JP2010095666A - Joining method and electronic device produced using the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joining method which can easily join together each item to be joined, using a low-temperature heat treatment without contaminating the items to be jointed and is highly suitable for a semiconductor process. <P>SOLUTION: Polysilazane is diluted with an organic solvent which is not compatible with water to lower viscosity (step S10), and the polysilazane dilution is coated on a joint surface of the item to be jointed using an appropriate technique (step S12). Preferably, the coating of the polysilazane dilution is carried out in vacuum. And then, the item to be joined is dried at a temperature which hardly causes silica inversion to remove the organic solvent only from the coated polysilazane dilution (step S14). The other item to be joined is laid on to the surface to sandwitch the polysilazane left on the joint surface of the item to be joined (step S16). The polysilazane is then heated at an atmosphere where water vapor or oxygen is present to bring about the silica inversion of the polysilazane, resulting in the joining of those items to be joined having SiO<SB>2</SB>as a joint layer (step S18). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a bonding method and an electronic apparatus (a semiconductor device, an electronic device, etc.) manufactured using the method.

Conventional inorganic bonding agents (inorganic adhesives) include those that have sodium silicate (water glass), potassium silicate, and ammonium phosphate added to fillers such as alumina and silica that do not have bonding strength to the skeleton. Classified as calcium (cement). As a joining technique by the water glass method, for example, there is a substrate joining method described in Patent Document 1 below, but water resistance is not sufficient. In addition, the sodium silicate contains a lot of sodium harmful to semiconductors, which adversely affects the operation of semiconductor transistors and the like. In addition, aluminum phosphate has a disadvantage that it absorbs external moist air to become a strong acid and corrodes surrounding metals. For these reasons, inorganic bonding agents are not used in the semiconductor field, and organic bonding agents and soft solder materials (commonly known as solder) have been used.
JP 2002-88318 A

The metal alcoside method is not classified as any of the above-described methods, and this is a technique in which a metal alcoside used for CVD or the like is put into a bonding surface and heated to deposit a metal oxide to be bonded. As a joining technique using such a metal alcoside, for example, there is a technique disclosed in Patent Document 2 below. However, this technique has a disadvantage that voids are generated in the bonding layer because a large amount of gas is generated and large volume shrinkage is accompanied.
JP 2002-137973 A

  In recent years, TEOS bonding is an application of the above-described metal alkoxide method. The metal alkoxide method is limited to a method of applying a liquid, but the TEOS bonding is limited to vapor phase growth. The TEOS method has a high weight reduction rate and a high volume reduction rate, and it is difficult to form a dense bonding surface. Therefore, a large load is applied during the bonding for densification. For this reason, there is an inconvenience that it is difficult to apply to an element having extremely high sensitivity to stress such as MEMS (micro electromechanical element).

By the way, as a bonding agent used in a semiconductor, only a constituent material of a semiconductor or a material used in a process of manufacturing a semiconductor is considered to be the most excellent material that does not cause contamination. Actually, in the semiconductor field, a resist material used in a semiconductor manufacturing process is used as an organic bonding agent. However, as can be seen from the background described above, the conditions that are compatible with semiconductor processes are (1) no contamination sources that adversely affect the operation of the semiconductor, (2) withstand the temperatures of oxidation and diffusion processes, (3) Dissimilar materials can be bonded with low stress, (4) Resistant to various chemicals, (5) Resistant to plasma, and (6) Covered with a step of about 0.1 μm. The most ideal bonding material that satisfies these conditions is silicon or silicon oxide. A technique using SiO ₂ as a bonding layer is, for example, hydrofluoric acid bonding disclosed in Patent Document 3 below.
JP 10-36145 A

The technique described in Patent Document 3 is a method of applying a buffered hydrofluoric acid aqueous solution before the SiO ₂ layer on the surface of a member to be bonded and the SiO ₂ layer on the surface of another member to be bonded are stacked and bonded together. It is. When a buffered hydrofluoric acid aqueous solution is applied, the hydrofluoric acid aqueous solution dissolves the extreme surface layer of SiO ₂ . In this state, when the members to be joined are bonded together and dried by heating, they do not remain as SiF ₄ but a lot of fluorine volatilizes and returns to SiO ₂ . Therefore, the resulting SiO ₂ in the surface layer of the surface layer of SiO ₂ layer and another member to be joined of the workpieces but nothing seems to be joined without inclusions.

The chemical reaction in the surface layer of such a member to be joined is represented by the following reaction formula. The mechanism of the bonding is to promote the dissolution reaction of the convex part due to the load (the part where the workpieces meet) and the flattening and the recombination part by promoting the precipitation reaction of the unloaded concave part. This is an increase in bonding strength by diffusion removal.

From the above-mentioned background, the most ideal bonding material can be said to be SiO ₂ , but at present, hydrofluoric acid bonding that makes it possible to do so is violated by hydrofluoric acid in the bonding process, because it uses strong corrosive hydrofluoric acid. There is a restriction that the material cannot be present. Therefore, a bonding agent using a material that can apply some liquid and paste the members to be joined, convert to silicon or silicon oxide by simple processing (hereinafter referred to as silica conversion), and exhibit a strong bonding force ( Or an adhesive) is convenient.

  By the way, as a substance having the property of converting to silica, there is polysilazane (official name: Perhydropolysilazane (PHPS)). Polysilazane has the property of being converted to silica by being oxidized with water vapor or oxygen, but it is a very high-viscosity liquid, so it is very difficult to apply it to the joint surface without dilution. Furthermore, it is a well-known fact that high-concentration polysilazane is converted into silicon oxide only by contact with water vapor or oxygen in the air, and once it is converted into high-purity silicon oxide, the bonding ability is lost. Therefore, if the members to be joined cannot be joined before the polysilazane is converted to silica, it cannot be used as a joining agent.

  The present invention pays attention to the above points, and the purpose of the present invention is to bond the objects to be bonded easily by low-temperature heat treatment without contaminating the objects to be bonded, and to have a good compatibility with the semiconductor process. Is to provide a method. Another object is to provide an electronic device (such as a semiconductor device or an electronic device) manufactured using the bonding method.

  In order to achieve the above-mentioned object, the bonding method of the present invention comprises a polysilazane diluted with an organic solvent that is not compatible with water so as to have a viscosity that can be applied to the bonding surface of the objects to be bonded. Applying, drying the object to be bonded at a temperature lower than the silica conversion temperature of polysilazane, removing only the organic solvent to leave polysilazane on the bonding surface, and bonding objects whose bonding surface is covered with polysilazane A step of stacking other objects to be bonded, a step of heating the pair of objects to be bonded in the step in the presence of water vapor or oxygen, and converting the polysilazane to silica to bond the pair of objects to be bonded. , Is included.

  One of the main forms is that the step of removing only the organic solvent is performed under vacuum, without heating or cooling, or at a temperature lower than the silica conversion temperature of polysilazane in an inert gas. It is performed by heating.

  In another embodiment, before the step of applying diluted polysilazane to the bonding surface, the bonding surface is planarized by silica impregnation using polysilazane. In another embodiment, the treatment for flattening the bonding surface by silica impregnation includes a step of applying polysilazane diluted with an organic solvent so as to have a viscosity applicable to the bonding surface, an inert gas, Heating the object to be bonded and removing the organic solvent, heating the object from which the organic solvent has been removed in the step in the presence of water vapor or oxygen, and converting the polysilazane covering the bonding surface to silica Including a step of performing.

  Yet another embodiment is characterized in that a process of forming a silicon hydroxide film on the bonding surface is performed before the step of applying diluted polysilazane to the bonding surface. Still another embodiment is characterized in that a load is applied to the stacked objects to be bonded in the step of bonding the pair of objects to be bonded. Yet another embodiment is characterized in that at least one of the objects to be joined is a semiconductor material or a semiconductor element.

  The electronic device according to the present invention includes a bonding portion bonded by any one of the methods described above. The above and other objects, features and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.

  In the present invention, polysilazane diluted with an organic solvent is applied to the bonding surface of the object to be bonded, and only the organic solvent is removed by drying the object to be bonded at a temperature at which the polysilazane is not converted to silica. Stack things up. And the to-be-joined objects were joined by heating the piled to-be-joined thing in presence of water vapor | steam or oxygen, and converting the said polysilazane into a silica. For this reason, it is possible to easily join the parts to be joined by low-temperature heat treatment without contaminating the parts to be joined, and to obtain an effect of showing good compatibility with semiconductor processes.

  Hereinafter, the best mode for carrying out the present invention will be described in detail based on examples.

  First, Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a flowchart showing basic steps of the joining method of the present invention, and FIG. 2 is a main cross-sectional view showing the basic steps. FIG. 3 is a flowchart showing a silica impregnation step (bonding surface flattening process) in Example 1, FIG. 4 is a flowchart showing a pre-joining step, and FIG. 5 is a flowchart showing the joining step. FIG. 6 is an explanatory diagram showing a polysilazane film forming step for a film-forming object having a hydroxyl group on the surface.

The present invention joins various objects to be joined using polysilazane and satisfies the conditions shown in the various semiconductor processes shown in the background art described above. Polysilazane (perhydropolysilazane) is an inorganic polymer composed of only silicon, nitrogen, and hydrogen and does not contain any organic components such as carbon, and has a molecular structure as shown in the following structural formula.

When the polysilazane encounters water or oxygen, it has an oxidation reaction at a low temperature and has the property of being converted to SiO ₂ while releasing ammonia gas and hydrogen into the reaction product. However, since polysilazane is a liquid with extremely high viscosity, it is extremely difficult to apply it to the bonding surface as it is. Furthermore, polysilazane of high concentration is converted into silicon oxide only by contact with water vapor or oxygen in the air. End up. If polysilazane diluted with an organic solvent (for example, xylene) is spin-coated and bonded and heat-treated, the bonding area is about 1/4 of the bonding surface. Moreover, since it has been found by analysis that the bonding strength is substantially proportional to the bonding area, the bonding strength is about ¼ that of the entire surface bonding. Therefore, in the present invention, in order to solve such a problem of reduction in the bonding area and to bond the bonding interface with an area of 100%, the fact that polysilazane is a high-viscosity liquid even in a solvent-free state is utilized. It was decided to create a tucked state.

  <Basic Step> ... With reference to FIGS. 1 and 2, the basic step of the bonding method of the present invention will be described. First, polysilazane is diluted with an organic solvent that is not compatible with water (for example, xylene or the like) to lower the viscosity (step S10 in FIG. 1). Dilution can also prevent polysilazane from being converted to silica. The dilution concentration varies depending on the method used in the coating step described later, but is, for example, about 10% in the case of spin coating and about 1% in the case of dip coating or dripping. Then, as shown in FIG. 2A, the polysilazane diluted solution 12 is applied to the bonding surface of the object to be bonded 10 by a method such as spin coating, dip coating, or dropping (step S12). Application of the polysilazane diluted solution 12 is, for example, (1) performed in a vacuum, (2) coated with the polysilazane diluted solution 12 at atmospheric pressure, and then evacuated to atmospheric pressure again in the uneven holes on the joint surface. (3) Apply the polysilazane diluent 12 at atmospheric pressure and dry it at atmospheric pressure (depending on the permeability of polysilazane). Appendices are most desirable.

Next, the object to be bonded 10 is dried at a temperature at which it is difficult to convert to silica, and only the organic solvent is removed from the applied polysilazane diluted solution 12 (step S14). As shown in FIG. Only the polysilazane 14 remains on the bonding surface of the bonded article 10. In this step of removing the organic solvent, if the polysilazane is converted to silica, the bonding strength is lost. Therefore, it is necessary to remove only the solvent without converting the silica. Specifically, it is performed by either heating without heating or removing the vacuum solvent in a cooled state, or heating at a temperature (about 80 to 120 ° C.) at which silica conversion is difficult in an inert gas. Thereafter, as shown in FIG. 2C, the other object to be bonded 16 is stacked (step S16), and the objects to be bonded 10 and 16 sandwich the polysilazane 14 from which the organic solvent has been removed. Then, when the polysilazane 14 is converted into silica by heating in an environment where water vapor or oxygen is present, the objects to be bonded 10 and 16 are bonded using the SiO ₂ as the bonding layer 18 as shown in FIG. Step S18).

また、前記ステップＳ１８において、酸素中でシリカ転化させた場合の反応は、下記反応式の通りとなり、アンモニアを生成する。

In this method, silica conversion proceeds with a small amount of gas in and out. At this time, it is suppressed by a small weight change and volume change. In addition, in the said step S18, reaction at the time of carrying out the silica conversion in water vapor | steam becomes as the following Reaction Formula, and produces | generates ammonia and hydrogen gas.

In Step S18, the reaction when silica is converted in oxygen is as shown in the following reaction formula, and ammonia is generated.

<Specific Example> Next, with reference to FIG. 3 to FIG. 6, a procedure for joining ferrite substrates by the joining method of Example 1 will be specifically shown.
(1) Silica impregnation step: In this embodiment, the process starts with the ferrite substrate flattening (bonding surface flattening) by the silica impregnation step shown in FIG. First, the ferrite substrate that is the object to be bonded is washed with an organic solvent such as alcohol or acetone (step S20), and the ferrite substrate is heat-treated with a cooling function that can be set to three types of atmospheres of vacuum, dry nitrogen, and water vapor. It puts into a furnace (step S22). Next, after the temperature of the heat treatment furnace is lowered to −10 ° C. (step S24), the heat treatment furnace is evacuated (step S26). In this state, for example, polysilazane diluted with an organic solvent such as xylene is dropped onto the surface of the ferrite substrate by an appropriate method such as spin coating, spray coating, dip coating, or the like (step S28).

  When it is confirmed that the surface of the ferrite substrate is covered with the dilute solution of polysilazane (step S30), dry nitrogen is introduced into the heat treatment furnace and set to atmospheric pressure (step S32). Then, the temperature is set to 80 ° C. with the heat treatment furnace filled with dry nitrogen to remove the solvent (step S34), and the temperature is set to 250 ° C. to 450 ° C. with the heat treatment furnace filled with dry nitrogen. And removed (step S36). If the heating is not performed in two steps as in steps S34 and S36 but is heated at a high temperature in the presence of a large amount of an organic solvent such as xylene, rapid boiling occurs and the flatness of the joint surface is impaired. In order to prevent this, in this embodiment, in a state where there is a large amount of the organic solvent, the organic solvent is gradually volatilized and removed at a low temperature (step S34), and the flatness of the bonding surface is ensured. After that, after a very small amount of organic solvent is contained, high temperature is used (step S36), and the organic solvent is removed with high accuracy. In addition, when drying is performed in the air instead of dry nitrogen, silica is converted from the surface of the polysilazane before the organic solvent is removed, and the organic solvent inside is confined. Therefore, in this embodiment, the organic solvent is confined. In order to prevent this, drying is performed in dry nitrogen.

  After removing the organic solvent in steps S34 and S36, water vapor is introduced into the heat treatment furnace (step S38), the temperature is set to 250 ° C. to 450 ° with the heat treatment furnace filled with water vapor, and polysilazane is converted into silica. It is converted (step S40), and finally cooled (removed) while removing the stress (step S42). The silica impregnation process in steps S20 to S42 as described above is a process performed when the joint surface (here, the surface of the ferrite substrate) has many pores, and the joint surface has few pores and sufficient flatness. If it is secured, it can be omitted.

  (2) Pre-bonding step: Next, polysilazane is applied by the pre-bonding step shown in FIG. 4 to the ferrite substrate that has been subjected to the flattening process of the bonding surface by the silica impregnation step. First, the ferrite substrate is washed with an organic solvent such as alcohol or acetone (step S50), and if necessary, a silicon hydroxide film is formed on the surface of the ferrite substrate (step S52). The silicon hydroxide film is not always necessary, but it is convenient to use the silicon hydroxide film when the bonding area is large and it takes time to diffuse moisture. For example, as shown in FIG. 6A, an organic solvent is used for a film-forming object 20 in which a hydroxyl group (= structured water) 22 exists on the surface and water molecules 24 are adsorbed on the hydroxyl group 22. Polysilazane 26 diluted with is dropped. At this time, when the silica 28 is formed by the silica conversion reaction shown in the reaction formula (Formula 3), a dehydration reaction from the structural water occurs as shown in FIG. 6B. A material in which an oxidation reaction due to water absorption strongly generates a strong adhesive force, and a strong adhesive force can be obtained as a film. Adhesive strength of adhesives that do not use many chemical bonds is mainly due to intermolecular attractive force and anchor effect. For the same reason, by introducing a hydroxyl group to the surface of the ferrite substrate in the step S52, it is possible to induce strong bondability by the strong polarity of the hydroxyl group, that is, the Coulomb force.

  Next, a heat treatment furnace with a cooling function capable of setting the ferrite substrate cleaned in step S50 or the ferrite substrate on which the silicon hydroxide film is formed in step S52 to three types of atmospheres of vacuum, dry nitrogen, and water vapor. (Step S54). Then, after the temperature of the heat treatment furnace is lowered to −10 ° C. (step S56), the heat treatment furnace is evacuated (step S58). Next, polysilazane diluted with an organic solvent such as xylene to lower the viscosity is dropped onto the surface of the ferrite substrate by an appropriate method such as spin coating, spray coating, dip coating (step S60). When it is confirmed that the surface of the ferrite substrate is covered with a dilute solution of polysilazane (step S62), dry nitrogen is introduced into the heat treatment furnace to atmospheric pressure (step S64), and then the heat treatment furnace is evacuated (step S62). S66). Then, the organic solvent is removed by setting the heat treatment furnace in a vacuum state and at room temperature (step S68).

  (3) Joining process: Next, the joining process shown in FIG. 5 will be described. First, the two ferrite substrates to be bonded together are fixed by a vacuum chuck in the atmosphere (step S70). Both of the two ferrite substrates to be bonded may be coated with polysilazane by the pre-joining step shown in FIG. 4 or may be coated with polysilazane only on the surface of one of the ferrite substrates. May be. Next, water vapor or moist air is introduced into the heat treatment furnace (step S72), and the two ferrite substrates to be bonded are stacked (step S74). Then, a load of about 0.01 MPa to 10 MPa is applied between the two ferrite substrates to be bonded together (step S76), and the temperature is heated to about 40 ° C. to 80 ° C. in a state where the heat treatment furnace is filled with water vapor to soften the polysilazane. The adhesion is increased (step S78). The load in step S76 is applied for correction when a gap is formed between the ferrite substrates, and may be omitted when the ferrite substrate is not distorted. Next, in a state where the inside of the heat treatment furnace is filled with water vapor, the temperature is heated to about 250 ° C. to 450 ° C., polysilazane is converted into silica, and the two ferrite substrates are joined (step S80). Finally, the bonded body is cooled (removed) while removing the stress (step S82).

Thus, according to the first embodiment, there are the following effects.
(1) A polysilazane diluted solution 12 diluted with an organic solvent is applied to the bonding surface of the object to be bonded 10, and only the organic solvent is removed by drying the object to be bonded 10 at a temperature at which the polysilazane is not converted to silica. Only on the surface of the article 10 to be joined. Then, the other objects to be bonded 16 were overlapped and heated in the presence of water vapor or oxygen, and the polysilazane 14 was converted to silica, whereby the objects to be bonded 10 and 16 were bonded. Therefore, the objects 10 and 16 can be easily bonded to each other by low-temperature heat treatment without contaminating the objects 10 and 16 to be bonded. Further, silica is not converted before bonding, and no void is formed between the objects to be bonded 10 and 16.
(2) Since the surface of the article to be joined is planarized by the silica impregnation step before the polysilazane is applied, the adhesion can be improved. In particular, when the surface of the object to be bonded is a mirror surface due to the planarization and the object to be bonded is not distorted, very high adhesion can be obtained. Further, even if the article to be joined is distorted, if it is a mirror surface, the distortion is improved by the load at the time of joining, so that sufficient adhesion can be obtained.
(3) Since a silicon hydroxide film is formed on the surface of the object to be bonded as required, strong bondability can be induced by the strong polarity of the hydroxyl group, that is, the Coulomb force.

<Application Examples> Next, application examples of the present invention will be described with reference to FIGS. First, the examples shown in FIGS. 7A-1 and 7A-2 are examples in which the present invention is applied to a small antenna. FIG. 7A-2 is an end view of FIG. 7A-1 cut along line # 7A- # 7A. In the antenna element 30 shown in FIGS. 7A-1 and 7A-2, a conductor pattern 34 of a minute loop antenna is formed by a conductor 38 embedded in a groove 36 formed in a ferrite substrate 32. In the conductor pattern 34, another ferrite substrate 40 is superposed on the loop-shaped portion excluding the power feeding portions 34A and 34B via the bonding layer 42. As shown in FIG. A gap is provided between the conductor pattern 34 and the ferrite substrate 40. The bonding layer 42 is SiO ₂ generated by the silica conversion of the bonding method shown in Example 1 described above, and the thickness thereof is, for example, about 0.1 μm. The conductor 38 is formed by applying and drying Ag paste or the like.

The examples shown in FIGS. 7B-1 and 7B-2 are examples in which the present invention is applied to a common mode choke coil. FIG. 7B-2 is an end view of FIG. 7B-1 cut along the line # 7B- # 7B. The common mode choke coil 50 shown in FIGS. 7B-1 and 7B-2 has a structure in which two conductor patterns 56 are formed in a ferrite substrate 54 provided on a substrate 52. . As shown in FIG. 7B-2, the conductor pattern 56 includes a conductor 60A embedded in the groove 58A of the ferrite substrate 54A and a conductor 60B embedded in the groove 58B of the ferrite substrate 54B. The ferrite substrates 54A and 54B are joined by the joining layer 62 so that the conductors 60A and 60B face each other. The bonding layer 62 is SiO ₂ produced by the silica conversion of polysilazane according to the bonding method shown in Example 1 described above, and the thickness thereof is, for example, about 0.1 μm.

  Since the antenna element 30 and the common mode choke coil 50 described above do not use semiconductors, they are irrelevant to semiconductor interaction. However, the joining technique using the polysilazane of the present invention is applied to such electronic devices. This is also effective. This is because the thickness of the bonding layers 42 and 62 can be controlled by controlling the viscosity in the solvent removal in the bonding method of the present invention, and can be made 0.1 μm or less. Both the antenna element 30 and the common common mode choke coil 50 are high frequency components, and both improve the function of the product by utilizing the high permeability of ferrite. Therefore, it is not preferable to insert a material having a relative dielectric constant larger than that of air or vacuum in a thick manner, which decreases the performance. However, by using the bonding method of the present invention, the thickness of the bonding layer is controlled to be thin. Can do.

The example shown in FIGS. 8 and 9 is an example in which the present invention is applied to a semiconductor device. First, the example shown in FIG. 8A is an example in which the bonding method using polysilazane of the present invention is used for bonding the bulk piezoelectric acceleration sensor 70 and the integrated circuit (LSI) 80. The integrated circuit 80, there is formed a MOS transistor 84 on the silicon substrate 82, a bottom surface of the acceleration sensor 70 and the passivation film 86 of the outermost layer is joined by bonding layer 72 made of SiO _2. The example shown in FIG. 8B is an example in which the crystal gyro element 90 and the ceramic for packaging 92 are joined by a joining layer 94 made of SiO ₂ . Further, the example shown in FIG. 8C is a stacked integrated circuit in which integrated circuits 102A, 102B, and 102C having a planar (two-dimensional) structure are three-dimensionally (three-dimensionally) integrated by a bonding layer 104 made of SiO _2. 100 is shown. The metal micro bumps 106 provided on the bonding layer 104 are connected to the embedded wiring 108. In the example shown in FIGS. 8A to 8C, the semiconductor can be easily joined without contaminating the semiconductor.

Next, an example shown in FIG. 9A is a conventional pressure sensor 110 in which a pedestal 114 in which a through hole 114A is formed and a silicon substrate 112 are joined by anodic oxidation. The pedestal 114 is made of alkali borosilicate glass. In the pressure sensor 110, Na and K, which are harmful to semiconductors, are important substances for bonding, and cannot be bonded without an alkali metal. On the other hand, the pressure sensor 120 shown in FIG. 9B joins a pedestal 124 having a through-hole 124A and a silicon substrate 122 with a polysilazane 126. The pedestal 124 is made of, for example, borosilicate glass or SiO _2. It consists of For this reason, there is no alkali metal, and the polysilazane 126 is converted into pure SiO ₂ after bonding, so that the bonding stress due to the difference in thermal expansion coefficient is small and strong bonding is possible, and fusion with the semiconductor is possible.

In addition, this invention is not limited to the Example mentioned above, A various change can be added in the range which does not deviate from the summary of this invention. For example, the following are also included.
(1) The shapes and dimensions shown in the above embodiments are examples, and may be appropriately changed as necessary.
(2) The solvents and objects to be joined shown in the above-described embodiments are also examples, and may be appropriately changed so as to achieve the same effect.
(3) The silica impregnation step and the silicon hydroxide film formation shown in the above embodiments are examples, and the steps may be introduced as necessary.
(4) The application examples shown in FIGS. 7 to 9 are also examples, and the present invention can be applied not only to semiconductors but also to various known electronic devices in general including joints between objects to be joined.

  According to the present invention, polysilazane diluted with an organic solvent is applied to the bonding surface of the object to be bonded, and only the organic solvent is removed by drying the object to be bonded at a temperature at which the polysilazane is not converted to silica. Stack the objects to be joined. And since it superposed | heated in presence of water vapor | steam or oxygen and the polysilazane was silica-converted, it can apply when joining a to-be-joined part thing. In particular, it is suitable for bonding in the semiconductor field because it can be easily bonded by low-temperature heat treatment without contaminating the objects to be bonded, and exhibits good compatibility with semiconductor processes.

It is a flowchart which shows the basic process of the joining method of this invention. It is principal sectional drawing which shows the basic process of the joining method of this invention. It is a flowchart which shows the silica impregnation process (joining surface planarization process) in Example 1 of this invention. It is a flowchart which shows the process before joining in the said Example 1. FIG. It is a flowchart which shows the joining process in the said Example 1. FIG. It is explanatory drawing which shows the film-forming process of the polysilazane with respect to the to-be-film-formed object which has a hydroxyl group on the surface. It is a figure which shows the example of application of this invention. It is a figure which shows the other application example of this invention. It is a figure which shows the other application example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,16: To-be-joined object 12: Polysilazane dilution liquid 14: Polysilazane 18: Joining layer 20: To-be-film-formed object 22: Hydroxyl group (structural water)
24: Water molecule 26: Polysilazane 28: Silica 30: Antenna element 32, 40: Ferrite substrate 34: Conductor pattern 34A, 34B: Power feeding portion 36: Groove portion 38: Conductor 42: Bonding layer 50: Common mode choke coil 52: Substrate 54 , 54A, 54B: Ferrite substrate 56: Conductor pattern 58A, 58B: Groove 60A, 60B: Conductor 62: Bonding layer 70: Acceleration sensor 72: Bonding layer 80: Integrated circuit (LSI)
82: Silicon substrate 84: MOS transistor 86: Passivation film 90: Quartz gyro element 92: Ceramics for packaging 94: Bonding layer 100: Stacked integrated circuits 102A, 102B, 102C: Integrated circuit 104: Bonding layer 106: Metal micro bump 108 : Embedded wiring 110, 120: Pressure sensor 112, 122: Silicon substrate 114, 124: Base 114A, 124A: Through hole 126: Polysilazane

Claims (9)

A step of applying polysilazane diluted with an organic solvent that is not compatible with water so as to have a viscosity that can be applied to the bonding surface of an object to be bonded to the bonding surface;
Drying the object to be bonded at a temperature lower than the silica conversion temperature of polysilazane, removing only the organic solvent and leaving polysilazane on the bonding surface;
A process of superimposing another object to be bonded on the object whose bonding surface is covered with polysilazane,
Heating the pair of objects to be joined in the step in the presence of water vapor or oxygen, converting the polysilazane to silica, and joining the pair of objects to be joined;
A bonding method comprising:   The bonding method according to claim 1, wherein the step of removing only the organic solvent is performed under vacuum in an unheated or cooled state.   The bonding method according to claim 1, wherein the step of removing only the organic solvent is performed by heating at a temperature lower than the silica conversion temperature of polysilazane in an inert gas.   The joining method according to any one of claims 1 to 3, wherein a treatment for flattening the joining surface by silica impregnation using polysilazane is performed before the step of applying diluted polysilazane to the joining surface. . The process of flattening the joint surface by the silica impregnation,
Applying polysilazane diluted with an organic solvent so as to have a viscosity that can be applied to the bonding surface, to the bonding surface;
Heating the object to be bonded in an inert gas to remove the organic solvent;
Heating the bonded product from which the organic solvent has been removed in the step in the presence of water vapor or oxygen to convert polysilazane covering the bonding surface into silica;
The bonding method according to claim 4, further comprising:   The bonding method according to claim 1, wherein a process of forming a silicon hydroxide film on the bonding surface is performed before the step of applying diluted polysilazane to the bonding surface.   The joining method according to claim 1, wherein in the step of joining the pair of objects to be joined, a load is applied to the stacked objects to be joined.   The bonding method according to claim 1, wherein at least one of the objects to be bonded is a semiconductor material or a semiconductor element.   An electronic device comprising a bonding portion bonded by the method according to claim 1.

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