Soldering system for soldering semiconductor element to substrate and related method

Abstract

A soldering system for soldering a semiconductor element to a substrate is provided. The seaming system includes a reducing gas delivery system configured to provide a reducing gas to a seaming region of the seaming system. The seaming system also includes a gas delivery line configured to deliver a reducing gas from the reducing gas source to the reducing gas delivery system. At least a portion of the gas delivery line is heated.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 398,328, filed on August 16, 2022, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to soldering systems (eg, flip chip and / or thermocompression soldering systems) and related soldering processes, and more particularly, to improved systems and methods for soldering semiconductor components to substrates, including the use of reducing gases. Background Art

[0004] Conventional semiconductor packaging generally involves a bare die attach process and a wire bonding process. Advanced semiconductor packaging techniques (e.g., flip chip bonding, thermocompression bonding, etc.) continue to gain traction in the industry. For example, in thermocompression bonding (i.e., 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.

[0005] In certain flip chip soldering or thermocompression soldering applications, the conductive structures of the semiconductor component and / or substrate may include copper structures (e.g., copper pillars) or other materials that are subject to oxidation and / or other contamination. In such applications, it is desirable to provide an environment suitable for soldering. Conventionally, such an environment may be provided by using a reducing gas in the soldering area to reduce potential oxidation and / or contamination of the conductive structures of the semiconductor component or substrate to which it is to be soldered.

[0006] It would be desirable to provide improved soldering systems and related methods for soldering such semiconductor components to substrates. Summary of the invention

[0007] According to an exemplary embodiment of the present invention, a soldering system for soldering a semiconductor element to a substrate is provided. The soldering system includes a reducing gas delivery system configured to provide a reducing gas to a soldering area of ​​the soldering system. The soldering system also includes a gas delivery line configured to transport the reducing gas from a reducing gas source to the reducing gas delivery system. At least a portion of the gas delivery line is heated.

[0008] According to various exemplary embodiments of the present invention, the welding system of the immediately preceding paragraph may include any one or more of the following features: a portion of the manifold for distributing the reducing gas may also be heated by a heating element; the reducing gas is formic acid vapor; the formic acid concentration of the formic acid vapor is 4-15%; a heating element for heating the gas delivery line; heating the gas delivery line according to a thermal profile; using the temperature of the reducing gas source to at least partially determine the thermal profile; the thermal profile includes a temperature greater than the temperature of the reducing gas source; the temperature of the reducing gas source is 20°C-70°C; the reducing gas source is a bubbler type system; the substrate oxidation The invention relates to a substrate oxide reduction chamber, which is configured to receive a substrate before the semiconductor element is soldered to the substrate, and the substrate oxide reduction chamber has an inert environment when receiving the substrate; a substrate oxide reduction chamber, which is configured to receive a substrate before the substrate oxide reduction chamber receives the substrate, and is configured to receive a reducing gas, and further includes another reducing gas delivery system, which is configured to provide reducing gas into the substrate oxide reduction chamber; and an additional gas delivery pipeline, which is configured to transport reducing gas from a reducing gas source to the substrate oxide reduction chamber, wherein at least a portion of the additional gas delivery pipeline is heated.

[0009] According to another exemplary embodiment of the present invention, a method for soldering a semiconductor element to a substrate is provided. The method includes: using a gas delivery line to guide a reducing gas from a reducing gas source to a soldering area of ​​a soldering system; heating at least a portion of the gas delivery line; and soldering the semiconductor element to the substrate in the soldering area.

[0010] According to various exemplary embodiments of the present invention, the method of the immediately preceding paragraph may include any one or more of the following features: a portion of the manifold for distributing the reducing gas may also be heated with a heating element; the directing step includes delivering the reducing gas to the welding area via a reducing gas delivery system; the reducing gas is formic acid vapor; the formic acid concentration of the formic acid vapor is 4-15%; the heating step includes heating the gas delivery line according to the thermal distribution (for example, using a heating element); heating the gas delivery line according to the thermal distribution; the thermal distribution is at least partially determined using the temperature of the reducing gas source; the thermal distribution includes a temperature greater than the temperature of the reducing gas source; the temperature of the reducing gas source is 20°C-70°C; the reducing gas source is a bubbler type system; further includes the step of heating the reducing gas source; further includes the step of directing the reducing gas from the reducing gas source via an additional gas delivery line to the substrate oxide reduction chamber, the substrate being received by the substrate oxide reduction chamber before the welding step; and heating the additional gas delivery line. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present invention can be best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be emphasized that, according to common practice, the various features of the drawings are not drawn to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. The drawings include the following figures:

[0012] Figures 1 to 4 is a block side view illustrating a welding system configured to provide a reducing gas to a welding area according to various exemplary embodiments of the present invention;

[0013] FIG. 5A to FIG. 5B and FIG. 6A to FIG. 6B is a block side view illustrating a welding system configured to provide a reducing gas to a welding area and a substrate oxide reduction chamber according to various exemplary embodiments of the present invention; and

[0014] Figure 7 is a flow chart illustrating a method of soldering a semiconductor component to a substrate on a soldering system according to various exemplary embodiments of the present invention. DETAILED DESCRIPTION

[0015] Various aspects of the present invention relate to supplying a reducing gas (e.g., formic acid in a carrier gas (e.g., nitrogen)) from a reducing gas source (e.g., a formic acid vapor source, such as a bubbler) to a predetermined area of ​​a soldering system (e.g., a soldering area of ​​a hot press soldering machine). According to certain aspects of the present invention, it is desirable to reduce (and possibly prevent) the likelihood of condensation of the reducing gas (e.g., formic acid vapor including the carrier gas) by raising the temperature of the delivery line above the dew point of the reducing gas (e.g., formic acid vapor). It may also be desirable to provide a higher concentration of acid in the reducing gas (e.g., provide a higher concentration of formic acid in the formic acid vapor). For example, according to certain exemplary embodiments of the present invention, the reducing gas may include 4-15% formic acid. Such a reducing gas may be provided to a reducing gas delivery system (e.g., a solder head shield of a soldering system) and / or another area of ​​a soldering system (e.g., a substrate oxide reduction chamber). The reducing gas may be used to create a localized reducing environment around a semiconductor component and a substrate. Utilizing a high acid concentration reducing gas facilitates the removal of oxides (e.g., copper, silver, indium, solder, tin-silver solder, etc.) from the surfaces of semiconductor components and / or conductive structures of the substrate. The use of such a high acid concentration reducing gas also helps to reduce the injection time of the reducing gas. As a result, an overall improvement in UPH (unit per hour) of a bonding process (eg, a flip chip bonding process, a thermocompression bonding process, etc.) is provided.

[0016] Each of U.S. Patent No. 10,861,820 (entitled “METHODS OF BONDING SEMICONDUCTORELEMENTS TO A SUBSTRATE, INCLUDING USE OF A REDUCING GAS, AND RELATED BONDING MACHINES”), U.S. Patent No. 11,205,633 (entitled “METHODS OF BONDING SEMICONDUCTORELEMENTS TO SUBSTRATES, AND RELATED BONDING SYSTEMS”), and U.S. Patent No. 11,515,286 (entitled “METHODS OF BONDING SEMICONDUCTOR ELEMENTS TO SUBSTRATES, AND RELATED BONDING SYSTEMS”) relates to welding systems utilizing reducing gases and are incorporated herein by reference in their entirety.

[0017] As used herein, the term "semiconductor element" is intended to refer to any structure that includes (or is configured to include at a later step) a semiconductor chip or die. Exemplary semiconductor elements include bare semiconductor dies, semiconductor dies on substrates (e.g., lead frames, PCBs, carriers, semiconductor chips, semiconductor wafers, BGA substrates, semiconductor elements, etc.), packaged semiconductor devices, flip-chip semiconductor devices, dies embedded in substrates, stacks of semiconductor dies, etc. In addition, semiconductor elements may include elements that are configured to be soldered or otherwise included in a semiconductor package (e.g., spacers, substrates, etc. that are soldered in a stacked die configuration).

[0018] As used herein, the term "substrate" is intended to refer to any structure to which a semiconductor component may be soldered. Exemplary substrates include, for example, a lead frame, a PCB, a carrier, a module, a semiconductor chip, a semiconductor wafer, a BGA substrate, another semiconductor component, etc.

[0019] Now referring to the accompanying drawings, Figure 1 A soldering system 100 (e.g., a flip chip soldering machine, a hot press soldering machine, etc.) is shown. The soldering system 100 includes a support structure 102 for supporting a substrate 104 during a soldering operation (wherein the substrate 104 includes a plurality of conductive structures 104a). The support structure 102 may include any suitable structure for a particular application. In the illustrated embodiment, the support structure 102 includes a top plate 102a (configured to directly support the substrate 104), a chuck 102c, and a heater 102b disposed between the substrate and the chuck.

[0020] The welding system 100 also includes a welding head assembly 106, which can be configured to move along (and around) multiple axes of the welding system 100, such as, for example, an x-axis, a y-axis, a z-axis, a theta (rotational) axis, etc. The welding head assembly 106 includes and / or carries a heater 108 and a welding tool 110. In certain welding machines (e.g., a hot press welder), it may be necessary to heat the welding tool 110. Although Figure 1 A separate heater 108 is shown for heating the bonding tool 110 (for heating the semiconductor element 112 including the plurality of conductive structures 112a), but it is understood that the heater 108 and the bonding tool 110 may be integrated into a single element (eg, a heated bonding tool).

[0021] Regarding the soldering operation, the semiconductor element 112 is soldered to the substrate 104 using the soldering tool 110. During the soldering operation, corresponding ones of the conductive structures 112a are soldered (eg, using heat, force, ultrasonic energy, etc.) to respective ones of the conductive structures 104a. Figure 1 In the example shown, the conductive structures 112a include solder material 112a1 at the contact portion of each conductive structure 112b (e.g., the portion of the conductive structure 104a configured to contact the substrate 104). It should be understood that this is an example, and any of the conductive structures of the semiconductor element and / or substrate shown herein (or other conductive structures within the scope of the present invention) may or may not include such solder material.

[0022] In certain welding applications (e.g., hot press welding, flip chip welding, etc.), it is desirable to provide an environment suitable for welding. Conventionally, such an environment can be provided by using a reducing gas in the welding area to reduce the potential oxides of the conductive structures of the semiconductor element and / or the substrate to which it will be welded. The reducing gas is delivered to the welding area by a reducing gas delivery system. Such a reducing gas delivery system can be any device for distributing the reducing gas to the welding area. Here, the reducing gas delivery system is illustrated and described as a manifold, which is configured to receive a fluid and distribute the fluid to the welding area. However, the present invention is not limited to this. It is conceivable that the reducing gas delivery system may include any suitable structure, such as a pipe / tube opening, a nozzle, a sprayer, etc.

[0023] exist Figure 1 In the embodiment of the present invention, the welding head assembly 106 carries a welding head manifold 114 that serves as a reducing gas delivery system. Although the welding head manifold 114 is shown in a cross-sectional view, the actual welding head manifold 114 surrounds the welding tool 110 (e.g., the welding head manifold surrounds the welding tool 100 in a coaxial configuration). Of course, the welding head manifold 114 may have a similar configuration to the welding head manifold 114. Figure 1The construction shown in has a different configuration. In addition, it should be understood that for the sake of simplicity, certain details of the weld head manifold 114 are omitted.

[0024] The weld head manifold 114 includes three channels 114a, 114b, and 114c with different functions. The outer channel 114a receives a shielding gas (e.g., nitrogen) from a shielding gas supply source (not shown). The shielding gas 128 is provided from the outer channel 114a of the weld head manifold 114 to shield the welding area 122 from the external environment. The inner channel 114c receives a reducing gas 130 (e.g., wherein the reducing gas 130 can be a saturated vapor gas, such as formic acid vapor, a reducing gas including an excess reducing substance, etc.) via a gas delivery line 120, and provides the reducing gas 130 to the welding area 122 (e.g., the welding area 122 is the location where the semiconductor element 112 is welded to the substrate 104).

[0025] The reducing gas 130 is provided by a reducing gas source 118 (via a gas delivery line 120). For example, the reducing gas source 118 can be a bubbler-type system that includes (i) an acidic fluid such as formic acid, acetic acid, or another acidic fluid (wherein the bubbler-type system can be part of the welding system 100) and (ii) a carrier gas (e.g., nitrogen). In another example, the reducing gas source 118 can be a container (e.g., a pressurized container such as a tank) or another source for directing the reducing gas 130 to the welding system 100. The reducing gas source 118 can be heated to promote a higher vapor-gas saturation point (e.g., a formic acid vapor concentration of 4-15%). The reducing gas source 118 can be heated, for example, to a range of 20° C.-70° C., or a range of 40° C.-50° C., etc. The reducing gas 130 (e.g., formic acid vapor including a carrier gas such as nitrogen) is delivered from the reducing gas source 118 to the weld head manifold 114 via the gas delivery line 120. The gas delivery line 120 is a structure (eg, a conduit, a pipe, a hose, etc.) configured to carry the reducing gas 130 , and may include a plurality of branches.

[0026] If a higher concentration of acid is provided in the reducing gas, the reducing gas 130 may be more effective when heated (e.g., in providing a desired environment for welding); however, it is desirable to avoid condensation caused by temperature differences between (i) the reducing gas at the reducing gas source and (ii) the reducing gas in the gas delivery line 120. Figure 1A heating element 120a is shown surrounding the gas delivery line 120. The heating element 120a provides heat (e.g., by conduction, convection, radiation, or any other heating method) to the gas delivery line 120 (and, if desired, to the portion of the manifold 114 that receives the reducing gas). Heat may be provided to the gas delivery line 120 according to a heat profile. As used herein, the term "heat profile" is intended to be broadly defined as any type of heating process for heating at least a portion of a gas delivery line.

[0027] Various aspects of various exemplary "heat profiles" are now described. For example, the heat profile may simply heat appropriate portions of the gas delivery line to a fixed set point. In another example, the heat profile may include a time-based heating process (e.g., where the heat set point varies over time) (e.g., having a first temperature set point before welding, and having a different temperature set point during welding). In yet another example, the heat profile may include a heating process that takes into account the reducing gas flow rate. In yet another example, the heat profile may utilize different set points depending on the location along the gas delivery line (e.g., where the gas delivery line may include multiple branches, and where the multiple branches may have different temperature set points).

[0028] In another example, the thermal profile is determined at least in part using a temperature of the reducing gas source (e.g., a set point temperature value, a measured temperature value, a temperature range, a temperature profile, etc.). As used herein, the reducing gas source temperature can be a temperature of a liquid (e.g., formic acid liquid) at the reducing gas source, a temperature of a gas (e.g., formic acid vapor including a carrier gas) at the reducing gas source, a temperature of a structure of the reducing gas source, etc. If it is desired to use such a temperature, certain figures provided herein illustrate a temperature sensor 118a for providing the reducing gas source temperature.

[0029] In a more specific example, the thermal profile can include a temperature target (eg, a specific temperature value, a temperature range, etc.) The temperature target can be based on another temperature (eg, greater than a reducing gas source temperature, a temperature required for a specific concentration of formic acid vapor in nitrogen, etc.).

[0030] In another more specific example, the heat profile can be controlled by a closed loop system that includes a controller (e.g., a sensor that measures the temperature of the gas delivery line and a controller configured to achieve a temperature set point, not shown for simplicity). In another example, the heat profile can include parameters other than temperature (e.g., heat flow based on the reducing gas flow rate, on / off time, etc.).

[0031] The above exemplary aspects of heat profiles are not mutually exclusive; that is, heat profiles may combine more than one of these aspects. Thus, it should be understood by those skilled in the art that the term "heat profile" is not limited to any specific process for heating a gas delivery line. As will be further understood by those skilled in the art, Figure 1 The descriptions of heating elements and / or heat profiles provided may be applicable to other embodiments of the invention shown and described herein (e.g., Figures 2 to 4 , FIG. 5A to FIG. 5B and FIG. 6A to FIG. 6B ) and corresponding heating elements, as well as other embodiments within the scope of the present invention.

[0032] although Figure 1 The heating element 120a is shown surrounding the entire length of the gas delivery line 120 (and the portion of the manifold 114 that receives the reducing gas), but the invention is not limited in this regard. As will be appreciated by those skilled in the art, the gas delivery line 120 may be heated by other arrangements, including heaters placed near, below, in, or otherwise proximate to the gas delivery line to achieve the same effect. Moreover, it is contemplated that the heating element 120a may achieve its purpose by surrounding only a portion of the length of the gas delivery line 120. The variations described in this paragraph (e.g., heating may be for the entire gas delivery line, or a portion of the gas delivery line, etc.) apply to all other embodiments of the invention (not just the entire gas delivery line). Figure 1 those shown in ).

[0033] After the reducing gas 130 is distributed in the welding area 122, the reducing gas 130 contacts the surface of each of the conductive structure 104a (of the substrate 104) and the conductive structure 112a (of the semiconductor element 112). The surface of the conductive structure 104a / 112a may then include reaction products (e.g., the reaction products are provided as a result of (i) surface oxides on the conductive structure 104a / 112a, and (ii) the reducing gas 130 (and, if necessary, heat that may be provided by the heater 108 and transferred to the conductive structure 104a via contact with the conductive structure 112a). The reaction products are preferably removed from the welding area 122 using a vacuum provided through the central passage 114b of the weld head manifold 114 via the outlet conduit 116.

[0034] Reference now Figure 2, a welding system 200 is shown. The welding system 200 is similar in many respects to the welding system 100, wherein similar elements have the same reference numbers or numbers beginning with "2" instead of "1" (unless otherwise explicitly indicated). The welding system 200 includes a support structure 202 for supporting the substrate 104. The support structure 202 includes a top plate 202a (configured to directly support the substrate 104), a chuck 202c, and a heater 202b disposed between the top plate and the chuck.

[0035] The welding system 200 also includes a welding head assembly 106 (including a heater 108 and a welding tool 110), which can be configured to move along (and around) multiple axes (e.g., x-axis, y-axis, z-axis, θ (rotational) axis, etc.) of the welding system 200. The welding head assembly 106 includes and / or carries the heater 108 and the welding tool 110. The welding tool 110 is shown as carrying a semiconductor component 112 (including a plurality of conductive structures 112a and solder material 112a1). The welding head assembly 106 is shown carrying a plate 107 for partially containing at least one of a shielding gas 128 and a reducing gas 130.

[0036] With the welding head assembly 106 (such as Figure 1 ) is opposite to the welding head manifold 114, Figure 2 Another manifold 214 is shown carried by and / or integrated with the support structure 202. The manifold 214 serves as a reducing gas delivery system. Although the manifold 214 is shown in a cross-sectional view, the actual manifold 214 at least partially surrounds the substrate 104. Of course, the manifold 214 may have a similar structure to the substrate 104. Figure 2 In addition, it should be understood that for simplicity, certain details of the manifold 214 are omitted (e.g., interconnection details with the gas delivery line 120, structural details for distributing the reducing gas 130 within the manifold 214, structural details for distributing the shielding gas 128 within the manifold 214, structural details for evacuating the central channel 214b of the manifold 214, etc.).

[0037] The manifold 214 includes three channels 214a, 214b, 214c with different functions. The outer channel 214a receives a shielding gas 128 (e.g., nitrogen) from a shielding gas supply source (e.g., a nitrogen tank, a gas supply source, etc.). The shielding gas 128 is provided from the outer channel 214b of the manifold 214 to shield the welding area 222 from the external environment. The inner channel 214c receives the reducing gas 130 via the gas delivery line 120 and provides the reducing gas 130 to the welding area 222 in conjunction with the welding operation. The reducing gas 130 is provided by the reducing gas source 118 and carried by the gas delivery line 120.

[0038] The gas delivery line 120 is configured to carry the reducing gas 130 from the reducing gas source 118 to the soldering area 222 of the soldering system 200, wherein the reducing gas 130 is configured to be used during soldering of the semiconductor element 112 to the substrate 104 at the soldering area 222. Figure 2 In the illustrated embodiment, the gas delivery line 120 is configured to provide the reducing gas 130 (e.g., via the manifold 214) to the support structure 202. A heating element 120a is provided for increasing the temperature of the gas delivery line 120 (and, if desired, the portion of the manifold 214 that receives the reducing gas), thereby increasing the temperature of the reducing gas 130 flowing through the gas delivery line 120 before the reducing gas 130 reaches the welding area.

[0039] After the reducing gas 130 is distributed in the region of the semiconductor element 112 and the substrate 104, the reducing gas 130 contacts the surface of each of the conductive structures 104a and 112a. The surface of the conductive structures 104a / 112a may then include reaction products (e.g., where the reaction products are provided as a result of: (i) surface oxides on the conductive structures 104a / 112a, and (ii) the reducing gas from the reducing gas 130 (and, if necessary, heat provided by the heater 108). The reaction products are preferably removed from the bonding region (i.e., the region where the conductive structures 112a of the semiconductor element 112 are bonded to the corresponding conductive structures 104a of the substrate 104) using a vacuum provided through the central passage 214b of the manifold 214 via the outlet conduit 216.

[0040] Reference now Figure 3 , shows a welding system 300. The welding system 300 is similar in many respects to Figure 1 The soldering system 100 of the present invention is shown in the drawings, wherein similar elements have the same reference numbers or numbers beginning with "3" instead of "1" (unless otherwise explicitly indicated). The soldering system 300 includes: a substrate source 300a (e.g., a wafer handler or other source) for providing a substrate 104 (e.g., a wafer, a printed circuit board, etc.) on a support structure 300a1; and a processing system 300b. The substrate 104 is configured to be transferred to the processing system 300b (e.g., including an internal environmental chamber 320, which includes a tunnel 302). The tunnel 302 includes a substrate oxide prevention chamber 302b and a soldering position 302c (which is a portion of the substrate oxide prevention chamber 302b). A reducing gas delivery system 308 (including a solder head manifold 114) is also included in the processing system 300b. Within the processing system 300b (sometimes referred to as a mainframe compartment), the internal environmental chamber 320 may include the substrate oxide prevention chamber 302b and at least a portion of the reducing gas delivery system 308.

[0041] The welding system 300 also includes a welding head assembly 106 and a welding tool 110, wherein the welding head assembly includes a heater 108. Figure 1 Details of an exemplary welding head assembly 106 are described below. Figure 3 Also shown is a main exhaust device 304, which is connected to the main exhaust device 304 through a pipe 304a and a pipe 114b1 (where the pipe 114b1 is directly or indirectly coupled to Figure 1 The weld head assembly 106 carries a weld head manifold 114 that serves as a reducing gas delivery system. The weld head manifold 114 receives reducing gas 130 from a reducing gas source 118 via a gas delivery line 120.

[0042] exist Figure 3 In the example shown, the tunnel 302 includes an entry door 302a1 (which closes the opening 302a1a). A substrate transfer system (which can be part of a material handling system, including the support structure 102) is used to transfer the substrate 104 through the entry door 302a1 to the substrate oxide prevention chamber 302b. The substrate oxide prevention chamber 302b includes an inert environment 306 (e.g., by a nitrogen supply, not shown for simplicity). The material handling system is used to move the substrate 104 within the substrate oxide prevention chamber 302b to a welding position 302c. At the welding position 302c, a reducing gas 130 is provided by a reducing gas delivery system 308. The reducing gas 130 is provided by a reducing gas source 118 and carried by a gas delivery line 120.

[0043] The gas delivery line 120 is configured to deliver the reducing gas 130 from the reducing gas source 118 to a welding region (e.g., including the welding location 302c) of the welding system 300, wherein the reducing gas 130 is configured to be used during welding of the semiconductor element 112 to the substrate 104 at the welding region. Figure 3 In the illustrated embodiment, the gas delivery line 120 is configured to provide the reducing gas 130 to the weld head assembly 106 and / or the weld head manifold 114. A heating element 120a is provided for increasing the temperature of the gas delivery line 120 and, in turn, increasing the temperature of the reducing gas 130 flowing through the gas delivery line 120 before the reducing gas 130 reaches the welding area.

[0044] In connection with the soldering operation, the semiconductor component 112 (which is carried by the soldering head assembly 106 into the tunnel 302 through the opening 302e) is soldered to the substrate 104 using the soldering tool 110. During the soldering operation, corresponding conductive structures of the plurality of conductive structures of the semiconductor component 112 are soldered (e.g., using heat, force, ultrasonic energy, etc.) to corresponding conductive structures of the conductive structures of the substrate 104. The soldering head manifold 114 provides a reducing gas 130 (e.g., where the reducing gas can be a saturated vapor, such as formic acid vapor) in the region of the semiconductor component 112 and the substrate 104 in connection with the soldering operation (in the illustrated example, the reducing gas is able to enter the tunnel 302 through the opening 302e). After the reducing gas 130 is distributed in the region of the semiconductor component 112 and the substrate 104, the reducing gas 130 contacts the surface of each of the conductive structures of the semiconductor component 112 and the substrate 104.

[0045] Reference now Figure 4 , shows a welding system 400. The welding system 400 is similar in many respects to Figure 2 The welding system 200 and Figure 3 The welding system 400 is substantially the same as the welding system 300, but with similar components having the same reference numbers or numbers beginning with "4" instead of "1", "2" or "3" (unless otherwise expressly indicated). Figure 2 The manifold 214 (and related structure) is replaced by Figure 1 The weld head manifold 114 (and related structure) is shown.

[0046] The welding system 400 includes a main exhaust 404 that extracts exhaust gases (e.g., gases such as reducing gas vapor) through conduits 404a and 404b. The processing system 400b is similar to the processing system 300b, except that the processing system 400b includes a reducing gas delivery system 408 (including the manifold 214) instead of the reducing gas delivery system 308 (including the welding head manifold 114). The manifold 214 is provided for receiving and distributing the fluids (e.g., gases, vapors, etc.) required in a given application. The manifold 214 receives the reducing gas 130 from the reducing gas source 118 via the gas delivery line 120.

[0047] The gas delivery line 120 is configured to deliver the reducing gas 130 from the reducing gas source 118 to a welding region (e.g., including the welding position 402c) of the welding system 400, wherein the reducing gas 130 is configured to be used during welding of the semiconductor element 112 to the substrate 104 at the welding region. Figure 4In the illustrated embodiment, the gas delivery line 120 is configured to provide the reducing gas 130 (e.g., via the manifold 214) to the support structure 102. A heating element 120a is provided for increasing the temperature of the gas delivery line 120, and thus, the temperature of the reducing gas 130 flowing through the gas delivery line 120 before the reducing gas 130 reaches the welding area.

[0048] Reference now Figure 5A , a welding system 500 is shown. The welding system 500 includes: a substrate source 500a (e.g., a wafer handler or other source) for providing a substrate 104 (e.g., a wafer, a printed circuit board, etc.) on a support structure 500a1; and a processing system 500b. The substrate 104 is configured to be transferred to the processing system 500b (e.g., including a tunnel 502). The tunnel 502 includes a substrate oxide reduction chamber 502a, a substrate oxide prevention chamber 502b, and a welding position 502c (which is a part of the substrate oxide prevention chamber 502b). A reducing gas delivery system 508 (including the welding head manifold 114 described below) is also included in the processing system 500b.

[0049] exist Figure 5A In the example shown, at least a portion of the substrate oxide reduction chamber 502a has a common boundary with the substrate oxide prevention chamber 502b because the tunnel 502 includes both the substrate oxide reduction chamber 502a and the substrate oxide prevention chamber 502b. The substrate oxide reduction chamber 502a is closed using an entrance door 502a1 (which closes the opening 502a1a) and an exit door 502a2 (which closes the opening 502a2a). Another reducing gas delivery system 502d provides a reducing gas 130 (e.g., formic acid vapor) to the substrate oxide reduction chamber 502a. In the embodiment shown in FIG. Figure 5A In the example shown, reducing gas delivery system 508 and reducing gas delivery system 502d receive reducing gas from reducing gas source 118 .

[0050] After processing in the substrate oxide reduction chamber 502a (e.g., removing oxide from the conductive structure of the substrate 104), the substrate 104 is transferred to the substrate oxide prevention chamber 502b through the exit door 502a2 using a substrate transfer system (which can be part of a material handling system including the support structure 102). The substrate oxide prevention chamber 502b includes an inert environment 506 (e.g., via a nitrogen supply, not shown for simplicity). The material handling system (e.g., including the support structure 102) is used to move the substrate 104 within the substrate oxide prevention chamber 502b to the welding position 502c. When at the welding position 502c, the reducing gas 130 is provided by the reducing gas delivery system 508.

[0051] The welding system 500 also includes a welding head assembly 106, which includes a heater 108 and a welding tool 110 (see Figure 1 for a more detailed description of the weld head assembly). Figure 5A Also shown is a main exhaust 504 which is connected to the main exhaust through pipes 504a and 114b1 (where pipe 114b1 is directly or indirectly coupled to Figure 1 The weld head assembly 106 carries a weld head manifold 114 for receiving and distributing fluids (eg, gases, vapors, etc.) as required in a given application.

[0052] The gas delivery line 120 is configured to deliver the reducing gas 130 from the reducing gas source 118 to (i) the reducing gas delivery system 508 (and / or the welding head manifold 114) and (ii) the reducing gas delivery system 502d. Thus, the gas delivery line 120 delivers the reducing gas 130 from the reducing gas source 118 to the welding area (e.g., including the welding position 502c) via the reducing gas delivery system 508. The reducing gas 130 is configured to be used during welding (e.g., thermocompression welding, flip chip welding, etc.) of the semiconductor element 112 to the substrate 104. Figure 5A (and Figure 5B ), the gas delivery line 120 is further configured to deliver the reducing gas 130 to the substrate oxide reduction chamber 502a via the reducing gas delivery system 502d. The substrate oxide reduction chamber 502a is configured to receive the substrate 104 before the semiconductor element 112 is soldered to the substrate 104.

[0053] A heating element 120a is provided for increasing the temperature of the gas delivery line 120 and, in turn, increasing the temperature of the reducing gas 130 flowing through the gas delivery line 120 before the reducing gas 130 reaches the welding area.

[0054] With respect to the soldering operation, the semiconductor component 112 (which is carried by the soldering head assembly 106 into the tunnel 502 through the opening 502e) is soldered to the substrate 104 using the soldering tool 110. During the soldering operation, corresponding conductive structures of the plurality of conductive structures of the semiconductor component 112 are soldered (e.g., using heat, force, ultrasonic energy, etc.) to corresponding conductive structures of the conductive structures of the substrate 104. The soldering head manifold 114 provides a reducing gas 130 (e.g., where the reducing gas is a saturated vapor gas) in the region of the semiconductor component 112 and the substrate 104 in connection with the soldering operation (in the example shown, the reducing gas 130 is able to enter the tunnel 502 through the opening 502e). After the reducing gas 130 is distributed in the region of the semiconductor component 112 and the substrate 104, the reducing gas 130 contacts the surface of each of the conductive structures of the semiconductor component 112 and the substrate 104.

[0055] Figure 5B A welding system 500' is shown. The welding system 500' is the same as the welding system 500, except that the welding system 500 shows multiple branches of the gas delivery line 120 (and multiple heating elements) extending from the reducing gas source 118, while the welding system 500' shows a single gas delivery line (and a single heating element 120a) extending from the reducing gas source 118 and then branching into two portions of the gas delivery line 120 (i.e., one branch of the gas delivery line extends to the substrate oxide reduction chamber 502a, and the other branch of the gas delivery line 120 is connected to the manifold 214). Therefore, while being delivered from the reducing gas source 118, the reducing gas 130 passes through the single heating element 120a in the welding system 500' and the multiple heating elements 120a in the welding system 500.

[0056] Reference now Fig. 6A , shows a welding system 600. The welding system 600 is similar in many respects to Figure 5A The welding system 500 and Figure 2 2 , wherein like elements have the same reference numerals or numbers beginning with "6" are substituted for "5," "2," or "1" (unless otherwise expressly indicated). Soldering system 600 is substantially soldering system 500, except that processing system 600b includes reducing gas delivery system 608 (including manifold 214 and associated structures) in place of reducing gas delivery system 508 (including weld head manifold 114 and associated structures) of processing system 500b. Soldering system 600 includes substrate source 600a (e.g., wafer handler or other source) for providing substrate 104 (e.g., wafers, printed circuit boards, etc.) on support structure 600a1. Substrate 104 is configured to be transferred to processing system 600b (e.g., including tunnel 602). Tunnel 602 (or another structure as desired) includes substrate oxide reduction chamber 602a, substrate oxide prevention chamber 602b, and soldering position 602c (which is a portion of substrate oxide prevention chamber 602b).

[0057] exist Fig. 6AIn the example shown, at least a portion of the substrate oxide reduction chamber 602a has a common boundary with the substrate oxide prevention chamber 602b because the tunnel 602 includes both the substrate oxide reduction chamber 602a and the substrate oxide prevention chamber 602b. A reducing gas delivery system 608 is also included in the processing system 600b. The substrate oxide reduction chamber 602a is closed using an entrance door 602a1 (which closes the opening 602a1a) and an exit door 602a2 (which closes the opening 602a2a). Another reducing gas delivery system 602d (which is shown as being indirectly interconnected with the reducing gas delivery system 608 to use a common reducing gas source, i.e., the reducing gas source 118) provides a reducing gas 130 (e.g., formic acid vapor) in the substrate oxide reduction chamber 602a. After processing in the substrate oxide reduction chamber 602a (e.g., removing oxide from the conductive structure of the substrate 104), the substrate 104 is transferred through the opening 602a2a to the substrate oxide prevention chamber 602b using a substrate transfer system (which can be part of a material handling system including the support structure 102). The substrate oxide prevention chamber 602b includes an inert environment 606 (e.g., via a nitrogen supply, not shown for simplicity). The material handling system (e.g., including the support structure 102) is used to move the substrate 104 within the substrate oxide prevention chamber 602b to a welding position 602c. When at the welding position 602c, a reducing gas 130 is provided by a reducing gas delivery system 608.

[0058] Fig. 6A Also shown is a welding head assembly 106 including a heater 108 and a welding tool 110 (see FIG. Figure 1 Detailed description of FIG. 1 ). The soldering tool 110 is capable of carrying the semiconductor element 112 through the opening 602e in connection with the soldering operation. Fig. 6A Also shown is a main exhaust 604 that draws exhaust gas (eg, gas such as reducing gas vapor) through conduits 604a and 604b. A manifold 214 is provided for receiving and distributing fluids (eg, gas, vapor, etc.) as required in a given application.

[0059] The gas delivery line 120 is configured to deliver the reducing gas 130 from the reducing gas source 118 to the reducing gas delivery system 608 and then to the bonding area (e.g., including the bonding position 602c), wherein the reducing gas 130 is configured to be used during the bonding (e.g., thermocompression bonding, flip chip bonding, etc.) of the semiconductor element 112 to the substrate 104. Fig. 6A (and Figure 6B), the gas delivery line 120 is configured to deliver the reducing gas 130 to the substrate oxide reduction chamber 602a (which is configured to receive the substrate 104) before the semiconductor element 112 is soldered to the substrate 104. In addition, the gas delivery line 120 is configured to deliver the reducing gas 130 to the support structure 102 (e.g., via the manifold 214). A heating element 120a is provided to increase the temperature of the gas delivery line 120, and thus, increase the temperature of the reducing gas 130 flowing through the gas delivery line 120 before the reducing gas 130 reaches the soldering area.

[0060] Figure 6B A welding system 600' is shown. The welding system 600' is the same as the welding system 600, except that the welding system 600 illustrates multiple branches of the gas delivery line 120 (including multiple heating elements 120a) extending from the reducing gas source 118, while the welding system 600' illustrates a single gas delivery line 120 (including a single heating element 120a) extending from the reducing gas source 118 and then branching into two portions of the gas delivery line 120 (i.e., one branch of the gas delivery line 120 extends to the substrate oxide reduction chamber 602a and the other branch of the gas delivery line 120 is connected to the manifold 214). Therefore, while being delivered from the reducing gas source 118, the reducing gas 130 passes through the single heating element 120a in the welding system 600' and the multiple heating elements 120a in the welding system 600.

[0061] Figure 7 is a flow chart illustrating a method of soldering a semiconductor element to a substrate. As will be appreciated by those skilled in the art, certain steps included in the flow chart may be omitted; certain additional steps may be added; and the order of the steps may be altered from the order shown - all within the scope of the present invention.

[0062] In step 700, a reducing gas is directed from a reducing gas source to a welding area of ​​a welding system using a gas delivery line (see FIG. Figures 1 to 4 , FIG. 5A to FIG. 5B , FIG. 6A to FIG. 6B ). In optional step 702, the reducing gas source is heated. In step 704, at least a portion of the gas delivery line is heated. In optional step 706, the reducing gas is directed from the reducing gas source via the additional gas delivery line to the substrate oxide reduction chamber, where the substrate is received prior to step 710 (see FIG. 5A to FIG. 5B , FIG. 6A to FIG. 6B ). In optional step 708, the additional gas delivery line is heated. In step 710, the semiconductor component is soldered to the substrate at the soldering area.

[0063] Various aspects of the present invention relate not only to heating gas delivery lines (or portions thereof), but also to heating manifolds (e.g., manifold 114, manifold 214, etc.) that distribute reducing gas. In the illustrated embodiment, a heating element 120a is shown, which, if desired, can be extended to heat relevant portions of the manifolds (e.g., inner passage 114c of manifold 114, inner passage 214c of manifold 214, etc.). However, it should be understood that separate heating elements can be provided to heat relevant portions of each manifold. Therefore, the portion of the heating element 120a shown in the figure extending into the respective manifold should be considered as part of the same heating element used to heat the gas delivery line, or as a separate heating element.

[0064] Although the invention is illustrated and described herein with reference to particular embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made to the details within the scope and equivalents of the claims without departing from the invention.

Claims

1. A soldering system for soldering a semiconductor element to a substrate, the soldering system comprising: a reducing gas delivery system configured to provide reducing gas to a welding area of ​​the welding system; as well as A gas delivery line is configured to deliver the reducing gas from a reducing gas source to the reducing gas delivery system, at least a portion of the gas delivery line being heated.

2. The welding system according to claim 1, wherein: The reducing gas is formic acid vapor.

3. The welding system according to claim 2, wherein: The formic acid concentration of the formic acid vapor is 4-15%.

4. The welding system of claim 1, further comprising a heating element for heating the gas delivery line.

5. The welding system according to claim 1, wherein: The gas delivery line is heated according to a heat profile.

6. The welding system according to claim 5, wherein: The thermal profile is determined at least in part using the temperature of the reducing gas source.

7. The welding system according to claim 6, wherein: The heat profile includes a temperature greater than a temperature of the reducing gas source.

8. The welding system according to claim 7, wherein: The temperature of the reducing gas source is 20°C-70°C.

9. The welding system according to claim 1, wherein: The reducing gas source is a bubbler type system. 10 . The soldering system according to claim 1 , further comprising a substrate oxide prevention chamber configured to receive a substrate before soldering the semiconductor element to the substrate, the substrate oxide prevention chamber having an inert environment when receiving the substrate.

11. The soldering system of claim 10, further comprising a substrate oxide reduction chamber configured to receive the substrate before the substrate is received by the substrate oxide prevention chamber and configured to receive the reducing gas, and further comprising another reducing gas delivery system configured to provide the reducing gas to the substrate oxide reduction chamber.

12. The soldering system of claim 11, further comprising an additional gas delivery line configured to carry the reducing gas from the reducing gas source to the substrate oxide reduction chamber, wherein at least a portion of the additional gas delivery line is heated.

13. A method for soldering a semiconductor element to a substrate, the method comprising the following steps: (a) using a gas delivery line to direct the reducing gas from a reducing gas source to a welding area of ​​the welding system; (b) heating at least a portion of the gas delivery line; and (c) Soldering the semiconductor element to the substrate at the soldering area.

14. The method according to claim 13, wherein: Step (a) includes delivering the reducing gas to the welding area via a reducing gas delivery system.

15. The method according to claim 13, wherein: The reducing gas is formic acid vapor.

16. The method according to claim 15, wherein: The formic acid concentration of the formic acid vapor is 4-15%.

17. The method according to claim 13, wherein: Step (b) includes heating the gas delivery line according to a heat profile.

18. The method according to claim 17, wherein: The thermal profile is determined at least in part using the temperature of the reducing gas source.

19. The method of claim 13, further comprising the step of heating the reducing gas source.

20. The method according to claim 13, wherein: Step (b) includes heating the gas delivery line using a heating element.

21. The method according to claim 13, wherein: The reducing gas source is a bubbler type system.

22. The method according to claim 13, further comprising the steps of: (d) directing the reducing gas from the reducing gas source to a substrate oxide reduction chamber via an additional gas delivery line, the substrate being received by the substrate oxide reduction chamber prior to step (c); and (e) heating the additional gas delivery line.

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