The present disclosure is directed to transistor devices, and more particularly, to structures for transistor device packaging.
Power amplifiers are used in a variety of applications such as base stations for wireless communication systems, multi-stage and multiple-path amplifiers (e.g., Doherty amplifiers), etc. The signals amplified by the RF power amplifiers often include signals that have a modulated carrier having frequencies in the megahertz (MHz) to gigahertz (GHz) range. For example, Electrical circuits requiring high power handling capability while operating at high frequencies, such as R-band (0.5-1 GHz), S-band (3 GHz), X-band (10 GHz), Ku-band (12-18 GHz), K-band (18-27 GHz), Ka-band (27-40 GHz) and V-band (40-75 GHz) have become more prevalent. In particular, there is now a high demand for radio frequency (“RF”) transistor amplifiers that are used to amplify RF signals at frequencies of, for example, 500 MHz and higher (including microwave frequencies).
Many power amplifier designs utilize semiconductor switching devices as amplification devices. Examples of these switching devices include power transistor devices, such as MOSFETs (metal-oxide semiconductor field-effect transistors), DMOS (double-diffused metal-oxide semiconductor) transistors, HEMTs (high electron mobility transistors), MESFETs (metal-semiconductor field-effect transistors), LDMOS (laterally-diffused metal-oxide semiconductor) transistors, etc. A power amplifier may also include passive matching networks at the input and output nodes of the active power transistor devices.
The transistor devices are typically formed as semiconductor integrated circuit chips. Transistor devices may be implemented, for example, in silicon or using wide bandgap semiconductor materials (i.e., having a band-gap greater than 1.40 eV), such as silicon carbide (“SiC”) and Group III nitride materials. As used herein, the term “Group III nitride” refers to those semiconducting compounds formed between nitrogen and the elements in Group III of the periodic table, usually aluminum (Al), gallium (Ga), and/or indium (In). The term also refers to ternary and quaternary compounds, such as AlGaN and AlInGaN. These compounds have empirical formulas in which one mole of nitrogen is combined with a total of one mole of the Group III elements.
Silicon-based RF transistor amplifiers may typically be implemented using LDMOS transistors, and can exhibit high levels of linearity with relatively inexpensive fabrication. Group III nitride-based RF amplifiers may typically be implemented using HEMTs, primarily in applications requiring high power and/or high frequency operation where LDMOS transistor amplifiers may have inherent performance limitations.
RF transistor amplifiers may include one or more amplification stages, with each stage typically implemented as a transistor amplifier. In order to increase the output power and current handling capabilities, RF transistor amplifiers are typically implemented in a “unit cell” configuration in which a large number of individual “unit cell” transistors are electrically connected (e.g., in parallel). An RF transistor amplifier may be implemented as a single integrated circuit chip or “die,” or may include a plurality of dies. A die or chip may include a small block of semiconducting material or other substrate in which electronic circuit elements are fabricated. For example, a plurality of individual power transistor devices may be formed on a relatively large semiconductor substrate (e.g., by growing epitaxial layers there on doping selected regions with dopants, forming insulation and metal layers thereon, etc.) and the completed structure may then be cut (e.g., by a sawing or dicing operation) into a plurality of individual die. When multiple RF transistor amplifier dies are used, they may be connected in series and/or in parallel.
RF transistor amplifiers often include matching circuits, such as impedance matching circuits, that are designed to improve the impedance match between the active transistor die (e.g., including MOSFETs, HEMTs, LDMOS, etc.) and transmission lines connected thereto for RF signals at the fundamental operating frequency, and harmonic termination circuits that are designed to at least partly terminate harmonic products that may be generated during device operation such as second and third order harmonic products. The termination of the harmonic products also influences generation of intermodulation distortion products.
The RF amplifier transistor die(s) as well as the impedance matching and harmonic termination circuits may be enclosed in a device package. Integrated circuit packaging may refer to encapsulating one or more dies in a supporting case or package (e.g., overmold or open-cavity packages) that protects the dies from physical damage and/or corrosion, and supports the electrical contacts for connection to external circuits. The input and output impedance matching circuits in an integrated circuit device package typically include LC networks that provide at least a portion of an impedance matching circuit that is configured to match the impedance of the active transistor die to a fixed value. Electrical leads may extend from the package to electrically connect the RF amplifier to external circuit elements such as input and output RF transmission lines and bias voltage sources.
Some conventional methods for assembling RF power devices may involve assembling the transistor die and some of the matching network components in a ceramic or over-molded package on a CPC (copper, copper-molybdenum, copper laminate structure) or copper flange. The transistor die, capacitors, and input/output leads may be interconnected with wires, such as gold and/or aluminum wires. Such an assembly process may be slow and sequential (e.g., one package bonded at a time), and assembly costs may be high (e.g., due to cost of gold wires and expensive wire-bond machines).
According to some embodiments, a transistor device package includes a transistor die comprising a gate terminal, a drain terminal, and a source terminal, a passive component assembly including the transistor die on a surface thereof and comprising one or more passive electrical components electrically coupled to the gate terminal, the drain terminal, and/or the source terminal, and a thermally conductive support structure on the surface of the passive component assembly and extending along one or more sides of the transistor die.
In some embodiments, the thermally conductive support structure provides a cavity that extends around the transistor die.
In some embodiments, a first surface of the transistor die is on the surface of the passive component assembly, and a substrate is on a second surface of the transistor die opposite the first surface. The thermally conductive support structure extends between the substrate and the passive component assembly.
In some embodiments, the substrate comprises a thermally conductive material. The thermally conductive structure provides a first heat conduction path, and the second surface of the transistor die provides a second heat conduction path.
In some embodiments, the surface of the passive component assembly including the transistor die thereon is a second surface, the one or more passive electrical components are on a first surface of the passive component assembly opposite the second surface, and the passive component assembly comprises conductive traces and/or vias that electrically couple the one or more passive electrical components on the first surface thereof to the gate terminal, the drain terminal, and/or the source terminal of the transistor die on the second surface thereof.
In some embodiments, the passive component assembly further comprises a mold structure on the one or more passive electrical components on the first surface thereof, and one or more conductive pads that are exposed by the mold structure.
In some embodiments, the second surface of the passive component assembly is free of the mold structure.
In some embodiments, the passive component assembly further comprises first and second package leads on the first or second surface, and the one or more passive electrical components are electrically coupled between the gate terminal and the first package lead or between the drain terminal and the second package lead.
In some embodiments, the thermally conductive support structure comprises an electrically insulating material.
In some embodiments, the thermally conductive support structure comprises copper, aluminum, and/or silicon carbide.
In some embodiments, the one or more passive electrical components comprise a surface mount device and/or an integrated passive device.
In some embodiments, the gate terminal, the drain terminal, and the source terminal comprise conductive pillar structures adjacent the surface of the passive component assembly and electrically coupled to the one or more passive electrical components by conductive bumps.
In some embodiments, the surface of the passive component assembly comprises an integral support structure that provides a cavity extending around the transistor die, and the thermally conductive support structure is within the integral support structure.
According to some embodiments, a transistor device package includes a transistor die comprising a gate terminal, a drain terminal, and a source terminal, and a passive component assembly comprising one or more passive electrical components electrically coupled to the gate terminal, the drain terminal, and/or the source terminal. The transistor die is on a surface of the passive component assembly, and the surface of the passive component assembly comprises a support structure that provides a cavity extending around the transistor die.
In some embodiments, the support structure comprises an electrically insulating material.
In some embodiments, the support structure comprises an integral portion of the passive component assembly that protrudes from the surface.
In some embodiments, a first surface of the transistor die is on the surface of the passive component assembly, and a substrate is on a second surface of the transistor die opposite the first surface. The support structure extends between the substrate and the passive component assembly.
In some embodiments, the substrate comprises a thermally conductive material, the support structure includes a thermally conductive structure extending therein that provides a first heat conduction path, and the second surface of the transistor die provides a second heat conduction path.
In some embodiments, the surface of the passive component assembly including the transistor die thereon is a second surface, and the one or more passive electrical components are on a first surface of the passive component assembly opposite the second surface.
In some embodiments, the passive component assembly further comprises a mold structure on the one or more passive electrical components on the first surface thereof, and one or more conductive pads that are exposed by the mold structure.
In some embodiments, the second surface of the passive component assembly is free of the mold structure and comprises first and second package leads thereon.
According to some embodiments, a transistor device package includes an active component assembly comprising a transistor die having a gate terminal, a drain terminal, and a source terminal, a passive component assembly including the active component assembly on a surface thereof and comprising one or more passive electrical components electrically coupled to the gate terminal, the drain terminal, and/or the source terminal, a mold structure on the one or more passive electrical components, and a frame structure providing a cavity that extends around the transistor die.
In some embodiments, a first surface of the transistor die is on the surface of the passive component assembly, and a substrate is on a second surface of the transistor die opposite the first surface. The frame structure extends between the substrate and the passive component assembly.
In some embodiments, the cavity is an air cavity defined by the frame structure and the substrate.
In some embodiments, the cavity is filled with an encapsulant that extends around the transistor die.
In some embodiments, the frame structure and the substrate respectively comprise a thermally conductive material, the frame conductive structure provides a first heat conduction path, and the second surface of the transistor die provides a second heat conduction path.
In some embodiments, the frame structure and the substrate comprise a unitary structure.
In some embodiments, the surface of the passive component assembly including the transistor die thereon is a second surface, and the one or more passive electrical components are on a first surface of the passive component assembly opposite the second surface.
In some embodiments, the passive component assembly comprises one or more conductive pads are exposed by the mold structure.
In some embodiments, the second surface of the passive component assembly is free of the mold structure and comprises first and second package leads thereon.
According to some embodiments, a passive component assembly includes one or more passive electrical components on a surface of an interconnect structure, where the interconnect structure is configured to electrically couple the one or more passive electrical components to a gate terminal, drain terminal, and/or source terminal of a transistor die. A mold structure is on the one or more passive electrical components on the surface of the interconnect structure, and one or more conductive pads are electrically coupled to the one or more passive electrical components and are exposed by the mold structure.
In some embodiments, the surface of the interconnect structure comprising the one or more passive electrical components and the mold structure thereon is a first surface, and the interconnect structure comprises a second surface opposite the first surface that is configured to accept the transistor die.
In some embodiments, the second surface of the passive component assembly comprises the one or more conductive pads thereon.
In some embodiments, the second surface is free of the mold structure.
In some embodiments, the one or more conductive pads are arranged in a ground-signal-ground layout.
In some embodiments, the one or more passive electrical components are configured to be electrically tested via the one or more conductive pads prior to electrically connecting the transistor die to the passive component assembly.
In some embodiments, the one or more passive electrical components comprise a surface mount device and/or an integrated passive device.
In some embodiments, the second surface of the interconnect structure is configured to electrically couple the one or more passive electrical components to the gate terminal, drain terminal, and/or source terminal of the transistor die by conductive bumps.
In some embodiments, the second surface of the interconnect structure comprises a support structure that provides a cavity configured to accept the transistor die.
In some embodiments, the support structure comprises an electrically insulating material.
In some embodiments, the support structure comprises an integral portion of the interconnect structure that protrudes from the second surface.
In some embodiments, the support structure comprises a thermally conductive material.
In some embodiments, the transistor die is a Group III nitride-based RF transistor amplifier die.
In some embodiments, an operating frequency of the RF transistor amplifier is in the R-band, S-band, X-band, Ku-band, K-band, Ka-band, and/or V-band.
Other devices, apparatus, and/or methods according to some embodiments will become apparent to one with skill in the art upon review of the following drawings and detailed description. It is intended that all such additional embodiments, in addition to any and all combinations of the above embodiments, be included within this description, be within the scope of the invention, and be protected by the accompanying claims.
In the following detailed description, numerous specific details are set forth to provide a thorough understanding of embodiments of the present disclosure. However, it will be understood by those skilled in the art that the present disclosure may be practiced without these specific details. In some instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to obscure the present disclosure. It is intended that all embodiments disclosed herein can be implemented separately or combined in any way and/or combination. Aspects described with respect to one embodiment may be incorporated in different embodiments although not specifically described relative thereto. That is, all embodiments and/or features of any embodiments can be combined in any way and/or combination.
As shown in
The channel layer 134 and barrier layer 136 may together form a semiconductor structure 190 on the substrate 132. A source contact 156 and a drain contact 154 are formed on an upper surface of the barrier layer 136 and are laterally spaced apart from each other. The source contact 156 and the drain contact 154 may each form an ohmic contact to the barrier layer 136.
A gate contact 152 is formed on the upper surface of the barrier layer 136 between the source contact 156 and the drain contact 154. A two-dimensional electron gas (2DEG) layer is formed at a junction between the channel layer 134 and the barrier layer 136 when the HEMT device 110 is biased to be in its conducting or “on” state. The 2DEG layer acts as a highly conductive layer that allows current to flow between the source and drain regions of the device that are beneath the source contact 156 and the drain contact 154, respectively. The source contact 156 may be coupled to a reference signal such as, for example, a ground voltage.
In some embodiments, one or more insulating layers 150 may directly contact the upper surface of the semiconductor structure 190 (e.g., contact the upper surface 136A of the barrier layer 136). The one or more insulating layers 150 may serve as passivation layers for the HEMT device 110.
In some embodiments, additional metal contacts (not shown) may be provided to contact the gate contact 152, the drain contact 154, and/or the source contact 156. For example, conductive pillar structures (e.g., copper pillars) may protrude from the front surface 112 of the HEMT device 100 to provide electrical connections between the gate contact 152, the drain contact 154, and/or the source contact 156 and an external device or module, such as the passive component assemblies described herein.
As shown in
In
As noted above, Group III nitride-based transistor devices, including the HEMT device 100 illustrated in
Pursuant to embodiments of the present disclosure, transistor devices, such as Group III nitride-based RF transistor amplifiers, include transistor dies that have one or more of their gate terminals, drain terminals, and source terminals located on the same (e.g., the “front”) side or surface of the transistor die, adjacent the active channel or active area. The transistor dies may not require bond wires for the gate and drain connections, which may reduce an amount of inductance present in the circuit, which may be advantageous in some applications. In addition, the top side gate, drain, and/or source contacts may allow for modular assembly techniques, for example, such that modules or assemblies can be coupled directly to the gate, drain, and/or source terminals of the RF transistor amplifier dies.
The modules or assemblies may be implemented as active modules or active component assemblies (which may include the active transistor die and coupling elements or structures thereon) and passive modules or passive component assemblies (which may include one or more passive electrical components that can provide additional circuitry, such as harmonic termination circuitry, input impedance matching circuitry, and/or output impedance matching circuitry). The active component assembly may be provided on a surface of the passive component assembly (e.g. on a back surface, opposite to the front surface on which the passive electrical components are provided). For example, the active module may include an active GaN on SiC die and redistribution layer (RDL) or heat spreader mounted on a surface of the passive module. The active module and passive module may be coupled by flip chip connection. As used herein, “flip chip” may refer to a configuration in which pads or terminals of a transistor device or other components are electrically connected by conductive bumps or pillars (rather than by wirebonds), which can allow for stacked or vertical connections with one or more other circuit elements.
The passive module may include various passive electrical components, implemented by discrete devices (e.g., surface mount devices (SMDs), integrated passive devices (IPDs) with thin film substrates such as silicon, alumina, or glass) in a flip chip configuration and/or by elements integrated in a multi-layer laminate structure (e.g., spiral inductors, plate or interdigitated capacitors, laminate-based transmission lines, etc.) to provide impedance matching and/or harmonic termination. The passive module may also include conductive pads (also referred to herein as interconnection pads) that are exposed (e.g., outside of or not covered by an overmold structure that covers the passive electrical components) so as to be accessible for electrical testing and screening before integration with the active modules, which may improve yield and reduce product costs.
A frame structure (which may be integral to or additionally provided on the surface of the passive component assembly on which the die is mounted) may extend around the active module for environmental protection and/or thermal conduction. Where the substrate of the transistor die (e.g., on the “back” side or inactive surface of the die) has a high thermal conductivity, such as a SiC growth substrate for a Group III nitride based HEMT, the active component assembly may include a thermally conductive carrier substrate or submount, such as a metal slug, leadframe, or flange, mounted on the bottom side or surface of the transistor die to provide improved thermal dissipation of the heat generated by the die from the amplifier package.
The frame structure may not only offer environmental protection of the die and mechanical support to the laminate or other interconnect structure for assembly flexibility, but may also provide an additional heat extraction path (i.e., in addition to the thermal path from the inactive surface of the transistor die to the flange) when formed of a material having high thermal conductivity and coupled to the thermally conductive carrier substrate. That is, the modular assembly may be configured to provide multiple thermal conduction paths for heat removal, which may allow for improved thermal performance and capabilities.
Embodiments of the present disclosure may also provide electrical ground paths separate from the main heat conduction path (e.g., by providing the source terminals on the front surface of the transistor die, and providing the heat conduction path(s) by coupling the frame structure and/or back surface of the transistor die to the thermally conductive substrate), which may otherwise be difficult or impossible to achieve without a flip chip interconnection scheme. Also, implementing the active and passive components of a packaged device as modular assemblies (with separate active and passive modules) and exposed test pads may allow for electrical testing and/or screening before final packaging/assembly, which can improve yield and reduce costs. Embodiments of the present disclosure may allow for stacked component connections (e.g., in the Z-direction), in some embodiments with an active components surrounded by an air cavity defined by a frame structure, passive components packaged in a mold structure, and package leads and/or test pads integrated on a surface (e.g., on the back side) of the passive component assembly or otherwise exposed by the mold structure and the frame structure. As used herein, the terms air cavity and open cavity may be used interchangeably to refer to a packaging structure in which components (e.g., transistor dies 210, passive devices 350, etc.) are enclosed in or protected by an air gap or air space (i.e., where one or more surfaces of the components do not physically contact another element), in contrast with encapsulation or protection by a mold structure where the encapsulant material physically contacts multiple surfaces of the components.
In any of the example active component assemblies 205a, 205b, 205c, 205d, 205e, 205f, the die 210 may be mounted in a flip chip arrangement on a surface 312, 314 of a passive component assembly 305, that is, with the gate terminal 222, the drain terminal 224, and the source terminal 226 facing the surface of the passive component assembly 305. In the example of
The conductive patterns 373 may provide various routing and/or circuitry within the interconnect structure 310. For example, the conductive patterns 373 may electrically connect interconnection pads 372, 374, 376 on the first surface 312 of the interconnect structure 310 to one another and/or to interconnection pads 322, 324, 326 on a second surface 314 of the interconnect structure 310. In particular, as shown in
The passive electrical components 350 may include, for example, resistors/transmission lines, capacitors, and/or inductors implemented by SMDs and/or IPDs and attached (e.g., by solder, conductive epoxy, etc.) and electrically connected to the conductive elements and/or traces provided by conductive connections 373. In the examples of
In the examples of
The mold structure 340 or other protective member may encapsulate or otherwise cover the passive electrical components 350, while leaving conductive contact pads exposed or otherwise free of the protective member. As shown in
The passive electrical components 350 coupled by the interconnect structure 310 may be configured to provide, for example, input matching circuits, output matching circuits, and/or harmonic termination circuits that are used to impedance match at the fundamental frequency and/or to terminate intermodulation products to ground. The use of passive component assemblies 305 described herein may thus provide greater flexibility in that different performance characteristics (e.g., to address harmonics at different frequencies, different impedances, etc.) for different applications may be achieved by swapping passive component assemblies 305 and/or the passive electrical components 350. In addition, the exposed interconnection pads 322, 324, 326, 372, 374, and/or 376 of the passive component assemblies 305 can be used for electrically testing before integration with the active component assemblies described herein, which may improve yield and reduce product costs. As such, passive component assemblies 305 in accordance with embodiments of the present disclosure may enable a modular approach for fabricating RF transistor amplifiers with desired performance characteristics.
Embodiments of the present disclosure may include various combinations of active component assemblies (e.g., 205a, 205b, 205c, 205d, 205e, 205f) and passive component assemblies (e.g., 305a, 305b, 305c, 305d, 305e, 305f), mounted on the first side 312 or second side 314 of the passive component assemblies. It will be understood that these embodiments are provided by way of illustration rather than limitation, and that any and all configurations of the passive component assembly 305 and active component assembly 205 are included in the scope of the present disclosure.
Likewise, the active component assemblies 205 and passive component assemblies 305 may be implemented in a packaged device using various packaging components that provide one or more protective structures.
The packaging components also include electrically conductive leads 415A, 415B (also referred to herein as package leads or RF leads) that are used for electrical connections to external circuit elements such as input and output RF transmission lines and bias voltage sources. The leads 415A, 415B may be coupled to the passive electrical components 350 of the passive module 305 using, for example, wire bonds or a conductive die attach material. In some embodiments, the leads 415A and 415B may be coupled to the interconnection pads on the first surface 312 of the interconnect structure 310 (e.g., to interconnection pads 372 and 374, respectively). In some embodiments, the leads 415A and 415B may be coupled to the interconnection pads on the second surface 314 (e.g., to interconnection pads 322 and 324, respectively). In some embodiments, the leads 415A, 415B may be directly coupled or may be integral to the interconnection pads, such that the use of wire bonds to connect the RF transistor amplifier 200 to leads 415A, 415B may be reduced or eliminated. Although primarily illustrated with reference to two leads 415A and 415B, embodiments of the present disclosure are not so limited. In some embodiments, three or more leads may be provided, for example, coupled to the interconnection pads 322 or 372 (e.g., as gate leads), 324 or 374 (e.g., as drain leads), and 326 or 376 (e.g., as source leads).
The passive electrical components 350 may thereby be electrically coupled between the gate terminal 222 and the first (e.g., input) lead 415A, and/or between the drain terminal 224 and the second (e.g., output) lead 415B. In particular, an RF signal input to the transistor die 210 on the input lead 415A may be passed through the interconnect structure 310 to passive electrical components 350 and from there to a gate terminal 222 of the transistor die 210, and the amplified output RF signal may be passed from the drain terminal 224 of the transistor die 210 to the passive electrical components 350 and from there through the interconnect structure 310 where the RF signal is output through output lead 415B.
In particular,
In particular,
Still referring to
The support structure(s) 2000s, 2000s′ may thus be configured to conduct heat away from the active component assembly 205 and/or the passive component assembly 305 and toward the thermally conductive substrate 410. The material(s) of the support structure(s) 2000s, 2000s′ may be electrically conductive in some embodiments, or electrically insulating in other embodiments. More generally, the shapes and/or material(s) of the support structure(s) 2000s, 2000s′ may be configured to provide a desired thermal conductivity and/or CTE.
The support structures 2000s and 2000s′ can be used alone or in combination with one or more of the packaging structures 400a, 400b, and/or 400c. For example, the ring- or frame-shaped support structure 2000s may be sized and dimensioned such that, when the transistor die 210 is provided on the substrate 410 within the perimeter of the support structure 2000s, an air cavity extends around the transistor die 210. In some embodiments, a passive module 305 (e.g., with passive components 350 encapsulated by a mold structure 340) may be stacked on the support structure 2000s opposite the substrate 410 with the exposed interconnection pads 322, 324, 372, and/or 374 providing the input or output package leads 415A or 415B. As such, some packages may include characteristics of both molded and open-cavity packages, as further described by way of example with reference to the embodiments of
Embodiments of the present disclosure may include various combinations of active component assemblies 205, passive component assemblies 305, and packaging components (e.g., 400a, 400b, 400c, 400d, 400e; collectively 400), and are not limited to those specifically shown and described herein. In some embodiments, the passive component assembly 305 may include the active component assembly 205 or transistor die 210 on the same side or surface of the interconnect structure as the passive electrical components 350, which may be referred to herein as an active module on same side of passive module (AMSPM) configuration. In some embodiments, the passive component assembly 305 may include the active component assembly 205 or transistor die 210 on an opposite surface of the interconnect structure than the passive electrical components 350, which may be referred to herein as an active module on backside of passive module (AMBPM) configuration.
As shown in
In the example AMSPM configuration of
As shown in
In
In
In the example AMBPM packages 600a to 600e of
The packages 600a to 600e further includes one or more support structures 2000s, 2000s′ on the second surface 314 of the interconnect structure 310 adjacent the die(s) 210. The support structure(s) 2000s, 2000s′ extend between the thermally conductive substrate 410 and the second surface 314 of the interconnect structure 310. The support structure(s) 2000s, 2000s′ may extend along or adjacent one or more sides of the die 210, and in some embodiments define an air gap or air cavity AC that extends along one or more sides (or completely around) the die 210. The support structure(s) 2000s, 2000s′ may be mounted (e.g., using a thermal layer 240) on a surface of the thermally conductive substrate 410 to provide improved mechanical support for the passive component assembly 305 stacked thereon, and may have a thickness (e.g., in the Z-direction) greater than or equal to a thickness of the active component assembly 205. The thickness of the support structure(s) 2000s, 2000s′ may be substantially similar to the die(s) 210 in some embodiments. In some embodiments, the support structure(s) 2000s may be formed of one or more materials that may improve thermal conduction, e.g., to provide an additional thermal path to conduct heat away from the active component assembly 205 and/or the passive component assembly 305 and toward the thermally conductive substrate 410.
As shown in
As shown in
In particular, in the example package 600c of
As shown in
As such, the package 600c includes a combination of a mold structure 340 on the passive electrical components 350, and a frame structure 2000s that provides an air cavity AC that extends around the transistor die 210. In other words, the package 600c includes features of both overmold and open cavity packages. In some embodiments, the support structure 2000s and the die 210 may be pre-assembled on the substrate 410 (for example, mounted by thermal layer(s) 240, such as the module 205e of
The example package 600d of
As shown in
The example package 600e of
As shown in
The packages 600a to 600e including modular active and passive component assemblies 205 and 305 according to some embodiments of the present disclosure thus each include a transistor die 210 having a gate terminal 222, a drain terminal 224, and a source terminal 226, one or more passive electrical components 350 electrically coupled to the gate terminal 222, the drain terminal 224, and/or the source terminal 226, and a support structure 2000s, 2000s′ on the surface 314 of the passive module 305 that defines or otherwise provides a cavity (which may be an air cavity or filled with an encapsulant) extending along one or more sides of the transistor die 210. The packages 600c to 600e may further include characteristics of overmold and open cavity packages.
In addition, in the packages 600a to 600e, the substrate 410 may be a thermally conductive material that provides a first heat conduction path (e.g., between the transistor die 210 and the substrate 410). The support structures 2000s, 2000s′ are coupled to the substrate 410 (e.g., by a thermal layer 240) to provide a second heat conduction path (e.g., between the passive component assembly 305 or die 210 and the substrate 410).
Moreover, the packages 500a, 500b, and 600a to 600e may include one or more conductive pads 322, 324 that are coupled to the one or more passive electrical components 350 and are exposed by the mold structure 340 and configured to be tested prior to assembly of the transistor die 210 on the passive component assembly 305. The package configurations described herein are provided by way of example only, and may include variations and any and all combinations the active component assemblies and passive component assemblies described herein, in AMSPM or AMBPM configurations.
At block 810, one or more active electrical components (e.g., transistor die(s) 210) are assembled on the surface of the substrate adjacent to the support structure, such that the support structure extends along one or more sides of the active electrical component(s). In some embodiments, the support structure may define a cavity that extends around the active electrical component(s). The active electrical component(s) and/or support structure(s) may be mounted on the substrate by a thermal adhesive or other thermally conductive layer (e.g., layer 240). The operations of blocks 805 and 810 may be performed in any order to define an active component assembly (e.g., active module 205).
Still referring to
Optionally, at block 820, electrical testing may be performed on the active and/or passive modules. For example, the passive electrical components of the passive module may be electrically tested using the exposed conductive pads. Defective component(s) may thereby be identified and replaced (either at the component-level or at the module level) before assembly into a final package, thereby improving yield. In embodiments where the passive modules include an encapsulating structure (e.g., mold structure 340) on the passive electrical component(s), the electrical testing at block 820 may be performed before or after forming the encapsulating structure.
At block 825, the passive module and the active module are stacked or otherwise assembled such that one or more of the passive electrical components are electrically coupled to the gate terminal, the drain terminal, and/or the source terminal of the transistor die(s). For example, the active module may be mounted (e.g., using one or more die attach layers) on the same or front surface of the passive module adjacent the passive electrical components (i.e., in an AMSPM configuration), or on an opposite or back surface of the passive module (i.e., in an AMBPM configuration). The active module may be mounted on the passive module in a flip chip configuration, with the gate drain, and/or source terminals facing the exposed conductive pads or other electrical interconnections of the passive module.
The package including the active and passive modules is completed at block 830, for example, by providing one or more additional packaging components for protection (e.g., a lid or package encapsulant material) and/or external connections (e.g., input and output leads 415A and 415B). For example, in some embodiments, a lid 625 and/or sidewall members 620 may be assembled on the stacked active and passive modules to arrive at the package 600a of
Still referring to
At block 935, a carrier substrate or flange (e.g., a thermally conductive substrate 410) is attached to the active electrical component(s) and the frame structure to define an active component assembly (e.g., active module 205), and a dicing or other singulation operation is performed at block 940. The flange may be thermal management structure, such as a metal flange or heatsink, to which the active electrical component(s) and/or the frame structure are mounted by a thermal adhesive or other thermally conductive layer (e.g., layer 240). In some embodiments, the flange attachment operations at block 935 may be performed before the singulation operations at block 940, such that the singulation operations separate the flange into respective carrier substrates. In some embodiments, the singulation operations at block 940 may be performed before respective flange attachment operations at block 935. The resulting packaged transistor device may thus include features of both overmold and open cavity packages, such as the package 600c of
Modular passive component assemblies 305 as described herein can allow for ease of assembly of RF transistor amplifier packages with different characteristics and/or additional functionality, such as impedance matching and/or harmonic termination. For example, by providing passive component assemblies 305 including interconnect structures 310 with exposed interconnection pads, one or more of the passive electrical components 350a, 350b, 350c can be configured and/or replaced to provide application-specific impedance characteristics. That is, transistor packages may be designed and/or reconfigured to provide different input/output matching and/or harmonic termination characteristics using the same interconnect structure 310 populated with different arrangements and/or combinations of the passive electronic components 350 on the exposed interconnection pads 322, 324, 326, 372, 374, 376.
Thus, different functionality and/or capability may be coupled to a transistor die 205 of an active component assembly 205 simply by using a different passive component assembly 305 and/or differently populating the passive component assembly 305 with different combinations and/or arrangements of passive electrical components 350. In addition, as discussed above, modular passive component assemblies 305 including interconnection pads 322, 324, 326, 372, 374, 376 that are exposed outside of a mold structure 340 can allow for electrical testing and/or component/module replacement before final assembly into a package, thus improving yield.
Further advantages of modular passive and active component assemblies as described herein may include simplified device packaging in which a molded passive component can be stacked (e.g., in z-direction) on an active component surrounded by an air cavity, with package leads integrated on a surface of the passive component, thereby reducing and/or eliminating additional packaging components and associated fabrication complexity and cost. The stacked active and passive component assemblies may also provide improved thermal capabilities, with a first heat conduction path provided by a flange mounted to the backside of the transistor die (which may be separate from the electrical ground path to which the source terminals are coupled), and an additional heat conduction path provided by a thermally conductive support structure(s) coupled to the flange adjacent a periphery of the transistor die.
Some embodiments of the present disclosure may be used in high power RF transistors for cellular or aerospace and defense (A&D) applications, such as 20 W or higher average output power RF transistors for 5G base station application at 3.5 GHz and above. Embodiments of the present disclosure may also provide lower cost products at higher frequencies.
While embodiments of the present disclosure have been described herein with reference to particular HEMT structures, the present disclosure should not be construed as limited to such structures, and may be applied to formation of many different transistor structures, such as pHEMTs (including GaAs/AlGaAs pHEMTs) and/or GaN MESFETs.
Various embodiments have been described herein with reference to the accompanying drawings in which example embodiments are shown. These embodiments may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure is thorough and complete and fully conveys the inventive concept to those skilled in the art. Various modifications to the example embodiments and the generic principles and features described herein will be readily apparent. In the drawings, the sizes and relative sizes of layers and regions are not shown to scale, and in some instances may be exaggerated for clarity.
It will be understood that, although the terms “first,” “second,” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
It will be understood that when an element such as a layer, region, or substrate is referred to as being “on,” “attached,” or extending “onto” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” or “directly attached” or extending “directly onto” another element, there are no intervening elements present. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present.
Relative terms such as “below” or “above” or “upper” or “lower” or “horizontal” or “lateral” or “vertical” may be used herein to describe a relationship of one element, layer or region to another element, layer or region as illustrated in the figures. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.
Embodiments of the invention are described herein with reference to cross-section illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the invention. The thickness of layers and regions in the drawings may be exaggerated for clarity. Additionally, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the invention should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. Elements illustrated by dotted lines may be optional in the embodiments illustrated.
Like numbers refer to like elements throughout. Thus, the same or similar numbers may be described with reference to other drawings even if they are neither mentioned nor described in the corresponding drawing. Also, elements that are not denoted by reference numbers may be described with reference to other drawings.
In the drawings and specification, there have been disclosed typical embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.