Embodiments of the present invention generally relate to a chip package having hybrid bonding, and in particular, to a chip package having both chiplets and integrated circuit dies boned to substrates, such as package substrates, interposers and the like.
Electronic devices, such as tablets, computers, copiers, digital cameras, smart phones, control systems, automated teller machines, data centers, artificial intelligence system, and machine learning systems among others, often employ electronic components which leverage chip package assemblies for increased functionality and higher component density. Conventional chip packaging schemes often utilize a package substrate, often in conjunction with a through-silicon-via (TSV) interposer substrate, to enable a plurality of integrated circuit (IC) dies to be mounted to a single package substrate. The IC dies may include memory, logic or other IC devices.
In advanced chip-on-wafer (CoW) chip packages, the integration of large IC dies and chiplets is becoming increasingly challenging, particularly as fine pitch and high density interconnects at the IC die/chiplet to substrate interface are highly desirable to obtain performance goals. Some of these challenges at the interface include warpage control, prevention of solder joint defects such as bridging and poor reflow, and effective removal of flux residue. Failure to adequately address any of these challenges could lead to poor device performance and even device failure.
Therefore, a need exists for a chip package having an improved IC die/chiplet to substrate interface.
A chip package and method for fabricating the same are provided that includes hybrid bonds between a substrate and integrated circuit devices. In one example, a chip package includes a plurality of integrated circuit (IC) devices mounted on a substrate. The substrate has a die side and a ball side. The die side of the substrate includes a plurality of exposed metal bond pads. Each IC device has a device body. Functional circuitry is formed in the device body, terminating at a plurality of exposed metal bond pads. The plurality of exposed metal bond pads are hybrid bonded to the plurality of exposed metal bond pads.
In another example, the chip package may include a first bond pad of the plurality of exposed metal bond pads that has a surface area in contact with a first contact pad of the plurality of exposed metal bond pads. The surface area if the first bond pad is greater than a sectional area of the first bond pad taken in a direction parallel to a plane of the substrate.
In yet another example, a method for fabricating a chip package is provided. The method includes temporarily securing a plurality of integrated circuit (IC) devices to a carrier, revealing a plurality of metal bond pads of each IC device disposed on the carrier, mounting the IC devices disposed on the carrier to a substrate, hybrid bonding a plurality of exposed metal bond pads of the substrate to the metal bond pads of the IC devices disposed on the carrier, and removing the carrier to form the chip package. The hybrid bonds mechanically couple the IC devices to the substrate and electrically couple the functional circuitry of the IC devices to circuitry formed through the substrate.
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements of one embodiment may be beneficially incorporated in other embodiments.
A chip package and method for fabricating the same are provided that enable fine pitch and high density interconnects at the IC die (and/or chiplet) to substrate interface. The interface leverages hybrid bonding techniques to enable formation of sub-micron fine pitches between interconnects, improves warpage resistance, eliminates flux residue In some examples, the hybrid bond across the interconnect interface is not completely parallel to the plane of the substrate, which desirably increases the surface area available for hybrid bonding, resulting in increased bond strength, improved electrical performance, and more relaxed tolerances. As an end result, the chip package with hybrid bonded interface provide improved reliability and performance over conventional solder interface designs.
Turning now to
The method 100 begins at operation 102 by temporarily securing a plurality of integrated circuit (IC) devices 202 to a carrier 204, as shown in
The carrier 204 may be any suitable rigid substrate that to which the IC devices 202 may be temporally secured during the hybrid bonding process. In one example, the carrier 204 is a metal plate, such as an aluminum plate. In another example, the carrier 204 is a glass or glass reinforced plastic plate.
The IC dies 202D and chiplets 202C each include a device body 208 having functional circuitry 210 formed in therein. The functional circuitry 210 may include block random access memory (BRAM), UltraRAM (URAM), digital signal processing (DSP) blocks, configurable logic elements (CLEs), and the like. The IC dies 202D may be, but are not limited to, programmable logic devices, such as field programmable gate arrays (FPGA), memory devices, such as high band-width memory (HBM), optical devices, processors or other IC logic structures. The IC dies 202D may optionally include optical devices such as photo-detectors, lasers, optical sources, and the like. In some examples, at least one of the IC dies 202D is a logic die having math processor (also known as math engine) circuitry for accelerating machine-learning math operations in hardware, such as self-driving cars, artificial intelligence and data-center neural-network applications. In another example, at least one of the IC dies 202D is a logic die, while the other IC die 202D or one or more of the chiplets 202C are memory devices.
Optionally, at least one or more of the IC devices 202 may be disposed in a vertical stack. It is contemplated that the IC devices 202 comprising a vertical stack may be the same or different types. An exemplary stack is a stack of memory dies. Although eight IC devices 202 are shown in
The device body 208 of each IC device 202 has a die bottom surface 212 and a die top surface. The die top surface is attached to the carrier 204. The functional circuitry 210 is disposed within the device body 208 and includes routing that terminates on the die bottom surface 212 of the IC device 202, for example at bond pads 214.
After the IC device 202 is attached to the carrier 204, the method 100 continues to operation 104. At operation 104, the plurality of metal bond pads 214 of each IC device 202 disposed on the carrier 204 are revealed. The metal bond pads 214 may be revealed by any suitable technique, such as grinding, milling or etching.
At operation 106, the IC devices 202 disposed on the carrier 204 are mounted on a substrate 230. The substrate 230 may be an interposer or a package substrate. The substrate 230 includes circuitry 236 that connects bond pads 234 exposed on an IC device (i.e., top) surface 232 of the substrate 230 with bond pads exposed on the opposite (i.e., bottom) surface of the substrate. The bond pads 234 are arranged in groups that are in mirror image of the arrangement of the bond pads 214 of the IC devices 202 secured to the carrier 204. In this manner, when the carrier 204 is flipped and mounted on the substrate 230, each of the bond pads 214 of every IC devices 202 is aligned and in contact with the bond pads 234 of the IC devices 202 secured to the carrier 204. An outline of the mounting area of each IC device 202 on the substrate 230 is shown in phantom in
Once the IC devices 202 have been mounted on the substrate 230, the exposed metal bond pads 234 of the substrate 230 are hybrid bonded to the exposed metal bond pads 214 of the IC devices 202 at operation 108. Hybrid bonding includes forming non-metal to non-metal bonds using fusion bonding, and forming metal-to-metal bonds. The metal-to-metal bonds may be formed using pressure and heat to form eutectic metal bonds. In one example, a hybrid bond is formed by bonding the dielectric materials surrounding the bond pads 214, 234 to first secure the substrate 230 and IC devices 202, followed by an interfusion of the metal materials of the bond pads 214, 234 to create the electric interconnect between the functional circuitry 210 of the IC devices 202 and the circuitry 236 of the substrate 230.
As illustrated in
Similarly, the substrate 230 includes a plurality of contact pads 342 that are electrically connected to the circuitry 236 extending between the top and bottom surfaces 232, 352 of the substrate 230. The circuitry 236 generally terminates at a contact pad 338 exposed on the bottom surface 352 of the substrate 230. The substrate 230 may include a core 324 that has interconnect layers 322, 336 formed on either side. Each interconnect layer 322, 336 includes patterned metal layers that form portions of the circuitry 236. The core 324 typically includes a conductive via that couples the portions of the circuitry 236 formed in each interconnect layer 322, 336.
The interconnect layer 322 includes a plurality of contact pads 342 that are separated by an internal dielectric layer 346. Each bond pad 234 is formed on and electrically connected to a respective one of the contact pads 342. In one example, the bond pad 234 is formed from plated copper that is disposed on a copper seed layer 344. Each bond pad 234 is separated from each other by an external dielectric layer 348. The dielectric layer 348 is selected from a material suitable for hybrid bonding to the dielectric material of the external dielectric layer 308. In one example, the dielectric layers 308, 348 are made of the same type of material, for example, polybenzoxazole (PBO), polyimide (PI), benzocyclobutene (BCB), a combination thereof or the like.
As the dielectric layer 308 and the bond pads 214 of the IC device 202 are pressed against the exposed the dielectric layer 348 and the bond pads 234 of the substrate 230, the dielectric layers 308, 348 bond together as illustrated in
At operation 110, the carrier 204 (and optional carrier 330) are removed to form a chip package 400, as illustrated in
In some embodiment and as illustrated in
Referring first to
The method 900 begins at operation 902 by forming an underbump metalization structure, such as the contact pad 302, that is electrically connected to the functional circuitry 210 of the IC device 202. The internal dielectric layer 306 is formed and patterned over the contact pads 302, leaving a portion 1002 of the contact pad 302 exposed through an opening 1004 formed in the dielectric layer 306.
At operation 904, photoresist 1006 is deposited and patterned over the dielectric layer 306 forming an opening 1008. A portion 1010 of the top surface of the dielectric layer 306 and the exposed portion 1002 of the contact pad 302 are exposed through the opening 1008 in the dielectric layer 306.
At operation 906, a bond pad 214 is formed in the opening 1008. The bond pad 214 makes electrical contact with the exposed portion 1002 of the contact pad 302. Optionally, a copper seed layer 304 may be disposed over the exposed portion 1002 of the contact pad 302 to facilitate plating of the bond pad 214 on the contact pad 302. The photoresist 1006 is removed after formation of the bond pad 214.
At operation 908, an external dielectric layer 308 is formed on the exposed portions of the top surface of the dielectric layer 306 and the bond pad 214. The dielectric layer 308 is selected from a material suitable for hybrid bonding to another dielectric material. In one example, the dielectric layer 308 is polybenzoxazole (PBO), polyimide (PI), benzocyclobutene (BCB), a combination thereof or the like.
At operation 910, the die bottom surface 1030 of the device body 208 is ground to thin the IC device 202 to a desired thickness.
At operation 912, the wafer containing the IC devices 202 are mounted to a frame 1012. The wafer is mounted to the frame 1012 using die attach tape or other suitable temporary adhesive to secure the ground die bottom surface 1030 of the device body 208 to the frame 1012. At operation 914, the IC devices 202 are singulated, for example by dicing the wafer with a wire saw, and removed from the frame 1012.
At operation 916, IC devices 202 are temporarily attached to a carrier 204. The IC devices 202 are mounted to the carrier 204 using a temporary adhesive, such as a die attach film or tape in a geometrical arrangement identical to the geometrical arrangement in which the IC devices 202 will have in the finished chip package.
In one example, a single IC device 202 may be attached on the carrier 204. In another example, one or more IC devices 202 in the form of IC dies 202D along with one or more IC devices 202 in the form of chiplets 202C may be attached on the carrier 204. In yet another example, one or more IC devices 202 in the form of IC logic dies 202D along with one or more IC devices 202 in the form of a stack of IC memory dies 202D or chiplets 202C may be attached on the carrier 204.
At operation 918, a mold material 208 is deposited on the carrier 204 and over the IC devices 202. The mold material 208 separates the IC devices 202 and covers the dielectric layer 308. At operation 920, the mold material 208 is ground to reveal the bond pads 214 and the dielectric layer 308.
At optionally operation 922, the bond pads 214 are patterned to increase the contact surface area, such as described above with reference to
In one example, the bond pads 214 may be patterned by disposing a patterned resist layer that has opening through which a portion of the bond pads 214 are exposed. The exposed portion of the bond pads 214 are then etched to form a step, recess or other structure that may be mated with a mirror image structure formed in the bond pad 234 of the substrate 230.
The method 1100 begins at operation 1102 by forming an underbump metalization structure, such as the contact pad 342 that is electrically connected to the circuitry 236 of the substrate 230. The internal dielectric layer 346 is formed and patterned over the contact pads 342, leaving a portion 1202 of the contact pad 342 exposed through an opening 1204 formed in the dielectric layer 346.
At operation 1104, photoresist 1206 is deposited and patterned over the dielectric layer 346 forming an opening 1208. A portion 1210 of the top surface of the dielectric layer 346 and the exposed portion 1202 of the contact pad 342 are exposed through the opening 1208.
At operation 1106, a bond pad 234 is formed in the opening 1208. The bond pad 234 makes electrical contact with the exposed portion 1202 of the contact pad 342. Optionally, a copper seed layer 344 may be disposed over the exposed portion 1202 of the contact pad 342 to facilitate plating of the bond pad 234 on the contact pad 342. The photoresist 1206 is removed after formation of the bond pad 234.
At operation 1108, an external dielectric layer 348 is formed on the exposed portions of the top surface of the dielectric layer 346 and the bond pad 234. The dielectric layer 348 is selected from a material suitable for hybrid bonding to another dielectric material. In one example, the dielectric layer 348 is the same materials used for the dielectric layer 308, such as polybenzoxazole (PBO), polyimide (PI), benzocyclobutene (BCB), a combination thereof or the like.
At operation 1110, substrate 230 is temporarily attached to a carrier 330. The substrate 230 is mounted to the carrier 330 using a temporary adhesive, such as a die attach film or tape. At operation 1112, a portion of the mold material 310 is removed to reveal the bond pads 234.
At optionally operation 1114, the bond pads 234 are patterned to increase the contact surface area, such as described above with reference to
After the methods 900 and 1100 are complete, the substrate 230 and IC devices 202 disposed on the carrier 204 are hybrid bonded together, for example as described above with reference to the method of
Thus, a chip package and method for fabricating the same have been described that includes hybrid bonding configured to improve the formation of sub-micron fine pitches between interconnects, improves warpage resistance, and eliminates flux residue. In some examples, the hybrid bond across the interconnect interface is not completely parallel to the plane of the substrate, which desirably increases the surface area available for hybrid bonding, resulting in increased bond strength, improved electrical performance, and more relaxed tolerances. As an end result, the chip package with hybrid bonded interface provide improved reliability and performance over conventional solder interface designs.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.