2 and Figure 3The accompanying drawings illustrate this. In different embodiments, some described operations may be replaced or eliminated. Alternatively, some operations may be added in different embodiments.

[0108] Method 400 includes operation 401, wherein a substrate 20 is provided. In some embodiments, the substrate 20 has a plurality of devices 21 formed therein, such as active devices and passive devices. In some embodiments, an interconnect structure 22 is formed on the substrate 20 and electrically coupled to the devices 21. Details of the interconnect structure 22 can be found in... Figure 2 The description.

[0109] Method 400 further includes operation 402, wherein a (first) passivation layer 23 (sometimes referred to as a bottom passivation layer) is formed over substrate 20. In some embodiments, passivation layer 23 is formed on interconnect structure 22 over substrate 20. In some embodiments, a patterning process (e.g., a mask-defined photoresist etching process) is performed on passivation layer 23 to simultaneously form a plurality of openings 231, 232, and 233 for receiving subsequently formed bonding pads 241 and sealing ring pads 242 and 243, respectively. In some embodiments, the width W1 of the opening 232 for sealing ring pad 242 (near bonding pad 241) is greater than the width W2 of the opening 233 for sealing ring pad 243 (away from bonding pad 241). Additionally or alternatively, two or more openings 232 may be used for sealing ring pad 242.

[0110] Method 400 further includes operation 403, wherein a metal layer 24 is conformally formed on the passivation layer 23. In some embodiments, a portion of the metal layer 24 extends into openings 231, 232, and 233 of the passivation layer 23. In some embodiments, a patterning process (e.g., a mask-defined photoresist etching process) is performed on the metal layer 24 to simultaneously form bonding pads 241 and sealing ring pads 242 and 243.

[0111] Method 400 further includes operation 404, wherein a (second) passivation layer 25 (sometimes referred to as a top passivation layer) is conformally formed on the passivation layer 23 and the patterned metal layer 24 (including bonding pads 241 and sealing ring pads 242 and 243). In some embodiments, a stepped structure SS is formed on the top surface 25A of the passivation layer 25 and corresponds to the sealing ring pad 242 having a stepped structure (see...). Figure 2 and Figure 3 In some embodiments, the stepped structure SS includes a plurality of higher portions SS1 and one or more lower portions (grooves) SS2, which correspond to the shape of the sealing ring gasket 242 below.

[0112] Method 400 further includes operation 405, wherein a back-end-of-line (BEOL) process is performed, including forming and patterning a polymer layer 26, a post-passivation interconnect (PPI) layer 27, a polymer layer 28, and a bump under-metallization (UBM) layer 29 on the passivation layer 25, and then mounting a plurality of electrical connectors 30 (e.g., solder balls) on the patterned bump under-metallization layer 29. Figure 2 As shown. In some embodiments, the polymer layer 28 extends to partially cover the stepped structure SS of the passivation layer 25, and the peripheral portion 280 of the polymer layer 28 extends into one or more lower portions (grooves) SS2 to engage with the stepped structure SS, thereby improving the anchorage of the polymer layer 28 on the passivation layer 25. According to some embodiments, after the BEOL process is completed, a die dicing or monomerization process is performed using a mechanical or laser saw to remove the wafer 12 (see...) Figure 1A Multiple individual numeric pieces were separated from the original 11.

[0113] Embodiments of this disclosure form a wafer-level package structure with a polymer layer delamination prevention design. According to some embodiments, the polymer layer delamination prevention design is achieved by increasing the number of openings in the bottom passivation layer and / or increasing the width of these openings to form a stepped structure on the top surface of the top passivation layer. The morphology of the stepped structure has a height difference (i.e., unevenness) that matches the morphology of the underlying layer, allowing the polymer layer landing on the top passivation layer to better engage with the stepped structure. Therefore, the risk of polymer layer delamination is reduced, and the reliability of the package structure is improved.

[0114] According to some embodiments of this disclosure, a packaging structure includes a substrate, a first passivation layer, a metal layer, a second passivation layer, and a polymer layer. The first passivation layer is formed on the substrate. The metal layer is conformally formed on the first passivation layer. The second passivation layer is conformally formed on the first passivation layer and the metal layer. A stepped structure is formed on the top surface of the second passivation layer and includes at least one lower portion, said at least one lower portion being lower than other portions of the stepped structure. The polymer layer is formed on the second passivation layer. A portion of the polymer layer extends into said at least one lower portion of the stepped structure to engage with the stepped structure.

[0115] In some embodiments, the portion of the polymer layer that engages with the stepped structure is located below the periphery of the polymer layer. In some embodiments, the metal layer includes a first metal pad, and the first metal pad includes a plurality of first portions and a second portion, the first portions being located above a first passivation layer, and the second portion being located between the first portions and extending into the first passivation layer. The stepped structure includes a plurality of higher portions and a lower portion, the lower portion being located between the higher portions and below the higher portions. The positions of the higher portions correspond to the positions of the first portions of the first metal pad, and the positions of the lower portions correspond to the positions of the second portions of the first metal pad. In some embodiments, a device is placed on a substrate, and the metal layer further includes a second metal pad covered by the polymer layer and separated from the first metal pad. The second metal pad is electrically coupled to the device, and the first metal pad is insulated from the device. In some embodiments, the metal layer further includes a second metal pad farther from the polymer layer than the first metal pad, and the second metal pad includes a plurality of third portions and a fourth portion, the third portions being located above the first passivation layer, and the fourth portion being located between the third portions and extending into the first passivation layer. In some embodiments, the width of a second portion of the first metal pad is greater than the width of a fourth portion of the second metal pad in a horizontal direction parallel to the top surface of the second passivation layer. In some embodiments, the first metal pad further includes a plurality of second portions located between the first portions and extending into the first passivation layer. The stepped structure also includes a plurality of lower portions located between the higher portions and below the higher portions. The positions of the higher portions correspond to the positions of the first portions of the first metal pad, and the positions of the lower portions correspond to the positions of the second portions of the first metal pad. In some embodiments, one of the first portions is located between two of the second portions, and one of the higher portions is located between two of the lower portions. In some embodiments, the metal layer further includes a second metal pad farther from the polymer layer than the first metal pad, and the second metal pad includes a plurality of third portions and a fourth portion, the third portions being located above the first passivation layer, and the fourth portion being located between the third portions and extending into the first passivation layer. In some embodiments, the width of each of the second portions of the first metal pad is equal to or greater than the width of the fourth portion of the second metal pad in a horizontal direction parallel to the top surface of the second passivation layer. In some embodiments, the second portions of the first metal pad have the same width. In some embodiments, the portion of the polymer that engages with the stepped structure extends into one of the lower portions.

[0116] According to other embodiments of this disclosure, a package structure includes a substrate, a first passivation layer, a metal layer, a second passivation layer, and a polymer layer. The first passivation layer is formed on the substrate. The metal layer is formed on the first passivation layer, and at least a portion of the metal layer extends into the first passivation layer. The second passivation layer is conformally formed on the first passivation layer and the metal layer. A stepped structure is formed on the top surface of the second passivation layer and includes at least one lower portion, said at least one lower portion being lower than other portions of the stepped structure. The at least one lower portion of the stepped structure corresponds to said at least one portion of the metal layer in the first passivation layer. The polymer layer is formed on the second passivation layer. A peripheral portion of the polymer layer extends into said at least one lower portion of the stepped structure.

[0117] In some embodiments, the metal layer includes a first metal pad and a second metal pad. The first metal pad has a plurality of first portions and a second portion, the first portions being located above a first passivation layer, the second portions being located between the first portions and extending into the first passivation layer, and the stepped structure including a plurality of higher portions and a lower portion, the lower portion being located between the higher portions and below the higher portions, wherein the positions of the higher portions correspond to the positions of the first portions of the first metal pad, and the positions of the lower portions correspond to the positions of the second portions of the first metal pad. The second metal pad is further away from the polymer layer than the first metal pad, and the second metal pad has a plurality of third portions and a fourth portion, the third portions being located above the first passivation layer, and the fourth portion being located between the third portions and extending into the first passivation layer. In a horizontal direction parallel to the top surface of the second passivation layer, the width of the second portion of the first metal pad is greater than the width of the fourth portion of the second metal pad. In some embodiments, the metal layer further includes a third metal pad located below the polymer layer and separated from the first and second metal pads. The package structure further includes a device located in a first region of the substrate, and the third metal pad is electrically coupled to the device. In this embodiment, a first metal pad and a second metal pad are located in a second region, which surrounds a first region. In some embodiments, the metal layer includes a first metal pad and a second metal pad. The first metal pad has a plurality of first portions and a plurality of second portions, the first portions being located above a first passivation layer, the second portions being located between the first portions and extending into the first passivation layer, and the stepped structure including a plurality of higher portions and a plurality of lower portions, the lower portions being located between the higher portions and below the higher portions, wherein the positions of the higher portions correspond to the positions of the first portions of the first metal pad, and the positions of the lower portions correspond to the positions of the second portions of the first metal pad. The second metal pad is further away from the polymer layer than the first metal pad, and the second metal pad has a plurality of third portions and a fourth portion, the third portions being located above the first passivation layer, and the fourth portion being located between the third portions and extending into the first passivation layer. In some embodiments, the second portions of the first metal pad have different widths in a horizontal direction parallel to the top surface of the second passivation layer, and the lower portions of the stepped structure have different widths.

[0118] According to other embodiments of this disclosure, a method for forming a package structure is provided. The method includes forming a first passivation layer on a substrate. The method also includes conformally forming a metal layer on the first passivation layer. The method further includes conformally forming a second passivation layer on the first passivation layer and the metal layer, such that a stepped structure is formed on the top surface of the second passivation layer, wherein the stepped structure has at least one lower portion that is lower than other portions of the stepped structure. Furthermore, the method includes forming a polymer layer on the second passivation layer, wherein a peripheral portion of the polymer layer extends into the at least one lower portion of the stepped structure to engage with the stepped structure.

[0119] In some embodiments, the method further includes patterning a first passivation layer to form at least one first opening in the first passivation layer before forming a metal layer. The step of forming the metal layer includes conformally forming a first metal pad on the first passivation layer, and the first metal pad having at least one first portion extending into the at least one first opening. After forming the polymer layer, the at least one lower portion of the stepped structure corresponds to the at least one first portion of the first metal pad. In some embodiments, the at least one first opening of the first passivation layer includes a plurality of first openings separated from each other, the at least one first portion of the first metal pad includes a plurality of first portions, and the at least one lower portion of the stepped structure includes a plurality of lower portions. The position of the lower portions corresponds to the position of the first opening and the position of the first portions. In some embodiments, after forming the polymer layer, a peripheral portion of the polymer layer extends into one or more of the lower portions. In some embodiments, the method further includes patterning a first passivation layer to form a second opening in the first passivation layer before forming a metal layer. The step of forming the metal layer further includes conformally forming a second metal pad on the first passivation layer, and the second metal pad having a second portion extending into the second opening. Wherein, after the polymer layer is formed, the second metal pad is further away from the polymer layer than the first metal pad, and in a horizontal direction parallel to the top surface of the second passivation layer, the width of the at least one first portion of the first metal pad is greater than the width of the second portion of the second metal pad.

[0120] The foregoing outlines features of numerous embodiments to enable those skilled in the art to better understand this disclosure from various perspectives. Those skilled in the art will understand that other processes and structures can be readily designed or modified based on this disclosure to achieve the same purpose and / or the same advantages as the embodiments described herein. Those skilled in the art will also understand that these equivalent structures do not depart from the inventive spirit and scope of this disclosure. Various changes, substitutions, or modifications can be made to this disclosure without departing from its inventive spirit and scope.

Claims

1. A packaging structure, comprising: One substrate; A first passivation layer is formed on the substrate; A metal layer is conformally formed on the first passivation layer; A second passivation layer is conformally formed on the first passivation layer and the metal layer, wherein a stepped structure is formed on a top surface of the second passivation layer and includes at least one lower portion, which is lower than the other portions of the stepped structure. as well as A polymer layer is formed on the second passivation layer, wherein a portion of the polymer layer extends into at least one lower portion of the stepped structure to engage with the stepped structure. The metal layer includes a first metal pad, and the first metal pad includes a plurality of first portions and a second portion. The plurality of first portions are located on the first passivation layer, and the second portion is located between the plurality of first portions and extends into the first passivation layer. The stepped structure includes multiple higher sections and a lower section, wherein the lower section is located between and below the multiple higher sections. The positions of the plurality of higher portions correspond to the positions of the plurality of first portions of the first metal pad, and the positions of the lower portions correspond to the positions of the second portions of the first metal pad. The metal layer further includes a second metal pad located further away from the polymer layer than the first metal pad, and the second metal pad includes a plurality of third portions and a fourth portion. The plurality of third portions are located above the first passivation layer, and the fourth portion is located between the plurality of third portions and extends into the first passivation layer. In a horizontal direction parallel to the top surface of the second passivation layer, the width of the second portion of the first metal pad is greater than the width of the fourth portion of the second metal pad.

2. The encapsulation structure of claim 1, wherein the portion of the polymer layer that engages with the stepped structure is located below the periphery of the polymer layer.

3. The packaging structure of claim 1, wherein a device is placed on the substrate, and the metal layer further includes a third metal pad covered by the polymer layer and separated from the first metal pad, and The third metal pad is electrically coupled to the device, and the first metal pad is insulated from the device.

4. The packaging structure of claim 1, wherein the first metal pad further comprises a plurality of second portions located between the plurality of first portions and extending into the first passivation layer, and The stepped structure also includes a plurality of lower portions located between and below the plurality of higher portions, and The positions of the plurality of higher portions correspond to the positions of the plurality of first portions of the first metal pad, and the positions of the plurality of lower portions correspond to the positions of the plurality of second portions of the first metal pad.

5. The packaging structure of claim 4, wherein one of the plurality of first portions is located between two of the plurality of second portions, and one of the plurality of higher portions is located between two of the plurality of lower portions.

6. The packaging structure of claim 4, wherein in a horizontal direction parallel to the top surface of the second passivation layer, the width of each of the plurality of second portions of the first metal pad is greater than the width of the fourth portion of the second metal pad.

7. The packaging structure of claim 6, wherein the plurality of second portions of the first metal pad have the same width.

8. The encapsulation structure of claim 4, wherein the portion of the polymer engaging with the stepped structure extends into one of the plurality of lower portions.

9. A packaging structure, comprising: One substrate; A first passivation layer is formed on the substrate; A metal layer is formed on the first passivation layer, and at least a portion of the metal layer extends into the first passivation layer; A second passivation layer is conformally formed on the first passivation layer and the metal layer, wherein a stepped structure is formed on a top surface of the second passivation layer and includes at least one lower portion, the at least one lower portion being lower than other portions of the stepped structure, wherein the at least one lower portion of the stepped structure corresponds to the at least portion of the metal layer in the first passivation layer; and A polymer layer is formed on the second passivation layer, wherein a peripheral portion of the polymer layer extends into the at least one lower portion of the stepped structure. The metal layer includes: A first metal pad having a plurality of first portions and a second portion, the plurality of first portions being located above a first passivation layer, the second portion being located between the plurality of first portions and extending into the first passivation layer, wherein the stepped structure includes a plurality of higher portions and a lower portion, the lower portion being located between the plurality of higher portions and below the plurality of higher portions, wherein the positions of the plurality of higher portions correspond to the positions of the plurality of first portions of the first metal pad, and the positions of the lower portion correspond to the positions of the second portion of the first metal pad; as well as A second metal pad, wherein the second metal pad is further away from the polymer layer than the first metal pad, and the second metal pad has a plurality of third portions and a fourth portion, the plurality of third portions being located above the first passivation layer, and the fourth portion being located between the plurality of third portions and extending into the first passivation layer. In a horizontal direction parallel to the top surface of the second passivation layer, the width of the second portion of the first metal pad is greater than the width of the fourth portion of the second metal pad.

10. The packaging structure of claim 9, wherein the metal layer further comprises: A third metal pad, wherein the third metal pad is located below the polymer layer and is separate from the first metal pad and the second metal pad, and The packaging structure further includes a device located in a first region of the substrate, and the third metal pad is electrically coupled to the device. The first metal pad and the second metal pad are located in a second region, which surrounds the first region.

11. The packaging structure of claim 9, wherein the first metal pad further has a plurality of second portions, the plurality of second portions being located between the plurality of first portions and extending into the first passivation layer, and wherein the stepped structure includes a plurality of higher portions and a plurality of lower portions, the plurality of lower portions being located between the plurality of higher portions and below the plurality of higher portions, wherein the positions of the plurality of higher portions correspond to the positions of the plurality of first portions of the first metal pad, and the positions of the plurality of lower portions correspond to the positions of the plurality of second portions of the first metal pad.

12. The packaging structure of claim 11, wherein in a horizontal direction parallel to the top surface of the second passivation layer, the plurality of second portions of the first metal pad have different widths, and the plurality of lower portions of the stepped structure have different widths.

13. A method for forming an encapsulation structure, comprising: A first passivation layer is formed on a substrate; The first passivation layer is patterned to form at least a first opening and a second opening in the first passivation layer; A metal layer is conformally formed on the first passivation layer, including a first metal pad and a second metal pad conformally formed on the first passivation layer. The first metal pad has at least a first portion extending into the at least one first opening, and the second metal pad has a second portion extending into the second opening. A second passivation layer is conformally formed on the first passivation layer and the metal layer, such that a stepped structure is formed on a top surface of the second passivation layer, wherein the stepped structure has at least one lower portion that is lower than the other portions of the stepped structure; and A polymer layer is formed on the second passivation layer, wherein a peripheral portion of the polymer layer extends into the at least one lower portion of the stepped structure to engage with the stepped structure, wherein after the formation of the polymer layer, the at least one lower portion of the stepped structure corresponds to the at least one first portion of the first metal pad, and wherein after the formation of the polymer layer, the second metal pad is further away from the polymer layer than the first metal pad, and in a horizontal direction parallel to the top surface of the second passivation layer, the width of each of the at least one first portion of the first metal pad is greater than the width of the second portion of the second metal pad.

14. The method of forming an encapsulation structure as claimed in claim 13, wherein the at least one first opening of the first passivation layer comprises a plurality of first openings separated from each other, the at least one first portion of the first metal pad comprises a plurality of first portions, and the at least one lower portion of the stepped structure comprises a plurality of lower portions, and The positions of the plurality of lower portions correspond to the positions of the plurality of first openings and the positions of the plurality of first portions.

15. The method of forming an encapsulation structure as claimed in claim 14, wherein after the polymer layer is formed, the peripheral portion of the polymer layer extends into one or more of the plurality of lower portions.

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