CN104037027B - A kind of MEMS capacitance switch - Google Patents
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Abstract
一种MEMS电容开关,属于电子科学技术领域。包含带绝缘层的基底,信号传输线和两侧的地电极,信号传输线表面有介质层,介质层表面具有三个金属覆盖区,两个地电极上分别具有一个固定锚点,两个固定锚点支撑起驱动电极结构;驱动电极结构为“两翼”型阶跃结构,包括中间的第一驱动电极和两翼的第二、三驱动电极,第一驱动电极两侧采用固支梁与固定锚点相连,第二、三驱动电极分别采用悬臂梁与第一驱动电极相连,第二、三驱动电极与信号传输线之间的距离大于第一驱动电极与信号传输线之间的距离;三个驱动电极的面积依次增大。本发明可实现3个工作频段,并且具有插入损耗低、隔离度高、下拉电压低的特点,可应用于射频或微波通信系统中。
A MEMS capacitive switch belongs to the field of electronic science and technology. It includes a substrate with an insulating layer, a signal transmission line and ground electrodes on both sides. There is a dielectric layer on the surface of the signal transmission line. Support the driving electrode structure; the driving electrode structure is a "two-wing" step structure, including the first driving electrode in the middle and the second and third driving electrodes on the two wings. , the second and third driving electrodes are respectively connected to the first driving electrode using cantilever beams, the distance between the second and third driving electrodes and the signal transmission line is greater than the distance between the first driving electrode and the signal transmission line; the area of the three driving electrodes increase in turn. The invention can realize three working frequency bands, and has the characteristics of low insertion loss, high isolation and low pull-down voltage, and can be applied to radio frequency or microwave communication systems.
Description
技术领域technical field
本发明属于电子科学技术领域,涉及微机电系统(MEMS),尤其是一种MEMS电容开关。The invention belongs to the technical field of electronic science and relates to microelectromechanical systems (MEMS), in particular to a MEMS capacitance switch.
技术背景technical background
开关是射频(RF)和微波通信系统中的基本部件,射频微机电(RFMEMS)开关在射频和微波组件级和系统级都有很大的应用空间。在组件级可以用射频微机电(RFMEMS)开关构造压控振荡器、滤波器(电容开关,电感)和移相器等,是现代雷达和通信系统不可或缺的元件。射频微机电(RFMEMS)开关相比于传统的FET和PIN二极管开关具有直流功耗小、插入损耗低、隔离度高、互调失真小、工作频带宽及低成本,易于集成等特点。Switches are fundamental components in radio frequency (RF) and microwave communication systems, and radio frequency microelectromechanical (RFMEMS) switches have great potential for application at both the RF and microwave component and system levels. At the component level, radio frequency microelectromechanical (RFMEMS) switches can be used to construct voltage-controlled oscillators, filters (capacitor switches, inductors) and phase shifters, etc., which are indispensable components of modern radar and communication systems. Compared with traditional FET and PIN diode switches, radio frequency microelectromechanical (RFMEMS) switches have the characteristics of low DC power consumption, low insertion loss, high isolation, low intermodulation distortion, wide operating frequency band, low cost, and easy integration.
美国专利文献US7,265,647B2公开了一种可调式MEMS电容开关,如图1至图3所示,该可调式MEMS电容开关在衬底基片110表面中间区域设置有金属层108作为传输线,在传输线两侧分别具有金属层104和106作为地电极(地电极104和106的高度超过传输线108的高度),在作为传输线的金属层108表面覆盖有介质层109,并在其中一条地电极106表面覆盖有介质层402,在传输线108正上方设置三个悬梁结构112、120和122,三个悬梁结构横跨传输线108,两端分别置于两个地电极表面,且与覆盖绝缘介质层的电极形成可调电容。该结构加载一定的驱动电压拉下传输线上方的开关梁来实现开关从up到down态的转变。在down时,通过改变电极与悬梁间的可变电容以实现总电容的改变,使得开关有不同的谐振频率,使得在不同频段的获得较高隔离度。但该结构所有的开关梁都置在同一平面,若开关梁和传输线之间的距离过小,则开关的up态电容较大,造成开关的插入损耗增大,如果增加开关梁与传输线之间的距离,由于驱动电压与间距的平方关系,则开关的驱动电压会急剧增大,除此之外,介质层的粗糙度对开关的射频性能产生较大的影响,这些都将严重限制的RFMEMS开关的应用范围。U.S. Patent No. 7,265,647B2 discloses an adjustable MEMS capacitive switch. As shown in FIGS. Both sides of the transmission line have metal layers 104 and 106 as ground electrodes (the height of the ground electrodes 104 and 106 exceeds the height of the transmission line 108), and the surface of the metal layer 108 as the transmission line is covered with a dielectric layer 109, and one of the ground electrodes 106 surface Covered with a dielectric layer 402, three suspension beam structures 112, 120 and 122 are arranged directly above the transmission line 108. The three suspension beam structures straddle the transmission line 108, and the two ends are respectively placed on the surfaces of the two ground electrodes, and are connected to the electrodes covered with the insulating dielectric layer. form an adjustable capacitor. The structure loads a certain driving voltage to pull down the switch beam above the transmission line to realize the transition of the switch from up to down state. When down, the total capacitance is changed by changing the variable capacitance between the electrode and the cantilever, so that the switch has different resonant frequencies, so that higher isolation can be obtained in different frequency bands. However, all the switch beams of this structure are placed on the same plane. If the distance between the switch beam and the transmission line is too small, the up-state capacitance of the switch will be large, resulting in an increase in the insertion loss of the switch. If the distance between the switch beam and the transmission line is increased Due to the square relationship between the driving voltage and the spacing, the driving voltage of the switch will increase sharply. In addition, the roughness of the dielectric layer has a greater impact on the RF performance of the switch, which will seriously limit the RFMEMS The scope of application of the switch.
发明内容Contents of the invention
本发明提供一种可工作于3个频段内的频段可调式高隔离度/低插损MEMS电容开关,具有插入损耗低,隔离度高,下拉电压低的特点,可应用于射频或微波通信系统中。The invention provides a frequency band adjustable high isolation/low insertion loss MEMS capacitive switch that can work in three frequency bands, has the characteristics of low insertion loss, high isolation, and low pull-down voltage, and can be applied to radio frequency or microwave communication systems middle.
本发明的技术方案如下:Technical scheme of the present invention is as follows:
一种MEMS电容开关,如图3至图5所示,包括一个表面具有绝缘层8的衬底7,在绝缘层8表面的中间位置具有导电材料制作的信号传输线9,在信号传输线9两侧的绝缘层8表面分别具有一条平行于信号传输线9的地电极13-1和13-2,在信号传输线9表面全层覆盖有一层介质层10,在介质层10的表面设置有第一金属覆盖区11-2、第二金属覆盖区11-1和第三金属覆盖区11-3,其中第一金属覆盖区11-2位于第二金属覆盖区11-1和第三金属覆盖区11-3之间;在第一地电极13-1表面设置有第一固定锚点12-1,在第二地电极13-2表面设置有第二固定锚点12-2,在第一固定锚点12-1和第二固定锚点12-2之间连接有一个驱动电极结构;所述驱动电极结构包括三个驱动电极,其中第一驱动电极4位于第一金属覆盖区11-2上方,第二驱动电极5位于第二金属覆盖区11-1上方,第三驱动电极6位于第三金属覆盖区11-3上方,且第一驱动电极4的面积小于第二驱动电极5的面积,第二驱动电极5的面积小于第三驱动电极6的面积,三个驱动电极的面积分别小于与之对应的金属覆盖层的面积;第一驱动电极4与信号传输线9两侧对应的两个边中,一边采用第一固支梁1-1与第一固定锚点12-1相连,另一边采用第二固支梁1-2与第二固定锚点12-2相连;第二驱动电极5与第一驱动电极4之间采用第一悬臂梁2相连,第三驱动电极6与第一驱动电极4之间采用两个第二悬臂梁3相连;第二驱动电极5与第二金属覆盖区11-1之间的距离和第三驱动电极6与第三金属覆盖区11-3之间的距离相等,且大于第一驱动电极4与第一金属覆盖区11-2之间的距离。A MEMS capacitive switch, as shown in Figures 3 to 5, includes a substrate 7 with an insulating layer 8 on the surface, a signal transmission line 9 made of conductive material in the middle of the surface of the insulating layer 8, and on both sides of the signal transmission line 9 The surface of the insulating layer 8 has a ground electrode 13-1 and 13-2 parallel to the signal transmission line 9, the surface of the signal transmission line 9 is fully covered with a layer of dielectric layer 10, and the surface of the dielectric layer 10 is provided with a first metal covering area 11-2, the second metal covering area 11-1 and the third metal covering area 11-3, wherein the first metal covering area 11-2 is located in the second metal covering area 11-1 and the third metal covering area 11-3 Between; a first fixed anchor point 12-1 is set on the surface of the first ground electrode 13-1, a second fixed anchor point 12-2 is set on the surface of the second ground electrode 13-2, and the first fixed anchor point 12 A driving electrode structure is connected between -1 and the second fixed anchor point 12-2; the driving electrode structure includes three driving electrodes, wherein the first driving electrode 4 is located above the first metal covering region 11-2, and the second The driving electrode 5 is located above the second metal covering region 11-1, the third driving electrode 6 is located above the third metal covering region 11-3, and the area of the first driving electrode 4 is smaller than the area of the second driving electrode 5, and the second driving electrode 6 is located above the third metal covering region 11-3. The area of the electrode 5 is smaller than the area of the third driving electrode 6, and the areas of the three driving electrodes are respectively smaller than the area of the corresponding metal covering layer; among the two sides corresponding to the first driving electrode 4 and the two sides of the signal transmission line 9, one side The first fixed beam 1-1 is connected to the first fixed anchor point 12-1, and the other side is connected to the second fixed anchor point 12-2 by the second fixed beam 1-2; the second driving electrode 5 is connected to the first fixed anchor point 12-1. The driving electrodes 4 are connected by the first cantilever beam 2, and the third driving electrode 6 and the first driving electrode 4 are connected by two second cantilever beams 3; the second driving electrode 5 and the second metal covering area 11-1 The distance between them is equal to the distance between the third driving electrode 6 and the third metal covering region 11-3, and is greater than the distance between the first driving electrode 4 and the first metal covering region 11-2.
本发明的工作原理是:The working principle of the present invention is:
本发明提供的MEMS电容开关,具有三个驱动极板,其中第一驱动电极4为一个固支梁电极,第二驱动电极5和第三驱动电极6为位于固支梁电极“两翼”的悬臂梁电极,其等效电路如图6所示:信号传输线9、介质层10和第一金属覆盖区11-2构成固定电容C1,信号传输线9、介质层10和第二金属覆盖区11-1构成固定电容C2,信号传输线9、介质层10和第三金属覆盖区11-3构成固定电容C3,第一金属覆盖区11-2与第一驱动电极4以及二者之间的空气层构成可变电容C1’,第二金属覆盖区11-1与第二驱动电极5以及二者之间的空气层构成可变电容C2’,第三金属覆盖区11-3与第三驱动电极6以及二者之间的空气层构成可变电容C3’;整个MEMS电容开关在Up态时,“两翼”的悬臂梁驱动电极的存在相当于增大了驱动电极与信号线9之间的相对间距,减小了Up态的电容,进而使整个MEMS电容开关的插入损耗降低。当在三个驱动电极上施加偏置电压时(偏置下拉电压实际施加在地电极与信号传输线之间,由于地电极与三个驱动电极是电气相同的,所以偏置电压也可以说是施加在三个驱动电极上),整个MEMS电容开关由Up态相Down态转换:当施加的偏置电压大于第一驱动电极4的下拉电压时,第一驱动电极4被拉下来与第一金属覆盖区11-2相接触,同时第一驱动电极4两翼的第二驱动电极5和第三驱动电极6也被拉下一段距离(由于第一驱动电极4的面积小于第二驱动电极5的面积,第二驱动电极5的面积小于第三驱动电极6的面积,所以第一驱动电极4的下拉电压小于第二驱动电极5的下拉电压,第二驱动电极5的下拉电压小于第三驱动电极6的下拉电压),但并不与下面的金属覆盖区相接触,此时整个MEMS电容开关处于第一Down态(等效电路如图7(a)所示,等效电容为电容C1);继续增加偏置电压,当偏置电压大于第二驱动电极5的下拉电压时,第二驱动电极被拉下与第二金属覆盖区11-1相接触,但第三驱动电极6仍未被完全拉下,此时整个MEMS电容开关处于第二Down态(等效电路如图7(b)所示,等效电容为电容C1和电容C2的并联);再继续增加偏置电压,当偏置电压大于三驱动电极6的下拉电压时,第三驱动电极6也被拉下与第三金属覆盖区11-3相接触,此时整个MEMS电容开关处于第三Down态(等效电路如图7(c)所示,等效电容为电容C1、电容C2和电容C3的并联)。由于整个MEMS电容开关具有三个Down态,对应三个不同的等效电容,进而能够获得三个不同的谐振频率,使得整个MEMS电容开关可工作在三个不同的频段内。另外,在固支梁电极被拉下后,两翼的驱动电极相对信号传输线9的有效高度随之降低,再分别对另外两个电极施加驱动,即在完成一次驱动的基础上,进行二次驱动,可大大的减小一次性驱动所需的电压;在信号传输线9表面与各驱动电极相对应的绝缘介质层上覆盖一层面积大于相应驱动电极面积的金属覆盖层,当各个驱动电极被拉下与金属覆盖层相接触时,各驱动电极的有效面积转化为各个金属覆盖层的面积,相当于增大了电容的相对面积,加大了电容值,提高了隔离度;同时,由于金属覆盖层的存在,只要驱动电极被拉至与金属层的部分接触,便等效于整个极板与金属层接触,无需整个驱动电极被完全拉下,能够在提高开关电容比的同时大大降低驱动电压。The MEMS capacitive switch provided by the present invention has three driving plates, wherein the first driving electrode 4 is a fixed beam electrode, and the second driving electrode 5 and the third driving electrode 6 are cantilevers located on the "two wings" of the fixed beam electrode. The equivalent circuit of the beam electrode is shown in Figure 6: the signal transmission line 9, the dielectric layer 10 and the first metal covering area 11-2 form a fixed capacitance C1, and the signal transmission line 9, the dielectric layer 10 and the second metal covering area 11-1 Constitute a fixed capacitance C2, the signal transmission line 9, the dielectric layer 10 and the third metal covering area 11-3 form a fixed capacitance C3, the first metal covering area 11-2 and the first driving electrode 4 and the air layer between the two constitute a variable The variable capacitance C1', the second metal covering region 11-1 and the second driving electrode 5 and the air layer between the two constitute the variable capacitance C2', the third metal covering region 11-3 and the third driving electrode 6 and the two The air layer between them constitutes the variable capacitor C3'; when the entire MEMS capacitive switch is in the Up state, the existence of the "two-wing" cantilever beam driving electrodes is equivalent to increasing the relative distance between the driving electrodes and the signal line 9, reducing The capacitance in the Up state is reduced, thereby reducing the insertion loss of the entire MEMS capacitive switch. When a bias voltage is applied on the three drive electrodes (the bias pull-down voltage is actually applied between the ground electrode and the signal transmission line, since the ground electrode is electrically identical to the three drive electrodes, the bias voltage can also be said to be applied On the three drive electrodes), the entire MEMS capacitive switch is switched from the Up state to the Down state: when the applied bias voltage is greater than the pull-down voltage of the first drive electrode 4, the first drive electrode 4 is pulled down and covered with the first metal The area 11-2 is in contact, and the second drive electrode 5 and the third drive electrode 6 on the two wings of the first drive electrode 4 are also pulled down a certain distance (because the area of the first drive electrode 4 is smaller than the area of the second drive electrode 5, The area of the second drive electrode 5 is less than the area of the third drive electrode 6, so the pull-down voltage of the first drive electrode 4 is less than the pull-down voltage of the second drive electrode 5, and the pull-down voltage of the second drive electrode 5 is less than that of the third drive electrode 6. Pull-down voltage), but not in contact with the metal coverage area below, at this time the entire MEMS capacitive switch is in the first Down state (the equivalent circuit is shown in Figure 7(a), and the equivalent capacitance is capacitor C1); continue to increase Bias voltage, when the bias voltage is greater than the pull-down voltage of the second drive electrode 5, the second drive electrode is pulled down to be in contact with the second metal covering region 11-1, but the third drive electrode 6 is not completely pulled down , the entire MEMS capacitive switch is in the second Down state (the equivalent circuit is shown in Figure 7(b), and the equivalent capacitance is the parallel connection of capacitor C1 and capacitor C2); then continue to increase the bias voltage, when the bias voltage is greater than During the pull-down voltage of the three drive electrodes 6, the third drive electrode 6 is also pulled down to be in contact with the third metal covering region 11-3, and now the whole MEMS capacitive switch is in the third Down state (equivalent circuit as shown in Fig. 7(c ), the equivalent capacitance is the parallel connection of capacitor C1, capacitor C2 and capacitor C3). Since the entire MEMS capacitive switch has three Down states, corresponding to three different equivalent capacitances, three different resonant frequencies can be obtained, so that the entire MEMS capacitive switch can work in three different frequency bands. In addition, after the electrodes of the fixed beam are pulled down, the effective heights of the drive electrodes on the two wings relative to the signal transmission line 9 decrease accordingly, and then drive is applied to the other two electrodes respectively, that is, the second drive is performed on the basis of the first drive. , can greatly reduce the voltage required for one-time driving; the surface of the signal transmission line 9 is covered with a metal covering layer with an area larger than the area of the corresponding driving electrode on the insulating medium layer corresponding to each driving electrode, when each driving electrode is pulled When it is in contact with the metal covering layer, the effective area of each driving electrode is converted into the area of each metal covering layer, which is equivalent to increasing the relative area of the capacitor, increasing the capacitance value, and improving the isolation; at the same time, due to the metal covering The existence of the layer, as long as the driving electrode is pulled to part of the contact with the metal layer, it is equivalent to the contact of the entire plate with the metal layer, without the need for the entire driving electrode to be pulled down completely, which can greatly reduce the driving voltage while increasing the switching capacitance ratio .
在Down态时,驱动电极的下拉电压VP可以表述为:In the Down state, the pull-down voltage V P of the drive electrode can be expressed as:
其中k为驱动电极和支撑梁组成结构的弹性系数,ε0为真空介电常数,W为信号传输线9的宽度,w为驱动电极的宽度,h为驱动电极与信号传输线之间的距离。 Where k is the elastic coefficient of the structure composed of the driving electrode and the support beam, ε0 is the vacuum dielectric constant, W is the width of the signal transmission line 9, w is the width of the driving electrode, and h is the distance between the driving electrode and the signal transmission line.
开关的工作在开态(up态)时,S21参数表示的插入损耗为:When the switch works in the open state (up state), the insertion loss represented by the S 21 parameter is:
开关工作在关态(down态)时,若开关工作频率远离于其谐振频率,由于开关的电感值L一般为皮亨量级,电容C为皮法量级,所以1/jωC远大于jωL,因此开关的S21参数主要由开关的关态(down态)电容值Cdown决定,关态时,S21参数表示的开关隔离度为:When the switch is in the off state (down state), if the operating frequency of the switch is far away from its resonant frequency, since the inductance L of the switch is generally in the order of picohenries and the capacitance C is in the order of picofarads, 1/jωC is much larger than jωL, Therefore, the S 21 parameter of the switch is mainly determined by the off-state (down state) capacitance value C down of the switch. In the off state, the switch isolation represented by the S 21 parameter is:
综上所述,本发明提供的MEMS电容开关具有以下有益效果:In summary, the MEMS capacitive switch provided by the present invention has the following beneficial effects:
本发明提供的MEMS电容开关采用固支驱动电极与悬臂驱动电极相结合的结构,两种电极处于不同的水平高度的,形成一种“两翼”型阶跃结构,而传统的开关极板都处于同一水平面上,这使得本发明提供的MEMS电容开关减小了up态电容,进而减小插入损耗,同时因为使用多次下拉过程,降低了下拉电压,缓解了插入损耗与驱动电压之间的矛盾。同时,本发明提供的MEMS电容开关在信号传输线9表面的介质层10上增加了与三个驱动电极对应的金属覆盖层,相当于增加了电容极板间的相对面积,增大了down态电容,提高了隔离度,同时能有效降低下拉电压。The MEMS capacitive switch provided by the present invention adopts a structure in which a fixed drive electrode and a cantilever drive electrode are combined. The two electrodes are at different levels, forming a "two-wing" step structure, while the traditional switch plates are all in the On the same level, this makes the MEMS capacitive switch provided by the present invention reduce the up-state capacitance, thereby reducing the insertion loss, and at the same time, because of the use of multiple pull-down processes, the pull-down voltage is reduced, and the contradiction between the insertion loss and the driving voltage is alleviated . At the same time, the MEMS capacitive switch provided by the present invention adds a metal covering layer corresponding to the three driving electrodes on the dielectric layer 10 on the surface of the signal transmission line 9, which is equivalent to increasing the relative area between the capacitive plates and increasing the down state capacitance. , improves the isolation, and can effectively reduce the pull-down voltage.
附图说明Description of drawings
图1为美国专利文献US7,265,647B2公开的MEMS电容开关俯视结构示意图。FIG. 1 is a schematic top view structure diagram of a MEMS capacitive switch disclosed in US Patent No. 7,265,647B2.
图2为美国专利文献US7,265,647B2公开的MEMS电容开关在图1中的A-A连线剖视结构示意图。FIG. 2 is a schematic cross-sectional structural diagram of the A-A connection line in FIG. 1 of the MEMS capacitive switch disclosed in US Patent No. 7,265,647B2.
图3为本发明提供的MEMS电容开关的俯视结构示意图。Fig. 3 is a schematic top view structure diagram of the MEMS capacitive switch provided by the present invention.
图4为本发明提供的MEMS电容开关在图3中A-A连线剖视结构示意图。FIG. 4 is a schematic cross-sectional structural diagram of the MEMS capacitive switch provided by the present invention along the line A-A in FIG. 3 .
图5为本发明提供的MEMS电容开关在图3中B-B连线剖视结构示意图。FIG. 5 is a schematic cross-sectional structure diagram of the MEMS capacitive switch provided by the present invention on the line B-B in FIG. 3 .
图6为本发明提供的MEMS电容开关Up态等效电路图。FIG. 6 is an equivalent circuit diagram of an Up state of the MEMS capacitive switch provided by the present invention.
图7(a)为本发明提供的MEMS电容开关第一Down态等效电路图。Fig. 7(a) is an equivalent circuit diagram of the first Down state of the MEMS capacitive switch provided by the present invention.
图7(b)为本发明提供的MEMS电容开关第二Down态等效电路图。Fig. 7(b) is an equivalent circuit diagram of the second Down state of the MEMS capacitive switch provided by the present invention.
图7(c)为本发明提供的MEMS电容开关第三Down态等效电路图。Fig. 7(c) is an equivalent circuit diagram of the third Down state of the MEMS capacitive switch provided by the present invention.
图8为本发明提供的MEMS电容开关Up态的插入损耗仿真测试结果。Fig. 8 is the insertion loss simulation test result of the MEMS capacitive switch Up state provided by the present invention.
图9为本发明提供的MEMS电容开关Down态隔离度仿真测试结果。FIG. 9 is the simulation test result of the isolation of the MEMS capacitive switch in the Down state provided by the present invention.
具体实施方式detailed description
一种MEMS电容开关,如图3至图5所示,包括一个表面具有绝缘层8的衬底7,在绝缘层8表面的中间位置具有导电材料制作的信号传输线9,在信号传输线9两侧的绝缘层8表面分别具有一条平行于信号传输线9的地电极13-1和13-2,在信号传输线9表面全层覆盖有一层介质层10,在介质层10的表面设置有第一金属覆盖区11-2、第二金属覆盖区11-1和第三金属覆盖区11-3,其中第一金属覆盖区11-2位于第二金属覆盖区11-1和第三金属覆盖区11-3之间;在第一地电极13-1表面设置有第一固定锚点12-1,在第二地电极13-2表面设置有第二固定锚点12-2,在第一固定锚点12-1和第二固定锚点12-2之间连接有一个驱动电极结构;所述驱动电极结构包括三个驱动电极,其中第一驱动电极4位于第一金属覆盖区11-2上方,第二驱动电极5位于第二金属覆盖区11-1上方,第三驱动电极6位于第三金属覆盖区11-3上方,且第一驱动电极4的面积小于第二驱动电极5的面积,第二驱动电极5的面积小于第三驱动电极6的面积,,三个驱动电极的面积分别小于与之对应的金属覆盖层的面积;第一驱动电极4与信号传输线9两侧对应的两个边中,一边采用第一固支梁1-1与第一固定锚点12-1相连,另一边采用第二固支梁1-2与第二固定锚点12-2相连;第二驱动电极5与第一驱动电极4之间采用第一悬臂梁2相连,第三驱动电极6与第一驱动电极4之间采用两个第二悬臂梁3相连;第二驱动电极5与第二金属覆盖区11-1之间的距离和第三驱动电极6与第三金属覆盖区11-3之间的距离相等,且大于第一驱动电极4与第一金属覆盖区11-2之间的距离。A MEMS capacitive switch, as shown in Figures 3 to 5, includes a substrate 7 with an insulating layer 8 on the surface, a signal transmission line 9 made of conductive material in the middle of the surface of the insulating layer 8, and on both sides of the signal transmission line 9 The surface of the insulating layer 8 has a ground electrode 13-1 and 13-2 parallel to the signal transmission line 9, the surface of the signal transmission line 9 is fully covered with a layer of dielectric layer 10, and the surface of the dielectric layer 10 is provided with a first metal covering area 11-2, the second metal covering area 11-1 and the third metal covering area 11-3, wherein the first metal covering area 11-2 is located in the second metal covering area 11-1 and the third metal covering area 11-3 Between; a first fixed anchor point 12-1 is set on the surface of the first ground electrode 13-1, a second fixed anchor point 12-2 is set on the surface of the second ground electrode 13-2, and the first fixed anchor point 12 A driving electrode structure is connected between -1 and the second fixed anchor point 12-2; the driving electrode structure includes three driving electrodes, wherein the first driving electrode 4 is located above the first metal covering region 11-2, and the second The driving electrode 5 is located above the second metal covering region 11-1, the third driving electrode 6 is located above the third metal covering region 11-3, and the area of the first driving electrode 4 is smaller than the area of the second driving electrode 5, and the second driving electrode 6 is located above the third metal covering region 11-3. The area of the electrode 5 is smaller than the area of the third driving electrode 6, and the areas of the three driving electrodes are respectively smaller than the area of the corresponding metal covering layer; in the two sides corresponding to the first driving electrode 4 and the two sides of the signal transmission line 9, One side is connected to the first fixed anchor point 12-1 by using the first fixed beam 1-1, and the other side is connected to the second fixed anchor point 12-2 by the second fixed beam 1-2; the second driving electrode 5 is connected to the second fixed anchor point 12-1. One drive electrode 4 is connected with the first cantilever beam 2, and the third drive electrode 6 is connected with the first drive electrode 4 with two second cantilever beams 3; the second drive electrode 5 is connected with the second metal covering area 11- The distance between 1 is equal to the distance between the third driving electrode 6 and the third metal covering region 11-3, and is greater than the distance between the first driving electrode 4 and the first metal covering region 11-2.
上述方案中,各部分尺寸如下:In the above scheme, the dimensions of each part are as follows:
信号传输线9的长×宽×厚为1㎜×100μm×2μm、绝缘介质层10为厚度为0.35μm、材料为氮化硅(Si3N4),两条地电极12-1、12-2的长×宽×厚为1㎜×60μm×2μm,第一驱动电极4的长×宽×厚为40μm×60μm×2μm,两个固支梁1-1、1-2的长×宽×厚为60μm×10μm×2μm,第二驱动电极5的长×宽×厚为60μm×60μm×2μm,悬臂梁2或3的长×宽×厚为60μm×10μm×2μm,第三驱动电极6的长×宽×厚为100μm×60μm×2μm,第一驱动电极4与信号传输线9的间距为2μm,第二与第三驱动电极与信号传输线9的间距为6μm,三个金属覆盖层的厚度为0.05μm,第一金属覆盖层的长×宽为100μm×100μm,第二、三金属覆盖层的长×宽为400μm×100μm。The length×width×thickness of the signal transmission line 9 is 1mm×100μm×2μm, the insulating dielectric layer 10 is 0.35μm in thickness, and the material is silicon nitride (Si 3 N 4 ), two ground electrodes 12-1, 12-2 The length×width×thickness of the first driving electrode 4 is 1㎜×60μm×2μm, the length×width×thickness of the first driving electrode 4 is 40μm×60μm×2μm, and the length×width×thickness of the two fixed beams 1-1, 1-2 is 60 μm×10 μm×2 μm, the length×width×thickness of the second driving electrode 5 is 60 μm×60 μm×2 μm, the length×width×thickness of the cantilever beam 2 or 3 is 60 μm×10 μm×2 μm, the length of the third driving electrode 6 is × width × thickness is 100 μm × 60 μm × 2 μm, the distance between the first driving electrode 4 and the signal transmission line 9 is 2 μm, the distance between the second and third driving electrodes and the signal transmission line 9 is 6 μm, and the thickness of the three metal covering layers is 0.05 μm, the length×width of the first metal covering layer is 100 μm×100 μm, and the length×width of the second and third metal covering layers are 400 μm×100 μm.
开关的性能参数仿真结果如图8和图9所示,该MEMS电容开关在30GHz内可工作于3个频段内,且各频段的插损皆小于0.25dB,隔离度均高于37dB。The simulation results of the performance parameters of the switch are shown in Figure 8 and Figure 9. The MEMS capacitive switch can work in three frequency bands within 30 GHz, and the insertion loss of each frequency band is less than 0.25dB, and the isolation is higher than 37dB.
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