Method for forming electronic devices with glass substrates

Abstract

The invention provides a method for forming an electronic device, the method comprising: providing a glass substrate, where the glass substrate has a top redistribution layer on a top surface thereof; attaching an electronic component on the top redistribution layer of the glass substrate; bonding the electronic component to the top redistribution layer by performing laser assisted bonding through the glass substrate; forming an encapsulant layer on the glass substrate to encapsulate the electronic component and the top redistribution layer; forming a plurality of through holes in the glass substrate; forming a bottom redistribution layer onto the bottom surface of the glass substrate; and mounting a solder bump on the bottom redistribution layer.

Description

Technical Field

[0001] This application generally relates to electronic technology, and more specifically to a method for forming electronic devices having a glass substrate. Background Technology

[0002] The electronics industry has consistently faced complex integration challenges as consumers demand smaller, faster, and higher-performing electronic devices, packing increasing functionality into single devices. To meet these needs, more and more electronic components are being integrated into individual devices. Specifically, this requires bonding electronic components, such as semiconductor chips, to substrates, such as polymer-based printed circuit boards, to form integrated devices or packages.

[0003] Furthermore, glass wafers are considered a promising alternative to polymer-based substrates for electronic components, exhibiting numerous advantages such as excellent thermal stability, optical transparency, and chemical resistance. However, conventional bonding processes are less efficient at bonding electronic components to glass substrates.

[0004] Therefore, there is a need for a method for bonding one or more electronic components to a glass substrate to form an electronic device. Summary of the Invention

[0005] One objective of this application is to provide a method for bonding one or more electronic components to a glass substrate to form an electronic device.

[0006] According to one aspect of this application, a method for forming an electronic device is provided, the method comprising: providing a glass substrate having a top redistribution layer on its top surface; attaching an electronic component to the top redistribution layer of the glass substrate; bonding the electronic component to the top redistribution layer by laser-assisted bonding through the glass substrate; forming an encapsulant layer on the glass substrate to encapsulate the electronic component and the top redistribution layer; forming a plurality of through-holes in the glass substrate; forming a bottom redistribution layer on the bottom surface of the glass substrate; and mounting solder bumps to the bottom redistribution layer.

[0007] According to another aspect of this application, a method for forming an electronic device is provided, the method comprising: providing a glass substrate, wherein the glass substrate includes a top surface and a bottom surface; forming a plurality of through-holes in the glass substrate; forming a top redistribution layer on the top surface of the glass substrate; attaching electronic components to the top redistribution layer; bonding the electronic components to the top redistribution layer by laser-assisted bonding through the glass substrate; forming an encapsulant layer on the glass substrate to encapsulate the electronic components and the top redistribution layer; forming a bottom redistribution layer on the bottom surface of the glass substrate; and mounting solder bumps to the bottom redistribution layer.

[0008] It should be understood that both the above general description and the following detailed description are exemplary and explanatory only, and do not limit the invention. Furthermore, the accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. Attached Figure Description

[0009] The drawings referenced herein form part of this specification. The features shown in the drawings illustrate only some embodiments of this application, and not all embodiments of this application, unless the specific embodiments clearly indicate otherwise, and the reader of this specification should not infer the contrary.

[0010] Figures 1A to 1K A cross-sectional view is shown of a method for forming an electronic device according to an embodiment of this application.

[0011] Figures 2A to 2K A cross-sectional view is shown of a method for forming an electronic device according to another embodiment of this application.

[0012] Figures 3A to 3C Various alternative methods for laser-assisted bonding according to some embodiments of this application are shown.

[0013] Figure 4 The temperature change curve of the solder material on the glass substrate during a laser-assisted bonding process is shown in one example according to this application.

[0014] Throughout the diagram, the same reference numerals will be used to refer to the same or similar parts. Detailed Implementation

[0015] The following detailed description of exemplary embodiments of this application refers to the accompanying drawings, which form part of the description. The drawings illustrate specific exemplary embodiments in which this application may be practiced. The detailed description, including the drawings, is described in sufficient detail to enable those skilled in the art to practice this application. Those skilled in the art may further utilize other embodiments of this application and make logical, mechanical, and other changes without departing from the spirit or scope of this application. Therefore, the reader of the following detailed description should not interpret the description in a limiting sense, and the scope of the embodiments of this application is defined only by the appended claims.

[0016] In this application, unless otherwise specified, the use of the singular includes the plural. In this application, unless otherwise specified, the use of "or" means "and / or". Furthermore, the use of the term "including" and other forms such as "includes" and "included" is not restrictive. Additionally, unless explicitly stated otherwise, terms such as "element" or "component" cover elements and components comprising one unit, as well as elements and components comprising more than one sub-unit. Furthermore, the section headings used herein are for organizational purposes only and should not be construed as limiting the subject matter described.

[0017] For ease of description, spatial relative terms such as “below,” “under,” “above,” “on top,” “upper,” “lower,” “left,” “right,” “vertical,” “horizontal,” and “side” may be used to describe the relationship between one element or feature and another element(s) shown in the figures. In addition to the orientation depicted in the figures, spatial relative terms also inherently cover different orientations of the device during use or operation. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptors used herein may be interpreted accordingly. It should be understood that when an element is referred to as “connected to” or “coupled to” another element, it may be directly connected to or coupled to the other element, or there may be an intermediate element present.

[0018] In electronic devices such as integrated semiconductor packages, one or more electronic components need to be bonded to a substrate. Many bonding techniques have been developed, primarily for silicon or polymer substrates, or specifically for solder materials formed between the substrate and the electronic components thereon. However, conventional bonding techniques may not be suitable for bonding electronic components to glass substrates. To address this issue, a laser-assisted bonding process has been proposed to utilize laser energy to bond electronic components to a glass substrate. Because glass has relatively high laser transmittance, most of the laser beam is allowed to pass through it to heat the solder material between the glass substrate and the electronic components and resolder it, with minimal energy loss. In this way, energy consumption can be reduced compared to bonding processes used for silicon or polymer substrates. Furthermore, since laser energy can be applied over a shorter time than conventional heating processes, the bonding time can be significantly reduced, thus improving the efficiency of the bonding process.

[0019] Figures 1A to 1K A cross-sectional view is shown of a method for forming an electronic device according to one embodiment of this application. In this embodiment, a glass substrate is used as the substrate of the electronic device, and a corresponding bonding method is used when forming the electronic device.

[0020] See Figure 1A A glass substrate 110 is provided. The material of the glass substrate 110 can be adjusted to allow for tuning of the glass properties for specific applications. For example, the glass substrate 110 may comprise borosilicate glass or quartz glass. Preferably, the glass substrate 110 has a transmittance greater than 80% for light beams with wavelengths between 350 nm and 1100 nm, or preferably between 400 nm and 700 nm. In some embodiments, the thickness of the glass substrate 110 is 300 μm to 1500 μm. As described above, compared to silicon or polymer substrates widely used in semiconductor packaging, glass substrates can provide superior thermal stability, optical transparency, chemical resistance, etc. Utilizing the unique properties of glass substrates can overcome the limitations of silicon wafers, thereby facilitating the development of more advanced and reliable semiconductor packages or devices.

[0021] Various additional structures may be formed in or on the glass substrate 110 to impart electrical connectivity to the glass substrate 110, as detailed below. See Figure 1B In some embodiments, a top redistribution layer 120 is formed on the top surface of the glass substrate 110. The top redistribution layer 120 may include a conductive structure 121 extending through the dielectric layer 122 to provide electrical connectivity between the top and bottom surfaces of the top redistribution layer 120. It is understood that the conductive structure 121 may include conductive patterns exposed from both the top and bottom surfaces of the top redistribution layer 120, such that electronic components or structures on either side of the top redistribution layer 120 can be electrically coupled to each other when connected to the top or bottom conductive patterns. Preferably, the conductive structure 121 has good thermal conductivity. The top redistribution layer 120 may be made of any material compatible with the glass substrate 110 and suitable for redistribution. Preferably, the conductive structure 121 may be made of copper, aluminum, silver, or other metallic materials or combinations thereof. It is understood that in some embodiments, the glass substrate 110 may have the top redistribution layer 120 pre-formed thereon. For example, the top redistribution layer 120 may be composed of the same material as the glass substrate 110, as part of the glass substrate 110, especially when the top redistribution layer 120 includes a small number (e.g., one or two) of conductive structures 121.

[0022] See Figure 1CIn some embodiments, a non-conductive layer 130 is formed on the top redistribution layer 120, opposite the glass substrate 110, for example, a non-conductive paste (NCP) or non-conductive film (NCF) layer. The non-conductive layer 130 may include an adhesive material or adhesive tape, and thus may assist in further attaching one or more electronic components to the top redistribution layer 120. Preferably, the non-conductive layer 130 can be formed by applying an epoxy resin and any suitable filler and curing it during laser bonding. Solder materials distributed in the patterned non-conductive layer 130 can be electrically isolated from each other. For example, an anisotropic NCF or NCP layer may include small-diameter resin particles that are Ni / Au coated and dispersed in an insulating resin, wherein the insulating resin includes an epoxy resin or cyanate ester resin as a substrate. Preferably, the non-conductive layer 130 may have lower light absorption characteristics and lower thermal distortion characteristics compared to solder materials also formed on the top redistribution layer 120. Thus, the non-conductive layer 130 can exhibit better stability during subsequent bonding processes, which will be described in more detail below.

[0023] See Figure 1D After the non-conductive layer 130 and solder material 131 are formed, one or more electronic components 141, 142 can be attached to the top redistribution layer 120 through the non-conductive layer 130 and solder material 131. It is understood that electronic components 141 and 142 may be the same as or different from each other. Preferably, some or all of the electronic components 141, 142 and any other electronic components mounted on the top redistribution layer 120 may be semiconductor dies or semiconductor packages. It is understood that the number, size, and / or type of electronic components on the top redistribution layer 120 may vary as needed. Electronic components 141, 142 are connected to the solder material 131 such that the electronic components can be electrically coupled to conductive structures in the top redistribution layer 120. It is understood that during the attachment process, suitable pressure may be applied so that one or more electronic components 141, 142 can contact the top surface of the top redistribution layer 120 through the solder material 131.

[0024] See Figure 1ELaser-assisted bonding can be performed through the glass substrate 110 to bond the electronic components 141 and 142 to the top redistribution layer 120 by heating and reflowing the solder material 131 beneath them. For example, the glass substrate 110 can be placed on a transparent carrier 150, such as a quartz platform, and the laser source 160 can be positioned below the transparent carrier 150. A laser beam can be emitted from the laser source 160 through the transparent carrier 150 and the glass substrate 110 toward the top redistribution layer 120 and the solder material 131. Since both the transparent carrier 150 and the glass substrate 110 are transparent to the laser beam emitted from the laser source 160, most of the laser beam's energy can reach at least the top redistribution layer 120 without significant loss in the transparent carrier 150 and the glass substrate 110.

[0025] Specifically, since the laser energy can directly and efficiently reach the conductive structure 121 of the top redistribution layer 120, most photons (e.g., for laser beams in the wavelength range of 400 to 700 nm) are absorbed by the conductive structure 121 in the top redistribution layer 120. Therefore, the absorbed laser energy can be converted into heat that can be transferred throughout the conductive structure 121 in the top redistribution layer 120, because the thermal conductivity of the conductive structure 121 (e.g., copper) is higher than that of the dielectric material of the top redistribution layer 120. The conductive structure 121 can further transfer heat to the solder material 131 directly connected to the conductive structure 121 to heat and reflow the solder material 131, and via the solder material 131, bond the electronic components 141, 142 to the top redistribution layer 120. It is understood that the temperature of the solder material 131 during the bonding process should generally be higher than the melting temperature of the solder material 131, which can be controlled by the irradiation power and time. In specific examples, a laser source (e.g., with a wavelength range between 400 nm and 700 nm) is used, with a duration between 1 second and 5 seconds (e.g., 2 seconds, 3 seconds, 4 seconds, etc.). However, this application is not limited to the above examples, and the wavelength of the laser source and the duration of irradiation can vary depending on the intensity of the laser beam, the material and volume of the solder material 131, etc.

[0026] Figure 4 The diagram illustrates the temperature variation curve of the solder material on a glass substrate during a laser-assisted bonding process, according to an example of this application. Figure 4As shown, before irradiating the glass substrate with a laser beam, the glass substrate can be preheated to 70 degrees Celsius, for example, by a heater. Then, at the start of the laser-assisted bonding process, the laser source can be switched on to emit a laser beam onto the glass substrate. For example, the emission of the laser beam can last for one second. In the early stages of the bonding process duration, the temperature of the solder material can be rapidly increased from 70 degrees Celsius to approximately 240 degrees Celsius within a very short time period (e.g., 0.3 seconds). Subsequently, during the later stages of the bonding process duration, the temperature of the solder material can be maintained at approximately 240 to 260 degrees Celsius, which is above the melting temperature of the solder material (e.g., tin or a tin alloy or mixture). Afterward, the laser beam can be removed from the glass substrate, which allows the solder material to cool to, for example, approximately 70 degrees Celsius or even lower. Figure 4 After the temperature change shown, electronic components can be bonded to the top redistribution layer of the glass substrate as needed via solder material.

[0027] It is understood that the combination of a glass substrate and a top redistribution layer not only reduces power consumption during the bonding process but also directs or focuses energy to the region where solder material forms. This mechanism further improves the efficiency of laser-assisted bonding processes. In some embodiments, the conductive structures in the top redistribution layer can have different distributions or densities based on the location of the solder material. In other words, the top redistribution layer can have a denser conductive structure in the region below the solder material (i.e., below the electronic component) than in another region not below the solder material. In this way, the absorption of laser energy by the top redistribution layer can be more concentrated, which is beneficial for heating the solder material. In some alternative embodiments, the laser beam emitted from the laser source can be patterned or shaped such that it can be aligned with or scan only the portion of the top redistribution layer below the solder material, rather than the entire top redistribution layer.

[0028] Compared to conventional methods, laser-assisted bonding from the back side of the glass substrate allows for relatively direct and efficient laser transmission, and thus such bonding methods are efficient and fast, while also reducing energy consumption.

[0029] Furthermore, in some embodiments, the non-conductive layer can also be cured while one or more electronic components are being bonded during laser-assisted bonding. The cured non-conductive layer can protect the solder material. It is understood that this process is relatively efficient because the bonding of the electronic components and the curing of the non-conductive layer can be completed simultaneously.

[0030] After the electronic components are bonded to the top redistribution layer and thus connected to the glass substrate, various other processes can be performed to form integrated electronic devices. See also Figure 1FAn encapsulant layer 170 is formed on a glass substrate 110 to encapsulate electronic components 141, 142 and a top redistribution layer 120. In some embodiments, the encapsulant layer 170 may be a polymer composite material, such as epoxy resin, epoxy acrylate, or any suitable polymer with or without fillers. The encapsulant layer 170 may be non-conductive, providing structural support and environmentally protecting the electronic devices from external environmental factors and contaminants. The encapsulant layer 170 may be formed in any shape as needed. The encapsulant layer 170 may be formed by depositing an encapsulant or molding compound on the glass substrate 110 using injection molding, pressure molding, transfer molding, liquid encapsulant molding, vacuum lamination, spin coating, or other suitable processes. It is understood that, for simplicity, the non-conductive layer is not shown in other steps. The non-conductive layer may similarly encapsulate within the encapsulant layer 170 and may not be removed.

[0031] See Figure 1G and 1H The glass substrate 110 can be flipped so that its bottom surface faces upward, and a via 180 can then be formed in the glass substrate 110. Specifically, the via 180 can be formed by first creating a hole through ablation or drilling, and then filling the hole with a conductive material to create an electrical connection extending through the glass substrate 110. It is understood that the via 180 can be electrically coupled to the conductive structure 131 in the top redistribution layer 130, and thus further coupled to electronic components 141 and 142. Figure 1H In the illustrated embodiment, each of the vias 180 can be in the form of a cone with a diameter decreasing from top to bottom. It is understood that the vias 180 can take any form as needed. Since the vias 180 are formed after the laser-assisted bonding process, the vias do not affect the bonding process, and in particular, do not obstruct the transmission of the laser beam.

[0032] See Figure 1I A bottom redistribution layer 190 is then formed on the bottom surface of the glass substrate 110. The bottom redistribution layer 190 can provide electrical connections to a larger area of ​​the via 180 within the glass substrate 110. The configuration of the bottom redistribution layer 190 is similar to that of the top redistribution layer 120. For example, conductive structures can be formed in the bottom redistribution layer 190, which can connect to the via. Similar to the via 180, since the bottom redistribution layer 190 is formed after the bonding process, the conductive structures in the bottom redistribution layer 190 do not affect the laser-assisted bonding process.

[0033] See Figure 1JSolder bump 191 can be further mounted onto bottom redistribution layer 190 to provide electrical connection to external devices. Thus, generally speaking, electronic components 141, 142 can be electrically coupled to solder bump 191 via top redistribution layer 120, glass substrate 110 and bottom redistribution layer 190.

[0034] See Figure 1K In some embodiments, during manufacturing, solder bumps 191 can be installed with the bottom surface of the glass substrate 110 facing upwards and the electronic components 141, 142 facing downwards. For further attachment operations, the overall structure can be flipped so that the electronic components 141, 142 face upwards, and the solder bumps 191 can be attached to other substrates below.

[0035] Figures 2A to 2K A cross-sectional view is shown of a method for forming an electronic device according to another embodiment of this application. (See reference...) Figures 1A to 1K The described implementation differs in that through-holes can be formed in the glass substrate before the electronic components are bonded to it.

[0036] See Figure 2A A glass substrate 210 is provided, the glass substrate having a top surface 211 and a bottom surface 212. See below. Figure 2B A via 220 is formed in the glass substrate 210. In some embodiments, the via 220 may be formed as a conductive cone with a diameter decreasing from top to bottom.

[0037] See Figure 2C A top redistribution layer 230 with an internal conductive structure is formed on the top surface 211 of the glass substrate 210. See also... Figure 2D A non-conductive layer 240 can be formed on the top redistribution layer 230 to facilitate the subsequent attachment of electronic components.

[0038] See Figure 2E One or more electronic components 251, 252 are attached to the top redistribution layer 230. It is understood that solder material 231 can be formed through the non-conductive layer 240.

[0039] Then, see Figure 2FLaser-assisted bonding can be performed through the glass substrate 210 to bond electronic components 251, 252 to the top redistribution layer 230 via solder material. Similar to the embodiments mentioned above, in some embodiments, the glass substrate 210 can be disposed on a transparent carrier 260, and the laser source 270 can be disposed below the transparent carrier 260 to emit an upward laser beam. The laser beam can pass through the transparent carrier 260 and the glass substrate 210 and reach the top redistribution layer 230. In this way, solder material can be reflowed to bond electronic components 251, 252 to the top redistribution layer 230.

[0040] See Figure 2G Then, an encapsulating agent layer 280 can be formed on the glass substrate 210 to encapsulate the electronic components 251, 252 and the top redistribution layer 230. See also Figure 2H Then the glass substrate can be flipped to expose the bottom surface 212 of the glass substrate 210, thereby further forming a redistribution layer and attaching solder bumps.

[0041] See Figure 2I and 2J A bottom redistribution layer 290 can be formed on the bottom surface 212 of the glass substrate 210, and solder bumps 291 can be mounted on the bottom redistribution layer 290.

[0042] See Figure 2K The glass substrate can be flipped again so that the electronic components 251 and 252 face upwards and the solder bump 291 faces downwards.

[0043] Figures 3A to 3C Various alternative methods for laser-assisted bonding according to some embodiments of this application are shown.

[0044] For example, see Figure 3A and 3B In some embodiments, when electronic components 311 and 312 are bonded to the top redistribution layer 320, a bonding process combining thermocompression bonding and laser-assisted bonding can be performed on electronic components 311 and 312, respectively. Specifically, when a laser beam is emitted from a laser source through the transparent carrier 350 and the glass substrate 310 toward the solder material between electronic components 311 and 312 and the top redistribution layer 320, a pressure head 395 can apply pressure against the top redistribution layer 320 at electronic components 311 and 312. It is understood that thermocompression bonding performed by the pressure head 395 further improves the bonding between electronic components 311 and 312 and the top redistribution layer 320.

[0045] See Figure 3CIn some other embodiments, electronic component 312, or any other electronic component mounted on glass substrate 310, may be a high-bandwidth memory (HBM) chiplet package or other semiconductor package, rather than a semiconductor die. While semiconductor package 312 may be opaque to laser beams and therefore unsuitable for laser-assisted bonding from its top side, the laser-beam-transparent glass substrate 310 allows the energy of the laser beam to pass through it, similar to... Figures 1A to 1K The implementations shown in 2A to 2K.

[0046] This document includes numerous illustrative diagrams illustrating various parts of a method for forming an electronic device. For clarity, such diagrams do not show all aspects of each example assembly. Any of the example assemblies and / or methods provided herein may share any or all characteristics with any or all other assemblies and / or methods provided herein.

[0047] Various embodiments have been described herein with reference to the accompanying drawings. However, it will be apparent that various modifications and alterations can be made thereto, and additional embodiments can be implemented, without departing from the broader scope of the invention as set forth in the appended claims. Furthermore, other embodiments will be apparent to those skilled in the art upon consideration of the description and practice of one or more embodiments of the invention disclosed herein. Therefore, this application and the examples herein are intended to be considered merely exemplary, and the true scope and spirit of the invention are indicated by the set forth in the appended exemplary claims.

Claims

1. A method for forming an electronic device, characterized in that, The method includes: A glass substrate is provided, wherein the glass substrate has a top redistribution layer on its top surface; Electronic components are attached to the top redistribution layer of the glass substrate; The electronic components are bonded to the top redistribution layer by laser-assisted bonding through the glass substrate; An encapsulating agent layer is formed on the glass substrate to encapsulate the electronic components and the top redistribution layer; Multiple through-holes are formed in the glass substrate; A bottom redistribution layer is formed on the bottom surface of the glass substrate; and Solder bumps are mounted onto the bottom redistribution layer.

2. The method according to claim 1, characterized in that, Bonding the electronic components to the top redistribution layer includes: laser-assisted bonding through the glass substrate, and hot-pressing the electronic components.

3. The method according to claim 1, characterized in that, The electronic components include semiconductor dies or semiconductor packages.

4. The method according to claim 1, characterized in that, The thickness of the glass substrate is 300um to 1500um.

5. The method according to claim 1, characterized in that, The duration of the laser-assisted bonding is 1 to 5 seconds.

6. The method according to claim 1, characterized in that, Before attaching electronic components to the top redistribution layer, the method further includes forming a non-conductive layer on the top redistribution layer.

7. A method for forming an electronic device, characterized in that, The term includes: A glass substrate is provided, wherein the glass substrate includes a top surface and a bottom surface; Multiple through-holes are formed in the glass substrate; A top redistribution layer is formed on the top surface of the glass substrate; Electronic components are attached to the top redistribution layer; The electronic components are bonded to the top redistribution layer by laser-assisted bonding through the glass substrate; An encapsulating agent layer is formed on the glass substrate to encapsulate the electronic components and the top redistribution layer; A bottom redistribution layer is formed on the bottom surface of the glass substrate; as well as Solder bumps are mounted onto the bottom redistribution layer.

8. The method according to claim 7, characterized in that, Bonding the electronic components to the top redistribution layer includes: laser-assisted bonding through the glass substrate, and hot-pressing the electronic components.

9. The method according to claim 7, characterized in that, The electronic components include semiconductor dies or semiconductor packages.

10. The method according to claim 7, characterized in that, The thickness of the glass substrate is 300um to 1500um.

11. The method according to claim 7, characterized in that, The duration of the laser-assisted bonding is 1 to 5 seconds.

12. The method according to claim 7, characterized in that, Before attaching electronic components to the top redistribution layer, the method further includes forming a non-conductive layer on the top redistribution layer.

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