Core layer with fully encapsulated co-axial magnetic material around PTH in IC package substrate

Embodiments may include inductors with embedded magnetic cores and methods of making such inductors. In an embodiment, an integrated circuit package may include an integrated circuit die with a multi-phase voltage regulator electrically coupled to the integrated circuit die. In such embodiments, the multi-phase voltage regulator may include a substrate core and a plurality of inductors. The inductors may include a conductive through-hole disposed through the substrate core and a plugging layer comprising a dielectric material surrounding the conductive through-hole. In an embodiment, a magnetic sheath is formed around the plugging layer. In an embodiment, the magnetic sheath is separated from the plated through hole by the plugging layer. Additionally, a first layer comprising a dielectric material may be disposed over a first surface of the magnetic sheath, and a second layer comprising a dielectric material may be disposed over a second surface of the magnetic sheath.

TECHNICAL FIELD

Embodiments of the present disclosure relate to power management solutions, and in particular to methods and apparatuses that include embedded magnetic sheaths for use in co-axial inductors.

BACKGROUND

Efficient power management is crucial for many integrated circuit (IC) technologies, especially for high end server devices. Currently, voltage regulation in some ICs may be implemented with imbedded voltage regulators. Such embedded voltage regulators often use air coil inductors (ACIs) formed by plating through hole walls with copper. However, ACIs may not provide the desired inductance. In order to increase the inductance, more ACIs may be formed in series. This increases the overall footprint of the voltage regulators. Additional solutions for increasing the inductances of ACIs have been proposed. For example, a magnetic sheath material may be positioned inside and around the coil.

However, the introduction of magnetic materials results in disruptions to currently used manufacturing processes. The magnetic materials leach and negatively affect chemistries used in the processing of IC substrates. For example, exposed magnetic materials may result in bath contamination during desmear, electroless copper plating, and subtractive etching processes.

EMBODIMENTS OF THE PRESENT DISCLOSURE

Described herein are systems with fully embedded magnetic materials on IC substrates and methods of forming such systems. More particularly, embodiments include co-axial inductors with fully embedded magnetic material and methods of forming such devices. In the following description, various aspects of the illustrative implementations will be described using terms commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. However, it will be apparent to those skilled in the art that the present invention may be practiced with only some of the described aspects. For purposes of explanation, specific numbers, materials and configurations are set forth in order to provide a thorough understanding of the illustrative implementations. However, it will be apparent to one skilled in the art that the present invention may be practiced without the specific details. In other instances, well-known features are omitted or simplified in order not to obscure the illustrative implementations.

As noted above, the inclusion of magnetic materials in the manufacture of IC devices is currently problematic due to the leaching of magnetic materials (e.g., iron, alloys containing iron, and other ferromagnetic particles or elements) into processing baths. Accordingly, it is presently not feasible to integrate components, such as inductors, that include magnetic materials into IC substrates. However, embodiments described herein provide processing methods that allow for the integration of magnetic materials with currently available processing techniques. Particularly, embodiments include fully embedding magnetic materials, so that the magnetic materials are not exposed to processing environments where the leaching of magnetic materials is detrimental. For example, embodiments include embedding the magnetic materials so that the magnetic materials are not exposed to processing environments that have chemistries that may be negatively altered by leached magnetic materials, such as one or more of desmear baths, electroless baths, and subtractive etching baths. Since the magnetic material is isolated from such environments, there is no need to redesign the chemistries of processing baths or provide dedicated processing baths to handle the magnetic materials. Furthermore, isolating the magnetic material allows for subsequent changes to the magnetic material to be made without needing to adjust the chemistries of processing environments. This allows for quicker design times and reduces the cost of development. In embodiments, the magnetic material always interfaces with an organic resin material instead of copper surfaces. This provides better reliability in terms of interface delamination and blistering.

In accordance with an embodiment, the fully embedded magnetic material may be used to form a co-axial inductor. In the co-axial inductors described herein, the magnetic material may be a sheath that surrounds a plated through-hole. The magnetic sheath may be separated from the plated through-hole by a dielectric material. Additionally, a top surface and a bottom surface of the magnetic sheath may be covered by layers of dielectric material, and an outer sidewall surface of the magnetic sheath may be covered by a substrate core. Fully embedding the magnetic sheath simplifies the processing as described above.

Referring now toFIG. 1A, a cross-sectional illustration of an inductor is shown, in accordance with an embodiment. In an embodiment, inductor110may be disposed in and around a substrate core105. In an embodiment, the substrate core105may be any suitable substrate on which build-up layers are formed. The substrate core105may be an organic material with or without reinforcement materials, such as glass fibers, particles, or the like.

In the illustrated embodiment, a single inductor110is shown in order to not obscure various aspects of the embodiment. However, it is to be appreciated that a plurality of inductors110may be electrically coupled in series or in parallel. For example, a plurality of inductors110may be coupled in series to produces a desired inductance, or a plurality of inductors110may be coupled in parallel to provide a multi-phase voltage regulator. For example, a multi-phase voltage regulator may be electrically coupled to an integrated circuit die to provide power management solutions.

As illustrated inFIG. 1A, the inductors110may include a through-hole that extends through the substrate core105. The through-hole may be plated with a conductive layer112. In an embodiment, the plated through-hole112may be copper or any other suitable conductive material. The plated through-holes112may be filled with a dielectric material113, such as an epoxy. The plated through-holes112may have lids119formed on opposing surfaces. The lids119may be conductive materials, such as copper. In an embodiment, the lids may be electrically coupled to other inductors110or circuitry in the substrate core105.

In order to increase the inductance of the inductor110, a magnetic sheath115is formed around the plated through-holes112. In an embodiment, the magnetic sheath115is fully embedded within dielectric materials. In an embodiment, a first surface117A of the magnetic sheath115is in direct contact with a surface of dielectric layer108A, a second surface117E of the magnetic sheath115is in direct contact with a surface of dielectric layer108B, a third (outer) surface117cis in direct contact with the substrate core105, and a fourth (inner) surface117D is in direct contact with a dielectric layer111. In an embodiment, dielectric layers108A and108E may be a prepreg material. The dielectric layers108A and108E may be laminated over surfaces of the substrate core105. In an embodiment, the plated through-holes112may also pass through the dielectric layers108A and108B. As such, the magnetic sheath115is not in contact with any conducting surface, including the lid119and the plated through-hole112. As such, the magnetic sheath115is not exposed to processing environments that are used to form the pated through-hole112or lid119, such as electroless plating environments. Accordingly, currently used processing chemistries may be used without magnetic materials leaching into processing baths.

In an embodiment, the magnetic sheath115may pass entirely through the substrate core105. Surfaces117A and117E of the magnetic sheath115may be substantially coplanar with surfaces106and107of the substrate core105. As used herein, “substantially coplanar” may refer to surfaces that are within +/−2 μm of being coplanar with each other. In an embodiment, the outer surface117cand inner surface117D of the magnetic sheath115may be substantially vertical. As used herein, “substantially vertical” may refer to surfaces that are within +/−5° from 90°. Additional embodiments may include an outer surface117cand an inner surface117D that are tapered surfaces.

The magnetic sheath115may be any suitable magnetic material. In an embodiment, the magnetic sheath115may be a dielectric material that includes magnetic particles. In one embodiment, the magnetic particles may include iron, alloys including iron, or any other elements or alloys that have magnetic properties. In an embodiment, the magnetic sheath115may have a relative permeability greater than 10. In an embodiment, the magnetic sheath115may have a relative permeability greater than 20.

Referring now toFIG. 1B, a cross-sectional illustration of the inductor110along line1-1′ is shown, in accordance with an embodiment.FIG. 1Billustrates a cross-sectional view of an inductor110that has a substantially circular cross-section. In such embodiments, a circular magnetic sheath115may be surrounded by the substrate core105. In an embodiment, the outer surface117cof the magnetic sheath115may be in direct contact with the substrate core105. In an embodiment, the inner surface117D may be in direct contact with dielectric layer111. Dielectric layer111may separate the inner surface117D of the magnetic sheath115from the plated through-hole via112.

The inductance of the inductor110may be controlled by varying the thickness of each layer. For example, the thickness T1of the dielectric layer111may be minimized in order to increase the inductance of inductor110. In an embodiment, the thickness T1may be 50 μm or less. Additionally, the thickness T2of the magnetic sheath115may be increased in order to increase the inductance of the inductor110. In an embodiment, the thickness T2may be 50 μm or more. In embodiments, the outer diameter of each layer may coincide with standard mechanical drill bit sizes. For example, an outer diameter of the magnetic sheath115may be approximately 350 μm, the outer diameter of the dielectric layer111may be approximately 250 μm, and the outer diameter of the plated through-hole via112may be approximately 150 μm. Additional embodiments may include outer diameters that are any diameter, and it is to be appreciated that standard drill bit sizes do not limit the dimensions of various features in the inductor110. For example, laser drilling may be used to provide different dimensions or custom drill bit sizes may be developed to fabricate desired inductances.

Additionally, it is to be appreciated that the cross-sectional shape of the inductor110is not limited to circular shapes, as shown inFIG. 1B. For example,FIG. 1Cillustrates an inductor110that includes a substantially square cross-section. Additional embodiments may also include inductors110that have any other shaped cross-section, including rectangular, elliptical, or any other desired shape.

Referring now toFIGS. 2A-2Ja process flow for forming an inductor with a sheath of magnetic material is shown, in accordance with an embodiment. As will be described below, embodiments include disposing the magnetic sheath into the substrate core and fully embedding the magnetic sheath in order to isolate the magnetic material from subsequent processing environments, such as electroless plating baths, desmear baths, and wet etching chemistries. Accordingly, existing processing operations may be used without the need to have dedicated processing environments to accommodate the magnetic material.

Referring now toFIG. 2A, a cross-sectional illustration of a substrate core205is shown, in accordance with an embodiment. In an embodiment, the substrate core205may be received with metal layers241, such as copper, formed over a first surface206and second surface207of the substrate core205.

Referring now toFIG. 2B, a cross-sectional illustration of the substrate core205is shown after an opening250is formed through the substrate core205, in accordance with an embodiment. In an embodiment, the opening250may be formed through the substrate core205with any suitable process. For example, the opening250may be formed with a mechanical drilling process, a laser drilling process, a wet or dry etching process, or the like. Embodiments may also include an etching process that removes the metal layers241from the first surface206and the second surface207of the substrate core205. In an embodiment, the opening250may be cleaned with a desmear process. In the illustrated embodiment, the sidewalls of the opening250are substantially vertical. However it is to be appreciated that embodiments may also include sidewalls of the opening250that are tapered or otherwise shaped, depending on the process used to form the opening250.

Referring now toFIG. 2C, a cross-sectional illustration of the substrate core after a magnetic material is disposed in the opening is shown, in accordance with an embodiment. In an embodiment, the magnetic sheath215may be disposed in the opening250with any suitable process. In an embodiment, the magnetic sheath215may be plugged into the opening250. After the magnetic material is plugged into the opening250, a polishing process, a grinding process, or the like (e.g., chemical mechanical polishing (CMP)) may be used to remove any overburden of the magnetic material250. The magnetic material used to form the magnetic sheath215may be cured.

In an embodiment, the magnetic sheath215may have a first surface217Athat is substantially coplanar with a first surface206of the substrate core205, and the magnetic sheath215may have a second surface217Ethat is substantially coplanar with a second surface207of the substrate core205. Embodiments may also include an outer sidewall surface217cthat is in direct contact with the substrate core205. The outer surface217cmay conform to the surfaces of the opening250. As such, the profile of the outer surface217cmay match the profile of the opening250(i.e., vertical sidewalls, tapered sidewalls, etc.).

Referring now toFIG. 2D, a cross-sectional illustration of the substrate after an opening is formed through the magnetic sheath is shown, in accordance with an embodiment. In an embodiment, opening251may be formed with an suitable dry process. A dry process may be used in order to not expose the magnetic sheath215to a processing bath (e.g., a wet etching bath). Embodiments may include a mechanical drilling process or a laser drilling process. In the illustrated embodiment, the inner surface217Dformed by opening251is substantially vertical. However it is to be appreciated that embodiments may also include inner surfaces217Dformed by opening251that are tapered or otherwise shaped, depending on the process used to form the opening251.

Referring now toFIG. 2E, a cross-sectional illustration of the substrate core205after a first plugging layer211is disposed into the openings251is shown, in accordance with an embodiment. In an embodiment, the first plugging layer211may be disposed into the openings251with a plugging process, as is known in the art. In an embodiment, the first plugging layer213may be a dielectric material, such as an epoxy or any other suitable material. In an embodiment, the first plugging layer211may be planarized with a top surface217Aand bottom surface217Eof the magnetic sheath215using a polishing or grinding process. In some embodiments, the first plugging layer211may be cured with a curing process. As illustrated, the magnetic sheath215is now embedded on two surfaces, (i.e., the outer surface217cby the substrate core205, and the inner surface217Dby the first plugging layer211).

Referring now toFIG. 2F, a cross-sectional illustration of the substrate core205after dielectric layers208Aand208Bare disposed over the first surface217Aand the second surface217Eof the magnetic sheath215is shown, in accordance with an embodiment. In an embodiment, the dielectric layers208Aand208Bmay be laminated over the first surface206and the second surface207of the substrate core205, respectively. The lamination may be implemented with a hot press. In additional embodiments, the dielectric layers208Aand208Bmay be disposed over the substrate core205with any other dry deposition process, such as printing, chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma enhanced CVD (PECVD), or the like. In an embodiment, the dielectric layers208Aand208Bmay be in direct contact with the first surface217Aand the second surface217Eof the magnetic sheath215, respectively. Accordingly, embodiments include a magnetic sheath215that is fully embedded by the substrate core205, the first plugging layer211, and the first and second dielectric layers208Aand208B. As such, subsequent processing operations may be implemented without exposing the magnetic sheath215to the processing environments.

In the illustrated embodiment, conductive layers261,262are disposed over the first and second dielectric layers208Aand208B. In some embodiments the conductive layers261and262may be formed on the dielectric layers208Aand208Bprior to the dielectric layers208Aand208Bbeing disposed over the substrate core205. In other embodiments, one or both of the conductive layers over dielectric layers208Aand208Bmay be omitted.

Referring now toFIG. 2G, a cross-sectional illustration of the substrate core205after through-hole vias252are formed through the substrate core205and the first plugging layer211is shown, in accordance with an embodiment. In an embodiment, the through-hole vias252may be formed with a mechanical drilling process. Additional embodiments may include forming the through-hole vias252with other processes, such as laser drilling, etching, or the like. In the illustrated embodiment, the through-hole vias252may have substantially vertical sidewalls. However, additional embodiments may include through-hole vias with any profile (e.g., tapered, or the like) depending on the process used to form the through-hole vias252. In an embodiment, the through-hole vias252are also formed through the dielectric layers208Aand208Band the conductive layers261and262. After the formation of the through-hole vias252, embodiments may also include a desmear process.

As illustrated, a through-hole via252may be formed through the first plugging layer211. The through-hole via252may be formed so that a portion of the first plugging layer211remains. This allows for the inner surface217Dof the magnetic sheath215to remain protected from the processing environment by the remaining portions of the first plugging layer211. Accordingly, the magnetic sheath215is not exposed to the through-hole via formation process environment or the desmear environment since it is fully embedded.

Furthermore, through-hole vias252may also be formed in non-inductor regions of the substrate core205as well. For example, the through-hole via on the right inFIG. 2Gmay be in a non-inductor region. It is to be appreciate that both through-hole vias252may be formed with the same sized drill-bit, and therefore, reduces manufacturing complexity.

Referring now toFIG. 2H, a cross-sectional illustration of the substrate core205after the through-hole vias are plated is shown, in accordance with an embodiment. In an embodiment, conductive material may be disposed along the sidewalls of the through-hole vias to form plated through-hole vias212along the first plugging layer211in the inductor region and along a surface of the substrate core205in the non-inductor regions. The conductive material may be disposed on the sidewalls of the through-hole vias212with a plating process, such as an electroless plating process. In an embodiment, the conductive material may be copper or any other conductive material. In such embodiments, magnetic sheath215is not exposed to the electroless plating bath since it is fully embedded by the substrate core205, the first plugging layer211, and the first and second dielectric layers208Aand208B.

Referring now toFIG. 21, a cross-sectional illustration of the substrate core205after a second plugging layer213is disposed into the openings252is shown, in accordance with an embodiment. In an embodiment, the second plugging layer213may be disposed into the openings252with a plugging process, as is known in the art. In an embodiment, the second plugging layer213may be a dielectric material, such as an epoxy or any other suitable material. In an embodiment, the second plugging layer213may be the same material as first plugging layer211. In an additional embodiment, the second plugging layer213may be a different material than the first plugging layer211. In an embodiment, the second plugging layer213may be planarized with a top surface of the through-hole vias using a polishing or grinding process. In some embodiments, the second plugging layer213may be cured with a curing process. In some embodiments, the second plugging layer213may be omitted and the through-hole vias252may be air filled.

Referring now toFIG. 2J, a cross-sectional illustration of the substrate core205after lids219are formed over the plated through-hole vias212is shown, in accordance with an embodiment. In an embodiment, the lids219are conductive lids and may be formed with any deposition process. For example, the lids218may be formed with an electroless plating process. After the plating, a subtractive etching process may be implemented to define the pattern of the lids218and remove the conductive layers261and262. In some embodiments, the subtractive etching process may also be utilized to form conductive traces along surfaces of the dielectric layers208Aand208Bused to connect the plated through-hole vias212to other inductors and circuitry in or on the substrate core205.

Referring now toFIG. 3, a cross-sectional illustration of a packaged system310is shown, in accordance with an embodiment. In an embodiment, the packaged system310may include a die340electrically coupled to a package substrate370with solder bumps343. In additional embodiments, the die340may be electrically coupled to the package substrate340with any suitable interconnect architecture, such as wire bonding or the like. The package substrate340may be electrically coupled to a board, such as a printed circuit board (PCB) with solder bumps373or any other suitable interconnect architecture, such as wire bonding or the like.

In an embodiment, an inductor310similar to embodiments described above may be integrated into the package substrate370or the board380, or the package substrate370and the board380. Embodiments include any number of inductors310formed into the package substrate370and the board380. For example, a plurality of inductors310may be integrated into the circuitry of the package substrate370or the board380, or the package substrate370and the board380for power management, filtering, or any other desired use.

FIG. 4illustrates a computing device400in accordance with one implementation of the invention. The computing device400houses a board402. The board402may include a number of components, including but not limited to a processor404and at least one communication chip406. The processor404is physically and electrically coupled to the board402. In some implementations the at least one communication chip406is also physically and electrically coupled to the board402. In further implementations, the communication chip406is part of the processor404.

The processor404of the computing device400includes an integrated circuit die packaged within the processor404. In some implementations of the invention, the integrated circuit die of the processor may include an inductor with a fully embedded magnetic sheath, in accordance with embodiments described herein. The term “processor” may refer to any device or portion of a device that processes electronic data from registers and/or memory to transform that electronic data into other electronic data that may be stored in registers and/or memory.

The communication chip406also includes an integrated circuit die packaged within the communication chip406. In accordance with another implementation of the invention, the integrated circuit die of the communication chip includes one or more devices that include an inductor with a fully embedded magnetic sheath, in accordance with embodiments described herein.

Example 1 may include an inductor, comprising: a substrate core; a conductive through-hole disposed through the substrate core; and a magnetic sheath around the conductive through hole, wherein the magnetic sheath is separated from the plated through hole by a plugging layer comprising a dielectric material.

Example 2 may include the inductor of Example 1, wherein a first surface of the magnetic sheath is substantially coplanar with a first surface of the substrate core and wherein a second surface of the magnetic sheath is substantially coplanar with a second surface of the substrate core.

Example 3 may include the inductor of Example 1 or Example 2, wherein a first layer comprising a dielectric material is in contact with the first surface of the magnetic sheath, and wherein a second layer comprising a dielectric material is in contact with the second surface of the magnetic sheath.

Example 4 may include the inductor of Examples 1-3, wherein the magnetic sheath is fully embedded.

Example 5 may include the inductor of Examples 1-4, wherein a thickness of the plugging layer separating the magnetic sheath from the conductive through hole is 50 μm or less.

Example 6 may include the inductor of Examples 1-5, wherein a thickness of the magnetic sheath is 50 μm or greater.

Example 7 may include the inductor of Examples 1-6, wherein a diameter of the conductive through via is the same diameter as conductive through vias disposed in non-inductor regions of the substrate core.

Example 4 may include the inductor of Examples 1-7, wherein a permeability of the magnetic sheath is greater than 10.

Example 9 may include the inductor of Examples 1-8, wherein the permeability of the magnetic sheath is greater than 20.

Example 10 may include the inductor of Examples 1-9, further comprising a second plugging layer filling the conductive through-hole, wherein the second plugging layer comprises a dielectric material.

Example 11 may include the inductor of Examples 1-10, wherein the second plugging layer is the same material as the plugging layer separating the magnetic sheath from the conductive through-hole.

Example 12 may include a method of forming an inductor, comprising: forming a first opening through a substrate core; filling the first opening with a magnetic material; forming a second opening through the magnetic material to define a magnetic sheath; disposing a plugging layer comprising a dielectric material into the second opening; disposing a first layer comprising a dielectric material over a first surface of the magnetic sheath; disposing a second layer comprising a dielectric material over a second surface of the magnetic sheath; forming a third opening through the plugging layer, wherein surfaces of the magnetic sheath are separated from the third opening by the plugging layer; and disposing conductive layers over sidewalls of the third opening to form a conductive through via.

Example 13 may include the method of Example 12, wherein a first surface of the magnetic sheath is substantially coplanar with a first surface of the substrate core, and wherein a second surface of the magnetic sheath is substantially coplanar with a second surface of the substrate core.

Example 14 may include the method of Example 12 or Example 13, wherein the magnetic sheath is fully embedded by the substrate core, the plugging layer, the first layer comprising a dielectric material, and the second layer comprising a dielectric material.

Example 15 may include the method of Examples 12-14, wherein one or more of the first opening, the second opening, and the third opening are formed with a mechanical drilling process.

Example 16 may include the method of Examples 12-15, wherein one or more of the first opening, the second opening, and the third opening are formed with a laser drilling process.

Example 17 may include the method of Examples 12-16, wherein a diameter of the third opening is equal to a diameter of a plated through-hole via formed through the substrate core in a non-inductor region.

Example 18 may include the method of Examples 12-17, further comprising: disposing a second plugging layer comprising a dielectric material into the third opening.

Example 19 may include the method of Examples 12-18, wherein the first plugging layer and the second plugging layer comprise the same dielectric material.

Example 20 may include the method of Examples 12-19, wherein the third opening is formed through the first layer comprising a dielectric material and the second layer comprising a dielectric material.

Example 21 may include the method of Examples 12-20, wherein a thickness of the plugging layer separating the magnetic sheath from the conductive through via is 50 μm or less, and wherein a thickness of the magnetic sheath is 50 μm or greater.

Example 22 may include the method of Examples 12-21, wherein a permeability of the magnetic sheath is greater than 20.

Example 23 may include an integrated circuit package comprising: an integrated circuit die; a multi-phase voltage regulator electrically coupled to the integrated circuit die, wherein the multi-phase voltage regulator comprises: a substrate core; a plurality of inductors, wherein the inductors comprise: a conductive through-hole disposed through the substrate core; a plugging layer comprising a dielectric material surrounding the conductive through-hole; a magnetic sheath around the plugging layer, wherein the magnetic sheath is separated from the plated through hole by the plugging layer; a first layer comprising a dielectric material disposed over a first surface of the magnetic sheath; and a second layer comprising a dielectric material disposed over a second surface of the magnetic sheath.

Example 24 may include the integrated circuit package of Example 23, wherein the magnetic sheath is fully embedded by the substrate core, the plugging layer, the first layer comprising a dielectric material, and the second layer comprising a dielectric material.

Example 25 may include the integrated circuit package of Example 23 or Example 24, wherein a permeability of the magnetic sheath is greater than 20.