An acceleration sensor

Abstract

The application discloses an acceleration sensor, comprising: a substrate; a plurality of anchor points fixed on the substrate; a detection mass connected with a first type of anchor point among the anchor points via an elastic structure; a first movable electrode connected with the detection mass via a rigid element; a first detection electrode connected with a second type of anchor point among the anchor points via a rigid element and forming a first set of detection capacitors with a corresponding first movable electrode; and a second detection electrode connected with a third type of anchor point among the anchor points via a rigid element and forming a second set of detection capacitors with a corresponding first movable electrode, the first set of detection capacitors and the second set of detection capacitors output a differential signal representing acceleration in a first direction, the first type of anchor point, the second type of anchor point and the third type of anchor point are arranged along two parallel second direction axes, and the first direction is perpendicular to the second direction. The acceleration sensor can significantly reduce the zero offset temperature drift coefficient and improve the thermal stress suppression capability.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to an acceleration sensor. Background Technology

[0002] Capacitive MEMS (Micro-Electro-Mechanical Systems) accelerometers are widely used as core sensing components in consumer electronics, automotive electronics, and industrial control. Capacitive MEMS accelerometers typically employ a comb-type capacitor structure to detect acceleration. They obtain the acceleration signal by detecting the change in capacitance between movable and fixed electrodes caused by the displacement of a mass under acceleration.

[0003] In existing technologies, differential capacitance designs are typically used to suppress common-mode interference and sensitivity and linearity are improved by optimizing mechanical structure parameters to enhance the performance of accelerometers. However, capacitive MEMS accelerometers are susceptible to changes in ambient temperature in practical applications. When the temperature changes, thermomechanical stress is generated inside the device due to the mismatch in thermal expansion coefficients between the packaging material and the chip substrate. This stress is transmitted to the anchor point through the substrate, causing additional displacements in the detection mass and comb electrodes that are unrelated to acceleration. This displacement manifests as a change in the zero-point output of each detection axis in the form of a pseudo-signal, resulting in a significant zero-bias temperature drift, which severely affects the accuracy and long-term stability of the sensor.

[0004] Currently, stress-induced electrode position changes are often compensated by introducing elastic elements into the coupling structure, or by using independent compensation structures to monitor anchor point displacement and perform signal correction. However, these methods often fail to completely eliminate the effects of non-uniform stress gradients, especially when anchor points at different locations on the substrate may experience displacements of different directions or magnitudes. The symmetry or rigid connection of existing compensation structures may result in limited compensation effectiveness and fail to adequately suppress zero-bias temperature drift. Summary of the Invention

[0005] In view of the above problems, the purpose of this application is to provide an accelerometer that can significantly reduce the zero bias temperature drift coefficient and improve the thermal stress suppression capability.

[0006] According to one aspect of this application, an acceleration sensor is provided, comprising: a substrate;

[0007] Multiple anchor points are used to fix the substrate;

[0008] The detection mass block is connected to the first type of anchor point among the anchor points via an elastic structure;

[0009] The first movable electrode is connected to the detection mass block via a rigid element;

[0010] The first detection electrode is connected to the second type of anchor point in the anchor point via a rigid element, and forms a first set of detection capacitors with the corresponding first movable electrode.

[0011] The second detection electrode is connected to a third type of anchor point among the anchor points via a rigid element, and forms a second set of detection capacitors with the corresponding first movable electrode. The first set of detection capacitors and the second set of detection capacitors output a differential signal characterizing the acceleration in the first direction.

[0012] The first type of anchor point, the second type of anchor point, and the third type of anchor point are arranged along two parallel second direction axes, and the first direction is perpendicular to the second direction.

[0013] Optionally, the first type of anchor points includes a first anchor point and a second anchor point distributed along a first direction; the second type of anchor points includes a third anchor point and a fourth anchor point distributed along the first direction; and the third type of anchor points includes a fifth anchor point and a sixth anchor point distributed along the first direction.

[0014] The first anchor point, the third anchor point, and the fifth anchor point are distributed along the second direction and located on the same axis.

[0015] The second, fourth, and sixth anchor points are distributed along the second direction and located on the same other axis.

[0016] Optionally, in the second direction, the first anchor point is located between the third and fifth anchor points, and the second anchor point is located between the fourth and sixth anchor points.

[0017] Optionally, it further includes: a second movable electrode, connected to the first anchor point and the second anchor point via a rigid element;

[0018] The first compensation electrode is connected to the third and fourth anchor points via a rigid element, and forms a first set of compensation capacitors with the corresponding second movable electrode to compensate for the zero-bias drift value of the first set of detection capacitors; and

[0019] The second compensation electrode is connected to the fifth and sixth anchor points via an elastic element, and forms a second set of compensation capacitors with the corresponding second movable electrode to compensate for the zero-bias drift value of the second set of detection capacitors.

[0020] Optionally, the second type of anchor points further includes a seventh and an eighth anchor point distributed along the first direction, and the third type of anchor points further includes a ninth and a tenth anchor point distributed along the first direction.

[0021] The first, third, fifth, seventh, and ninth anchor points are distributed along the second direction and located on the same axis.

[0022] The second, fourth, sixth, eighth, and tenth anchor points are distributed along the second direction and located on the same other axis.

[0023] Optionally, in the second direction, the third anchor point is located between the ninth anchor point and the first anchor point, the fourth anchor point is located between the tenth anchor point and the second anchor point, the fifth anchor point is located between the seventh anchor point and the first anchor point, and the sixth anchor point is located between the eighth anchor point and the second anchor point.

[0024] Optionally, the first detection electrode and the second detection electrode are mirror-distributed along the central axis of the accelerometer in the first direction.

[0025] Optionally, the detection mass block, the elastic structure, the rigid element connecting the first movable electrode and the detection mass block, and the rigid element connecting the second movable electrode to the first type of anchor point together form first to fourth blank regions distributed sequentially along the second direction. The second detection electrode is disposed in the first blank region and the third blank region, and the first detection electrode is disposed in the second blank region and the fourth blank region.

[0026] The detection electrodes in the first blank area and the second blank area are mirror images of the detection electrodes in the third blank area and the fourth blank area along the central axis of the accelerometer in the first direction.

[0027] Optionally, the first detection electrode includes a first set of comb teeth and a second set of comb teeth located in the second blank region, and a third to fifth set of comb teeth located in the fourth blank region. The first to fifth sets of comb teeth respectively form the first set of detection capacitors with the corresponding comb teeth in the first movable electrode.

[0028] The first set of comb teeth is connected to the third anchor point via a rigid element, and the second set of comb teeth is connected to the fourth anchor point via a rigid element.

[0029] The fourth set of comb teeth is located between the third and fifth sets of comb teeth, and the third set of comb teeth is connected to the seventh anchor point via a rigid element, the fifth set of comb teeth is connected to the eighth anchor point via a rigid element, and the fourth set of comb teeth is connected to both the seventh and eighth anchor points via rigid elements.

[0030] The third and fourth anchor points are located in the second blank area, and the seventh and eighth anchor points are located in the fourth blank area.

[0031] Optionally, a first compensation electrode is disposed in the second blank area. The first compensation electrode includes a sixth set of comb teeth, which is located between the first set of comb teeth and the second set of comb teeth. The sixth set of comb teeth and the corresponding comb teeth in the second movable electrode form the first set of compensation capacitors.

[0032] The first to fifth groups of comb teeth extend in the same direction along the second direction, and the sixth group of comb teeth extends in the second direction in the opposite direction to the first to fifth groups of comb teeth.

[0033] Optionally, the second detection electrode includes a seventh group of comb teeth and an eighth group of comb teeth located in the third blank area, and a ninth to eleventh group of comb teeth located in the first blank area. The seventh to eleventh groups of comb teeth respectively form the second group of detection capacitors with the corresponding comb teeth in the first movable electrode.

[0034] The seventh set of comb teeth is connected to the fifth anchor point via a rigid element, and the eighth set of comb teeth is connected to the sixth anchor point via a rigid element.

[0035] The tenth group of comb teeth is located between the ninth and eleventh group of comb teeth, and the ninth group of comb teeth is connected to the ninth anchor point via a rigid element, the eleventh group of comb teeth is connected to the tenth anchor point via a rigid element, and the tenth group of comb teeth is connected to both the ninth and tenth anchor points via a rigid element.

[0036] The fifth and sixth anchor points are located in the third blank area, and the ninth and tenth anchor points are located in the first blank area.

[0037] Optionally, a second compensation electrode is disposed in the third blank area. The second compensation electrode includes a twelfth group of comb teeth, which is located between the seventh group of comb teeth and the eighth group of comb teeth. The twelfth group of comb teeth and the corresponding comb teeth in the second movable electrode form the second group of compensation capacitors.

[0038] The seventh to eleventh groups of comb teeth extend in the same direction along the second direction, and the twelfth group of comb teeth extends in the second direction and in the opposite direction to the seventh to eleventh groups of comb teeth, and in the opposite direction to the sixth group of comb teeth.

[0039] Optionally, the first anchor point and the second anchor point are located between the third blank area and the second blank area.

[0040] Optionally, the first, third, fifth, seventh, and ninth anchor points are mirror images of the second, fourth, sixth, eighth, and tenth anchor points along the central axis of the accelerometer in the second direction.

[0041] Optionally, the acceleration sensor is an X-axis acceleration sensor or a Y-axis acceleration sensor.

[0042] Optionally, it also includes a stop structure disposed in the corner area of ​​the detection mass block.

[0043] The accelerometer provided in this application, based on an accelerometer capable of differential detection, utilizes a coaxial anchor point arrangement strategy to align the first, second, and third types of anchor points along an axis perpendicular to the detection direction (first direction). This makes the strain components of the substrate surface under thermal stress tend to be consistent among the anchor points, effectively suppressing the relative displacement between the detection comb teeth and the mass block comb teeth caused by non-uniform strain gradients, and reducing zero-bias drift from the source.

[0044] Furthermore, this application also includes a first compensation electrode and a second compensation electrode. The first compensation electrode is connected to the third and fourth anchor points via a rigid beam, and the second compensation electrode is connected to the fifth and sixth anchor points via a rigid element. This ensures that when the package undergoes thermal deformation, the zero-bias signal generated by the compensation capacitor has opposite polarity and can accurately cancel the drift component of the detection capacitor.

[0045] Furthermore, this application employs a mirror-symmetric layout based on the differential output architecture, further eliminating common-mode interference and improving the ability to suppress thermal stress. In other words, through the synergistic optimization of structural mechanics and circuit design, this application achieves a significant reduction in the temperature drift coefficient of the accelerometer itself without increasing the complexity of the manufacturing process. This makes it highly practical and competitive in temperature-sensitive applications such as consumer electronics, automotive electronics, and industrial control. Attached Figure Description

[0046] The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0047] Figure 1 A top view of the structure of an acceleration sensor provided according to an embodiment of this application is shown;

[0048] Figure 2 This diagram illustrates the structure of the electrode comb teeth of an accelerometer provided according to an embodiment of this application.

[0049] Figure 3 A schematic diagram of the capacitance of an accelerometer provided according to an embodiment of this application is shown;

[0050] Figure 4 This is a perspective view of a portion of the structure of an accelerometer provided according to an embodiment of this application;

[0051] Figure 5 A schematic diagram showing the strain components of the deformed surface of an accelerometer substrate according to an embodiment of this application is provided.

[0052] Figure 6 A schematic diagram showing the anchor point distribution of an accelerometer provided according to an embodiment of this application is shown. Detailed Implementation

[0053] Various embodiments of the invention will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements are indicated by the same or similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale.

[0054] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0055] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," and "coupling" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0056] Figure 1 A top view of the accelerometer provided according to an embodiment of this application is shown. Figure 2 A schematic diagram of the electrode comb of an accelerometer provided according to an embodiment of this application is shown. Figure 3 A schematic diagram of the capacitance of an accelerometer provided according to an embodiment of this application is shown. Figure 4 A perspective view of a portion of the structure of an accelerometer provided according to an embodiment of this application is shown. Figure 5 A schematic diagram showing the strain components of the deformed surface of an accelerometer substrate provided according to an embodiment of this application is shown. Figure 6 A schematic diagram showing the anchor point distribution of an accelerometer provided according to an embodiment of this application is shown.

[0057] Accelerometer 100 is, for example, a capacitive MEMS accelerometer, and the following description uses an X-axis accelerometer as an example. However, the implementation of this application is not limited to this. Based on the same concept, rotating the entire sensing structure by 90 degrees can form an accelerometer sensitive to a second direction (e.g., the Y-axis). Its structural features, working principle and technical effects are the same as or substantially similar to the X-axis accelerometer described below, and will not be repeated here.

[0058] like Figure 1 , Figure 2 , Figure 3 As shown, the accelerometer 100 includes a substrate, multiple anchor points, a detection mass block 101, a first detection electrode 110, a second detection electrode 120, and a first movable electrode 130.

[0059] Multiple anchor points are fixed on the substrate, including first-type anchor points, second-type anchor points, and third-type anchor points.

[0060] The detection mass block 101 is connected to the first type of anchor point among the anchor points via an elastic structure.

[0061] The first movable electrode 130 is connected to the detection mass block 101 via a rigid element.

[0062] The first detection electrode 110 is connected to the second type of anchor point in the anchor point via a rigid element, and forms a first set of detection capacitors with the corresponding first movable electrode.

[0063] The second detection electrode 120 is connected to the third type of anchor point in the anchor points via a rigid element, and forms a second set of detection capacitors with the corresponding first movable electrode.

[0064] Furthermore, the first set of detection capacitors and the second set of detection capacitors output a differential signal characterizing the acceleration in the first direction (X-axis direction).

[0065] Furthermore, the first type of anchor point, the second type of anchor point, and the third type of anchor point are aligned along an axis perpendicular to the detection direction (first direction). For example, the first type of anchor point, the second type of anchor point, and the third type of anchor point are arranged along two parallel second directions (Y-axis directions), where the first direction is perpendicular to the second direction.

[0066] For example, the first type of anchor points includes a first anchor point 1001 and a second anchor point 1002 distributed along a first direction; the second type of anchor points includes a third anchor point 1003 and a fourth anchor point 1004 distributed along the first direction; and the third type of anchor points includes a fifth anchor point 1005 and a sixth anchor point 1006 distributed along the first direction. Correspondingly, the accelerometer includes two blank areas for respectively setting the first detection electrode and the second detection electrode.

[0067] Furthermore, the first anchor point 1001, the third anchor point 1003, and the fifth anchor point 1005 are distributed along the second direction and located on the same axis. The second anchor point 1002, the fourth anchor point 1004, and the sixth anchor point 1006 are distributed along the second direction and located on another axis.

[0068] Furthermore, in the second direction, the first anchor point 1001 is located between the third anchor point 1003 and the fifth anchor point 1005. The second anchor point 1002 is located between the fourth anchor point 1004 and the sixth anchor point 1006.

[0069] In other embodiments, the acceleration sensor further includes a second movable electrode 160, a first compensation electrode 140, and a second compensation electrode 150.

[0070] The second movable electrode 160 is connected to the first anchor point 1001 and the second anchor point 1002 via a rigid element.

[0071] The first compensation electrode 140 is connected to the third anchor point 1003 and the fourth anchor point 1004 via a rigid element, and forms a first set of compensation capacitors with the corresponding second movable electrode 160 to compensate for the zero bias drift value of the first set of detection capacitors.

[0072] The second compensation electrode 150 is connected to the fifth anchor point 1005 and the sixth anchor point 1006 via an elastic element, and forms a second set of compensation capacitors with the corresponding second movable electrode to compensate for the zero bias drift value of the second set of detection capacitors.

[0073] In other embodiments, the second type of anchor points further includes a seventh anchor point 1007 and an eighth anchor point 1008 distributed along a first direction, and the third type of anchor points further includes a ninth anchor point 1009 and a tenth anchor point 1010 distributed along the first direction. The first anchor point 1001, the third anchor point 1003, the fifth anchor point 1005, the seventh anchor point 1007, and the ninth anchor point 1009 are distributed along a second direction and located on the same axis. The second anchor point 1002, the fourth anchor point 1004, the sixth anchor point 1006, the eighth anchor point 1008, and the tenth anchor point 1010 are distributed along the second direction and located on the same other axis.

[0074] Furthermore, in the second direction, the third anchor point 1003 is located between the ninth anchor point 1009 and the first anchor point 1001, the fourth anchor point 1004 is located between the tenth anchor point 1010 and the second anchor point 1002, the fifth anchor point 1005 is located between the seventh anchor point 1007 and the first anchor point 1001, and the sixth anchor point 1006 is located between the eighth anchor point 1008 and the second anchor point 1002.

[0075] Furthermore, the first detection electrode 110 and the second detection electrode 120 are mirror-distributed along the central axis of the accelerometer in the first direction.

[0076] For example, the detection mass 101, the elastic structure composed of elastic beam 1901 and rigid beam 1902, the rigid beam 1904 and rigid beam 1903 connecting the first movable electrode 130 and the detection mass 101, and the rigid element 1905 connecting the second movable electrode 160 to the first type of anchor point, together form first to fourth blank regions distributed sequentially along the second direction. The second detection electrode 120 is disposed in the first blank region 181 and the third blank region 183, and the first detection electrode 110 is disposed in the second blank region 182 and the fourth blank region 184. The detection electrodes in the first blank region 181 and the second blank region 182 are mirror images of the detection electrodes in the third blank region 183 and the fourth blank region 184 along the central axis of the accelerometer in the first direction.

[0077] For example, the first detection electrode 110 includes a first set of comb teeth 1101 and a second set of comb teeth 1102 located in the second blank area 182, and a third to fifth set of comb teeth located in the fourth blank area 184. The first to fifth sets of comb teeth form the first set of detection capacitors (Cs101, Cs102, Cs103, Cs104, Cs105, Cs106, Cs107, Cs108, Cs111, Cs112) with the corresponding comb teeth 131 in the first movable electrode 130, respectively. The first set of comb teeth 1101 is connected to the third anchor point 1003 via a rigid beam 1906, and the second set of comb teeth 1102 is connected to the fourth anchor point 1004 via a rigid beam 1907. The fourth set of comb teeth 1104 is located between the third set of comb teeth 1103 and the fifth set of comb teeth 1105. The third set of comb teeth 1103 is connected to the seventh anchor point 1007 via a rigid beam 1908, the fifth set of comb teeth 1105 is connected to the eighth anchor point 1008 via a rigid beam 1909, and the fourth set of comb teeth 1104 is connected to the seventh anchor point 1007 and the eighth anchor point 1008 via a rigid beam 1910. The third anchor point 1003 and the fourth anchor point 1004 are located in the second blank area 182, and the seventh anchor point 1007 and the eighth anchor point 1008 are located in the fourth blank area 184.

[0078] For example, a first compensation electrode 140 is provided in the second blank area 182. The first compensation electrode 140 includes a sixth set of comb teeth 141. The sixth set of comb teeth 141 is located between the first set of comb teeth 1101 and the second set of comb teeth 1102. The sixth set of comb teeth 141 and the corresponding comb teeth 161 in the second movable electrode 160 form the first set of compensation capacitors (Cs109, Cs110).

[0079] Furthermore, the first to fifth groups of comb teeth extend in the same direction along the second direction, and the sixth group of comb teeth 141 extends in the second direction and in the opposite direction to the first to fifth groups of comb teeth.

[0080] Exemplarily, the second detection electrode 120 includes a seventh set of comb teeth 1201 and an eighth set of comb teeth 1202 located in the third blank area 183, and a ninth to eleventh set of comb teeth located in the first blank area 181. The seventh to eleventh sets of comb teeth form the second set of detection capacitors (Cs201, Cs202, Cs205, Cs206, Cs207, Cs208, Cs209, Cs210, Cs211, Cs212) with the corresponding comb teeth 131 in the first movable electrode 130. The seventh set of comb teeth 1201 is connected to the fifth anchor point 1005 via a rigid beam 1912, and the eighth set of comb teeth 1202 is connected to the sixth anchor point 1006 via a rigid beam 1913. The tenth set of comb teeth 1204 is located between the ninth set of comb teeth 1203 and the eleventh set of comb teeth 1205. The ninth set of comb teeth 1203 is connected to the ninth anchor point 1009 via a rigid beam 1914, the eleventh set of comb teeth 1205 is connected to the tenth anchor point 1010 via a rigid beam 1915, and the tenth set of comb teeth 1204 is connected to both the ninth and tenth anchor points 1009 and 1010 via a rigid beam 1916. The fifth anchor point 1005 and the sixth anchor point 1006 are located in the third blank area 183, and the ninth and tenth anchor points 1009 are located in the first blank area 181.

[0081] For example, a second compensation electrode 150 is provided in the third blank area 183. The second compensation electrode 150 includes a twelfth group of comb teeth 151. The twelfth group of comb teeth 151 is located between the seventh group of comb teeth 1201 and the eighth group of comb teeth 1202. The twelfth group of comb teeth 151 and the corresponding comb teeth 161 in the second movable electrode 160 form the second group of compensation capacitors (Cs203, Cs204).

[0082] Furthermore, the seventh to eleventh groups of comb teeth extend in the same direction along the second direction, and the twelfth group of comb teeth 151 extends in the second direction and in the opposite direction to the direction in which the seventh to eleventh groups of comb teeth extend, and in the opposite direction to the direction in which the sixth group of comb teeth 141 extends.

[0083] Furthermore, the first anchor point 1001 and the second anchor point 1002 are located between the third blank area 183 and the second blank area 182.

[0084] Furthermore, the first anchor point 1001, the third anchor point 1003, the fifth anchor point 1005, the seventh anchor point 1007, and the ninth anchor point 1009 are mirror images of the second anchor point 1002, the fourth anchor point 1004, the sixth anchor point 1006, the eighth anchor point 1008, and the tenth anchor point 1010 along the central axis of the accelerometer in the second direction.

[0085] Furthermore, the acceleration sensor also includes stop structures (171, 172, 173, 174) disposed in the corner area of ​​the detection mass block 101.

[0086] like Figure 3 As shown, the first set of detection capacitors (Cs101, Cs102, Cs103, Cs104, Cs105, Cs106, Cs107, Cs108, Cs111, Cs112) formed by the first detection electrode 110 and the first movable electrode 130, when the movable detection mass block 101 is subjected to an acceleration field or acceleration field component in the direction a in the figure, the relative position of the movable detection mass block 101 and the first detection electrode 110 shifts, generating a changing capacitance signal. Furthermore, the detection sensitivity is mainly determined by the stiffness of the movable detection mass block 101 and the elastic beam 1901. Further, the first compensation electrode 140 and the second movable electrode 160 forming the first set of compensation capacitors Cs109 and Cs110 are both connected to corresponding anchor points via rigid beams. Therefore, the sensitivity of the compensation capacitors in detecting changes in the acceleration field is extremely small, and Cs109 and Cs110 do not participate in the acceleration detection in the direction a. When the package deforms due to thermal mismatch caused by temperature change, the comb teeth of the first detection electrode 110 and the comb teeth of the first movable electrode 130 will undergo relative displacement due to the relative difference in the anchor point positions, thereby forming a zero-bias signal. At the same time, the relative displacement between the comb teeth of the first compensation electrode 140 and the comb teeth of the second movable electrode 160 generates another part of the zero-bias signal with opposite polarity. That is, the capacitance changes of Cs109 and Cs110 are opposite in polarity to the sum of the zero-bias changes of the first set of detection capacitors, thus forming the compensation effect of the detection capacitor after the package deformation.

[0087] The second set of detection capacitors (Cs201, Cs202, Cs205, Cs206, Cs207, Cs208, Cs209, Cs210, Cs211, Cs212) formed by the second detection electrode 120 and the first movable electrode 130, when the movable detection mass block 101 is subjected to an acceleration field or acceleration field component in the direction a in the figure, the relative position of the movable detection mass block 101 and the second detection electrode 120 shifts, generating a changing capacitance signal. Furthermore, the detection sensitivity is mainly determined by the stiffness of the movable detection mass block 101 and the elastic beam 1901. Further, the second compensation electrode 150 and the second movable electrode 160, which form the second set of compensation capacitors Cs203 and Cs204, are both connected to corresponding anchor points via rigid beams. Therefore, the sensitivity of the compensation capacitors in detecting changes in the acceleration field is extremely small, and Cs203 and Cs204 do not participate in the acceleration detection in the direction a. When the package deforms due to thermal mismatch caused by temperature change, the comb teeth of the second detection electrode 120 and the comb teeth of the first movable electrode 130 will be relatively displaced due to the relative difference in the anchor point positions, thus forming a zero bias signal. At the same time, the relative displacement between the comb teeth of the second compensation electrode 150 and the comb teeth of the second movable electrode 160 generates another part of the zero bias signal with opposite polarity. That is, the capacitance changes of Cs203 and Cs204 are opposite in polarity to the sum of the zero bias changes of the second set of detection capacitors, thus forming the compensation effect of the detection capacitor after the package is deformed.

[0088] like Figure 4 As shown, for a clearer description, Figure 4 Only the chip substrate 102, anchor point structure, and packaging substrate 103 are retained. When the internal stress distribution of the package changes due to thermal mismatch, the chip substrate 102 will be subjected to stress from all directions of the package, resulting in deformation (strain) inside the substrate and on the substrate surface connected to the anchor points. The strain at each point on the surface of the substrate 102 can be decomposed into strain components in three directions: εx, εy, and εz. Taking an X-axis or Y-axis accelerometer as an example, the distribution of the deformation components (εx / εy) on the surface of the substrate 102 in its detection direction is one of the most critical factors for its zero-bias drift. At the same time, the non-uniform strain gradient of the substrate in the X direction and the relative positions between the anchor points determine the relative displacement between the comb teeth of the detection electrode and the comb teeth of the movable electrode, thus affecting the severity of the zero-bias drift.

[0089] like Figure 5As shown, the εx values ​​on the strain gradient contour lines of the deformed surface of the accelerometer substrate 102 are at the same level. Based on the arrangement of the anchor points aligned along the axis perpendicular to the detection direction (first direction) in this application, the εx strain components transmitted to each anchor point will be close to or at the same level, greatly reducing the relative displacement in the X direction between the detection electrode comb teeth and the movable electrode comb teeth under thermal deformation of the package, and ultimately reducing the zero-bias drift of the first and second detection electrodes. Furthermore, the polarity of the capacitance change of the first and second sets of compensation capacitors under the strain components on the substrate surface is opposite to the polarity of the corresponding detection capacitance change, further reducing the zero-bias drift of the capacitance output of each detection electrode.

[0090] Furthermore, the relative positions of the multiple anchor points in the accelerometer structure proposed in this application, as well as the arrangement ratio of the compensation capacitor and the detection capacitor, can all affect the sensitivity of the sensor output to temperature changes and the offset value of the capacitor output.

[0091] like Figure 6 As shown, the second blank area 182 and the fourth blank area 184 include the first detection capacitors Cd1, Cd2, Cd3, Cd4, and Cd5, and the first compensation capacitor Ccp. The zero-bias drift of the first detection electrode 110 can be calculated by ΔC1 = ΔCd1 + ΔCd2 + ΔCd3 + ΔCd4 + ΔCd5 + ΔCCP (the calculation method for the zero-bias drift ΔC2 of the second detection electrode is similar and will not be repeated here). This application can obtain the optimal structure by adjusting the spacing D3 between the left and right axis anchor points, the minimum spacing D1 between the second type anchor point and the first type anchor point in the second direction, and the minimum spacing D2 between the second type anchor point / third type anchor point and the first type anchor point.

[0092] For example, this application can optimize the optimal structural design through finite element simulation. For instance, based on the initial structural design requirements, the capacitance zero-bias drift level of the initial structure under a defined package temperature mismatch simulation is first determined (this can be evaluated using the sum of the zero-bias drift levels of the first and second detection electrodes in the finite element simulation results: ΔC3 = ΔC1 + ΔC2). By adjusting the spacing D3, the arrangement of the anchor points on the substrate surface relative to the εx strain components is adjusted. Furthermore, the ratio between the compensation capacitor and the detection capacitor can be adjusted, and the optimal solution is determined based on the lowest capacitance drift level and the lowest relative electrode position offset level among different arrangement schemes. Next, by adjusting the spacings D1 and D2, the relative positions of the anchor points are adjusted to ensure that the coaxial anchor points are as close as possible to the εx strain component contour lines on the substrate surface. Finally, the final structural design is determined based on the lowest capacitance drift level among different spacings D1 and D2.

[0093] The accelerometer provided in this application, based on an accelerometer capable of differential detection, utilizes a coaxial anchor point arrangement strategy to align the first, second, and third types of anchor points along an axis perpendicular to the detection direction (first direction). This makes the strain components of the substrate surface under thermal stress tend to be consistent among the anchor points, effectively suppressing the relative displacement between the detection comb teeth and the mass block comb teeth caused by non-uniform strain gradients, and reducing zero-bias drift from the source.

[0094] Furthermore, this application also includes a first compensation electrode and a second compensation electrode. The first compensation electrode is connected to the third and fourth anchor points via a rigid beam, and the second compensation electrode is connected to the fifth and sixth anchor points via a rigid element. This ensures that when the package undergoes thermal deformation, the zero-bias signal generated by the compensation capacitor has opposite polarity and can accurately cancel the drift component of the detection capacitor.

[0095] Furthermore, this application employs a mirror-symmetric layout based on the differential output architecture, further eliminating common-mode interference and improving the ability to suppress thermal stress. In other words, through the synergistic optimization of structural mechanics and circuit design, this application achieves a significant reduction in the temperature drift coefficient of the accelerometer itself without increasing the complexity of the manufacturing process. This makes it highly practical and competitive in temperature-sensitive applications such as consumer electronics, automotive electronics, and industrial control.

[0096] As described above, these embodiments of the present invention do not exhaustively cover all details, nor do they limit the invention to the specific embodiments described. Clearly, many modifications and variations can be made based on the above description. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to effectively utilize the invention and its modifications. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. An acceleration sensor, comprising: Substrate; Multiple anchor points are used to fix the substrate; The detection mass block is connected to the first type of anchor point among the anchor points via an elastic structure; The first movable electrode is connected to the detection mass block via a rigid element; The first detection electrode is connected to the second type of anchor point in the anchor point via a rigid element, and forms a first set of detection capacitors with the corresponding first movable electrode. The second detection electrode is connected to a third type of anchor point among the anchor points via a rigid element, and forms a second set of detection capacitors with the corresponding first movable electrode. The first set of detection capacitors and the second set of detection capacitors output a differential signal characterizing the acceleration in the first direction. The first type of anchor point, the second type of anchor point, and the third type of anchor point are arranged along two parallel second direction axes, and the first direction is perpendicular to the second direction.

2. The acceleration sensor according to claim 1, wherein, The first type of anchor points includes a first anchor point and a second anchor point distributed along a first direction; the second type of anchor points includes a third anchor point and a fourth anchor point distributed along the first direction; and the third type of anchor points includes a fifth anchor point and a sixth anchor point distributed along the first direction. The first anchor point, the third anchor point, and the fifth anchor point are distributed along the second direction and located on the same axis. The second, fourth, and sixth anchor points are distributed along the second direction and located on the same other axis.

3. The acceleration sensor according to claim 2, wherein, In the second direction, the first anchor point is located between the third and fifth anchor points, and the second anchor point is located between the fourth and sixth anchor points.

4. The acceleration sensor according to claim 2, wherein, Also includes: The second movable electrode is connected to the first anchor point and the second anchor point via a rigid element; The first compensation electrode is connected to the third and fourth anchor points via a rigid element, and forms a first set of compensation capacitors with the corresponding second movable electrode to compensate for the zero bias drift value of the first set of detection capacitors. as well as The second compensation electrode is connected to the fifth and sixth anchor points via an elastic element, and forms a second set of compensation capacitors with the corresponding second movable electrode to compensate for the zero-bias drift value of the second set of detection capacitors.

5. The acceleration sensor according to claim 2, wherein, The second type of anchor points further includes a seventh and an eighth anchor point distributed along the first direction, and the third type of anchor points further includes a ninth and a tenth anchor point distributed along the first direction. The first, third, fifth, seventh, and ninth anchor points are distributed along the second direction and located on the same axis. The second, fourth, sixth, eighth, and tenth anchor points are distributed along the second direction and located on the same other axis.

6. The acceleration sensor according to claim 5, wherein, In the second direction, the third anchor point is located between the ninth anchor point and the first anchor point, the fourth anchor point is located between the tenth anchor point and the second anchor point, the fifth anchor point is located between the seventh anchor point and the first anchor point, and the sixth anchor point is located between the eighth anchor point and the second anchor point.

7. The acceleration sensor according to claim 2, wherein, The first detection electrode and the second detection electrode are mirror-distributed along the central axis of the accelerometer in the first direction.

8. The acceleration sensor according to claim 5, wherein, The detection mass block, the elastic structure, the rigid element connecting the first movable electrode and the detection mass block, and the rigid element connecting the second movable electrode to the first type of anchor point together form first to fourth blank regions distributed sequentially along the second direction. The second detection electrode is disposed in the first blank region and the third blank region, and the first detection electrode is disposed in the second blank region and the fourth blank region. The detection electrodes in the first blank area and the second blank area are mirror images of the detection electrodes in the third blank area and the fourth blank area along the central axis of the accelerometer in the first direction.

9. The acceleration sensor according to claim 8, wherein, The first detection electrode includes a first set of comb teeth and a second set of comb teeth located in the second blank region, and a third to fifth set of comb teeth located in the fourth blank region. The first to fifth sets of comb teeth respectively form the first set of detection capacitors with the corresponding comb teeth in the first movable electrode. The first set of comb teeth is connected to the third anchor point via a rigid element, and the second set of comb teeth is connected to the fourth anchor point via a rigid element. The fourth set of comb teeth is located between the third and fifth sets of comb teeth, and the third set of comb teeth is connected to the seventh anchor point via a rigid element, the fifth set of comb teeth is connected to the eighth anchor point via a rigid element, and the fourth set of comb teeth is connected to both the seventh and eighth anchor points via rigid elements. The third and fourth anchor points are located in the second blank area, and the seventh and eighth anchor points are located in the fourth blank area.

10. The acceleration sensor according to claim 9, wherein, A first compensation electrode is disposed in the second blank area. The first compensation electrode includes a sixth set of comb teeth, which is located between the first set of comb teeth and the second set of comb teeth. The sixth set of comb teeth and the corresponding comb teeth in the second movable electrode form a first set of compensation capacitors. The first to fifth groups of comb teeth extend in the same direction along the second direction, and the sixth group of comb teeth extends in the second direction in the opposite direction to the first to fifth groups of comb teeth.

11. The acceleration sensor according to claim 8, wherein, The second detection electrode includes a seventh group of comb teeth and an eighth group of comb teeth located in the third blank area, and a ninth to eleventh group of comb teeth located in the first blank area. The seventh to eleventh groups of comb teeth respectively form the second group of detection capacitors with the corresponding comb teeth in the first movable electrode. The seventh set of comb teeth is connected to the fifth anchor point via a rigid element, and the eighth set of comb teeth is connected to the sixth anchor point via a rigid element. The tenth group of comb teeth is located between the ninth and eleventh group of comb teeth, and the ninth group of comb teeth is connected to the ninth anchor point via a rigid element, the eleventh group of comb teeth is connected to the tenth anchor point via a rigid element, and the tenth group of comb teeth is connected to both the ninth and tenth anchor points via a rigid element. The fifth and sixth anchor points are located in the third blank area, and the ninth and tenth anchor points are located in the first blank area.

12. The acceleration sensor according to claim 11, wherein, A second compensation electrode is disposed in the third blank area. The second compensation electrode includes a twelfth group of comb teeth, which is located between the seventh group of comb teeth and the eighth group of comb teeth. The twelfth group of comb teeth and the corresponding comb teeth in the second movable electrode form a second compensation capacitor. The seventh to eleventh groups of comb teeth extend in the same direction along the second direction, and the twelfth group of comb teeth extends in the second direction and in the opposite direction to the seventh to eleventh groups of comb teeth, and in the opposite direction to the sixth group of comb teeth.

13. The acceleration sensor according to claim 8, wherein, The first anchor point and the second anchor point are located between the third blank area and the second blank area.

14. The acceleration sensor according to claim 5, wherein, The first, third, fifth, seventh, and ninth anchor points are mirror images of the second, fourth, sixth, eighth, and tenth anchor points along the central axis of the accelerometer in the second direction.

15. The acceleration sensor according to claim 1, wherein, The acceleration sensor is an X-axis acceleration sensor or a Y-axis acceleration sensor.

16. The acceleration sensor according to claim 1, characterized in that, Also includes: A stop structure is provided in the corner area of ​​the detection mass block.

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