The present disclosure relates in general to coupling electronic signals into and out of an integrated circuit (IC). More specifically, the present disclosure relates to systems, methodologies and resulting structures for executing the direct transfer of electronic signals into and out of a semiconductor-based IC in a manner that eliminates the need for intermediary coupling mechanisms such as printed circuit boards (PCBs), wire bond connections, and the like.
Semiconductor devices are used in a variety of electronic and electro-optical applications. ICs are typically formed from various circuit configurations of semiconductor devices formed on semiconductor wafers. Alternatively, semiconductor devices may be formed as monolithic devices, e.g., discrete devices. Semiconductor devices are formed on semiconductor wafers by depositing many types of thin films of material over the semiconductor wafers, patterning the thin films, doping selective regions of the semiconductor wafers, etc. In a conventional semiconductor fabrication process, a large number of semiconductor devices are fabricated in a single wafer. CMOS (complementary metal-oxide semiconductor) is the semiconductor fabrication technology used in the transistors that are manufactured into most of today's computer microchips. In CMOS technology, both n-type and p-type transistors are used in a complementary way to form a current gate that forms an effective means of electrical control. Processing steps performed later in CMOS technology fabrication sequences are referred to as back-end-of-line (BEOL) CMOS processing, and processing steps performed earlier in CMOS technology fabrication sequences are referred to as front-end-of-line (FEOL) CMOS processing.
After completion of device level and interconnect level fabrication processes, the semiconductor devices on the wafer are separated into micro-chips (i.e., chips), and the final product is packaged. IC packaging typically involves encasing the silicon chip(s) inside a hermetically sealed plastic, metal or ceramic package that prevents the chip(s) from being damaged by exposure to dust, moisture or contact with other objects. IC packaging also allows easier connections to a PCB. The purpose of a PCB is to connect ICs and discreet components together to form larger operational circuits. Other parts that can be mounted to the PCB include card sockets, microwave connectors, and the like.
Wire bonding is a known BEOL operation for forming electrical interconnections between a PCB and other components (e.g., external components, card sockets, microwave connectors, etc.). In wire bonding, a length of small diameter soft metal wire (e.g., gold (Au), copper (Cu), silver (Ag), aluminum (Al), and the like) is attached or bonded without the use of solder to a compatible metallic surface or pad mounted on a PCB. The actual bond between the wire and the pad can be formed in a variety of ways, including thermocompression, thermosonic and ultrasonic. Although wire bonding is widely used, the additional wire bond hardware, particularly in microwave/radio frequency (RF) applications, is manually intensive to fabricate, suffers from low temperature CTE (coefficient of thermal expansion) mismatches, is difficult to reliably repeat, causes signal path problems, increases cost, adds bulk and introduces extraneous microwave cavity modes.
Embodiments are directed to a method of forming a coupler system. The method includes forming a semiconductor wafer, forming an interconnect layer coupled to the semiconductor wafer, and physically securing and electronically coupling a connector to the interconnect layer.
Embodiments are further directed to a method of forming a coupler system. The method includes forming a semiconductor wafer, forming an interconnect layer coupled to the semiconductor wafer, forming radio frequency (RF) circuitry electronically coupled to the interconnect layer, physically securing and electronically coupling a microwave connector to the interconnect layer.
Embodiments are further directed to a method of forming a coupler system. The method includes forming a semiconductor wafer, forming an interconnect layer coupled to the semiconductor wafer, forming radio frequency (RF) circuitry electronically coupled to the interconnect layer, physically securing and electronically coupling a microwave connector to the interconnect layer, wherein the microwave connector and interconnect layer are configured to couple electronic signals to the RF circuitry.
Embodiments are further directed to a coupler system including a semiconductor wafer, an interconnect layer coupled to the semiconductor wafer and a connector formed over the interconnect layer, wherein the connector is physically secured and electronically coupled to the interconnect layer. In one or more of the above-described embodiments, the connector is physically secured and electronically coupled to the interconnect layer by a structure comprising a bond layer and an electrically conductive layer. In one or more of the above-described embodiments, the structure is formed according to a methodology that includes forming the bond layer over the interconnect layer, forming the electrically conductive layer as a solder layer over the bond layer, and applying a reflow operation to at least the solder layer.
Embodiments are further directed to a coupler system including a semiconductor wafer, an interconnect layer coupled to the semiconductor wafer, and RF circuitry electronically coupled to the interconnect layer. The coupler system further includes a microwave connector physically secured and electronically coupled to the interconnect layer. In one or more of the above-described embodiments, the microwave connector is physically secured and electronically coupled to the interconnect layer by a structure. In one or more of the above-described embodiments, the structure comprises a bond layer and an electrically conductive layer. In one or more of the above-described embodiments, the structure is formed according to a methodology that includes forming the bond layer over the interconnect layer, forming the electrically conductive layer as a solder layer over the bond layer, and applying a reflow operation to at least the solder layer.
Additional features and advantages are realized through the techniques described herein. Other embodiments and aspects are described in detail herein. For a better understanding, refer to the description and to the drawings.
The subject matter which is regarded as the present disclosure is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
In the accompanying figures and following detailed description of the disclosed embodiments, the various elements illustrated in the figures are provided with three or four digit reference numbers. The leftmost digit(s) of each reference number corresponds to the figure in which its element is first illustrated.
It is understood in advance that, although this disclosure includes a detailed description of attaching a specific type of microwave connector to interconnect metallurgy on a silicon wafer/chip, implementation of the teachings recited herein are not limited to a particular type of connector or transmission architecture. Rather embodiments of the present disclosure are capable of being implemented in conjunction with any other type of connector or transmission architecture, now known or later developed.
Various embodiments of the present disclosure are described herein with reference to the related drawings. Alternative embodiments may be devised without departing from the scope of this disclosure. It is noted that various connections and positional relationships (e.g., over, below, adjacent, etc.) are set forth between elements in the following description and in the drawings. These connections and/or positional relationships, unless specified otherwise, may be direct or indirect, and the present disclosure is not intended to be limiting in this respect. Accordingly, a coupling of entities may refer to either a direct or an indirect coupling, and a positional relationship between entities may be a direct or indirect positional relationship. As an example of an indirect positional relationship, references in the present disclosure to forming layer “A” over layer “B” include situations in which one or more intermediate layers (e.g., layer “C”) is between layer “A” and layer “B” as long as the relevant characteristics and functionalities of layer “A” and layer “B” are not substantially changed by the intermediate layer(s).
The term “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs. The terms “at least one” and “one or more” may be understood to include any integer number greater than or equal to one, i.e. one, two, three, four, etc. The terms “a plurality” may be understood to include any integer number greater than or equal to two, i.e. two, three, four, five, etc. The term “connection” may include both an indirect “connection” and a direct “connection.”
As previously noted herein, after completion of device level and interconnect level fabrication processes, the semiconductor devices on the wafer are separated into micro-chips (i.e., chips), and the final products is packaged. IC packaging typically involves encasing the silicon chip(s) inside a hermetically sealed plastic, metal or ceramic package that prevents the chip(s) from being damaged by exposure to dust, moisture or contact with other objects. IC packaging also allows easier connections to a PCB. The purpose of a PCB is to connect ICs and discreet components together to form larger operational circuits. Other parts that can be mounted to the PCB include card sockets, microwave connectors, and the like.
Wire bonding is a known BEOL operation for forming electrical interconnections between a PCB and other components (e.g., external components, card sockets, microwave connectors, etc.). In wire bonding, a length of small diameter soft metal wire (e.g., Au, Cu, Ag, Al, and the like) is attached or bonded with the use of solder to a compatible metallic surface or pad mounted on a PCB. The actual bond between the wire and the pad can be formed in a variety of ways, including thermocompression, thermosonic and ultrasonic. Although wire bonding is widely used, the additional wire bond hardware, particularly in microwave/RF applications, is manually intensive to fabricate, suffers from low temperature CTE mismatches, is difficult to reliably repeat, causes signal path problems, increases cost, adds bulk and introduces extraneous microwave cavity modes.
The present disclosure provides systems, methodologies and resulting structures for executing the direct transfer of electronic signals into and out of a semiconductor-based IC in a manner that eliminates the need for intermediary coupling mechanisms such as PCBs, wire bond connections, and the like. In one or more embodiments, electronic connectors (e.g., microwave connectors) are attached directly to interconnect metallurgy (e.g., Cu, Al, etc.) on a semiconductor (e.g., Si, GaAs, and the like) wafer or chip. The interconnect metallurgy (or interconnect layer) can take a variety of forms, including, for example, metal on film, damascene metal, diffusion or any other type of conductive contact area on the wafer. In one or more embodiments, a bond stack and solder attachment method is utilized to physically secure and electronically couple the electronic connectors directly to the interconnect metallurgy layer. The bond stack metallurgy is tailored to the specific joining method and material. In one or more embodiments, the disclosed semiconductor wafer functions as an interposer that couples the electronic connector to other circuitry (e.g., RF circuitry) on the semiconductor wafer. Accordingly, the present disclosure avoids the manually intensive fabrication, low temperature CTE mismatches, lack of repeatability, signal path problems, increased cost, added bulk and extraneous microwave cavity modes introduced by routing electronic signals through intermediary coupling mechanisms such as PCBs and wire bond connections.
For the sake of brevity, conventional techniques related to semiconductor device and IC fabrication may not be described in detail herein. Moreover, the various tasks and process steps described herein may be incorporated into a more comprehensive procedure or process having additional steps or functionality not described in detail herein. In particular, various steps in the manufacture of semiconductor devices and semiconductor-based ICs are well known and so, in the interest of brevity, many conventional steps will only be mentioned briefly herein or will be omitted entirely without providing the well-known process details.
By way of background, however, a more general description of the semiconductor device fabrication processes that may be utilized in implementing one or more embodiments of the present disclosure will now be provided. Although specific fabrication operations used in implementing one or more embodiments of the present disclosure may be individually known, the disclosed combination of operations and/or resulting structures of the present disclosure are unique. Thus, the unique combination of the operations described in connection with the fabrication of a coupler system according to the present disclosure utilize a variety of individually known physical and chemical processes performed on a semiconductor (e.g., silicon) substrate. In general, the various processes used to form a micro-chip that will be packaged into an IC fall into three categories, namely, film deposition, patterning, etching and semiconductor doping. Films of both conductors (e.g., poly-silicon, aluminum, copper, etc.) and insulators (e.g., various forms of silicon dioxide, silicon nitride, etc.) are used to connect and isolate transistors and their components. Selective doping of various regions of the semiconductor substrate allows the conductivity of the substrate to be changed with the application of voltage. By creating structures of these various components, millions of transistors can be built and wired together to form the complex circuitry of a modern microelectronic device.
Fundamental to all of the above-described fabrication processes is semiconductor lithography, i.e., the formation of three-dimensional relief images or patterns on the semiconductor substrate for subsequent transfer of the pattern to the substrate. In semiconductor lithography, the patterns are a light sensitive polymer called a photo-resist. To build the complex structures that make up a transistor and the many wires that connect the millions of transistors of a circuit, lithography and etch pattern transfer steps are repeated multiple times. Each pattern being printed on the wafer is aligned to the previously formed patterns and slowly the conductors, insulators and selectively doped regions are built up to form the final device.
Turning now to a more detailed description of one or more embodiments, a fabrication methodology for forming various stages of a coupler system according to the present disclosure will now be described with reference to
Thus, it can be seen from the foregoing detailed description and accompanying illustrations that one or more embodiments of the present disclosure provide systems, methodologies and resulting structures for executing the direct transfer of electronic signals into and out of a semiconductor-based IC in a manner that eliminates the need for intermediary coupling mechanisms such as PCBs, wire bond connections, and the like. In one or more embodiments, electronic connectors (e.g., microwave connectors) are attached directly to interconnect metallurgy (e.g., Cu, Al, etc.) on a semiconductor (e.g., Si, GaAs, and the like) wafer or chip. In one or more embodiments, a bond stack and solder attachment method is utilized to physically secure and electronically couple the electronic connectors directly to the interconnect metallurgy layer. Eliminating the need for intermediary coupling mechanisms such as PCBs, wire bond connections, and the like, minimizes the use of non-like materials in the structure that physically couples microwave connector 402 to wafer 102, which mitigates the impact of low temperature CTE mismatches. Additionally, the relatively small size (e.g., 2 millimeters by 2 millimeters) area of the microwave connector 402 that is coupled through the bond stack to the wafer 102 further mitigates the impact of low temperature CTE mismatches. The bond stack metallurgy is tailored to the specific joining method and material. In one or more embodiments, the disclosed semiconductor wafer functions as an interposer that couples the electronic connector to other circuitry (e.g., RF circuitry, microwave circuitry, transmissions lines, resonators, capacitors, etc.) on the semiconductor wafer. Accordingly, the present disclosure avoids the manually intensive fabrication, low temperature CTE mismatches, lack of repeatability, signal path problems, increased cost, added bulk and extraneous microwave cavity modes introduced by routing electronic signals through intermediary coupling mechanisms such as PCBs and wire bond connections.
In some embodiments, various functions or acts may take place at a given location and/or in connection with the operation of one or more apparatuses or systems. In some embodiments, a portion of a given function or act may be performed at a first device or location, and the remainder of the function or act may be performed at one or more additional devices or locations.
The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosure. The embodiments were chosen and described in order to best explain the principles of the disclosure and the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.
The flowchart and block diagrams in the figures illustrate the functionality and operation of possible implementations of systems and methods according to various embodiments of the present disclosure. In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. The actions may be performed in a differing order or actions may be added, deleted or modified. Also, the term “coupled” describes having a signal path between two elements and does not imply a direct connection between the elements with no intervening elements/connections therebetween. All of these variations are considered a part of the disclosure.
The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of ±8% or 5%, or 2% of a given value.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. 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” and/or “comprising,” when used in this specification, 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, element components, and/or groups thereof.
While the present disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the present disclosure is not limited to such disclosed embodiments. Rather, the present disclosure can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the present disclosure. Additionally, while various embodiments of the present disclosure have been described, it is to be understood that aspects of the present disclosure may include only some of the described embodiments. Accordingly, the present disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
The invention described in the present disclosure was made with government support under government contract number H98230-13-D-0173 awarded by the National Security Agency. The government has certain rights in the invention.