MANUFACTURING PROCESS OF A LOTHÖCKER STRUCTURE

Abstract

Method for producing a bump structure, comprising: forming a passivation layer (25, 30) over a substrate (10); forming a metal pad structure (35) over the substrate (10), wherein the passivation layer (25, 30) surrounds the metal pad structure (35); forming a polyimide layer (40, 40a, 40b) containing a polyimide over the passivation layer (25, 30) and the metal pad structure (35); and formation of a metal bump (55) over the metal pad structure (35) and the polyimide layer (40, 40a, 40b), wherein the metal bump (55) is in electrical contact with the metal pad structure (35), wherein the polyimide layer (40, 40a, 40b) is bonded to the passivation layer (25, 30) and the metal pad structure (35) by an adhesion promoter, wherein the adhesion promoter is chemically bonded to the polyimide, the passivation layer (25, 30) and the metal pad structure (35), and wherein the adhesion promoter contains a chelating group, a silanol group and a crosslinking group.

Description

BACKGROUNDWhile consumer devices with ever better performance have become smaller and smaller in response to demand from the consumers, individual components of these devices have also necessarily been miniaturized. Semiconductor devices constituting the main constituent elements of consumer devices such as mobile phones, computer tablets and the like have become smaller and smaller. Downsizing of semiconductor devices has been accomplished through advances in semiconductor manufacturing techniques such as the fabrication of interconnects between semiconductor devices.While the electronics industry develops three-dimensional integrated circuits (3D IC) based on through-Si (through-silicon) technology, the processing and reliability of bumps (bumps) used to interconnect the stacked chips is actively studied. Delamination (delamination) of dielectric layers, such as extreme low-k dielectric layers, in bump areas presents problems with smaller devices. Delamination of extreme low-k dielectric layers may cause failure or malfunction of the device.US 2021 / 0047470 A1 describes a method for producing a bump structure having an insulating film made of an alkali-soluble plastic, with which high extensibility, high adhesion to metal, reduced mechanical stress and high heat resistance can be achieved. DE 10 2006 051 491 A1 describes a method for producing a bump structure with direct formation of a bump underside metallization layer on a contact region of the last metallization layer.BRIEF DESCRIPTION OF THE DRAWINGSThe present disclosure will be best understood from the following detailed description taken in conjunction with the accompanying drawings. It should be appreciated that, in accordance with practice in the industry, various features are not drawn to scale and are for purposes of illustration only. Indeed, for clarity of explanation, the dimensions of the various features may be arbitrarily increased or decreased. FIGS. 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 1J, 1K, 1L, 1M, and 1N are cross-sectional views of stages of a sequential method of manufacturing a bump structure according to an embodiment of the disclosure. FIG. 2 illustrates the formation of a polyimide according to embodiments of the disclosure. FIG. 3A illustrates various dianhydride reactants used in forming polyimides in accordance with embodiments of the disclosure. FIG. 3B illustrates various diamine reactants used in forming polyimides in accordance with embodiments of the disclosure. FIGS. 4A, 4B, and 4C are cross-sectional views of stages of a sequential method of forming a bump structure according to an embodiment of the disclosure. FIGS. 5A, 5B, 5C, 5D, 5E, 5F, and 5G are cross-sectional views of stages of a sequential method of forming a bump structure, according to an embodiment of the disclosure. FIG. 6A illustrates an adhesion promoter for improving adhesion of the polyimide layer to metal substrates. FIG. 6B illustrates the adhesion promoter without capping solution. FIG. 6C shows a solution of the adhesion promoter and a capping solvent according to embodiments of the disclosure. FIG. 7 illustrates a process flow for manufacturing a semiconductor device according to embodiments of the disclosure.DETAILED DESCRIPTIONIt is to be understood that the following disclosure provides many different embodiments or examples for implementing various features of the invention. Specific embodiments or examples of constituent elements and arrangements will be described below in order to simplify the present disclosure. These are of course only examples, which should not be limiting. For example, the dimensions of elements are not limited to the disclosed range or values, but may depend on process conditions and / or desired characteristics of the device. Moreover, the formation of a first feature over or on a second feature in the following description may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features such that the first and second features may not be in direct contact. Various features may be drawn at various arbitrary scales for simplicity and clarity.Further, for convenience herein, spatially relative terms such as "bottom," "below," "downward," "above," "above," "upward," and the like may be used to describe the relationship of an element or feature to one or more other element or feature(s) as illustrated in the drawings. The spatially relative terms are intended to encompass different orientations of the device during use or operation in addition to the orientation depicted in the drawings. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may also be interpreted accordingly. Moreover, the term "made of" may mean "comprising" or "consisting of.".Embodiments of the present disclosure relate to polyamic acid compositions, bump structures having a polyimide layer, semiconductor devices, methods of forming polyimide layers, methods of making bump structures, and methods of making semiconductor devices. Embodiments of the disclosure relate to bump structures for an integrated circuit with higher elastic modulus polyimide layers.FIGS. 1A-1N are cross-sectional views of stages of a sequential method of forming a bump structure, according to an embodiment of the disclosure. It should be appreciated that additional operations may be provided before, during, and after the processes illustrated in FIGS. 1A-1N, and some of the operations described below may be replaced or eliminated for additional embodiments of the method. The order of the operations / processes may be interchangeable. As shown in FIG. 1A, in some embodiments, a dielectric layer 15 is formed over a substrate 10. In some embodiments, the substrate 10 includes a semiconductor device 5 disposed over a semiconductor wafer such as a silicon wafer. In some embodiments, the semiconductor device 5 includes one or more transistors, such as field effect transistors. In other embodiments, the semiconductor device 5 includes capacitors, inductors, resistors, diodes, integrated circuits, and related wirings and interconnections embedded in an insulating layer.In some embodiments, the dielectric layer 15 is an interlayer dielectric (ILD) layer. The materials of the ILD layer 15 include compounds containing Si, O, C, and / or H, such as silicon oxide, SiCOH, and SiOC. In some embodiments, the dielectric layer is an extremely low k (ELK) material having a dielectric constant less than about 2.5. In some embodiments, the ELK has a dielectric constant between about 1.8 and about 2.1. In some embodiments, the ELK materials include porous SiCOH or porous SiOC. The dielectric layer 15 may be formed by chemical vapor deposition (CVD), low pressure chemical vapor deposition (LPCVD), plasma enhanced chemical vapor deposition (CVD), or atomic layer deposition (ALD), or any other suitable method of film formation. Organic materials such as polymers may also be used for the ILD layer 15.In some embodiments, openings or trenches 17 are formed in the dielectric layer 15 by suitable photolithographic and etching operations, as shown in FIG. 1B. In some embodiments, the opening is disposed in the substrate via electrical contacts on the semiconductor device 5. As shown in FIG. 1C, the opening 17 is subsequently filled with an electrically conductive material, such as a metal, to form a metal contact 20 connecting the semiconductor device 5 and a metal pad structure, which is subsequently formed. In some embodiments, the metal includes aluminum, copper, nickel, titanium, tantalum, tungsten, cobalt, molybdenum, and alloys thereof. The metal may be deposited by physical vapor deposition (PVD), sputtering, chemical vapor deposition (CVD), atomic layer deposition (ALD), or electroplating (electroplating). In some embodiments, a planarization operation is performed after depositing the metal to remove metal overlying the top surface of the dielectric layer 15. In some embodiments, the planarization operation is a chemical mechanical polishing (CMP) operation or an etch back operation. In some embodiments, the metal contact 20 is a metal interconnect.Next, a passivation layer 25 is formed over the dielectric layer 15 and the metal contact 20, as shown in FIG. 1D. In some embodiments, the passivation layer 25 is a first passivation layer and one or more additional passivation layers are formed over the first passivation layer 25. For example, as shown in FIG. 1E, a second passivation layer 30 is formed over the first passivation layer 25. In some embodiments, the first passivation layer 25 and the second passivation layer 30 are formed of different materials or formed under different deposition parameters to provide passivation layers having different physical properties, such as different densities and porosities. The first passivation layer and the second passivation layer may be an oxide layer such as silicon oxide or a nitride layer such as silicon nitride. In some embodiments, the first passivation layer 25 is silicon dioxide and the second passivation layer 30 is silicon nitride. In some embodiments, the first passivation layer and the second passivation layer independently have a thickness of about 1 μm to about 5 μm. In some embodiments, if the passivation layers are less than about 1 μm, the passivation layers do not have sufficient thickness, and if the passivation layers are greater than about 5 μm, the passivation layers do not provide additional advantages and the overall thickness of the device is unnecessarily increased.An opening 33 is formed in the passivation layer(s) by suitable photolithography and etching operations exposing the metal contact 20, as shown in FIG. 1F. Then, a metal pad structure 35 is formed by forming a metal layer over the opening 33 and the passivation layer 30, as shown in FIG. 1G. In some embodiments, the metal pad structure 35 is formed of aluminum, copper, silver, gold, nickel, tungsten, titanium, tin, titanium nitride, hafnium, tin, ruthenium, tantalum, tantalum nitride, alloys, or multilayers thereof. In some embodiments, the metal pad is an AlCu alloy. The metal layer is formed by physical vapor deposition, chemical vapor deposition, atomic layer deposition, or electroplating (electroplating) in some embodiments. The metal layer is planarized, in some embodiments, such as by chemical mechanical polishing (CMP) or by an etch back operation. In some embodiments, portions of the metal layer overlying the second passivation layer 30 are removed by suitable photolithography and etching operations to form the metal pad structure 35.After the formation of the metal pad structure 35, the deposition of the second passivation layer 30 is continued so that the second passivation layer 30 covers the upper surface of the metal pad structure 35. In some embodiments, a third passivation layer is formed, wherein the third passivation layer is a different material than the second passivation layer. Then, the second passivation layer 30 is planarized, e.g., by CMP or etchback, and an opening 37 is formed in the second passivation layer 30 over the metal pad structure 35 using suitable photolithography and etching operations. In some embodiments, the top surface of the metal pad structure 35 is recessed by suitable photolithographic patterning and etching operations, as shown in FIG. 1H. In some embodiments, an upper portion of the metal pad structure 35 extends along the X direction (horizontal direction) from the lower side walls extending in the Y direction (vertical direction) of the metal pad structure 35.As shown in FIG. 1I, an organic material layer (e.g., polymer), such as a polyimide layer 40, containing a polyimide is formed over the second passivation layer 30 and the metal pad structure 35. The polyimide layer 40 is patterned by suitable photolithography and etching operations to expose the surface of the metal pad structure 35 through an opening 37'. In some embodiments, the polyimide layer 40 has a thickness after curing of about 2 μm to about 10 μm. If the thickness of the polyimide layer is less than about 2 μm, the polyimide layer may provide insufficient protection of the passivation layer, and if the thickness of the polyimide layer is greater than about 10 μm, no additional advantages are obtained and the overall thickness of the device is unnecessarily increased.In some embodiments, the polyimide layer 40 is formed by forming a polyamic acid composition containing a polyamic acid over the device and then converting the polyamic acid to a polyimide by heating the polyamic acid to a temperature of about 150° C. to about 350° C. At temperatures below about 150°C, the polyamic acid may not be converted to a polyimide in sufficient amount. At temperatures above about 350° C., the substrate may deform or be damaged. The polyimide layer acts as a buffer layer to spread the pressure generated during a flip-chip bonding operation over the surface of the device, thereby protecting the device from damage when the pressure is concentrated in a region around the bump.In some embodiments, the polyamic acid is a reaction product of a dianhydride and a diamine, wherein at least one of the dianhydride and the diamine contains one of the following group: a cycloalkane, a fused ring (fused ring), a bicycloalkane, a tricycloalkane, a bicycloalkene, a tricycloalkene, a spiroalkane, and a heterocyclic ring. The reaction of dianhydride and a diamine to form a polyimide is illustrated in Figure 2. The dianhydride and the diamine first form a polyamic acid and, in some embodiments, the polyamic acid is converted to a polyimide upon heating the polyamic acid.In some embodiments, at least one of the dianhydride and the diamine contains a tricycloalkane or tricycloalkene. In some embodiments, at least one of dianhydride and diamine contains two or more cyclic groups. In some embodiments, the two or more cyclic groups are linked together by a linking group selected from the group consisting of -CH2-, -CH=CH-, -C ≡C-, -O-, -C(O)O-, -CF3CH2CF3-, -CH3CH2CH3-, -SH-, and -SO2-. In some embodiments, the cycloalkane is selected from the group consisting of cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane and cyclooctane. In some embodiments, the fused ring is selected from the group consisting of naphthalene, anthracene, phenanthrene, chrysene, pyrene, coranulen, coronene, hexhelicene, indole, isoindole, indolizine, quinoline, isoquinoline, purine, carbazole, dibenzofuran, xanthene, phenazine, phenoxazine, and phenoxathiine. In some embodiments, the bicycloalkane is Bicyclo[3.2.0]heptan. In some embodiments, the tricycloalkane is adamantane. In some embodiments, the spiroalkane is spiro[2.2]pentane. In some embodiments, the heterocyclic ring is selected from the group consisting of thiolane, oxolane and pyrrole.In some embodiments, the dianhydride is selected from the group consisting of cyclobutanetetracarboxylic dianhydride, 4,4'-biphthalic anhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 5,5'-(9H-fluorene-9,9-diyl)bis(2-benzofuran-1,3-dione, 2,3,6,7-naphthalenetetracarboxylic 2,3:6,7-dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, and 4,4'-(ethyne-1,2-diyl)diphthalic anhydride, as depicted in Figure 3A. In some embodiments, the diamine is selected from the group consisting of Bis(aminoethyl)norbornan 2,6-diaminoanthraquinone, 1,5-diaminonaphthalene, 4,4"-diamino-p-terphenyl, 9,9-bis(4-aminophenyl)fluorene, 2,7-diaminofluorene, 2,6-diaminopyridine and 3,6-diaminocarbazole, as shown in Figure 3B.In some embodiments, the polyimide layer 40 has a Young's modulus (Young's modulus) of about 4.5 GPa to about 7 GPa. In some embodiments, the polyimide layer 40 has a modulus of elasticity of greater than 5 GPa to about 7 GPa.In some embodiments, an under bump metallization layer (seed layer) 45 is formed over the polyimide layer 40 and the metal pad 35, as shown in FIG. 1J. In some embodiments, the under bump metallization layer 45 includes a double layer including a titanium-based layer and a copper-based layer. In some embodiments, the titanium-based layer contains titanium, titanium alloys, and titanium compounds with 50 mol % or more of titanium, and the copper-based layer contains copper, copper alloys, and copper compounds with 50 mol % or more of copper. In some embodiments, the under bump metallization layer 45 has a thickness of about 50 nm to about 1 μm. In some embodiments, the titanium-based layer is the bottom layer of the bilayer and the titanium-based layer has a thickness of about 25 nm to about 400 nm. In other embodiments, the titanium-based layer has a thickness of about 50 nm to about 200 nm. In some embodiments, the copper-based layer is the top layer of the bilayer and the copper-based layer has a thickness of about 25 nm to about 800 nm. In other embodiments, the copper-based layer has a thickness of about 100 nm to about 600 nm.Then, a photoresist layer 50 is formed over the under bump metallization layer 45 or the polyimide layer 40, as shown in FIG. 1K. The photoresist layer 50 is patterned by suitable photolithographic operations to form an opening 53 in the photoresist layer over the metal pad structure 35. The photoresist layer 50 may be a positive tone resist or a negative tone resist. A positive tone resist refers to a photoresist material which becomes soluble in a developer upon exposure to radiation (typically UV light), while the portion of the photoresist that is not (or less) exposed is insoluble in the developer. A negative tone resist, on the other hand, refers to a photoresist material which becomes insoluble in the developer upon exposure to radiation (typically UV light), while the portion of the photoresist which is not (or less) exposed is soluble in the developer. The portion of a negative tone resist which becomes insoluble after exposure may become insoluble due to a crosslinking reaction caused by exposure.Whether a resist is a positive tone or a negative tone may depend on the type of developer used to develop the resist. For example, some positive tone photoresists provide a positive pattern (i.e., exposed areas are removed by the developer) when the developer is a water-based developer, such as a tetramethylammonium hydroxide (TMAH) solution. On the other hand, the same photoresist provides a negative pattern (i.e., unexposed areas are removed by the developer) when the developer is an organic solvent. Further, in some negative photoresists developed with the TMAH solution, the unexposed areas of the photoresist are removed by the TMAH and the exposed areas of the photoresist, which are crosslinked upon exposure to actinic radiation, remain on the substrate after development. In some embodiments of the present disclosure, a negative tone photoresist is exposed to actinic radiation. The exposed portions of the negative tone photoresist are crosslinked as a result of exposure to actinic radiation and the unexposed, uncrosslinked portions of the photoresist are removed during development by the developer, leaving the exposed areas of the photoresist on the substrate.A metal bump 55 is then placed over the metal pad structure 35 and the polyimide layer 40. As shown in FIG. 1L, the metal bump is formed by depositing a metal in the photoresist opening 53. The metal bump 55 is in electrical contact with the metal pad structure 35. in some embodiments, the metal bump 55 is in electrical contact with the metal pad structure 35 via the under bump metallization layer 45. in some embodiments, the metal bump 55 is formed of one or more metals from the group consisting of aluminum, copper, chromium, iron, manganese, magnesium, molybdenum, nickel, tin, niobium, tantalum, titanium, tungsten, zinc, and alloys thereof. In some embodiments, the metal bump 55 is formed by electroplating (electroplating), physical vapor deposition, chemical vapor deposition, or evaporative deposition. In some embodiments, the metal bump 55 has a thickness of about 500 nm to about 50 μm.In some embodiments, a solder layer 60 is formed over the metal bump. In some embodiments, the solder layer is formed of a tin-containing alloy selected from the group consisting of PbSn, AgSn, SnAgCu, CuSnNi, AgCuSnSn, AuSn, and CuSn.Then, the photoresist layer 50 is removed by a suitable photoresist removing technique such as a solvent stripping operation or a plasma ashing operation as shown in Fig. 1M. In some embodiments, the exposed portion of under bump metallization 45 is removed by a suitable etching operation. After removal of the photoresist layer 50, in some embodiments, the solder layer 60 is reflowed to form a smooth hemispherical shape, as shown in FIG. 1N. The solder layer 60 is reflowed by heating the solder to a temperature at which it softens and flows.FIGS. 4A, 4B, and 4C are cross-sectional views of stages of a sequential method of manufacturing a semiconductor device according to an embodiment of the disclosure. The structure in FIG. 4A is fabricated by the operations explained below with reference to FIGS. 1A-1F. Then, a metal pad structure 35 is formed by forming a metal layer over the opening 33 and the passivation layer 30, as shown in FIG. 4A. In some embodiments, the metal pad structure 35 includes aluminum, copper, silver, gold, nickel, tungsten, titanium, tin, titanium nitride, hafnium, tin, ruthenium, tantalum, tantalum nitride, alloys thereof, or multilayers thereof. In some embodiments, the metal pad is an AlCu alloy. In some embodiments, the metal layer is formed by PVD, CVD, ALD, or electroplating. The metal layer is planarized, e.g., by CMP or by etching, in some embodiments. In some embodiments, portions of the metal layer overlying the second passivation layer 30 are removed by suitable photolithography and etching operations to form the metal pad structure 35.After the formation of the metal pad structure 35, the deposition of the second passivation layer 30 is continued so that the second passivation layer covers the upper surface of the metal pad structure 35. Then, the second passivation layer 30 of the metal is planarized, e.g. by CMP or etch back, and an opening 37 is formed in the second passivation layer 30 over the metal pad structure 35 by suitable photolithography and etching operations. In some embodiments, the top surface of the metal pad structure 35 is recessed by suitable photolithographic patterning and etching operations, as shown in FIG. 4B. In some embodiments, the sidewalls of the metal pad structure 35 are arranged in a substantially straight line along the Y direction.The structure of FIG. 4B is then processed in the manner described above with reference to FIGS. 1I through 1N to obtain the structure shown in FIG. 4C having a metal bump structure 55 with a reflowed hemispherical solder layer 60.FIGS. 5A-5G are cross-sectional views of stages of a sequential method of manufacturing a semiconductor device according to an embodiment of the disclosure. The structure in FIG. 5A is produced by the operations described herein with reference to FIGS. 1A-1L. After the first polyimide layer 40 ais formed, a second polyimide layer 40 bis formed over the first polyimide layer 40 a, as illustrated in FIG. 5B. The first polyimide layer 40 aincludes a first polyimide and the second polyimide layer 40 bincludes a second polyimide. Each of the first polyimide and the second polyimide is a reaction product of a dianhydride and a diamine, wherein at least one of the dianhydride and the diamine contains one selected from the group consisting of a cycloalkane, a fused ring, a bicycloalkane, a tricycloalkane, a bicycloalkene, a tricycloalkene, a spiroalkane, and a heterocyclic ring, and the first polyimide and the second polyimide are different from each other. The first polyimide layer 40 aand the second polyimide layer 40 bare formed from the materials and according to methods disclosed herein with reference to FIG. 1L.The first polyimide and the second polyimide are selected to achieve the desired modulus of elasticity in some embodiments. In some embodiments, the first polyimide layer 40 aand the second polyimide layer 40 bhave different elastic modulus, and the elastic modulus of the first polyimide layer and the second polyimide layer in combination is about 4.5 GPa to about 7 GPa. In some embodiments, the elastic modulus of the first polyimide layer and the second polyimide layer in combination is between greater than 5 GPa and about 7 GPa. In some embodiments, the elastic modulus of the first polyimide layer 40 ais greater than that of the second polyimide layer 40 b. In other embodiments, the elastic modulus of the second polyimide layer 40 bis greater than that of the first polyimide layer 40 a.In some embodiments, the first polyimide layer 40 ais formed by applying a polyamic acid composition over the passivation layer 30 and the metal pad structure 35 to form a first polyamic acid layer, and then converting the first polyamic acid layer to the first polyimide layer 40 aby heating the first polyamic acid layer to a temperature of about 150° C. to about 350° C. Then, the second polyimide layer 40 bis formed by applying a polyamic acid composition over the first polyimide layer 40 ato form a second polyamic acid layer, and then the second polyamic acid layer is converted to the second polyimide layer 40 bby heating the second polyamic acid layer to a temperature of about 150° C. to about 350° C. In other embodiments, the first polyamic acid layer is formed over the passivation layer 30 and the metal pad structure 35. The second polyamic acid layer is formed over the first polyamic acid layer, and then both polyamic acid layers are heated to a temperature of about 150° C. to about 350° C. to convert the first polyamic acid layer and the second polyamic acid layer to the first polyimide layer 40 aand the second polyimide layer 40 b. In some embodiments, the polyamic acid composition is mixed with a solvent and applied to the device structure by a coating operation such as spin coating. The polyamic acid layer is then heated to a temperature of about 40°C to about 120°C to dry the polyamic acid layer and remove excess solvent before the polyamic acid layer is converted to the polyimide layer.In some embodiments, the thickness of the first polyimide layer 40 aand the second polyimide layer 40 bis about 1 μm to about 9 μm, respectively, and the total thickness of the first polyimide layer 40 aand the second polyimide layer 40 bis about 2 μm to about 10 μm after the polyimide layers are cured.In some embodiments, an under bump metallization layer (seed layer) 45 is formed over the second polyimide layer 40 band the metal pad structure 35, as shown in FIG. 5C. In some embodiments, the under bump metallization layer 45 includes a double layer including a titanium-based layer and a copper-based layer. In some embodiments, the under bump metallization layer 45 has a thickness of about 50 nm to about 1 nm μm.Then, a photoresist layer 50 is formed over the under bump metallization layer 45 or the second polyimide layer 40b, as shown in FIG. 5D. The photoresist layer 50 is patterned by suitable photolithography operations to form an opening 53 in the photoresist layer over the metal pad pattern 35.As shown in FIG. 5E, a metal bump 55 is subsequently disposed over the metal pad structure 35 and the second polyimide layer 40 bor the under bump metallization layer 45, in a similar manner as described herein with reference to FIG. 1L. As shown in FIG. 5E, the metal bump 55 is formed in the photoresist opening 53 by depositing a metal, e.g., one or more metals selected from the group consisting of aluminum, copper, chromium, iron, manganese, magnesium, molybdenum, nickel, tin, niobium, tantalum, titanium, tungsten, zinc, and alloys thereof. A solder layer 60 is formed over the metal bump 55.Then, the photoresist layer 50 is removed by a suitable photoresist removing technique such as a solvent stripping or plasma ashing operation, as shown in Fig. 5F. In some embodiments, after the photoresist layer 50 is removed, the solder layer 60 is reflowed to form a smooth hemispherical shape, as shown in FIG. 5G and described with reference to FIG. 1N.In some embodiments, the polyimide layer 40, 40 ais adhered to the passivation layer 30 or the metal pad structure 35 by an adhesion promoter. The adhesion promoter is chemically bonded to the polyimide layer 40, 40 a, the passivation layer 30, and the metal pad structure 35. In some embodiments, the adhesion promoter is bonded to the polyimide layer 40, 40a through crosslinking groups on the adhesion promoter. In some embodiments, the utilizing groups are one or more selected from the group consisting of an alkyl oxide group, an alkene group, an alkyne group, and a triazine group. In some embodiments, the adhesion promoter is bonded to the passivation layer 30 through silanol groups on the adhesion promoter.FIG. 6A shows an adhesion promoter that improves the adhesion of the polyimide layer to substrates. One end A of the adhesion promoter adheres to the substrate (metal, passivation layer or dielectric layer), while the other end B of the adhesion promoter adheres to the polyimide layer. The two ends A, B of the adhesion promoter are connected to one another by a chain connecting group. In some embodiments, the chain linking group is a hydrocarbon chain.In some embodiments, the coupling agent contains a chelating group or a silanol group at one end A and a cross-linking group at the other end B. The chelating group contains one or more of N, O, S, or a halogen. In some embodiments, the adhesion promoter is attached to the metal pad structure 35 through the chelating group. In some embodiments, the adhesion promoter is bonded to the passivation layer 30 via the silanol group. In some embodiments, the adhesion promoter is bonded to the polyimide layer 40, 40a through the crosslinking group.In some embodiments, the chelating group is one or more of the following group: a thiol, a thiirane, a thiirene, a thietane, a thiolane, a thiophene, a thiane, a thiopyran, a thiepan, a thiepine, a 2,3-dihydrothiophene, a 2,5-dihydrothiophene, a hydroxy, a carboxyl, an oxirane, an oxirane, an oxetane, an oxolane, a furan, an oxan, a pyran, an oxepan, an oxepine, a 2,5-dihydrofuran, a 2,3-dihydrofuran, an amine, an aziridine, an azetidine, an azine, a pyrrolidine, a pyrrole, a piperidine, a pyridine, an azepine, an azepine, a 1-pyrroline, a 2-pyrroline, a 3-pyrroline, a dihydropyridine, a cyano group, a fluoro group, a chloro group, a bromo group and an iodo group. In some embodiments, the crosslinking group comprises an alkyl oxide, an alkene, an alkyne, or a triazine.Figure 6B shows the adhesion promoter without a capping solvent. The silanol groups on the adhesion promoter are not stable. Without the capping solvent, the silanol groups on the adhesion promoter react with each other to form a silica gel. FIG. 6C shows a solution of the adhesion promoter and a capping solvent (first solvent) according to embodiments of the disclosure. The capping solvent solvates the silanol groups to keep the adhesion promoter in solution until the silanol groups on the adhesion promoter react with the silanol groups on the passivation layer 30 to bond the adhesion promoter to the passivation layer 30.In some embodiments, the capping solvent (first solvent) is one or more selected from the following group: 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, pentan-2-ol, 3-methylbutan-1-ol, 3-methylbutan-2-ol, 2-methylbutan-1-ol, 2,2-dimethylpropan-1-ol, pentan-3-ol, pentan-2-ol, 3-methylbutan-2-ol, 2-methylbutan-2-ol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, ethylene glycol, diethylene glycol, glycerol, 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-isopropoxyethanol, 2-butoxyethanol, 2-phenoxyethanol, 2-benzoyloxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-propoxy-2-propanol, methyl carbitol, carbitol cellosolve, butyl carbitol, dipropylene glycol methyl ether, tripropylene glycol methyl ether, and a crown ether selected from the group consisting of 12-crown-4, 15-crown-5, 18-crown-6, dibenzo-18-crown-6, and dibenzo-18-crown-6, and combinations thereof. In some embodiments, the polyamic acid composition contains up to 30 wt % of the first solvent relative to the total weight of the polyamic acid composition. In some embodiments, the polyamic acid composition includes a second solvent of one or more selected from the group consisting of N-methyl-2-pyrrolidone, gamma-butyrolactone, and propylene glycol methyl ether acetate. In some embodiments, the concentration of capping solvent in the polyamic acid composition is up to 30 wt % relative to the total weight of the polyamic acid composition.An embodiment of the disclosure includes a method 700 of manufacturing a semiconductor device as shown in the flow chart of FIG. 7. A dielectric layer 15, such as an interlayer dielectric layer (ILD), is formed over a substrate 10 in operation S 705 (see FIG. 1A ). In some embodiments, the substrate 10 includes a semiconductor device 5 disposed over a semiconductor wafer. In some embodiments, the semiconductor device 5 includes one or more of transistors, capacitors, inductors, resistors, diodes, integrated circuits, and related wirings and interconnections embedded in an insulating layer.In operation S 710 an opening or trench 17 is formed in the dielectric layer 15 by suitable photolithography and etching operations, as shown in FIG. 1B. The opening 17 is disposed in the substrate via electrical contacts on the semiconductor device 5, in some embodiments. Next, in operation S 715, the opening 17 is then filled with an electrically conductive material, e.g. a metal, to form a metal contact 20 (see FIG. 1C ). In some embodiments, a planarization operation is performed after depositing the metal to remove metal overlying the top surface of the dielectric layer 15.Subsequently, in operation S 720, a passivation layer 25 is formed over the dielectric layer 15 and the metal contact 20 (see FIG. 1D ). In some embodiments, the passivation layer 25 is a first passivation layer and a second or additional passivation layer 30 is formed over the first passivation layer 25 in operation S 422 (see FIG. 1E ). In some embodiments, the first passivation layer 25 and the second passivation layer 30 are formed of materials different from each other. The first passivation layer 25 and the second passivation layer 30 may be an oxide layer such as a silicon oxide or a nitride layer such as a silicon nitride. In some embodiments, the first passivation layer 25 or the second passivation layer 30 is an extreme low-k (ELK) material.In operation S 730, an opening 33 is formed by appropriate photolithography and etching operations in the passivation layer(s) exposing the metal contact 20 (see FIG. 1F ). Then, a metal pad structure 35 is formed by forming a metal layer over the opening 33 and the passivation layer 30 in operation S 730 (see FIG. 1G ). In some embodiments, the metal pad structure 35 includes aluminum, copper, silver, gold, nickel, tungsten, titanium, tin, titanium nitride, hafnium, tin, ruthenium, tantalum, tantalum nitride, alloys thereof, or multilayers thereof. In some embodiments, the metal pad is an AlCu alloy. In some embodiments, portions of the metal layer overlying the second passivation layer 30 are removed by suitable photolithography and etching operations to form the metal pad structure 35.After the formation of the metal pad structure 35, the deposition of the second passivation layer 30 is continued in operation S 740 such that the second passivation 30 covers the top surface of the metal pad structure 35. The metallic second passivation layer 30 is planarized, e.g., by CMP or etchback, and an opening 37 is formed in the second passivation layer 30 over the metal pad structure 35 by suitable photolithography and etching operations in operation S 745 (see FIG. 1H ).Then, in operation S 750, a polyimide layer 40 including a polyimide is formed over the second passivation layer 30 and the metal pad structure 35. The polyimide layer 40 is patterned so that the surface of the metal pad pattern 35 is exposed through an opening 37' (see FIG. 1L ). In some embodiments, the polyimide layer 40 is formed by forming a polyamic acid composition containing a polyamic acid over the device and then converting the polyamic acid to a polyimide by heating the polyamic acid to a temperature of about 150° C. to about 350° C. The polyamic acid is a reaction product of any of the dianhydrides and diamines disclosed herein with reference to Figure 1L. In some embodiments, the polyimide layer is a first polyimide layer 40 aand a second polyimide layer 40 bis formed over the first polyimide layer 40 ain operation S755 (see FIG. 5B ). The second polyimide layer 40 bis formed of one of the polyamic acid compositions disclosed with reference to FIG. 1L, and the second polyimide layer 40 bis formed of a different polyimide than the first polyimide layer 40 a. After the formation of the polyimide layers 40, 40a, 40b, an opening 37' is formed in the polyimide layers in operation S760.In some embodiments, in operation S 765, an under bump metallization layer (seed layer) 45 is formed over the polyimide layer 40, 40 band the metal pad structure 35 (see FIGS. 1J and 5C ). In some embodiments, the under bump metallization layer 45 includes a double layer including a titanium-based layer and a copper-based layer.In operation S 770, a photoresist layer 50 is formed over the under bump metallization layer 45 or the polyimide layer 40, 40 b(see FIGS. 1K and 5D ). The photoresist layer 50 is patterned by suitable photolithographic operations to form an opening 53 in the photoresist layer over the metal pad structure 35. Next, in operation S 780, a metal bump 55 is disposed over the metal pad structure 35 and the polyimide layer 40, 40 b. In some embodiments, the metal bump 55 is formed by electroplating (electroplating), physical vapor deposition, chemical vapor deposition, or evaporative deposition. Then, in operation S 785, a solder layer 60 is formed over the metal bump (see FIGS. 1L and 5E ).Next, in operation S790, the photoresist layer 50 (see FIGS. 1M and 5F ) is removed by a suitable photoresist removal technique, such as a solvent stripping operation or a plasma ashing operation. In some embodiments, after the removal of the photoresist layer 50, the solder layer 60 is reflowed in operation S795 (see FIGS. 1N and 5G ).Additional operations S 800 are performed on the structures of FIGS. 1N, 4C, and 5G. In some embodiments, the additional operations include sawing the substrate to separate multiple structures formed on the substrate into individual dies and then packaging (packaging) the individual dies. In some embodiments, in operation S 805, the dies are attached through the bump structures to a substrate that carries a chip. In some embodiments, the dies are attached by a flip chip bonding operation. In some embodiments, the chip-carrying substrate is a printed circuit board or interposer.After attaching the dies to a carrier substrate, an underfill material is applied to the area between the bottom side of the die and the carrier substrate in operation S 810. The underfill material protects and isolates the bonded bump structures. The underfill material further improves the adhesion of the die to the supporting substrate.In some embodiments, one or more additional components, such as a heat spreader, are applied to the main surface of the die that is opposite the surface of the die that faces the carrier substrate. In operation S 818, the device for protection and insulation is included in a molding compound such as an epoxy resin. In some embodiments, after each of the operations disclosed herein, inspection or electrical testing of the device is performed to ensure the quality and functionality of the device.In some embodiments of the disclosure, the elastic modulus of the polyimide layer of a bump structure is increased to about 4.5 GPa to about 7 GPa. Embodiments of the disclosure that include polyimide layers having the elastic modulus in the disclosed range prevent delamination of the polyimide layer from an underlying passivation layer and thereby prevent damage to the underlying passivation layer. Embodiments of the disclosure provide improved protection of the underlying extreme low-k (ELK) passivation layers. Devices with bump structures according to the present disclosure avoid delamination even when subjected to more than 100 times of pressure during stress testing.An embodiment of the disclosure is a method of forming a bump structure including forming a passivation layer over a substrate. A metal pad structure is formed over the substrate, wherein the passivation layer surrounds the metal pad structure. A polyimide layer containing a polyimide is formed over the passivation layer and the metal pad structure. A metal bump is formed over the metal pad structure and the polyimide layer. The polyimide is a reaction product of a dianhydride and a diamine, wherein at least one of the dianhydride and the diamine contains one selected from the group consisting of a cycloalkane, a fused ring, a bicycloalkane, a tricycloalkane, a bicycloalkene, a tricycloalkene, a spiroalkane, and a heterocyclic ring. In one embodiment, at least one of dianhydride and diamine contains a tricycloalkane or tricycloalkene. In one embodiment, at least one of dianhydride and diamine contains two or more cyclic groups. In one embodiment, the two or more cyclic groups are linked together by a linking group selected from the group consisting of -CH2-, -CH=CH-, -C≡C-, -O-, -C(O)O-, -CF3CH2CF3-, -CH3CH2CH3-, -SH-, and -SO2-. In one embodiment, at least one of dianhydride and diamine contains a cycloalkane selected from the group consisting of cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane and cyclooctane. In one embodiment, at least one of dianhydride and diamine contains a fused ring selected from the group consisting of naphthalene, anthracene, phenanthrene, chrysene, pyrene, coranulen, coronene, hexhelicene, indole, isoindole, indolizine, quinoline, isoquinoline, purine, carbazole, dibenzofuran, xanthene, phenazine, phenoxazine, and phenoxathiine. In an embodiment, forming the passivation layer includes: forming a first passivation layer over the substrate; and forming a second passivation layer over the first passivation layer, wherein the first passivation layer and the second passivation layer are made of materials different from each other. @In an embodiment, forming the polyimide layer includes: forming a first polyimide layer including a first polyimide over the passivation layer; and forming a second polyimide layer containing a second polyimide, wherein each of the first polyimide and the second polyimide is a reaction product of a dianhydride and a diamine, wherein at least one of the dianhydride and the diamine contains one selected from the group consisting of a cycloalkane, a fused ring, a bicycloalkane, a tricycloalkane, a bicycloalkene, a tricycloalkene, a spiroalkane, and a heterocyclic ring, and the first polyimide and the second polyimide are different from each other. In one embodiment, at least one of dianhydride and diamine contains Bicyclo[3.2.0]heptan. In one embodiment, one of dianhydride and diamine contains adamantane. In one embodiment, at least one of dianhydride and diamine contains spiro[2.2.2]pentane. In one embodiment, at least one of dianhydride and diamine contains a heterocyclic ring selected from the group consisting of thiolane, oxolane and pyrrole. In one embodiment, the dianhydride is selected from the group consisting of cyclobutanetetracarboxylic dianhydride, 4,4'-biphthalic anhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 5,5'-(9H-fluorene-9,9-diyl)bis(2-benzofuran-1,3-dione, 2,3,6,7-naphthalenetetracarboxylic 2,3:6,7-dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride and 4,4'-(ethyne-1,2-diyl)diphthalic anhydride. In one embodiment, the diamine is selected from the group consisting of Bis(aminoethyl)norbornan 2,6-diaminoanthraquinone, 1,5-diaminonaphthalene, 4,4"-diamino-p-terphenyl, 9,9-bis(4-aminophenyl)fluorene, 2,7-diaminofluorene, 2,6-diaminopyridine and 3,6-diaminocarbazole. In one embodiment, the metal bump is formed from a metal selected from the group consisting of aluminum, copper, chromium, iron, manganese, magnesium, molybdenum, nickel, tin, niobium, tantalum, titanium, tungsten, zinc, and alloys thereof. In an embodiment, the method includes forming a solder layer over the metal bump. In one embodiment, the solder layer contains a tin-containing alloy selected from the following group: PbSn, AgSn, SnAgCu, CuSnNi, AgCuSnSn, AuSn and CuSn. In an embodiment, the first passivation layer includes a silicon oxide or a silicon nitride. In an embodiment, the second passivation layer includes a silicon oxide or a silicon nitride. In one embodiment, the polyimide layer has an elastic modulus of 4.5 GPa to 7 GPa. In an embodiment, forming the polyimide layer includes heating a polyamic acid layer at a temperature of 150° C. to 350° C. The second passivation layer includes a silicon oxide or a silicon nitride. In an embodiment, the method includes patterning the polyimide layer to expose the metal pad structure before forming the metal bump. In an embodiment, the metal pad structure includes aluminum, copper, silver, gold, nickel, tungsten, titanium, tin, titanium nitride, hafnium, ruthenium, tantalum, tantalum nitride, alloys thereof, or multiple layers thereof. In an embodiment, the method includes forming an under bump metallization layer over the metal pad structure and the polyimide layer before forming the metal bump. In an embodiment, the under bump metallization layer comprises a double layer with a titanium-based layer and a copper-based layer. In one embodiment, the titanium-based layer contains titanium, titanium alloys, and titanium compounds containing 50 mol % or more of titanium, and the copper-based layer contains copper, copper alloys, and copper compounds containing 50 mol % or more of copper. In an embodiment, the method includes forming a photoresist layer over the passivation layer or the under bump metallization layer and patterning the photoresist layer to form an opening in the photoresist layer over the metal pad structure prior to forming the metal bump. In an embodiment, forming the metal bump includes forming a metal layer over the metal pad structure in the opening in the photoresist layer and removing the photoresist layer. In one embodiment, the method includes forming a solder layer over the metal layer prior to removing the photoresist layer. In an embodiment, the method includes removing exposed portions of the under bump metallization layer after removing the photoresist layer. In one embodiment, the method includes reflowing the solder layer to form a solder bump.Another embodiment of the disclosure is a method of forming a bump structure, including forming a passivation layer over a substrate. A metal pad structure is formed over the substrate, wherein the passivation layer surrounds the metal pad structure. A polyimide layer including a polyimide is formed over the passivation layer and the metal pad structure, and a metal bump is formed over the metal pad structure and the polyimide layer. The metal bump is in electrical contact with the metal pad structure and the polyimide layer is bonded to the passivation layer and the metal pad structure by a bonding agent, the bonding agent being chemically bonded to the polyimide, the passivation layer, and the metal pad structure. In one embodiment, forming the polyimide layer comprises combining polyamic acid, adhesion promoter, and a first solvent to form a polyamic acid composition; applying the polyamic acid composition to the passivation layer and the metal pad structure; and heating the polyamic acid composition to a temperature of 150° C. to 350° C. to convert the polyamic acid to the polyimide. In one embodiment, the polyamic acid is a reaction product of a dianhydride and a diamine wherein at least one of the dianhydride and diamine contains one selected from the group consisting of a cycloalkane, a fused ring, a bicycloalkane, a tricycloalkane, a bicycloalkene, a tricycloalkene, a spiroalkane, and a heterocyclic ring. In one embodiment, the adhesion promoter comprises a chelating group, a silanol group, and a crosslinking group. In one embodiment, the chelating group contains at least one of N, O, S, or a halogen. In one embodiment, the chelating group includes at least one of a thiol, a thiirane, a thiirane, a thietane, a thiolane, a thiophene, a thiane, a thiopyran, a thieane, a thiepine, a 2,3-dihydrothiophene, a 2,5-dihydrothiophene, a hydroxy, a carboxyl, an oxirane, an oxirene, an oxetane, an oxolane, a furan, an oxan, a pyran, an oxepan, an oxepine, a 2,5-dihydrofuran, a 2,3-dihydrofuran, an amine, an aziridine, an azetidine, an acetate, a pyrrolidine, a pyrrole, a piperidine, a pyridine, an azepine, an azepine, a 1-pyrroline, a 2-pyrroline, a 3-pyrroline, a dihydropyridine, a cyano group, a fluoro group, a chloro group, a bromo group or an iodo group. In one embodiment, the crosslinking group contains an alkyl oxide, an alkene, an alkyne or a triazine. In one embodiment, the first solvent is at least one of the following: 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, pentan-2-ol, 3-methylbutan-1-ol, 3-methylbutan-2-ol, 2-methylbutan-1-ol, 2,2-dimethylpropan-1-ol, pentan-3-ol, pentan-2-ol, 3-methylbutan-2-ol, 2-methylbutan-2-ol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, ethylene glycol, diethylene glycol, glycerol, 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-isopropoxyethanol, 2-butoxyethanol, 2-phenoxyethanol, 2-benzoyloxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-propoxy-2-propanol, Methyl carbitol, carbitol cellosolve, butyl carbitol, dipropylene glycol methyl ether, tripropylene glycol methyl ether, or a crown ether selected from the group consisting of 12-crown-4, 15-crown-5, 18-crown-6, dibenzo-18-crown-6, dibenzo-18-crown-6, and combinations thereof. In one embodiment, the polyamic acid composition contains up to 30 wt % of the first solvent relative to the total weight of the polyamic acid composition. In one embodiment, the polyamic acid composition contains a second solvent and the second solvent is at least one of N-methyl-2-pyrrolidone, gamma-butyrolactone, or propylene glycol methyl ether acetate. In one embodiment, the polyamic acid is a reaction product of a dianhydride and a diamine, and at least one of the dianhydride and diamine contains a cycloalkane, a fused ring, a bicycloalkane, a tricycloalkane, a bicycloalkene, a tricycloalkene, a spiroalkane, or a heterocyclic ring. In one embodiment, at least one of dianhydride and diamine contains a tricycloalkane or tricycloalkene. In one embodiment, at least one of dianhydride and diamine contains two or more cyclic groups. In one embodiment, the two or more cyclic groups are linked together by a linking group selected from the group consisting of -CH2-, -CH=CH-, -C≡C-, -O-, -C(O)O-, -CF3CH2CF3-, -CH3CH2CH3-, -SH-, and -SO2-. In one embodiment, at least one of dianhydride and diamine contains a cycloalkane, and the cycloalkane is selected from the group consisting of cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane. In one embodiment, at least one of dianhydride and diamine contains a fused ring and the fused ring is selected from the group consisting of naphthalene, anthracene, phenanthrene, chrysene, pyrene, coranulen, coronene, hexhelicene, indole, isoindole, indolizine, quinoline, isoquinoline, purine, carbazole, dibenzofuran, xanthene, phenazine, phenoxazine, and phenoxathiine. In one embodiment, at least one of dianhydride and diamine is Bicyclo[3.2.0]heptan. In one embodiment, at least one of dianhydride and diamine is adamantane. In one embodiment, at least one of dianhydride and diamine is spiro[2.2.2]pentane. In one embodiment, at least one of dianhydride and diamine is a heterocyclic ring selected from the group consisting of thiolane, oxolane and pyrrole. In one embodiment, the dianhydride is selected from the group consisting of cyclobutanetetracarboxylic dianhydride, 4,4'-biphthalic anhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 5,5'-(9H-fluorene-9,9-diyl)bis(2-benzofuran-1,3-dione, 2,3,6,7-naphthalenetetracarboxylic 2,3:6,7-dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride and 4,4'-(ethyne-1,2-diyl)diphthalic anhydride. In one embodiment, the diamine is selected from the group consisting of Bis(aminoethyl)norbornan 2,6-diaminoanthraquinone, 1,5-diaminonaphthalene, 4,4"-diamino-p-terphenyl, 9,9-bis(4-aminophenyl) fluorene, 2,7-diamino fluorene, 2,6-diaminopyridine and 3,6-diaminocarbazole. In one embodiment, the metal bump is formed from a metal selected from the group consisting of aluminum, copper, chromium, iron, manganese, magnesium, molybdenum, nickel, tin, niobium, tantalum, titanium, tungsten, zinc, and alloys thereof. In an embodiment, the method includes forming a solder layer over the metal bump. In one embodiment, the solder layer contains a tin-containing alloy selected from the following group: PbSn, AgSn, SnAgCu, CuSnNi, AgCuSnSn, AuSn and CuSn. In an embodiment, forming the passivation layer includes: forming a first passivation layer over the substrate; and forming a second passivation layer over the first passivation layer, wherein the first passivation layer and the second passivation layer are formed of materials different from each other. In an embodiment, the first passivation layer includes a silicon oxide or a silicon nitride. In an embodiment, the second passivation layer includes a silicon oxide or a silicon nitride. In one embodiment, the polyimide layer has an elastic modulus of 4.5 GPa to 7 GPa. In one embodiment, forming the polyimide layer comprises: forming a first polyimide layer containing a first polyimide over the passivation layer; and forming a second polyimide layer containing a second polyimide over the first polyimide layer, wherein each of the first polyimide and the second polyimide is a reaction product of a dianhydride and a diamine, wherein at least one of the dianhydride and the diamine contains one selected from the group consisting of a cycloalkane, a fused ring, a bicycloalkane, a tricycloalkane, a bicycloalkene, a tricycloalkene, a spiroalkane, and a heterocyclic ring, and the first polyimide and the second polyimide are different from each other. In an embodiment, the method includes patterning the polyimide layer to expose the metal pad structure before forming the metal bump. In an embodiment, the metal pad structure includes aluminum, copper, silver, gold, nickel, tungsten, titanium, tin, titanium nitride, hafnium, ruthenium, tantalum, tantalum nitride, alloys thereof, or multilayers thereof. In an embodiment, the method includes forming an under bump metallization layer over the metal pad structure and the polyimide layer before forming the metal bump. In an embodiment, the under bump metallization layer comprises a double layer with a titanium-based layer and a copper-based layer. In one embodiment, the titanium-based layer contains titanium, titanium alloys, and titanium compounds containing 50 mol % or more of titanium, and the copper-based layer contains copper, copper alloys, and copper compounds containing 50 mol % or more of copper. In an embodiment, the method includes forming a photoresist layer over the passivation layer or the under bump metallization layer and patterning the photoresist layer to form an opening in the photoresist layer over the metal pad structure before forming the metal bump. In an embodiment, forming the metal bump includes forming a metal layer over the metal pad structure in the opening in the photoresist layer and removing the photoresist layer. In one embodiment, the method includes forming a solder layer over the metal layer prior to removing the photoresist layer. In an embodiment, the method includes removing exposed portions of the under bump metallization layer after removing the photoresist layer. In one embodiment, the method includes reflowing the solder layer to form a solder bump.Another embodiment of the disclosure is a bump structure including: a passivation layer surrounding a metal pad; and a polyimide layer including a polyimide disposed over the passivation layer and the metal pad. A metal bump is disposed over the metal pad and the polyimide layer. The metal bump is in electrical contact with the metal pad, and the polyimide is a reaction product of a dianhydride and a diamine, wherein at least one of the dianhydride and diamine contains one selected from the group consisting of a cycloalkane, a fused ring, a bicycloalkane, a tricycloalkane, a bicycloalkene, a tricycloalkene, a spiroalkane, and a heterocyclic ring. In one embodiment, at least one of dianhydride and diamine contains a tricycloalkane or tricycloalkene. In one embodiment, at least one of dianhydride and diamine contains two or more cyclic groups. In one embodiment, the two or more cyclic groups are linked together by a linking group selected from the group consisting of -CH2-, -CH=CH-, -C≡C-, -O-, -C(O)O-, -CF3CH2CF3-, -CH3CH2CH3-, -SH-, and -SO2-. In one embodiment, at least one of dianhydride and diamine contains a cycloalkane selected from the group consisting of cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane and cyclooctane. In one embodiment, at least one of dianhydride and diamine contains a fused ring selected from the group consisting of naphthalene, anthracene, phenanthrene, chrysene, pyrene, coranulen, coronene, hexhelicene, indole, isoindole, indolizine, quinoline, isoquinoline, purine, carbazole, dibenzofuran, xanthene, phenazine, phenoxazine, and phenoxathiine. In one embodiment, at least one of dianhydride and diamine is Bicyclo[3.2.0]heptan. In one embodiment, at least one of dianhydride and diamine is adamantane. In one embodiment, at least one of dianhydride and diamine is spiro[2.2.2]pentane. In one embodiment, at least one of dianhydride and diamine is a heterocyclic ring selected from the group consisting of thiolane, oxolane and pyrrole. In one embodiment, the dianhydride is selected from the group consisting of cyclobutanetetracarboxylic dianhydride, 4,4'-biphthalic anhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 5,5'-(9H-fluorene-9,9-diyl)bis(2-benzofuran-1,3-dione, 2,3,6,7-naphthalenetetracarboxylic 2,3:6,7-dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride and 4,4'-(ethyne-1,2-diyl)diphthalic anhydride. In one embodiment, the diamine is selected from the group consisting of Bis(aminoethyl)norbornan 2,6-diaminoanthraquinone, 1,5-diaminonaphthalene, 4,4"-diamino-p-terphenyl, 9,9-bis(4-aminophenyl)fluorene, 2,7-diaminofluorene, 2,6-diaminopyridine and 3,6-diaminocarbazole. In an embodiment, the metal bump is formed of a metal selected from the group consisting of aluminum, copper, chromium, iron, manganese, magnesium, molybdenum, nickel, tin, niobium, tantalum, titanium, tungsten, zinc, and alloys thereof. In an embodiment, the bump structure includes a solder layer disposed over the metal bump. In one embodiment, the solder layer contains a tin-containing alloy selected from the following group: PbSn, AgSn, SnAgCu, CuSnNi, AgCuSnSn, AuSn and CuSn. In an embodiment, the passivation layer includes a first passivation layer and a second passivation layer, and the first passivation layer and the second passivation layer are formed of materials different from each other. In an embodiment, the first passivation layer includes a silicon oxide or a silicon nitride. In an embodiment, the second passivation layer includes a silicon oxide or a silicon nitride. In one embodiment, the polyimide layer has an elastic modulus of 4.5 GPa to 7 GPa. In one embodiment, the polyimide layer includes a first polyimide layer containing a first polyimide and a second polyimide layer disposed over the first polyimide layer and containing a second polyimide, wherein the first polyimide and the second polyimide are each a reaction product of a dianhydride and a diamine, wherein at least one of the dianhydride and the diamine contains one selected from the group consisting of a cycloalkane, a fused ring, a bicycloalkane, a tricycloalkane, a bicycloalkene, a tricycloalkene, a spiroalkane, and a heterocyclic ring, and the first polyimide and the second polyimide are different from each other. In an embodiment, the metal pad includes aluminum, copper, silver, gold, nickel, tungsten, titanium, tin, titanium nitride, hafnium, ruthenium, tantalum, tantalum nitride, alloys thereof, or multilayers thereof. In an embodiment, the bump structure includes an under bump metallization layer disposed between the metal bump and the metal pad. In an embodiment, the under bump metallization layer comprises a double layer with a titanium-based layer and a copper-based layer. In one embodiment, the titanium-based layer contains titanium, titanium alloys, and titanium compounds containing 50 mol % or more of titanium, and the copper-based layer contains copper, copper alloys, and copper compounds containing 50 mol % or more of copper.Another embodiment of the disclosure is a bump structure including a passivation layer surrounding a metal pad structure. A polyimide layer containing a polyimide is disposed over the passivation layer and the metal pad structure. A metal bump is disposed over the metal pad structure and the polyimide layer, the metal bump being in electrical contact with the metal pad structure. The polyimide layer is bonded to the passivation layer and the metal pad structure by a coupling agent, wherein the coupling agent is chemically bonded to the polyimide, the passivation layer and the metal pad structure. In one embodiment, the adhesion promoter is bonded to the polyimide through crosslinking groups on the adhesion promoter. In one embodiment, the crosslinking groups are one or more selected from the group consisting of an alkyl oxide group, an alkene group, an alkyne group and a triazine group. In one embodiment, the adhesion promoter is bonded to the passivation layer by silanol groups on the adhesion promoter. In one embodiment, the adhesion promoter is bonded to the metal pad structure. In one embodiment, the polyimide is a reaction product of a dianhydride and a diamine, wherein at least one of the dianhydride and diamine contains one selected from the group consisting of a cycloalkane, a fused ring, a bicycloalkane, a tricycloalkane, a bicycloalkene, a tricycloalkene, a spiroalkane, and a heterocyclic ring. In one embodiment, at least one of dianhydride and diamine contains a tricycloalkane or tricycloalkene. In one embodiment, at least one of dianhydride and diamine contains two or more cyclic groups. In one embodiment, the two or more cyclic groups are linked together by a linking group selected from the group consisting of -CH2-, -CH=CH, -C≡C-, -O-, -C(O)O-, -CF3CH2CF3-, -CH3CH2CH3-, -SH-, and -SO2-. In one embodiment, at least one of dianhydride and diamine is a cycloalkane selected from the group consisting of cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane and cyclooctane. In one embodiment, at least one of dianhydride and diamine is a fused ring selected from the group consisting of naphthalene, anthracene, phenanthrene, chrysene, pyrene, coranulen, coronene, hexhelicene, indole, isoindole, indolizine, quinoline, isoquinoline, purine, carbazole, dibenzofuran, xanthene, phenazine, phenoxazine, and phenoxathiine. In one embodiment, at least one of dianhydride and diamine is Bicyclo[3.2.0]heptan. In one embodiment, at least one of dianhydride and diamine is adamantane. In one embodiment, at least one of dianhydride and diamine is spiro[2.2.2]pentane. In one embodiment, at least one of dianhydride and diamine is a heterocyclic ring selected from the group consisting of thiolane, oxolane and pyrrole. In one embodiment, the dianhydride is selected from the group consisting of cyclobutanetetracarboxylic dianhydride, 4,4'-biphthalic anhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 5,5'-(9H-fluorene-9,9-diyl)bis(2-benzofuran-1,3-dione, 2,3,6,7-naphthalenetetracarboxylic 2,3:6,7-dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride and 4,4'-(ethyne-1,2-diyl)diphthalic anhydride. In one embodiment, the diamine is selected from the group consisting of Bis(aminoethyl)norbornan 2,6-diaminoanthraquinone, 1,5-diaminonaphthalene, 4,4"-diamino-p-terphenyl, 9,9-bis(4-aminophenyl)fluorene, 2,7-diaminofluorene, 2,6-diaminopyridine and 3,6-diaminocarbazole. In an embodiment, the metal bump is formed of a metal selected from the group consisting of aluminum, copper, chromium, iron, manganese, magnesium, molybdenum, nickel, tin, niobium, tantalum, titanium, tungsten, zinc, and alloys thereof. In an embodiment, the bump structure includes a solder layer disposed over the metal bump. In one embodiment, the solder layer contains a tin-containing alloy selected from the following group: PbSn, AgSn, SnAgCu, CuSnNi, AgCuSnSn, AuSn and CuSn. In an embodiment, the passivation layer comprises a first passivation layer and a second passivation layer, wherein the first passivation layer and the second passivation layer are formed from materials different from one another. In an embodiment, the first passivation layer includes a silicon oxide or a silicon nitride. In an embodiment, the second passivation layer includes a silicon oxide or a silicon nitride. In one embodiment, the polyimide layer has an elastic modulus of 4.5 GPa to 7 GPa. In one embodiment, the polyimide layer includes a first polyimide layer containing a first polyimide and a second polyimide layer disposed over the first polyimide layer and containing a second polyimide, wherein the first polyimide and the second polyimide are each a reaction product of a dianhydride and a diamine, wherein at least one of the dianhydride and the diamine contains one selected from the group consisting of a cycloalkane, a fused ring, a bicycloalkane, a tricycloalkane, a bicycloalkene, a tricycloalkene, a spiroalkane, and a heterocyclic ring, and the first polyimide and the second polyimide are different from each other. In an embodiment, the metal pad structure is formed of aluminum, copper, silver, gold, nickel, tungsten, titanium, tin, titanium nitride, hafnium, ruthenium, tantalum, tantalum nitride, alloys thereof, or multilayers thereof. In an embodiment, the metal pad structure includes a metal contact pad and a metallization layer disposed under the bump disposed over the metal contact pad. In an embodiment, the metallization layer under the bump comprises a double layer of a titanium-based layer and a copper-based layer. In one embodiment, the titanium-based layer includes titanium, titanium alloys, and titanium compounds containing 50 mol % or more of titanium, and the copper-based layer includes copper, copper alloys, and copper compounds containing 50 mol % or more of copper.Another embodiment of the disclosure is a polyamic acid composition containing a polyamic acid, a coupling agent, and a first solvent. The coupling agent contains a chelating group, a silanol group, and a cross-linking group, wherein the chelating group contains one or more of N, O, S, and a halogen. In one embodiment, the chelating group is one or more of the following: a thiol, a thiirane, a thiirene, a thietane, a thiolane, a thiophene, a thiane, a thiopyran, a thiepan, a thiepine, a 2,3-dihydrothiophene, a 2,5-dihydrothiophene, a hydroxy, a carboxyl, an oxirane, an oxirene, an oxetane, an oxolane, a furan, an oxan, a pyran, an oxepan, an oxepine, a 2,5-dihydrofuran, a 2,3-dihydrofuran, an amine, an aziridine, an azetidine, an acetate, a pyrrolidine, a pyrrole, a piperidine, a pyridine, an azepine, an azepine, a 1-pyrroline, a 2-pyrroline, a 3-pyrroline, a dihydropyridine, a cyano group, a fluoro group, a chloro group, a bromo group or an iodo group. In one embodiment, the crosslinking group comprises an alkyl oxide, an alkene, an alkyne or a triazine. In one embodiment, the first solvent is one or more of the following: 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, pentan-2-ol, 3-methylbutan-1-ol, 3-methylbutan-2-ol, 2-methylbutan-1-ol, 2,2-dimethylpropan-1-ol, pentan-3-ol, pentan-2-ol, 3-methylbutan-2-ol, 2-methylbutan-2-ol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, ethylene glycol, diethylene glycol, glycerol, 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-isopropoxyethanol, 2-butoxyethanol, 2-phenoxyethanol, 2-benzoyloxyethanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-propoxy-2-propanol, Methyl carbitol, carbitol cellosolve, butyl carbitol, dipropylene glycol methyl ether, tripropylene glycol methyl ether or a crown ether selected from the group consisting of 12-crown-4, 15-crown-5, 18-crown-6, dibenzo-18-crown-6 and dibenzo-18-crown-6. In one embodiment, the polyamic acid composition contains up to 30 wt% of the first solvent based on the weight of the polyamic acid composition. In one embodiment, the polyamic acid composition contains a second solvent selected from one or more of N-methyl-2-pyrrolidone, gamma-butyrolactone, or propylene glycol methyl ether acetate. In one embodiment, the polyamic acid is a reaction product of a dianhydride and a diamine wherein at least one of the dianhydride and diamine contains one selected from the group consisting of a cycloalkane, a fused ring, a bicycloalkane, a tricycloalkane, a bicycloalkene, a tricycloalkene, a spiroalkane, and a heterocyclic ring. In one embodiment, at least one of dianhydride and diamine contains a tricycloalkane or tricycloalkene. In one embodiment, at least one of dianhydride and diamine contains two or more cyclic groups. In one embodiment, the two or more cyclic groups are linked together by a linking group selected from the group consisting of -CH2-, -CH=CH-, -C≡C-, -O-, -C(O)O-, -CF3CH2CF3-, -CH3CH2CH3-, -SH-, and -SO2-. In one embodiment, at least one of dianhydride and diamine is a cycloalkane selected from the group consisting of cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane and cyclooctane. In one embodiment, at least one of dianhydride and diamine is a fused ring selected from the group consisting of naphthalene, anthracene, phenanthrene, chrysene, pyrene, coranulen, coronene, hexhelicene, indole, isoindole, indolizine, quinoline, isoquinoline, purine, carbazole, dibenzofuran, xanthene, phenazine, phenoxazine, and phenoxathiine. In one embodiment, at least one of dianhydride and diamine is Bicyclo[3.2.0]heptan. In one embodiment, at least one of dianhydride and diamine is adamantane. In one embodiment, at least one of dianhydride and diamine is spiro[2.2.2]pentane. In one embodiment, at least one of dianhydride and diamine is a heterocyclic ring selected from the group consisting of thiolane, oxolane and pyrrole. In one embodiment, the dianhydride is selected from the group consisting of cyclobutanetetracarboxylic dianhydride, 4,4'-biphthalic anhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 5,5'-(9H-fluorene-9,9-diyl)bis(2-benzofuran-1,3-dione, 2,3,6,7-naphthalenetetracarboxylic 2,3:6,7-dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride and 4,4'-(ethyne-1,2-diyl)diphthalic anhydride. In one embodiment, the diamine is selected from the group consisting of Bis(aminoethyl)norbornan 2,6-diaminoanthraquinone, 1,5-diaminonaphthalene, 4,4"-diamino-p-terphenyl, 9,9-bis(4-aminophenyl)fluorene, 2,7-diaminofluorene, 2,6-diaminopyridine and 3,6-diaminocarbazole.Another embodiment is a method of manufacturing a semiconductor device, the method comprising: forming a first passivation layer over a substrate and forming an opening in the first passivation layer. A metal pad structure is formed in the opening. A second passivation layer is formed over the metal pad structure. The first passivation layer and the second passivation layer are formed of materials different from each other. An opening is formed in the second passivation layer over the metal pad structure exposing a portion of the metal pad structure. A polyimide layer containing a polyimide is formed over the second passivation layer and the metal pad structure. A metal bump is formed over the metal pad structure and the polyimide layer. The polyimide is a reaction product of a dianhydride and a diamine, wherein at least one of the dianhydride and the diamine contains one selected from the group consisting of a cycloalkane, a fused ring, a bicycloalkane, a tricycloalkane, a bicycloalkene, a tricycloalkene, a spiroalkane, and a heterocyclic ring. In one embodiment, at least one of dianhydride and diamine contains a tricycloalkane or tricycloalkene. In one embodiment, at least one of dianhydride and diamine contains two or more cyclic groups. In one embodiment, the two or more cyclic groups are linked together by a linking group selected from the group consisting of -CH2-, -CH=CH-, -C≡C-, -O-, -C(O)O-, -CF3CH2CF3-, -CH3CH2CH3-, -SH-, and -SO2-. In one embodiment, at least one of dianhydride and diamine contains a cycloalkane selected from the group consisting of cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane and cyclooctane. In one embodiment, at least one of dianhydride and diamine contains a fused ring selected from the group consisting of naphthalene, anthracene, phenanthrene, chrysene, pyrene, coranulen, coronene, hexhelicene, indole, isoindole, indolizine, quinoline, isoquinoline, purine, carbazole, dibenzofuran, xanthene, phenazine, phenoxazine, and phenoxathiine. In one embodiment, forming the polyimide layer includes: forming a first polyimide layer including a first polyimide over the second passivation layer; and forming a second polyimide layer including a second polyimide, wherein each of the first polyimide and the second polyimide is a reaction product of a dianhydride and a diamine, wherein at least one of the dianhydride and the diamine includes one selected from the group consisting of a cycloalkane, a fused ring, a bicycloalkane, a tricycloalkane, a bicycloalkene, a tricycloalkene, a spiroalkane, and a heterocyclic ring, and the first polyimide and the second polyimide are different from each other. In an embodiment, the metal bump is in electrical contact with the metal pad structure, the polyimide layer is bonded to the second passivation layer and the metal pad structure by a coupling agent, and the coupling agent is chemically bonded to the polyimide, the second passivation layer, and the metal pad structure. In one embodiment, forming the polyimide layer comprises: combining polyamic acid, adhesion promoter, and a first solvent to form a polyamic acid composition; applying the polyamic acid composition over the second passivation layer and the metal pad structure; and heating the polyamic acid composition to a temperature of 150° C. to 350° C. to convert the polyamic acid to the polyimide. In one embodiment, the polyamic acid is a reaction product of a dianhydride and a diamine wherein at least one of the dianhydride and diamine contains one selected from the group consisting of a cycloalkane, a fused ring, a bicycloalkane, a tricycloalkane, a bicycloalkene, a tricycloalkene, a spiroalkane, and a heterocyclic ring. In one embodiment, the adhesion promoter comprises a chelating group, a silanol group and a cross-linking group. In one embodiment, the chelating group contains at least one of the following group: N, O, S, or a halogen. In one embodiment, the chelating group includes at least one of a thiol, a thiirane, a thiirane, a thietane, a thiolane, a thiophene, a thiane, a thiopyran, a thieane, a thiepine, a 2,3-dihydrothiophene, a 2,5-dihydrothiophene, a hydroxy, a carboxyl, an oxirane, an oxirane, an oxetane, an oxolane, a furan, an oxan, a pyran, an oxepan, an oxepine, a 2,5-dihydrofuran, a 2,3-dihydrofuran, an amine, an aziridine, an azetidine, an acetate, a pyrrolidine, a pyrrole, a piperidine, a pyridine, an azepine, an azepine, a 1-pyrroline, a 2-pyrroline, a 3-pyrroline, a dihydropyridine, a cyano group, a fluoro group, a chloro group, a bromo group or an iodo group. In an embodiment, the substrate is a chip. In an embodiment, the method includes attaching the chip to a chip-carrying substrate by bonding the chip to the chip-carrying substrate via the metal bump. In one embodiment, the chip is bonded to the chip-carrying substrate by a flip-chip bonding operation. In one embodiment, the method includes filling a gap between the chip and the chip-carrying substrate with an underfill material. In an embodiment, the method includes covering the chip and the chip-carrying substrate with a molding material.Another embodiment of the disclosure is a semiconductor device including a chip bonded to a chip-carrying substrate. A passivation layer is disposed over a main side of the chip facing the chip-carrying substrate, the passivation layer surrounding a first metal pad. A polyimide layer includes a polyimide disposed over the passivation layer and the first metal pad. A metal bump is disposed over the first metal pad and the polyimide layer. The metal bump is in electrical contact with the first metal pad and a second metal pad on the chip-carrying substrate. The polyimide is a reaction product of a dianhydride and a diamine, wherein at least one of the dianhydride and the diamine contains one selected from the group consisting of a cycloalkane, a fused ring, a bicycloalkane, a tricycloalkane, a bicycloalkene, a tricycloalkene, a spiroalkane, and a heterocyclic ring. In one embodiment, at least one of dianhydride and diamine contains a tricycloalkane or tricycloalkene. In one embodiment, at least one of dianhydride and diamine contains two or more cyclic groups. In one embodiment, the two or more cyclic groups are linked together by a linking group selected from the group consisting of -CH2-, -CH=CH-, -C≡C-, -O-, -C(O)O-, -CF3CH2CF3-, -CH3CH2CH3-, -SH-, and -SO2-. In one embodiment, at least one of dianhydride and diamine contains a cycloalkane selected from the group consisting of cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane and cyclooctane. In one embodiment, at least one of dianhydride and diamine contains a fused ring selected from the group consisting of naphthalene, anthracene, phenanthrene, chrysene, pyrene, coranulen, coronene, hexhelicene, indole, isoindole, indolizine, quinoline, isoquinoline, purine, carbazole, dibenzofuran, xanthene, phenazine, phenoxazine, and phenoxathiine. In one embodiment, the metal bump is formed from a metal selected from the group consisting of aluminum, copper, chromium, iron, manganese, magnesium, molybdenum, nickel, tin, niobium, tantalum, titanium, tungsten, zinc, and alloys thereof. In an embodiment, the semiconductor device includes a solder layer disposed over the metal bump. In one embodiment, the solder layer contains a tin-containing alloy selected from the following group: PbSn, AgSn, SnAgCu, CuSnNi, AgCuSnSn, AuSn and CuSn. In an embodiment, the passivation layer comprises a first passivation layer and a second passivation layer, wherein the first passivation layer and the second passivation layer are made of materials different from each other. In an embodiment, the first passivation layer includes a silicon oxide or a silicon nitride. In an embodiment, the second passivation layer includes a silicon oxide or a silicon nitride. In one embodiment, the polyimide layer has an elastic modulus of 4.5 GPa to 7 GPa. In one embodiment, the polyimide layer includes a first polyimide layer containing a first polyimide and a second polyimide layer disposed over the first polyimide layer and containing a second polyimide, wherein the first polyimide and the second polyimide are each a reaction product of a dianhydride and a diamine, wherein at least one of the dianhydride and the diamine contains one selected from the group consisting of a cycloalkane, a fused ring, a bicycloalkane, a tricycloalkane, a bicycloalkene, a tricycloalkene, a spiroalkane, and a heterocyclic ring, and the first polyimide and the second polyimide are different from each other. In an embodiment, the first metal pad and the second metal pad are formed from aluminum, copper, silver, gold, nickel, tungsten, titanium, tin, titanium nitride, hafnium, ruthenium, tantalum, tantalum nitride, alloys thereof, or multilayers thereof. In an embodiment, an under bump metallization layer is disposed over the first metal pad. In an embodiment, the under bump metallization layer comprises a double layer with a titanium-based layer and a copper-based layer. In one embodiment, the titanium-based layer contains titanium, titanium alloys, and titanium compounds containing 50 mol % or more of titanium, and the copper-based layer contains copper, copper alloys, and copper compounds containing 50 mol % or more of copper.

Claims

A method of manufacturing a bump structure, comprising: forming a passivation layer (25, 30) over a substrate (10); forming a metal pad structure (35) over the substrate (10), wherein the passivation layer (25, 30) surrounds the metal pad structure (35); forming a polyimide layer (40, 40a, 40b) containing a polyimide over the passivation layer (25, 30) and the metal pad structure (35); and forming a metal bump (55) over the metal pad structure (35) and the polyimide layer (40, 40a, 40b), the metal bump (55) being in electrical contact with the metal pad structure (35), the polyimide layer (40, 40a, 40b) being bonded to the passivation layer (25, 30) and the metal pad structure (35) by a coupling agent, the coupling agent being chemically bonded to the polyimide, the passivation layer (25, 30), and the metal pad structure (35), and the coupling agent including a chelating group, a silanol group, and a cross-linking group.The method of claim 1, wherein forming the polyimide layer (40, 40a, 40b) comprises: combining a polyamic acid, a coupling agent, and a first solvent to form a polyamic acid composition; applying the polyamic acid composition to the passivation layer (25, 30) and the metal pad structure (35); and heating the polyamic acid composition to a temperature of 150°C to 350°C to convert the polyamic acid to the polyimide.The method of claim 2, wherein the polyamic acid is a reaction product of a dianhydride and a diamine, wherein at least one of the dianhydride and the diamine contains one selected from the group consisting of a cycloalkane, a fused ring, a bicycloalkane, a tricycloalkane, a bicycloalkene, a tricycloalkene, a spiroalkane, and a heterocyclic ring.The method according to any one of claims 1 to 3, wherein the chelating group contains at least one of N, O, S or a halogen.The method of any one of claims 1 to 4, wherein the chelating group contains at least one of a thiol, a thiirane, a thiirane, a thietane, a thiolane, a thiophene, a thiane, a thiopyran, a thiepan, a thiepine, a 2,3-dihydrothiophene, a 2,5-dihydrothiophene, a hydroxy, a carboxyl, an oxirane, an oxirane, an oxetane, an oxolane, a furan, an oxan, a pyran, an oxetane, an oxepine, a 2,5-dihydrofuran, a 2,3-dihydrofuran, an amine, an aziridine, an azetidine, an acetate, a pyrrolidine, a pyrrole, a piperidine, a pyridine, an azepan, an azepine, a 1-pyrroline, a 2-pyrroline, a 3-pyrroline, a dihydropyridine, a cyano group, a fluoro group, a chloro group, a bromo group or an iodo group.

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