A MEMS piezoelectric device

Abstract

The application provides a MEMS piezoelectric device, relates to the field of semiconductor technology, and comprises an electrode layer, the electrode layer comprises a bottom electrode and a middle electrode, or the electrode layer comprises a bottom electrode, a middle electrode and a top electrode, and a piezoelectric layer is arranged between the bottom electrode and the middle electrode and between the middle electrode and the top electrode; when the top electrode is provided with a through hole structure, below the through hole structure corresponds the middle electrode and / or the bottom electrode in the stacking direction; when the middle electrode is provided with a through hole structure, below the through hole structure corresponds the bottom electrode in the stacking direction. The problems of grain boundary precipitation in the piezoelectric layer area above the electrode layer corresponding to the through hole structure are solved, the surface deposition quality of the device is ensured, the precision of through hole etching can be improved, the connection quality of the through hole is ensured, and the performance of the MEMS system is ensured.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically to a MEMS piezoelectric device. Background Technology

[0002] In MEMS (Micro-Electro-Mechanical Systems) piezoelectric devices, such as Figure 1 As shown, the central area is the effective thin film region A, or the effective region, while the area outside effective thin film region A is the ineffective region D above the substrate. The ineffective region D forms the metal bonding region B. Since the final signal needs to be wired and led out, no electrodes are placed below the metal bonding region B. The ineffective region D also forms a via connection region C above the substrate for through-hole connections. Because there are different via connection plates at the location corresponding to the via connection region C, no electrodes are placed below the via connection region C.

[0003] However, if electrodes are not deposited in the areas below the metal wire bonding region B and the via connection region C, especially in the area below the via connection region C, the highly doped piezoelectric layer below the via connection region C will have a rough surface due to grain boundary precipitation, resulting in an uneven surface. Furthermore, the quality of the via connection significantly impacts the performance of the MEMS system. Since the via structure domain requires etching of the piezoelectric layer, severe grain boundary precipitation in this area will affect the etching precision of the via, thereby affecting the connection quality and causing performance degradation of the MEMS system. Summary of the Invention

[0004] The purpose of this invention is to provide a MEMS piezoelectric device that can ensure the integrity of the connection at the electrical connection point and the overall manufacturing level of the MEMS.

[0005] In one aspect, the present invention provides a MEMS piezoelectric device, comprising: an electrode layer, the electrode layer including a bottom electrode and a middle electrode, or the electrode layer including a bottom electrode, a middle electrode and a top electrode, wherein a piezoelectric layer is disposed between the bottom electrode and the middle electrode and between the middle electrode and the top electrode; When the top electrode is provided with a through-hole structure, the middle electrode and / or the bottom electrode are located below the through-hole structure in the stacking direction; When the middle electrode is provided with the through-hole structure, the bottom electrode is located below the through-hole structure in the stacking direction.

[0006] The MEMS piezoelectric device provided by this invention has an electrode plate disposed in the region corresponding to the lower part of the through-hole structure along the stacking direction. The electrode plate is the middle electrode and / or the bottom electrode below the through-hole structure of the top electrode, or the bottom electrode below the through-hole structure of the middle electrode, to fill the gaps in the same electrode layer, so that the electrode layer can achieve a full-coverage effect as much as possible. The setting of the electrode plate can solve the problem of grain boundary precipitation in the piezoelectric layer region above the electrode layer corresponding to the through-hole structure, ensuring the surface deposition quality of the device; it can also improve the etching accuracy of the through-hole, ensure the connection quality of the through-hole, and ensure the performance of the MEMS system. Attached Figure Description

[0007] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in 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 should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0008] Figure 1 This is a top view of a MEMS piezoelectric device; Figure 2 This is one of the schematic diagrams of a partial top view of the MEMS piezoelectric device provided by the present invention; Figure 3 yes Figure 2 EE-directed cross-section; Figure 4 yes Figure 3 Enlarged view at point P; Figure 5 This is the second partial top view schematic diagram of the MEMS piezoelectric device provided by the present invention; Figure 6 This is the third partial top view schematic diagram of the MEMS piezoelectric device provided by the present invention; Figure 7 yes Figure 6 Sectional view along the GH direction.

[0009] Icons: 10-Substrate; 11-Cavity; 12-Functional Layer; 130-Bottom Electrode; 131-Middle Electrode; 14-Piezoelectric Layer; 151-First Electrode Plate; 151.1-First Electrode Plate of Bottom Electrode; 151.2-First Electrode Plate of Middle Electrode; 151.3-First Electrode Plate of Top Electrode; 152-Second Electrode Plate; 16-Slit; 17-Through Hole; 170-Through Hole Structure; 18-Metallic Connection Structure; A-Effective Thin Film Region; B-Metal Wire Bonding Region; C-Through Hole Connection Region; D-Non-Effective Region; F-Layering Direction. Detailed Implementation

[0010] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings.

[0011] Reference Figure 2 , Figure 3 As shown, the present invention provides a MEMS piezoelectric device (hereinafter referred to as the device), comprising: an electrode layer, the electrode layer comprising a bottom electrode 130 and a middle electrode 131, or the electrode layer comprising a bottom electrode 130, a middle electrode 131 and a top electrode, wherein a piezoelectric layer 14 is disposed between the bottom electrode 130 and the middle electrode 131 and between the middle electrode 131 and the top electrode. When the top electrode is provided with a through-hole structure 170, in the stacking direction F, there is a middle electrode 131 and / or a bottom electrode 130 below the through-hole structure 170. When the middle electrode 131 is provided with a through hole structure 170, the bottom electrode 130 is located below the through hole structure 170 in the stacking direction F.

[0012] For example, the bottom electrode 130, the middle electrode 131, or the bottom electrode 130, the middle electrode 131 and the top electrode are sequentially stacked on the substrate 10 having the cavity 11. The bottom electrode 130, the middle electrode 131, or the bottom electrode 130, the middle electrode 131 and the top electrode can be collectively referred to as the electrode layer. The electrode layer and the piezoelectric layer 14 form an effective thin film region A in the region corresponding to the cavity 11, and the electrode layer and the piezoelectric layer 14 form an ineffective region D in the region corresponding to the region of the substrate 10.

[0013] The lower electrode layer region corresponding to the through-hole structure 170 is an electrode plate, which can be located in the effective thin film region A or in the non-effective region D.

[0014] The electrode plate includes a first electrode plate 151, which is connected to the same electrode layer. The through-hole structure 170 connects the corresponding piezoelectric layer 14 and the first electrode plate 151 to extract the signal from the same electrode layer. The electrode plate also includes a second electrode plate 152, which is spaced from the same electrode layer.

[0015] The present invention describes the first electrode plate 151 or the second electrode plate 152 below the stacking direction F corresponding to the through hole structure 170.

[0016] In addition to the through-hole structure 170, the electrode layer in the effective thin film region A and the electrode layer in the non-effective region D of the MEMS piezoelectric device of the present invention are fully covered as much as possible, that is, the electrode layer is laid over a large area. This can solve the problems of severe grain boundary precipitation, large surface roughness and uneven surface of the highly doped piezoelectric layer 14, thereby improving the surface deposition quality of the device.

[0017] Compared to the prior art where no electrode is laid below the via structure 170, this invention takes into account the problem of grain boundary precipitation of the piezoelectric layer 14. In particular, the highly doped piezoelectric layer lattice of the via structure 170 has a significant impact on the performance of the system itself. Therefore, a first electrode plate 151 or a second electrode plate 152 is also provided below the via structure 170 along the stacking direction F to fill the gap where the via structure 170 corresponding to the same electrode layer is not laid. This solves the problem of grain boundary precipitation of the piezoelectric layer 14 and ensures the deposition quality of the piezoelectric layer 14 and the electrode layer at that location.

[0018] For example, when the electrode layer of the present invention has two layers, namely a bottom electrode 130 and a middle electrode 131, the following description will take the bottom electrode 130 as an example.

[0019] like Figure 3 As shown, an electrode plate is disposed below the through-hole structure 170 along the stacking direction F. The electrode plate is in the same layer as the bottom electrode 130. The electrode plate fills the gap of the bottom electrode 130 at that location, allowing the bottom electrode 130 to be fully covered and solving the problem of grain boundary precipitation. For example, the electrode plate here is a second electrode plate 152. The second electrode plate 152 is separated from the bottom electrode 130 in the same layer and on the periphery by a slit 16, ensuring that the second electrode plate 152 below the through-hole structure 170 is isolated from the bottom electrode 130 that is fully covered on the periphery. Figure 3 , Figure 4 Since there is no need to extract the signal from the bottom electrode 130, the second electrode plate 152 is isolated from the surrounding bottom electrode 130.

[0020] Figure 3 , Figure 4 The through-hole structure 170 is connected to the intermediate electrode 131. The through-hole structure 170 contains a metal connection structure 18, which enables signal extraction from the intermediate electrode 131. The area below the through-hole structure 170 corresponding to the intermediate electrode 131 can be considered as the first electrode plate 151 of the intermediate electrode 131. This first electrode plate 151 is connected to the intermediate electrode 131. The through-hole structure 170 connects the corresponding piezoelectric layer 14 and the first electrode plate 151, thus enabling signal extraction from the intermediate electrode 131.

[0021] like Figure 2 As shown, a second electrode plate 152 is disposed below the via connection area C connected to the metal wire bonding area B. The second electrode plate 152 is separated from the electrode layer of the effective thin film area A by a slit 16, indicating that the via connection area C here is not intended to lead out electrical signals from the electrode layer. Figure 3 , Figure 4 As shown, a second electrode plate 152 is disposed on the same layer as the bottom electrode 130. The second electrode plate 152 corresponds to the through hole structure 170 above it. The second electrode plate 152 and the bottom electrode 130 on the same layer are separated by a slit 16.

[0022] By placing an electrode plate below the through-hole structure 170, the electrode layer in the same layer can be fully covered as much as possible. The electrode plate could be either a first electrode plate 151 or a second electrode plate 152. The difference is that the first electrode plate 151 is connected to the electrode layer in the same layer and needs to have signals extracted, while the second electrode plate 152 is spaced apart from the electrode layer in the same layer. The second electrode plate 152 is only set up to complete the full coverage of the electrode layer in the same layer. The function of the second electrode plate 152 is solely to meet the quality control of the highly doped piezoelectric layer 14 deposited above, solving the aforementioned problem of grain boundary precipitation in the piezoelectric layer 14. Therefore, the first electrode plate 151 is an effective part of the MEMS design itself and can be considered as part of the electrode layer in the same layer.

[0023] Generally, when there are multiple electrode layers, the projections of the first electrode plates 151 of the multi-layer electrode layers in the stacking direction F do not overlap to prevent parasitic capacitance. For example, when there are three electrode layers, namely the bottom electrode 130, the middle electrode 131, and the top electrode, as shown... Figure 5 As shown, the projections of the first electrode plate 151.1 of the bottom electrode, the first electrode plate 151.2 of the middle electrode, and the first electrode plate 151.3 of the top electrode are completely non-overlapping in the stacking direction F. It should be noted that, here, the projections of the first electrode plate 151 in the stacking direction F are non-overlapping, while the projections of the first electrode plate 151 and the second electrode plate 152 in the stacking direction F can overlap.

[0024] Reference Figure 6 , Figure 7 As shown, when it is necessary to extract the signal from the middle electrode 131, the electrode plate corresponding to the middle electrode 131 below the through hole 17 for extracting the signal from the middle electrode 131 is the first electrode plate 151. The through hole structure 170 is connected to the first electrode plate 151 corresponding to the middle electrode 131, directly extracting the signal from the middle electrode 131. The electrode plates of the bottom electrode 130 and the top electrode corresponding to the first electrode plate 151 of the middle electrode 131 in the stacking direction F are both second electrode plates 152. The second electrode plate 152 is connected to the first electrode plate 151 in the stacking direction through the through hole structure 170.

[0025] At this time, for the bottom electrode 130, the bottom electrode 130 signal is led out through the first electrode plate 151. In the stacking direction F, the first electrode plate 151 of the bottom electrode 130 does not need to be laid at the corresponding position in the stacking direction F. If it is necessary to lay, the second electrode plate 152 can be laid at the corresponding middle electrode 131 position and the top electrode position. The second electrode plate 152 has a through hole structure 170 and is connected to the first electrode plate 151 of the bottom electrode 130.

[0026] When it is necessary to extract the signal from the bottom electrode 130, the electrode plate of the bottom electrode 130 corresponding to the through hole 17 below the through hole 17 is the first electrode plate 151. The through hole structure 170 is connected to the first electrode plate 151 of the corresponding bottom electrode 130, directly extracting the signal from the bottom electrode 130. The electrode plates of the middle electrode 131 and the top electrode, which are corresponding to the first electrode plate 151 of the bottom electrode 130 in the stacking direction F, are both second electrode plates 152. The second electrode plate 152 is connected to the first electrode plate 151 in the stacking direction F through the through hole structure 170.

[0027] Normally, there is no direct connection between the middle electrode 131 and the bottom electrode 130, nor is there a direct connection between the top electrode and the bottom electrode 130. The effective electrodes of each electrode layer are connected individually, or the effective electrodes of the top electrode and the bottom electrode 130 are connected before the signal is output.

[0028] If only the top electrode signal needs to be extracted, the same method can be used. When the first electrode plate 151 is set in the same layer as the top electrode, the signal of the top electrode is extracted through the first electrode plate 151 and the corresponding through hole structure 170. The electrode plates of the bottom electrode 130 and the middle electrode 131 corresponding to the first electrode plate 151.3 of the top electrode in the stacking direction F are both second electrode plates 152. The second electrode plate 152 and the first electrode plate 151 are connected in the stacking direction F through the through hole structure 170.

[0029] When the top electrode and bottom electrode 130 are connected by an effective metal signal, even if the signals of the top electrode and bottom electrode 130 are already connected, their potentials must be the same. At this time, it is perfectly fine for the second electrode plate 152 of the bottom electrode 130 to be located below the first electrode plate 151.3 of the top electrode. Then, it is connected to the second electrode plate 152 of the middle electrode 131 of the next part through the metal connection structure 18. This allows the first electrode plate 151.3 of the top electrode, the second electrode plate 152 of the middle electrode 131, and the second electrode plate 152 of the bottom electrode 130 to be connected through the through hole 17 to achieve the interconnection of electrical signals.

[0030] To achieve the connection via 17, the bottom electrode 130 and the top electrode are first connected via 17, and then the signal is connected to the middle electrode 131. This is because, for the design of the double piezoelectric layer 14, the potentials of the top electrode signal and the bottom electrode 130 signal are always the same when the thin film vibrates. The middle electrode 131, located essentially in the neutral layer of the entire thin film, always has the lowest potential. Therefore, electrical designs often connect the top electrode and bottom electrode 130 signals at one location, and then connect the middle electrode 131 signal at the next location.

[0031] The bottom electrode 130 is completely laid out in the corresponding position. Since the signal of the bottom electrode 130 needs to be connected to the electrode plate of the middle electrode 131 and the electrode plate of the top electrode, when the through hole 17 is completely connected to them by the metal connection structure 18, the potential of the second electrode plate 152 of the bottom electrode 130 below the middle electrode 131 and the top electrode is actually the same as that of the electrode plate of the middle electrode 131 and the electrode plate of the top electrode. Therefore, there is no problem in fully laying the bottom electrode 130.

[0032] Current double piezoelectric layer structures cannot be designed in this way, or such designs are ineffective, or there are other design connection methods. However, the present invention, through the above-mentioned settings, enables the proposed solution of fully covering the bottom electrode 130 to be realized. The fully covering bottom electrode 130 achieves the laying of almost all the bottom electrodes 130, with only a certain spacing width in the areas where the slits 16 need to be spaced. The spacing width of the slits 16 is so small that it can be ignored.

[0033] The above description describes the full coverage of the bottom electrode 130. Similarly, the full coverage of the middle electrode 131 can be set with reference to the full coverage of the bottom electrode 130. Whether the top electrode is fully covered or not is meaningless for the improvement of the highly doped piezoelectric layer 14, so the present invention does not limit it.

[0034] In addition, a functional layer 12 is provided between the substrate 10 and the bottom electrode 130, such as an oxide layer, to realize the corresponding functions.

[0035] The above description is merely an example of the present invention and is not intended to limit the scope of protection of the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A MEMS piezoelectric device, characterized in that, include: An electrode layer, comprising a bottom electrode, a middle electrode, and a top electrode, wherein a piezoelectric layer is disposed between the bottom electrode and the middle electrode, and between the middle electrode and the top electrode; When the top electrode is provided with a through-hole structure, the middle electrode and the bottom electrode are located below the through-hole structure in the stacking direction; When the middle electrode is provided with the through hole structure, the bottom electrode is located below the through hole structure in the stacking direction; The area of ​​the electrode layer below the through-hole structure is an electrode plate. The electrode plate includes a first electrode plate, which is connected to the electrode layer in the same layer. The through-hole structure connects the corresponding piezoelectric layer and the first electrode plate to extract the signal from the electrode layer in the same layer. The electrode plate also includes a second electrode plate, which forms a gap with the electrode layer in the same layer so that the electrode layer in the same layer is basically fully covered.

2. The MEMS piezoelectric device according to claim 1, characterized in that, The projections of the first electrode plates of each electrode layer in the stacking direction do not overlap.

3. The MEMS piezoelectric device according to claim 2, characterized in that, When the first electrode plate is disposed in the same layer as the bottom electrode, the signal of the bottom electrode is led out through the first electrode plate and the corresponding through hole structure. The electrode plates of the middle electrode and the top electrode, which correspond to the first electrode plate of the bottom electrode in the stacking direction, are both the second electrode plates. The second electrode plate and the first electrode plate are connected in the stacking direction through the through hole structure.

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