The instant application relates to semiconductor packages, and more particularly to contacting the backside of semiconductor chips embedded in packages.
Embedded-chip packaging is a semiconductor chip (die) packaging technology where materials are added to a printed circuit structure to create optional passive elements such as resistors and capacitors, and active chips (dies) are placed on an internal layer and then buried as additional layers are added. For example some embedded-chip processes include die placement with non-conductive paste attach to a pre-patterned Cu foil, lamination of standard glass reinforced, prepreg (pre-impregnated composite fibers where a matrix material, such as epoxy, is already present) for dimensional stability, and Cu foil patterning to realize PCB (printed circuit board) routing layers. Typical laminate structures can be two to six layers with more complex structures being up to ten metal layers. Standard packaging processes such as wire or clip bonding, as well as common molding techniques, are typically replaced with galvanic processes. The results are a significantly reduced package footprint, package resistance and inductance, as well as low thermal resistance. However, it would be desirable to optimize embedded-chip packaging technologies for multi-chip assemblies so that the embedded-chip packaging technologies are adapted and expanded to meet the needs of different chip technologies e.g. such as high power contacts for power semiconductor dies and dies of different thickness embedded in the same package.
According to an embodiment of a semiconductor package, the package comprises a semiconductor die embedded in an insulating material. The die has a first surface facing in a first direction, a second surface facing in a second direction opposite the first direction and an edge extending between the first and second surfaces. The semiconductor package further comprises a metal clip embedded in the insulating material above the die and bonded to the second surface of the die. Part of the metal clip extends laterally beyond the edge of the die and vertically in the first direction to provide galvanic redistribution at the second surface of the die.
According to another embodiment of a semiconductor package, the package comprises a semiconductor die embedded in an insulating material. The die has opposing first and second surfaces and an edge extending between the first and second surfaces. The package further comprises a structured metal redistribution layer disposed in the insulating material below the die, first conductive vias connecting the structured metal redistribution layer to terminals at the first surface of the die, and a first metal component embedded in the insulating material above the die and bonded to the second surface of the die. Part of the first metal component extends laterally beyond the edge of the die. The package also includes second conductive vias extending vertically from the structured metal redistribution layer toward the first metal component and terminating prior to the first metal component so that a gap exists between the second conductive vias and the part of the first metal component extending laterally beyond the edge of the die. The package further comprises a second metal component disposed in the gap and connecting the second conductive vias to the part of the first metal component extending laterally beyond the edge of the die.
According to yet another embodiment of a semiconductor package, the package comprises a semiconductor die embedded in an insulating material. The die has opposing first and second surfaces and an edge extending between the first and second surfaces. The package further comprises a first metal component embedded in the insulating material above the die and bonded to the second surface of the die. Part of the first metal component extends laterally beyond the edge of the die. The package also comprises a second metal component disposed under and connected to the part of the first metal component that extends laterally beyond the edge of the die. The second metal component vertically extends through the insulating material so that part of the second metal component is uncovered by the insulating material at a side of the package facing away from the second surface of the die. The first and second metal components form at least a thermal pathway from the second surface of the die to the side of the package facing away from the second surface of the die.
Those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings.
The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts. The features of the various illustrated embodiments can be combined unless they exclude each other. Embodiments are depicted in the drawings and are detailed in the description which follows.
According to an embodiment described herein, an embedded-chip package is provided that includes additional rewiring and/or contact elements in the form of a metal clip for contacting the backside of an embedded semiconductor die. According to additional embodiments described herein, embedded-chip packages are provided with backside rewiring and/or contact elements for thick semiconductor dies or semiconductor dies of different thicknesses embedded in the same package.
The package 100 further comprises a structured metal redistribution layer (RDL) 112 disposed in the insulating material 104 below the first die 102. The structured metal redistribution layer 112 is defined by the addition of metal and dielectric layers 114, 116 onto the surface of a wafer or carrier to re-route the I/O (input/output) layout into a new, looser pitch footprint. Such redistribution utilizes thin film polymers 116 such as BCB, (benzocyclobutene), polyimide, Asahi Glass ALX, etc. and metallization 114 such Al or Cu to reroute the peripheral pads to an area array configuration. The redistribution trace can be fabricated directly on a primary passivation such as SiN or SiON, or can be routed over a second layer of polymer to add additional compliancy. One or more additional metal (and corresponding dielectric layers) can be connected to the structured metal redistribution layer 112 to facilitate connection to a board or other component. Such material layers are not shown in
The package 100 also comprises first conductive vias 118 that connect the structured metal redistribution layer 112 to terminals at the first surface 106 of the first die 102. These terminals are not shown in
A metal clip (also commonly referred to as a metal strap in the semiconductor packaging arts) 120 is embedded in the insulating material 104 above the first die 102 and bonded to the second surface (e.g. backside) 108 of the first die 102. The metal clip 120 can be bonded to the second surface 108 of the first die 102 by an adhesive in case the second surface 108 of the first die 102 is not electrically active i.e. all terminals are disposed at the first surface (e.g. front side) of the first die 102. Such an adhesive connection provides a thermal partway from the second surface 108 of the first die 102 to the structured metal redistribution layer 112. In the case of an electrically active backside i.e. one or more terminals disposed at the second surface of the first die 102, the metal clip 120 can be bonded to one or more of the terminals at the second surface 108 of the first 102 die by solder or other electrically conductive joining material, by advanced diffusion soldering, etc. Terminals are not shown at the second surface 108 of the first die 102 for ease of illustration. In each case, the metal clip 120 can be bonded to the second surface 108 of the first die 102 prior to embedding of the die 102 in the insulating material 104.
In general, part 122 of the metal clip 120 extends laterally beyond the edge 110 of the first die 102 and vertically in the first direction X toward the structured metal redistribution layer 112 to provide galvanic redistribution at the second surface 108 of the first die 102. The metal clip 120 can be realized by any standard clip forming process such as stamping, drawing, cutting, etching, etc. The metal clip 120 can at least partially replace standard wire-bond connections between the second surface 108 of the first die 102 and the structured metal redistribution layer 112 by a solid copper bridge, which can be soldered e.g. by solder paste. Such an embedded-chip package construction with embedded clip backside connection significantly increases the current (in the case of an electrically active backside of the die) and/or heat carrying capacity of the package 100.
The package 100 further comprises second conductive vias 124 connecting the structured metal redistribution layer 112 to the part 122 of the metal clip 120 that extends laterally beyond the edge 110 of the first die 102 and vertically toward the structured metal redistribution layer 112. The second conductive vias 124, like the first conductive vias 118, can be formed as part of any standard RDL process. The dimensions of the vias 118, 124 formed in the structured metal redistribution layer 112, including height, are limited by the particular RDL process being used. For thick dies, this means that the vias 118, 124 cannot extend vertically to the same level (L2) in the package 100 as the second surface (e.g. backside) 108 of the first die 102. As such, part 122 of the metal clip 120 extends laterally beyond the edge 110 of the first die 102 and vertically toward the structured metal redistribution layer 112 to enable contact with the second vias 124. In one embodiment, the part 122 of the metal clip 120 that extends laterally beyond the edge 110 of the die 102 and vertically in the first direction X toward the structured metal redistribution layer 112 has a surface 126 facing the structured metal redistribution layer 112 and which terminates at the same level (L1) within the insulating material 104 as the first surface 106 of the first die 102.
The package 100 can include more than one semiconductor die. For example, the semiconductor package 100 can further comprise a second semiconductor die 128 embedded in the insulating material 104 and spaced apart from the first die 102. The second die 128, like the first die 102, has a first surface 130 facing in the first direction X, a second surface 132 facing in the second (opposite) direction Y and an edge 134 extending between the first and second surfaces 130, 132. Third conductive vias 136 connect the structured metal redistribution layer 112 to terminals at the first surface 130 of the second die 128 to form a circuit connection between the dies 102, 128. For example, the dies 102, 128 can be high-side and low-side transistors, respectively, of a half-bridge circuit. Although not shown for ease of illustration, the package 100 can include a driver die for driving the gates (inputs) of the high-side and low-side transistors. Alternatively, the driver die can be omitted and instead provided in a separate package.
The part 122 of the metal clip 120 that extends laterally beyond the edge 110 of the first die 102 and vertically toward the structured metal redistribution layer 112 can be interposed between the first and second dies 102, 128 as shown in the multi-chip embedded package 100 of
In addition to the metal clip connections, some of the other connections in the package 100 optionally can be provided by wire bonds which are not shown for ease of illustration. The metal clip 120 and the first semiconductor die 102 can be provided as a pre-fabricated chip-clip type module with the metal clip 120 pre-bonded to the first die 102 prior to the chip-embedding process. The chip-embedded package 100 can have different redistribution wiring thicknesses, clip thicknesses and/or materials. For example, the redistribution wiring thickness can range from 1 μm to 1000 μm and the redistribution wiring and clip material can include Cu, Fe, Ni, Al, Au, Ag, Pt, Pd and their alloys. In one embodiment, the structured metal redistribution layer 112, the first conductive vias 118, the metal clip 120, the second conductive vias 124 and the third conductive vias 136 each comprise copper or a copper alloy.
A first metal component 216 is embedded in the insulating material 204 above the first die 202 and bonded to the second surface 208 of the first die 202. The first metal component 216 is a metal lead frame according to this embodiment e.g. a Cu lead frame. Part 218 of the metal lead frame 216 extends laterally beyond the edge 210 of the first die 202 so that the lead frame 216 overhangs the first die 202.
The package 200 further comprises second conductive vias 220 extending vertically from the structured metal redistribution layer 212 toward the lead frame 216 and terminating prior to the lead frame 216 so that a gap exists between the second conductive vias 220 and the part 218 of the lead frame 216 extending laterally beyond the edge 210 of the first die 202.
The package 200 also includes a second metal component 222 disposed in the gap between the second conductive vias 220 and the part 218 of the first metal component 216 extending laterally beyond the edge 210 of the first die 202. The second metal component 222 connects the second conductive vias 220 to the part 218 of the first metal component 216 extending laterally beyond the edge 210 of the first die 202. The additional metal volume provided by the second metal component 222 provides significantly higher heat transition than other embedding materials such as epoxy mold compounds or laminates, enabling a double-sided cooling package with high conductive metal volume which can also support electrical functionality in the case of one or more terminals at the second surface (e.g. backside) 208 of the first die 202. For example the first metal component 216 can be electrically connected to a terminal at the second surface 208 of the first die 202, and the second metal component 222 and the second conductive vias 220 can collectively provide both a thermal pathway and an electrical pathway between the structured metal redistribution layer 212 and the first metal component 216.
Using the second metal component 222 to accommodate at least most of the height (H1) of the first die 202 also allows for the use of standard RDL technologies which have small via processes for the first redistribution layer 212. For example, standard RDL technologies typically allow for vias with a height of less than about 71 μm for the first redistribution layer. As such, relatively thick dies (>71 μm) can get assembled with this approach. Furthermore, increased heat dissipation is provided from the second surface 208 of the first die 202 into a board (not shown for ease of illustration) through the second metal component 222, the first redistribution layer 212 and a redistribution layer 224 on the board without an intermediary epoxy insulation layer in the direct heat path. The second metal component 222 also provides a high conductive metal volume as a substitute for low conductive laminate materials, and also accommodates different die and different lead frame thicknesses within the same package 200.
According to the embodiment of
Further according to the embodiment of
In each case, the second die 228, like the first die 202, has opposing first and second surfaces 230, 232 and an edge 234 extending between the first and second surfaces 230, 232. Third conductive vias 236 connect the structured metal redistribution layer 212 to terminals (not shown for ease of illustration) at the first surface 230 of the second die 228. For example, the dies 202, 228 can be high-side and low-side transistors of a half-bridge circuit as previously described herein. Although not shown for ease of illustration, the package 200 can also include a driver die for driving the gates (inputs) of the high-side and low-side transistors. Alternatively, the driver die can be omitted and instead provided in a separate package.
Also according to the embodiment shown in
Spatially relative terms such as “under”, “below”, “lower”, “over”, “upper” and the like, are used for ease of description to explain the positioning of one element relative to a second element. These terms are intended to encompass different orientations of the device in addition to different orientations than those depicted in the figures. Further, terms such as “first”, “second”, and the like, are also used to describe various elements, regions, sections, etc. and are also not intended to be limiting. Like terms refer to like elements throughout the description.
As used herein, the terms “having”, “containing”, “including”, “comprising” and the like are open-ended terms that indicate the presence of stated elements or features, but do not preclude additional elements or features. The articles “a”, “an” and “the” are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.
With the above range of variations and applications in mind, it should be understood that the present invention is not limited by the foregoing description, nor is it limited by the accompanying drawings. Instead, the present invention is limited only by the following claims and their legal equivalents.
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