Microbattery device and method of manufacturing the same

Abstract

To provide a micro-battery device and a method for manufacturing the same.SOLUTION: A method for manufacturing a micro-battery is provided. The method includes forming a micro-battery device by: forming a first metal anode via and a first metal cathode via in a first substrate; forming a first metal layer on a bottom side of the first substrate; forming a first battery element on a top side of the first substrate; forming an encapsulation layer around the first battery element; forming trenches passing through the encapsulation layer and the first substrate on a plurality of different sides of the first battery element; and forming a metal sealing layer in the trenches so as to cover at least a plurality of sidewall surfaces of the first battery element. Here, the metal sealing layer is electrically connected to the battery element through the first metal layer and the first metal cathode via.SELECTED DRAWING: Figure 1I

Description

[Technical Field]

[0001] The present disclosure relates to microbatteries, and more particularly to hermetic sealing structures (i.e., packaging, particularly hermetic packaging of microbattery devices) for microbatteries using metal seals. [Background technology]

[0002] Hermetic sealing of microbattery devices may be desirable to prevent or minimize the possibility of battery materials leaking outside the battery package. In some microbattery devices, sealing of the microbattery is achieved using polymeric materials, which may not be sufficient to achieve hermeticity. Also, some sealing structures for microbattery devices may include a metallic sealing layer. However, this metallic sealing layer may not hermetically seal all sides of the microbattery device, potentially creating a leakage path from one or more sides of the microbattery device. Additionally, some microbattery devices include an anode and cathode on the same side of the device, which may complicate connecting multiple microbattery devices in parallel or series. Summary of the Invention [Problem to be solved by the invention]

[0003] The present invention aims to provide a microbattery device and a method for manufacturing the same. [Means for solving the problem]

[0004] An embodiment of the present disclosure relates to a method for fabricating a microbattery device, which includes forming a first metal anode via and a first metal cathode via in a first substrate, forming a first metal layer on a bottom side of the first substrate, forming a first battery element on a top side of the first substrate, forming an encapsulation layer around the first battery element, forming trenches through the encapsulation layer and the first substrate on different sides of the first battery element, and forming a metal sealing layer in the trenches to cover at least sidewall surfaces of the first battery element, wherein the metal sealing layer is electrically connected to the battery element through the first metal layer and the first metal cathode via.

[0005] Another embodiment relates to a microbattery apparatus comprising a first microbattery device comprising a first substrate. The first substrate comprises a first metal anode via and a first metal cathode via. The first microbattery device also comprises a first battery element formed on the first substrate, the first battery element comprising a first cathode current collector, a first anode current collector, a first cathode, and a first anode. The first cathode current collector is electrically connected to the first cathode through the first metal cathode via, and the first anode current collector is electrically connected to the first anode through the first metal anode via. A metal sealing layer is formed on at least a sidewall surface of the first battery element, where the metal sealing layer is electrically connected to the first cathode.

[0006] Another embodiment relates to a microbattery apparatus comprising a microbattery device comprising a first substrate, the first substrate comprising a first metal anode via and a first metal cathode via. A first battery element is formed on the first substrate, the first battery element comprising a first cathode current collector, a first anode current collector, a first cathode, and a first anode. The first cathode current collector is electrically connected to the first cathode through the first metal cathode via, and the first anode current collector is electrically connected to the first anode through the first anode via. A second substrate is formed on the first battery element, the second substrate comprising a second metal anode via and a second metal cathode via. A second battery element is formed on the second substrate and includes a second cathode current collector, a second anode current collector, a second cathode, and a second anode. The second cathode current collector is electrically connected to the second cathode through the second cathode via, and the second anode current collector is electrically connected to the second anode through the second anode via. The microbattery device also includes a metal interconnect electrically connecting the first anode to the second anode and a metal sealing layer formed on the sidewall surfaces of the first and second battery elements. The metal sealing layer is electrically connected to the first cathode and the second cathode.

[0007] The above summary is not intended to describe each illustrated embodiment or every implementation of the present disclosure.

[0008] The drawings included in this application are incorporated into and form a part of this specification. The drawings illustrate embodiments of the present disclosure and, together with the detailed description of the invention, explain the principles of the present disclosure. The drawings are only illustrative of certain embodiments and are not intended to limit the disclosure. [Brief explanation of the drawings]

[0009] [Figure 1A]FIG. 1A is a cross-sectional view showing a microbattery device at an intermediate stage in the manufacturing process, according to an embodiment. [Figure 1B] FIG. 1B is a cross-sectional view of the microbattery device of FIG. 1A after further fabrication operations, according to an embodiment. [Figure 1C] FIG. 1C is a cross-sectional view of the microbattery device of FIG. 1B after further fabrication operations, according to an embodiment. [Figure 1D] FIG. 1D is a cross-sectional view of the microbattery device of FIG. 1C after further manufacturing operations, according to an embodiment. [Figure 1E] FIG. 1E is a cross-sectional view of the microbattery device of FIG. 1D after further fabrication operations, according to an embodiment. [Figure 1F] FIG. 1F is a cross-sectional view of the microbattery device of FIG. 1E after further fabrication operations, according to an embodiment. [Figure 1G] FIG. 1G is a cross-sectional view of the microbattery device of FIG. 1F after further fabrication operations, according to an embodiment. [Figure 1H] FIG. 1H is a cross-sectional view of the microbattery device of FIG. 1G after further fabrication operations, according to an embodiment. [Figure 1I] FIG. 1I is a cross-sectional view of the microbattery device of FIG. 1H after further fabrication operations, according to an embodiment. [Figure 1J] FIG. 1J is a cross-sectional view of several microbattery devices of FIG. 1I electrically connected in series, according to an embodiment. [Figure 1K] FIG. 1K is a cross-sectional view of several microbattery devices of FIG. 1I electrically connected in parallel, according to an embodiment. [Figure 2A] FIG. 2A is a cross-sectional view showing a single layer of a multi-layer microbattery device at an intermediate stage in the fabrication process, according to an embodiment. [Figure 2B] FIG. 2B is a cross-sectional view of a multi-layer microbattery device comprising the single layer of FIG. 2A after further fabrication operations, according to an embodiment. [Figure 2C] FIG. 2C is a cross-sectional view of the microbattery device of FIG. 2B after further manufacturing operations, according to an embodiment. [Figure 2D] FIG. 2D is a cross-sectional view of the multilayer microbattery device of FIG. 2C after further fabrication operations, according to an embodiment. [Figure 2E] FIG. 2E is a cross-sectional view of the multilayer microbattery device of FIG. 2D after further fabrication operations, according to an embodiment. [Figure 2F] FIG. 2F is a cross-sectional view of the multilayer microbattery device of FIG. 2E after further fabrication operations, according to an embodiment. [Figure 2G] FIG. 2G is a cross-sectional view of several multi-layered microbattery devices of FIG. 2F electrically connected in series, according to an embodiment. [Figure 3A] FIG. 3A is a cross-sectional view showing a first single layer of a multi-layer microbattery device at an intermediate stage in the manufacturing process, according to an embodiment. [Figure 3B] FIG. 3B is a cross-sectional view of a second single layer of the multi-layer microbattery device of FIG. 3A, according to an embodiment. [Figure 3C] FIG. 3C is a cross-sectional view of the combination of the first and second layers of the microbattery device of FIGS. 3A and 3B after further manufacturing operations, according to an embodiment. [Figure 3D] FIG. 3D is a cross-sectional view of the multilayer microbattery device of FIG. 3C after further fabrication operations, according to an embodiment. [Figure 3E] FIG. 3E is a cross-sectional view of the multilayer microbattery device of FIG. 3D after further fabrication operations, according to an embodiment. [Figure 3F] FIG. 3F is a cross-sectional view of the multilayer microbattery device of FIG. 3E after further fabrication operations, according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] It should be understood that elements in the figures are illustrated for simplicity and clarity, and well-understood elements that may be useful or necessary in a commercially viable embodiment may not be shown for the sake of brevity and to aid in understanding the illustrated embodiment.

[0011] The present disclosure describes embodiments of a microbattery device including a metallic hermetic sealing layer and a method of manufacturing the microbattery device. The drawings in this application are provided for illustrative purposes, and as such, the drawings may not be drawn to scale.

[0012] Various embodiments of the present disclosure are described herein with reference to the associated drawings. Alternative embodiments may be devised without departing from the spirit of the present disclosure. It should be noted that the following specification and drawings illustrate various connections and relationships (e.g., above, below, adjacent, etc.) between elements. These connections or relationships, or combinations thereof, may be direct or indirect unless otherwise specified, and the present disclosure is not intended to be limited in this respect. Thus, joining entities can refer to either direct or indirect joining, and relationships between entities can be direct or indirect relationships. As an example of an indirect relationship, a reference in the detailed description of the invention to forming layer "A" on layer "B" includes the situation where one or more intermediate layers (e.g., layer "C") are present between layer "A" and layer "B," as long as the relevant properties and functions of layer "A" and layer "B" are not substantially altered by the one or more intermediate layers.

[0013] The following definitions and abbreviations will be used for interpreting the claims and the specification. As used herein, the words "comprises," "comprising," "includes," "including," "has," "having," "contains," or "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, mixture, process, method, article, or device that includes a list of elements is not necessarily limited to only those elements, but can include other elements not expressly listed or inherent in such composition, mixture, process, method, article, or device.

[0014] For purposes of the following description, the terms "above," "below," "right," "left," "vertical," "horizontal," "top," "bottom," and their derivatives shall refer to structures and methods described as oriented in the drawings. The terms "above," "atop," "upper," "located on," or "located on" mean that a first element, e.g., a first structure, is located above a second element, e.g., a second structure, where intervening elements, e.g., interface structures, may be located between the first and second elements. The term "directly contact" means that a first element, e.g., a first structure, and a second element, e.g., a second structure, are connected without any intermediate conductive, insulating, or semiconducting layer at the interface between the two elements. It should be noted that the term "selective," e.g., "a first element selective to a second element," means that the first element can be etched and the second element can serve as an etch stop.

[0015] For the sake of brevity, conventional techniques for microbattery devices, or conventional techniques for integrated circuit (IC) manufacturing, or combinations thereof, may or may not be described in detail herein. Moreover, various tasks and process steps described herein may be incorporated into a more comprehensive procedure or process having additional steps or functions not described in detail herein. In particular, the various steps in the manufacture of microbattery devices or ICs, or combinations thereof, are well known, and therefore, for the sake of brevity, many conventional steps will only be briefly mentioned herein or will be omitted entirely, without providing details of the well-known processes.

[0016] Generally, the various processes used to form microbattery devices fall into four general categories: film deposition, removal / etching / laser milling, patterning (laser milling patterning) / lithography, and injection molded soldering (IMS).

[0017] Vapor deposition is any process by which material is grown, coated, or otherwise transferred onto a wafer. Available techniques include physical vapor deposition (PVD), chemical vapor deposition (CVD), electrochemical deposition (ECD), molecular beam epitaxy (MBE), and more recently, atomic layer deposition (ALD), particularly spin-coating. Another deposition technique is plasma-enhanced chemical vapor deposition (PECVD), which uses the energy in a plasma to induce reactions at the wafer surface that would normally require the higher temperatures associated with conventional CVD. Bombarding the wafer with energetic ions during PECVD deposition can also improve the electrical and mechanical properties of the film.

[0018] Removal / etching is any process that removes material from a wafer. Examples include etching processes (either wet or dry), chemical-mechanical planarization (CMP), laser milling, etc. One example of a removal process is ion beam etching (IBE). Generally, IBE (or milling) refers to a dry plasma etching method that utilizes a remote broad-beam ion / plasma source to remove substrate material by physical inert gas means, chemical reactive gas means, or a combination of both. Like other dry plasma etching techniques, IBE offers advantages such as etch rate, anisotropy, selectivity, uniformity, aspect ratio, and minimal substrate damage. Another example of a dry removal process is reactive ion etching (RIE). Generally, RIE uses a chemically reactive plasma to remove material deposited on the wafer. With RIE, plasma is generated under low pressure (vacuum) by an electromagnetic field. High-energy ions from the RIE plasma attack and react with the wafer surface, removing material. Laser milling, or laser beam machining (LBM), is a form of machining in which a laser is directed at a workpiece for machining. This process uses thermal energy to remove material from metallic or non-metallic surfaces. High-frequency monochromatic light at the surface of the object melts and vaporizes the material, allowing selective removal of portions of the object.

[0019] Lithography involves creating a three-dimensional relief image, or pattern, on a substrate and then transferring this pattern into the substrate. In lithography, the pattern is formed using a light-sensitive polymer called a photoresist. The pattern transfer process of lithography and etching is repeated multiple times to build the complex structures that make up electronic devices. Each pattern printed on the wafer is aligned with a previously formed pattern, and conductors, insulators, and other regions are gradually built up to form the final device.

[0020] Turning now to an overview of technologies more specifically related to aspects of the present disclosure, in one embodiment, injection molded solder (IMS) is utilized to form metallic hermetic sealing structures for microbatteries. Generally, IMS refers to a metal deposition process in which molten solder is injected directly into holes (i.e., spaces) (e.g., as patterned in a photoresist mask film), as opposed to conventional electroplating techniques. For example, an IMS deposition head applies molten solder (e.g., SAC305, a lead-free alloy containing 96.5% tin, 3% silver, and 0.5% copper) to one side of a patterned wafer and then scans the other side of the wafer to complete the solder injection into the holes (i.e., spaces).

[0021] 1A-1K of the drawings, where like numbers represent the same or similar elements, and initially referring to FIG. 1A, a cross-sectional view of a portion of a microbattery 100 at an intermediate stage in the fabrication process is shown. As shown in FIG. 1, a bottom substrate, i.e., a first substrate 102, is provided. The first substrate 102 can be a flexible substrate. Vias 104 are formed in the first substrate 102 and then filled with a conductive metal material. An anode current collector 106 is formed over the left one of the vias 104. The anode current collector 106 can be a single layer or multiple layers. In one example, the anode current collector 106 is made of at least one conductive metal material, such as titanium or platinum. In one embodiment of the present application, the anode current collector 106 is made of titanium. In other embodiments, the anode current collector 106 is made of any metal, such as nickel, copper, zinc, etc. The anode current collector can have a thickness of from 10 nm to 20,000 nm, or any other suitable thickness.

[0022] 1B, a first metal layer 108 is formed on the backside (i.e., bottom side) of the first substrate 102. The first metal layer 108 is at least partially on the left side of the first substrate 102, with at least a portion of the first metal layer 108 located to the left of the anode current collector 106. The first metal layer 108 also is on a right portion of the first substrate 102 that is formed in direct contact with a right via of the plurality of vias 104.

[0023] 1C, an anode 110 is also formed on the bottom side of the first substrate 102 and is electrically connected to the anode current collector 106 through a left one of the vias 104. The anode 110 may be a single layer or multiple layers. In one example, the anode 110 is composed of a material stack of a titanium layer, a nickel layer on the surface of the titanium layer, and a zinc layer on the surface of the nickel layer (i.e., a Ti / Ni / Zn stack).

[0024] Referring now to FIG. 1D , the remainder of the microbattery device 100 is assembled. A battery element 112 is formed over the anode current collector 106 and over a portion of the first substrate 102. It should be understood that the battery element 112 can include any suitable number of layers or other battery components. A cathode current collector 114 is formed over the battery element 112 and over a portion of the first substrate 102. In particular, the cathode current collector 114 is in direct contact with the rightmost one of the vias 104, thus creating a conductive path from the cathode current collector 114 to the rightmost one of the vias 104 and to the right portion of the first metal layer 108. An encapsulation layer 116 is formed over the cathode current collector 114 and all other exposed portions of the substrate. In some embodiments, the encapsulation layer 116 is an insulating material. Finally, a second substrate 118 is formed over the encapsulation layer 116. The second substrate 118 may be made of the same material as the first substrate 102, or may be made of a different material and may include several sub-layers. At this stage in the manufacturing process, the left portion of the first metal layer 108 is not electrically connected to any other portion of the microbattery 100 device.

[0025] 1E, an adhesive layer 120 is formed on the bottom side of the first substrate 102, and a handler substrate 122 is stacked on the adhesive layer. Both the adhesive layer 120 and the handler substrate 122 are temporary structures that will facilitate further assembly of the device and will then be removed, as described in detail below.

[0026] Referring now to FIG. 1F, trench 150 is formed, for example, by a laser milling process using first metal layer 108 as a stop layer (i.e., layer removal is stopped when the laser reaches first metal layer 108).

[0027] 1G, a metal seal 124 is formed to fill trench 150 and on top of second substrate 118. Thus, metal seal 124 covers and hermetically seals the entire side of microbattery 100 as well as the top of the device. In one embodiment, metal seal 124 is formed by injection molded soldering (IMS), which is a metal deposition process in which molten solder is injected directly into trench 150. As shown in FIG. 1G, metal seal 124 contacts both the right and left sides of first metal layer 108, thus creating a conductive path from cathode current collector 114 through metal seal 124 to the right side of via 104, to the right side of first metal layer 108, and finally to the left side of first metal layer 108. The cathode can be considered to include both the right and left sides of first metal layer 108 and metal seal 124. Thus, the top portion of metal seal 124 (i.e., the portion covering second substrate 118) functions as the cathode on the top side of microbattery 100, and anode 110 is on the bottom side of microbattery 100. Having a cathode and an anode on opposite sides of microbattery 100 can facilitate less complex series connection of multiple microbatteries 100, as described in more detail below with respect to FIG. 1J, and can also facilitate less complex parallel connection of multiple microbatteries 100, as described in more detail below with respect to FIG. 1K.

[0028] 1H, the handler substrate 122 and adhesive layer 120 are removed, and then a first insulating layer 126 is formed on the bottom side of the first substrate 102. In some embodiments, a laser ablation process or an etching process can be used to remove the adhesive layer 120 and the handler substrate 122. In some embodiments, the first insulating layer 126 can be composed of an insulating polymer material and electrically isolates the anode side of the microbattery 100 from the cathode side of the microbattery 100. For example, the insulating material of the first insulating layer 126 is disposed between the anode 110 and the right portion of the first metal layer 108 (i.e., which can function as part of the cathode). As shown in FIG. 1H, the first insulating layer 126 is formed to be thick enough to cover all of the exposed surface of the first metal layer 108 while still leaving the bottom side of the anode 110 exposed. In some embodiments, the thickness of the anode 110 is greater than the thickness of the first insulating layer 120 .

[0029] Referring now to FIG. 1I, the microbattery 100 structure after singulation is illustrated. Generally, when multiple microbatteries are fabricated on a common substrate, singulation refers to the process of separating or dividing these devices into individual microbatteries. In one embodiment, singulation involves removing portions of the first substrate 102, encapsulation layer 116, second substrate 118, first metal layer 108, and first insulating layer 126 outside (i.e., to the right and left of) the metal seal 124 to prepare the microbattery 100. In one embodiment, a laser milling process can be used to perform the singulation. In another embodiment, sawing is used to separate the individual microbattery 100 devices.

[0030] Referring now to FIG. 1J, three different microbatteries 100-1, 100-2, and 100-3 are shown connected in series. In this example of a series battery connection, the first metal layer 108-1 of microbattery 100-1 may be connected to the anode 110-3 of microbattery 100-3 (not shown). In some embodiments, the anode 110-1 of the first microbattery 100-1 contacts the top portion of the metal seal 124-2 of the second microbattery 100-2. Although not shown in FIG. 1J for simplicity, the same type of series electrical connection occurs between the second microbattery 100-2 and the third microbattery 100-3.

[0031] Referring now to FIG. 1K, three different microbatteries 100-1, 100-2, and 100-3 are shown connected in parallel. In this example of parallel battery connection, the cathode electrical connection can be made through either the first metal layer 108-1 of microbattery 100-1, the first metal layer 108-2 of microbattery 100-2, or the first metal layer 108-3 of microbattery 100-3 (not shown). This is because they are all electrically connected through their respective metal seals 124-1, 124-2, and 124-3. Additionally, electrical connections (not shown) may be required to connect all three anodes 110-1, 110-2, and 110-3 in the parallel battery circuit. In some embodiments, the metal seal 124-1 of the first microbattery 100-1 contacts the left portion of the metal seal 124-2 of the second microbattery 100-2. Although not shown in FIG. 1K for simplicity, the same type of parallel electrical connection occurs between the second microbattery 100-2 and the third microbattery 100-3.

[0032] Referring now to FIGS. 2A-2G, and initially to FIG. 2B, an embodiment of a two-layer integrated solid-state microbattery 250 is shown. The single-layer microbattery 200 shown in FIG. 2A is shown at an intermediate stage in the manufacturing process and is similar in most respects to the microbattery 100 shown in FIG. 1D. Therefore, the description of the manufacturing process of FIGS. 1A-1D will not be repeated for these embodiments. One difference between the microbattery stack 200 of FIG. 2A and the microbattery of FIG. 1D is the absence of the second substrate 118 shown in FIG. 1D. Another difference is the presence of a polymer insulating layer 126 in FIG. 2A. The polymer insulating layer in FIG. 2A may be the same as or similar to the insulating layer 126 shown in FIG. 1H. This somewhat improved structure of the single-layer microbattery stack 200 allows for the connection of two different battery stacks, as described below with respect to FIG. 2B.

[0033] 2B, a first microbattery stack 200-A is bonded with a second microbattery stack 200-B to form a microbattery device 250. The first microbattery stack 200-A includes a first battery stack substrate 102-A, a first battery stack via 104-A, a first battery stack anode current collector 106-A, a first battery stack metal layer 108-A, a first battery stack anode 110-A, a first battery stack battery element 112-A, a first battery stack cathode current collector 114-A, a first battery stack encapsulation layer 116-A, and a first battery stack insulating layer 126-A. Similarly, second microbattery stack 200-B includes second battery stack substrate 102-B, second battery stack via 104-B, second battery stack anode current collector 106-B, second battery stack metal layer 108-B, second battery stack anode 110-B, second battery stack battery element 112-B, second battery stack cathode current collector 114-B, second battery stack encapsulation layer 116-B, and second battery stack insulating layer 126-B.

[0034] As shown in FIG. 2B , the first battery stack 200-A is inverted (i.e., upside down) with respect to the second battery stack 200-B so that the encapsulation layer 116-A of the first battery stack is formed in direct contact with the encapsulation layer 116-B of the second battery stack. However, it should be understood that other layers (e.g., adhesive layers) may be formed between the encapsulation layer 116-A of the first battery stack and the encapsulation layer 116-B of the second battery stack. Moreover, in some embodiments, the metal layer 108-A of the first battery stack is patterned somewhat differently than the metal layer 108-B of the second battery stack. In this regard, there is a first opening 202 in the metal layer 108-A of the first battery stack to allow for a subsequent laser milling operation, as described below with respect to FIG. 2D .

[0035] 2C, a handler substrate 122 is adhered to the second battery stack 200-B by an adhesive layer 120. The handler substrate 122 may be the same type as the substrate described above with respect to the embodiment of FIGS. 1A-1K, or may be a different type.

[0036] 2D , trench 202 is formed, for example, by a laser milling process using second cell stack metal layer 108-B as a stopping layer (i.e., layer removal is stopped when the laser reaches second cell stack metal layer 108-B). It should be understood that because opening 202 is provided in first cell stack metal layer 108-A, first cell stack metal layer 108-A is not an obstacle to the laser milling process. Thus, laser milling removes all of the material from both first cell stack 200-A and second cell stack 200-B down to the horizontal surface of second cell stack metal layer 108-B.

[0037] Referring now to FIG. 2E, a metal seal 204 is formed to fill the trench 202. Thus, the metal seal 204 covers and hermetically seals the entire sides of both the first cell stack 200-A and the second cell stack 200-B. In one embodiment, the metal seal 204 is formed by injection molding solder (IMS), in which molten solder is directly injected into the trench 202. As shown in FIG. 2E, the metal seal 204 provides a conductive path connecting the right side of the metal layer 108-A of the first cell stack with the right side of the metal layer 108-B of the second cell stack. The cathode 108A and the cathode 108B are electrically connected, and the anode 110A and the anode 110B are connected in parallel, where this parallel cell connection example provides increased storage capacity at the same voltage compared to a single cell. Additionally, metal seal 204 provides a conductive path connecting the peripheral / left / anode electrical connection in this example of metal layer 108-A of the first cell stack with the peripheral / left / anode electrical connection of metal layer 108-B of the second cell stack. As also shown in FIG. 2E, a second opening 206 is formed in first cell stack insulating layer 126-A to expose first cell stack anode 110-A.

[0038] 2F, the handler substrate 122 and adhesive layer 120 are removed to expose the anode 110-B of the second battery stack, and singulation is performed to produce individual microbattery 250 devices.

[0039] 2G, three different microbatteries 250-1, 250-2, and 250-3 are shown connected together. Depending on the intended application, the stacked battery structure of two high batteries and the associated interconnections between the batteries may be parallel (e.g., both cathodes connected to an external wire and both anodes connected to an external wire) for the same voltage but with a larger storage capacity, or may be series (e.g., an external wire connected to the cathode of the first battery, the anode of the first battery connected to the cathode of the second battery, and the anode of the second battery connected to an external wire) for the same capacity but with a higher voltage. Similarly, for multiple high batteries, e.g., three or more batteries, the integration and interconnection structures may enable the construction of microbatteries with multiple batteries in parallel, multiple batteries in series, or a combination of series and parallel configurations. In one embodiment, for example, for parallel interconnected battery stacks, the anode 110-B of the battery stack of the first microbattery 250-1 contacts the anode 110-A of the battery stack of the second microbattery 250-2, and the second cathode connection (i.e., the first metal layer 108) of the first microbattery 250-1 contacts the cathode (i.e., the first metal layer 108) of the battery stack of the second microbattery 250-2. Although not shown in FIG. 2G, the same type of parallel electrical connection occurs between the second microbattery 250-2 and the third microbattery 250-3. Alternatively, a serially interconnected stack of microbatteries can be constructed with interconnections from cathode to anode between the first microbattery 250-1 and the second microbattery 250-2, and also from cathode to anode between the second microbattery 250-2 and the third microbattery 250-3.

[0040] 3A-3F, and initially with reference to FIGS. 3A and 3B, embodiments of a two-layer integrated solid-state microbattery are shown. Microbattery stacks 300-A and 300-B, respectively, are shown at intermediate stages in the manufacturing process and are similar in most respects to microbattery 100 shown in FIG. 1C. Accordingly, the description of the manufacturing process of FIGS. 1A-1C will not be repeated for these embodiments. One difference between microbattery stacks 300-A and 300-B and microbattery 100 of FIG. 1C is the different dimensions and relative positions of the anodes and anode current collectors. In particular, anode 110-A of the first cell stack and anode 110-B of the second cell stack are larger than or extend further to the left than the leftmost anode current collector 106-A of the first cell stack and anode current collector 106-B of the second cell stack, respectively, or a combination thereof. This somewhat improved structure of microbattery stacks 300-A and 300-B allows for connecting two different battery stacks, as described below with respect to FIG. 3C. Also shown in FIG. 3B, a metal interconnect 302 is formed through the substrate 102-B of the second battery stack and in contact with the anode 110-B of the second battery stack. Also, the entire metal interconnect 302 is formed toward the left of the leftmost anode current collector 106-A of the first battery stack and the leftmost anode current collector 106-B of the second battery stack. In one aspect, a plurality of the microbattery devices are formed in a two-dimensional array.

[0041] 3C , a first microbattery stack 300-A is bonded with a second microbattery stack 300-B to form a microbattery 350. The first microbattery stack 300-A includes a first battery stack substrate 102-A, a first battery stack via 104-A, a first battery stack anode current collector 106-A, a first battery stack metal layer 108-A, a first battery stack anode 110-A, a first battery stack battery element 112-A, a first battery stack cathode current collector 114-A, a first battery stack encapsulation layer 116-A, and a first battery stack insulating layer 304. Somewhat similarly, the second microbattery stack 200-B includes a second battery stack substrate 102-B, a second battery stack via 104-B, a second battery stack anode current collector 106-B, a second battery stack metal layer 108-B, a second battery stack anode 110-B, a second battery stack battery element 112-B, a second battery stack cathode current collector 114-B, and a second battery stack encapsulation layer 116-B. As also shown in FIG. 3C , a top substrate 306 is formed on the top side of the first battery stack 300-A (i.e., formed on the first battery stack encapsulation layer 116-A). 3B extends all the way to the underside of the anode 110-A of the first cell stack, thereby electrically connecting the anode 110-A of the first cell stack to the anode 110-B of the second cell stack. This configuration allows for stacked microbatteries comprising parallel-connected microbatteries with anode-to-anode and cathode-to-cathode interconnections.

[0042] Although not shown in the drawings, shifting the location of the first metal layer 108, via 104, anode via (i.e., metal interconnect 302), and anode 110 (i.e., pad) in a stack of two or more cells can allow for connection of the anode and cathode in a stack of microbatteries. This type of connection can provide a serially interconnected cell configuration while avoiding contact of the peripheral interconnect electrical interconnect (i.e., from trench 308 to first metal layer 108) by a dielectric layer (or by not connecting the cathode to a metal seal).

[0043] 3D , trench 308 is formed, for example, by a laser milling process that uses metal layer 108-B of the second cell stack as a stop layer (i.e., the laser stops removing the layer once it reaches metal layer 108-B of the second cell stack). Thus, the laser milling removes all of the material of both first cell stack 300-A and second cell stack 300-B down to the horizontal surface of metal layer 108-B of the second cell stack.

[0044] Referring now to FIG. 3E, a metal seal 310 is formed to fill the trench 308 and on top of the top substrate 306. Thus, the metal seal 310 covers and hermetically seals the entire side of the multiple-stack microbattery 350 device, as well as its top. In one embodiment, the metal seal 310 is formed by injection molding solder (IMS), in which molten solder is directly injected into the trench 308. As shown in FIG. 3E, the metal seal 310 contacts both the right and left sides of the metal layer 108-A of the first battery stack and the metal layer 108-B of the second battery stack. Thus, the metal seal 310 electrically connects the cathode current collector 114-A of the first battery stack to the cathode current collector 114-B of the second battery stack. The cathode can be considered to include both the right and left sides of metal layer 108-A of the first battery stack and metal layer 108-B of the second battery stack, as well as metal seal 310. Thus, the top portion of metal seal 310 (i.e., the portion covering top substrate 306) functions as the cathode on the top side of microbattery 350 of the multiple stacks, and the exposed portion of the anode (i.e., anode 110-B of the second battery stack) is on the bottom side of microbattery 350. Having a cathode and an anode on opposite sides of microbattery 350 can facilitate less complex series connection of multiple microbatteries 350, similar to that described in detail with respect to FIG. 1J above.

[0045] 3F, singulation is performed to create a plurality of individual microbatteries 350, and a polymer insulating layer 126-B is provided between the second cell stack anode 110-B and the second cell stack metal layer 108-B to electrically isolate the anode and cathode. The singulation process is similar to that described above with respect to the embodiments of FIGS. 1A-1K and 2A-2G.

[0046] The metal seal of the various embodiments described above provides a hermetic seal for multiple sides (i.e., sidewalls and top side) of the microbattery device. This metal seal packaging allows the battery device to have higher mechanical strength while allowing for smaller seal widths (e.g., less than 30 μm width for the sidewalls of the metal seal). This results in a small form factor relative to existing microbattery devices. Furthermore, by providing the anode and cathode of the microbattery device on different sides (e.g., top and bottom), this allows for simple series / parallel connection of multiple batteries. In addition, the hermetic metal seal may enable a longer shelf life of the microbattery (e.g., less than 3% energy loss per year).

[0047] The description of various embodiments has been presented for purposes of illustration and is not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terms used in this specification have been selected to explain the principles of the embodiments, practical applications or technical improvements to technology found in the market, or to enable those skilled in the art to understand the embodiments disclosed herein. [Explanation of symbols]

[0048] 100 micro batteries 102 first substrate 104 Beer 106 Anode current collector 108 First Metal Layer 110 Anode 112 Battery elements 114 Cathode current collector 116 Encapsulation Layer 118 Second board 124 Metal Seal 126 Insulating Layer

Claims

1. 1. A microbattery apparatus comprising a first microbattery device, the first microbattery device comprising: a first substrate having a first metal anode via and a first metal cathode via; a first battery element formed on the first substrate, wherein the first battery element comprises a first cathode current collector, a first anode current collector, a first cathode, and a first anode, the first cathode current collector being electrically connected to the first cathode through a via in the first metal cathode, and the first anode current collector being electrically connected to the first anode through a via in the first metal anode; a metal sealing layer formed on at least a sidewall surface of the first battery element, wherein the metal sealing layer is electrically connected to the first cathode; Equipped with The microbattery device.

2. The microbattery device of claim 1 , wherein the metal sealing layer is also formed on a top surface of the first battery element.

3. an encapsulation layer covering the first cathode current collector; a second substrate covering the encapsulation layer; and The microbattery device of claim 1 or 2, further comprising:

4. A microbattery device as described in claim 3 when claim 2 is relied upon, wherein the encapsulation layer is formed between the metal sealing layer and the side wall surface of the first battery element, and the second substrate is formed between the metal sealing layer and the top surface of the first battery element.

5. the microbattery apparatus further comprising a second microbattery device; the second microbattery device: a second battery element formed on the first battery element, wherein the second battery element comprises a second cathode current collector, a second anode current collector, a second cathode, and a second anode; a second substrate comprising a second metal anode via and a second metal cathode via, wherein the second cathode current collector is electrically connected to the second cathode through the second cathode via and the second anode current collector is electrically connected to the second anode through the second anode via; It is equipped with the metal sealing layer is formed on the side wall surface of the first battery element and the side wall surface of the second battery element, the metal sealing layer is electrically connected to the first cathode and the second cathode; The microbattery device according to any one of claims 1 to 4.

6. 6. The microbattery device of claim 5, wherein the second battery element is in an opposite orientation relative to the first battery element.

7. The microbattery apparatus of any one of claims 1 to 6, further comprising a plurality of the first microbattery devices connected in series or in parallel.

8. 1. A microbattery apparatus comprising a microbattery device, the microbattery device: a first substrate having a first metal anode via and a first metal cathode via; a first battery element formed on the first substrate, wherein the first battery element comprises a first cathode current collector, a first anode current collector, a first cathode, and a first anode, the first cathode current collector being electrically connected to the first cathode through a via in the first metal cathode, and the first anode current collector being electrically connected to the first anode through a via in the first anode; a second substrate formed on the first battery element, wherein the second substrate comprises a second metal anode via and a second metal cathode via; a second battery element formed on the second substrate, wherein the second battery element comprises a second cathode current collector, a second anode current collector, a second cathode, and a second anode, the second cathode current collector being electrically connected to the second cathode through a via in the second cathode, and the second anode current collector being electrically connected to the second anode through a via in the second anode; a metal interconnect electrically connecting the first anode to the second anode; a metal sealing layer formed on sidewall surfaces of the first and second battery elements, wherein the metal sealing layer is electrically connected to the first cathode and the second cathode; Equipped with The microbattery device.

9. 9. The microbattery device of claim 8, wherein the metal sealing layer is also formed on a top surface of the second battery element.

10. a first encapsulation layer covering the first cathode current collector, and wherein the second substrate is formed on the first encapsulation layer; a second encapsulation layer covering the second cathode current collector; and a third substrate formed on the second encapsulation layer; and 10. The microbattery device of claim 8 or 9, further comprising:

11. The microbattery device according to any one of claims 8 to 10, wherein the second battery element is electrically connected in series with the first battery element.

12. 12. The microbattery apparatus of claim 8, further comprising a plurality of said microbattery devices connected in series or in parallel.

13. 1. A method for manufacturing a microbattery device, comprising: forming a first metal anode via and a first metal cathode via in a first substrate; forming a first metal layer on a bottom side of the first substrate; forming a first battery element on a top side of the first substrate; forming an encapsulation layer around the first battery element; forming trenches through the encapsulation layer and the first substrate on different sides of the first cell element; and forming a metal sealing layer in the trench to cover at least a plurality of sidewall surfaces of the first battery element, wherein the metal sealing layer is electrically connected to the battery element through the first metal layer and the first metal cathode vias; forming a microbattery device by

14. forming the first battery element; forming a first cathode current collector; forming a first cell on the first cathode current collector; forming a first anode current collector on the first cell; Including, the first cathode current collector is electrically connected to the first cathode through the first metal cathode via, and the first anode current collector is electrically connected to the first anode through the first metal anode via; The method of claim 13.

15. 15. The method of claim 13 or 14, wherein the metal sealing layer is also formed on the top surface of the first battery element.

16. 16. The method of claim 15, further comprising electrically connecting a plurality of said microbattery devices in series.

17. 17. The method of claim 16, wherein the plurality of microbattery devices are connected in a stacked configuration.

18. further comprising electrically connecting a plurality of the microbattery devices in parallel; 16. The method of claim 15, wherein the plurality of microbattery devices are connected in a stacked configuration.

19. The method of claim 13 , further comprising forming a plurality of the microbattery devices in a two-dimensional array.

20. 20. The method of claim 19, further comprising separating the microbattery devices from one another by a laser milling singulation process.

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