Patent Application
20140262440
An embodiment described herein relates generally to package substrates and in particular to a multi-layer core organic package substrate.
In fabricating an integrated circuit (IC) package, one or more integrated circuit (IC) dies may be placed on a package substrate to form an integrated circuit package. The package substrate serves to provide mechanical stability to the one or more integrated circuit (IC) dies as well as interconnections for the one or more integrated circuit (IC) dies. The package substrate may provide interconnectivity to input/output (I/O), power sources (e.g., supply power or ground), configuration information, etc.
One type of package substrate conventionally used in fabricating IC packages is a single-core organic package substrate. Single-core organic package substrates include a single organic core layer composed of an organic material and one or more build-up layers formed on top or below the single organic core layer. The one or more build-up layers provide interconnectivity for I/O, power, configuration information, etc. While single-core organic package substrates have several desirable characteristics for particular applications, such single-core organic package substrates include several deficiencies which may make them undesirable for integrated circuit (IC) dies that operate using high-speed signals (e.g., signal transmission rates greater than 16 gigabits per second (Gbps)). Some of these deficiencies include conductor loss and dielectric loss, which may lead to errors and undesirable performance of the IC package when operating at high speeds.
Another type of package substrate used for fabricating is a ceramic package substrate. Ceramic package substrates include several ceramic package layers formed using ceramic material that provide interconnectivity for I/O, power, configuration information, etc., for the one or more integrated circuit (IC) dies using the ceramic package substrate. Ceramic packages are preferred over single-core organic package substrates for high-speed applications because they have much more desirable loss characteristics in comparison to single-core organic package substrates. The dielectric loss and conductor loss associated with a ceramic package substrate is significantly less than that associated with the single-core organic package substrate and as such provides a better package substrate option for high-speed applications. However, costs associated with ceramic package substrates may be significantly greater than those associated with single-core organic package substrates. Additionally, significant noise associated with power distribution within ceramic package substrates may be present as well as cross-talk between ceramic package layers. Furthermore, the ceramic package substrates may have poor board level reliability, resulting in ceramic package substrates providing mechanical support for only a limited number of ceramic package layers.
A multi-layer core organic package substrate includes: a multi-layer core comprising at least two organic core layers, wherein two of the at least two organic core layers are separated by a core metal layer; a first plurality of build-up layers formed on top of the multi-core layer; and a second plurality of build-up layers formed below the multi-core layer.
Optionally, the at least two organic core layers may comprise a center organic core layer and an additional organic core layer on one of a top side and a bottom side of the center organic core layer.
Optionally, the additional organic core layer on one of the top side and the bottom side of the center core layer may be configured to support high-speed signal transmission.
Optionally, the additional organic core layer may have a greater thickness than a thickness of the center organic core layer.
Optionally, the at least two organic core layers may comprise a center organic core layer, a top organic core layer on a top side of the center organic core layer, and a bottom organic core layer on a bottom side of the center organic core layer.
Optionally, at least one of (1) the first plurality of build-up layers and (2) the second plurality of build-up layers may comprise a metal build-up layer and a dielectric build-up layer.
Optionally, the core metal layer may have a greater thickness than a thickness of the metal build-up layer.
Optionally, one of the at least two organic core layers may have a greater thickness than the dielectric build-up layer.
Optionally, the core metal layer may be configured to support a high-speed signal transmission rate of at least 28 gigabits per second (Gbps).
Optionally, the at least two organic core layers may comprise at least 10 organic core layers.
Optionally, at least one of (1) the first plurality of build-up layers and (2) the second plurality of build-up layers may be configured to be impedance-matched with incoming high-speed signals.
Optionally, at least one of the first plurality of build-up layers, the second plurality of build-up layers, and the multi-layer organic core, may be configured to provide one of I/O, power, ground, and configuration interconnectivity.
Optionally, the multi-layer organic core may be configured to support an integrated circuit (IC) die.
Optionally, at least one of (1) the first plurality of build-up layers and (2) the second plurality of build-up layers may include an organic substrate.
Optionally, the multi-layer core may further comprise an additional core metal layer, and the at least two organic core layers may comprise three organic core layers that are separated by the core metal layer and the additional core metal layer.
A method for forming a multi-layer core organic package substrate, includes: forming a multi-layer organic core comprising at least two organic core layers, wherein two of the at least two organic core layers are separated by a core metal layer; forming a first plurality of build-up layers on top of the multi-core layer; and forming a second plurality of build-up layers below the multi-core layer.
Optionally, the formed multi-layer core may comprise a center organic core layer and an additional organic core layers on one of a top side and a bottom side of the center organic core layer.
Optionally, the additional organic core layers may have a greater thickness than the center organic core layer.
Optionally, at least one of (1) the first plurality of build-up layers and (2) the second plurality of build-up layers may include a metal build-up layer and a dielectric build-up layer.
Optionally, the at least two organic core layers comprise three organic core layers, and the formed multi-layer organic core may comprise an additional core metal layer, and wherein the three organic core layers may be separated by the core metal layer and the additional core metal layer.
Other and further aspects and features will be evident from reading the following detailed description.
The drawings illustrate the design and utility of various features described herein, in which similar elements are referred to by common reference numerals. These drawings are not necessarily drawn to scale. In order to better appreciate how the above-recited and other advantages and objects are obtained, a more particular description will be rendered, which are illustrated in the accompanying drawings. These drawings depict only exemplary features and are not therefore to be considered limiting in the scope of the claims.
Various features are described hereinafter with reference to the figures. It should be noted that the figures are not drawn to scale and that the elements of similar structures or functions are represented by like reference numerals throughout the figures. It should be noted that the figures are only intended to facilitate the description of the features. They are not intended as an exhaustive description of the claimed invention or as a limitation on the scope of the claimed invention. In addition, an illustrated embodiment need not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced in any other embodiments even if not so illustrated.
In fabricating an integrated circuit (IC) package, one or more integrated circuit (IC) dies may be placed on a package substrate to form an integrated circuit package.
The integrated circuit package may include one or more integrated circuit (IC) dies 101, a package substrate 105, and one or more microbumps 103 forming connections between the integrated circuit dies 101 and the package substrate 105. The integrated circuit die(s) 101 may perform different functionalities or may perform the same functionality. The package substrate 105 may be configured to support homogenous IC dies (e.g., IC dies that perform the same functionalities), heterogeneous IC dies (e.g., IC dies that perform different functionalities), or both.
The package substrate 105 serves to provide mechanical stability to the one or more integrated circuit (IC) dies 101 as well as interconnections for the one or more integrated circuit (IC) dies 101. The package substrate 105 may provide interconnectivity for input/output (I/O), power (e.g., supply power or ground), configuration information, etc. Interconnectivity for the one or more integrated circuit (IC) dies 101 may be provided through various metal layers (not shown) formed within the package substrate 105.
One type of package substrate that may be used in fabricating IC packages is a single-core organic package substrate.
Each build-up layer 208 of the plurality of build-up layers 207 includes a metal build-up layer 201 and a dielectric build-up layer 203. The metal build-up layers 201 of the respective build-up layers 208 may be connected through metal vias 205 formed in the dielectric build-up layers 203. Additionally, a bottom most metal build-up layer 201 of the first plurality build-up layers 207 may be connected to a top most metal build-up layer 201 of the second plurality of build-up layers 207′ through metal vias 205 in the single organic core 209. The build-up layers 208 provide interconnectivity for IC dies connected to the single core organic package substrate 200 for I/O, power, configuration information, etc. Signals to and from IC dies connected to the single core organic package substrate 200 may be transmitted through the metal build-up layers 201 and metal vias 205 in the dielectric build-up layers 203.
While single-core organic package substrates 200 have several desirable characteristics for particular applications, such single-core organic package substrates include several deficiencies which may make them undesirable for integrated circuit (IC) dies that operate using high-speed signals (e.g., signal transmission rates greater than 16 gigabits per second (Gbps)). Some of these deficiencies include conductor loss and dielectric loss, which may lead to errors and undesirable performance of the IC package when operating at high speeds.
One way to reduce conductor loss and dielectric loss is to implement wider metal build-up layers 201 for each build-up layer 208 of the single-core organic package substrate 200. However, increasing metal build-up layer 201 thickness may lead to a lower impedance for the single core organic package substrate 200. The lower impedance attributed to increasing metal build-up layer 201 thickness cannot be compensated for by simply increasing dielectric build-up layer 203 thickness because of design constraints associated with the single core organic package substrate 200. Impedance matching is critical for package substrates because impedance mismatch can lead to severe reflection loss during the transmission of signals. Because increasing metal build-up layer 201 thickness to support high-speed signal transmission in single core organic package substrates 200 leads to impedance mismatch, single core organic package substrates 200 cannot support high speed signal transmission.
The single organic core 209 may support wider metal build-up layers 201 adjacent to the single organic core 209 because the organic core 209 has a greater thickness than the dielectric build-up layers 203. However with only a single organic core 209 signal density issues and high dielectric loss may still arise, making it undesirable to route high-speed signals through the metal build-up layers 201 adjacent to the single organic core 209 regardless of the metal build-up layer 201 thickness.
Another type of package substrate that may be used for fabricating IC packages is a ceramic package substrate.
The ceramic package layers 304 provide interconnectivity for IC dies connected to the ceramic package substrate 300 for I/O, power, configuration information, etc. Signals to and from IC dies connected to the ceramic package substrate 300 may be transmitted through the metal ceramic package layers 301 and metal vias 305.
Ceramic package substrates 300 may be preferred over single-core organic package substrates 200 for high-speed applications because they have much more desirable loss characteristics in comparison to single-core organic package substrates 200. The dielectric loss and conductor loss associated with a ceramic package substrate 300 may be significantly less than that associated with the single-core organic package substrate 200, and as such, may provide a better package substrate option for high-speed applications. However, costs associated with ceramic package substrates 300 may be significantly greater than those associated with single-core organic package substrates. Additionally, significant noise associated with power distribution within ceramic package substrates may be present as well as cross-talk between ceramic package layers 304, thereby reducing its ability to provide flexible high speed signal transmission to IC dies. Furthermore, the ceramic package substrates 300 may have poor board level reliability, resulting in ceramic packages providing mechanical support to only a limited number of ceramic package layers 304. Organic package substrates 200, on the other hand, exhibit desirable power distribution characteristics, insignificant cross-talk between build-up layers, and strong board level reliability, but cannot support high speed signal transmission due to its channel loss characteristics.
It would therefore be desirable to utilize the advantages of the single-core organic package substrate including its power distribution characteristics, insignificant cross-talk between build-up layers, and strong board-level reliability while minimizing conductor loss and dielectric loss such that high-speed signal transmission may be supported.
A multi-layer organic core package substrate provides the advantages of the single organic core package substrate while minimizing conductor loss and dielectric loss such that high-speed signal transmission may be supported.
The multi-layer organic core organic package substrate 400 includes a multi-layer organic core 409, a first plurality of build-up layers 207 formed on top of the multi-layer organic core 409, and a second plurality of build-up layers 207′ formed below the multi-layer organic core 409. The first plurality of build-up layers 207 or second plurality of build-up layers 207′ may include (e.g., be formed using) an organic substrate.
The multi-layer organic core 409 includes multiple organic core layers 411, 413 separated by core metal layers 401. The multi-layer organic core 409 may include a center organic core layer 413 and one or more additional organic core layers 411. It should be noted that the center organic core layer 413 may or may not be located at the middle or center location in the multi-layer organic core 409. For example, in some cases, the center organic core layer 413 may be offset from the center location in the multi-layer organic core 409, as long as it is not located at the top-most or bottom-most layer. One additional organic core layer 411 may be formed on a top side of the center organic core layer 413. Another additional organic core layer 411 may be formed on a bottom side of the center organic core layer 413. The core metal layers 401 may be connected through metal vias 405 formed in the organic core layers 411, 413.
In some cases, at least one of the one or more additional organic core layers 411 may have a greater thickness than the center organic core layer 413. In other cases, at least one of the one or more additional organic core layers 411 may have a thickness less than or equal to the center organic core layer 413.
While
Each build-up layer 208 of the first plurality of build-up layers 207 includes a metal build-up layer 201 and a dielectric build-up layer 203. The metal build-up layers 201 of the respective build-up layers 208 may be connected through metal vias 205 in the dielectric build-up layers 203. A bottom most metal build-up layer 201 of the first plurality build-up layers 207 may be connected to a core metal layer 401 through a core metal via 405 formed within the organic core layer 411. Likewise, a top most metal build-up layer 201 of the second plurality of build-up layers 207 may be connected to a core metal layer 401 through a core metal via 405 within the organic core layer 411.
The build-up layers 208 and organic core layers 411, 413 provide interconnectivity for IC dies connected to the multi-layer core organic package substrate 400 for I/O, power, configuration information, etc. Signals to and from IC dies connected to the multi-layer core organic package substrate 400 may travel through the metal build-up layers 201, core metal layers 401, metal vias 205 and core metal vias 405.
In some cases, at least one (or each) of the core metal layers 401 separating the organic core layers 411, 413 has a greater thickness than a metal build-up layer 201. Increasing the thickness of the core metal layer(s) 401 reduces conductor loss and dielectric loss, such that the multi-layer organic core package substrate 400 can support high-speed signal transmission. The decrease in impedance associated with implementing thicker core metal layer(s) 401 can be compensated for by increasing the thickness of the additional organic core layer(s) 411. In some cases, at least one (or each) of the one or more organic core layers 411, 413 may have a greater thickness than a dielectric build-up layer 203. Increasing the thickness of the additional organic core layer(s) 411 allows for the multi-layer organic core package substrate 400 to be impedance-matched with incoming high-speed signals from integrated circuit dies connected to the multi-layer organic core package substrate 400. This allows for reduction (or minimization) of reflection loss that may occur during transmission of signals.
Additionally, having more organic core layers 411, 413 allows for additional routing paths for high speed signal transmission. Whereas the single organic core package substrate 200 only had two metal layers 201 adjacent to the single organic core layer 209, the multi-layer core organic package substrate 400 has multiple metal layers 401, 201 adjacent to organic core layers 411, 413. These adjacent metal layers 401, 201 may have greater thicknesses to support high-speed signal transmission while maintaining optimal impedance by configuring the organic core layer 411, 413 to have certain desired thicknesses.
In some cases, high-speed signals may be routed through the metal build-up layers 201 and core metal layers 401 adjacent to the organic core layers 411, 413 because signal density issues and high dielectric loss are minimized by the multi-layer organic core 409 configuration. This is in contrast to the single organic core 209 of
In some cases, the multi-layer core organic package substrate 400 may support high-speed signal transmission rates at or above 28 gigabits per second (Gbps). In other cases, the multi-layer core organic package substrate may support signal transmission rates below 28 Gbps.
Thus, by implementing a multi-layer organic core package substrate 400, transmission of high-speed signals may be supported with minimal conductor loss and dielectric loss, while at the same time retaining the power distribution characteristics, insignificant cross-talk between build-up layers, and strong board-level reliability of the single-core organic package substrate 200 of
In some cases, at least one of the one or more additional organic core layers may have a greater thickness than the center organic core layer. In other cases, at least one of the one or more additional organic core layers may have a thickness less than or equal to the center organic core layer.
Returning to
Next, a second plurality of build-up layers may then be formed below the multi-layer organic core as shown at item 505. The second plurality of build-up layers may include (e.g., be formed using) an organic substrate. Each build-up layer includes a metal build-up layer and a dielectric build-up layer. The metal build-up layers of each build-up layer may be connected through metal vias formed in the dielectric build-up layer.
A bottom most metal build-up layer of the first plurality build-up layers may be connected to a core metal layer through a core metal via formed within the organic core layer. Likewise, a top most metal build-up layer of the second plurality of build-up layers may be connected to a core metal layer through a core metal via within the organic core layer.
The build-up layers and organic core layers provide interconnectivity for IC dies connected to the multi-layer core organic package substrate for I/O, power, configuration information, etc. Signals to and from IC dies connected to the multi-layer core organic package substrate may be transmitted through the metal build-up layers, core metal layers, metal vias and core metal vias.
As mentioned above, in some cases, the core metal layer(s) separating the organic core layers may have a greater thickness than the metal build-up layers. Increasing the core metal layer(s) thickness reduces conductor loss and dielectric loss, such that the multi-layer organic core package substrate can support high-speed signal transmission. The decrease in impedance associated with implementing thicker core metal layer(s) may be compensated for by increasing the thickness of the additional organic core layer(s). In some cases, at least one of the one or more organic core layers may have a greater thickness than a dielectric build-up layer. Increasing the thickness of the additional organic core layer(s) allows for the multi-layer organic core package substrate to be impedance-matched with incoming high-speed signals from integrated circuit dies connected to the multi-layer organic core package substrate. This may allow for a reduction or minimization of reflection loss that occurs during the transmission of signals.
In some cases, high-speed signals may be routed through the metal build-up layers and core metal layers adjacent to the organic core layers because signal density issues and high dielectric loss may be reduced or minimized by the multi-layer organic core configuration. This is in contrast to the single organic core, where signal density issues and high dielectric loss would make it undesirable to route high-speed signals through the metal build-up layers adjacent to the single organic core.
Thus, by implementing a multi-layer organic core package substrate 400, transmission of high-speed signals may be supported with minimal conductor loss and dielectric loss, while at the same time retaining the power distribution characteristics, insignificant cross-talk between build-up layers, and strong board-level reliability of the single-core organic package substrate.
It should be noted that the term “on top”, as used in this specification, may refer to directly on top, or indirectly on top. For example, when the first plurality of build-up layers is described as being formed “on top” of the multi-layer organic core, the first plurality of build-up layers may be either directly on top (e.g., abutting) of the multi-layer organic core, or indirectly on top of the multi-layer organic core (e.g., the first plurality of build-up layers may be on another layer that is between the first plurality of build-up layers and the multi-layer organic core).
Likewise, it should be noted that the term “below”, as used in this specification, may refer to directly below, or indirectly below. For example, when the second plurality of build-up layers is described as being formed “below” the multi-layer organic core, the second plurality of build-up layers may be either directly below (e.g., abutting) the multi-layer organic core, or indirectly below the multi-layer organic core (e.g., the second plurality of build-up layers may be on another layer that is between the second plurality of build-up layers and the multi-layer organic core). Note also that “on top” and “below” are relative terms, and that this specification contemplates various orientations and is broad enough to encompass such orientations.
Also, as used in this specification, the term “plurality” may refer to two or more items. For example, a “plurality” of build-up layers may refer to two or more build-up layers, which may or may not be all of the available build-up layers. Accordingly, the phrase “each” build-up layer may refer to each of two or more build-up layers, which may or may not be all of the available build-up layers.
Although particular features have been shown and described, it will be understood that they are not intended to limit the claimed invention, and it will be made obvious to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the claimed invention. The specification and drawings are, accordingly to be regarded in an illustrative rather than restrictive sense. The claimed invention is intended to cover all alternatives, modifications and equivalents.
