Patent Description:
The field relates to gas sensor packages.

Gas sensor devices are used in many industries to detect the presence of and to identify gases. For example, in the automotive industry, it can be important to detect and/or identify various types of gases during operation of a vehicle. In petrochemical or other industrial applications, it can also be important to detect and/or identify gases. However, conventional gas sensor devices are expensive, large, and difficult to integrate with surface mount technology. Accordingly, there remains a continuing need for improved gas sensors.

<CIT> discloses an electrochemical sensor including a ceramic substrate, a capillary disposed through the ceramic substrate, a plurality of electrodes disposed on a first surface of the ceramic substrate, an electrolyte disposed over at least a portion of each electrode of the plurality of electrodes, a coating disposed over the plurality of electrodes and the electrolyte, and control and detection circuitry coupled to the substrate.

<CIT> discloses an electrochemical sensor having a lid element comprising a substrate, multiple electrodes, multiple interior contacts electrically coupled to the multiple electrodes, a base element configured to be coupled to the lid element, and an electrolyte element.

According to the invention there is provided a gas sensor package according to the claims.

Embodiments will now be described with reference to the following drawings, which are provided by way of example, and not limitation. <FIG>,<FIG> are not in accord with the present invention.

Various embodiments disclosed herein relate to gas sensor packages. For example, the gas sensor packages disclosed herein can enable sensing devices that are smaller and less expensive than conventional sensors. In various embodiments, the gas sensor packages can comprise a housing defining a first chamber and a second chamber. An electrolyte can be provided in the first chamber. A gas inlet can provide fluid communication between the second chamber and the outside environs. The gas inlet can be configured to permit gas to enter the second chamber from the outside environs. An integrated device die can be mounted to the housing. The integrated device die can comprise an amperometric sensor. The integrated device die can comprise a sensing element configured to detect the gas. The integrated device die can have a first side exposed to the first chamber and a second side exposed to the second chamber. The first side can be opposite the second side.

<FIG> is a schematic side sectional view of a gas sensor package <NUM>, which does not fall under the scope of the invention. The gas sensor package <NUM> can include a housing <NUM> comprising first and second chambers <NUM>, <NUM>, as shown in <FIG>. The housing <NUM> can be defined by a molded package body <NUM> that at least partially delimits the first and/or second chambers <NUM>, <NUM>. For example, as shown in <FIG>, the package body <NUM> can comprise a nonconductive molding compound <NUM>. As shown in <FIG>, the package body <NUM> can comprise a dual-sided construction. A first lid <NUM> can be attached (e.g., by way of thermoplastic welding or joining techniques such as thermocompression bonding) to the package body <NUM> to partially define the first chamber <NUM>. A second lid <NUM> can be attached (e.g., by way of thermoplastic welding or joining techniques such as thermocompression bonding) to the package body <NUM> to partially define the second chamber <NUM>.

An integrated device die <NUM> can be physically mounted to a ledge <NUM> defined in the package body <NUM>. The die <NUM> can be disposed between the first and second chambers <NUM>, <NUM>. A die attach or sealant compound <NUM> can mechanically attach the die <NUM> to the ledge <NUM>. The integrated device die <NUM> can comprise an amperometric sensor. The integrated device die <NUM> can comprise a sensing element <NUM> on a first side <NUM> of the die <NUM>. For example, the sensing element <NUM> can be adhered or laminated to the die <NUM>. In various embodiments, the sensing element <NUM> can comprise platinum black or other types of electrodes used in electrochemical applications. In some embodiments, the sensing element <NUM> can comprise ruthenium black, iridium black, carbon, gold black, or gold. For example, in various embodiments, platinum black can be used for sensing carbon monoxide and hydrocarbons, such as alcohol, etc. In various embodiments, sintered platinum or iridium can be used for sensing hydrogen gas. Gold black may be used to detect sulfur containing compounds, such as hydrogen sulfide. In some embodiments, stabilized iridium may be used to detect gases such as ammonia and hydrazine.

In some embodiments, the sensing element <NUM> can electrically connect to corresponding contact pads (not shown) on the die <NUM>. In other embodiments, the sensing element <NUM> can be formed as part of the die <NUM>. In various embodiments, the sensing element <NUM> can be printed on a sensor part of the die <NUM> over capillaries or channels. In some embodiments, a cap can be attached over the sensing element <NUM>, for example, to protect the sensing element <NUM>. Furthermore, the die <NUM> can comprise other active circuitry and electrical interconnects connecting the active circuitry to the sensing element <NUM> for preprocessing signals detected by the sensing element, in some embodiments. As shown in <FIG>, contact pads on a second side <NUM> of the die <NUM> can electrically connect the active circuitry or the interconnects to leads <NUM> of the package <NUM>, e.g., by way of wire bonds <NUM>. The wire bonds <NUM> may comprise gold or aluminum bonding wires, and may be bonded to the pads of the die <NUM> at room temperature to ensure that temperature limits of the sensing element are not exceeded. An encapsulant <NUM> or glob-top can be applied over the wire bonds <NUM> to protect the wire bonds <NUM> and/or electrically isolate the wire bonds <NUM>. In other embodiments, the die <NUM> can be flip chip mounted to a substrate or package body, e.g., by way of solder balls or anisotropic conductive film (ACF), but such an arrangement may introduce additional costs as compared with wire bonding.

As shown in <FIG>, an electrolyte <NUM> can be provided in the first chamber <NUM> of the package <NUM>. The electrolyte <NUM> can comprise any suitable type of electrolyte for gas sensing applications, including, e.g., acids, such as a solution comprising sulfuric acid (e.g., a <NUM>% sulfuric acid solution), bases, salts, organic electrolytes, gel electrolytes, polymer electrolytes, etc. In other embodiments, the electrolyte <NUM> can comprise other types of liquids (including gels) or solid electrolytes. In various embodiments, a combination of liquid and solid can be used for the electrolyte <NUM>, such as water and a conductive polymer, for example, a sulfonated tetrafluoroethylene based fluoropolymer-copolymer (e.g., Nafion® manufactured by DuPont USA). For example, in some embodiments, the first lid <NUM> can be attached to a lower portion of the package body <NUM> as explained above. The electrolyte <NUM> can be flowed into the first chamber <NUM> by way of an opening <NUM>. A sealing cap <NUM> can be provided over the opening <NUM> to seal the electrolyte <NUM> in the first chamber <NUM>. In <FIG>, the sensing element <NUM> can be exposed to the electrolyte <NUM> (for example, contacting the electrolyte) and/or at least partially disposed in the first chamber <NUM>.

The first chamber <NUM> can also include a wicking material <NUM> to ensure that the electrolyte <NUM> contacts the sensing element <NUM>. The wicking material <NUM> can comprise any suitable type of material, including, for example, a glass fiber matting in the first chamber <NUM>. In various embodiments, the wicking material <NUM> can comprise a discrete component that is provided in the first chamber <NUM>. In some embodiments, the wicking material <NUM> may comprise an open-cell foam that can be dispensed in fluid form to fill the first chamber <NUM>. For example, projections <NUM> shown in <FIG> can cooperate with the wicking material <NUM> to press or draw the electrolyte <NUM> upwards to maintain contact with the sensing element <NUM>. In the absence of the wicking material <NUM>, there may be an air gap below the sensing element <NUM> such that the electrolyte <NUM> does not contact the sensing element <NUM> along its area. The wicking material <NUM> may also prevent splashing of the electrolyte <NUM> during dispensing and capping of the sealing cap <NUM>. Thus, providing the wicking material <NUM> can improve the sensing capabilities of the gas sensor package <NUM> by maintaining contact between the electrolyte <NUM> and the sensing element <NUM>.

The second chamber <NUM> can fluidly communicate with the outside environs by way of a gas inlet <NUM>. As shown in <FIG>, one or more filters <NUM> can be provided across the gas inlet <NUM>. The filter(s) <NUM> can comprise mechanical barriers configured to prevent debris from entering the second chamber <NUM>. In some embodiments, the filter(s) <NUM> can additionally or alternatively be configured to filter out organic compounds or other undesirable contaminants. Two filters <NUM> are illustrated in <FIG>, but any suitable number and type of filters can be provided across the gas inlet <NUM> between the second chamber <NUM> and the outside environs. The filter(s) <NUM> may be provided before or after the second lid <NUM> is attached to the package body <NUM>. The filter(s) <NUM> may be any suitable type of filter, such as a graphite filter, a polytetrafluoroethylene (PTFE) anticondensation filter or dust filter.

During operation, gas(es) can enter the second chamber by way of the gas inlet <NUM> and the filter(s) <NUM>. As shown in <FIG>, the second side <NUM> of the die <NUM> is exposed to the second chamber <NUM> and to the gas(es) entering the second chamber <NUM>. The die <NUM> can comprise one or a plurality of channels <NUM> or capillaries formed through the die <NUM>, e.g., from the second side <NUM> of the die <NUM> exposed to the second chamber <NUM> to the first side <NUM> of the die <NUM> on which the sensing element <NUM> is mounted or otherwise disposed. As shown in <FIG>, the sensing element <NUM> can be disposed on a portion of the first side <NUM> of the die <NUM>, and another portion of the first side <NUM> of the die <NUM> can be exposed to the electrolyte <NUM> in the first chamber <NUM>. The die <NUM>, therefore, can comprise a material resistant to the electrolyte <NUM> (e.g., an acid) such that the electrolyte <NUM> does not damage the die <NUM>. Thus, the first side <NUM> of the die <NUM> can comprise a "wet" side <NUM> of the die <NUM>, and the second side <NUM> of the die <NUM> can comprise a "dry" side <NUM> of the die <NUM>. In various embodiments, the die <NUM> can comprise a semiconductor material such as silicon. Importantly, the die attach material or sealant, in cooperation with the integrated device die <NUM>, can seal and/or fluidly separate the first chamber <NUM> from the second chamber <NUM> such that the electrolyte <NUM> does not enter the second chamber <NUM> from the first chamber <NUM>. The die <NUM> can act as a barrier between the electrolyte <NUM> in the first chamber <NUM> and the gas(es) in the second chamber <NUM>.

Gas passing through the channels <NUM> can contact the dry side <NUM> of the sensing element <NUM> on an opposite side of the wet side <NUM> of the sensing element <NUM>, which contacts the electrolyte <NUM>. In some embodiments, the gas can diffuse into the sensing element <NUM> of the integrated device die <NUM> (e.g., amperometric sensor die) and the integrated device die <NUM> can generate current, for example, as a consequence of chemical reactions of the gas at an interface between the sensing electrode <NUM> and the electrolyte <NUM> in the first chamber <NUM>. A magnitude of the generated current is proportional to a gas concentration near the sensing element <NUM>. Beneficially, the embodiment of <FIG> can enable the production of smallerscale gas sensor packages that are simple and less expensive as compared with conventional gas sensors.

In some embodiments, the die <NUM> can include through substrate vias (TSVs) from the first side <NUM> of the die <NUM> that receives the sensing element <NUM> to the second side <NUM> opposite the first side <NUM>, as illustrated, for example, in <FIG> and <FIG>. The TSVs on the second side can be connected to the wire bonds <NUM> to make electrical connection with the leads <NUM>.

<FIG> is a schematic side cross-sectional view of a gas sensor package <NUM>, which does not fall under the scope of the invention. Unless otherwise noted, the components of <FIG> may be the same as or generally similar to like-referenced components of <FIG>. Further, the package <NUM> may operate generally similar to the package <NUM> of <FIG>, in that gas can enter the gas inlet <NUM> and pass from the second chamber <NUM> and through the channels <NUM> to the first chamber <NUM>. Current generated by the sensor die <NUM> can be measured, and the measured current can be representative of one or more target gas species. For example, as with <FIG>, the gas sensor package <NUM> can comprise a first chamber <NUM> in which an electrolyte <NUM> is disposed and a second chamber <NUM> that fluidly communicates with the outside environs by way of a gas inlet <NUM> and one or more filters <NUM> disposed over the gas inlet <NUM>. Additionally, unlike the embodiment of <FIG>, in which the package body <NUM> and a package lid <NUM> define the first chamber <NUM>, in the embodiment of <FIG>, a die cap <NUM> can be attached to or formed with the integrated device die <NUM>. The die cap <NUM> can define a smaller first chamber <NUM> than in the embodiment of <FIG>, which can beneficially enable a smaller gas sensor package.

In the embodiment of <FIG>, moreover, the package body <NUM> can be molded about the illustrated components by way of film assist molding (FAM), which combines high volume molding processes with the ability to leave an opening <NUM> such as that shown in <FIG>. For example, in some embodiments, the integrated device die <NUM>, the die cap <NUM>, and the leads <NUM> can be molded using FAM, and the opening <NUM> may be left open by providing a tip or insert on the bottom of the die cap <NUM> such that the opening <NUM> is not molded. After molding, the electrolyte <NUM> (e.g., sulfuric acid) can flow through the opening <NUM> and into the first chamber <NUM>. The sealing cap <NUM> (or a sealant or adhesive) can be provided over the opening in the die cap <NUM> to seal the electrolyte <NUM> in the first chamber <NUM>, e.g., by way of a suitable sealant or adhesive. Beneficially, therefore, the gas sensor package <NUM> of <FIG> can utilize low cost molding techniques and materials at any suitable temperature, since the electrolyte <NUM> can be provided after molding, but assembly is simplified by omitting separate lid attachment for the first chamber <NUM>. Moreover, the die <NUM> can be supported by, and at least partially embedded in, the package body <NUM> which may be defined by the molding compound <NUM>. There may be no separate die paddle in various embodiments. For example, as shown in <FIG>, the die <NUM> may be supported by the package body <NUM> and distal portions of the leads <NUM>. The package body <NUM> can at least partially embed end portions of the die <NUM> so as to support the die <NUM>. In some embodiments, the die <NUM> can be adhered to the distal portions of the leads <NUM>. Further, as shown in <FIG>, the molding compound <NUM> can be defined to include recesses for receiving the filter(s) <NUM>. In some embodiments, the filter(s) <NUM> may be flush with or below the top surface of the package body <NUM>. In some embodiments, one or more filter(s) <NUM> may protrude above the top surface of the package body <NUM>.

Further, in embodiment of <FIG>, electrical connections (e.g., the wire bonds <NUM>) between the die <NUM> and the lead <NUM> may be covered with the molding compound <NUM> that at least partially defines the package body <NUM>. Therefore, protection for the wire bonds <NUM> and/or electrical isolation of the wire bonds <NUM> may be provided without the separate encapsulant <NUM> or glob-top shown in <FIG>.

<FIG> is a schematic side cross-sectional view of a gas sensor package <NUM>, which does not fall under the scope of the invention. Unless otherwise noted, the components of <FIG> may be the same as or generally similar to like-referenced components of <FIG>, and may operate or function in a generally similar manner. Unlike the embodiment of <FIG>, in which the sealing cap <NUM> can be applied after filling the first chamber <NUM> with the electrolyte <NUM> either before or after molding, in <FIG>, the electrolyte <NUM> can be provided in the first chamber <NUM> prior to the molding of the package body <NUM>. For example, the first chamber <NUM> defined at least in part by the die cap <NUM> can be filled with the electrolyte <NUM> at the wafer level, and the sealing cap <NUM> can be applied over the opening <NUM> in the die cap <NUM>. The molding compound <NUM> can be provided over the die cap <NUM> and the sealing cap <NUM> in <FIG>. In some embodiments, therefore, the die cap <NUM>, the electrolyte <NUM>, and the sealing cap <NUM> can be applied to a wafer having multiple integrated device regions. The integrated device regions can be singulated to define a plurality of dies with the electrolyte <NUM> provided before singulation. In still other embodiments, the electrolyte <NUM> may be provided in the die cap <NUM> chamber after singulation of the wafer.

<FIG> is a schematic side cross-sectional view of a gas sensor package <NUM>, which is not according to the invention. Unless otherwise noted, the components of <FIG> may be the same as or generally similar to like-referenced components of <FIG>, and may operate or function in a generally similar manner. For example, as with <FIG>, the package of <FIG> can comprise a first chamber <NUM> and a second chamber <NUM> on opposing sides of the integrated device die <NUM>. Moreover, the package <NUM> can comprise a molded package body <NUM> (which may be formed by a FAM technique). The package body <NUM> can be applied over or coupled with a package substrate <NUM>, which may comprise a laminate substrate such as a printed circuit board (PCB) substrate, a ceramic substrate, or any other suitable type of substrate. The package substrate <NUM> can comprise an opening <NUM> that can at least partially define the gas inlet <NUM>. As shown in <FIG>, the opening <NUM> and the gas inlet <NUM> can be disposed on a bottom side <NUM> of the gas sensor package <NUM>. One or more filters <NUM> can be coupled to the package substrate <NUM> over the opening <NUM>. The second chamber <NUM>, which can be in fluid communication with gas(es) in the outside environs by way of the gas inlet <NUM>, can be defined at least in part by the opening <NUM> in the package substrate <NUM>. The integrated device die <NUM> can be disposed over the opening <NUM> and the second chamber <NUM>.

A lid <NUM> can be coupled to or embedded within the package body <NUM>. For example, as explained above, FAM techniques can enable the formation of openings or voids <NUM> in the molding compound <NUM> of the package body <NUM>. The lid <NUM> can be connected to the package body <NUM> within openings or voids defined in the molding compound <NUM>. The lid <NUM> and the package body <NUM> can define an outer chamber <NUM> in which the integrated device die <NUM> is disposed. The die cap <NUM> can be mounted to the integrated device die <NUM> over the sensing element <NUM> to define the first chamber <NUM> in which the electrolyte <NUM> is provided. In some embodiments, the die cap <NUM> can be pre-filled with the electrolyte <NUM>, and the sealing cap <NUM> can seal the first chamber <NUM> of the die cap <NUM> during wafer-level assembly. In other embodiments, the first chamber <NUM> of the die cap <NUM> can be filled with electrolyte <NUM> during packaging, e.g., after the die <NUM> is mounted to the package substrate <NUM> but before application of the lid <NUM>. As with the above embodiments, the integrated device die <NUM> and associated die attach materials or sealants can act as a barrier or seal between the electrolyte <NUM> in the first chamber and the gas(es) in the second chamber <NUM>.

Further, as shown in <FIG>, a second integrated device die <NUM> can be mounted to the package substrate <NUM> and can be laterally offset relative to the integrated device die <NUM> coupled with the sensing element <NUM>. In <FIG>, the second die <NUM> can be embedded in the molding compound of the package body <NUM>, which can beneficially enable standard high temperature packaging and molding techniques. The device die <NUM> and sensing element <NUM> can be packaged in a separate, low temperature packaging stage so as to mitigate damage to the sensing element as a result of high temperature processing. The integrated device die <NUM> can be wire bonded to the substrate <NUM>, and the second integrated device die <NUM> can electrically communicate with the integrated device die <NUM> by way of conductive traces embedded in or on the package substrate <NUM> (e.g., by way of flip-chip or wire bonding interconnections, which are not shown in <FIG>). In various embodiments, the wire bonds <NUM> may be protected by a glob-top or molding material (see, for example, <FIG>). In other embodiments, the wire bonds <NUM> may not be protected by a glob-top or molding material. In some embodiments, the second die <NUM> can process signals transduced by the integrated device die <NUM> with the sensing element <NUM>. Other devices (e.g., passives) can be similarly mounted on the package substrate <NUM> (e.g., laminate substrate) and communicate with the integrated device (sensor) die <NUM> and/or the second integrated device die <NUM> through the the package substrate <NUM> (e.g., laminate substrate) or directly. The packaging substrate <NUM> includes leads <NUM> on the lower surface thereof to facilitate electrical connection to larger electronic systems, e.g., by way of a mother board, such as a printed circuit board, or PCB.

<FIG> is a schematic side cross-sectional view of a gas sensor package <NUM>, according to an embodiment of the invention. Unless otherwise noted, the components of <FIG> may be the same as or generally similar to like-referenced components of <FIG>, and may otherwise operate or function in a generally similar manner. Unlike the embodiment of <FIG>, for example, the gas inlet <NUM> can be provided at the top side of the package <NUM>. The filter(s) <NUM> can be provided over an aperture defined in the molding compound <NUM> (e.g., which may be formed using a FAM technique) and over the gas inlet <NUM>. As shown, the die <NUM> can be mounted to the package substrate <NUM> by way of a die attach material <NUM>. Further, a standoff structure <NUM> can be provided to space the bottom surface of the die <NUM> vertically offset from the top surface of the package substrate <NUM>. Gas can enter the outer chamber <NUM> of the package <NUM> through the gas inlet <NUM> and filters <NUM>, and can pass laterally through lateral channels <NUM> to enter the second chamber <NUM>. Thus, the standoff structure <NUM>, the integrated device die <NUM>, and the package substrate <NUM> can define the second chamber <NUM> in the embodiment of <FIG>, which is in open fluid communication with the outer chamber <NUM>. The lateral channels <NUM> within the standoff structure <NUM> can provide fluid communication between the outer chamber <NUM> and the second chamber <NUM>. In various embodiments, the lateral channels <NUM> can be defined by etching laterally through the standoff structure <NUM> (which may comprise silicon). As with the embodiments described above, the die <NUM>, the die cap <NUM> and the sealing cap <NUM> can define the first chamber <NUM> in which the electrolyte <NUM> is disposed. Thus, in <FIG>, the second chamber <NUM> can be disposed between the die <NUM> and the package substrate <NUM>. The first chamber <NUM> can be disposed between the die <NUM> and the gas inlet <NUM> or filters <NUM>. In some embodiments the lateral channels <NUM> may comprise the second chamber <NUM>.

<FIG> is a schematic side cross-sectional view of a gas sensor package <NUM>, which does not fall under the scope of the invention. Unless otherwise noted, the components of <FIG> may be the same as or generally similar to like-referenced components of <FIG>, and may operate or function in a generally similar manner. As with the embodiment of <FIG>, the gas inlet <NUM> and filter(s) <NUM> can be provided at a top side <NUM> of the package <NUM>. Unlike the embodiment of <FIG>, however, the outer chamber can directly serve as the second chamber <NUM>, and the first chamber <NUM> can be disposed nearer the bottom side <NUM> of the package <NUM>. One or more die supports <NUM> can support the die <NUM> above the package substrate <NUM> to improve the structural support of the die <NUM> during manufacturing and/or use, and to provide a space which can accommodate the thickness of the die cap <NUM> and first chamber <NUM>. As shown in <FIG>, the first chamber <NUM> can be disposed between the die <NUM> and the package substrate <NUM>. As shown in <FIG>, one or more through-silicon vias (TSVs) <NUM> can be provided to provide electrical communication between front and back surfaces of the die <NUM>.

<FIG> is a schematic side cross-sectional view of a gas sensor package <NUM>, which does not fall under the scope of the invention. Unless otherwise noted, the components of <FIG> may be the same as or generally similar to like-referenced components of <FIG>, and may operate or function in a generally similar manner. The package <NUM> of <FIG> may be similar to the package <NUM> shown in <FIG>, e.g., the second chamber <NUM> may be disposed between the die <NUM> and the package substrate <NUM>, or nearer the bottom side <NUM> of the package <NUM>. The first chamber <NUM> and the electrolyte <NUM> may be disposed between the die <NUM> and the gas inlet <NUM>, or nearer the top side <NUM> of the package <NUM>. Unlike the embodiment of <FIG>, however, in <FIG>, the integrated device die <NUM> can be mounted over a die shelf <NUM> defined at least in part by the molding compound <NUM> of the package body <NUM>. As shown in <FIG>, the package body <NUM> can be overmolded over one or more additional integrated device dies and/or other electronic components <NUM> (e.g., passives) to define the die shelf <NUM>. The integrated device die <NUM> with the sensing element <NUM> can be mounted to the die shelf <NUM> over the one or more additional devices or dies <NUM>. The integrated device (sensor) die <NUM> can be electrically connected to the laminate package substrate <NUM>, such as by way of the illustrated bond wires <NUM>, for communication with the embedded dies and/or other electronic components <NUM>.

As with <FIG>, in <FIG>, a standoff structure <NUM> can be provided to vertically offset the die <NUM> relative to the die shelf <NUM>. Lateral channels <NUM> can be defined in the standoff structure <NUM> and/or the die shelf <NUM> during molding to enable fluid communication between the outer chamber <NUM> and the second chamber <NUM>. Thus, gas(es) can enter the outer chamber <NUM> through the gas inlet <NUM> and filter(s) <NUM>. The gas(es) can pass through the lateral channels <NUM> in the standoff structure <NUM> and/or the die shelf <NUM> to enter the second chamber <NUM>. Beneficially, the embodiment of <FIG> can enable a lower package footprint since the integrated device die <NUM> can be stacked on the overmolded additional devices or dies <NUM>.

<FIG> is a schematic side sectional view of a sensor die <NUM> in which a sensor portion <NUM> and a processor portion <NUM> are defined in a common unitary structure. Unless otherwise noted, the components of <FIG> may be the same as or generally similar to like-referenced components of <FIG>. For example, as shown in <FIG>, a sensing element <NUM> can be applied (e.g., printed or otherwise coupled) on the sensor portion <NUM> of the die <NUM> over the gas channels <NUM>. An electrolyte <NUM> can be provided in the first chamber <NUM>. The sensor die <NUM> of <FIG> can be used in conjunction with any of the packages disclosed herein. The sensor portion <NUM> and processor portion <NUM> can be made from the same substrate, e.g., the same wafer. For example, active processing circuitry can be defined in the processor portion <NUM>, and additional routing circuitry can be defined in the sensor portion <NUM>. A lateral chamber <NUM> or channel can be defined between the processor portion <NUM> and the sensor portion <NUM>. The lateral chamber <NUM> or channel can provide a gas inlet for gas to enter the vertical channels <NUM> to interact with the sensing element <NUM>. In some embodiments, the lateral chamber <NUM> can serve as the second chamber <NUM> to provide fluid communication to one side of the sensor portion of the die <NUM>. In other embodiments, a chamber outside of the die <NUM> can serve as the second chamber <NUM>.

In various embodiments, the lateral chamber <NUM> or channel can be defined by etching. For example, a sacrificial material can be deposited on the processor portion <NUM>, and an etchant can be provided through the vertical channels <NUM> to etch the sacrificial material in the lateral chamber <NUM> or channel. The lateral channels <NUM> can be etched by wet etching, dry etching, or any other suitable method. In various embodiments, the sensor die <NUM> may comprise pre-formed channels, and the sensor die <NUM> and an application specific integrated circuit (ASIC) can be stacked together, e.g., by a die attach material. Additional details of the sensor die <NUM> shown in <FIG> may be found throughout U. Patent Publication No. <CIT>.

<FIG> is a schematic side cross-sectional view of a gas sensor package <NUM>, which does not fall under the scope of the invention. Unless otherwise noted, the components of <FIG> may be the same as or generally similar to like-referenced components of <FIG>, and may operate or function in a generally similar manner. In the embodiment of <FIG>, the gas sensor package <NUM> can comprise a package lid <NUM> that at least partially defines the second chamber <NUM> that communicates with the gas inlet <NUM>. As shown in <FIG>, the sensor die <NUM> can be supported by a package substrate <NUM> (e.g., a laminate substrate) by way of intervening die supports <NUM> or dams. The die supports <NUM> or dams can comprise L- or T-shaped structures (e.g., molded dams) to restrict the bleed out of die attach material between the sensor die <NUM> and the package substrate <NUM>, and to provide support to the die <NUM>. However, it should be understood that the die supports <NUM> or dams can comprise other shapes suitable.

The package <NUM> can serve as a laminate-based system-in-package. As above, the electrolyte <NUM> can be provided in the first chamber <NUM> defined at least in part by the die cap <NUM>. The sensor die <NUM> can be inverted in the illustrated embodiment, e.g., to reduce the distance between the gas inlet <NUM> and the sensor die <NUM> and sensing element <NUM>. In the illustrated embodiment, the package lid <NUM> can be provided over the sensor die <NUM> and other dies, packages, and/or passive components <NUM>. The package lid <NUM> can comprise a shaped lid, e.g., with one or more vertical legs <NUM> that support a horizontal upper lid portion <NUM>. One or more filters <NUM> can be coupled to the lid <NUM>. In <FIG>, the filters <NUM> are disposed over the horizontal upper lid portion <NUM> of the package lid <NUM>. However, in some embodiments, the filters <NUM> may be disposed inside the package lid <NUM> (e.g., under the lid portion <NUM>), or both inside and outside of the package lid <NUM> (e.g., over and under the lid portion <NUM>). The gas inlet <NUM> can comprise a port hole formed in the lid <NUM>, e.g., the upper portion of the lid <NUM>.

As explained above, the package lid <NUM> can at least partially define the second chamber <NUM>. In the embodiment of <FIG>, the sensor die <NUM> and other dies, packages, or passive components <NUM>, including processor dies (e.g., ASICs) may also be disposed in the second chamber <NUM> defined at least in part by the lid <NUM>. As explained above, the bonding wires electrically connecting the sensor die <NUM> or other dies, packages, or passive components <NUM> to the package substrate <NUM> may be protected by a polymer or glob-top. In other embodiments, the bonding wires may be exposed to the second chamber <NUM>. In various embodiments, the filters <NUM> can be applied as sheets to the lid <NUM>, and can protrude above the package body or housing <NUM>. The filter(s) <NUM> can be applied to the lid <NUM> before or after attaching the lid <NUM> to the package substrate <NUM>, according to various embodiments. In still other embodiments, the package lid <NUM> can comprise one or more recesses sized and shaped to receive and/or support the filter(s) <NUM>. The filter(s) <NUM> can be compression fit and/or glued to the lid <NUM> to prevent gas leaks. In various embodiments, the filter(s) <NUM> can comprise a hydrophobic and/or dust film to reduce the risks of exposing the package <NUM> to moisture. Further, as shown in <FIG>, one or more through-silicon vias (TSVs) <NUM> can be provided to provide electrical communication between front and back surfaces of the die <NUM>.

<FIG> is a schematic side cross-sectional view of a gas sensor package <NUM>, which does not fall under the scope of the invention. Unless otherwise noted, the components of <FIG> may be the same as or generally similar to like-referenced components of <FIG>, and may operate or function in a generally similar manner. Unlike the embodiment of <FIG>, however, in <FIG>, the lid <NUM> may be disposed over the sensor die <NUM>, but the other dies, packages, and/or passive components <NUM> may be mounted to the package substrate <NUM> and disposed outside the lid <NUM> and the second chamber <NUM>.

<FIG> is a schematic side cross-sectional view of a gas sensor package <NUM>, which does not fall under the scope of the invention. Unless otherwise noted, the components of <FIG> may be the same as or generally similar to like-referenced components of <FIG>, and may operate or function in a generally similar manner. Unlike the embodiments of <FIG>, as shown in <FIG>, the one or more filter(s) <NUM> can be provided on an inner surface of the lid <NUM>, as opposed to on an outer surface of the lid (such as is shown in <FIG>). Furthermore, in the embodiment of <FIG>, the filter(s) <NUM> may contact at least a portion the surface of the sensor die <NUM>. In other embodiments, the lid <NUM> and filter(s) <NUM> may stand off from the sensor die <NUM>, such that the second chamber <NUM> of the package <NUM> may also be defined by the lid <NUM> in a manner similar to that shown in <FIG>. The wire bond <NUM> can make electrical connection between the die <NUM> and the package substrate <NUM>. In some other embodiments, the die supports <NUM> may make electrical connection between the sensor die <NUM> and the substrate <NUM>. In the embodiment of <FIG>, gas can pass through the gas inlet <NUM>, through the gas channels <NUM>, and into the first chamber <NUM>. Current generated by the die <NUM> can be proportional to a gas concentration of the gas, which can be used to identify the gas.

<FIG> is a schematic side cross-sectional view of a gas sensor package <NUM>, according to another embodiment of the invention. <FIG> is a schematic side cross-sectional view of a gas sensor package <NUM>, according to another embodiment of the invention. Unless otherwise noted, the components of <FIG> may be the same as or generally similar to like-referenced components of <FIG>, respectively. For example, in <FIG>, the package lid <NUM> can be provided over the sensor die <NUM> and over other dies (such as Application Specific Integrated Circuit, or ASIC, dies), packages, and/or passive components <NUM>. In <FIG>, the package lid <NUM> can be provided over the sensor die <NUM>, and the other dies (e.g., ASIC die(s)), packages, and/or package components <NUM> can be provided outside the lid <NUM> and the second chamber <NUM>. Unlike in <FIG>, however, in <FIG>, respectively, the sensor die <NUM> can be inverted as compared with <FIG>. As shown in <FIG>, for example, the gas can pass through the gas inlet <NUM> into the second chamber <NUM>. For example, the gas can pass through openings (not shown) in the die support <NUM> or dam to enter the second chamber <NUM>.

Claim 1:
An electrochemical gas sensor package (<NUM>) comprising:
a housing (<NUM>) defined by a lid (<NUM>) or package body (<NUM>) and a package substrate (<NUM>);
an integrated device die (<NUM>) comprising a sensor portion (<NUM>) having a sensing element (<NUM>) configured to detect a gas, and one or more gas channels (<NUM>) formed through the integrated device die, the sensor portion being in fluid communication with the one or more gas channels;
a die cap (<NUM>) mounted to the integrated device die, the die cap at least partially defining a first chamber (<NUM>);
an electrolyte (<NUM>) in the first chamber;
an outer chamber (<NUM>), defined by the housing, the integrated device die mounted to the package substrate (<NUM>) of the housing within the outer chamber using die supports (<NUM>) or standoff structures (<NUM>);
a second chamber (<NUM>), at least partially defined by the package substrate (<NUM>), the die support or standoff structures and the integrated device die, the second chamber being in fluid communication with the outer chamber via openings in the die supports or lateral channels (<NUM>) in the standoff structures, the first chamber being fluidly separate from the second chamber;
a gas inlet (<NUM>) to provide fluid communication between the outer chamber and the outside environs, the gas inlet configured to permit the gas to enter the outer chamber from the outside environs; and
an additional integrated device die (<NUM>) or electronic component mounted to the package substrate;
wherein the sensor portion of the integrated device die has a first side (<NUM>) at least partially exposed to the first chamber and a second side (<NUM>) at least partially exposed to the second chamber, the first side opposite the second side; and
wherein, in use, gas passes from the outside environs through the gas inlet (<NUM>) into the outer chamber (<NUM>), then passes laterally through the openings or channels in the die supports (<NUM>) or support structures (<NUM>) into the second chamber (<NUM>), then through the one or more gas channels (<NUM>) to impinge on the sensing element (<NUM>).