Embodiments of the present disclosure generally relate to the field of package assemblies, and in particular package assemblies that include high-speed input/output (HSIO) traces.
Continued reduction in end product size of mobile electronic devices such as smart phones and ultrabooks is a driving force for the development of reduced size system in package components. As speed requirements between dies on a package, for example between a compute die and a memory die, continues to increase, density of traces in a package substrate will continue to increase, and the increased frequency and speed of transmission on these traces will become increasingly important.
Embodiments of the present disclosure may generally relate to systems, apparatus, and/or processes directed to creating a package that includes transmission lines that operate at high frequencies, where the transmission lines include copper interfaces. In embodiments, smooth surfaces for the interface between where a copper trace and a copper via are directly electrically coupled will reduce electrical resistance between the surfaces. In embodiments, the smooth surfaces may facilitate maintaining an insertion loss budget for the package.
To promote mechanical stability of the package where the smooth copper surfaces come into contact with a dielectric, to promote adhesion with the dielectric the copper surfaces may be coated with an OAP film prior to the application of the dielectric to the copper surface. As a result, the likelihood of delamination of the dielectric from the copper surface is reduced. In embodiments, the OAP may provide a chemical adhesive layer to enable a smooth copper/dielectric interface without compromising the adhesion between metal and organic dielectric layers. In embodiments, OAP on copper surfaces may be removed prior to forming a copper feature, such as a metal via, when creating a direct electrical connection on the copper surface. Although copper is specifically mentioned, embodiments described herein may be applied to any conductive metal.
Embodiments described herein may use a semi-additive process (SAP) when using OAP film as an adhesion promoter that uses a dry desmear process to prevent the copper-OAP-dielectric interface from delaminating during fabrication. This may be referred to as a semi-wet SAP process flow that enables a wet OAP process with compatibility with dry desmear and sputter seed deposition processes. If wet desmear chemicals are used, for example a permanganate solution, delamination may result. As a result, in embodiments, a sputtered seed process may be preferred together with a dry desmear process to provide a wet-chemical free process flow to maintain the copper-OAP-dielectric interface integrity. This is in contrast to using an inorganic adhesion promotor using a dry SAP flow, for example using SiNx with dry etching and a sputter seed process, which is less cost-effective.
Embodiments described herein may improve the performance of transmission lines within packages by enabling them to operate at higher frequencies while maintaining a package insert loss budget by forming copper connections with smooth copper surfaces to reduce insertion loss and to improve overall package mechanical stability.
In legacy implementations, smooth copper surfaces that are used during manufacture, for example during substrate manufacture, may cause weak bonding between a dielectric, for example an organic dielectric that is laminated or otherwise placed on the copper surface. This weak bonding may result in delamination, which may result in the failure of the package. In legacy implementations, adhesion between dielectric and copper surfaces has been increased by roughening the copper surface to provide an anchor to which the laminated dielectric may mechanically adhere. However, in these legacy implementations, the roughened surface of the copper results in a higher insertion loss for higher frequencies of the signal being transmitted, as compared to smooth surfaces of copper.
In a first group of implementations, a non-roughening dielectric adhesion promotion solution for copper surfaces has used organic adhesion promoters that rely on spray and/or dipping equipment to deposit a base adhesion film, where a film growth on the surface of the copper is driven by a copper-ligand complexation at the copper surface. This induces a three-dimensional intermolecular polymerization to form the bulk film matrix. At this point, a process flow for wet adhesion promoters uses a wet desmear process post via drilling to clean and mechanically etch dielectrics inside of the via to enable a good adhesion using an electroless seed layer.
However, this first group of implementations start from a tri-functional group-ended monomer in the deposition solution. This involves gathering all functionalities into one molecule structure and limits the flexibility on the molecular design and synthesis, in which case some of the more favorable functional groups with the desired adhesion performance may not be practically utilized. Furthermore, these implementations rely on inter-molecular polymerization and complexation to form the film matrix, which results in highly disordered three-dimensional stack-ups and thus may result in potential film defects and low bonding density. As a result, the overall effective adhesion between copper and dielectric may be compromised. The weak bonding strength and vulnerability from downstream manufacturing processes that include wet desmear chemistry (e.g. a microetch), may cause a wet chemical attack of organic or inorganic adhesive promoters during subsequent processing may result in interface failure and reliability issues.
In a second group of implementations, an inorganic adhesion promoter, for example silicon nitride (SiNx) thin film, may be deposited by a plasma enhanced chemical vapor deposition (PECVD) process or by a sputtering process. This may act as a diffusion barrier to prevent oxidation of a copper substrate by forming a bond with the copper. A process flow for dry adhesion promoters may involve dry desmear processes post via drilling to completely remove any dielectric residual in the via without mechanically etching dielectrics inside of a via. Thus, a dry sputter seed layer is required to enable good adhesion to the dielectric surface.
However, the second group of implementations has a high manufacturing process cost and is challenging to use for high-volume manufacturing. In addition, downstream processes after the PECVD or sputtering, for example desmear and seed, are typically dry processes that are plasma based to enable SiNx technology. This causes the overall cost of the integrated process to ramp up significantly. As a result, the overall process flow involving SiNx deposition, dry etch, and sputtered seed processes is not cost-effective due to, but not limited to, the highly expensive toolsets, limited process throughputs, and underdeveloped tools and processes needed to implement these processes.
In the following detailed description, reference is made to the accompanying drawings which form a part hereof, wherein like numerals designate like parts throughout, and in which is shown by way of illustration embodiments in which the subject matter of the present disclosure may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of embodiments is defined by the appended claims and their equivalents.
For the purposes of the present disclosure, the phrase “A and/or B” means (A), (B), or (A and B). For the purposes of the present disclosure, the phrase “A, B, and/or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).
The description may use perspective-based descriptions such as top/bottom, in/out, over/under, and the like. Such descriptions are merely used to facilitate the discussion and are not intended to restrict the application of embodiments described herein to any particular orientation.
The description may use the phrases “in an embodiment,” or “in embodiments,” which may each refer to one or more of the same or different embodiments. Furthermore, the terms “comprising,” “including,” “having,” and the like, as used with respect to embodiments of the present disclosure, are synonymous.
The term “coupled with,” along with its derivatives, may be used herein. “Coupled” may mean one or more of the following. “Coupled” may mean that two or more elements are in direct physical or electrical contact. However, “coupled” may also mean that two or more elements indirectly contact each other, but yet still cooperate or interact with each other, and may mean that one or more other elements are coupled or connected between the elements that are said to be coupled with each other. The term “directly coupled” may mean that two or more elements are in direct contact.
Various operations may be described as multiple discrete operations in turn, in a manner that is most helpful in understanding the claimed subject matter. However, the order of description should not be construed as to imply that these operations are necessarily order dependent.
As used herein, the term “module” may refer to, be part of, or include an ASIC, an electronic circuit, a processor (shared, dedicated, or group) and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.
Various Figures herein may depict one or more layers of one or more package assemblies. The layers depicted herein are depicted as examples of relative positions of the layers of the different package assemblies. The layers are depicted for the purposes of explanation, and are not drawn to scale. Therefore, comparative sizes of layers should not be assumed from the Figures, and sizes, thicknesses, or dimensions may be assumed for some embodiments only where specifically indicated or discussed.
Additional dielectric layers 108 are physically coupled, for example laminated to the roughened surface 104a and the roughened surface 106a. The roughened surfaces promote a solid bond to minimize delamination of the additional dielectric layers 108 from the first trace 104 and the second trace 106.
In legacy implementations, a copper via 110 may be created and electrically coupled with the first trace 104 by removing a portion of the dielectric layers 108 above a roughened surface 104b of the first trace 104, and filling the removed portion with copper. The copper deposited in the copper via 110 is in physical and electrical contact with a portion of the roughened surface 104b of the first trace 104. Additional copper 112 may be deposited on the dielectric layers 108. As a result of the roughened interface, insertion loss may be increased during operation, as is discussed further below.
In embodiments, additional dielectric layers 158 may be placed, or laminated, on the OAP layer 120 that at least partially covers the first trace 154 and the second trace 156. In embodiments, the OAP layer facilitates bonding between the traces 154, 156 and the dielectric layers 158. In embodiments, a copper via 160 may be placed on the surface 154a of the first trace 154 by removing a portion of the dielectric layers 158. In embodiments, a portion of the OAP layer 120 may be removed prior to deposition of the copper, as described further below, to form the copper via 160. As a result, a physical and electrical interface 154a between the first trace 154 and the copper via 160 is formed that is smooth. As a result of the smooth physical and electrical interface 154a, insertion loss between the copper via 160 and the first trace 154 is reduced. Additional copper 162 may be deposited on the dielectric layers 158.
Diagram 200A shows a cross-section side view of an enlargement of a portion of illustration 200. As shown, the surface of the copper trace 254 at the OAP layer 220 is smooth, and not rough. In embodiments, the OAP layer may have a roughness that is less than 100 nm. As shown, there is good adhesion between the dielectric layers 258 and the copper trace 254, with no delamination or gap at the interfaces. In embodiments, the copper trace 254 may have a roughness that is less than 100 nm.
Subsequently, a drill process, that may include a laser drill, may be used to create a cavity 316 within the dielectric 308 to expose a portion of the roughened surface 304b, which is a portion of roughened surface 304a of
This legacy process that is shown with respect to
In embodiments, the dielectric layer 452 may be a dielectric layer within a substrate, or may be a wafer. Note that the top surface 454a of the first copper trace 454 and the top surface 456a of the second copper trace 456 are smooth. This smoothness may be a result of the legacy deposition techniques for depositing the first copper trace 454 and the second copper trace 456 on the dielectric layer 452. Note that in embodiments, the first copper trace 454 and the second copper trace 456 have not been roughened.
Subsequently, a drill process, that may include a laser drill, may be used to create a cavity 416 within the dielectric 458 to expose a portion of the surface 454a of the copper trace 454. In embodiments, the laser drill may be a CO2 or ultraviolet (UV) laser drill. In embodiments, the surface 454a of copper trace 454 may be similar to the surface 154a of the first copper trace 154 of
At block 502, the process may include providing a dielectric layer. In embodiments, the dielectric layer may be similar to dielectric layer 152 of
At block 504, the process may further include forming a trace on a surface of the dielectric layer, wherein the trace includes copper. In embodiments, the trace may be similar to first copper trace 154 or second copper trace 156 of
At block 506, the process may further include placing a layer of an organic adhesion promoter (OAP) on a surface of the trace. In embodiments, the OAP may be similar to OAP 220 of
In an embodiment, the electronic system 600 is a computer system that includes a system bus 620 to electrically couple the various components of the electronic system 600. The system bus 620 is a single bus or any combination of busses according to various embodiments. The electronic system 600 includes a voltage source 630 that provides power to the integrated circuit 610. In some embodiments, the voltage source 630 supplies current to the integrated circuit 610 through the system bus 620.
The integrated circuit 610 is electrically coupled to the system bus 620 and includes any circuit, or combination of circuits according to an embodiment. In an embodiment, the integrated circuit 610 includes a processor 612 that can be of any type. As used herein, the processor 612 may mean any type of circuit such as, but not limited to, a microprocessor, a microcontroller, a graphics processor, a digital signal processor, or another processor. In an embodiment, the processor 612 includes, or is coupled with, an organic adhesion promotor for dielectric adhesion to a copper trace, as disclosed herein. In an embodiment, SRAM embodiments are found in memory caches of the processor. Other types of circuits that can be included in the integrated circuit 610 are a custom circuit or an application-specific integrated circuit (ASIC), such as a communications circuit 614 for use in wireless devices such as cellular telephones, smart phones, pagers, portable computers, two-way radios, and similar electronic systems, or a communications circuit for servers. In an embodiment, the integrated circuit 610 includes on-die memory 616 such as static random-access memory (SRAM). In an embodiment, the integrated circuit 610 includes embedded on-die memory 616 such as embedded dynamic random-access memory (eDRAM).
In an embodiment, the integrated circuit 610 is complemented with a subsequent integrated circuit 611. Useful embodiments include a dual processor 613 and a dual communications circuit 615 and dual on-die memory 617 such as SRAM. In an embodiment, the dual integrated circuit 610 includes embedded on-die memory 617 such as eDRAM.
In an embodiment, the electronic system 600 also includes an external memory 640 that in turn may include one or more memory elements suitable to the particular application, such as a main memory 642 in the form of RAM, one or more hard drives 644, and/or one or more drives that handle removable media 646, such as diskettes, compact disks (CDs), digital variable disks (DVDs), flash memory drives, and other removable media known in the art. The external memory 640 may also be embedded memory 648 such as the first die in a die stack, according to an embodiment.
In an embodiment, the electronic system 600 also includes a display device 650, an audio output 660. In an embodiment, the electronic system 600 includes an input device such as a controller 670 that may be a keyboard, mouse, trackball, game controller, microphone, voice-recognition device, or any other input device that inputs information into the electronic system 600. In an embodiment, an input device 670 is a camera. In an embodiment, an input device 670 is a digital sound recorder. In an embodiment, an input device 670 is a camera and a digital sound recorder.
As shown herein, the integrated circuit 610 can be implemented in a number of different embodiments, including a package substrate having an organic adhesion promotor for dielectric adhesion to a copper trace, according to any of the several disclosed embodiments and their equivalents, an electronic system, a computer system, one or more methods of fabricating an integrated circuit, and one or more methods of fabricating an electronic assembly that includes a package substrate having an organic adhesion promotor for dielectric adhesion to a copper trace, according to any of the several disclosed embodiments as set forth herein in the various embodiments and their art-recognized equivalents. The elements, materials, geometries, dimensions, and sequence of operations can all be varied to suit particular I/O coupling requirements including array contact count, array contact configuration for a microelectronic die embedded in a processor mounting substrate according to any of the several disclosed package substrates having an organic adhesion promotor for dielectric adhesion to a copper trace, embodiments and their equivalents. A foundation substrate may be included, as represented by the dashed line of
The following paragraphs describe examples of various embodiments.
Example 1 is a die comprising: a substrate; a feature that includes copper, wherein the feature has a first side and a second side opposite the first side, wherein the second side of the feature is coupled with the substrate; a layer that includes an organic adhesion promoter (OAP) on at least a portion of the first side of the feature; and a layer that includes a dielectric on the layer that includes the OAP.
Example 2 includes the die of example 1, or of any other example or embodiment herein, wherein the OAP includes a selected one or more of: silicon, silicane, a silicane-based self-assembly layer, or an organic-based adhesive.
Example 3 includes the die of example 1, or of any other example or embodiment herein, wherein a surface of the first side of the feature has a roughness that is less than 100 nm.
Example 4 includes the die of example 1, or of any other example or embodiment herein, wherein the feature that includes copper is a copper trace.
Example 5 includes the die of example 1, or of any other example or embodiment herein, wherein the OAP is on a first portion of the first side of the feature, and wherein the OAP is not on a second portion of the first side of the feature.
Example 6 includes the die of example 5, or of any other example or embodiment herein, further comprising copper on the second portion of the first side of the feature.
Example 7 includes the die of example 6, or of any other example or embodiment herein, wherein the copper on the second portion of the first side of the feature includes a copper seed.
Example 8 includes the die of example 1, or of any other example or embodiment herein, wherein the first side of the feature, the OAP on the first side of the feature, and the layer that includes a dielectric on the OAP form a continuous layer.
Example 9 includes the die of example 1, or of any other example or embodiment herein, wherein the substrate includes a dielectric material.
Example 10 includes the die of example 1, or of any other example or embodiment herein, wherein the layer that includes the OAP has a thickness between 2 nm and 200 μm.
Example 11 is a package comprising: a die; and a substrate electrically coupled with the die, the substrate comprising: a first dielectric layer; a trace that includes copper on the first dielectric layer; a layer that includes an organic adhesion promoter (OAP) on a first portion of a surface of the trace; and a second dielectric layer on the layer that includes the OAP on the first portion of the surface of the trace.
Example 12 includes the package of example 11, or of any other example or embodiment herein, wherein the OAP includes a selected one or more of: silicon, silicane, a silicane-based self-assembly layer, or an organic-based adhesive.
Example 13 includes the package of example 11, or of any other example or embodiment herein, wherein the trace further includes a second portion of the surface of the trace that does not include an OAP on the second portion of the surface of the trace.
Example 14 includes the package of example 13, or of any other example or embodiment herein, further including an electrically conductive material on the second portion of the surface of the trace.
Example 15 includes the package of example 14, or of any other example or embodiment herein, wherein the electrically conductive material includes copper.
Example 16 includes the package of example 14, or of any other example or embodiment herein, wherein the electrically conductive material includes copper seed.
Example 17 includes the package of example 11, or of any other example or embodiment herein, further including OAP on an edge of the trace between the surface of the trace and the surface of the first dielectric layer.
Example 18 includes the package of example 11, or of any other example or embodiment herein, wherein the surface of the trace has a roughness that is less than 100 nm.
Example 19 is a method comprising: providing a dielectric layer; forming a trace on a surface of the dielectric layer, wherein the trace includes copper; and placing a layer of an organic adhesion promoter (OAP) on a surface of the trace.
Example 20 includes the method of example 19, or of any other example or embodiment herein, wherein the OAP includes a selected one or more of: silicon, silicane, a silicane-based self-assembly layer, or an organic-based adhesive.
Example 21 includes the method of example 19, or of any other example or embodiment herein, wherein a thickness of the layer of OAP is less than 200 μm.
Example 22 includes the method of example 19, or of any other example or embodiment herein, wherein the dielectric layer is a first dielectric layer; and further comprising forming a second dielectric layer on the layer of the OAP on the surface of the trace.
Example 23 includes the method of example 22, or of any other example or embodiment herein, further comprising: removing a portion of the layer of the OAP and a portion of the second dielectric layer above the portion of the layer of the OAP; and placing a material that includes copper within the removed portion of the layer of the OAP and the removed portion of the second dielectric layer, wherein the material that includes copper is electrically coupled with the trace.
Example 24 includes the method of example 23, or of any other example or embodiment herein, wherein removing the portion of the layer of the OAP and the portion of the second dielectric layer above the portion of the layer of the OAP further includes: drilling the portion of the second dielectric layer above the portion of the layer of the OAP; exposing a portion of a surface of the trace by removing the portion of the layer of the OAP using a dry desmear process; and sputtering a copper seed onto the exposed portion of the surface of the trace.
Various embodiments may include any suitable combination of the above-described embodiments including alternative (or) embodiments of embodiments that are described in conjunctive form (and) above (e.g., the “and” may be “and/or”). Furthermore, some embodiments may include one or more articles of manufacture (e.g., non-transitory computer-readable media) having instructions, stored thereon, that when executed result in actions of any of the above-described embodiments. Moreover, some embodiments may include apparatuses or systems having any suitable means for carrying out the various operations of the above-described embodiments.
The above description of illustrated embodiments, including what is described in the Abstract, is not intended to be exhaustive or to limit embodiments to the precise forms disclosed. While specific embodiments are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the embodiments, as those skilled in the relevant art will recognize.
These modifications may be made to the embodiments in light of the above detailed description. The terms used in the following claims should not be construed to limit the embodiments to the specific implementations disclosed in the specification and the claims. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.