A piezoelectric device

Abstract

The present invention provides a piezoelectric device, which relates to the field of semiconductor technology and includes: a substrate and a cantilever beam laminated on the substrate. The substrate forms a cavity, and the cantilever beam is divided into a fixed end located on the substrate and a free end located on the cavity. The cantilever beam includes a piezoelectric layer laminated on the substrate and at least one first metal layer. The piezoelectric layer extends onto the substrate and the cavity. The first metal layer is at least suspended at the free end above the cavity and away from the fixed end. In the extending direction from the free end to the fixed end, a preset distance is formed between the first end face of the fixed end facing the cavity and the second end face of the first metal layer facing the fixed end. By adjusting the relative position of the first metal layer on the cantilever beam and the fixed end, part of the stress is transferred to the first metal layer, thereby reducing the stress of the piezoelectric layer and improving the anti-cracking ability of the cantilever beam.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a piezoelectric device. Background Art

[0002] MEMS (Micro-Electro-Mechanical System, also known as microelectronic mechanical system) piezoelectric devices, as an advanced sensor technology, mainly consist of a piezoelectric unit and an ASIC circuit (Application-Specific Integrated Circuit). The main structure of the piezoelectric unit generally includes a cantilever beam or a diaphragm. Due to the material properties of the piezoelectric material, when the cantilever beam is driven (externally driven or self-driven) to vibrate, the cantilever beam will deform along the Figure 1 direction of the arrow in the figure, thus undergoing cyclic changes of compression and tension.

[0003] When the cantilever beam / diaphragm undergoes large strains, it is prone to fracture in the root region, and this fracture phenomenon has a serious impact on the application scenarios and service life of the product. Figure 2a shows the situation where the cantilever beam fractures during the reliability shock test, Figure 2b is a schematic model diagram of the fracture of the cantilever beam of the MEMS piezoelectric device. The fracture generally occurs in the root region, and part of the cantilever beam may remain at the fixed end, as shown in Figure 2a , Figure 2b the position selected by the dashed box. When 100 samples are selected for the reliability shock test, only 27 devices can pass the test, that is, the qualified rate is only 27%. Therefore, under the existing process capabilities, it is urgent to improve the reliability of the device and increase the yield rate through some improvements. Summary of the Invention

[0004] The purpose of the present invention is to provide a piezoelectric device that can improve the reliability and yield rate of the device.

[0005] On the one hand, the present invention provides a piezoelectric device, including a substrate and a cantilever beam stacked on the substrate. The substrate forms a cavity, and the cantilever beam is divided into a fixed end located on the substrate and a free end located on the cavity;

[0006] The cantilever beam includes a piezoelectric layer stacked on the substrate and at least one first metal layer. The piezoelectric layer extends onto the substrate and the cavity, and the first metal layer is at least suspended above the cavity at the free end and away from the fixed end. In the extending direction from the free end to the fixed end, a preset distance is formed between the first end face of the fixed end facing the cavity and the second end face of the first metal layer facing the fixed end.

[0007] Optionally, the second end face of the first metal layer extends into the fixed end, and the preset distance between the first end face and the second end face is greater than zero;

[0008] Alternatively, the second end face of the first metal layer extends to the first end face of the fixed end, and the preset distance between the first end face and the second end face is equal to zero;

[0009] Alternatively, the first metal layer is located at the free end, and the second end face of the first metal layer does not extend to the first end face of the fixed end, and it is defined that the preset distance between the first end face and the second end face is less than zero.

[0010] Optionally, when the preset distance from the first end face to the second end face is less than zero, the preset distance ≥ -25um;

[0011] When the preset distance between the first end face and the second end face is greater than zero, the preset distance ≥ 25um.

[0012] Optionally, at least one layer of the first metal layer is disposed below the piezoelectric layer, and / or at least one layer of the first metal layer is disposed above the piezoelectric layer, and / or at least one layer of the first metal layer is disposed within the piezoelectric layer.

[0013] Optionally, when the preset distance from the first end face of the first metal layer to the second end face of the fixed end is less than zero, the cantilever beam further includes at least one layer of a second metal layer stacked on the substrate, and at least one layer of the second metal layer is close to the fixed end and extends toward the first metal layer.

[0014] Optionally, the second metal layer is located within the fixed end, or the second metal layer is located within the free end, or the second metal layer extends from the fixed end to the free end.

[0015] Optionally, the projection of the second metal layer and the first metal layer in the stacking direction do not overlap, or the projection of the second metal layer and the first metal layer in the stacking direction overlaps.

[0016] Optionally, at least one layer of the second metal layer is disposed below the piezoelectric layer, and / or at least one layer of the second metal layer is disposed above the piezoelectric layer, and / or at least one layer of the second metal layer is disposed within the piezoelectric layer.

[0017] Optionally, an oxide layer is further disposed on the substrate corresponding to the fixed end, and the piezoelectric layer and the first metal layer are both located on the oxide layer.

[0018] Optionally, the cantilever beam further includes at least one functional film layer, and at least one of the functional film layers is disposed below the piezoelectric layer, and / or at least one of the functional film layers is disposed above the piezoelectric layer, and / or at least one of the functional film layers is disposed within the piezoelectric layer.

[0019] In the piezoelectric device provided by the present invention, a preset distance is formed between the first end face of the fixed end and the second end face of the first metal layer. By adjusting the relative positional relationship between the first metal layer in the cantilever beam and the root of the fixed end of the cantilever beam (the first end face of the fixed end), the first metal layer with stronger tensile strength is used to replace the piezoelectric material to bear part of the stress, and part of the stress is transferred to the first metal layer, thereby improving the anti-cracking ability of the cantilever beam. The principle is to disperse the stress generated when the piezoelectric device undergoes strain, so that the first metal layer bears most of the stress, thereby reducing the stress of the piezoelectric layer. And because the tensile strength of the metal material is high and it is not easy to crack, the anti-cracking ability of the root of the cantilever beam is enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the present invention, the drawings required for the present invention will be briefly introduced below. It should be understood that the following drawings only show some examples of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0021] Figure 1 is a schematic diagram of the force deformation of the cantilever beam of the MEMS piezoelectric device;

[0022] Figure 2a is a schematic diagram of the fracture of the cantilever beam of the MEMS piezoelectric device;

[0023] Figure 2b is a schematic model diagram of the fracture of the cantilever beam of the MEMS piezoelectric device;

[0024] Figure 3 is a schematic diagram of the wurtzite crystal structure of AlN;

[0025] Figure 4 is a schematic diagram of the chemical bond between aluminum and nitrogen atoms;

[0026] Figure 5 is a top view of the AlN crystal structure;

[0027] Figure 6 is a schematic diagram of the fracture of the cantilever beam of the MEMS piezoelectric device due to stress concentration force;

[0028] Figure 7 is one of the schematic diagrams of the structure of the piezoelectric device provided by the present invention;

[0029] Figure 8It is the second schematic diagram of the piezoelectric device structure provided by the present invention;

[0030] Figure 9 It is the third schematic diagram of the piezoelectric device structure provided by the present invention;

[0031] Figure 10 It is Figure 7 、 Figure 8 、 Figure 9 The corresponding stress distribution simulation diagram;

[0032] Figure 11 It is Figure 7 、 Figure 8 、 Figure 9 The corresponding maximum tensile stress distribution curve graph;

[0033] Figure 12 It is Figure 7 、 Figure 8 、 Figure 9 The first influence trend graph of stress;

[0034] Figure 13 It is Figure 7 、 Figure 8 、 Figure 9 The second influence trend graph of stress;

[0035] Figure 14 It is the cross-sectional view of the surface topography of the piezoelectric device provided by the present invention;

[0036] Figure 15 It is the schematic diagram of the rugged surface structure design of the piezoelectric device provided by the present invention;

[0037] Figure 16 It is the schematic diagram of the stress distribution on the rugged surface of the piezoelectric device provided by the present invention;

[0038] Figure 17 It is the normalized maximum tensile stress curve graph of the rugged surface and the flat surface of the piezoelectric device provided by the present invention;

[0039] Figure 18 It is the comparison graph of different coverage areas of the first metal layer of the piezoelectric device provided by the present invention;

[0040] Figure 19 It is the schematic diagram of the bending resistance and brittle fracture resistance model structure of the piezoelectric device provided by the present invention;

[0041] Figure 20 It is the schematic diagram of the surface topography characterization of the piezoelectric device provided by the present invention;

[0042] Figure 21 It is the fourth schematic diagram of the piezoelectric device structure provided by the present invention;

[0043] Figure 22It is the fifth schematic diagram of the piezoelectric device structure provided by the present invention;

[0044] Figure 23 It is the sixth schematic diagram of the piezoelectric device structure provided by the present invention;

[0045] Figure 24 It is the seventh schematic diagram of the piezoelectric device structure provided by the present invention;

[0046] Figure 25 It is the eighth schematic diagram of the piezoelectric device structure provided by the present invention;

[0047] Figure 26 It is the ninth schematic diagram of the piezoelectric device structure provided by the present invention;

[0048] Figure 27 It is the tenth schematic diagram of the piezoelectric device structure provided by the present invention;

[0049] Figure 28 It is the eleventh schematic diagram of the piezoelectric device structure provided by the present invention;

[0050] Figure 29 It is the twelfth schematic diagram of the piezoelectric device structure provided by the present invention;

[0051] Figure 30 It is the stress distribution diagram of the MEMS piezoelectric device;

[0052] Figure 31 It is the thirteenth schematic diagram of the piezoelectric device structure provided by the present invention;

[0053] Figure 32 It is the fourteenth schematic diagram of the piezoelectric device structure provided by the present invention;

[0054] Figure 33 It is the fifteenth schematic diagram of the piezoelectric device structure provided by the present invention;

[0055] Figure 34 It is the sixteenth schematic diagram of the piezoelectric device structure provided by the present invention;

[0056] Figure 35 It is the seventeenth schematic diagram of the piezoelectric device structure provided by the present invention;

[0057] Figure 36 It is the eighteenth schematic diagram of the piezoelectric device structure provided by the present invention;

[0058] Figure 37 It is the nineteenth schematic diagram of the piezoelectric device structure provided by the present invention;

[0059] Figure 38 It is the twentieth schematic diagram of the piezoelectric device structure provided by the present invention;

[0060] Figure 39It is the twenty-first schematic structural diagram of the piezoelectric device provided by the present invention;

[0061] Figure 40 It is the twenty-second schematic structural diagram of the piezoelectric device provided by the present invention;

[0062] Figure 41 It is the twenty-third schematic structural diagram of the piezoelectric device provided by the present invention.

[0063] Icons: 10 - Substrate; 11 - Cavity; 12 - Oxide layer; 13 - First metal layer; 14 - Piezoelectric layer; 15 - Second metal layer; 16 - Functional film layer; A - Stress concentration point; B1 - Fixed end; B2 - Free end; D - Preset distance; E1 - First end face; E2 - Second end face; F - Tensile stress; G - Corner area; S - Extension direction. Detailed implementation manners

[0064] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the accompanying drawings in the present invention.

[0065] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention. In addition, terms such as "first", "second", etc. are only used for differential description and cannot be understood as indicating or implying relative importance.

[0066] It should also be noted that unless otherwise clearly specified and limited, the terms "set", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0067] The crystal lattice of piezoelectric materials is generally a wurtzite crystal structure. For example, Figure 3 , Figure 4 As shown, taking the lattice structure of AlN (aluminum nitride) as an example, the crystal lattice structure of piezoelectric materials has no center of symmetry, and its finally formed crystal structure is as Figure 5 shown. Such crystals can be regarded as composed of multiple hexagonal prisms. Inside a hexagonal prism, the forces between atoms are very tight, but the forces between prisms are relatively weak.

[0068] When a piezoelectric material is subjected to a lateral tensile stress F, the crystal structure is prone to fracture along the interface between the two prisms. Macroscopically, it is manifested that the cantilever beam of the piezoelectric device is prone to brittle fracture in the direction perpendicular to the cantilever beam. As Figure 6 shown, brittle fracture may occur at the stress concentration point A.

[0069] Based on this, the present invention provides a piezoelectric device. Please refer to Figures 7 - 9 shown, which includes: a substrate 10 and a cantilever beam laminated on the substrate 10. The substrate 10 forms a cavity 11. The cantilever beam is divided into a fixed end B1 located on the substrate 10 and a free end B2 located on the cavity 11;

[0070] The cantilever beam includes a piezoelectric layer 14 laminated on the substrate 10 and at least one first metal layer 13. The piezoelectric layer 14 extends to the substrate 10 and the cavity 11. The first metal layer 13 is at least suspended above the cavity 11 at the free end B2 and is far from the fixed end B1. In the extension direction S from the free end B2 to the fixed end B1, a preset distance D is formed between the first end face E1 of the fixed end B1 facing the cavity 11 and the second end face E2 of the first metal layer 13 facing the fixed end B1.

[0071] A cantilever beam is formed on the substrate 10 with the cavity 11. The area of the cantilever beam located on the substrate 10 is called the fixed end B1, and the area located on the cavity 11 is called the free end B2.

[0072] Specifically, the cantilever beam includes a piezoelectric layer 14 and a first metal layer 13. The piezoelectric layer 14 covers both the substrate 10 and the cavity 11 at the same time. There is at least one first metal layer 13, and the first metal layer 13 is at least suspended above the cavity 11 at the free end B2 and is far from the fixed end B1. That is to say, the first metal layer 13 extends from the free end B2 towards the fixed end B1.

[0073] For example Figure 9 shown, the first metal layer 13 is located at the free end B2, and the second end face E2 of the first metal layer 13 facing the fixed end B1, that is, the left end of the first metal layer 13, has not extended to the first end face E1 of the fixed end B1 yet; at this time, it is defined that the preset distance D between the first end face E1 and the second end face E2 is less than zero because the defined extension direction S is from right to left, and the second end face E2 is on the right side of the first end face E1, making the preset distance D between the first end face E1 and the second end face E2 in the reverse direction of the extension direction S, that is, the direction is negative.

[0074] The second end face E2 of the first metal layer 13 continues to extend towards the first end face E1 of the fixed end B1 until it extends to be flush with the first end face E1, forming Figure 8 the structure shown. At this time, the preset distance D between the first end face E1 and the second end face E2 is zero.

[0075] The second end face E2 of the first metal layer 13 continues to extend along the extension direction S, extending beyond the first end face E1 of the fixed end B1 and into the interior of the fixed end B1, obtaining [[ID=6 the structure shown. At this time, the direction of the preset distance D between the first end face E1 and the second end face E2 is positive and greater than zero.

[0076] A preset distance D is formed between the first end face E1 of the fixed end B1 and the second end face E2 of the first metal layer 13. The numerical value of the preset distance D is different in ​ , that is, the relative position relationship between the first end face E1 of the fixed end B1 and the second end face E2 of the first metal layer 13 is different. By adjusting the relative position relationship between the first metal layer 13 in the cantilever beam and the root of the fixed end B1 of the cantilever beam (the first end face E1 of the fixed end B1), the first metal layer 13 with stronger tensile ability is used to replace the piezoelectric material to bear part of the stress, thereby improving the anti-cracking ability of the cantilever beam. The principle is to disperse the stress when the piezoelectric device undergoes strain, so that the first metal layer 13 bears most of the stress, and because the tensile strength of the metal material is high and it is not easy to crack, the anti-cracking ability of the root of the cantilever beam is enhanced.

[0077] ​ The stress distribution simulation images of the piezoelectric device after adopting ​ are shown successively from top to bottom. ​ In, the color bar represents the magnitude of the stress value, and the stress image shows the stress distribution through the light and dark shades of gray corresponding to different sections, where the uppermost section is the part with the maximum stress.

[0078] ​ The simulation results of

[0079] are obtained under the same driving conditions. Due to the symmetry of the cantilever beam bending, only the modeling of the first metal layer 13 located below the piezoelectric layer 14 and the simulation of the downward bending are carried out. ​ Corresponding to ​ , it can be seen from

[0080] that the corner region G of the fixed end B1 of the cantilever beam is the stress concentration region for the downward bending of the entire model. This corner region G is a relatively large range, not a single corner point. ​ The corresponding structure in ​ does not show the first metal layer 13 because after the local image is magnified, the first metal layer 13 corresponding to ​ cannot be displayed together within the limited image range, but it does not mean that the first metal layer 13 does not exist in the simulation image corresponding to ​ .

[0081] ​ shows ​The normalized stress performance of the piezoelectric device model, where the curve represents the trend of the maximum tensile stress in the piezoelectric layer 14 and the first metal layer 13 changing with time. Through comparison, it can be judged that ​ the stress distribution of the three types of models. Among them, ​ is Example 1, ​ is Example 2, ​ is Example 3, and the first metal layer 13 can use molybdenum as the material.

[0082] Among them, the AlN region (i.e., the piezoelectric layer 14) where the first metal layer 13 "shortens" (corresponding to ​ ) bears the maximum stress value, and the first metal layer 13 bears the minimum stress value. This is because in the region with the maximum strain, ​ the first metal layer 13 of the model has the least participation degree. The stress situation in the region with the maximum strain is equivalent to that when the first metal layer 13 is not added, and all are borne by AlN.

[0083] It can be seen from the change of the stress curve that as the length of the first metal layer 13 increases, the maximum stress value shared by the first metal layer 13 continuously increases, and the maximum stress value borne by AlN continuously decreases. In particular, ​ the maximum stress of the corresponding (extended) first metal layer 13 exceeds the maximum stress value of AlN.

[0084] Furthermore, ​ shows the influence trend of different lengths of the first metal layer 13 on stress. The AlN pressure is the pressure when the piezoelectric layer 14 is aluminum nitride, and the Mo (molybdenum) pressure is the pressure when the first metal layer 13 is molybdenum. The abscissa represents the preset distance D from the first end face E1 of the fixed end B1 to the leftmost end (the second end face E2) of the first metal layer 13. The direction of the preset distance D to the left is the positive direction. As the x-axis increases, the structural model changes from ​ the corresponding structure to ​ the corresponding structure.

[0085] From ​ it can be seen that when the first metal layer 13 is far from the fixed end B1 ( ​ ), the stress sharing effect of the first metal layer 13 on the cantilever beam is small. As the left end (the second end face E2) of the first metal layer 13 gradually approaches the fixed end B1, the pressures on the first metal layer 13 and the AlN layer start to change significantly at -25um. The stress borne by the first metal layer 13 suddenly increases, while the AlN layer suddenly decreases. Until the first metal layer 13 crosses the fixed end B1 and extends 25um into the fixed end B1 ( ​ ), the stress borne by the AlN layer reaches the minimum value, and the stress borne by the first metal layer 13 reaches the maximum value. After that, as the first metal layer 13 continues to extend, the stresses on the two types of film layers remain stable and no longer have an obvious change trend.

[0086] In summary, the conclusion 1 can be obtained: under the same driving force, the first metal layer 13 plays a very good protective role for the AlN layer (piezoelectric layer 14), greatly reducing the brittle fracture risk of the cantilever beam under the same conditions. In particular, when the preset distance D from the first end face E1 to the second end face E2 is less than zero ( ​ ), when the preset distance D≥-25um, the protective effect of the first metal layer 13 is obvious; when the preset distance D between the first end face E1 and the second end face E2 is greater than zero ( ​ ), after the preset distance D≥25um, the protective effect of the first metal layer 13 reaches the maximum.

[0087] ​ It shows the influence trend of the change of the preset distance D between the first end face E1 and the second end face E2 on the stress under the conditions of different cantilever beam lengths. In order to verify whether different cantilever beam lengths have an impact on the change of the preset distance D, ​ the cantilever beam length of ​ is reduced by 0.2mm compared with the cantilever beam length of ​ . From the ​ data, it can be seen that the change of the cantilever beam length has basically no influence on the protective effect of the first metal layer 13 shown in conclusion 1.

[0088] In addition, ​ The figure shows a cross-sectional view of the AlN film layer covered with a metal layer. It can be seen that there are rugged morphologies like mountains / valleys on the surface of the AlN film layer. The metal layer covering it can relieve the uneven characteristics of the surface, making the surface of the entire composite film layer a relatively flat and continuous surface.

[0089] During the verification process, for the cantilever beam not protected by the metal layer, the actual impact acceleration at which it breaks is much smaller than the theoretical value of the structural simulation. Therefore, the rugged surface of AlN shown in ​ was studied.

[0090] It is considered that the rugged morphology is also one of the reasons for the easy fracture in the root region of the cantilever beam. Because combined with its morphological characteristics, this morphology like mountains / valleys will have stress concentration at the 'valleys' when undergoing stress deformation and bending, which is more likely to cause the AlN film layer to fracture along the grain boundaries, and then lead to the fracture of the cantilever beam. After simulating this, this view can be demonstrated based on the results.

[0091] The simulation model was processed, and a morphological structure design equivalent to the rugged surface was added to the surface of the root region of the cantilever beam, as shown in ​ .

[0092] ​The stress distribution diagram of the model under external excitation is given.

[0093] All models adopt ​ the method of "having the first metal layer 13, and the second end face E2 of the first metal layer 13 being flush with the first end face E1 of the fixed end B1" in

[0094] From ​ it can be seen that after adding a fine rough surface topography, stress concentration points of tensile stress F will be formed at the valleys on the upper surface. The value is even greater than the maximum compressive stress in the lower metal layer area. ( ​ Shows the maximum and minimum values of the section, and the absolute maximum value of the uppermost section is 5.59x10 7 which is greater than the absolute maximum value of 5.37x10 of the lowermost section 7 )

[0095] By comparison, it can be seen that there are more stress concentration points on the rough surface compared to the flat surface. This further proves that when the surface of the film layer is rough and uneven, under the condition of the same tensile stress F, there will be more stress concentration points on the rough surface, and it will bear greater stress than the flat surface. For piezoelectric materials, due to the lattice characteristics, cracks are more likely to occur at these stress concentration points, and these cracks will gradually spread and ultimately lead to brittle fracture of the cantilever beam.

[0096] ​ The normalized maximum tensile stress curve graphs of the rough surface and the flat surface under the same conditions are given. From ​ it can be seen that under the same conditions, the maximum tensile stress of the flat surface is only 40% of the maximum tensile stress of the rough surface. Thus, conclusion 2 is obtained: the rough surface will greatly weaken the anti-brittle fracture performance of the cantilever beam when it is subjected to a large tensile stress.

[0097] In addition, during the actual testing process, the thicker the metal layer on the surface of the cantilever beam, the higher the flatness of its surface. This is due to the metal deposition process and the characteristics of the metal material. The metal film deposition process will fill and flatten the relatively rough surface. Therefore, the thicker the metal layer, the higher the improvement in the anti-brittle fracture performance of the cantilever beam, and the cantilever beam is not likely to break.

[0098] ​ The schematic diagrams of different metal layer coverage areas are given. ​ The anti-brittle fracture performance of the cantilever beam in

[0099] shows H < I < J. That is, in the case of a rough surface, the anti-brittle fracture performance of the cantilever beam increases with the increase of the surface metal layer coverage area. This conclusion can be obtained by combining conclusion 1 and conclusion 2. ​The improved cantilever beam bending model structure is shown. Subsequently, when the cantilever beam is subjected to a squeezing test, it can be clearly observed that the cantilever beam bends and then recovers without fracture.

[0100] For the impact test of the improved product, a total of 200 samples were tested, and the number of samples with fractures was 0.

[0101] The improved surface morphology is as ​ shown. Compared with the device morphology before improvement in the prior art, the surface of the piezoelectric device of the present invention is covered by a metal electrode layer.

[0102] In summary, for the piezoelectric device provided by the present invention, by adjusting the relative position of the first metal layer 13 on the cantilever beam and the fixed end B1, part of the stress is transferred to the first metal layer 13, thereby reducing the stress on the piezoelectric layer 14, and thus improving the anti-brittle fracture ability of the cantilever beam. The extension range of the first metal layer 13 can extend from not reaching the root of the fixed end B1 to extending into the fixed end B1. When the second end face E2 of the first metal layer 13 does not reach the fixed end B1, the preset distance D between the first end face E1 and the second end face E2 in the range of ≥ -25um has a better effect. When the second end face E2 extends into the fixed end B1, making the preset distance D greater than 25um and then the anti-brittle fracture effect in the root area of the cantilever beam reaches the best. The setting of the first metal layer 13 has a certain improvement effect on the anti-brittleness of the piezoelectric device, and its effect increases with the increase of the coverage range of the first metal layer 13 and will gradually reach the maximum. That is ​ the effect begins to be significant after the preset distance D ≥ -25um, ​ the best effect is obtained after the preset distance D ≥ 25um.

[0103] In addition, the anti-brittle fracture effect obtained by the first metal layer 13 covering the rough surface increases with the increase of the coverage area of the first metal layer 13: As can be seen from Conclusion 2, the rough surface has a great impact on the anti-brittle fracture performance of the cantilever beam. Therefore, the effect of the first metal layer 13 covering the surface to make the surface flat contributes greatly to the improvement of the anti-brittle fracture performance of the cantilever beam. With the increase of the coverage area of the first metal layer 13 and the reduction of the rough surface, its anti-brittle fracture performance will continue to increase until the surface is completely covered by the first metal layer 13.

[0104] On the other hand, in the above ​ case, the first metal layer 13 is located below the piezoelectric layer 14, and the maximum stress distribution area when the cantilever beam undergoes strain is on the upper and lower sides of the root of the structure (as can be seen from ​ ) Therefore, it is extremely important to arrange metal layers on the upper and lower sides of the cantilever beam. Special metal layers can be arranged on both the upper and lower sides at the same time. And arranging metal layers within the piezoelectric layer 14 or additionally arranging metal layers on the premise that there are metal layers on both the upper and lower sides should belong to equivalent technologies.

[0105] Thus, in some other examples, at least one layer of the first metal layer 13 is disposed below the piezoelectric layer 14, and / or at least one layer of the first metal layer 13 is disposed above the piezoelectric layer 14, and / or at least one layer of the first metal layer 13 is disposed within the piezoelectric layer 14.

[0106] As ​ shown, there is only one layer of the first metal layer 13, all of which are located below the piezoelectric layer 14.

[0107] As ​ shown, there are two layers of the first metal layer 13, which are respectively located below and above the piezoelectric layer 14. And the lengths of the two layers of the first metal layer 13 in the extending direction S can be the same, that is, the preset distance D from the first end face E1 of the fixed end B1 to the second end face E2 of the first metal layer 13 can be the same. For example ​ shown; the lengths of the two layers of the first metal layer 13 in the extending direction S can also be different. For example ​ shown.

[0108] Of course, there can also be only one layer of the first metal layer 13, which is only disposed above the piezoelectric layer 14.

[0109] It can also be as ​ shown that on the premise that there is a metal layer on at least one side of the piezoelectric layer 14, adding at least one layer of metal layer at any position in the piezoelectric layer 14 material can slightly improve the anti-cracking performance.

[0110] As ​ shown, the stress value of the cantilever beam at the position of the black dotted line is small, and the stress gradually increases from the dotted line to the upper and lower sides until it reaches the maximum at the upper and lower sides of the cantilever beam. Therefore, setting metal layers on the upper and lower sides of the cantilever beam has the best effect, and inserting a metal layer in the piezoelectric layer 14 has a smaller effect, but it also has a certain improvement effect, and its improvement effect should conform to the aforementioned conclusion 1.

[0111] ​ shows the situation of inserting at least one layer of metal layer in the piezoelectric layer 14 material. However, this setting method has some defects, that is, in the case where there is no metal layer protection on the outside of the piezoelectric layer 14 material, there is still a high probability that cracks may occur on the surface of the piezoelectric layer 14 material due to the lattice structure characteristics, and then expand during the subsequent vibration process, ultimately leading to the scrapping of the device. But from ​ it can be seen that although the effect of inserting a metal layer in the piezoelectric layer 14 is not the best, it can still improve the anti-cracking effect of the cantilever beam.

[0112] In addition, the cantilever beam further includes at least one layer of the second metal layer 15 stacked on the substrate 10, and at least one layer of the second metal layer 15 is close to the fixed end B1 and extends toward the first metal layer 13.

[0113] ​ The case where the second metal layer 15 can also be used as the metal layers on both the upper and lower sides of the cantilever beam to enhance the anti-cracking property is shown.

[0114] The covering condition of the second metal layer 15 should conform to Conclusion 1, that is, the best covering range of the second metal layer 15 is in the interval of -25um to 25um. As ​ shown, the second metal layer 15 extends from the fixed end B1 to the inside of the free end B2; the left end of the second metal layer 15 can extend to the left end as ​ shown to achieve full coverage of the fixed end B1.

[0115] The second metal layer 15 can also be located at the fixed end B1 or the free end B2 as ​ and ​ shown. Its covering range intersects with [-25um, 25um], but the performance is relatively ​ weaker, but it can also play a role in enhancing the anti-cracking property.

[0116] ​ In, the projection of the second metal layer 15 and the first metal layer 13 in the stacking direction does not coincide. Or, as ​ shown, the projection of the second metal layer 15 and the first metal layer 13 in the stacking direction coincides.

[0117] Therefore, at least one second metal layer 15 is provided below the piezoelectric layer 14, and / or at least one second metal layer 15 is provided above the piezoelectric layer 14, and / or at least one second metal layer 15 is provided inside the piezoelectric layer 14.

[0118] It should be noted that ​ the shorter second metal layer 15 is for the convenience of drawing. In fact, the distances of the second metal layer 15 from the fixed end B1 in the above examples can be the same or different, which is related to the actual design requirements.

[0119] And, the first metal layer 13 can also be as described above ​ and has not extended to the fixed end B1 yet. When the first metal layer 13 extends to the fixed end B1 or beyond the fixed end B1, the above setting method of the second metal layer 15 can also be applied, which will not be elaborated here.

[0120] For the piezoelectric device of the present invention, the cantilever beam can further include at least one functional film layer 16. At least one functional film layer 16 is provided below the piezoelectric layer 14, and / or at least one functional film layer 16 is provided above the piezoelectric layer 14, and / or at least one functional film layer 16 is provided inside the piezoelectric layer 14.

[0121] Taking ​ and ​For example, in the stacking direction, functional film layers 16 are provided on both the upper and lower sides of the piezoelectric layer 14. The functional film layer 16 can be a composite film layer, and the functional film layers 16 on the upper and lower sides of the piezoelectric layer 14 can be different, that is, the materials of the two functional film layers 16 can be different, the lengths can be different, and so on.

[0122] The material of the functional film layer 16 is not limited and is specifically selected according to needs.

[0123] The functional film layer 16 can be applied to the foregoing various different examples, and details are not described herein again.

[0124] In each of the above examples, an oxide layer 12 can also be provided on the substrate 10 in the region corresponding to the fixed end B1, and each film layer such as the piezoelectric layer 14, the first metal layer 13, and the second metal layer 15 is located on the oxide layer 12.

[0125] The above description is only an example of the present invention and is not intended to limit the protection scope of the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A piezoelectric device, characterized in that, Comprising: A substrate and a cantilever beam laminated on the substrate, the substrate having a cavity formed therein, the cantilever beam being divided into a fixed end located on the substrate and a free end located over the cavity; The cantilever beam includes a piezoelectric layer laminated on the substrate and at least one first metal layer, the piezoelectric layer extending onto the substrate and the cavity, the first metal layer being at least suspended over the free end above the cavity and away from the fixed end, and a preset distance is formed between a first end face of the fixed end facing the cavity and a second end face of the first metal layer facing the fixed end in the extending direction from the free end to the fixed end; At least one of the first metal layers is disposed below the piezoelectric layer, and the first metal layer extends from an end of the free end away from the first end face towards the fixed end along the extending direction, the first metal layer starting from the end of the free end away from the first end face and ending at the second end face; When the second end face of the first metal layer does not extend to the first end face of the fixed end, the preset distance from the first end face to the second end face is less than zero; the preset distance ≥ -25um, and when the direction from the first end face to the second end face is defined as opposite to the extending direction, the preset distance is less than zero.

2. The piezoelectric device according to claim 1, wherein The cantilever beam further includes at least one second metal layer laminated on the substrate, and at least one of the second metal layers is close to the fixed end and extends towards the first metal layer.

3. The piezoelectric device according to claim 2, characterized in that, The second metal layer is located within the fixed end, or the second metal layer is located within the free end, or the second metal layer extends from the fixed end into the free end.

4. The piezoelectric device according to claim 3, characterized in that, The projection of the second metal layer and the first metal layer in the lamination direction does not coincide, or the projection of the second metal layer and the first metal layer in the lamination direction coincides.

5. The piezoelectric device according to claim 4, characterized in that, At least one of the second metal layers is disposed below the piezoelectric layer, and / or at least one of the second metal layers is disposed above the piezoelectric layer, and / or at least one of the second metal layers is disposed within the piezoelectric layer.

6. The piezoelectric device according to any one of claims 1 to 5, characterized in that, An oxide layer is further provided on the substrate corresponding to the fixed end, and both the piezoelectric layer and the first metal layer are located on the oxide layer.

7. The piezoelectric device according to any one of claims 1 to 5, characterized in that, The cantilever beam further includes at least one functional film layer, and at least one of the functional film layers is disposed below the piezoelectric layer, and / or at least one of the functional film layers is disposed above the piezoelectric layer, and / or at least one of the functional film layers is disposed within the piezoelectric layer.

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