CN111498796A - Method for producing a MEMS structure and corresponding MEMS structure - Google Patents
Method for producing a MEMS structure and corresponding MEMS structure Download PDFInfo
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- 238000004519 manufacturing process Methods 0.000 title abstract description 22
- 239000010410 layer Substances 0.000 claims abstract description 119
- 239000002346 layers by function Substances 0.000 claims abstract description 55
- 238000000034 method Methods 0.000 claims abstract description 41
- 238000000151 deposition Methods 0.000 claims abstract description 39
- 238000007789 sealing Methods 0.000 claims abstract description 25
- 239000000758 substrate Substances 0.000 claims abstract description 21
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- 150000004767 nitrides Chemical class 0.000 claims description 8
- 238000004544 sputter deposition Methods 0.000 claims description 6
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- 230000008021 deposition Effects 0.000 description 34
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 6
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- 229910052710 silicon Inorganic materials 0.000 description 3
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- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 238000005538 encapsulation Methods 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 2
- 229920005591 polysilicon Polymers 0.000 description 2
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
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- 230000001419 dependent effect Effects 0.000 description 1
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- 229910000077 silane Inorganic materials 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 238000012876 topography Methods 0.000 description 1
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
- G01L9/0041—Transmitting or indicating the displacement of flexible diaphragms
- G01L9/0042—Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms
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- 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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
- B81B7/02—Microstructural systems; Auxiliary parts of microstructural devices or systems containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS]
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- 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
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- 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
- B81C1/00349—Creating layers of material on a substrate
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- 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
- B81C1/00349—Creating layers of material on a substrate
- B81C1/0038—Processes for creating layers of materials not provided for in groups B81C1/00357 - B81C1/00373
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
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- 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
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- 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
- B81C2201/0118—Processes for the planarization of structures
- B81C2201/0119—Processes for the planarization of structures involving only addition of materials, i.e. additive planarization
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- 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
- B81C2201/0118—Processes for the planarization of structures
- B81C2201/0122—Selective addition
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- 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
- B81C2201/0174—Manufacture or treatment of microstructural devices or systems in or on a substrate for making multi-layered devices, film deposition or growing
- B81C2201/0181—Physical Vapour Deposition [PVD], i.e. evaporation, sputtering, ion plating or plasma assisted deposition, ion cluster beam technology
Abstract
The invention relates to a method for producing a MEMS structure, to a corresponding MEMS structure and to a MEMS component. The method comprises the following steps: providing a substrate (S) on which a micromechanical functional layer assembly (FS) is applied, which has one or more functional layers, the functional layer assembly (FS) having a cavity (K) which is exposed towards the outside of the functional layer (FS) via a through-opening (D; D'), the through-opening having a smaller lateral extent than the functional layer assembly (FS); depositing a sealing layer (O, O ') on the outside of the functional layer assembly (FS) and the through-opening (D; D') by means of an HDP method in such a way that a first region (O) of the sealing layer (O, O ') grows on the outside of the functional layer assembly (FS) and a second region (O') of the sealing layer (O, O ') grows from the interior of the cavity (K) in a column below the through-opening (D; D'); a closed region (VBO) is formed in the through-opening (D; D ') by a second region (O ') of the closed layer (O, O ').
Description
Technical Field
The invention relates to a method for manufacturing a MEMS structure and a corresponding MEMS structure.
Background
The invention and the problems based on it are explained in terms of a MEMS absolute pressure sensor device, although any micromechanical component (MEMS) can also be used.
Many MEMS components require a defined gas pressure enclosed in a cavity (Kaverne) to operate, especially in a vacuum or at least at pressures well below 100 torr. As examples of this, mention may be made, for example, of systems which resonate, such as rotational speed sensor devices, oscillators which operate as a time reference, or MEMS absolute pressure sensor devices.
Fig. 5a) -c) are schematic cross-sectional views for explaining an exemplary manufacturing method of a MEMS structure in the form of an absolute pressure sensor device and its way of action.
Reference sign S in fig. 5a) -c) denotes a substrate, for example a silicon wafer substrate. A micromechanical functional layer assembly FS having one or more functional layers (e.g., a polysilicon layer, an oxide layer, a nitride layer, a metal layer, etc.) is applied to the substrate S, wherein the functional layer assembly FS has a cavity K.
The cavity K is spanned by a membrane M for absolute pressure detection (ü berspannen), wherein the membrane M has a male pattern on its underside
The electrode ST of (a). Above the outside of the functional layer assembly FS is deposited a closing layer V which closes the through opening D, D ″ which is located on the side of the film and opens into the cavity K. The transverse extent of the through opening D, D "is much smaller than the transverse extent of the cavity K located therebelow.
Fig. 5a) shows the state immediately after the deposition of the sealing layer V, wherein a predetermined reference pressure P0 is sealed in the cavity K.
Next, with reference to fig. 5b), the closing layer V is partially removed, so that only the closing regions VS, VS "remain plug-like in the through-openings D, D".
As illustrated in fig. 5c), the external pressure P loaded on the membrane causes the membrane to deform in the direction of the substrate S. Here, the male die electrode ST is close to the substrate S, and the absolute pressure can be capacitively detected by means of the substrate electrode (not shown).
For the production of the MEMS structures shown in fig. 5a) to c), there are many different possibilities in micro-mechanics. The standard method is, for example, to apply and structure functional and sacrificial layers of different micromachines on the substrate S. The sacrificial layer is next removed by an etching process through the through opening D, D ".
It is also possible to provide two or more substrates having recesses and to connect these substrates to one another by means of a bonding method.
These two basic methods can be combined with each other in any way.
It is important in the deposition of the closing layer V that a low pressure P0, typically well below 1 bar, is closed in the cavity.
The through openings D, D "are also typically implemented as narrow channels, and they have the additional function of electrically separating the conductive layers. The electrically insulating properties can additionally be achieved by means of oxide deposition, nitride deposition or oxynitride deposition.
L PCVD or PECVD oxide deposition or nitride deposition is particularly suitable for the sealing process.
For example, L PCVD with TEOS may be used, TEOS is directed through the MEMS structure to be enclosed at a low pressure of typically 300 mTorr at a temperature of typically 700 deg.C
And (4) depositing. Uniformity describes the growth ratio of layers in the vertical plane relative to the horizontal plane at the time of deposition. In principle, there is no preferred direction in the case of this growth method, and therefore a consistency equal to 1 is theoretically expected at very low working pressures and high flows. But due to TEOS depletion in narrow trenches or through openings at operating pressures that still enable reasonable layer growth rates, not completely uniform deposition, but only near uniform deposition.
In addition, even at lower temperatures of 250 ℃ to 350 ℃, it is possible to deposit oxide layers by means of plasma support consisting of TEOS or silane (Plasmaulterst ü tzung). Wherein principle, only a lower uniformity can be achieved by means of this method due to the plasma support and the directional deposition components associated therewith.
With a very high consistency, it is possible to close narrow inlets with a relatively low layer thickness. At lower consistencies, very high layer thicknesses are required to close narrow channels or narrow through openings.
Fig. 6a) -c) are schematic partial cross-sectional views for illustrating an exemplary method of manufacturing a MEMS structure, wherein the deposition of the closing layer has a consistency ideally equal to one.
In fig. 6a) -c), only the area a of fig. 5a) -c) is shown for reasons of simplicity. Fig. 6a) -c) show that, in the case of a deposition with a desired uniformity equal to 1, a closing layer V1 with a layer thickness D1 is required, which corresponds exactly to half the width B2 of the through-opening D. Therefore, the through opening D is closed by the closed region VB over the entire height.
The disadvantage here is that the entire layer thickness d1 is also deposited in the cavity K, while the thickness d2 is deposited in some regions. It may therefore happen that: the movability of the film M is restricted or hindered. The high performance of other functional elements may also be hampered by the sealing layer V1 deposited in the cavity K.
Fig. 7a) -c) are schematic partial cross-sectional views for illustrating an exemplary method of manufacturing a MEMS structure, wherein the deposition of the closing layer has a high uniformity close to unity.
Similarly to fig. 6a) -c), it can be seen in fig. 7a) -c) that the time course of the closure in the through-openings D in the region a is changed when depositing a closure layer V2 of high consistency, which is achieved, for example, when depositing L PCVD, a layer thickness D1 'approximately corresponding to the width D2 of the through-openings D is required to close the through-openings D, the closure region VB' is located in the oxide of the closure layer V2 above the through-openings D due to the depletion of TEOS in the through-openings D, also in the case of this closure method a relatively thick closure layer V2 is deposited in the cavity K, which may have a negative effect on the function of the components in the cavity K.
Fig. 8a) -c) are schematic partial cross-sectional views for illustrating an exemplary method of fabricating a MEMS structure, wherein the deposition of the closing layer has a low uniformity of less than one.
The closing in time of the narrow channel or through opening D in the region a, in which the closing layer V3 is deposited with a low consistency, such as PECVD deposition provides this low consistency, can be seen in fig. 8a) -c).
In order to close the through-opening D by means of the closing layer VB ", a layer thickness D1" is required which is much larger than the width D2 of the through-opening D. This closed region VB "in the oxide of the closed layer V3 lies well above the through opening D due to the low uniformity of the deposition. The required thickness d1 ″ of the closing layer V3 is therefore disadvantageous, but it is advantageous if relatively little oxide of the closing layer V3 is deposited in the cavity K, and therefore the function of the components in the cavity K is not affected or is only slightly affected.
In general, therefore, a relatively large layer thickness of the closure layer is required in the described method, but this is not desirable because it has a different thermal expansion coefficient compared to the silicon of the functional layer assembly FS, causing bending and stress in the MEMS, compared to thermal oxide, L PCVD oxide and especially PECVD oxide has a lower density and a tendency to form cracks (risse) at higher temperatures, which causes a risk of leakage of the closure region.
It is also generally desirable to remove the oxide in areas where there is no oxide confinement, for example to achieve stress-free areas of the film M. However, since the closed regions lie above the through-openings and the oxide located there cannot be removed, very high surface shapes (topographies) are produced on the surface, which are disadvantageous for further process steps.
Finally, in the case of a consistency at the sealing zone not equal to 1, a deeper notch (Kerbe) is usually made on the lower layer and a shallower notch is made on the upper side of the sealing zone, which results in the sealing zone having an intended breaking point (sollbruchsellen) when strained or bent, since an overpressure is generated there.
DE 102009045385 a1 and DE 102010000895 a1 describe a method for closing a channel of a micromechanical component by means of a lattice structure.
EP 2637007 a1 describes a capacitive MEMS absolute pressure sensor device.
US 6,261,957B 1 discloses a self-planarizing trench filling method using HD-PCVD.
Disclosure of Invention
The invention relates to a method for producing a MEMS structure according to the invention and to a corresponding MEMS structure according to the invention.
Preferred embodiments are the subject matter of the corresponding dependent claims.
THE ADVANTAGES OF THE PRESENT INVENTION
The idea on which the invention is based consists in applying a closing layer deposited with a very low uniformity, so that the material of the closing layer (for example oxide) is not deposited at the edges. In particular, HDP layer deposition with sputtered portions (Sputteranteil) is proposed. An "HDP layer" is to be understood here as a high-density plasma layer which can be used, for example, as a passivation layer, wherein the HDP layer is formed by means of a Chemical Vapor Deposition (CVD) method. If no sealing material grows laterally in the through-opening, the through-opening can be sealed off from the underside and can also be completely filled if required.
On the one hand, the disadvantages of the prior art can thus be avoided, while on the other hand, an HDP sealing material (e.g. HDP oxide) is a very tight sealing material which has only a very low tendency to crack compared to PECVD sealing materials or L PCVD sealing materials.
The method according to the invention offers great advantages in terms of costs due to the very high deposition rate in the HDP method. The HDP deposition process can be used both at the front end (front) and at the back end (Backend) and therefore a high process flexibility can be achieved. The closed area that can be achieved by the method according to the invention is stable and tight. Due to the small surface shape, it can be used simply in combination with other process steps.
According to a preferred embodiment, the substrate below the cavity is exposed, wherein the second region is grown on the exposed substrate. This enables the formation of a large number of stable closed areas.
According to a further preferred embodiment, an auxiliary layer is arranged below the through-opening, which auxiliary layer is surrounded by the cavity and overlaps the through-opening, wherein the second region is grown on the auxiliary layer. This enables accelerated formation of closed areas that require less closed layer volume.
According to a further preferred embodiment, the auxiliary layer is suspended laterally in the functional layer arrangement in a self-supporting manner (free) and/or the auxiliary layer is suspended laterally in the functional layer arrangement by means of spring elements. This enables balancing of internal stresses.
According to a further preferred embodiment, the through-opening has a first funnel shape adjoining the outside
A region and a second channel-like region below the first funnel-like region. This can accelerate the formation of the enclosed area.
According to a further preferred embodiment, the first region of the sealing layer is at least partially removed on the outside of the functional layer arrangement. This enables a planar surface shape.
According to a further preferred embodiment, an etch stop layer is applied to the functional layer arrangement on the outer side below the sealing layer, wherein the first region of the sealing layer is completely removed. This enables the first region of the sealing layer to be removed effectively without damaging the functional layer arrangement.
According to a further preferred embodiment, the etch stop layer is removed after the removal of the first regionRemoving, and then etching the second region from above
So that the outer side of the plane of the functional layer assembly is obtained. This achieves a particularly planar surface shape.
According to a further preferred embodiment, the HDP method has a reverse sputtering section and has a consistency of 0.2 or less. This ensures an effective and rapid construction of the enclosed area.
According to a further preferred embodiment, the sealing layer has an oxide layer and/or a nitride layer and/or an oxynitride layer. Such layers can be deposited particularly well by means of the HDP method.
Drawings
The features and advantages of the invention are explained below with reference to the drawings according to embodiments. The figures show:
fig. 1a) -g) show schematic partial cross-sectional views for explaining a manufacturing method for a MEMS structure according to a first embodiment of the invention;
fig. 2a) -g) show schematic partial cross-sectional views for explaining a manufacturing method for a MEMS structure according to a second embodiment of the invention;
fig. 3a) -i) show schematic partial cross-sectional views for explaining a manufacturing method for a MEMS structure according to a third embodiment of the invention;
fig. 4a) -c) show schematic partial cross-sectional views for explaining a manufacturing method for a MEMS structure according to a fourth embodiment of the invention;
fig. 5a) -c) show schematic cross-sectional views for elucidating an exemplary method of manufacturing a MEMS structure in the form of an absolute pressure sensor device and the manner of action thereof;
fig. 6a) -c) show schematic cross-sectional views for illustrating an exemplary manufacturing method of a MEMS structure, wherein the deposition of the closing layer has a consistency ideally equal to one;
FIGS. 7a) -c) show schematic cross-sectional views illustrating an exemplary fabrication method for a MEMS structure, wherein the deposition of the closing layer has a high uniformity close to unity;
fig. 8a) -c) show schematic cross-sectional views for illustrating an exemplary manufacturing method of a MEMS structure, wherein the deposition of the closing layer has a low uniformity of less than one.
Detailed Description
In the drawings, identical or functionally identical elements are provided with the same reference numerals.
Fig. 1a) -g) are schematic partial cross-sectional views for explaining a manufacturing method for a MEMS structure according to a first embodiment of the present invention.
According to fig. 1a) to g), a substrate S is provided, on which a micromechanical functional layer assembly FS is applied, which has one or more functional layers. The substrate S is for example a silicon wafer substrate, while the functional layer assembly FS comprises one or more functional layers, for example consisting of polysilicon, oxide, nitride, metal, etc. The functional layer assembly FS has a cavity K with a smaller lateral extension than the functional layer assembly FS. According to fig. 1a), the through-opening is exposed towards the outside of the functional layer assembly FS.
The cavity K is spanned by a membrane M for absolute pressure detection, wherein the membrane M has a male-like electrode ST on its underside, as already explained in fig. 5a) -c). Fig. 1a) -g) show the region a of fig. 5a) -c).
As fig. 1b) to g) show in sequence, a sealing layer O, O' made of an oxide is deposited by means of an HDP method on the outside of the functional layer assembly FS and over the through-opening D. Here, the first region O of the closing layer O, O ' grows on the outside of the functional layer assembly FS, and the second region O ' of the closing layer O, O ' grows cylindrically below the through opening D from inside the cavity K. During the HDP deposition, a closed region VBO is constructed in the through opening D from the side of the substrate S.
HDP deposition is a degenerate PECVD process. For deposition, very low gas pressures are used. At the same time, a high plasma power is used, the plasma potential being controlled in such a way that a reverse sputtering effect is produced on the MEMS structure. A large degree of ionization of the deposition gas, which in this example is TEOS, can be achieved by correspondingly selected parameters. A high deposition rate can thus be obtained with very low uniformity. The uniformity can be reduced to zero by the reverse sputtering portion in the plasma. The growth rate in the horizontal plane is greater than the reverse sputtering rate. The reverse sputtering rate is greater than the growth rate in the vertical plane, for example in the through-opening D. The balancing is adjusted on an inclined plane, wherein a flattened area (ablfachunen) with an inclination of typically about 45 ° is produced at the edge. A portion of the deposited material sputtered on the planarized area is in turn coated (under) at the bottom of the edge. This effect helps to be able to fill also deep trenches. Funnels are formed as layer deposition increases, which accelerates deposition in the channel.
In a preferred embodiment of the HDP deposition, the uniformity is less than 0.2. Preferably, a plasma power of greater than 2500 watts per square meter is used. The process pressure is typically below 50 mtorr.
Although an oxide layer is deposited as a sealing layer in the above-described embodiments, a nitride layer or an oxynitride layer can be deposited.
Fig. 2a) -g) are schematic partial cross-sectional views for explaining a manufacturing method for a MEMS structure according to a second embodiment of the present invention.
Fig. 2a) -g) show the region a of fig. 5a) -c).
As shown in fig. 2a) -g), in the second embodiment, an auxiliary layer HS suspended in a self-supporting manner transversely in the functional layer assembly FS is provided below the through-opening D, which auxiliary layer is surrounded by the cavity K and overlaps the through-opening D. This enables the second region O 'of the sealing layer O, O' to grow on the auxiliary layer HS. Therefore, only a smaller volume portion of the second region O 'of the encapsulation layer O, O' is required in order to create the encapsulation layer VBO. This can be adjusted by the distance a1 between the auxiliary layer HS and the lower end of the through-opening D. A distance a1 which is smaller than the other distances a2 in the cavity K can be selected here.
Therefore, the formation of the closed region VBO is accelerated in the second embodiment as compared with the first embodiment.
The auxiliary layer HS can be integrated in one of the functional layers of the functional layer assembly FS or already present in some MEMS processes.
Fig. 3a) -i) are schematic partial cross-sectional views for explaining a manufacturing method for a MEMS structure according to a third embodiment of the present invention.
Fig. 3a) -i) show the region a of fig. 5a) -c).
As shown in fig. 3a) -i), the auxiliary layer HS in the third embodiment is suspended laterally in the functional layer assembly FS by means of spring elements FE. Such spring elements are capable of absorbing stresses in the closure layer O, O'. By the self-supporting boundary in the horizontal direction, a part of these stresses in the auxiliary layer HS can relax in the direction of the spring element FE, whereby a very robust closed region VBO can be ensured.
In the third embodiment, the etch stop layer ES is deposited on the outer side of the functional layer assembly FS before the HDP deposition is carried out, and the HDP deposition is not carried out until then.
Referring to fig. 3g) -i), this enables the removal of the unwanted oxide of the first region O of the sealing layer O, O' from the unwanted region on the outside. This can be achieved by means of a CMP step, which stops on the etch stop layer ES. If, as shown in fig. 3i), the etch stop layer ES is thereafter removed and the oxide of the second region O' is slightly etched back, a particularly planar outer side of the functional layer assembly FS can be produced, which is particularly suitable for further processing.
Fig. 4a) -c) are schematic partial cross-sectional views for explaining a manufacturing method for a MEMS structure according to a fourth embodiment of the present invention.
Fig. 4a) -c) show the region a of fig. 5a) -c).
In the fourth embodiment according to fig. 4a) -c), the through-opening D' has a first funnel-shaped region TB, which adjoins the outside of the functional layer assembly FS. The first funnel TB is connected to the second channel KB. The first funnel region TB may be created by a long first isotropic etching step. By means of the first funnel region TB, the filling of the oxide is accelerated already at a very early stage of the layer deposition by HDP deposition. The second channel-like region KB can be closed by the closing region VBO in the vicinity of the surface.
Optionally, after the process state shown in fig. 4c), a cover layer SC (for example a nitride layer) is also deposited above the closure region and is structured such that it covers the closure layer VBO and thus additionally seals the closure layer.
Although the present invention has been described based on preferred embodiments, the present invention is not limited thereto. In particular, the materials and surface shapes mentioned are exemplary only and are not limiting to the examples set forth.
Although in the above embodiments, the closed region for forming the defined air pressure is formed within the absolute pressure sensor apparatus, the present invention is not limited thereto, but can be applied to any closed region on any MEMS structure in principle.
Claims (16)
1. A method for fabricating a MEMS structure, the method having the steps of:
providing a substrate (S) on which a micromechanical functional layer assembly (FS) is applied, said functional layer assembly having one or more functional layers, wherein the functional layer assembly (FS) has a cavity (K) which is exposed to the outside of the functional layer (FS) via a through-opening (D; D'), wherein the through-opening has a smaller lateral extent than the functional layer assembly (FS);
depositing a sealing layer (O, O ') by means of an HDP method on the outside of the functional layer assembly (FS) and above the through-opening (D; D') in such a way that a first region (O) of the sealing layer (O, O ') grows on the outside of the functional layer assembly (FS) and a second region (O') of the sealing layer (O, O ') grows from inside the cavity (K) in a columnar manner below the through-opening (D; D');
wherein a sealing region (VBO) is formed in the through-opening (D; D ') by the second region (O ') of the sealing layer (O, O ').
2. Method according to claim 1, wherein the substrate (S) below the cavity (K) is exposed and the second region (O') is grown on the exposed substrate (S).
3. Method according to claim 1, wherein an auxiliary layer (HS; HS ') is provided below the through opening (D; D'), which auxiliary layer is surrounded by the cavity (K) and overlaps the through opening (D; D '), wherein the second region (O') is grown on the auxiliary layer (HS).
4. Method according to claim 1, wherein the auxiliary layer (HS ') is suspended laterally in the functional layer assembly (FS) self-supporting and/or wherein the auxiliary layer (HS') is suspended laterally in the functional layer assembly (FS) by means of spring elements (FE).
5. Method according to any one of the preceding claims, wherein the through opening (D') has a first funnel-shaped region (TB) adjoining the outer side and a second channel-shaped region (KB) below the first funnel-shaped region (TB).
6. Method according to any one of the preceding claims, wherein the first area (O) of the closing layer (O, O') is at least partially removed on the outside of the functional layer assembly (FS).
7. Method according to claim 6, wherein an etch stop layer (ES) is applied on the functional layer assembly (FS) on the outer side below the closing layer (O, O ') and the first area (O) of the closing layer (O, O') is completely removed.
8. Method according to claim 6, wherein the etch stop layer (ES) is removed after the removal of the first region (O) and the second region (O') is subsequently etched from above, thereby obtaining the outer side of the plane of the functional layer assembly (FS).
9. The method according to any of the preceding claims, wherein the HDP process has a reverse sputtering section and has a uniformity of 0.2 or less.
10. Method according to any of the preceding claims, wherein the closing layer (O, O') has an oxide layer and/or a nitride layer and/or an oxynitride layer.
11. A MEMS structure, the MEMS structure having:
a substrate (S) on which a micromechanical functional layer assembly (FS) is applied, which functional layer assembly has one or more functional layers, wherein the functional layer assembly (FS) has a cavity (K) which extends through a through-opening (D; D') towards the outside of the functional layer assembly (FS), wherein the through-opening has a smaller lateral extent than the functional layer assembly (FS);
a sealing layer (O, O ') having a first region (O ') which is formed in the interior of the cavity (K) in a cylindrical manner below the through-opening (D; D ') and in which a sealing region (VBO) is formed.
12. The MEMS structure according to claim 11, wherein the region (O') is configured on the exposed substrate (S).
13. The MEMS structure according to claim 11, wherein an auxiliary layer (HS) is provided below the through opening (D; D '), which auxiliary layer is surrounded by the cavity (K) and overlaps the through opening (D; D '), wherein the region (O ') is formed on the auxiliary layer (HS).
14. MEMS structure according to claim 13, wherein the auxiliary layer (HS) is laterally suspended free-standing in the functional layer assembly (FS) and/or wherein the auxiliary layer (HS) is laterally suspended in the functional layer assembly (FS) by means of spring elements (FE).
15. The MEMS structure of any one of claims 11 to 14, wherein the through opening (D') has a first funnel-shaped region (TB) contiguous with the outer side and a second channel-shaped region (KB) below the first funnel-shaped region (TB).
16. MEMS structure according to any of claims 11 to 15, wherein the MEMS structure comprises an absolute pressure sensor device and the through opening (D; D') is contiguous with a membrane (M) for absolute pressure detection, wherein the cavity (K) extends under the membrane.
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| Application Number | Priority Date | Filing Date | Title |
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| DE102019201236.1A DE102019201236B4 (en) | 2019-01-31 | 2019-01-31 | Method for producing a MEMS structure and corresponding MEMS structure |
| DE102019201236.1 | 2019-01-31 |
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| US6261957B1 (en) | 1999-08-20 | 2001-07-17 | Taiwan Semiconductor Manufacturing Company | Self-planarized gap-filling by HDPCVD for shallow trench isolation |
| DE102009045385B4 (en) | 2009-10-06 | 2019-07-04 | Robert Bosch Gmbh | Method for producing a contact and corresponding micromechanical component |
| DE102010000895B4 (en) | 2010-01-14 | 2018-12-27 | Robert Bosch Gmbh | A method of making a via of a semiconductor device having a surrounding annular isolation trench and corresponding semiconductor device |
| EP2637007B1 (en) | 2012-03-08 | 2020-01-22 | ams international AG | MEMS capacitive pressure sensor |
| US9452923B2 (en) * | 2012-12-20 | 2016-09-27 | Infineon Technologies Dresden Gmbh | Method for manufacturing a micromechanical system comprising a removal of sacrificial material through a hole in a margin region |
| DE102016217001B4 (en) * | 2016-09-07 | 2023-11-23 | Infineon Technologies Dresden Gmbh | Method for forming a microelectromechanical component with a support structure holding a lamella structure |
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