Membrane-based microelectromechanical system (MEMS) device with integrated CMOS circuitry

Abstract

A method of fabricating a MEMS device including a movable microelectromechanical electrostatic component and a CMOS circuit configured in conductive communication with the microelectromechanical component. A plurality of CMOS circuit layers are formed on a substrate to form the CMOS circuit, the plurality of CMOS circuit layers including a plurality of CMOS passivation and metallization layers. Portions of at least one of the plurality of CMOS passivation and metallization layers in a component region of the device are removed. One or more component region layers are formed in place of the removed portions in the component region to form the movable microelectromechanical electrostatic component. The one or more component region layers are different from the portions of the at least one of the plurality of CMOS passivation and metallization layers.

Description

TECHNICAL FIELD

[0001] The present invention relates to a microelectromechanical system, MEMS, device with integrated CMOS circuitry and a method of manufacturing the device. BACKGROUND

[0002] MEMS devices are used in a variety of applications. Typically, the devices contain a MEMS component controlled using a control circuit or interfaced with a sensing circuit. One possible type of MEMS component is an actuator, for example a piezoelectric actuator.

[0003] One application of piezoelectric actuators is for printers, including inkjet printers, piezoelectric actuators are also used in additive manufacturing, textile, biotechnology and pharmaceutical applications. Inkjet printers reconstruct digital images on a print medium, such as paper, by ejecting droplets onto the print medium. Many inkjet printers incorporate “drop-on-demand” technology, in which individual droplets are sequentially ejected from the ink ejection nozzles of a printhead under control. The droplets are ejected with sufficient momentum that they adhere to the medium. Each droplet is ejected in accordance with an applied drive signal, which distinguishes drop-on-demand printers from continuous inkjet devices, in which a continuous stream of droplets is generated by pumping ink through a micro-nozzle.

[0004] A successful drop-on-demand technology is the piezoelectric inkjet printer. Piezoelectric inkjet printers incorporate a piezoelectric actuator into the wall of a fluid chamber. Deformation of the piezoelectric element causes the piezoelectric actuator to deflect, causing a change in pressure in the printing fluid stored within the fluid chamber, thereby causing a droplet to be ejected through a nozzle.

[0005] WO 2018 / 054917 Al relates to a droplet ejector for a printhead, which contains an electronics assembly integrated with a substrate and electrically connected with a first electrode and a second electrode, a piezoelectric actuator being provided between the first electrode and the second electrode. A material forming a nozzle forming layer extends over the electronics assembly and also defines a fluid chamber outlet of a fluid chamber. The piezoelectric actuator covers the nozzle forming layer.

[0006] US 2011 / 0169892 Al relates to a nozzle for an injection-type printer, which includes a top layer defining a nozzle port, a substrate layer defining a nozzle cavity wall that supports the top layer, and an actuator assembly attached to the substrate, the actuator assembly including a support, a lever arm cantilevered from the support to terminate in a piston within the nozzle cavity wall, and a solenoid disposed at an end of the lever arm opposite the end of the piston, the solenoid including a movable magnetic pole and a fixed magnetic pole spaced apart from the movable magnetic pole.

[0007] It is against this background that the present disclosure has been designed. SUMMARY

[0008] According to an aspect of the disclosure, there is provided a method of fabricating a microelectromechanical system, MEMS, device. The MEMS device comprises a microelectromechanical component and an integrated circuit configured in electrically conductive communication with the microelectromechanical component. The method comprises: forming a plurality of integrated circuit layers on a substrate to form the integrated circuit, the plurality of integrated circuit layers comprising a plurality of integrated circuit passivation layers and metallisation layers; removing portions of at least one of the plurality of integrated circuit passivation layers and metallisation layers in a component region of the device; and forming one or more component region layers to replace the removed portions in the component region to form the movable microelectromechanical component, the one or more component region layers being different from the portions of the at least one of the plurality of integrated circuit passivation layers and metallisation layers.

[0009] Thus, the component need not comprise at least some of the integrated circuit layers, which are typically selected for their functionality in the integrated circuit and not for the component, and so the component region layers can be specifically selected to provide the intended properties of the movable microelectromechanical component. Such properties can include Young’s modulus, thickness or density.

[0010] Furthermore, by removing and replacing functionally redundant layers in the component region, the MEMS device can be particularly compact, since the component need not comprise at least some of the redundant layers.

[0011] It will be appreciated that the method typically comprises removing the portions of the at least one of the plurality of integrated circuit passivation layers and metallisation layers precisely. In other words, not all of the at least one layer is removed.

[0012] It will also be appreciated that the integrated circuit layers are layers which provide the integrated circuit for the MEMS device. Similarly, it will be appreciated that the component region layers are any layers which form part of the movable MEMS device, and so do not form part of the integrated circuit of the MEMS device.

[0013] The plurality of integrated circuit layers can be a plurality of CMOS circuit layers.

[0014] Thus, according to another aspect of the disclosure, there is provided a method of fabricating a microelectromechanical system, MEMS, device. The MEMS device typically comprises a movable microelectromechanical component and a CMOS circuit configured in electrically conductive communication with the microelectromechanical component. The method comprises: forming a plurality of CMOS circuit layers on a substrate to form the CMOS circuit, the plurality of CMOS circuit layers comprising a plurality of CMOS circuit passivation layers and metallisation layers; removing portions of at least one of the plurality of CMOS circuit passivation layers and metallisation layers in a component region of the device; and forming one or more component region layers to replace the removed portions in the component region to form the movable microelectromechanical component, the one or more component region layers being different from the portions of the at least one of the plurality of CMOS circuit passivation layers and metallisation layers.

[0015] Accordingly, the component region need not include at least some of the CMOS circuitry layers, which are typically selected for their functionality in CMOS circuitry and not for the component, and thus one or more component region layers can be specifically selected to provide the intended properties of the movable microelectromechanical component. Such properties can include Young's modulus, thickness, or density.

[0016] The one or more component region layers can each have a Young's modulus greater than 10 gigapascals. The one or more component region layers can each have a Young's modulus less than 1,200 gigapascals, such as less than 700 gigapascals.

[0017] In some examples, the one or more component region layers have a stiffness less than (e.g., less than half) the stiffness of the removed portion. In other words, the one or more component region layers are more flexible than the portion they replace. Accordingly, flexibility is enhanced.

[0018] In other examples, the one or more component region layers can have a stiffness greater than (e.g., more than twice) the stiffness of the removed portion. Accordingly, actuation force can be enhanced.

[0019] Further, by removing and replacing redundant layers in the component region, the MEMS device can be particularly compact, as the component need not include at least some of the redundant layers.

[0020] Still further, the method allows for the use of a process with particularly good tolerance control on material properties and thickness to deposit the MEMS passivation feature as one of the component region layers. It will be appreciated that during formation, the CMOS circuitry is subjected to multiple process steps to optimize electrical performance. Such process steps can compromise mechanical and structural aspects important to MEMS functionality. Accordingly, it is beneficial that at least some of the CMOS passivation layers and metallization layers in the component region forming the MEMS component can be removed and replaced. This is particularly important for arrays of multiple MEMS component devices. Accordingly, the method reduces process variation and improves wafer yield.

[0021] It will be appreciated that the multiple integrated circuit passivation layers and metallization layers can together form one or more integrated circuit metallization features within the multiple integrated circuit layers, which are surrounded by integrated circuit passivation regions. Similarly, it will be appreciated that the multiple CMOS passivation layers and metallization layers can together form one or more CMOS metallization features within the multiple CMOS circuit layers, which are surrounded by CMOS passivation regions.

[0022] The multiple CMOS passivation layers and metallization layers can comprise a plurality of CMOS passivation layers and a plurality of CMOS metallization layers.

[0023] The one or more component area layers are at least partially different from a portion of at least one of the one or more CMOS circuit layers.

[0024] The one or more component area layers can be a plurality of at least two different component area layers.

[0025] Metalization in the context of CMOS passivation layers and metalization layers should be understood as essentially any area of an integrated circuit, such as a CMOS circuit, which provides interconnections between components of the integrated circuit, or between the integrated circuit and an external connector of the integrated circuit. The metalization area can be formed of a metal, such as aluminum, copper, an aluminum copper alloy, or any other suitable alloy.

[0026] Passivation in the context of CMOS passivation layers and metalization layers should be understood as essentially any area of an integrated circuit, such as a CMOS circuit, which provides electrical stability to the integrated circuit by isolating one or more components of the integrated circuit, such as a transistor surface, from electrical and / or chemical conditions in the environment. The passivation area can be formed of an insulating material, such as an oxide, a nitride, a carbide, and combinations thereof, such as a laminate thereof.

[0027] The substrate is typically formed of silicon. The substrate can be formed of a silicon wafer.

[0028] It should be understood that the terms "metalization area" and "passivation area" are well known to the person skilled in the art.

[0029] The CMOS circuit typically further comprises a plurality of circuit layers forming a plurality of transistors which together operate to cause the CMOS circuit to act as a control circuit (i.e. a controller). It can be appreciated that a typical manufacturing process for a CMOS metalization layer or a CMOS passivation layer comprises a polishing step to prepare a layer for the application of a further layer thereon. Polishing, sometimes referred to as a chemical mechanical polishing CMP step, is typically not possible in localized sub-areas of a layer having well-defined boundaries only. Therefore, typically the entire layer is polished. For this reason, it should be understood that the CMOS passivation layer and the metalization layer are applied over the entire substrate and must subsequently be removed in any areas of the substrate where the passivation layer and the metalization layer are not required.

[0030] Removing the portion of the at least one of the plurality of CMOS passivation layers and metalization layers in the component area of the device can comprise removing a portion of more than one of the plurality of CMOS passivation layers and metalization layers. Removing the portion of the at least one of the plurality of CMOS passivation layers and metalization layers in the component area of the device can comprise removing a portion of each of the plurality of CMOS passivation layers and metalization layers.

[0031] Thus, no CMOS passivation and metallization layers remain in the component area, and thus the component area of the device can be formed entirely of layers different from the plurality of CMOS passivation and metallization layers.

[0032] Removing portions of at least one of the plurality of CMOS passivation and metallization layers can include etching the layers to be removed. Thus, a simple process commonly used in integrated circuit fabrication can be used to remove the layers.

[0033] The etching can be deep reactive ion etching, DRIE. Alternatively, the etching can be a standard passivation etch to remove one or more passivation regions in the CMOS passivation and metallization layers.

[0034] The etching can be to a location that only partially penetrates through the substrate and the plurality of CMOS passivation and metallization layers.

[0035] The etching can be performed from a side of the component area opposite the substrate. Thus, the etching can remove the plurality of CMOS passivation and metallization layers in the component area up to the substrate.

[0036] At least one of the one or more component area layers can be formed of a different material than an adjacent layer in the plurality of CMOS circuit layers. The adjacent layer can be flush with the at least one of the one or more component area layers. Thus, a different material configuration can be used to achieve different functional characteristics of the one or more component area layers provided in place of the CMOS circuit layers as compared to the plurality of CMOS circuit layers. The material can be different than any of those used for any of the layers in the plurality of CMOS circuit layers.

[0037] In other examples, at least one of the one or more component area layers can be formed to have a different thickness than an adjacent layer in the plurality of CMOS circuit layers. In this case, the at least one of the one or more component area layers can be formed of the same material as the adjacent layer. The at least one of the one or more component area layers can be formed as a single layer or a laminate of different materials.

[0038] Forming the one or more component area layers can include depositing a MEMS passivation layer in place of the removed portions. The MEMS passivation layer can extend over the plurality of CMOS passivation and metallization layers outside of the component area. The MEMS passivation layer can be formed of a different material than the CMOS passivation regions in the plurality of CMOS passivation and metallization layers. In other examples, the MEMS passivation layer can be formed of the same material as the CMOS passivation regions in the plurality of CMOS passivation and metallization layers, or a single layer, or a laminate of different materials, but having a different thickness therefrom. Thus, the MEMS passivation layer is configured to be particularly suitable for structures of microelectromechanical components in the component area.

[0039] The MEMS passivation layer can be a layer that is different from any other component area layer involved functionally during operation of the MEMS component.

[0040] In some instances, the MEMS passivation layer can be formed of a material that is not suitable for use as a CMOS passivation area formed of a plurality of CMOS passivation layers and metallization layers.

[0041] Viewed from another aspect, the disclosure provides a microelectromechanical system, MEMS, device including a substrate having a CMOS circuit provided integrally therewith. The CMOS circuit is formed of a plurality of CMOS circuit layers including a plurality of CMOS passivation layers and metallization layers. The CMOS circuit is disposed in a CMOS circuit area of the MEMS device. The MEMS device further includes a movable microelectromechanical component configured to be controlled by the integrated circuit and disposed in a component area of the MEMS device. The component area is different from the CMOS circuit area. The component area includes one or more component area layers including the microelectromechanical component. The one or more component area layers in the component area or each of the one or more component area layers are different from each of the plurality of CMOS passivation layers and metallization layers of the integrated circuit area.

[0042] Thus, the component is formed of layers that are not selected for their functionality as CMOS passivation layers or CMOS metallization layers of the CMOS circuit.

[0043] The CMOS circuit area can be adjacent to the component area in a direction parallel to a plane of the substrate.

[0044] The substrate can include a first surface having one of the plurality of CMOS passivation layers and metallization layers formed thereon. In the component area, the component area layer can extend coplanar with the first surface.

[0045] One of the one or more component area layers can be a MEMS passivation layer. Thus, the other component area layers can be provided with electrical stability and chemical isolation with respect to the plurality of CMOS passivation layers and metallization layers in the integrated circuit area.

[0046] The one or more component area layers can sometimes be referred to as replacement layers.

[0047] The MEMS passivation layer can overlie the plurality of CMOS passivation layers and metallization layers in the integrated circuit area. Thus, the MEMS passivation layer can provide further electrical isolation and chemical isolation of the CMOS circuit component from the environment.

[0048] The MEMS passivation layer can define an opening therein to provide electrical connection to the plurality of CMOS passivation layers and CMOS metallization regions of the CMOS circuit. The electrical connection can be provided via the MEMS metallization assembly connecting the CMOS metallization regions to at least one of the first and second electrodes of the microelectromechanical assembly.

[0049] The method can include forming an opening in the MEMS passivation layer. The opening can be formed by etching. The etching can be a deep reactive ion etching, DRIE, method or a standard CMOS passivation etching method.

[0050] The MEMS device can include a packaging layer covering the microelectromechanical assembly, the MEMS passivation layer, and the MEMS metallization layer. The method can include forming the packaging layer, e.g., by deposition.

[0051] The substrate can define an opening in its assembly region. The microelectromechanical assembly can include a cantilever extending over the opening. The microelectromechanical assembly can include a diaphragm extending over the opening.

[0052] One or more of the openings described above can have etched sides.

[0053] The method can include forming the opening in the substrate in its assembly region. Thus, when the opening in the substrate is formed in the assembly region, one or more assembly region layers can be released from the substrate in the assembly region, thereby making it easier for them to flex (i.e., move) relative to portions of the device outside the assembly region.

[0054] The opening in the substrate can be formed by etching. The etching can be a deep reactive ion etching, DRIE, method or other method, e.g., anisotropic wet etching.

[0055] The opening in the substrate can be formed from a side of the substrate opposite the microelectromechanical assembly. The opening in the substrate can extend to one or more assembly region layers. The opening in the substrate can extend to the MEMS passivation layer. In this way, when the opening in the substrate is formed by etching, the one or more assembly region layers can be configured to act as an etch stop. In other words, the etching does not typically extend beyond the etch stop.

[0056] The MEMS device can further include a nozzle opening through the MEMS passivation layer and the packaging layer to allow fluid to flow through the opening in the MEMS passivation layer and the packaging layer between a fluid cavity at least partially defined by the substrate and an external environment of the MEMS device.

[0057] The microelectromechanical assembly can be a plurality of microelectromechanical assemblies. Each of the plurality of microelectromechanical assemblies can define a respective nozzle opening in the assembly region. Thus, the MEMS device can include a plurality of nozzle openings. Each of the microelectromechanical assemblies can be electrically connected to the CMOS circuit. Each of the microelectromechanical assemblies can be configured to be controlled by the CMOS circuit. Thus, the plurality of microelectromechanical assemblies can be provided with control by the CMOS circuit.

[0058] The method can further include forming the nozzle opening. The nozzle opening can be formed by etching. The etching can be deep reactive ion etching (DRIE) or other conventional CMOS passivation etching. The nozzle opening can be formed from a side of the MEMS device opposite the substrate.

[0059] In some examples, the nozzle opening can be formed prior to the substrate opening formation. In other examples, the nozzle opening can be formed after the substrate opening formation.

[0060] The microelectromechanical assembly can be a piezoelectric assembly. In other words, the microelectromechanical assembly can include one or more regions of piezoelectric material functionally used in the microelectromechanical assembly.

[0061] The microelectromechanical assembly can be an actuator.

[0062] The actuator can be a piezoelectric actuator.

[0063] The actuator can include a first electrode, a second electrode, and a piezoelectric actuator body disposed between the first electrode and the second electrode. At least one of the first electrode and the second electrode can be electrically connected to the CMOS circuit via one or more of a plurality of CMOS passivation layers and CMOS metallization regions of the plurality of CMOS metallization layers.

[0064] The piezoelectric assembly generally includes a piezoelectric body disposed between a first electrode and a second electrode. At least one of the first electrode and the second electrode is generally electrically connected to at least one electronic assembly (e.g., an electronic assembly of a CMOS circuit). The piezoelectric body generally includes one or more piezoelectric materials (e.g., formed therefrom) that can be processed at temperatures below 450 °C.

[0065] Above 300 °C, integrated electronic assemblies (e.g., CMOS electronic assemblies) generally begin to degrade, impeding device operation and reducing efficiency. Above 450 °C, integrated electronic assemblies (e.g., CMOS electronic assemblies) generally degrade even more severely. Thus, the use of piezoelectric materials that can be processed at temperatures below 450 °C allows for the processing and integration of piezoelectric assemblies with at least one electronic assembly (e.g., an electronic assembly of a drive circuit) without substantially impairing the at least one electronic assembly.

[0066] The piezoelectric body can be formed of one or more piezoelectric materials that can be processed at temperatures below 300°C. The use of piezoelectric materials that can be processed at temperatures below 300°C allows for the processing and integration of the piezoelectric assembly with at least one electronic assembly (e.g., of a drive circuit) with even less damage to the at least one electronic assembly. The use of piezoelectric materials that can be processed at temperatures below 300°C generally allows for higher yields of functional devices from the large-scale fabrication of multiple MEMS devices on a single substrate (e.g., from a single substrate wafer).

[0067] By integrating the piezoelectric assembly with at least one electronic assembly (e.g., of drive electronics), the need to provide separate drive electronics is reduced or eliminated. Thus, a large number of piezoelectric assemblies can be closely integrated on one chip, increasing the number of assemblies per chip, reducing the overall device size, and allowing for higher assembly densities than can be achieved with existing MEMS devices having piezoelectric MEMS assemblies. Other benefits associated with integration on a single chip include reduced manufacturing costs, modularity, and device reliability.

[0068] Piezoelectric materials that can be processed at temperatures below 450°C (or below 300°C) generally have poorer piezoelectric properties (e.g., lower piezoelectric constants) than piezoelectric materials that need to be processed at higher temperatures. For example, a piezoelectric actuator formed of a high-temperature processable piezoelectric material, such as lead zirconate titanate (PZT), is capable of exerting an order of magnitude greater force than a piezoelectric actuator formed of a low-temperature processable piezoelectric material, such as aluminum nitride (AIN), all other factors being equal.

[0069] The one or more piezoelectric materials can generally be processed (e.g., deposited, and if necessary, annealed) at temperatures below 450°C (or below 300°C) so that the piezoelectric assembly can be fabricated at temperatures below 450°C (or below 300°C). Fabrication of the piezoelectric assembly at temperatures below 450°C (or below 300°C) allows for the integration of the piezoelectric assembly with at least one electronic assembly integrated with the substrate.

[0070] Thus, the piezoelectric body can generally be formed (e.g., by depositing one or more piezoelectric materials, and if necessary, annealing them) at temperatures below 450°C (or below 300°C).

[0071] The one or more piezoelectric materials are generally processable (e.g. can be deposited, and if required, annealed) at a substrate temperature of less than 450°C (or less than 300°C). In other words, the temperature of the substrate generally does not reach or exceed 450°C (or 300°C) during processing (e.g. deposition, and if required, annealing) of the one or more piezoelectric materials. The temperature of the substrate generally does not reach or exceed 450°C (or 300°C) during formation of the piezoelectric body. The temperature of the substrate generally does not reach or exceed 450°C (or 300°C) during manufacture of the piezoelectric assembly. It can be that the temperature of the substrate does not reach or exceed 450°C (or 300°C) during (e.g. throughout) manufacture of the MEMS device.

[0072] The piezoelectric body can comprise (e.g. be formed from) one piezoelectric material. Alternatively, the piezoelectric body can comprise (e.g. be formed from) more than one piezoelectric material.

[0073] The piezoelectric body can comprise (e.g. be formed from) a ceramic material comprising aluminium and nitrogen and optionally one or more elements selected from scandium, yttrium, titanium, magnesium, hafnium, zirconium, tin, chromium, boron.

[0074] The piezoelectric body can comprise (e.g. be formed from) aluminium nitride (AIN).

[0075] The piezoelectric body can comprise (e.g. be formed from) zinc oxide (ZnO).

[0076] The one or more piezoelectric materials can comprise (e.g. consist of) aluminium nitride and / or zinc oxide.

[0077] The aluminium nitride can consist of pure aluminium nitride. Alternatively, the aluminium nitride can comprise one or more elements (i.e. the aluminium nitride can comprise an aluminium nitride compound). The aluminium nitride can comprise one or more of the following elements: scandium, yttrium, titanium, magnesium, hafnium, zirconium, tin, chromium, boron.

[0078] The piezoelectric body can comprise (e.g. be formed from) scandium aluminium nitride (ScAIN). The percentage of scandium in the scandium aluminium nitride is generally chosen to optimise the piezoelectric constant d 31 for example, the value of x in Sc x AIN is generally chosen from the range 0 < x < 0.5. A larger fraction of scandium generally results in a d 1-x 31 ​The mass percentage (i.e. weight percentage) of scandium in scandium aluminium nitride is typically greater than 5%. The mass percentage (i.e. weight percentage) of scandium in scandium aluminium nitride is typically greater than 10%. The mass percentage (i.e. weight percentage) of scandium in scandium aluminium nitride is typically greater than 20%. The mass percentage (i.e. weight percentage) of scandium in scandium aluminium nitride is typically greater than 30%. The mass percentage (i.e. weight percentage) of scandium in scandium aluminium nitride is typically greater than 40%. The mass percentage (i.e. weight percentage) of scandium in scandium aluminium nitride can be less than or equal to 50%.

[0079] Aluminium nitride and zinc oxide including aluminium nitride compounds (and in particular scandium aluminium nitride) are piezoelectric materials that can be deposited at less than 450°C, or more preferably at less than 300°C. Aluminium nitride and zinc oxide including aluminium nitride compounds (and in particular scandium aluminium nitride) are piezoelectric materials that can be deposited by physical vapour deposition (e.g. sputtering) at less than 450°C, or more preferably at less than 300°C. Aluminium nitride and zinc oxide including aluminium nitride compounds (and in particular scandium aluminium nitride) are piezoelectric materials that typically do not require annealing after deposition.

[0080] The piezoelectric body can comprise (e.g. be formed from) aluminium nitride (e.g. an aluminium nitride compound such as scandium aluminium nitride) and / or zinc oxide that is deposited by physical vapour deposition at less than 450°C, or more preferably at less than 300°C.

[0081] The piezoelectric body can comprise (e.g. be formed from) one or more III-V semiconductors and / or II-VI semiconductors (i.e. compound semiconductors comprising elements from groups III and V and / or groups II and VI of the periodic table). Such III-V semiconductors and II-VI semiconductors typically crystallise in a wurtzite crystal structure. As III-V semiconductors and II-VI semiconductors that crystallise in a wurtzite crystal structure have a non-centrosymmetric crystal structure, they are typically piezoelectric.

[0082] The piezoelectric body can comprise (e.g. be formed from or consist of) a non-ferroelectric piezoelectric material. The one or more piezoelectric materials can be one or more non-ferroelectric piezoelectric materials. Ferroelectric materials typically require poling (i.e. after deposition) under a strong applied electric field. Non-ferroelectric piezoelectric materials typically do not require poling.

[0083] The piezoelectric body typically has a piezoelectric constant d 31 with a magnitude of less than 30 pC / Newton, or more typically less than 20 pC / Newton, or even more typically less than 10 pC / Newton. The one or more piezoelectric materials typically has a piezoelectric constant d 31 with a magnitude of less than 30 pC / Newton, or more typically less than 20 pC / Newton, or even more typically less than 10 pC / Newton.

[0084] The one or more piezoelectric materials are typically CMOS compatible. Thus, it should be understood that the one or more piezoelectric materials typically do not contain substances that damage CMOS electronic structures, or typically can be processed (e.g., deposited and, if necessary, annealed) without using substances that damage CMOS electronic structures. For example, processing (e.g., depositing and, if necessary, annealing) the one or more piezoelectric materials typically does not include the use of (e.g., strong) acids (e.g., hydrochloric acid) and / or (e.g., strong) bases (e.g., potassium hydroxide).

[0085] It will be appreciated by those skilled in the art that alternative actuator designs are possible, such as multiple actuators with multiple electrodes.

[0086] The method may include depositing a micro-electromechanical component on the MEMS passivation layer. The micro-electromechanical component may be deposited using a physical vapor deposition (PVD) method. Specifically, a piezoelectric actuator body is typically deposited using a physical vapor deposition method.

[0087] The piezoelectric actuator body may comprise one or more PVD-deposited piezoelectric materials.

[0088] The MEMS device may be a droplet ejector for a printhead. Thus, the actuator may be used to eject droplets from the printhead. In other words, the present disclosure may extend to a printhead. The printhead may be an inkjet printhead. The droplet ejector may be a droplet ejector for (e.g., configured for) an inkjet printhead. The droplet ejector may be an ink drop ejector.

[0089] The printhead may be configured to print fluids (eg, functional fluids) for use in fabricating printed electronics.

[0090] The print head can be configured to print biological fluids. Biological fluids typically contain biomacromolecules, such as polynucleotides such as DNA or RNA, microorganisms, and / or enzymes. The print head can be configured to print other fluids for biological or biotechnological applications, such as diluents or reagents.

[0091] The print head may be a voxel print head (ie a print head configured for 3D printing such as additive printing).

[0092] Print heads are commonly used in printers. Accordingly, the present disclosure extends to a printer comprising one or more print heads. It will be appreciated that a printer is essentially any device arranged to expel a printing material (e.g. a printing liquid such as ink) to create an intended appearance (e.g. colour) and / or shape and / or functionality of a printed object. The printer can be a 2D printer arranged to print coloured ink onto a substrate (e.g. paper). In other examples, the printer can be an additive manufacturing device (i.e. a 3D printer) configured to create a 3D object by expelling a printing material from one or more print heads of the printer.

[0093] Accordingly, the present disclosure extends to a printer comprising one or more print heads comprising the MEMS droplet ejector described above, from another aspect. The printer can be configured to eject a printing liquid (e.g. ink) from the MEMS droplet ejector by controlling operation of the MEMS piezoelectric actuator to cause at least one of the one or more component region layers to flex, thereby expelling the printing liquid therefrom. The printer can further comprise a printing liquid source. The printing liquid source can be a printing liquid cartridge.

[0094] The present disclosure also extends to a printing method, from another aspect. The method comprises providing a printing apparatus comprising a printer as described above. The apparatus comprises a printing liquid source. It can be that the printing liquid (e.g. ink) source is part of the printer. The printer comprises one or more print heads, each print head comprising one or more droplet ejectors as described above. The method comprises controlling at least one of the one or more droplet ejectors such that the actuator causes at least one of the one or more component region layers to flex, thereby ejecting a printing liquid from the droplet ejector. Accordingly, the printer prints using the printing liquid.

[0095] The actuator can generate sound, for example for a PMUT or a loudspeaker. The actuator can be used for a fluidic pump.

[0096] The microelectromechanical component can be a sensor component. The sensor component can be a piezoelectric sensor component. In other words, movement of the microelectromechanical component can be converted into an electrical signal which can be conducted to CMOS circuitry. The sensor component can be a microphone, a pressure sensor or a biosensor.

[0097] According to yet another aspect of the disclosure, a microelectromechanical system, MEMS, device is provided, comprising a substrate having a CMOS circuit integrally provided therewith. The CMOS circuit is formed by a plurality of CMOS circuit layers comprising a plurality of CMOS passivation layers and metallization layers, which together define a plurality of CMOS metallization regions surrounded by one or more CMOS passivation regions. The plurality of CMOS passivation layers and metallization layers together extend between a first plane defined by one of the plurality of CMOS passivation layers and metallization layers abutting the substrate, and a second plane parallel to the first plane and defined by a furthest one of the plurality of CMOS passivation layers and metallization layers. The CMOS circuit is disposed in a CMOS circuit region of the MEMS device. The MEMS device further comprises a movable microelectromechanical component configured to be controlled by the integrated circuit and disposed in a component region of the MEMS device. The component region is different from the CMOS circuit region. The component region comprises one or more component region layers comprising the microelectromechanical component. At least one of the one or more component region layers extends to the first plane. The at least one of the one or more component region layers extending to the first plane is different from the one of the plurality of CMOS passivation layers and metallization layers abutting the substrate.

[0098] Thus, in the same plane as the plurality of CMOS passivation layers and metallization layers, a corresponding layer in the component region of the MEMS device is different.

[0099] Typically, the one or more component region layers extending to the first plane are adjacent to the plurality of CMOS passivation layers and metallization layers. The one or more component region layers extending to the first plane can extend from the same side of the substrate as the plurality of CMOS passivation layers and metallization layers. At least one of the one or more component region layers extending to the first plane can extend in a direction from the second plane to the first plane.

[0100] The first plane can be defined as a boundary between the one of the plurality of CMOS passivation layers and metallization layers abutting the substrate and the substrate.

[0101] In some instances, at least one of the one or more component region layers extending to the first plane is formed of a different material than the one of the plurality of CMOS passivation layers and metallization layers abutting the substrate. In other instances, at least one of the one or more component region layers extending to the first plane is formed of a same material as the one of the plurality of CMOS passivation layers and metallization layers abutting the substrate, but having a different thickness therefrom.

[0102] The thickness of the MEMS passivation layer can be less than the combined thickness of the plurality of CMOS passivation layers and metallization layers. Alternatively, the thickness of the MEMS passivation layer can be greater than the combined thickness of the plurality of CMOS passivation layers and metallization layers.

[0103] The MEMS passivation layer can have a substantially similar thickness in the assembly region as in the CMOS circuit region.

[0104] A surface of the MEMS passivation layer facing away from the substrate in the assembly region can be substantially coplanar with a surface of the MEMS passivation layer facing away from the substrate in the CMOS circuit region.

[0105] The MEMS passivation layer can be formed of a plurality of layers. The plurality of layers is formed of at least two different materials.

[0106] The MEMS device can include a plurality of microelectromechanical assemblies disposed outside the CMOS circuit region. The CMOS circuit can be in electrical communication with more than one of the plurality of microelectromechanical assemblies.

[0107] The MEMS device can include a plurality of CMOS circuits disposed outside the assembly region. The plurality of CMOS circuits can comprise a plurality of CMOS circuits of different types. The plurality of CMOS circuits can include at least one HV CMOS circuit and at least one LV CMOS circuit. Additionally or alternatively, the plurality of CMOS circuits can be divided by one or more deep trench isolation (DTI) structures.

[0108] In some examples, each CMOS circuit is in electrical communication with a respective one of the plurality of microelectromechanical assemblies disposed outside the CMOS circuit region.

[0109] The substrate can include one or more bond pads.

[0110] The MEMS device can be configured such that the microelectromechanical assembly is electrically connected to the CMOS circuit via a MEMS metallization layer provided as one of the one or more assembly region layers. BRIEF DESCRIPTION OF DRAWINGS

[0111] Example embodiments of the application will now be described with reference to the following drawings, in which:

[0112] Figure 1 An example of a microelectromechanical system device in the form of a printhead is shown;

[0113] Figure 2 A further example of a microelectromechanical system device is shown;

[0114] Figures 3a to 3f Manufacturing stages of a microelectromechanical system device according to an aspect of the disclosure are shown;

[0115] Figures 4 to 8 A further example of a microelectromechanical system device according to aspects of the disclosure is shown; and

[0116] Figure 9is a flowchart illustrating a method of forming a microelectromechanical system device in accordance with aspects of the present disclosure. DETAILED DESCRIPTION

[0117] Figure 1 A schematic illustration of a microelectromechanical system printhead is shown. The microelectromechanical system (MEMS) printhead 100 is formed with an integrated circuit passivation region 102, in this case in the form of a complementary metal-oxide-semiconductor (CMOS) passivation region 102, surrounding one or more, in this case a plurality, of non-CMOS passivation regions 104, in this case in the form of MEMS passivation regions 104 on a substrate (not shown). It will be appreciated that in other examples, the CMOS passivation region 102 can be in the form of a CMOS dielectric region, and the non-CMOS passivation regions 104 can be in the form of dielectric regions on the substrate. Figure 1 In the view shown, the substrate is hidden by the footprint of the CMOS passivation region 102 and the non-CMOS passivation regions 104. The non-CMOS passivation regions 104 are suitable for having one or more MEMS components disposed thereon.

[0118] In this example, the MEMS printhead 100 further comprises an integrated circuit isolation structure 106, in this case in the form of a CMOS isolation structure 106, surrounding an integrated circuit transistor region 108, in this case in the form of a CMOS transistor region 108. The CMOS isolation structure 106 and the CMOS transistor region 108 are separated from the non-CMOS passivation regions 104 by the CMOS passivation region 102. The MEMS printhead 100 further comprises a bond pad 110 connected to the CMOS via the CMOS passivation region 102. A MEMS metallization line 112 electrically connects the CMOS transistor region 108 to a MEMS component (not shown) in one of the non-CMOS passivation regions 104. In this way, the MEMS component in the non-CMOS passivation region 104 can be controlled by the CMOS transistor region 108 acting as a controller.

[0119] In this example, the CMOS passivation region 102 is formed from a different material to the non-CMOS passivation regions 104, such as the MEMS passivation regions 104. In this way, it will be appreciated that the material used for the non-CMOS passivation regions 104 need not be a material suitable for use in the CMOS passivation region 102, but rather a material selected specifically for its functionality in the MEMS components in the non-CMOS passivation regions 104. In other examples, the CMOS passivation region 102 is formed from the same material as the non-CMOS passivation regions 104, but differs in other respects, such as having a different thickness.

[0120] As described further below, the CMOS passivation region 102 is typically formed by depositing a plurality of layers of deposition material.

[0121] In this example, as will be appreciated by those skilled in the art, the MEMS assembly is typically a piezoelectric actuator, which is controllable to expel drops of ink and act as a microdroplet ejector of an inkjet printhead.

[0122] Figure 2 A further example of a microelectromechanical system device, such as a sensor or actuator, is shown. Similarly to Figure 1 , the MEMS device 200 includes an integrated circuit passivation region 202 in the form of a CMOS passivation region 202, a non-CMOS passivation region 204 surrounded by the CMOS passivation region 202, and a plurality of bond pads 210 disposed in the CMOS passivation region 202. The non-CMOS passivation region 204 includes one or more MEMS assemblies electrically connected to a CMOS chip via metallization connections (not shown) through the CMOS passivation layer region 202. In this example, the MEMS assemblies are sensor assemblies, such as a piezoelectric micromechanical ultrasonic transducer (PMUT), a microphone, or other pressure sensor. In this way, a compact MEMS sensor device can be provided. In other examples, the MEMS assemblies are actuator assemblies, such as for a PMUT, a loudspeaker, or a fluidic pump. As described with reference to Figure 1 , the non-CMOS passivation layer region 204 is formed from a different material to that used to form the CMOS passivation layer region 202, such as a material that is not suitable for use as the CMOS passivation layer region 202.

[0123] As described elsewhere herein, Figure 1 and Figure 2 The example shown can also provide a higher yield process.

[0124] Figure 3a to 3f A stage in the manufacture of a microelectromechanical system device according to an aspect of the disclosure is shown.

[0125] Figure 3a A substrate 320 is shown, provided in the form of a silicon wafer substrate 320, having a first surface 322 and a second surface 324 provided opposite the first surface 322. An integrated circuit substrate region 330 in the form of a CMOS substrate region 330 is provided at the substrate 320, which in this example extends from the first surface 322 into the substrate 320 at a CMOS region 320a of the substrate 320. The CMOS substrate region 330 is typically formed on the substrate by standard CMOS fabrication methods. For example, the integrated CMOS substrate region can be deposited by one or more of the following methods: physical vapour deposition, chemical vapour deposition, electrochemical deposition, molecular beam epitaxy, atomic layer deposition, ion implantation, photopatterning, reactive ion etching, plasma exposure. As described further below with reference to Figures 3c to 3f , the CMOS region 320a is different to a component region 320b of the substrate.

[0126] Then, if Figure 3b As shown, a plurality of CMOS passivation layers and metallization layers 340 covering a CMOS substrate region 330 are formed on a first surface 322 of a substrate 320 to provide electrical stability and chemical isolation from the environment for the CMOS substrate region 330, and also to provide electrical connection to and / or from the CMOS substrate region 330 via metallization interconnects 342. The metallization interconnects 342 are formed of aluminum. In other examples, the metallization interconnects 342 can be formed of other electrical conductors such as copper, aluminum-copper alloys, or other alloying elements. In this example, the metallization interconnects 342 provide a CMOS metallization structure in the plurality of CMOS passivation layers and metallization layers 340. The CMOS substrate region 330 and the plurality of CMOS passivation layers and metallization layers 340 together form a CMOS circuit.

[0127] The plurality of CMOS passivation and metallization layers 340 are formed using any suitable process known to those skilled in the art, such as by deposition and / or micromachining.

[0128] As such, the plurality of CMOS passivation layers and metallization layer 340 together form one or more CMOS metallization features within the plurality of CMOS circuit layers, which are surrounded by a CMOS passivation region.

[0129] Next, portions of the plurality of CMOS passivation layers and metallization layers 340 in the component region 320b of the substrate 320, away from the CMOS region 320a of the substrate 320, are removed. Thus, materials or structures for the plurality of CMOS passivation layers and metallization layers 340 may not be used in association with the component region 320b.

[0130] In this example, the plurality of CMOS passivation layers and metallization layers 340 in the component region 320b are removed by etching, specifically by deep reactive ion etching (DRIE) or conventional CMOS passivation removal methods, while the plurality of CMOS passivation layers and metallization layers 340 in the CMOS region 320a are not removed. In this step, none or substantially none of the substrate 320 is removed. The wall surfaces of the plurality of CMOS passivation layers and metallization layers 340 form an angle of less than 90 degrees with the first surface 322 of the substrate 320, such that the angle between the wall surfaces and the outermost surfaces of the plurality of CMOS passivation layers and metallization layers 340 is an obtuse angle. However, it should be understood that in other examples, this angle may be as high as 90 degrees. In this example, all of the plurality of CMOS passivation layers and metallization layers 340 in the component region 320b are removed. However, it should be understood that in other examples, only some of the plurality of CMOS passivation layers and metallization layers 340 in the component region 320b may be removed.

[0131] After removing the plurality of CMOS passivation and metallization layers 340 in the assembly region 320b, an additional passivation layer 350 is deposited on the assembly, specifically on the remaining portions of the plurality of CMOS passivation and metallization layers 340 outside of the assembly region 320b and on the first surface 322 of the substrate 320 in the assembly region 320b. In this way, the first surface 322 of the substrate 320 has the plurality of CMOS passivation and metallization layers 340 deposited thereon in the CMOS region 320a and has the additional passivation layer 350 deposited thereon in the assembly region 320b. The additional passivation layer 350 is sometimes referred to as a MEMS passivation layer 350. In this example, the additional passivation layer 350 is deposited to have a uniform thickness in a direction normal to the first surface 322 of the substrate 320. In other words, the thickness of the additional passivation layer 350 in the CMOS region 320a is substantially the same as the thickness of the additional passivation layer in the assembly region 320b. The additional passivation layer 350 is formed of a material that is different from any of the plurality of CMOS passivation and metallization layers 340. Specifically, the additional passivation layer 350 is formed of a material selected based on requirements of the structure and function of the MEMS assembly to be disposed in the assembly region 320b of the MEMS device to be formed. The additional passivation layer 350 provides protection, such as electrical and chemical stability, for the assembly of the CMOS substrate region 330 and the plurality of CMOS passivation and metallization layers 340.

[0132] The thickness of the additional passivation layer 350 is typically between 1.0 microns and 10 microns. In this example, the thickness of the additional passivation layer 350 is approximately 2 microns. Additionally, the additional passivation layer 350 typically has a very low Young’s modulus, and thus does not substantially affect operation of the actuator (to be described subsequently).

[0133] Next, a microelectromechanical system (MEMS) assembly 360 in the form of a piezoelectric actuator 360 is deposited on the outer surface 352 of the additional passivation layer 350. In this example, the piezoelectric actuator 360 is formed of a plurality of layers, each of which is deposited individually. The piezoelectric actuator 360 includes a first electrode 362 and a second electrode 364 and a piezoelectric body 366 disposed between the first electrode 362 and the second electrode 364. The piezoelectric body 366 is configured to exhibit piezoelectric behavior when the MEMS device is fully assembled, although it should be understood that the piezoelectric body 366 can be applied after the piezoelectric actuator 360 is initially deposited on the additional passivation layer 350.

[0134] It will be appreciated that the piezoelectric actuator 360 and the further passivation layer 350 must each be formed from a material that can be deposited and for which processing to form the MEMS device is possible under environmental conditions, such as temperature, under which damage to the CMOS substrate region 330 can be reduced or even completely avoided. Suitable such temperatures are below 450 degrees Celsius. A suitable material for the piezoelectric body 366 is aluminium nitride (AIN).

[0135] The piezoelectric actuator 360 is provided with an opening 370 defined therein, which will be described below with reference to Figure 3f Further steps are described with the aim of.

[0136] As Figure 3e illustrated, in this example, portions of the further passivation layer 350 adjacent to the CMOS passivation layer and the metallised interconnect portions 342 in the CMOS region 320a are removed by etching, in particular to expose contact with the metallised interconnect portions 342 adjacent to the further passivation layer 350. The etching is typically a DRIE process or a CMOS passivation etching process. In this way, a recess 375 is defined by the further passivation layer 350. Subsequently, a MEMS metallised interconnect portion 380 is deposited on the further passivation layer 350 between the metallised interconnect portions 342 exposed at the inner end of the recess 375 and at least one of the electrodes 362, 364 of the piezoelectric actuator 360, in this example the first electrode 362. In this way, it will be appreciated that the piezoelectric actuator 360 can be provided with control signals from the CMOS substrate region 330 via the metallised interconnect portions 342, the MEMS metallised interconnect portion 380 and the first electrode 362.

[0137] The MEMS metallised interconnect portion 380 is typically formed from aluminium. In other examples, the MEMS metallised interconnect portion 380 is formed from a different electrical conductor material, such as copper, an aluminium copper alloy or other alloy.

[0138] Next, as Figure 3f illustrated, further steps are completed to provide the MEMS device 300 in the form of the microdroplet ejector 300. The further steps include further deposition of an encapsulation layer 385 that covers the MEMS device 360 in the form of the piezoelectric actuator 360, the MEMS metallised interconnect portion 380 and the further passivation layer 350. The further steps also include a further removal step.

[0139] In this example, a further removal step is performed to define a structural feature of the droplet ejector. Specifically, a nozzle structure 395 is defined by removing material of the further passivation layer 350 in the assembly region 320b. The nozzle structure 395 is arranged to be defined within the opening 370 defined in the piezoelectric actuator 360 and has a width that is less than the width of a fluid cavity 390 (described below).

[0140] Further, the substrate 320 in the assembly region 320b is removed to at least define the region of the fluid cavity 390. The fluid cavity 390 is formed by etching the substrate from the second surface 324 to the first surface 322, wherein the etching terminates at the interface between the substrate and the further passivation layer 350 (or nozzle structure 395). The etching is typically a DRIE process. Thus, the MEMS device 300 is formed.

[0141] As will be appreciated by those skilled in the art, by activating the piezoelectric actuator 360 controlled by the CMOS substrate region 330, one or more fluid droplets provided in the fluid cavity 390 can be controlled to be expelled through the nozzle 395. Of course, the CMOS substrate region 330 can be provided with control signals from a further control circuit via a further electrical connection (not shown). In this example, the fluid cavity 390 is completely filled with fluid in order to operate correctly.

[0142] It will be appreciated that the material used to form the further passivation layer 350 is selected as a fluid resistant agent to ensure that fluid is contained within the cavity 390 and also to ensure consistent droplet directionality. The material of the further passivation layer 350 is typically planarised to provide an optimal surface for printhead maintenance.

[0143] Figures 4 to 8 A further example of a microelectromechanical system device according to aspects of the disclosure is shown. Unless otherwise described, it will be appreciated that, apart from the differences mentioned below, Figures 4 to 8 Features of the shown embodiment of the MEMS device should be understood as being substantially the same as Figures 3a to 3e Features of the shown embodiment of the MEMS device should be understood as being substantially the same as

[0144] Figure 4 A droplet ejector 400 is shown in which a further passivation layer 450 is formed to have a thickness that is less than Figures 3a to 3e The shown thickness.

[0145] Figure 5A droplet ejector 500 is shown in which a further passivation layer 550 is formed such that a first surface 552 of the further passivation layer 550 opposite the substrate 520 has the same vertical distance from the substrate 520 in both the CMOS region 520a and the assembly region 520b. In other words, the thickness of the further passivation layer 550 in the CMOS region 520a is less than the thickness of the further passivation layer 550 in the assembly region. In this way, the connection length through the MEMS passivation layer 550 in the CMOS region 520a can be shorter than the thickness of the MEMS passivation layer 550 in the CMOS region 520a to the same in the assembly region 520b. As a result, electrical connectivity is improved. Furthermore, by ensuring a planar first surface 552 of the further passivation layer 550, maintenance system requirements for printhead wiping and capping are also improved.

[0146] Figure 6 A droplet ejector 600 is shown in which the further passivation layer 650 is a plurality of layers 650a, 650b, 650c. Each of the plurality of layers is typically selected so as to provide the intended structural function for the MEMS assembly in the form of a piezoelectric actuator 660.

[0147] Figure 7 A droplet ejector 700 is shown in which the droplet ejector contains a plurality of MEMS devices 760a, 760b, 760c in the form of a plurality of piezoelectric actuators 760a, 760b, 760c. A first piezoelectric actuator 760a is electrically connected to a CMOS substrate region 730. Each piezoelectric actuator 760a, 760b, 760c is provided with a nozzle. Although not shown, it will be appreciated that typically each piezoelectric actuator 760a, 760b, 760c is electrically connected to the CMOS substrate region 730 such that the CMOS substrate region 730 can be used to control each of the piezoelectric actuators 760a, 760b, 760c.

[0148] Figure 8 A droplet ejector is shown which, although comprising a plurality of CMOS substrate regions 830a, 830b, is similar to the droplet ejector shown in Figure 8. Figure 7 A droplet ejector 800 is shown which is similar to the droplet ejector shown in Figure 8. In this example, a first CMOS substrate region 830a is a low voltage CMOS substrate region 830a and a second CMOS substrate region 830b is a high voltage CMOS substrate region 830b. The low voltage CMOS substrate region 830a is separated (i.e. electrically isolated such as by electrical stabilisation) from the high voltage CMOS substrate region 830b by a deep trench isolation (DTI) feature 835a. A further DTI feature 835b is provided between the high voltage CMOS substrate region 830b and a fluid cavity 890 defined in an assembly region 820b of the substrate 820.

[0149] It should be appreciated that the representations of the MEMS devices shown in the present figures are shown for illustrative purposes only and are not intended to be considered as shown to scale or in proportion.

[0150] Figure 9 is a flowchart illustrating a method of forming a microelectromechanical system device in accordance with aspects of the present disclosure. The method 900 is substantially similar to the method described above with reference to Figures 3a to 3f The method 900 is a method of forming a MEMS device by replacing one or more CMOS passivation layers and / or CMOS metallization layers in a component region of the MEMS device with a MEMS layer. In this way, the MEMS component can be formed of a different material than the material selected for use as the CMOS passivation layer and / or CMOS metallization layer.

[0151] In particular, the method 900 is a method of fabricating a MEMS device that includes a movable microelectromechanical component and a CMOS circuit configured in conductive communication with the microelectromechanical component. The method 900 includes forming 910 a CMOS circuit including a plurality of CMOS passivation layers and a plurality of CMOS metallization layers. Typically, the CMOS circuit is formed to include a plurality of transistors configured such that the CMOS circuit functions as a controller. Electrical signals can be exchanged with the CMOS circuit via the plurality of CMOS metallization layers.

[0152] After forming 910 the CMOS circuit, the method 900 includes removing 920 a portion of at least one of the plurality of CMOS passivation layers and / or the plurality of CMOS metallization layers in a component region of the device. As described above, the portion is typically removed by an etching process such as a DRIE process.

[0153] After removing 920 the portion, the method 900 includes forming 930 one or more component region layers to replace the removed portion. The one or more component region layers are formed in the component region and the movable microelectromechanical component is formed. Importantly, by forming at least one of the one or more component region layers from a different material than the removed portion, the resulting MEMS device can have structural features in the MEMS component that are selected specifically to support the functionality of the MEMS component.

[0154] Optionally, the method 900 further includes etching 940 the substrate in the component region to define a substrate opening therein. Typically, the substrate opening is configured to extend within the substrate to a boundary between the substrate and the one or more component region layers in the component region. In some instances, the etching step is configured to continue through the substrate and terminate at the boundary between the substrate and the one or more component region layers in the component region. In this way, the one or more component region layers in the component region can be released from the substrate, improving their ability to flex.

[0155] In summary, a method (900) of fabricating a microelectromechanical system, MEMS, device is provided. The MEMS device includes a movable microelectromechanical component (360) and CMOS circuitry (330, 340, 342) configured in conductive communication with the microelectromechanical component. The method includes forming (910) a plurality of CMOS circuitry layers (330, 340, 342), one or more of the CMOS circuitry layers including a plurality of CMOS passivation layers and a plurality of CMOS metallization layers (340); removing (920) portions of at least one of the plurality of CMOS passivation layers and / or the plurality of CMOS metallization layers (340) in a component region (320b) of the device; and forming (930) one or more component region layers (350, 352, 364, 366) in the component region to form the movable microelectromechanical component (360). The one or more component region layers are formed from a material different from portions of at least one of the one or more CMOS circuitry layers.

[0156] In the description and claims of the application, the terms "including" and "containing" and variations thereof do not imply that the components, integers or steps recited therein are exclusive or that the methods, processes or compositions consisting solely of these components, integers or steps are complete or entire without additional components, integers or steps. In describing and claiming the present application, unless the context requires otherwise, the singular encompasses the plural and vice versa. Specifically, although the description and claims may use the singular, the use of the singular is intended to be read as incorporating the plural as well as the singular. The use of the singular is thus to be construed as meaning either the singular or the plural, unless it is clear from the context that the singular is intended.

[0157] Features, integers, characteristics or groups described in conjunction with a particular aspect, embodiment or example of the application are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features and / or steps disclosed in the specification (including any accompanying claims, abstract and drawings) can be combined in any combination, provided such features and / or steps are not mutually inconsistent. The application is not limited to the details of any foregoing embodiments. The application extends to any novel one, or any novel combination of the features disclosed in the specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination of the steps of any method or process so disclosed.

Claims

1. A method of manufacturing a micro-electromechanical system (MEMS) device, the MEMS device comprising a movable micro-electromechanical component and a CMOS circuit configured to be in conductive communication with the micro-electromechanical component, the method comprising: forming a plurality of CMOS circuit layers on a substrate to form the CMOS circuit, wherein the plurality of CMOS circuit layers include a plurality of CMOS passivation layers and a metallization layer; removing a portion of at least one of the plurality of CMOS passivation layers and metallization layers in a component area of ​​the device; as well as forming one or more component region layers to replace the removed portion in the component region to form the movable micro-electromechanical component, the one or more component region layers being different from the portion of the at least one of the plurality of CMOS passivation layers and metallization layers, wherein one of the one or more component region layers is a MEMS passivation layer, and The forming of the one or more component region layers includes depositing the microelectromechanical component on the MEMS passivation layer.

2. The method according to claim 1, characterized in that Wherein removing the portion of the at least one of the plurality of CMOS passivation layers and metallization layers includes removing the portion of each of the plurality of CMOS passivation layers and metallization layers in the component area of ​​the device.

3. The method according to claim 1 or claim 2, characterized in that Wherein removing the portion of the at least one of the plurality of CMOS passivation layers and metallization layers comprises etching the layer to be removed.

4. The method according to claim 1, wherein At least one of the one or more component region layers is formed of a material different from an adjacent layer of the plurality of CMOS circuit layers, and the adjacent layer is flush with the at least one of the one or more component region layers.

5. The method according to claim 1, wherein Wherein forming the one or more component region layers includes depositing a MEMS passivation layer to replace the removed portion.

6. The method according to claim 1, characterized in that The micro-electromechanical component is a plurality of micro-electromechanical components, each of the plurality of micro-electromechanical components defines a corresponding nozzle opening in the component area.

7. The method according to claim 6, characterized in that Each of the micro-electromechanical components is electrically connected to and controlled by the CMOS circuit.

8. The method according to claim 1, characterized in that One of the plurality of CMOS passivation layers and metallization layers is formed on a first surface of the substrate, and wherein in the component area, the one or more component area layers extend coplanar with the first surface.

9. The method according to claim 1, characterized in that The substrate defines an opening in the component region, and the micro-electromechanical component includes a cantilever or a membrane extending over the opening.

10. The method according to claim 9, characterized in that The micro-electromechanical component is an actuator.

11. The method according to claim 10, characterized in that The actuator is a piezoelectric actuator.

12. The method according to claim 10 or 11, characterized in that The MEMS device is a droplet ejector for a print head.

13. The method according to claim 1, wherein The one or more component area layers are multiple different component area layers.

14. The method according to claim 1, wherein The micro-electromechanical component is a sensor component.

15. A method of manufacturing a micro-electromechanical system (MEMS) device, the MEMS device comprising a movable micro-electromechanical component and a CMOS circuit configured to be in conductive communication with the micro-electromechanical component, the method comprising: forming a plurality of CMOS circuit layers on a substrate to form the CMOS circuit, wherein the plurality of CMOS circuit layers include a plurality of CMOS passivation layers and a metallization layer; removing a portion of at least one of the plurality of CMOS passivation layers and metallization layers in a component area of ​​the device; as well as forming one or more component region layers to replace the removed portion in the component region to form the movable micro-electromechanical component, the one or more component region layers being different from the portion of the at least one of the plurality of CMOS circuit layers, wherein forming the one or more component region layers comprises depositing a MEMS passivation layer in place of the removed portions, and The MEMS passivation layer covers the multiple CMOS passivation layers and metallization layers in the CMOS circuit area.

16. The method according to claim 15, characterized in that The micro-electromechanical component is a plurality of micro-electromechanical components, each of the plurality of micro-electromechanical components defines a corresponding nozzle opening in the component area.

17. The method according to claim 16, characterized in that Each of the micro-electromechanical components is electrically connected to and controlled by the CMOS circuit.

18. The method according to claim 15, characterized in that One of the plurality of CMOS passivation layers and metallization layers is formed on a first surface of the substrate, and wherein in the component area, the one or more component area layers extend coplanar with the first surface.

19. The method according to claim 15, characterized in that The substrate defines an opening in the component region, and the micro-electromechanical component includes a cantilever or a membrane extending over the opening.

20. The method according to claim 19, wherein The micro-electromechanical component is an actuator.

21. The method according to claim 20, characterized in that The actuator is a piezoelectric actuator.

22. The method according to claim 20 or 21, characterized in that The MEMS device is a droplet ejector for a print head.

23. The method according to claim 15, characterized in that The one or more component area layers are multiple different component area layers.

24. The method according to claim 15, wherein The micro-electromechanical component is a sensor component.

25. A micro-electromechanical system (MEMS) device, comprising: a substrate having a CMOS circuit integrally provided therewith, the CMOS circuit being formed of a plurality of CMOS circuit layers including a plurality of CMOS passivation layers and a metallization layer, and being disposed in a CMOS circuit region of the MEMS device; and a movable microelectromechanical component configured to be controlled by the CMOS circuit and disposed in a component region of the MEMS device, the component region being distinct from the CMOS circuit region, wherein the component area comprises one or more component area layers including the micro-electromechanical component, wherein the one or more component area layers or each of the one or more component area layers in the component area is different from each of the plurality of CMOS passivation layers and metallization layers of the CMOS circuit area, wherein one of the one or more component region layers is a MEMS passivation layer, wherein the MEMS passivation layer covers the multiple CMOS passivation layers and metallization layers in the CMOS circuit area, wherein the micro-electromechanical component is deposited on the MEMS passivation layer, wherein one of the plurality of CMOS passivation layers and metallization layers is formed on the first surface of the substrate, and Wherein in the component area, the one or more component area layers extend to be coplanar with the first surface.

26. The MEMS device according to claim 25, wherein: The micro-electromechanical component is a plurality of micro-electromechanical components, each of the plurality of micro-electromechanical components defines a corresponding nozzle opening in the component area.

27. The MEMS device according to claim 26, wherein: Each of the micro-electromechanical components is electrically connected to and controlled by the CMOS circuit.

28. The MEMS device according to claim 25, wherein: The substrate defines an opening in the component region, and the micro-electromechanical component includes a cantilever or a membrane extending over the opening.

29. The MEMS device according to claim 28, wherein: The micro-electromechanical component is an actuator.

30. The MEMS device according to claim 29, wherein: The actuator is a piezoelectric actuator.

31. The MEMS device according to claim 29 or 30, wherein: The MEMS device is a droplet ejector for a print head.

32. The MEMS device according to claim 25, wherein: The one or more component area layers are multiple different component area layers.

33. The MEMS device according to claim 25, wherein: The micro-electromechanical component is a sensor component.

34. A print head comprising the drop ejector of claim 31.

35. A printer comprising one or more of the printheads of claim 34, wherein the printer is configured to control operation of the actuator of at least one drop ejector to eject printing liquid from the drop ejector.

36. The printer according to claim 35, wherein It further comprises a source of printing liquid.

37. A micro-electromechanical system (MEMS) device comprising: a substrate having a CMOS circuit integrally provided therewith, the CMOS circuit being formed of a plurality of CMOS circuit layers including a plurality of CMOS passivation layers and a metallization layer, and being disposed in a CMOS circuit region of the MEMS device, the plurality of CMOS passivation layers and the metallization layer together extending between a first plane and a second plane, the first plane being defined between the substrate and one of the plurality of CMOS passivation layers and the metallization layer adjacent to the substrate, and the second plane being parallel to the first plane and defined by one of the plurality of CMOS passivation layers and the metallization layer farthest from the substrate; and a movable microelectromechanical component configured to be controlled by the CMOS circuit and disposed in a component region of the MEMS device, the component region being distinct from the CMOS circuit region, wherein the component area comprises one or more component area layers including the micro-electromechanical component, at least one of the one or more component area layers extends to the first plane in a direction from the second plane to the first plane, and wherein said at least one of said one or more component area layers extending to said first plane is formed of a different material than said one of said plurality of CMOS passivation layers and metallization layers adjacent to said substrate, wherein one of the one or more component region layers is a MEMS passivation layer, and The micro-electromechanical component is deposited on the MEMS passivation layer.

38. A printing method, comprising: providing a printing apparatus comprising the printer according to claim 35; and At least one of the one or more drop ejectors is controlled such that the actuator bends at least one of the one or more component region layers, thereby ejecting a printing liquid from the drop ejector to print with the printing liquid.

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