Patent Application
20250069903
This disclosure relates generally to semiconductor device packaging, and more specifically, to semiconductor devices with embedded leadframe and method of forming the same.
Today, there is an increasing trend to include sophisticated semiconductor devices in products and systems that are used every day. These sophisticated semiconductor devices may include features for specific applications which may impact the configuration of the semiconductor device packages, for example. For some features and applications, the configuration of the semiconductor device packages may be susceptible to lower reliability, lower performance, and higher product or system costs. Accordingly, significant challenges exist in accommodating these features and applications while minimizing the impact on semiconductor devices' reliability, performance, and costs.
The present invention is illustrated by way of example and is not limited by the accompanying figures, in which like references indicate similar elements. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale.
Generally, there is provided, a semiconductor device having an embedded leadframe. The semiconductor device includes a semiconductor die, a redistribution layer substrate formed on the active side of the semiconductor die, and a leadframe attached to the backside of the semiconductor die. The redistribution layer substrate may be formed as a build-up substrate or may be provided as a pre-formed substrate. Conductive connectors such as solder balls are affixed to under-bump metallization structures of the redistribution layer substrate. The conductive connectors are interconnected to the bond pads of the semiconductor die by way of the redistribution layer substrate, for example. The leadframe includes a die pad and a plurality of leads connected to the die pad. The leadframe is pre-formed such that the plurality of leads extend vertically from the die pad and surround the sidewalls of the semiconductor die in a cage-like manner. The semiconductor die and the leadframe are encapsulated with an encapsulant. Each lead of the plurality of lead includes a lead tip region exposed through the bottom side of the encapsulant. Likewise, the bottom side of the redistribution layer substrate including the conductive connectors attached to the under-bump metallization structures are exposed through the bottom side of the encapsulant. The exposed lead tip regions and the conductive connectors are configured for attachment to a printed circuit board, for example. By forming the semiconductor device with the embedded leadframe in this manner, additional package strength and secure mechanical bonding of the semiconductor device is achieved when the exposed lead tip regions of the leadframe are mounted on a printed circuit board, thus improving board level reliability. In addition, the embedded leadframe may be configured to serve as an electromagnetic interference shield and/or a heat spreader allowing greater flexibility.
The semiconductor die 102 has an active side (e.g., major side having circuitry) and a backside (e.g., major side opposite of the active side). The semiconductor die 102 includes bond pads 202 formed at the active side. In this embodiment, semiconductor die 102 is oriented with the active side up having the backside temporarily affixed on the carrier substrate 204. The semiconductor die 102 may be formed from any suitable semiconductor material, such as silicon, germanium, gallium arsenide, gallium nitride, and the like. The semiconductor die 102 further includes any digital circuits, analog circuits, RF circuits, power circuits, memory, processor, the like, and combinations thereof formed at the active side.
In this embodiment, conductive connectors 304 (e.g., solder balls) are affixed to respective UBM structures 306 exposed at the bottom side 308 of the RDL substrate 302. The conductive connectors 304 may be in the form of suitable conductive structures such as solder balls, gold studs, copper pillars, and the like, to connect conductive features of the semiconductor device 100 with the PCB.
The leadframe 502 may be formed from any suitable electrically conductive metal material, such as copper, silver, nickel, aluminum, or iron, or alloys thereof, for example. The conductive metal may be bare, partially plated, or plated with another metal or alloy such thereof. In this embodiment, the die pad 504 and the plurality of leads 506 of the leadframe 502 are formed from a common metal sheet. In some embodiments, the leadframe 502 may include being used for thermal conduction as well as electrical conduction. The number and arrangement of leads 506 of the leadframe 502 are chosen for illustration purposes.
Each lead 506 of the plurality of leads has a proximal end portion directly connected to the die pad 504 and a distal end (e.g., lead tip) portion 508 placed on the carrier substrate 402. In this embodiment, the leads 506 are pre-formed (e.g., bent) to extend vertically downward along sidewalls of the semiconductor die toward a plane in common with the bottom side 308 of the RDL substrate 302. The distal end portion of each lead 506 is configured to form the lead tip portion 508 substantially coplanar with the UBM structures 306 of the RDL substrate 302. In this embodiment, the conductive connectors 304 affixed to the UBM structures 306 and the lead tip portions 508 of the plurality of leads 506 are substantially embedded in the releasable adhesive 404 when the semiconductor device 100 is placed on the carrier substrate 402.
In this embodiment, the leadframe 502 is configured to form a cage-like structure having die pad 504 covering the backside of the semiconductor die 102 and the plurality of leads 506 substantially surrounding the semiconductor die 102 on all four sides. In some embodiments, the cage-like structure of the leadframe 502 surrounding the semiconductor die 102 may be further configured to serve as an EMI shield. In some embodiments, the leadframe 502 may be attached to the backside of the semiconductor die 102 by way of a thermally conductive die attach adhesive 510 and further configured to serve as a heat spreader.
Generally, there is provided, a method including forming a redistribution layer (RDL) substrate over an active side of a semiconductor die, the RDL substrate having a plurality of under-bump metallization (UBM) structures; affixing a die pad of a leadframe on a backside of the semiconductor die, the leadframe including a plurality of leads having a first portion of each lead connected to the die pad and a second portion of each lead extending vertically along sidewalls of the semiconductor die toward a plane of the RDL substrate; and encapsulating with an encapsulant the semiconductor die and the leadframe, a lead tip portion of each lead exposed through the encapsulant. The plurality of leads of the leadframe may be pre-bent such that the plurality of leads substantially surround the sidewalls of the semiconductor die after affixing the die pad on the backside of the semiconductor die. A lead tip portion of each lead the plurality of leads may be substantially coplanar with the UBM structures of the RDL substrate. The plurality of leads and the die pad of the leadframe may be formed from a same contiguous metal. The method may further include affixing a plurality of conductive ball connectors to respective UBM structures. The lead tip regions of the plurality of leads may be configured for connection to a printed circuit board. The leadframe may be configured as electromagnetic interference (EMI) shield. The method may further include grinding a top surface of the encapsulant to expose a backside of the die pad of the leadframe. The exposed die pad of the leadframe may be configured for attachment of a heat sink or heat spreader.
In another embodiment, there is provided, a semiconductor device including a semiconductor die having a plurality of bond pads located at an active side of the semiconductor die; a redistribution layer (RDL) substrate formed over the active side of the semiconductor die, the RDL substrate having a plurality of under-bump metallization (UBM) structures configured for attachment of ball connectors; a die pad of a leadframe affixed on a backside of the semiconductor die, the leadframe including a plurality of leads connected to the die pad and bent such that the leads extend vertically from the die pad toward a plane of the RDL substrate; and an encapsulant encapsulating the semiconductor die and at least a portion of the leadframe, a lead tip portion of each lead of the plurality of leads exposed through the encapsulant. The lead tip portion of each lead of the plurality of leads may be substantially coplanar with the plurality of UBM structures. The plurality of leads of the leadframe may be bent and extend vertically such that the plurality of leads substantially surround the sidewalls of the semiconductor die. The semiconductor device may further include a plurality of conductive ball connectors affixed to respective UBM structures. A backside of the die pad of the leadframe may be exposed through a top surface of the encapsulant. The exposed backside of the die pad of the leadframe may be configured for attachment of a heat sink or heat spreader.
In yet another embodiment, there is provided, a method including forming a redistribution layer (RDL) substrate over an active side of a semiconductor die, the RDL substrate having a plurality of under-bump metallization (UBM) structures; affixing a die pad of a leadframe on a backside of the semiconductor die, the leadframe including a plurality of leads having a first portion of each lead connected to the die pad and a second portion of each lead extending vertically along sidewalls of the semiconductor die to a lead tip portion; and encapsulating with an encapsulant the semiconductor die and the leadframe, the lead tip portion of each lead exposed through the encapsulant. The lead tip portion of each lead exposed through the encapsulant may be substantially coplanar with the plurality of UBM structures of the RDL substrate. The plurality of leads of the leadframe may be pre-bent such that the plurality of leads are distributed around the sidewalls of the semiconductor die after affixing the die pad on the backside of the semiconductor die. The method may further include exposing a backside of the die pad of the leadframe through the encapsulant. The plurality of leads and the die pad of the leadframe may be formed from a same contiguous metal.
By now, it should be appreciated that there has been provided a semiconductor device having an embedded leadframe. The semiconductor device includes a semiconductor die, a redistribution layer substrate formed on the active side of the semiconductor die, and a leadframe attached to the backside of the semiconductor die. The redistribution layer substrate may be formed as a build-up substrate or may be provided as a pre-formed substrate. Conductive connectors such as solder balls are affixed to under-bump metallization structures of the redistribution layer substrate. The conductive connectors are interconnected to the bond pads of the semiconductor die by way of the redistribution layer substrate, for example. The leadframe includes a die pad and a plurality of leads connected to the die pad. The leadframe is pre-formed such that the plurality of leads extend vertically from the die pad and surround the sidewalls of the semiconductor die in a cage-like manner. The semiconductor die and the leadframe are encapsulated with an encapsulant. Each lead of the plurality of lead includes a lead tip region exposed through the bottom side of the encapsulant. Likewise, the bottom side of the redistribution layer substrate including the conductive connectors attached to the under-bump metallization structures are exposed through the bottom side of the encapsulant. The exposed lead tip regions and the conductive connectors are configured for attachment to a printed circuit board, for example. By forming the semiconductor device with the embedded leadframe in this manner, additional package strength and secure mechanical bonding of the semiconductor device is achieved when the exposed lead tip regions of the leadframe are mounted on a printed circuit board, thus improving board level reliability. In addition, the embedded leadframe may be configured to serve as an electromagnetic interference shield and/or a heat spreader allowing greater flexibility.
The terms “front,” “back,” “top,” “bottom,” “over,” “under” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein.
Although the invention is described herein with reference to specific embodiments, various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention. Any benefits, advantages, or solutions to problems that are described herein with regard to specific embodiments are not intended to be construed as a critical, required, or essential feature or element of any or all the claims.
Furthermore, the terms “a” or “an,” as used herein, are defined as one or more than one. Also, the use of introductory phrases such as “at least one” and “one or more” in the claims should not be construed to imply that the introduction of another claim element by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim element to inventions containing only one such element, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an.” The same holds true for the use of definite articles.
Unless stated otherwise, terms such as “first” and “second” are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements.
