阅读说明：本技术 一种微机电系统的电容式加速度计 (A kind of capacitive accelerometer of MEMS ) 是由 郭慧芳 裘进 于 2019-09-16 设计创作，主要内容包括：本发明涉及微机电系统技术领域,尤其涉及一种微机电系统的电容式加速度计,一种微机电系统的电容式加速度计,包括一检测板、一支撑基座、以及一可动结构,可动结构可旋转的连接于支撑基座上；支撑基座设置于检测板的第一中轴线和第二中轴线的交点；电容式加速计还包括：多个电极以第一中轴线为对称轴相对设置于检测板上；多个电极以第二中轴线为对称轴呈镜像对称设置于检测板上。发明技术方案的有益效果在于：通过改变电容式加速度计的结构,有效地降低了因支撑基座应力和检测板翘曲产生的零点漂移,从而提升电容式加速度计的检测精度。(The present invention relates to micro-electromechanical system fields, more particularly to a kind of capacitive accelerometer of MEMS, a kind of capacitive accelerometer of MEMS, including a detection plate, a support base and a movable structure, movable structure is rotatable to be connected in support base；Support base is set to the first central axes of detection plate and the intersection point of the second central axes；Capacitive accelerometer further include: multiple electrodes are relatively arranged in detection plate using the first central axes as symmetry axis；Multiple electrodes are set in detection plate using the second central axes as symmetry axis in mirror symmetry.The beneficial effect of inventive technique scheme is: the structure by changing capacitive accelerometer, the null offset because of support base stress and detection slab warping generation is significantly reduced, to promote the detection accuracy of capacitive accelerometer.)

1. a kind of capacitive accelerometer of MEMS, including a detection plate, a support base and a movable structure, institute State that movable structure is rotatable to be connected in the support base；It is characterized in that, the support base is set to the detection First central axes of plate and the intersection point of the second central axes；The capacitive accelerometer further include:

Multiple electrodes are relatively arranged in the detection plate using first central axes as symmetry axis；

Multiple electrodes are set in the detection plate using second central axes as symmetry axis in mirror symmetry.

2. capacitive accelerometer according to claim 1, which is characterized in that the detection plate includes by described first Four detection zones that axis and second central axes mark off, each detection zone include at least a pair of electricity Pole.

3. capacitive accelerometer according to claim 2, which is characterized in that a pair of electrode include a positive electrode and One negative electrode.

4. capacitive accelerometer according to claim 2, which is characterized in that multiple institutes in each detection zone It states electrode to be arranged alternately, and each electrode is opposite with the adjacent polarity of the electrode.

5. capacitive accelerometer according to claim 1, which is characterized in that using first central axes as symmetry axis phase It is opposite to the polarity between two electrodes of setting.

6. capacitive accelerometer according to claim 1, which is characterized in that using second central axes as symmetry axis pair Claim the polarity between two electrodes of setting identical.

7. capacitive accelerometer according to claim 1, which is characterized in that the size of multiple electrodes is identical.

Technical field

The present invention relates to micro-electromechanical system field more particularly to a kind of capacitive accelerometers of MEMS.

Background technique

It is well known that the drift of capacitive accelerometer is always the technical problem that those skilled in the art need to capture, The especially drift of Z axis.As shown in Figure 1, MEMS (Micro Electro Mechanical System, MEMS) The sensing unit of capacitive accelerometer be by detection plate 1, support base 2, the movable structure 3 that is set in support base 2 with And the differential capacitance that the multiple electrodes 4 being set in detection plate 1 form.As shown in Figure 1, in the ideal case, working as sensing unit Be when not by sensing power or external force, at left and right sides of differential capacitance completely it is comparable, exporting is 0；As shown in Fig. 2, when sense When surveying unit by acceleration perpendicular to structural plan direction, movable structure 3 can generate inclination, so that support base two sides Capacitor changes, and the difference of two lateral capacitances is read by cmos signal processing circuit, then difference is converted to corresponding acceleration Value.

Current existing capacitive accelerometer has the following problems: even if (1) being not perpendicular to the acceleration of structural plan Degree, due to the stress of the support base of sensing unit, movable structure 3 can be rotated relative to the electrode in detection plate 1, So that the capacitor of the left and right sides is asymmetric, to generate drift；(2) as shown in figure 3, detection plate 1 is pasted in high temperature or on surface Warpage can also occur in dress technique (Surface MountTechnology, SMT), equally also result in zero point and drift about.Cause This, now needs a kind of capacitive accelerometer for reducing drift.

Summary of the invention

For the above-mentioned problems in the prior art, a kind of capacitive accelerometer of MEMS is now provided.

Specific technical solution is as follows:

The present invention includes a kind of capacitive accelerometer of MEMS, including a detection plate, a support base and One movable structure, the movable structure is rotatable to be connected in the support base；The support base is set to the inspection First central axes of drafting board and the intersection point of the second central axes；The capacitive accelerometer further include:

Multiple electrodes are relatively arranged in the detection plate using first central axes as symmetry axis；

Multiple electrodes are set in the detection plate using second central axes as symmetry axis in mirror symmetry.

Preferably, the detection plate includes four detections marked off by first central axes and second central axes Region, each detection zone include at least a pair of electrode.

Preferably, a pair of electrode includes a positive electrode and a negative electrode.

Preferably, multiple electrodes in each detection zone are arranged alternately, and each electrode with it is adjacent The electrode polarity it is opposite.

Preferably, opposite using polarity of first central axes between two electrodes that symmetry axis is oppositely arranged.

Preferably, identical using polarity of second central axes between symmetrically arranged two electrodes of symmetry axis.

Preferably, the size of multiple electrodes is identical.

The beneficial effect of inventive technique scheme is: movable structure and detection plate by optimizing capacitive accelerometer The distribution of top electrode significantly reduces the null offset of the warpage generation of the stress and detection plate because of support base, to mention The detection accuracy of capacitive accelerometer is risen.

Detailed description of the invention

With reference to appended attached drawing, to be described more fully the embodiment of the present invention.However, appended attached drawing be merely to illustrate and It illustrates, and is not meant to limit the scope of the invention.

Fig. 1 is the structural schematic diagram of capacitive accelerometer ideally；

Fig. 2 is the structural schematic diagram of the capacitive accelerometer under the stress of support base；

Fig. 3 is the structural schematic diagram of capacitive accelerometer when detecting plate benging；

Fig. 4 is the distribution of electrodes figure of basic structure A in the prior art；

Fig. 5 is the distribution of electrodes figure of the first optimization structure B in the embodiment of the present invention；

Fig. 6 is the distribution of electrodes figure of the second optimization structure C in the embodiment of the present invention.

Specific embodiment

Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete Site preparation description, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on Embodiment in the present invention, those of ordinary skill in the art without creative labor it is obtained it is all its His embodiment, shall fall within the protection scope of the present invention.

It should be noted that in the absence of conflict, the feature in embodiment and embodiment in the present invention can phase Mutually combination.

The present invention will be further explained below with reference to the attached drawings and specific examples, but not as the limitation of the invention.

Specifically, first to the basic structure of existing capacitive accelerometer there are the problem of analyze, such as Fig. 4 institute Show, in the case where no Z-direction (perpendicular to the direction of structural plan) acceleration, due to answering for sensing unit support base Power effect, movable structure 3 can be rotated relative to detection plate 1, and movable structure 3 may both turn around the first central axes (X-axis shown in Fig. 4) It is dynamic, it is also possible to it is rotated around the second central axes (Y-axis shown in Fig. 4), meanwhile, by the effect of high temperature or surface mount process, detection Plate 1 may bend, and the spacing Z between movable structure 3 and electrode will receive the influence of factors above, can use following formula It indicates:

Z=Z (x, y)=gap+R (x)+R (y)+Curv (x, y)；

R (x)=Rx*x；R (y)=Ry*y；Curv (x, y)=K/2* (X²+Y²)；

Z for indicate after sensing unit deforms movable structure to the spacing between electrode, Z be x, the function of y；With branch Support group seat coordinate (0,0), x and y are used to indicate the coordinate value (x, y) of electrode centers；

Gap is used to indicate sensing unit, and there is no movable structures when deformation to the original pitch between detection plate electrode；

Rx is for indicating rotation angle of the movable structure around X-axis；

Ry is for indicating rotation angle of the movable structure around Y-axis；

K is used to indicate the bending value of detection plate；

Curv is for indicating the deformation values as caused by bending value K.

Correspondingly, the capacitor between movable structure 3 and electrode can be indicated with following formula:

C=eps*A/Z

Wherein dielectric constant of the eps between capacitor plate, A are movable structure area corresponding with detection plate top electrode, electricity Capacitance is nonlinear with corresponding spacing.

Since sensing unit deforms, movable structure 3 is rotated relative to detection plate 1, and detection plate 1 bends, such as Fig. 4 institute Show, we can be summarized as following several situations:

(1) movable structure is rotated only along X-axis, top electrode (E1t, E2t shown in Fig. 4) and lower electrode (E1b shown in Fig. 4, E2b) spacing between movable structure changes as movable structure changes around the rotation angle (i.e. Rx) of X-axis；

(2) movable structure is rotated only along Y-axis, left electrode (E1t, E1b shown in Fig. 4) and right electrode (E2t shown in Fig. 4, E2b) spacing between movable structure changes as movable structure changes around the rotation angle (i.e. Ry) of Y-axis；

(3) detect plate benging, spacing between electrode and movable structure with electrode and the supporting point of support base away from It is different from difference；

(4) Rx and Ry are existed simultaneously, that is, generate the inclination of Rs angle, (S1, S2 are it to movable structure around S1 or S2 rotation Middle a kind of embodiment, according to the difference of Rx or Ry relative value, it is also possible to be rotated around other directions)；

(5) plate benging is detected, Rx is existed simultaneously；

(6) plate benging is detected, Ry is existed simultaneously；

(7) plate benging is detected, Rx and Ry are existed simultaneously.

Specifically, the variation of the spacing between electrode and movable structure is analyzed from above seven situations, to analyze Z axis zero The drift situation of point.As shown in figure 4, there are four pieces of electrodes of the same area in the lower section of movable structure 3, wherein E1t, E2t are positive electricity Pole；E1b, E2b are negative electrode, and the value read through cmos signal processing circuit is proportional to the capacitance variations value and negative electrode of positive electrode Capacitance variations value difference.

Specifically, in said circumstances (1), there are Rx inclination, the spacing of positive electrode E1t, E2t and movable structure 3 increases, The spacing of negative electrode E1b, E2b and movable structure 3 reduces simultaneously, in this configuration, even if capacitance signal is with the change of spacing Change be it is linear, Rx, which is tilted, also results in the null offset of Z axis.In said circumstances (2), there are Ry inclination, left electrode E1t, The spacing variation and the variation of the spacing of right electrode E2t, E2b and movable structure 3 of E1b and movable structure 3 are exactly the opposite, can mutually support Disappear.In said circumstances (3), detection plate 1 is bent, due to the supporting point distance having the same of four pieces of electrodes and support base, electricity The spacing of pole and movable structure 3 increases or reduces simultaneously, can cancel out each other.For situation (6), detects plate benging and there are Ry Inclination, although capacitance signal with the variation of spacing be it is nonlinear, situation (6) will not generate the null offset of z-axis, mainly Reason is to exist simultaneously positive electrode and negative electrode at left and right sides of Y-axis, can cancel out each other.For said circumstances (1), situation (4), situation (5) and situation (7) change due to all there is spacing caused by Rx is tilted, situation (4), (5), (7) are all The null offset of z-axis can be generated.By analysis it is known that the structure of existing capacitive accelerometer can be there are Rx inclinations When generate Z axis null offset.