JP6986105B2 - Permanent bonding method of wafer - Google Patents

Description

The present invention relates to the method of joining the first contact surface of the first substrate to the second contact surface of the second substrate according to the first aspect.

The purpose of permanent or irreversible bonding of substrates is to produce the strongest possible and particularly irreversible interconnection between the two contact surfaces of the substrate, and thus high bonding force. In the prior art, there are various methods and manufacturing methods for such joining.

Known manufacturing methods and methods that have been practiced to date are often impossible or fully reproducible, and can be mostly applied, especially when conditions change. Can not. In particular, currently used manufacturing methods often use high temperatures, especially above 400 ° C., to ensure reproducible results.

Technical problems such as high energy consumption and the risk of destroying the structures present on the substrate have been required for high bonding forces to date, partly well above 300 ° C. It is the result of higher temperatures. The following Patent Document 1 shows a method of low temperature bonding. Further joining methods are shown in Patent Documents 1 to 8 below.

Other requirements include-front-end-of-line intercompatibility, which is defined as process intercompatibility during the manufacture of electrically active components. Will be done. Therefore, the joining process must be designed so that active components such as transistors already present on the structure wafer are not adversely affected or damaged during processing. Criteria for intercompatibility include mainly the purity of chemical elements (mainly in CMOS structures) and mainly mechanical load bearing capacity due to thermal stress.
− Low pollution − No force

The reduced bonding force requires more careful handling of the structural wafers, thus reducing the probability of breakage due to direct mechanical loads.

International Publication No. 01/61743 Pamphlet U.S. Patent Application Publication No. 2003/809950 U.S. Patent Application Publication No. 2002/0048900 U.S. Patent Application Publication No. 2008/0006369 U.S. Pat. No. 5,451,547 European Patent Application Publication No. 0584778 U.S. Pat. No. 5,427,638 Japanese Unexamined Patent Publication No. 5-166690

Therefore, it is an object of the present invention to devise a method for carefully manufacturing a permanent bond having the highest possible bonding force.

This object is achieved by the features described in aspect 1. Advantageous developments of the invention are described in subordinate embodiments. Any combination of at least two of the features described herein, claims, and at least one of the drawings is also within the framework of the invention. Within a given value range, values within the indicated limits are also disclosed as boundary values and are claimed in any combination.

The underlying idea of the present invention is to come up with a reservoir for holding the first raw material on at least one of the substrates, and the first raw material is present in the other substrate. The reaction is carried out after the substrates having the raw materials of the above are brought into contact with each other or after being temporarily bonded to form an irreversible bond or a permanent bond between the substrates. Cleaning of the substrate is generally performed, especially by the flushing step, before or after forming the reservoir in one surface layer on the first contact surface. This cleaning should generally ensure that the particles are not present on the surface, and the presence of such particles will result in unbonded spots. After the temporary or reversible junction is formed by the reservoir and the raw materials contained in the reservoir, the reaction that strengthens the permanent junction directly on the contact surface and increases the junction speed in a controlled manner is particularly the contact surface. At least one of the above, preferably, the technical possibility of being induced by deforming the contact surface facing the reservoir by the reaction is obtained.

There are various possibilities for the purpose of creating a weak interaction between the contact surfaces of the substrates as a temporary bonding step for forming a temporary or reversible bond between the substrates. The strength of the temporary bond is lower than the strength of the permanent bond, which is at least 1/2 to 1/3, particularly 1/5, preferably 1/15, and more preferably 1/25. As a guide value, the provisional bonding strength pure deactivation hydrophilic silicon is about 100 mJ / m ^2, the temporary bonding strength of a pure plasma activation hydrophilic silicon is about 200~300mJ / m ^2. Temporary bonding between molecular-wetted substrates is achieved by van der Waals interactions between molecules on different sides of the substrate. Therefore, molecules with predominantly permanent dipole moments are suitable for allowing temporary bonding between wafers. The following chemical compounds are given as examples as interconnectors, but are not limited thereto.
− Water − Thiol − AP3000
− Silane and / or − Silanol

A suitable substrate according to the present invention is capable of reacting the material as a raw material with a separately supplied raw material to form a product having a higher molar volume, resulting in a growth layer on the substrate. Is the substrate on which is formed. The following combinations are particularly advantageous, with raw materials listed on the left side of the arrow and products listed on the right side of the arrow, but the supplied raw materials or by-products that react with the listed raw materials are individual. Not listed in.
− Si → SiO ₂ , Si ₃ N ₄ , SiN _x O _y
− Ge → GeO ₂ , Ge ₃ N ₄
− Α − Sn → SnO ₂
− B → B ₂ O ₃ , BN
− Se → SeO ₂
− Te → TeO ₂ , TeO ₃
− Mg → MgO, Mg ₃ N ₂
− Al → Al ₂ O ₃ , Al N
− Ti → TIO ₂ , TiN
− V → V ₂ O ₅
− Mn → MnO, MnO ₂ , Mn ₂ O ₃ , Mn ₂ O ₇ , Mn ₃ O ₄
− Fe → FeO, Fe ₂ O ₃ , Fe ₃ O ₄
− Co → CoO, Co ₃ O ₄
− Ni → NiO, Ni ₂ O ₃
− Cu → CuO, Cu ₂ O, Cu ₃ N
− Zn → ZnO
− Cr → CrN, Cr ₂₃ C ₆ , Cr ₃ C, Cr ₇ C ₃ , Cr ₃ C ₂
− Mo → Mo ₃ C ₂
− Ti → TiC
− Nb → Nb ₄ C ₃
− Ta → Ta ₄ C ₃
− Zr → ZrC
− Hf → HfC
− V → V ₄ C ₃ , VC
− W → W ₂ C, WC
− Fe → Fe ₃ C, Fe ₇ C ₃ , Fe ₂ C

As a substrate, a mixed type of the following semiconductors is also conceivable.
-III-V: GaP, GaAs, InP, InSb, InAs, GaSb, GaN, AlN, InN, Al _x Ga _1-x As, In _x Ga _1-x N
-IV-IV: SiC, SiGe
-III-IV: InAlP
-Nonlinear optics: LiNbO ₃ , LiTaO ₃ , KDP (KH ₂ PO ₄ )
-Solar cells: CdS, CdSe, CdTe, CuInSe ₂ , CuInGaSe ₂ , CuInS ₂ , CuInGaS ₂
-Conductive oxide: In _2-x Sn _x O _3-y

As claimed in the present invention, a storage unit capable of storing at least one of the raw materials supplied for the volume expansion reaction directly on at least one of the wafers and on each contact surface in a certain amount. There is. Therefore, the raw material may be, for example, O ₂ , O ₃ , H ₂ O, N ₂ , NH ₃ , H ₂ O ₂ , or the like. Possible gaps, holes, and cavities between contact surfaces are minimized, and thus between substrates in these regions, based on the tendency of reaction partners to reduce the energy of the system, especially due to the expansion caused by oxide growth. As the distance decreases, the bonding force increases. In the best possible case, the existing gaps, holes, and cavities are completely closed, resulting in an increase in the overall bonding area and correspondingly increased bonding force as claimed in the present invention.

The contact surface usually exhibits a root mean square roughness (Rq) of 0.2 nm. This corresponds to a peak-to-peak value on the surface in the 1 nm range. These empirical values were determined using atomic force microscopy (AFM).

The reaction claimed in the present invention is the wafer surface of a conventional circular wafer having a diameter of 200 to 300 mm and having one single molecular layer (ML) of water, in which the growth layer is grown only from 0.1 to 0.3 nm. Suitable for making it possible.

Therefore, as claimed in the present invention, in particular, at least 2 ML, preferably at least 5 ML, more preferably 10 ML of fluid, particularly water, is stored in the reservoir.

It is particularly preferable to form the reservoir by plasma exposure, because plasma exposure further results in smoothing and hydrophilicization of the contact surface as a synergistic effect. The surface is smoothed by plasma activation, mainly by the viscous flow of the surface layer material. The increase in hydrophilicity is caused by an increase in silicon hydroxyl group bonds, particularly by decomposition of Si—O bonds present on the surface of Si—O—Si or the like, particularly according to the reaction represented by the following chemical formula (1). ..

In particular, another side effect obtained as a result of the above-mentioned action is that the temporary bonding strength is particularly improved by 2 to 3 times.

The reservoir in the surface layer on the first contact surface of the first substrate is formed, for example, by plasma activation of the first substrate coated with a thermal oxide. Plasma activation is performed in a vacuum chamber so that the conditions required for the plasma can be adjusted. As patented in the present invention, N ₂ gas, O ₂ gas, or argon gas is used as the plasma discharge in the range of 0 to 2000 eV ionic energy, resulting in the reservoir being the treated surface, in this case. Is formed up to a depth of 20 nm on the first contact surface, preferably up to 15 nm, more preferably up to 10 nm, and most preferably up to 5 nm. As claimed in the present invention, at least one of the respective particle types, atoms, and molecules suitable for forming the reservoir can be used. Preferably, atoms and / or molecules that can be formed so that the reservoir has the required properties are used. Related properties are primarily pore size, pore distribution, and pore density. Alternatively, as claimed in the present invention, air or a mixed gas such as a forming gas consisting of _{95% Ar and 5% H 2 can be used, for example.} Depending on the gas used, there are especially N ⁺ , N ₂ ⁺ , O ⁺ , O ₂ ⁺ , and Ar ⁺ ions in the reservoir during the plasma treatment. The first raw material can be accommodated in an unoccupied free space.

The reservoir is formed based on the following considerations. The pore diameter is less than 10 nm, preferably less than 5 nm, more preferably less than 1 nm, still more preferably less than 0.5 nm, and most preferably less than 0.2 nm.

The pore density is preferably directly proportional to the density of the particles that produce pores by impact, and most preferably varies depending on the partial pressure of the impact species and also depending on the processing time and, in particular, the parameters of the plasma system used. You can also do it.

The pore distribution preferably has at least one region with the highest pore density under the surface, and by varying the parameters of some such regions, the regions overlap to form a preferably flat-shaped region (preferably flat-shaped regions). See FIG. 7). The pore distribution decreases to zero as the thickness increases. The region near the surface during impact has a pore density approximately the same as the pore density near the surface. After the plasma treatment is complete, the pore density on the surface can be reduced as a result of the stress relaxation mechanism. The pore distribution in the thickness direction has steep sides to the surface and is rather flatter to the bulk, but has continuously diminishing sides (see FIG. 7).

Similar considerations apply to any method that is not performed with plasma in terms of pore size, pore distribution, and pore density.

Reservoir can be designed by controlling, using and combining process parameters. FIG. 7 shows the concentration of nitrogen atoms injected by plasma as a function of the penetration depth into the silicon oxide layer. It was possible to obtain two profiles by varying the physical parameters. The first profile 11 is formed by the faster accelerated atoms penetrating deeper into the silicon oxide, whereas the profile 12 is formed after changing the process parameters to a lower density. .. By superimposing the two profiles, the sum 13 of the curves is obtained, and this curve becomes the characteristic of the reservoir. The relationship between the concentrations of the injected atomic and / or molecular species is clear. Higher concentrations indicate areas of the structure with more defects and therefore more space to accommodate subsequent raw materials. By controlling the process parameters in a dedicated manner during plasma activation, it is possible to realize a reservoir in which the added ions are distributed as uniformly as possible over the depth by continuously changing the process parameters.

It is conceivable to use a TEOS (tetraethyl orthosilicate) oxide layer on at least one of the substrates, at least on the first substrate, as a reservoir or instead of a reservoir formed by plasma. This oxide is generally not as dense as a thermal oxide, which is why it is advantageous to compress as claimed in the present invention. The compression is performed by heat treatment for the purpose of adjusting the porosity of the reservoir to the specified porosity.

According to one embodiment of the present invention, the filling of the reservoir can be performed at the same time as the formation of the reservoir by applying the reservoir as a coating to the first substrate, particularly advantageously, for the coating. Already contains the first raw material.

The reservoir is as a porous layer with porosity in the nanometer range, or less than 10 nm, more preferably less than 5 nm, even more preferably less than 2 nm, most preferably less than 1 nm, most preferably less than 0.5 nm of all. Can be considered as a layer having channels with a channel width of.

Regarding the step of filling the reservoir with the first raw material or the first raw material group, the following embodiments and combinations thereof can be considered as claimed in the present invention.
− The step of exposing the reservoir to the surrounding atmosphere − The step of flushing with deionized water in particular − The step of flushing with the raw material, especially _{the fluid containing H 2} O, H ₂ O ₂ and NH ₄ OH, or the fluid consisting of those raw materials. -Steps to expose the reservoir to any gas atmosphere, especially atomic gas, molecular gas, mixed gas-Steps to expose the reservoir to an atmosphere containing steam or hydrogen vapor, and-A reservoir already filled with raw materials. Is deposited on the first substrate as a surface layer.

At least one of the compounds O ₂ , O ₃ , N ₂ , NH ₃ , H ₂ O, H ₂ O ₂ , and NH ₄ OH can be considered as raw materials.

The use of hydrogen peroxide vapor mentioned above is considered a preferred version in addition to the use of water. Hydrogen peroxide further has the advantage of having a higher oxygen to hydrogen ratio. Furthermore, hydrogen peroxide dissociates into hydrogen and oxygen when a high frequency electromagnetic field above a certain temperature and / or in the MHz range is used.

According to one advantageous embodiment of the present invention, the formation of the growth layer and the strengthening of the irreversible bonding are carried out by diffusing the first raw material into the reaction layer.

According to another advantageous embodiment of the invention, the formation of irreversible junctions is typically less than 300 ° C, preferably less than 200 ° C, more preferably less than 150 ° C, even more preferably less than 100 ° C. It is intended to be carried out most preferably at room temperature, in particular up to 12 days, more preferably up to 1 day, even more preferably up to 1 hour, most preferably up to 15 minutes.

In this specification, irreversible joining 1.5 J / m ^2, greater than especially 2J / m ² greater, preferably particularly advantageous with a bonding strength of 2.5 J / m ² greater.

Bonding strength is particularly advantageously increased during the reaction by forming in the reaction layer a product having a molar volume greater than the molar volume of the second raw material, as claimed in the present invention. Can be made to. In this way, growth is triggered on the second substrate, and as a result, the gaps between the contact surfaces can be closed by a chemical reaction as claimed in the present invention. As a result, the distance between the contact surfaces, and thus the average distance, is reduced and dead space is minimized.

The formation of the reservoir is by plasma activation, especially with an activation frequency between 10 and 600 kHz, and / or ^{an output density between 0.075 and 0.2 watts / cm 2} , and / or 0.1 to 0. Additional effects such as smoothing of the contact surface and a clear increase in the hydrophilicity of the contact surface can be obtained as long as it is carried out under pressure with a pressure of between .6 mbar.

Alternatively, the formation of the reservoir claimed in the present invention can also be performed by using, in particular, a tetraethoxysilane oxide layer compressed in a controlled form to a certain porosity as the surface layer.

According to another advantageous embodiment of the invention, the surface layer is mainly composed of silicon dioxide produced, especially essentially completely, especially amorphous, especially by thermal oxidation, and the reaction layer is an oxidizable material. In particular, it is intended primarily and preferably composed entirely of Si, Ge, InP, GaP, or GaN. A particularly stable reaction that closes existing gaps particularly effectively is made possible by oxidation.

As claimed herein, it is particularly advantageous to have a growth layer of predominantly natural silicon dioxide between the second contact surface and the reaction layer. This growth layer undergoes growth caused by the reaction claimed in the present invention. This growth proceeds from the transition Si-SiO ₂ (7) _{by the reformation of the amorphous SiO 2} , whereby on the interface of the growing layer, especially with the reaction layer, and especially with the first contact surface and the second. Deformation, especially swelling, occurs in the gap region between the contact surface of the silicon. Therefore, the distance between the two contact surfaces is reduced or the dead space is reduced, and as a result, the bonding strength between the two substrates is increased. Temperatures between 200 and 400 ° C., preferably between about 200 ° C. and 150 ° C., more preferably between 150 ° C. and 100 ° C., most preferably between 100 ° C. and room temperature are particularly advantageous.

It is particularly advantageous herein that the growth layer has an average thickness A between 0.1 nm and 5 nm before forming an irreversible bond. The thinner the growth layer, the faster and easier the reaction between the first and second raw materials via the growth layer, especially by diffusing the first raw material into the reaction layer via the growth layer. Will be done in.

According to one embodiment of the invention, the formation of reservoirs is advantageous if carried out in vacuum. Therefore, it is possible to prevent the reservoir from being contaminated by unwanted materials or compounds.

In another embodiment of the invention, the filling of the reservoir is
-A step of exposing the first contact surface to the atmosphere in order to fill the reservoir with moisture in the atmosphere and / or oxygen contained in the air.
-A step in which the first contact surface is exposed to a fluid consisting particularly primarily, preferably almost completely, particularly deionized H ₂ O and / or H ₂ O _2.
-First contact surface with at least one of N ₂ gas, O ₂ gas, Ar gas, and forming gas, especially _{forming gas consisting of 95% Ar and 5% H 2} , especially ion energy. Steps in the range of 0 to 2000 eV,
-Performed by one or more of the steps of evaporating any of the previously named raw materials to fill the reservoir.

The reservoir is preferably between 0.1 nm and 25 nm, more preferably between 0.1 nm and 15 nm, more preferably between 0.1 nm and 10 nm, and most preferably between 0.1 nm and 5 nm. Formed in, is particularly useful for process sequences. Further, according to one embodiment of the present invention, the average distance B between the reservoir and the reaction layer immediately before forming an irreversible junction is between 0.1 nm and 15 nm, particularly between 0.5 nm and 5 nm. Between, preferably between 0.5 nm and 3 nm, is advantageous.

The device for carrying out the method claimed in the present invention is provided in particular for forming a reservoir, a chamber specifically provided for filling the reservoir, and a temporary junction. The chambers are formed and all of these chambers are directly connected to each other via a vacuum system.

In another embodiment, the reservoir filling can also be done directly by the atmosphere and thus in a chamber that can be open to the atmosphere, or without a wafer, but semi-automatically and / or. It can also be easily done on a structure that can handle the wafer completely automatically.

Other advantages, features, and details of the invention will be apparent by using the following description and drawings of exemplary preferred embodiments.

It is a figure which shows the 1st step of the method of claiming a patent in this invention immediately after contacting a 1st substrate with a 2nd substrate. It is a figure which shows the other step of the method of claiming a patent in this invention for forming a higher bond strength. It is a figure which shows the other step of the method of claiming a patent in this invention for forming a higher bond strength. FIG. 1 is a diagram illustrating another step of the method of claiming the invention, in which the contact surfaces of the substrates are in contact, following the steps described in FIGS. 1, 2a and 2b. It is a figure which shows the step which claims the patent in this invention for forming an irreversible bond / permanent bond between substrates. 3 is an enlarged view of a chemical / physical process going on on two contact surfaces during the steps described in FIGS. 3 and 4. 3 is another magnified view of the chemical / physical process proceeding on the interface between the two contact surfaces during the steps described in FIGS. 3 and 4. It is a graph which shows the manufacture of the storage part which claims the patent in this invention.

In the figure, the same component / mechanism and the component / mechanism having the same action are identified by the same reference number.

In the situation shown in FIG. 1, the chemistry that progresses between the first contact surface 3 of the first substrate 1 and the second contact surface 4 of the second substrate 2 during or immediately after the temporary joining step. Only part of the reaction is shown. This surface has polar OH groups at the ends and is therefore hydrophilic. The first substrate 1 and the second substrate 2 have an _{attractive force due to a hydrogen bond between an OH group existing on the surface and an H 2} O molecule, and an attractive force due to a hydrogen bond between the H ₂ O molecule alone. Held by. At least the hydrophilicity of the first contact surface 3 is increased by the plasma treatment of the first contact surface 3 in the preceding step.

The reservoir 5 in the surface layer 6 made of hot silicon dioxide is formed by plasma treatment as claimed in the present invention. Plasma treatment with O ₂ ions in the ion energy range of 0 to 2000 eV results in an average thickness R of the reservoir 5 of approximately 15 nm, and the ions form channels or pores in the surface layer 6. To.

Similarly, before the step shown in FIG. 1 and after the plasma treatment, the reservoir 5 is _{filled with H 2} O as a first raw material. The reduced species of ions present during the plasma process, especially O ₂ , N ₂ , H ₂ , Ar, can also be located within the reservoir.

Therefore, the contact surfaces 3 and 4 still have a relatively wide gap, which is particularly occupied by the water present between the contact surfaces 3 and 4. Therefore, the existing bonding strength is relatively small, between about 100 mJ / cm ² and 300 mJ / cm ² , especially over 200 mJ / cm ² . In this regard, the prior plasma activation plays a decisive role because the hydrophilicity of the first contact surface 3 is increased by the plasma activation and the smoothing effect is obtained by the plasma activation.

The step, referred to as temporary joining, shown in FIG. 1 can preferably proceed at ambient temperature or up to 50 ° C. 2a and 2b show hydrophilic bonds, where Si—O—Si cross-linking occurs as a result of water desorption by the —OH termination surface. The steps of FIGS. 2a and 2b last for about 300 hours at room temperature. It lasts for about 60 hours at 50 ° C. The condition of FIG. 2b occurs at the indicated temperature without manufacturing the reservoir.

_{H 2} O molecules are formed between the contact surfaces 3 and 4, and as long as free space is still present, at least a portion _{of the H 2 O molecules is supplied to further fill the reservoir 5.} Other H ₂ O molecules are removed. In the step shown in FIG. 1, there are about 3 to 5 individual OH base _{layers or H 2} O layers, and from the step shown in FIG. 1 to the step shown in FIG. 2a, 1 to 3 layers of H ₂ O are present. The monolayer is removed or housed in the reservoir 5.

In the step shown in FIG. 2a, hydrogen cross-linking bonds are directly formed between the siloxane groups, resulting in higher bonding strength. Due to this bonding force, the contact surfaces 3 and 4 are attracted more strongly to each other, and the distance between the contact surfaces 3 and 4 is reduced. Therefore, there are only one or two individual OH base layers between the contact surfaces 3 and 4.

_{In the step shown in FIG. 2b, the separation of H 2} O molecules according to the reaction shown in the following chemical formula (2) forms a covalent bond in the form of a silanol group between the contact surfaces 3 and 4, thereby far. A strong bonding force is generated and less space is required, so that the distance between the contact surfaces 3 and 4 is further reduced, and finally the contact surfaces 3 and 4 shown in FIG. 3 are formed. Reach the minimum distance to touch each other.

Up to step 3, since the reservoir 5 is particularly formed, it is not necessary to raise the temperature excessively, but rather it is possible to proceed at room temperature. In this way, it is possible to proceed with the process steps shown in FIGS. 1 to 3 with particular care.

In the method step shown in FIG. 4, the temperature is preferably up to 500 ° C., more preferably up to 300 ° C., to form an irreversible or permanent bond between the first contact surface and the second contact surface. The temperature is preferably raised to a maximum of 200 ° C., most preferably a maximum of 100 ° C., and most preferably a temperature not exceeding room temperature. These temperatures are relatively low, unlike in the prior art, only when the reservoir 5 contains the first raw material for the reaction represented by the following chemical formula (3), shown in FIGS. 5 and 6. It is possible.

By a slight temperature rise of the above, H ₂ O molecules diffuse from the reservoir 5 to the reaction layer 7 as the first material. This diffusion can be done by direct contact between the surface layer 6 formed as the oxide layer and the growth layer, through the gaps 9 present between the oxide layers, or from the gaps 9. There, silicon dioxide, a chemical compound having a larger molar volume than pure silicon, is formed from the reaction layer 7 as the reaction product 10 of the above reaction. This silicon dioxide grows at the interface between the reaction layer 7 and the growth layer 8, and thus deforms the layer of the growth layer 8 formed as a natural oxide in the direction of the gap 9. Again, H ₂ O molecules from the reservoir are needed.

Since there are gaps in the nanometer range, the natural oxide layer 8 may swell, and as a result, the stress on the contact surfaces 3 and 4 can be reduced. In this way, the distance between the contact surfaces 3 and 4 is reduced, resulting in a further increase in the effective contact surface, and thus the bonding strength. The welded connection thus performed, unlike prior art products that are not partially welded, closes all holes and forms a welded connection over the entire wafer, thus essentially contributing to an increase in bonding force. The type of bond between two amorphous silicon oxide surfaces that are welded together is a mixed form of covalent and ionic bonds.

The above-mentioned reaction in the reaction layer 7 between the first raw material (H ₂ O) and the second raw material (Si) is performed as long as the average distance B between the first contact surface 3 and the reaction layer 7 is as large as possible. When smaller, it is done especially quickly or at the lowest possible temperature.

Therefore, the pretreatment of the first substrate 1 and the selection of the second substrate 2 composed of the reaction layer 7 of silicon and the thinnest possible natural oxide layer as the growth layer 8 are decisive factors. The thinnest possible natural oxide layer claimed in the present invention is provided for the following two reasons. Since the growth layer 8 is very thin, the reaction product 10 newly formed on the reaction layer 7 is directed toward the surface layer 6 formed as the oxide layer of the substrate 1 on which the growth layer 8 faces. It can swell mainly within the region of the nanogap 9. In addition, the shortest possible diffusion path is desirable in order to achieve the desired effect as quickly as possible and at the lowest possible temperature. Similarly, the first substrate 1 is composed of a silicon layer and an oxide layer formed as a surface layer 6 on the silicon layer, and a reservoir 5 is formed in the surface layer 6 at least partially or completely. To.

Therefore, the reservoir 5 claimed in the present invention is filled with at least the amount of the first raw material required to close the nanogap 9, and thus the growth layer 8 is packed in the growth layer 8 in the shortest possible time and / or as much as possible. It can be optimally grown to close the nanogap 9 at low temperatures.

Embodiments of the present invention will be described below.
-Aspect 1
A method of joining the first contact surface (3) of the first substrate (1) to the second contact surface (4) of the second substrate (2).
A step of forming a reservoir (5) in the surface layer (6) on the first contact surface (3),
A step of at least partially filling the storage portion (5) with the first raw material or the first raw material group.
A step of bringing the first contact surface (3) into contact with the second contact surface (4) in order to form a temporary joint connection.
A step of forming a permanent bond between the first contact surface (3) and the second contact surface (4), which is a reaction between the first raw material and the second substrate (2). A step of at least partially strengthening the permanent bond by reacting with a second raw material contained in the layer (7).
Especially in the above order, the method.
-Aspect 2
The method according to aspect 1, wherein the formation and / or reinforcement of the permanent bond is carried out by diffusing the first raw material into the reaction layer (7).
-Aspect 3
The formation of the permanent bond is carried out at a temperature between room temperature and 200 ° C., in particular up to 12 days, more preferably up to 1 day, even more preferably up to 1 hour, most preferably up to 15 minutes, said embodiment 1 or 2. The method described in.
-Aspect 4
Irreversible said junction is greater than 1.5 J / m ^2, greater in particular 2J / m ^2, preferably has a 2.5 J / m ² greater than the bonding strength, according to any of 3 from the embodiment 1 Method.
-Aspect 5
The reaction product (10) having a molar volume larger than the molar volume of the second raw material is formed in the reaction layer (7) during the reaction, according to any one of the above embodiments 1 to 4. Method.
-Aspect 6
The method according to any one of aspects 1 to 5, wherein the reservoir (5) is formed by plasma activation.
-Aspect 7
The method according to any one of aspects 1 to 6, wherein the formation of the reservoir (5) is performed using a particularly compressed tetraethoxysilane oxide layer as the surface layer (6).
-Aspect 8
The surface layer (6) is predominantly, in particular essentially completely, made of an amorphous material, particularly silicon dioxide produced by thermal oxidation, and the reaction layer (7) is an oxidizable material, particularly predominantly. The method according to any one of aspects 1 to 7, preferably comprising essentially entirely Si, Ge, InP, GaP, or GaN.
-Aspect 9
The method according to any one of aspects 1 to 8, wherein there is a growth layer (8) mainly of natural silicon dioxide between the second contact surface (4) and the reaction layer (7).
Aspect 10
9. The method of aspect 9, wherein the growth layer (8) has an average thickness A between 1 angstrom and 10 nm prior to forming a permanent bond.
Aspect 11
The method according to any one of aspects 1 to 10, wherein the reservoir is formed in vacuum.
Aspect 12
The storage section
The step of exposing the first contact surface (3) to an atmosphere particularly high in oxygen and / or water.
A step of exposing the first contact surface (3) to a fluid consisting _{particularly primarily, preferably almost completely, particularly deionized H 2} O and / or H ₂ O _2.
The first contact surface (3) is attached to at least one _{of N 2} gas, O ₂ gas, Ar gas, and a forming gas, particularly _{a forming gas consisting of 95% Ar and 5% H 2.} Steps where the ion energy is in the range of 0 to 2000 eV,
The method according to any one of embodiments 1 to 11, wherein the method is filled by one or more of the steps.
Aspect 13
The method according to any one of embodiments 1 to 12, wherein the reservoir (5) is formed with an average thickness (R) of between 0.1 nm and 25 nm, particularly between 0.1 nm and 20 nm.
Aspect 14
The average distance (B) between the reservoir (5) and the reaction layer (7) immediately before forming the permanent bond is preferably between 0.1 nm and 15 nm, particularly between 0.5 nm and 5 nm. The method according to any one of aspects 1 to 13, wherein is between 0.5 nm and 3 nm.
Aspect 15
The method according to any one of aspects 1 to 14, wherein the irreversible bond has a bonding strength of 2 times, preferably 4 times, more preferably 10 times, and most preferably 25 times the strength of the temporary bonding. ..

1 1st substrate 2 2nd substrate 3 1st contact surface 4 2nd contact surface 5 Reservoir 6 Surface layer 7 Reaction layer 8 Growth layer 9 Nano gap 10 Reaction product 11 1st profile 12 2nd Profile 13 Sum of curves A Average thickness B Average distance R Average thickness

Claims (14)

A method of joining the first contact surface of the first substrate to the second contact surface of the second substrate.
The first contact is made by hitting the first contact surface with at least one of N ₂ gas, O ₂ gas, Ar gas, and a forming gas consisting of 95% Ar and 5% H _2. The step of forming a reservoir in the surface layer on the surface,
A step of at least partially filling the reservoir with the first raw material or the first group of raw materials.
A step of bringing the first contact surface into contact with the second contact surface in order to form a temporary joint connection.
A step of forming a permanent bond between the first contact surface and the second contact surface, which is a second raw material contained in the reaction layer of the first raw material and the second substrate. And the step of at least partially strengthening the permanent bond by reacting with
Including, the storage part
A step of exposing the first contact surface to water or an atmosphere high in oxygen and water.
The step of applying said first contact surface, H ₂ O or H ₂ O ₂ or the fluid consisting both,
A step of applying the first contact surface to at least one of N ₂ gas, Ar gas, and a forming gas consisting of 95% Ar and 5% H _2.
A method of being filled by one or more steps of. The method of claim 1, wherein the formation and / or reinforcement of the permanent bond is performed by diffusing the first raw material into the reaction layer. The method of claim 1 or 2, wherein the formation of the permanent bond is carried out at a temperature between room temperature and 200 ° C. The method according to any one of claims 1 to 3, wherein the permanent bond has a ^{bond strength greater than 1.5 J / m 2.} The method according to any one of claims 1 to 4, wherein a reaction product having a molar volume larger than the molar volume of the second raw material is formed in the reaction layer during the reaction. The method according to any one of claims 1 to 5, wherein the reservoir is formed by plasma activation. The method according to any one of claims 1 to 6, wherein the formation of the reservoir is performed using the tetraethoxysilane oxide layer as the surface layer. The method according to any one of claims 1 to 7, wherein the surface layer is made of an amorphous material and the reaction layer is made of an oxidizable material. The method according to any one of claims 1 to 8, wherein there is a growth layer between the second contact surface and the reaction layer. 9. The method of claim 9, wherein the growth layer has an average thickness A between 1 angstrom and 10 nm prior to forming a permanent bond. The method according to any one of claims 1 to 10, wherein the reservoir is formed in a vacuum. The method according to any one of claims 1 to 11 , wherein the reservoir is formed with an average thickness (R) between 0.1 nm and 25 nm. The method according to any one of claims 1 to 12 , wherein the average distance (B) between the reservoir and the reaction layer immediately before forming the permanent bond is between 0.1 nm and 15 nm. .. The method according to any one of claims 1 to 13 , wherein the permanent bond has a bond strength twice that of the temporary bond.

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