Patent Application
20240404988
Bonding a semiconductor die to a packaging substrate typically uses flux. However, the use of flux in a bonding process may have adverse effects on the bonded assembly. For example, flux may contain impurities that may contaminate the bonding surfaces. This may lead to poor electrical performance of even device failure. Also, in instances in which the flux is not properly cleaned, flux residue may remain on bonding surfaces and cause reliability issues. The heat and pressure used during the bonding process may cause a semiconductor die or package substrate to warp and cause structural damage, leading to poor alignment and poor electrical performance. In other instances in which the bonding is not performed correctly, the semiconductor die may delaminate from the package substrate, leading to device failure. In addition, flux residue may cause corrosion, oxidation, and other reliability issues over time, reducing the lifespan of the device. Also, improper use of flux may cause poor soldering, which may lead to poor electrical performance and device failure.
Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly. Unless explicitly stated otherwise, each element having the same reference numeral is presumed to have the same material composition and to have a thickness within a same thickness range.
Bonding a semiconductor die to a packaging substrate is a critical step in the manufacturing of electronic devices, as it ensures that the semiconductor die is properly connected to the packaging substrate and may function as intended. One of the most common methods for bonding a semiconductor die to a packaging substrate is by using flux. However, the use of flux may have an adverse effect of inducing structural damages to a bonded assembly. Flux is a chemical substance that is applied to the bonding surface of a semiconductor die and packaging substrate before the two are joined together. The flux is used to remove any oxides or other contaminants on the bonding surfaces, which may prevent a proper bond from forming. Additionally, flux may also act as a lubricant, making it easier to position the semiconductor die on the packaging substrate.
However, the use of flux may also have negative effects on the bonded assembly. The flux may cause structural damage to the semiconductor die and packaging substrate, especially in instances in which the flux is not properly cleaned off after the bonding process. The flux may also cause corrosion to the bonding surfaces, which may weaken the bond and make the assembly more susceptible to failure. The most common type of damage that may be caused by flux is called “die-pad cratering,” which occurs when the flux causes a corrosion in the die-pad of the packaging substrate. This corrosion may create a hole or “crater” that may weaken the bond between the die and the substrate. Another type of damage that may be caused by flux is called “die-pad delamination,” which occurs in instances in which the flux causes the die-pad to separate from the substrate. Die-pad delamination may occur in instances in which the flux is not properly cleaned off the bonding surfaces, or in instances in which the flux causes corrosion to the die-pad. Die-pad cratering and die-pad delamination may both cause a variety of problems such as electrical open circuits, and even die cracking. Generally, the use of flux may also have an adverse effect of inducing structural damages to a bonded assembly.
According to an embodiment of the present disclosure, atmospheric pressure plasma jet (APPJ) treatment may be performed to clean surface contaminants from bonding structures and solder material portions prior to performing a thermocompression bonding (TCB) process between a semiconductor die and a packaging substrate. APPJ treatment can be used in semiconductor fabrication to clean, activate and treat surfaces. APPJ uses a low-temperature plasma, generated at atmospheric pressure, to modify the surface chemistry of a material. Plasma is a state of matter that is created when a gas is ionized, or when its atoms are stripped of some of their electrons, creating mixture of ions, electrons, and neutral particles. Plasma may be created at a variety of pressures, including atmospheric pressure.
The APPJ system typically consists of a plasma generator, a gas feed system, and a nozzle that directs the plasma onto the surface to be treated. The plasma may be generated by introducing a gas, such as argon or oxygen, into the plasma generator, where it is excited by an electrical discharge. The plasma generator may create a plasma, which is then directed through the nozzle and onto the surface to be treated. APPJ may be a non-contact, low-temperature, and low-pressure process, which makes APPJ compatible with a wide range of materials and can be easily integrated into existing semiconductor fabrication processes.
The generated high-energy plasma of an APPJ system may remove contaminants and particles from surfaces, providing a clean surface for subsequent processing steps. The plasma may modify the surface chemistry of a material, increasing the reactivity of the material and making the material more suitable for subsequent processing steps. The plasma may also be used to deposit thin films or change the surface morphology of a material. The plasma may be used to remove or passivate surface oxides and other unwanted surface layers. The plasma may also be used to change the surface energy of a material to improve the adhesion of subsequent layers.
There are several factors that may contribute to the time-consuming nature of APPJ treatment. One factor is the desire for precise control of the plasma parameters, such as temperature, plasma density, and gas flow rate. These parameters should be carefully controlled in order to achieve the desired surface modification without damaging the material being treated. Such control may consume a large amount of time and attention from an operator. In addition, the material surface may further benefit from a careful cleaning and preparation before the APPJ treatment. This may include removing contaminants, roughing up the surface to improve adhesion, or applying a pre-treatment to improve the effectiveness of the plasma treatment. Sequential performance of the APPJ treatment and the bonding process for each bonded pair of a semiconductor die and a packaging substrate may be time-consuming.
According to an aspect of the present disclosure, embodiment apparatus and methods are provided for parallel execution of APPJ treatment and TCB processes over multiple pairs of a respective semiconductor die and a respective packaging substrate. A combination of a stationary plasma treatment system and a mobile plasma treatment system may be used to simultaneously provide plasma treatments on a pair of a semiconductor die and a packaging substrate, while a mobile thermocompressive bonding head performs a TCB process on another pair of a semiconductor die and a packaging substrate. The plasma treatment processes and the bonding process may be performed in a low-oxygen environment. Joint interfaces may be free of bonding line interfaces. Various embodiments disclosed herein may provide time efficient execution of APPJ treatments and TCB processes.
Referring to
The chamber enclosure 31 may comprise a first opening and a second opening. A first door 32 may be provided at the first opening in a manner that provides sealing of a volume that is enclosed by the chamber enclosure 31. A second door 34 may be provided at the second opening in a manner that provides sealing of the volume that is enclosed by the chamber enclosure 31. Suitable door actuation mechanisms may be provided for the first door 32 and the second door 34 so that the first door 32 and the second door 34 may be opened and closed to provide transport of semiconductor packages and packaging substrates in and out of the chamber enclosure 31. While the present disclosure is described using an embodiment in which a first door 32 and a second door 34 are located on opposite sides of the low-oxygen ambient, embodiments are expressly contemplated herein in which the first door 32 and the second door 34 are arranged differently, or merged as a single door.
A thermocompressive bonding head 40 may be provided in the process chamber. The thermocompressive bonding head 40 may be configured to hold and carry a semiconductor package 10 over a stage 90, and to induce reflow of solder material portions 30 on the semiconductor package 10 so that the semiconductor package 10 (e.g., 101, 102, 103) is bonded to a respective packaging substrate 20 (e.g., 201, 202, 203). Generally, the thermocompressive bonding head 40 may include all necessary components that are configured to provide thermocompressive bonding between a semiconductor package 10 and a packaging substrate 20. Generally, a commercially available thermocompressive bonding head may be used.
At least one plasma treatment system 60 configured to generate a respective plasma jet may be located within the process chamber (31, 32, 34). The at least one plasma treatment system 60 may comprise only a single plasma treatment system 60, or may comprise a plurality of plasma treatment systems 60 (such as a first plasma treatment system 601, a second plasma treatment system 602, etc.). Each of the at least one plasma treatment system 60 comprises a respective plasma nozzle 61 configured to generate a respective atmospheric pressure plasma jet containing ions of a respective reducing gas, i.e., a respective gas that may combine with oxygen atoms to de-oxidize a surface. Each plasma nozzle 61 of the at least one plasma treatment system 60 may be configured such that each plasma jet is directed toward solder material portions on a semiconductor package 10 under a pre-bonding clean process. The plasma jet direction (i.e., the flow direction of a plasma jet as ejected from a respective plasma nozzle 61) of each plasma treatment system 60 may be tilted with respect to the vertical direction, and may, or may not, be tilted with respect to the horizontal direction. The tilt angle of each plasma jet direction relative to the horizontal direction may be generally in a range from −89 degrees to +89 degrees, such as from −45 degrees to +45 degrees, although lesser and greater tilt angles may also be used. Generally, the tilt angle θ may be a fixed angle, or may be a in-situ controllable variable angle.
A stage 90 configured to mount a plurality of packaging substrate 20 may be provided within the process chamber (31, 32, 34). In one embodiment, the plurality of packaging substrates 20 may be provided as portions of a wafer 20W, and the stage 90 may be configured to mount a wafer 20W thereupon.
The embodiment bonding apparatus 100 may include various transport systems to move the thermocompressive bonding head 40, the at least one plasma treatment system 60, a plurality of semiconductor packages 10, and a plurality of packaging substrates 20 (which may be provided within a wafer). For example, a first transport system 70 may be configured to transport the thermocompressive bonding head 40 and a selected semiconductor package 10 toward the stage 90, and specifically, to a bonding position selected from a plurality of package bonding positions located above the stage 90. The first transport system 70 may comprise a first horizontal transport system 70H and a first vertical transport system 70V. A second transport system 80 may be configured to transport the at least one plasma treatment system 60 to a respective selected plasma treatment position. The plasma treatment positions for each plasma treatment system 60 may be selected from a plurality of plasma treatment positions. The second transport system 80 may comprise a second horizontal transport system 80H and a second vertical transport system 80V. Each of the transport systems (70, 80) may comprise at least one rail and at least one motorized structure.
Generally, movement of any movable elements within the embodiment bonding apparatus 100 may be controlled by a process controller 300. Further, operation of all elements within an embodiment bonding apparatus 100 may be controlled by the process controller 300. For example, the process controller 300 may be configured to control operation of the at least one plasma treatment system 60 and the thermocompressive bonding head 40.
According to an aspect of the present disclosure, an embodiment bonding apparatus 100 may be configured to perform fluxless solder bonding. In this embodiment, the embodiment bonding apparatus 100 is free of any flux material within a volume of the process chamber (31, 32, 34), and does not include any conduit for flowing any flux material therein or thereupon. In other words, a flux material may not be present within, or on, the exemplary bonding apparatus 100.
To initiate a bonding process, the first door 32 may be opened. In one embodiment, the ambient outside the low-oxygen ambient 29 may be controlled to be similar to the low oxygen ambient so that disturbance to the composition and the pressure of the low-oxygen ambient 29 may be minimized. A plurality of semiconductor packages 10 may be loaded into the chamber enclosure 31. In the illustrated example, the plurality of semiconductor packages 10 may comprise a first semiconductor package 101, a second semiconductor package 102, and a third semiconductor package 103. While the present invention is described using an embodiment in which three semiconductor packages 10 (e.g., 101, 102, 103) may be loaded into the chamber enclosure 31, embodiments are expressly contemplated herein in which two or more than three semiconductor packages 10 may be loaded into the chamber enclosure 31 at a time. The total number of semiconductor packages 10 loaded into the chamber enclosure 31 may be in a range from 2 to 1013, although a greater number may also be used.
As used herein, a semiconductor package 10 refers to any of a semiconductor die that functions as a stand-alone package, or a composite package including an interposer and at least one semiconductor die. In one embodiment, one, a plurality, and/or each, of the semiconductor packages 10 loaded into the chamber enclosure 31 may comprise a respective fan-out package including at least one semiconductor chip and an interposer.
A plurality of packaging substrates 20 (e.g., 201, 202, 203) may be loaded into the chamber enclosure 31. In the illustrated example, the plurality of packaging substrates 20 may comprise a first packaging substrate 201, a second packaging substrate 202, and a third packaging substrate 203. While the present invention is described using an embodiment in which three packaging substrates 20 may be loaded into the chamber enclosure 31, embodiments are expressly contemplated herein in which two or more than three packaging substrates 20 may be loaded into the chamber enclosure 31 at a time. The total number of packaging substrates 20 loaded into the chamber enclosure 31 may be in a range from 2 to 1013, although a greater number may also be used. In one embodiment, the number of the packaging substrates 20 that are loaded into the chamber enclosure 31 may be the same as the number of semiconductor packages 10 that are loaded into the chamber enclosure 31.
In one embodiment, the plurality of packaging substrates 20 may be provided as portions of a wafer 20W. In one embodiment, the wafer 20W may comprise a two-dimensional array of packaging substrates 20. In the illustrated example, the wafer 20W comprises a first packaging substrate 201, a second packaging substrate 202, and a third packaging substrate 203 therein. The various packaging substrates 20 may be portions of the wafer 20W that are laterally spaced apart from one another.
In one embodiment, each of the semiconductor packages 10 may comprise package-side bonding structures 18 to which solder material portions 30 are attached. For example, the first semiconductor package 101 may comprise first package-side bonding structures 18 to which first solder material portions 30 are attached, the second semiconductor package 102 may comprise second package-side bonding structures 18 to which second solder material portions 30 are attached, and the third semiconductor package 103 may comprise third package-side bonding structures 18 to which third solder material portions 30 are attached.
In one embodiment, each of the packaging substrates 20 may comprise substrate-side bonding structures 28. For example, the first packaging substrate 201 may comprise first substrate-side bonding structures 28, the second packaging substrate 202 may comprise second substrate-side bonding structures 28, and the third packaging substrate 203 may comprise third substrate-side bonding structures 28.
Generally, the semiconductor packages 10 and the packaging substrates 20 may be loaded into the process chamber (31, 32, 34) while the first door 32 is open. While the present disclosure is described using an embodiment in which solder material portions 30 are attached to semiconductor packages 10, embodiments are expressly contemplated herein in which the solder material portions 30 are attached to the packaging substrates 20. As discussed above, no flux material is present on the solder material portions 30, the semiconductor packages 10, or the packaging substrates 20.
Referring to
The at least one plasma treatment system 60 may be transported to an initial first package clean position such that each plasma nozzle 61 of the at least one plasma treatment system 60 may be directed sideways toward the first solder material portions 30 bonded to the first semiconductor package 101. In embodiments in which the at least one plasma treatment system 60 comprises a plurality of plasma treatment systems 60, the plurality of plasma treatment systems 60 may be positioned around the first semiconductor package 101. In one embodiment, the plurality of plasma treatment systems 60 may be azimuthally spaced apart from one another around a vertical axis passing through a geometrical center of the thermocompressive bonding head 40.
Referring to
In one embodiment, the at least one plasma treatment system 60 comprise a plurality of plasma treatment systems 60, and each of the at least one first plasma jet P may be directed to the first solder material portions 30 throughout the first plasma package-treatment process. In one embodiment, each plasma nozzle 61 of the at least one plasma treatment system 60 may be directed to the first solder material portions 30 along at least one respective non-vertical direction throughout the first plasma package-treatment process.
The at least one plasma treatment system 60 may be any type of plasma treatment system configured to clean surfaces of solder material portions or bonding structures on a semiconductor package. The plasma nozzle 61 of each plasma treatment system 60 may be a line-type plasma nozzle, a matrix-type plasma nozzle, a round plasma nozzle, a rectangular plasma nozzle, or a plasma nozzle having an irregular shape.
Each plasma nozzle 61 of a plasma treatment system 60 comprises at least one plasma outlet, which may be a plurality of plasma outlets. During the first plasma package-treatment process, the vertical distance between each plasma nozzle 61 of the at least one plasma treatment system 60 and the first solder material portions 30 on the first semiconductor package 101 may be in a range from 1 mm to 50 mm, although lesser and greater vertical distances may also be used. In one embodiment, the lateral distance between the outermost edge of the solder material portions 30 and a most proximal portion of each plasma nozzle 61 may be in a range from 1 mm to 200 mm, although lesser and greater lateral distances may also be used.
The at least one plasma treatment system 60 forms a reducing plasma (i.e., a de-oxidizing plasma) around the first solder material portions 18 by generating a plasma jet P, which is an atmospheric pressure plasma jet (APPJ). Generally, an atmospheric pressure plasma jet (APPJ) may be generated by passing a gas (such as air, argon, or helium) through a high voltage electrical discharge. The resulting plasma is composed of highly reactive species, such as ions and radicals, which may be used for a variety of industrial and research applications. In one embodiment of the present disclosure, the first APPJ and the second APPJ are used for surface cleaning. Specifically, ions in each plasma jet P are directed towards the first solder material portions 30 to clean the surfaces of the first solder material portions 30. The high energy species in the plasma interact with the surfaces, thereby breaking down, and removing, contaminants on the first solder material portions 30. In one embodiment, each plasma jet P uses ions of a reducing gas to reduce and/or remove contaminants (such as oxygen or water vapor) on the surfaces of the first solder material portions 30. A reducing gas is mixed with a respective plasma jet P, and the resulting reactive species are directed towards the surfaces to be cleaned, effectively reducing and removing the contaminants on the surfaces.
Embodiment reducing gases that may be used to for each plasma jet P from the at least one plasma treatment system 60 may include, but are not limited, to hydrogen, various hydride gases (such as methane, ammonia, acetylene, etc.), carbon monoxide, and various volatile compounds including hydrogen radicals. Hydrogen gas is a strong reducing agent and may be used to remove oxides, sulfates, and other contaminants from surfaces. Methane is a hydrocarbon gas that may be used to remove carbon-based by contaminants from surfaces. Ammonia is a weak reducing agent that may be used to remove nitrides and other nitrogen-based contaminants from surfaces. Carbon dioxide may be used to remove organic contaminants from surfaces. Nitrogen may be used to remove oxygen-based contaminants. Propane is a hydrocarbon gas that may be used to remove carbon-based contaminants from surfaces. In some other embodiments, non-reducing gases such as argon and helium may be optionally used to cool down the plasma, and/or to protect the plasma jet and to improve the plasma properties. Generally, any ion that acts as a reducing agent may be used. Each atmospheric pressure plasma jets generated by the at least one plasma treatment system 60 does not need to be at an “atmospheric” pressure, but may be any pressure that may be used to generate the condition of an atmospheric pressure plasma jet known in the art.
The temperature of the low-oxygen ambient 29 in the process chamber (31, 32, 34) is lower than the reflow temperature of the solder material portions 30. The temperature of the low-oxygen ambient 29 may be in range from 10 degrees Celsius to 450 degrees Celsius, and may be in a range from 10 degrees Celsius to 200 degrees Celsius, such as from 10 degrees Celsius to 100 degrees Celsius. Generally, the first plasma package-treatment process may be performed on the first semiconductor package 101 in the low-oxygen ambient 29 having an oxygen partial pressure that is lower than 17 kPa.
Generally, the process controller 300 comprises a processor and a memory in communication with the processor, and is loaded with a program that controls locations and angles of each component within the exemplary bonding apparatus 100.
Subsequently, the first semiconductor package 101 may be transported toward the first packaging substrate 201. For example, the combination of the thermocompressive bonding head 40 and the first semiconductor package 101 may be vertically moved toward the first packaging substrate 201 to reduce the vertical distance between the first semiconductor package 101 and the first packaging substrate 201 until the first semiconductor package 101 is positioned at a first bonding position at which thermocompressive bonding with the first packaging substrate 201 may be performed. The first transport system 70 may be used to transport the combination of the thermocompressive bonding head 40 and the first semiconductor package 101 to the first bonding position.
In one embodiment, the first semiconductor package 101 moves along a vertical direction toward the first semiconductor package 101 in a first plasma treatment step during the first plasma package-treatment process. In one embodiment, the at least one first plasma jet P is generated by at least one plasma treatment system 60 having a respective plasma nozzle 61, and the at least one plasma treatment system 60 moves along the vertical direction at a same speed as the first semiconductor package 101 during the first plasma treatment step.
In one embodiment, the second transport system 80 may be configured to transport the at least one plasma treatment system 60 at a same speed as the first semiconductor package 101 while the first semiconductor package 101 is transported toward the stage 90. Generally, the controller 300 may be loaded with an automated program to control synchronous movement of the at least one plasma treatment system 60 and the combination of the thermocompressive bonding head 40 and the first semiconductor package 101. The first plasma treatment step of the first plasma package-treatment process may be continued throughout the movement of the first semiconductor package 101. The first solder material portions 30 may be cleaned by the first plasma jet P during transport of the first semiconductor package 101 toward the first packaging substrate 201 loaded on the stage 90. In one embodiment, the tilt angle q of the nozzle direction of the at least one plasma treatment system 60 may remain constant during transport of the combination of the thermocompressive bonding head 40 and the first semiconductor package 101 to the first bonding position.
Referring to
In one embodiment, the at least one first plasma jet P is generated by at least one plasma treatment system 60 having a respective plasma nozzle 61, and each plasma nozzle 61 of the at least one first plasma treatment system 60 changes a respective nozzle direction such that the at least one first plasma jet P is directed at the first solder material portions 30 during a vertical movement of the first semiconductor package 101 toward the stage 90. After the first semiconductor package 101 reaches the first bonding position at which thermocompressive bonding with the first packaging substrate 201 may be performed, each first plasma jet P may be directed toward first substrate-side bonding structures 28 which are located on a surface of the first packaging substrate 20.
Referring to
Generally, the first solder material portions 30 may be brought onto, or in proximity to, the first substrate-side bonding structures 28 while the at least one first plasma jet P is directed to the first solder material portions 30. The first substrate-side bonding structures are treated with the first plasma jet P prior to bonding the first semiconductor package 101 to the first packaging substrate 201.
In one embodiment, the first semiconductor package 101 remains stationary after the first semiconductor package 101 is brought onto, or in proximity to, the first substrate-side bonding structures 28 during the second plasma treatment step of the first plasma package-treatment process. According to an aspect of the present disclosure, the first solder material portions 30 and the first substrate-side bonding structures 28 may be simultaneously treated with the at least one first plasma jet P.
Subsequently, a first bonding process may be performed to bond the first solder material portions 30 of the first semiconductor package 101 to the first substrate-side bonding structures 28 (which may be bonding pads such as controlled collapse chip connection bonding pads). The bonding processes used in the present disclosure may be fluxless bonding processes. In this embodiment, the first solder material portions 30 and the first substrate-side bonding structures 28 are not in contact with any flux material prior to, and during, the first plasma package-treatment process that bonds the first semiconductor package 101 to the first packaging substrate 201.
Generally, the first semiconductor package 101 may be bonded to the first packaging substrate 201 while, or after, the first substrate-side bonding structures 28 are treated with the first plasma jet P. In one embodiment, the first semiconductor package 101 may be bonded to the first packaging substrate 201 while the first substrate-side bonding structures 28 are treated with the first plasma jet P. In this embodiment, the first bonding process may occur simultaneously with the second plasma treatment step of the first plasma package-treatment process. In another embodiment, the first semiconductor package 101 may be bonded to the first packaging substrate 201 after the first substrate-side bonding structures 28 are treated with the first plasma jet P. In this embodiment, the first bonding process may occur after termination of the first plasma package-treatment process. A first bonded assembly of the first semiconductor package 101 and the first packaging substrate 201 may be formed by the first bonding process.
In embodiments in which the first bonding process may occur simultaneously with the second plasma treatment step of the first plasma package-treatment process, the first plasma jet P may be active during the thermocompressive bonding process. Generally, the volume in which the first plasma jet P is active may include the entire space between the first semiconductor package 101 and the first packaging substrate 201. This volume may have a lateral extent that is greater than the area of the first semiconductor package 101 and the area of the first packaging substrate 201. In embodiments in which the at least one plasma treatment system 60 comprises a plurality of plasma treatment systems 60, the plurality of plasma treatment systems 60 may laterally surround the thermocompressive bonding head 40. The range of each first plasma jet P is greater than one half of the lateral extent of the first semiconductor package 101, and the array of first solder material portions 30 may be laterally surrounded by the at least one first plasma jet P during, and prior to, the thermocompressive bonding process. In embodiments in which a single plasma treatment system 60 is used, the range of the first plasma jet P is greater than the lateral extent of the array of first solder material portions 30 so that each of the first solder material portions 30 is exposed to the first plasma jet P. The thermocompressive bonding process may form a bonded assembly including the first semiconductor package 101 and the first packaging substrate 201 such that the joint interfaces do not have any bonding line interfaces.
Referring to
The at least one plasma treatment system 60 may be transported to an initial second package clean position such that each plasma nozzle 61 of the at least one plasma treatment system 60 is directed sideways toward the second solder material portions 30 bonded to the second semiconductor package 102. In embodiments in which the at least one plasma treatment system 60 comprises a plurality of plasma treatment systems 60, the plurality of plasma treatment systems 60 may be positioned around the second semiconductor package 102. In one embodiment, the plurality of plasma treatment systems 60 may be azimuthally spaced apart from one another around a vertical axis passing through a geometrical center of the thermocompressive bonding head 40. In one embodiment, one of the plurality of plasma treatment systems 60 may overlie, and have an real overlap in a plan view with, the bonded assembly of the first semiconductor package 101 and the first packaging substrate 201.
Referring to
Generally, each of the at least one second plasma jet P that is generated by the at least one plasma treatment system 60 (which may be a plurality of plasma treatment systems 60) has a respective plasma nozzle 61 that is directed to the second solder material portions throughout the second plasma package-treatment process. In embodiments in which a plurality of plasma treatment system 60 is used, one of the plurality of plasma treatment systems 60 may be disposed over an assembly of the first semiconductor package 101 and the first packaging substrate 201 during the second plasma package-treatment process on the second semiconductor package 102 with an areal overlap with the first packaging substrate 201 along a vertical direction.
Referring to
The second semiconductor package 102 may be bonded to the second packaging substrate 202 while, or after, the second substrate-side bonding structures 28 are treated with the second plasma jet P. In one embodiment, the second semiconductor package 102 may be bonded to the second packaging substrate 202 while the second substrate-side bonding structures 28 are treated with the second plasma jet P. In this embodiment, the second bonding process may occur simultaneously with the second plasma treatment step of the second plasma package-treatment process. In another embodiment, the second semiconductor package 102 may be bonded to the second packaging substrate 202 after the second substrate-side bonding structures 28 are treated with the second plasma jet P. In this embodiment, the second bonding process may occur after termination of the second plasma package-treatment process. A second bonded assembly of the second semiconductor package 102 and the second packaging substrate 202 may be formed by the second bonding process.
In embodiments in which the second bonding process may occur simultaneously with the second plasma treatment step of the second plasma package-treatment process, the second plasma jet P may be active during the thermocompressive bonding process. Generally, the volume in which the second plasma jet P is active may include the entire space between the second semiconductor package 102 and the second packaging substrate 202. This volume may have a lateral extent that is greater than the area of the second semiconductor package 102 and the area of the second packaging substrate 202. In embodiments in which the at least one plasma treatment system 60 comprises a plurality of plasma treatment systems 60, the plurality of plasma treatment systems 60 may laterally surround the thermocompressive bonding head 40. The range of each second plasma jet P is greater than one half of the lateral extent of the second semiconductor package 102, and the array of second solder material portions 30 may be laterally surrounded by the at least one second plasma jet P during, and prior to, the thermocompressive bonding process. In embodiments in which a single plasma treatment system 60 is used, the range of the second plasma jet P is greater than the lateral extent of the array of second solder material portions 30 so that each of the second solder material portions 30 is exposed to the second plasma jet P. The thermocompressive bonding process may form a bonded assembly including the second semiconductor package 102 and the second packaging substrate 202 such that the joint interfaces do not have any bonding line interfaces.
Referring to
While the present disclosure is described using an embodiment in which the wafer 20W comprises three packaging substrates 20 and three semiconductor packages 10 are used to form three bonded assemblies of a respective semiconductor package 10 and a respective packaging substrate 20, embodiments are expressly contemplated herein in which a single bonded assembly, two bonded assemblies, or four or more bonded assemblies are formed. In embodiments in which three or more packaging substrates 20 are provided within the wafer 20, the three or more packaging substrates 20 may be arranged as a single linear array, or may be arranged as a two-dimensional array including a plurality of rows and columns that may, or may not, be orthogonal to one another. In one embodiment, each packaging substrate 20 in the wafer 20W may be bonded to a respective one of the semiconductor packages 10 that are loaded into the process chamber (31, 32, 34).
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Referring to all drawings and according to various embodiments of the present disclosure, a method of forming a bonded assembly may be provided. The method may include the steps of: providing at least a first packaging substrate 20 in a low-oxygen ambient 29 having an oxygen partial pressure that is lower than 17 kPa; providing at least a first semiconductor package 10 in the low-oxygen ambient 29; performing a first plasma package-treatment process on the first semiconductor package 10 in the low-oxygen ambient 29 by directing at least one first plasma jet P to first solder material portions 30 bonded to the first semiconductor package 10; bringing the first solder material portions 30 onto, or in proximity to, first substrate-side bonding structures 28 located on the first packaging substrate 20 while the at least one first plasma jet P is directed to the first solder material portions 30, whereby the first substrate-side bonding structures 28 are treated with the first plasma jet P; and bonding the first semiconductor package 10 to the first packaging substrate 20 while, or after, the first substrate-side bonding structures 28 are treated with the first plasma jet P.
In one embodiment, the at least one first plasma jet P may be generated by at least one plasma treatment system 60 having a respective plasma nozzle 61 that is directed to the first solder material portions 30. In one embodiment, each plasma nozzle 61 of the at least one plasma treatment system 60 may be directed to the first solder material portions 30 along at least one respective non-vertical direction throughout the first plasma package-treatment process. In one embodiment, the first semiconductor package 10 moves along a vertical direction toward the first packaging substrate package 20 in a first plasma treatment step during the first plasma package-treatment process. In one embodiment, the at least one first plasma jet P may be generated by at least one plasma treatment system 60 having a respective plasma nozzle 61; and the at least one plasma treatment system 60 moves along the vertical direction at a same speed as the first semiconductor package 10 during the first plasma treatment step. In one embodiment, the first semiconductor package 10 may remain stationary after the first semiconductor package 10 is brought onto, or in proximity to, the first substrate-side bonding structures 28; and the first plasma package-treatment process comprises a second plasma treatment step during which the first solder material portions 30 and the first substrate-side bonding structures 28 may be simultaneously treated with the at least one first plasma jet P. In one embodiment, the at least one first plasma jet P may be generated by at least one plasma treatment system 60 having a respective plasma nozzle 61; and each plasma nozzle 61 of the at least one first plasma treatment system 60 changes a respective nozzle direction such that the at least one first plasma jet P may be directed at the first solder material portions 30 during a vertical movement of the first semiconductor package 10. In one embodiment, the first solder material portions 30 are not in contact with any flux material prior to, and during, the first plasma package-treatment process. In one embodiment, the first solder material portions 30 and the first substrate-side bonding structures 28 are not in contact with any flux material during bonding of the first semiconductor package to the first packaging substrate. In one embodiment, the method may further include: providing a second packaging substrate 202 in the low-oxygen ambient 29; providing a second semiconductor package 102 in the low-oxygen ambient 29; performing a second plasma package-treatment process on the second semiconductor package 102 in the low-oxygen ambient 29 by directing at least one second plasma jet P to second solder material portions 30 bonded to the second semiconductor package 102; bringing the second solder material portions 30 onto, or in proximity to, second substrate-side bonding structures 28 located on the second packaging substrate 202 while the at least one second plasma jet P may be directed to the second solder material portions 30, whereby the second substrate-side bonding structures 28 are treated with the second plasma jet P; and bonding the second semiconductor package 102 to the second packaging substrate 202 while, or after, the second substrate-side bonding structures 28 are treated with the second plasma jet P. In one embodiment, first packaging substrate 201 and the second packaging substrate 202 are provided within a same wafer 20W and are laterally spaced apart from each other.
Another embodiment is drawn to a method of forming a bonded assembly, the method may include the steps of: providing a wafer 20W comprising at least a first packaging substrate 201 and a second packaging substrate 202 in a low-oxygen ambient 29 having an oxygen partial pressure that is lower than 17 kPa; performing a first plasma package-treatment process on a first semiconductor package 101 in the low-oxygen ambient 29 by directing at least one first plasma jet P to first solder material portions 30 bonded to the first semiconductor package 101; bonding the first semiconductor package 101 to the first packaging substrate 201 while, or after, the first substrate-side bonding structures 28 are treated with the first plasma jet P; performing a second plasma package-treatment process on a second semiconductor package 102 in the low-oxygen ambient 29 by directing at least one second plasma jet P to second solder material portions 30 bonded to the second semiconductor package 102; and bonding the second semiconductor package 102 to the second packaging substrate 202 while, or after, the second substrate-side bonding structures 28 are treated with the second plasma jet P.
In one embodiment, the method may include bringing the first solder material portions 30 onto, or in proximity to, the first substrate-side bonding structures 28 while the at least one first plasma jet P may be directed to the first solder material portions 30, whereby the first substrate-side bonding structures 28 are treated with the first plasma jet P at least prior to bonding the first semiconductor package 101 to the first packaging substrate 201. In one embodiment, the method may include bringing the second solder material portions 30 onto, or in proximity to, the second substrate-side bonding structures 28 while the at least one second plasma jet P is directed to the second solder material portions 30, whereby the second substrate-side bonding structures 28 are treated with the second plasma jet P at least prior to bonding the second semiconductor package 102 to the second packaging substrate 202. In one embodiment, each of the at least one first plasma jet P and the at least one second plasma jet P is generated by a plurality of plasma treatment systems 60 having a respective plasma nozzle 61 that is directed to the first solder material portions 30 or to the second solder material portions 30 during operation; and one of the plurality of plasma treatment systems 60 is disposed over an assembly of the first semiconductor package 101 and the first packaging substrate 201 during the second plasma package-treatment process on the second semiconductor package 102 with an areal overlap with the first packaging substrate 201 along a vertical direction.
In another embodiment, an apparatus for forming a bonded assembly is provided. The apparatus comprises: a process chamber (31, 32, 34) including chamber enclosure 31 and an ambient control system configured to provide a low-oxygen ambient 29 having an oxygen partial pressure that is lower than 17 kPa; a stage 90 located in the process chamber (31, 32, 34) and configured to hold at least one packaging substrate 20 thereupon; a thermocompressive bonding head 40 located in the process chamber (31, 32, 34) and configured to hold and carry a semiconductor package 10 over a stage 90, and to induce reflow of solder material portions 30 on the semiconductor package 10; at least one plasma treatment system 60 located within the process chamber (31, 32, 34) and configured to generate a respective plasma jet P along a respective direction toward the solder material portions 30; a first transport system 70 configured to transport the thermocompressive bonding head 40 and the semiconductor package 10 toward the stage 90; and a process controller 300 configured to operate the at least one plasma treatment system 60 such that the respective plasma jet P is generated while the semiconductor package 10 is transported toward the stage 90.
In one embodiment, a second transport system 80 may be configured to transport the at least one plasma treatment system 60 at a same speed as the semiconductor package 10 while the semiconductor package 10 is transported toward the stage 90. In one embodiment, at least one plasma treatment system 60 comprises a respective plasma nozzle 61; and each plasma nozzle 61 of the at least one first plasma treatment system 60 changes a respective nozzle direction such that the respective plasma jet P is directed at the solder material portions 30 while the semiconductor package 10 is transported toward the stage 90. In one embodiment, the process controller 300 configured to operate the at least one plasma treatment system 60 such that the respective plasma jet P is directed toward a surface of one of the at least one packaging substrate 20 on the stage 90 after the semiconductor package 10 is transported to a bonding position overlying the one of the at least one packaging substrate 20. In one embodiment, the apparatus is free of any flux material within a volume of the process chamber (31, 32, 34), and does not include any conduit for flowing any flux material therein or thereupon.
The various embodiments of the present disclosure may be used to provide fluxless bonding of at least two pairs of semiconductor packages 10 and packaging substrates 20. Each pair of a semiconductor package 10 and a packaging substrate 20 may be cleaned using plasma treatment processes in a same low-oxygen ambient 29 without using any flux. Problems associated with use of flux during bonding may be avoided through use of the methods and the apparatus of the present disclosure.
The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.
