# Patent

## Title
Embedded component package and fabrication method

## Abstract

An array includes a substrate having a frontside surface and a backside surface. A backside cavity is formed in the backside surface. Backside through vias extend through the substrate from the frontside surface to the backside surface. Embedded component through vias extend through the substrate from the frontside surface to the backside cavity. An embedded component is mounted within the backside cavity and coupled to the embedded component through vias. In this manner, the embedded component is embedded within the substrate.

## Background
TECHNICAL FIELD
The present application relates to the field of electronics, and more particularly, to methods of forming electronic component packages and related structures.
BACKGROUND
Passive components, e.g., capacitors, resistor, and inductors, are incorporated into electronic component packages. For example, a passive component is mounted to a surface of an interposer of an electronic component package using surface mount technology (SMT). However, the passive component protrudes from the surface of the interposer thus increasing the size of the overall electronic component package.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of an embedded component package fabrication method in accordance with one embodiment;
FIG. 2 is a cross-sectional view of an array including a substrate including a plurality of electronic components in accordance with one embodiment; and
FIGS. 3, 4, 5, 6 are cross-sectional views of the array of FIG. 2 at later stages during fabrication in accordance with various embodiments.



In the following description, the same or similar elements are labeled with the same or similar reference numbers.
DETAILED DESCRIPTION
As an overview and in accordance with one embodiment, referring to FIG. 6, an array 200 includes a substrate 202 having a frontside surface 206 and a backside surface 332. A backside cavity 556 is formed in backside surface 332.
Backside through vias 218 extend through substrate 202 from frontside surface 206 to backside surface 332. Embedded component through vias 220 extend through substrate 202 from frontside surface 206 to backside cavity 556.
An embedded component 668 is mounted within backside cavity 556 and coupled to embedded component through vias 220. In this manner, embedded component 668 is embedded within substrate 202.
By embedding embedded component 668 within substrate 202, the overall thickness of array 200 is minimized. Further, by electrically connecting embedded component 668 to embedded component through vias 220, which are relatively short, the impedance between active surface ends 228 of embedded component through vias 220 and bond pads 674 of embedded component 668 is minimized thus providing superior power management. Further, routing space on frontside surface 206 and/or backside surface 332 is preserved.
Now in more detail, FIG. 1 is a block diagram of an embedded component package fabrication method 100 in accordance with one embodiment. FIG. 2 is a cross-sectional view of an array 200 including a substrate 202 including a plurality of electronic components 204 in accordance with one embodiment.
In one embodiment, substrate 202 is a silicon wafer. Substrate 202 includes a frontside, e.g., first, surface 206 and an opposite backside, e.g., second, surface 208.
Substrate 202 includes electronic components 204 integrally connected to one another. For simplicity, the term substrate 202 shall be used herein and it is to be understood that this term generally includes electronic components 204.
In one embodiment, electronic components 204 are integrated circuit chips, e.g., active components including active circuitry. However, in other embodiments, electronic components 204 are passive components such as capacitors, resistors, or inductors.
In accordance with this embodiment, electronic components 204 include active surfaces 210 and opposite inactive surfaces 212. Active surfaces 210 and inactive surfaces 212 generally define frontside surface 206 and backside surface 208 of substrate 202, respectively. For simplicity, the terms frontside surface 206 and backside surface 208 shall be used herein and it is to be understood that these terms generally include active surfaces 210 and inactive surfaces 212, respectively. Electronic components 204 further includes bond pads 214 on active surfaces 210.
Electronic components 204 are delineated from one another by singulation streets 216. Substrate 202 is singulated, e.g., sawed, along singulation streets 216 to separate packaged electronic components 204 from one another at a later stage during fabrication.
In another embodiment, array 200 includes a plurality of interposers 204 connected together (instead of electronic components 204). More particularly, interposers 204, e.g., silicon interposers, have an absence of active circuitry and thus do not have bond pads 214. The structure of array 200 when formed of interposers 204 is otherwise the same or similar to the structure of array 200 when formed of electronic components as discussed above. Array 200 including electronic components 204 (instead of interposers) shall be discussed below but it is to be understood that the discussion is equally applicable to the embodiment where array 200 is formed of interposers.
Referring now to FIGS. 1 and 2 together, in a form backside through vias and embedded component through vias operation 102, backside through vias 218 and embedded component through vias 220 are formed in electronic components 204. Backside through vias 218 and embedded component through vias 220 are surrounded by dielectric backside through via passivation linings 222 and dielectric embedded component through via passivation linings 224, respectively.
Illustratively, backside through vias 218 are formed first and then embedded component through vias 220 are formed second. In accordance with this embodiment, a first set of through via apertures are formed, e.g., by laser drilling, into electronic components 204 from frontside surface 206. Backside through via passivation linings 222, e.g., silicon oxide (SiO2), are formed on the sidewalls of the first set of through via apertures. In one embodiment, the silicon of substrate 202 exposed within the first set of through via apertures is oxidized to form backside through via passivation linings 222. In another embodiment, a dielectric material is deposited within the first set of through via apertures to form backside through via passivation linings 222.
Backside through vias 218 are formed within backside through via passivation linings 222. Illustratively, an electrically conductive material, e.g., copper or tungsten, is deposited, e.g., plated, within backside through via passivation linings 222 to form backside through vias 218. Backside through via passivation linings 222 electrically isolate backside through vias 218 from substrate 202.
A patterned mask is then applied to cover and protect backside through vias 218 and backside through via passivation linings 222 at frontside surface 206 of substrate 202. Embedded component through vias 220 and embedded component through via passivation linings 224 are then formed.
More particularly, a second set of through via apertures are formed, e.g., by laser drilling, into electronic components 204 from frontside surface 206. Embedded component through via passivation linings 224, e.g., silicon oxide (SiO2), are formed on the sidewalls of the second set of through via apertures in a manner similar to that discussed above regarding the formation of backside through via passivation linings 222.
Embedded component through vias 220 are formed within embedded component through via passivation linings 224 in a manner similar to discussed above regarding the formation of backside through vias 218. Embedded component through via passivation linings 224 electrically isolate embedded component through vias 220 from substrate 202. The patterned mask is then stripped.
Although formation of backside through vias 218 and backside through via passivation linings 222 prior to the formation of embedded component through vias 220 and embedded component through via passivation linings 224 is described above, in other embodiments, embedded component through vias 220 and embedded component through via passivation linings 224 are formed prior to, or simultaneously with, backside through vias 218 and backside through via passivation linings 222.
Backside through vias 218 are longer than embedded component through vias 220 in this embodiment. More particularly, backside through vias 218 have a length L1, e.g., 100 μm, and embedded component through vias 220 have a length L2, e.g., 15 μm, where length L1 is greater than length L2.
Backside through vias 218 and embedded component through vias 220 include active surface ends 226, 228, respectively. Active surface ends 226, 228 are circular in accordance with this embodiment. Active surface ends 226, 228 are coplanar with and parallel to frontside surface 206 of substrate 202.
In one embodiment, a frontside circuit pattern including one or more dielectric layers is formed on frontside surface 206. The frontside circuit pattern is electrically coupled to active surface ends 226, 228 and/or bond pads 214.
From form backside through vias and embedded component through vias operation 102, flow moves to a backgrind backside surface operation 104. In backgrind backside surface operation 104, substrate 202 is thinned, sometimes called backgrinded, to almost expose backside through vias 218 at backside surface 208 of substrate 202. More particularly, backside through vias 218 and embedded component through vias 220 remain enclosed within substrate 202 at backside surface 208 in accordance with this embodiment.
As illustrated, except at frontside surface 206, backside through vias 218 and embedded component through vias 220 are totally enclosed within linings 222, 224. Further, a portion of substrate 202, e.g., silicon, remains between backside through vias 218 and backside surface 208 and also between embedded component through vias 220 and backside surface 208. However, in another embodiment, substrate 202 is thinned to expose backside through vias 218 at backside surface 208 of substrate 202.
FIG. 3 is a cross-sectional view of array 200 of FIG. 2 at a later stage during fabrication in accordance with one embodiment. Referring now to FIGS. 1, 2, and 3 together, from backgrind backside surface operation 104, flow moves to an etch backside surface to expose backside through via nubs operation 106. In etch backside surface to expose backside through via nubs operation 106, backside surface 208 of substrate 202 is etched, i.e., removed, to expose backside through via nubs 330 of backside through vias 218. Etch backside surface to expose backside through via nubs operation 106 is sometimes called a primary reveal operation.
In one embodiment, backside surface 208 is removed using a selective etch that etches substrate 202, e.g., silicon, but does not etch backside through vias 218, e.g., copper. Optionally, the portion of backside through via passivation lining 222 covering backside through via nubs 330 is also removed.
Generally, substrate 202 is thinned from backside surface 208. Stated another way, a portion of substrate 202 at backside surface 208 as illustrated in FIG. 2 is removed to form a recessed backside surface 332 as illustrated in FIG. 3. For example, a Si dry or wet etch is performed to thin substrate 202.
Accordingly, after performance of etch backside surface to expose backside through via nubs operation 106, substrate 202 includes a recessed backside surface 332. Inactive surfaces 212 generally define recessed backside surface 332. For simplicity, the term recessed backside surface 332 shall be used herein and it is to be understood that this term generally includes inactive surfaces 212.
However, backside through vias 218 are not thinned and thus backside through via nubs 330 are exposed as illustrated in FIG. 3. Backside through vias 218 are sometimes said to stand proud of or extend from recessed backside surface 332.
Backside through via nubs 330 are the upper portions of backside through vias 218 exposed and uncovered by substrate 202. Backside through via nubs 330 are cylindrical protrusions protruding upwards from recessed backside surface 332.
Backside through via nubs 330, e.g., first portions of backside through vias 218, include inactive surface ends 334, e.g., planar circular ends or curved ends. Inactive surface ends 334 are spaced above recessed backside surface 332. Generally, backside through vias 218 are electrically conductive columns extending between active surface ends 226 and inactive surface ends 334.
FIG. 4 is a cross-sectional view of array 200 of FIG. 3 at a later stage during fabrication in accordance with one embodiment. Referring now to FIGS. 1 and 4 together, from etch backside surface to expose backside through via nubs operation 106, flow moves, optionally, to an apply backside passivation layer operation 108. In apply backside passivation layer operation 108, a backside passivation layer 446 is applied to recessed backside surface 332.
Backside passivation layer 446 is a dielectric material. In one embodiment, backside passivation layer 446 is formed from an organic material such as polyimide (PI), polybutyloxide (PBO), benzocyclobutene (BCB), a polymer, or other carbon containing material. In one embodiment, backside passivation layer 446 is formed by spinning, or spraying an organic material onto recessed backside surface 332 or applying a laminated film. In other embodiments, backside passivation layer 446 is an inorganic material, e.g., silicon oxide or silicon nitride, formed using a plasma enhanced chemical vapor deposition (PECVD) deposition process.
Backside passivation layer 446 is patterned to expose inactive surface ends 334 of backside through vias 218. In accordance with this embodiment, backside passivation layer 446 is further patterned to expose an embedded component cavity region 448 of recessed backside surface 332.
Embedded component cavity region 448 is the region of recessed backside surface 332 where a backside cavity will be formed as discussed below. Generally, embedded component cavity region 448 is above embedded component through vias 220 such that etching embedded component cavity region 448 will expose embedded component through vias 220 as discussed below. Illustratively, embedded component cavity region 448 is a 1 mm square area.
However, in another embodiment, backside passivation layer 446 covers embedded component cavity region 448.
From apply backside passivation layer operation 108, flow moves, optionally, to an apply interconnection metal to backside through via nubs operation 110. In apply interconnection metal to backside through via nubs operation 110, an interconnection metal 450 is applied to inactive surface ends 334 of backside through vias 218. Interconnection metal 450 is an electrically conductive material, e.g., a gold and/or nickel layer, that enhances bonding with backside through vias 218.
From apply interconnection metal to backside through via nubs operation 110, flow moves, optionally, to an apply mask operation 112. In apply mask operation 112, a patterned mask 452 is applied generally to recessed backside surface 332.
More particularly, patterned mask 452 is applied to and protects backside passivation layer 446 and inactive surface ends 334 including interconnection metal 450 formed thereon. Patterned mask 452 exposes embedded component cavity region 448.
FIG. 5 is a cross-sectional view of array 200 of FIG. 4 at a later stage during fabrication in accordance with one embodiment. Referring now to FIGS. 1, 4, and 5 together, from apply mask operation 112, flow moves to a selectively etch backside surface to expose embedded component through via nubs operation 114. In selectively etch backside surface to expose embedded component through via nubs operation 114, recessed backside surface 332 is selectively etched, i.e., selectively removed, to expose embedded component through via nubs 554. Selectively etch backside surface to expose embedded component through via nubs operation 114 is sometimes called a secondary reveal operation.
More particularly, embedded component cavity region 448 is etched using patterned mask 452 to prevent etching of the remaining area of recessed backside surface 332. In one embodiment, embedded component cavity region 448 is removed using a selective etch that etches substrate 202, e.g., silicon, but does not etch embedded component through vias 220, e.g., copper.
For example, once embedded component through vias 220 are revealed, an additional 5 μm of substrate 202 is removed to expose embedded component through via nubs 554. Optionally, the portion of embedded component through via passivation linings 224 covering embedded component through via nubs 554 is also removed.
By etching embedded component cavity region 448, a backside cavity 556 is formed in recessed backside surface 332. Backside cavity 556 is defined by a backside cavity base 558 and backside cavity sidewalls 560.
Backside cavity base 558 is parallel to frontside surface 206 and recessed backside surface 332 and located therebetween. Backside cavity sidewalls 560 extend perpendicularly between backside cavity base 558 and recessed backside surface 332. Although various features herein may be described as parallel, perpendicular, and having other orientations, in light of this disclosure, those of skill in the art will understand that the features may not be exactly parallel or perpendicular, but only substantially parallel and perpendicular to within accepted manufacturing tolerances.
Embedded component through vias 220 are not thinned and thus embedded component through via nubs 554 are exposed from backside cavity base 558 as illustrated in FIG. 5. Embedded component through vias 220 are sometimes said to stand proud of or extend from backside cavity base 558.
Embedded component through via nubs 554 are the upper portions of embedded component through vias 220 exposed and uncovered by substrate 202. Embedded component through via nubs 554 are cylindrical protrusions protruding upwards from backside cavity base 558 and into backside cavity 556.
Embedded component through via nubs 554, e.g., first portions of embedded component through vias 220, include inactive surface ends 562, e.g., planar circular ends or curved ends. Inactive surface ends 562 are spaced above backside cavity base 558. Generally, embedded component through vias 220 are electrically conductive columns extending between active surface ends 228 and inactive surface ends 562.
From selectively etch backside surface to expose embedded component through via nubs operation 114, flow moves, optionally, to an apply backside cavity passivation layer operation 116. In apply backside cavity passivation layer operation 116, a backside cavity passivation layer 564 is applied to backside cavity base 558. Optionally, backside cavity passivation layer 564 is also applied to backside cavity sidewalls 560.
Backside cavity passivation layer 564 is a dielectric material similar to backside passivation layer 446 as described above, and is applied in a similar manner. Backside cavity passivation layer 564 is patterned to expose inactive surface ends 562 of embedded component through vias 220.
From apply backside cavity passivation layer operation 116, flow moves, optionally, to an apply interconnection metal to embedded component through via nubs operation 118. In apply interconnection metal to embedded component through via nubs operation 120, an interconnection metal 566 is applied to inactive surface ends 562 of embedded component through vias 220. Interconnection metal 566 is an electrically conductive material, e.g., a gold and/or nickel layer, that enhances bonding with embedded component through vias 220.
From apply interconnection metal to embedded component through via nubs operation 120, flow moves, optionally, to a strip mask operation 120. In strip mask operation 120, patterned mask 452 is stripped, i.e., removed, resulting in array 200 as illustrated in FIG. 5.
FIG. 6 is a cross-sectional view of array 200 of FIG. 5 at a later stage during fabrication in accordance with one embodiment. Referring now to FIGS. 1 and 6 together, from strip mask operation 120, flow moved to a mount embedded component to embedded component through via nubs operation 122. In mount embedded component to embedded component through via nubs operation 122, an embedded component 668 is mounted, e.g., physically and electrically connected, to embedded component through via nubs 554. Embedded component 668 is an electronic component, e.g., is an off the shelf passive component such as a capacitor, resistor, or inductor. In another embodiment, embedded component 668 is an integrated circuit chip, e.g., an active component including active circuitry.
In accordance with this embodiment, embedded component 668 includes an active surface 670, an opposite inactive surface 672, and sides 673 extending therebetween. Active surface 670 further includes bond pads 674 thereon. Bond pads 674 are sometimes called terminals.
Bond pads 674 are physically and electrically connected to inactive surface ends 562, e.g., interconnection metal 566 thereon, by bumps 676, e.g., flip chip solder bumps or SMT joints.
As illustrated in FIG. 6, embedded component 668 is mounted within backside cavity 556. Accordingly, embedded component 556 is embedded within substrate 202. In one embodiment, inactive surface 672 is recessed below recessed backside surface 332 such that embedded component 668 is located entirely within backside cavity 556.
By embedding embedded component 668 within substrate 202, the overall thickness of array 200 is minimized. Further, by electrically connecting embedded component 668 to embedded component through vias 220, which are relatively short, the impedance between active surface ends 228 and bond pads 674 is minimized thus providing superior power management. Further, routing space on frontside surface 206 and/or recessed backside surface 332 is preserved.
From mount embedded component to embedded component through via nubs operation 122, flow moves, optionally, to an encapsulate operation 124. In encapsulate operation 124, embedded component 668 is encapsulated in a dielectric package body 678. Package body 678 fills the space between active surface 670 and backside cavity base 558 and enclosed bumps 676. In one embodiment, package body 678 is an underfill such that some or all of sides 673 of embedded component 668 are exposed.
In another embodiment such as the one illustrated, package body 678, e.g., a glob top encapsulant, completely encloses embedded component 668 including sides 673 and inactive surface 672 and fills backside cavity 556.
In another embodiment, as indicated by the dashed line 680, embedded component 668 protrudes out of backside cavity 556 to a height above recessed backside surface 332.
Array 200 is singulated along singulation streets 216 resulting in a plurality of embedded component packages or embedded component interposers depending upon the embodiment.
In other embodiments, one or more of operations 108, 110, 112, 116, 118, 120, 124 are not performed and so operations 108, 110, 112, 116, 118, 120, 124 are optional.
Although specific embodiments were described herein, the scope of the invention is not limited to those specific embodiments. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of the invention is at least as broad as given by the following claims.

## Claims

1. A structure comprising:
a substrate comprising:
an integrated circuit (IC) chip;
an active frontside surface;
an inactive backside surface, wherein the IC chip comprises a bond pad directly on the frontside surface;
a backside through via extending into the substrate from the frontside surface, the backside through via having a first length;
a backside cavity comprising a backside cavity base and backside cavity sidewalls; and
an embedded component through via extending into the substrate from the frontside surface, the embedded component through via having a second length less than the first length;

a backside passivation layer formed on the backside surface of the substrate; and
a backside cavity passivation layer formed on the backside cavity base,
wherein the backside passivation layer and the backside cavity passivation layer are separated from each other by a passivation layer gap.

2. The structure of claim 1, comprising
a backside through via nub protruding from the backside passivation layer, where the backside through via nub comprises an end portion of a continuous metal column filling the backside through via.

3. The structure of claim 1, wherein:
the backside cavity base is parallel to the active frontside surface; and
the backside cavity sidewalls are perpendicular to the active frontside surface.

4. The structure of claim 2, comprising
an embedded component through via nub protruding from the backside cavity passivation layer, where the embedded component through via nub comprises an end portion of a continuous metal column filling the embedded component through via.

5. The structure of claim 1, comprising a backside cavity side passivation layer formed on at least a portion of the backside cavity sidewalls.

6. A structure comprising:
a substrate comprising:
an integrated circuit (IC) chip;
an active frontside surface;
an inactive backside surface, wherein the IC chip comprises a bond pad directly on the frontside surface;
a backside cavity in the backside surface, the backside cavity comprising a backside cavity base and backside cavity sidewalls;
a backside through via extending through the substrate from the frontside surface to the backside surface; and
an embedded component through via extending through the substrate from the frontside surface to the backside cavity;

an encapsulant filling at least a portion of the backside cavity;
a backside passivation layer formed on the backside surface of the substrate; and
a backside cavity passivation layer formed on the backside cavity base,
wherein the backside passivation layer and the backside cavity passivation layer are separated from each other by at least a passivation layer gap.

7. A method comprising:
forming a backside through via in a substrate that comprises an integrated circuit (IC) chip;
forming an embedded component through via in the substrate;
exposing the backside through via at a backside surface of the substrate by, at least in part, grinding the substrate; and
etching a backside cavity in the backside surface to expose an embedded component through via nub of the embedded component through via, the embedded component through via nub protruding into the backside cavity, wherein said etching a backside cavity comprises:
forming a backside passivation layer on the backside surface of the substrate;
applying a patterned mask to the backside passivation layer, the patterned mask exposing an embedded component cavity region of the backside surface above the embedded component through via;
etching the embedded component cavity region to expose the embedded component through via nub; and
forming a backside cavity passivation layer on a base of the backside cavity, from which the embedded component through via nub protrudes.

8. The method of claim 7, wherein said exposing the backside through via comprises exposing
a backside through via nub, where the backside through via nub comprises an end portion of a continuous metal column filling the backside through via.

9. The method of claim 7
wherein the embedded component through via nub comprises an end portion of a continuous metal column filling the embedded component through via.

10. The structure of claim 7, comprising forming a backside cavity side passivation layer formed on at least a portion of the backside cavity sidewalls.

11. The method of claim 7, wherein said exposing the backside through via comprises exposing an axial end conductive surface and a radial side conductive surface of material filling the backside through via from the backside surface of the substrate and from a passivation lining of the backside through via.

12. The method of claim 7, further comprising:
coupling an embedded component located within the backside cavity to the embedded component through via, wherein the embedded component comprises passive electronic component comprising a first surface facing a base of the backside cavity, a second surface opposite the first surface, and a plurality of side surfaces connecting the first surface and the second surface; and
encapsulating the embedded component in an encapsulant, such that at least a portion of at least one of the plurality of side surfaces is exposed from the encapsulant.

13. The method of claim 7, wherein:
the backside cavity base is parallel to the active frontside surface; and
the backside cavity sidewalls are perpendicular to the active frontside surface.

14. The method of claim 7 wherein the backside through via is at least six times longer than the embedded component through via.

15. The method of claim 7, wherein said forming a backside passivation layer and said forming a backside cavity passivation layer are performed in a same manner.

16. The method of claim 7 further comprising coupling an embedded component to the embedded component through via and within the backside cavity.

17. The method of claim 16 wherein the embedded component extends from a base of the backside cavity to outside of the backside cavity.

18. The method of claim 7, wherein the exposing the backside through via at the backside surface of the substrate comprises exposing an axial end conductive surface and a radial side conductive surface of the backside through via from the backside surface of the substrate.

19. The method of claim 7, comprising:
coupling an embedded component positioned within the backside cavity to the embedded component through via, and
filling at least a portion of the backside cavity with an encapsulant,
wherein:
the embedded component comprises a semiconductor die comprising a first surface facing a base of the backside cavity, a second surface opposite the first surface, and a plurality of side surfaces connecting the first surface and the second surface; and
at least a portion of at least one of the plurality of side surfaces is exposed through the encapsulant.

20. The method of claim 7, comprising:
coupling an embedded component positioned within the backside cavity to the embedded component through via, and
substantially filling the backside cavity with an encapsulant such that the embedded component is completely covered with the encapsulant, and the encapsulant extends from the backside cavity beyond a backside passivation layer on the backside surface of the substrate.