Micro-electromechanical system device and method for forming the same, and micro-electromechanical system structure

Abstract

Various embodiments relate to a microelectromechanical system (MEMS) device and a method of forming the same and a MEMS structure, the MEMS device including a conductive bonding structure disposed between a substrate and a MEMS substrate. An interconnect structure overlies the substrate. The MEMS substrate overlies the interconnect structure and includes a movable membrane. A dielectric structure is disposed between the interconnect structure and the MEMS substrate. The conductive bonding structure is sandwiched between the interconnect structure and the MEMS substrate. The conductive bonding structure is laterally spaced between sidewalls of the dielectric structure. The conductive bonding structure, the MEMS substrate, and the interconnect structure at least partially define a cavity. The movable membrane overlies the cavity and is laterally spaced between sidewalls of the conductive bonding structure.

Description

Technical Field

[0001] The embodiments of the present invention relate to a micro-electro-mechanical system device and a forming method thereof and a micro-electro-mechanical system structure. Background Art

[0002] Microelectromechanical system (MEMS) devices (e.g., accelerometers, pressure sensors, microphones, and transducers) have been widely used in many modern electronic devices. For example, MEMS accelerometers and transducers are commonly found in automobiles (e.g., airbag deployment systems), tablet computers, or medical devices. MEMS devices may have movable parts for detecting motion and converting the motion into electrical signals. For example, a MEMS accelerometer includes a movable part that converts accelerated movement into electrical signals. A transducer includes a moveable membrane that converts sound waves into electrical signals. Summary of the invention

[0003] An embodiment of the present invention provides a micro-electromechanical system device, which includes a substrate, an interconnect structure, a micro-electromechanical system substrate, a dielectric structure, and a conductive bonding structure. The interconnect structure overlies the substrate. The micro-electromechanical system substrate overlies the interconnect structure, wherein the micro-electromechanical system substrate includes a movable membrane. The dielectric structure is disposed between the interconnect structure and the micro-electromechanical system substrate. The conductive bonding structure is sandwiched between the interconnect structure and the micro-electromechanical system substrate. The conductive bonding structure is laterally spaced between the side walls of the dielectric structure. The conductive bonding structure, the micro-electromechanical system substrate, and the interconnect structure at least partially define a first cavity, wherein the movable membrane overlies the first cavity and is laterally spaced between the side walls of the conductive bonding structure.

[0004] An embodiment of the present invention provides a micro-electromechanical system structure, which includes a substrate, an interconnect structure, a micro-electromechanical system substrate, a conductive bonding ring structure and a dielectric structure. The interconnect structure is overlaid on the substrate, wherein the interconnect structure includes a conductive bonding layer. The micro-electromechanical system substrate is overlaid on the interconnect structure, wherein the micro-electromechanical system substrate includes a movable membrane. The conductive bonding ring structure is sandwiched between the interconnect structure and the micro-electromechanical system substrate. The conductive bonding ring structure contacts the conductive bonding layer of the interconnect structure. The conductive bonding ring structure, the micro-electromechanical system substrate and the interconnect structure at least partially define a first cavity. The movable membrane overlies the first cavity and is laterally spaced between the side walls of the conductive bonding ring structure. The dielectric structure is sandwiched between the interconnect structure and the micro-electromechanical system substrate. The conductive bonding ring structure is laterally spaced between the inner side walls of the dielectric structure. The thickness of the dielectric structure is less than the thickness of the conductive bonding ring structure.

[0005] An embodiment of the present invention provides a method for forming a micro-electromechanical system device, the method comprising: forming an interconnect structure on a substrate; forming a dielectric layer stack having a first thickness on the interconnect structure; patterning the dielectric layer stack to define the dielectric structure and one or more stop structures along the upper surface of the interconnect structure; forming a movable membrane on the micro-electromechanical system substrate; forming an isolation dielectric layer on the micro-electromechanical system substrate; forming a conductive bonding ring structure on the micro-electromechanical system substrate, wherein the conductive bonding ring structure has a second thickness greater than the first thickness; and performing a eutectic bonding process to bond the conductive bonding ring structure to the interconnect structure, wherein the eutectic bonding process seals a first cavity disposed between inner side walls of the conductive bonding ring structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The various aspects of the present disclosure will be best understood by reading the following detailed description in conjunction with the accompanying drawings. It should be noted that, in accordance with standard practice in the industry, the various features are not drawn to scale. In fact, the size of the various features may be arbitrarily increased or reduced for clarity of discussion.

[0007] Figure 1 Cross-sectional views of some embodiments of a microelectromechanical system (MEMS) device having a conductive bonding structure surrounded by a dielectric structure are shown.

[0008] Figure 2A to Figure 2B Show Figure 1 Top views of some alternative embodiments of MEMS devices are shown.

[0009] Figure 3 Cross-sectional views of some embodiments of an integrated chip including a MEMS device having a dielectric structure laterally surrounding a conductive bonding structure are shown.

[0010] Figure 4 Show Figure 3 Top views of some alternative embodiments of MEMS devices are shown.

[0011] Figure 5A Cross-sectional views of some embodiments of a MEMS device having a movable membrane overlying a cavity are shown.

[0012] FIG. 5B to FIG. 5C Show Figure 5A Cross-sectional views of some embodiments of portions of MEMS devices are shown.

[0013] Figure 6 Cross-sectional views of some embodiments of a MEMS device having a conductive bonding structure surrounded by a dielectric structure are shown, wherein the conductive bonding structure laterally surrounds an electrode.

[0014] Figures 7 to 13Cross-sectional views of some embodiments of methods of forming a MEMS device having a conductive bonding structure surrounded by a dielectric structure are shown.

[0015] Fig.14 Some embodiments of methods of forming a MEMS device having a conductive bonding structure surrounded by a dielectric structure are shown. DETAILED DESCRIPTION

[0016] The present disclosure provides many different embodiments or examples for implementing the different features of the present disclosure. Specific examples of components and arrangements are described below to simplify the present disclosure. Of course, these are only examples and are not intended to be limiting. For example, the following description in which a first feature is formed on or on a second feature may include an embodiment in which the first feature and the second feature are formed to be in direct contact, and may also include an embodiment in which an additional feature may be formed between the first feature and the second feature so that the first feature and the second feature may not be in direct contact. In addition, the present disclosure may reuse reference numbers and / or letters in various examples. This repetition is for the purpose of simplicity and clarity, rather than indicating the relationship between the various embodiments and / or configurations discussed by itself.

[0017] Additionally, for ease of description, spatially relative terms such as "beneath," "below," "lower," "above," "upper," etc. may be used herein to describe the relationship of one element or feature to another (other) element or feature as shown in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein may be interpreted accordingly.

[0018] Microelectromechanical systems (MEMS) devices for acoustic applications (e.g., capacitive micro-machined ultrasonic transducers (CMUTs)) often include a movable membrane disposed above and / or within a cavity. The cavity is defined between a MEMS substrate and a carrier substrate. The MEMS substrate includes a movable membrane located above the cavity and a cavity electrode disposed below the movable membrane. During operation, ultrasound waves may cause the movable membrane to move toward or away from the cavity electrode, such that a change in capacitance between the membrane electrode and the cavity electrode may be detected. This change in capacitance may be converted into an electrical signal and may be transferred to a contact electrode electrically coupled to the cavity electrode and / or the membrane electrode. The range of capacitance values ​​that may be sensed by the MEMS device is defined by the height of the cavity (i.e., the sensing gap). The sensing gap of a MEMS device may be specific to each application, wherein having an inaccurate sensing gap may adversely affect the performance and / or sensitivity of the MEMS device.

[0019] During the fabrication of the MEMS device, the above structure may present challenges. The MEMS substrate may be fusion bonded to the carrier substrate by a dielectric bonding structure disposed between the MEMS substrate and the carrier substrate. The thickness of the dielectric bonding structure may define the height of the cavity and / or the sensing gap. Due to the limitations of current processing tools, it may be difficult to accurately define the desired thickness of the dielectric bonding structure. During the fabrication of the dielectric bonding structure, a plurality of dielectric layers are deposited on the carrier substrate. After the deposition of the plurality of dielectric layers, a planarization process (e.g., a chemical mechanical planarization (CMP) process) is performed on the plurality of dielectric layers to achieve the desired thickness of the dielectric bonding structure and define a substantially flat upper surface of the dielectric bonding structure. The substantially flat upper surface is configured to facilitate a strong bond between the MEMS substrate and the dielectric bonding structure. However, due to the limitations of the processing tools, it may be difficult to control the planarization process to define a dielectric bonding structure having a desired thickness (e.g., in the range of about 2,400 angstroms to 2,800 angstroms) and a substantially flat upper surface.

[0020] For example, the plurality of dielectric layers may have an initial thickness that is substantially greater than a desired thickness (e.g., greater than 6,000 angstroms). The planarization process may have a tolerance of approximately 1,000 angstroms, such that after performing the planarization process, the thickness of the dielectric bonding structure may be in a range of approximately 1,600 angstroms to 3,600 angstroms. Failure to accurately set the thickness of the dielectric bonding structure may result in a poor and / or inaccurate sensing gap between the movable membrane and the cavity electrode, thereby reducing the sensitivity of the MEMS device. In addition, without the planarization process, the upper surface of the dielectric bonding structure may not be substantially flat. This in turn may result in a poor bonding interface between the dielectric bonding structure and the MEMS substrate, resulting in lifting and / or delamination between the MEMS substrate and the carrier substrate. In addition, in some embodiments, the deposition process and the planarization process may be repeated more than once to achieve a substantially flat upper surface and a suitable thickness of the dielectric bonding structure. This may increase the time and cost associated with forming the MEMS device.

[0021] In some embodiments, the present disclosure relates to a MEMS device with an accurately defined sensing gap. For example, the MEMS device includes a MEMS substrate overlying a carrier substrate. A conductive bonding structure is disposed between the MEMS substrate and the carrier substrate. A dielectric structure laterally surrounds the conductive bonding structure and is located between the MEMS substrate and the carrier substrate. A cavity is disposed between the MEMS substrate and the carrier substrate, wherein a movable membrane overlies the cavity. A cavity electrode is disposed below the movable membrane along a lower surface of the cavity. During a process of forming the MEMS device, the dielectric structure is deposited by a deposition process with high thickness control (e.g., high density plasma (HDP) chemical vapor deposition (CVD)). This in turn helps to accurately define the thickness of the dielectric structure (e.g., within a range of + / -5% of a target thickness) and reduces the cost and time associated with making the dielectric structure (e.g., omitting a CMP process). The MEMS substrate is bonded to the carrier substrate by eutectic bonding, wherein the dielectric structure is configured to serve as a bonding stop structure during eutectic bonding. Therefore, the height of the cavity is defined by the thickness of the dielectric structure. Since the thickness of the dielectric structure is easily controlled, the sensing gap between the movable membrane and the cavity electrode can be easily set. This in turn increases the sensitivity of the MEMS device while reducing the time and cost associated with forming the MEMS device.

[0022] Figure 1A cross-sectional view of some embodiments of a microelectromechanical system (MEMS) device 100 having a conductive bonding structure 122 surrounded by a dielectric structure 130 is shown.

[0023] The MEMS device 100 includes an interconnect structure 104 overlying a substrate 102. The interconnect structure 104 includes an interconnect dielectric structure 106, a plurality of conductive lines 108, a plurality of vias 110, and a redistribution layer 112. In some embodiments, a semiconductor device (e.g., a transistor, a capacitor, a resistor, etc.) (not shown) is disposed on and / or within the substrate 102 and is electrically coupled to the conductive lines 108, the vias 110, and the redistribution layer 112. An upper layer 108ul of the conductive lines 108 includes a conductive bonding layer 108b and a cavity electrode 108a.

[0024] The MEMS substrate 134 overlies the interconnect structure 104 and an isolation dielectric layer 132 is disposed along the lower surface of the MEMS substrate 134. A cavity 120 is defined between the lower surface of the isolation dielectric layer 132 and the upper surface of the interconnect structure 104. In some embodiments, a cavity electrode 108a is disposed within the interconnect dielectric structure 106 and below the cavity 120. A dielectric structure 130 is disposed between the interconnect structure 104 and the isolation dielectric layer 132. The dielectric structure 130 includes a first dielectric layer 124 overlying the interconnect dielectric structure 106, a second dielectric layer 126 overlying the first dielectric layer 124, and a third dielectric layer 128 overlying the second dielectric layer 126. In some embodiments, the dielectric structure 130 has a thickness t1 defined from the upper surface of the third dielectric layer 128 to the lower surface of the first dielectric layer 124. In some embodiments, the thickness t1 is in a range of about 2,400 angstroms to 2,800 angstroms. In other embodiments, the thickness t1 may be, for example, in a range from about 100 nanometers to about 1 micron. In some embodiments, the thickness t1 depends on a customer-specified value. The conductive bonding structure 122 is laterally offset from the dielectric structure 130 and is disposed between the conductive bonding layer 108b and the isolation dielectric layer 132. The cavity 120 is defined between the sidewalls of the conductive bonding structure 122 and between the lower surface of the isolation dielectric layer 132 and the upper surface of the interconnect structure 104. In some embodiments, the sidewalls of the conductive bonding structure 122 are defined from a cross-sectional view. For example, when viewed from above, if the conductive bonding structure 122 is annular or circular / elliptical, the sidewall is a single continuous sidewall when viewed from above, and thus "sidewall" refers to the properties of this single continuous sidewall when depicted in a cross-sectional view. Additionally, if the conductive bonding structure 122 is annular, circular, or elliptical when viewed from above, any length and / or width of the structure and / or layer associated with a cross-sectional view including the conductive bonding structure 122 corresponds to the diameter of the circle or the length between two vertices defined on the major axis of the ellipse, respectively.

[0025] In some embodiments, a movable membrane 136 is disposed within the MEMS substrate 134. For example, in some embodiments, the movable membrane 136 may be a doped region of the MEMS substrate 134. In such an embodiment, the MEMS substrate 134 may include a first doping type (e.g., p-type), and the movable membrane 136 may include a second doping type (e.g., n-type) opposite to the first doping type. In other embodiments, the movable membrane 136 may be a conductive electrode (not shown) disposed along a lower surface or an upper surface of the MEMS substrate 134 (see, e.g., Figure 5A During operation of the MEMS device 100, the movable membrane 136 is configured to move toward or away from the cavity electrode 108a so that a change in capacitance between the movable membrane 136 and the cavity electrode 108a can be detected. The change in capacitance can be converted into an electrical signal and can be transmitted to a semiconductor device and / or other semiconductor devices (not shown) disposed on the substrate 102 through the interconnect structure 104. For example, the position of the movable membrane 136 may be displaced by an acoustic wave (e.g., an ultrasonic signal) disposed on the MEMS device 100. In such an embodiment, the MEMS device 100 can be configured as a capacitive micromachined ultrasonic transducer (CMUT).

[0026] In some embodiments, the range of capacitance values ​​between the movable membrane 136 and the cavity electrode 108a may be defined by the distance ds. The distance ds is defined between the upper surface of the third stopper structure 118c and the movable membrane 136. The range of capacitance values ​​increases as the distance ds increases, and the range of capacitance values ​​decreases as the distance ds decreases. In some embodiments, during the fabrication of the MEMS device 100, the distance ds is defined by setting the thickness t1 of the dielectric structure 130 to a predetermined value. By accurately setting the thickness t1 of the dielectric structure 130 to a predetermined value, the sensitivity (i.e., the range of capacitance values) of the MEMS device 100 may be defined. However, if the thickness t1 of the dielectric structure 130 is inaccurately defined, the sensitivity of the MEMS device 100 may not be suitable for a particular application. This, in turn, may adversely affect the performance of the MEMS device 100 for a particular application.

[0027] In some embodiments, the conductive bonding structure 122 (not shown) is omitted, and the dielectric structure 130 may be configured as a dielectric bonding structure. In such an embodiment, in order to achieve a strong bonding interface with the isolation dielectric layer 132, a planarization process (e.g., a chemical mechanical planarization (CMP) process) is performed on the dielectric structure 130 so that the dielectric structure 130 has a substantially flat upper surface. However, due to limitations of processing tools (e.g., tolerances of the CMP process), it may be difficult to form a substantially flat upper surface while accurately defining the thickness t1. Therefore, in some embodiments according to the present disclosure, in order to achieve a strong bond between the substrate 102 and the MEMS substrate 134 and an accurate thickness t1, a deposition process with high thickness control may be used to deposit the dielectric structure 130, and the conductive bonding structure 122 may be bonded to the interconnect structure 104 by eutectic bonding. For example, the formation of the dielectric structure 130 may include a deposition process (e.g., high density plasma (HDP) chemical vapor deposition (CVD)) with a high degree of control over the thickness t1 (i.e., forming the dielectric structure 130 to a predetermined thickness with an error within a range of + / -5%). In addition, the conductive bonding structure 122 is bonded to the conductive bonding layer 108b by eutectic bonding, thereby achieving a strong bond between the MEMS substrate 134 and the substrate 102. During the eutectic bonding process, as the conductive bonding structure 122 is bonded to the conductive bonding layer 108b, the thickness of the conductive bonding structure 122 may decrease. When the lower surface of the isolation dielectric layer 132 contacts the upper surface of the dielectric structure 130, the reduction in the thickness of the conductive bonding structure stops. Therefore, the dielectric structure 130 acts as a bonding stop structure so that the thickness t1 can define the distance ds. Therefore, while accurately defining the distance ds, a strong bond can be achieved between the conductive bonding structure 122 and the conductive bonding layer 108b. This in turn increases the reliability, structural integrity, and sensitivity of the MEMS device 100 .

[0028] In some embodiments, a plurality of stopper structures 118a, 118b, 118c (or may be described as stopper structures 118a-118c) may be disposed along the upper surface of the interconnect dielectric structure 106. During operation of the MEMS device 100, the stopper structures 118a-118c are each configured to prevent the movable membrane 136 from sticking and / or adhering to the interconnect dielectric structure 106. In some embodiments, each of the stopper structures 118a-118c may have a rough upper surface configured to prevent sticking with the isolation dielectric layer 132 and / or the movable membrane 136. This in turn may prevent the movable membrane 136 from getting stuck and / or being unable to move in response to acoustic waves, thereby increasing the durability, reliability, and performance of the MEMS device 100. The first stopper structure 118a and the second stopper structure 118b each include a first stopper layer 114 located below the second stopper layer 116. In some embodiments, the third stopper structure 118 c includes the same material as the first stopper layer 114 .

[0029] Figure 2A Shown is a view taken along line A-A' Figure 1 A top view 200 a of some alternative embodiments of the MEMS device 100 is shown. Figure 1 Shown is a view taken along line A-A' Figure 2A Some embodiments of a cross-sectional view of top view 200a are shown.

[0030] The groove 202 laterally surrounds the movable membrane 136. In some embodiments, the groove 202 is configured to electrically and / or mechanically isolate the movable membrane 136 from other regions, structures, and / or layers (not shown) disposed on the MEMS substrate 134. In other embodiments, the groove 202 extends through the entire thickness of the MEMS substrate 134. Figure 2A As shown in FIG. 1 , when viewed from above, the movable membrane 136 may include a central body 136 a having a circular shape or an elliptical shape, and further include a rounded protrusion 136 b extending from the central body 136 a.

[0031] Figure 2B Shows the area taken along line B-B' Figure 1 A top view 200b of some alternative embodiments of the MEMS device 100 is shown. In some embodiments, Figure 1 In the cross-sectional view shown, line BB′ is disposed along the upper surface of the dielectric structure 130 . Figure 1 Shows the area taken along line B-B' Figure 2B Some embodiments of a cross-sectional view of a top view 200b are shown.

[0032] like Figure 2BAs shown in FIG. 1 , the dielectric structure 130 includes a central body having a circular shape and / or an elliptical shape and a rounded protrusion extending from the central body. A contact through hole 204 is provided in the rounded protrusion, and the contact through hole 204 is electrically coupled to the movable membrane ( Figure 1 136). The trench 202 continuously surrounds the dielectric structure 130. The dielectric structure 130 continuously surrounds the conductive bonding structure 122. In some embodiments, when viewed from above, the conductive bonding structure 122 is annular in shape and can be configured to pressurize the cavity ( Figure 1 When viewed from above, the first stopper structure 118a and the second stopper structure 118b may have an annular shape, and the third stopper structure 118c may have a circular shape or an elliptical shape.

[0033] Figure 3 A cross-sectional view of some embodiments of an integrated chip 300 including a MEMS device 302 having a dielectric structure 130 laterally surrounding a conductive bonding structure 122 is shown.

[0034] The integrated chip 300 includes an interconnect structure 104 overlying a substrate 102. In some embodiments, the substrate 102 may be or may include, for example, a bulk substrate (e.g., a bulk silicon substrate), a silicon-on-insulator (SOI) substrate, or some other suitable substrate. In alternative embodiments, the substrate 102 may be configured as a carrier substrate or a semiconductor substrate. The interconnect structure 104 includes an interconnect dielectric structure 106, a plurality of conductive lines 108, a plurality of vias 110, and a redistribution layer 112. The interconnect dielectric structure 106 may include one or more inter-level dielectric (ILD) layers. In some embodiments, the one or more ILD layers may be or may include, for example, silicon dioxide, a low-k dielectric material, an extremely low-k dielectric material, a combination of the foregoing, or another suitable dielectric material. The conductive lines 108 and / or the vias 110 may be or may include, for example, aluminum, copper, aluminum-copper, tungsten, titanium, tantalum, a combination of the foregoing, or the like. The redistribution layer 112 may be or may include, for example, aluminum, copper, tungsten, a combination of the foregoing, etc. The conductive line 108 includes an upper layer 108ul located above the redistribution layer 112 in a vertical direction. The upper layer 108ul of the conductive line 108 includes a conductive bonding layer 108b and a cavity electrode 108a. In some embodiments, the conductive bonding layer 108b may be or may include aluminum, copper, aluminum copper, etc.

[0035] The MEMS device 302 includes a movable membrane 136, a cavity 120, a dielectric structure 130, a conductive bonding structure 122, a plurality of stopper structures 118a-118c, one or more contact vias 204, and a cavity electrode 108a. A MEMS substrate 134 overlies the interconnect structure and an isolation dielectric layer 132 is disposed along a lower surface of the MEMS substrate 134. The cavity 120 is defined between a lower surface of the isolation dielectric layer 132 and an upper surface of the interconnect structure 104. The dielectric structure 130 is disposed between the interconnect structure 104 and the isolation dielectric layer 132. The dielectric structure 130 includes a first dielectric layer 124, a second dielectric layer 126, and a third dielectric layer 128. In some embodiments, the first dielectric layer 124 may be or may include, for example, aluminum oxide (e.g., Al2O3), another metal oxide, etc., and / or may have a thickness t3 of about 300 angstroms or in a range of about 285 angstroms to 315 angstroms. In some embodiments, the second dielectric layer 126 may be or may include, for example, silicon nitride, silicon carbide, etc., and / or may have a thickness t4 of about 300 angstroms or in a range of about 285 angstroms to 315 angstroms. In other embodiments, the third dielectric layer 128 may be or may include, for example, an oxide (e.g., silicon dioxide, another suitable oxide, etc.), and / or may have a thickness t5 of about 2,000 angstroms or in a range of about 1,900 angstroms to 2,100 angstroms. In some embodiments, the upper region 106ur of the interconnect dielectric structure 106 may have a thickness t2 of about 200 angstroms, greater than about 100 angstroms, or in a range of about 190 angstroms to 210 angstroms. In some embodiments, if the thickness t2 is greater than about 100 angstroms, the upper region 106ur of the interconnect dielectric structure 106 may be configured to prevent stress and / or damage to the upper layer 108ul of the conductive line 108. In some embodiments, the dielectric structure 130 has a thickness t1.

[0036] In some embodiments, the thickness t2 of the upper region 106ur of the interconnect dielectric structure 106, the thickness t3 of the first dielectric layer 124, and / or the thickness t4 of the second dielectric layer 126 may be fixed to initial values, respectively, for example. In such embodiments, the thickness t1 of the dielectric structure 130 may be adjusted by changing the thickness t5 of the third dielectric layer 128 to a suitable value. Therefore, the distance ds between the movable membrane 136 and the third stopper structure 118c may be set by appropriately setting the thickness t5 of the third dielectric layer 128. In other embodiments, since the third dielectric layer 128 is formed by a deposition process (e.g., high density plasma (HDP) chemical vapor deposition (CVD)) having a high degree of control over the thickness t5 (i.e., forming the third dielectric layer 128 to a predetermined thickness within a range of + / -5%), the distance ds may be formed to a target value within a range of about + / -5% of the target value. This in turn increases the performance and sensitivity of the MEMS device 302.

[0037] The conductive bonding structure 122 is disposed between the isolation dielectric layer 132 and the conductive bonding layer 108b. In some embodiments, the dielectric structure 130 continuously surrounds the outer perimeter of the conductive bonding structure 122. In some embodiments, the conductive bonding structure 122 may be or may include, for example, germanium, another suitable conductive material, etc. In some embodiments, during the fabrication of the integrated chip 300, the conductive bonding structure 122 may be bonded to the conductive bonding layer 108b, thereby sealing the cavity 120 with the first gas pressure.

[0038] The movable membrane 136 is disposed in the MEMS substrate 134 and overlies the cavity 120. The groove 202 laterally surrounds the movable membrane 136 and can be configured to electrically isolate the movable membrane 136 from other devices disposed in and / or on the MEMS substrate 134. The groove 202 continuously extends from the upper surface of the MEMS substrate 134 to the bottom surface of the first dielectric layer 124, so that the upper surface of the interconnect dielectric structure 106 is exposed. One or more contact vias 204 extend from the conductive line 108 in the interconnect structure 104 through the dielectric structure 130 to contact the movable membrane 136. The one or more contact vias 204 are configured to electrically couple the movable membrane 136 to the conductive line 108 and the via 110.

[0039] The movable membrane 136 is separated from the lower surface of the cavity 120 by a distance ds. The cavity electrode 108a is disposed within the interconnect dielectric structure 106 and is separated from the cavity 120 by an upper region 106ur of the interconnect dielectric structure 106. The plurality of stopper structures 118a-118c are disposed within the cavity 120 and overlying the cavity electrode 108a. The first stopper structure 118a and the second stopper structure 118b each include a first stopper layer 114 and a second stopper layer 116. In some embodiments, the first stopper layer 114 may be or may include, for example, aluminum oxide (e.g., Al2O3), another metal oxide, etc. In other embodiments, the second stopper layer 116 may be or may include, for example, silicon nitride, silicon carbide, etc. The third stopper structure 118c may be or may include, for example, aluminum oxide (e.g., Al2O3), another metal oxide, etc. In some embodiments, the third stopper structure 118c may, for example, have the same thickness (not shown) as the first dielectric layer 124. In some embodiments, the upper surface of each stopper structure 118a-118c may be roughened and / or may include a plurality of protrusions configured to prevent sticking with the isolation dielectric layer 132 and / or the movable membrane 136. In other embodiments, the third stopper structure 118c is configured as a sensing electrode so that the capacitance between the third stopper structure 118c and the movable membrane 136 can be detected.

[0040] Figure 4 Shown along line C-C' Figure 3 A top view 400 of some alternative embodiments of the integrated chip 300 is shown. Figure 3 Shown along line C-C' Figure 4 Some embodiments of a cross-sectional view of a portion of top view 400 are shown.

[0041] like Figure 4 As shown in the top view 400, a plurality of MEMS devices 402a, 402b, 402c, 402d, 402e, 402f (or MEMS devices 402a-402f) are arranged in an array including rows and columns. In some embodiments, each MEMS device 402a-402f is configured to Figure 3 The MEMS device 302 is shown. The groove 202 laterally surrounds the outer periphery of each MEMS device 402a-402f and is configured to electrically isolate the MEMS devices 402a-402f from each other. In addition, a plurality of contact pads 404 are laterally offset from the MEMS devices 402a-402f. The contact pads 404 are configured to electrically couple the MEMS devices 402a-402f to another semiconductor device (not shown) by, for example, bonding wires (not shown). The contact pads 404 each include a contact pad body 408 and a contact pad through-hole 410. In some embodiments, the contact pad through-hole 410 extends into the MEMS substrate 134 to contact the interconnect structure ( Figure 3 104) of the metal features (e.g., Figure 3 The conductive wire 108, Figure 3 In addition, the contact pad 404 can be connected through the internal connection structure ( Figure 3 104) is electrically coupled to the MEMS devices 402a-402f. In addition, a contact pad trench 406 laterally surrounds each contact pad body 408 and contact pad via 410, wherein the contact pad trench 406 is configured to electrically isolate the contact pad 404 from other devices disposed within and / or on the MEMS substrate 134. In some embodiments, the contact pad body 408 and / or the contact pad via 410 can each be or can include, for example, aluminum, copper, aluminum-copper, etc.

[0042] Figure 5A Show according to Figure 3 A cross-sectional view of an integrated chip 500 is shown that illustrates some alternative embodiments of the integrated chip 300 .

[0043] like Figure 5AAs shown in , the movable membrane 136 may be configured as a movable membrane electrode, so that the movable membrane 136 may be or may include aluminum, copper, aluminum copper, titanium, tantalum, a combination of the foregoing, etc. In addition, the upper isolation layer 502 may overlie the MEMS substrate 134. In such an embodiment, the MEMS substrate 134, the upper isolation layer 502 and the isolation dielectric layer 132 may be configured as a silicon-on-insulator (SOI) substrate. In some embodiments, the upper isolation layer 502 may be or may include, for example, an oxide (e.g., silicon dioxide, another suitable dielectric material, etc.). In addition, the lower surface of the movable membrane 136 may be disposed along the upper surface 134us of the MEMS substrate 134. In some embodiments, the upper surface of the movable membrane 136 may be disposed along the lower surface 134ls of the MEMS substrate 134 (not shown). In other embodiments, the lower surface of the movable membrane 136 may be disposed along the lower surface 134ls of the MEMS substrate 134.

[0044] Figure 5B The dashed box indicates Figure 5A A close-up cross-sectional view 504 is shown of the interface between the conductive bonding structure 122 and the conductive bonding layer 108 b .

[0045] In some embodiments, the bottom surface 122bs of the conductive bonding structure 122 may include a plurality of protrusions extending below the upper surface 108us of the conductive bonding layer 108b. In addition, the conductive bonding structure 122 may include lateral segments 122ls1, 122ls2, which extend laterally from the sidewalls 122sw1, 122sw2 of the conductive bonding structure 122 to above the upper surface 108us, respectively. In some embodiments, the lateral segments 122ls1, 122ls2 may be caused by force and / or temperature applied to the conductive bonding structure 122 during the manufacture of the integrated chip 500.

[0046] Figure 5C Show Figure 5A 506 of the upper surface 116us of the second stopper layer 116. Figure 5C As shown in FIG, the upper surface 116us of the second stopper layer 116 may include a plurality of protrusions configured to reduce sticking with the isolation dielectric layer 132. In some embodiments, the upper surface of each of the stopper structures 118a-118c may be configured as an upper surface 116us (not shown).

[0047] Figure 6 A cross-sectional view of some embodiments of a micro-electromechanical system (MEMS) device 600 is shown having a conductive bonding structure 122 surrounded by a dielectric structure 130 , wherein the conductive bonding structure 122 laterally surrounds an upper electrode 602 .

[0048] In some embodiments, a distance ds is defined between the movable membrane 136 and an upper surface 602us of the upper electrode 602. The upper electrode 602 abuts the cavity 120. A change in capacitance between the movable membrane 136 and the upper electrode 602 can be detected. The upper electrode 602 can, for example, be electrically coupled to a conductive line 108 in the interconnect structure 104. In other embodiments, the thickness of the upper electrode 602 can be equal to the thickness of the first dielectric layer 124, and / or the upper electrode 602 and the first dielectric layer 124 can include the same material (e.g., metal oxide).

[0049] Figures 7 to 13 Cross-sectional views 700 through 1300 illustrate some embodiments of methods of forming a microelectromechanical system (MEMS) device having a conductive bonding structure surrounded by a dielectric structure according to aspects of the present disclosure. Figures 7 to 13 700 to 1300 shown in FIG. 1 , however, it should be understood that Figures 7 to 13 The structures shown in are not limited to the described methods, but can be independently separated from the described methods. Figures 7 to 13 It is described as a series of actions, but it should be understood that these actions are not restrictive, the order of the actions can be changed in other embodiments, and the disclosed method is also applicable to other structures. In other embodiments, some actions shown and / or described can be omitted in whole or in part.

[0050] like Figure 7 As shown in the cross-sectional view 700, a substrate 102 is provided and an interconnect structure is formed on the front side surface of the substrate 102. The interconnect structure 104 includes an interconnect dielectric structure 106, a plurality of conductive lines 108, a plurality of vias 110, and a redistribution layer 112. In some embodiments, the interconnect dielectric structure 106 may be or may include one or more interlayer dielectric (ILD) layers. The one or more ILD layers may be or may include, for example, an oxide (e.g., silicon dioxide), a low-k dielectric material, or another suitable dielectric material. In some embodiments, the process of forming the interconnect structure 104 includes forming the conductive line 108, the redistribution layer 112, and / or the via 110 by a single damascene process or a dual damascene process. In some embodiments, the conductive line 108 and / or the via 110 may be or may include, for example, aluminum, copper, aluminum-copper, tungsten, titanium, a combination of the foregoing, and the like. The upper layer 108ul of the conductive line 108 includes a conductive bonding layer 108b and a cavity electrode 108a.

[0051] like Figure 8As shown in the cross-sectional view 800, a dielectric layer stack 801 is formed over the interconnect structure 104. In some embodiments, the dielectric layer stack 801 includes a first dielectric layer 124, a second dielectric layer 126, and a third dielectric layer 128. In some embodiments, the first dielectric layer 124 may be or may include, for example, aluminum oxide (e.g., Al2O3), another metal oxide, etc., and / or may have a thickness t3 of about 300 angstroms or in a range of about 285 angstroms to 315 angstroms. In some embodiments, the second dielectric layer 126 may be or may include, for example, silicon nitride, silicon carbide, etc., and / or may have a thickness t4 of about 300 angstroms or in a range of about 285 angstroms to 315 angstroms. In other embodiments, the third dielectric layer 128 may be or may include, for example, an oxide (e.g., silicon dioxide, another suitable oxide, etc.), and / or may have a thickness t5 of about 2,000 angstroms or in a range of about 1,900 angstroms to 2,100 angstroms. In some embodiments, the dielectric layer stack 801 has a thickness t1. In some embodiments, the dielectric layers in the dielectric layer stack 801 can each be formed by physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), thermal oxidation, or another suitable deposition or growth process.

[0052] In some embodiments, the first dielectric layer 124, the second dielectric layer 126, and / or the third dielectric layer 128 may each be formed by a CVD process having, for example, a + / -5% process control over the thickness of the layer. For example, if the target thickness of the third dielectric layer 128 is 2,000 angstroms, the third dielectric layer 128 may be formed by a high density plasma (HDP) CVD process such that the thickness t5 of the third dielectric layer 128 is in the range of about 1,900 angstroms to 2,100 angstroms. Thus, the thickness t1 of the dielectric layer stack 801 may be precisely formed such that the thickness t1 has a tolerance of + / -5% of the target thickness.

[0053] like Fig. 9 As shown in the cross-sectional view 900, Figure 8The structure shown performs one or more etching processes to define the dielectric structure 130 and the plurality of stopper structures 118a-118c and expose the upper surface of the conductive bonding layer 108b. The one or more etching processes may include performing a first etching process to define the dielectric structure 130. The first etching process may include: forming a mask layer (not shown) over the third dielectric layer 128; exposing unmasked areas of the third dielectric layer 128 and underlying layers to one or more etchants to define the dielectric structure 130; and performing a removal process to remove the mask layer. In addition, the one or more etching processes may include performing a second etching process to define the first stopper structure 118a and / or the second stopper structure 118b. The second etching process may include: forming a mask layer (not shown) over the third dielectric layer 128; exposing the unmasked areas of the third dielectric layer 128 and the underlying layers to one or more etchants to define the first stopper structure 118a and the second stopper structure 118b; and performing a removal process to remove the mask layer. In addition, a third etching process may be performed to define the third stopper structure 118c. In yet other embodiments, the third etching process may remove the third stopper structure 118c and may expose the upper surface of the cavity electrode 108a (not shown). In addition, a fourth etching process may be performed to expose the upper surface of the conductive bonding layer 108b.

[0054] In some embodiments, the first stopper structure 118a and the second stopper structure 118b each include a first stopper layer 114 and a second stopper layer 116. In some embodiments, the first stopper layer 114 may be or may include, for example, aluminum oxide (e.g., Al2O3), another metal oxide, etc. In other embodiments, the second stopper layer 116 may be or may include, for example, silicon nitride, silicon carbide, etc. The third stopper structure 118c may be or may include, for example, aluminum oxide (e.g., Al2O3), another metal oxide, etc. In some embodiments, the upper surface of each stopper structure 118a-118c may be a rough upper surface and / or may include a plurality of protrusions configured to prevent sticking, so that the stopper structures 118a-118c may be configured as anti-sticking structures.

[0055] like Fig.10As shown in the cross-sectional view 1000, a sacrificial substrate 1002 is provided and a MEMS substrate 134 is bonded to the sacrificial substrate 1002 through an upper isolation layer 502. In some embodiments, the sacrificial substrate 1002 may be, for example, a bulk substrate (e.g., a bulk silicon substrate) or some other suitable substrate. The upper isolation layer 502 may be or may include, for example, an oxide (e.g., silicon dioxide) or another suitable dielectric material, and / or may be formed by CVD, PVD, thermal oxidation, or another suitable deposition process. A MEMS substrate 134 is provided and then bonded to the upper isolation layer 502. In some embodiments, the MEMS substrate 134 may be, for example, a bulk substrate (e.g., a bulk silicon substrate) or some other suitable substrate. In some embodiments, the bonding process may include performing a fusion bond process. A movable membrane 136 is formed within the MEMS substrate 134. In some embodiments, the movable membrane 136 may be formed by a selective ion implantation process. The selective ion implantation process may include: forming a mask layer (not shown) over the MEMS substrate 134; selectively implanting dopants (e.g., n-type dopants) into unmasked areas of the MEMS substrate 134; and performing a removal process to remove the mask layer. In other embodiments, the movable membrane 136 may be formed by, for example, CVD, PVD, electroless plating, sputtering, or another suitable growth or deposition process (not shown). In yet other embodiments, the movable membrane 136 may be formed over the MEMS substrate 134 (not shown) and may include aluminum, copper, titanium, tantalum, etc.

[0056] In addition, if Fig.10 As shown in the cross-sectional view 1000, an isolation dielectric layer 132 is formed over the MEMS substrate 134 and / or the movable membrane 136. In some embodiments, the isolation dielectric layer 132 may be or may include, for example, an oxide (e.g., silicon dioxide), another suitable dielectric material, etc. A conductive bonding layer 1004 is formed over the isolation dielectric layer 132. In some embodiments, the conductive bonding layer 1004 may be formed by, for example, CVD, PVD, electroless plating, sputtering, or other suitable deposition or growth processes. In addition, in some embodiments, the conductive bonding layer 1004 may be or may include, for example, germanium, gold, nickel, combinations of the foregoing, etc., and / or may have a thickness tcb of about 3,800 angstroms or in a range of about 3,610 angstroms to 3,980 angstroms.

[0057] like Fig.11 As shown in the cross-sectional view 1100, the conductive bonding layer ( Fig.10 1004) is patterned to define a conductive bonding structure 122. The conductive bonding structure 122 has a thickness tcb. In some embodiments, the conductive bonding layer ( Fig.10The patterning as shown in 1004 may include: Fig.10 1004) is formed on a mask layer (not shown); the conductive bonding layer ( Fig.10 The unmasked areas of the mask layer 1004 are exposed to one or more etchants to define the conductive bonding structure 122; and a removal process is performed to remove the mask layer.

[0058] like Fig.12 As shown in the cross-sectional view 1200, Fig.11 The structure shown is rotated 180 degrees and the conductive bonding structure 122 is then bonded to the conductive bonding layer 108b, thereby sealing the cavity 120 with a first gas pressure. In other embodiments, the bonding process can also seal the outer cavity 1204 with a second gas pressure. The outer cavity 1204 is defined between the inner sidewall of the dielectric structure 130 and the outer sidewall of the conductive bonding structure 122. In some embodiments, the bonding process includes performing eutectic bonding. In such embodiments, the eutectic bonding can reach a maximum bonding temperature of about 420 degrees Celsius or 500 degrees Celsius. In other embodiments, the eutectic bonding may include applying a bonding force to the upper surface of the sacrificial substrate 1002 toward the substrate 102. In some embodiments, the bonding force may be, for example, in the range of about 30 kilonewtons (KN) to 40 kilonewtons. In some embodiments, during eutectic bonding, the maximum bonding temperature and / or the bonding force may cause the thickness tcb of the conductive bonding structure 122 to decrease. This may be due in part to the conductive bonding structure 122 being pressed against the conductive bonding layer 108b, and material from the conductive bonding structure 122 being forced to push laterally along the upper surface 108us of the conductive bonding layer 108b (e.g., see dashed box 1202). In other embodiments, the bottom surface 122bs of the conductive bonding structure 122 may be disposed below the upper surface of the conductive bonding layer 108b in a vertical direction. In yet other embodiments, during eutectic bonding, the dielectric structure 130 may act as a bonding stop structure such that when the lower surface of the isolation dielectric layer 132 contacts the upper surface of the dielectric structure 130, the reduction in the thickness tcb of the conductive bonding structure 122 stops. Therefore, the distance ds between the movable membrane 136 and the third stopper structure 118c is defined by the thickness t1 of the dielectric structure 130. In yet other embodiments, if the dielectric structure 130 is omitted (not shown), accurate control of the distance ds is mitigated or eliminated. Therefore, by accurately defining the thickness t1 of the dielectric structure 130 (e.g., by utilizing Figure 8 By setting the deposition process shown) to a suitable value, the distance ds can be accurately defined.

[0059] The dashed box 1202 shows some embodiments of a close-up of the interface between the conductive bonding structure 122 and the conductive bonding layer 108b after the eutectic bonding process. The bottom surface 122bs of the conductive bonding structure 122 may include a plurality of protrusions extending below the upper surface 108us of the conductive bonding layer 108b. In addition, the conductive bonding structure 122 may include lateral segments 122ls1, 122ls2, which extend laterally from the sidewalls 122sw1, 122sw2 of the conductive bonding structure 122 to above the upper surface 108us, respectively. In some embodiments, the lateral segments 122ls1, 122ls2 may be caused by the material from the body of the conductive bonding structure 122 being pushed laterally to the outside of the sidewalls 122sw1, 122sw2 due to the bonding force and / or the maximum bonding pressure. This in turn may result in a reduction in thickness tcb. In some embodiments, the second stopper layer 116 may be configured, for example, as a barrier and / or a wall to prevent the lateral segments 122ls1, 122ls2 of the conductive bonding structure 122 from extending laterally over the cavity electrode 108a. This in turn may, for example, prevent an electrical short between the movable membrane 136 and / or the cavity electrode 108a and the lateral segments 122ls1, 122ls2.

[0060] like Fig.13 As shown in the cross-sectional view 1300, a removal process is performed to remove the sacrificial substrate ( Fig.12 1002) and / or upper isolation layer ( Fig.12 In some embodiments, the removal process may include performing an etching process (eg, blanket etching), a planarization process (eg, CMP process), a grinding process (eg, mechanical grinding process), a combination thereof, or another suitable removal process.

[0061] Fig.14 A method 1400 of forming a microelectromechanical system (MEMS) device having a conductive bonding structure surrounded by a dielectric structure according to the present disclosure is shown. Although method 1400 is shown and / or described as a series of actions or events, it should be understood that the method is not limited to the order or actions shown. Therefore, in some embodiments, the actions may be performed in an order different from the order shown and / or may be performed simultaneously. In addition, in some embodiments, the actions or events shown may be subdivided into multiple actions or events, which may be performed separately or simultaneously with other actions or sub-actions in batches. In some embodiments, some of the actions or events shown may be omitted, and other actions or events not shown may be included.

[0062] At act 1402, an interconnect structure is formed over a substrate. The interconnect structure includes a conductive bonding layer. Figure 7Cross-sectional view 700 corresponding to some embodiments of act 1402 is shown.

[0063] At act 1404, a dielectric layer stack having a first thickness is formed over the interconnect structure. Figure 8 Cross-sectional view 800 corresponding to some embodiments of act 1404 is shown.

[0064] At act 1406, the dielectric layer stack is patterned to define a dielectric structure and one or more stopper structures along an upper surface of the interconnect structure. Fig. 9 Cross-sectional view 900 corresponding to some embodiments of act 1406 is shown.

[0065] At act 1408, a movable membrane is formed on the MEMS substrate. Fig.10 Cross-sectional view 1000 corresponding to some embodiments of act 1408 is shown.

[0066] At act 1410, an isolation dielectric layer is formed over a MEMS substrate. Fig.10 A cross-sectional view 1000 corresponding to some embodiments of act 1410 is shown.

[0067] At act 1412, a conductive bonding ring structure is formed over the MEMS substrate. The conductive bonding ring structure has a second thickness greater than the first thickness. Fig.10 and Fig.11 Cross-sectional view 1000 and cross-sectional view 1100 are shown corresponding to some embodiments of act 1412 .

[0068] At act 1414, a eutectic bonding process is performed to bond the conductive bonding ring structure to the conductive bonding layer. The eutectic bonding process seals a first cavity disposed between inner sidewalls of the conductive bonding ring structure. Fig.12 Cross-sectional view 1200 corresponding to some embodiments of act 1414 is shown.

[0069] Thus, in some embodiments, the present disclosure is directed to a microelectromechanical system (MEMS) device having a conductive bonding structure surrounded by a dielectric structure, wherein the conductive bonding structure is bonded to an underlying interconnect structure by eutectic bonding.

[0070] In some embodiments, the present application provides a microelectromechanical system (MEMS) device, which includes: a substrate; an interconnect structure overlying the substrate; a MEMS substrate overlying the interconnect structure, wherein the MEMS substrate includes a movable membrane; a dielectric structure disposed between the interconnect structure and the MEMS substrate; and a conductive bonding structure sandwiched between the interconnect structure and the MEMS substrate, wherein the conductive bonding structure is laterally spaced apart from sidewalls of the dielectric structure between sidewalls of the dielectric structure, wherein the conductive bonding structure, the MEMS substrate and the interconnect structure at least partially define a cavity, wherein the movable membrane overlies the cavity and is laterally spaced apart from sidewalls of the conductive bonding structure between sidewalls of the conductive bonding structure.

[0071] In the above-mentioned MEMS device, the conductive bonding structure directly contacts a conductive bonding layer disposed in the interconnect structure, wherein an upper surface of the conductive bonding layer defines a bottom surface of the first cavity.

[0072] In the above-mentioned MEMS device, the conductive bonding structure extends laterally across the upper surface of the conductive bonding layer.

[0073] In the above-mentioned MEMS device, the conductive bonding structure includes germanium and the conductive bonding layer includes aluminum copper.

[0074] In the above-mentioned MEMS device, the dielectric structure overlies the conductive bonding layer.

[0075] In the above-mentioned MEMS device, the thickness of the dielectric structure is smaller than the thickness of the conductive bonding structure.

[0076] In the above-mentioned MEMS device, the dielectric structure includes: a first dielectric layer overlying the interconnect structure; a second dielectric layer overlying the first dielectric layer; and a third dielectric layer overlying the second dielectric layer, wherein the first dielectric layer, the second dielectric layer and the third dielectric layer include different dielectric materials from each other.

[0077] The above-mentioned MEMS device further includes: a second cavity defined between the outer periphery of the conductive bonding structure and the inner sidewall of the dielectric structure.

[0078] In the above-mentioned MEMS device, it also includes: a cavity dielectric layer, which is arranged along the upper surface of the interconnect structure, wherein the cavity dielectric layer is adjacent to the first cavity and is located under the movable membrane.

[0079] In the above-mentioned MEMS device, it also includes: one or more stopper structures overlying the upper surface of the interconnect structure and arranged in the first cavity, wherein the stopper structure is located below the movable membrane.

[0080] In some embodiments, the present application provides a microelectromechanical system (MEMS) structure, which includes: a substrate; an interconnect structure overlying the substrate, wherein the interconnect structure includes a conductive bonding layer; a MEMS substrate overlying the interconnect structure, wherein the MEMS substrate includes a movable membrane; a conductive bonding ring structure sandwiched between the interconnect structure and the MEMS substrate, wherein the conductive bonding ring structure contacts the conductive bonding layer of the interconnect structure, wherein the conductive bonding ring structure, the MEMS substrate and the interconnect structure at least partially define a first cavity, wherein the movable membrane overlies the first cavity and is laterally spaced between side walls of the conductive bonding ring structure; a dielectric structure sandwiched between the interconnect structure and the MEMS substrate, wherein the conductive bonding ring structure is laterally spaced between inner side walls of the dielectric structure; and an anti-stiction structure disposed along an upper surface of the interconnect structure and within the first cavity, wherein the anti-stiction structure includes one or more protrusions extending toward the MEMS substrate, wherein the anti-stiction structure comprises the same material as the dielectric structure.

[0081] In the above-mentioned micro-electromechanical system structure, the dielectric structure includes a first dielectric layer, a second dielectric layer and a third dielectric layer, wherein the second dielectric layer is arranged between the first dielectric layer and the third dielectric layer, wherein the first dielectric layer, the second dielectric layer and the third dielectric layer each contain dielectric materials different from each other, and wherein the anti-adhesion structure includes the second dielectric layer overlying the first dielectric layer.

[0082] In the above-mentioned micro-electromechanical system structure, the lateral segment of the conductive bonding ring structure extends across the upper surface of the conductive bonding layer and directly contacts the upper surface of the conductive bonding layer, and the lower surface of the conductive bonding ring structure includes one or more protrusions arranged below the upper surface of the conductive bonding layer in the vertical direction.

[0083] In the above-mentioned MEMS structure, it also includes: a groove extending through the MEMS substrate, wherein the groove laterally surrounds the outer periphery of the movable membrane; and one or more contact holes extending from the interconnect structure to the movable membrane.

[0084] In some embodiments, the present application provides a method for forming a microelectromechanical system (MEMS) device, the method comprising: forming an interconnect structure over a substrate, wherein the interconnect structure comprises a conductive bonding layer; forming a dielectric layer stack having a first thickness over the interconnect structure; patterning the dielectric layer stack to define a dielectric structure and one or more stop structures along an upper surface of the interconnect structure; forming a movable membrane over a MEMS substrate; forming an isolation dielectric layer over the MEMS substrate; forming a conductive bonding ring structure over the MEMS substrate, wherein the conductive bonding ring structure has a second thickness greater than the first thickness; and performing a eutectic bonding process to bond the conductive bonding ring structure to the conductive bonding layer, wherein the eutectic bonding process seals a first cavity disposed between inner side walls of the conductive bonding ring structure.

[0085] In the above method, the second thickness of the conductive bonding ring structure decreases during the eutectic bonding process, wherein the decrease in the second thickness stops when a lower surface of the isolation dielectric layer contacts an upper surface of the dielectric structure.

[0086] In the above method, the process of forming the dielectric layer stack includes: depositing a first dielectric layer having a first dielectric thickness on the interconnect structure, wherein the first dielectric layer is deposited by a chemical vapor deposition process; depositing a second dielectric layer having the first dielectric thickness on the first dielectric layer, wherein the second dielectric layer is deposited by a chemical vapor deposition process; and depositing a third dielectric layer having a second dielectric thickness greater than the first dielectric thickness on the second dielectric layer, wherein the third dielectric layer is deposited by a high-density plasma chemical vapor deposition process.

[0087] In the above method, the conductive bonding ring structure includes germanium.

[0088] In the above method, the eutectic bonding process seals the first cavity with a first gas pressure and seals the second cavity with a second gas pressure, wherein the second cavity is defined between an outer perimeter of the conductive bonding ring structure and a sidewall of the dielectric structure.

[0089] The features of several embodiments are summarized above so that those skilled in the art can better understand the various aspects of the present disclosure. Those skilled in the art will understand that they can easily use the present disclosure as a basis for designing or modifying other processes and structures to implement the same purposes and / or achieve the same advantages as the embodiments described herein. Those skilled in the art will also recognize that these equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they can make various changes, substitutions and modifications herein without departing from the spirit and scope of the present disclosure.

Claims

1. A micro-electromechanical system device, comprising: substrate; an interconnect structure overlying the substrate; a micro-electromechanical system substrate overlying the interconnect structure, wherein the micro-electromechanical system substrate includes a movable membrane; a dielectric structure disposed between the interconnect structure and the MEMS substrate; as well as a conductive bonding structure interposed between the interconnect structure and the MEMS substrate, wherein the conductive bonding structure is laterally spaced between sidewalls of the dielectric structure, wherein the conductive bonding structure, the MEMS substrate, and the interconnect structure at least partially define a first cavity, wherein the movable membrane overlies the first cavity and is laterally spaced between sidewalls of the conductive bonding structure, The thickness of the dielectric structure is smaller than the thickness of the conductive bonding structure. 2 . The MEMS device of claim 1 , wherein the conductive bonding structure directly contacts a conductive bonding layer disposed within the interconnect structure, wherein an upper surface of the conductive bonding layer defines a bottom surface of the first cavity. 3 . The MEMS device of claim 2 , wherein the conductive bonding structure extends laterally across the upper surface of the conductive bonding layer. 4 . The MEMS device of claim 2 , wherein the conductive bonding structure comprises germanium and the conductive bonding layer comprises aluminum copper. The MEMS device of claim 2 , wherein the dielectric structure overlies the conductive bonding layer.

6. The MEMS device of claim 1 , wherein the dielectric structure comprises: A first dielectric layer overlying the interconnect structure; a second dielectric layer overlying the first dielectric layer; as well as The third dielectric layer is overlying the second dielectric layer, wherein the first dielectric layer, the second dielectric layer and the third dielectric layer comprise different dielectric materials.

7. The MEMS device according to claim 1, wherein: Also includes: The second cavity is defined between the outer periphery of the conductive bonding structure and the inner sidewall of the dielectric structure.

8. The MEMS device according to claim 1, further comprising: A cavity dielectric layer is disposed along an upper surface of the interconnect structure, wherein the cavity dielectric layer is adjacent to the first cavity and is located below the movable membrane.

9. The MEMS device according to claim 1, further comprising: One or more stop structures overlying an upper surface of the interconnect structure and disposed within the first cavity, wherein the stop structures are located below the movable membrane.

10. A micro-electromechanical system structure, comprising: substrate; an interconnect structure overlying the substrate, wherein the interconnect structure comprises a conductive bonding layer; a micro-electromechanical system substrate overlying the interconnect structure, wherein the micro-electromechanical system substrate includes a movable membrane; a conductive bonding ring structure interposed between the interconnect structure and the MEMS substrate, wherein the conductive bonding ring structure contacts the conductive bonding layer of the interconnect structure, wherein the conductive bonding ring structure, the MEMS substrate, and the interconnect structure at least partially define a first cavity, wherein the movable membrane overlies the first cavity and is laterally spaced between sidewalls of the conductive bonding ring structure; as well as A dielectric structure is sandwiched between the interconnect structure and the MEMS substrate, wherein the conductive bonding ring structure is laterally spaced between inner sidewalls of the dielectric structure, wherein a thickness of the dielectric structure is less than a thickness of the conductive bonding ring structure.

11. The MEMS structure according to claim 10, further comprising: An anti-stiction structure is disposed along the upper surface of the interconnect structure and within the first cavity, wherein the anti-stiction structure comprises one or more protrusions extending toward the MEMS substrate, wherein the anti-stiction structure comprises the same material as the dielectric structure.

12. The microelectromechanical system structure according to claim 11, wherein the dielectric structure comprises a first dielectric layer, a second dielectric layer and a third dielectric layer, wherein the second dielectric layer is disposed between the first dielectric layer and the third dielectric layer, wherein the first dielectric layer, the second dielectric layer and the third dielectric layer each comprise a dielectric material different from each other, and wherein the anti-stiction structure comprises the second dielectric layer overlying the first dielectric layer.

13. A micro-electromechanical system structure according to claim 10, wherein the lateral segment of the conductive bonding ring structure extends across the upper surface of the conductive bonding layer and directly contacts the upper surface of the conductive bonding layer, and wherein the lower surface of the conductive bonding ring structure includes one or more protrusions arranged below the upper surface of the conductive bonding layer in a vertical direction.

14. The MEMS structure according to claim 10, further comprising: a trench extending through the MEMS substrate, wherein the trench laterally surrounds an outer perimeter of the movable membrane; as well as One or more contact vias extend from the interconnect structure to the movable membrane.

15. A method of forming a micro-electromechanical system device, the method comprising: forming an interconnect structure on the substrate; forming a dielectric layer stack having a first thickness over the interconnect structure; patterning the dielectric layer stack to define a dielectric structure and one or more stopper structures along an upper surface of the interconnect structure; forming a movable membrane on a MEMS substrate; forming an isolation dielectric layer on the micro-electromechanical system substrate; forming a conductive bonding ring structure on the MEMS substrate, wherein the conductive bonding ring structure has a second thickness greater than the first thickness; as well as A eutectic bonding process is performed to bond the conductive bonding ring structure to the interconnect structure, wherein the eutectic bonding process seals a first cavity disposed between inner sidewalls of the conductive bonding ring structure.

16. The method of claim 15, wherein the second thickness of the conductive bonding ring structure decreases during the eutectic bonding process, wherein the decrease in the second thickness stops when a lower surface of the isolation dielectric layer contacts an upper surface of the dielectric structure.

17. The method according to claim 15, wherein the process of forming the dielectric layer stack comprises: Depositing a first dielectric layer having a first dielectric thickness over the interconnect structure, wherein the first dielectric layer is deposited by a chemical vapor deposition process; depositing a second dielectric layer having the first dielectric thickness over the first dielectric layer, wherein the second dielectric layer is deposited by a chemical vapor deposition process; as well as A third dielectric layer having a second dielectric thickness greater than the first dielectric thickness is deposited over the second dielectric layer, wherein the third dielectric layer is deposited by a high density plasma chemical vapor deposition process. The method of claim 15 , wherein the conductive bonding ring structure comprises germanium.

19. The method of claim 15, wherein the eutectic bonding process seals the first cavity with a first gas pressure and seals a second cavity with a second gas pressure, wherein the second cavity is defined between an outer perimeter of the conductive bonding ring structure and a sidewall of the dielectric structure.

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