Semiconductor structure and method for manufacturing the same

Abstract

Embodiments of the present invention relate to semiconductor structures and methods for manufacturing the same. Embodiments of the present invention provide a micro-electromechanical system (MEMS) structure, comprising: a device substrate having a first region and a second region different from the first region; a cover substrate bonded to the device substrate; a first cavity in the first region and between the device substrate and the cover substrate, wherein the first cavity has a first cavity pressure; a second cavity in the second region and between the device substrate and the cover substrate, wherein the second cavity has a second cavity pressure lower than the first cavity pressure; a passivation layer in the first cavity; and a release material above the passivation layer, wherein the release material includes a top surface and a sidewall exposed to the first cavity.

Description

Technical Field

[0001] Embodiments of the present invention relate to a semiconductor structure and a method for manufacturing the same. Background Art

[0002] Microelectromechanical systems (MEMS) refer to a class of devices that exhibit mechanical properties, such as having components that can move or deform. MEMS devices may include mechanical elements and / or electronics for sensing.

[0003] Micro-electromechanical system devices, such as pressure sensors, gyroscopes, accelerometers, position sensors, etc., are widely used in many modern electronic devices. For example, MEMS accelerometers can be commonly found in mobile devices, automobiles (e.g., in airbag deployment systems), tablet computers, or consumer devices. Summary of the invention

[0004] Embodiments of the present invention relate to a microelectromechanical system (MEMS) structure, comprising: a device substrate having a first region and a second region different from the first region; a cover substrate bonded over the device substrate; a first cavity in the first region and between the device substrate and the cover substrate, wherein the first cavity has a first cavity pressure; a second cavity in the second region and between the device substrate and the cover substrate, wherein the second cavity has a second cavity pressure lower than the first cavity pressure; a passivation layer in the first cavity; and a release material over the passivation layer, wherein the release material comprises a top surface and sidewalls exposed to the first cavity.

[0005] Embodiments of the present invention relate to a microelectromechanical system (MEMS) structure, comprising: a device substrate having a first region and a second region different from the first region; a cover substrate bonded over the device substrate; a first cavity in the first region and between the device substrate and the cover substrate, wherein the first cavity has a first cavity pressure; a second cavity in the second region and between the device substrate and the cover substrate, wherein the second cavity has a second cavity pressure lower than the first cavity pressure; a passivation layer in the first cavity; and a release material in the passivation layer, wherein the release material comprises a groove having a depth greater than about 10% of a thickness of the release material.

[0006] An embodiment of the present invention relates to a method for manufacturing a semiconductor structure, comprising: providing a device substrate, wherein the device substrate includes a first region and a second region different from the first region; forming an outgassing material in the first region; partially removing a portion of the outgassing material to expose a sidewall of the outgassing material; and bonding the device substrate to a cover substrate to form a first cavity in the first region and a second cavity in the second region. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Aspects of the embodiments of the present invention are best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be noted that, in accordance with standard practice in the industry, the various components are not drawn to scale. In fact, the dimensions of the various components may be arbitrarily increased or reduced for clarity of discussion.

[0008] Figure 1 is a cross-sectional view of a micro-electromechanical system structure according to some embodiments of the present invention.

[0009] Figure 2A is a perspective view of a portion of an outgassing material and a portion of a passivation layer according to some embodiments of the present invention.

[0010] Figure 2B is a perspective view of a portion of an outgassing material and a portion of a passivation layer according to some embodiments of the present invention.

[0011] Figure 2C is a perspective view of a portion of an outgassing material and a portion of a passivation layer according to some embodiments of the present invention.

[0012] Figure 2D is a perspective view of a portion of an outgassing material and a portion of a passivation layer according to some embodiments of the present invention.

[0013] Figure 2E is a perspective view of a portion of an outgassing material and a portion of a passivation layer according to some embodiments of the present invention.

[0014] Figure 2F is a perspective view of a portion of an outgassing material and a portion of a passivation layer according to some embodiments of the present invention.

[0015] Figure 3A A flow chart representing a method for fabricating a micro-electromechanical system structure according to some embodiments of the present invention is shown.

[0016] Figure 3B A flow chart representing a method for fabricating a micro-electromechanical system structure according to some embodiments of the present invention is shown.

[0017] Figures 4 to 12 is a cross-sectional view of a micro-electromechanical system structure during an intermediate stage of manufacturing operations according to some embodiments of the present invention.

[0018] Fig.13A is a cross-sectional view of a micro-electromechanical system structure during an intermediate stage of manufacturing operations according to some embodiments of the present invention.

[0019] Figures 13B to 13Cis a cross-sectional view of a micro-electromechanical system structure during an intermediate stage of manufacturing operations according to some embodiments of the present invention.

[0020] Figures 14 to 15 is a cross-sectional view of a micro-electromechanical system structure during an intermediate stage of manufacturing operations according to some embodiments of the present invention. DETAILED DESCRIPTION

[0021] The following disclosure provides many different embodiments or examples for implementing the different features of the target provided. The following describes the specific examples of components and arrangements to simplify the embodiments of the present invention. Of course, these are only examples and do not wish to limit. For example, the first component in the following description is formed on or above the second component and may include an embodiment in which the first component and the second component are formed to be directly in contact, and may also include an embodiment in which an additional component may be formed between the first component and the second component so that the first component and the second component may not be directly in contact. In addition, the embodiments of the present invention may repeat element symbols and / or letters in various examples. This repetition is for the purpose of simplification and clarity, and does not specify the relationship between the various embodiments and / or configurations discussed per se.

[0022] Additionally, for ease of description, spatially relative terms, such as "below," "beneath," "lower," "above," "upper," and the like, may be used herein to describe the relationship of one element or component to another element or components, as illustrated 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 likewise interpreted accordingly.

[0023] Although the numerical ranges and parameters describing the broad range of embodiments of the present invention are approximate values, the numerical values ​​described in the specific examples are reported as accurately as possible. However, any numerical value essentially contains a specific error caused by the standard deviation found in the corresponding test measurement. Again, as used herein, the term "substantially", "approximately" or "approximately" generally means within the value or range that can be expected by a person of ordinary skill in the art. Alternatively, when considered by a person of ordinary skill in the art, the term "substantially", "approximately" or "approximately" means within the acceptable standard error of the mean value. A person of ordinary skill in the art can understand that the acceptable standard error can be changed according to different technologies. Except in the operation / working examples, or unless otherwise explicitly specified, all numerical ranges, amounts, values ​​and percentages (such as the numerical ranges, amounts, values ​​and percentages for the ratios of the amount of materials, durations, temperatures, operating conditions, amounts and the like disclosed herein) should be understood to be modified by the terms "substantially", "approximately" or "approximately" in all examples. Therefore, unless otherwise specified, the numerical parameters described in the embodiments of the present invention and the appended claims are approximate values ​​that can be changed as needed. At the very least, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Ranges may be expressed herein as from one endpoint to the other endpoint or between two endpoints. Unless otherwise specified, all ranges disclosed herein include endpoints.

[0024] Microelectromechanical systems (MEMS) devices are widely used, for example, pressure sensors are used to detect pressure, and motion sensors are used for motion-activated user interfaces in consumer electronic devices such as smart phones, tablet computers, game consoles, smart TVs, and automotive collision detection systems. In recent generations of MEMS integrated circuits, multiple MEMS devices can be integrated into one integrated chip to enable the chip to have multiple functions. Specifically, to capture more accurate and complete movement in three-dimensional space, motion sensors often utilize a combination of accelerometers and gyroscopes. To meet consumer demand for low cost, high quality, and small device footprint, accelerometers and gyroscopes can be incorporated into the same chip.

[0025] However, different MEMS devices typically operate at different cavity pressures. For example, in the case of a gyroscope device, a relatively low cavity pressure (i.e., a higher vacuum) is desired because it can provide a preferred measurement of displacement that is converted to a signal. Conversely, in the case of an accelerometer device, a relatively high cavity pressure is desired because air damping can be used to improve the reliability of movable components (e.g., proof masses) in the accelerometer. Therefore, MEMS devices typically require a sealed chamber that is maintained at a controlled pressure level that enables optimized operation of the device. Depending on the device type, the pressure level of each device can range from a vacuum (e.g., 0.001 millibar or even lower) to a specific degree of pressure. To achieve a desired reference pressure in the cavity of the device, a sealing technique can be performed to seal the cavity. In addition, to increase the pressure in a cavity that requires a higher cavity pressure, an outgassing material can be incorporated into a predetermined cavity to individually increase the cavity pressure in the predetermined cavity.

[0026] However, a challenge in forming a MEMS structure with several cavities requiring different cavity pressures is the performance of the device requiring a higher cavity pressure. For example, an outgassing material in a selected cavity may not produce enough outgassing gas. When the cavity pressure of a MEMS accelerometer is too low, the performance of sensing its motion and / or reliability may degrade. It is arduous to integrate the device(s) requiring a higher cavity pressure and the device(s) requiring a higher vacuum level on the same integrated chip.

[0027] The embodiment of the present invention provides a MEMS structure and a method for manufacturing the MEMS structure to improve the outgassing ability of outgassing materials in a selected cavity so as to increase the cavity pressure in the selected cavity, so as to realize the integration of different devices with different cavity pressure requirements on an integrated chip.

[0028] refer to Figure 1 , Figure 1 1 is a cross-sectional view of a microelectromechanical system structure according to some embodiments of the present invention. The MEMS structure 100 includes at least a device substrate 101, a cover substrate 309, and a release material 105. The device substrate 101 includes a first region R1 and a second region R2 different from the first region R1. In some embodiments, the device substrate 101 further includes an intermetallic dielectric (IMD) material at its top surface. The cover substrate 309 is bonded to the device substrate 101, thereby having a first cavity C1 and a second cavity C2 between the device substrate 101 and the cover substrate 309, wherein the first cavity C1 is in the first region R1, and the second cavity C2 is in the second region R2. The first cavity C1 has a first cavity pressure, and the second cavity C2 has a second cavity pressure lower than the first cavity pressure.

[0029] The bonding in the embodiments of the present invention may be referred to as a method of attaching substrates, including but not limited to eutectic bonding (e.g., CuSn, AlGe, AuSi), fusion bonding, thermal compression, or any other suitable wafer-level bonding. In some embodiments, a plurality of top metal lines 201 are at a bonding region between the device substrate 101 and the cap substrate 309, wherein the top metal lines 201 include a conductive material, such as aluminum copper, aluminum, copper, tin, gold, a combination thereof, or other metals or metal alloys suitable for bonding. In some embodiments, the MEMS structure 100 may further include a titanium layer 202 (which is not at a bonding region) above the top metal lines 201 and not directly between the device substrate 101 and the cap substrate 309. In some embodiments, the titanium layer 202 may optionally include a silicon oxynitride (SiON) layer. In some other embodiments, the titanium layer 202 may optionally be replaced by a titanium nitride (TiN) layer.

[0030] The device substrate may refer to a substrate having circuits, semiconductor devices and / or semiconductor structures (e.g., accelerometers, gyroscopes, barometers, magnetometers, position sensors, etc.). For example, the MEMS structure 100 may include a combination of an accelerometer and a gyroscope, and this MEMS structure 100 may be incorporated into a 6-axis device. However, embodiments of the present invention are not limited thereto, for example, this MEMS structure 100 may also be incorporated into a 7-axis device, a 9-axis device, or the like. For example, the accelerometer is placed in the first region R1 and the gyroscope is placed in the second region R2, and the second cavity pressure is lower than the first cavity pressure. In some embodiments, the second cavity pressure is at a high vacuum level. In some embodiments, the accelerometer may include a movable component 323 in the first cavity C1, for example, the movable component 323 may be confined to a proof mass in the first cavity C1, wherein the movement of the movable component 323 in the first cavity C1 is used to measure acceleration.

[0031] The MEMS structure 100 may include a passivation layer 111 in the first region R1 and the second region R2. In some embodiments, the passivation layer 111 may include multiple layers, for example, a first passivation layer 102 above the device substrate 101 and surrounding some top metal lines 201, a second passivation layer 103 above the first passivation layer 102, and a third passivation layer 104 above the second passivation layer 103. In some embodiments, the first passivation layer 102 includes plasma assisted oxide (PEOX), the second passivation layer 103 may include silicon-rich oxide, and the third passivation layer 104 includes silicon nitride (SiN), but the embodiments of the present invention are not limited thereto. In some other alternative embodiments, the passivation layer 111 may include one material. In some other alternative embodiments, the passivation layer 111 may include other combinations of multiple passivation materials.

[0032] The MEMS structure 100 may include a degassing zone Z1 and a first redistribution zone Z2 in a first cavity C1, and a second redistribution zone Z2' in a second cavity C2. A degassing barrier layer 121 is formed in the first redistribution zone Z2 and the second redistribution zone Z2' above the passivation layer 111. In some embodiments, the degassing barrier layer 121 may include silicon nitride (SiN) or the like. The trenches T1 and T2 penetrate the passivation layer 111 and the degassing barrier layer 121 in the first redistribution zone Z2 and the second redistribution zone Z2', respectively. The redistribution layer 120 may be directly contacted and surrounded by the sidewalls of the trenches T1 in the first redistribution zone Z2 and the trenches T2 in the second redistribution zone Z2', wherein the redistribution layer 120 includes one or more conductive materials (e.g., metals). For example, the redistribution layer 120 may include a first layer 122 that is above the outgassing barrier layer 121 and in direct contact with the sidewalls of the first trench T1 and the second trench T2, and a second layer 123 that is above the first layer 122. In some embodiments, the first layer 122 includes titanium. In some embodiments, the second layer includes titanium nitride. In some embodiments, the MEMS structure 100 may further include other semiconductor structures (such as fins or passivation structures) as needed. In some embodiments, these semiconductor structures may include a passivation layer 111 (as previously discussed, in some embodiments, it may include a first passivation layer 102 above the device substrate 101, a second passivation layer 103 above the first passivation layer 102, and a third passivation layer 104 above the second passivation layer 103), and a outgassing barrier layer 121 that covers the top surface of the passivation layer 111. The location of these semiconductor structures may be outside the first cavity C1 and the second cavity C2, or alternatively in one of the first cavity C1 and the second cavity C2.

[0033] The MEMS structure 100 includes at least a passivation layer 111 and a gas release material 105 above the passivation layer 111 in a gas release zone Z1. The gas release material 105 includes a gas release material that can be used to bond the device substrate 101 to the cap substrate 309 (which will be in the Fig.15 106. The outgassing material 105 may be a material that generates a large amount of outgassing gas after increasing the temperature of the device substrate 101 to the cover substrate 309. For example, the cavity pressure in the range of about 0.001 mbar to about 2 mbar may be increased to a range of about 10 mbar to about 300 mbar by utilizing the outgassing material 105, which may be regarded as a result of "generating a large amount of outgassing gas" in embodiments of the present invention. It should be understood that the rate of outgassing gas generation at a first type eutectic bonding temperature for Cu-Sn, Al-Sn, or Au-Sn (e.g., about 260 degrees Celsius) is lower than the rate at a second type eutectic bonding temperature for Al-Ge (e.g., about 420 degrees Celsius). The outgassing material 105 to be used in embodiments of the present invention may depend on the eutectic bonding temperature used in the operation of bonding the device substrate 101 to the cover substrate 309.

[0034] The outgassing material 105 may include a high density plasma oxide (HDP oxide, such as silicon oxide formed by a high density plasma tool), a plasma assisted oxide, a polymer, polysilicon, amorphous silicon, polyimide, an organic compound, an oxide compound, a poly(p-xylene) derivative, or other suitable outgassing dielectric material. In some embodiments, depending on the type of material, the outgassing gas may include hydrogen (H2), argon (Ar), and / or other types of gases generated from the outgassing material 105 described above. The bonding in the embodiments of the present invention may be referred to as a method of attaching a substrate, including (but not limited to) eutectic bonding (e.g., CuSn, AlGe, AuSi), fusion bonding, thermal compression, or any other suitable wafer-level bonding. For example, during the operation of CuSi bonding, the MEMS structure 100 may be heated to about 200° C. to about 300° C.; during the operation of AlGe eutectic bonding, the MEMS structure 100 may be heated to about 420° C. to about 440° C.; during the operation of AuSi bonding, the MEMS structure 100 may be heated to about 360° C. to about 380° C. Therefore, the selection of the type of outgassing material 105 may be adjusted based on the desired temperature of the bonding operation of the device substrate 101 and the cap substrate 309 .

[0035] The MEMS structure 100 may further include a top metal line 201 surrounded by a passivation layer 111 and below the outgassing material 105, if desired. In some embodiments, the MEMS structure 100 may further include a titanium layer 202 (or a titanium nitride layer) above this top metal line 201. In some embodiments, the titanium layer 202 may include a silicon oxynitride (SiON) layer, if desired. In some embodiments, a top surface S105 of the outgassing material 105 may be recessed toward the device substrate 101. In some embodiments, a thickness H between the top surface S105 of the outgassing material 105 and a top surface of the titanium layer 202 or the top metal line 201 directly below the outgassing material 105 is in a range of about 0.5 μm and about 10 μm. In some examples, the passivation layer 111 between the outgassing material 105 and the titanium layer 202 is about 3400 angstroms. In some embodiments, the width of the outgassing material 105 is in the range of about 10 μm to about 2,000 μm, which can provide a sufficient amount of outgassing gas during the outgassing operation while complying with the device miniaturization trend. In some embodiments, the passivation layer 111 has a groove recessed from the top surface, and the outgassing material 105 is filled in the groove of the passivation layer 111 and exposed to the first cavity C1 from the passivation layer 111. In other words, the passivation layer 111 has an inner sidewall S111, and the outgassing material 105 is laterally surrounded by the inner sidewall S111 of the passivation layer 111. In some embodiments, the bottom surface of the groove is below the top surface of the first passivation layer 102. In addition, in some embodiments, the inner sidewall of the outgassing material 105 is exposed to the first cavity C1, as will be described later. Figures 2A to 2FVarious different embodiments of outgassing material 105 are discussed in . In some embodiments, this structure results from partial removal of outgassing material 105 during manufacturing operations, wherein the partially removed outgassing material 105 may have a greater total surface area exposed to cavity C1 than if it were not partially removed.

[0036] refer to Figure 2A , Figure 2A 1 is a perspective view of a portion of a release material and a portion of a passivation layer according to some embodiments of the present invention. In some embodiments, a plurality of blocks of the release material 105 are separated from each other. The depth d of the space SP between two blocks of the release material 105 is the same as the thickness X of the release material 105 (i.e., d=1.0*X), and the bottom surface RB of the groove is exposed to the first cavity C1. In other words, the surface of the passivation layer 111 (or in some embodiments, specifically, the surface of the first passivation layer 102) is exposed from the release material 105 to the first cavity C1. In addition, the sidewall SW of the release material 105 is exposed to the first cavity C1. In some embodiments, the spacing a between each block of the release material 105 may be in the range of about 0.1 μm to about 20 μm. In some embodiments, the width b of each block of the release material 105 may be in the range of about 0.1 μm to about 20 μm. In some embodiments, the length c of each block of the release material 105 may be in the range of about 0.1 μm to about 20 μm. The thickness X of the outgassing material 105 (and Figure 2A In some embodiments, the depth d) of the space SP is greater than or equal to 0.1 μm. In some embodiments, the thickness X of the outgassing material 105 is less than or equal to 10 μm. It should be noted that the sidewall SW of the outgassing material 105 is not limited to a vertical sidewall, that is, the embodiments of the present invention also include an inclined sidewall or a curved sidewall.

[0037] refer to Figure 2B , Figure 2B is a perspective view of a portion of a release material and a portion of a passivation layer according to some embodiments of the present invention. Alternatively, a depth d of a space SP between two blocks of the release material 105 is less than a thickness X of the release material 105. In some embodiments, the depth d is in a range from about 0.1 times to up to 1.0 times the thickness X, and a sidewall SW of the release material 105 is exposed to the first cavity C1. In other words, the release material 105 has a lower surface L105 between a top surface S105 of the release material 105 and a bottom surface RB of the groove, wherein the lower surface L105 is exposed to the first cavity C1. In addition, a plurality of blocks of the release material 105 are connected by a lower portion 105' of the release material 105, and the passivation layer 111 is not exposed from the release material 105. Herein, a spacing a between each block of the release material 105, a width b of each block, and a length c of each block are similar to Figure 2AIn some embodiments, when the depth d is greater than 0.1 times the thickness X (or greater than 0.1 μm in some alternative embodiments), the amount of outgassing gas generated by the outgassing material 105 during the time interval of processing at high temperature is substantially increased.

[0038] refer to Figure 2C , Figure 2C is a perspective view of a portion of a release material and a portion of a passivation layer according to some embodiments of the present invention. Alternatively, in some embodiments, multiple blocks of the release material 105 are separated from each other. The depth d of the space SP between two blocks of the release material 105 is the same as the thickness X of the release material 105 (i.e., d=1.0*X), and the bottom surface RB of the groove is exposed to the first cavity C1. In other words, the surface of the passivation layer 111 (or in some embodiments, specifically, the surface of the first passivation layer 102) is exposed from the release material 105 to the first cavity C1. In addition, the sidewall SW of the release material 105 is exposed to the first cavity C1. Herein, the spacing a between each block of the release material 105, the width b of each block, and the length c of each block are similar to Figure 2A The length c of each piece of the outgassing material 105 may be in the range of about 0.1 μm to the width W of the outgassing material 105 (shown in FIG. Figure 1 within the range of .

[0039] refer to Figure 2D , Figure 2D is a perspective view of a portion of a release material and a portion of a passivation layer according to some embodiments of the present invention. Alternatively, a depth d of a space SP between two blocks of the release material 105 is less than a thickness X of the release material 105. In some embodiments, the depth d is in a range from about 0.1 times to up to 1.0 times the thickness X, and a sidewall SW of the release material 105 is exposed to the first cavity C1. In other words, the release material 105 has a lower surface L105 between a top surface S105 of the release material 105 and a bottom surface RB of the groove, wherein the lower surface L105 is exposed to the first cavity C1. In addition, a plurality of blocks of the release material 105 are connected by a lower portion 105' of the release material 105, and the passivation layer 111 is not exposed from the release material 105. Herein, a spacing a between each block of the release material 105, a width b of each block, and a length c of each block are similar to Figure 2C In some embodiments, when the depth d is greater than 0.1 times the thickness X (or greater than 0.1 μm in some alternative embodiments), the amount of outgassing gas generated by the outgassing material 105 during the interval period at high temperature is substantially increased.

[0040] refer to Figure 2E , Figure 2E 1 is a perspective view of a portion of a release material and a portion of a passivation layer according to some embodiments of the present invention. Alternatively, in some embodiments, a plurality of grooves 1050 are recessed from a top surface S105 of the release material 105. Herein, the depth of the grooves 1050 is in a range of about 0.1 times the thickness X of the release material 105 to 1.0 times the thickness X of the release material 105, and the sidewalls SW of the grooves 1050 are exposed to the first cavity C1. If the depth of the grooves 1050 is the same as the thickness X of the release material 105, the passivation layer 111 may be exposed from the release material 105. If the depth of the grooves 1050 is less than the thickness X of the release material 105, the passivation layer 111 may be covered by the release material 105, while the bottom surface L1050 of the grooves 1050 is exposed to the first cavity C1. It should be noted that each of the grooves 1050 may be the same or may be different; and the shape of the grooves 1050 is not limited herein, wherein the cross-section of the grooves 1050 may be circular, polygonal, or irregular.

[0041] refer to Figure 2F , Figure 2F 1 is a perspective view of a portion of a outgassing material and a portion of a passivation layer according to some embodiments of the present invention. Alternatively, in some embodiments, the top surface of the passivation layer 111 may be partially covered by the outgassing material 105 while being partially exposed from the outgassing material 105. A trench 1050 may be formed as desired, wherein the sidewall(s) SW of the trench 1050, a portion of the bottom surface RB of the recess, and one or more bottom surfaces L1050 of the trench 1050 are exposed to the first cavity C1.

[0042] refer to Figure 3A , Figure 3A A flow chart representing a method for fabricating a micro-electromechanical system structure according to some embodiments of the present invention is shown. The method 1000 for fabricating a micro-electromechanical system structure includes: providing a device substrate, wherein the device substrate includes a first region and a second region (operation 1001, which can be referred to as Figure 4 ); forming a degassing material in the first zone (operation 1003, which can be referred to as Figures 5 to 6 ); partially removing a portion of the outgassing material to expose a sidewall of the outgassing material (operation 1006, which may refer to Figures 13A to 13B or 13C); and bonding the device substrate to the cover substrate to form a first cavity in the first region and a second cavity in the second region (operation 1009, which may refer to Fig.15 ).

[0043] refer to Figure 3B , Figure 3BA flow chart representing a method for fabricating a micro-electromechanical system structure according to some embodiments of the present invention is shown. The method 2000 for fabricating a micro-electromechanical system structure includes: providing a device substrate, wherein the device substrate includes a first region and a second region (operation 2001, which can be referred to as Figure 4 ); forming a passivation layer over the first region and the second region (operation 2004, which can refer to Figure 4 ); blanket depositing outgassing material in the first zone and the second zone (operation 2007, which can be referred to as Figure 5 ); removing the outgassing material in the second zone (operation 2009, which can be referred to as Figure 6 ); forming a gas release barrier layer above the gas release material (operation 2011, which can be referred to as Figure 7 ); partially removing a portion of the outgassing material in the first zone to expose the sidewall of the outgassing material (operation 2013, which can be referred to as Figures 13A to 13B or 13C); removing the outgassing barrier layer (operation 2016, which can be referred to as Fig.14 ); and bonding the device substrate to the cover substrate to form a first cavity in the first region and a second cavity in the second region (operation 2018, which may refer to Fig.15 ).

[0044] refer to Figure 4 , Figure 4 is a cross-sectional view of a micro-electromechanical system structure during an intermediate stage of a manufacturing operation according to some embodiments of the present invention. A device substrate 101 including a first region R1 and a second region R2 different from the first region R1 is provided. A plurality of top metal lines 201 are formed over the device substrate, wherein the top metal lines 201 may include a conductive material such as aluminum copper, aluminum, copper, tin, gold, combinations thereof, or other metals or metal alloys suitable for bonding. In some embodiments, a titanium layer 202 over the top metal lines 201 may be formed over each of the top metal lines 201. In some embodiments, the titanium layer 202 may optionally include a silicon oxynitride (SiON) layer. In some other embodiments, the titanium layer 202 may be replaced by a titanium nitride (TiN) layer.

[0045] A passivation layer 111 is further formed in the first region R1 and the second region R2, wherein the passivation layer surrounds and covers the top metal line 201 and the titanium layer 202. In some embodiments, the passivation layer 111 may include multiple layers, for example, a first passivation layer 102 above the device substrate 101 and surrounding some of the top metal lines 201, a second passivation layer 103 above the first passivation layer 102, and a third passivation layer 104 above the second passivation layer 103. In some embodiments, the first passivation layer 102 includes plasma assisted oxide (PEOX), the second passivation layer 103 may include silicon-rich oxide, and the third passivation layer 104 includes silicon nitride (SiN), but the embodiments of the present invention are not limited thereto. In some other alternative embodiments, the passivation layer 111 may include one material. In some other alternative embodiments, the passivation layer 111 may include other combinations of multiple passivation materials. Therefore, a recess R111 recessed from the top surface of the passivation layer 111 is formed. In some embodiments, the recess R111 is tapered toward the device substrate 101. In some alternative embodiments, the groove R111 may have substantially vertical sidewalls. In some embodiments, the groove R111 may be formed by using a first mask 901, wherein partially removing the passivation layer 111 may require a photolithography operation and / or an etching operation. In the above-described embodiments of the first passivation layer 102, the second passivation layer 103, and the third passivation layer 104 constituting the passivation layer 111, the bottom surface of the groove R111 is in the first passivation layer 102, wherein the first passivation layer 102 may be partially removed. If desired, in order to control the amount of the passivation layer 111 to be removed and the depth of the groove R111, an endpoint detection technique may be utilized. For example, the groove R111 is formed above at least the top metal line 201 and / or a titanium layer 202, wherein the top surface of the titanium layer 202 may be used as a reference point for endpoint detection during the removal of the passivation layer 111. For example, the thickness of the passivation layer 111 is about 10,000 angstroms, and the distance between the bottom surface of the groove R111 and the top surface of the titanium layer 202 is about 3,400 angstroms.

[0046] refer to Figure 5 , Figure 5 is a cross-sectional view of a micro-electromechanical system structure during an intermediate stage of a manufacturing operation according to some embodiments of the present invention. A gas release layer 105' is formed by blanket deposition over the passivation layer 111 and in the recess R111, covering the first region R1 and the second region R2. For example, the thickness of the formed gas release layer 105' is about 10,500 angstroms, and the distance between the top surface of the titanium layer 202 and the top surface of the gas release layer 105' directly above the recess R111 is in the range of about 12,000 angstroms to about 16,000 angstroms. As previously described Figure 1, the outgassing layer 105′ may include a high density plasma oxide (HDP oxide, such as silicon oxide formed by a high density plasma tool), a plasma assisted oxide, a polymer, polysilicon, amorphous silicon, polyimide, an organic compound, an oxide compound, a poly(p-xylene) derivative, or other suitable outgassing dielectric. In some embodiments, during the operation of depositing the outgassing layer 105′ (e.g., the HDP oxide layer), silane (SiH 4 ), oxygen (O 2 ) and / or argon (Ar) or other suitable reactive gases may be supplied.

[0047] refer to Figure 6 , Figure 6 is a cross-sectional view of a micro-electromechanical system structure during an intermediate stage of a manufacturing operation according to some embodiments of the present invention. Subsequently, a chemical mechanical planarization (CMP) operation is performed from the top surface of the outgassing layer 105' to remove the outgassing layer 105' outside the recess R111 and expose the top surface of the passivation layer 111 (or the top surface of the third passivation layer 104). After performing the CMP operation, the distance between the top surface of the titanium layer 202 and the top surface of the outgassing material 105 in the recess R111 is reduced, for example, to about 9,000 angstroms, but the present invention is not limited thereto. It should be noted that because the device to be formed in the second region R2 may require a lower chamber pressure or a higher vacuum level (for example, a gyroscope), the outgassing layer 105' within the second region R2 is completely removed to prevent the outgassing layer 105' from generating outgassing gas in the sealed device formed in the second region R2 in subsequent manufacturing operations, which may reduce device performance. Furthermore, a recessing effect may be induced during the CMP operation performed on the outgassing layer 105 ′, and thus, after the CMP operation, the top surface S105 of the outgassing material 105 in the recess R111 may be recessed toward the device substrate 101 .

[0048] refer to Figure 7 , Figure 7is a cross-sectional view of a microelectromechanical system structure during an intermediate stage of a manufacturing operation according to some embodiments of the present invention. A gas release barrier layer 121 is then formed over the gas release material 105 in the first region R1 and the second region R2. The gas release barrier layer 121 may be capable of hindering the gas release generated by the gas release material 105 and the passivation layer 111 (depending on the material of the passivation layer 111) from penetrating from its top surface. In some embodiments, the gas release barrier layer 121 may include a nitride, such as silicon nitride (SiN), or other suitable barrier layers. The gas release barrier layer 121 reduces the amount of gas release from the gas release material 105 during the time interval until the gas release barrier layer 121 is removed, and thus may increase the amount of gas release from the gas release material 105 thereafter. In addition, in the case where some materials of the passivation layer 111 also generate gas at high temperatures, the gas release barrier layer 121 may limit the gas release from the passivation layer 111 (especially in the second region R2).

[0049] refer to Figure 8 , Figure 8 is a cross-sectional view of a MEMS structure during an intermediate stage of a manufacturing operation according to some embodiments of the present invention. A trench T1 and a trench T2 are formed in the first redistribution area Z2 and the second redistribution area Z2', respectively, thereby exposing the top surface of the titanium layer 202. In this article, the trench T1 and the trench T2 penetrate through the passivation layer 111 and the gas release barrier layer 121. The trench T1 and the trench T2 can be formed by using a second mask 902, wherein removing the passivation layer 111 may require a photolithography operation and / or an etching operation. For example, the critical dimension of the trench may be about 2 μm, but the embodiments of the present invention are not limited thereto.

[0050] refer to Fig. 9 , Fig. 9 is a cross-sectional view of a microelectromechanical system structure during an intermediate stage of a manufacturing operation according to some embodiments of the present invention. A redistribution layer 120 is formed above the degassing barrier layer 121 and on the sidewalls of the trench T1 in the first redistribution zone Z2 and the sidewalls of the trench T2 in the second redistribution zone Z2'. In addition, the redistribution layer 120 directly contacts the exposed top surface of the titanium layer 202. In this article, the redistribution layer 120 includes one or more conductive materials (such as metals). For example, the redistribution layer 120 may include a first layer 122 above the degassing barrier layer 121 and in direct contact with the exposed top surface of the titanium layer 202, the sidewalls of the trench T1, and the sidewalls of the trench T2, and a second layer 123 above the first layer 122. For example, the first layer 122 includes titanium, and the second layer includes titanium nitride (TiN).

[0051] refer to Fig.10 , Fig.109 is a cross-sectional view of a MEMS structure during an intermediate stage of a manufacturing operation according to some embodiments of the present invention. The portion of the redistribution layer 120 above the outgassing barrier layer 121 is removed by patterning with a third mask 903. The removal of the redistribution layer 120 may require a photolithography operation and / or an etching operation.

[0052] refer to Fig.11 , Fig.11 is a cross-sectional view of a MEMS structure during an intermediate stage of a manufacturing operation according to some embodiments of the present invention. Some top metal lines 201 are not connected to the redistribution layer 120 and are not directly under the outgassing material 105. The passivation layer 111 and the outgassing barrier layer 121 above these top metal lines 201 (neither connected to the redistribution layer 120 nor directly under the outgassing material 105) are removed so as to expose the entire top surface of the titanium layer 202, thereby forming a plurality of spaces SC above this titanium layer 202. In some embodiments, the bottom surface of the space SC is below the top surface of the top metal line 201 but above the top surface of the device substrate 101. The space SC can be formed by using a fourth mask 904 to remove a portion of the passivation layer 111 and a portion of the outgassing barrier layer 121, which may require a photolithography operation and / or an etching operation.

[0053] refer to Fig.12 , Fig.12 2 is a cross-sectional view of a MEMS structure during an intermediate stage of a manufacturing operation according to some embodiments of the present invention. Subsequently, the titanium layer 202 exposed from the space SC is removed, wherein the removal operation may include a photolithography operation and / or an etching operation. Some of the top metal lines 201 are thereby exposed.

[0054] refer to Figures 2A to 2F and 13A, Fig.13A 9 is a cross-sectional view of a MEMS structure during an intermediate stage of a manufacturing operation according to some embodiments of the present invention. Subsequently, the outgassing material 105 and the outgassing barrier layer 121 are partially removed by patterning using a sixth mask 906, wherein the removal operation may include a photolithography operation and / or an etching operation. Figures 2A to 2F Various embodiments regarding the shape of the outgassing material 105 are discussed in detail, wherein in some embodiments, the groove 1050 (eg, Figures 2A to 2F ) of at least one of the inner side walls, the groove (e.g., Figure 2A , 2C , 2E or 2F) and / or the outgassing material 105 (e.g., Figure 2B , 2D , 2E or 2F) is exposed. By partially removing the outgassing material 105, the total surface area of ​​the outgassing material 105 is increased and / or close to the groove R111 (such as Figure 4Specifically, because the outgassing material 105 generates outgassing gas primarily at the surface area, the total exposed surface area is positively correlated to the outgassing rate of outgassing gas generated by the outgassing material 105 in a given period of time. Thus, when the outgassing material 105 is used in a subsequent operation (e.g., a bonding operation, as will be described later in Fig.15 When heated to a specific temperature in the process discussed in the foregoing, the amount of outgassing gas generated by the outgassing material 105 may increase within a limited period of time of this heating operation.

[0055] refer to Fig. 13B , Fig. 13B 907 is a cross-sectional view of a micro-electromechanical system structure during an intermediate stage of a manufacturing operation according to some embodiments of the present invention. Some portions of the passivation layer 111 at the bottom of the space SC are further removed by patterning with the seventh mask 907. Because the passivation layer 111 may generate outgassing gas in some embodiments (depending on the material of the passivation layer 111), by further removing the additional passivation layer 111, the amount of outgassing gas generated by the passivation layer 111 in subsequent operations (especially in the sealing device in the second region R2) can be reduced. It should be noted that performing Fig.13A The operations and Fig. 13B The order of operations discussed in is not limited.

[0056] refer to Fig. 13C , Fig. 13C is a cross-sectional view of a MEMS structure during an intermediate stage of a manufacturing operation according to some embodiments of the present invention. Alternatively, in some embodiments, the sixth mask 906' may be used to perform Fig.13A The operations and Fig. 13B The operations discussed in the foregoing are to facilitate manufacturing efficiency. It should be noted that because the critical size of the removed portion of the outgassing material 105 (e.g., Figures 2A to 2D The distance a discussed in Figures 2A to 2F The other critical dimensions discussed in ) are smaller than the critical dimensions of the space SC, so when patterned by the single sixth mask 906 ′, the etching rate at the outgassing material 105 may be lower than the etching rate at the bottom of the space SC.

[0057] refer to Fig.14 , Fig.14 3 is a cross-sectional view of a MEMS structure during an intermediate stage of manufacturing operations according to some embodiments of the present invention. Because some annealing operations (e.g., treatment of the intermetallic dielectric or the interlayer dielectric) may be performed before the cap substrate 309 is bonded to the device substrate 101, the portion of the outgassing material 105 may be partially removed (as previously described). Figures 13A to 13BIn some embodiments, the outgassing barrier layer 121 is removed after the device substrate 101 and the cover substrate 309 are bonded together (as discussed in the embodiments of the present invention or 13C), whereby the outgassing material 105 can outgas during the bonding operation, rather than substantially releasing most of the outgassing gas before bonding the device substrate 101 and the cover substrate 309, wherein the outgassing gas is not generated in the sealed cavity as expected. In some embodiments, the outgassing barrier layer 121 can be removed by a blanket etching operation. In some embodiments, the outgassing barrier layer 121 in the first redistribution region Z2 and the second redistribution region Z2' is retained to hinder the passivation layer 111 from generating outgassing gas during the subsequent bonding operation.

[0058] refer to Fig.15 , Fig.15 is a cross-sectional view of a MEMS structure during an intermediate stage of manufacturing operations according to some embodiments of the present invention. Subsequently, the device substrate 101 is bonded to the cap substrate 309, wherein the bonding operation may include, but is not limited to, eutectic bonding (e.g., CuSn, AlGe, AuSi), fusion bonding, thermal compression, or any other suitable wafer-level bonding. For example, when the top metal line 201 comprises aluminum copper and the bonding region of the cap substrate 309 comprises germanium, an AlGe eutectic bonding may be performed. It should be noted that, as Fig.12 As discussed in , removing the titanium layer 202 can allow the top metal line 201 to act as a pad and directly contact the cap substrate 309, thereby promoting bonding adhesion. By bonding the cap substrate 309 to the device substrate 101, a first cavity C1 and a second cavity C2 are formed in the first region R1 and the second region R2, respectively. Because the bonding operation can be performed in a reduced pressure environment, both the first cavity C1 and the second cavity C2 initially have a lower cavity pressure (in some embodiments, a high vacuum level). As previously described, Figure 1 As discussed in , to individually increase the cavity pressure in the first cavity C1 , the outgassing material 105 in the first cavity C1 generates outgassing gas during the bonding operation.

[0059] Typically, outgassing gas may be generated from the outgassing material 105 by high temperature stimulation. During the bonding operation, the temperature of the device substrate 101 (including the first region R1 and the second region R2) and the cap substrate 309 is increased. For the example of an AlGe eutectic bonding operation, the temperature is increased to at least 400° C., such as in the range of about 420° C. to about 440° C. In addition, in embodiments where the outgassing material 105 includes a high density plasma (HDP) oxide, the outgassing material 105 may generate hydrogen (H2), and in some embodiments further includes argon (Ar), which may be derived from Figure 5 However, it should be noted that the type of outgassing gas depends on the nature of the outgassing material 105, the manufacturing operation involved and the type.

[0060] As before Figures 7 to 14As discussed in the foregoing, in order to generate a larger amount of outgassing gas from the outgassing material 105 into the first cavity C1, especially during the time interval of the bonding operation, the outgassing barrier layer 121 is formed above the outgassing material 105 before the rewiring operation, and then Fig.15 The outgassing barrier layer 121 is removed before the bonding operation discussed in , thereby reducing the amount of outgassing gas released into the environment rather than being retained in the sealed first cavity C1. Figures 1 to 2F As discussed in FIGS. 13A to 13C , because the outgassing material 105 generates outgassing gas primarily at the surface area, the total exposed surface area is positively correlated to the outgassing rate of outgassing gas generated by the outgassing material 105 in a given time period. For example, during a bonding operation, the outgassing material 105 is raised to over 400° C. for about a predetermined time period (e.g., 10 minutes) and then cooled down. By increasing the total exposed surface area (which is exposed to the first cavity C1 during the bonding operation), the amount of outgassing gas generated can be increased within the limited time period of this heating operation. By partially removing the outgassing material 105, at least the sidewall or the lower surface below the top surface is exposed to the first cavity C1, where more outgassing gas can be generated at the surface of the outgassing material 105.

[0061] After the cap substrate 309 is bonded to the device substrate 101, thereby forming the MEMS structure 100, the temperature of the MEMS structure 100 is reduced. At a temperature lower than the bonding temperature, the amount of outgassing gas generated by the outgassing material 105 is greatly reduced.

[0062] In some embodiments, an accelerometer is formed in the first region R1, wherein during the bonding operation, a movable component 323 (which may be a proof mass) is enclosed in the first cavity C1. In some embodiments, a gyroscope is formed in the second region, wherein the second cavity C2 has a cavity pressure lower than the first cavity C1. In some embodiments, the cap substrate 309 and the device substrate 101 may be singulated into a plurality of chips by dicing, and a device including the first cavity C1 and a device including the second cavity C2 are integrated into one integrated chip, so the integrated chip may be able to perform a variety of functions. It should be noted that the type of device included in the MEMS structure 100 is not limited in the embodiments of the present invention.

[0063] Some embodiments of the present invention provide a microelectromechanical system (MEMS) structure, comprising: a device substrate having a first region and a second region different from the first region; a cover substrate bonded above the device substrate; a first cavity in the first region and between the device substrate and the cover substrate, wherein the first cavity has a first cavity pressure; a second cavity in the second region and between the device substrate and the cover substrate, wherein the second cavity has a second cavity pressure lower than the first cavity pressure; a passivation layer in the first cavity; and a release material above the passivation layer, wherein the release material includes a top surface and sidewalls exposed to the first cavity.

[0064] Some embodiments of the present invention provide a microelectromechanical system (MEMS) structure, comprising: a device substrate having a first region and a second region different from the first region; a cover substrate bonded to the device substrate; a first cavity in the first region and between the device substrate and the cover substrate, wherein the first cavity has a first cavity pressure; a second cavity in the second region and between the device substrate and the cover substrate, wherein the second cavity has a second cavity pressure lower than the first cavity pressure; a passivation layer in the first cavity; and a release material in the passivation layer, wherein the release material comprises a groove having a depth greater than about 10% of a thickness of the release material.

[0065] Some embodiments of the present invention provide a method for manufacturing a semiconductor structure, comprising: providing a device substrate, wherein the device substrate includes a first region and a second region different from the first region; forming an outgassing material in the first region; partially removing a portion of the outgassing material to expose a sidewall of the outgassing material; and bonding the device substrate to a cover substrate to form a first cavity in the first region and a second cavity in the second region.

[0066] The foregoing summarizes the features of several embodiments so that those skilled in the art may better understand aspects of the embodiments of the present invention. Those skilled in the art will appreciate that they may readily use the embodiments of the present invention as a basis for designing or modifying other operations and structures for carrying out the same purposes and / or achieving the same advantages of 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 embodiments of the present invention, and that they may make various changes, substitutions, and modifications herein without departing from the spirit and scope of the embodiments of the present invention.

[0067] In addition, the scope of the present application is not intended to be limited to the specific embodiments of the processes, machines, manufactures, material compositions, components, methods, and steps described in this specification. As will be readily understood by those skilled in the art from the disclosure of the embodiments of the present invention, currently existing or later developed processes, machines, manufactures, material compositions, components, methods, or steps that perform substantially the same functions or achieve substantially the same results as the corresponding embodiments described herein may be utilized according to the embodiments of the present invention. Therefore, the appended claims intend to include such processes, machines, manufactures, material compositions, components, methods, or steps within their scope.

[0068] Explanation of symbols

[0069] 100 Micro-electromechanical systems (MEMS) structures

[0070] 101 Device substrate

[0071] 102 first passivation layer

[0072] 103 Second passivation layer

[0073] 104 Third passivation layer

[0074] 105 Outgassing Material

[0075] 105' Lower section / gas release layer

[0076] 111 Passivation layer

[0077] 120 Rewiring Layer

[0078] 121 Gas release barrier layer

[0079] 122 First Floor

[0080] 123 Second Floor

[0081] 201 Top Metal Wire

[0082] 202 Titanium layer

[0083] 309 Cover substrate

[0084] 323 Removable components

[0085] 901 First Mask

[0086] 902 Second Mask

[0087] 903 Third Mask

[0088] 904 The Fourth Mask

[0089] 906 Sixth Mask

[0090] 906' Sixth Mask

[0091] 907 The Seventh Mask

[0092] 1000 Methods

[0093] 1001 Operation

[0094] 1003 Operation

[0095] 1006 Operation

[0096] 1009 Operation

[0097] 1050 Groove

[0098] 2000 Methods

[0099] 2001 Operation

[0100] 2004 Operation

[0101] 2007 Operation

[0102] 2009 Operation

[0103] 2011 Operation

[0104] 2013 Operation

[0105] 2016 Operation

[0106] 2018 Operations

[0107] a Spacing

[0108] b Width

[0109] c Length

[0110] C1 First cavity

[0111] C2 Second cavity

[0112] d Depth

[0113] H Thickness

[0114] L105 bottom surface

[0115] L1050 bottom surface

[0116] R1 Zone 1

[0117] R2 Zone 2

[0118] R111 Groove

[0119] RB bottom surface

[0120] S105 top surface

[0121] S111 Inner wall

[0122] SC Space

[0123] SP Space

[0124] SW side wall

[0125] T1 Groove

[0126] T2 Groove

[0127] W Width

[0128] X Thickness

[0129] Z1 Gas release zone

[0130] Z2 The first rewiring area

[0131] Z2' The second rewiring area

Claims

1. A micro-electromechanical system (MEMS) structure, comprising: a device substrate having a first region and a second region different from the first region; a cover substrate bonded over the device substrate; a first cavity in the first region and between the device substrate and the cap substrate, wherein the The first chamber has a first chamber pressure; a second chamber in the second region and between the device substrate and the cap substrate, wherein the second chamber has a second chamber pressure lower than the first chamber pressure; a passivation layer having a groove in the first cavity; as well as an outgassing material in the recess of the passivation layer, wherein the outgassing material comprises a top surface and sidewalls exposed to the first cavity, The outgassing material is laterally surrounded by inner sidewalls of the passivation layer. 2 . The MEMS structure of claim 1 , wherein the outgassing material is separated from the device substrate by the passivation layer. 3 . The MEMS structure of claim 1 , wherein the outgassing material comprises a material capable of generating a significant amount of outgassing gas after being subjected to temperatures used to bond the device substrate and the cap substrate. The MEMS structure of claim 1 , further comprising a movable component in the first cavity. The MEMS structure of claim 1 , wherein the top surface of the outgassing material is concave toward the device substrate. The MEMS structure of claim 1 , wherein a bottom of the recess is exposed from the outgassing material to the first cavity. 7 . The MEMS structure of claim 1 , wherein the outgassing material comprises a lower surface between the top surface and a bottom of the recess, the lower surface being exposed to the first cavity.

8. The MEMS structure of claim 1 wherein the outgassing material comprises an oxide.

9. A micro-electromechanical system (MEMS) structure, comprising: a device substrate having a first region and a second region different from the first region; a cover substrate bonded over the device substrate; a first cavity in the first region and between the device substrate and the cap substrate, wherein the The first chamber has a first chamber pressure; a second chamber in the second region and between the device substrate and the cap substrate, wherein the second chamber has a second chamber pressure lower than the first chamber pressure; a passivation layer having a groove in the first cavity; as well as an outgassing material in the recess of the passivation layer, wherein the outgassing material comprises a groove having a depth greater than about 10% of a thickness of the outgassing material, The outgassing material is laterally surrounded by inner sidewalls of the passivation layer.

10. The MEMS structure of claim 9, wherein a sidewall of the trench is exposed to the first cavity. The MEMS structure of claim 9 , wherein a bottom surface of the trench is exposed to the first cavity.

12. The MEMS structure of claim 9, wherein a bottom of the recess is exposed from the outgassing material.

13. A method for manufacturing a semiconductor structure, comprising: providing a device substrate, wherein the device substrate comprises a first region and a second region different from the first region; forming a passivation layer over the first region and the second region; forming a groove in the passivation layer above the first region; forming an outgassing material in the groove of the passivation layer such that the outgassing material is laterally surrounded by inner sidewalls of the passivation layer; partially removing a portion of the outgassing material to expose a sidewall of the outgassing material; and The device substrate is bonded to a cap substrate to form a first cavity in the first region and a second cavity in the second region.

14. The method of claim 13, wherein forming the outgassing material comprises: blanket depositing the outgassing material in the first region and the second region; and The outgassing material in the second zone is removed.

15. The method according to claim 13 further includes forming a titanium layer in the first area before forming the passivation layer, wherein forming the groove in the passivation layer above the first area further includes removing the passivation layer above the titanium layer using the titanium layer as a reference point to form the groove. 16 . The method of claim 13 , further comprising forming an outgassing barrier layer over the outgassing material before partially removing the portion of the outgassing material. 17 . The method of claim 16 , further comprising removing the outgassing barrier layer after partially removing the portion of the outgassing material.

18. The method of claim 13, wherein forming the outgassing material comprises depositing an oxide material capable of generating a significant amount of outgassing gas after bonding the device substrate to a cap substrate.

19. The method of claim 13, wherein bonding the device substrate to the cap substrate comprises forming a eutectic bond.

20. The method of claim 13, wherein partially removing the portion of the outgassing material comprises exposing a portion of the passivation layer from the outgassing material.

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