TWI472002B - Mems apparatus - Google Patents

Description

Microelectromechanical device

The present disclosure relates to a microelectromechanical device, particularly a microelectromechanical device that is used as a mass block by coating a connecting layer through an oxide layer or an oxide layer.

In the semiconductor process, most of the fabrication of the components comes from the continuous process of the metal layer and the oxide layer. The metal layer is mostly formed by physical deposition, so the metal layer usually has tensile stress, and the oxide layer is mostly chemical. The deposition is formed by the way, so the oxide layer usually has compressive stress. A microelectromechanical (MEMS) device is a common semiconductor element formed by stacking a metal layer and an oxide layer, so the residual stress of the MEMS element is an equivalent stress value combined with compressive stress and tensile stress. The biggest advantage of MEMS components fabricated in semiconductor manufacturing is the integration of special-purpose integrated circuits (ASICs) and MEMS in the same plane, eliminating the need for complex packaging, but the biggest problem is the residual stress of MEMS structures.

The common XY-axis accelerometer is the application of MEMS components because the metal layer has tensile stress (the structure is curved upwards), and the oxide layer has compressive stress (the structure is bent downward), wherein the oxide layer is chemically bonded. The film is formed by the bond, the deposition temperature of the oxide layer is high, and the force between the bond and the bond causes the residual stress of the oxide layer to be greater than the residual stress of the metal, so the residual stress is dominated by the oxide layer and the MEMS structure is bent downward. At this time, although a rapid annealing (RTA) system can be used for the release of residual stress, the thermal expansion coefficient of the composite material must be considered. For example, the thermal expansion coefficient of the metal aluminum is 23 ppm/° C., and the thermal expansion coefficient of the oxide layer is 0.5. At ppm/°C, the stacking of two different materials results in a 46-fold difference in thermal expansion coefficient. As a result, when the MEMS structure is subjected to temperature changes, in addition to its own residual stress, it is necessary to consider the thermal expansion phenomenon when two different materials are stacked.

In general, most of the materials currently used in the MEMS element structure of the prior art have a high expansion coefficient, which causes the MEMS element structure to exhibit warpage when subjected to temperature changes.

The present disclosure provides a microelectromechanical device, which is a structure of a mass block by coating a connecting layer through an oxide layer or an oxide layer, so that the structure itself can be moved without being affected by temperature changes, thereby achieving high stability.

A microelectromechanical device according to an embodiment of the present disclosure includes a substrate, an oxide layer, and a plurality of cantilevers. The substrate includes a plurality of first electrodes, a plurality of second electrodes, a first region, a second region, and an etched region. The plurality of first electrodes are located in the first region, the plurality of second electrodes are located in the second region, the etching region is located at the center of the substrate, and the first region and the second region are opposite to each other. An oxide layer is disposed at a center of the etched region, the oxide layer includes a plurality of third electrodes, a plurality of fourth electrodes, a first side, and a second side, and the plurality of third electrodes are located on the first side, The fourth electrodes are located on the second side, and the first side and the second side are opposite to each other. A plurality of cantilevers are respectively disposed between the periphery of the substrate and the periphery of the oxide layer, and a plurality of cantilevers are used to support the oxide layer. The plurality of first electrodes and the plurality of third electrodes intersect each other, and the plurality of second electrodes and the plurality of fourth electrodes cross each other.

The above description of the disclosure and the following description of the embodiments are used The spirit and principles of the present disclosure are illustrated and explained, and a further explanation of the scope of the patent application of the present disclosure is provided.

The detailed features and advantages of the present disclosure are described in detail in the following detailed description of the embodiments of the present disclosure, which are The objects and advantages associated with the present disclosure can be readily understood by those skilled in the art. The following examples are intended to further illustrate the present disclosure, but are not intended to limit the scope of the disclosure.

Referring to FIG. 1 , a microelectromechanical device 100 according to an embodiment of the present disclosure includes a substrate 110 , an oxide layer 120 , and a plurality of cantilevers 130 . The substrate 110 includes a plurality of first electrodes 111, a plurality of second electrodes 112, a first region 113, a second region 114, and an etched region 115. The plurality of first electrodes 111 are located in the first region 113, the plurality of second electrodes 112 are located in the second region 114, the etching region 115 is located at the center of the substrate 110, and the first region 113 and the second region 114 are opposed to each other. In some embodiments, the material of the substrate 110 may be 矽, but not limited thereto, and the number of the first electrode 111 and the second electrode 112 may be eight, and is not limited thereto.

As shown in FIG. 1 , the oxide layer 120 is disposed at the center of the etched region 115 . The oxide layer 120 includes a plurality of third electrodes 121 , a plurality of fourth electrodes 122 , a first side 123 , and a second layer . The side edges 124, the plurality of third electrodes 121 are located on the first side 123, and the plurality of fourth electrodes 122 are located on the second side 124, and the first side 123 and the second side 124 are opposite to each other. In some embodiments, the oxide layer 120 can be oxidized. The thermal expansion coefficient of the oxide layer 120 may be 0.5 ppm/° C., but not limited thereto, and the number of the third electrode 121 and the fourth electrode 122 may be eight or not. In addition, the oxide layer 120 further includes a connecting layer (not shown). In some embodiments, the connecting layer may be made of tungsten and the connecting layer may have a thermal expansion coefficient of 4 ppm/° C. Limited.

As shown in FIG. 1 , a plurality of cantilevers 130 are respectively disposed between the periphery of the substrate 110 and the periphery of the oxide layer 120 , and a plurality of cantilevers 130 are used to support the oxide layer 120 . In some embodiments, the number of the cantilever 130 can be two, four, or six, but not limited thereto, and the material of the cantilever 130 can be metal. The plurality of first electrodes 111 and the plurality of third electrodes 121 cross each other, and the plurality of second electrodes 112 and the plurality of fourth electrodes 122 cross each other.

In the present embodiment, the MEMS device 100 acts as an accelerometer and the oxide layer 120 acts as a mass. The operation of the MEMS device 100 is mainly to drive the oxide layer 120 to receive an acceleration when the external environment changes, thereby driving the plurality of third electrodes 121 and the plurality of fourth electrodes 122 to receive the acceleration. Since the plurality of first electrodes 111 and the plurality of third electrodes 121 cross each other, the plurality of first electrodes 111 and the plurality of third electrodes 121 have overlapping coupling regions with each other, and an effect of coupling capacitance is formed. The difference between the front and rear coupling capacitances between the plurality of first electrodes 111 and the plurality of third electrodes 121 can be detected by using the difference between the oxide layer 120 and the received acceleration before receiving the acceleration. Similarly, the plurality of second electrodes 112 and the plurality of fourth electrodes 122 also form a coupling capacitance effect between each other, and can also detect the front-back coupling capacitance between the plurality of second electrodes 112 and the plurality of fourth electrodes 122. Difference For the detection of accelerometers.

In the present embodiment, the microelectromechanical device 100 is a structure in which the oxide layer 120 is used as a mass. The oxide layer 120 may be ceria and the thermal expansion coefficient of the oxide layer 120 may be 0.5 ppm/° C. In addition, the oxide layer 120 may be coated as a mass of the connecting layer. The material of the connecting layer may be tungsten and the connecting layer may have a thermal expansion coefficient of 4 ppm/° C. The structure of the foregoing mass is compared with the conventional structure of aluminum as a mass, since the coefficient of thermal expansion of aluminum is 23 ppm/° C., and the coefficients of thermal expansion of the oxide layer 120 and the connecting layer are 0.5 ppm/° C. and 4 ppm, respectively. /°C, the mass produced by coating the connection layer with the oxide layer 120 or the oxide layer 120 can avoid the instability of the warp, for example, and can not be used as an accelerometer detection application.

Please refer to the schematic diagram of the manufacturing process of a microelectromechanical device 100, which is shown in FIG. 2A and FIG. 2E, as shown in FIG. 2A. First, the substrate 210 is utilized. In the present embodiment, the material of the substrate 210 is germanium, and the oxide layer 220 is germanium dioxide and the thermal expansion coefficient of the oxide layer 220 is 0.5 ppm/° C. On the other hand, the oxide layer 220 and the connection layer (not shown) may be grown on the substrate 210, that is, the structure in which the oxide layer 220 covers the connection layer. In this embodiment, the material of the connection layer is Tungsten and the tie layer have a coefficient of thermal expansion of 4 ppm/°C.

Next, as shown in FIG. 2B, the photoresist 230 is first applied over the oxide layer 220, and a hard mask is defined through the photomask and the lithography process of exposure and development. The area covered by this hard mask is intended to be retained and not broken. Bad area. Next, as shown in FIG. 2C, dry etching is used to remove the oxide layer 220 not covered by the photoresist 230, and the oxide layer 220 covered by the photoresist 230 is retained. In this embodiment, the dry etching may be performed by reactive ion etching (RIE) or inductively coupled plasma (ICP) etching, but not limited thereto to achieve anisotropic etching. Next, as shown in FIG. 2D, the oxide layer 220 covered by the photoresist 230 is used as a mask, and the substrate 210 under the oxide layer 220 is removed by using the dry etching described above to suspend the structure of the oxide layer 220. An etched region 240 is formed. Finally, as shown in FIG. 2E, the photoresist 230 located above the oxide layer 220 is removed by the dry etching described above (as shown in FIG. 2D), and at this time, the MEMS of "Fig. 1" can be completed. Process of device 100.

In summary, compared with the prior art, since the MEMS device is coated with a connecting layer through an oxide layer or an oxide layer as a mass structure, the structure itself can be moved without being affected by temperature changes. To achieve high stability.

Although the disclosure is disclosed above in the foregoing embodiments, it is not intended to limit the disclosure. All changes and refinements are beyond the scope of this disclosure. Please refer to the attached patent application for the scope of protection defined by this disclosure.

100‧‧‧Micro-electromechanical devices

110, 210‧‧‧ substrate

111‧‧‧First electrode

112‧‧‧second electrode

113‧‧‧First District

114‧‧‧Second District

115, 240‧‧ ‧ etched area

120, 220‧‧‧ oxide layer

121‧‧‧ third electrode

122‧‧‧fourth electrode

123‧‧‧First side

124‧‧‧Second side

130‧‧‧cantilever

230‧‧‧Light resistance

1 is a microelectromechanical device in accordance with an embodiment of the present disclosure.

2A to 2E are schematic views showing a manufacturing process of a microelectromechanical device according to Fig. 1.

100‧‧‧Micro-electromechanical devices

110‧‧‧Substrate

111‧‧‧First electrode

112‧‧‧second electrode

113‧‧‧First District

114‧‧‧Second District

115‧‧‧etched area

120‧‧‧Oxide layer

121‧‧‧ third electrode

122‧‧‧fourth electrode

123‧‧‧First side

124‧‧‧Second side

130‧‧‧cantilever

Claims (6)

A microelectromechanical device includes: a substrate including a plurality of first electrodes, a plurality of second electrodes, a first region, a second region, and an etched region, wherein the first electrodes are located in the first region The second electrodes are located in the second region, the etching region is located at a center of the substrate, the first region and the second region are opposite to each other; an oxide layer is disposed at a center of the etching region, and the oxide layer includes a connection a layer, the connection layer is coated in the oxide layer, the connection layer is made of tungsten, and the oxide layer comprises a plurality of third electrodes, a plurality of fourth electrodes, a first side, and a second side. The third electrodes are located on the first side, the fourth electrodes are located on the second side, the first side and the second side are opposite to each other, and a plurality of cantilevers are respectively disposed around the substrate The cantilever is configured to support the oxide layer, and the first electrodes and the third electrodes are opposite to each other, and the second electrodes and the fourth electrodes are opposite to each other. The MEMS device of claim 1, wherein the material of the substrate is ruthenium. The MEMS device of claim 1, wherein the oxide layer is cerium oxide. The microelectromechanical device of claim 3, wherein the oxide layer has a coefficient of thermal expansion of 0.5 ppm/° C. The microelectromechanical device of claim 5, wherein the connecting layer has a coefficient of thermal expansion of 4 ppm/° C. The MEMS device of claim 1, wherein the materials of the cantilevers are metal.