TWI472472B - Mems structure and method for fabricating the same - Google Patents

Description

Microelectromechanical system structure and manufacturing method thereof

The present invention relates to a microelectromechanical system (MEMS) structure and a method of fabricating the same, and more particularly to a microelectromechanical system structure having a guard ring and a method of fabricating the same.

Microelectromechanical systems (MEMS) are tiny electro-mechanical components fabricated in miniaturized package structures that are manufactured with technology much similar to that used to make integrated circuits, but MEMS devices interact more with their surrounding environments than they do. Traditional integrated circuits, such as mechanical, optical or magnetic interactions. The MEMS device can include very small electromechanical components such as motors, pumps, valves, switches, capacitors, accelerometers, sensors, capacitive sensors, pixels, microphones or actuators, and the like. These electromechanical components usually use a micromechanical structure to interact with semiconductor components such as integrated circuits, and are designed according to the principle of capacitance to cause displacement to achieve a predetermined target.

In general, MEMS uses semiconductor process technology to design components on a germanium wafer, and then integrates the MEMS into a bulk circuit in a single block. Due to the significant increase in semiconductor process technology, the component size of MEMS is designed to be continuously reduced and integrated. Therefore, the development of MEMS that can be integrated with integrated circuit chips made by semiconductor processes is nowadays. A major trend in development.

However, the current process of MEMS components is usually done in semi-conductive After the process of the latter part of the institutional process, it is carried out. That is to say, after completing the integrated circuit, a plurality of thick polycrystalline germanium film layers are deposited in the microelectromechanical system region as a structure of the microelectromechanical system components. Since the overall structure of the MEMS components is made of a polycrystalline silicon material, problems such as stress are easily encountered. Furthermore, polycrystalline germanium materials are subject to distortion due to repeated mechanical stresses, reducing component lifetime and resulting in poor component performance. In addition, although deposition of polysilicon is a common semiconductor process, polycrystalline germanium materials are not formed in the latter stage of general semiconductor processing, so the process of forming microelectromechanical system components requires additional procedures, which increases process steps and time costs. Moreover, in practice, the use of a polycrystalline germanium material as the structure of the microelectromechanical system is easily limited by the thickness of the deposited polycrystalline germanium film layer, thus affecting the components.

In view of this, the present invention provides a microelectromechanical system structure having a guard ring.

The present invention further provides a method of fabricating a microelectromechanical system that can be integrated with a complementary metal-oxide semiconductor (CMOS) process to reduce process steps.

The invention provides a microelectromechanical system structure comprising a fixing portion and a movable portion. The fixing portion is disposed on the substrate and connected to the substrate. The movable portion is suspended on the substrate, and the movable portion includes at least two first metal layers, a first protection ring and a first dielectric layer. The first guard ring connects the adjacent two first metal layers to define a first closed space between the adjacent two first metal layers between. The first dielectric layer is disposed in the first enclosed space and connects the adjacent two first metal layers.

In an embodiment of the invention, the first guard ring substantially corresponds to the contour of each of the first metal layers.

In an embodiment of the invention, the material of the first guard ring comprises a metal.

In an embodiment of the invention, the fixing portion includes at least two second metal layers, a second guard ring and a second dielectric layer. The second guard ring connects the adjacent two second metal layers to define a second closed space between the adjacent two second metal layers. The second dielectric layer is disposed in the second enclosed space and connects the adjacent two second metal layers.

In an embodiment of the invention, the second guard ring substantially corresponds to the contour of each of the second metal layers.

In an embodiment of the invention, the material of the second guard ring comprises a metal.

In an embodiment of the invention, the MEMS structure further includes a metal plug to connect the fixing portion to the substrate.

In an embodiment of the invention, the MEMS structure described above comprises a cantilever beam, a bridge or a diaphragm.

The invention further provides a method of fabricating a microelectromechanical system. First, a substrate is provided that includes separately configured circuit regions and MEMS regions. Then, a first metal interconnect structure is formed on the substrate in the circuit region, and a first dielectric layer structure is simultaneously formed on the substrate in the MEMS region. Then, forming a second metal interconnect structure on the first metal interconnect structure, And forming a second dielectric layer structure, at least two metal layers and a guard ring on the first dielectric layer structure. The metal layer and the guard ring are formed in the second dielectric layer structure, and the guard ring connects the adjacent two metal layers to define a closed space between the adjacent two metal layers. Accordingly, the first dielectric layer structure and the second dielectric layer structure outside the enclosed space are removed to form MEMS components in the MEMS region.

In one embodiment of the invention, the guard ring described above substantially corresponds to the contour of each metal layer.

In an embodiment of the invention, the material of the guard ring comprises a metal.

In an embodiment of the invention, before forming the first metal interconnect structure, the semiconductor component is further formed in the circuit region, and the semiconductor component is connected to the first metal interconnect structure.

In an embodiment of the invention, the semiconductor component described above comprises a complementary metal oxide semiconductor device.

In an embodiment of the invention, the MEMS component includes a movable portion and a fixed portion.

In an embodiment of the invention, the method further includes forming a metal plug in the first dielectric layer structure, wherein the metal plug connects the fixing portion and the substrate.

In an embodiment of the invention, the structure of the MEMS component described above comprises a cantilever beam, a bridge or a diaphragm.

The MEMS structure of the present invention connects adjacent two metal layers by a guard ring and a dielectric layer, thereby reducing residual stress in the metal layer to avoid problems such as warpage. Furthermore, due to the junction formed by the metal layer and the guard ring The structure is a large-area conductor layer, which can increase the sensing capacitance and mass weight, thereby improving the sensitivity and performance of the MEMS.

In addition, the manufacturing method of the microelectromechanical system of the present invention can be integrated into the process of the complementary metal oxide semiconductor to reduce the process steps, thereby helping to improve the yield and reducing the roughness, stress and particles caused by the components. Bad effects.

The above described features and advantages of the present invention will be more apparent from the following description.

1A to 1D are schematic cross-sectional views showing a manufacturing process of a microelectromechanical system according to an embodiment of the present invention. Since the process of the MEMS of the present invention can be integrated with the back-end process of the complementary gold-oxide semiconductor to achieve the efficiency of the process step, in the following embodiments, the metal oxide semiconductor, the interconnect and the MEMS are simultaneously The process steps of the system are described to illustrate the invention.

Referring to FIG. 1A, a substrate 100 is provided, which is, for example, a semiconductor wafer such as an N-type germanium wafer, a P-type germanium wafer, or the like. The substrate 100 includes a circuit region 102 and a MEMS region 104, and the circuit region 102 is configured separately from the MEMS region 104. Then, a transistor 110 is formed on the substrate 100 of the circuit region 102. The transistor 110 is, for example, a complementary metal oxide semiconductor transistor comprising a gate structure 112 on the substrate 100 and a doped region 114 in the substrate 100 on both sides of the gate structure 112. The gate structure 112 includes a gate 112a and a gate dielectric layer 112b, wherein the gate dielectric layer 112b is disposed on the gate Between 112a and substrate 100.

Referring to FIG. 1B, an interconnect process is performed to form a metal interconnect structure 116 on the substrate 100 in the circuit region 102. A dielectric layer structure 118 is formed on the substrate 100 of the MEMS region 104 while forming the metal interconnect structure 116.

Metal interconnect structure 116 includes dielectric layers 116a, 116b, 116c, plugs 116d, 116e, 116f and metal layers 116g, 116h. The material of the dielectric layers 116a, 116b, 116c is, for example, an oxide or other suitable dielectric material. The material of the plugs 116d, 116e, 116f is, for example, tungsten, copper or other suitable metal or alloy material. The material of the metal layers 116g, 116h is, for example, aluminum, copper or other suitable metal or alloy material. The interconnect process is well known to those of ordinary skill in the art and will not be described herein.

Dielectric layer structure 118 is comprised of, for example, three dielectric layers 118a, 118b, 118c, but is not intended to limit the invention. The material of the dielectric layer structure 118 is, for example, an oxide or other suitable dielectric material. Moreover, in an embodiment, since the subsequently preformed MEMS element includes a fixed portion and a movable portion, a plug may be selectively formed in the dielectric layer structure 118 at a position where the fixed portion 106 is pre-formed. 120a, 120b, 120c and metal layers 122a, 122b are used as fixed ends to which the fixing portion 106 is connected to the substrate 100. The material of the plugs 120a, 120b, 120c is, for example, tungsten, copper or other suitable metal or alloy material. The material of the metal layers 122a, 122b is, for example, aluminum, copper or other suitable metal or alloy material.

It is explained herein that since the process of the present invention in the circuit region 102 can be integrated with the process in the MEMS region 104, the MEMS is All of the process of zone 104 can be accomplished using interconnect programming techniques performed in circuit region 102. In particular, the dielectric layer structure 118 is formed, for example, with the dielectric layers 116a, 116b, 116c in the metal interconnect structure 116; the plugs 120a, 120b, 120c are, for example, interposed with the metal interconnect structure 116. The plugs 116d, 116e, 116f are formed together; the metal layers 122a, 122b are formed, for example, together with the metal layers 116g, 116h in the metal interconnect structure 116.

Referring to FIG. 1C, a metal interconnect structure 124 is formed on the metal interconnect structure 116. A dielectric layer structure 126, metal layers 128a, 128b, 128c, 128d, 132a, 132b, 132c, 132d are formed on the dielectric layer structure 118 of the MEMS region 104 while forming the metal interconnect structure 124. Rings 130a, 130b, 130c, 134a, 134b, 134c.

Similar to the metal interconnect structure 116, the metal interconnect structure 124 includes dielectric layers 124a, 124b, 124c, plugs 124d, 124e, 124f and metal layers 124g, 124h, 124i, 124j. The material of the dielectric layers 124a, 124b, 124c is, for example, an oxide or other suitable dielectric material. The material of the plugs 124d, 124e, 124f is, for example, tungsten, copper or other suitable metal or alloy material. The material of the metal layers 124g, 124h, 124i, 124j is, for example, aluminum, copper or other suitable metal or alloy material. The method of fabricating the metal interconnect structure 124 is well known to those of ordinary skill in the art and will not be described herein.

Dielectric layer structure 126 is comprised of, for example, three dielectric layers 126a, 126b, 126c, but is not intended to limit the invention. The material of the dielectric layer structure 126 is, for example, an oxide or other suitable dielectric material.

The metal layers 128a, 128b, 128c and the metal layers 132a, 132b, 132c are formed separately in the dielectric layer structure 126, for example, in a stacked manner. The metal layer 128d and the metal layer 132d are formed on the dielectric layer structure 126, for example, at positions corresponding to the metal 128c and the metal layer 132c, respectively. The guard rings 130a, 130b, 130c, 134a, 134b, 134c respectively connect adjacent two metal layers to define a closed space between adjacent two metal layers. The dielectric layers 126a, 126b, 126c located in the enclosed space are, for example, respectively connected to adjacent two metal layers. Further, the guard rings 130a, 130b, 130c, 134a, 134b, 134c, for example, substantially correspond to the contours of the metal layers of the respective layers, and connect the adjacent two metal layers. The material of the metal layers 128a, 128b, 128c, 128d, 132a, 132b, 132c, 132d is, for example, aluminum, copper or other suitable metal or alloy material. The material of the guard rings 130a, 130b, 130c, 134a, 134b, 134c is, for example, tungsten, copper or other suitable metal or alloy material.

As shown in FIG. 1C, in one embodiment, the guard rings 130a, 130b, 130c formed between the metal layers 128a, 128b, 128c, 128d will have a ring shape similar to the contour of the metal layers 128a, 128b, 128c, 128d. The outer shape is connected to the inner side of the outline of the metal layers 128a, 128b, 128c, 128d. The guard rings 130a, 130b, 130c surrounding the inner sides of the metal layers 128a, 128b, 128c, 128d, for example, enclose the dielectric layers 126a, 126b, respectively, between adjacent two metal layers 128a, 128b, 128c, 128d. The enclosed spaces 136a, 136b, 136c of 126c.

In one embodiment, the guard rings 134a, 134b, 134c formed between the metal layers 132a, 132b, 132c, 132d will have an annular shape similar to the contours of the metal layers 132a, 132b, 132c, 132d, and be connected to the metal. The inside of the outline of the layers 132a, 132b, 132c, 132d. The guard rings 134a, 134b, 134c surrounding the outline of the metal layers 132a, 132b, 132c, 132d, for example, enclose the dielectric layer 126a, 126b between adjacent two metal layers 132a, 132b, 132c, 132d, respectively. 126c encloses the spaces 138a, 138b, 138c.

The metal layers 128a, 128b, 128c, 128d and the guard rings 130a, 130b, 130c are, for example, the structure of the fixing portion 106 as a microelectromechanical system element; the metal layers 132a, 132b, 132c, 132d and the guard rings 134a, 134b, 134c are, for example, The structure of the movable portion 108 of the MEMS element. In detail, the metal layer 128a is formed on the dielectric layer structure 118 above the plug 120c to connect the plug 120c, and the metal layers 128b, 128c, 128d and the guard rings 130a, 130b, 130c are formed on the metal layer 128a. The fixing portion 106 can thus be connected to the substrate 100. The metal layer 132a is formed on the dielectric layer structure 118 without being connected to any plug or metal layer connected to the substrate 100, and the metal layers 132b, 132c, 132d and the guard rings 134a, 134b, 134c are formed on the metal. On the layer 132a, the movable portion 108 is thus not connected to the substrate 100 via a plug or a metal layer.

In particular, since the process of the present invention in the circuit region 102 can be integrated with the process in the MEMS region 104, all processes in the MEMS region 104 can utilize the interconnect process in the circuit region 102. Completed by technology. In particular, the dielectric layer structure 126 is formed, for example, with the dielectric layers 124a, 124b, 124c in the metal interconnect structure 124; the guard rings 130a, 130b, 130c, 134a, 134b, 134c are, for example, interconnected with metal The plug plugs 124d, 124e, 124f in the line structure 124 are shaped together The metal layers 128a, 128b, 128c, 128d, 132a, 132b, 132c, 132d are formed, for example, together with the metal layers 124g, 124h, 124i, 124j in the metal interconnect structure 124.

Referring to FIG. 1D, the dielectric layer structure 118 and the portion of the dielectric layer structure 126 are removed to form MEMS components in the MEMS region 108, that is, to fabricate the MEMS structure of the present invention. After the dielectric layer structure 118 and the portion of the dielectric layer structure 126 are removed, the fixing portion 106 of the MEMS element is fixedly connected to the substrate 100 via plugs 120a, 120b, 120c and metal layers 122a, 122b, for example. The movable portion 108 of the electromechanical system element is, for example, suspended on the base 100. The method of removing the dielectric layer structure 118 and the portion of the dielectric layer structure 126 is, for example, an isotropic etch. In one embodiment, the method of removing the dielectric layer structure 118 and the portion of the dielectric layer structure 126 is a wet etching method, and the etchant used is, for example, hydrofluoric acid, hydrogen fluoride vapor or xenon difluoride (XeF _{2 ).} )steam.

In particular, the guard rings 130a, 130b, 130c, 134a, 134b, 134c formed in the steps described in FIG. 1C will connect adjacent two metal layers 128a, 128b, 128c, 128d, 132a, 132b, 132c, 132d, thus the guard rings 130a, 130b, 130c, 134a, 134b, 134c can protect the dielectric material located within the enclosed spaces 136a, 136b, 136c, 138a, 138b, 138c. That is, when the etching process for removing a portion of the dielectric layer structure 126 is performed, only the dielectric layers 126a, 126b, 126c outside the guard rings 130a, 130b, 130c, 134a, 134b, 134c are removed while remaining Dielectric layers 126a', 126b', 126c' in enclosed spaces 136a, 136b, 136c, 138a, 138b, 138c.

In addition, while forming the metal interconnect structures 116, 124, an isolation structure (not shown) may be selectively formed between the circuit region 102 and the MEMS region 104 for etching to remove the dielectric material. The dielectric material located in circuit region 102 is protected during the process. The method of forming the isolation structure is formed, for example, with each of the metal interconnect structures 116, 124.

In an embodiment, the movable portion 108 suspended from the base 100 may be further connected to an elastic member (not shown), for example, to a spring. The sensing movable portion 108 is subjected to external disturbance to generate a change such as vibration, thereby changing the value of the induced capacitance between the movable portion 108 and the fixed portion 106 to generate an electronic signal. When the elastic member is disposed between the side of the movable portion 108 and a member other than the movable portion 108, the microelectromechanical system element can be used to sense horizontal vibration of the movable portion 108 along the X-axis or the Y-axis. When the elastic member is disposed between the lowermost metal layer 132a and the substrate 100, the microelectromechanical system element can be used to sense the vertical vibration of the movable portion 108 along the Z axis.

Of course, the structure of the MEMS formed in the above embodiments may be a structure such as a cantilever beam, a bridge or a diaphragm, and the MEMS component may be an accelerometer, a gyroscope, an oscillator, a microphone, a switch, an inductor, or A very small microelectromechanical system component such as an actuator is not particularly limited herein. In addition, the number of metal layers constituting the metal interconnect structure and the MEMS component structure is not limited to the number shown in FIG. 1D. In other embodiments, the general knowledge in the technical field can adjust the metal layer according to actual needs. quantity.

Hereinafter, the structure of the MEMS of the present invention will be described by taking the structure in the region of the microelectromechanical element 104 in Fig. 1D as an example. worth taking note of The materials, effects, and formation methods of the components of the MEMS structure of the following embodiments have been described in detail in the above embodiments, and thus will not be described again.

Referring to FIG. 1D, the MEMS structure includes a fixing portion 106 and a movable portion 108. The fixing portion 106 is disposed on the substrate 100, and the fixing portion 106 is connected to the substrate 100, for example. The movable portion 108 is disposed on one side of the fixed portion 106, and the movable portion 108 is, for example, suspended on the base 100. In an embodiment, the MEMS structure may be other structures such as a cantilever beam, a bridge, or a diaphragm.

The fixing portion 106 includes plugs 120a, 120b, 120c, metal layers 122a, 122b, 128a, 128b, 128c, 128d, guard rings 130a, 130b, 130c and dielectric layers 126a', 126b', 126c'. The metal layers 128a, 128b, 128c, and 128d are disposed on the substrate 100, for example, in a stacked manner. The guard rings 130a, 130b, and 130c respectively connect the adjacent two metal layers 128a, 128b, 128c, and 128d to define a closed space 136a, 136b between the adjacent two metal layers 128a, 128b, 128c, and 128d. 136c. The guard rings 130a, 130b, 130c, for example, substantially correspond to the contours of the respective metal layers 128a, 128b, 128c, 128d. In one embodiment, the guard rings 130a, 130b, 130c have an annular profile similar to the contours of the metal layers 128a, 128b, 128c, 128d and are attached to the inside of the contour of the metal layers 128a, 128b, 128c, 128d. Dielectric layers 126a', 126b', 126c' are disposed within enclosed spaces 136a, 136b, 136c and connect adjacent two metal layers 128a, 128b, 128c, 128d. Further, the plugs 120a, 120b, and 120c and the metal layers 122a and 122b are disposed between the metal layer 128a and the substrate 100, for example, as a fixing portion. A fixed end connected to the base 100 to support the fixing portion 106. In one embodiment, the plug 120a connects the substrate 100 with the metal layer 122a, the plug 120b connects the metal layer 122a with the metal layer 122b, and the plug 120c connects the metal layer 122b with the metal layer 128a.

The movable portion 108 includes metal layers 132a, 132b, 132c, 132d, guard rings 134a, 134b, 134c and dielectric layers 126a', 126b', 126c'. The metal layers 132a, 132b, 132c, and 132d are disposed on the substrate 100, for example, in a stacked manner. The guard rings 134a, 134b, 134c respectively connect the adjacent two metal layers 132a, 132b, 132c, 132d to define a closed space 138a, 138b between the adjacent two metal layers 132a, 132b, 132c, 132d. 138c. The guard rings 134a, 134b, 134c, for example, substantially correspond to the contours of the respective metal layers 132a, 132b, 132c, 132d. In one embodiment, the guard rings 134a, 134b, 134c have an annular profile similar to the contours of the metal layers 132a, 132b, 132c, 132d and are attached to the inside of the contour of the metal layers 132a, 132b, 132c, 132d. Dielectric layers 126a', 126b', 126c' are disposed within enclosed spaces 136a, 136b, 136c and connect adjacent two metal layers 132a, 132b, 132c, 132d.

Since the guard ring and the dielectric layer are connected to the adjacent two metal layers, the residual stress in the metal layer can be compensated by the dielectric layer to avoid problems such as warpage of the metal layer. Furthermore, since the structure formed by the metal layer and the guard ring is a large-area conductor, the inductance between the movable portion 108 and the fixed portion 106 can be increased and the weight of the mass can be increased, thereby improving the sensitivity of the MEMS. In addition, the structure of the fixing portion 106 and the structure of the movable portion 108 can be formed together by performing an interconnect process in the circuit region. Thus, it helps to simplify the process and increase the yield, and reduces the roughness, stress and adverse effects of the particles on the components.

In summary, the MEMS structure and the manufacturing method thereof have at least the following advantages: 1. The MEMS structure of the above embodiment can increase the sensing area of the capacitor and the weight of the mass, and reduce the stress of the material. In turn, component sensitivity and component performance can be effectively improved.

2. Since the manufacturing method of the MEMS system of the above embodiment can be easily integrated with the current semiconductor process, that is, the integrated semiconductor process technology can be used to simultaneously form the integrated circuit and the MEMS component, thereby simplifying the process and increasing the process. Yield and other effects.

Although the present invention has been disclosed in the above preferred embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

100‧‧‧Base

102‧‧‧Circuit area

104‧‧‧Microelectromechanical system area

106‧‧‧Fixed Department

108‧‧‧movable department

110‧‧‧Optoelectronics

112‧‧‧ gate structure

112a‧‧‧ gate

112b‧‧‧gate dielectric layer

114‧‧‧Doped area

116, 124‧‧‧Metal interconnection structure

116a, 116b, 116c, 118a, 118b, 118c, 124a, 124b, 124c, 126a, 126b, 126c, 126a', 126b', 126c'‧‧‧ dielectric layer

116d, 116e, 116f, 120a, 120b, 120c, 124d, 124e, 124f‧‧‧ plug

116g, 116h, 122a, 122b, 124g, 124h, 124i, 124j, 128a, 128b, 128c, 128d, 132a, 132b, 132c, 132d‧‧‧ metal layers

118, 126‧‧ dielectric layer structure

130a, 130b, 130c, 134a, 134b, 134c‧‧‧ protection ring

136a, 136b, 136c, 138a, 138b, 138c‧‧‧ enclosed space

1A to 1D are schematic cross-sectional views showing a manufacturing process of a microelectromechanical system according to an embodiment of the present invention.

100‧‧‧Base

102‧‧‧Circuit area

104‧‧‧Microelectromechanical system area

106‧‧‧Fixed Department

108‧‧‧movable department

110‧‧‧Optoelectronics

112‧‧‧ gate structure

112a‧‧‧ gate

112b‧‧‧gate dielectric layer

114‧‧‧Doped area

116, 124‧‧‧Metal interconnection structure

116a, 116b, 116c, 124a, 124b, 124c, 126a', 126b', 126c'‧‧‧ dielectric layer

116d, 116e, 116f, 120a, 120b, 120c, 124d, 124e, 124f‧‧‧ plug

116g, 116h, 122a, 122b, 124g, 124h, 124i, 124j, 128a, 128b, 128c, 128d, 132a, 132b, 132c, 132d‧‧‧ metal layers

130a, 130b, 130c, 134a, 134b, 134c‧‧‧ protection ring

136a, 136b, 136c, 138a, 138b, 138c‧‧‧ enclosed space

Claims (8)

A MEMS structure includes: a fixing portion disposed on a substrate and connected to the substrate; and a movable portion disposed on the substrate, the movable portion comprising: at least two first metal layers; The first protection ring is connected to the two adjacent first metal layers to define a first closed space between the two adjacent first metal layers; and a first dielectric layer is disposed in the first closed space. And connecting two adjacent first metal layers. The MEMS structure of claim 1, wherein the first guard ring substantially corresponds to a contour of each of the first metal layers. The MEMS structure of claim 1, wherein the material of the first guard ring comprises a metal. The MEMS structure of claim 1, wherein the fixing portion comprises: at least two second metal layers; and a second protection ring connecting adjacent two second metal layers to adjacent two A second enclosed space is defined between the metal layers; and a second dielectric layer is disposed in the second enclosed space and connects the adjacent two second metal layers. The MEMS structure of claim 4, wherein the second guard ring substantially corresponds to each of the second metal layer wheels Profile. The MEMS structure of claim 4, wherein the material of the second guard ring comprises a metal. The MEMS structure of claim 1, further comprising a metal plug for connecting the fixing portion to the substrate. The MEMS structure of claim 1, wherein the MEMS structure comprises a cantilever beam, a bridge or a diaphragm.