Method for forming conductive lines with controlled thermal expansion coefficient

Abstract

Disclosed is a method for forming a conductive line having a controlled coefficient of thermal expansion (CTE). The method includes the step of coating a suspension onto the surface of a substrate. The suspension comprises a solvent and a solid component, the solid component comprising a mixture of at least two types of conductive nanoparticles. The method further includes the steps of sintering the suspension to form a conductive line and removing the unsintered portion of the suspension. The at least two types of conductive nanoparticles include a first type of conductive nanoparticle having a positive CTE and a second type of conductive nanoparticle having a different CTE from the first type of conductive nanoparticle. The ratio of the at least two types of conductive nanoparticles determines the final CTE of the conductive line.

Description

Technical Field

[0001] The present disclosure generally relates to semiconductor devices, and more particularly to a method for forming conductive lines with a controlled coefficient of thermal expansion.

Background Art

[0002] The continuous growth and development of the semiconductor industry aim to minimize the size of electronic devices while improving their performance and yield by manufacturing highly integrated systems. For example, by designing multiple integrated circuit chips within a single module. Typically, the integrated circuit chips are packaged and then mounted on a printed circuit board (PCB). The package includes contacts that enable electrical interconnection between the integrated circuit chip and the PCB. In particular, thin wire bonds are used to electrically connect each integrated circuit chip (e.g., its input / output ports) to the bonding points of the package, enabling its function. Wire bonds provide high flexibility in forming electrical interconnections and involve a cost-effective production method. However, since the input / output ports of wire bonds are formed in the peripheral region (e.g., the periphery) of the integrated circuit chip, the number and density of the input / output ports are limited. Furthermore, the length of the wire bonds increases the electrical resistance and energy loss, thereby increasing the power consumption and causing excessive heat formation by the electronic device.

Summary of the Invention

[0003] Aspects of the present disclosure relate to semiconductor devices, according to some embodiments thereof. More specifically, without limitation, aspects of the present disclosure relate to a method for forming conductive lines with a controlled coefficient of thermal expansion, according to some embodiments thereof.

[0004] According to several embodiments, a method for forming a conductive line with a controlled coefficient of thermal expansion (CTE) is provided. Advantageously, in some embodiments, controlling the CTE in a semiconductor device such as an integrated circuit minimizes / prevents thermal stress between one or more electronic components or elements, thereby minimizing / preventing cracks and undesirable deformations (e.g., bending, twisting, etc.) of one or more electronic components / elements, thereby improving the performance, yield, and reliability of the electronic device.

[0005] Advantageously, in some embodiments, adjusting the CTE allows for the incorporation of various materials into electronic devices (for example, introducing various materials into integrated circuits), thereby matching the CTE with various components, which improves the performance and yield of electronic devices.

[0006] Advantageously, in some embodiments, adjusting the CTE facilitates thermal management of semiconductor / electronic devices. Advantageously, in some embodiments, adjusting the CTE facilitates heat dissipation from semiconductor / electronic devices and / or their components.

[0007] Advantageously, in some embodiments, the methods disclosed herein enable determining the resolution of a conductive line having a controlled CTE during formation, thereby enabling obtaining a conductive line with a line / spatial resolution of at least about 5 / 5 μm.

[0008] According to several embodiments, a method is provided for forming a conductive line with a controlled coefficient of thermal expansion (CTE). The method comprises the step of coating a suspension onto the surface of a substrate, the suspension comprising a solvent and a solid component, the solid component comprising a mixture of at least two types of conductive nanoparticles. The suspension is sintered to form a conductive line, and the unsintered portion of the suspension is removed. The at least two types of conductive nanoparticles include a first type of conductive nanoparticle having a positive CTE and a second type of conductive nanoparticle having a different CTE from the first type of conductive nanoparticle. The ratio of the at least two types of conductive nanoparticles determines the final CTE of the conductive line.

[0009] According to some embodiments, the second type of conductive nanoparticles can have a negative CTE.

[0010] According to some embodiments, the CTE of the second type of conductive nanoparticle may be at least two orders of magnitude lower than the CTE of the first type of conductive nanoparticle.

[0011] According to some embodiments, the CTE of the second type of conductive nanoparticle may be at least three orders of magnitude lower than the CTE of the first type of conductive nanoparticle.

[0012] According to some embodiments, the method may further include drying the suspension to remove the solvent.

[0013] According to some embodiments, sintering can include laser sintering.

[0014] According to some embodiments, sintering can include electron beam sintering.

[0015] According to some embodiments, the first type of conductive nanoparticles may include copper (Cu) nanoparticles.

[0016] According to some embodiments, the second type of conductive nanoparticles may include molybdenum (Mo) nanoparticles.

[0017] According to some embodiments, the final CTE of a conductive line made from or containing a first type of conductive nanoparticles containing copper (Cu) nanoparticles and a second type of conductive nanoparticles containing molybdenum (Mo) nanoparticles is approximately 7.3 ppm / °C, thereby matching the CTE of GaAs.

[0018] According to some embodiments, the second type of conductive nanoparticles can include carbon nanotubes.

[0019] According to some embodiments, the final CTE of a conductive line made from or containing a first type of conductive nanoparticles containing copper (Cu) nanoparticles and a second type of conductive nanoparticles containing carbon nanotubes is approximately 7.3 ppm / °C, thereby matching the CTE of GaAs.

[0020] According to some embodiments, the final CTE of a conductive line made from or containing a first type of conductive nanoparticles containing copper (Cu) nanoparticles and a second type of conductive nanoparticles containing carbon nanotubes is approximately 5.5 ppm / °C, thereby matching the CTE of GaN, AlN, and SiC.

[0021] According to some embodiments, the final CTE of a conductive line made from or containing a first type of conductive nanoparticles containing copper (Cu) nanoparticles and a second type of conductive nanoparticles containing carbon nanotubes is approximately 3.6 ppm / °C, thereby matching the CTE of Si.

[0022] According to some embodiments, the second type of conductive nanoparticles may include nitinol (TiNi) nanoparticles.

[0023] According to some embodiments, the final CTE of a conductive line made of or including a first type of conductive nanoparticles comprising copper (Cu) nanoparticles and a second type of conductive nanoparticles comprising nitinol (TiNi) nanoparticles is about 7.3 ppm / °C, thereby being able to match the CTE of GaAs.

[0024] According to some embodiments, the final CTE of a conductive line made of or including a first type of conductive nanoparticles comprising copper (Cu) nanoparticles and a second type of conductive nanoparticles comprising nitinol (TiNi) nanoparticles is about 5.5 ppm / °C, thereby being able to match the CTE of GaN, AlN, and SiC.

[0025] According to some embodiments, the final CTE of a conductive line made of or including a first type of conductive nanoparticles comprising copper (Cu) nanoparticles and a second type of conductive nanoparticles comprising nitinol (TiNi) nanoparticles is about 3.6 ppm / °C, thereby being able to match the CTE of Si.

[0026] According to some embodiments, the second type of conductive nanoparticles can include tungsten (W) nanoparticles.

[0027] According to some embodiments, the final CTE of a conductive line made of or including a first type of conductive nanoparticles comprising copper (Cu) nanoparticles and a second type of conductive nanoparticles comprising tungsten (W) nanoparticles is about 5.5 ppm / °C, thereby being able to match the CTE of GaN, AlN, and SiC.

[0028] According to some embodiments, the final CTE of a conductive line made of or including a first type of conductive nanoparticles comprising copper (Cu) nanoparticles and a second type of conductive nanoparticles comprising tungsten (W) nanoparticles is about 3.6 ppm / °C, thereby being able to match the CTE of Si.

[0029] According to some embodiments, the line / space resolution of the conductive line can be at least about 5 / 5 um.

[0030] According to some embodiments, the method can further include removing the substrate.

[0031] According to some embodiments, the substrate may be coated.

[0032] According to some embodiments, the solvent of the suspension can be selected from water, ethanol, methanol, isopropanol, ethylene glycol, and diethylene glycol monomethyl ether.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. In case of conflict, the patent specification, including definitions, will control. As used herein, the indefinite articles "a" and "an" mean "at least one" or "one or more" unless the context clearly dictates otherwise.

Brief Description of the Drawings

[0034] Some embodiments of the present disclosure are described herein with reference to the accompanying drawings. The description, together with the drawings, will make clear to those skilled in the art how some embodiments can be implemented. The drawings are for illustrative purposes only and are not intended to show the structural details of the embodiments in more detail than is necessary for a basic understanding of the present disclosure. For clarity, some of the objects shown in the drawings are not drawn to scale. Further, two different objects in the same figure may be drawn to different scales. In particular, the scale of some objects may be greatly exaggerated compared to other objects in the same figure. [Figure 1] FIG. 1 schematically illustrates an example of an additive process for forming a conductive line according to some embodiments.

Modes for Carrying Out the Invention

[0035] (Detailed explanation) The principles, use, and implementation of the teachings herein can be better understood by referring to the accompanying description and drawings. A person skilled in the art will be able to implement the teachings herein without excessive effort or experimentation after carefully examining the description and drawings herein.

[0036] In the description and claims of this application, the words “include” and “have,” and their forms, are not limited to members of the list to which the words may be associated.

[0037] As used herein, the term “about” can be used to specify a value of a quantity or parameter (e.g., the length of a member) within a continuous range of values ​​in the vicinity (and including) a given (stated) value. According to some embodiments, “about” can specify a parameter value such that it is between 80% and 120% of a given value. For example, the statement “The length of the member is about 1 m” is equivalent to the statement “The length of the member is between 0.8 m and 1.2 m.” According to some embodiments, “about” can specify a parameter value such that it is between 90% and 110% of a given value. According to some embodiments, “about” can specify a parameter value such that it is between 95% and 105% of a given value.

[0038] As used herein, the terms “substantially” and “about” may be interchangeable according to some embodiments.

[0039] As used herein, according to some embodiments, the terms “conductive line,” “conductive material area,” “conductive region,” “contact pad,” and “conductive pattern” may be interchangeable. According to some embodiments, the conductive line is configured to electrically interconnect, route, and / or reroute integrated circuit devices and / or components thereof, including but not limited to microprocessors, memory devices, chipsets, graphics devices, one or more dies, or any combination thereof.

[0040] According to some embodiments, a conductive line can refer to any conductive element, including but not limited to vias, contacts, nodes, pads (e.g., contact pads, bond pads, etc.), traces, paths, tracks, terminals, ports, etc., or any combination thereof. Each possibility is a separate embodiment. According to some embodiments, a conductive line can refer to and form a redistribution layer (e.g., of an integrated circuit) to facilitate, for example, die lamination / assembly.

[0041] In addition, or alternatively, in some embodiments, the conductive line can form a conductive path (e.g., a vertical electrical connection). According to some embodiments, the conductive line can form various types of vias, including, but not limited to, through vias, tented vias, blind vias, embedded vias, stacked vias, or any combination thereof. Each possibility is a separate embodiment.

[0042] According to some embodiments, the conductive line can refer to any type of metallization region (e.g., a metallization layer on an integrated circuit) configured to electrically interconnect one or more electronic components of the chip.

[0043] According to some embodiments, the conductive line can refer to a conductive area (e.g., via) of an interposer (e.g., a coreless interposer, a 3D interposer, etc.). According to some embodiments, the conductive line can refer to a conductive part / area (e.g., a pad, a via, etc.) of an interposer, chip module, etc.

[0044] According to some embodiments, the conductive line can be configured to form an ohmic contact. According to some embodiments, the conductive line can be configured to form a rectifying (e.g., metal-semiconductor) contact.

[0045] As used herein, according to some embodiments, the term “electronic device” may refer to any device including electronic components, integrated circuits, etc. Examples include, but are not limited to, wearable devices (such as smartwatches and fitness trackers), mobile phones (such as smartphones), tablets, computers (such as laptops), cameras, screens (such as touchscreens), televisions, robots (such as robotic arms), memory devices, power storage devices, light-emitting devices, etc. According to some embodiments, an electronic device may be portable. According to some embodiments, an electronic device may refer to a non-mobile device. According to some embodiments, an electronic device may refer to household appliances, industrial equipment / systems, cars, etc. Each possibility is a distinct embodiment.

[0046] As used herein, according to some embodiments, the term “one or more electronic components” may refer to any circuit and / or electronic components / elements mounted, attached, fixed or otherwise incorporated into an electronic device. According to some embodiments, one or more electronic components may include, among other things, chips, semiconductor dies, semiconductor devices (e.g., transistors), micromechanical systems (MEMS), integrated circuits (e.g., application-specific integrated circuits), memory interfaces, input / output devices, graphics processing units, microprocessors, microcontrollers, logic chips (e.g., analog-to-digital converters), wireless modems, sensors, signal generation circuits, signal conversion circuits, switch circuits, amplification circuits, passive components (inductors, capacitors, etc., etc.), and any combination thereof. Each possibility is a distinct embodiment. According to some embodiments, one or more electronic components may include, among other things, one or more silicon dies, silicon carbide dies (e.g., SiC metal oxide silicon field-effect transistors (MOSFETs)), gallium nitride dies (e.g., bare GaN high electron-mobility transistors (HEMTs), gallium arsenide (GaAs) dies, etc.), or any combination thereof. Each possibility is a distinct embodiment.

[0047] According to several embodiments, a method is provided for forming a conductive line having a controlled coefficient of thermal expansion (CTE). The method comprises the step of coating a suspension onto the surface of a substrate, the suspension comprising a solvent and a solid component, the solid component comprising a mixture of at least two types of conductive nanoparticles. The suspension is dried to remove the solvent, the suspension is sintered to form a conductive line, and any unsintered portions are removed. According to some embodiments, the at least two types of conductive nanoparticles comprises a first type of conductive nanoparticle having a positive CTE and a second type of conductive nanoparticle having a different CTE from the first type of conductive nanoparticle, the ratio of the at least two types of conductive nanoparticles determines the final CTE of the conductive line.

[0048] According to several embodiments, the disclosed method makes it possible to obtain a CTE that matches various materials of integrated circuits, such as Si, GaAs, SiC, GaN, and AlN. Each possibility is a distinct embodiment. Advantageously, in some embodiments, matching the CTE of an integrated circuit minimizes / prevents thermal stress between one or more electronic components or elements within an electronic device, thereby minimizing / preventing cracks and undesirable deformations (e.g., bending, twisting, etc.) of the electronic components / elements of the electronic device, thereby improving the performance, yield, and reliability of the electronic device.

[0049] Advantageously, in some embodiments, by adjusting the CTE, various materials can be incorporated into the electronic components of an electronic device (e.g., integrated circuits), thereby matching the CTE with various components and ultimately improving the performance and yield of the electronic device.

[0050] Advantageously, in some embodiments, adjusting the CTE facilitates thermal management of electronic devices (i.e., promoting heat dissipation).

[0051] Advantageously, in some embodiments, the methods disclosed herein enable determining the resolution of a conductive line having a controlled CTE during formation, and enabling obtaining a conductive line having a line / spatial resolution of at least about 5 / 5 μm.

[0052] Referring to Figure 1, flowcharts 100 of additive manufacturing methods for forming conductive lines according to several embodiments are schematically shown.

[0053] According to some embodiments, the additive manufacturing method may include, among other things, selective laser sintering (SLS) methods (such as direct SLS, direct metal laser sintering (DMLS), selective laser melting (SLM), metal wire 3D printing, electron beam melting (EBM), electron beam sintering, or any other additive manufacturing method). Each possibility is a distinct embodiment. According to some embodiments, the additive manufacturing method may include any type of directed energy deposition method, powder-based fusion additive manufacturing method, or any combination thereof. According to some embodiments, the additive manufacturing method may include micrometal additive manufacturing (MMAM) methods. Each possibility is a distinct embodiment.

[0054] According to some embodiments, step 102 may include obtaining the substrate 124. According to some embodiments, step 102 may optionally include cleaning the substrate 124.

[0055] According to some embodiments, cleaning of the substrate 124 may include performing a plasma surface treatment. According to some embodiments, the plasma surface treatment may be performed by atmospheric pressure plasma. According to some embodiments, cleaning of the substrate 124 may include chemical etching (i.e., wet or dry etching) of the surface of the substrate 124. According to some embodiments, cleaning of the substrate 124 may include dry etching of the surface of the substrate 124. According to some embodiments, cleaning of the substrate 124 may include ultrasonic cleaning. According to some embodiments, cleaning of the substrate 124 may include ozone treatment of the surface of the substrate 124. According to some embodiments, cleaning of the substrate 124 may include any combination of the above-described cleaning methods or any other surface treatment / cleaning methods.

[0056] According to some embodiments, the substrate 124 may be inert. According to some embodiments, the substrate 124 may be made from, or include, glass (e.g., coated glass, uncoated glass, etc.), Si, ceramic material, polymer, stainless steel, etc., or any combination thereof. Each possibility is a separate embodiment.

[0057] According to some embodiments, the carrier substrate 124 may be rigid. In non-limiting examples, the carrier substrate 124 may have a Shore hardness of about 85D to 96D. According to some embodiments, the carrier substrate 124 may be flexible. In non-limiting examples, the carrier substrate 124 may have a Shore hardness of about 45D to 70D. According to some embodiments, the carrier substrate 104 may be semi-rigid (e.g., a composite Shore hardness of a rigid substrate and a flexible substrate). Each possibility is a separate embodiment.

[0058] According to some embodiments, the substrate 124 may be a temporary substrate (i.e., a removable substrate). Alternatively, in some embodiments, the substrate 124 may be a non-temporary substrate.

[0059] According to some embodiments, the substrate 124 may be a coated substrate. According to some embodiments, the coating of the substrate 124 may be configured to facilitate the adhesion of conductive lines. According to some embodiments, the coating of the substrate 124 may be made from, or include, seed layers of TiW and Cu, among other things. According to some embodiments, the substrate 124 may be uncoated.

[0060] According to some embodiments, the substrate 124 may be a substantially flat substrate. According to some embodiments, the substrate 124 may not be flat. For example, the substrate 124 may include a patterned surface (not shown). In a non-limiting example, the patterned surface of the substrate 124 may include gaps, among other things, to form a format of different surface heights.

[0061] According to some embodiments, the method may optionally include applying a coating to the substrate 124 (steps not shown). According to some embodiments, the coating may be applied by a suitable method such as deposition, but is not limited thereto.

[0062] According to some embodiments, step 104 may include coating the surface of the substrate 124 with the suspension 130. According to some embodiments, the suspension 130 may include a solvent and a solid component. According to some embodiments, the solid component may include a mixture of at least two types of conductive nanoparticles.

[0063] According to some embodiments, at least two types of conductive nanoparticles may include two, three, four, five, six, or more types of conductive nanoparticles. Each possibility is a distinct embodiment.

[0064] According to some embodiments, each of at least two types of conductive nanoparticles may have a different particle size. According to some embodiments, the diameter of each of the at least two types of conductive nanoparticles may be in the range of about 10 to 500 nm. According to some embodiments, the diameter of each of the at least two types of conductive nanoparticles may be in the range of about 10 to 500 nm, about 10 to 100 nm, about 10 to 200 nm, about 10 to 300 nm, about 10 to 400 nm, about 50 to 250 nm, about 100 to 500 nm, about 300 to 500 nm, etc. Each possibility is a separate embodiment. As a non-limiting example, a first of the at least two types of conductive nanoparticles may have a diameter of about 10 to 30 nm, and a second of the at least two types of conductive nanoparticles may have a diameter of about 80 to 120 nm.

[0065] Alternatively, or further, in some embodiments, each of at least two types of conductive nanoparticles may have substantially the same particle size. According to some embodiments, the diameter of each of the at least two types of conductive nanoparticles may be in the range of about 10-500 nm, about 10-100 nm, about 10-200 nm, about 10-300 nm, about 10-400 nm, about 50-250 nm, about 100-500 nm, about 300-500 nm, etc. Each possibility is a separate embodiment.

[0066] According to some embodiments, at least two types of conductive nanoparticles may include a first type of conductive nanoparticle having a positive coefficient of thermal expansion (CTE) and a second type of conductive nanoparticle having a different CTE than the first type of conductive nanoparticle. In some embodiments, the different CTE of the second type of conductive nanoparticle may include different values ​​of positive or negative CTE. Each possibility is a distinct embodiment.

[0067] According to some embodiments, the second type of conductive nanoparticles may have a negative CTE.

[0068] According to some embodiments, the CTE of a second type of conductive nanoparticle can be at least one order of magnitude lower than that of a first type of conductive nanoparticle. According to some embodiments, the CTE of a second type of conductive nanoparticle can be at least two orders of magnitude lower than that of a first type of conductive nanoparticle. According to some embodiments, the CTE of a second type of conductive nanoparticle can be at least three orders of magnitude lower than that of a first type of conductive nanoparticle. According to some embodiments, the CTE of a second type of conductive nanoparticle can be at least four orders of magnitude lower than that of a first type of conductive nanoparticle. According to some embodiments, the CTE of a second type of conductive nanoparticle can be at least five orders of magnitude lower than that of a first type of conductive nanoparticle. According to some embodiments, the CTE of a second type of conductive nanoparticle can be about six orders of magnitude or more lower than that of a first type of conductive nanoparticle. Each possibility is a distinct embodiment.

[0069] According to some embodiments, the first type of conductive nanoparticles may include copper (Cu), gold (Au), silver (Ag), nickel (Ni), titanium (Ti), tin (Sn), molybdenum (Mo), tungsten (W), and may include alloys or any combination thereof. Each possibility is a distinct embodiment. As a non-limiting example, the first type of conductive nanoparticles may be made from or include nitinol (NiTi) nanoparticles.

[0070] According to some embodiments, the second type of conductive nanoparticles may include tungsten (W), titanium (Ti), silicon (Si), molybdenum (Mo), germanium (Ge), tantalum (Ta), chromium (Cr), silver (Ag), iron (Fe), vanadium (V), zirconium (Zr), platinum (Pt), and alloys thereof or any combination thereof. Each possibility is a distinct embodiment. As a non-limiting example, the second type of conductive nanoparticles may be made from or include an iron-cobalt-nickel alloy. Each possibility is a distinct embodiment.

[0071] According to some embodiments, the second type of conductive nanoparticles may include carbon-based materials such as carbon nanotubes, carbon nanodots (e.g., carbon quantum dots), carbon nanowires, and fullerenes, and any combination thereof. Each possibility is a separate embodiment. According to some embodiments, the second type of conductive nanoparticles may include any type of carbon allotrope.

[0072] According to some embodiments, the first type of conductive nanoparticles may include copper (Cu) nanoparticles, and the second type of conductive nanoparticles may include carbon nanotubes, molybdenum (Mo) nanoparticles, nitinol (TiNi) nanoparticles, tungsten (W) nanoparticles, and any combination thereof. Each possibility is a separate embodiment.

[0073] According to some embodiments, the ratio of at least two types of conductive nanoparticles may determine the final CTE of the conductive line. According to some embodiments, the ratio of at least two types of conductive nanoparticles may include any of the following: molar ratio, atomic ratio, weight ratio, etc. Each possibility is a distinct embodiment. According to some embodiments, the ratio of at least two types of conductive nanoparticles may include any value in the range of about 5% to about 95% of the first type of conductive nanoparticles and any value in the range of about 95% to about 5% of the second type of conductive nanoparticles. Each possibility is a distinct embodiment.

[0074] According to some embodiments, the suspension may contain at least two types of conductive nanoparticles, comprising about 50% of a first type of conductive nanoparticle and about 50% of a second type of conductive nanoparticle. According to some embodiments, the suspension may contain at least two types of conductive nanoparticles, comprising about 25% of a first type of conductive nanoparticle and about 75% of a second type of conductive nanoparticle. According to some embodiments, the suspension may contain at least two types of conductive nanoparticles, comprising about 20% of a first type of conductive nanoparticle and about 80% of a second type of conductive nanoparticle. According to some embodiments, the suspension may contain at least two types of conductive nanoparticles, comprising about 10% of a first type of conductive nanoparticle and about 90% of a second type of conductive nanoparticle. According to some embodiments, the suspension may contain at least two types of conductive nanoparticles, comprising about 5% of a first type of conductive nanoparticle and about 95% of a second type of conductive nanoparticle. According to some embodiments, the suspension may contain at least two types of conductive nanoparticles, comprising about 3% of a first type of conductive nanoparticle and about 97% of a second type of conductive nanoparticle. According to some embodiments, the suspension may contain at least two types of conductive nanoparticles, comprising about 40% of a first type of conductive nanoparticle and about 60% of a second type of conductive nanoparticle. Each possibility is a distinct embodiment.

[0075] According to some embodiments, the relationship between the ratio of at least two types of conductive nanoparticles in the suspension and the final CTE of the conductive line may not be linear.

[0076] According to some embodiments, the suspension 130 may not contain intermetallic compounds.

[0077] According to some embodiments, the solvent of suspension 130 may include water, ethanol, methanol, isopropanol, ethylene glycol, diethylene glycol monomethyl ether, and the like. Each possibility is a separate embodiment. It can be understood by those skilled in the art that different solvents produce suspensions (e.g., suspension 130) with different viscosities.

[0078] According to some embodiments, the application of the suspension 130 to the carrier 124 can be carried out by an ink spray coater, slot die coater, ultrasonic spin spray coater, spin coater, or any combination thereof. According to some embodiments, the application of the suspension 130 may include doctor blade coating to facilitate the formation of a distinct coating thickness.

[0079] According to some embodiments, step 106 may include, as an optional step of the method, drying the suspension 130 to remove the solvent. According to some embodiments, drying may be carried out by, among other things, a blower, an oven, etc.

[0080] According to some embodiments, step 108 may include sintering the suspension 130 to form conductive lines 132 according to a predetermined pattern. According to some embodiments, the pattern may include conductive lines having a predetermined width, length, and inter-line distance.

[0081] According to some embodiments, the sintering of the suspension 130 may be carried out using a direct laser writer. According to some embodiments, step 108 may include 3D printing, electron beam sintering / melting, laser sintering (e.g., selective laser sintering) or any other additive manufacturing method. Each possibility is a separate embodiment.

[0082] According to some embodiments, the conductive lines 132 can be formed according to a predetermined pattern. According to some embodiments, the line / spatial resolution of the conductive lines 132 can be at least about 5 / 5 μm (i.e., line width about 5 μm, space between lines about 5 μm). According to some embodiments, the line / spatial resolution of the conductive lines 132 can be at least about 4 / 4 μm. According to some embodiments, the line / spatial resolution of the conductive lines 132 can be at least about 3 / 3 μm. According to some embodiments, the line / spatial resolution of the conductive lines 132 can be at least about 2.5 / 2.5 μm. Each possibility is a separate embodiment. According to some embodiments, the resolution of the conductive lines is defined by the manufacturing method of the conductive lines (e.g., laser sintering, electron beam sintering, etc.), so that the complexity of the pattern can be increased while substantially maintaining the resolution.

[0083] According to some embodiments, the conductive line 132 may have a final CTE that is specially obtained / adjusted to match the CTE of a desired electronic component (e.g., die). According to some embodiments, the composition of the solid components of the suspension 130 may define the final CTE of the conductive line 132.

[0084] In particular, in some embodiments, the solid component of the suspension 130 may include at least two types of conductive nanoparticles. According to some embodiments, the at least two types of conductive nanoparticles may include a first type of conductive nanoparticle having a positive CTE and a second type of conductive nanoparticle having a different CTE from the first type of conductive nanoparticle. According to some embodiments, the ratio of the at least two types of conductive nanoparticles can determine the final CTE of the conductive line 132.

[0085] According to some embodiments, the conductive nanoparticles of the solid component of the suspension 130 may include at least two types of nanoparticles, one of a first type and one of a second type. According to some embodiments, the ratio of the first type to the second type of nanoparticles can be about 1:30, about 1:25, about 1:20, about 1:10, about 1:9, about 1:8, about 1:7, about 1:6, about 1:5, about 1:4, about 1:3, about 1:2, about 3:7, about 2:3, about 1:1, and their inverse ratios. Each possibility is a distinct embodiment.

[0086] According to some embodiments, the ratio of at least two types of conductive nanoparticles can include a weight ratio. According to some embodiments, the ratio of at least two types of conductive nanoparticles can include a molar ratio. According to some embodiments, the ratio of at least two types of conductive nanoparticles can include an atomic ratio. Each possibility is a distinct embodiment.

[0087] According to some embodiments, at least two types of conductive nanoparticles may include a first type containing copper (Cu) nanoparticles and a second type containing molybdenum (Mo) nanoparticles. According to some embodiments, the ratio (e.g., by weight) of copper (Cu) nanoparticles to molybdenum (Mo) nanoparticles can determine the final CTE of the conductive line. According to some embodiments, the ratio may include any value in the range of about 5% to about 95% of copper (Cu) nanoparticles and any value in the range of about 95% to about 5% of molybdenum (Mo) nanoparticles. Each possibility is a distinct embodiment. As a non-limiting example, the ratio may include about 50% copper (Cu) nanoparticles and about 50% molybdenum (Mo) nanoparticles. As another non-limiting example, the ratio may include about 20% copper (Cu) nanoparticles and about 80% molybdenum (Mo) nanoparticles.

[0088] According to some embodiments, a ratio of copper (Cu) nanoparticles ranging from about 5% to about 95% and a ratio of molybdenum (Mo) nanoparticles ranging from about 95% to about 5% can lead to a final CTE of about 5.5 ppm / °C for the conductive line, thereby matching the CTE of GaN, AlN, and SiC.

[0089] According to some embodiments, at least two types of conductive nanoparticles may include a first type comprising copper (Cu) nanoparticles and a second type comprising carbon nanotubes (CNTs). According to some embodiments, the ratio of copper (Cu) nanoparticles to CNTs can determine the final CTE of the conductive line. According to some embodiments, the ratio may include any value in the range of about 5% to about 95% for copper (Cu) nanoparticles and any value in the range of about 95% to about 5% for CNTs. Each possibility is a distinct embodiment.

[0090] According to some embodiments, a ratio of approximately 85% to 95% copper (Cu) nanoparticles and approximately 15% to 5% CNTs in the solid component of suspension 130 (e.g., weight ratio, molar ratio, atomic ratio) can determine the final CTE of the conductive line to approximately 7.3 ppm / °C, thereby matching the CTE of GaAs. According to some embodiments, a ratio of approximately 90% copper (Cu) nanoparticles and approximately 10% CNTs in the solid component of suspension 130 can determine the final CTE of the conductive line to approximately 7.3 ppm / °C, thereby matching the CTE of GaAs.

[0091] According to some embodiments, a solid component of suspension 130 containing approximately 40% to 60% copper (Cu) nanoparticles and approximately 60% to 40% carbon nanotubes (CNTs) determines the final CTE of the conductive line to approximately 3.6 ppm / °C, thereby matching the CTE of Si. According to some embodiments, a solid component of suspension 130 containing approximately 50% copper (Cu) nanoparticles and approximately 50% carbon nanotubes (CNTs) determines the final CTE of the conductive line to approximately 3.6 ppm / °C, thereby matching the CTE of Si.

[0092] According to several embodiments, in the solid component of suspension 130, approximately 60% to 80% copper (Cu) nanoparticles and approximately 40% to 20% carbon nanotubes (CNTs) determine the final CTE of the conductive line to approximately 5.5 ppm / °C, thereby matching the CTE of GaN, AlN, and SiC.

[0093] According to some embodiments, at least two types of conductive nanoparticles include copper (Cu) nanoparticles as a first type and nitinol (TiNi) nanoparticles as a second type. According to some embodiments, the ratio of copper (Cu) nanoparticles to nitinol (TiNi) nanoparticles determines the final CTE of the conductive line 132. According to some embodiments, the ratio can include any value in the range of about 5% to about 95% for copper (Cu) nanoparticles and any value in the range of about 95% to about 5% for nitinol (TiNi) nanoparticles. Each possibility is a separate embodiment.

[0094] According to some embodiments, at least two types of conductive nanoparticles include copper (Cu) nanoparticles as a first type and tungsten (W) nanoparticles as a second type. According to some embodiments, the ratio of copper (Cu) nanoparticles to tungsten (W) nanoparticles determines the final CTE of the conductive line 132. According to some embodiments, the ratio can include any value in the range of about 5% to about 95% for copper (Cu) nanoparticles and any value in the range of about 95% to about 5% for tungsten (W) nanoparticles. Each possibility is a separate embodiment.

[0095] According to some embodiments, the final CTE of the conductive line 132 is approximately 7.3 ppm / °C, thereby matching the CTE of GaAs. According to some embodiments, the final CTE of the conductive line 132 is approximately 5.5 ppm / °C, thereby matching the CTE of GaN, AlN, and SiC. According to some embodiments, the final CTE of the conductive line 132 is approximately 3.6 ppm / °C, thereby matching the CTE of Si. Each possibility is a separate embodiment. According to some embodiments, the final CTE of the conductive line 132 is adjusted to obtain a substantially required CTE to match other components of the wafer or integrated circuit.

[0096] According to some embodiments, in step 110, the method may include removing / washing away the non-sintered portion of the suspension 130, thereby revealing / obtaining the conductive line 132.

[0097] According to some embodiments, the method may omit a step involving the subtraction of material. According to some embodiments, the method may omit drilling, etching, or any combination thereof.

[0098] According to some embodiments, the method is a complete additive method for forming conductive lines. Alternatively, in some embodiments, the method may be carried out as part of a semi-additive method, such as photolithography for integrated circuit manufacturing. Each possibility is a distinct embodiment.

[0099] The steps of the method may be described in a specific order according to some embodiments, but the method of this disclosure may include some or all of the described steps which are performed in a different order. In particular, it should be understood that the order of any of the stages and substages of the described method may be rearranged, except, for example, when a later stage requires an output or input of a earlier stage, or when a later stage requires the product of a earlier stage, unless the context otherwise explicitly indicates otherwise. The method of this disclosure may include some or all of the described steps. No particular step in the disclosed method should be considered an essential step of the method unless it is expressly designated as such.

[0100] While this disclosure is described in conjunction with its specific embodiments, it is evident that numerous alternative, modified, and variant forms may exist that are apparent to those skilled in the art. Accordingly, this disclosure encompasses all such alternative, modified, and variant forms that fall within the scope of the appended claims. It should be understood that, in its application, this disclosure is not necessarily limited to the details of the configuration and arrangement of the components and / or methods described herein. Other embodiments may be implemented, and embodiments may be carried out in a variety of ways.

[0101] The language and terminology used herein are for illustrative purposes only and should not be construed as limiting. No citation or identification of a citation in this application shall be construed as an admission that such citation is available as prior art of the disclosure. Section headings are used herein to facilitate understanding of this specification and should not be construed as limiting.

Claims

1. A method for forming a conductive line having a controlled coefficient of thermal expansion (CTE), The aforementioned method, A step of coating a suspension onto the surface of a substrate, wherein the suspension comprises a solvent and a solid component, and the solid component comprises a mixture of at least two types of conductive nanoparticles, The steps include: sintering the suspension to form conductive lines, The step includes removing the unsintered portion of the suspension, The at least two types of conductive nanoparticles are, A first type of conductive nanoparticle having positive CTE, A second type of conductive nanoparticle having a different CTE than the first type of conductive nanoparticle, A method wherein the ratio of the at least two types of conductive nanoparticles determines the final CTE of the conductive line.

2. The method according to claim 1, wherein the second type of conductive nanoparticle has a negative CTE.

3. The method according to claim 1, wherein the CTE of the second type of conductive nanoparticle is at least three orders of magnitude lower than the CTE of the first type of conductive nanoparticle.

4. The method according to any one of claims 1 to 3, further comprising the step of drying the suspension to remove the solvent.

5. The method according to any one of claims 1 to 4, wherein the sintering includes laser sintering.

6. The method according to any one of claims 1 to 4, wherein the sintering includes electron beam sintering.

7. The method according to any one of claims 1 to 6, wherein the first type of conductive nanoparticles includes copper (Cu) nanoparticles.

8. The method according to any one of claims 1 to 7, wherein the second type of conductive nanoparticles includes molybdenum (Mo) nanoparticles.

9. The method according to claim 8, wherein the final CTE of the conductive line is approximately 7.3 ppm / °C, which matches the CTE of GaAs.

10. The method according to any one of claims 1 to 7, wherein the second type of conductive nanoparticle comprises a carbon nanotube.

11. The method according to claim 10, wherein the final CTE of the conductive line is about 7.3 ppm / °C, which is consistent with the CTE of GaAs.

12. The method according to claim 10, wherein the final CTE of the conductive line is about 5.5 ppm / °C, which is consistent with the CTE of GaN, AlN, and SiC.

13. The method according to claim 10, wherein the final CTE of the conductive line is about 3.6 ppm / °C, which is consistent with the CTE of Si.

14. The method according to any one of claims 1 to 7, wherein the second type of conductive nanoparticles includes nitinol (TiNi) nanoparticles.

15. The method according to claim 14, wherein the final CTE of the conductive line is approximately 7.3 ppm / °C, which is consistent with the CTE of GaAs.

16. The method according to claim 14, wherein the final CTE of the conductive line is about 5.5 ppm / °C, which is consistent with the CTE of GaN, AlN, and SiC.

17. The method according to claim 14, wherein the final CTE of the conductive line is about 3.6 ppm / °C, which is consistent with the CTE of Si.

18. The method according to any one of claims 1 to 7, wherein the second type of conductive nanoparticle comprises tungsten (W).

19. The method according to claim 18, wherein the final CTE of the conductive line is about 5.5 ppm / °C, which is consistent with the CTE of GaN, AlN, and SiC.

20. The method according to claim 18, wherein the final CTE of the conductive line is about 3.6 ppm / °C, which is consistent with the CTE of Si.

21. The method according to any one of claims 1 to 20, wherein the line / spatial resolution of the conductive line is at least about 5 / 5 μm.

22. The method according to any one of claims 1 to 21, further comprising removing a substrate.

23. The method according to any one of claims 1 to 22, wherein the substrate is coated.

24. The method according to any one of claims 1 to 23, wherein the solvent is selected from water, ethanol, methanol, isopropanol, ethylene glycol, and diethylene glycol monomethyl ether.

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