Galvanic isolation capacitors are typically employed to electrically isolate microelectronic devices (e.g., transistors).
In accordance with some examples, a multi-chip module (MCM), comprises a first and a second die-attach pad (DAP); a first die comprising a first set of microelectronic devices; a second die comprising a first capacitor and a second capacitor; and a third die comprising a second set of microelectronic devices, where the first and second dies are positioned on the first DAP, and the third die is positioned on the second DAP. The first set of microelectronic devices couples to the first capacitor via a first inter-die connection and the second set of microelectronic devices couples to the second capacitor via a second inter-die connection.
In accordance with some examples, a multi-chip module (MCM), comprises a first die comprising a first integrated circuit (IC) coupled to a first inter-die connection; a second die comprising a first capacitor and a second capacitor; and a third die comprising a second IC coupled to a second inter-die connection. The first capacitor coupled to the first IC via the first inter-die connection and the second capacitor coupled to the second IC via the second inter-die connection.
In accordance with some examples, a method of packaging a multi-chip module (MCM), the method comprises placing a first die including a first integrated circuit (IC) on a first die-attach pad (DAP); placing a second die including a pair of asymmetrical capacitors on the first DAP; and placing a third die including a second IC on a second DAP.
For a detailed description of various examples, reference will now be made to the accompanying drawings in which:
A multi-chip package (MCP) or multi-chip module (MCM) refers to a packaging configuration containing multiple dies (e.g., two or more dies). Inter-die communication in the MCM is typically achieved by die-to-die wire bonding. In some cases, one of the inter-connected dies includes an isolation capacitor (e.g., galvanic isolation capacitor) that is configured to provide electrical isolation (e.g., high voltage isolation) between an input terminal positioned on one die and an output terminal positioned on the other die. For the sake of illustration, the description below describes an MCM that includes a collection of microelectronic devices (e.g., integrated circuit (IC)) forming a transmitter circuit fabricated on one die and another collection of microelectronic devices forming a receiver circuit fabricated on a different die. The isolation capacitor, in this disclosure, provides isolation between the transmitter circuit and the receiver circuit. In this disclosure, the transmitter and receiver circuits are also configured to send signals (or communicate) via the isolation capacitor. However, the description below is not limited to the dies including transmitter and receiver circuits and may apply to the dies including other ICs. For examples, digital/analog circuits requiring high voltage isolation, and capacitive sensing circuits.
In some cases, the electrical isolation between receiver and transmitter circuits is achieved by fabricating an isolation capacitor on the die with the receiver (and/or transmitter) circuit. In such cases, the voltage isolation and communication capabilities are limited by the isolation ability of the isolation capacitor. In some cases, a pair of series-connected isolation capacitors with substantially equal capacitance may be employed to increase the voltage isolation and communication capabilities (see, for example, patent U.S. Pat. No. 9,299,697B2). In such cases, one isolation capacitor is typically fabricated on the die with the transmitter circuit, and the other isolation capacitor is fabricated on the other die with the receiver circuit. In such cases, the lower plate of both the isolation capacitors is at a potential substantially similar to its respective substrate, and both the substrates typically operate at different voltage nodes. Further, the output terminal of the transmitter circuit couples to one isolation capacitor, which is series-connected to the other isolation capacitor that is further coupled to the receiver circuit.
The fabrication process of the isolation capacitor positioned on the same die as the IC may be similar. For example, a complementary metal oxide semiconductor (CMOS) process (or other suitable processes) may be used to fabricate both the IC and the isolation capacitor disposed on the same die. However, embedding the isolation capacitor on the die with the IC reduces the portability of the isolation capacitor since it has to be qualified with a technology node of the IC. The technology node refers to a semiconductor manufacturing process and its design rules. The time required to qualify the isolation capacitor for a given technology node can be extensive, as the test time for measuring time-dependent dielectric breakdown (TDDB) of the isolation capacitor to assess its expected lifetime can take several months. Once the isolation capacitor is qualified with a particular technology node, only then it can be built on that technology node. This lengthy qualification procedure must be repeated for every technology node incorporating an isolation capacitor.
Embedding the isolation capacitor also has higher fabrication costs and results in a larger die size as the embedded isolation capacitor is cost and size limited due to the design rules and cost associated with the underlying IC. Moreover, embedding isolation capacitors and ICs on the same die may require adding extra metal levels to achieve the isolation requirements of the capacitor, which are otherwise not required for fabricating the underlying ICs, which also adds to the overall cost. The above-described limitations can be circumvented by using a standalone isolation device that is fabricated on a separate die. The standalone galvanic isolation device, in some cases, includes transformers fabricated using multiple layers of polyimide and gold. However, such standalone isolation transformers have high fabrication costs, are large in area, and have lower isolation ratings than traditional silicon dioxide capacitors. Therefore, alternative systems are needed to mitigate the issues mentioned above.
Accordingly, at least some of the examples disclosed herein include an MCM comprising standalone isolation. The standalone isolation is fabricated on a separate substrate (e.g., silicon, or other suitable substrates). In at least some examples, the standalone isolation comprises a capacitor or multiple capacitors connected in series with the circuits disposed on other dies of the MCM. In at least some examples, the standalone capacitors employ one or more layers of thick (e.g., 10 micrometers or more) dielectrics positioned between a top metal layer and a bottom metal layer to form the standalone capacitors. In at least some examples, the MCM includes multiple die-attach pads (DAPs). In at least some examples, the die with the standalone capacitors is positioned on a separate die-attach pad (DAP). In some examples, the die with the standalone capacitors shares the DAP with another die including an IC.
The circuit 100 further includes capacitors 110, 112, which are disposed in a die 104. The capacitor 110 has a first plate 109 and a second plate 111. For the sake of simplicity, the first plate 109 is referred to as top plate 109 and the second plate 111 is referred to as a bottom plate 111. The capacitor 112 has a first plate 114 and a second plate 113. Again, for simplicity's sake, the first plate 114 is referred to as a top plate 114 and the second plate 113 is referred to as a bottom plate 113. In the example shown in
The example of the transmitter and receiver circuits 105, 116, respectively, has been chosen for the sake of illustration. This disclosure applies to the circuit 100 including a collection of microelectronic devices (such as the transmitter circuit 105) forming a first circuit fabricated on a first die (such as the semiconductor die 102) and another collection of microelectronic devices (such as the receiver circuit 116) forming a second circuit fabricated on a second die (such as the semiconductor die 106). In other examples, different digital/analog circuits requiring high voltage isolation may form the circuits positioned on the semiconductor dies 102, 106. The MCM in which the circuit 100 is disposed further includes DAPs, depicted in
For simplicity's sake, the microelectronic elements 234 are depicted by a block. In actual implementation, examples of the various microelectronic elements 234 that may be formed in the substrate 224 include: transistors (e.g., metal oxide semiconductor field effect transistors (MOSFET), complementary metal oxide semiconductor (CMOS) transistors, bipolar junction transistors (BJT), high voltage transistors, high frequency transistors, p-channel and/or n-channel field effect transistors (PFETs/NFETs), etc.); resistors; diodes; capacitors; inductors; and other suitable elements. Various processes are performed to form the various microelectronic elements including deposition, etching, implantation, photolithography, annealing, and other suitable processes. The microelectronic elements are interconnected via metallic interconnects to form the semiconductor device (or, in other words, the IC), such as a logic device, sensor device, radio frequency (RF) device, input/output (I/O) device, system-on-chip (SoC) device, combinations thereof, and other suitable types of devices. Therefore, in some examples, the microelectronic elements 234 (or microelectronic devices 234) can be referred to include the IC.
The cross-section of the die 102 further shows a portion 230 disposed on the substrate 224. The portion 230, in some examples, may include pre-metal dielectric layer 201, a metal layer 202. In some examples, a protective overcoat layer 203 and a polyimide layer 204 are supported by the metal layer 202. At least some of the parts comprising the portion 230 provide a pathway between the microelectronic elements 234 and other circuits disposed in the MCM. For example, the portion 230 includes a bonding structure 205 that couples to the metal layer 202. The metal layer 202 electrically couples (through vias and other interconnect metal layers) to the microelectronic elements 234 and to the inter-die connection 207 that connects to the circuitry (or electronic elements, such as capacitors) positioned on other dies. The inter-die connection 207 is similar to the inter-die connection 107 of
Similar to the cross-sectional side view of the die 102,
For simplicity's sake, the microelectronic elements 236 are depicted by a block. In actual implementation, examples of the various microelectronic elements 236 that may be formed in the substrate 226 include: transistors (e.g., metal oxide semiconductor field effect transistors (MOSFET), complementary metal oxide semiconductor (CMOS) transistors, bipolar junction transistors (BJT), high voltage transistors, high frequency transistors, p-channel and/or n-channel field effect transistors (PFETs/NFETs), etc.); resistors; diodes; capacitors; inductors; and other suitable elements. Various processes are performed to form the various microelectronic elements including deposition, etching, implantation, photolithography, annealing, and other suitable processes. The microelectronic elements are interconnected via metallic interconnects to form the semiconductor device (or, in other words, the IC) such as a logic device, sensor device, radio frequency (RF) device, input/output (I/O) device, system-on-chip (SoC) device, combinations thereof, and other suitable types of devices. Therefore, in some examples, the microelectronic elements 236 (or microelectronic devices 236) can be referred to include the IC.
The cross-section of the die 106 further shows a portion 231 that is disposed on the substrate 226. The portion 231, in some examples, may include pre-metal dielectric layer 218 and a metal layer 219. In some examples, a protective overcoat layer 229 and a polyimide layer 221 are supported by the metal layer 219. At least some of the parts comprising the portion 231 provide a pathway between the microelectronic elements 236 and other circuits disposed in the MCM. For example, the portion 231 includes a bonding structure 223 that couples to the metal layer 219. The metal layer 219 electrically couples (through vias and other interconnect metal layers) to the microelectronic elements 236 and to the inter-die connection 208 that connects to the circuitry (or electronic elements, such as capacitors) positioned on other dies. The die 106 further includes a bonding structure 223 that couples to the inter-die connection 208 and forms a connection with circuitry (or electronic elements, such as capacitors) positioned on other dies. The inter-die connection 208 is similar to the inter-die connection 108 of
The capacitors 110, 112 further include metal layers 211, 212 forming the top plates 109, 114, (
Fabricating the capacitors 110, 112 further includes depositing a protective overcoat oxide layer 215 between the metal layers 211, 212. In some examples, the protective overcoat oxide layer 215 may be partially disposed (not expressly depicted in
Referring now to
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In the foregoing discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection or through an indirect connection via other devices and connections. Similarly, a device that is coupled between a first component or location and a second component or location may be through a direct connection or through an indirect connection via other devices and connections. An element or feature that is “configured to” perform a task or function may be configured (e.g., programmed or structurally designed) at a time of manufacturing by a manufacturer to perform the function and/or may be configurable (or re-configurable) by a user after manufacturing to perform the function and/or other additional or alternative functions. The configuring may be through firmware and/or software programming of the device, through a construction and/or layout of hardware components and interconnections of the device, or a combination thereof. Additionally, uses of the phrases “ground” or similar in the foregoing discussion are intended to include a chassis ground, an Earth ground, a floating ground, a virtual ground, a digital ground, a common ground, and/or any other form of ground connection applicable to, or suitable for, the teachings of the present disclosure. Unless otherwise stated, “about,” “approximately,” or “substantially” preceding a value means +/−10 percent of the stated value.
The above discussion is meant to be illustrative of the principles and various embodiments of the present disclosure. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.