Method for bonding semiconductor element to substrate

Abstract

A method of bonding a semiconductor element to a substrate is provided. The method comprises the steps of: (a) providing the semiconductor element at a location separate from the substrate, the semiconductor element comprising a plurality of conductive structures, each of the conductive structures comprising a contact portion; (b) heating the semiconductor element at the location such that the contact portion is in a molten state; and (c) bonding the semiconductor element to the substrate such that each of the contact portions is bonded to a corresponding conductive structure of the substrate.

Description

Cross-reference to related applications

[0001] This application claims priority to U.S. Provisional Application No. 63 / 539,284, filed on September 19, 2023, the contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to a bonding system and process, and more particularly, to an improved system and method for bonding semiconductor elements to a substrate. Background Technology

[0003] Traditional semiconductor packaging typically involves die bonding and wire bonding processes. Advanced semiconductor packaging technologies, such as flip-chip bonding and thermocompression bonding, continue to receive attention in the industry. For example, in thermocompression bonding (TCB), heat and / or pressure (and sometimes ultrasonic energy) are used to form multiple interconnects between (i) conductive structures on a semiconductor element and (ii) conductive structures on a substrate. In certain flip-chip bonding or thermocompression bonding applications, the conductive structures of the semiconductor element and / or substrate may include surface oxides that could compromise bonding quality.

[0004] Therefore, it is desirable to provide a better method for bonding semiconductor devices to a substrate (e.g., a method for reducing oxides and / or improving bonding quality). Summary of the Invention

[0005] According to an exemplary embodiment of the present invention, a method for bonding a semiconductor element to a substrate is provided. The method includes the steps of: (a) providing the semiconductor element at a location separated from the substrate, the semiconductor element comprising a plurality of conductive structures, each of the conductive structures comprising a contact portion; (b) heating the semiconductor element at the location such that the contact portion is in a molten state; and (c) bonding the semiconductor element to the substrate such that each of the contact portions is bonded to a corresponding conductive structure of the substrate.

[0006] According to other embodiments of the present invention, the method described in the preceding paragraph may have any one or more of the following technical features: further comprising the steps of: providing a deoxidizer to contact the contact portion before step (c); further comprising the steps of: providing a deoxidizer to contact the contact portion before step (b); further comprising the steps of: providing a deoxidizer to contact the contact portion during step (b); further comprising the steps of: providing a deoxidizer to contact the contact portion after step (b); wherein the deoxidizer (in any prior step) comprises at least one of a reducing gas and a plasma gas; wherein the deoxidizer (in any prior step) comprises a reducing gas, the reducing gas comprising formic acid; further comprising the steps of: cooling the semiconductor element after step (b) such that the contact portion is in a solid state just before step (c): the position is an aligned position; and / or further comprising the steps of: heating the conductive structure of the substrate before step (c).

[0007] According to another exemplary embodiment of the present invention, a method for bonding a semiconductor element to a substrate is provided. The method includes the steps of: (a) providing the semiconductor element at a location separated from the substrate, the semiconductor element comprising a plurality of conductive structures, each of the conductive structures comprising a contact portion; (b) heating the semiconductor element at the location such that the contact portion is at a temperature within 40°C of the melting point of a material of the contact portion, the temperature being below the melting point; and (c) bonding the semiconductor element to the substrate such that each of the contact portions is bonded to a corresponding conductive structure of the substrate.

[0008] According to other embodiments of the present invention, the method described in the preceding paragraph may have any one or more of the following technical features: further comprising the following steps: providing a deoxidizer to contact the contact portion before step (c); further comprising the following steps: providing a deoxidizer to contact the contact portion before step (b); further comprising the following steps: providing a deoxidizer to contact the contact portion during step (b); further comprising the following steps: providing a deoxidizer to contact the contact portion after step (b); the deoxidizer (in any prior step) comprising at least one of a reducing gas and a plasma gas; the deoxidizer (in any prior step) comprising a reducing gas. The reducing gas comprises formic acid; further comprising the following steps: after step (b), cooling the semiconductor element: the location is an aligned position; further comprising the following steps: before bonding, heating the conductive structure of the substrate; step (b) comprising: heating the semiconductor element at the location such that the contact portion is at a temperature within 30°C of the melting point; step (b) comprising heating the semiconductor element at the location such that the contact portion is at a temperature within 20°C of the melting point; and / or step (b) comprising heating the semiconductor element at the location such that the contact portion is at a temperature within 10°C of the melting point.

[0009] According to yet another exemplary embodiment of the present invention, a method for bonding a semiconductor element to a substrate is provided. The method includes the steps of: (a) providing the semiconductor element at a location separated from the substrate, the semiconductor element comprising a plurality of conductive structures; (b) heating the semiconductor element at the location to an increased temperature; (c) after step (b), cooling the semiconductor element to a decreased temperature, the decreased temperature being lower than the increased temperature; and (d) bonding the semiconductor element to the substrate such that each of the conductive structures is bonded to a corresponding conductive structure of the substrate.

[0010] According to other embodiments of the present invention, the method described in the preceding paragraph may have any one or more of the following technical features: further comprising the steps of: providing a deoxidizer to the conductive structure before step (d); further comprising the steps of: providing a deoxidizer to the conductive structure before step (b); further comprising the steps of: providing a deoxidizer to the conductive structure during step (b); further comprising the steps of: providing a deoxidizer to the conductive structure after step (b); wherein the deoxidizer (in any prior step) comprises at least one of a reducing gas and a plasma gas; wherein the deoxidizer (in any prior step) comprises a reducing gas, the reducing gas comprising formic acid; the position is an aligned position; further comprising the steps of: heating the conductive structure of the substrate before bonding; wherein the conductive structure of the semiconductor element comprises copper; wherein the conductive structure of the substrate comprises copper; wherein the conductive structure of the substrate comprises copper; and / or during step (d), no solder is provided between the conductive structure and the corresponding conductive structure of the substrate.

[0011] According to yet another exemplary embodiment of the present invention, a method for bonding a semiconductor element to a substrate is provided. The method includes the following steps: (a) providing the semiconductor element at a location separated from the substrate, the semiconductor element comprising a plurality of conductive structures, each of the conductive structures comprising a contact portion; (b) providing a deoxidizer to contact the contact portion; (c) heating the semiconductor element at the location such that the contact portion is in a molten state; (d) after step (c), cooling the semiconductor element such that the contact portion is in a solid state; and (e) after step (d), bonding the semiconductor element to the substrate such that each of the contact portions is bonded to a corresponding conductive structure of the substrate.

[0012] According to other embodiments of the present invention, the method described in the preceding paragraph may have any one or more of the following technical features: step (b) occurs before step (e); step (b) occurs before step (c); step (d) occurs after step (c) such that exactly before step (e), the contact portion is in a solid state; the position is an aligned position; further comprising the following steps: heating the conductive structure of the substrate before bonding; the deoxidizer comprising at least one of a reducing gas and a plasma gas; and / or the deoxidizer comprising a reducing gas, the reducing gas comprising formic acid. Attached Figure Description

[0013] The invention will be best understood by referring to the accompanying drawings and the following detailed description. It should be emphasized that, by convention, the features in the drawings are not shown to scale. Instead, the dimensions of the features have been arbitrarily enlarged or reduced to make them clear. The drawings include the following figures: Figures 1A to 1I These are a series of block diagrams of a bonding system, illustrating a method of bonding semiconductor elements to a substrate according to various exemplary embodiments of the present invention; Figures 2A to 2J yes Figure 1A A series of block diagrams of the bonding system to FIG1J illustrate another method of bonding semiconductor elements to a substrate according to another exemplary embodiment of the present invention; Figures 3A to 3J yes Figure 1A A series of block diagrams of the bonding system to FIG1J illustrate another method of bonding semiconductor elements to a substrate according to another exemplary embodiment of the present invention; Figures 4 to 7 This is a flowchart illustrating various methods for bonding semiconductor elements to a substrate according to various exemplary embodiments of the present invention; and Figure 8 This is a block diagram of another bonding system according to another exemplary embodiment of the present invention. Detailed Implementation

[0014] This invention provides various methods for bonding semiconductor elements to a substrate. Both the substrate (e.g., a target substrate) and the semiconductor element (e.g., a die, "chip," etc.) may have various oxides with varying degrees of oxide thickness, which can cause bonding quality problems. Specific embodiments provided herein mitigate problems associated with such oxides compared to known bonding processes and provide more efficient and uniform cleaning. Specific embodiments of the invention can accelerate the rate of oxide reduction on the conductive surfaces to be bonded. For example, oxides on the conductive structures of the semiconductor element (e.g., the "chip" side) can be reduced in a thermocompression bonding (TCB) process (e.g., a fluxless TCB process).

[0015] In a specific TCB process, a semiconductor element (e.g., a source die) can be brought to a suitable distance (e.g., 1-2 mm) away from the target substrate. A deoxidizer (e.g., reducing gas, formic acid vapor, plasma, plasma gas, etc.) can be provided (e.g., implanted) at or near the semiconductor element and / or the target substrate. Simultaneously, the semiconductor element can be heated such that the contact portions of the conductive structure (e.g., including solder) are heated above the melting temperature of the material contained in / on the contact portions (e.g., solder). In the presence of a specific deoxidizer (e.g., formic acid vapor), the rate of oxide reduction increases when the contact portions are in the molten state. The contact portions in the molten state can be configured to absorb a specific amount of surface oxides. In a specific embodiment, the effects of oxide reduction and oxide absorption are harmonized / combined to create a particularly effective cleaning process. In a specific embodiment, the molten solder can be solidified prior to the corresponding conductive structure (e.g., "target bump") on the contact substrate. In a specific embodiment, contact during bonding can be performed when the contact portions are in the molten state.

[0016] When the conductive structure (e.g., "die bumps") of a clean semiconductor element contacts the substrate, the conductive structure acts as a thermally conductive medium. As a result, heat from the semiconductor element is conducted (e.g., flows) through the conductive structure of the substrate, and surface oxides (e.g., oxide / formate layers) present on the substrate are cleaned. Embodiments of the present invention provide improved cleaning on both the chip and substrate sides compared to known bonding processes, which can significantly improve bonding quality. Specific embodiments of the invention allow pre-cleaning process steps (such as pre-cleaning processes for the substrate) to be avoided.

[0017] As used herein, the term "semiconductor element" means any structure that includes (or is configured to include in subsequent steps) a semiconductor chip or die. Exemplary semiconductor elements include: bare semiconductor dies, semiconductor dies on a substrate (e.g., leadframe, PCB, carrier, semiconductor chip, semiconductor wafer, BGA substrate, semiconductor element, etc.), packaged semiconductor devices, flip-chip semiconductor devices, dies embedded in a substrate, stacks of semiconductor dies, etc. Furthermore, a semiconductor element may include elements configured to be bonded or otherwise included in a semiconductor package (e.g., spacers, substrates, etc., to be bonded in a stacked die configuration).

[0018] As used in this invention, the term "substrate" means any structure to which a semiconductor element can be bonded. Exemplary substrates include, for example, leadframes, PCBs, carriers, modules, semiconductor chips, semiconductor wafers, BGA substrates, other semiconductor elements, etc.

[0019] According to a specific exemplary embodiment of the present invention, the fluxless bonding system is provided by using a deoxidizer (e.g., a reducing gas). For example, the bonding system may be a flip-chip bonding system, a thermocompression bonding system, a thermosonic bonding system, and so on.

[0020] Specific embodiments will be best described in conjunction with the accompanying drawings. Throughout the drawings, similar reference numerals denote similar elements, unless otherwise explained herein. Shading, diagonal lines, and / or patterns in the drawings may be used to indicate elevated temperatures. However, such shading, diagonal lines, and / or patterns are arbitrary and not necessarily intended to represent the same temperatures in the various drawings.

[0021] Please refer to the following: Figures 1A to 1I , Figures 2A to 2J ,and Figures 3A to 3J The diagram illustrates a bonding machine 100 (e.g., a flip chip bonding machine, a thermoforming bonding machine, etc.) with respect to a specific exemplary embodiment of the invention. The bonding machine 100 includes a bonding head / welding head assembly 106, which may be configured along (or around) multiple axes of the bonding machine 100 (e.g., x-axis, y-axis, z-axis, rotation / θ-axis, etc.). The bonding head assembly 106 includes a heater 108 and a bonding tool 110. In a particular embodiment, the heater 108 and / or the bonding tool 110 may include gas channels configured to supply cooling fluid (e.g., gas, forced gas, forced air, nitrogen, etc.) to cool the semiconductor element. In a particular bonding machine (e.g., a thermoforming bonding machine), it may be necessary to heat the bonding tool 110. Therefore, when Figures 1A to 1I When the individual heaters 108 are illustrated for heating the bonding tool 100 (e.g., for heating a semiconductor element 112 / 112′ including multiple conductive structures 112a / 112b and / or multiple contact portions 112a1), it will be understood that the heaters 108 and the bonding tool 110 may be integrated into a single element (e.g., a heated bonding tool).

[0022] Bonding head assembly 106 carries bonding head manifold 114 for receiving and distributing fluids (e.g., deoxidizers, gases, liquids, vapors, plasmas, etc.) as required in a given application. As used herein, the terms "fluid" and "gas" can be interpreted broadly (e.g., including states of matter that do not have a fixed shape and / or have flowability). According to a particular exemplary embodiment of the invention, the bonding system (e.g., a fluxless bonding system) can provide a "gas" for reducing oxides on the conductive structures of the substrate and / or semiconductor element. Such a gas may include a carrier gas (e.g., nitrogen, argon, etc.), wherein such a carrier gas may be a gas mixture (e.g., a mixture of nitrogen and hydrogen, etc.). For example, the gas may be a reducing gas (e.g., formic acid vapor, acetic acid vapor), a plasma gas (e.g., including carrier gases such as nitrogen), a gas that includes electron-attaching gases (e.g., including carrier gases such as a mixture of nitrogen and hydrogen, etc.), and so on.

[0023] As shown in the figure, the bonding head manifold 114 is illustrated as being connected via conduit 120 (e.g., including rigid conduit, flexible conduit, a combination of the two, or other structures suitable for carrying deoxidizer and / or the fluids described herein) to a deoxidizer source 118 (e.g., a bubbler system, gas canister, plasma source, etc.). In a particular embodiment, the deoxidizer source 118 may be a vapor generation system, such as a bubbler system comprising an acidic fluid (e.g., formic acid, acetic acid, etc.). In a particular embodiment, the deoxidizer source 118 may be configured to supply plasma gas to reduce or remove oxides (e.g., on semiconductor elements 112 / 112′ and / or substrate 104 / 104′). For example, the deoxidizer source 118 may be a plasma gas delivery system (or connected to a plasma gas delivery system).

[0024] Throughout the accompanying drawings, the bonding head manifold 114 is shown in cross-sectional view; however, it should be understood that the bonding head manifold 114 may surround the bonding tool 110 (e.g., the bonding head manifold 114 may be coaxially arranged around the bonding tool 110). The bonding head manifold 114 may have a different configuration than that shown in the figures. Furthermore, it is understood that certain details of the bonding head manifold 114 (e.g., the interconnection with the conduit 120, structural details of distributing the deoxidizer within the bonding head manifold 114, structural details of distributing the shielding gas within the bonding head manifold 114, structural details of evacuating a vacuum through the central channel of the bonding head manifold 114, etc.) have been omitted for simplicity.

[0025] The bonding head manifold 114 includes three channels 114a, 114b, and 114c with different functions. The outer channel 114a receives a shielding gas (e.g., an inert gas, nitrogen, etc.) from a shielding gas supply source (e.g., included in or flowably connected to a deoxidizer source 118). Specifically, the shielding gas is supplied from the shielding gas supply source (e.g., a nitrogen supply source) and delivered to the outer channel 114a of the bonding head manifold 114 via conduit 120. From the outer channel 114a of the bonding head manifold 114, shielding gas 122 is provided to provide shielding against the external environment. The inner channel 114c receives a deoxidizer 124 via conduit 120 and provides the deoxidizer 124 to the region associated with the bonding operation, including the semiconductor elements 112 / 112′ and the substrate 104 / 104′.

[0026] As will be understood by those skilled in the art, the specific design of the bonding head manifold (or different delivery systems for providing the deoxidizer) can vary considerably. For example, in certain embodiments of the invention, the shielding gas may not be provided by the bonding head manifold. Similarly, in certain embodiments of the invention, the exhaust system for a localized area of ​​the bonding head manifold may not be used. For example, in bonding systems utilizing plasma gas as the deoxidizer, such a shielding gas (and / or localized exhaust system) may not be considered critical and therefore may not be included in the bonding system.

[0027] The bonding machine 100 includes a support structure 102 for supporting the substrate 104 / 104' during bonding operations (where the substrate 104 / 104' includes a plurality of conductive structures 104a / 104b). The support structure 102 may include a suitable structure for a particular application. The support structure 102 includes a top plate 102a (configured to directly support the substrate 104 / 104'), a chuck 102c, and a heater 102b disposed between the top plate and the chuck. In bonding operations where heat is required to heat the substrate 104 / 104', a heater such as heater 102b may be utilized.

[0028] Regarding the bonding operation, a bonding tool 110 is used to bond semiconductor elements 112 / 112′ to substrates 104 / 104′. During the bonding operation, corresponding portions of the conductive structures of semiconductor elements 112 / 112′ are bonded (e.g., using heat, force, ultrasonic energy, etc.) to the respective corresponding portions of the conductive structures 104a / 104b of substrates 104 / 104′. A bonding head manifold 114 provides a deoxidizer 124 (e.g., a reducing gas containing saturated vapor gas) in the regions of semiconductor elements 112 / 112′ and substrates 104 / 104′ regarding the bonding operation. After the deoxidizer 124 is dispensed into the regions of semiconductor elements 112 / 112′ and substrates 104 / 104′, the deoxidizer 124 contacts the surface of each of the conductive structures 112a / 112b / 104a / 104b of semiconductor elements 112 / 112′ and substrates 104 / 104′. The surface of conductive structures 104a / 112a may subsequently include reaction products (e.g., said reaction products are provided as (i) surface oxides on conductive structures 112a / 112b / 104a / 104b and (ii) a deoxidizer 124 from deoxidizer source 118). These reaction products need to be removed from the bonding region (i.e., the region where the conductive structures 112a / 112b of semiconductor elements 112 / 112′ are bonded to the corresponding conductive structures 104a / 104b of substrate 104 / 104′) using a vacuum provided via outlet conduit 116 through the central channel 114b of bonding head manifold 114.

[0029] Please refer to this carefully now. Figures 1A to 1I ,exist Figure 1A In the figure, the bonding head assembly 106 is illustrated to position a semiconductor element 112 above a substrate 104. The semiconductor element 112 includes a plurality of conductive structures 112a. As shown, each conductive structure 112a includes a contact portion 112a1 (e.g., a solder contact portion).

[0030] exist Figure 1B In this configuration, semiconductor element 112 is lowered by bonding head assembly 106 and provided at a position separated from substrate 104. Such a position can be considered as (i) an aligned position, (ii) a pre-bonded position, or (iii) another desired position (e.g., a predetermined position).

[0031] exist Figure 1CIn the diagram, the bonding head manifold 114 is illustrated as providing a shielding gas 122 and a deoxidizer 124. The shielding gas 122 (e.g., an inert gas, a gas including nitrogen, etc.) is provided in the region surrounding the semiconductor element 112 and the substrate 104. The deoxidizer 124 is illustrated as being distributed in the adjacent region of the bonding region of the semiconductor element 112 and the substrate 104. The deoxidizer 124 is accessible to the surface of each of the conductive structures 112a (including contact portions 112a1) of the semiconductor element 112 and the surface of each of the conductive structures 104a of the substrate 104.

[0032] exist Figure 1D In China, compared to Figure 1C The contact portion 112a1 is illustrated in the figure and is depicted as being at a higher temperature (as indicated by the shaded portion of contact portion 112a1). In a particular embodiment, contact portion 112a1 is in a molten state (e.g., where the solder of contact portion 112a1 is in a liquid or molten state). In a particular embodiment, contact portion 112a1 is in a semi-molten state (e.g., where the innermost solder of contact portion 112a1 is in a liquid or molten state). In a particular embodiment, contact portion 112a1 is in a solid state (e.g., at a temperature lower than the melting point of the material of contact portion 112a1, such as within 40°C (or 30°C, or 20°C, or 10°C) of the melting point).

[0033] exist Figure 1E In this process, the contact portion 112a1 is brought into contact with the corresponding conductive structure 104a of the substrate 104. Compared to in Figure 1D The contact portion 112a1 shown in the diagram is now depicted at a lower temperature. The conductive structure 104a of the substrate 104 can act as a heat sink or cooling mechanism to cool the contact portion 112a1. In a particular embodiment, the contact portion 112a1 can be solidified from a previous molten state.

[0034] exist Figure 1F In China, compared to Figure 1E The contact portion 112a1 shown in the diagram is now depicted as being at a higher temperature (as indicated by the shaded area of ​​the contact portion 112a1). Furthermore, compared to in Figure 1E The conductive structure 104a is illustrated in the diagram, and at least a portion of the conductive structure 104a of the substrate 104 is now shown at a higher temperature. In certain embodiments, heat may be provided from heater 108 and / or heater 102b. The increased temperature of the contact portion 112a1 and the conductive structure 104a tends to cause metallurgical bonding formed therebetween (e.g., caused by solder reflow).

[0035] exist Figure 1G In this process, semiconductor element 112 has now been bonded to substrate 104. That is, Figure 1F Each contact portion 112a1 is illustrated as a corresponding conductive structure 104a bonded to the substrate 112, thereby forming a bonding portion 126. Therefore, during the bonding operation, corresponding portions of the conductive structures 112a of the semiconductor element 112 are bonded (e.g., using heat, force, ultrasonic energy, etc.) to their respective corresponding portions of the conductive structures 104a of the substrate 104. Although the six conductive structures 112a of the semiconductor element 112 are illustrated as six conductive structures 104a bonded to the substrate 104, the invention is not limited thereto. It should be understood that any number of conductive structures 112a can be bonded to any number of conductive structures 104a. For example, two or more conductive structures 112a can be bonded to one conductive structure 104a. For example, two or more conductive structures 104a can be bonded to one conductive structure 112a.

[0036] exist Figure 1H In the diagram, the bonding head manifold 114 is shown as no longer supplying deoxidizer 124 and shielding gas 122. Figure 1I In the diagram, the bonding head assembly 106 is shown to have moved away from the support structure 102 (e.g., along the Z-axis), and the semiconductor element 112 is now bonded to the substrate 104.

[0037] Figures 1C to 1G The diagram illustrates that the bonding head manifold 114 continuously (e.g., before and during bonding) provides a deoxidizer 124 (e.g., reducing gas, formic acid, plasma, plasma gas, etc.) and a shielding gas (e.g., inert gas, gas including nitrogen, etc.). However, the invention is not limited thereto. For example, in certain embodiments, the deoxidizer may be provided to contact the contact portion 112a1 at various different times, such as: immediately before bonding; before heating the contact portion 112a1; during heating the contact portion 112a1; after heating the contact portion 112a1, etc.

[0038] Now for reference Figures 2A to 2J Another exemplary embodiment of the invention is illustrated therein. See details. Figure 2A The bonding head assembly 106 is illustrated to position the semiconductor element 112 above the substrate 104. The semiconductor element 112 includes a plurality of conductive structures 112a. As shown, each conductive structure 112a includes a contact portion 112a1 (e.g., a solder contact portion).

[0039] exist Figure 2BIn this configuration, semiconductor element 112 is provided at a location separate from substrate 104. Such a location may be considered as (i) an aligned location, (ii) a pre-bonded location, or (iii) another required location (e.g., a predetermined location).

[0040] exist Figure 2C In the diagram, the bonding head manifold 114 is illustrated as providing a shielding gas 122 and a deoxidizer 124. The shielding gas 122 (e.g., an inert gas, a gas including nitrogen, etc.) is provided in the region surrounding the semiconductor element 112 and the substrate 104. The deoxidizer 124 is illustrated as being distributed in the adjacent region of the bonding region of the semiconductor element 112 and the substrate 104. The deoxidizer 124 is accessible to the surface of each of the conductive structures 112a (including contact portions 112a1) of the semiconductor element 112 and the surface of each of the conductive structures 104a of the substrate 104.

[0041] exist Figure 2D In China, compared to Figure 2C The contact portion 112a1 is illustrated in the figure and is depicted as being at a higher temperature (as indicated by the shaded portion of contact portion 112a1). In a particular embodiment, contact portion 112a1 is in a molten state (e.g., where the solder of contact portion 112a1 is in a liquid or molten state). In a particular embodiment, contact portion 112a1 is in a semi-molten state (e.g., where the innermost solder of contact portion 112a1 is in a liquid or molten state). In a particular embodiment, contact portion 112a1 is in a solid state (e.g., at a temperature lower than the melting point of the material of contact portion 112a1, such as within 40°C (or 30°C, or 20°C, or 10°C) of the melting point).

[0042] exist Figure 2E In China, compared to Figure 2D The contact portion 112a1, as illustrated in the diagram, is now depicted at a lower temperature. Accordingly, the semiconductor element 112 (including the conductive structure 112a) is now cooled. In certain embodiments, the semiconductor element 112 may be passively cooled (e.g., via turning off the heater, via convection of adjacent gas, etc.) and / or actively cooled (e.g., via forced air, via forced gas through gas channels from the heater 108 and / or bonding tool 110, via a cooling mechanism, etc.). In certain embodiments, the contact portion 112a1 is in a solid state (e.g., at a temperature lower than the melting point of the material of the contact portion 112a1, such as within 40°C of the melting point).

[0043] exist Figure 2FIn this process, the contact portion 112a1 is brought into contact with the corresponding conductive structure 104a of the substrate 104. Compared to in Figure 2E The contact portion 112a1 shown in the figure can be at an even lower temperature. The conductive structure 104a of the substrate 104 can act as a heat sink or cooling mechanism to further cool the contact portion 112a1.

[0044] exist Figure 2G In China, compared to Figure 2F The contact portion 112a1 shown in the diagram is now depicted as being at a higher temperature (as indicated by the shaded area of ​​the contact portion 112a1). Furthermore, compared to in Figure 2F The conductive structure 104a is illustrated in the diagram, and at least a portion of the conductive structure 104a of the substrate 104 is now shown at a higher temperature. In certain embodiments, heat may be provided from heater 108 and / or heater 102b. The increased temperature of the contact portion 112a1 and the conductive structure 104a tends to cause metallurgical bonding formed therebetween (e.g., caused by solder reflow).

[0045] exist Figure 2H In this process, semiconductor element 112 has now been bonded to substrate 104. Figure 2G Each contact portion 112a1 is illustrated as a corresponding conductive structure 104a bonded to the substrate 112, thereby forming a bonding portion 126. During the bonding operation, corresponding portions of the conductive structures 112a of the semiconductor element 112 are bonded (e.g., using heat, force, ultrasonic energy, etc.) to their respective corresponding portions of the conductive structures 104a of the substrate 104. Although the six conductive structures 112a of the semiconductor element 112 are illustrated as six conductive structures 104a bonded to the substrate 104, the invention is not limited thereto. It should be understood that any number of conductive structures 112a can be bonded to any number of conductive structures 104a. For example, two or more conductive structures 112a can be bonded to one conductive structure 104a. In another example, two or more conductive structures 104a can be bonded to one conductive structure 112a.

[0046] exist Figure 2I In the diagram, the bonding head manifold 114 is shown as no longer supplying deoxidizer 124 and shielding gas 122. Figure 2J In the diagram, the bonding head assembly 106 is shown to have moved away from the support structure 102 (e.g., along the Z-axis), and the semiconductor element 112 is now bonded to the substrate 104.

[0047] Figures 2C to 2HThe diagram illustrates that the bonding head manifold 114 continuously (e.g., before and during bonding) provides a deoxidizer 124 (e.g., reducing gas, formic acid, plasma, plasma gas, etc.) and a shielding gas (e.g., inert gas, gas including nitrogen, etc.). However, the invention is not limited thereto. For example, in certain embodiments, the deoxidizer may be provided to contact the contact portion 112a1 at various different times, such as: immediately before bonding; before heating the contact portion 112a1; during heating the contact portion 112a1; and / or after heating the contact portion 112a1.

[0048] Now for reference Figures 3A to 3J Another exemplary embodiment of the invention is illustrated therein. Please refer to the following in particular. Figure 3A The bonding head assembly 106 is shown to position the semiconductor element 112' above the substrate 104'.

[0049] exist Figure 3B In this embodiment, semiconductor element 112' is provided at a location separated from substrate 104'. Such a location can be considered an aligned location, (ii) a pre-bonded location, or (iii) another desired location (e.g., a predetermined location). Semiconductor element 112' includes a plurality of conductive structures 112b. In a particular embodiment, conductive structures 112b may comprise copper (and / or be made of copper) (e.g., copper alloys, elemental copper, etc.). Substrate 104' includes a plurality of conductive structures 104b. In a particular embodiment, conductive structures 104b may comprise copper (and / or be made of copper) (e.g., copper alloys, elemental copper, etc.).

[0050] exist Figure 3C In the diagram, the bonding head manifold 114 is illustrated as providing a shielding gas 122 and a deoxidizer 124. The shielding gas 122 (e.g., an inert gas, a gas including nitrogen, etc.) is provided in the region surrounding the semiconductor element 112' and the substrate 104'. The deoxidizer 124 is illustrated as being distributed in the adjacent region of the bonding region of the semiconductor element 112' and the substrate 104'. The deoxidizer 124 is accessible to the surface of each of the conductive structures 112b of the semiconductor element 112' and the surface of each of the conductive structures 104b of the substrate 104'.

[0051] exist Figure 3D In China, compared to Figure 3C The conductive structure 112b is illustrated in the figure. The conductive structure 112b is shown at a higher temperature (as indicated by the shaded portion of the conductive structure 112b) while still in a solid state (e.g., at a temperature lower than the melting point of the material of the conductive structure 112b).

[0052] exist Figure 3E In China, compared to Figure 3DThe conductive structure 112b shown in the diagram is now depicted at a lower temperature. Accordingly, the semiconductor element 112' (including the conductive structure 112b) is now cooled. In certain embodiments, the semiconductor element 112' may be passively cooled (e.g., via turning off the heater 108, via convection of adjacent gas, etc.) and / or actively cooled (e.g., via forced air, via forced gas through gas channels from the heater 108 and / or bonding tool 110, via a cooling mechanism, etc.).

[0053] exist Figure 3F In the diagram, conductive structure 112b is shown as having been brought into contact with the corresponding conductive structure 104b of substrate 104'. Compared to... Figure 3D and / or Figure 3E The conductive structure 112b shown in the figure can be at a lower temperature. The conductive structure 104b of the substrate 104' can act as a heat sink or cooling mechanism to cool the conductive structure 112b.

[0054] exist Figure 3G In China, compared to Figure 3F The conductive structure 112b shown in the diagram is now depicted at a higher temperature (as indicated by the shaded area of ​​conductive structure 112b). Furthermore, compared to... Figure 3F The conductive structure 104b is illustrated in the diagram, and at least a portion of the conductive structure 104b of the substrate 104' is now shown at a higher temperature. In a particular embodiment, heat may be provided from heater 108 and / or heater 102b. The increased temperature of the conductive structure 112b and the conductive structure 104b tends to cause metallurgical bonding formed therebetween.

[0055] exist Figure 3H In this process, semiconductor element 112' has now been bonded to substrate 104'. Each conductive structure 112b (e.g., Figure 3G The diagram shows the corresponding conductive structure 104b that has been bonded to the substrate 112'. During the bonding operation, corresponding portions of the conductive structures 112b of the semiconductor element 112' are bonded (e.g., using heat) to their respective corresponding portions of the conductive structures 104b of the substrate 104'. Although the six conductive structures 112b of the semiconductor element 112' are shown as six conductive structures 104b bonded to the substrate 104', the invention is not limited thereto. It should be understood that any number of conductive structures 112b can be bonded to any number of conductive structures 104b. For example, two or more conductive structures 112b can be bonded to one conductive structure 104b. In another example, two or more conductive structures 104b can be bonded to one conductive structure 112b.

[0056] exist Figure 3I In the diagram, the bonding head manifold 114 is shown as no longer supplying deoxidizer 124 and shielding gas 122. Figure 3J In the diagram, the bonding head assembly 106 is shown to have moved away from the support structure 102 (e.g., along the Z-axis), and the semiconductor element 112′ is now bonded to the substrate 104′.

[0057] Figures 3C to 3H The diagram illustrates that the bonding head manifold 114 continuously (e.g., before and during bonding) provides a deoxidizer 124 (e.g., reducing gas, formic acid, plasma, plasma gas, etc.) and a shielding gas (e.g., inert gas, gas including nitrogen, etc.). However, the invention is not limited thereto. For example, in certain embodiments, the deoxidizer may be provided to contact the contact portion 112b1 at various different times, such as: immediately before bonding; before heating the contact portion 112b1; during heating the contact portion 112b1; and / or after heating the contact portion 112b1.

[0058] Figures 4 to 7 This is a flowchart illustrating various exemplary methods of bonding semiconductor elements to a substrate. As will be understood by those skilled in the art, specific steps included in the flowchart may be omitted; specific additional steps may be added; and the order of steps may be varied from the order shown, all of which are covered within the scope of this invention.

[0059] Please refer to this carefully. Figure 4 In step 400, a semiconductor element is provided at a location separated from the substrate (e.g., see in...). Figure 1B and Figure 2B The relative positions of the semiconductor element 112 and the substrate 104. The semiconductor element includes multiple conductive structures (e.g., in...). Figure 1B and Figure 2B The conductive structure 112a in the middle), each of the conductive structures includes a contact portion (e.g., in the middle of the conductive structure 112a). Figure 1B and Figure 2B (Contact portion 112a1 in the middle). In a particular embodiment, the position is an aligned position.

[0060] In step 402, the semiconductor element is heated at the location such that the contact portion is in a molten state (e.g., in...). Figure 1D and Figure 2D (Contact portion 112a1 in the semiconductor). In a particular embodiment, step 402 may be performed before, during, and / or after the semiconductor element is located at the position. For example, the semiconductor element may be heated before or during its movement to the position.

[0061] In selective step 404, a deoxidizer is provided (e.g., in...). Figures 1C to 1G and Figures 2C to 2H The deoxidizer 124 in the plasma comes into contact with the contact portion. In a particular embodiment, step 404 occurs: (i) before step 410; (ii) before step 402; (iii) during step 402; and / or (iv) after step 402. In a particular embodiment, the deoxidizer comprises at least one of a reducing gas and a plasma gas. In a particular embodiment, the deoxidizer comprises a reducing gas, which comprises formic acid.

[0062] In selective step 406 (e.g., after step 402), the semiconductor element is cooled such that the contact portion (e.g., in...) Figure 2E The contact portion 112a1 in the semiconductor element is in a solid state (e.g., just before step 410). In a particular embodiment, the semiconductor element may be passively cooled and / or actively cooled. In selective step 408, the conductive structure of the substrate is heated prior to bonding (e.g., Figure 1F and Figure 2G The conductive structure 104a of the substrate 104 in the middle.

[0063] In step 410, the semiconductor element is bonded to the substrate such that each of the contact portions is bonded to a corresponding conductive structure of the substrate (e.g., Figure 1F The contact portion 112a is bonded to the conductive structure 104a to form Figure 1G The bonding portion 126, Figure 2F The contact portion 112a is bonded to the conductive structure 104a to form Figure 2H (126)

[0064] Please refer to the following: Figure 5 In step 500, a semiconductor element is provided at a location separated from the substrate (e.g., see [reference]). Figure 1B and Figure 2B The relative positions of the semiconductor element 112 and the substrate 104. The semiconductor element includes multiple conductive structures (e.g., in...). Figure 1B and Figure 2B The conductive structure 112a in the middle), each of the conductive structures includes a contact portion (e.g., in the middle of the conductive structure 112a). Figure 1B and Figure 2B (Contact portion 112a1 in the middle). In a particular embodiment, the position is an aligned position.

[0065] In step 502, the semiconductor element is heated at the location such that the contact portion is at a distance from the contact portion (e.g., at...). Figure 1D and Figure 2DThe temperature is within 40°C of the melting point of the material of the contact portion 112a1. The temperature may be lower than the melting point (e.g., the melting point of the material of the contact portion, such as solder). In a particular embodiment, the temperature is: within 30°C of the melting point; within 20°C of the melting point; and / or within 10°C of the melting point. In a particular embodiment, step 502 may be performed before, during, and / or after the semiconductor element is located at the position. For example, the semiconductor element may be heated before or during its movement to the position.

[0066] In selective step 504, a deoxidizer is provided (e.g., in...). Figures 1C to 1G and Figures 2C to 2H The deoxidizer 124 in the plasma comes into contact with the contact portion. In a particular embodiment, step 504 occurs: (i) before step 510; (ii) before step 502; (iii) during step 502; and / or (iv) after step 502. In a particular embodiment, the deoxidizer comprises at least one of a reducing gas and a plasma gas. In a particular embodiment, the deoxidizer comprises a reducing gas, which comprises formic acid.

[0067] In selective step 506 (e.g., after step 502), the semiconductor element (e.g., including...) is cooled. Figure 1E The contact portion 112a1). In a particular embodiment, the semiconductor element may be passively cooled and / or actively cooled. In selective step 508, the conductive structure of the substrate is heated prior to bonding (e.g., Figure 1F and Figure 2G The conductive structure 104a of the substrate 104 in the middle.

[0068] In step 510, the semiconductor element is bonded to the substrate such that each of the contact portions is bonded to a corresponding conductive structure of the substrate (e.g., Figure 1F The contact portion 112a1 is bonded to the conductive structure 104a to form Figure 1G The bonding portion 126, Figure 2F The contact portion 112a1 is bonded to the conductive structure 104a to form Figure 2H (126)

[0069] Please refer to the following: Figure 6 In step 600, a semiconductor element is provided at a location separated from the substrate (e.g., see in...). Figure 3B The relative positions of the semiconductor element 112' and the substrate 104' are shown. The semiconductor element includes multiple conductive structures (e.g., in...). Figure 3B(Conductive structure 112b in the semiconductor element). In a particular embodiment, the conductive structure of the semiconductor element is made of copper (and / or contains copper).

[0070] In step 602, the semiconductor element is heated to an increased temperature at the said location. In a particular embodiment, step 602 may be performed before, during, and / or after the semiconductor element is located at the said location. For example, the semiconductor element may be heated before or while it is being moved to the said location.

[0071] In selective step 604, a deoxidizer (e.g., in...) is provided. Figures 3C to 3H The deoxidizer 124 in the plasma contacts the conductive structure (e.g., conductive structure 112b). In a particular embodiment, step 604 occurs: (i) before step 610; (ii) before step 602; (iii) during step 602; and / or (iv) after step 602. In a particular embodiment, the deoxidizer comprises at least one of a reducing gas and a plasma gas. In a particular embodiment, the deoxidizer comprises a reducing gas, which comprises formic acid.

[0072] In selective step 606 (e.g., after step 602), the semiconductor element is cooled to a reduced temperature, which is lower than the increased temperature (e.g., Figure 3E The semiconductor element 112'). In a particular embodiment, the semiconductor element may be passively cooled and / or actively cooled. In selective step 608, the conductive structure of the substrate is heated prior to bonding (e.g., Figure 3G (Conductive structure 104b in the example). In step 610, the semiconductor element is bonded to the substrate such that each of the conductive structures is bonded to a corresponding conductive structure on the substrate (e.g., see [reference]). Figure 3I (The bonded semiconductor element 112').

[0073] Please refer to the following: Figure 7 In step 700, in contact with the substrate (e.g., Figure 1B Semiconductor elements (e.g., substrate 104) are provided at locations where they are separated (e.g., an aligned location). Figure 1B The semiconductor element 112). The semiconductor element includes a plurality of conductive structures, each of which includes a contact portion (e.g., Figure 1B (Contact portion 112a1).

[0074] In step 702, a deoxidizer (e.g., Figure 1CThe deoxidizer 124 contacts the contact portion. In a particular embodiment, step 702 occurs before bonding (e.g., step 708). In a particular embodiment, step 702 occurs before heating the semiconductor element (e.g., step 704). In a particular embodiment, the deoxidizer comprises at least one of a reducing gas and a plasma gas. In a particular embodiment, the deoxidizer comprises a reducing gas containing formic acid (e.g., formic acid vapor).

[0075] In step 704, the semiconductor element is heated at the location such that the contact portion is in a molten state (e.g., Figure 1D The contact portion 112a1). In step 706, (e.g., after step 704) the semiconductor element is cooled such that the contact portion (e.g., in Figure 1E The contact portion 112a1 is in a solid state (e.g., just before step 708).

[0076] In step 708, after step 706, the semiconductor element is bonded to the substrate such that each of the contact portions is bonded to a corresponding conductive structure of the substrate (e.g., Figure 1F The contact portion 112a is bonded to the conductive structure 104a to form Figure 1G (The bonding portion 126). In a particular embodiment, the step of heating the conductive structure of the substrate occurs before step 708 (e.g., exactly before).

[0077] Various exemplary aspects of the invention are described in relation to heating a semiconductor element at a location separate from the substrate. For example, heat may be provided by a heater (e.g., heater 108) included in the bonding head assembly. For example, such a heater may heat the semiconductor element at said location such that the contact portions of the conductive structure of the semiconductor element are in a molten state. In another example, such a heater may heat the semiconductor element at said location such that the contact portions are at a temperature within 40°C of the melting point of the material of the contact portions, said temperature being below said melting point. In yet another example, such a heater may heat the semiconductor element at said location to an increased temperature, wherein, after heating (and before bonding), the semiconductor element is cooled to a decreased temperature, said decreased temperature being lower than said increased temperature. It should be understood that instead of using these exemplary methods to heat the semiconductor element (or, in addition to these), the substrate (or a portion of the substrate) may also be heated. Figure 8The bonding system 100a is illustrated. Except as described herein, the bonding system 100a is the same as the previously described bonding systems (having the same reference numerals). The bonding system 100a includes a local heater 102b1 (e.g., a laser source, a pulsed laser source, etc.) for heating a local portion 104c of the substrate 104. That is, the local portion 104c may be a part of the substrate 104, which is configured to receive a semiconductor element 112 in the bonding process. In the presence of the deoxidizer 124, a heating conduction structure 104a (e.g., in particular, the contact portion 104a1 of such conduction structure 104a) may be required. For example, the substrate 104 is heated at the location such that the contact portion 104a1 is in a molten state; the substrate 104 is heated at the location such that the contact portion 104a1 is at a temperature within 40°C of the melting point of the material at the contact portion (the temperature is below the melting point); or the substrate 104 is heated at the location to an increased temperature, wherein after heating (and before bonding) the substrate is cooled to a decreased temperature, the decreased temperature being lower than the increased temperature. Such heating operations can be performed using a local heater 102b1, or using another heat source as needed. The heating operations described in this paragraph with respect to the contact portion 104a1 of the substrate 104 can be implemented in conjunction with (or instead of) any other embodiment of the invention, for example, as with respect to Figures 1A to 1I , Figures 2A to 2J , Figures 3A to 3J ,and Figures 4 to 7 The illustrations and descriptions.

[0078] While the present invention is primarily illustrated and described with respect to the dispensing of deoxidizers via a bonding head assembly, the invention is not limited thereto. Those skilled in the art will appreciate that the deoxidizer can be provided in several different configurations, for example, via a support structure configured to support a substrate. More specifically, as shown in U.S. Patent No. 11,1205,633 (see Figures 11A through 11D), a reducing gas (i.e., an example of a deoxidizer described herein) can be provided via a support structure.

[0079] Although not explicitly described in relation to the various embodiments disclosed in this invention, as those skilled in the art will know, the bonding of a semiconductor element to a substrate can be carried out using ultrasonic energy and / or force.

[0080] While the present invention has been illustrated and described with reference to specific embodiments, it is not intended to be limited to the details shown. Rather, various modifications to the details may be made within the scope and equivalents of the claims and without departing from the invention.

Claims

1. A method for bonding a semiconductor element to a substrate, the method comprising the following steps: (a) The semiconductor element is provided at a location separated from the substrate, the semiconductor element comprising a plurality of conductive structures, each of the conductive structures comprising a contact portion; (b) Heating the semiconductor element at the location such that the contact portion is in a molten state; as well as (c) Bonding the semiconductor element to the substrate such that each of the contact portions is bonded to the corresponding conductive structure of the substrate.

2. The method according to claim 1, further comprising the following steps: Prior to step (c), a deoxidizer is provided to contact the contact portion.

3. The method according to claim 1, further comprising the following steps: Prior to step (b), a deoxidizer is provided to contact the contact portion.

4. The method according to claim 1, further comprising the following steps: During step (b), a deoxidizer is provided to contact the contact portion.

5. The method according to claim 1, further comprising the following steps: After step (b), a deoxidizer is provided to contact the contact portion.

6. The method of claim 1, further comprising the following steps: After step (b), the semiconductor element is cooled so that the contact portion is in a solid state just before step (c).

7. The method according to claim 1, wherein, The position is an aligned position.

8. The method of claim 1, further comprising the following steps: Prior to step (c), the conductive structure of the substrate is heated.

9. The method according to claim 2, wherein, The deoxidizer comprises at least one of a reducing gas and a plasma gas.

10. The method according to claim 2, wherein, The deoxidizer contains a reducing gas, which contains formic acid.

11. A method for bonding a semiconductor element to a substrate, the method comprising the following steps: (a) The semiconductor element is provided at a location separated from the substrate, the semiconductor element comprising a plurality of conductive structures, each of the conductive structures comprising a contact portion; (b) Heating the semiconductor element at the location such that the contact portion is at a temperature within 40°C of the melting point of the material of the contact portion, the temperature being below the melting point; as well as (c) Bonding the semiconductor element to the substrate such that each of the contact portions is bonded to the corresponding conductive structure of the substrate.

12. The method of claim 11, further comprising the following steps: Prior to step (c), a deoxidizer is provided to contact the contact portion.

13. The method of claim 11, further comprising the following steps: Prior to step (b), a deoxidizer is provided to contact the contact portion.

14. The method of claim 11, further comprising the following steps: During step (b), a deoxidizer is provided to contact the contact portion.

15. The method of claim 11, further comprising the following steps: After step (b), a deoxidizer is provided to contact the contact portion.

16. The method of claim 11, further comprising the following steps: After step (b), the semiconductor element is cooled.

17. The method according to claim 11, wherein, The position is an aligned position.

18. The method of claim 11, further comprising the following steps: Prior to step (c), the conductive structure of the substrate is heated.

19. The method according to claim 12, wherein, The deoxidizer comprises at least one of a reducing gas and a plasma gas.

20. The method according to claim 12, wherein, The deoxidizer contains a reducing gas, which contains formic acid.

21. The method according to claim 11, wherein, Step (b) includes heating the semiconductor element at the location such that the contact portion is at a temperature within 30°C of the melting point.

22. The method according to claim 11, wherein, Step (b) includes: heating the semiconductor element at the location such that the contact portion is at a temperature within 20°C of the melting point.

23. The method according to claim 11, wherein, Step (b) includes heating the semiconductor element at the location such that the contact portion is at a temperature within 10°C of the melting point.

24. A method for bonding a semiconductor element to a substrate, the method comprising the following steps: (a) The semiconductor element is provided at a location separate from the substrate, the semiconductor element comprising a plurality of conductive structures; (b) Heating the semiconductor element at the location to an increased temperature; (c) After step (b), the semiconductor element is cooled to a reduced temperature, the reduced temperature being lower than the increased temperature; as well as (d) Bonding the semiconductor element to the substrate such that each of the conductive structures is bonded to the corresponding conductive structure of the substrate.

25. The method of claim 24, further comprising the following steps: Prior to step (d), a deoxidizer is provided to contact the conductive structure.

26. The method of claim 24, further comprising the following steps: Prior to step (b), a deoxidizer is provided to contact the conductive structure.

27. The method of claim 24, further comprising the following steps: During step (b), a deoxidizer is provided to contact the conductive structure.

28. The method of claim 24, further comprising the following steps: After step (b), a deoxidizer is provided to contact the conductive structure.

29. The method according to claim 24, wherein, The position is an aligned position.

30. The method of claim 24, further comprising the following steps: The conductive structure of the substrate is heated before bonding.

31. The method according to claim 25, wherein, The deoxidizer comprises at least one of a reducing gas and a plasma gas.

32. The method of claim 25, wherein the deoxidizer comprises a reducing gas, and the reducing gas comprises formic acid.

33. The method according to claim 24, wherein, The conductive structure of the semiconductor element comprises copper.

34. The method according to claim 33, wherein, The conductive structure of the substrate comprises copper.

35. The method according to claim 24, wherein, The conductive structure of the substrate comprises copper.

36. The method according to claim 24, wherein, During step (d), no solder is provided between the conductive structure and the corresponding conductive structure of the substrate.

37. A method for bonding a semiconductor element to a substrate, the method comprising the following steps: (a) The semiconductor element is provided at a location separated from the substrate, the semiconductor element comprising a plurality of conductive structures, each of the conductive structures comprising a contact portion; (b) Provide a deoxidizer to contact the contact portion; (c) Heating the semiconductor element at the location such that the contact portion is in a molten state; (d) After step (c), the semiconductor element is cooled so that the contact portion is in a solid state; and (e) After step (d), the semiconductor element is bonded to the substrate such that each of the contact portions is bonded to the corresponding conductive structure of the substrate.

38. The method according to claim 37, wherein, Step (b) occurs before step (e).

39. The method according to claim 37, wherein, Step (b) occurs before step (c).

40. The method of claim 37, wherein, Step (d) occurs after step (c), such that the contact portion is in a solid state just before step (e).

41. The method according to claim 37, wherein, The position is an aligned position.

42. The method of claim 37, further comprising the following steps: Prior to step (e), the conductive structure of the substrate is heated.

43. The method according to claim 37, wherein, The deoxidizer comprises at least one of a reducing gas and a plasma gas.

44. The method of claim 37, wherein, The deoxidizer contains a reducing gas, which contains formic acid.

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