JP2001119092A - Substrate-connecting method for joining minute region and substrate-connecting structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate connection method which joins separating a connection pat from a functional connection part and locally perform high frequency heating and/or ion irradiation, in order to further increase the intrinsic connection area of the functional connection part, and a substrate connection structure. SOLUTION: Functional connection faces 4, 5 and first and second substrates 1, 2 having joining parts in the periphery thereof are formed. The functional connection faces 4, 5 of both the substrates 1, 2 are counterposed to each other and the joining parts are counterposed to each other, and the substrates 1, 2 are jointed mechanically to each other under depressurization ambiance via joining members 12, 11 of the joining part. At this time, the functional connection faces 4, 5 are in proximity to each other, while forming a closed space 14 under depressurizing ambiance. After the closed space 14 is formed, the substrate 1 is thinned, and a part 13 where the substrate is made flexible, thereby being pushed into a side of the closed space 14 under atmospheric pressure to fulfill functional connection of the functional connection faces 4, 5. Furthermore, the position of the functional connection is further thinned, and simultaneously at least one of ion irradiation for local heating and high frequency electric field application for high-frequency heating is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for forming a plurality of functional couplings (electrical coupling, optical coupling) in a microscopic region between substrates of the same or different materials in a microscopic region, typically, a plurality of substrates. The present invention relates to a substrate bonding method and a substrate bonding structure for performing region bonding.

[0002]

2. Description of the Related Art Conventionally, as a method for directly joining different kinds of semiconductors for light emission, "Applied Physics", Vol.
No. (Hiroshi Wada, Ken Kamijo, p. 53, 1994). Here, bonding of a combination of InP / GaAs and InP / Si purifies the surface to be bonded and places a weight on the substrate at 700 ° C. in a hydrogen atmosphere at 30 ° C.
It is obtained by heat treatment for a minute.

[0003] Appl. Phys. Lett.
(Lincoln Lab. ZL Lian, 5
6 (8), 19, Feb. 1990, p. As described in U.S. Pat. No. 737), a combined InP / GaAs combination is obtained by cleaning the surfaces to be joined and then heat treating at 750 ° C. in a hydrogen atmosphere in a cylindrical graphite / quartz reactor. Te

[0004]

However, in the above conventional example, since the bonding is performed at a high temperature of about 750 ° C. and the substrates are bonded to each other, there are the following disadvantages.

[0005] 1. In the case of joining different kinds of semiconductors having different coefficients of thermal expansion, a phenomenon occurs in which the joined substrates warp after joining at a high temperature as described above, during cooling to room temperature, or after cooling. That is, residual stress is generated in the bonding substrate, and various problems occur.

[0006] 2. Since the bonding is a combination of the electrical connection, which is a functional connection, and the mechanical bonding strength (the bonding strength for preventing the two materials from being peeled off), an attempt is made to reduce the functional connection portion. Reducing the bonding area reduces the mechanical bonding strength. In these cases,
A decrease in bonding strength causes peeling at a bonding point during the process. Therefore, for electrical and functional coupling, mechanical bonding strength must be ensured even if not so much area is required, so it is difficult to reduce the bonding area as necessary. . Reducing the junction area is required to reduce the threshold value in a surface-emitting type semiconductor laser or the like.

SUMMARY OF THE INVENTION Accordingly, in view of the above problems, it is an object of the present invention to perform joining by separating a joining portion for securing mechanical joining strength and a functional joining portion for achieving functional joining, and In order to further increase the bonding area, high-frequency heating or / and ion irradiation are performed locally, typically,
It is an object of the present invention to provide a substrate bonding method and a substrate bonding structure for performing micro-region bonding that achieves a structure having a plurality of electrical connections in a minute reduced-pressure closed space.

[0008]

In order to achieve the above object, the present invention provides a substrate bonding method and a substrate bonding structure for performing micro-region bonding, which employ a bonding method using at least one of high-frequency heating and ion irradiation. One or a plurality of micro regions (small coupling area) can be coupled in a micro space between the substrates by using the substrates, and an electrical or optical coupling surface that produces a functional coupling. And a bonding portion for providing bonding force are formed on the first and second substrates of the same or different materials, respectively, and these bonding surfaces and the bonding portion are opposed to each other. The two substrates are mechanically joined by applying a compressive load to them, thereby forming a minute space including the functional coupling surface, and at the same time bringing the functional coupling surfaces close to each other, and thereafter thinning at least one of the substrates. By doing The rigid connection is reduced, and the substrate with reduced rigidity is pressed with the pressing force of the atmospheric pressure to make the functional bonding surfaces adhere to each other. Further, the high frequency is applied from the thinned substrate side to heat the contact area, and the interface is heated. And / or further reduce the sliced substrate by the impact of ion irradiation, and at the same time promote the diffusion of atoms at the interface by the heat generated, thereby completing a more stable functional bond. . Heating is typically performed using the number 1
It is performed up to about 00 degrees.

That is, the substrate bonding method for performing micro-region bonding according to the present invention has a functional bonding surface for generating functional bonding (electrical coupling and optical coupling) and a bonding portion for providing bonding force. Forming first and second substrates made of the same or different materials, each having a bonding portion provided around a mechanically bonding surface, wherein the functional bonding surfaces of the first and second substrates and the bonding portions are opposed to each other. Then, the first and second members are joined via the joining member of the joining portion.
While mechanically bonding the substrates in a reduced-pressure atmosphere and making the functional coupling surfaces close to each other, a space including the functional coupling surface is formed in a closed space composed of the reduced-pressure atmosphere, and at least one of the closed spaces is formed. The portion of the substrate close to the closed space is thinned, and the portion of the substrate that has been made flexible by the thinning is pushed into the closed space side by the atmospheric pressure to perform the functional connection of the functional connection surface, and further, the functional connection is performed. At a portion where the heat treatment is performed, at least one of ion irradiation for performing local heating and application of a high-frequency electric field for locally performing high-frequency heating is performed while performing further thinning.

[0010] Further, the substrate bonding structures including the microregion bonding portion according to the present invention each have a functional bonding surface for generating functional bonding (electrical coupling and optical coupling) and a bonding portion for providing bonding force. The first and second substrates made of the same or different materials and provided with a bonding portion around the functional bonding surface are made to face each other with the functional bonding surfaces facing each other and the bonding portions are opposed to each other to form a bonding member of the bonding portion. After the first and second substrates are mechanically joined in a reduced-pressure atmosphere via the intermediary, and the functional coupling surfaces are brought close to each other, a space including the functional coupling surface is formed in a closed space composed of the reduced-pressure atmosphere. A portion of at least one of the substrates close to the sealed space is sliced, and the portion of the substrate which is made flexible by the thinning is pushed into the sealed space side by the atmospheric pressure to achieve a functional coupling of the functional coupling surface. At the place where the connection is achieved, Characterized in that it is constituted by performing at least one of the ion irradiation and locally high frequency electric field is applied to perform a high-frequency heating to carry out the local heating at the same time performing becomes thinned.

According to the present invention, since the substrates are joined by plastic deformation at the joining portion formed by the joining members during the application of the compressive stress, the joining can be performed at a relatively low temperature, for example, room temperature. Therefore, after joining, the functional bonding surfaces in the closed space in a reduced-pressure atmosphere are in close contact with each other at room temperature due to the pressing force of the atmospheric pressure in the atmosphere. Further, a functional coupling surface and a bonding portion are formed on one substrate, and a functional coupling surface and a bonding portion are formed on the other substrate, and thereafter, both substrates are opposed to each other, and the functional coupling surfaces are functionally coupled with each other. Since the mechanical joint force is shared between the joint portions, the functional joint area can be made extremely small. Since the region including the functional connection surface is a closed space of a reduced-pressure atmosphere, the functional connection is always achieved by pressing with the atmospheric pressure.

However, when the solid planes come into contact with each other near room temperature, the solid planes are microscopically made up of countless irregularities, so that the projections inevitably come into contact with each other, making it difficult to make contact over the entire surface. Therefore, by applying high frequency from outside to the functional coupling surface and locally heating it,
It promotes the diffusion of atoms in the functional bonding surface to generate stable functional bonding over the entire surface of the functional bonding surface. Alternatively, when thinning the substrate surface opposite to the functional bonding surface, the substrate surface is locally thinned by ion bombardment due to ion irradiation, and at the same time, the atomic diffusion of the functional bonding surface is reduced by heat generated by ion bombardment. Promotes and produces a stable functional connection over the entire functional connection surface.

In addition, even during high frequency heating or ion irradiation, the light reflected from the interface of the functional coupling surface is observed as an image on a monitor television while irradiating the functional coupling surface with light (eg, laser light). Is also possible.

The heat generated by the high-frequency heating and the ion irradiation described above is local, so that the influence on the entire substrate is extremely small. Therefore, even between substrates having different coefficients of thermal expansion, a plurality of functional coupling portions can be provided over the entire substrate without deforming the substrates, and, for example, only the electrical coupling portions can be made conductive.

By the way, for example, a thinned substrate whose rigidity is reduced by thinning a substrate having a planar electric coupling surface is pushed into a closed space side in a reduced-pressure atmosphere by a pressing force due to atmospheric pressure. In addition, it is necessary to secure an electrical insulation by forming an insulating film on the periphery other than the convex electric coupling surface at the same time, in close contact with the convex electric coupling surface of the other substrate existing in the closed space. There is.

In the above, more specifically, it can be performed as follows. In the step of forming a closed space, the joints made of the joint members made in consideration of the plastic deformation allowance in advance,
By applying a compressive stress from both sides of both substrates and mechanically joining them in the process of plastic deformation, the functional coupling surfaces are as close as possible to each other. However, even in the case of extremely close proximity, it is necessary to form a joint in consideration of the plastic deformation allowance so as not to make contact. In addition, close contact between the functional coupling surfaces which are infinitely close to each other can be achieved by the pressing force of the atmospheric pressure by thinning one of the substrates as described above, that is, by reducing the rigidity of the substrate. At this time, when the thinning is performed indefinitely (for example, about 1 μm), that is, when the thinned substrate is infinitely thin and loses rigidity, the adhesion (direct bonding) force between the functional coupling surfaces is strong. As a result, the functional bonding surfaces are more closely adhered to each other.

The substrate is typically a semiconductor substrate. In this case, the semiconductor substrate is Si, Ge, GaAs,
One of GaN, InP, SiC, AlN and compound semiconductors grown on these semiconductor substrates.

The functional coupling is typically an electrical coupling substantially free of contact resistance at the coupling surface, an optical coupling that propagates light substantially without loss at the coupling surface, or the like. Thereby, in the connection between the same or different semiconductor substrates, in the case of obtaining an electrical connection in a very small area or performing an optical connection with the substrate on which the light emitting device is formed,
It is possible to simultaneously perform the above-mentioned functional functions (electrical connection, optical connection) and the connection of the connection portion made of the connection member for providing the connection force.

The above-mentioned joining step is preferably performed in a greenhouse (about 25 ° C.).

Further, if an electrical insulating film is formed on at least one of the first substrate and the second substrate, an insulation is reliably performed at the junction, and an element structure having an electrical coupling surface is provided. Function can be improved. This insulating film is typically a Si oxide film, a Si nitride film, or an Al oxide film. First and second
An electrical insulating film may be formed on a portion other than at least one functional coupling surface of the substrate.

[0021] The joining member of the joining portion may be composed of, for example, an adhesive formed in an uneven shape on an electrical insulating film. In this case, the opposing joint portions of the first and second substrates are formed of an uneven adhesive in at least one of the substrates, and one convex adhesive is connected to the other opposing planar surface. If a mechanical joint between the first and second substrates is realized by pressing the joint between the first and second substrates, a space in which a functional joint exists simultaneously with the mechanical joint between the substrates can be formed as a closed space.

Furthermore, typically, at least one of the first and second substrates may have a slightly convex functional coupling surface.

Also, typically, the joining member is made of a material having plastic deformation ability. In this case, the material having plastic deformability is, for example, a metal material. This metal material is typically Al, Au, In, S
n, Cu, Zn, Ni or Pb. Or these alloys.

Further, if the closed space is evacuated (including a decompressed space) or is set in a decompressed state in which an atmospheric gas is replaced, it is effective to keep the functional connection long and good. The atmosphere gas is preferably a reducing gas or an inert gas such as a hydrogen gas, an argon gas, a nitrogen gas or a mixed gas thereof.

Further, by forming a plurality of functional coupling surfaces and a plurality of joints on the same substrate, many element structures can be formed on the same substrate at one time. Further, a plurality of light emitting elements having a functional connection in the closed space can be formed within a range of a length equal to the wavelength of light emission of the light emitting element. This makes it possible to extract light emitted individually from the plurality of light emitting elements as interference light. In this case, if necessary, after completion of the device, it is also possible to separate the device into each closed space.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIGS. 1, 2, 3, 4, 5, 6, and 7 show the best features of the first embodiment of the present invention. In these figures, 1 is a substrate for bonding, 2 is another substrate for bonding, 3
Is a flat surface of the substrate 2, 4 is a bonding surface composed of the plane of the substrate 1,
5 is a bonding surface on the convex portion formed on the substrate 2, 7 is an insulating film formed on the substrate 1 other than the bonding surface 4, 8 is an insulating film formed on the flat surface 3 of the substrate 2, Reference numeral 10 denotes an intermediate layer made of a metal material formed on the insulating film 7 (the intermediate layer is, for example, 40
11 is a bonding portion on the substrate 2 side made of a metal material formed on the insulating layer 8, and 12 is a substrate 1 side made of a convex metal material formed on the intermediate layer 10. (For example, formed concentrically as shown in FIG. 2), 13 is a thin substrate formed on the substrate 1 (for example, FIG.
, And has a cross-sectional shape as shown in FIG. 5), and 14 is an enclosed space (see FIG. 5) formed by joining the substrate 1 and the substrate 2 together.

Further, in FIG. 5 and FIG.
The applied load 16 for joining the substrate 1 and the substrate 2 is in non-contact with and close to the substrate 1 and covers the bonding surface 4 of the substrate 1, that is, a portion other than the thin substrate 13. A high-frequency generator for heating a bonding interface between the substrate 1 and the substrate 2;
Reference numeral 18 denotes irradiation light for irradiating a bonding interface between the substrate 1 and the substrate 2, and reference numeral 19 denotes irradiation light reflected from a bonding surface between the substrate 1 and the substrate 2 as an image (changes depending on a bonding state of the bonding surface). Reference numeral 20 denotes a monitor television for viewing an image received by the infrared camera 19.

In the above structure, a semiconductor substrate is used as one of the bonding substrates 1, and an insulating film 7 is formed on a substrate surface other than the bonding surface 4 by a photoresist process using a resist mask. 7, an intermediate layer 10 made of a metal film
Is formed. Then, a convex bonding portion 12 made of a metal material having a plastic deformability is formed on the intermediate layer 10.

Next, a semiconductor substrate is used as the other bonding substrate 2, and the periphery of the electrical coupling surface 5 is first etched in a concave shape by using a photolithography process using a resist mask. As a result, a plurality of convex electric coupling surfaces 5 are formed, and subsequently, an insulating film 8 is formed on the flat surface 3 other than the electric coupling portions 5 by the same method as described above. Further, a bonding portion 11 made of a plastically deformable metal material is formed on the insulating film 8. FIG. 4 shows this as viewed from above.

Thereafter, the electrical coupling surfaces 4 and 5 on the substrate 1 and the substrate 2 and the joints 11 and 12 are opposed to each other as shown in FIG. 1, and the direction of the arrow P as shown in FIG. , An applied load 15 is applied to the substrate 1 and the substrate 2. At this time, by application of the applied load 15, as shown in FIG. 5, the convex adhesive of the joint 12 is pressed against the flat surface of the joint 11, and undergoes a plastic deformation process. Join. By this bonding, the substrate 1 and the substrate 2 obtain strong mechanical bonding strength.

During the above-described mechanical bonding process, the bonding surface 4 of the substrate 1 and the bonding surface 5 of the substrate 2 are simultaneously in close contact with each other or in a state of being extremely close to each other. Then, during the above-mentioned mechanical joining process, the closed space 14 is formed at the same time.
The closed space 14 can be made into a reduced pressure atmosphere by performing the above-described mechanical bonding process in a reduced pressure atmosphere.

In this case, since the closed space 14 is in a reduced-pressure atmosphere, the bonding surface 4 of the substrate 1 is pressed against the bonding surface 5 of the substrate 2 at atmospheric pressure. Then, when the thin section 13 as shown in FIG. 5 is formed on the substrate 1 by using a photoresist process, the bonding surface 4 is formed due to a decrease in the rigidity of the thin section 13 as shown in FIG. Is pushed toward the insulating film 8 on the substrate 2 by the atmospheric pressure.

Therefore, even if there are a plurality of convex bonding surfaces 5 of the substrate 2, as shown in FIG.
By arranging, it is possible to avoid the electric coupling other than the coupling surface 4 and the coupling surface 5 and to establish the electric coupling only at a necessary portion.

By performing the above-mentioned mechanical joining process in a reduced-pressure atmosphere replaced with an inert gas, the sealed space 14 is removed.
In an inert gas atmosphere. Alternatively, the closed space 14 can be made into a reducing gas atmosphere by a similar method.

In the next step, only the bonding surface layer is heated by high frequency. That is, as shown in FIG. 6, the high-frequency heater 17 is installed above the substrate 1, and a shielding plate 16 for shielding high-frequency is placed between the high-frequency heater 17 and the substrate 1. However, since the shielding plate 16 has a hole only at the portion of the thin substrate portion 13 as shown in FIG. 6, the high frequency passes through the hole and acts on the thin substrate portion 13. In this way, the surface of the flake substrate portion 13 is heated by high frequency,
Then, the bonding interface between the bonding surface 4 and the bonding surface 5 located near the surface is similarly heated. At this time, the region other than the thin substrate portion 13 of the substrate 1 is not heated because the high frequency is blocked by the shielding plate 16.

When only the region of the lamella substrate portion 13, that is, only the bonding interface is locally heated, it is preferable that the state of the bonding interface photographed by the infrared camera 19 is simultaneously observed on the monitor television 20. In this observation, the laser light 18 is locally applied to a portion of the bonding interface where it is found that the bonding is not sufficient, and this portion is locally heated using the heat of absorption of the laser light 18.

The above method is continued until the electrical connection at the bonding interface reaches the intended value in the measured value. According to this method, the electrical coupling area at the coupling interface between the coupling surface 4 and the coupling surface 5 is further enlarged as compared with the close contact at the time of the mechanical coupling, and more stable characteristics can be obtained.

In this embodiment, p-InP is used for the substrate 1 and n-InP (having a laser structure; not shown) is used for the substrate 2, and a film is formed on the surfaces of the substrate 1 and the substrate 2 in advance. Some (not shown) electrical coupling of p-InP, ie, I
A pp junction between nPs was performed. With this type of solid-state bonding, a laser structure can be established. However, electrical coupling on a minute surface required for injecting a constriction current (to lower a threshold) into an active layer formed by a film forming method such as MBE may not be easily realized. . In addition, in the vicinity of a distance equal to or shorter than the wavelength of the oscillating laser light, electrical coupling on a plurality of separate micro surfaces as shown in FIG. 6 may not be easily realized. It is good to use a method.

The substrates 1 and 2 are made of a material other than InP, for example, Si, Ge, GaAs, GaN, Si
It is also possible to perform joining (electrical coupling) by combining C and AlN or by combining different materials of these materials.

In the present embodiment, the bonding member is formed by plating, but may be formed by another method, for example, vacuum evaporation.

Further, in this embodiment, Au is used as the joining member, but other materials having plastic deformability may be used. For example, Al, Sn, In, Cu, Z
n, Pb, etc., or their alloys can be used similarly.

Further, in this embodiment, the Si oxide film is used as the insulating film. However, an Al oxide film or a Si nitride film can be used instead.

Further, in this embodiment, a copper plate is used as the high frequency shielding plate, but any conductive substrate may be used. In addition, for example, Al, Sn, Zn and the like may be used, and these are rich in plasticity and easy to use.

Further, in the present embodiment, A
Although an r laser was used, for example, a YAG laser, a carbon dioxide laser, a helium neon laser, an excimer laser, or the like can also be used.

The same can be said for the replacement in the second embodiment.

According to this method, the laser structure (active layer, I
An electrode was arranged on the nGaAsP) to realize the electrical coupling in the minute region, and a voltage was applied between the two substrates. As a result, light emission was observed.

Further, a mirror was formed on the thin substrate portion 13 (not shown), and a voltage was applied between the two substrates in the same manner as described above.

The present invention is also applicable to a case where a GaAs structure (including an active layer, not shown) is provided on the substrate 2. Further, in this embodiment, a substrate having a laser structure is used as the substrate 2, but the present invention can be applied to a case where a substrate having a laser structure is used as the substrate 1.

(Embodiment 2) FIGS. 2, 3, 8, 9, 10, 11, and 12 show the features of the second embodiment of the present invention. In the same figure, the same reference numerals as those described in the first embodiment denote parts having the same function.
In these figures, 5 is a convex bonding surface different from that of the first embodiment fabricated on the substrate 2, 6 is a terrace near the periphery of the convex bonding surface 5, and 8 is a flat surface 3 of the substrate 2. An insulating film formed on the insulating film 8 on the terrace 6; an intermediate layer 9 made of a metal material formed on the insulating film 8;
Is an irradiation ion for further thinning, 22 is an ion gun, and 23 is a mirror.

In the above structure, similar to the first embodiment,
A semiconductor substrate is used as one of the bonding substrates 1, and an insulating film 7 is formed on a substrate surface other than the bonding surface 4 by a photoresist process using a resist mask, and an intermediate metal film is formed on the insulating film 7. Layer 10 is deposited and further intermediate layer 1
A convex joint portion 12 made of a metal material having plastic deformability is formed on zero.

Next, using a semiconductor substrate as the other bonding substrate 2, first, the periphery of the electrical coupling surface 5 is etched into a concave shape using a photoresist process, and a flat portion near the periphery of the coupling surface 5 is terraced 6. And Further, the outer periphery of the terrace 6 is etched in a concave shape by using a photoresist process.

As a result of the above-described process, a convex electric coupling surface 5 and a terrace 6 are formed.
In addition, as shown in FIG. 8 and FIG. 9, a plurality of bonding surfaces 5 and terraces 6 are respectively formed using a photoresist process.
It is formed in the same closed space 14.

Thereafter, an electric insulating film 8 is formed on the substrate 2 in a region other than the bonding surface 5 through a photolithography process, a film forming process, and a lift-off process, and further through the same process as described above. The bonding part 11 was formed into a film.

When the insulating film 8 is formed, the terrace 6
The upper insulating film 8 is set at the same height as the bonding surface 5 or
It is preferable to form a lower film.

Next, as shown in FIG. 10, alignment is performed so that the bonding surface 4 of the substrate 1 and the bonding surface 5 of the substrate 2 are opposed to each other. Act between the two.

Thus, the bonding portion 12 of the substrate 1 and the substrate 2
Are joined during the plastic deformation process by application of an applied load 15. By joining, as seen in FIG.
A space region surrounded by the substrate 1, the substrate 2, the bonding portion 11 and the bonding portion 12 becomes a closed space 14, and at the same time, the bonding surface 4 of the substrate 1 and the plurality of convex bonding portions 5 of the substrate 2 are in a state of being in close contact with each other. Leads to the near state.

The bonded sample is taken out of the reduced-pressure atmosphere into the air. Thereafter, as shown in FIG. 10, the region of the substrate 1 opposite to the bonding surface 4 is removed to form a thin substrate 13. The lamella substrate portion 13 whose rigidity has been reduced in the lamella-forming step is pushed into the closed space 14 by the atmospheric pressure. By this pushing, the bonding surface 4 and the bonding surface 5 are more firmly adhered to each other, and an electrical connection is obtained. At this stage, the electrical coupling state between the substrate 1 and the substrate 2 can be confirmed from an I (current) -V (voltage) diagram.

Next, in order to increase the electrical coupling area, as shown in FIG.
Sample No. 3 was further thinned by ion sputtering using an ion gun 22, and was simultaneously locally heated with heat generated by ion irradiation. Then, the electrical coupling region of the thin substrate 13 further thinned by the thinning step is irradiated with the irradiation light 18, and the reflected light from the bonding interface between the bonding surface 4 and the bonding surface 5 is captured by the infrared camera 19. And observed on the monitor TV 20 as an image. FIG. 11 shows the state of the electrical coupling region at this time. Again, the electrical coupling state is I
It can be confirmed by a (current) -V (voltage) diagram.

The above series of steps is repeated. That is, the thinning of the sliced substrate 13 and the irradiation of the irradiation light 18 are continued until more stable characteristics are obtained. After obtaining stable characteristics, a mirror 23 is formed on the thin substrate 13 of the bonded sample as shown in FIG.

In this embodiment, a light-emitting layer is formed on an epitaxial layer (not shown) including an active layer formed on the InP substrate 2, and a convex tip surface is used as an electrical coupling surface 5.
As one of the electrodes, there is one in which a flat portion of the GaAs substrate 1 is used as an electric coupling surface 4. After bonding the substrate 1 and the substrate 2 to each other as described above and confirming the electrical coupling, FIG.
As shown in FIG. 2, a conductive semiconductor mirror was formed on the substrate 1. In this embodiment, the laser structure (the active layer is InGa
When electrodes (not shown) were attached to 10 pairs of GaAs / AlAs for AsP and mirrors, and a voltage was applied between these electrodes, light emission was observed.

In this embodiment, after forming the joined body,
Although the mirror is formed, the tip of an epitaxial layer (not shown) made of a conductive semiconductor mirror electrode may be used as the electrical coupling surface 4.

In this embodiment, Ar ions are used as the irradiation ions. However, for example, Kr ions or the like can also be used.

[0064]

As described above, according to the present invention,
Forming first and second substrates of the same or different materials, each having a functional bonding surface for providing a functional bond and a bonding region comprising a bonding layer for providing bonding force; The functional bonding surfaces on the substrate are made to face each other and the bonding layers are opposed to each other, and mechanically bonded by applying a load in a reduced-pressure atmosphere via the bonding layers, and the functional bonding surfaces are in close contact with each other,
Or make it near. This joining forms a closed space consisting of a reduced-pressure atmosphere, and a functional connection exists in the closed space. Thereafter, the surface of the substrate opposite to the functional connection surface of at least one substrate is thinned to reduce rigidity. Due to the thinning, the functional bonding surfaces are more closely adhered to each other by the atmospheric pressure, and at the same time, further thinning by ion irradiation and improvement of the functional bonding surface by heating and further improvement of the functional bonding surface by high frequency heating. It will be easier to make improvements. Then, due to the heat generated by ion irradiation on the functional bonding surface and the high-frequency heating, atom diffusion (interface diffusion) occurs in a direction that eliminates voids at the bonding interface, so that a stronger and more stable functional bond can be achieved. realizable.

Furthermore, while observing the characteristics of the functional joint while locally heating in a state where the thinning and the rigidity are reduced by ion irradiation, when the best stable characteristics are generated, This is a method that enables functional coupling in a minute area by stopping irradiation or high-frequency heating.

From the above, the following effects can be obtained. 1. Functional bonding can be performed in a minute area at room temperature, and sufficient bonding strength between substrates can be obtained. 2. In a decompressed atmosphere, the functional joint surface is sealed in the depressurized closed space by mechanical joining around the functional joint surfaces, and then the substrate is thinned, and the functional joint surface is brought into close contact with the atmospheric pressure. Therefore, it is possible to avoid excessive stress concentration at the joint surface. 3. A plurality of electrical coupling surfaces can be formed within the same decompressed closed space at a distance within the wavelength of light.

4. After the functional bonding surfaces are brought into close contact with each other, the functional bonding surfaces are heated by high-frequency heating, or heat is generated in the thinning process by ion irradiation to promote the surface diffusion and interface diffusion of atoms. Functional binding can be made more stable. Since a heating source for heating the whole like an electric furnace is not required, functional coupling in a minute area can be realized regardless of a difference in thermal expansion coefficient between substrates. 5. The inside of the sealed space including the functional connection surface can be set to a reduced pressure atmosphere, a reduced pressure atmosphere by the replacement of inert gas, or a reduced pressure atmosphere by the replacement of the reducing gas.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a cross section of both substrates before a load is applied according to a first example of the present invention.

FIG. 2 is a view on arrow A in FIGS. 1 and 8;

FIG. 3 is a view as seen from the arrow B in FIGS. 5 and 10;

FIG. 4 is a view taken in the direction of the arrow C in FIG. 1;

FIG. 5 is a diagram illustrating a cross section of both substrates in close contact bonding when a load is applied according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a cross section of both substrates in an electrical coupling improvement process by high-frequency heating according to the first embodiment of the present invention.

FIG. 7 is a core diagram of a portion D in FIG. 6;

FIG. 8 is a diagram illustrating a cross section of both substrates before a load is applied according to a second embodiment of the present invention.

FIG. 9 is a view as seen from an arrow E in FIG. 8;

FIG. 10 is a cross-sectional view in an electrical coupling improvement process by ion irradiation and light irradiation according to a second embodiment of the present invention.

FIG. 11 is an enlarged view of a portion F in FIG. 10;

FIG. 12 is a diagram illustrating a cross section of a laser structure according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 2 Substrate 3 Flat surface 4, 5 Coupling surface 6 Terrace 7, 8 Insulating film 9, 10 Intermediate layer 11, 12 Joint part 13 Thin substrate 14 Sealed space 15 Applied load 16 Shielding plate 17 High frequency generator 18 Irradiation light 19 Infrared Camera 20 Monitor TV 21 Irradiated ions 22 Ion gun 23 Mirror

Claims (28)

[Claims] A first and a second material of the same or different kind, each having a functional coupling surface for producing a functional coupling and a joint for providing a joining force, and having a joint around the functional coupling surface. The second substrate is formed, and the functional bonding surfaces of the first and second substrates and the bonding portions are opposed to each other.
And the second substrate are mechanically joined in a reduced-pressure atmosphere, and while the functional coupling surfaces are brought close to each other, a space including the functional coupling surface is formed in a closed space composed of the reduced-pressure atmosphere. Thinning a portion of at least one of the substrates in the vicinity of the sealed space, and pressing a portion of the substrate, which has been made flexible by the thinning, into the sealed space side by atmospheric pressure to achieve a functional connection of a functional connection surface; A substrate for bonding a small area, characterized by performing at least one of ion irradiation for performing local heating and applying high frequency electric field for locally performing high frequency heating while performing further thinning at a location where a mechanical coupling is achieved. Join method. 2. The substrate bonding method according to claim 1, wherein the first and second substrates are formed so as to have a plurality of functionally connected portions in one closed space. 3. A light-emitting device is formed by joining the first and second substrates, and a plurality of functionally coupled portions are within a distance equal to or less than the wavelength of light emitted from the light-emitting device. 3. The method according to claim 2, wherein the first and second substrates are formed so as to form a substrate. 4. The first and second substrates are formed so that one or more sealed spaces are formed by joining the first and second substrates. Or the substrate bonding method according to 3. 5. The substrate bonding method according to claim 1, wherein a shielding plate is used as a mask so as to enable ion irradiation only at a portion where a functional connection is achieved. 6. A high-frequency heating of only a portion having a functional connection, a shielding plate made of a conductor for shielding a high-frequency electric field is used at a portion other than the portion having a functional connection. Item 6. The substrate bonding method according to any one of Items 1 to 5. 7. The method according to claim 1, wherein the substrate is a semiconductor substrate. 8. The semiconductor substrate is made of Si, Ge, GaAs, Ga.
The substrate bonding method according to claim 7, wherein the substrate is any one of N, InP, SiC, AlN, and a compound semiconductor formed on these semiconductor substrates. 9. The method according to claim 1, wherein at least one of the first and second substrates includes:
9. The method according to claim 1, further comprising a thin film layer that can be an active layer of the semiconductor laser. 10. The substrate bonding method according to claim 1, wherein an electrical insulating film is formed at a portion other than at least one of the functional bonding surfaces of the first and second substrates. . 11. The substrate bonding method according to claim 1, wherein at least one of the first and second substrates has a functional connection surface formed as a convex-shaped flat surface. 12. The method according to claim 1, wherein the joining member of the joining portion is made of a material having a plastic deformation ability. 13. The method according to claim 12, wherein the joining member of the joining portion is made of metal. 14. The reduced pressure atmosphere is an inert gas, a reducing gas, or a mixed gas thereof.
14. The substrate bonding method according to any one of items 13 to 13. 15. The method according to claim 14, wherein the reduced pressure atmosphere is an argon gas, a nitrogen gas, a hydrogen gas, or a mixed gas thereof. 16. A first and a second material of the same or different kind, each having a functional connection surface for producing a functional connection and a joint for providing a bonding force and having a joint around the functional connection surface. The first and second substrates are mechanically joined in a reduced-pressure atmosphere via the joining member of the joining portion, with the functional coupling surfaces of the second substrate facing each other and the joining portions facing each other, and the functional joining is performed. After forming the space including the functional coupling surface in a closed space made of a reduced-pressure atmosphere while bringing the surfaces close to each other, the portion of at least one of the substrates that is close to the closed space is sliced, and the flexible substrate is thinned. The part is pushed into the closed space side by atmospheric pressure to achieve the functional connection of the functional connection surface, and furthermore, at the place where the functional connection is achieved, further thinning and local heating are performed simultaneously with ion irradiation and local irradiation High-frequency heating to high frequency Substrate binding structure containing minute domains junction, characterized in that it is constructed by performing at least one of the electric field application. 17. The substrate coupling structure according to claim 16, wherein the first and second substrates are formed so as to have a plurality of functional coupling points in one closed space. 18. A light emitting device is formed by joining the first and second substrates, and a plurality of functionally coupled portions are located within a distance equal to or less than the wavelength of light emitted from the light emitting device. 18. The substrate coupling structure according to claim 17, wherein the first and second substrates are formed so as to form a substrate. 19. The first and second substrates are formed so that one or more sealed spaces are formed by joining the first and second substrates. Or 1
9. The substrate bonding structure according to 8. 20. The substrate coupling structure according to claim 16, wherein said substrate is a semiconductor substrate. 21. A semiconductor substrate comprising Si, Ge, GaAs, G
21. The substrate bonding structure according to claim 20, wherein the substrate bonding structure is any one of aN, InP, SiC, AlN, and a compound semiconductor formed on the semiconductor substrate. 22. The substrate-coupling structure according to claim 16, wherein a thin film layer that can be an active layer of a semiconductor laser is provided in at least one of the first and second substrates. . 23. The substrate according to claim 16, wherein an electrical insulating film is formed at a portion other than at least one of the functional coupling surfaces of the first and second substrates. Combined structure. 24. The substrate coupling structure according to claim 16, wherein a functional coupling surface of at least one of the first and second substrates is a convex-shaped flat surface. 25. The substrate-coupling structure according to claim 16, wherein the bonding member at the bonding portion is made of a material having plastic deformation ability. 26. The substrate coupling structure according to claim 25, wherein the joining member of the joining portion is made of metal. 27. The reduced pressure atmosphere is an inert gas, a reducing gas or a mixed gas thereof.
27. The substrate bonding structure according to any one of 6 to 26. 28. The substrate bonding structure according to claim 27, wherein the reduced pressure atmosphere is an argon gas, a nitrogen gas, a hydrogen gas, or a mixed gas thereof.