Microelectromechanical system component or microfluidic component, device and method

Abstract

The invention relates to a microelectromechanical system component or microfluidic component, comprising a substrate layer of a first material, preferably a silicon material, more preferably a doped silicon material, yet more preferably a p+ doped silicon material. The substrate layer is provided with a first microchannel for conducting a fluid. The microchannel is free-hanging or free-standing. The component further comprises at least one protrusion protruding into said microchannel from the upper side of the microchannel and in a direction substantially transverse to the substrate layer. Advantageously, the protrusion is made at least partly of the first material and / or integrally formed with the substrate layer.

Description

[0001] Title: Microelectromechanical system component or microfluidic component, device and method

[0002] Description

[0003] FIELD OF THE INVENTION

[0004] The present invention generally relates to a microelectromechanical system (MEMS) component or a microfluidic component comprising a free-hanging or free-standing microchannel for conducting a fluid.

[0005] BACKGROUND OF THE INVENTION

[0006] From the prior art, microelectromechanical system (MEMS) component or microfluidic component are known, which can be used as a component of a sensor device, for example micro-Coriolis mass flow meter (MFM) device.

[0007] Components are known which are made using so-called Surface Channel Technology (SCT), which allows for free-hanging channels, including (semi-) circular.

[0008] For instance, in EP2078936 B1 a method of manufacturing a system chip for a flowmeter is disclosed, wherein a monocrystalline silicon substrate is provided in which a SiN tube is realized by means of SiN deposition steps and further MEMS-techniques such that a tube structure is realized that is fixed on at least one side and is otherwise free, for which SCT is used.

[0009] Further, EP4031484 A1 discloses a method of manufacturing a microelectromechanical system (MEMS) component or microfluidic component comprising a free-hanging or free-standing microchannel.

[0010] American patent publication US10655994 B2 discloses a microfluidic channel and a flow sensor along said channel, wherein the flow sensor comprises a heat emitting resistor inside the microchannel. The heat emitting resistor, which can be considered to be a thermistor, is presented in various planar layouts to vary aspect ratios of length to width. However, the heat transfer of such a substantially planar or wire-like heat emitting resistor is relatively inefficient. Additionally, contact with bulk material may create parasitic heat transfer, which may degrade an available signal.Furthermore, US6093330 A discloses a single-mask process for fabricating enclosed, micron-scale subsurface cavities in a single crystal silicon substrate, which includes the steps of: a) patterning the substrate to form vias; b) etching the cavities through the vias; and c) sealing the vias, which method preferably includes producing closely spaced cavity pairs.

[0011] OBJECT OF THE INVENTION

[0012] It is an object of the invention to provide an alternative microelectromechanical system (MEMS) component or a microfluidic component comprising a free-hanging or free-standing microchannel for conducting a fluid. In particular, it can be an object of the invention to provide MEMS component or a microfluidic component, wherein at least one of the disadvantages of prior art MEMS components or microfluidic components is counteracted. More in particular, the invention may aim to provide a MEMS component or a microfluidic component wherein at least one of the disadvantages mentioned above is counteracted. In embodiments, the invention may aim at providing an alternative MEMS component or an alternative microfluidic component comprising a sensor element protruding into the microchannel, which preferably may be manufactured in a relatively efficient and / or relatively reliable way, and / or which preferably may provide for a relatively reliable and / or relatively accurate and / or relatively efficient use. In embodiments, the invention may provide for a component which may provide for a relatively high heat transfer between a protrusion and fluid flowing in the microchannel, preferably while allowing for a relatively high flowrate, more preferably while enabling relatively low volumes and / or relatively low pressure drops.

[0013] SUMMARY OF THE INVENTION

[0014] According to a first aspect of the invention, a microelectromechanical system (MEMS) component or a microfluidic component comprising a substrate layer of a first material, wherein the substrate layer is provided with a first microchannel for conducting a fluid, wherein the microchannel is free-hanging or free-standing, and wherein said component further comprises at least one protrusion protruding into said microchannel from the upper side of the microchannel and in a direction substantially transverse to the substrate layer.By letting the protrusion protrude into said microchannel from the upper side of the microchannel and in a direction substantially transverse to the substrate layer, a relatively large contact surface area can be provided between the protrusion and a fluid present in the microchannel during use. For example, in particular in preferred embodiments in which at least one of the one or multiple protrusions may form a heater, this may allow for a relatively accurate and / or relatively large heat transfer. For example therefore, the invention may provide for a relatively high accuracy of measurement, for example during measurement of one or more of the fluid’s thermal properties, such as for instance its thermal conductivity. The combination of such downwardly protruding protrusion with a free-hanging or freestanding microchannel may enhances this effect further, in particular if the latter may provide for additional insulation against thermal loss towards bulk material, which in particular may reduce parasitic signals, which may provide for an unprecedented capability. In particular, said MEMS or microfluidic component may allow for inline measurements, especially both in static and dynamic flow, for example while offering the possibility of a relatively large flow range and / or relatively low pressure drop.

[0015] The microchannel, which may be free-hanging or free-standing, may have an inlet and an outlet, and may have bends to direct the fluid to desired locations. Inlet and outlet are preferably on the side opposite to the upper side of the microchannel for most applications. It is noted that the microchannel can, for example, be straight, (semi-)circular, rectangular or have other shapes.

[0016] Additionally or alternatively, the provision of the protrusion protruding into said microchannel from the upper side of the microchannel and in a direction substantially transverse to the substrate layer may provide for an innovative manufacturing process.

[0017] Protruding or extending “substantially transverse” may, at least in embodiments, be considered as substantially extending in a direction not deviating more than 15% from perpendicular, preferably not deviating more than 10%.

[0018] At least in embodiments, “free-hanging” or “free-standing” may mean that, after production, the microchannel is not or only minimally connected or attached to the surrounding structure, e.g. the substrate layer, in which the channel is provided, instead of for instance still being embedded therein. In embodiments, when seen in a cross-sectional view, most of the circumference of the microchannel may becircumvented by empty space within the substrate layer. It is noted that “free-hanging” may for instance be considered as that the microchannel is only supported at or near its upper side and / or at one or more lateral sides, whereas a “free-standing” may for instance be considered as that the microchannel may, in particular in addition to being supported at or near its upper side and / or at one or more lateral sides, be supported at or near a bottom region, for example by a support structure supporting a bottom wall of the microchannel from below. “Upper side” is understood to be a side on which the microchannel is made, thus it faces outward. The microchannel and the chip or wafer on which it is located may be turned in any convenient direction during or after production. In yet another embodiment, the other side of the chip or wafer on which the microchannel is made may also be provided with a microchannel, thus also becoming an upper side.

[0019] In embodiments, the microchannel can have a first side wall having a first outer surface facing away from the microchannel, said first outer surface being defined at least partly by a first cavity provided in the substrate layer, preferably wherein said first cavity is formed as a first channel, more preferably a first channel extending substantially parallel with the microchannel. Said first cavity may be filled with a gas and may be sealed off, or may comprise a vacuum. Alternatively, the first cavity may be open to atmosphere, which may provide an advantageously lower thermal conductivity between the microchannel and the bulk material.

[0020] Additionally, the microchannel can optionally have a second side wall, being opposite to the first side wall, wherein said second side wall can then have a second outer surface facing away from the microchannel, said second outer surface then being defined at least partly by the first cavity or a second cavity provided in the substrate layer, preferably wherein said second cavity is formed as a second channel, more preferably a second channel extending substantially parallel with the microchannel. In such embodiments, material present between said two cavities can form one or more support structures, for example in order to support a free-standing microchannel. Such a support structure may form a heat sink and / or it may comprise the function of an energy transfer to or from the microchannel, such as thermal energy transfer.

[0021] It is noted that the first and / or second side wall of the microchannel can, at least partly and preferably substantially entirely, be relatively thin, preferablyunder 5 pm thickness, more preferably under 4 pm, under 3 pm, under 2 pm, or even under 1 pm. This is also the case in the examples shown in the SEM (Scanning Electron Microscope) images shown in Figs. 6A-6C. Additionally, or alternatively, the bottom wall of a free-hanging microchannel can be equally thin. The same goes for those parts of the bottom wall of a free-standing microchannel, which parts are free from a support structure formed by a remaining portion of the first substrate material.

[0022] Although the first cavity and / or the second cavity, if any, can be configured to allow a flow of a fluid, and may for instance thereto be provided with one or multiple inlets and / or one or multiple outlets, and / or is / are open to atmosphere, said first cavity and / or said second cavity may alternatively be sealed off, and may for example be filled with a gas, another fluid, such as a liquid, or a solid or may provide a vacuum.

[0023] In embodiments, the microchannel can define a microchannel height and a microchannel width, and an upper end of the microchannel can then be delimited by a microchannel upper wall, wherein at least said upper wall then can be thinner than the microchannel height and being thinner than said microchannel width. Preferably, the upper wall may be substantially flush with the upper end of the substrate layer. For example in such embodiments, the microchannel may be provided relatively close to the top side of the substrate layer.

[0024] Preferably, the microchannel can be formed as a so-called surface microchannel.

[0025] An advantage of such a construction may for example lay in that the volume of the microchannel can be in relatively direct contact to an upper surface of the substrate layer. Additionally or alternatively, an element, such as for example a sensor or transducer element, placed on the upper surface of said substrate layer may be in relatively direct contact with the protrusion. This may for example be advantageous specifically but not limited to the conduction of thermal signals.

[0026] By arranging the component such that said protrusion is made at least partly of the first material and / or is integrally formed with the substrate layer, a relatively simple production process may be provided. Additionally or alternatively, it may enable that the protrusion, which for example may be heater element, can be formed from the same material as the substrate layer. It will be appreciated that integrally formed may, at least in embodiments, may be considered as meaning thatat least parts of the protrusion are made of material that is part of initial substrate material, in particular bulk material, into which the microchannel is formed, in particular by etching it thereinto.

[0027] In embodiments, the first material of the substrate layer can be a silicon material, preferably a doped silicon material, more preferably a p+ doped silicon material. An advantage may lay in the electrical conductivity of such material, in particular when used in an electrical transducer or sensor, such as for example a thermoelectrical transducer or sensor, such as a heating element.

[0028] Preferably, a bottom wall of the microchannel may have a bottom wall thickness smaller than both the microchannel height and the microchannel width, preferably said bottom wall thickness being at most 15% of said microchannel height and at most 15% of said microchannel width, more preferably at most 10% of said height and said width, yet more preferably at most 5% of said height and said width, such as for example at most 1% of said height and said width. Additionally or alternatively, the bottom wall of the microchannel can have a bottom wall thickness of at most 25 pm, preferably at most 15 pm, more preferably at most 10 pm, yet more preferably 5 pm, such as for example about 2 or 3 pm. Preferably, the skilled person will attempt to keep the bottom wall at an even thickness, although some variation is acceptable in most applications.

[0029] An advantage of such embodiments may be that by providing a relatively low ratio of microchannel wall thickness to microchannel diameter may facilitate a relatively good energy transfer and thus relatively good signal, in particular through the volume of said microchannel, especially while it may counteract parasitic transfers and signals. This may be especially advantageous for thermal signals.

[0030] In embodiments, the component may be arranged such that the at least one protrusion extends into the microchannel from an upper wall of the microchannel. This may allow for a relatively good energy / signal transfer between said protrusion and the volume of the microchannel. Further, such position on the lower side of the, preferably relatively thin, upper wall may facilitate accessibility of said protruding element, for example such as by electrical, optical, or sonic means. Additionally or alternatively, such positioning may ease in the production, in particular when it is combined with the option to form the protrusion as an at least partly integral part of the bulk substrate material, as it then may prevent the use of a separatelyformed element which may be relatively hard to align and / or connect to the substrate layer, in particular when that has to be done in a relatively accurate and / or relatively reliable manner.

[0031] Advantageously, the at least one protrusion may comprise the same material as the substrate layer. Preferably, said at least one protrusion may be formed from said substrate layer. This may for instance enable a relatively reliable and / or relatively simple production process, for instance as tit may facilitate to omit certain additional steps, such as depositing extra material, extra masking of material and / or removal of unwanted surpluses.

[0032] In preferred embodiments, the microchannel may be a freestanding microchannel, comprising a support structure provided at the lower end of the bottom wall of the microchannel, preferably said support structure being formed at least partly by the material of the first substrate layer, more preferably wherein support structure is extending between the first cavity and the second cavity, if any. Such configuration may for instance allow for a relatively simple and / or relatively reliable construction of relatively thin walls, for example as the support structure connecting the microchannel to the bulk material and separating the adjacent cavities may enhance the mechanical stability of said microchannel. Such a support structure, which may form a heat sink, may also comprise the function of an energy transfer to or from the microchannel, such as thermal energy transfer. Such a support structure for the microchannels is preferably at or near a bottom region and it may comprise 20% of the microchannel diameter or less, or preferably 18%, 16%, 14%, 12%, 10%, 8%, 6%, 4%, 2% or less, or even more preferably 1% of the microchannel diameter, without counting the support at or near its upper side and / or at one or more lateral sides.

[0033] In a further aspect, the invention provides for a device comprising a microelectromechanical system component or a microfluidic component as described-above. Advantageously, the device may be in the form of: a sensor; a valve; a pump; or a transducer, for instance a micro-heater. In particular, the sensor may form at least one of: a thermal sensor; a flow sensor, e.g. a mass flow sensor, a thermal flow sensor or a Coriolis flow sensor; a pressure sensor; a density sensor; a viscosity sensor; and a multi-parameter sensor.

[0034] It will be appreciated that the protrusion can be encompassed in many different sensors. The sensor may comprise at least part of the one or multipleprotrusions and may, in embodiments, comprise one or multiple other elements, for instance one integrated or at least partly integrated in a side wall of the microchannel.

[0035] For example, the protrusion can be encompassed in a sensor being an electric sensor, such as a field-effect transistor-based sensor, or a capacitive sensor. Advantageously, the protrusion may for example form at least part of an effector, a heater, a mixer and / or an activator. In embodiments, the protrusion might be accompanied by one or more additional protrusions, which can form a respective one of a second, third, fourth or even further protrusion. The one or more additional protrusions may be of the same type as the first protrusion, for example such that they form two or more effectors, heaters, mixers, and / or activators. Two, three, four or more heaters are particularly preferred. The protrusions are preferably spaced regularly on the microchannel upper wall. Alternative, it is also possible that the multiple protrusions form several types, for example combining at least two different ones of effectors, heaters, mixers, and activators. Alternatively, or additionally, the sensor may be part of an electrochemical device, and / or the sensor may be an amperometric, potentiometric, conductometric, or impedimetric sensor. Alternatively, or additional, the sensor may be an optical sensor, advantageously a surface plasmon resonance based sensor, or a surface enhanced raman spectroscopy based sensor or an optical resonator. The protrusion may also be part of a sensor having a sensing principle based on biorecognition elements, such as for example antibodies or other immunochemical substances, nucleic acid sequences, enzymatic reactions, viral particles, phages, cells, complex sugars etc. Alternatively, or additionally, the sensor may form a mass-based sensor, in particular one utilizing a piezoelectric or surface acoustic wave.

[0036] In yet a further aspect, the invention provides for a method for manufacturing a microelectromechanical system component or microfluidic component, preferably one as described above, wherein said method comprises the steps of:

[0037] providing a substrate layer of a first substrate material;

[0038] etching at least one substantially vertical first trench into the first substrate material, preferably by means of anisotropic etching;

[0039] creating a first channel-etch protective layer in said first trench thereby at least covering a bottom wall and side walls of the first trench;etching a first channel portion into the first substrate material at least partly along a first lateral side of the first channel-etch protective layer,

[0040] wherein said first channel-etch protective layer forms a first barrier surface for the etching, wherein said first channel portion extends at least partly up to said channel-etch protective layer;

[0041] etching a second channel portion into the first substrate material at least partly along a second lateral side of the first channel-etch protective layer,

[0042] preferably etching said second channel portion at least up to a second barrier surface, which may be formed by a channel-etch protective layer at the first trench or a further channel-etch protective layer at a further trench, if any, and wherein the first channel portion and the second channel portion are etched to such extent that they merge and together form a microchannel.

[0043] By creating a first channel-etch protective layer in the first trench, a first barrier surface can be formed, which for instance can counteract that when the first channel portion is being etched, etchant may unintentionally reach a location at which a protrusion is to be provided within the microchannel, in particular a protrusion being formed at least partly by leaving a portion of the first substrate material behind. As such, the method may for example provide for a relatively simple and / or relatively accurate production method. Alternatively, or additionally, the method may facilitate producing a relatively accurate and / or relatively reliable microelectromechanical system component or microfluidic component.

[0044] Advantageous embodiments according to the invention are described in the appended claims.

[0045] BRIEF DESCRIPTION OF THE DRAWINGS

[0046] By way of non-limiting examples only, embodiments of the present invention will now be described with reference to the accompanying figures in which:

[0047] Fig. 1 shows a schematic partly cut-away perspective view of a first embodiment of a microelectromechanical system component or microfluidic component according to an aspect of the invention comprising a free-standing channel;Fig. 2 shows a schematic partly cut-away perspective view of a second embodiment of a microelectromechanical system component or microfluidic component according to an aspect of the invention comprising a free-hanging channel;

[0048] Fig. 3 shows a schematic partly cut-away perspective view of a third embodiment of a microelectromechanical system component or microfluidic component according to an aspect of the invention comprising a shaped protrusion;

[0049] Figs. 4A-4F show schematic cross-sectional views of an embodiment of microelectromechanical system component or microfluidic component during subsequent phases of a manufacturing process;

[0050] Figs. 5A-5B show schematic cross-sectional views of a further embodiment of microelectromechanical system component or microfluidic component during subsequent phases of an alternative embodiment of a manufacturing process; and

[0051] Figs. 6A-6C show schematic cross-sectional SEM (Scanning Electron Microscope) images of three different embodiments of microelectromechanical system components or microfluidic components.

[0052] It is noted that the figures show merely preferred embodiments according to the invention. In the figures, the same or similar reference signs or numbers refer to equal or corresponding parts.

[0053] DETAILED DESCRIPTION

[0054] Fig. 1 shows a partly cut-away microelectromechanical system component or microfluidic component 100 provided with a first microchannel 1 extending in an elongate direction D1. In order to enable showing elements of said component 100, portions of the component are cut-away in this figure. In particular, a front portion is cut-way, which in the elongate direction is located in front of the shown portion of the microelectromechanical system component or microfluidic component 100. Furthermore, also portion at both lateral sides of the shown portion are cut-away.

[0055] It is noted that the microelectromechanical system component or microfluidic component 100 comprises a substrate layer 2 of a first material, in particular a silicon material, preferably a doped silicon material, more preferably a p+ doped silicon material. The first microchannel 1, which is for conducting a fluid, for example a gas or a liquid, extends at least substantially through said substrate layer 2.In the embodiment here shown in Fig. 1, the first microchannel 1 is a free-hanging microchannel 1A, which, after manufacturing, is not any longer substantially embedded in the substrate layer 2, but is hanging freely within said substrate layer 2, as, can be seen in Fig. 1. Here, the free-hanging microchannel 1A is substantially not in contact with the material of which the substrate layer is made, and is shielded therefrom by a first cavity 4.

[0056] Although the microchannel 1 may be free-hanging, it does not necessarily have to hang free. In alternative embodiments, such as for example in the one shown in Fig. 2, the microchannel 1 can be a free-standing microchannel 1B, which may be supported by one or multiple support structures 6. Also this freestanding microchannel 1B is, after manufacturing, not any longer substantially embedded in the substrate layer 2, but is standing substantially free from said substrate layer 2, as, can be seen in Fig. 2, it is only minimally connected or attached to its surrounding structure formed by the substrate layer 2.

[0057] As for example is the case in the embodiment of Fig. 1, the microchannel 1 comprises a first side wall 13 having a first outer surface 131 facing away from the microchannel 1, i.e. facing away from the interior of the microchannel, wherein said first outer surface 131 is being defined at least partly by a first cavity 4 provided in the substrate layer 2. Preferably, said first cavity 4 can be formed as a first channel 4A, more preferably a first channel 4A extending substantially parallel with the microchannel 1, i.e. substantially extending in the elongate direction D1 of said microchannel 1. This elongate direction is straight or may comprise bends, such as 90° bends. When seen from above, the microchannel may for example be formed as straight line, a curved line, for example a substantially U-shaped line, a substantially rectangular line. In embodiments, it is also possible that the microchannel is in fluid communication with one or more other microchannels and / or that the microchannel itself may be branched.

[0058] The microchannel may have a second side wall 14, being located opposite to the first side wall 13, wherein said second side wall 14 may have a second outer surface 141 facing away from the microchannel 1, i.e. facing away from the interior of said microchannel 1. As can be seen in Fig. 1 , said second outer surface 141 may be defined at least partly by the above-mentioned first cavity 4. However, as can be seen for example in Fig. 2, said second outer surface 141 may alternatively forexample be defined at least partly a second cavity 5, which, at least in embodiments, may be delimited from the first cavity 4, in particular by means of a support structure 6. Preferably, said second cavity 5 can be formed as a second channel 5A, more preferably a second channel extending substantially parallel with the microchannel 1. However, the outer wall of the cavity does not have to be parallel with the outer wall of the microchannel, For example, the outer wall of, at least a certain section of, the microchannel, may be substantially straight, whereas the cavity, or a respective section thereof, extending substantially parallel with said outer wall or outer wall section does not have to be substantially straight by may for example comprise a local bulge or other widening, or may extend for instance in a zig-zagging, meandering or undulating manner. Substantially parallel may, at least in this context, be considered to comprise for example embodiments in which both cavities have straight walls on the side of the substrate 2, embodiments in which cavities where the walls have minor imperfections, and for example embodiments having cavities where the walls are not straight but have for instance a zig-zag, meander or undulation.

[0059] Although the support structure 6, which for example may form a heat sink, may be substantially closed or uninterrupted, it is also feasible that the support structure comprises one or more passages from the first cavity to the second cavity, for example due to that slightly more of the substrate material has been etched away in certain areas along the elongate direction of the microchannel 1.

[0060] As can be seen in Figs. 1 and 2, the component 100 further comprises at least one protrusion 3 protruding into said microchannel 1 from the upper side 1’ of the microchannel and in a direction D3 substantially transverse to the substrate layer 2, which may extend in a substantially flat, in particular a substantially horizontal direction.

[0061] Although the embodiments of Figs. 1 and 2 only show one protrusion 3 protruding into the microchannel 1, multiple protrusions may be provided in alternative embodiments. Although at least two of those protrusions may then have mutually different function, they may also have the same function.

[0062] In the here shown embodiments, the protrusion 3 extends substantially in the elongate or longitudinal direction D1 of the microchannel 1. In embodiments, the protrusion, which may be substantially wall-shaped, may for instance extend along at least 50% of the length of the microchannel, more preferablyextending along at least 70% of said length, yet more preferably extending along at least 90% of said length, such as for example extending substantially along the entire length of said microchannel 1.

[0063] However, it is also possible that that the component 1 comprises multiple protrusions extending into the first microchannel 1. For example, the component 1 comprises at least a first set of multiple protrusions, provided substantially behind each other in a longitudinal direction D1 of the microchannel 1. Although such multiple protrusions may also be substantially wall-shaped, they may have another shape, and may for instance be substantially shaped as fingers or columns extending into the microchannel 1. Further, it is noted that in case of multiple protrusions, they do not all have to have the same shape and / or size, and may be mutually differently formed.

[0064] Additionally or alternatively, the protrusion 3, at least a portion of which is here substantially formed as a straightly extending wall extending parallel with the elongate direction D1 of the microchannel 1, may be formed differently. For example, the width W3 of the protrusion 3 may vary along the length of the protrusion. Alternatively or additionally, the protrusion does not have to extend in substantially straight direction, and may for example meander or undulate, as shown in Fig. 3, or extend in a zigzag manner (not shown). It will be appreciated that, for instance in such embodiments, the length of the protrusion 3, when measured along the meandering or zigzagging path, may, at least in sub-embodiments, be longer than the length of the microchannel 1 itself.

[0065] Here, the microchannel 1 is formed as a so-called surface microchannel. Said microchannel 1 defines a microchannel height H1 and a microchannel width W1, and an upper end T of the microchannel 1 is delimited by a microchannel upper wall 11, wherein at least said upper wall 11 then can be thinner than the microchannel height H1 and being thinner than said microchannel width W1. Preferably, the upper wall 11 may be substantially flush with the upper end of the substrate layer 2’. For example in such embodiments, the microchannel 1 may be provided relatively close to the top side 2’ of the substrate layer 2.

[0066] The bottom wall 12 of the microchannel 1 may a bottom wall thickness T12 smaller than both the microchannel height H1 and the microchannel width W1. Preferably, said bottom wall thickness T12 may be at most 15% of saidmicrochannel height H1 and at most 15% of said microchannel width W1, more preferably at most 10% of said height H1 and said width W1, yet more preferably at most 5% of said height and said width, such as for example at most 1% of said height and said width.

[0067] Additionally or alternatively, the bottom wall 12 of the microchannel 1 can have a bottom wall thickness T12 of at most 25 pm, preferably at most 15 pm, more preferably at most 10 pm, yet more preferably 5 pm, such as for example about 2 or 3 pm.

[0068] Figs. 4A-4F show a microfluidic component 100 during subsequent phases being manufactured by an embodiment of a method for manufacturing a microelectromechanical system component or microfluidic component. Said method comprises a step of providing a substrate layer 2 of a first substrate material. Said first material of the substrate layer 2 can be a silicon material, preferably a doped silicon material, more preferably a p+ doped silicon material.

[0069] As can be seen in Fig. 4A, at least one substantially vertical first trench 71 is etched into the first substrate material, preferably while the upper side of the substrate material is selectively covered by a mask 91, e.g. a t-SiOa hard mask. Advantageously, the etching is done by means of anisotropic etching, in particular using an anisotropic etchant.

[0070] Subsequently, as can be seen in Fig. 4B, a first channel-etch protective layer 81 is created in said first trench 71 , thereby at least covering a bottom wall 711 and side walls 712, 713 of the first trench 71. However, as is the case in the here shown embodiment, the trench may also be filled substantially completely with channel-etch protective layer material, which for example may be or comprise a silicon nitride material, in particular a silicon-rich silicon nitride material.

[0071] In a further step, a first channel portion 1C is etched into the first substrate material 2 at least partly along a first lateral side 81 A of the first channeletch protective layer 81, in particular by means of isotropic etching, more in particular using an isotropic etchant. Said first channel-etch protective layer 81 forms a first barrier surface 81 A’ for the etching, wherein said first channel portion 1C extends at least partly up to said channel-etch protective layer 81 , in particular due to an isotropic etchant etching also in a lateral direction.In the here shown embodiment, at the opposite lateral side of the first channel portion 1 C, said first channel portion is also delimited by means of a respective barrier, which preferably is also formed by respective channel-etch protective layer 83, in particular one formed by at least partly refilling a respective trench 73, preferably a substantially vertical trench, which may be etched, in particular by anisotropic etching, for example in the same step as in which the first trench 71 was etched.

[0072] However, not in every embodiment it is necessary that at both lateral sides of the first channel portion 1 C isotropic etching is delimited by a barrier structure.

[0073] In a further step, a second channel portion 1D is etched, in particular by isotropic etching, into the first substrate material 2 at least partly along a second lateral side 81 B of the first channel-etch protective layer 81. Said etching of the second channel portion 1D, can preferably be done simultaneously with etching the first channel portion 1C, and may preferably thus be integrated in a single step.

[0074] Advantageously, said etching of the second channel portion 1D, includes etching said second channel portion 1D at least up to a second barrier surface, which may be formed by a channel-etch protective layer 81 at the first trench 71, as can be seen in the alternative embodiment of Figs. 5A-5B, but which second barrier surface may preferably be formed by a further channel-etch protective layer 82 at a further trench 72, as is the case in the exemplary embodiments shown in Figs. 4A-4F.

[0075] According to an aspect of the present method, the first channel portion 1C and the second channel portion 1D are etched to such extent that they merge, in particular below the at least partly filled first trench, and also below the further trench 72, if present. Said first channel portion 1C and said second channel portion 1D will then together form a microchannel 1.

[0076] As mentioned above, the method may thus comprise a step of etching, preferably by means of anisotropic etching, a substantially vertical second trench 72 into the first substrate material, preferably substantially along the first trench 71, and preferably executed substantially simultaneously with etching said first trench 71. A second channel-etch protective layer 82 can then be created in said second trench 72 thereby at least covering a bottom wall and side walls of the second trench 72. It will be appreciated that this may be done together with creating the firstchannel-etch protective layer 81, and that this may thus form a single or integrated step.

[0077] In such embodiments, such as for example the one shown in Figs. 4A-4E, the step of etching the second channel portion 1D may thus include etching said second channel portion 1 D up to a second barrier surface formed by said channel-etch protective layer 82 formed in said second trench 72, and said second channel portion 1D can then thus extend at least partly up to said second barrier surface formed by said channel-etch protective layer 82 in the second trench 71.

[0078] Additionally, or alternatively, the method may comprise a step of etching, preferably by means of anisotropic etching, at least a substantially vertical first outer trench 73 into the first substrate material 2 which extends substantially along the first trench 71. Preferably, said first outer trench 73 can extend deeper into the first substrate than the first trench 71. This may for example be done by etching the first outer trench 73 as a wider trench than the first trench 71, as can be seen in Fig. 4A relatively well. The method may then also comprise creating a channel-etch protective layer 83 in the first outer trench 73 thereby at least covering a bottom wall and side walls of said first outer trench 73.

[0079] It is noted that the step of etching the first channel portion 1C then can also include etching said first channel portion 1C up to a third barrier formed by said channel-etch protective layer 83 formed in the first outer trench 73, and that said first channel portion 1C can extend at least partly up to said third barrier formed by said channel-etch protective layer 83 in the first outer trench 73.

[0080] It will be appreciated that similarly, the method may comprise etching, preferably by means of anisotropic etching, a substantially vertical second outer trench 74 into the first substrate material 2, which second outer trench 74 may then extends also substantially along the first trench 71, and preferably substantially along the second trench 72, if any. Preferably, said second outer trench 74, like the first outer trench 73, can extend deeper into the first substrate than the first trench 71 and / or the second trench 72. This may counteract that the microchannel 1 , when being isotropically etched, will not extend too much sidewards, due to the respective barrier formed by a channel-etch protective layer 84 created in said second outer trench 74 extending relatively deep into the first substrate material 2.It will be appreciated that the first trench 71, the second trench 72, if any, and any outer trenches 73, 74 may be etched in a single step, in particular using a single mask 91, as can be understood relatively well from Fig. 4A.

[0081] Further, it will be appreciated that the protective layers 81, 82, 83, 84 formed in the respective trenches 71, 72, 73, 74 may be created in a single step, as can be understood relatively well from Fig. 4B.

[0082] As schematically shown in Fig. 4D, the method may further comprise providing at least the bottom of the microchannel 1, and preferably substantially the entire microchannel 1 , with a channel-etch protective layer 111 or a so-called channel sealing 111, which for example may be or comprise a silicon nitride material, in particular a silicon-rich silicon nitride material.

[0083] Although said channel-etch protective layer 111 or a so-called channel sealing 111 may in embodiments form a respective barrier for use in a further etching step in which one or more cavities 4, 5 are etched, in particular by means of isotropic etching, as can understood from Fig. 4F, said channel-etch protective layer 111 or a so-called channel sealing 111 may additional, or alternatively, have another function. For example, said channel-etch protective layer 111 or a so-called channel sealing 111 may form a protective layer covering the microchannel 1 at its inside, for example in order to provide a relatively high level of chemical inertness, in particular to facilitate that the microchannel 1, during use thereof, may be resistant against chemical corrosion to a certain extent. It will be appreciated that multiple functions of the channel-etch protective layer 111 or a so-called channel sealing 111 may be performed at least partly by different sub-layers thereof.

[0084] It will be appreciated that, at least in embodiments, the microchannel 1 may be substantially leak-free and / or may have a wall which is substantially non-permeable, in particular non-permeable for gas, and / or may be corrosion-resistant and / or may have a relatively high level of chemical inertness.

[0085] Advantageously, the channel-etch protective layer 111 or a so-called channel sealing 111 may be substantially non-permeable, in particular non-permeable for gas, and / or may be corrosion-resistant and / or may have a relatively high level of chemical inertness.

[0086] The method may further comprise the etching of one or more cavities 4, 5, in order to turn the micro-channel 1 into a free-hanging microchannel 1 A,as for example shown in Fig. 1, or a free-standing microchannel 1B, as for example shown in Fig. 4F. This may include etching a first cavity portion 4B into the first substrate material 2, preferably by means of isotropic etching, wherein said first cavity portion 4B extending along and at least partly up to at least parts of the channel-etch protective layer 111 at the bottom of the microchannel 1 , and preferably along and at least partly up to the protective layer 83 at the first outer trench 73. Additionally, it may then include etching a second cavity portion 5B into the first substrate material 2, preferably by means of isotropic etching, wherein said second cavity portion 5B then extends along and at least partly up to at least parts of the channel-etch protective layer 111 at the bottom of the microchannel 1 , and preferably along and at least partly up to the protective layer 84 at the second outer trench 74.

[0087] Said first cavity portion 4B and said second cavity portion 5B may be etched to such extent that they merge and thereby together form a single combined cavity 4, in particular such as to turn the microchannel 1 into a free-hanging microchannel 1A. Alternatively, the first cavity portion 4B and the second cavity portion 5B are etched only to such extent that a portion 26 of the first substrate material 2 remains present between the first cavity portion 4B and the second cavity portion 5B to such extent that said remaining first substrate material 2, 26 stays connected to a lower surface of the channel-etch protective layer 111 at the bottom of the microchannel 1 , in particular such that said remaining first substrate material 2, 26 forms a support 6 for the microchannel 1, which then can be considered a so-called free-standing microchannel 1B, as can be seen in Fig. 4F.

[0088] Although Figs. 4A-4F show phases during a method in which four trenches 71-74 are etched in which subsequently a creating a respective channel-etch protective layer 81-84 is created, it is not necessary to provide at least four trenches. For example, the outer trenches 73, 74 may be omitted. Alternatively, or additionally, as is the case in a method corresponding to what is shown in Figs. 5A-5B, the second trench 72 may also be omitted. In such embodiments, the first trench 71 may for example be provided with a channel-etch protective layer 81 not completely filing said trench 71. Said channel-etch protective layer 81, which then forms a protrusion 3 extending into said microchannel 1 from the upper side of the microchannel 1 and in a direction substantially transverse to the substrate layer 2, may then be kept hollow, and may thus for example form a so-called channel in channel, which preferably maybe closed off at its upper end at least partly. However, said initially hollow protrusion 3 may also be refilled, as may be understood from Fig. 5A, for example by filling it up with a material substantially similar to the first substrate material 2, in particular a silicon material, preferably a doped silicon material, more preferably a p+ doped silicon material.

[0089] However, in embodiments in which the protrusion 3 extending into the microchannel 1 is formed at least partly by two substantially parallelly extending channel-etch protective layers 81, 82 formed in two substantially parallelly etched trenches 71 , 72, a portion of the initial material of the substrate layer 2 may be kept in position between said two trenches 71 , 72 at least partly filled up by said channel-etch protective layers 81, 82. The etching of the first channel portion 1C and the second channel portion 1D may thus preferably be done to such extent that said channel portions 1 C, 1 D merge below the channel-etch protective layers 81 , 82 of the first and second trenches 71 , 72 in a manner in which at least part of the first substrate material remains present between the channel-etch protective layers of said first and second trenches 71, 72. Microelectromechanical system component 1 or microfluidic component 1, substantially the entire inner surface of the microchannel 1 and substantially the entire outer surface of the protrusion 3 may be provided with the same surface material, preferably said surface material being a silicon nitride material, more preferably a silicon rich silicon nitride material. It will be appreciated that this is for instance not only the case in the embodiment shown in Figs. 5A-5B, but may also be the case in the other shown embodiments, in particular as during the creation of the channel-etch protective layer 111 at the bottom of the microchannel 1, the lower end of substrate material 2, 23 remaining between the channel-etch protective layers 81, 82 of the first and second trenches 71, 72 may be covered by the same material 111 B deposited to form said channel-etch protective layer 111.

[0090] In yet a further, not shown embodiment, at least one of the side walls 13, 14 of the microchannel 1 may comprise a silicon material, for instance formed by the material of the first substrate layer 2, more preferably said silicon material being covered by a channel-etch protective layer, in particular a silicon nitride material, such as a silicon rich silicon nitride material. Said respective side wall 13, 14 of the microchannel 1 may for instance be formed by ensuring that some of the initial substrate layer material 2 remains behind between two channel-etch protective layers,which may be formed in two, preferably substantially parallel, trenches. This may be done more or less just like how the protrusion 3 being formed in a method corresponding to Figs. 4A-4F. Thus, instead of etching a single respective outer trench 73, 74 at the respective lateral side of the microchannel to be formed, two outer trenches may be etched at a single lateral side of the microchannel to be formed such as to leave at least a portion of substrate layer material 2 behind between the channeletch protective layers formed within those two outer trenches. As such, the respective side wall 13, 14 of the microchannel 1 may for example also function as a heater, for example in addition to, or alternative to, the protrusion 3.

[0091] It is noted that in embodiments the at least one protrusion may form an outer structure, for instance one at least partly formed of a silicon nitride material, wherein the outer structure houses some of the original substrate material 2, 23, as is the case in for example Figs. 4A-4F, or may be refilled with silicon material or kept substantially empty, other variants may be possible as well. In particular, said outer structure may house at least one of: a solid material different than the material of the outer structure, said solid material for example comprising a metal, an alloy, a ceramic material, a polymer, such as a photoresist, and / or a semiconductor material ; and / or a cavity, for example one open to atmosphere or one provided with a gas, a liquid or a vacuum, preferably wherein the cavity is formed as a channel with at least one inlet and / or at least one outlet.

[0092] In preferred embodiments of the microelectromechanical system component or microfluidic component 100, the at least one protrusion 3 may form a heater. For example thereto, as can be seen in Fig. 2, at an outer side of the upper wall of the microchannel 1, metal traces 32A, 32B may be provided on either lateral side of the protrusion 3. For example, such metal traces 32A, 32B, which may be formed by depositing, for example by sputtering, metal, in particular Platinum (Pt) or Chromium (Cr),as is depicted in Fig. 4.

[0093] It will be appreciated that the component 100, or the device of which it may become part, may comprise a heater actuation 33, see e.g. Fig. 2.

[0094] Fig. 6A shows a cross-sectional Scanning Electron Microscope (SEM) image of an example of an embodiment of a component 100, in particular a microelectromechanical system component, which to a relatively large extent corresponds with the embodiment shown in Fig. 4F. The SEM image of Fig. 6A clearlyshows the protrusion 3, which in this case is a heater. In this example, the microchannel 1 is slightly irregularly shaped, which does not negatively impact performance. The component 100 has thin side walls 13, 14 and a thin bottom wall 12, all under 5 pm thick.

[0095] Fig. 6B shows a cross-sectional SEM image of an alternative embodiment of the component 100, in particular a microelectromechanical system component, which comprises two heaters, each in the form of a respective protrusion 3.

[0096] Fig. 6C shows a cross-sectional SEM image of two microchannels 1, which, just like the microchannel 1 shown in Figs. 4C-4E, are in a phase in which they have not been made free-standing or free-hanging yet. Each of the two microchannels 1 in Fig. 6C is provided with two protrusions 3. Advantageously, these two microchannels 1 , or two other microchannels, may be arranged in an up and down configuration in which they are connected to each other at respective ends, for example by means of a bend section (not shown), such as to form a combined microchannel in which the two microchannels 1 may then thus form to substantially paral lelly extending sections of the combined microchannel.

[0097] In embodiments, the component 100, or the device, in particular a sensor device, of which said component 100 may become part, may be suitable and / or arranged and / or intended for inline microfluidic thermal conductivity sensing, in particular by means of a suspended protrusion 3, forming a heater, which comprises silicon material. The suspended heater can transfer heat directly into a fluid inside the microchannel 1, thereby minimizing heat losses. Moreover, cavities 4, 5 on either side of the microchannel 1, or a single cavity 4 substantially enclosing the microchannel, may provide for a relatively good thermal isolation, which may provide for a relatively low power consumption. It is noted that during use, the thermal conductivity of the fluid may be determined by measuring the temperature increase when the suspended heater dissipates a certain amount of power, for example 10 mW of power. Determining said thermal conductivity of the fluid, can be used in numerous industrial process, such as for example during the production of biofuels, especially those for the aerospace industry, since the thermal management in aircrafts may rely heavily on the thermal conductivity of the fuel itself. Further, by determining a thermal conductivityof a fluid mixture, the ratio between two mixed liquids in said fluid mixture may for example be determined.

[0098] It may be very advantageous to provide an etch-resistant barrier layer 83, 84, 111 which extends about the microchannel 1 at least at a bottom side and at lateral sides of said microchannel 1, wherein the first cavity portion 4B and / or the second cavity portion 5B is etched into the first substrate material 2, preferably by means of isotropic etching, up to said barrier layer 83, 84, 111. By etching up to said barrier layer 83, 84, 111 , as can for example be seen in Figs. 4F and 5B, as well as in the example shown in Fig. 6A, very thin wall portions 2, 13, 14 may be provided between the microchannel 1 and the respective cavity portion 4B, 5B. It may then be enabled that that no substrate material 2 remains present between the respective cavity portion 4B, 5B and the microchannel 1, which may be advantageously. Additionally, or alternatively, this may enable that both the side wall portions and the bottom wall portion of the wall between the microchannel 1 and the respective cavity portion 4B, 5B can have a wall thickness being no greater than 10 pm, preferably at most 5 pm, more preferably at most 4 pm, such as at most 3 pm, at most 2 pm, or even at most 1 pm.

[0099] It is noted that for the purpose of clarity and a concise description features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described. Further, it is noted that the invention is not restricted to the embodiments described herein. It will be understood that many variants are possible. Such variants will be apparent for the person skilled in the art and are considered to lie within the scope of the invention as formulated in the following claims.LIST OF REFERENCE NUMERALS

[0100] 1 microchannel

[0101] 1A free-hanging microchannel

[0102] 1B free-standing microchannel

[0103] 1C first channel portion

[0104] 1D second channel portion

[0105] 1” upper side of the microchannel

[0106] 2 substrate layer

[0107] 2’ upper side of the substrate layer

[0108] 3 protrusion

[0109] 4 first cavity

[0110] 4A first channel

[0111] 4B first cavity portion

[0112] 5 second cavity

[0113] 5A second channel

[0114] 5B second cavity portion

[0115] 6 support structure

[0116] 11 microchannel upper wall

[0117] 12 microchannel bottom wall

[0118] 13 microchannel first side wall

[0119] 14 microchannel second side wall

[0120] 23 substrate material remaining between the channel-etch protective layers 26 connecting portion of the first substrate

[0121] 32A, 32B metal traces

[0122] 33 heater actuation

[0123] 71 first trench

[0124] 711 bottom wall of the first trench

[0125] 712, 713 side walls of the first trench

[0126] 72 second trench

[0127] 73 first outer trench

[0128] 74 second outer trench

[0129] 81 first channel-etch protective layer81 A first lateral side of the first channel-etch protective layer

[0130] 81 A’ first barrier surface

[0131] 81 b second lateral side of the first channel-etch protective layer 82 second channel-etch protective layer

[0132] 83 first outer channel-etch protective layer

[0133] 84 second outer channel-etch protective layer

[0134] 91 mask

[0135] 100 microfluidic component

[0136] 111 lower surface of the channel-etch protective layer / channel sealing 131 first outer surface

[0137] 141 second outer surface

[0138] D1 elongate direction of the microchannel

[0139] H1 microchannel height

[0140] W1 microchannel width

[0141] T12 bottom wall thickness

Claims

CLAIMS1. Microelectromechanical system component or microfluidic component comprising a substrate layer of a first material,wherein the substrate layer is provided with a first microchannel for conducting a fluid,wherein the microchannel is free-hanging or free-standing, and wherein said component further comprises at least one protrusion protruding into said microchannel from the upper side of the microchannel and in a direction substantially transverse to the substrate layer.

2. Microelectromechanical system component or microfluidic component according to claim 1, preferably being formed by means of a method according to anyone of claims 20-28,wherein the microchannel has a first side wall (13) and a second side wall (14), said side walls (13, 14) having a respective outer surface (131, 141) facing away from the microchannel (1) and being defined at least partly by a respective cavity (4, 5) provided in the substrate layer (2), andwherein the side walls (13, 14) have thickness under 10 pm, preferably under 5 pm, more preferably under 4 pm, under 3 pm, under 2 pm, or even under 1 pm.

3. Microelectromechanical system component or microfluidic component according to claim 1 or 2, wherein the at least one protrusion is a heater.

4. Microelectromechanical system component or microfluidic component according to claim 1 , 2 or 3,wherein the protrusion is made at least partly of the first material and / or integrally formed with the substrate layer.

5. Microelectromechanical system component or microfluidic component according to any one of the preceding claims,wherein the microchannel is a surface microchannel; and / orwherein the microchannel defines a microchannel height and a microchannel width, and an upper end of the microchannel is delimited by a microchannel upper wall, at least said upper wall being thinner than the microchannel height and being thinner than said microchannel width.

6. Microelectromechanical system component or microfluidic component according to any one of the preceding claims,wherein the first material of the substrate layer is a silicon material, preferably a doped silicon material, more preferably a p+ doped silicon material.

7. Microelectromechanical system component or microfluidic component according to any one of the preceding claims,wherein a bottom wall of the microchannel has a bottom wall thickness being at most 15% of said microchannel height and at most 15% of said microchannel width, more preferably at most 10% of said height and said width, yet more preferably at most 5% of said height and said width, such as for example at most 1 % of said height and said width,preferably wherein a bottom wall of the microchannel has a bottom wall thickness of at most 25 pm, preferably at most 15 pm, more preferably at most 10 pm, yet more preferably 5 pm, such as for example about 2 or 3 pm.

8. Microelectromechanical system component or microfluidic component according to any one of the preceding claims,wherein the at least one protrusion extends into the microchannel from an upper wall of the microchannel.

9. Microelectromechanical system component or microfluidic component according to any one of the preceding claims,wherein the at least one protrusion comprises the same material as the substrate layer, preferably said at least one protrusion is formed from said substrate layer.

10. Microelectromechanical system component or microfluidic component according to any one of the preceding claims,wherein the microchannel has a first side wall having a first outer surface facing away from the microchannel, said first outer surface being defined at least partly by a first cavity provided in the substrate layer,preferably wherein said first cavity is formed as a first channel, more preferably a first channel extending substantially parallel with the microchannel.

11. Microelectromechanical system component or microfluidic component according to any one of the preceding claims, preferably according to claim 10,wherein the microchannel has a second side wall, being opposite to the first side wall, said second side wall having a second outer surface facing away from the microchannel, said second outer surface being defined at least partly by the first cavity or a second cavity provided in the substrate layer,preferably wherein said second cavity is formed as a second channel, more preferably a second channel extending substantially parallel with the microchannel.

12. Microelectromechanical system component or microfluidic component according to any one of the preceding claims,wherein the microchannel is a freestanding microchannel, comprising a support structure provided at the lower end of the bottom wall of the microchannel, preferably said support structure being formed at least partly by the material of the first substrate layer,more preferably wherein the microelectromechanical system component or microfluidic component is a microelectromechanical system component or microfluidic component according to claim 10 and claim 11, and said support structure is extending between the first cavity and the second cavity.

13. Microelectromechanical system component or microfluidic component according to any one of claims 10-12,wherein the first cavity and / or the second cavity, if any, is configured to allow a flow of a fluid; are open to atmosphere; or are sealed and filled with a fluid, solid or vacuum.

14. Microelectromechanical system component or microfluidic component according to any one of the preceding claims,wherein substantially the entire inner surface of the microchannel and substantially the entire outer surface of the protrusion are provided with the same surface material, preferably said surface material being a silicon nitride material, more preferably a silicon-rich silicon nitride material.

15. Microelectromechanical system component or microfluidic component according to any one of the preceding claims,wherein at least one of the side walls of the microchannel at least comprises or entirely consists of a silicon nitride material, such as a silicon-rich silicon nitride material,preferably wherein said at least one side wall comprises a silicon material, for instance formed by the the material of the first substrate layer, more preferably said silicon material being covered by silicon nitride material, such as a silicon-rich silicon nitride material.

16. Microelectromechanical system component or microfluidic component according to any one of the preceding claims,wherein the at least one protrusion is an elongate protrusion extending substantially in a longitudinal direction of the microchannel, preferably extending along at least 50% of the length of the microchannel, more preferably extending along at least 70% of said length, yet more preferably extending along at least 90% of said length, such as for example extending substantially along the entire length of said microchannel; and / orwherein the component comprises at least a first set of multiple protrusions, provided substantially behind each other in a longitudinal direction of the microchannel.

17. Microelectromechanical system component or microfluidic component according to any one of the preceding claims,wherein the at least one protrusion comprises an outer structure, for instance of a silicon nitride material, wherein the outer structure houses at least one of:a solid material different than the material of the outer structure, said solid material for example comprising a metal, an alloy, a ceramic material, a polymer, such as a photoresist, and / or a semiconductor material; and / ora cavity, for example one open to atmosphere or one provided with a gas, a liquid or a vacuum,preferably wherein the cavity is formed as a channel with at least one inlet and / or at least one outlet.

18. Microelectromechanical system component or microfluidic component according to any one of the preceding claims,wherein the microchannel is open to atmosphere, for example at a proximal end and / or a distal end of the microchannel.

19. Device, comprising the microelectromechanical system component or microfluidic component according to any one of the preceding claims,preferably wherein the device is in the form of: a sensor; a valve; a pump; or a transducer, for instance a micro-heater,more preferably wherein the sensor forms at least one of: a thermal sensor; a flow sensor, e.g. a mass flow sensor, a thermal flow sensor or a Coriolis flow sensor; a pressure sensor; a density sensor; a viscosity sensor; and a multi-parameter sensor.

20. Method for manufacturing a microelectromechanical system component or microfluidic component, preferably one according to any one of claims 1-18, said method comprising the steps of:providing a substrate layer (2) of a first substrate material; etching at least one substantially vertical first trench (71 ) into the first substrate material, preferably by means of anisotropic etching;creating a first channel-etch protective layer (81) in said first trench (71) thereby at least covering a bottom wall and side walls of the first trench;etching a first channel portion (1C) into the first substrate material at least partly along a first lateral side (81 A) of the first channel-etch protective layer, wherein said first channel-etch protective layer (81) forms a first barrier surface (81 A’) for the etching, wherein said first channel portion (1C) extends at least partly up to said channel-etch protective layer (81);etching a second channel portion (1 D) into the first substrate material at least partly along a second lateral side (81b) of the first channel-etch protective layer (81 ),preferably etching said second channel portion at least up to a second barrier surface, which may be formed by a channel-etch protective layer at the first trench or a further channel-etch protective layer at a further trench, if any, and wherein the first channel portion (1C) and the second channel portion (1D) are etched to such extent that they merge and together form a microchannel (1).

21. Method according to claim 20, further comprising the steps of:etching, preferably by means of anisotropic etching, a substantially vertical second trench into the first substrate material, preferably substantially along the first trench;creating a second channel-etch protective layer in said second trench thereby at least covering a bottom wall and side walls of the second trench,wherein the step of etching the second channel portion includes etching said second channel portion up to a second barrier surface formed by said channel-etch protective layer in the second trench, and said second channel portion extends at least partly up to said second barrier surface formed by said channel-etch protective layer in the second trench.

22. Method according to claim 20 or 21 , said method comprising the steps of:etching, preferably by means of anisotropic etching, a substantially vertical first outer trench (73) into the first substrate material (2) which extends substantially along the first trench (71),preferably wherein said first outer trench (73) extends deeper into the first substrate than the first trench (71); andcreating a channel-etch protective layer (83) in the first outer trench (73) thereby at least covering a bottom wall and side walls of said first outer trench (73),wherein the step of etching the first channel portion (1C) includes etching said first channel portion (1 C) up to a third barrier formed by said channel-etch protective layer (83) in the first outer trench (73), and said first channel portion (1C) extends at least partly up to said third barrier formed by said channel-etch protective layer (83) in the first outer trench (73).

23. Method according to any one of claims 20-22, said method comprising the steps of:etching, preferably by means of anisotropic etching, a substantially vertical second outer trench into the first substrate material which extends substantially along the first trench, and preferably substantially along the second trench, if any,preferably wherein said second outer trench extends deeper into the first substrate than the first trench and / or the second trench; andcreating a channel-etch protective layer in the second outer trench thereby at least covering a bottom wall and side walls of said second outer trench, wherein the step of etching the second channel portion includes etching said second channel portion up to a fourth barrier formed by said channel-etch protective layer in the second outer trench, and said second channel portion extends at least partly up to said fourth barrier formed by said channel-etch protective layer in the second outer trench.

24. Method according to any one of claims 20-23, said method further comprising:providing at least the bottom of the microchannel (1) with a channeletch protective layer (111),preferably wherein said step of providing at least the bottom of the microchannel with a channel-etch protective layer (111) is comprised by a step of providing substantially the entire inner surface of the microchannel with a cover layer, more preferably wherein one or more openings at the upper side of the microchannel are closed off by said cover layer.

25. Method according to claim 22, further comprising the steps of:etching a first cavity portion (4B) into the first substrate material (2), preferably by means of isotropic etching, said first cavity portion (4B) extending at least partly up to at least parts of the channel-etch protective layer (111) at the bottom of the microchannel (1); andetching a second cavity portion (5B) into the first substrate material (2), preferably by means of isotropic etching, said second cavity portion (5B) extending along and at least partly up to at least parts of the channel-etch protective layer (111) at the bottom of the microchannel (1 ).

26. Method according to claim 23,wherein said first cavity portion (4B) extends along and at least partly up to the protective layer (83) at the first outer trench (73), andwherein said second cavity portion (5B) extends along and at least partly up to the protective layer (84) at the second outer trench (74).

27. Method according to claim 25 or 26,wherein the first cavity portion and the second cavity portion are etched to such extent that they merge and thereby together form a single combined cavity, in particular such as to turn the microchannel (1) into a free-hanging microchannel (1A).

28. Method according to claim 25 or 26,wherein the first cavity portion and the second cavity portion are etched only to such extent that a portion of the first substrate material remains presentbetween the first cavity portion and the second cavity portion to such extent that said remaining first substrate material stays connected to a lower surface of the channeletch protective layer at the bottom of the microchannel, in particular such that said remaining first substrate material forms a support for the microchannel, which then can be considered a so-called free-standing microchannel (1B).

29. Method according to anyone of claims 21-28, preferably according to any one of claims 24-28,wherein a etch-resistant barrier layer (83, 84, 111) is provided which extends about the microchannel (1) at least at a bottom side and lateral sides of said microchannel (1),wherein a first cavity portion (4B) and / or a second cavity portion (5B) is etched into the first substrate material (2), preferably by means of isotropic etching, up to said barrier layer (83, 84, 111 ).

30. Method according to any one of claims 21-29,wherein the etching of the first channel portion and the second channel portion is to such extent that they merge below the channel-etch protective layers of the first and second trenches in a manner in which at least part of the first substrate material remains present between the channel-etch protective layers of said first and second trenches.

Images