Vibration plate joint

Abstract

Based on a bonded body of a vibration plate comprising high-rigidity ceramic and a support substrate, a structure is provided that can maintain the strength of the vibration plate and prevent the vibration plate from peeling or cracking. The vibration plate bonded body 5 comprises: a support substrate 3 comprising silicon; a vibration plate 1A comprising high-rigidity ceramic and having a thickness of 100 μm or less; and a bonding layer 2 comprising α-Si, located between the support substrate 3 and the vibration plate 1A and in contact with the bonding surface 1a of the vibration plate 1A. The arithmetic mean roughness Ra of the bonding surface 1a of the vibration plate 1A is not less than 0.01 nm and not more than 10.0 nm, and the etch pit density of the bonding surface 1a of the vibration plate 1A is not less than 0.01 nm and not more than 10.0 nm per 100 μm. 2 There are more than 10.

Description

Technical Field

[0001] The present invention relates to a bonded body formed by bonding a high-rigidity ceramic vibration plate and a supporting substrate, which can be used for a MEMS (Micro Electro Mechanical System) mirror or the like. Background Art

[0002] A head-up display (HUD) is a device that displays necessary information in the driver's field of vision while maintaining forward gaze. Compared to viewing information on the instrument panel or console, being able to view information while maintaining forward gaze is effective in preventing inattentive driving. Furthermore, since eye focus shifts less, driver fatigue is reduced, improving safety.

[0003] The principle of HUD is explained below. Images from fluorescent tubes, CRTs, or liquid crystal displays are projected onto the car's windshield or a transparent screen (combiner). HUDs have the following two types, depending on their optical structure.

[0004] (1) Direct projection method that projects images directly onto a screen such as a windshield.

[0005] (2) Virtual Imaging method that uses the windshield, etc. as a reflector to form an image on the driver's retina

[0006] The biggest difference between the above methods lies in the driver's perception of distance when viewing the image. While the Direct Projection method displays images on a screen (combiner) like a regular projector, the Virtual Imaging method displays images in a space several meters away from the driver's line of sight. With both methods, compared to not using a HUD, the driver's eye movement between the forward field of view and the instrument panel and console panel is significantly reduced. However, with the Virtual Imaging method, the focus shift from the field of view during normal driving is also reduced, allowing for greater focus on driving and reducing fatigue. Within the Virtual Imaging method, new methods using scanning laser beams for drawing have been developed in recent years.

[0007] Laser scanning displays combine three RGB laser beams using an optical element called a combiner. This single beam is then reflected by tiny mirrors and scanned two-dimensionally to create images. While similar to electron beam scanning in CRTs, instead of exciting phosphors, the pulse width and output power of each laser are controlled at the corresponding pixel position on the horizontal scan line, changing the color and brightness to create high-speed pixel rendering. The achievable resolution depends on the mirror's vibration frequency and the laser's modulation frequency.

[0008] The following are the main advantages of this method.

[0009] (1) The number of components is small, so miniaturization, cost reduction and improved reliability can be achieved.

[0010] (2) The laser is turned on according to the brightness required for each pixel, thereby achieving low power consumption.

[0011] (3) Collimated (parallel light) laser light is used, so focus adjustment is not required.

[0012] For micromirrors, which are core components of laser scanning displays, silicon is processed using MEMS (Micro Electro Mechanical System) technology and then metal is evaporated. Mirror driving methods include: electrostatic driving using electrostatic attraction, electromagnetic driving using electromagnetic force, and piezoelectric driving using piezoelectric elements. The piezoelectric method has advantages such as high-speed driving, low power consumption, and high driving force, while its disadvantages include the difficulty of forming a film using piezoelectric elements. For example, a MEMS mirror using an SOI substrate has been proposed (Patent Document 1).

[0013] Prior art literature

[0014] Patent Literature

[0015] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-037578

[0016] Patent Document 2: Japanese Patent Application Laid-Open No. 2014-086400 Summary of the Invention

[0017] In the future, HUDs are expected to have larger screens and wider viewing angles, with the current viewing angle of 7-8 degrees being increased to a maximum of 20 degrees. To achieve these larger screens and wider viewing angles, the frequency, amplitude, and reliability of the MEMS mirror's piezoelectric elements must be improved. In particular, the scanning width and speed must be increased. However, this is not possible with conventional piezoelectric elements formed by film deposition on Si substrates.

[0018] Therefore, research has been conducted on the use of a high-rigidity ceramic plate as a vibration plate below the piezoelectric layer. However, in order to use a high-rigidity ceramic plate as the above-mentioned vibration plate, the thickness of the high-rigidity ceramic plate needs to be reduced to a thickness of less than 100μm, which is necessary to increase the frequency. However, if the thickness of the high-rigidity ceramic plate is less than 100μm, the mechanical strength is insufficient. Therefore, research has been conducted on the following: after bonding the high-rigidity ceramic plate to a supporting substrate to obtain a bonded body, the high-rigidity ceramic plate is ground to a thickness of less than 100μm.

[0019] However, actual experiments have shown that due to the difficulty in machining high-rigidity ceramics, the load (shear stress) during machining is high, resulting in problems such as peeling and cracking. In addition, research has been conducted to improve the bond strength between the vibration plate and the support substrate by introducing a bonding layer between the vibration plate and the support substrate. This is achieved by roughening the surface of the vibration plate to improve the adhesion between the vibration plate and the bonding layer. However, it is believed that roughening the surface of the vibration plate reduces the bending strength of the vibration plate. Therefore, it is difficult to prevent peeling and cracking in the bonded structure of the vibration plate and the support substrate composed of high-rigidity ceramics.

[0020] An object of the present invention is to provide a structure of a bonded body of a diaphragm made of high-rigidity ceramic and having a thickness of 100 μm or less and a support substrate, which can maintain the strength of the diaphragm and prevent peeling or cracking of the diaphragm.

[0021] The vibration plate assembly according to the present invention comprises:

[0022] a support substrate comprising silicon;

[0023] a vibration plate comprising high-rigidity ceramic and having a thickness of 100 μm or less; and

[0024] a bonding layer comprising α-Si, located between the support substrate and the vibration plate and in contact with a bonding surface of the vibration plate;

[0025] The arithmetic mean roughness Ra of the bonding surface of the vibration plate is not less than 0.01 nm and not more than 10.0 nm, and the etch pit density of the bonding surface of the vibration plate is 2 There are more than 10.

[0026] Furthermore, the present invention is a method for producing a vibration plate assembly, comprising:

[0027] a step of providing a bonding layer containing α-Si on the surface of a high-rigidity ceramic plate containing high-rigidity ceramic,

[0028] Next, a step of bonding the bonding surface of the bonding layer to a bonding surface of a support substrate made of silicon, and

[0029] Next, the high-rigidity ceramic plate is processed to obtain a vibration plate having a thickness of 100 μm or less.

[0030] The method for producing the vibration plate assembly is characterized in that:

[0031] The arithmetic mean roughness Ra of the surface of the high-rigidity ceramic plate is not less than 0.01 nm and not more than 10.0 nm, and the etch pit density of the surface of the high-rigidity ceramic plate is 2 There are more than 10.

[0032] Effects of the Invention

[0033] If a block-shaped high-rigidity ceramic plate is directly bonded to a support substrate containing silicon, it will not be able to withstand the grinding process when the high-rigidity ceramic plate is ground to a thickness of less than 100 μm, and the high-rigidity ceramic plate will peel off or crack. Therefore, the inventors of the present invention tried: providing an α-Si bonding layer on the block-shaped high-rigidity ceramic plate, and bonding the bonding layer to the support substrate containing silicon. The purpose of providing the α-Si bonding layer is, for example, to be able to suppress costs in the etching process for making the vibration plate a hollow structure. The bonding strength between the bonding layer containing α-Si and the support substrate containing silicon is high, and it should be able to withstand the process of grinding the high-rigidity ceramic plate to a thickness of less than 100 μm.

[0034] However, it was thought in the past that: when grinding, the possibility of cracking or peeling off at the interface of high rigidity ceramic plate and bonding layer was higher. This is because: high rigidity ceramic plate needs bending strength, therefore, it is necessary to make the surface smoothing of high rigidity ceramic plate. However, if the high rigidity ceramic plate surface is smooth, then the adhesion between the surface of the bonding layer (amorphous silicon) provided on its surface is reduced, therefore, it should be easy to peel off or crack at the smooth interface of high rigidity ceramic plate and bonding layer.

[0035] While considering the above factors, the inventors of the present invention attempted to improve the smoothness of the surface of the high-rigidity ceramic plate (the bonding surface where the bonding layer is to be set). As a result, it was found that in some cases, even if the bonding surface is smooth, peeling or cracking is not likely to occur at the interface with the bonding layer during grinding.

[0036] The inventors of the present invention further studied the vibration plate assembly exhibiting the above-mentioned characteristics exceeding expectations. They discovered that even in the case of a smooth surface with an extremely low arithmetic mean roughness (Ra) of the high-rigidity ceramic plate's bonding surface, etch pits caused by minute voids exist on the bonding surface due to the physical properties of the high-rigidity ceramic plate. These surface etch pits suppress delamination, leading to the present invention.

[0037] That is, if the arithmetic mean roughness Ra of the joint surface of the vibration plate exceeds 10.0 nm, the bending strength of the vibration plate when vibrating is weak and it cannot withstand high-amplitude, high-frequency vibrations. Therefore, an ultra-smooth surface with an Ra of 10.0 nm or less is used. It was found that even in this case, by setting the pit density of the joint surface of the vibration plate to 100 μm per 100 μm, the vibration plate can be smoothed. 2 Even if there are 10 or more of them, cracking or peeling of the vibration plate during grinding can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 In the figure, (a) shows a state where a bonding layer 2 is provided on a bonding surface 1a of a high-rigidity ceramic plate 1, (b) shows a state where a surface 2b of the bonding layer 2 is activated by a neutral atom beam, and (c) shows a state where a bonding surface 3a of a supporting substrate 3 is activated by a neutral atom beam.

[0039] Figure 2 In the drawings, (a) shows a bonded structure 4 of the high-rigidity ceramic plate 1 and the support substrate 3 , and (b) shows a bonded structure 5 of the vibration plate 1A and the support substrate 3 .

[0040] Figure 3 This is an AFM measurement image showing the state of surface pits on the bonding surface of a high-rigidity ceramic plate. DETAILED DESCRIPTION

[0041] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings as appropriate.

[0042] like Figure 1 As shown in (a), a high-rigidity ceramic plate 1 is prepared. The arithmetic mean roughness Ra of the surface 1a of the high-rigidity ceramic plate is set to 0.01 nm or more and 10.0 nm or less, and the etch pit density of the surface of the high-rigidity ceramic plate is set to 0.01 nm or more and 10.0 nm or less per 100 μm. 2 There are more than 10. 1b is the back surface of the high-rigidity ceramic plate 1.

[0043] Next, a bonding layer 2 containing α-Si is formed on the surface 1a of the high-rigidity ceramic plate 1. Figure 1 As shown in (b), the bonding surface 2a of the bonding layer 2 is activated by irradiating a neutral atom beam as indicated by arrow A. Meanwhile, the bonding surface 3a of the supporting substrate 3 is activated by irradiating a neutral atom beam as indicated by arrow B.

[0044] Next, if Figure 2 As shown in (a), the activated bonding surface 2b of the bonding layer 2 and the activated bonding surface 3a of the supporting substrate 3 are brought into contact and directly bonded to obtain a bonded body 4. Next, the back surface 1b of the high-rigidity ceramic plate 1 of the bonded body 4 is processed, thereby Figure 2As shown in (b), the thickness of the high-rigidity ceramic plate is reduced to form a vibration plate 1A with a thickness of 100 μm or less, thereby obtaining a vibration plate assembly 5. 1c is a processed surface.

[0045] The thickness of the silicon-containing support substrate is not particularly limited, but is preferably 200 μm or greater, more preferably 400 μm or greater, from the perspective of maintaining strength during processing. Furthermore, the arithmetic mean roughness Ra of the bonding surface of the support substrate is preferably 1 nm or less, more preferably 0.3 nm or less, from the perspective of promoting direct bonding.

[0046] High-rigidity ceramics are defined as ceramic materials with a Young's modulus ≥ 200 GPa and a three-point bending strength ≥ 300 GPa.

[0047] As the high-rigidity ceramic, sialon, cordierite, mullite, translucent alumina, aluminum nitride, silicon nitride, or silicon carbide is preferable.

[0048] The thickness of the high-rigidity ceramic plate is preferably 100 μm or greater, more preferably 200 μm or greater, from the perspective of operability in processes such as substrate cleaning and bonding. While there is no particular upper limit on the thickness of the high-rigidity ceramic plate, it is preferably 300 μm or less from the perspective of shortening processing time.

[0049] In the present invention, the arithmetic mean roughness Ra of the surface of the vibration plate (the surface on which the bonding layer is to be provided) is 0.01 nm to 10.0 nm, and the etch pit density of the surface of the vibration plate is 2 However, in the vibration plate assembly, since a bonding layer is formed on the vibration plate, the surface Ra and the pit density of the vibration plate are the same as those of the high-rigidity ceramic plate before processing.

[0050] The arithmetic mean roughness Ra of the high-rigidity ceramic plate and the vibration plate is measured as follows. First, the surface is measured using an atomic force microscope (AFM) with a field of view of 10 μm × 10 μm, and Ra is calculated according to JIS B 0601. 2 ) in the process, the number of etch pits was counted. Here, the criteria for determining etch pits were as follows. That is, the following concave portions among the concave portions observed on the surface were defined as etch pits.

[0051] (1) The concave portion has a diameter of not less than 50 nm and not more than 2000 nm.

[0052] (2) The depth of the concave portion is 1 nm or more.

[0053] In the present invention, the arithmetic mean roughness Ra of the surfaces of the vibration plate and the high-rigidity ceramic plate (the surface on which the bonding layer is to be formed) is set to 0.01 nm to 10.0 nm, but from the perspective of bending strength, it is more preferably 7.0 nm or less, and particularly preferably 5.0 nm or less. In addition, from the perspective of adhesion with the bonding layer, Ra is set to 0.01 nm or more, but more preferably 0.02 nm or more.

[0054] The etch pit density of the surface of the vibration plate was set to 100 μm. 2 There are 10 or more, but more preferably 20 or more. In addition, the etch pit density of the surface of the vibration plate can be generally set to 100 μm per 100 μm. 2 The number is 200 or less, more preferably 96 or less, and particularly preferably 70 or less.

[0055] It is believed that the etch pits present on the surfaces of the vibration plate and the high-rigidity ceramic plate facing the bonding layer are caused by the sintering aid added to densely sinter the high-rigidity ceramic plate. Most of the sintering aid remaining during firing exists in the form of aggregation at the grain boundaries of the ceramic particles. When the high-rigidity ceramic with residual sintering aid is wafered and polished to a mirror surface, the part where the sintering aid is aggregated is polished faster than the high-rigidity ceramic itself, and therefore, the part where the sintering aid is aggregated becomes an etch pit. Based on this, there is a correlation between the amount of sintering aid added and the number of etch pits, and the number of etch pits can be adjusted by the amount of sintering aid added.

[0056] To ensure both the bending strength and low Ra of the high-rigidity ceramic plate, the relative density of the high-rigidity ceramic plate is preferably 95% or higher, and more preferably 99% or higher. Furthermore, the type and amount of sintering aid suitable for achieving the aforementioned Ra and pit density are selected based on the type of high-rigidity ceramic to be sintered. Examples of sintering aids include Y2O3, CaO, MgO, and ZrO2.

[0057] In the present invention, the arithmetic mean roughness Ra of the back surface (surface on which the bonding layer is not formed) of the vibration plate and the high-rigidity ceramic plate is preferably 0.01 nm to 10.0 nm from the viewpoint of bending strength.

[0058] The surface of the high-rigidity ceramic plate is polished by, for example, grinding it to a desired thickness using a #3000 grindstone, then lapping it with diamond slurry with a particle size of 3 μm, and finally mirror-finishing it using chemical mechanical polishing (CMP).

[0059] The thickness of the bonding layer 2 formed on the high-rigidity ceramic plate is not particularly limited, but is preferably 0.01 to 10 μm, more preferably 0.05 to 0.5 μm, from the viewpoint of production cost.

[0060] The film formation method of the bonding layer 2 is not limited, and examples thereof include sputtering, chemical vapor deposition (CVD), and vapor deposition.

[0061] Methods for planarizing the bonding surface of the bonding layer 2 and the bonding surface of the supporting substrate include lapping, chemical mechanical polishing (CMP), and the like.

[0062] In a preferred embodiment, the neutral atom beam can activate the surface 2b of the bonding layer 2 and the surface 3a of the support substrate 3. In particular, direct bonding is facilitated when the surface 2b of the bonding layer 2 and the surface 3a of the support substrate 3 are flat.

[0063] When using a neutral atom beam for surface activation, it is preferred to use a device such as that described in patent document 2 to generate a neutral beam for irradiation. That is, as a beam source, a saddle-type high-speed atom beam source is used. Then, an inert gas is introduced into the chamber, and a high voltage is applied to the electrode from a DC power supply. Thus, the saddle-type electric field generated between the electrode (positive electrode) and the shell (negative electrode) is utilized to move the electrons e, thereby generating a beam of atoms and ions of the inert gas. The ion beam in the beam reaching the grid is neutralized in the grid, and therefore, the beam of neutral atoms is emitted from the high-speed atom beam source. The atomic species constituting the beam are preferably inert gases (argon, nitrogen, etc.).

[0064] The voltage during activation by beam irradiation is preferably 0.5 to 2.0 kV, and the current is preferably 50 to 200 mA.

[0065] Next, the activated surfaces are brought into contact with each other in a vacuum atmosphere for bonding. The temperature during bonding is room temperature, specifically, preferably 40°C or lower, more preferably 30°C or lower. Furthermore, the bonding temperature is particularly preferably 20°C or higher and 25°C or lower. The bonding pressure is preferably 100 to 20,000N.

[0066] Next, the high-rigidity ceramic plate is processed to obtain a vibration plate with a thickness of less than 100 μm. The thickness of the vibration plate is selected according to the target frequency, so the lower limit of the thickness is not particularly limited. For ease of processing, it is preferably 1 μm or more. As an example of this processing method, after grinding to the desired thickness using a #3000 grindstone, it is then lapped with diamond slurry with a particle size of 3 μm, and finally mirror-finished using chemical mechanical polishing (CMP).

[0067] Example

[0068] (Examples 1 to 8)

[0069] As reference Figures 1 and 2As described above, a vibration plate bonded body was produced as a prototype.

[0070] Specifically, a wafer-shaped silicon aluminum oxynitride ceramic substrate with a diameter of 4 inches and a thickness of 250 μm is used as the high-rigidity ceramic plate 1. The surface 1a of the high-rigidity ceramic plate 1 is ground to the desired thickness using a #3000 grindstone in such a manner that the arithmetic mean roughness Ra is the values ​​given in Tables 1, 2, and 3, and then, in the case of the vibration plate surface shown in Table 1 (Ra≤1nm), it is lapped with a diamond slurry with a particle size of 3 μm, and finally, it is mirror-finished using chemical mechanical polishing (CMP). The processing pressure and processing time during CMP polishing are adjusted to adjust the value of Ra. In the case of the vibration plate surface given in Table 2 (Ra>1nm), it is lapped with a diamond slurry and mirror-finished. In order to adjust the value of Ra, the diamond slurry used at the end is selected from a particle size of 0.5 μm to 6 μm.

[0071] The Ra of the surface 1a of the high-rigidity ceramic diaphragm 1 was measured using an atomic force microscope (AFM) within a 10μm×10μm field of view. Furthermore, the number of etch pits larger than 50nm in diameter was counted within the 10μm×10μm field of view using the atomic force microscope (AFM). However, when measuring the number of etch pits on the surface 1a of the high-rigidity ceramic plate 1, the pit density was measured at three locations: the center of the wafer-shaped plate 1, a point 10mm inward from the positioning edge of the plate 1, and a point 10mm inward from the end of the plate 1 opposite the positioning edge. The average of the three measured values ​​was defined as the pit density, which is shown in Tables 1, 2, and 3.

[0072] It should be explained that Figure 3 The surface condition of the high-rigidity ceramic plate used in Example 4 is shown in FIG. 1 (Ra = 0.07 nm, pit density in a field of view of 10 μm × 10 μm = 58).

[0073] In addition, the bending strength of each high-rigidity ceramic plate cannot be measured after the substrates are joined. Therefore, each high-rigidity ceramic plate with the same material, thickness, Ra, and pit density as the high-rigidity ceramic substrate 1 of each example was prepared in advance. Test pieces were cut from each high-rigidity ceramic plate and the three-point bending strength was measured. The bending strength was measured according to the three-point bending strength test standard in JIS R 1601 (Test method for room temperature bending strength of fine ceramics). The test piece dimensions were as follows: sample length 40.0 mm, width 4.0 mm, thickness 3.0 mm.

[0074] Next, a bonding layer 2 is formed on the surface 1a of the high-rigidity ceramic plate 1 by direct current sputtering. Boron-doped Si is used as the target. The thickness of the bonding layer 2 is set to 30 to 200 nm. The arithmetic mean roughness Ra of the surface 2a of the bonding layer 2 is 0.2 to 0.6 nm. Next, the bonding layer 2 is subjected to chemical mechanical polishing (CMP) to a film thickness of 20 to 150 nm and an Ra of 0.08 to 0.4 nm.

[0075] On the other hand, a silicon-made support substrate 3 having an orientation flat (OF) portion, a diameter of 4 inches, and a thickness of 500 μm was prepared as the support substrate 3. The surface of the support substrate 3 was finished by chemical mechanical polishing (CMP) to an arithmetic mean roughness Ra of 0.2 nm.

[0076] Next, the surface 2b of the bonding layer 2 and the surface 3a of the support substrate 3 are cleaned to remove dirt and then introduced into a vacuum chamber. －6 After Pa, high-speed atomic beam (acceleration voltage 1 kV, Ar flow rate 27 sccm) was irradiated to each surface for 120 seconds. Next, the activated surface 2b of the bonding layer 2 and the activated surface 3a of the support substrate 3 were brought into contact, and then bonded by applying pressure of 10000 N for 2 minutes ( Figure 2 (a)) Next, the obtained bonded body 4 of each example was heated at 100°C for 20 hours.

[0077] Next, the back surface 1b of the high-rigidity ceramic plate 1 is ground and polished so that the thickness is changed from the initial 250 μm to 40 μm (see Figure 2 (b)).

[0078]

Table 1

[0079]

[0080]

Table 2

[0081]

[0082]

Table 3

[0083]

[0084] In Examples 1 to 8, the etch pit density ranged from 10 to 96, and the Ra ranged from 0.02 to 9.97 nm. Even after polishing the vibration plate 1A to a thickness of 40 μm, no delamination occurred. Furthermore, a trend was observed where the flexural strength of the ceramic decreased with increasing Ra. However, even with Ra = 9.97 nm, the flexural strength was a sufficiently high 500 MPa.

[0085] (Comparative Example 1)

[0086] In Comparative Example 1, a bonding layer 2 comprising α-Si was not formed on the high-rigidity ceramic plate 1. Instead, a high-speed atomic beam was irradiated onto the surface 1a of the high-rigidity ceramic plate 1, bringing the activated surface 1a of the high-rigidity ceramic plate 1 into contact with the activated surface 3a of the supporting substrate 3, and bonding was performed to produce a bonded product. However, the number of etch pits on the surface 1a of the high-rigidity ceramic plate 1 in Comparative Example 1 was 51, and the Ra was 0.03 nm. The fabrication was performed under the same conditions as in Example 1, except that the α-Si bonding layer was not formed.

[0087] Next, the back surface 1b of the high-rigidity ceramic plate 1 of the resulting assembly was ground and polished, and an attempt was made to reduce the thickness from the initial 250 μm. When the thickness of the high-rigidity ceramic plate 1 reached 110 μm, delamination occurred at the bonding interface between the high-rigidity ceramic plate and the supporting substrate. It is believed that the delamination occurred because the bonding strength between the high-rigidity ceramic plate 1 and the supporting substrate 3 in the assembly was lower than that in Examples 1 to 8, and was unable to withstand the processing stress during the polishing of the high-rigidity ceramic plate 1.

[0088] (Comparative Examples 2 and 3)

[0089] The bonded bodies of Comparative Examples 2 and 3 were produced under the same conditions as in Examples 1 to 8.

[0090] However, in Comparative Example 2, the number of etch pits on surface 1a of the high-rigidity ceramic plate 1 was as low as 4, and the Ra of surface 1a was 0.01 nm. In this case, when the back surface of the high-rigidity ceramic plate 1 was thinned to a thickness of 100 μm by grinding and polishing, peeling occurred at the interface between the surface of the high-rigidity ceramic plate 1 and the bonding layer 2. This is believed to be because the adhesion strength between the high-rigidity ceramic plate 1 and the bonding layer 2 could not withstand the processing stress during the polishing of the high-rigidity ceramic plate 1.

[0091] On the other hand, even when the surface Ra of the ceramic interface in Examples 1 to 4 is less than 0.2 nm and is sufficiently small, no peeling occurs. It is speculated that this is because: there are etching pits on the surface 1a of the high-rigidity ceramic plate 1, and the bonding layer 2 formed on the etching pits has an improved adhesion due to the anchoring effect.

[0092] In Comparative Example 3, the number of etch pits on surface 1a of the high-rigidity ceramic diaphragm 1 was 55, but the Ra of surface 1a was 10.85 nm. With an Ra of 10.85 nm, the flexural strength of the high-rigidity ceramic plate dropped to 300 MPa. This is believed to be due to stress concentration on the uneven surface of the high-rigidity ceramic plate, resulting in a decrease in flexural strength.

Claims

1. A vibration plate assembly, characterized in that: have: a support substrate comprising silicon; a vibration plate comprising high-rigidity ceramic and having a thickness of 100 μm or less; and a bonding layer comprising α-Si, located between the support substrate and the vibration plate and in contact with the surface of the vibration plate; The arithmetic mean roughness Ra of the surface of the vibration plate is not less than 0.01 nm and not more than 10.0 nm, and the etch pit density of the surface of the vibration plate is not less than 100 μm. 2 There are more than 10.

2. The vibration plate assembly according to claim 1, wherein The bonding layer and the support substrate are directly bonded.

3. The vibration plate assembly according to claim 1 or 2, wherein: The high-rigidity ceramic is selected from the group consisting of sialon, cordierite, mullite, translucent alumina, aluminum nitride, silicon nitride, and silicon carbide.

4. A method for manufacturing a vibration plate assembly, comprising: a step of providing a bonding layer containing α-Si on the surface of a high-rigidity ceramic plate containing high-rigidity ceramic, Next, a step of bonding the bonding surface of the bonding layer to a bonding surface of a support substrate made of silicon, and Next, the high-rigidity ceramic plate is processed to obtain a vibration plate having a thickness of 100 μm or less. The manufacturing method of the vibration plate assembly is characterized in that: The arithmetic mean roughness Ra of the surface of the high-rigidity ceramic plate is not less than 0.01 nm and not more than 10.0 nm, and the etch pit density of the surface of the high-rigidity ceramic plate is 2 There are more than 10.

5. The method for manufacturing a vibration plate assembly according to claim 4, wherein: The bonding surface of the bonding layer and the bonding surface of the support substrate are directly bonded.

6. The method for manufacturing a vibration plate assembly according to claim 5, wherein: The bonding surface of the bonding layer and the bonding surface of the support substrate are respectively activated by a neutral atom beam, and then directly bonded.

7. The method for manufacturing a vibration plate assembly according to any one of claims 4 to 6, wherein: The high-rigidity ceramic is selected from the group consisting of sialon, cordierite, mullite, translucent alumina, aluminum nitride, silicon nitride, and silicon carbide.

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