Electrical circuit apparatus and methods including hermeticity testing structures for testing the hermeticity of the electrical circuit apparatus.

BACKGROUND

The disclosure herein relates generally to apparatus and methods for hermeticity testing, and further to fabrication methods for constructing such apparatus.

Electrical circuits (e.g., integrated circuits) include many types of active and passive devices (e.g., transistors, capacitors, resistors, etc.) that may be subject to damage from moisture (e.g., corrosion and functional changes to the system). For example, moisture may affect the operation and performance of circuitry, such as sensitive circuits used in implantable medical devices (e.g., sensor circuitry, pacing circuitry, timing circuitry, etc.).

Various attempts have previously been made to test the hermeticity of electrical circuit apparatus. For example, U.S. Pat. No. 4,775,831 entitled “IN-LINE DETERMINATION OF PRESENCE OF LIQUID PHASE MOISTURE IN SEALED IC PACKAGES,” issued on Oct. 4, 1988, describes measuring the conductance and capacitance of an integrated circuit at a temperature that is above temperatures which allow moisture to condense, subsequently measuring the conductance and capacitance of the integrated circuit at a temperature that allows moisture to condense, and comparing the two measured conductances and capacitances to determine the hermeticity of the integrated circuit. Further, for example, U.S. Pat. No. 5,606,264 entitled “MOISTURE SENSOR FOR ELECTRONIC MODULES,” issued on Feb. 25, 1997, describes utilizing a moisture sensing circuit formed of loosely spaced conductor lines consisting of migratory metal, which reacts to moisture.

SUMMARY

The disclosure herein relates generally to apparatus for hermeticity testing, methods of fabrication of such apparatus, and methods for testing such apparatus for hermeticity. For example, as described in one or more embodiments herein, semiconductor substrates and semiconductor fabrication techniques may be used to provide a testing structure around one or more hermetically-sealed regions of a circuit device (e.g., a die that includes circuitry).

One exemplary apparatus disclosed herein includes electrical circuit apparatus including a first portion, a second portion, and one or more circuit devices (e.g., including electrical circuitry, forming a part of an implantable medical device, etc.). The first portion includes a first chain-structure portion of a testing structure. Further, the first portion includes a substantially-planar connection surface, a substrate (e.g., a semiconductor substrate) provided from a wafer, and one or more chain-structure segments forming at least a part of the first chain-structure portion. Each chain-structure segment includes two connection pads exposed at the connection surface and an electrical interconnect electrically coupling the two connection pads. The second portion includes a second chain-structure portion of the testing structure. Further, the second portion includes a substantially-planar connection surface, a substrate (e.g., a semiconductor substrate) provided from a wafer, and one or more chain-structure segments forming at least a part of the second chain-structure portion. Each chain-structure segment includes two connection pads exposed at the connection surface and an electrical interconnect electrically coupling the two connection pads. The one or more circuit devices are located in one or more hermetically-sealed regions. Further, the connection surface of the first portion is bonded to the connection surface of the second portion and each connection pad of one or more chain-structure segments of the first portion is electrically coupled to a connection pad of the one or more chain-structure segments of the second portion to form the testing structure. The testing structure includes at least one series circuit (e.g., at least two series circuits interleaved with each other) extending from a first end to a second end around the one or more hermetically-sealed regions and aimed at an interface of the connection surface of the first portion and the connection surface of the second portion. In at least one embodiment, the first portion further includes one or more layers formed on the substrate terminating at the connection surface and the one or more layers of the first portion include each chain-structure segment of the first portion and/or a circuit device of the one or more circuit devices. Further, the second portion includes one or more layers formed on the substrate terminating at the connection surface and the one or more layers of the second portion include each chain-structure segment of the second portion and/or a circuit device of the one or more circuit devices.

One exemplary method disclosed herein includes forming an electrical circuit apparatus. The method includes providing a first portion, providing a second portion, and providing one or more circuit devices (e.g., including electrical circuitry, forming a part of an implantable medical device, etc.). The first portion includes a first chain-structure portion of a testing structure and a substantially-planar connection surface. Providing the first portion includes providing a substrate (e.g., a semiconductor substrate) provided from a wafer and providing one or more chain-structure segments. The one or more chain-structure segments form at least a part of the first chain-structure portion and each chain-structure segment includes two connection pads exposed at the connection surface and an electrical interconnect electrically coupling the two connection pads. The second portion includes a second chain-structure portion of the testing structure and a substantially-planar connection surface. Providing the second portion includes providing a substrate (e.g., a semiconductor substrate) provided from a wafer and providing one or more chain-structure segments. The one or more chain-structure segments form at least a part of the second chain-structure portion and each chain-structure segment includes two connection pads exposed at the connection surface and an electrical interconnect electrically coupling the two connection pads. Further, the one or more circuit devices are located in one or more hermetically-sealed regions. The method further includes bonding the connection surface of the first portion to the connection surface of the second portion, e.g., such that each connection pad of one or more chain-structure segments of the first portion is electrically coupled to a connection pad of the one or more chain-structure segments of the second portion to form the testing structure. Further, the testing structure includes at least one series circuit (e.g., at least two series circuits interleaved with each other) extending from a first end to a second end around the one or more hermetically-sealed regions and formed at an interface of the connection surface of the first portion and the connection surface of the second portion.

Another exemplary method disclosed herein includes testing an electrical circuit apparatus. The method includes providing an electrical circuit apparatus. The apparatus includes a first portion, a second portion, and one or more circuit devices (e.g., including electrical circuitry, forming a part of an implantable medical device, etc.). The first portion includes a first chain-structure portion of a testing structure. Further, the first portion includes a substantially-planar connection surface, a substrate (e.g., a semiconductor substrate) provided from a wafer, and one or more chain-structure segments forming at least a part of the first chain-structure portion. Each chain-structure segment includes two connection pads exposed at the connection surface and an electrical interconnect electrically coupling the two connection pads. The second portion includes a second chain-structure portion of the testing structure. Further, the second portion includes a substantially-planar connection surface, a substrate (e.g., a semiconductor substrate) provided from a wafer, and one or more chain-structure segments forming at least a part of the second chain-structure portion. Each chain-structure segment includes two connection pads exposed at the connection surface and an electrical interconnect electrically coupling the two connection pads. The one or more circuit devices define one or more hermetically-sealed regions. Further, the connection surface of the first portion is bonded to the connection surface of the second portion, wherein each connection pad of one or more chain-structure segments of the first portion is electrically coupled to a connection pad of the one or more chain-structure segments of the second portion to form the testing structure. The testing structure includes at least one series circuit extending from a first end to a second end around the one or more hermetically-sealed regions and formed at an interface of the connection surface of the first portion and the connection surface of the second portion. The method further includes testing the at least one series circuit of the testing structure to confirm or validate hermeticity about the one or more hermetically-sealed areas (e.g., determining if the at least one series circuit is open, determining if a first series circuit of the at least two series circuits is shorted to a second series circuit of the at least two series circuits, etc.).

The above summary is not intended to describe each embodiment or every implementation of the present disclosure. A more complete understanding will become apparent and appreciated by referring to the following detailed description and claims taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Exemplary apparatus, and methods of constructing such apparatus, shall be described with reference toFIGS. 1-7. It will be apparent to one skilled in the art that elements from one embodiment may be used in combination with elements of the other embodiments, and that the possible embodiments of such apparatus using combinations of features set forth herein is not limited to the specific embodiments shown in the Figures and/or described herein. Further, it will be recognized that the embodiments described herein may include many elements that are not necessarily shown to scale. Further, it will be recognized that the size and shape of various elements herein may be modified but still fall within the scope of the present disclosure, although one or more shapes and/or sizes, or types of elements, may be advantageous over others.

FIGS. 1A-1Bshow generalized exploded and assembled perspective views of components which may form a part of an exemplary apparatus10that when assembled includes one or more circuit devices90located along an axis12and within in one or more hermetically-sealed regions80(seeFIG. 1B) and a testing structure100extending (represented schematically by a dashed line) around or at least partially around the one or more hermetically-sealed regions80along a plane orthogonal to the axis12. The testing structure100may be located around the one or more circuit devices90at a distance further away from the axis12than the one or more devices90and located within the hermetically-sealed regions80.

Although not limited thereto, in one or more embodiments, the apparatus10is beneficial for the circuitry of a package used in implantable medical devices. For example, the apparatus10including the testing structure100may be a part of an implantable medical device. For example, the implantable medical device may be a device implantable in a body near a human heart. For example, the implanted medical device may be any implantable cardiac pacemaker, defibrillator, cardioverter-defibrillator, or pacemaker-cardioverter-defibrillator (PCD). Further, for example, the implantable medical device may be an implantable nerve stimulator or muscle stimulator, an implantable monitoring device (e.g., a hemodynamic monitoring device), a brain stimulator, a gastric stimulator, a drug pump, or any other implantable device that would benefit from moisture protection. As used herein, “moisture” may be defined as any material capable of ingressing into semiconductor devices. For example, moisture may include water, biological liquids, vapors, gases, etc. Therefore, the apparatus10may find wide application in any form of implantable medical device. As such, any description herein making reference to any particular medical device is not to be taken as a limitation of the type of medical device which can benefit from and which can employ the testing structure100as described herein.

Further, although the testing structure100may be beneficial for implantable medical devices, such structure is not limited to such applications. For example, such testing structure may be beneficial for many different types of circuitry (e.g., whether for medical use or not, whether for an implantable medical device or not). For example, one or more types of circuits that may benefit from such testing structure may include circuits such as sensor circuits, pacing circuits, timing circuits, telemetry circuits, etc.

The apparatus10, as shown generally in the exploded views ofFIGS. 1A-1B, includes a first portion20and a second portion40. The first portion20includes at least one side surface28(e.g., one side surface, four side surfaces, etc.) substantially parallel to the axis12and at least a substantially planar connection surface26substantially orthogonal to the axis12. The second portion40also includes at least one side surface48(e.g., one side surface, four side surfaces, etc.) substantially parallel to the axis12and at least a substantially planar connection surface46substantially orthogonal to the axis12.

The one or more circuit devices90may be formed in one or both (in both, as shown) of the first portion20and the second portion40lying along axis12. Further, although not depicted, one or both of the first portion20and the second portion40may define a cavity and at least one of the one or more circuit devices90may be located within the cavity. Further, the one or more circuit devices90may be provided and located in any manner within the hermetically-sealed regions80. As used herein, the one or more circuit devices90may be any device or devices that include electrical circuitry that performs one or more functions (e.g., die containing circuitry).

The first portion20includes a first chain-structure portion110of the testing structure100and the second portion40includes a second chain-structure portion120of the testing structure100. When assembled and/or coupled together to form interface82(e.g., the connection surface26of the first portion20is bonded (e.g., oxide bonded) to the connection surface46of the second portion40, or in other words, to, e.g., form a face-to-face bonded die), the first chain-structure portion110and the second chain-structure portion120of the first and second portions20,40, respectively, form the testing structure100. Generally, the testing structure100may be utilized to test the hermeticity of the one or more hermetically-sealed regions80of the apparatus10.

The testing structure100may take any shape or size suitable for its intended purpose. For example, the testing structure100may be rectangular in shape (e.g., with four side), circular in shape (e.g., a single circular side), etc. Further, for example, the shape of the testing structure100may not be describable by a particular shape (e.g., in the case where, for example, the structure is shaped to conform to a region that it extends around). Still further, in one or more embodiments, the testing structure100may only occupy a portion of the apparatus10to surround specific hermetically-sealed regions that may contain moisture sensitive circuitry (see, e.g.,FIGS. 5A-5B). Yet still further, in or more embodiments, the testing structure100may only extend around a portion of a hermitically-sealed region, e.g., a single side, two or more sides, etc.

Although the first and the second chain-structure portions110,120are represented schematically as dashed lines inFIGS. 1A-1B, each of the first and the second portions20,40may include one or more chain-structure segments that form at least part of the chain-structure portions110,120of the testing structure100. Such chain-structure segments are described herein with further detail in reference toFIGS. 2-5.

Further, the testing structure100includes at least one series circuit extending from a first end to a second end around the one or more hermetically-sealed regions80and formed at the interface82(seeFIG. 1B) of the connection surface26of the first portion20and the connection surface46of the second portion. The at least one series circuit of the testing structure100may be utilized to, e.g., confirm or validate hermeticity about the one or more hermetically-sealed areas80. Such methods are described herein with further detail in reference toFIGS. 6-7.

Wafer scale fabrication techniques may be used to form each of the first and second portions20,40. In one or more embodiments, each of the first portion20and the second portion40includes a substrate provided from or as a part of a wafer (e.g., a portion of any size and shape of substrate usable in wafer scale fabrication processes, such as a circular silicon wafer, a glass substrate, etc.). In other words, multiple portions may be fabricated on a wafer (e.g., the first portions on a first wafer and the second portions on a second wafer). As such, the fabrication of each of the portions may be initiated with use of a wafer substrate (e.g., a semiconductor, conductor, or insulator substrate wafer). In one or more embodiments, the wafer substrate is a doped semiconductor wafer substrate (e.g., doped to either a bulk n-type or p-type wafer), such as those used as the base substrate for microelectronic devices (e.g., substrates built in and over using one or more microfabrication process steps such as doping, ion implantation, etching, deposition of various materials, and photolithographic patterning processes). In one or more embodiments, the semiconductor wafer is a silicon wafer. However, other available types of semiconductor wafers may be used, such as, for example, a gallium arsenide wafer, a germanium wafer, a silicon on insulator (SOI) wafer, etc. Further, for example, in one or more embodiments, the substrate may be formed of one or more materials other than semiconductor material, such as a glass substrate, wherein the substrate includes a metal film. In other words, for example, the first portion20may include a substrate provided from or as a part of a wafer and the second portion40may include a substrate provided from or as a part of a wafer (see, e.g.,FIGS. 2-3).

In one or more embodiments, the first portion20and the second portion40may include one or more layers (see, e.g.,FIGS. 2-3) formed on a substrate (e.g., directly on a semiconductor substrate) terminating at the connection surfaces26,46, respectively. The one or more layers may include the one or more circuit devices90and/or the first and the second chain-structure portions110,120forming the testing structure100. Such layers are described herein with further detail in reference toFIGS. 2-3.

The first portion20and the second portion40may further include one or more contact pads30,50, respectively, electrically coupled to the one or more circuit devices90using one or more interconnects32,52(represented schematically with dashed lines) and located at the connection surfaces26,46. When the first portion20is assembled with the second portion40, the contact pads30,50are electrically coupled such that the one or more circuit devices90are electrically coupled. Further, although not depicted, the apparatus10(e.g., the first portion20and/or the second portion40) may include one or more additional interconnects extending between the circuit devices90and an outer surface of the apparatus10.

As described herein, one or both of the first portion20and the second portion40may define a cavity within which the one or more circuit devices90may be located. In this embodiment, the one or more circuit devices90may be directly electrically coupled to the one or more contacts pads30,50without the use of interconnects (e.g., interconnects32,52). For example, at least in one embodiment, the second portion40defines a cavity extending into the connection surface46. A circuit device90may be located within the cavity and electrically coupled to the contact pads30of the first portion20.

At least in one embodiment, connection surface26, which may be defined at least partly by one or more layers, may include oxide material. For example, such oxide material may be oxide material formed, deposited or grown as part of one or more processing steps (e.g., oxides such as BPSG, silicon oxide, native oxide, etc.).

The one or more circuit devices90, the first and the second chain-structure portions110,120, the one or more interconnects32,52, and the one or more contact pads30,50may be formed using standard microelectronic fabrication processing techniques (e.g., such as etching of materials, deposition of materials, and photolithographic patterning process steps, etc.). Various portions of first and second portions20,40may be formed during the same or different processing steps. For example, a portion of an interconnect that may be used to provide a portion of first chain-structure portion110may be formed within layer used to provide a portion of the interconnect32or contact pad30. The present disclosure is not limited to any particular processing, or timing or order, of such process steps. However, some types of processing and order thereof may be beneficial over other types.

To form the apparatus10, the first portion20and the second portion40are coupled together. For example, in one or more embodiments, the connection surfaces26,46may be coupled (e.g., using plasma-enhanced bonding) together to assemble the apparatus10and to form interface82. In one or more embodiments, bonding the first and second portions20,40together to assemble the apparatus10may be implemented using any wafer and/or die bonding process (e.g., bonding a wafer including the first portions with a wafer including the second portions, which also refers to the bonding of an individual die to a full wafer and the bonding of an individual die to another individual die), such as chemical bonding processes (e.g., those using adhesion promoters, etc.), high temperature bonding processes (e.g., thermal fusion bonding, etc.), hydrogen bonding processes, anodic bonding processes, and oxide bonding processes (e.g., plasma enhanced bonding, etc.). For example, use of oxide bonding permits oxide surfaces (e.g., portions of the connection surfaces26,46of the first and second portions20,40including an oxide material, such as silicon oxide) to be bonded together. Further, for example, in one or more embodiments, the connection surfaces26,46may be chemical mechanically polished or planarized to expose any conductive portions thereof (e.g., the contact pads30,50at connection surfaces26,46) to be exposed. For example, when the oxide portions and the conductive portions (e.g., the first chain-structure portion110or contact pads30) located at the connection surface26(e.g., a planar surface) are aligned with the oxide portions and the conductive portions (e.g., the first chain-structure portion110or contact pads50) located at the connection surface46(e.g., a planar surface), oxide bonding may be performed. For example, oxide bonding processes may form a bond between oxide portions of the connection surfaces26,46of the first and second portions20,40without the need for adhesives or other intermediate layers may be used.

FIG. 2is a schematic cross-sectional side view of one exemplary embodiment of an apparatus201that includes a first portion220bonded to a second portion240. The first portion220includes a substrate222and the second portion240also includes a substrate242. Substrates222,242may be provided from or as a part of a wafer (e.g., a doped or an undoped silicon wafer, or an insulating wafer such as glass or plastic).

The first portion220includes one or more layers224formed on the substrate222terminating at a substantially planar connection surface226that is orthogonal to axis203. In this embodiment, the first portion220is larger than the second portion240such that, when bonded together, regions of the connection surface226are exposed, e.g., to provide contact pads for connections outside of the apparatus201. In other embodiments, the first portion220and the second portion240may be any size relative to each so as to provide suitable functionality to the apparatus201.

The second portion240also includes one or more layers244formed on the substrate242terminating at a substantially planar connection surface246that is orthogonal to axis203. The one or more or layers224,244of either portion220,240may also provide one or more circuit devices290arranged along axis203. Further, the one or more layers224,244of either portion220,240may include any number of layers desired for providing one or more electrical interconnects (although not shown) extending from the one or more circuit devices290to each other or to any location within or outside of the apparatus201. Still further, as described herein, the one or more circuit devices290may be located in a cavity within either of the first portion220or second portion240, and as such, the one or more layers224,244may not need to provide the one or more circuit devices but may still provide the one or more electrical interconnects.

The first portion220includes a first chain-structure portion210and the second portion240includes a second-chain-structure portion230. When the first portion220and the second portion240are coupled as shown inFIG. 2, the first-chain-structure portion210and the second-chain-structure portion230form the testing structure200(e.g., the testing structure200forms a daisy chain strand connection that weaves between the two portions that are bonded together and is located at the interface to be tested). In this embodiment, the testing structure200includes one series circuit203extending from a first end202to a second end204around a hermetically-sealed region280and formed at an interface250(perpendicular to the axis203) of the connection surface226of the first portion220and the connection surface246of the second portion240.

The interface250between the connection surfaces226,246of the first and second portions220,240may include bonded oxide portions in locations other than where conductive elements are located (e.g., such as connection pads212,232of the chain-structure portions210,230described below). For example, such bonded oxide portions may be formed if an oxide bonding process is used to couple the first and second portions220,240.

The one or more layers224of the first portion220include one or more chain-structure segments211that form the first chain-structure portion210and the one or more layers244of the second portion240also include one or more chain-structure segments231that the form the second chain-structure portion230. Each of the one or more chain-structure segments211includes at least two connection pads212located (e.g., exposed) at the connection surface226and at least one electrical interconnect214(represented schematically by dashed lines) electrically coupling the at least two connection pads212. Further, each of the one or more chain-structure segments231also includes at least two connection pads232located (e.g., exposed) at the connection surface246and an electrical interconnect234(represented schematically by dashed lines) electrically coupling the at least two connection pads232.

When the first portion220is coupled to the second portion240(as shown), each connection pad212of the one or more chain-structure segments211of the first portion220is electrically coupled to a connection pad232of the one or more chain-structure segments231of the second portion240to form the testing structure200. In this embodiment, the testing structure200forms a single series circuit203(e.g., a daisy-chain strand connection) extending from a first end202to a second end204around at least a portion of the hermetically-sealed region280and formed at an interface250of the connection surface226of the first portion220and the connection surface246of the second portion240. A first end202of the series circuit203of the testing structure200may be connection pad218of a chain-structure segment211of the first portion220and a second end204of the series circuit203of the testing structure200may be a connection pad216of a chain-structure segment211of the first portion220. The connection pads216,218may be utilized to the test the apparatus100to, e.g., confirm or validate hermeticity about the one or more hermetically-sealed areas280, as described herein with reference toFIGS. 6-7. Although the testing structure200forms a single series circuit203, in other embodiments, the testing structure may include more than one series circuit (see, e.g., testing structure300ofFIG. 3).

As depicted inFIG. 2, the series circuit203only extends around a single side of the hermetically-sealed region280. In one or more embodiments, the series circuits of the testing structures described herein may extend partially around and/or completely around the hermetically-sealed regions and lie along a plane orthogonal to an axis (e.g., axis203). For example, in one embodiment, a series circuit of a testing structure may extend completely around a hermetically-sealed region such that the first end and the second of the series circuit are located next to each other (e.g., completing a loop). Further, in one or more embodiments, a testing structure may include two or more series circuits, each of the two or more series circuits extending partially around the different sides of the hermetically-sealed areas so as when utilized together completely surround the hermetically-sealed areas along a plane orthogonal to the axis (e.g., axis203)/For example, a testing structure may include four series circuits, each of the four series circuits extending along a single different side (i.e., a different side from the other series circuits) of a square hermetically-sealed area. In effect, the four series circuits form a testing structure extending completely around the square hermetically-sealed area.

In at least one embodiment, one or more chain-structure segments may form a testing structure (e.g., including at least one series circuit) within the one or more layers of a single portion so as to, e.g., confirm or validate hermeticity within the one or more layers. Further, the testing structure may extend through more than two layers of the one or more layers of both of the first and the second portion. In such an embodiment, each chain-structure segment may include two or more connection pads and one or more electrical interconnects extending in multiple directions throughout the one or more layers.

Additionally, other functional circuitry may be formed within the one or more layers (e.g., within a circuit device of the one or more circuit devices) and incorporated into the testing structure in order to test the hermeticity of the hermetically-sealed regions. In such an embodiment, the connection pads located at either end of the series circuit for electrically coupling, e.g., to an external apparatus may be unnecessary. For example, such functional circuitry may include voltage or current monitoring devices, frequency sensitive components, etc. In other words, the testing structure and the apparatus to test the electrical circuit apparatus may be self-contained.

FIG. 3depicts an exemplary embodiment of apparatus301including a first portion320and a second portion340that may be similar to the first portion220and the second portion240of the apparatus201described herein with reference toFIG. 2. For example, the first and second portions320,340of the apparatus301may include a substrate322,342, one or more layers324,344terminating in a substantially planar connection surface326,346, one or more circuit devices, one or more chain-structure segments forming at least part of a first and the second chain-structure portion310,330(each chain-structure segment including two connection pads and an electrical interconnect electrically coupling the two connection pads) that may be substantially similar to the substrates222,242, the one or more layers224,244terminating in a substantially planar connection surface226,246, the one or more circuit devices290, and the one or more chain-structure segments211,231forming at least part of a first and the second chain-structure portions210,230(each chain-structure portion including two connection pads212,232and an electrical interconnect214,234electrically coupling the two connection pads) of the first and second portions220,240of the apparatus201described herein with reference toFIG. 2. As such, for simplicity, further detailed description of such features of the first and second portions320,340will not be provided.

In the embodiment depicted inFIG. 3, however, the first portion320and the second portion340are substantially the same size such that no portion of the connection surfaces326,346is exposed. As a result, each of the first portion320and the second portion340includes four interconnects352extending to an outer surface of either the first portion320or the second portion340. In other embodiments, the first and the second portions320,340may include more or less than four interconnects depending on the configuration. The interconnects352are electrically coupled to a testing structure300formed by the first chain-structure portion310of the first portion320and the second chain-structure portion330of the second portion340and extending at least partially around one or more hermetically-sealed portions380.

The testing structure300includes a first series circuit303(extending from a first end304to second end305) and a second series circuit306(extending from a first end307to a second end308) interleaved with each other (e.g., the testing structure300may be a double stranded daisy chain including two or more points to check for connectivity). As used herein, two or more circuits “interleaved with each other” may be defined as having at least a portion of one of the two or more circuits located between a portion of another of the two more circuits. For example, every other connection pad and corresponding interconnect therebetween of each of the first and second portions320,340may form the first series circuit303while the other connection pads and interconnect therebetween of each of the first and second portions320,340form the second series circuit306. In other words, the odd connection pads of the first and second portions320,340may form the first series circuit303and the even connection pads may form the second series circuit306.

As described herein, the testing structure may include more than two series circuits interleaved with each other. For example, every third contact pad may form one series circuit of three series circuits. Further, such interleaved series circuits need not be uniformly arranged. For example, one testing structure may include a first series circuit formed by the first contact pad and every other contact pad thereafter, a second series circuit formed by the second contact pad and every fourth contact pad thereafter, and a third series circuit formed by the fourth contact pad and every fourth contact pad thereafter. Further, such interleaved series circuit configurations may also be described using number sequences. For example, ‘1 ’ could represent a connection pad of a chain-structure portion of a first series circuit, ‘2 ’ could represent a connection pad of a chain-structure portion of a second series circuit, and ‘3 ’ could represent a connection pad of a chain-structure portion of a third series circuit. Using such nomenclature, one configuration of a testing structure may be arranged 1-2-3-1-2-3-1-2-3-1-2-3, another may be arranged 1-1-1-2-2-2-1-1-1-2-2-2-1-1-1, or another may be arranged 1-2-1-2-3-1-2-1-2-3-1-2.

Testing structures including interleaved series circuits, e.g., series circuits303,306, may be utilized for redundancy, multiple tests, locating the site of loss of hermeticity, measuring the rate of loss of hermeticity, measuring the rate of external material penetration (such as moisture), determining the impact of hermeticity loss, etc.

FIG. 4Ais top view of a first portion420andFIG. 4Bis a bottom view of a second portion440of an unassembled exemplary apparatus. In this view, the first chain-structure portion410of the first portion420and the second chain-structure portion430of the second portion440are shown extending around a hermetically-sealed region480. Although not depicted, one or more circuit devices may be located coupled to or as part of one or both of the first portion420and the second portion440. The one or more circuit devices may be arranged along axis402such that the hermetically-sealed region extends a distance further away from the axis402than the one or more circuit devices. Further, in this embodiment, the first chain-structure portion410and the second chain-structure portion430extend around the hermetically-sealed region480and are located a distance further away from the axis402than the one or more circuit devices (not shown) or hermetically-sealed region480. The first portion420includes one or more chain-structure segments411, each including two connection pads412and an electrical interconnect414(represented schematically with dashed lines), forming at least part of the first chain-structure portion410. The second portion440also includes one or more chain-structure segments431, each including two connection pads432and an electrical interconnect434, forming at least part of the second chain-structure portion430. As shown, the connection pads412,432are exposed at the substantially planar connection surfaces426,446of the first and the second portions420,440. When the first portion420and the second portion440are coupled together (e.g., bonded), the connection pads412of the first portion420will be electrically coupled to the connection pads432of the second portion440to complete the at least one series circuit of a testing structure that extends from a first end405to a second end406.

In this embodiment (depicted inFIGS. 4A-4B), the first chain-structure portion410and the second chain-structure portion430extend around a single hermetically-sealed region480that includes most of the area of the first and the second connections surfaces426,446. In other embodiments, the first and the second portions420,440may include more than one hermetically-sealed region that may be smaller and in different shapes than the hermetically-sealed region480.

For example,FIG. 5Ais top view of a first portion520andFIG. 5Bis a bottom view of a second portion540of an unassembled exemplary apparatus that includes a hermetically-sealed region580that is smaller than the hermetically-sealed region480of the first and the second portions420,440as shown inFIGS. 4A-4B. The first portion520includes a first chain-structure portion510and the second portion540includes a second chain-structure portion530that extend around the hermetically-sealed region580.

FIG. 6is a block diagram generally illustrating a method of forming an exemplary apparatus including a hermeticity testing structure such as generally shown inFIGS. 1A-1B. The process600includes providing a first portion (block602), providing a second portion (block604), and providing one or more circuit devices (block606).

Providing the first portion (block602) and providing the second portion (block604) may include fabricating a wafer (e.g., a doped semiconductor wafer) or starting with a pre-fabbed foundry wafer. All of the structures and/or features described herein may be formed within or on such wafers. For example, the first portion20of apparatus10as shown inFIGS. 1A-1Bmay be processed to form the first chain-structure portion110by fabricating (e.g., using any known fabrication processes including deposition, patterning, and/or etching) one or more additional layers on a substrate terminating at the connection surface26.

The first portion20and/or the second portion40may be processed to form the one or more circuit devices in one or both of the first and the second portions (block606) by fabricating (e.g., using any known fabrication processes including deposition, patterning, and/or etching) one or more additional layers on a substrate terminating at the connection surface26. Further, the first portion20and/or the second portion40may be processed to form cavities within which the provided one or more circuit devices (block606) may be located.

The process600further includes bonding (e.g., chemically bonding) the first portion to the second portion (block608). For example, with reference to apparatus10ofFIGS. 1A-1B, the connection surface26of the first portion20may be bonded to the connection surface46of the second portion40such that the connection pads (not shown) of the first and the second chain-structure portions110,120are electrically coupled. In one embodiment, the connection surfaces26,46may be bonded using an oxide bonding process forming an oxide interface therebetween. For example, the connection surfaces26,46may each be etched, polished or planarized (e.g., using a chemical mechanical planarization or polishing) to expose conductive locations (for example, connection pads of the chain-structure portions, connections pads30,50, etc.) on the surfaces26,46but leaving an oxide on the remaining portion of such surfaces26,46. Thereafter, the first portion20may be aligned with the second portion40to, for example, match the plurality of connection pads of the first portion20with the connection pads of the second portion40. An oxide bond may then be performed resulting in bonded oxide portions at the interface of the connection surfaces26,46.

The method presented inFIG. 6is only one example of a method that may be used to implement the apparatus described herein and is not to be taken as limiting to the scope of the disclosure provided herein. Various modifications to the process steps and/or timing or order of the process steps may be made to the method while still providing the benefits of apparatus described herein.

FIG. 7is a block diagram generally illustrating a method700of testing the hermeticity of an exemplary apparatus including a hermeticity testing structure such as generally shown inFIGS. 1A-1B. The hermeticity testing structures as described herein may be utilized to test that the interface between the first portion and the second portion is hermetically sealed (e.g., the testing structures, when electrically probed under different conditions, may produce different results based on whether or not the component is hermetic). For example, the testing structures may test that the first portion and the second portion have adequately, uniformly bonded to form a hermetic seal. Further, for example, the testing structures may test whether moisture has ingressed into the interface between the first and the second portion. Still further, the testing structures may test whether the first portion was properly aligned with the second portion when being assembled (e.g., bonded).

The method700includes providing an electrical circuit apparatus (block702) and testing the testing structure of the electrical circuit apparatus (block704). The testing structure of the electrical circuit apparatus may be tested (block704) multiple ways to confirm or validate hermeticity about one or more hermetically-sealed areas. Two such tests are depicted inside block704.

For example, the method700may include determining if the testing structure is an open circuit (block706). The testing structure may include a series circuit extending from a first end to a second end around one or more hermetically-sealed regions and formed at an interface between the connection surfaces of the first and second portions of an exemplary electrical circuit apparatus, e.g., as depicted generally inFIGS. 1A-1B. At least one technique for determining if the testing structure is an open circuit may be measuring a resistance across the at least one series circuit and comparing the measured resistance to a selected value (e.g., a large resistance value) to determine if the at least one series circuit is complete. If the testing structure is determined to be an open circuit (i.e., an incomplete circuit), then the contact pads of the first portion and the second portion forming part of the testing structure may not be electrically coupled which, e.g., may indicate that the electrical circuit apparatus is not hermetically sealed (e.g., that the first portion and the second portion have not been bonded so as to form one or more hermetically-sealed regions).

Further, for example, the method700may include determining if the testing structure includes a short circuit (block708). The testing structure may include two series circuits interleaved with each other extending around one or more hermetically-sealed regions and formed at an interface between the connection surfaces of the first and second portions of an exemplary electrical circuit apparatus, e.g., as depicted generally inFIGS. 1A-1B. At least one technique for determining if the testing structure includes a short circuit may be applying a voltage across a first series circuit of the at least two series circuits, measuring a voltage across a second series circuit of the at least two series circuits, and comparing the measured voltage across the second series circuit to the applied voltage across the second series circuit to determine if the at least two series circuits are electrically coupled (i.e., short circuited to each other). If the testing structure is determined to include a short circuit (e.g., having a first series circuit electrically coupled to a second series circuit), then moisture may be electrically coupling the first series circuit to the second series circuit which, e.g., may indicate that the hermetically-sealed regions of the apparatus have been compromised by moisture (e.g., the apparatus may have lost hermeticity). Further, if the testing structure is determined to include a short circuit, then the contact pads of the first series circuit forming part of the testing structure may not be electrically coupled and instead may be coupled to the second series circuit which, e.g., may indicate that the electrical circuit apparatus is not hermetically sealed (e.g., that the first portion and the second portion have not been bonded so as to form one or more hermetically-sealed regions).

Any features, components, and/or properties of any of the embodiments described herein may be incorporated into any other embodiment(s) described herein.

All patents, patent documents, and references cited herein are incorporated in their entirety as if each were incorporated separately. This disclosure has been provided with reference to illustrative embodiments and is not meant to be construed in a limiting sense. As described previously, one skilled in the art will recognize that other various illustrative applications may use the techniques as described herein to take advantage of the beneficial characteristics of the apparatus and methods described herein. Various modifications of the illustrative embodiments, as well as additional embodiments of the disclosure, will be apparent upon reference to this description.