micro electro mechanical system

Abstract

The present disclosure relates to a microelectromechanical system comprising an ASIC layer, a mediator layer, a MEMS layer and a cover layer attached to each other. The MEMS system further comprises an isolated enclosure formed between the mediator layer and the cover layer, wherein the mediator layer comprises a measurement electrode inside the isolated enclosure. The present disclosure is advantageous in that the mediator layer comprises the measurement electrode without comprising the ASIC wafer, such that no structural modifications to the ASIC wafer are required. In addition, the structure of the disclosed MEMS system allows for arranging an isolated enclosure with a desired pressure inside.

Description

Technical Field

[0001] This disclosure relates to microelectromechanical systems (MEMS), and more particularly to systems having an ASIC layer integrated with a MEMS layer, having an intermediate layer with measurement electrodes located between the ASIC layer and the MEMS layer. This disclosure also relates to methods of manufacturing microelectromechanical systems. Background Technology

[0002] Microelectromechanical (MEMS) devices, such as those used to measure acceleration, rotational speed, magnetic fields, pressure, and / or combinations thereof, typically consist of a MEMS wafer and an ASIC wafer. A movable transducer structure resides within the MEMS wafer, and the ASIC wafer is designed to evaluate the measurement signals from the MEMS wafer. Traditionally, the MEMS wafer is attached to the ASIC wafer using a horizontally arranged bond that occupies design space.

[0003] To minimize the design space of MEMS devices, ASIC chips can be vertically integrated with the MEMS chip structure. However, when an ASIC chip is vertically attached to a MEMS chip, the ASIC chip needs to be modified to ensure that measurements from the MEMS layer are possible. It is desirable to avoid modifying the complex ASIC chip structure. Summary of the Invention

[0004] The purpose of this disclosure is to provide a MEMS system that addresses the aforementioned problems.

[0005] The purpose of this disclosure is achieved through a MEMS system characterized by the features described in the first aspect of this disclosure. Some implementation methods are also disclosed in this disclosure.

[0006] According to a first aspect of this disclosure, a microelectromechanical system (100) is provided, comprising:

[0007] - ASIC layer (101), wherein the ASIC layer includes control circuitry (102).

[0008] - Includes an intermediary layer (104) with a first side and a second side, wherein the ASIC layer (101) is bonded to the first side of the intermediary layer (104), and

[0009] - A MEMS layer (106) including a first side and a second side, wherein the second side of the interposer layer (104) is attached to the first side of the MEMS layer (106).

[0010] - A capping layer (109) attached to the second side of the MEMS layer (106).

[0011] in

[0012] - The intermediate layer (104) and the cover layer (109) form a first isolation shell (110), and the first isolation shell (110) has the MEMS layer (106) inside.

[0013] - And the MEMS layer (106) includes a first movable structure (107), wherein the first movable structure (107) is within the first isolation housing (110),

[0014] in

[0015] - The intermediary layer (104) includes a first measuring electrode (105) on the second side, wherein the first measuring electrode (105) is adjacent to the first movable structure (107) in the first isolation housing (110).

[0016] This disclosure is based on a concept of a MEMS system comprising an ASIC layer, an interposer layer, a MEMS layer, and a capping layer attached to each other. The MEMS system also includes an isolation housing formed between the interposer layer and the capping layer, wherein the interposer layer includes measurement electrodes inside the isolation housing.

[0017] The advantage of this arrangement is that the interposer includes the measurement electrodes, and no structural modifications to the ASIC chip are required. Furthermore, the structure of the disclosed MEMS system allows for the arrangement of an insulating shell with the desired internal pressure. Attached Figure Description

[0018] In the following, the present disclosure will be described in more detail with reference to the accompanying drawings, in which:

[0019] Figure 1 The MEMS structure of this disclosure is shown;

[0020] Figure 2a An example of a MEMS system including a second measuring electrode is shown;

[0021] Figure 2b An example of a movable MEMS system including a second insulating housing and a first movable structure is shown;

[0022] Figure 3a An example is shown where an external ASIC layer can be connected via an intermediary layer, a device layer, and a capping layer;

[0023] Figure 3b An example is shown where wire bonding can be used to connect to an external ASIC layer;

[0024] Figure 4 The manufacturing process of the MEMS system disclosed herein is illustrated. Detailed Implementation

[0025] The microelectromechanical system (MEMS) includes: an ASIC layer, wherein the ASIC layer includes control circuitry; an interposer layer including a first side and a second side, wherein the ASIC layer is bonded to the first side of the interposer layer; and a MEMS layer including a first side and a second side, wherein the second side of the interposer layer is attached to the first side of the MEMS layer; and a capping layer attached to the second side of the MEMS layer, wherein the interposer layer and the capping layer form a first isolation housing, the first isolation housing having the MEMS layer inside, and the MEMS layer including a first movable structure, wherein the first movable structure is within the first isolation housing, wherein the interposer layer includes a first measurement electrode on the second side, wherein the first measurement electrode is adjacent to the first movable structure in the first isolation housing.

[0026] The microelectromechanical (MEMS) system 100 disclosed herein is in Figure 1 As shown in the diagram, it includes an ASIC layer 101. The ASIC layer includes control circuitry 102. ASIC layer 101 may include a first layer and a second layer attached to one another. The first layer may be an ASIC substrate 103. The second layer may be the control circuitry 102. ASIC layer 101 may include a first side and a second side. The first side may correspond to the ASIC substrate 103. The second side may correspond to the control circuitry 102.

[0027] ASIC layer 101 may include ASIC conductive elements on the second side, such as... Figure 2b 201 and 216 are shown in the diagram. Some ASIC conductive elements (such as 201) can be used to bond the ASIC layer to the interposer (described later). Some ASIC conductive elements (such as 216) can be used to electrically connect portions of the interposer to the ASIC layer.

[0028] The MEMS system 100 also includes an interposer layer 104. The interposer layer 104 includes a first side and a second side opposite to each other. The second side of the ASIC layer 101 is attached to the first side of the interposer layer 104. The ASIC layer 101 is attached to the first side of the interposer layer 104 by bonding. Specifically, the ASIC layer 101 can be attached to the first side of the interposer layer 104 by metal bonding. The bonding can occur at the bonding points, for example... Figure 1 The 113 locations were inspected.

[0029] like Figure 2bAs shown, the interposer 104 may include a first insulating layer 202. The first insulating layer 202 may be attached to the underlying MEMS layer (described later). The interposer 104 may also include a first conductive layer 203 above the first insulating layer 202. The interposer 104 may include a second insulating layer 204 above the first conductive layer 203. The interposer 104 may include further alternating insulating and conductive layers. The insulating layer may be made of silicon oxide. The conductive layer may be made of polysilicon. The conductive layer may be made of metal. The layered structure of the interposer allows for the addition of numerous routing paths for connecting the ASIC layer to the rest of the MEMS system.

[0030] Intermediate layer 104 may include an intermediate layer conductive element on the first side, such as Figure 2b As shown in Figures 205 and 206. Some interposer conductive elements (e.g., 205) can be used to bond the interposer to the ASIC layer. Other interposer conductive elements (e.g., 206) can be used to route signals from the interposer to the ASIC layer.

[0031] like Figure 1 As shown, the interposer 104 includes a first measurement electrode 105 on its second side. The material of the first measurement electrode 105 may be polysilicon. The first measurement electrode 105 may not be patterned. Alternatively, the first measurement electrode 105 may be pre-patterned, for example by providing notches, slots, openings, grooves, trenches, or through-holes. The structure of the MEMS system 100 allows the first measurement electrode 105 to be disposed at the interposer 104 within the MEMS system 100 without requiring any modification to the ASIC layer 101 and simplifying the manufacturing process.

[0032] like Figure 2a As shown, the intermediary layer 104 may include a recess on the second side, which may form the upper detection gap 111.

[0033] MEMS system 100 also includes a MEMS layer 106. MEMS layer 106 includes a first side and a second side. The second side of an interposer layer 104 is attached to the first side of MEMS layer 106. The interposer layer 104 can be attached to MEMS layer 106 by bonding. Alternatively, the interposer layer 104 can be deposited on MEMS layer 106. In this case, the interposer layer 104 must be partially released from MEMS layer 106 after deposition, allowing the movable structure of MEMS layer 106 to move.

[0034] MEMS layer 106 may define a device plane. The device plane may also be referred to as a horizontal plane or an xy-plane. A direction perpendicular to the device plane may be referred to as a vertical direction or a z-direction. Terms such as “horizontal,” “vertical,” “bottom,” “top,” “above,” and “below,” etc., in this disclosure, whether during the manufacture or use of the device, do not refer to the orientation of the device relative to the Earth's gravitational field. Instead, the term “horizontal” simply defines a plane, while “vertical” defines a direction perpendicular to that plane. Other terms then refer to the relative position within that “vertical” direction.

[0035] MEMS layer 106 includes a first movable structure 107. MEMS layer 106 may include movable portions other than the first movable structure 107. Additionally, MEMS layer 106 may include static portions (not shown). The static portions always remain stationary relative to the surrounding portions of MEMS system 100. The first movable structure may be attached to the static portion using a flexible spring, which allows the movable structure to move relative to the static structure. The flexible spring may also be referred to as a hanger. The static portion of the MEMS layer may define a device plane. Alternatively, the movable portions in an unactuated state may define a device plane.

[0036] MEMS layer 106 can be formed from a silicon wafer. The silicon can be doped, and MEMS layer 106 can actually be conductive.

[0037] like Figure 1 As shown, the MEMS layer 106 may include an upper detection gap 111 formed by recessing a first side. The MEMS layer 106 may include a lower detection gap 112 formed by recessing a second side. The recesses can be created using a variety of different etching methods. In some applications, performing the recesses in a localized oxidation of silicon (LOCOS) process is particularly advantageous. This allows for very precise control over the height of the lower gap. The height of the upper detection gap 111 in the z-direction can be equal to the height of the lower detection gap 112 in the z-direction.

[0038] The heights of the upper detection gap 111 and the lower detection gap 112 in the z-direction can be from 0.9 μm to 3.0 μm. The heights of the upper detection gap 111 and the lower detection gap 112 in the z-direction can be from 1.4 μm to 2.4 μm. For both the upper detection gap 111 and the lower detection gap 112, the gap height tolerance can be less than + / - 40 nm.

[0039] MEMS layer 106 may include vias (not shown). A via is a set of relatively small holes extending through MEMS layer 106 in the z-direction. The vias may be etched into movable structures 107 or 108 (measuring areas) within MEMS layer 106, but they may alternatively be located elsewhere. The optimal location and size of the vias depend on the geometry of the device and the thickness of the first insulating layer 202.

[0040] The MEMS system 100 also includes a capping layer 109. The capping layer 109 is attached to a second side of the MEMS layer 106. The capping layer 109 may include a first side that can be attached to the MEMS layer 106. The capping layer 109 can be attached to the MEMS layer 106 by bonding. The capping layer 109 can be attached to the MEMS layer 106 by anodic bonding. The capping layer 109 may include a second side opposite to the first side.

[0041] The cover layer 109 may include a cover recess (not shown) in a first surface. Specifically, the cover recess may be in a first insulating housing 110 (described later). The depth of the cover recess in the z-direction may be from 10 μm to 30 μm. Specifically, the depth of the cover recess in the z-direction may be greater than 10 μm or less than 30 μm. This recess is particularly useful when the first movable structure 107 is part of an accelerometer structure, to provide more space for out-of-plane movement.

[0042] The ASIC layer 101, the interposer layer 104, the MEMS layer 106, and the capping layer 109 can be attached to each other in the vertical direction in the described order.

[0043] Intermediate layer 104 and capping layer 109 form a first isolation housing 110, which has a MEMS layer 106 inside. In other words, a portion of the MEMS layer 106 may be within the first isolation housing 110. The term "isolation" may mean that the housing is hermetically sealed from the external environment and from another housing (if more than one housing exists).

[0044] Specifically, the pressure within the first isolation enclosure 110 can be a vacuum. The pressure within the first isolation enclosure 110 can be from 0.4 mbar to 1.1 mbar. The pressure within the first isolation enclosure 110 can be from 1250 mbar to 2000 mbar. The gas within the first isolation enclosure 110 can be pure argon. Other rare gases, such as neon and helium, can also be used. Nitrogen (N2) can also be used.

[0045] The first movable structure 107 can be located within the first isolation housing 110.

[0046] Microelectromechanical systems (MEMS) in which the ASIC layer and the interposer layer can form a second isolation enclosure.

[0047] Microelectromechanical systems, wherein the pressure in the first isolation enclosure may differ from the pressure in the second isolation enclosure.

[0048] like Figure 2b As shown, the ASIC layer 101 and the interposer layer 104 can form a second isolation housing 211.

[0049] The pressure in the first isolation housing 110 can differ from the pressure in the second isolation housing 211. The pressure in the first isolation housing 110 can be lower than the pressure in the second isolation housing 211. The manufacturing process of the MEMS system (described below) allows for different pressures to be provided in the first and second isolation housings. Pressure setting is reliable and efficient in the manufacturing process because it does not require any additional structural modifications to the MEMS system. Pressure is set when bonding the ASIC layer to the interposer (e.g., using metal bonding) and when bonding the capping layer to the MEMS layer (e.g., using anodic bonding).

[0050] MEMS systems may include connection points, for example Figure 2a Connection points 214 and 215. Connection points 214 and 215 may include ( Figure 2b ASIC conductive components 201 and 216, ( Figure 2b (in) intermediate conductive element 206 and ( Figure 2b The metal bonding element 210 electrically connects the ASIC conductive element and the interposer conductive element.

[0051] Microelectromechanical systems (MEMS) in which a first measurement electrode can be connected to an ASIC layer via a first measurement via in an interposer layer.

[0052] The first measuring electrode 105 is located within the first isolation housing 110. The first measuring electrode 105 is adjacent to the first movable structure 107 in the z-direction. The first measuring electrode 105 can be accessed via a first measuring through-hole (e.g., ...). Figure 2a 209 shown in the diagram is connected to connection point 214 (or specifically, as shown in the diagram). Figure 2b (The intermediate conductive element 206 in the middle). The first measuring electrode 105 can be configured to measure the out-of-plane displacement of the first movable structure 107. Specifically, the out-of-plane displacement of the first movable structure 107 can be measured using the capacitance change in the first measuring electrode 105. The first movable structure 107 can be used as one of the electrodes of a capacitor, and the first measuring electrode 105 can be the first anti-electrode of the capacitor.

[0053] like Figure 2b As shown, the first movable structure 107 can be configured to move outside the device plane. Figure 2bIn this configuration, the first movable structure 107 rotates outside the device plane. Specifically, the first movable structure 107 can be configured to rotate about a first rotation axis. The first rotation axis can be located within the device plane. Figure 2b As shown, the first axis of rotation can be along the x-direction and pass through point 217. Alternatively, the first movable structure 107 can be configured to perform a linear translation in the z-direction (not shown).

[0054] The advantage of having an interposer layer 104 between the ASIC layer 101 and the MEMS layer 106 is that it provides design freedom for the arrangement of the movable structure 107 and the first measurement electrode 105 with excellent electrical performance. The interposer layer 104 provides low parasitic capacitance and a built-in bias environment for sensitive signal detection. Without the interposer layer 104, out-of-plane detection would need to be performed against the second surface of the ASIC layer 101, which is difficult and expensive because it requires accommodating a large and electrically unaffected detection electrode on the second surface of the ASIC layer 101.

[0055] A microelectromechanical system (MEMS) wherein a cover layer may include a first side attached to a MEMS layer, and the cover layer may also include a second measurement electrode on the first side, wherein the second measurement electrode may be adjacent to a first movable structure in a first insulating housing.

[0056] Microelectromechanical systems (MEMS) in which the second measurement electrode can be connected to the ASIC layer via the MEMS layer and the interposer layer.

[0057] Microelectromechanical systems, wherein the first measuring electrode may be polycrystalline silicon.

[0058] Microelectromechanical systems, wherein the first measuring electrode and / or the second measuring electrode may be metal.

[0059] like Figure 2a As shown, the cover layer 109 may include a second measuring electrode 207 on its first side. The second measuring electrode 207 may be located within the first insulating housing 110. The second measuring electrode 207 may be adjacent to the first movable structure 107 in the z-direction.

[0060] The second measurement electrode can be connected to the ASIC layer via the MEMS layer and the interposer layer. The second measurement electrode 207 can be connected via a second measurement via (e.g., Figure 2a 208 in the diagram is connected to ASIC layer 101. A second measurement via, such as 208, can be disposed in the MEMS layer and the interposer layer. The second measurement via, such as 208, can terminate at connection point 215 (or an interposer conductive element, such as...). Figure 2b (at position 206 in the text).

[0061] For example Figure 2bAs shown in the diagram. The second measuring electrode 207 can be configured to measure the out-of-plane displacement of the first movable structure 107. In other words, both the first measuring electrode 105 and the second measuring electrode 207 can be configured to measure the out-of-plane displacement of the first movable structure 107 within the first isolation housing 110. Specifically, the out-of-plane displacement of the first movable structure 107 can be measured using the capacitance change in the first measuring electrode 105 and the second measuring electrode 207. Specifically, the first movable structure may include a first measuring region facing the first measuring electrode 105 and a second measuring region facing the second measuring electrode 207. The first measuring region and the second measuring region may be aligned one over the other along the z-direction. The first measuring region of the first movable structure 107 (e.g., made of monocrystalline silicon) can serve as the first electrode of a capacitor, and the first measuring electrode 105 can serve as the first anti-electrode of the capacitor. The second measuring region of the first movable structure 107 can serve as the second electrode of a capacitor, and the second measuring electrode 207 can serve as the second anti-electrode of the capacitor.

[0062] The advantage of using the same first movable structure 107 to align the first and second measurement regions is that it facilitates differential measurement. The capacitance measured across the first measurement gap to the first measurement electrode 105 can be labeled C1, and the capacitance measured across the second measurement gap to the second measurement electrode 207 can be labeled C2. When the first and second measurement regions are aligned one over the other, movement of the first movable structure 107 in the positive z-direction (upward in the figure) decreases C1 and increases C2, while movement in the negative z-direction (downward) increases C1 and decreases C2. The differential capacitance DC = C1–C2 will generally exhibit a stronger linear dependence on the mass displacement compared to either of the two capacitances alone.

[0063] Primarily, the measuring gap and measuring electrodes can be used for out-of-plane displacement detection as discussed above. However, the measuring gap and measuring electrodes can also be used for actuation of movable structures.

[0064] The first measuring electrode 105 can be made of polycrystalline silicon. The first measuring electrode 105 and the second measuring electrode 207 can be made of metal. Specifically, the second measuring electrode 207 can be made of aluminum. The thickness of the aluminum second measuring electrode 207 can be 80 nm. The aluminum second measuring electrode 207 may also include a 50 nm insulating diamond-like carbon (DLC) layer thereon.

[0065] Microelectromechanical systems (MEMS) in which the ASIC layer can be electrically connected to the capping layer via ASIC vias in the interposer layer and the MEMS layer, and signals from the ASIC layer can be routed from the capping layer to the outside of the MEMS system.

[0066] Figure 3a An example of how signals from a MEMS system 100 can be routed to the outside is shown. In this example, an ASIC layer 101 can be electrically connected to a cap layer 109 via ASIC vias, such as, for example, ASIC TSVs. Figure 3a The schematic diagram is shown as 301. The ASIC via 301 can be arranged to pass through the interposer layer 104 and the MEMS layer 106 to reach the capping layer 109.

[0067] The capping layer 109 may be made of silicon and may be doped to make it conductive. The capping layer 109 may include a first vertical electrical contact (not shown) extending from a first side to a second side. The first vertical contact can be electrically isolated from other portions of the capping layer by insulating the capping region. The first vertical contact may be connected to an output contact pad, such as 302.

[0068] An ASIC via 301 may terminate at an output contact pad 302 on a second side of the capping layer 109. The output contact pad 302 may be electrically connected to the outside of the MEMS system 100. For example, the capping layer 109 may include conductive solder balls 303 on its second side, which may be connected to an external printed circuit board (PCB, not shown). The MEMS system 100 may include a number of arrangements including ASIC vias (e.g., 301), output contact pads (e.g., 302), and conductive solder balls (e.g., 303).

[0069] The advantage of this arrangement is that, since all electrical connections are arranged vertically, the lateral space required in the design of the MEMS system is reduced.

[0070] Microelectromechanical systems (MEMS) are systems in which signals from the ASIC layer to the outside of the MEMS system can be configured to be routed directly from the ASIC layer.

[0071] Microelectromechanical systems (MEMS) are systems in which signals from the ASIC layer to the outside of the MEMS system can be configured to be routed via wires connected to the ASIC layer.

[0072] Alternatively, signals can be routed directly from ASIC layer 101 to the outside of MEMS system 100, such as... Figure 3b As shown in the diagram. Specifically, the ASIC layer 101 may include an output electrode 304 on the second side. The output electrode 304 may be electrically connected to an external electronic device 306 via, for example, wire bonding 305. In this arrangement, the capping layer 109 may be passive and does not include conductive elements. Alternatively, the capping layer 109 may include conductive elements ( Figure 3b(not shown in the diagram), the conductive elements are electrically connected to the MEMS layer 106, the interposer layer 104 and / or the ASIC layer 101, but are not directly electrically connected to the outside of the MEMS system 100.

[0073] The advantage of this arrangement is that it simplifies the manufacturing process of MEMS systems because fewer vias are needed for internal signal routing. Another benefit of routing signals directly from the ASIC layer via wire bonding is that less mechanical stress is generated on the MEMS structure because there are no solder ball assemblies on the external printed circuit board.

[0074] The first movable structure can be a gyroscope.

[0075] A gyroscope is a device used to detect and measure changes in the angular velocity and orientation of an object. Traditional MEMS gyroscopes include a movable test mass, such as... Figure 1 The first movable structure 107 typically comprises a portion of a silicon wafer. A movable test mass is suspended from a fixed element, typically a fixed portion of the same wafer. The test mass is connected to a force transducer, which drives the test mass into oscillating motion. As the gyroscope undergoes angular rotation, the Coriolis effect causes the oscillation of the movable test mass to be modulated. This oscillation modulation is proportional to the angular rate of the gyroscope, and the magnitude of the angular rotation rate can be determined.

[0076] When the first movable structure is a gyroscope, the first and second measuring electrodes can be used for quadrature signal compensation, that is, by applying corresponding voltages to adjust the movement of the movable structure in the undesired direction.

[0077] If the first movable structure 107 is a gyroscope, the pressure in the first isolation housing 110 can be a vacuum.

[0078] The first movable structure can be an accelerometer.

[0079] An accelerometer is a device used to detect and measure the magnitude of the acceleration of an object. In traditional MEMS accelerometers, such as... Figure 1 The mass element of the first movable structure 107 is suspended from a fixed structure by a flexible suspension spring. When an external force is applied to the accelerometer, causing it to accelerate, the mass element displaces from its rest position. The magnitude of the acceleration can be determined by measuring the magnitude of this displacement using a force transducer. Ideally, the accelerometer should not generate any output signal when it undergoes steady-state motion.

[0080] The second isolation housing 211 may include a first protrusion 212, such as Figure 2bAs shown in the diagram. A first bump 212 may be located on a first side of the capping layer 109. The purpose of the first bump 212 may be to mechanically stop the movement of the first movable structure 107 in the first isolation housing 110 before the capacitor is electrically short-circuited. The first bump 212 may be particularly useful if the first isolation housing 110 includes an accelerometer. Another purpose of the first bump 212 is to prevent the MEMS layer 106 from bonding to the structure of the capping layer 109 during anodic bonding. During the anodic bonding of the capping layer 109 and the MEMS layer 106, the capping layer 109 (which may be alkaline glass) is biased to a high voltage, while the silicon of the MEMS layer 106 remains at a ground potential. This potential difference generates a strong electrostatic field that pulls all movable structures of the MEMS layer 106 toward the capping layer 109. The first bump 212 at the capping layer 109, which may consist of silicon dioxide covered with DLC, can prevent permanent bonding of the MEMS layer 106 structure to the capping layer 109. The ultimate purpose of the first bump 212 may be for electrical testing. The first movable structure 107 can undergo a pull-in test (against a stop bump) during the final detection, thereby enabling the characterization of various functional characteristics of the MEMS gyroscope and / or MEMS accelerometer.

[0081] Intermediate layer 104 may include a second bump 213 on the second side, such as Figure 2b As shown in the diagram. The second bump 213 serves the same purpose as described above with respect to the first bump 212, except to prevent adhesion, since it can be bonded to the ASIC layer side on the interposer layer via non-biased metal bonding.

[0082] The material of the second bump 213 on the interposer 104 can be polysilicon. The second bump can be fabricated during the formation of the first measuring electrode 105.

[0083] Manufacturing method

[0084] A method for manufacturing a microelectromechanical system (MEMS) includes the following steps: a) forming an interposer layer on a first wafer; b) forming a MEMS layer from the first wafer, the MEMS layer including a first movable structure; c) attaching a capping layer to the MEMS layer such that a first isolation shell is formed between the capping layer and the interposer layer, and setting pressure in the first isolation shell; d) attaching an ASIC layer to the interposer layer.

[0085] MEMS system can be based on Figure 4 The following processes are used to manufacture:

[0086] - Step a:

[0087] A silicon wafer 401 is provided and exposed to thermal oxidation to obtain a first oxide layer of a certain thickness. Recesses are formed in / through the first oxide layer using photolithography and dry etching.

[0088] ○ A first conductive layer (e.g., polysilicon) is deposited on top of the first oxide layer. A first conductive pattern is obtained in the first conductive layer using photolithography and dry etching.

[0089] A second oxide layer is formed on the first conductive pattern and the exposed first oxide layer. The first oxide layer, the first conductive layer, and the second oxide layer form the interposer layer 104 of the MEMS system.

[0090] ○ Optionally, a thick third oxide layer may be deposited on the second oxide layer.

[0091] - Step b:

[0092] ○ The temporary silicon carrier wafer 402 is attached to the third oxide layer by, for example, fusion bonding.

[0093] ○ A structure for forming MEMS layer 106 is formed in silicon wafer 401 by using, for example, a local oxidation of silicon (LOCOS) process to define a recess in the MEMS layer (detection gap 112) and by using a second photolithography and HF etching process to define a first movable structure 107.

[0094] - Step c:

[0095] ○ The capping layer 109 is attached to the MEMS layer, for example, by anodic bonding. Other attachment methods are also possible. At this step, pressure is set in the first isolation housing 110. The pressure can be set by performing bonding under the desired pressure.

[0096] ○ Remove the temporary silicon carrier wafer 402 and form a via, for example 209, through the third (optional) oxide layer and the second oxide layer.

[0097] ○ Deposit a metal layer, such as a titanium and germanium layer, on the third oxide layer and pattern it using photolithography and wet etching to form metal contacts 205 to 206 and make the via (e.g., 209) conductive.

[0098] - Step d:

[0099] ○ The ASIC layer 101 is attached to metal contacts 205 to 206 by means of, for example, metal bonding.

[0100] Optionally, at this step, a second isolation housing 211 is formed and pressure is set within the second isolation housing 211. The pressure can be set by performing bonding at the desired pressure.

[0101] ○ Optionally, electrical contacts for external connections are provided in the cover layer.

[0102] The disclosed manufacturing method relates to the fabrication of MEMS systems, wherein multiple systems are simultaneously fabricated from stacked wafers through wafer-level processing. After the fabrication steps are completed, the wafers are diced to produce individual MEMS systems.

Claims

1. A microelectromechanical system (100), comprising: - ASIC layer (101), wherein the ASIC layer includes control circuitry (102). - Includes an intermediary layer (104) with a first side and a second side, wherein the ASIC layer (101) is bonded to the first side of the intermediary layer (104), and - A MEMS layer (106) including a first side and a second side, wherein the second side of the interposer layer (104) is attached to the first side of the MEMS layer (106). - A capping layer (109) attached to the second side of the MEMS layer (106). in - The intermediate layer (104) and the cover layer (109) form a first isolation shell (110), and the first isolation shell (110) has the MEMS layer (106) inside. - And the MEMS layer (106) includes a first movable structure (107), wherein the first movable structure (107) is within the first isolation housing (110), in - The intermediary layer (104) includes a first measuring electrode (105) on the second side, wherein the first measuring electrode (105) is adjacent to the first movable structure (107) in the first isolation housing (110).

2. The microelectromechanical system according to claim 1, wherein, The first measuring electrode (105) is connected to the ASIC layer (106) through the intermediary layer (104).

3. The microelectromechanical system according to claim 1 or 2, wherein, The cover layer (109) includes a first side attached to the MEMS layer (106), and the cover layer includes a second measurement electrode (207) on the first side, wherein the second measurement electrode is adjacent to the first movable structure (107) in the first isolation housing.

4. The microelectromechanical system according to claim 3, wherein, The second measuring electrode (207) is connected to the ASIC layer (101) through the MEMS layer (106) and the intermediary layer (104).

5. The microelectromechanical system according to any one of the preceding claims, wherein, The first measuring electrode (105) is polycrystalline silicon.

6. The microelectromechanical system according to any one of claims 1 to 4, wherein, The first measuring electrode (105) and / or the second measuring electrode (207) are metals.

7. The microelectromechanical system according to any one of the preceding claims, wherein, The ASIC layer (101) is electrically connected to the capping layer (109) via ASIC vias (301) in the intermediary layer (104) and the MEMS layer (106), and signals from the ASIC layer (101) are routed from the capping layer (109) to the outside of the microelectromechanical system.

8. The microelectromechanical system according to any one of claims 1 to 6, wherein, Signals from the ASIC layer (101) to the outside of the microelectromechanical system are configured to be routed directly from the ASIC layer (101).

9. The microelectromechanical system according to claim 8, wherein, The signals from the ASIC layer (101) to the outside of the microelectromechanical system are configured to be routed via wires (305) connected to the ASIC layer.

10. The microelectromechanical system according to any one of the preceding claims, wherein, The first movable structure (107) is a gyroscope.

11. The microelectromechanical system according to any one of the preceding claims, wherein, The first movable structure (107) is an accelerometer.

12. The microelectromechanical system according to any one of the preceding claims, wherein, The ASIC layer (101) and the intermediary layer (104) form a second insulating shell (211).

13. The microelectromechanical system according to claim 12, wherein, The pressure in the first isolation housing (110) is different from the pressure in the second isolation housing (211).

14. A method of manufacturing a microelectromechanical system (100) according to any one of the preceding claims, comprising the following steps: a) An intermediary layer (104) is formed on the first wafer (401). b) A MEMS layer (106) is formed from the first wafer, the MEMS layer including a first movable structure (107). c) Attaching the cover layer (109) to the MEMS layer to form a first isolation shell (110) between the cover layer and the intermediate layer (104); and setting a pressure in the first isolation shell. d) Attach the ASIC layer (101) to the intermediary layer.

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