Abstract:
A microelectromechanical system device including anchors and mass is provided. Electrical interconnections are formed on the mass by using a insulation layer of mass, an electrical insulation trench and conductive through hole. The electrical interconnections replace the cross-line structure without adding additional processing steps, thereby reducing the use of the conductive layer and the electrical insulation layer. A method for fabricating the microelectromechanical system device is also provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan application serial no. 100149587, filed on Dec. 29, 2011. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
     TECHNICAL FIELD 
     The disclosure relates to a microelectromechanical system (MEMS) device, in particular, to a microelectromechanical system device with electrical interconnections. 
     BACKGROUND 
     GPS technology has been widely applied in automobile navigation devices and personal navigation devices now. However, the error of GPS positioning signal may occur because the signals from satellite could be easily effected by shielding effects of terrain, buildings and weather conditions. 
     The industry solution has been provided by combining GPS technology with an inertia sensors (such as an accelerometer and a gyroscope). When the signal of the GPS device becomes weak or even failed due to the shielding effect (such as entering an underground parking lot), several approaches are provided for positioning, for example, an accelerometer and/or gyro. By continuously detecting acceleration by the accelerometer and/or detecting angular velocity by the gyro, the position of a car or person can be obtained, and the navigation function of the navigation device can work as normal in such a worse case. However, when the positions of the car or person are continuously obtained by the information from the accelerometer and/or the gyro, more and more calculation errors may be accumulated accordingly over time. That will cause the accuracy of the positions obtained by the navigation device being difficult to maintain. 
     A MEMS (Microelectromechanical systems) inertia sensing elements such as a magnetometer may be used to adjust the information from the gyro to avoid the accumulation of calculation errors over time. The location information measured by the magnetometer can be used to adjust the rotation angle calculated by the gyro, by which the accumulation of calculation errors can be reduced and the accuracy of the navigation device can be maintained and/or enhanced. In other word, the navigation device combining GPS device, accelerometer, gyro and magnetometer can prevent automobile navigation devices and personal navigation devices from the impact of the shielding effect. 
     With the innovation and applications of the MEMS (Microelectromechanical systems) inertia sensing elements on smart phones and navigation devices, the application scope of the navigation device can expand from an outdoor flat road to an indoor parking lot or to a large shopping mall. The MEMS magnetometer made with the MEMS technology has become a key element of the next-generation of automobile navigation devices and personal navigation devices. 
     A one-axis magnetometer is introduced herein in  FIG. 1 . In the uniaxial magnetometer  10 , an electrical current I flows through a coil  14  on a twist plate  12 . A magnetic field B will induce a Lorentz force F, and the Lorentz force F will drive the twist plate  12  to rotate. A sensing electrode (not shown) below the twist plate  12  can detect changes of the capacitance between the twist plate  12  and the sensing electrode. By the manner, the magnetic force of the position where the magnetometer  10  is located is obtained. If three uniaxial magnetometers  10  are disposed in three vertical axial directions, a three-axis magnetometer is formed. The location of the three-axis magnetometer can be deduced by calculating components of the geomagnetism on the three axial directions of the three-axis magnetometer, so as to realize a function similar to that of a compass. 
     At present a MEMS magnetometer usually adopts a single conductive coil design. Such MEMS magnetometers require large element size or require a large electrical current to sense the magnetic force, so it cannot satisfy the mobile phone product requirements of small size and low power consumption. 
     Another MEMS magnetometer adopts a design of a plurality of conductive coils. Referring to  FIG. 2 , the magnetometer  20  includes a plurality of coils  22  with a spiral path throughout a twist plate, but an extra cross-line structure  24  formed by a conductive layer  26  and an electrical insulation layer  28  are required to achieve electrical connections. In this way, the process requires more steps, and process cost and process risks are increased. 
     A MEMS micro-mirror is another application of the MEMS technology. Referring to  FIG. 3 , in the MEMS micro-mirror  30 , the Lorentz force is produced after that the electrical current flowing through a coil  32  on a twist plate interacts with a permanent magnet  38 . The Lorentz is used to drive the twist plate to rotate and to drive a mirror  34  on the twist plate to rotate accordingly. However, the coil  32  still requires the cross-line structure  36  to achieve electrical connection. Similarly, the process requires more steps, and process cost and process risks are increased. 
     SUMMARY 
     A microelectromechanical system device with electrical interconnections passing through an insulation layer of the mass and a method for fabricating the same are introduced herein. 
     In one of some exemplary embodiments, a microelectromechanical system device with electrical interconnections is provided herein. The microelectromechanical system device comprises a mass and a substrate. The mass comprises an insulation layer of the mass, a trench of the mass and a conductive through hole of the mass. The insulation layer of the mass divides the mass into a base conductive layer and a target conductive layer. The trench of the mass is disposed in the target conductive layer, passes through the target conductive layer to the insulation layer of the mass, and divides the target conductive layer into a first conductive portion and a second conductive portion which are insulated electrically from each other. The conductive through hole of the mass passes through the insulation layer of the mass and connects the base conductive layer and the first conductive portion. The substrate comprises at least one electrode disposed on an upper surface of the substrate, wherein in a working status, the electrical current flows through the base conductive layer, the conductive through hole of the mass and the first conductive portion, and an electrical potential difference exists between the second conductive portion and the electrode. 
     In one embodiment, the microelectromechanical system device with electrical interconnections is provided herein. The microelectromechanical system device comprises a first anchor. The first anchor includes a first insulation layer and a first trench. The first insulation layer divides the first anchor into an upper conductive layer of the first anchor and a lower conductive layer of the first anchor. The first trench is disposed in the lower conductive layer of the first anchor passing through the lower conductive layer of the first anchor to the first insulation layer. The first trench divides the lower conductive layer of the first anchor into an inner conductive portion of the first anchor and an outer conductive portion of the first anchor which are insulated electrically from each other. The inner conductive portion of the first anchor is electrically coupled to the second conductive portion. 
     In one embodiment, the microelectromechanical system device with electrical interconnections further comprises at least one first conductive through hole disposed in the first anchor. The at least one first conductive through hole passes through the first insulation layer and connects the upper conductive layer of the first anchor and the outer conductive portion of the first anchor. 
     In one embodiment, the microelectromechanical system device with electrical interconnections can further comprise at least one spring. The spring includes a third insulation layer. The third insulation layer divides the at least one spring into an upper conductive layer and a lower conductive layer. The lower conductive layer of the spring connects the inner conductive portion of the first anchor and the second conductive portion of the mass. The upper conductive layer of the spring connects the upper conductive layer of the first anchor and the base conductive layer. 
     In one embodiment, the microelectromechanical system device with electrical interconnections further comprises a device wherein a portion of the insulation layer of the mass is covered by the base conductive layer, and the base conductive layer is a spiral-shaped with at least one turn. The trench of the mass can be an open-loop-shaped electrical insulation trench. The device further comprises an electrical insulation material filled in the first trench and the trench of the mass to form another kind of electrical insulation trench. 
     In one embodiment, the microelectromechanical system device with electrical interconnections further comprises two permanent magnets and a second anchor. The first anchor and the second anchor are located on two opposite sides of the mass. The two permanent magnets are located near the mass and are aligned with a line that is perpendicular to the line connecting the first anchor and the second anchor. 
     In another one of some exemplary embodiments, a microelectromechanical device with electrical interconnections is provided herein. The microelectromechanical device comprises two anchors, a mass, and two torsion springs. The first anchor is one of the two anchors. The first anchor includes a first insulation layer and a first trench. The first insulation layer divides the first anchor into an upper conductive layer of the first anchor and a lower conductive layer of the first anchor. The first trench is disposed in the lower conductive layer of the first anchor and, passes through the lower conductive layer of the first anchor to the first insulation layer. The first trench divides the lower conductive layer of the first anchor into an inner conductive portion and an outer conductive portion which are insulated electrically from each other. A first conductive through hole is disposed in the first anchor, passing through the first insulation layer and connecting the upper conductive layer of the first anchor and the outer conductive portion. 
     In one embodiment, the second anchor includes a second insulation layer and a second trench. The second insulation layer divides the second anchor into an upper conductive layer of the second anchor and a lower conductive layer of the second anchor. The second trench of the second anchor is disposed in the lower conductive layer of the second anchor passing through the lower conductive layer of the second anchor to the second insulation layer. The second trench divides the lower conductive layer into an inner conductive portion and an outer conductive portion which are insulated electrically from each other. 
     In one embodiment, the mass includes an insulation layer of the mass, a trench of the mass and a conductive through hole of the mass. The insulation layer of the mass divides the mass into a base conductive layer and a target conductive layer. The trench of the mass passes through the target conductive layer to the insulation layer of the mass, and divides the target conductive layer into a first conductive portion and a second conductive portion which are insulated electrically from each other. The conductive through hole of the mass passes through the insulation layer of the mass and connecting the base conductive layer and the first conductive portion. 
     In one embodiment, each torsion spring includes a third insulation layer, which divides the torsion spring into an upper conductive layer of the torsion spring and a lower conductive layer of the torsion spring. The base conductive layer can be a spiral-shaped conductor having at least one turn. The upper conductive layer of one of the torsion springs connects the upper conductive layer of the first anchor and the base conductive layer. The lower conductive layer of the one of the torsion springs connects the inner conductive portion of the first anchor and the second conductive portion of the mass. The lower conductive layer of the other torsion spring connects the inner conductive portion of the second anchor and the first conductive portion of the mass. 
     In one of some exemplary embodiments, a method for fabricating a microelectromechanical system device with electrical interconnections is provided herein. The method includes the following steps. Provide a silicon on insulator wafer, where the silicon on insulator wafer includes a device layer, an insulation layer and a handle layer stacked sequentially. Etch the device layer to form a recess portion and a plurality of protruding portions. Bond the plurality of protruding portions with a substrate. Remove the handle layer. Form a plurality of upper conductive layers on the insulation layer. Pattern the device layer such that the plurality of protruding portions is formed to be a plurality of lower conductive layers of a plurality of anchors, and the recess portion is formed to be a lower conductive layer of a mass and a lower conductive layer of at least one torsion spring. Pattern the insulation layer to form insulation layers of the anchors, an insulation layer of the mass and an insulation layer of the torsion spring. 
     In another one of some exemplary embodiments, a method for fabricating a microelectromechanical system device with electrical interconnections is provided. The method includes the following steps. Provide a silicon on insulator wafer, where the silicon on insulator wafer includes a device layer, an insulation layer and a handle layer stacked sequentially. Etch the device layer to form a recess portion and a plurality of protruding portions, where the recess portion is to form a lower conductive layer of a mass and a lower conductive layer of at least one torsion spring, and the plurality of protruding portions are to form a plurality of lower conductive layers of a plurality of anchors. Etch a first trench at the at least one of the plurality of protruding portions and etch a trench of the mass at the recess portion, where the first trench and the trench of the mass extend to the insulation layer, the first trench divides the lower conductive layer of the anchor into an inner conductive portion and an outer conductive portion which are insulated electrically from each other, and the trench of the mass divides the lower conductive layer of the mass into a first conductive portion and a second conductive portion which are insulated electrically from each other. Bond the protruding portions with a substrate. Remove the handle layer. Form at least one first through hole through the insulation layer on the one of the plurality of protruding portions and at lest one second through hole through the insulation layer on the recess portion, wherein a portion of the one of the plurality of protruding portions is exposed in the first through hole and a part of the recess portion is exposed in the second through hole. Form a plurality of upper conductive layers on the insulation layer and filling the upper conductive layers in the first through hole and the second through hole to form a first conductive through hole and a conductive through hole of the mass. The first conductive through hole and the conductive through hole of the mass pass through the insulation layers, the first conductive through hole connects the upper conductive layer of the first anchor and the outer conductive portion of the first anchor, the conductive through hole of the mass connects the upper conductive layer of the mass and the first conductive portion. The first conductive portion electrically couples the inner conductive portion of the second anchor and the second conductive portion electrically couples the inner conductive portion of the first anchor. Pattern the device layer such that the plurality of protruding portions is formed to be the lower conductive layer of the anchors, and the recess portion is formed to be the lower conductive layer of the mass and the lower conductive layer of at least one torsion spring. Pattern the insulation layer to form insulation layers of the anchors, an insulation layer of the mass and an insulation layer of the torsion spring. 
     Based on the above, electrical interconnections are formed by employing the upper conductive layer, lower conductive layer, an electrical insulation layer, trench and conductive through hole. The electrical interconnections may substitute the cross-line structure without additional process steps, thereby reducing the use of the conductive layer and the insulation layer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  and  FIG. 2  are schematic diagrams illustrating two conventional magnetometers. 
         FIG. 3  is a schematic diagram illustrating a conventional MEMS micro-mirror. 
         FIG. 4A  is a top view of a microelectromechanical system device with an insulation structure of ROC Patent Application No. 099145427. 
         FIG. 4B  is a cross-sectional view along a section line II-II in  FIG. 4A . 
         FIG. 5A  is a top view of a microelectromechanical system device with electrical interconnections according to an embodiment of the disclosure. 
         FIG. 5B  is a side view of the microelectromechanical system device in  FIG. 5A  along a section line III-III. 
         FIG. 6  is a top view of a microelectromechanical system device with electrical interconnections according to another embodiment of the disclosure. 
         FIG. 7A  is a top view of a microelectromechanical system device with electrical interconnections according to another embodiment of the disclosure. 
         FIG. 7B  is a side view of the microelectromechanical system device in  FIG. 7A  along a section line IV-IV. 
         FIG. 8A  is a top view of a microelectromechanical system device with electrical interconnections according to another exemplary embodiment of the disclosure. 
         FIG. 8B  is a side view of the microelectromechanical system device in  FIG. 8A  along a section line V-V. 
         FIG. 9A  is a top view of a microelectromechanical system device with electrical interconnections according to another embodiment of the disclosure. 
         FIG. 9B  is a side view of the microelectromechanical system device in  FIG. 9A  along a section line VI-VI. 
         FIG. 10A  is a top view of a microelectromechanical system device with electrical interconnections according to another embodiment of the disclosure. 
         FIG. 10B  is a side view of the microelectromechanical system device in  FIG. 10A  along a section line VII-VII. 
         FIG. 11A  is a top view of a microelectromechanical system device with electrical interconnections according to another embodiment of the disclosure. 
         FIG. 11B  is a side view of the microelectromechanical system device in  FIG. 11A  along a section line VIII-VIII. 
         FIG. 12A  to  FIG. 12H  are flowcharts of fabricating a microelectromechanical system device with electrical interconnections according to an embodiment of the disclosure. 
         FIG. 13A  and  FIG. 13B  are simplified cross-sectional side views of the two microelectromechanical system devices of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     A microelectromechanical system device with an electrical insulation structure as illustrated in U.S. Pat. No. 13/220,068 filed on Aug. 29, 2011 is depicted in  FIGS. 4A and 4B . All disclosures thereof are incorporated by reference herewith.  FIG. 4A  depicts a top view of a microelectromechanical system device with an electrical insulation structure.  FIG. 4B  is a cross-sectional view along a section line II-II in  FIG. 4A . As shown in  FIG. 4A  and  FIG. 4B , an electrical signal from a mass  41  is transmitted to an anchor  45  via a path labelled as arrow “a” from an upper conductive portion  421  of a spring, an upper conductive portion  431  of a frame  43 , an upper conductive portion  441  of a spring, a conductive through hole  455  connected to an outer conductive region  4521  of the anchor  45 . The signal from the mass  41  is then transmitted to a conductive trace (not shown) on a substrate  46  via the outer conductive region  4521  of the anchor  45 . An electrical signal from the frame  43  is transmitted to an inner conductive region  4522  of the anchor  45  via a lower conductive portion  442  of the spring and is then transmitted to another conductive trace (not shown) on the substrate  46 , as a path labelled an arrow “b.” However, in  FIG. 4A  and  FIG. 4B , it is impossible for the mass  41  to be an electrical interconnection allowing the electrical current to flow through it and to be an electrode plate having an electrical potential difference at the same time. 
     Some of exemplary embodiments of the disclosure provide a microelectromechanical system device with electrical interconnections, which includes a mass, a conductive through hole of mass and a substrate. The mass includes a insulation layer of mass and a trench of mass. The insulation layer of mass divides the mass into a base conductive layer and a target conductive layer. The trench of mass is disposed in the target conductive layer and passes through the target conductive layer to the insulation layer of mass, and divides the target conductive layer into a first conductive portion and a second conductive portion which are insulated electrically from each other. The conductive through hole of mass passes through the insulation layer of mass, and connects the base conductive layer and the first conductive portion. The substrate includes at least one electrode which is disposed on the upper surface of the substrate. In the working status, an electrical current flows through the base conductive layer, the conductive through hole of mass and the first conductive portion, and an electrical potential difference exists between the second conductive portion and the electrode. In this way, the microelectromechanical system device of this embodiment provides two independent electrical interconnections without a cross-line structure. 
     The target conductive layer may be a lower conductive layer located below the electrical insulation layer of mass. And the target conductive layer may also be an upper conductive layer located on the electrical insulation layer of mass. 
     One of some exemplary embodiments of the disclosure is illustrated in  FIGS. 5A and 5B , but not limited thereto.  FIG. 5A  is a top view of a microelectromechanical system device with electrical interconnections according to an embodiment of the disclosure.  FIG. 5B  is a side view of the microelectromechanical system device in  FIG. 5A  along a section line III-III. 
     Referring to  FIG. 5A  and  FIG. 5B , the microelectromechanical system device with electrical interconnections  100  is an MEMS magnetometer. The microelectromechanical system device  100  includes two anchors  110 , a mass  120 , two torsion springs  130  and a substrate  140 . The two anchors  110  are secured on the substrate  140 . The mass  120  is connected between the two anchors  110  via the two torsion springs  130 . In other words, the mass  120  is rotatablely suspended over the substrate  140  by the torsion springs  130  and the anchors  110 . 
     Each anchor  110  (referring to the first anchor  110 A and the second anchor  110 B shown in the drawings) includes a first insulation layer  112  and a first trench  114 , and the first anchor  110 A further includes a first conductive through hole  116 . In another embodiment, the second anchor  110 B may further include a first conductive through hole  116 . The first anchor  110 A is used as an example for explanation herein. The first insulation layer  112  divides the anchor  110  into an upper conductive layer  118 A and a lower conductive layer  118 B which are electrically insulated from each other by the first insulation layer  112 . The first trench  114  is disposed in the lower conductive layer  118 B of the anchor  110  and passes through the lower conductive layer  118 B of the anchor  110  to the first insulation layer  112  of the anchor  110 . The first trench  114  divides the lower conductive layer  118 B of the anchor into an inner conductive portion  118 B 1  and an outer conductive portion  118 B 2  which are electrically insulated from each other by the first trench  114 . The first conductive through hole  116  is disposed in the first anchor  110 A and passes through the first insulation layer  112  of the first anchor  110 A. The first conductive through hole  116  also connects the upper conductive layer  118 A of the first anchor  110 A and the outer conductive portion  118 B 2 . An electrical insulation material  114 A may be filled in the first trench  114  to form an electrical insulation structure by which the inner conductive portion  118 B 1  and an outer conductive portion  118 B 2  are electrically insulated from each other. 
     The mass  120  includes a insulation layer  122  of mass  120 , a trench  124  of mass  120  and a conductive through hole  126  of mass  120 . The insulation layer  122  of mass  120  divides the mass  120  into a base conductive layer  128 A and a target conductive layer  128 B. The trench  124  of mass  120  is disposed in the target conductive layer  128 B, and passes through the target conductive layer  128 B to the insulation layer  122  of mass  120 . The trench  124  of mass  120  also divides the target conductive layer  128 B into a first conductive portion  128 B 1  and a second conductive portion  128 B 2  which are insulated electrically from each other by the trench  124  of mass  120 . The base conductive layer  128 A is the upper conductive layer located on one surface of the insulation layer  122  of mass  120  away from the substrate  140 , while the target conductive layer  128 B is the lower conductive layer located between the insulation layer  122  of mass  120  and the substrate  140 , but the disclosure is not limited to this. 
     The trench  124  of mass  120  is located at the target conductive layer  128 B. The trench  124  of mass  120  is shaped as a letter U. Referring to the top view in  FIG. 5A , the mass  120  is rectangular, and the U-shaped trench  124  of mass  120  has an opening. The opening of the U-shaped trench  124  of mass  120  faces toward the torsion spring  130  that connects the anchor  110 B and the mass  120 , and two ends of the opening extend to the same side edge of the target conductive layer  128 B such that the first conductive portion  128 B 1  and a second conductive portion  128 B 2  are insulated electrically from each other by the U-shaped trench  124  of mass  120  and the lower conductive layer  136  of the torsion spring  130  and second conductive portion  128 B 2  are also insulated electrically from each other by the U-shaped trench  124  of mass  120 . In other words, the U-shaped trench  124  of mass  120  is one kind of electrical insulation trench. 
     The second segment  124 B of the U-shaped trench  124  of mass  120  is substantially perpendicular to the section line III-III. In other words, two ends of the U-shaped trench  124  of mass  120  point to the second anchor  110 B. An electrical insulation material  124 A may be filled in the U-shaped trench  124  of mass  120  to form an electrical insulation structure. In this way, the U-shaped trench  124  of mass  120  which is filled with the insulation material  124 A can be another kind of electrical insulation trench. 
     In another exemplary embodiment, the trench  124  of mass  120  may be shaped as any polygon with an opening or may be shaped as any loop with an opening (open-loop-shaped trench), and two ends of the opening extend to the same side edge of the target conductive layer  128 B such that the first conductive portion  128 B 1  and a second conductive portion  128 B 2  are insulated electrically from each other by the trench  124  of mass  120 . And the lower conductive layer  136  of the torsion spring  130  (the torsion spring, on right side of  FIG. 5A , which connects the mass  120  and the second anchor  110 B) and second conductive portion  128 B 2  are also insulated electrically from each other by the trench  124  of mass  120 . In other words, the trench  124  of mass  120  is one kind of open-loop-shaped electrical insulation trench. 
     The conductive through hole  126  of mass  120  passes through the insulation layer  122  of the mass  120 , and the conductive through hole  126  of mass  120  connects the base conductive layer  128 A and the first conductive portion  128 B 1 . A portion of the insulation layer  122  of the mass  120  is covered by the base conductive layer  128 A. The base conductive layer  128 A is a spiral-shaped conductor having at least a turn and a spiral path throughout the mass  120 . Hence, the Lorentz force will be produced when the electrical current flowing through the base conductive layer  128 A interacts with the magnetic force, thus the mass  120  rotates relative to the anchor  110 . 
     Referring to  FIG. 5A  and  FIG. 5B , the torsion spring  130  connects the anchor  110  and the mass  120 . The torsion spring  130  is a beam, so that the mass  120  can rotate relative to the anchor  110 . Each torsion spring  130  includes a third insulation layer  132 . The third insulation layer  132  divides the torsion spring  130  (the torsion spring  130 A) on the left side in  FIG. 5A  and  FIG. 5B  into an upper conductive layer  134  of the torsion spring  130 A and a lower conductive layer  136  of the torsion spring  130 A which are insulated electrically from each other by the third insulation layer  132 . The upper conductive layer  134  of the torsion spring  130  (the torsion spring  130 A) on the left side in  FIG. 5A  and  FIG. 5B  connects the base conductive layer  128 A and the upper conductive layer  118 A of the first anchor  110 A. 
     The lower conductive layer  136  of the torsion spring  130  (the torsion spring  130 B) on the right side in  FIG. 5A  and  FIG. 5B  connects the inner conductive portion  118 B 1  of the second anchor  110 B and the first conductive portion  128 B 1  of the mass  120 , so that the first conductive portion  128 B 1  of the mass  120  is electrically coupled to the inner conductive portion  118 B 1  of the second anchor  110 B. The lower conductive layer  136  of the torsion spring  130  (the torsion spring  130 A) on the left side in  FIG. 5A  and  FIG. 5B  connects the inner conductive portion  118 B 1  of the first anchor  110 A and the second conductive portion  128 B 2  of the mass  120 , so that the second conductive portion  128 B 2  of the mass  120  is electrically coupled to the inner conductive portion  118 B  1  of the first anchor  110 A. 
     The substrate  140  includes at least one electrode  142  and a plurality of conductive layers  144 . In this embodiment, two electrodes  142  are disposed on the substrate  140  respectively and are located below the mass  120 . The two electrodes  142  are mirror-symmetrical to each other with respect to the section line The substrate  140  includes a plurality of conductive layers  144  which are disposed on the substrate  140  and is located below the anchor  110 . The microelectromechanical system device  100  further includes a plurality of conductive bonding layers  146 . The outer conductive portion  118 B 2  and the inner conductive portion  1181  of the anchor  110  are electrically coupled to different conductive layers  144  on the substrate  140  respectively via the conductive bonding layer  146 . More particularly, the outer conductive portion  118 B 2  of the anchor  110 A is connected to the conductive layer  144 A on the substrate  140  via the conductive bonding layer  146 A. The inner conductive portion  118 B 1  of the anchor  110 A is connected to the conductive layer  144 B on the substrate  140  via the conductive bonding layer  146 B. The outer conductive portion  118 B 2  of the anchor  110 B is connected to the conductive layer  144 C on the substrate  140  via the conductive bonding layer  146 C. The inner conductive portion  118 B 1  of the anchor  110 B is connected to the conductive layer  144 D on the substrate  140  via the conductive bonding layer  146 D. Each of the conductive layers  144 A,  144 B,  144 C and  144 D is separated from each other. 
     Referring to  FIG. 5A  and  FIG. 5B , in a working status, a current path exists through the MEMS device  100 . In the current path, an electrical current flows through the conductive layer  144 A, the conductive bonding layer  146 A, the outer conductive portion  118 B 2  of the first anchor  110 A, the first conductive through hole  116 , the upper conductive layer  118 A of the first anchor  110 A, the upper conductive layer  134  of the torsion spring  130 A, the base conductive layer  128 A, the conductive through hole  126  of the mass  120 , the first conductive portion  128 B 1  and the lower conductive layer  136  of the torsion spring  130 B, the inner conductive portion  118 B 1  of the second anchor  110 B, the conductive bonding layer  146 D and the conductive layer  144 D sequentially. The Lorentz force produced by the electrical current flowing through the base conductive layer  128 A and the magnetic force drives the mass  120  to rotate relative to the anchor  110 . By a conductive bonding layer  146 A,  146 B, the outer conductive portion  118 B 1  of the first anchor  110 A and the inner conductive portion  118 B 2  of the first anchor  110 A are connected to different conductive layers  144 A,  144 B on the substrate  140  respectively to form two electrical interconnections which are insulated electrically from each other. 
     In the working status, the first electrical potential will exist in the second conductive portion  128 B 2  of the target conductive layer  128 B. The second electrical potential will exist in the electrode  142  of the substrate  140 . The electrical potential difference will exist between the second conductive portion  128 B 2  of the target conductive layer  128 B and electrode  142  of the substrate  140 . The two electrodes  142  and the second conductive portion  128 B 2  of the mass will respectively be equivalent to be two capacitors. When the Lorentz force, produced by the electrical current and the magnetic force, drives the mass  120  to rotate relative to the anchor  110 , the capacitances of the two capacitors will be varied. The magnetic force at the place where the microelectromechanical system device  100  is located can be obtained by calculating the variation of the capacitance. 
     In one of some exemplary embodiments for depicting a layout of the base conductive layer  128 C on the mass  120  is schematically illustrated in  FIG. 6 , but not limited thereto. The base conductive layer  128 C of the mass  120  is a single-turn spiral-shaped conductor surrounding the periphery of the mass  120 . The Lorentz force also will be produced when the electrical current flowing through the base conductive layer  128 C interacts with the magnetic force, thus the mass  120  rotates relative to the anchor  110 . 
       FIG. 7A  is a top view of a microelectromechanical system device with electrical interconnections according to another embodiment of the disclosure.  FIG. 7B  is a side view of the microelectromechanical system device in  FIG. 7A  along a section line IV-IV. Referring to  FIG. 7A  and  FIG. 7B , the microelectromechanical system device with electrical interconnections  200  is a MEMS micro-mirror. The microelectromechanical system device  200  further includes a mirror layer  210 , which is disposed on the upper surface of the mass  120 . The shape of the mirror layer  210  may be rectangular, round, or another shape. The microelectromechanical system device  200  further includes two permanent magnets  220 . As seen in  FIG. 7A , the two anchors  110  are located on two opposite sides of the mass  120  and approximately arranged along the section line IV-IV, while the two permanent magnets  220  are disposed near the mass  120  and are aligned with a line that is perpendicular to the section line IV-IV. The mass  120  is located between the two permanent magnets  220 , and the mass  120  is also located between the two anchors  110 . The opposite magnetic poles of the two permanent magnets  220  face each other. For example, the S pole of the permanent magnet  220  on the upper side in  FIG. 7A  faces the N pole of the permanent magnet  220  on the lower side in  FIG. 7B . The Lorentz force, induced by the electrical current and the magnetic force, may be adjusted by varying the electrical current flowing through the base conductive layer  128 A. By varying the electrical current, the mass  120  can be rotated to a specific angle r. Thus, the light travelling to the mirror layer  210  will be reflected to a targeted direction. The material of the mirror layer  210  may be aluminium, silver or other proper material for reflection. 
       FIG. 8A  is a top view of a microelectromechanical system device with electrical interconnections according to another embodiment of the disclosure.  FIG. 8B  is a side view of the microelectromechanical system device in  FIG. 8A  along a section line V-V. Referring to  FIG. 8A  and  FIG. 8B , in this embodiment, the microelectromechanical system device with electrical interconnections  300  is a MEMS magnetometer. However, the mass  310  of the embodiment is a frame, it means that the mass  310  has an opening  312 . The mass  310  with the opening  312  may increase the sensitivity of the microelectromechanical system device  300 . 
       FIG. 9A  is a top view of a microelectromechanical system device with electrical interconnections according to another embodiment of the disclosure.  FIG. 9B  is a side view of the microelectromechanical system device in  FIG. 9A  along a section line VI-VI. Referring to  FIG. 9A  and  FIG. 9B , in this embodiment, the microelectromechanical system device with electrical interconnections  400  is a combination of a magnetometer and a two-axis accelerometer. The mass  410  of the embodiment is a frame. The microelectromechanical system device  400  of the embodiment further includes an inner frame  452  and an inner mass  454 . The inner frame  452  is disposed within the frame of the mass  410  and is connected to the frame of the mass  410  via a plurality of first springs  456 . The inner mass  454  is disposed in the inner frame  452 , and the inner mass  454  is connected to the inner frame  452  via a plurality of second springs  458 . The inner mass  454  is electrically coupled to the target conductive layer  128 B via the second springs  458 , the inner frame  452  and the first springs  456 . In addition, a plurality of moving electrodes  460  is disposed at the peripheral portion of the inner frame  452  and a plurality of moving electrodes  460  is disposed at the peripheral portion of the inner mass  454 . The substrate  140  of the embodiment also includes the two electrodes  142  as shown in  FIG. 9B . The two electrodes  142  are located below the frame of the mass  410 . For clear identifying the key elements of the microelectromechanical system device  400  of the embodiment the electrodes  142  are omitted in  FIG. 9A . The microelectromechanical system device  400  can detect the magnetic force by measuring the rotation of the frame of the mass  410  when electrical current flow through the base conductive layer  128 A. The two-axis accelerations can also be detected by measuring movement of the inner frame  452  and the movement of inner mass  454  respectively. 
       FIG. 10A  is a top view of a microelectromechanical system device with electrical interconnections according to another embodiment of the disclosure.  FIG. 10B  is a side view of the microelectromechanical system device in  FIG. 10A  along a section line VII-VII. Referring to  FIG. 10A  and  FIG. 10B , in the embodiment, the microelectromechanical system device with electrical interconnections  500  is a MEMS oscillator. The base conductive layer  522  of the mass  120  of the microelectromechanical system device  500  in the embodiment is an electrical resistance. When the electrical current flowing through the base conductive layer  522 , the base conductive layer  522  will generate heat. In one embodiment, an electrical resistance value which is proper for a heating condition can be selected for the base conductive layer  522 . For example, the electrical resistance value of base conductive layer can be selected to be larger than the electrical resistance value of the target conductive layer. The microelectromechanical system device  500  of the embodiment further includes a driving electrode  550  and a sensing electrode  560 , which are disposed on the substrate  140 . As seen in  FIG. 10A , the driving electrode  550  and the sensing electrode  560  are located on the two opposite sides of the mass  120 . The driving electrode  550  and the sensing electrode  560  will drive the mass  120  to oscillate between the driving electrode  550  and the sensing electrode  560 . In addition, the oscillating frequency of the oscillator will be varied with the change of the working environment temperature. In the microelectromechanical system device  500 , the base conductive layer  522  may generate heat to keep the constant temperature in the working environment. Hence, the oscillating frequency of the mass  120  may not be shifted when the environment temperature is varied. 
       FIG. 11A  is a top view of a microelectromechanical system device with electrical interconnections according to another embodiment of the disclosure.  FIG. 11B  is a side view of the microelectromechanical system device in  FIG. 11A  along a section line VIII-VIII. Referring to  FIG. 11A  and  FIG. 11B , the microelectromechanical system device with electrical interconnections  600  is a micro inductance. The two electrodes  142  and the two torsion springs  130  shown in  FIG. 5A  are not required in the microelectromechanical system device  600 . The micro inductance of the embodiment does not need the cross-line structure for electrical interconnection and thus reduces the use of the conductive layer and the electrical insulation layer. 
       FIG. 12A  to  FIG. 12H  are schematic fabricating flow for a microelectromechanical system device with electrical interconnections according to an embodiment of the disclosure. Referring to  FIG. 12A  to  FIG. 12C  a silicon on insulator wafer (SOI wafer) is provided. The silicon on insulator wafer P 10  includes a device layer P 1 , a handle layer P 2  and an electrical insulation layer P 3  disposed between the device layer P 1  and the handle layer P 2 . The material of the electrical insulation layer P 3  may be silicon dioxide (SiO2). 
     Etch the device layer P 1  to form a plurality of protruding portions S 1  and a recess portion S 2  which will be used to form the anchor, the mass and the torsion spring respectively in the following fabricating steps. Then, etch a first trench  114  at each protruding portion S 1 , and etch a trench  124  of mass at the recess portion S 2 . The first trench  114  and the trench  124  of mass extend to the electrical insulation layer P 3 . In addition, the electrical insulation materials  114 A and  124 A may be filled in the first trench  114  and the trench  124  of mass to form the electrical insulation structure. 
     Referring to  FIG. 12D  and  FIG. 12E , deposit the conductive bonding layer  146  on each protruding portion S 1 , and then bond the protruding portion S 1  to the conductive layer  144  on the substrate  140  via the conductive bonding layer  146 . The wafer-to-wafer metal bonding process can be employed for this bonding process. The substrate  140  may be a glass substrate or a silicon substrate with conductive traces on the surface or a circuit chip with conductive traces on the surface. When the bonding process is finished, the handle layer P 2  of the SOI wafer is removed. 
     Referring to  FIG. 12F  and  FIG. 12G , remove a portion of the electrical insulation layer P 3  to form at least one first through hole H 1  and at least one second through hole H 2 . The at least one first through hole H 1  is disposed on the protruding portion S 1  and portion of the protruding portions S 1  is then exposed in the first through hole H 1 . The at least one second through hole H 2  is disposed on the recess portion S 2  and portion of the recess portion S 2  is exposed in the second through hole H 2 . Then, form a plurality of upper conductive layers  118 A,  128 A and  134  on the electrical insulation layer P 3 . At the same time, a portion of the upper conductive layer  118 A is filled in the first through hole H 1  to form the first conductive through hole  116 , and a portion of the upper conductive layer (also called the base conductive layer)  128 A is filled in the second through hole H 2  to form the conductive through hole  126  of mass. 
     Finally, referring to  FIG. 12G  and  FIG. 12H , pattern the device layer P 1  and pattern the electrical insulation layer P 3 . By this process, the lower conductive layer  118 B of the anchor  110  and the insulation layer of the anchor  110  are formed from the protruding portions S 1 . The lower conductive layer (also called the target conductive layer in this embodiment)  128 B of the mass  120  and the insulation layer of the mass  120  are formed from the recess portion S 2 . The lower conductive layer  136  of the torsion spring  130  and the insulation layer  132  of the torsion spring is also formed from the recess portion S 2 . Specifically speaking, the fabricated microelectromechanical system device  100  in  FIG. 12H  is the same as the microelectromechanical system device  100  in  FIG. 5B . 
     The fabricating flow as illustrated in  FIG. 12A  to  FIG. 12H  can also be applied to fabricate the microelectromechanical system device  200  as shown in  FIG. 7B  except for some minor modification in the step of  FIG. 12F . In the modified step of  FIG. 12F , a particular area as desired near a central part of the insulation layer P 3  above the recess portion S 2  is removed. A minor layer  210  can be formed in the hollowed portion of the particular area. 
     The fabricating flow as illustrated in  FIG. 12A  to  FIG. 12H  can also be applied to fabricate the microelectromechanical system device  300  as shown in  FIG. 8B  except for some minor modification in the step of  FIG. 12C . In the modified step of  FIG. 12C , the device layer P 1  is etched to form the protruding portions Si and the recess portion S 2 , and at the same time, a particular area as desired near a central part of the device layer P 1  is removed. The hollowed portion of the particular area in the device layer P 1  can be the opening  312  of the mass  310  as depicted in  FIG. 8B . 
     The microelectromechanical system device  700 A in  FIG. 13A  is a simplified schematic diagram of the disclosure, where its target conductive layer  728 A is located below the lower surface of the second electrical insulation layer  722 . The target conductive layer  728 A is the lower conductive layer located between the electrical insulation layer  722  and the electrode  142  of the substrate  140 . The electrical insulation layer  722  divides the mass  720 A into the base conductive layer  726 A and the target conductive layer  728 A. The target conductive layer  728 A is divided into a first conductive portion  728 A 1  and a second conductive portion  728 A 2  which are insulated electrically from each other by the trench  724 A. The conductive through hole  730  passes through the electrical insulation layer  722  and connects the base conductive layer  726 A and the first conductive portion  728 A 1 . 
     The microelectromechanical system device  700 B shown in  FIG. 13B  is another simplified schematic diagram of the disclosure. The electrical insulation layer  722  divides the mass  720 B into the base conductive layer  726 B and the target conductive layer  728 B. The target conductive layer  728 B is disposed on the upper surface of the electrical insulation layer  722 . The target conductive layer  728 B is the upper conductive layer located on one side of the electrical insulation layer  722  away from the electrode  142  of the substrate  140 . The target conductive layer  728 B is divided into a first conductive portion  728 B 1  and a second conductive portion  728 B 2  which are insulated electrically from each other by the trench  724 B. The conductive through hole  730  passes through the electrical insulation layer  722  and connects the base conductive layer  726 B and the first conductive portion  728 B 1 . 
     In this embodiment, electrical interconnections are formed by employing the upper conductive layer, lower conductive layer, a electrical insulation layer, trench and conductive through hole. By electrical interconnections in this embodiment, the microelectromechanical system device does not require the cross-line structure to form electrical interconnections, and thus reduces the use of the conductive layer and the electrical insulation layer. Such a microelectromechanical system device may be applied in the MEMS magnetometer, the micro-mirror, the combination of a magnetometer and a two-axis accelerometer, the MEMS oscillator and the micro inductance. 
     While the invention has been described and illustrated with reference to specific embodiments thereof, these descriptions and illustrations do not limit the invention. It should be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the true spirit and scope of the invention as defined by the appended claims. The illustrations may not necessarily be drawn to scale. There may be distinctions between the artistic renditions in the present disclosure and the actual apparatus due to manufacturing processes and tolerances. There may be other embodiments of the present invention which are not specifically illustrated. The specification and the drawings are to be regarded as illustrative rather than restrictive. Modifications may be made to adapt a particular situation, material, composition of matter, method, or process to the objective, spirit and scope of the invention. All such modifications are intended to be within the scope of the claims appended hereto. While the methods disclosed herein have been described with reference to particular operations performed in a particular order, it will be understood that these operations may be combined, sub-divided, or re-ordered to form an equivalent method without departing from the teachings of the invention. Accordingly, unless specifically indicated herein, the order and grouping of the operations are not limitations of the invention.