JP2011190163A - Method for producing aluminum nitride sintered compact workpiece - Google Patents

Abstract

When an aluminum nitride sintered body is processed at a high temperature of 1600 to 1750 ° C., the aluminum nitride sintered body is suppressed to a very small thermal deformation, and the appearance and dimensional accuracy are both good. A method of manufacturing a workpiece is provided.
A process of treating an aluminum nitride sintered body obtained by firing aluminum nitride powder using yttrium oxide as a sintering aid at a temperature of 1600 to 1750 ° C., for example, a metallization process. In the production of a processed aluminum nitride sintered body containing, as the aluminum nitride sintered body, the amount of YAG (3Y ₂ O ₃ .5Al ₂ O ₃ ) crystal phase in the grain boundary phase is aluminum nitride (100) plane. An aluminum nitride sintered body having an intensity ratio of the X-ray diffraction pattern of the YAG (211) plane to 0.001 or less is used.
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Description

  The present invention relates to a novel production method for producing a workpiece by treating an aluminum nitride sintered body obtained using yttrium oxide as a sintering aid at a high temperature. Specifically, when the aluminum nitride sintered body is processed at a high temperature of 1600 to 1750 ° C., the aluminum nitride sintered body is suppressed to a very small thermal deformation, and both the appearance and dimensional accuracy are good. A method for producing a body workpiece is provided.

  Aluminum nitride sintered bodies are used as circuit boards for semiconductors, LEDs, etc. by utilizing their excellent properties such as high thermal conductivity, insulation, halogen plasma resistance, and thermal expansion coefficient close to that of Si. Alternatively, it is used as a structure used for a film forming apparatus or an etching apparatus in a semiconductor manufacturing process.

  In the method for producing an aluminum nitride sintered body, as a technique for obtaining an aluminum nitride sintered body having high thermal conductivity, a method of firing using yttrium oxide as a sintering aid is becoming mainstream.

  On the other hand, in the use of the aluminum nitride sintered body, the aluminum nitride sintered body obtained by firing may be processed at a high temperature to produce a workpiece. For example, a base made of a sintered aluminum nitride sintered body is prepared, and a paste containing an aluminum nitride powder is applied to the bonding surface of the base, and then a separately prepared base made of an aluminum nitride sintered body is adhered. Patent Document 1 discloses a method of firing and joining at a temperature of 1700 ° C. or higher with pressure applied.

  A method of forming a conductive paste layer made of a refractory metal on an aluminum nitride sintered substrate and firing it at a temperature of 1600 ° C. or higher is called a post-fire method and is disclosed in Patent Document 2. . Since the post-fire method does not cause non-uniform shrinkage of the aluminum nitride green sheet compared to a method called cofire method in which an unfired aluminum nitride green sheet and a conductive paste layer are fired simultaneously, the planar direction of the conductive paste layer This has the advantage that the pattern dimensions are not likely to be non-uniform.

  However, heat treatment such as baking a conductive paste layer made of a refractory metal by the post-fire method causes deformation such as warping in the aluminum nitride sintered body obtained by firing using yttrium oxide as a sintering aid. Have the problem. Such deformation often becomes a problem when applied to a recent electronic component mounting board that requires high flatness. Therefore, in the processed product after heat treatment of the aluminum nitride sintered body, there is a problem that the yield is reduced and the labor for correcting the deformation in the subsequent process is increased, leading to a reduction in productivity.

Japanese Patent No. 3389484 JP 2006-196854 A

  Accordingly, an object of the present invention is an aluminum nitride sintered body that uses yttrium oxide as a sintering aid, and repairs the defect portion of the ceramic sintered body that is partially missing, and the aluminum nitride sintered body. Using a sintered body of aluminum nitride using yttrium oxide as a sintering aid, such as a process for joining bodies, a metallization process using the aluminum nitride sintered body, etc. An object of the present invention is to provide a method capable of preventing deformation of an aluminum nitride sintered body and producing a desired workpiece with high yield and good productivity.

As a result of intensive studies to achieve the above object, the present inventors have found that the high temperature thermal deformability of an aluminum nitride sintered body obtained by using yttrium oxide as a sintering aid is a high temperature range of 1750 ° C. or lower. In the study, it was found that the occurrence of the crystal phase of YAG (3Y ₂ O ₃ .5Al ₂ O ₃ ) in the grain boundary phase increases. And based on such knowledge, by using an aluminum nitride sintered body in which the abundance of YAG present in the grain boundary phase is limited, deformation of the sintered body in the treatment under the high temperature is effectively prevented. The inventors have found that an aluminum nitride sintered body without deformation can be obtained after the above-mentioned treatment, and completed the present invention.

  That is, the present invention includes a step of treating an aluminum nitride sintered body obtained by firing aluminum nitride powder using yttrium oxide as a sintering aid at a temperature of 1600 to 1750 ° C. In the production of a sintered product, the abundance of the YAG crystal phase in the grain boundary phase of the aluminum nitride sintered body subjected to the above treatment is an X-ray diffraction pattern of the YAG (211) plane relative to the aluminum nitride (100) plane The aluminum nitride sintered body having a strength ratio of 0.001 or less is used.

In the present invention, a YAP (Y ₂ O ₃ .Al ₂ O ₃ ) crystal phase, a YAM (2Y ₂ O ₃ .Al ₂ O ₃ ) crystal phase, and / or a Y ₂ O ₃ crystal phase in the grain boundary phase is used. Is a total of the intensity ratios of the X-ray diffraction patterns of the YAP (220) plane, the YAM (210) plane, and / or the Y ₂ O ₃ (400) plane with respect to the aluminum nitride (100) plane. 0.03 to 0.1 is particularly preferable in order to achieve high thermal conductivity of the obtained aluminum nitride sintered body and to further suppress thermal deformation in the treatment of the sintered body at a high temperature.

  According to the production method of the present invention, when the aluminum nitride sintered body obtained by using yttrium oxide as a sintering aid is subjected to treatment at a high temperature of 1600 to 1750 ° C., the grain boundary By limiting the abundance of the YAG crystal phase in the phase to the above range, deformation of the aluminum nitride sintered body due to the heat can be effectively suppressed.

  And in the manufacturing method of the workpiece accompanied with the high temperature treatment, if the abundance of the YAG crystal phase in the grain boundary phase of the aluminum nitride sintered body to be processed is controlled within the above range, the purpose is high yield and good productivity. It is possible to manufacture a workpiece to be manufactured.

  The method for producing an aluminum nitride sintered body according to the present invention is particularly useful in the production of a workpiece including a step of treating at a temperature of 1600 to 1750 ° C. Repair and bonding, aluminum nitride metallization treatment in the temperature range, and the like.

(Sintered aluminum nitride)
In the method of the present invention, the aluminum nitride sintered body to be used is obtained by firing aluminum nitride powder using yttrium oxide as a sintering aid, and in the auxiliary phase present at the grain boundaries. The abundance of the YAG crystal phase is below a specific amount, specifically, the abundance of YAG in the grain boundary phase is 0.001 in terms of the intensity ratio of the X-ray diffraction pattern of the YAG (211) plane to the aluminum nitride (100) plane. The biggest feature is that it is limited to the following. That is, when the amount of YAG present is greater than 0.001 in terms of the intensity ratio of the X-ray diffraction pattern, the amount of thermal deformation becomes large during processing at a high temperature of 1600 to 1750 ° C. Cannot be achieved.

  As described above, the reason why the thermal deformation of the sintered body at a high temperature can be suppressed by limiting the amount of YAG present in the crystal grain boundary of the aluminum nitride sintered body is not clear, but the present inventors Estimated as follows. That is, the YAG crystal phase has a lower melting point than the YAM crystal phase and the YAP crystal phase, and the once solidified YAG crystal phase becomes a liquid phase when processed at a high temperature of 1600 ° C. or higher. It is considered that heat deformation is considered to occur, and by limiting the abundance of the YAG, it is presumed that the phase change at a high temperature can be prevented and the heat deformation can be suppressed.

  In addition, in the treatment at a high temperature exceeding 1750 ° C., it is easily affected by other yttria compounds existing in the grain boundary, such as YAM crystal phase, YAP crystal phase, etc., and the effects of the present invention are sufficiently exhibited. I can't.

Further, the auxiliary phase for forming the grain boundary phase of the aluminum nitride sintered body used in the present invention can be obtained by using yttrium oxide as a sintering auxiliary, in addition to the YAG crystalline phase, the YAM crystalline phase, There exists a YAP crystal phase and / or a Y ₂ O ₃ crystal phase. Among them, the abundance of the YAM crystal phase, the YAP crystal phase, and / or the Y ₂ O ₃ crystal phase in the grain boundary phase is such that the YAP (220) plane, the YAM (210) plane, and / or the aluminum nitride (100) plane Alternatively, the total intensity ratio of the respective X-ray diffraction patterns on the Y ₂ O ₃ (400) plane is 0.03 to 0.1, and preferably 0.04 to 0.08.

  That is, when the total amount of the crystal phase in the grain boundary phase is less than the above range, the thermal conductivity of the obtained sintered body is lowered. Further, even if the total amount of the crystal phase is larger than the above range, the effect of improving the thermal conductivity is not limited, and the strength of the aluminum nitride sintered body may be lowered.

The method for measuring the intensity ratio of the X-ray diffraction pattern with respect to the aluminum nitride (100) plane for specifying the abundance of the YAG crystal phase, YAM crystal phase, YAP crystal phase, and Y ₂ O ₃ crystal phase is as follows: Measured according to the method shown in the examples described later.

  Other characteristics of the aluminum nitride sintered body used in the present invention are not particularly limited, but typical physical properties are as follows.

  For example, the average particle size of the aluminum nitride crystal grain size of the aluminum nitride sintered body is preferably about 2 to 15 μm.

  The shape of the aluminum nitride sintered body used in the present invention is appropriately determined according to the shape of the intended workpiece. Generally, it is a plate-like body, but can take any shape as another structure.

(Method for producing aluminum nitride sintered body)
The aluminum nitride sintered body used in the present invention can be basically obtained by a conventionally known method for producing an aluminum nitride sintered body, in which an aluminum nitride powder is fired using yttrium oxide as a sintering aid. it can.

  However, at that time, the condition that the YAG crystal phase existing in the grain boundary phase after firing is 0.001 or less in the intensity ratio of the X-ray diffraction pattern of the YAG (211) plane to the aluminum nitride (100) plane, that is, Therefore, it is necessary to employ a method of firing under conditions where the YAG crystal phase is difficult to be generated. If the said method is shown concretely, in the manufacturing method of the said aluminum nitride sintered compact, the production amount of a YAG crystal phase can be suppressed by increasing the addition amount of the yttrium oxide as a sintering auxiliary agent. Therefore, a method of limiting the amount of yttrium oxide used according to the amount of impurity oxygen inevitably contained in the aluminum nitride powder as the raw material of the sintered body is preferable. Further, it is effective to suppress the generation of the YAG crystal phase by performing reduction firing as the firing condition and controlling the reduction property of the reducing atmosphere at that time to be high.

  Specifically, a method for firing aluminum nitride powder using yttrium oxide as a sintering aid is controlled according to the aluminum nitride powder and the amount of impurity oxygen inevitably contained in the aluminum nitride powder. Examples include a method of molding a composition comprising yttrium oxide and organic binder into a predetermined green body shape, degreasing the green body, and firing at a temperature of 1700 to 2000 ° C. in a nitrogen atmosphere.

  The aluminum nitride powder used as the raw material is not particularly limited. However, in order to obtain a sintered body having sufficient strength, a powder having a particle size capable of achieving a crystal particle size of 2 to 15 μm by firing is preferably used. . In general, in consideration of grain growth during firing, those having an average particle size slightly smaller than the crystal grain size are preferably used. For example, those having an average particle size of 0.5 to 1.5 μm are suitable. is there.

  The content of oxygen atoms in the aluminum nitride powder is preferably 1% by mass or less, and more preferably 0.8% by mass or less, considering the thermal conductivity of the obtained sintered body. .

  In the present invention, yttrium oxide is used as a sintering aid. The particle size of the yttrium oxide is not particularly limited, but generally the smaller the particle size, the higher the activity and the better. For example, the average particle size is preferably 10 μm or less, and more preferably 5 μm or less. Moreover, the minimum of an average particle diameter is about 1 micrometer on manufacture.

  In the case where the oxygen content in the aluminum nitride powder is X mass%, the yttrium oxide contains 3.1X to 12.5X mass of yttrium oxide with respect to 100 parts by mass of the aluminum nitride powder when the green body is manufactured. Parts, preferably 4.7X to 9.4X parts by mass.

By using the sintering aid as described above, an aluminum nitride sintered body in which the grain boundary phase present in the obtained sintered body is composed of YAM, YAP or Y ₂ O ₃ and YAG is suppressed. Can be manufactured.

  That is, when the blending amount of yttrium oxide is less than the above range, the grain boundary phase present in the obtained sintered body contains a large amount of YAG crystal phase exceeding the above range, and therefore at a high temperature of 1600 to 1750 ° C. During the processing, the amount of thermal deformation tends to increase. Moreover, when there are more compounding quantities of an yttrium oxide than the said range, the effect of a heat conductivity improvement will not be acquired.

  The aluminum nitride powder and the sintering aid can be mixed by a known method. For example, a method of mixing by a dry method or a wet method using a mixer such as a ball mill can be suitably employed. In the above method, when wet mixing is performed, a dispersion medium such as water, alcohols and hydrocarbons is used, but alcohols and hydrocarbons are preferably used from the viewpoint of dispersibility.

Moreover, as an organic binder used in order to manufacture a green body, well-known things, such as butyral resins, such as polyvinyl butyral, acrylic resins, such as polymethacrylbutyl, are mentioned.
The organic binder is preferably blended in an amount of 0.1 to 30 parts by mass, preferably 1 to 15 parts by mass with respect to 100 parts by mass of the aluminum nitride powder.

  Moreover, in the composition for manufacturing a green body, you may add dispersing agents, such as glycerol compounds, and plasticizers, such as phthalic acid ester, as needed.

  The composition comprising the aluminum nitride powder, the sintering aid powder, and the organic binder is formed into a sheet-like green body by, for example, a doctor blade method. The obtained green body is subjected to baking after degreasing (debinding).

The degreasing is performed by heating in an arbitrary atmosphere such as in air, nitrogen, or hydrogen, and the temperature in degreasing varies depending on the type of organic binder, but is preferably 300 to 900 ° C, and preferably 300 to 700 ° C. Particularly preferred.
The amount of residual carbon in the defatted body and the adjustment method thereof are not particularly limited. As described above, in order to adjust the reducing atmosphere high, for example, the amount of residual carbon in the defatted body is 250 ppm or more and 1000 ppm or less. It is preferable that it is 300 ppm or more and 500 ppm or less. Such residual carbon amount is a method of adjusting the degreasing time and degreasing temperature of the green body, a method of adjusting the amount of the organic binder used for the production of the green body, a method of selecting the type of the organic binder, etc. Or it can employ | adopt in combination.

  In addition, when it shape | molds without using an organic binder like the compression molding method, said degreasing process is unnecessary.

  Next, the molded body is fired to obtain an aluminum nitride sintered body. Firing is performed in a reducing atmosphere using an inert gas such as argon or nitrogen. Further, as a firing container, a non-carbon container such as an aluminum nitride sintered body or a boron nitride molded body may be used, and the molded body may be accommodated in the container and fired.

  Moreover, in order to suppress the production | generation amount of the YAG crystal phase which exists in the grain-boundary phase of the obtained aluminum nitride sintered compact, it is preferable to perform the said baking in a comparatively strong reducing atmosphere. Examples of the method for realizing firing in the reducing atmosphere include a method of coexisting a carbon source with a molded body in a firing container, a method using a carbon product as a firing container, and the like. Among them, a method in which the molded body and the carbon generation source coexist in the firing container is suitable. In particular, in order to suppress the formation of the YAG crystal phase, the firing container is a sealed container, and this sealed A method of accommodating the molded body and the carbon generation source in the container is most preferable.

  Further, the generation source of the carbon is not particularly limited, and a known form of carbon such as amorphous carbon or graphite can be used, and solid carbon is preferable. The shape of the carbon is not particularly limited, and may be any of powder, fiber, felt, sheet, and plate, or a combination thereof. Among these, in consideration of obtaining higher thermal conductivity, plate-like amorphous carbon and graphite are suitable.

  Furthermore, the method for accommodating the compact and carbon in the container is not particularly limited, and the carbon and the compact may be accommodated in any form of non-contact or contact. Among these, the non-contact form is preferable from the viewpoint of easy control of the thermal conductivity of the obtained sintered body. The non-contact form may be a known form. For example, a method of simply providing a gap between the carbon and the molded body, or a powder such as boron nitride interposed between the carbon and the molded body. The method of making it non-contact, and the method of making non-contact by installing a ceramic plate such as aluminum nitride and boron nitride between carbon and the molded body, etc. are mentioned, but considering the improvement of thermal conductivity Then, a method of placing a plate or the like between the carbon and the molded body to make it non-contact is preferable, and in particular, the space containing the carbon and the space containing the molded body in the sealed container should be blocked as much as possible. A method of installing a plate is preferable in order to suppress the formation of the YAG crystal phase.

  It is preferable to obtain an aluminum nitride sintered body by firing at a temperature of 1700 to 2000 ° C., preferably 1700 to 1900 ° C., more preferably 1700 to 1850 ° C., for at least 3 hours, particularly 5 hours or more.

  In addition, the aluminum nitride sintered body obtained after firing may be subjected to the next process as it is, or may be subjected to a treatment such as polishing if necessary.

(Production method of aluminum nitride sintered product)
The method for producing a workpiece according to the present invention includes a step of treating the aluminum nitride sintered body at a temperature of 1600 to 1750 ° C. using the specific aluminum nitride sintered body (hereinafter also referred to as a high temperature treatment step). including.

  The high temperature treatment step includes all known treatments performed at the treatment temperature. Typical processes include a repair process for the aluminum nitride sintered body, a joining process for joining the aluminum nitride sintered bodies, and a metallization process.

(Repair treatment of aluminum nitride)
The repair process of the aluminum nitride sintered body will be described in detail below.
First, a paste containing a sintering aid and ceramic powder is filled in a defective portion of a partially broken aluminum nitride sintered body, and the ceramic powder is sintered by heating the paste at 1600 to 1750 ° C. The process to make is mentioned.

  As this ceramic powder, a ceramic powder having a component different from that of the aluminum nitride sintered body to be repaired can be used, but it is preferable to use an aluminum nitride powder having the same component.

  A method for heating the portion filled with the paste is not particularly limited, but a method using a sintering furnace and a method of irradiating electromagnetic waves are common.

  Here, the paste may further contain a sintering aid, and the sintering temperature of the ceramic powder in the paste can be lowered by containing the sintering aid. In particular, in the heating method of irradiating the electromagnetic wave, when the ceramic powder is a substance having a small dielectric loss factor such as aluminum nitride and self-heating due to electromagnetic wave irradiation is difficult near room temperature, a sintering aid is used. By using this, the sintering aid is self-heated by electromagnetic wave irradiation, and the heat generation raises the temperature of the ceramic powder having a low dielectric loss factor to a temperature at which self-heating is possible, and then the ceramic powder is sintered by electromagnetic wave irradiation. Can be tied.

Examples of the sintering aid include yttrium (Y), calcium (Ca), cerium (Ce), holmium (Ho), ytterbium (Yb), gadolinium (Gd), neodymium (Nd), samarium (Sm), dysprosium ( A compound containing at least one element selected from the group consisting of Dy) and strontium (Sr) is preferred, and the form of this compound is preferably an oxide, nitride, chloride, nitrate, carbonate, fluoride Can be mentioned. More specifically, for example, when the ceramic powder is aluminum nitride, Y ₂ O ₃ and CaO are preferable.

  When using a sintering aid, the ceramic powder and the sintering aid are in a mass ratio in the paste, ceramic powder: sintering aid = 100: 0.5-10, preferably It is desirable to be included at a ratio of 100: 2-7.

  In addition, when the paste includes a sintering aid, the paste may further include carbon powder. When carbon powder is contained, it is preferable in that scattering of the sintering aid can be promoted during heating by electromagnetic wave irradiation. The carbon powder is desirably contained in a mass ratio of ceramic powder: carbon powder = 100: 0.5 to 30, preferably 100: 1 to 10. When the proportion of the carbon powder is within the above range, scattering of the sintering aid can be promoted during sintering.

  Examples of the solvent contained in the paste include ethyl cellulose and terpineol. The content of the solvent may be 10 to 50% by mass in the paste at room temperature (25 ° C.). Moreover, the said paste may contain the viscosity modifier, the dispersing agent, etc.

  When repairing the ceramic sintered body by the above method, the defective portion of the ceramic sintered body is excessively filled with paste to such an extent that an excess portion is formed after sintering, and the excess portion is sintered after the ceramic powder is sintered. It is preferable that the shape of the repaired part is adjusted by polishing. Although it is difficult to directly obtain a desired shape by sintering the filled paste, the repaired portion can be easily formed into a desired shape by adopting such a method.

(Joint treatment of aluminum nitride sintered body)
Next, the joining process between aluminum nitride sintered bodies will be described. An inclusion containing a sintering aid is disposed between the joint surface of one aluminum nitride sintered body and the joint surface of the other aluminum nitride sintered body, and the inclusion is heated to 1600-1750 ° C. The method of joining the aluminum nitride sintered compact which joins this aluminum nitride sintered compact is mentioned.

The shape of the aluminum nitride sintered body to be joined is not particularly limited, and may be, for example, a prismatic shape, a cylindrical shape, or a lump shape, but in order to obtain an aluminum nitride joined body having more reliable joining strength. It is preferable that the joining surface of the aluminum nitride sintered bodies is flattened by polishing finish or the like so that no gap is generated when the aluminum nitride sintered bodies are brought into contact with each other.
Between the joint surfaces of the aluminum nitride sintered body, an inclusion containing a sintering aid is disposed so as to contact the joint surface.

  The inclusions disposed between the joining surfaces of the aluminum nitride sintered body include paste containing the sintering aid, green body of aluminum nitride containing the sintering aid, and nitriding containing the sintering aid. Examples include aluminum degreased bodies, and among these, the paste is preferable in that it can be easily applied and can be applied to a complex-shaped joint surface.

  As the sintering aid, a sintering aid used in the repair process can be used. The paste can be prepared in the same manner as described in the repair process.

(Metalization processing)
Finally, the metallization process will be described. Formation of a conductive layer made of a refractory metal by a post-fire method is called a metallization process, and is performed by laminating a conductive paste on an aluminum nitride sintered body and firing it at a temperature of 1600 to 2000 ° C. In particular, the present invention is preferably applied when the metallization treatment is performed at a temperature of 1600 to 1750 ° C.

  As the conductive paste, a known conductive paste composed of components such as a metal powder, an organic binder, an organic solvent, a dispersant, and a plasticizer can be used without particular limitation. In addition, it is preferable that the conductive paste contains an aluminum nitride powder because adhesion with the sintered aluminum nitride after firing can be improved.

  Examples of the metal powder contained in the conductive paste include tungsten, molybdenum, gold, silver, copper, and other metal powders. Among them, tungsten and molybdenum, which have heat resistance against high temperatures during firing, are sintered at 1750 ° C. or lower. High melting point metal powders that can be

  Moreover, as an organic binder contained in the conductive paste, known ones can be used without particular limitation. For example, acrylic resins such as polyacrylic acid ester and polymethacrylic acid ester, cellulose resins such as methyl cellulose, hydroxymethyl cellulose, nitrocellulose, and cellulose acetate butyrate, vinyl group-containing resins such as polyvinyl butyral, polyvinyl alcohol, and polyvinyl chloride, A hydrocarbon resin such as polyolefin and an oxygen-containing resin such as polyethylene oxide can be used singly or in combination.

  Furthermore, as the organic solvent contained in the conductive paste, known ones can be used without particular limitation. For example, toluene, ethyl acetate, terpineol, butyl carbitol acetate, texanol and the like can be used, and it is more preferable to select a solvent that easily dissolves the resin of the conductive paste.

  Furthermore, a well-known thing can be especially used as a dispersing agent contained in an electrically conductive paste without a restriction | limiting. For example, a phosphate ester-based or polycarboxylic acid-based dispersant can be used. Moreover, as a plasticizer contained in an electrically conductive paste, a well-known thing can be especially used without a restriction | limiting. For example, dioctyl phthalate, dibutyl phthalate, diisononyl phthalate, diisodecyl phthalate, dioctyl adipate and the like can be used.

Application of the conductive paste to the aluminum nitride sintered body can be performed by a known method such as screen printing, calendar printing, or pad printing. The thickness of the conductive paste layer to be formed is not particularly limited, but is generally about 1 to 100 μm, preferably about 5 to 30 μm.
In this manufacturing method, a sintered product is obtained by firing the conductive paste layer laminated on the surface of the aluminum nitride sintered substrate as described above at a high temperature. If necessary, degreasing may be performed before firing the conductive paste layer.

  The degreasing is carried out in an atmosphere of humidified gas in which an oxidizing gas such as oxygen or air, a reducing gas such as hydrogen, an inert gas such as argon or nitrogen, carbon dioxide and a mixed gas or water vapor thereof is mixed. This is performed by heat-treating the aluminum nitride sintered body substrate on which is laminated. Moreover, what is necessary is just to select heat processing conditions suitably from the range of temperature: 300 degreeC-900 degreeC and holding time: 1 minute-1000 minutes according to the kind and quantity of the organic component contained in the said paste layer.

  The baking performed subsequent to the degreasing treatment may be performed at a temperature of 1600 to 1750 ° C., preferably 1700 to 1750 ° C. for 3 hours or more, preferably 5 hours or more. As an atmosphere at the time of firing, it may be performed at normal pressure in an atmosphere of non-oxidizing gas such as nitrogen gas.

  Although the above method has been described with respect to the metallization treatment, the high temperature treatment step in the present invention includes a method of performing treatment for forming aluminum nitride not containing a conductive metal and other ceramic layers on the aluminum nitride sintered body. In this case, the same treatment can be performed using a paste having a composition obtained by removing the conductive metal component from the conductive paste.

  The high temperature treatment in the present invention is not particularly limited, and the method of the present invention can be suitably applied as long as the treatment is performed at a temperature of 1600 to 1750 ° C. using aluminum nitride.

As an application of the manufacturing method of the aluminum nitride sintered body according to the present invention, the aluminum nitride sintered body supplied to the high temperature treatment step is converted into YAG (3Y ₂ O ₃ .5Al ₂ O ₃ ) crystal in the grain boundary phase. Process control so that the abundance of the phase is measured and the abundance of the YAG is controlled to be 0.001 or less in terms of the intensity ratio of the X-ray diffraction pattern of the YAG (211) plane to the aluminum nitride (100) plane By adopting such a method, it is possible to dramatically improve the yield of the obtained workpiece.

  EXAMPLES Hereinafter, examples will be shown to describe the present invention more specifically, but the present invention is not limited to these examples.

  Various measurements in Examples and Comparative Examples were performed by the following methods.

(1) Density of aluminum nitride sintered body The density of the sintered body was measured by using Archimedes method.

(2) Thermal conductivity of aluminum nitride sintered body It was measured by a one-dimensional method by a laser flash method using “LFA-502” (trade name) manufactured by Kyoto Electronics Industry Co., Ltd.

(3) X-ray diffraction measurement was performed using a sintering aid-containing phase contained in the aluminum nitride sintered body and a peak intensity ratio “RINT-1400” (trade name) manufactured by Rigaku Denki. The measurement surface of the sample was a surface ground to about half the sample thickness.

X-ray source: Cu-Kα 40 kV-200 mA
2θ scanning range: 10 ° to 70 °
2θ scanning speed: 5 ° / min 2θ scanning step width: 0.02 °
Number of measurements: 1 time / sample The obtained diffraction peak is a peak identified in aluminum nitride and a peak identified in one or several kinds of grain boundary phases generated from the sintering aid. The XRD intensity of the aluminum nitride phase was the peak intensity of the (hkl) = (100) plane, and the XRD intensity of each grain boundary phase was selected as a peak having a relatively similar relative intensity between the grain boundary phases. For example, the peak intensity (relative intensity 27) of the (hkl) = (211) plane in the YAG crystal phase, the peak intensity (relative intensity 23) of the (hkl) = (220) plane in the YAP crystal phase, and (hkl) in the YAM crystal phase. ) = (210) plane peak intensity (relative intensity 23) and (hkl) = (400) plane peak intensity (relative intensity 24) in the Y ₂ O ₃ crystal phase. Therefore, the XRD intensity of the aluminum nitride phase is I (aluminum nitride), the XRD intensity of the YAG crystal phase is I (YAG), the XRD intensity of the YAP crystal phase is I (YAP), and the XRD intensity of the YAM crystal phase is I (YAM) When the XRD intensity of the Y ₂ O ₃ crystal phase is I (Y ₂ O ₃ ), the XRD intensity of each grain boundary phase is expressed as follows.

YAG crystal phase: I (YAG) / I (aluminum nitride)
YAP crystal phase: I (YAP) / I (aluminum nitride)
YAM crystal phase: I (YAM) / I (aluminum nitride)
Y ₂ O ₃ crystal phase: I (Y ₂ O ₃ ) / I (aluminum nitride)
Further, the total XRD strength of each grain boundary phase excluding the YAG crystal phase was defined as the amount of the auxiliary phase remaining in the aluminum nitride sintered body. That is, when the XRD strength of the aluminum nitride phase is I (aluminum nitride) and the XRD strength of the grain boundary phase excluding the YAG crystal phase is I (grain boundary), the amount of the remaining auxiliary phase is I (grain boundary) / I (aluminum nitride).

(4) Amount of thermal deformation The following test was carried out as an index for quantitatively measuring the amount of deformation of the obtained aluminum nitride sintered body after the high temperature treatment.

  The test piece was ground and cut so as to have a length of 65 mm, a width of 20 mm, and a thickness of 1 mm, and this was placed so as to be bridged on an aluminum nitride block placed at an interval of 50 mm. Next, by placing a tungsten heavy stone having a width of 40 mm on the test piece, the load applied during the test was 162 gf in the thickness direction of the test piece. These aluminum nitride sintered body test pieces, aluminum nitride blocks and tungsten barite were placed in a boron nitride molded body container, and held at 1700 ° C. for 5 hours in a nitrogen atmosphere. By measuring the deformation amount of the test piece after the above test, it was used as an index for measuring the deformation amount after the high temperature treatment.

The amount of thermal deformation (W) of the test piece is the maximum in the cross-section in the thickness direction of the test piece, the straight line connecting both end points of the surface opposite to the surface on which the tungsten weight is placed, and the surface having both end points connecting the straight lines. The distance R (μm) is measured, and is calculated from the maximum distance R and the length L (mm) between the end points by the following formula.
W (μm / mm) = (R / L)
When the amount of thermal deformation was 120 μm / mm or less, it was confirmed that the amount of deformation of the aluminum nitride sintered body after baking the paste layer by the postfire method was reduced, and the flatness of the electronic component mounting portion was improved.

Example 1
An apparently filling alumina ball having a Vickers hardness of 1200 and a ball diameter of 10 mm is put in a nylon pot having an internal volume of 10 (liters: 1), and then yttrium oxide is added to 100 parts by mass of the aluminum nitride powder. 5 parts by mass, 2 parts by mass of sorbitan triolate as a surfactant, 21 parts by mass of toluene, 12.25 parts by mass of ethanol and 1.75 parts by mass of butanol were added, and the first ball mill mixing was performed for 16 hours. Then, 8 parts by weight of polyvinyl butyral as a binder, 3.5 parts of dibutyl phthalate as a plasticizer, 27 parts by weight of toluene, 15.75 parts by weight of ethanol, and 2.25 parts by weight of butanol as a solvent were added to this mixture for the second time. Ball mill mixing was performed for 18 hours to obtain a white slurry (hereinafter referred to as slurry). The obtained slurry was filtered through a filter having an opening of 10 μm, and then the solvent was removed, and the viscosity was adjusted to 20000 to 30000 cps. Thereafter, a sheet was formed by a doctor blade method, and dried at room temperature for 1 hour, at 60 ° C. for 2 hours, and at 100 ° C. for 1 hour to produce a green sheet having a width of 200 mm and a thickness of 1.5 mm. Furthermore, it processed into the green body of 140x120mm with the punching press processing machine.

  The green body thus obtained was degreased in air at a temperature of 530 ° C. for 4 hours to obtain a degreased body having a residual carbon ratio of 400 ppm. Thereafter, the degreased body was placed in a firing container made of boron nitride and fired in a nitrogen atmosphere at 1740 ° C. for 5 hours.

  Table 1 shows the physical properties and thermal deformation of the obtained sintered body.

(High temperature processing)
The aluminum nitride sintered body substrate obtained by the above method was subjected to paste layer baking by a post-fire method as high-temperature processing.

  A tungsten paste was prepared by kneading 100 parts by mass of tungsten powder having an average particle diameter of 3.0 μm, 5 parts by mass of aluminum nitride powder having an average particle diameter of 1.5 μm, 2 parts by mass of ethyl cellulose, and 10 parts by mass of terpineol. The tungsten paste was screen-printed on the aluminum nitride sintered substrate. At this time, pattern formation was performed so that ten pattern units were arranged in a lattice shape on the aluminum nitride sintered body substrate 10 by 10 in the vertical and horizontal directions.

The aluminum nitride sintered body substrate on which the pattern was formed by the above method was degreased in air at 200 ° C. for 2 hours, and then fired in a nitrogen atmosphere at 1700 ° C. for 8 hours. The obtained metallized substrate was cut to obtain 100 pattern units. When the warp inspection of the pattern unit obtained by the high temperature treatment step was performed and a unit having a warp of 3 μm / mm or less was accepted, it was confirmed that a workpiece was obtained with a yield of 100%. In the following examples and comparative examples, the yield was examined in the same manner as in the above method.
(Example 2)
In Example 1, a sintered body was obtained and evaluated in the same manner as in Example 1 except that the amount of yttrium oxide added was changed to 7 parts by mass. Table 1 shows the physical properties and thermal deformation of the obtained sintered body. Using the aluminum nitride sintered body, a workpiece was produced in the same manner as in Example 1. It was confirmed that the workpiece was obtained with a yield of 100%.
(Example 3)
In Example 1, a sintered body was obtained and evaluated in the same manner as in Example 1 except that the amount of yttrium oxide added was changed to 9 parts by mass. Table 1 shows the physical properties and thermal deformation of the obtained sintered body. Using the aluminum nitride sintered body, a workpiece was produced in the same manner as in Example 1. It was confirmed that the workpiece was obtained with a yield of 100%.
Example 4
In Example 1, a sintered body was obtained and evaluated in the same manner as in Example 1 except that the firing time was changed to 15 hours. Table 1 shows the physical properties and thermal deformation of the obtained sintered body. Using the aluminum nitride sintered body, a workpiece was produced in the same manner as in Example 1. It was confirmed that the workpiece was obtained with a yield of 100%.
(Comparative Example 1)
In Example 1, a sintered body was obtained and evaluated in the same manner as in Example 1 except that the amount of yttrium oxide added was changed to 2 parts by mass. Table 1 shows the physical properties of the obtained sintered body. Using the aluminum nitride sintered body, a workpiece was produced in the same manner as in Example 1. It was confirmed that the yield decreased to 93.4%.
(Comparative Example 2)
In Comparative Example 1, a sintered body was obtained and evaluated in the same manner as Comparative Example 1 except that the firing time was changed to 15 hours. Table 1 shows the physical properties of the obtained sintered body. Using the aluminum nitride sintered body, a workpiece was produced in the same manner as in Example 1. It was confirmed that the yield decreased to 97.5%.

In the above examples, the yield of the obtained workpieces was 100%, whereas the yield of the workpieces in the comparative example was 93 to 98%. If the process of manufacturing with a yield of 100% of the workpiece can be managed as in the example, it is possible to make a sampling inspection where all the conventional products have been inspected. The difference from the above comparative example is very large in that it can be significantly suppressed.

Claims (2)

Workpiece of the aluminum nitride sintered body comprising a step of treating an aluminum nitride sintered body obtained by firing aluminum nitride powder using yttrium oxide as a sintering aid at a temperature of 1600 to 1750 ° C. In the production of the aluminum nitride sintered body to be subjected to the above treatment, the amount of YAG (3Y ₂ O ₃ .5Al ₂ O ₃ ) crystal phase in the grain boundary phase is YAG (211) plane relative to the aluminum nitride (100) plane An aluminum nitride sintered body having an intensity ratio of an X-ray diffraction pattern of 0.001 or less is used. The amount of YAM (2Y ₂ O ₃ .Al ₂ O ₃ ) crystal phase, YAP (Y ₂ O ₃ .Al ₂ O ₃ ) crystal phase, and / or Y ₂ O ₃ crystal phase in the grain boundary phase is nitrided The total intensity ratio of the X-ray diffraction patterns of the YAP (220) plane, YAM (210) plane, and / or Y ₂ O ₃ (400) plane relative to the aluminum (100) plane is 0.03 to 0.1. The manufacturing method of the aluminum nitride sintered compact processed material of Claim 1 which is these.