Patent Application
20210111332
The present invention relates to a bonded body and an acoustic wave device.
It has been widely used an SOI substrate composed of a high resistance Si/SiO2 thin film/Si thin film, for realizing a high-performance semiconductor device. Plasma activation is used for realizing the SOI substrate. This is because the bonding can be realized at a relatively low temperature (400° C.). It is proposed a composite substrate composed of similar Si/SiO2 thin film/piezoelectric thin film for improving the characteristics of a piezoelectric device (patent document 1). According to patent document 1, the piezoelectric single crystal substrate composed of lithium niobate or lithium tantalate and silicon substrate with the silicon oxide layer formed thereon are activated by ion activation method, followed by the bonding.
Further, it is known direct bonding method of so-called FAB (Fast Atom Beam) system. According to the method, neutralized atomic beam is irradiated onto each bonding surface at ambient temperature to active it, followed by direct bonding (patent document 2).
According to patent document 3, surfaces of a silicon substrate and lithium tantalate substrate are subjected to surface activation by neutralized atomic beam and the surfaces are bonded with each other, so that it is generated an amorphous layer containing tantalum, silicon and argon atoms along an interface between the silicon substrate and lithium tantalate substrate.
(Patent document 1) Japanese Patent Publication No. 2016-225537A
(Patent document 2) Japanese Patent Publication No. 2014-086400A
(Patent document 3) WO 2017/134980 A1
lithium tantalate or lithium niobate single crystal used in an acoustic wave filter has a low thermal conductivity. Due to increase of transmitted electric power resulting from recent increase of communication amounts and heat generation from surrounding devices provided by module fabrication, the acoustic wave device is susceptible to temperature rise. As a result, the acoustic wave filter composed of a piezoelectric single crystal substrate only could not be used for high performance communication terminal devices.
On the other hand, according to the method that neutralized atomic beam is irradiated onto bonding surfaces of a piezoelectric single crystal substrate and supporting substrate according to FAB (Fast Atom Beam) system to activate them which are directly bonded with each other, heat can be dissipated toward the side of the supporting substrate. The heat dissipation property is higher than the acoustic wave filter composed of the piezoelectric single crystal substrate only. However, a high temperature of about 80° C. is applied onto the bonded body of the piezoelectric single crystal substrate and supporting substrate, and the warping may thus occur. It is considered that a large stress is applied on a crystal plane of the piezoelectric single crystal substrate due to a difference of thermal expansion of the piezoelectric single crystal substrate and supporting substrate.
An object of the present invention is, in a bonded body of a piezoelectric single crystal substrate and supporting substrate, to suppress the warping of the bonded body.
The present invention provides a bonded body comprising:
The present invention further provides an acoustic wave device comprising:
According to the invention, the bonding layer of the specific composition described above is provided so that the insulating property of the bonding layer can be improved.
Moreover, in the case that such bonding layer is provided, a thin amorphous layer is generated along an interface between the bonding layer on the piezoelectric single crystal substrate and supporting substrate. However, as the thus obtained bonded body is heated, the warping of the bonded body may occur.
Thus, the inventors have researched the cause of the warping and reached the idea that the warping may possibly be generated due to the difference of thermal expansion of the piezoelectric single crystal substrate and supporting substrate. It is considered that the warping caused by the difference of the thermal expansion is difficult to absorb in the bonding layer and amorphous layer on the viewpoint of the structure.
Here, when the amorphous layer is generated along the bonding interface of the bonding layer on the piezoelectric single crystal substrate and supporting substrate, the inventors tried to change the structure of an emitting aperture of argon atomic beam, for example, for raising the energy intensity of the argon atomic beam at the central part of the bonding interface and for making the oxygen concentration at the central part higher than the oxygen concentration at the peripheral part of the amorphous layer on the bonding layer. The inventors then researched the effects on the warping of the bonded body upon heating. As a result, the warping of the bonded body upon heating was considerably reduced.
Although the reason is not clear, by providing in-plane distribution of the concentrations that the oxygen concentration at the central part of the amorphous layer is relatively high, the in-plane distribution of the thickness of the amorphous layer is adjusted so that the thickness at the central part is further increased. As a result, it is considered that the stress applied on the piezoelectric single crystal upon heating is relaxed and that the warping of the bonded body upon heating is suppressed.
The present invention will be described further in detail below, appropriately referring to drawings.
According to an embodiment shown in
According to a preferred embodiment, the surface 2a of the bonding layer 2 is then subjected to flattening process to form a flat surface 2b on the bonding layer, as shown in
Further, as shown in
According to a preferred embodiment, the surface 4b of the piezoelectric single crystal substrate 4 of the bonded body 5 is further subjected to polishing for thinning the piezoelectric single crystal substrate 4A and to obtain a bonded body 5A, as shown in
According to
Here, the amount of the energy irradiated onto each activated surface is appropriately adjusted to generate an amorphous layer 8 along an interface between the bonding layer 2A and supporting substrate 1, as shown in
According to an embodiment shown in
Further, as shown in
According to a preferred embodiment, the surface 4b of the piezoelectric single crystal substrate 4 of the bonded body 15 is further subjected to polishing to thin a piezoelectric single crystal substrate 4A to obtain a bonded body 15A, as shown in
Here, the amount of the energy irradiated onto each activated surface is appropriately adjusted to generate an amorphous layer 8 along an interface between the bonding layer 2A and supporting substrate 1, as shown in
Respective constituents of the present invention will be described further in detail below.
According to the present invention, the supporting substrate 1 is composed of a polycrystalline ceramic material or single crystal substrate. The single crystal substrate forming the supporting substrate 1 may preferably be silicon or sapphire. Further, the polycrystalline ceramic material may preferably be a material selected from the group consisting of mullite, cordierite, translucent alumina and sialon.
(Piezoelectric Single Crystal Substrate)
Specifically, as the materials of the piezoelectric single crystal 4 and 4A, single crystals of lithium tantalate (LT), lithium niobate (LN), lithium niobate-lithium tantalate solid solution, quartz and lithium borate may be listed. Among them, LT or LN is more preferred. As LT or LN has a high propagation speed of a surface acoustic wave and large electro-mechanical coupling factor, it is preferred for use in a piezoelectric surface acoustic wave device for high frequency and wide-band frequency applications. Further, the normal direction of the main surface of the piezoelectric single crystal substrate 4 or 4A is not particularly limited. However, in the case that the piezoelectric single crystal substrate 4 or 4A is made of LT, for example, it is preferred to use the substrate rotated from Y-axis to Z-axis by 36 to 47° (for example) 42° with respect to X-axis, which is a direction of propagation of a surface acoustic wave, because of a low propagation loss. In the case that the piezoelectric single crystal substrate 4 or 4A is made of LN, it is preferred to use the substrate rotated from Y-axis to Z-axis by 60 to 68° (for example 64°) with respect to X-axis, which is a direction of propagation of a surface acoustic wave, because of a lower propagation loss. Further, although the size of the piezoelectric single crystal substrate 4 or 4A is not particularly limited, for example, the diameter may be 50 to 150 mm and thickness may be 0.2 to 60 μm.
(Bonding Layer)
According to the present invention, it is provided the bonding layer 2A between the supporting substrate 1 and piezoelectric single crystal substrate 4 or 4A, and the bonding layer 2A has a composition of Si(1-x)Ox (0.008≤x≤0.408). The composition is a composition whose oxygen concentration is considerably lower than that of SiO2 (x==0.667). As the piezoelectric single crystal substrate 4 or 4A is bonded to the supporting substrate 1 through the bonding layer 2A of the silicon oxide Si(1-x)Ox of such composition, the bonding strength can be made high and the insulating property of the bonding layer 2A can be made high.
In the case that x is lower than 0.008 in the composition of Si(1-x)Ox forming the bonding layer 2A, the electrical resistance of the bonding layer 2A is low and desired insulating property cannot be obtained. Thus, x is made 0.008 or higher, x may preferably be made 0.010 or higher, more preferably be made 0.020 or higher, and most preferably be made 0.024 or higher. Further, in the case that x exceeds 0.408, the bonding strength is lowered and the separation of the piezoelectric single crystal substrate 4 or 4A tends to occur. x is thus made 0.408 or lower and more preferably be made 0.225 or lower.
The electrical resistivity of the bonding layer 2A may preferably be 4.8×103 Ω·cm or higher, more preferably be 5.8×103 Ω·cm or higher, and particularly preferably be 6.2×103 Ω·cm or higher. Further, the electrical resistivity of the bonding layer 2A is generally 1.0×108 Ω·cm or lower.
Although the thickness of the bonding layer 2A is not particularly limited, it may preferably be 0.01 to 10 μm and more preferably be 0.01 to 0.5 μm, on the viewpoint of production cost.
Although the film-forming method of the bonding layer 2A is not particularly limited, sputtering method, chemical vapor deposition (CVD) method and vapor deposition method may be listed. Here, particularly preferably, during reactive sputtering using a sputtering target of Si, the amount of oxygen gas flown into a chamber is adjusted so that the oxygen ratios (x) in the bonding layer 2A can be controlled.
Although specific conditions are appropriately selected depending on the specification of the chamber, according to a preferred example, the total pressure is made 0.28 to 0.34 Pa, the partial pressure of oxygen is made 1.2×10−3 to 5.7×10−2 Pa and the film-forming temperature is made ambient temperature. Further, Si doped with B is exemplified as the Si target. As described later, the amount of B (boron) as an impurity is controlled at about 5×1018 atoms/cm3 to 5×1019 atoms/cm3 at an interface between the bonding layer 2A and supporting substrate 1. It is thereby possible to obtain the insulation property of the bonding layer 2A more assuredly.
(Intermediate Layer)
An intermediate layer 9 may be further provided between the bonding layer 2A and piezoelectric single crystal substrate 4 or 4A. Such intermediate layer 9 is preferably to improve the adhesion of the bonding layer 2A and piezoelectric single crystal substrate 4 or 4A, and specifically intermediate layer 9 may preferably be composed of SiO2, Ta2O5, TiO2, ZrO2, HfO2, Nb2O3, Bi2O3, Al2O3, MgO, AlN or Si3N4. Most preferably, the intermediate layer is composed of SiO2.
(Amorphous Layer)
According to the present invention, an amorphous layer 8 is provided between the supporting substrate 1 and bonding layer 2A. The amorphous layer 8 contains at least oxygen atoms and argon atoms. Preferably, the amorphous layer 8 contains one or more element (excluding oxygen element) forming the supporting substrate 1. In the case that the element forming the supporting substrate 1 is of a single kind, the element forming the amorphous layer 8 is also of a single kind. In the case that plural kinds of the elements forming the supporting substrate 3 are present, the element (s) forming the amorphous layer 8 is of a single kind or plural kinds among them.
According to the present invention, the concentration of oxygen atoms at the central part of the amorphous layer 8 is made higher than the concentration of oxygen atoms at the peripheral part of the amorphous layer 8. Here, in the specification, the central part of the amorphous layer 8 means a center of the amorphous layer 8 in the case that the amorphous layer 8 is viewed in a plan view. Further, the peripheral part of the amorphous layer 8 is measured at each of three positions in a ring-shaped region defined by a width of 5 to 10 mm from an end part (edge) in the direction toward the center of the amorphous layer 8, and the average value is taken.
The oxygen concentration at the central part of the amorphous layer 8 may preferably be 1.08 atom % or higher and more preferably be 1.1 atom % or higher, on the viewpoint of electrical conductivity. Further, the oxygen concentration at the central part of the amorphous layer 8 may preferably be 40.8 atom %.
The oxygen concentration at the peripheral part of the amorphous layer 8 may preferably be 0.8 atom % or higher and more preferably be 1.0 atom % or higher, on the viewpoint of electrical conductivity. Further, the oxygen concentration at the peripheral part of the amorphous layer 8 may preferably be 39.8 atom % or lower.
On the viewpoint of reducing the warping of the bonded body 5, 5A, 15 or 15A upon heating, the difference between the concentration of oxygen atoms at the central part and the concentration of oxygen atoms at the peripheral part of the amorphous layer 8 may preferably be 1.0 atom % or larger and more preferably be 2.0 atom % or larger. In other words, the concentration of oxygen atoms at the central part of the amorphous layer 8 is preferably higher than the concentration of oxygen atoms at the peripheral part of the amorphous layer 8 by 1.0 atom % or larger and more preferably by 2.0 atom % or larger.
According to a preferred embodiment, the thickness at the central part of the amorphous layer 8 is larger than the thickness at the peripheral part of the amorphous layer 8. It is thereby possible to reduce the warping of the bonded body 5, 5A, 15 or 15A upon heating. On such viewpoint, the difference between the thickness at the central part of the amorphous layer 8 and the thickness at the peripheral part of the amorphous layer 8 may preferably be 0.5 nm or larger and more preferably be 1.0 nm or larger.
Further, the thickness at the central part of the amorphous layer 8 may preferably be 2.8 to 8 nm and more preferably be 3.2 to 8 nm. Further, the thickness at the peripheral part of the amorphous layer 8 may preferably be 1.0 to 2.8 nm and more preferably be 1.2 to 2.6 nm.
According to a preferred embodiment, the concentration of argon atoms at the central part of the amorphous layer 8 is made higher than the concentration of argon atoms at the peripheral part of the amorphous layer 8. Here, in the specification, the central part of the amorphous layer 8 means the center of the amorphous layer 8 in the case that the amorphous layer 8 is viewed in a plan view. Further, the peripheral part of the amorphous layer 8 means that the measurement is performed at three positions in a ring-shaped region in the direction from the end part (edge) toward the center of the amorphous layer in a width of 5 to 10 mm and that the average value is calculated.
The concentration of argon atoms at the central part of the amorphous layer 8 may preferably be 2.1 atom % or higher and more preferably be 2.4 atom % or higher, on the viewpoint of bonding strength. Further, the concentration of argon atoms at the central part of the amorphous layer is usually 5.0 atom % or lower and preferably be 4.8 atom % or lower.
The concentration of argon atoms at the peripheral part of the amorphous layer 8 may preferably be 1.1 atom % or higher and more preferably be 1.8 atom % or higher, on the viewpoint of bonding strength. Further, the concentration of argon atoms at the peripheral part of the amorphous layer is usually 3.0 atom % or lower and preferably be 2.5 atom % or lower.
On the viewpoint of reducing the warping of the bonded body 5, 5A, 15 or 15A upon heating, the difference between the concentration of argon atoms at the central part and the concentration of argon atoms at the peripheral part of the amorphous layer 8 may preferably be 1.0 atom % or higher and more preferably be 1.5 atom % or higher. In other words, the concentration of argon atoms at the central part of the amorphous layer 8 may preferably be higher than the concentration of argon atoms at the peripheral part of the amorphous layer 8 by 1 atom % or larger and more preferably be by 1.5 atom % or larger.
Further, the presence of the amorphous layer 8 is to be confirmed as follows.
The microstructure is observed using a transmission-type electron microscope “H-9500” supplied by Hitachi High-Tech Corporation.
A sample of a thinned piece is observed by FIB (Focused Ion Beam method) at an accelerating voltage of 200 kV.
The concentrations of the respective atoms in the amorphous layer 8 is to be measured as follows.
The elementary analysis is performed using an elementary analyzing system (“JEM-ARM200F” supplied by JEOL Ltd.).
A sample of a thinned piece is observed by FIB (Focused Ion Beam method) at an accelerating voltage of 200 kV.
The arithmetic average roughness Ra of the surface of the bonding layer 2A may preferably be 1 nm or smaller and more preferably be 0.3 nm or smaller. Further, the arithmetic average roughness Ra of the surface 1a of the supporting substrate 1 may preferably be 1 nm or smaller and more preferably be 0.3 nm or smaller. By this, the bonding strength of the supporting substrate 1 and bonding layer 2A is further improved.
The method of flattening the surfaces 2b of the bonding layer 2A and the surface 1a of the supporting substrate 1 includes lapping, chemical mechanical polishing (CMP) or the like.
According to a preferred embodiment, the surface 2b of the bonding layer 2A and the surface 1a of the supporting substrate 1 can be activated by neutralized beam. Particularly, in the case that the surface 2b of the bonding layer 2A and the surface 1a of the supporting substrate 1 are flat surfaces, the direct bonding can be easily performed.
When the activation of the surfaces is performed using the neutralized beam, it is preferred to use a system described in Japanese Patent Publication No. 2014-086400A to generate the neutralized beam, which is irradiated. That is, it is used a high-speed atomic beam source of saddle field type as the beam source. Then, argon gas is introduced into the chamber and a high voltage is applied onto electrodes from a direct current electric source. By this, electric field of saddle field type generated between the electrode (positive electrode) and a housing (negative electrode) causes motion of electrons, e, so that atomic and ion beams derived from the argon gas are generated. Among the beams reaches at a grid, the ion beam is neutralized at the grid, and the beam of neutral atoms is emitted from the high-speed atomic beam source.
In the activation step by beam irradiation, the voltage may preferably be made 0.5 to 2.0 kV, and the current may preferably be made 50 to 200 mA.
In the case that a high-speed atomic beam is irradiated onto the piezoelectric single crystal substrate 4 and supporting substrate 1, it is used a grid in which distribution is provided in the sizes, directions and inclination of the holes, so that a larger amount of the beam is irradiated onto the central part. Specifically, as to a square region having dimensions of 30 mm and 30 mm positioned at the central part of the grid, it may be used a grid in which the central part of the substrate to be irradiated by the beam is positioned on an extended line connecting the centers on the incident side and on the emitting side of the grid hole, or the sizes of the grid holes in the square region having dimensions of 30 mm and 30 mm at the central part of the grid are made larger than those in the other region by 15 to 30%. Alternatively, the flow rate of Ar gas may be made larger by 40% only in the region of 30 mm at the central part of the grid, so that the distribution can be provided in the irradiation amount of the beam. However, according to the present invention, it is not limited to the methods described above, it is permitted as far as a larger amount of the beam is irradiated onto the central part than the peripheral part as a result.
Then, the activated surfaces are contacted and bonded with each other under vacuum atmosphere. The temperature at this time may be ambient temperature, specifically 40° C. or lower and more preferably 30° C. or lower. Further, the temperature during the bonding may more preferably be 20° C. or higher and 25° C. or lower. The pressure at the bonding is preferably 100 to 20000N.
The application of each of the bonded bodies 5, 5A, 15 and 15A of the present invention is not particularly limited, and it may preferably be applied as an acoustic wave device or optical device.
As the acoustic wave devices 7 and 17, a surface acoustic wave device, Lamb wave-type device, thin film resonator (FBAR) or the like is known. For example, the surface acoustic wave device is produced by providing input side IDT (Interdigital transducer) electrodes (also referred to as comb electrodes or interdigitated electrodes) for oscillating surface acoustic wave and IDT electrodes on the output side for receiving the surface acoustic wave on the surface of the piezoelectric single crystal substrate. By applying high frequency signal on the IDT electrodes on the input side, electric field is generated between the electrodes, so that the surface acoustic wave is oscillated and propagated on the piezoelectric substrate. Then, the propagated surface acoustic wave is drawn as an electrical signal from the IDT electrodes on the output side provided in the direction of the propagation.
A metal film may be provided on a bottom surface of the piezoelectric single crystal substrate 4 or 4A. After the Lamb type device is produced as the acoustic wave device, the metal film plays a role of improving the electro-mechanical coupling factor near the bottom surface of the piezoelectric substrate. In this case, the Lamb type device has the structure that interdigitated electrodes are formed on the surface 4b or 4c of the piezoelectric single crystal substrate 4 or 4A and that the metal film on the piezoelectric single crystal substrate 4 or 4A is exposed through a cavity provided in the supporting body 1. Materials of such metal films include aluminum, an aluminum alloy, copper, gold or the like, for example. Further, in the case that the Lamb wave type device is produced, it may be used a composite substrate having the piezoelectric single crystal substrate 4 or 4A without the metal film on the bottom surface.
Further, a metal film and an insulating film may be provided on the bottom surface of the piezoelectric single crystal substrate 4 or 4A. The metal film plays a role of electrodes in the case that the thin film resonator is produced as the acoustic wave device. In this case, the thin film resonator has the structure that electrodes are formed on the upper and bottom surfaces of the piezoelectric single crystal substrate 4 or 4A and the insulating film is made a cavity to expose the metal film on the piezoelectric single crystal substrate. Materials of such metal films include molybdenum, ruthenium, tungsten, chromium, aluminum or the like, for example. Further, materials of the insulating films include silicon dioxide, phosphorus silicate glass, boron phosphorus silicate glass or the like.
Further, as the optical device, it may be listed an optical switching device, wavelength conversion device and optical modulating device. Further, a periodic domain inversion structure may be formed in the piezoelectric single crystal substrate 4 or 4A.
In the case that the present invention is applied to the optical device, the size of the optical device can be reduced. Further, particularly in the case that the periodic domain inversion structure is formed, it is possible to prevent the deterioration of the periodic domain inversion structure by heat treatment. Further, as the materials of the bonding layers 2A of the present invention are of high insulation, the generation of domain inversion is prevented during the processing by the neutralized beam before the bonding, and the shape of the periodic domain inversion structure formed in the piezoelectric single crystal substrate 4 or 4A is hardly disordered.
It was produced the bonded body 5A of the inventive example 1 shown in table 1, according to the method described referring to
Specifically, it was used a lithium tantalate substrate (LT substrate) having an OF (orientation flat) part, a diameter of 4 inches and a thickness of 250 μm as the piezoelectric single crystal substrate 4. It was used a 46° Y-cut X-propagation LT substrate in which the propagation direction of surface acoustic wave (SAW) is made X and the cutting angle was of rotated Y-cut plate, as the LT substrate. The surface 4a of the piezoelectric single crystal substrate 4 was subjected to mirror surface polishing so that the arithmetic average roughness Ra reached 0.3 nm. Further, Ra is measured by an atomic force microscope (AFM) in a visual field of 10 μm×10 μm.
Then, the bonding layer 2 was film-formed on the surface 4a of the piezoelectric single crystal substrate 4 by direct current sputtering method. Si doped with boron was used as a target. Further, oxygen gas was introduced as an oxygen source. At this time, the amount of the introduced oxygen gas was changed to change the total pressure of atmosphere and partial pressure of oxygen in a chamber, so that the oxygen ratio (x) in the bonding layer 2 was adjusted. The thickness of the bonding layer 2 was made 100 to 200 nm. The arithmetic average roughness Ra of the surface 2a of the bonding layer 2 was 0.2 to 0.6 nm.
Then, the bonding layer 2 was subjected to chemical mechanical polishing (CMP) so that the film thickness was made 80 to 190 μm and Ra was made 0.08 to 0.4 nm.
Further, as the supporting substrate 1, it was prepared the supporting substrate 1 composed of Si and having the orientation flat (OF) part, a diameter of 4 inches and a thickness of 500 μm. The surfaces 1a and 1b of the supporting substrate 1 were finished by chemical mechanical polishing (CMP) so that the respective arithmetic average roughnesses Ra reached 0.2 nm.
Then, the flat surface 2b of the bonding layer 2A and surface 1a of the supporting substrate 1 were cleaned to remove the contamination, followed by introduction into a vacuum chamber. After it was evacuated to the order of 10−6 Pa, high-speed atomic beam of 180 kJ was irradiated onto the bonding surfaces 1a and 2b of the respective substrates. Then, after the beam-irradiated surface (activated surface) 2b of the bonding layer 2A and activated surface 1a of the supporting substrate 1 were contacted with each other, the substrates 1 and 4 were bonded by pressurizing at 10000N for 2 minutes (refer to
At this time, it is used a grid in which the sizes of the grid holes are made larger by 20% only in the region of sizes of 30 mm×30 mm at the central part, so that a larger amount of the argon atomic beam is irradiated onto the central parts of the respective surfaces.
Then, the surface 4b of the piezoelectric single crystal substrate 4 was then subjected to grinding and polishing so that the thickness was changed from the initial 250 μm. to 1 μm (refer to
The oxygen ratio (x) of the bonding layer 2A of the thus obtained bonded body 5A was measured by EDS according to the following conditions. Here, the bonding layer 2A had a composition of Si(0.95)O0.05.
an elementary analysis system (“JEM-ARM200F” supplied by JEOL Ltd.).
A sample of a thinned piece is observed by FIB (Focused Ion Beam method) at an accelerating voltage of 200 kV.
Further, it was measured the concentrations of the respective atoms in the amorphous layer at the bonding interface between the bonding layer 2A and supporting substrate 1. Further, the thickness of the amorphous layer 8 was measured as follows.
The microstructure is observed using a transmission-type electron microscope (“H-9500” supplied by Hitachi High-Tech Corporation).
A sample of a thinned piece is observed by FIB (Focused Ion Beam method) at an accelerating voltage of 200 kV.
The measurement results were shown in table 1.
Further, the thus obtained bonded body was heated at 80° C., and the value of SORI was measured. The results were shown in table 1.
When the SORI was measured, it was used a laser displacement meter “LK-G5000” supplied by Keyence corporation, the information of the height of a wafer mounted on a movable table is measured, and the scanning is performed on lines. The measurement is performed on the orientation flat and on the two lines in horizontal and vertical directions of the substrate. The SORI is defined as a larger value of the measured SORI values.
As shown in table 1, according to the inventive example 1, the oxygen concentration, argon concentration and thickness at the central part of the amorphous layer 8 are larger than the oxygen concentration, argon concentration and thickness at the peripheral part of the amorphous layer 8, and SORI upon heating at 80° C. was as low as 330 μm.
The bonded body 15A was produced according to the method shown in
The oxygen ratio (x) of the bonding layer 2A of the thus obtained bonded body 15A was measured. Further, the concentrations of the respective atoms of the amorphous layer 8, the thickness of the amorphous layer 8 and SORI upon heating at 80° C. were measured. The results were shown in table 1.
As shown in table 1, according to the inventive example 2, the oxygen concentration, argon concentration and thickness at the central part of the amorphous layer 8 were larger than the oxygen concentration, argon concentration and thickness at the peripheral part of the amorphous layer 8, and SORI upon the heating at 80° C. was as low as 360 μm.
The bonded body 5A was produced and evaluated according to the same procedure as that of the inventive example 1. However, according to the present example, the structure of the emitting aperture of the argon atomic beam was made as follows, so that the argon atomic beam was irradiated substantially uniformly onto the whole of the bonding surfaces 2b and 1a. The results were shown in table 2.
As shown in table 2, according to the comparative example 1, the oxygen concentration and thickness at the central part of the amorphous layer 8 were same as the oxygen concentration and thickness at the peripheral part 8, and SORI upon heating at 80° C. was as large as 660 μm.
The bonded body 15A was produced and evaluated according to the same procedure as that of the inventive example 2. However, according to the present example, argon atomic beam was irradiated substantially uniformly over the whole of the bonding surface 2b and 1a. The results were shown in table 2.
As shown in table 2, according to the comparative example 2, the oxygen concentration, thickness and argon concentration at the central part of the amorphous layer 8 were smaller than the oxygen concentration, thickness and argon concentration at the peripheral part of the amorphous layer 8, SORI upon heating at 80° C. was as large as 670 μm.
The bonded body 5A was produced according to the same procedure as that of the comparative example 1. However, according to the present example, the irradiation amount of the argon atomic beam was increased to 360 kJ. The results were shown in table 2.
According to the comparative example 3, the oxygen concentration at the central part was same as the oxygen concentration at the peripheral part of the amorphous layer 8, the argon concentration and thickness at the central part were smaller than the argon concentration and thickness at the peripheral part of the amorphous layer, and SORI upon heating at 80° C. was as large as 610 μm.
Further, according to the inventive examples 1 and 2 and comparative examples 1 to 3, although the composition of the bonding layer 2A was made Si(1-x)Ox (x=0.05), it is not limited thereto. In the case that the bonding layer 2A has a composition of Si(1-x)Ox (0.0085≤x≤0.408), the warping can be reduced, while the insulating property of the bonded body 5, 5A, 15 or 15A can be assured.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-118503 | Jun 2018 | JP | national |
This is a continuation of PCT/JP2019/017156, filed Apr. 23, 2019, which claims priority to Japanese Application No. 2018-118503, filed Jun. 22, 2018, the entire contents of which are hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2019/017156 | Apr 2019 | US |
| Child | 17128857 | US |
