MEMS double-layer film thermal expansion coefficient measuring device and method

Abstract

The invention discloses an MEMS double-layer film thermal expansion coefficient measuring device and method. The measuring device comprises a thermal actuator structure, a displacement measuring structure, a double-layer door-shaped structure and a compensation structure. The measurement method comprises the following steps: firstly, heating a thermal actuator structure to obtain a horizontal displacement value s1, and obtaining an average temperature change DT1 before and after the thermal actuator is heated; then the double-layer door-shaped structure is heated, and the average temperature change DT2 of the door-shaped structure before and after heating is obtained; when the double-layer door-shaped structure is heated, the thermal actuator structure is heated, and a horizontal displacement value s2 is obtained; calculating the thermal expansion coefficient of the double-layer film according to the geometric dimension of the measuring device, the Young modulus E1 and E2 of the double-layer film, the temperature change DT1, the temperature change DT2 and the horizontal displacement values s1 and s2; the MEMS double-layer film thermal expansion coefficient measuring device and method have the advantages of being easy to operate, low in cost and high in measuring speed, and can be used for parameter monitoring of a process line.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-electromechanical systems and material parameter measurement thereof, and in particular to a device and method for measuring thermal expansion coefficient of a MEMS double-layer film. Background Art

[0002] MEMS technology is widely used in sensors, actuators and micro-mechanical systems due to its miniaturization and high performance. In these applications, double-layer film structures are often used to achieve complex mechanical functions, but the differences in thermal expansion characteristics of different materials may cause thermal mismatch, thereby inducing thermal stress and deformation, affecting the reliability and stability of the device. The thermal expansion coefficient is an important material parameter that describes the thermal expansion characteristics, reflecting the degree of volume change of the material when the temperature changes. Measuring the thermal expansion coefficient of MEMS double-layer films can provide MEMS designers with key process parameters for designing, optimizing and predicting device performance. It can also be used to monitor the material parameters of the processing process line to ensure the yield of the process line.

[0003] At present, most methods for measuring the thermal expansion coefficient of MEMS thin film materials require special test equipment or vacuum test environment, which has high test cost and slow measurement speed. For example, the cantilever beam warping method is a common thermal expansion coefficient test method. The thermal expansion coefficient is obtained by measuring the out-of-plane deformation of the cantilever beam after heating. This method often requires expensive test equipment, such as laser interferometers, scanning electron microscopes, etc., and is not suitable for process line monitoring. Summary of the invention

[0004] The purpose of the present invention is to provide a device and method for measuring the thermal expansion coefficient of a MEMS double-layer film, which has low measurement cost and high measurement speed and can be used for parameter monitoring of a process line. To achieve the above purpose, the present invention adopts the following technical solutions:

[0005] In a first aspect, the present invention provides a MEMS double-layer film thermal expansion coefficient measuring device, comprising: a thermal actuator structure, a displacement measuring structure connected to the thermal actuator structure, a double-layer gate-type structure and a compensation structure;

[0006] The thermal actuator structure comprises: a connecting beam, a plurality of Z-shaped thermal arms connected to both sides of the connecting beam, a first anchoring area, a second anchoring area, a first metal electrode and a second metal electrode arranged on the upper surface of the first anchoring area, and a third metal electrode and a fourth metal electrode arranged on the upper surface of the second anchoring area; the thermal actuator structure is symmetrically arranged with respect to the connecting beam; the first anchoring area and the second anchoring area are respectively arranged on both sides of the connecting beam, and are connected to one end of the plurality of Z-shaped thermal arms away from the connecting beam;

[0007] The displacement measurement structure comprises: a moving tooth, a contact electrode, and a first fixed tooth and a second fixed tooth respectively arranged on both sides of the moving tooth; the contact electrode is arranged at one end of the moving tooth;

[0008] The double-layer gate-shaped structure comprises: a gate-shaped beam, a third anchoring area and a fourth anchoring area connected to the fixed support end of the gate-shaped beam, a fifth metal electrode and a sixth metal electrode arranged on the upper surface of the third anchoring area, and a seventh metal electrode and an eighth metal electrode arranged on the upper surface of the fourth anchoring area;

[0009] The compensation structure includes: a fixed support beam, a fifth anchor region and a sixth anchor region respectively connected to both ends of the fixed support beam, a ninth metal electrode and a tenth metal electrode arranged on the upper surface of the fifth anchor region, and an eleventh metal electrode and a twelfth metal electrode arranged on the upper surface of the sixth anchor region;

[0010] The connecting beam of the thermal actuator structure is connected to the end of the moving tooth away from the contact electrode; there is a gap between the contact electrode of the displacement measurement structure and the double-layer gate structure; the connecting beam, moving tooth, contact electrode and gate beam are all on the same horizontal axis.

[0011] Optionally, before the sacrificial layer is released, the horizontal initial spacing between the displacement measurement structure and the double-layer gate structure is d; wherein the sacrificial layer is arranged between the measurement device and the substrate when the measurement device is manufactured.

[0012] Optionally, in the displacement measurement structure, the movable teeth include a main beam, and a first comb tooth assembly and a second comb tooth assembly symmetrically connected on both sides of the main beam; one end of the main beam is connected to the connecting beam, and the other end is connected to the contact electrode; the first comb tooth assembly and the second comb tooth assembly each include m teeth, the width of the teeth is a, and the tooth spacing is b; wherein the thickness of the contact electrode is h1, and the width is consistent with the width of the gate beam;

[0013] The first fixed teeth include a first base beam and a comb tooth assembly A; the comb tooth assembly A corresponds to the first comb tooth assembly, and includes m fixed teeth A evenly distributed on the first base beam; the second fixed teeth include a second base beam and a comb tooth assembly B; the comb tooth assembly B corresponds to the second comb tooth assembly, and includes m fixed teeth B evenly distributed on the second base beam.

[0014] Optionally, the width of the fixed teeth A and the fixed teeth B are both a, and the tooth spacing is both b+Δ.

[0015] Optionally, in the initial state of the measuring device, the comb tooth assembly A is offset to the right by Δ compared to the first comb tooth assembly of the moving teeth, and the comb tooth assembly B is offset to the right by (m+1)Δ compared to the second comb tooth assembly of the moving teeth; wherein the right direction is the direction of the double-layer door type structure.

[0016] Optionally, in the thermal actuator structure, the Z-shaped thermal arm includes: a first long beam, a second long beam, and a short beam connecting the first long beam and the second long beam; an end of the first long beam away from the short beam is connected to the first anchor area or the second anchor area; an end of the second long beam away from the short beam is connected to the connecting beam; wherein the length of the first long beam and the second long beam are both L3, and the width is both w3, and the length of the short beam is L4, and the width is w3;

[0017] In the first anchor region, the first metal electrode and the second metal electrode are arranged along a length direction perpendicular to the connecting beam, and the second metal electrode is located closer to the connecting beam than the first metal electrode;

[0018] In the second anchor region, the third metal electrode and the fourth metal electrode are arranged along a length direction perpendicular to the connecting beam, and the third metal electrode is located closer to the connecting beam than the fourth metal electrode.

[0019] Optionally, in the double-layer door-shaped structure, the door-shaped beam includes: a first slender beam and a second slender beam arranged in parallel with each other, and a short wide beam connecting the first slender beam and the second slender beam; the length of the first slender beam and the second slender beam are both L1, and both are composed of a double-layer film, the width and thickness of the first film are w1 and h1 respectively, and the width and thickness of the second film are w2 and h2 respectively; the short wide beam is composed of a single-layer film, the length and width of the single-layer film are both L2, and the thickness is h1; wherein L1 L2, L2 w1 ,L2 w2; the width of each layer of the double-layer film and the single-layer film is less than 5 times the thickness of the layer;

[0020] One end of the first slender beam away from the short width beam is connected to the third anchor area, and one end of the second slender beam away from the short width beam is connected to the fourth anchor area;

[0021] In the third anchor region, the fifth metal electrode and the sixth metal electrode are arranged along a length direction perpendicular to the first elongated beam, and the sixth metal electrode is located closer to the first elongated beam than the fifth metal electrode;

[0022] In the fourth anchor region, the seventh metal electrode and the eighth metal electrode are arranged along a length direction perpendicular to the second elongated beam, and the seventh metal electrode is located closer to the second elongated beam than the eighth metal electrode.

[0023] Optionally, in the compensation structure, the length of the fixed-support beam is 2L1 and the width is w1; in the fifth anchor zone, the ninth metal electrode and the tenth metal electrode are arranged along the length direction of the fixed-support beam, and the position of the tenth metal electrode is closer to the fixed-support beam than the ninth metal electrode; in the sixth anchor zone, the eleventh metal electrode and the twelfth metal electrode are arranged along the length direction of the fixed-support beam, and the position of the eleventh metal electrode is closer to the fixed-support beam than the twelfth metal electrode.

[0024] Optionally, the materials of the connecting beam, the multiple Z-shaped thermal arms, the displacement measurement structure, the clamped beam, the first layer of the double-layer film, and the short wide beam are all polycrystalline silicon.

[0025] In a second aspect, the present invention provides a method for measuring the thermal expansion coefficient of a MEMS double-layer film using the measuring device of the first aspect, comprising:

[0026] Obtain the resistance R between the second metal electrode and the third metal electrode at room temperature respectively 10 , the resistance R between the sixth metal electrode and the seventh metal electrode 20 , and the resistance R between the tenth metal electrode and the eleventh metal electrode 30 ;

[0027] The thermal actuator structure is electrically heated for the first time. When the contact electrode contacts the double-layer gate structure, the horizontal displacement value s1 displayed by the displacement measurement structure is obtained, and the resistance R between the second metal electrode and the third metal electrode is measured at the same time. 11 ;

[0028] Based on the obtained resistance R 11 and R 10 , the average temperature change ΔT1 of the thermal actuator structure before and after the first heating is obtained;

[0029] The double-layer door-shaped structure is heated, and the resistance R between the sixth metal electrode and the seventh metal electrode of the double-layer door-shaped structure after heating is obtained. 21 ;

[0030] Based on the obtained resistance R 21 , R 30 and R 20 , the average temperature change ΔT2 of the double-layer door structure before and after heating is obtained;

[0031] On the basis of heating the double-layer door-type structure, the thermal actuator structure is electrically heated for a second time, and when the contact electrode comes into contact with the double-layer door-type structure, a horizontal displacement value s2 displayed by the displacement measurement structure at this time is obtained;

[0032] Based on the geometric dimensions of the measuring device, the Young's modulus E1 and E2 of the double-layer film, the average temperature change ΔT1 of the thermal actuator structure before and after heating, the average temperature change ΔT2 of the double-layer door structure before and after heating, and the horizontal displacement values ​​s1 and s2, the thermal expansion coefficients α1 and α2 of the double-layer film are calculated as follows:

[0033]

[0034]

[0035] Wherein, α1 and α2 represent the thermal expansion coefficients of the first and second layers of the double-layer film, respectively.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The invention provides a MEMS double-layer film thermal expansion coefficient measuring device, comprising: a thermal actuator structure, a displacement measuring structure, a double-layer gate structure and a compensation structure; the invention provides a MEMS double-layer film thermal expansion coefficient measuring method, based on the measuring device, the thermal actuator structure is first heated to obtain a horizontal displacement value s1, and the average temperature change ΔT1 before and after the thermal actuator is heated is obtained; then the double-layer gate structure is heated to obtain the average temperature change ΔT2 before and after the double-layer gate structure is heated; while the double-layer gate structure is heated, the thermal actuator structure is heated again to obtain a horizontal displacement value s2; the thermal expansion coefficient of the double-layer film is calculated based on the geometric dimensions of the measuring device, Young's moduli E1 and E2 of the double-layer film, the average temperature change ΔT1 before and after the thermal actuator structure is heated, the average temperature change ΔT2 before and after the double-layer gate structure is heated, and the horizontal displacement values ​​s1 and s2; the MEMS double-layer film thermal expansion coefficient measuring device and the measuring method designed by the invention have the advantages of simple operation, low cost and fast measurement speed, and can be used for parameter monitoring of process lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The figure is a schematic structural diagram of a device for measuring thermal expansion coefficient of a MEMS double-layer film in one embodiment of the present invention;

[0039] Figure 2 Shown is a flow chart of a method for measuring thermal expansion coefficient of a MEMS double-layer film in one embodiment of the present invention;

[0040] In the figure: 201-208, Z-shaped hot arm; 201-1-208-1, first long beam; 201-2-208-2, short beam; 201-3-08-3, second long beam; 209, connecting beam; 210, first anchor area; 211, first metal electrode; 212, second metal electrode; 213, second anchor area; 214, third metal electrode; 215; fourth metal electrode; 301, moving tooth; 302, first fixed tooth; 303, second fixed tooth; 304, contact electrode; 101, first slender beam; 101-1, bottom layer of first slender beam; 1 01-2, top layer of the first slender beam; 102, second slender beam; 102-1, bottom layer of the second slender beam; 102-2, top layer of the second slender beam; 103, short wide beam; 104, third anchor region; 105, fifth metal electrode; 106, sixth metal electrode; 107, fourth anchor region; 108, seventh metal electrode; 109, eighth metal electrode; 401, fixed beam; 402, fifth anchor region; 403, ninth metal electrode; 404, tenth metal electrode; 405, sixth anchor region; 406, eleventh metal electrode; 407, twelfth metal electrode. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to those of ordinary skill in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may also include different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so that once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0043] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0044] Example 1

[0045] The embodiment of the present invention introduces a device for measuring the thermal expansion coefficient of a MEMS double-layer film. Figure 1 As shown, it includes: a thermal actuator structure, a displacement measurement structure connected to the thermal actuator structure, a double-layer door structure and a compensation structure;

[0046] The thermal actuator structure comprises: a connecting beam 209, a plurality of Z-shaped thermal arms 201-208 connected to both sides of the connecting beam 209, a first anchoring area 210, a second anchoring area 213, a first metal electrode 211 and a second metal electrode 212 arranged on the upper surface of the first anchoring area 210, and a third metal electrode 214 and a fourth metal electrode 215 arranged on the upper surface of the second anchoring area 213; the thermal actuator structure is symmetrically arranged with respect to the connecting beam 209; the first anchoring area 210 and the second anchoring area 213 are respectively arranged on both sides of the connecting beam 209, and connected to one end of the plurality of Z-shaped thermal arms 201-208 away from the connecting beam 209;

[0047] The displacement measurement structure includes: a moving tooth 301, a contact electrode 304, and a first fixed tooth 302 and a second fixed tooth 303 respectively arranged on both sides of the moving tooth 301; the contact electrode 304 is arranged at one end of the moving tooth 301;

[0048] The double-layer gate-shaped structure includes: a gate-shaped beam, a third anchoring area 104 and a fourth anchoring area 107 connected to the fixed end of the gate-shaped beam, a fifth metal electrode 105 and a sixth metal electrode 106 arranged on the upper surface of the third anchoring area 104, and a seventh metal electrode 108 and an eighth metal electrode 109 arranged on the upper surface of the fourth anchoring area 107;

[0049] The compensation structure includes: a clamped beam 401, a fifth anchor region 402 and a sixth anchor region 405 respectively connected to both ends of the clamped beam 401, a ninth metal electrode 403 and a tenth metal electrode 404 arranged on the upper surface of the fifth anchor region 402, and an eleventh metal electrode 406 and a twelfth metal electrode 407 arranged on the upper surface of the sixth anchor region 405;

[0050] The connecting beam 209 of the thermal actuator structure is connected to the end of the moving tooth 301 away from the contact electrode 304; there is a gap between the contact electrode 304 of the displacement measurement structure and the double-layer gate structure; the connecting beam 209, the moving tooth 301, the contact electrode 304 and the gate beam are all on the same horizontal axis.

[0051] Specifically, in this embodiment, the Z-shaped thermal arms 201 and 202 correspond to each other, the Z-shaped thermal arms 203 and 204 correspond to each other, the Z-shaped thermal arms 205 and 206 correspond to each other, and the Z-shaped thermal arms 207 and 208 correspond to each other, and the two corresponding Z-shaped thermal arms are arranged on both sides of the connecting beam 209; wherein the Z-shaped thermal arms 201, 203, 205, 207 are on the same side, and the Z-shaped thermal arms 202, 204, 206, 208 are on the same side; the entire thermal actuator structure is a symmetrical structure with the connecting beam 209 as the axis, and the Z-shaped thermal arms 201, 203, 205 and 207 are connected to the first anchor area 210 at one end away from the connecting beam 209, that is, the first long beams 201-1, 203-1, 205-1 and 207-1 of the Z-type thermal arms 201, 203, 205 and 207 are connected to the first anchor area 210; the ends of the Z-type thermal arms 202, 204, 206 and 208 are connected to the second anchor area 213 at one end away from the connecting beam 209, that is, the first long beams 202-1, 204-1, 206-1 and 208-1 of the Z-type thermal arms 202, 204, 206 and 208 are connected to the second anchor area 213.

[0052] Specifically, the first anchoring area 210, the first fixed tooth 302 and the third anchoring area 104 are all on one side of the same horizontal axis; the second anchoring area 213, the second fixed tooth 303 and the fourth anchoring area 107 are all on the other side of the same horizontal axis.

[0053] In this embodiment, there is no connection relationship between the displacement measurement structure and the double-layer gate-type structure. Before the sacrificial layer is released, the horizontal initial spacing between the displacement measurement structure and the double-layer gate-type structure is precisely set to a distance d, that is, the size of the gap between the contact electrode 304 and the gate-type beam is d; this spacing d is one of the key factors to ensure that the displacement measurement can be carried out accurately; wherein, the sacrificial layer is arranged between the measuring device and the substrate when the measuring device is manufactured.

[0054] In this embodiment, the resistance of the compensation structure is substantially equal to the resistance of the bottom layer of the gate structure;

[0055] In this embodiment, the movable tooth 301 includes a main beam, and a first comb tooth assembly and a second comb tooth assembly symmetrically connected on both sides of the main beam; one end of the main beam is connected to the connecting beam 209, and the other end is connected to the contact electrode 304; the first comb tooth assembly and the second comb tooth assembly each include m teeth, the width of the teeth is a, and the tooth spacing is b; specifically, Figure 1There are 9 teeth distributed on the upper and lower sides of the middle moving tooth 301, if m=9 as shown in the figure;

[0056] In this embodiment, the first fixed teeth 302 include a first base beam and a comb tooth assembly A; the comb tooth assembly A corresponds to the first comb tooth assembly, and the comb tooth assembly A and the first comb tooth assembly are on the same side of the first base beam; the comb tooth assembly A includes m fixed teeth A evenly distributed on the first base beam; the second fixed teeth 303 include a second base beam and a comb tooth assembly B; the comb tooth assembly B corresponds to the second comb tooth assembly, and the comb tooth assembly B and the second comb tooth assembly are on the same side of the second base beam; the comb tooth assembly B includes m fixed teeth B evenly distributed on the second base beam;

[0057] Specifically, anchor regions are provided on the first fixed tooth 302 and the second fixed tooth 303 for fixing the first fixed tooth 302 and the second fixed tooth 303 on the substrate.

[0058] Specifically, in Figure 1 The first fixed teeth 302 are located above the moving teeth 301, and the second fixed teeth 303 are located below the moving teeth 301, and 9 fixed teeth A and 9 fixed teeth B are respectively provided on the first fixed teeth 302 and the second fixed teeth 303;

[0059] Specifically, the width of the fixed teeth A and the fixed teeth B are both a, and the tooth spacing is b+Δ, which refers to the spacing distance between the fixed teeth A and the spacing distance between the fixed teeth B.

[0060] Specifically, in the initial state of the measuring device, the comb tooth assembly A is offset to the right by Δ compared to the first comb tooth assembly of the movable tooth 301, and the comb tooth assembly B is offset to the right by (m+1)Δ compared to the second comb tooth assembly of the movable tooth 301; wherein the right direction is the direction of the double-layer door structure.

[0061] In this embodiment, in the thermal actuator structure, the Z-shaped thermal arms 201-208 each include: a first long beam 201-1 to 208-1, a second long beam 201-3 to 208-3, and a short beam 201-21 to 208-2 connecting the first long beam 201-1 to 208-1 and the second long beam 201-3 to 208-3; one end of the first long beam 201-1 to 208-1 away from the short beam 201-2 to 208-2 is connected to the first anchor area 210 or the second anchor area 213; one end of the second long beam 201-3 to 208-3 away from the short beam 201-2 to 208-2 is connected to the connecting beam 209;

[0062] The lengths of the first long beams 201-1 to 208-1 and the second long beams 201-3 to 208-3 are both L3 and w3, and the lengths of the short beams 201-2 to 208-2 are L4 and w3;

[0063] In the first anchor region 210 , the first metal electrode 211 and the second metal electrode 212 are arranged along a length direction perpendicular to the connecting beam 209 , and the second metal electrode 212 is located closer to the connecting beam 209 than the first metal electrode 211 ;

[0064] In the second anchor region 213 , the third metal electrode 214 and the fourth metal electrode 215 are arranged along a length direction perpendicular to the connecting beam 209 , and the third metal electrode 214 is located closer to the connecting beam 209 than the fourth metal electrode 215 ;

[0065] Specifically, the two metal electrodes in the first anchor region 210 are not connected to each other, and the two metal electrodes in the second anchor region 213 are not connected to each other; the first metal electrode 211 and the fourth metal electrode 215 are located on the outside of the thermal actuator structure, and the second metal electrode 212 and the third metal electrode 214 are located on the inside of the thermal actuator structure.

[0066] In this embodiment, in the double-layer door-shaped structure, the door-shaped beam includes: a first slender beam 101 and a second slender beam 102 arranged in parallel with each other, and a short wide beam 103 connecting the first slender beam 101 and the second slender beam 102; the length of the first slender beam 101 and the second slender beam 102 are both L1, and both are composed of a double-layer film, the width and thickness of the first layer of film, i.e., the first slender beam bottom layer 101-1 or the second slender beam bottom layer 102-1 are w1 and h1 respectively, and the width and thickness of the second layer of film, i.e., the first slender beam top layer 101-2 or the second slender beam top layer 102-2 are w2 and h2 respectively; the short wide beam 103 is composed of a single-layer film, the length and width of the single-layer film are both L2, and the thickness is h1; wherein, L1 L2, L2 w1 ,L2 w2; the width of each layer of the double-layer film and the single-layer film is less than 5 times the thickness of the layer;

[0067] One end of the first slender beam 101 away from the short and wide beam 103 is connected to the third anchoring area 104, and one end of the second slender beam 102 away from the short and wide beam 103 is connected to the fourth anchoring area 107;

[0068] In the third anchor region 104 , the fifth metal electrode 105 and the sixth metal electrode 106 are arranged along a length direction perpendicular to the first elongated beam 101 , and the sixth metal electrode 106 is located closer to the first elongated beam 101 than the fifth metal electrode 105 ;

[0069] In the fourth anchor region 107 , the seventh metal electrode 108 and the eighth metal electrode 109 are disposed along a length direction perpendicular to the second elongated beam 102 , and the seventh metal electrode 108 is located closer to the second elongated beam 102 than the eighth metal electrode 109 .

[0070] Specifically, the two metal electrodes in the third anchor area 104 are not connected to each other, and the two metal electrodes in the fourth anchor area 107 are not connected to each other; the fifth metal electrode 105 and the eighth metal electrode 109 are located on the outside of the double-layer gate structure, and the sixth metal electrode 106 and the seventh metal electrode 108 are located on the inside of the double-layer gate structure.

[0071] In this embodiment, in the compensation structure, the length of the clamping beam 401 is 2L1 and the width is w1; in the fifth anchor area 402, the ninth metal electrode 403 and the tenth metal electrode 404 are arranged along the length direction of the clamping beam 401, and the position of the tenth metal electrode 404 is closer to the clamping beam 401 than the ninth metal electrode 403; in the sixth anchor area 405, the eleventh metal electrode 406 and the twelfth metal electrode 407 are arranged along the length direction of the clamping beam 401, and the position of the eleventh metal electrode 406 is closer to the clamping beam 401 than the twelfth metal electrode 407.

[0072] Specifically, the two metal electrodes in the fifth anchor region 402 are not connected to each other, and the two metal electrodes in the sixth anchor region 405 are not connected to each other; the ninth metal electrode 403 and the twelfth metal electrode 407 are located outside the compensation structure, and the tenth metal electrode 404 and the eleventh metal electrode 406 are located inside the compensation structure.

[0073] In this embodiment, the materials of the connecting beam 209, the multiple Z-shaped hot arms 201-208, the displacement measurement structure (moving tooth 301, the first fixed tooth 302, the second fixed tooth 302 and the contact electrode 304), the clamped beam 401, the first film of the double-layer film, and the short and wide beam 103 are all polycrystalline silicon. Specifically, the thickness of the contact electrode is h1, and the width is L2+2w1.

[0074] Example 2

[0075] Based on the measuring device described in Example 1, the present invention introduces a method for measuring the thermal expansion coefficient of a MEMS double-layer film, including:

[0076] S01: Obtain the resistance R between the second metal electrode and the third metal electrode at room temperature 10 , the resistance R between the sixth metal electrode and the seventh metal electrode 20 , and the resistance R between the tenth metal electrode and the eleventh metal electrode 30 ;

[0077] Wherein, in step S01, the resistance between the metal electrodes is measured and obtained by a four-probe method;

[0078] S02: Perform the first electrical heating on the thermal actuator structure. When the contact electrode comes into contact with the double-layer gate structure, obtain the horizontal displacement value s1 displayed by the displacement measurement structure, and measure the resistance R between the second metal electrode and the third metal electrode at the same time. 11 ;

[0079] The thermal actuator structure is electrically heated for the first time by applying a slowly increasing scanning current I1 between the first metal electrode and the fourth metal electrode; the resistance R between the second metal electrode and the third metal electrode 11 The measurement is obtained by the four-probe method; specifically, after the thermal actuator structure is electrically heated for the first time, the thermal actuator structure pushes the movable tooth and the contact electrode to move toward the double-layer door structure, and the resistance between the second metal electrode and the sixth metal electrode is monitored in real time. When the contact electrode contacts the double-layer door structure, the monitored resistance suddenly changes from infinity to a finite value, and the horizontal displacement value s1 displayed by the displacement measurement structure is read at this time;

[0080] S03: Based on the obtained resistance R 11 and R 10 , the average temperature change ΔT1 of the thermal actuator structure before and after the first heating is obtained;

[0081] Among them, the resistor R 11 and R 10 The relationship between the size and temperature can be expressed as:

[0082]

[0083] in, is the linear resistance temperature coefficient of polysilicon material. According to existing research, the temperature coefficient of resistance can be obtained by measurement. Treat it as a known quantity. 11 and R 10 Substituting into the formula, we can get the average temperature change ΔT1 of the thermal actuator structure before and after the first heating:

[0084]

[0085] S04: heating the double-layer door-shaped structure, and obtaining the resistance R between the sixth metal electrode and the seventh metal electrode after the double-layer door-shaped structure is heated 21 ;

[0086] The double-layer gate structure is heated by applying a constant current I2 between the fifth metal electrode and the eighth metal electrode; the resistance R between the sixth metal electrode and the seventh metal electrode 21 Acquired by four-probe measurement;

[0087] S05: Based on the obtained resistance R 21 , R 30 and R 20 , the average temperature change ΔT2 of the double-layer door structure before and after heating is obtained;

[0088] Among them, the resistor R 20 and R 21 It can be expressed as:

[0089]

[0090]

[0091] Among them, R a0 and R b0 are the resistance of the first and second layers of the portal beam at room temperature, R a1 and R b1 are the resistances of the first and second layers of the heated rear door beam, is the linear resistance temperature coefficient of the second layer material of the gate beam. According to existing research, the temperature coefficient of resistance can be obtained by measurement. Treat as a known quantity.

[0092] From the root-finding formula of the quadratic equation we can get:

[0093]

[0094] in,

[0095]

[0096]

[0097]

[0098] Since the length of the two slender beams is much greater than that of the short wide beam, the width of the short wide beam is the same as its length and greater than that of the slender beam. Compared with the two slender beams, the resistance of the short wide beam and the resistance change before and after heating can be ignored, that is, only the resistance of the two slender beams is considered. The length of the fixed beam in the compensation structure is equal to the sum of the two slender beams, and the width is equal to the bottom width of the slender beam. Therefore

[0099]

[0100] Substitute into R 20 In the formula, we can calculate

[0101]

[0102] S06: on the basis of heating the double-layer door-type structure, electrically heating the thermal actuator structure for a second time, and when the contact electrode comes into contact with the double-layer door-type structure, obtaining the horizontal displacement value s2 displayed by the displacement measurement structure at this time;

[0103] Wherein, by applying a slowly increasing scanning current I3 between the first metal electrode and the fourth metal electrode, the thermal actuator structure is electrically heated for the second time; specifically, after the thermal actuator structure is electrically heated for the second time, the thermal actuator structure pushes the movable tooth and the contact electrode to move toward the double-layer gate structure, and the resistance between the second metal electrode and the sixth metal electrode is monitored in real time. When the contact electrode contacts the double-layer gate structure, the monitored resistance suddenly changes from infinity to a finite value, and the horizontal displacement value s2 displayed by the displacement measurement structure at this time is read;

[0104] S07: Calculate the thermal expansion coefficients α1 and α2 of the double-layer film based on the geometric dimensions of the measuring device, the Young's modulus E1 and E2 of the double-layer film, the average temperature change ΔT1 of the thermal actuator structure before and after heating, the average temperature change ΔT2 of the double-layer door structure before and after heating, and the horizontal displacement values ​​s1 and s2;

[0105] Specifically, the formulas for the thermal expansion coefficients α1 and α2 of the double-layer film are as follows:

[0106]

[0107]

[0108] Wherein, α1 and α2 represent the thermal expansion coefficients of the first and second layers of the double-layer film, respectively.

[0109] Specifically, for ease of understanding, the theoretical principle of the measurement method proposed in the present invention is explained:

[0110] For the thermal actuator structure proposed in the present invention, according to the energy method, the following equations can be obtained:

[0111]

[0112] Among them, F is the axial force, P is the virtual force, and M is the moment;

[0113]

[0114] Where A is the cross-sectional area of ​​the Z-shaped thermal arm 201-208; E is the Young's modulus of the Z-shaped thermal arm, which is equal to the Young's modulus E1 of the first film; I is the moment of inertia of the Z-shaped thermal arm 201-208. When the virtual force P is set to zero, the horizontal displacement U of the thermal actuator can be obtained:

[0115]

[0116] For the double-layer door-type structure, the first slender beam 101 and the second slender beam 102 have the same size and are symmetrically distributed, so one of the slender beams can be equivalently modeled. Taking the first slender beam 101 as an example, it is essentially a double-layer cantilever beam, and the distance z between the neutral plane and the lower surface of the beam is c It can be expressed as:

[0117]

[0118] Under the action of the intrinsic stress difference, the double-layer beam bends, and its equivalent bending stiffness is It can be calculated using the following formula:

[0119]

[0120] in, are the cross-sectional inertia moments of the first and second layers of the double-layer film, , Ai is the cross-sectional area of ​​the i-th film, z represents the distance between a certain point on the film cross section and the lower surface of the beam;

[0121] The bending moment acting on the double-layer beam is:

[0122]

[0123] Here, Δε is the intrinsic strain difference of the bilayer film.

[0124] The radius of curvature r1 of the beam bending is given by:

[0125]

[0126] Substituting formula (5) and formula (6) into formula (7), we can obtain:

[0127]

[0128] When the double-layer beam is heated, the bending degree of the beam will change under the action of the temperature change ΔT2, so the curvature radius r2 of the heated beam can be expressed by the following formula:

[0129]

[0130] From formula (3), formula (8) and formula (9), we can get

[0131]

[0132] Based on the above principle, this embodiment provides a method for measuring the thermal expansion coefficient of a MEMS double-layer film. The specific measurement process is as follows:

[0133] (1) At room temperature, the resistance R between the second metal electrode 212 and the third metal electrode 214 is obtained based on the four-probe method. 10 , the resistance R between the sixth metal electrode 106 and the seventh metal electrode 108 20 , and the resistance R between the tenth metal electrode 404 and the eleventh metal electrode 406 30 ;

[0134] (2) A slowly increasing scanning current I1 is applied between the first metal electrode 211 and the fourth metal electrode 215 to electrically heat the thermal actuator structure, so that the thermal actuator structure pushes the movable tooth 301 and the contact electrode 304 to move in the direction of the double-layer gate structure; at the same time, the resistance between the second metal electrode 212 and the sixth metal electrode 106 is monitored. When the contact electrode 304 contacts the double-layer gate structure, the monitored resistance suddenly changes from infinity to a finite value, and the horizontal displacement value s1 displayed by the displacement measurement structure at this time is read;

[0135] Specifically, if at this time the first tooth of the first comb tooth assembly in the movable tooth 301 from left to right is aligned with the first fixed tooth A from left to right of the comb tooth assembly A in the first fixed tooth 302, then s1=Δ, if at this time the second tooth of the first comb tooth assembly in the movable tooth 301 from left to right is aligned with the second fixed tooth A from left to right of the comb tooth assembly A in the first fixed tooth 302, then s1=2Δ, and so on, if at this time the mth tooth of the first comb tooth assembly in the movable tooth 301 from left to right is aligned with the mth fixed tooth A from left to right of the comb tooth assembly A in the first fixed tooth 302, then s1=mΔ; similarly, if at this time the first tooth of the second comb tooth assembly from left to right is aligned with the first fixed tooth B from left to right of the comb tooth assembly B in the second fixed tooth 303, then s1=(m+1)Δ, if at this time the second tooth of the second comb tooth assembly from left to right is aligned with the second fixed tooth B from left to right of the comb tooth assembly B in the second fixed tooth 303, then s1=(m+2)Δ , and so on, if at this time the mth tooth from left to right of the second comb tooth assembly is aligned with the mth fixed tooth B from left to right of the comb tooth assembly B in the second fixed tooth 303, then s1=2mΔ.

[0136] (3) Obtaining the resistance R between the second metal electrode 212 and the third metal electrode 214 when the contact electrode 304 contacts the double-layer gate structure based on the four-probe method 11 , and based on the obtained resistance R 11 and R 10 , the average temperature change ΔT1 of the thermal actuator structure before and after heating is obtained;

[0137] (4) A constant current I2 is applied between the fifth metal electrode 105 and the eighth metal electrode 109 to heat the double-layer gate-shaped structure. Due to the different thermal expansion coefficients of the double-layer films in the gate-shaped beam, the bending degree of the gate-shaped beam changes. At this time, the resistance R between the sixth metal electrode 106 and the seventh metal electrode 108 after the double-layer gate-shaped structure is heated is obtained. 21 , based on the obtained resistance R 21 , R 30 and R 20 , the average temperature change ΔT2 of the double-layer door structure before and after heating is obtained;

[0138] (5) On the basis of heating the double-layer gate structure, a slowly increasing scanning current I3 is applied between the first metal electrode 211 and the fourth metal electrode 215 to electrically heat the thermal actuator structure, so that the thermal actuator structure pushes the movable tooth 301 and the contact electrode 304 to move in the direction of the double-layer gate structure; at the same time, the resistance between the second metal electrode 212 and the sixth metal electrode 106 is monitored. When the contact electrode 304 contacts the double-layer gate structure, the monitored resistance suddenly changes from infinity to a finite value, and the horizontal displacement value s2 displayed by the displacement measurement structure at this time is read;

[0139] Specifically, if at this time the first tooth from left to right of the first comb tooth assembly in the movable tooth 301 is aligned with the first fixed tooth A from left to right of the comb tooth assembly A in the first fixed tooth 302, then s2=Δ, if at this time the second tooth from left to right of the first comb tooth assembly in the movable tooth 301 is aligned with the second fixed tooth A from left to right of the comb tooth assembly A in the first fixed tooth 302, then s2=2Δ, and so on, if at this time the mth tooth from left to right of the first comb tooth assembly in the movable tooth 301 is aligned with the mth fixed tooth A from left to right of the comb tooth assembly A in the first fixed tooth 302, then s2=mΔ; similarly, if at this time the first tooth from left to right of the second comb tooth assembly is aligned with the first fixed tooth B from left to right of the comb tooth assembly B in the second fixed tooth 303, then s2=(m+1)Δ, if at this time the second tooth from left to right of the second comb tooth assembly is aligned with the second fixed tooth B from left to right of the comb tooth assembly B in the second fixed tooth 303, then s2=(m+2)Δ , and so on, if at this time the mth tooth from left to right of the second comb tooth assembly is aligned with the mth fixed tooth B from left to right of the comb tooth assembly B in the second fixed tooth 303, then s2=2mΔ.

[0140] (6) Assuming that when the thermal actuator is electrically heated for the first time and the second time, the arc lengths of the contact points where the first slender beam 101 and the second slender beam 102 contact the contact electrode 304 are l1 and l2 respectively, according to the geometric relationship after the beam structure is bent, it can be obtained:

[0141]

[0142] Solving formula (12) and formula (13), we can get the radius of curvature:

[0143]

[0144] Substituting formula (10) and formula (14) into formula (11), we can obtain:

[0145]

[0146] Therefore, based on the geometric dimensions of the measuring device, the Young's modulus E1 and E2 of the double-layer film, the average temperature change ΔT1 of the thermal actuator structure before and after heating, the average temperature change ΔT2 of the double-layer gate structure before and after heating, and the measured displacements s1 and s2, the thermal expansion coefficient of the double-layer film is calculated by formula (10) and formula (15).

[0147] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which all fall within the protection of the present invention.

Claims

1. A MEMS double-layer film thermal expansion coefficient measuring device, characterized in that: include: A thermal actuator structure, a displacement measuring structure connected to the thermal actuator structure, a double-layer door type structure and a compensation structure; The thermal actuator structure comprises: a connecting beam, a plurality of Z-shaped thermal arms connected to both sides of the connecting beam, a first anchoring area, a second anchoring area, a first metal electrode and a second metal electrode arranged on the upper surface of the first anchoring area, and a third metal electrode and a fourth metal electrode arranged on the upper surface of the second anchoring area; the thermal actuator structure is symmetrically arranged with respect to the connecting beam; the first anchoring area and the second anchoring area are respectively arranged on both sides of the connecting beam, and are connected to one end of the plurality of Z-shaped thermal arms away from the connecting beam; The displacement measurement structure comprises: a moving tooth, a contact electrode, and a first fixed tooth and a second fixed tooth respectively arranged on both sides of the moving tooth; the contact electrode is arranged at one end of the moving tooth; The double-layer gate-shaped structure comprises: a gate-shaped beam, a third anchoring area and a fourth anchoring area connected to the fixed support end of the gate-shaped beam, a fifth metal electrode and a sixth metal electrode arranged on the upper surface of the third anchoring area, and a seventh metal electrode and an eighth metal electrode arranged on the upper surface of the fourth anchoring area; The compensation structure includes: a fixed support beam, a fifth anchor region and a sixth anchor region respectively connected to both ends of the fixed support beam, a ninth metal electrode and a tenth metal electrode arranged on the upper surface of the fifth anchor region, and an eleventh metal electrode and a twelfth metal electrode arranged on the upper surface of the sixth anchor region; The connecting beam of the thermal actuator structure is connected to the end of the moving tooth away from the contact electrode; there is a gap between the contact electrode of the displacement measurement structure and the double-layer gate structure; the connecting beam, moving tooth, contact electrode and gate beam are all on the same horizontal axis.

2. The device for measuring thermal expansion coefficient of a MEMS double-layer film according to claim 1, characterized in that: Before the sacrificial layer is released, the horizontal initial spacing between the displacement measuring structure and the double-layer gate structure is d; wherein the sacrificial layer is arranged between the measuring device and the substrate when the measuring device is manufactured.

3. The device for measuring thermal expansion coefficient of a MEMS double-layer film according to claim 2, characterized in that: In the displacement measurement structure, the movable teeth include a main beam, and a first comb tooth assembly and a second comb tooth assembly symmetrically connected on both sides of the main beam; one end of the main beam is connected to the connecting beam, and the other end is connected to the contact electrode; the first comb tooth assembly and the second comb tooth assembly each include m teeth, the width of the teeth is a, and the tooth spacing is b; wherein the thickness of the contact electrode is h1, and the width is consistent with the width of the gate beam; The first fixed teeth include a first base beam and a comb tooth assembly A; the comb tooth assembly A corresponds to the first comb tooth assembly, and includes m fixed teeth A evenly distributed on the first base beam; the second fixed teeth include a second base beam and a comb tooth assembly B; the comb tooth assembly B corresponds to the second comb tooth assembly, and includes m fixed teeth B evenly distributed on the second base beam.

4. The device for measuring thermal expansion coefficient of a MEMS double-layer film according to claim 3, characterized in that: The widths of the fixed teeth A and B are both a, and the tooth spacings are both b+Δ.

5. The device for measuring thermal expansion coefficient of a MEMS double-layer film according to claim 4, characterized in that: In the initial state of the measuring device, the comb tooth assembly A is offset to the right by Δ compared to the first comb tooth assembly of the movable teeth, and the comb tooth assembly B is offset to the right by (m+1)Δ compared to the second comb tooth assembly of the movable teeth; wherein the right direction is the direction of the double-layer door structure.

6. The device for measuring thermal expansion coefficient of a MEMS double-layer film according to claim 5, characterized in that: In the thermal actuator structure, the Z-shaped thermal arm includes: a first long beam, a second long beam, and a short beam connecting the first long beam and the second long beam; an end of the first long beam away from the short beam is connected to the first anchor area or the second anchor area; an end of the second long beam away from the short beam is connected to the connecting beam; wherein the length of the first long beam and the second long beam are both L3, and the width is both w3, and the length of the short beam is L4, and the width is w3; In the first anchor region, the first metal electrode and the second metal electrode are arranged along a length direction perpendicular to the connecting beam, and the second metal electrode is located closer to the connecting beam than the first metal electrode; In the second anchor region, the third metal electrode and the fourth metal electrode are arranged along a length direction perpendicular to the connecting beam, and the third metal electrode is located closer to the connecting beam than the fourth metal electrode.

7. The device for measuring thermal expansion coefficient of a MEMS double-layer film according to claim 6, characterized in that: In the double-layer door-shaped structure, the door-shaped beam includes: a first slender beam and a second slender beam arranged in parallel with each other, and a short wide beam connecting the first slender beam and the second slender beam; the length of the first slender beam and the second slender beam are both L1, and both are composed of a double-layer film, the width and thickness of the first film are w1 and h1 respectively, and the width and thickness of the second film are w2 and h2 respectively; the short wide beam is composed of a single-layer film, the length and width of the single-layer film are both L2, and the thickness is h1; wherein L1 L2, L2 w1 ,L2 w2; the width of each layer of the double-layer film and the single-layer film is less than 5 times the thickness of the layer; One end of the first slender beam away from the short and wide beam is connected to the third anchor area, and one end of the second slender beam away from the short and wide beam is connected to the fourth anchor area; In the third anchor region, the fifth metal electrode and the sixth metal electrode are arranged along a length direction perpendicular to the first elongated beam, and the sixth metal electrode is located closer to the first elongated beam than the fifth metal electrode; In the fourth anchor region, the seventh metal electrode and the eighth metal electrode are arranged along a length direction perpendicular to the second elongated beam, and the seventh metal electrode is located closer to the first elongated beam than the eighth metal electrode.

8. The device for measuring thermal expansion coefficient of a MEMS double-layer film according to claim 7, characterized in that: In the compensation structure, the length of the fixed beam is 2L1 and the width is w1; in the fifth anchor zone, the ninth metal electrode and the tenth metal electrode are arranged along the length direction of the fixed beam, and the position of the tenth metal electrode is closer to the fixed beam than the ninth metal electrode; in the sixth anchor zone, the eleventh metal electrode and the twelfth metal electrode are arranged along the length direction of the fixed beam, and the position of the eleventh metal electrode is closer to the fixed beam than the twelfth metal electrode.

9. The device for measuring thermal expansion coefficient of a MEMS double-layer film according to claim 8, characterized in that: The connecting beam, the multiple Z-shaped thermal arms, the displacement measurement structure, the fixed support beam, the first film of the double-layer film, and the short and wide beam are all made of polycrystalline silicon.

10. A method for measuring the thermal expansion coefficient of a MEMS double-layer film using the measuring device of claim 9, characterized in that: include: Obtain the resistance R between the second metal electrode and the third metal electrode at room temperature respectively 10 , the resistance R between the sixth metal electrode and the seventh metal electrode 20 , and the resistance R between the tenth metal electrode and the eleventh metal electrode 30 ; The thermal actuator structure is electrically heated for the first time. When the contact electrode contacts the double-layer gate structure, the horizontal displacement value s1 displayed by the displacement measurement structure is obtained, and the resistance R between the second metal electrode and the third metal electrode is measured at the same time. 11 ; Based on the obtained resistance R 11 and R 10 , the average temperature change ΔT1 of the thermal actuator structure before and after the first heating is obtained; The double-layer door-shaped structure is heated, and the resistance R between the sixth metal electrode and the seventh metal electrode of the double-layer door-shaped structure after heating is obtained. 21 ; Based on the obtained resistance R 21 , R 30 and R 20 , the average temperature change ΔT2 of the double-layer door structure before and after heating is obtained; On the basis of heating the double-layer door-type structure, the thermal actuator structure is electrically heated for a second time, and when the contact electrode comes into contact with the double-layer door-type structure, a horizontal displacement value s2 displayed by the displacement measurement structure at this time is obtained; Based on the geometric dimensions of the measuring device, the Young's modulus E1 and E2 of the double-layer film, the average temperature change ΔT1 of the thermal actuator structure before and after heating, the average temperature change ΔT2 of the double-layer door structure before and after heating, and the horizontal displacement values ​​s1 and s2, the thermal expansion coefficient of the double-layer film is calculated. and , the formula is as follows: ； ； in, and Respectively represent the thermal expansion coefficients of the first and second layers of the double-layer film.

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