WO2017174709A1 - Procede de fabrication d'une structure micromecanique en carbure de silicium comportant au moins une cavite - Google Patents
Procede de fabrication d'une structure micromecanique en carbure de silicium comportant au moins une cavite Download PDFInfo
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- WO2017174709A1 WO2017174709A1 PCT/EP2017/058222 EP2017058222W WO2017174709A1 WO 2017174709 A1 WO2017174709 A1 WO 2017174709A1 EP 2017058222 W EP2017058222 W EP 2017058222W WO 2017174709 A1 WO2017174709 A1 WO 2017174709A1
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- silicon carbide
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- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 title claims abstract description 139
- 229910010271 silicon carbide Inorganic materials 0.000 title claims abstract description 133
- 238000000034 method Methods 0.000 title claims abstract description 47
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 108
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 72
- 239000010703 silicon Substances 0.000 claims abstract description 72
- 238000000151 deposition Methods 0.000 claims abstract description 50
- 238000000137 annealing Methods 0.000 claims abstract description 35
- 238000007493 shaping process Methods 0.000 claims abstract description 18
- 230000000977 initiatory effect Effects 0.000 claims abstract description 4
- 230000008021 deposition Effects 0.000 claims description 30
- 239000012528 membrane Substances 0.000 claims description 20
- 239000000758 substrate Substances 0.000 claims description 20
- 238000005255 carburizing Methods 0.000 claims description 17
- 238000004519 manufacturing process Methods 0.000 claims description 11
- 230000010512 thermal transition Effects 0.000 claims description 10
- 239000012298 atmosphere Substances 0.000 claims description 8
- 239000000126 substance Substances 0.000 claims description 7
- 150000001875 compounds Chemical class 0.000 claims description 4
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 claims description 3
- 230000008030 elimination Effects 0.000 claims description 3
- 238000003379 elimination reaction Methods 0.000 claims description 3
- 238000005304 joining Methods 0.000 claims description 3
- 239000004215 Carbon black (E152) Substances 0.000 claims description 2
- 229930195733 hydrocarbon Natural products 0.000 claims description 2
- 150000002430 hydrocarbons Chemical class 0.000 claims description 2
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims 2
- 229910052594 sapphire Inorganic materials 0.000 claims 1
- 239000010980 sapphire Substances 0.000 claims 1
- 230000007704 transition Effects 0.000 claims 1
- 238000005530 etching Methods 0.000 description 13
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 10
- 230000015572 biosynthetic process Effects 0.000 description 9
- 239000003795 chemical substances by application Substances 0.000 description 9
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 5
- 239000002243 precursor Substances 0.000 description 5
- 239000001294 propane Substances 0.000 description 5
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 4
- 230000008901 benefit Effects 0.000 description 4
- 238000005229 chemical vapour deposition Methods 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 238000009792 diffusion process Methods 0.000 description 4
- 239000001257 hydrogen Substances 0.000 description 4
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 3
- 229910000577 Silicon-germanium Inorganic materials 0.000 description 3
- LEVVHYCKPQWKOP-UHFFFAOYSA-N [Si].[Ge] Chemical compound [Si].[Ge] LEVVHYCKPQWKOP-UHFFFAOYSA-N 0.000 description 3
- 239000007833 carbon precursor Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 229910018503 SF6 Inorganic materials 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 239000013043 chemical agent Substances 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 229910021389 graphene Inorganic materials 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000005012 migration Effects 0.000 description 2
- 238000013508 migration Methods 0.000 description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- SFZCNBIFKDRMGX-UHFFFAOYSA-N sulfur hexafluoride Chemical compound FS(F)(F)(F)(F)F SFZCNBIFKDRMGX-UHFFFAOYSA-N 0.000 description 2
- 229960000909 sulfur hexafluoride Drugs 0.000 description 2
- 235000012431 wafers Nutrition 0.000 description 2
- 238000001039 wet etching Methods 0.000 description 2
- 241000252506 Characiformes Species 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- 229910006404 SnO 2 Inorganic materials 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 238000003486 chemical etching Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000005489 elastic deformation Effects 0.000 description 1
- 238000000407 epitaxy Methods 0.000 description 1
- 238000001657 homoepitaxy Methods 0.000 description 1
- 238000009616 inductively coupled plasma Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000001459 lithography Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 150000002926 oxygen Chemical class 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 229910000077 silane Inorganic materials 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
- B81C1/00134—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems comprising flexible or deformable structures
- B81C1/00158—Diaphragms, membranes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B3/00—Devices comprising flexible or deformable elements, e.g. comprising elastic tongues or membranes
- B81B3/0018—Structures acting upon the moving or flexible element for transforming energy into mechanical movement or vice versa, i.e. actuators, sensors, generators
- B81B3/0021—Transducers for transforming electrical into mechanical energy or vice versa
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
- B81C1/00023—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems without movable or flexible elements
- B81C1/00047—Cavities
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00436—Shaping materials, i.e. techniques for structuring the substrate or the layers on the substrate
- B81C1/00444—Surface micromachining, i.e. structuring layers on the substrate
- B81C1/00468—Releasing structures
- B81C1/00476—Releasing structures removing a sacrificial layer
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B2201/00—Specific applications of microelectromechanical systems
- B81B2201/02—Sensors
- B81B2201/0214—Biosensors; Chemical sensors
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B2201/00—Specific applications of microelectromechanical systems
- B81B2201/02—Sensors
- B81B2201/0264—Pressure sensors
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B2203/00—Basic microelectromechanical structures
- B81B2203/01—Suspended structures, i.e. structures allowing a movement
- B81B2203/0127—Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B2203/00—Basic microelectromechanical structures
- B81B2203/03—Static structures
- B81B2203/0315—Cavities
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C2201/00—Manufacture or treatment of microstructural devices or systems
- B81C2201/01—Manufacture or treatment of microstructural devices or systems in or on a substrate
- B81C2201/0101—Shaping material; Structuring the bulk substrate or layers on the substrate; Film patterning
- B81C2201/0111—Bulk micromachining
- B81C2201/0116—Thermal treatment for structural rearrangement of substrate atoms, e.g. for making buried cavities
Definitions
- the technical field of the invention is that of micro-fabrication.
- the present invention relates to a method of manufacturing a micromechanical structure of silicon carbide having at least one cavity.
- Micromechanical structures, and in particular electromechanical microsystems, are used in many technical fields and in particular in the manufacture of sensors. These sensors are sometimes used in hostile environments, that is, environments with high temperatures or pressures, or extreme chemical conditions. For such applications, it is known to use electromechanical microsystems made of a resistant material such as silicon carbide (SiC). This material has indeed many advantages, including its high mechanical strength and inertia vis-à-vis most chemical agents.
- SiC silicon carbide
- EP21 68910B1 proposes a method in which a sacrificial silicon germanium (SiGe) structure is deposited and structured on a surface of silicon carbide. This sacrificial structure is then covered by a layer of silicon carbide. An opening is then formed on the surface of the silicon carbide layer, this opening opening on the sacrificial structure of silicon germanium. Wet etching is then performed, the etching agent penetrating through the opening in the silicon carbide layer and attacking the sacrificial structure. Once the silicon germanium structure has been fully etched, the opening in the silicon carbide layer is closed to obtain a cavity.
- SiGe silicon germanium
- the invention offers a solution to the problems mentioned above, by making it possible to eliminate the discrete silicon structure by means of a carburation step, a deposition step and an annealing step. It is thus possible to overcome the etching step. The disadvantages concerning the opening formed in the silicon carbide layer and the bonding phenomenon associated with it are thus avoided.
- a first aspect of the invention relates to a method of manufacturing a micromechanical structure of silicon carbide having a cavity, from a stack comprising a first layer of silicon carbide and a silicon layer on the first silicon carbide layer, said method comprising a step of shaping the silicon layer so as to form a discrete structure of silicon on the first layer of silicon carbide.
- the method according to the invention also comprises:
- carburizing step is understood to mean an annealing step in an atmosphere containing a precursor of carbon, for example propane, but devoid of silicon, leading to the growth of a layer of silicon carbide at the level of the surface of the discrete structure of silicon. .
- This step will create empty spaces in sacrificial silicon structures. These empty spaces will be called voids in the rest of the text.
- voids in the rest of the text.
- a single discrete structure of silicon is formed.
- the expression "a discrete structure” should therefore be understood as “at least one discrete structure” and the expression “a cavity” should therefore be understood as "at least one cavity”.
- the shaping step of the silicon layer makes it possible to determine the geometry of the cavity and to control the size of the latter in all three dimensions.
- the method according to the invention makes it possible to control this phenomenon in order to to obtain a hermetically sealed cavity having dimensions perfectly controlled and independent of the crystalline orientation of the silicon layer. More particularly, once the discrete structure of silicon formed on the surface of the first layer of silicon carbide, the formation of the cavity is ensured by the last three steps of the process.
- the carburizing step initiates the formation of voids and a silicon carbide layer on the surface of the discrete silicon structure.
- the size of the voids is less than one hundred nanometers.
- the deposition step of a second layer of silicon carbide is then performed. This step will fill part of the openings created during the carburation stage. This step is performed so that, at the end of the deposition, openings allowing diffusion of the silicon atoms on the surface of the layer of silicon carbide are always present in the silicon carbide layer.
- the annealing step makes it possible to consume the carbon precursor and the remaining silicon so as to form a micromechanical structure of silicon carbide having a sealed cavity.
- the method of manufacturing a micromechanical silicon carbide structure comprising a cavity may have one or more additional characteristics among the following, considered individually. or in any technically possible combination.
- the shaping step of the silicon layer is directly followed by a second annealing step.
- This second annealing step makes it possible to improve the surface state of the discrete silicon structure before the carburizing step and thus to control the crystalline orientation of the silicon carbide membrane.
- it makes it possible to obtain a silicon carbide layer whose crystalline orientation is of (1 1 1) type.
- This crystalline orientation makes it possible to obtain a low roughness compared to a membrane whose crystalline orientation is of (1 10) type.
- a thermal transition step is performed between the carburizing step and the step of depositing the second layer of silicon carbide.
- the temperature changes from a first temperature equal to the temperature of the carburizing step to a second temperature equal to the temperature of the deposition step of the second layer of silicon carbide.
- the voids formed during the carburizing step will grow to reach a size of the order of a few hundred nanometers or even of the order of a few microns.
- a waiting step is performed between the thermal transition step and the deposition step of the second silicon carbide layer. This waiting time allows to modulate the size of the voids according to the size of the desired cavity.
- the temperature during the annealing step is between 1100 ° C. and 1400 ° C.
- This temperature window ensures a good compromise between the speed of growth of the voids and the silicon carbide layer and the quality of the silicon carbide obtained during this annealing step.
- the duration of the annealing step is chosen as a function of the width, the length and / or the thickness of the discrete silicon structure.
- the silicon structure is completely consumed at the end of the annealing step to form the micromechanical structure of silicon carbide having a cavity.
- the carburizing step is carried out in an atmosphere comprising a hydrocarbon gas.
- propane is chosen as carbon precursor gas and hydrogen is chosen as the carrier gas.
- the stack comprises a substrate and the method according to the invention comprises, before the step of shaping the silicon layer:
- the substrate forming the first layer of the stack is chosen so as to allow crystal growth of 3C-SiC.
- This substrate may be a substrate of silicon (Si), sapphire (Al 2 O 3 ), aluminum nitride (AlN), silicon carbide (SiC) or gallium nitride (GaN).
- the first silicon carbide layer and / or the second silicon carbide layer have a 3C-SiC crystal structure.
- the first silicon carbide layer has a crystalline orientation of (001) type and / or the second silicon carbide layer has a crystalline orientation of (1 1 1) type.
- the shaping step is performed so as to form in the silicon layer a plurality of connecting elements, each connecting element of the plurality of connecting elements joining at least a first discrete structure of the plurality from discrete structures to a second discrete structure of the plurality of discrete structures.
- the width of said link member is less than the width of the discrete structures among the plurality of discrete structures that said link member joins.
- width of a discrete structure is meant the edge of smaller dimension of a section of said discrete structure obtained in a plane parallel to the surface of the first layer of silicon carbide and passing through said discrete structure.
- width of a connecting element is understood to mean the edge of smaller dimension of a section of said connecting element obtained in a plane parallel to the surface of the first layer of silicon carbide and passing through said connecting element.
- a second aspect of the invention relates to a sensor of the electromechanical microsystem type comprising a micromechanical structure of silicon carbide having a cavity sealed by a silicon carbide membrane, obtained by a method according to a first aspect of the invention.
- the senor is a piezoresistive or capacitive type pressure sensor.
- the senor is a chemical sensor comprising at least one layer sensitive to a chemical compound to be detected, said sensitive layer being deposited on said membrane.
- a third aspect of the invention relates to the use of a sensor according to a second aspect of the invention in or on an organic tissue.
- a third aspect of the invention relates to the use of a sensor according to a second aspect of the invention in a radiative environment.
- FIGS. 2A to 2F a diagram of the different steps of the method according to a second embodiment
- FIG. 3 is a flow diagram of the method according to a third embodiment of the invention.
- FIG. 4 a flowchart of the method according to a fourth embodiment of the invention.
- FIGS. 7A and 7B an illustration of the structure obtained at the end of the shaping step of the silicon layer according to one embodiment of the invention
- An aspect of the invention illustrated in FIG. 1 and in FIGS. 2A to 2F concerns a method of manufacturing a micromechanical structure of silicon carbide having a cavity 5, starting from a stack comprising a first layer of silicon carbide 2 and a silicon layer 3 on the first silicon carbide layer 2, said method comprising a step 102 for shaping the silicon layer 3 (FIG. 2C) so as to form a discrete 3 'structure of silicon on the first layer of silicon carbide 2.
- the method furthermore comprises:
- a carburation step 103 initiating the elimination of the discrete 3 'silicon structure
- carburetion is understood to mean an annealing step in an atmosphere containing a carbon precursor, for example propane, but devoid of silicon, leading to the growth of a layer of silicon carbide at the level of the surface of the discrete structure of silicon and the formation of voids in these same structures.
- a carbon precursor for example propane, but devoid of silicon
- the growth of the silicon carbide during the carburizing step 103, the step 104 of deposition of a second layer of silicon carbide 4 and during the annealing step 105 causes the formation of a layer of carbide of silicon on the surface of the discrete structure (FIG. 2D) as well as a migration of the silicon atoms SI (illustrated by dashed arrows in FIG. 2E) of the discrete structure 3 'of silicon towards the growth zones, that is to say towards the surface of the discrete structure 3 'of silicon.
- This diffusion has two consequences: it feeds the growth of the silicon carbide layer 4 into silicon atoms at the surface of the discrete structure 3 'and it causes the formation of a cavity 5 (illustrated by continuous arrows at Figure 2E) in these same structures 3 '.
- a micromechanical structure of silicon carbide having a cavity 5 is thus obtained without resorting to an etching agent.
- no etching agent is used, it is no longer necessary to provide an opening in the silicon carbide layer 4 and thus a hermetically sealed cavity can be obtained.
- step 103 of carburation makes it possible to initiate the formation of the voids.
- the size of the voids is generally less than one hundred nanometers.
- the step 104 of deposition of a second layer of silicon carbide 4 is then performed. This step will make it possible to fill part of the openings created during the carburizing step 103. The latter is made so that, at the end of the step 104 of deposition of the second layer of silicon carbide 4, openings for the diffusion of the silicon atoms on the surface of the silicon carbide layer 4 are always present during the first two stages, the 3C-SiC layer continues to form and thicken.
- the annealing step 104 makes it possible to consume the precursor of the remaining carbon and silicon so as to form a micromechanical structure of silicon carbide having a sealed cavity 5.
- a micromechanical structure of silicon carbide having a cavity 5 is formed by the consumption of the silicon atoms of the discrete structure 3 ', this consumption resulting in the formation of the silicon carbide layer 4 forming a silicon carbide membrane .
- the cavity 5 is thus self-sealed and the pressure within this cavity 5 is identical to the pressure used during the annealing step 105.
- the silicon carbide component of the second layer of silicon carbide 4 has a crystal structure of the 3C-SiC type.
- the stack further comprises a substrate 1.
- the method then comprises, before step 102 of shaping the silicon layer 3:
- a deposition step 100 (FIG. 2A) of a first layer of silicon carbide 2 on the substrate 1;
- a deposition step 101 (FIG. 2B) of a silicon layer 3 on the first layer of silicon carbide 2.
- Step 100 of deposition of a first layer of silicon carbide 2 and step 101 of deposition of a silicon layer 3 make it possible to obtain the stack comprising a first layer of silicon carbide 2 and a layer of silicon 3 on the first layer of silicon carbide 2.
- the substrate 1 of the stack is chosen so as to allow the growth of silicon carbide. It may be selected from a substrate of silicon (Si), sapphire (Al 2 O 3 ), aluminum nitride (AlN), silicon carbide (SiC) or gallium nitride (GaN). Indeed, these substrates make it possible to grow, during step 100 of deposition of the first layer of silicon carbide 2, a monocrystalline silicon carbide layer and thus improves the mechanical and electrical characteristics of the micromechanical structure obtained.
- the first silicon carbide layer 2 is of the 3C-SiC type.
- the crystalline orientation of the first silicon carbide layer 2 is of the (001) type.
- the deposition step 100 of the first silicon carbide layer 2 on the substrate 1 may be preceded by a step of removing the native oxide present on the surface of said substrate 1.
- this step of removing the native oxide may take the form of a homoepitaxy of a thin silicon layer on the silicon substrate 1 or an annealing under hydrogen atmosphere. If the substrate 1 is a nitride, this step of removing the native oxide may take the form of annealing in a nitrogen atmosphere.
- the deposition step 100 of the first silicon carbide layer 2 may be carried out by an epitaxial process, for example by means of a chemical vapor deposition technique (CVD for "Chemical Vapor Deposition” in English).
- CVD chemical vapor deposition
- the thickness of the first silicon carbide layer 2 is between 100 nm and 20 ⁇ m, preferably equal to 5 ⁇ m.
- the shaping step 102 (FIG. 2C) of the silicon layer 3 may be carried out using a conventional lithography technique.
- the etching of the silicon layer may be carried out using inductively coupled plasma (ICP) etching in an atmosphere containing sulfur hexafluoride (SF). 6 ), ethylene (C 2 H 4 ) and argon (Ar).
- ICP inductively coupled plasma
- SF sulfur hexafluoride
- ethylene C 2 H 4
- Ar argon
- the removal of the resin layer after etching can be performed by an oxygen plasma step. This oxygen plasma cleaning step may optionally be followed by a cleaning step using a piranha solution.
- step 102 of shaping (FIG. 2C) of the silicon layer 3 is followed by a second annealing step 106.
- the temperature may be between 800 ° C. and 1000 ° C.
- the pressure during this annealing step 106 may be chosen less than 1 bar.
- the duration of this annealing step 106 may be substantially equal to 10 minutes or even 20 minutes. It makes it possible to obtain a better surface state before the carburizing step 103 and thus to control the crystalline orientation of the second layer of silicon carbide 4.
- the second layer of silicon carbide 4a a crystalline orientation of the type (1 1 1).
- the temperature during the carburizing step 103 is between 860 ° C and 1300 ° C, preferably between 860 ° C and 1150 ° C.
- the temperature is modified so as to go from a minimum temperature of 860 ° C. to a maximum temperature of 1150 ° C.
- the temperature is varied so as to go from a minimum temperature of 860 ° C to a maximum temperature of 1100 ° C.
- the carburation step 103 is carried out under an atmosphere comprising a precursor of carbon, for example propane, and hydrogen.
- a thermal transition step 107 is performed between the carburizing step 103 and the step 104 of deposition of the second layer of carbide of silicon 4.
- the temperature is changed from a first value equal to the temperature of the carburation step 103 to a second value equal to the temperature of the deposition step 104.
- the voids formed during the carburation step 103 will grow to a size of the order of a few hundred nanometers or even of the order of a micrometer .
- a carburation step 103 carried out at 1150 ° C. and a step
- the size of the voids is between 500nm and 1 ⁇ .
- This thermal transition step 107 can be carried out under an atmosphere comprising hydrogen.
- a waiting step 108 is performed between the thermal transition step 107 and the deposition step 104 of the second silicon carbide layer 4.
- This step 108 of waiting allows the voids to be grown before step 104 for depositing the second layer of silicon carbide 4.
- the size of the voids at the end of step 108 of waiting depends on the duration of this step 108 waiting . For example, for a thickness of the discrete silicon structure 3 'of 300 nm, a carburation step 103 carried out at 1150.degree. C. and a step 104 for depositing the second layer of silicon carbide 4 at 1320.degree. size of the voids obtained at the end of a step 108 waiting 5 minutes is between 1 .5 ⁇ and 2.5 ⁇ .
- the size of the voids obtained at the end of a step 108 waiting 10 minutes is between 3.5 ⁇ and 5 ⁇ .
- the size of the voids is also dependent on the thickness of the discrete structure 3 '.
- a carburation step 103 carried out at 1150.degree. C. and a step 104 for depositing the second layer of silicon carbide 4 at 1320.degree. voids obtained at the end of a waiting step 108 of 5 minutes is at least equal to 5 ⁇ .
- the size of the voids obtained at the end of a step 108 waiting 5 minutes is equal to 900 nm.
- the size of the voids obtained at the end of a waiting step 108 of 5 minutes is equal to 400 nm.
- the temperature during the step 104 of deposition of the second layer of silicon carbide 4 is between 1100 ° C and 1400 ° C.
- This deposition step 104 can be carried out by epitaxy using a precursor of silicon, for example silane (SiH 4 ) and a precursor of carbon, for example propane (C 3 H 8 ).
- This deposition can be carried out by a technique of chemical vapor deposition (CVD for "Chemical Vapor Deposition" in English).
- the duration of this step can be between 30 seconds and 10 minutes, preferably between 1 minute and 3 minutes.
- the temperature during the annealing step 105 is equal to the temperature during the deposition step 104 of the second silicon carbide layer 4, that is to say between 1 100 C. and 1400 ° C.
- the duration of annealing step 105 is a function of the size of the discrete structure of silicon 3 '. For example, if the discrete structure 3 'has a thickness of 200nm, a width of 20 ⁇ and a length of 20 ⁇ , then the annealing step 105 has a duration substantially equal (at plus or minus 20%) to 30 minutes. In an embodiment illustrated in FIG.
- the shaping step 102 is made so as to form in the silicon layer 3 a plurality of connecting elements, each connecting element 3bis of the plurality of elements connecting link joining at least a first discrete structure 3 'of the plurality of discrete structures to a second discrete structure 3' of the plurality of discrete structures.
- the width of said connecting element 3bis is smaller than the width of the discrete structures 3 'among the plurality of discrete structures that said connecting element 3bis joins.
- Each connecting element also has a length equal to the distance separating the discrete structures 3 'from among the plurality of discrete structures that said connecting element 3bis joins.
- the discrete structures 3 ' are distributed on the surface of the first layer of silicon carbide 2 in the form of a matrix of discrete structures 3', the said discrete structures forming a plurality of lines L and a plurality of columns C, each comprising a plurality of discrete structures 3 '.
- each discrete structure 3 'of the same column C is joined by means of a connecting element 3bis to the discrete structure 3' which precedes it in column C so as to obtain a continuous structure formed by an alternation of discrete structures 3 'and connecting elements 3bis.
- the discrete structures have a square shape with a width of 25 ⁇ and the connecting elements have a width of 5 ⁇ and a length of 10 ⁇ .
- two discrete structures 3 'consecutive joined by a connecting element 3bis are spaced apart by a distance of 10 ⁇ .
- the discrete silicon structures 3 'and the connecting elements 3a being made in the same silicon layer 3, they therefore have an identical thickness equal to the thickness of said silicon layer 3.
- This thickness may for example be equal to 200 nm .
- the steps performed on the discrete silicon 3 'structures, in particular the carburation step 103, the silicon carbide deposition step 104 and the annealing step 105, are also implemented on the connecting elements 3bis.
- a cavity 5 is thus obtained in a silicon carbide structure comprising zones having a width of 25 ⁇ corresponding to the discrete silicon structures 3 'suppressed and zones having a width of 5 ⁇ and a length of 10 ⁇ corresponding to the elements of FIG. link 3bis deleted by the method object of the invention.
- the connecting elements 3a being made in the same silicon layer 3 as the discrete silicon structures 3 ', they are therefore eliminated concomitantly with the discrete silicon structures.
- a particularly advantageous application of these micromechanical structures relates to the production of sensors, in particular sensors used in a severe environment, involving extreme pressure and / or temperature conditions, as well as in demanding chemical environments.
- sensors in particular MEMS sensors or electromechanical microsystems, advantageously benefit from the mechanical and electrical properties of SiC, in particular its properties of thermal conductivity, mechanical strength as well as its stability towards most chemical compounds, even at high temperatures. exceeding 300 ° C make the SiC particularly suitable for this type of application.
- MEMS sensors are, for example, capacitive type pressure sensors. In an embodiment illustrated in FIG.
- the sensor according to a second aspect of the invention comprises a support 1 0, for example a support made of silicon, separated from the micromechanical structure by an electrical insulating layer 1, for example a layer 1 of aluminum nitride (AlN).
- a support 1 for example a support made of silicon
- AlN aluminum nitride
- the membrane 4 undergoes an elastic deformation modifying the distance between the membrane 4 and the support 10.
- This variation in distance results in a proportional variation of the capacitance Cp.
- This variation can be measured, for example by means of a first PC contact disposed on the support and a second DC contact disposed on the membrane 4, and the pressure P exerted on the SiC membrane can be deduced from this measured.
- MEMS sensors can also be piezoresistive type pressure sensors.
- a piezoresistive sensor according to a second aspect of the invention comprises at least two deposited contacts. on the SiC membrane 4 of the micromechanical structure. Under the effect of pressure, a variation of the resistivity of the SiC membrane proportional to the pressure applied is measured and allows to deduce the pressure exerted on the SiC membrane.
- the senor is a chemical sensor.
- a chemical sensor may, for example, be obtained by deposition, on the silicon carbide membrane 4 of the cavity of the micromechanical structure obtained by a method according to a first aspect of the invention, of at least one sensitive layer.
- a chemical compound to be detected in particular graphene or metal oxide, for example a layer of SiO 2 , TiO 2 , ZnO, SnO 2 .
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Computer Hardware Design (AREA)
- Micromachines (AREA)
- Pressure Sensors (AREA)
- Chemical Vapour Deposition (AREA)
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
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US16/091,384 US10472230B2 (en) | 2016-04-06 | 2017-04-06 | Process for fabricating a micromechanical structure made of silicon carbide including at least one cavity |
EP17714827.7A EP3440012A1 (fr) | 2016-04-06 | 2017-04-06 | Procédé de fabrication d'une structure micromécanique en carbure de silicium comportant au moins une cavité |
JP2019503769A JP2019513904A (ja) | 2016-04-06 | 2017-04-06 | 少なくとも1個の空洞を含む炭化ケイ素製のマイクロメカニカル構造を製作するための方法 |
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FR1653006 | 2016-04-06 | ||
FR1653006A FR3049946B1 (fr) | 2016-04-06 | 2016-04-06 | Procede de fabrication d’une structure micromecanique en carbure de silicium comportant au moins une cavite |
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WO2017174709A1 true WO2017174709A1 (fr) | 2017-10-12 |
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PCT/EP2017/058222 WO2017174709A1 (fr) | 2016-04-06 | 2017-04-06 | Procede de fabrication d'une structure micromecanique en carbure de silicium comportant au moins une cavite |
Country Status (5)
Country | Link |
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US (1) | US10472230B2 (fr) |
EP (1) | EP3440012A1 (fr) |
JP (1) | JP2019513904A (fr) |
FR (1) | FR3049946B1 (fr) |
WO (1) | WO2017174709A1 (fr) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20040152228A1 (en) * | 2001-03-22 | 2004-08-05 | Hubert Benzel | Method for producing micromechanic sensors and sensors produced by said method |
US20080227286A1 (en) * | 2007-03-16 | 2008-09-18 | Commissariat A L'energie Atomique | Method for manufacturing an interconnection structure with cavities for an integrated circuit |
EP2168910B1 (fr) | 2008-09-29 | 2016-01-13 | Robert Bosch GmbH | Procédé de fabrication d'un dispositif micromécanique en SiC |
-
2016
- 2016-04-06 FR FR1653006A patent/FR3049946B1/fr not_active Expired - Fee Related
-
2017
- 2017-04-06 EP EP17714827.7A patent/EP3440012A1/fr not_active Withdrawn
- 2017-04-06 WO PCT/EP2017/058222 patent/WO2017174709A1/fr active Application Filing
- 2017-04-06 US US16/091,384 patent/US10472230B2/en not_active Expired - Fee Related
- 2017-04-06 JP JP2019503769A patent/JP2019513904A/ja active Pending
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20040152228A1 (en) * | 2001-03-22 | 2004-08-05 | Hubert Benzel | Method for producing micromechanic sensors and sensors produced by said method |
US20080227286A1 (en) * | 2007-03-16 | 2008-09-18 | Commissariat A L'energie Atomique | Method for manufacturing an interconnection structure with cavities for an integrated circuit |
EP2168910B1 (fr) | 2008-09-29 | 2016-01-13 | Robert Bosch GmbH | Procédé de fabrication d'un dispositif micromécanique en SiC |
Non-Patent Citations (4)
Title |
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D. J. YOUNG ET AL.: "High-Temperature Single-Crystal 3C-SiC Capacitive Pressure Sensor", IEEE SENSORS JOURNAL, vol. 4, no. 4, August 2004 (2004-08-01), XP001234160, DOI: doi:10.1109/JSEN.2004.830301 |
G-S CHUNG: "Fabrication and Characterization of a Polycrystalline 3C-SiC Piezoresistive Micro-pressure Sensor", JOURNAL OF THE KOREAN PHYSICAL SOCIETY, vol. 56, no. 6, June 2010 (2010-06-01), pages 1759 - 1762 |
N. MARSI ET AL.: "The Mechanical and Electrical Effects of MEMS Capacitive Pressure Sensor Based 3C-SiC for Extreme Temperature", JOURNAL OF ENGINEERING, vol. 2014 |
NANOTECHNOLOGY, vol. 25, no. 32, 2014, pages 325301 |
Also Published As
Publication number | Publication date |
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FR3049946B1 (fr) | 2018-04-13 |
US20190152772A1 (en) | 2019-05-23 |
US10472230B2 (en) | 2019-11-12 |
JP2019513904A (ja) | 2019-05-30 |
FR3049946A1 (fr) | 2017-10-13 |
EP3440012A1 (fr) | 2019-02-13 |
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