JP3017372B2 - Compound for ceramic joining - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention relates to a wide range of ceramics such as non-oxide ceramics such as silicon, silicon carbide, silicon nitride, aluminum nitride and composites thereof, and oxide ceramics such as alumina, zirconia and mullite. The present invention relates to a compound suitable for joining and filling the voids.

[0002]

2. Description of the Related Art Ceramics are advantageous in that they have high heat resistance, are solid, are chemically inert and can be prepared with extremely high purity, and are widely used as advanced materials. . Processing of these ceramics is generally performed at the stage of forming the material before firing. But,
Since a large volume change occurs before and after firing of the ceramic molded body, it is difficult to increase the dimensional accuracy only by processing before firing. Therefore, it can be re-processed after firing so as to obtain the desired shape and accuracy. However, since the ceramics are hard and brittle as described above and have poor workability, their shapes and sizes are limited.

[0003] Also, it has been conventionally performed to form a complex shape or a large-sized product by assembling and joining respective components which are divided so as to constitute a target ceramic shape. In this case, if the ceramic fired parts cannot be joined into a predetermined shape or the like while maintaining the advantages of ceramics having excellent heat resistance, chemical durability, and the like, the utility value of the original ceramics is lost. Therefore, various methods having heat resistance have been implemented as ceramic joining methods. For example, there are a joining method using solder glass and a metal joining method using metallizing. Some cement-based inorganic materials such as alumina cement are also used as high heat-resistant bonding materials.

[0004]

However, the materials to which both the above solder glass bonding and metal bonding methods can be applied are limited, and the heat resistance and corrosion resistance are not sufficient. In addition, high technology is required at the time of joining,
The shape of the joint is also limited to a simple one. In addition, the inorganic material-based bonding material has an advantage that it can be fixed at room temperature. However, in order to make it fire-resistant, it is usually necessary to fire at a high temperature of 1000 ° C. or more. In many cases, the material is broken due to the occurrence of phenomena, and it can be used only for extremely limited materials and applications.
In addition, the inorganic material-based bonding material often contains various elemental components as components and impurities, and a predetermined high purity may not be achieved in some cases.

[0005] In view of the current state of the above-mentioned conventional ceramic bonding method, the present invention can firmly bond various ceramics by simple steps, has sufficient bonding strength before and during firing, and The purpose of the present invention is to provide a ceramic bonding material capable of forming a bonding layer and a bonded body excellent in high purity, high heat resistance, high chemical resistance, and the like, that is, a compound for ceramic bonding. An object of the present invention is to easily form a large-sized product or a complex-shaped body of ceramics that are joined and integrated.

[0006] The inventor has studied various requirements as a joining material for achieving the above object, and as a result of intensive studies particularly satisfying the following two points, completed the present invention. That is, (1) the bonding material is capable of exhibiting a sufficient bonding force at room temperature at the time of bonding, and the bonding material is maintained in the firing process. That is, there is no possibility that the joining portion is detached during the firing process, and no special firing jig is required. Also, there is no restriction on the shape and size of the joined body. Further, in some cases, the firing temperature after the bonding can be omitted by setting the use temperature of the ceramic bonded body to the firing temperature range. (2) As a ceramic bonding material requiring high purity, for example, a contaminant such as a transition metal or an alkali metal ion should not be contained as a component or an impurity.
Ceramics are used in many applications requiring high purity, such as electronic components and members for manufacturing semiconductor devices. In these uses, the above contaminants are not mixed in the raw materials as well as in the ceramic manufacturing process and processing stage. You need to do that. Therefore, when the joined ceramic joined body is used particularly for processing a semiconductor device, Si, O, N, C, H
All other elements are contaminants and should be reduced as much as possible.

[0007]

According to the present invention, in a ceramic bonding compound comprising a polysilazane compound, a polycarbosilane compound, a ceramic powder and a solvent, the weight ratio of the polysilazane compound to the polycarbosilane compound is determined. Is 1: 0.05 to 40, and a compound for ceramic bonding is provided.
Further, according to the present invention, in a ceramic bonding compound comprising a polysilazane compound, a polycarbosilane compound, a ceramic powder and a solvent, the weight ratio of the total amount of the polysilazane compound and the polycarbosilane compound to the ceramic powder Is 1: 2 to 40, and a compound for ceramic bonding is provided. Further, according to the present invention, as a preferred embodiment of the ceramic bonding compound, there is provided a ceramic bonding compound, wherein the ceramic powder has the same type or a similar thermal expansion coefficient as the ceramic to be bonded.

[0008]

The present invention is constructed as described above, and the polysilazane or polycarbosilane compound compounded in the above specific ratio is dissolved in a predetermined solvent to form an adhesive solution, and the solution is bonded. The ceramics can be easily fixedly bonded by applying the coating to the bonding portion of the ceramics and drying, and the bonding force is maintained during the subsequent firing. When polysilazane or polycarbosilane compounds are heated in an atmosphere of an inert gas or an oxygen-containing gas, heat-resistant and chemically stable compounds such as SiN, SiC, SiON, Si, and SiO ₂ due to the atmosphere. Generate Then, a firm bonding layer is formed together with the ceramic powder mixed in a specific ratio with respect to the total amount of the polysilazane and the polycarbosilane, so that a strong bonded body between the ceramics can be obtained. In addition, polysilazanes and polycarbosilane compounds can be chemically synthesized, are easily purified, do not contain polluting elements harmful to semiconductors and the like, and are used as bonding materials for various ceramics such as semiconductor members. No source of pollution.

Hereinafter, the present invention will be described in detail. The polysilazane and polycarbosilane compounds used in the present invention are well known as precursors of silicon carbide (SiC) and silicon nitride (SiN). As the polysilazane, compounds generally used as a precursor of SiN or SiC, such as polymers of various molecular weights of perhydropolysilazane and various polymers of methyl polysilazane, can be used.
In addition, polycarbosilanes are [RR'SiCH ₂ ] _n
(Where R and R ′ are R ≠ R ′ and H, CH ₃ , C ₆
It is either H _5. n = 5 to 5000 or more), and a compound conventionally used as a precursor of SiC can be used.

According to the knowledge of the inventor, the above-mentioned polysilazanes and polycarbosilanes both have a certain fixing force at ordinary temperature when dissolved in an organic solvent such as xylene and then the solvent is removed. The fixing force changes due to the temperature rise. That is, for each of the polysilazane compound, the polycarbosilane compound, and the mixture having a ratio of about 1: 1, the relationship between the temperature and the fixing strength was experimentally examined. FIG. 1 schematically shows the results. According to FIG. 1, the fixing strength of the polysilazane compound, that is, the adhesive strength is about 100 to 200.
It almost disappears at ℃, but increases rapidly from around 200 ℃,
From around 500 ° C., the rate of increase decreases,
At 00 ° C., the temperature again tends to increase. A polysilazane compound is a solid to a viscous liquid at room temperature, depending on its type and degree of polymerization. When the temperature rises, a low-viscosity liquid is generated and a decomposition reaction occurs to generate an extremely brittle gel, so that the adhesive strength decreases. . At 200 ° C. or higher, the polymerization proceeds and the gel solidifies, thereby increasing the adhesive strength. However, from around 500 ° C., the thermal decomposition is severe, a large amount of organic substances are released, and the residue becomes porous, so that the increase in the adhesive strength is slow. . Also,
At about 900 to 1000 ° C., it is estimated that the thermal decomposition reaction is completed, the sintering and crystallization of the generated inorganic compound proceeds, and the bonding strength further increases sharply.

On the other hand, the polycarbosilane compound loses its adhesion at about 200 to 400 ° C. as shown in FIG. 1, but at about 400 ° C. or more, its adhesion increases with temperature.
When the temperature exceeds 00 ° C., the rate of increase in strength decreases, and the temperature tends to increase again at 900 to 1000 ° C. like the polysilazane compound. Most of the polycarbosilane compounds are solid at around room temperature, and are usually stable up to around 200 ° C., and the fixing power is maintained. However, when the temperature is raised to 200 ° C. or higher, the liquid becomes a low-viscosity liquid and the polymerization reaction starts to occur, and the adhesive strength is lost. Further, since no gelling reaction usually occurs, the strength becomes higher than that of polysilazane. If the temperature exceeds 600 ° C., as in the case of polysilazane, the thermal decomposition reaction of the solidified product proceeds and becomes porous, so that the strength increase rate decreases. It rises sharply with it.

On the other hand, as is apparent from FIG. 1, when the polysilazane compound and the polycarbosilane compound are used alone, a temperature range in which the sticking force hardly disappears in the middle of each temperature rise appears. As described above, when both are mixed and used, it can be seen that an adhesive strength exceeding the average value of both is obtained in almost the entire temperature range. Although the reason is not clear, the adhesion of polysilazane is lost to 100 to 20.
At around 0 ° C., polycarbosilane is solidified or a highly viscous liquid, which prevents the gelation of polysilazane,
In addition, since the polymerization reaction proceeds in a direction of increasing the viscosity of the polymer to increase, the fixing force does not decrease. On the other hand, at around 200 to 400 [deg.] C. where the bonding strength of polycarbosilane is lost, the polycarbosilane melted into the polymerized and solidified polysilazane acts as a plasticizer to supplement brittleness and increase strength. At a high temperature of 600 ° C. or higher, rapid decomposition of the gas does not occur as a whole due to the different decomposition temperatures, and the solidification is completed without destroying the structure. In addition, since the properties of the reaction products are different between the two, it is considered that the interaction due to the complexation contributes to the increase in the fixing force.

As described above, in the present invention, the polysilazane compound and the polycarbosilane compound are used together at a specific quantitative ratio, so that the interaction can maintain a predetermined high adhesive strength over the entire application temperature range. In the present invention, the polysilazane compound and the polycarbosilane compound are in a weight ratio of 1: 1, based on the polysilazane compound.
It is used by mixing at 0.05 to 40, more preferably at 1: 0.1 to 20.

In the ceramic bonding compound of the present invention, a ceramic powder is further added to and mixed with the above mixture of the polysilazane compound and the polycarbosilane compound. As the ceramic powder to be added, it is preferable to use a ceramic powder of the same type as the ceramic to be joined or a different type of ceramic powder whose thermal expansion coefficient matches that of the ceramic to be joined within a predetermined range. When the ceramic bonding compound is composed only of a mixture of a polysilazane compound and a polycarbosilane compound, a good bonded body can be obtained when the bonding surface of the ceramics is extremely small, but peeling occurs when the area is large, resulting in good peeling. It was difficult to obtain a conjugate. Inventors, the main cause is, during ceramic firing after bonding, these compounds varies SiN, SiC, and SiO ₂ or the like compounds, where organic material withdrawal or combustion such as hydrogen or hydrocarbon, volatilized It has been found that volume shrinkage occurs and gaps and cracks occur in the joint. In the present invention, by adding ceramic powder to a mixture of a polysilazane compound and a polycarbosilane compound, it is possible to reduce the above-mentioned volume shrinkage at the time of firing and to improve the bonding strength. .

In the present invention, when a ceramic powder of the same type as the ceramic to be bonded is used, a particularly good bonding state can be obtained. It is presumed that the difference in thermal expansion between the joining layer and the ceramic to be joined disappears, thereby reducing the thermal distortion of the ceramic joined body. Even if the ceramics to be joined are not of the same kind as the ceramics to be joined, even if they are of a different kind, a joined body having a high joining strength can be obtained even with a ceramic powder having a thermal expansion coefficient substantially the same or a difference of 1 × 10 ⁻⁶ or less. The ceramic powder of the same type as the ceramic to be joined added to the mixture of the polysilazane compound and the polycarbosilane compound refers to a ceramic powder of the same type as the ceramic to be joined. For example, for bonding silicon, silicon powder, S
SiC powder for iC, SiN powder for SiN, alumina powder for alumina, zirconia powder for zirconia, and the like. On the other hand, different ceramic powders having matching thermal expansion coefficients are ceramic powders having a difference in average thermal expansion coefficient of 1 × 10 ⁻⁶ or less unlike ceramics to be joined, such as silicon, SiC, SiN, and the like. It can be appropriately selected from various ceramic materials such as aluminum nitride. For example, powder of SiN or silicon can be selected for aluminum nitride of the ceramics to be joined. If the difference between the average thermal expansion coefficients of the ceramics to be joined and the different ceramics powder exceeds 1 × 10 ⁻⁶ , thermal distortion in the resulting ceramic joined body becomes large, and disadvantages such as peeling occur.

The amount of the ceramic powder to be added is 1: 2 to 40, preferably 1: 4, by weight relative to the above compound mixture.
Add at ~ 20. If the weight ratio of the ceramic powder to the total amount of the compound mixture is 2 or less, the effect of preventing cracking at the time of firing is not sufficient, and if it exceeds 40, the bonding strength is reduced and it is not practical. The particle size of the ceramic powder to be added can be appropriately selected depending on the application means to be applied, the shape of the joint, and the like. Further, by using a ceramic powder having a large particle size for filling a large gap or the like, good results can be obtained with little shrinkage after drying. In this case, there may be a problem that the ceramic powder is liable to settle and separate during storage of the kneaded and formed bonding compound. Usually, it is preferable to use a ceramic powder having an average particle diameter of 100 μm or less.

The compound of the present invention comprises a powder mixture obtained by adding the above-mentioned ceramic powder to the above-mentioned polysilazane and polycarbosilane compound mixture, and an organic solvent such as xylene, which is sufficiently kneaded to form a slurry. I do.
The type of the solvent and the mixing ratio between the solid content and the solvent can be appropriately selected according to each condition at the time of joining. These are related to the workability of coating and the like, and in general, the smaller the amount of the solvent, the easier the drying, the less the volume decreases after drying, and a good result can be obtained. However, if the amount of the solvent is too small, the fluidity decreases, and the coating operation becomes difficult. Therefore,
The above-mentioned powder mixture of the polysilazane and polycarbosilane compound mixture and the ceramic powder and the solvent were mixed in a ratio of 1:
It is preferable to mix at a weight ratio of 0.05 to 40. In order to impart high fluidity, it is preferable to add the solvent so that the liquid component of the solvent is 20% by weight or more. In the present invention, an appropriate amount of a surfactant or a thickener may be added in addition to the above-mentioned powder mixture and solvent for the purpose of improving workability.

The ceramic bonding compound of the present invention obtained as described above forms a bonding portion by applying or injecting a predetermined amount to the bonding surface of each bonded ceramic mix using a brush or a dispenser. can do.
After application or the like, before the solvent evaporates and solidifies, the joints of the respective ceramics to be joined are butted and heated and dried if necessary. Further, thereafter, by heating and firing at a predetermined temperature in an atmosphere of an inert gas such as nitrogen or argon, or in an atmosphere of an oxygen-containing gas such as air, the target ceramic joined body having high heat resistance and high strength is obtained. Obtainable.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments. However, the present invention is not limited by the following examples. Examples 1 to 9 and Comparative Example 1 Polycarbosilane obtained by heating polysilane in an autoclave was mixed with perhydropolysilazane having a molecular weight of 1700 to 2100 at each weight ratio shown in Table 1 to obtain a compound mixture. Obtained. An average particle size of 20 was added to the obtained mixture.
μm silicon powder was added at a weight ratio of 1: 5 with the mixture to obtain a mixed powder composed of polysilazane, polycarbosilane and silicon. Further, xylene was added at a weight ratio of 1: 0.5 with respect to the solid content of the obtained mixed powder, and kneaded with a ball mill for 4 hours to prepare a bonding compound. Each of the prepared bonding compounds weighed about 30 g.

The end face is flattened and has a diameter of 10 mm.
A silicon rod having a φ of 30 mm in length was prepared. Next, each of the bonding compounds obtained above was applied to the end face of one silicon rod with a quartz glass rod to form a bonded portion, and then pressed together with the end face of another silicon rod to be bonded. The bonded silicon bonded body was dried at 70 ° C. for 3 hours to fix the bonded portion. Thereafter, the fixed silicon bonded body was fired at each temperature shown in Table 1 in a nitrogen gas atmosphere. Each tensile strength of the fired and formed silicon joined body was measured. The results are shown in Table 1.

[0021]

[Table 1]

As is clear from the above Examples and Comparative Examples, when a bonding compound was prepared from a compound of polysilazane alone without adding polycarbosilane, the tensile strength was low at any of the firing temperatures, and in particular, 120%.
It can be seen that the tensile strength after firing at 1300C and 1350C is extremely low. On the other hand, after the bonding compound mixed at a polycarbosilane / polysilazane weight ratio of 0.05 to 40, particularly 0.1 to 20, is treated at a sintering temperature of 120 to 1350 ° C. as compared with a polysilazane alone. It can be seen that the tensile strength of each of them was improved.

Example 10 A bonding compound was prepared in the same manner as in Example 1 except that the weight ratio of polycarbosilane / polysilazane was changed to 0.3. The obtained bonding compound was applied to the end face of one silicon nitride rod having a diameter of 10 mmφ, and was butt-bonded to the end face of another silicon nitride rod. Thereafter, it was dried at room temperature and further heat-treated at 250 ° C. in air. The bonded silicon nitride rod after the heat treatment had a tensile strength of 0.5 MPa as measured in the same manner as in Example 1. Next, the bonded silicon nitride rod obtained above was baked at 1000 ° C. in a nitrogen gas atmosphere, and as a result, it had a bonding strength of 10 MPa. At a firing temperature of 1350 ° C., a bonding strength of 100 MPa was obtained.

Examples 11 to 17 and Comparative Examples 2 to 3 The polycarbosilane used in Example 1 was added to a hexamethylcyclotrisilazane polymer having an average molecular weight of about 1300 at a weight ratio of 1: 0.2. Weighed and added to give a mixture of compounds. Silicon carbide powder having an average particle size of 2 μm was added to the obtained mixture at a weight ratio shown in Table 2 to obtain a mixed powder. Further, the mixed powder having the same weight as the mixed solvent was added to a mixed solvent having a toluene / hexane ratio of 5/1, and the mixture was kneaded well with a ball mill to prepare a bonding compound. On the other hand, a 5 × 5 × 25 (mm) silicon carbide ceramic square bar was prepared, and the 5 × 5 × 25 × 25 (mm) square bar was prepared in the same manner as in Example 1 using the bonding compound prepared as described above.
(Mm), and the two end faces of two silicon carbide ceramic square bars were adhered. Next, after drying at room temperature, it was fired at each temperature shown in Table 2 in an argon gas atmosphere, and the bending strength was measured using a four-point bending load method. Table 2 shows the results.
It was shown to.

[0025]

[Table 2]

As is clear from the above Examples and Comparative Examples, the bonding compound of Comparative Example 2 in which the ceramic powder SiC was not added to the compound mixture of polysilazane and polycarbosilane was obtained by firing the bonding compound of the present invention. While the bending strength increases as the temperature increases, the bending strength after firing is low and does not change regardless of the firing temperature. In addition, SiC is used for the compound mixture.
It can be seen that the bonding compound of Comparative Example 3 in which was added more than 40 times and 50 times was not exhibited the adhesive ability itself.

Example 18 5 g of perhydropolysilazane used in Example 1, 5 g of polysilastyrene having an average molecular weight of about 40,000, and an average particle size of 2
80 g of 0 μm alumina powder, 45 g of alumina powder having an average particle diameter of 1 μm, and 30 g of xylene were mixed and kneaded with a ball mill to obtain a bonding compound. On the other hand, 5x
A 5 × 25 (mm) alumina ceramic square bar was prepared and applied to the 5 × 5 (mm) end face in the same manner as in Example 1 using the bonding compound prepared as described above. The end face of the alumina ceramic square bar was bonded.
Then, it was dried and fixed at room temperature. Each alumina ceramic fixing rod was fired in air at 500 ° C. and 1200 ° C., respectively, and the bending strength was measured in the same manner as in Example 11.
As a result, they had bending strengths of 3 MPa and 60 MPa, respectively.

Example 19 50 g of trimethylhydropolysilazane having an average molecular weight of about 2,000, 5 g of polycarbosilane, 200 g of silicon powder having an average particle size of 5 μm, 60 g of diethylene glycol butoxyacetate and 30 g of xylene were mixed well and kneaded well with a ball mill to form a bonding compound. Got pounds. Using the obtained bonding compound, a 30 × 30 (mm) square,
Screen printing was performed on a 0.8 mm-thick aluminum nitride ceramic plate, and a silicon ceramic plate of the same size was placed thereon and pressed, dried and fixed. As a result of heating and firing the obtained ceramic fixing plate at 1200 ° C. in a nitrogen gas atmosphere, a strong bonded body of aluminum nitride and silicon was obtained.

[0029]

The ceramic bonding compound of the present invention has sufficient bonding strength at room temperature drying, and maintains the bonding strength even during high-temperature heat treatment such as firing, and increases bonding strength. Various ceramics can be obtained as a strong ceramic bonded body with a large size and a complicated shape by a simple process without causing a defect or peeling of a bonded portion. Furthermore, the compound for ceramic joining of the present invention,
In addition to ceramic powder, compounds mainly composed of elements of Si, O, N, C and H can be used as constituent components, and contamination of semiconductor contaminants can be suppressed as much as possible. It is also useful as a bonding material or filler for ceramic members. Further, the formed bonding layer is excellent in high purity, high heat resistance, high chemical resistance and the like.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the sintering temperature and the adhesive strength in a polysilazane compound, a polycarbosilane compound, or an equivalent mixture of a polysilazane compound and a polycarbosilane compound.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C04B 37/00

Claims (4)

(57) [Claims] 1. A ceramic bonding compound comprising a polysilazane compound, a polycarbosilane compound, a ceramic powder and a solvent, wherein the weight ratio of the polysilazane compound to the polycarbosilane compound is 1: 0.05 to 40. The compound for ceramic joining characterized by the above-mentioned. 2. The ceramic bonding compound according to claim 1, wherein the ceramic powder is of the same type or has a similar thermal expansion coefficient to the ceramic to be bonded. 3. A ceramic bonding compound comprising a polysilazane compound, a polycarbosilane compound, a ceramic powder and a solvent, wherein the weight ratio of the total amount of the polysilazane compound and the polycarbosilane compound to the ceramic powder is 1: Two
40. A compound for ceramic joining, which is 40. 4. The ceramic bonding compound according to claim 3, wherein the ceramic powder is of the same type as the ceramic to be bonded or has a similar thermal expansion coefficient.