Patent Application
20250192096
For integrated circuit design and fabrication, the need to improve performance and lower costs are constant challenges. The semiconductor industry is presently looking to enhance the performance of semiconductor devices through scaling system-level interconnections, and hybrid bonding may provide a promising solution with the ability to integrate several dies with small interconnection pitches.
Hybrid bonding is a permanent bond that combines a dielectric bond (e.g., SiOx) with embedded metal (e.g., Cu) to form interconnections and provides superior interconnect density, enabling 3D-like packages and advanced memory cubes. Specifically, hybrid bonding provides a solution for interconnects with 10 μm pitches and below by completely avoiding the use of solder bumps, and will instead connect the dies in packages using small copper-to-copper connections.
In die-to-wafer (D2 W) hybrid bonding, obtaining 200 nm alignment accuracy or lower is typically necessary for a high level of electrical performance, and achieving this degree of accuracy at a high enough throughput is challenging with current hybrid bonding equipment since the throughput is dominated by the time required to perform a precision alignment.
One approach to addressing the alignment issue uses a “self-assembly” method, in which the wafers and dies are patterned to create hydrophobic regions surrounding hydrophilic bonding sites, with water droplets being dispensed on the bonding sites on the wafer and confined by the surrounding hydrophobic region. Thereafter, the dies may be placed on the bonding sites. However, it is presently not possible to pick and place multiple dies simultaneously onto a wafer, since the standard water dispense method uses a single nozzle to dispense a specific volume of water onto each bond site immediately before the die placement in a step-by-step process. This step-by-step process ensures that there is a sufficient volume of water on each bonding site and the self-assembly may be performed in an ambient environment without the need for humidity controls. A fast rate of evaporation in a low-humidity environment may limit the self-assembly to process to a sequential (one-by-one) die placement, which can significantly reduce the throughput and this is not desirable.
In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the present disclosure. The dimensions of the various features or elements may be arbitrarily expanded or reduced for clarity. In the following description, various aspects of the present disclosure are described with reference to the following drawings, in which:
The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details, and aspects in which the present disclosure may be practiced. These aspects are described in sufficient detail to enable those skilled in the art to practice the present disclosure. Various aspects are provided for devices, and various aspects are provided for methods. It will be understood that the basic properties of the devices also hold for the methods and vice versa. Other aspects may be utilized and structural, and logical changes may be made without departing from the scope of the present disclosure. The various aspects are not necessarily mutually exclusive, as some aspects can be combined with one or more other aspects to form new aspects.
According to the present disclosure, an improved self-assembly tool may provide for the placement and alignment of multiple dies simultaneously. In an aspect, the present self-assembly tool may provide a closed, controlled environment, e.g., using a processing chamber, whereby the self-assembly and bonding processes may be performed at a constant humidity, temperature, and airflow.
In another aspect, the present self-assembly tool may provide wafer-scale liquid dispensing that allows all bonding sites/locations on a wafer to be provided with water at the same or nearly the same time. This simultaneous dispensing of water will increase throughput over the present sequential bonding site by bonding site process. Alternatively, a “collective” or batch water dispense system may be provided in the present self-assembly tool to permit a precise dispensing of a controlled amount of water at each bonding site when different volumes are needed for the individual bonding sites.
The present disclosure provides a self-assembly module including a liquid dispensing unit having an applicator and a reservoir for a liquid, whereby the applicator dispenses the liquid simultaneously onto multiple bonding sites on a wafer, an environmental control unit, a wafer support, and a computer/processor. In an aspect, the self-assembly module further includes a die and wafer transport mechanism.
The present disclosure is also directed to a method that includes providing a wafer, patterning the wafer to form a hydrophobic surface with a plurality of hydrophilic regions, disposing the wafer on a wafer support in a self-assembly module of a hybrid bonding system, dispensing a liquid simultaneously onto multiple bonding sites on the wafer, positioning dies on the plurality of hydrophilic regions on the wafer, and bonding the dies to the wafer using hybrid bonding method.
The present disclosure is further directed to a hybrid bonding system including a self-assembly module having a liquid dispensing unit provided with an applicator and a reservoir for a liquid, whereby the liquid is simultaneously dispensed onto multiple bonding sites on a wafer, a wafer support, an environmental control unit, and a die and wafer transport mechanism. The hybrid bonding system may further include a bonding module and other modules self-assembly tool may provide.
The technical advantages of the present disclosure include, but are not limited to:
To more readily understand and put into practical effect the present self-alignment tool/module and methods, which may provide an improved hybrid bonding system, particular aspects will now be described by way of examples provided in the drawings that are not intended as limitations. The advantages and features of the aspects herein disclosed will be apparent through reference to the following descriptions relating to the accompanying drawings. Furthermore, it is to be understood that the features of the various aspects described herein are not mutually exclusive and can exist in various combinations and permutations. For the sake of brevity, duplicate descriptions of features and properties may be omitted.
In an aspect, the self-assembly tool/module 100 may include a liquid dispensing unit 104, an environmental control unit 105, and a die/wafer transport mechanism 106. In addition, the self-assembly tool/module 100 and self-alignment process may require a computer/processor 103, which may be integrated with the self-assembly module 100 or associated with the hybrid bonding system 10.
In an aspect, the liquid dispensing unit 104 may include a liquid applicator and a reservoir for a liquid (shown below in
In another aspect, the environmental control unit 105 may monitor and control the humidity and temperature in the self-assembly module 100, which may include humidity and temperature sensors, an airflow system with fans and vents to provide or shutoff airflow, and heaters for controlling humidity and evaporation. The evaporation rate of the dispensed water may be especially important for smaller dies, which require small amounts of water (e.g., in the range of approximately 0.1 to 0.5 uL), since a high evaporation rate may reduce the time window for die placement. The evaporation rate of the dispensed water may be regulated by the environmental control unit 105, which will control the humidity, airflow, and temperature levels in the self-assembly module 100. By controlling the evaporation rate, the water volume may be adjusted to a precise amount before die placement.
It should be understood that conventional environmental control equipment may be adapted for use with the present self-assembly tool. For example, a present environmental control unit may include an airflow system having an integrated pump and desiccant reservoir that can generate a dry airflow using ambient air, as well as a heated water reservoir to generate necessary humidity within a self-assembly tool and hybrid bonding system. In addition, the temperature control within a present self-assembly tool (e.g., adding a heating element to the wafer support or chuck) may be used to remove excess water, reduce dispensed water volume at a bonding site, or speed up post-placement evaporation at a bonding site, which may be necessary before moving the wafer with assembled dies for annealing.
In yet another aspect, the die/wafer transport mechanism 106 may include robotic arms, clamps, and holders for wafers and dies for the pickup and placement of wafers and dies. For example, in the collective self-assembly process, the dies may be placed on a carrier substrate and transferred all together or in batches onto a patterned wafer.
In an aspect, as shown in
In an operation similar to spin coating, a pre-determined volume of water 310 may be placed onto the middle region of the wafer 301, and then the wafer 301 may be spun at appropriate speeds to allow the water 310 to spread out radially across the entire wafer 301, i.e., a simultaneous dispensing of a liquid on multiple bonding sites, and remain only in the hydrophilic regions 302a. The spinning speed should be sufficiently fast to remove any excess water from the hydrophobic region 302b. The volume of the water 310 needed for this process may be determined by the number and sizes of the dies to be bonded, which, in turn, will determine the speed of the turntable platform 309 for removing the water 310 from the hydrophobic region 302b.
In an aspect, the tilting mechanism 511 may include, for example, configuring the wafer support 509 to tilt on attached axial pins (not shown), having the wafer 501 be positioned in a holder/clamping device that is tiltable, or having extendable vertical pins in the wafer support 509 that lift up one side of the wafer 501. The tilting of the wafer 501 may be effected by a motor and/or a piezoelectric device. The use of a wafer tilting method to remove excess liquid may be performed alone or in combination with other methods, including the spinning method discussed above.
According to the present disclosure, it may be necessary to provide a precise water volume on each bonding site/location, which may not be easy to accomplish with the aforementioned wafer-scale water dispensing methods or other similar methods. For heterogeneous integration, for example, each bonding site/location on a target wafer can have a very different area due to different die sizes. Therefore, a collective or batch liquid dispense system may be needed to provide precise and controlled amounts of water at such bonding sites/locations.
According to the present disclosure, a pin array and a micro dripper array may be configured and adapted to dispense a liquid so as to accommodate an individual design layout of a wafer. In addition, it is within the scope of the present disclosure to use pins with different sizes and tip shapes in different locations of a pin array and to use droppers with different sizes in different locations of a micro dropper array, so that different water volumes may be transferred to the corresponding locations on a wafer. In another aspect, if a bonding site is large, it may be necessary to use several pins or droppers to transfer the required volume of water onto the large bonding site. The pre-calculated amounts of water may be determined through simulations or pre-production testing.
In addition, the hybrid bonding process 1000 may include the steps: 5) a planarization of a wafer 1001b using a chemical mechanical polishing (CMP) step (in
The operation 1101 may be directed to providing a wafer and patterning the wafer to form a hydrophobic surface with a plurality of hydrophilic regions.
The operation 1102 may be directed to providing a self-alignment module and dispensing a liquid on the plurality of hydrophilic regions on the wafer.
The operation 1103 may be directed to monitoring and controlling humidity and evaporation of the liquid from the wafer.
The operation 1104 may be directed to positioning dies onto the plurality of hydrophilic regions and bonding the dies with the wafer by a hybrid bonding method.
It will be understood that any property described herein for a particular self-assembly module/tool and method for hybrid bonding may also hold for any self-assembly module/tool using the present features/units described herein. It will also be understood that any property described herein for a specific method may hold for any of the methods described herein. Furthermore, it will be understood that for any self-assembly module/tool and the methods described herein, not necessarily all the components or operations described will be shown in the accompanying drawings or method, but only some (not all) components or operations may be disclosed.
To more readily understand and put into practical effect the self-assembly module/tool having present features and units, they will now be described by way of examples. For the sake of brevity, duplicate descriptions of features and properties may be omitted.
The term “comprising” shall be understood to have a broad meaning similar to the term “including” and will be understood to imply the inclusion of a stated integer or operation or group of integers or operations but not the exclusion of any other integer or operation or group of integers or operations. This definition also applies to variations on the term “comprising” such as “comprise” and “comprises”.
The term “coupled” (or “connected”) herein may be understood as electrically coupled or as mechanically coupled, e.g., attached or fixed or attached, or just in contact without any fixation, and it will be understood that both direct coupling or indirect coupling (in other words: coupling without direct contact) may be provided.
The terms “and” and “or” herein may be understood to mean “and/or” as including either or both of two stated possibilities.
While the present disclosure has been particularly shown and described with reference to specific aspects, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims. The scope of the present disclosure is thus indicated by the appended claims and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced.
