阅读说明：本技术 陶瓷烧结体以及半导体装置用基板 (Ceramic sintered body and substrate for semiconductor device ) 是由 梅田勇治 河野浩 于 2018-12-06 设计创作，主要内容包括：陶瓷烧结体(3)包含Zr、Al、Y和Mg,Zr的含量以ZrO-2换算为7.5质量％以上且23.5质量％以下,Al的含量以Al-2O-3换算为74.9质量％以上且91.8质量％以下,Y的含量以Y-2O-3换算为0.41质量％以上且1.58质量％以下,Mg的含量以MgO换算为0.10质量％以上且0.80质量％以下。陶瓷烧结体(3)的热老化后M相率为15％以下。(The ceramic sintered body (3) contains Zr, Al, Y and Mg, the Zr content being ZrO 2 Converted to 7.5-23.5 mass%, and Al content is calculated as Al 2 O 3 Converted into 74.9-91.8 mass%, and the content of Y is Y 2 O 3 0.41 to 1.58 mass% in terms of MgO, and 0.10 to 0.80 mass% in terms of Mg. The ceramic sintered body (3) has an M-phase ratio of 15% or less after heat aging.)

1. A ceramic sintered body comprising Zr, Al, Y and Mg,

zr content in ZrO₂Converted to 7.5 to 23.5 mass%,

the content of Al is as follows₂O₃Converted to 74.9 to 91.8 mass%,

the content of Y is as follows₂O₃Converted to 0.41 to 1.58 mass%,

the content of Mg is 0.10-0.80 mass% in terms of MgO,

the ceramic sintered body contains ZrO₂The crystalline phase is used as a crystalline phase,

the ZrO₂The crystal phase has a monoclinic phase and a tetragonal phase as crystal structures,

when the heat aging treatment is performed for 100 hours in an environment of 180 ℃, the ratio of the peak intensity of the monoclinic phase to the sum of the peak intensities of the monoclinic phase and the tetragonal phase in the X-ray diffraction pattern is 15% or less.

2. The ceramic sintered body according to claim 1,

when the heat aging treatment is performed for 100 hours in an environment of 180 ℃, the ratio of the peak intensity of the monoclinic phase to the sum of the peak intensities of the monoclinic phase and the tetragonal phase in the X-ray diffraction pattern is 4% or more.

3. The ceramic sintered body according to claim 1 or 2,

the ceramic sintered body contains Al₂O₃Crystalline phase and MgAl₂O₄The crystalline phase is used as a crystalline phase,

MgAl in an X-ray diffraction pattern before the heat aging treatment is performed₂O₄Peak strength of crystalline phase relative to Al₂O₃The ratio of the peak intensity of the crystal phase is 4% or less.

4. The ceramic sintered body according to any one of claims 1 to 3,

when the heat aging treatment is performed for 100 hours in an environment of 180 ℃, the flexural strength is 500MPa or more.

5. The ceramic sintered body according to any one of claims 1 to 4,

before the heat aging treatment, a ratio of a peak intensity of the monoclinic phase to a sum of peak intensities of the monoclinic phase and the tetragonal phase in an X-ray diffraction pattern is 7% or less.

Technical Field

The present invention relates to a ceramic sintered body and a substrate for a semiconductor device.

Background

As substrates for semiconductor devices used in power transistor modules and the like, there are known a DBOC Substrate (Direct Bonding of Copper Substrate) having a Copper plate on a surface of a ceramic sintered body, and a DBOA Substrate (Direct Bonding of Aluminum Substrate, Direct Copper-clad Aluminum plate) having an Aluminum plate on a surface of a ceramic sintered body.

Patent document 1 discloses a ceramic sintered body containing alumina, partially stabilized zirconia, and magnesia. In the ceramic sintered body described in patent document 1, the content of partially stabilized zirconia is 1 to 30 wt%, the content of magnesia is 0.05 to 0.50 wt%, the mole fraction of yttria in the partially stabilized zirconia is 0.015 to 0.035, and 80 to 100% of zirconia crystals contained in the ceramic sintered body are tetragonal phases. According to the ceramic sintered body described in patent document 1, the mechanical strength can be improved, and the occurrence of cracks and voids (partial peeling or floating) at the joint interface between the ceramic sintered body and the copper plate or the aluminum plate can be suppressed.

Patent document 2 discloses a ceramic sintered body containing alumina, zirconia, and yttria. In the ceramic sintered body described in patent document 2, the content of zirconia is 2 to 15% by weight, and the average particle size of alumina is 2 to 8 μm. According to the ceramic sintered body described in patent document 2, the thermal conductivity can be improved.

Patent document 3 discloses a ceramic substrate containing alumina, a stabilizing component, hafnium oxide, and zirconium oxide. In the ceramic substrate described in patent document 3, the weight ratio of hafnium oxide and zirconium oxide to aluminum oxide is 7 to 11, the average particle size of aluminum oxide is 1.0 to 1.5 μm, and the average particle size of zirconium oxide is 0.3 to 0.5 μm. According to the ceramic sintered body described in patent document 3, the thermal conductivity can be improved.

Prior art documents

Patent document

Patent document 1: japanese patent No. 4717960

Patent document 2: japanese laid-open patent publication No. 2015-534280

Patent document 3: international publication No. 2016-208766

Disclosure of Invention

Problems to be solved by the invention

However, the ceramic sintered bodies described in patent documents 1 to 3 have a problem that the mechanical strength is easily lowered when exposed to a high-temperature environment, and a problem that cracks are easily generated when a heat cycle is repeated in a state of being assembled to a substrate for a semiconductor device.

The present invention aims to provide a ceramic sintered body which can suppress the reduction of mechanical strength and the generation of cracks.

Means for solving the problems

The ceramic sintered body of the present invention contains Zr, Al, Y and Mg, the Zr content being ZrO₂Converted to 7.5-23.5 mass%, and Al content is calculated as Al₂O₃Converted into 74.9-91.8 mass%, and the content of Y is Y₂O₃0.41 to 1.58 mass% in terms of MgO, and 0.10 to 0.80 mass% in terms of Mg. The ceramic sintered body contains ZrO₂The crystal phase is taken as a crystal phase. ZrO (ZrO)₂The crystal phase has a monoclinic phase and a tetragonal phase as crystal structures. When the heat aging treatment is performed for 100 hours in an environment of 180 ℃, the ratio of the peak intensity of the monoclinic phase to the sum of the peak intensities of the monoclinic phase and the tetragonal phase in the X-ray diffraction pattern is 15% or less.

Effects of the invention

According to the present invention, a ceramic sintered body in which a decrease in mechanical strength and the occurrence of cracks can be suppressed can be provided.

Drawings

Fig. 1 is a cross-sectional view showing a structure of a semiconductor device according to an embodiment.

Fig. 2 is a flowchart for explaining a method of manufacturing a substrate for a semiconductor device according to an embodiment.

Fig. 3 is a sectional view showing the structure of a substrate sample for a semiconductor device according to an embodiment.

Detailed Description

The ceramic sintered body according to the present invention and the structure of the substrate for a semiconductor device using the same will be described below with reference to the drawings.

(Structure of semiconductor device 1)

Fig. 1 is a cross-sectional view of a semiconductor device 1 according to an embodiment. The semiconductor device 1 is used as a power module in various electronic devices such as an automobile, an air conditioner, an industrial robot, a commercial elevator, a household microwave oven, an IH rice cooker, power generation (wind power generation, solar power generation, a fuel cell, and the like), a power train, and an UPS (uninterruptible power supply).

The semiconductor device 1 includes a substrate 2 for a semiconductor device, a1 st bonding material 5, a 2 nd bonding material 5', a semiconductor chip 6, a bonding wire 7, and a heat sink 8.

The Substrate 2 for a semiconductor device is a so-called DBOC Substrate (Direct Bonding of Copper Substrate). The substrate 2 for a semiconductor device includes a ceramic sintered body 3, a1 st copper plate 4, and a 2 nd copper plate 4'.

The ceramic sintered body 3 is an insulator for the semiconductor device substrate 2. The ceramic sintered body 3 is formed in a flat plate shape. The ceramic sintered body 3 is a substrate of the substrate 2 for a semiconductor device. The structure of the ceramic sintered body 3 will be described later.

The 1 st copper plate 4 is bonded to the surface of the ceramic sintered body 3. The 1 st copper plate 4 is formed with a power transmission circuit. The 2 nd copper plate 4' is joined to the back surface of the ceramic sintered body 3. The 2 nd copper plate 4' is formed in a flat plate shape.

The Substrate 2 for a semiconductor device may be a so-called DBOA Substrate (Direct Bonding of Aluminum Substrate) using a1 st and a 2 nd Aluminum plate instead of the 1 st and the 2 nd copper plates 4 and 4'. In the DBOA substrate using an aluminum plate that is more flexible than the copper plate, the thermal stress generated inside can be further relaxed.

In the semiconductor device substrate 2, the 1 st copper plate 4 having the power transmission circuit formed thereon is bonded to the surface of the ceramic sintered body 3, but the power transmission circuit may be formed by a subtractive method or an additive method.

The method for manufacturing the substrate 2 for a semiconductor device is not particularly limited, and can be manufactured as follows, for example. First, a laminate in which the 1 st and 2 nd copper plates 4 and 4' are disposed on the front and back surfaces of the ceramic sintered body 3 is formed. Subsequently, the laminate was heated at 1070 to 1075 ℃ for 10 minutes in a nitrogen atmosphere. As a result, a Cu — O eutectic liquid phase is formed at the interface where the ceramic sintered body 3 and the 1 st and 2 nd copper plates 4 and 4' are joined (hereinafter collectively referred to as "joint interface"), and the front and back surfaces of the ceramic sintered body 3 are wet. Subsequently, the laminate is cooled to solidify the Cu — O eutectic liquid phase, and the 1 st and 2 nd copper plates 4 and 4' are bonded to the ceramic sintered body 3.

The 1 st bonding material 5 is disposed between the 1 st copper plate 4 and the semiconductor chip 6. The semiconductor chip 6 is bonded to the 1 st copper plate 4 via the 1 st bonding material 5. The bonding wire 7 connects the semiconductor chip 6 and the 1 st copper plate 4.

The 2 nd bonding material 5 'is disposed between the 2 nd copper plate 4' and the heat spreader 8. The heat sink 8 is bonded to the 2 nd copper plate 4 'via the 2 nd bonding material 5'. The heat sink 8 may be made of copper, for example.

(constituent element of ceramic sintered body 3)

The ceramic sintered body 3 contains Zr (zirconium), Al (aluminum), Y (yttrium), and Mg (magnesium).

The contents of the respective constituent elements in the ceramic sintered body 3 are as follows.

Zr: with ZrO₂Converted into 7.5 to 23.5 mass%

Al: with Al₂O₃Converted into 74.9-91.8 mass%

Y: with Y₂O₃Converted into 0.41-1.58 mass%

Mg: 0.10 to 0.80 mass% in terms of MgO

It is considered that the Zr content is adjusted to ZrO by adding Zr₂By setting the conversion to 7.5 mass% or more, the coefficient of linear thermal expansion of the ceramic sintered body 3 can be suppressed from becoming excessively small, and the difference in coefficient of linear thermal expansion between the ceramic sintered body 3 and the 1 st and 2 nd circuit boards 4 and 4' can be reduced.As a result, it is considered that the thermal stress generated at the bonding interface can be reduced, and the generation of cracks due to thermal cycles can be suppressed.

It is considered that the Zr content is adjusted to ZrO by adding Zr₂The conversion is set to 23.5 mass% or less, so that excessive reaction at the joint interface can be suppressed when the circuit boards are joined. As a result, it is considered that the generation of voids at the bonding interface is suppressed.

It is considered that the content of Y is defined as Y₂O₃The conversion is 0.41 mass% or more, and the M phase ratio can be suppressed from becoming too large after heat aging, which will be described later. As a result, it is considered that the reduction of the mechanical strength of the ceramic sintered body 3 due to the heat aging treatment is suppressed.

It is considered that the content of Y is defined as Y₂O₃The conversion is 1.58 mass% or less, and the M phase ratio after heat aging described later can be suppressed from becoming too small. As a result, it is considered that the reduction of the mechanical strength of the ceramic sintered body 3 due to the heat aging treatment is suppressed.

It is considered that, by setting the Mg content to 0.10 mass% or more in terms of MgO, the ceramic sintered body 3 can be sintered without excessively raising the firing temperature, and Al can be suppressed₂O₃Particles and ZrO₂The particles are coarsened. As a result, it is considered that the mechanical strength of the ceramic sintered body 3 can be improved, and the occurrence of cracks due to thermal cycles can be suppressed. Further, it is considered that a sufficient amount of MgAl can be formed in the ceramic sintered body 3₂O₄(spinel) crystals capable of improving wettability with a Cu-O eutectic liquid phase at the time of circuit board bonding. As a result, it is considered that the generation of voids at the bonding interface is suppressed.

It is considered that excessive growth of alumina crystals and zirconia crystals can be suppressed and the mechanical strength of the ceramic sintered body 3 can be improved by setting the Mg content to 0.80 mass% or less in terms of MgO. As a result, it is considered that the generation of cracks due to thermal cycles is suppressed. Further, it is considered that sintering of ceramics can be suppressedExcess MgAl is produced in the body 3₂O₄The crystal can inhibit reaction at the joint interface from becoming excessive when the circuit boards are jointed. As a result, it is considered that the generation of voids at the bonding interface is suppressed.

In the present embodiment, the content of the constituent element of the ceramic sintered body 3 is calculated in terms of oxide as described above, but the constituent element of the ceramic sintered body 3 may be present in the form of oxide or may not be present in the form of oxide. For example, Y, Mg and at least 1 of Ca may be present in the form of oxides and may be dissolved in ZrO without being dissolved in the form of oxides₂In (1).

The content of the constituent element of the ceramic sintered body 3 in terms of oxide is calculated as follows. First, the constituent elements of the ceramic sintered body 3 were qualitatively analyzed by a fluorescence X-ray analyzer (XRF) or an energy dispersive analyzer (EDS) attached to a Scanning Electron Microscope (SEM). Then, each element detected by the qualitative analysis was quantitatively analyzed by an ICP emission spectrometer. Next, the content of each element measured by the quantitative analysis was converted into an oxide.

The ceramic sintered body 3 may contain at least 1 oxide of Hf (hafnium), Si (silicon), Ca (calcium), Na (sodium), K (potassium), Fe (iron), Ti (titanium), and Mn (manganese) in addition to the above-described constituent elements. These oxides may be intentionally added or may be inevitably mixed.

(M phase ratio of ceramic sintered body 3)

The ceramic sintered body 3 contains ZrO₂The crystal phase is taken as a crystal phase. ZrO (ZrO)₂The crystal phases have a monoclinic phase (monoclinic phase) and a tetragonal phase (tetragonal phase) as crystal structures.

In the X-ray diffraction pattern of the ceramic sintered body 3 subjected to the heat aging treatment at 180 ℃ for 100 hours after sintering, the ratio of the peak intensity of the monoclinic phase to the sum of the peak intensities of the monoclinic phase and the tetragonal phase (hereinafter referred to as "M-phase fraction after heat aging") is 15% or less. From this, it is considered that, in the ceramic sintered body 3, the accumulation of defects due to stress deformation accompanying volume expansion caused by the transformation of the tetragonal phase of the zirconia crystal into the monoclinic phase can be suppressed.

The M phase ratio after heat aging is preferably 4% or more. Thus, it is considered that the tetragonal phase of the zirconia crystal at the tip of the crack generated when the mechanical stress is applied to the ceramic sintered body 3 is transformed into the monoclinic phase, and the crack can be suppressed from propagating. As a result, it is considered that this contributes to suppressing the decrease in the mechanical strength of the ceramic sintered body 3 after the thermal aging.

In the X-ray diffraction pattern of the ceramic sintered body 3 that has not been subjected to the heat aging treatment, the ratio of the peak intensity of the monoclinic phase to the sum of the peak intensities of the monoclinic phase and the tetragonal phase (hereinafter, referred to as "M-phase ratio before heat aging") is preferably 7% or less. From this, it is considered that the tetragonal phase of the zirconia crystal is suppressed from being transformed into the monoclinic phase during the heat aging, and the decrease in the mechanical strength of the ceramic sintered body 3 after the heat aging can be further suppressed.

The M-phase ratio before and after thermal aging can be determined from the following formula (1) by using an X-ray diffraction pattern obtained by analyzing the outer surface of the ceramic sintered body 3 with an X-ray diffraction apparatus (XRD: MiniFlexII, manufactured by Nippon chemical Co., Ltd.). In formula (1), M1 is the peak intensity of the monoclinic (111) plane, M2 is the peak intensity of the monoclinic (11-1) plane, T1 is the peak intensity of the tetragonal (111) plane, and T2 is the peak intensity of the cubic (111) plane.

The ratio of monoclinic phase (100 × (M1+ M2)/(T1+ T2+ M1+ M2) · (1)

The M phase ratio after heat aging can be controlled by optimizing the content of the constituent elements of the ceramic sintered body 3 as described above and controlling ZrO contained in the ceramic sintered body 3 after sintering₂The particle characteristics of the crystal particles can be easily adjusted. Specifically, ZrO contained in the ceramic sintered body 3₂The average grain diameter of the crystal particles is more than 0.6 μm and less than 1.5 μm, and ZrO contained in the ceramic sintered body 3₂Coarse ZrO having a particle diameter of 1.8 μm or more in the crystal particles₂The area ratio of the crystal particles is 15% or less. In addition, it relates to ceramicsZrO in the porcelain sintered body 3₂Average particle diameter of crystal particles and coarse ZrO₂The method of controlling the content ratio of crystal particles will be described later.

ZrO₂The average particle size of the crystal particles was calculated as follows. First, the outer surface of the ceramic sintered body 3 was imaged at 6000 times by a scanning electron microscope. Next, 300 ZrO pieces randomly selected from the picked-up image are processed by image processing software₂The average equivalent circle diameter of the crystal particles was calculated as an average particle diameter. The average equivalent circle diameter is an average value of equivalent circle diameters, and the equivalent circle diameter is a diameter of a circle having the same area as the particle.

Coarse ZrO₂The area ratio of the crystal particles was 300 ZrO particles selected for the measurement of the average particle diameter₂Coarse ZrO having an equivalent circle diameter of 1.8 μm or more in crystal particles₂The total area of the crystal particles is divided by 300 ZrO₂The total area of crystal particles.

(spinel phase ratio of ceramic sintered body 3)

The ceramic sintered body 3 may contain MgAl₂O₄The crystal phase is taken as a crystal phase. In this case, MgAl is present in the X-ray diffraction pattern of the ceramic sintered body 3 which has not been subjected to the heat aging treatment₂O₄Peak strength of crystalline phase relative to Al₂O₃The ratio of the peak intensities of the crystal phases (hereinafter referred to as "spinel phase fraction") is preferably 4% or less. This can suppress excessive reaction at the joint interface when joining the copper plates, and can suppress the occurrence of voids at the joint interface. The spinel fraction may be 0%.

The spinel phase ratio is more preferably 0.5% or more and 3.5% or less. This can improve the wettability between the ceramic sintered body 3 and the Cu — O eutectic liquid phase at the time of joining the copper plates, and can further suppress the excessive reaction at the joint interface at the time of joining the copper plates, thereby further suppressing the generation of voids at the joint interface.

The spinel phase fraction can be determined from the X-ray diffraction pattern obtained by analyzing the surface of the ceramic sintered body 3 by XRDThe following equation (2). In the formula (2), A1 represents the peak strength of the (311) plane of the spinel phase, and B1 represents Al₂O₃Peak intensity of (104) plane of crystalline phase.

MgAl₂O₄100 × a1/(a1+ B1) · (2)

(method for producing ceramic sintered body 3)

A method for producing the ceramic sintered body 3 will be described with reference to fig. 2. Fig. 2 is a flowchart illustrating a method of manufacturing the ceramic sintered body 3.

In step S1, the following powder materials are blended.

With ZrO₂ZrO in a conversion of 7.5 to 23.5 mass%₂

With Al₂O₃Al in terms of 74.9 to 91.8 mass%₂O₃

With Y₂O₃Converted into Y of 0.41 to 1.58 mass%₂O₃

MgO in an amount of 0.10 to 0.80 mass% in terms of MgO

In this case, it is preferable to use a specific surface area of 5m²More than 10 m/g²ZrO of/g₂And (3) powder. This makes it easy to suppress the occurrence of cracks due to thermal cycles.

In addition, ZrO₂And Y₂O₃Each may be a separate powder material, but Y may be used in advance₂O₃Partially stabilized ZrO₂And (3) powder. Further, HfO may be blended as desired₂、SiO₂、CaO、Na₂O and K₂O and the like.

In step S2, the mixed powder material is pulverized and mixed by, for example, a ball mill or the like.

In step S3, an organic binder (for example, polyvinyl butyral), a solvent (xylene, toluene, or the like), and a plasticizer (dioctyl phthalate) are added to the pulverized and mixed powder material to form a slurry.

In step S4, the slurry-like substance is molded into a desired shape by a desired molding means (for example, mold pressing, cold isostatic pressing, injection molding, doctor blading, extrusion molding, or the like) to produce a ceramic molded body.

In step S5, the ceramic compact is fired in an oxygen atmosphere or an atmospheric atmosphere (1580 to 1620 ℃, 0.7 to 1.0 hour) to form the ceramic sintered body 3. As described above, the ceramic sintered body 3 is ZrO after sintering₂The average particle diameter of the crystal particles is 0.6-1.5 μm, and coarse ZrO₂Since the area ratio of the crystal particles is 15% or less, the mechanical strength can be prevented from being lowered by the heat aging treatment. Further, as described above, the content of each constituent element in the ceramic sintered body 3 was optimized, and a specific surface area of 5m was used²More than 10 m/g²ZrO of/g₂Since the powder is produced, the occurrence of cracks due to thermal cycling can be suppressed.

In addition, ZrO in the ceramic sintered body 3₂Average particle diameter of crystal particles and coarse ZrO₂The content ratio of the crystal particles can be adjusted to some extent by controlling the blending composition of the powder material (step S1), the pulverizing and mixing time (step S2), and the firing temperature (step S5). If the pulverization mixing time is prolonged, ZrO₂The average particle diameter of the crystal particles tends to be small and coarse ZrO₂The content ratio of the crystal particles also tends to be small. When the firing temperature is increased, ZrO₂The average particle diameter of the crystal particles tends to be large and coarse ZrO₂The content ratio of crystal particles tends to increase.

(characteristics)

In the ceramic sintered body 3, the Zr content is ZrO₂Converted to 7.5-23.5 mass%, and Al content is calculated as Al₂O₃Converted into 74.9-91.8 mass%, and the content of Y is Y₂O₃0.41 to 1.58 mass% in terms of MgO, and 0.10 to 0.80 mass% in terms of Mg. Further, the M-phase ratio after heat aging is 15% or less.

By optimizing the content of the constituent elements of the ceramic sintered body 3 and setting the M-phase ratio after heat aging to 15% or less in this manner, the mechanical strength (the breaking strength measured by the 3-point bending strength test) can be maintained after the heat aging treatment, and the occurrence of cracks due to heat cycles can be suppressed.

Examples

The ceramic sintered bodies 3 according to examples 1 to 9 and comparative examples 1 to 8 were produced as described below, and the M-phase ratio before and after thermal aging and the flexural strength (mechanical strength) before and after thermal aging were measured. Further, a substrate sample 10 for a semiconductor device shown in fig. 3 was produced using the ceramic sintered bodies 3 according to examples 1 to 9 and comparative examples 1 to 8, and the number of thermal cycles for generating cracks in the ceramic sintered body 3 was measured.

(preparation of ceramic sintered body 3)

First, materials having compositions shown in table 1 were pulverized and mixed by a ball mill. In examples 1 to 9 and comparative examples 1 to 6, the specific surface area was 5m²More than 10 m/g²ZrO of/g or less₂The powder used in comparative examples 7 and 8 had a specific surface area of 13m²19m or more per g²ZrO of/g or less₂And (3) powder.

Then, polyvinyl butyral as an organic binder, xylene as a solvent, and dioctyl phthalate as a plasticizer were added to the pulverized and mixed powder material to form a slurry.

Next, the slurry-like substance was molded into a sheet-like shape by a doctor blade method to prepare a ceramic molded body.

Next, the ceramic compact was fired in an oxygen atmosphere or an air atmosphere at the firing temperature shown in table 1 for 0.8 hours to produce a ceramic sintered body 3. The dimensions of the ceramic sintered body 3 were 0.32mm in thickness, 39mm in length and 45mm in width.

(M phase fraction)

The M phase ratio before heat aging was calculated from the above formula (1) by using an X-ray diffraction pattern obtained by analyzing the outer surface of each sintered ceramic body 3 after sintering by XRD (miniflexiii, manufactured by japan chemical company). The calculated M phase ratio before heat aging is shown in Table 1.

Next, each of the sintered ceramic bodies 3 was subjected to a heat aging treatment at 180 ℃ for 100 hours.

Next, the M-phase ratio after heat aging was calculated from the above formula (1) by using an X-ray diffraction pattern obtained by analyzing the outer surface of each ceramic sintered body 3 after heat aging by XRD (miniflexiii, manufactured by japan chemical company). The calculated M phase ratio after heat aging is summarized in table 1.

(spinel phase fraction)

MgAl was calculated from the above formula (2) by analyzing the outer surface of each sintered ceramic body 3 after sintering by XRD (MiniFlexi II, manufactured by Nippon chemical Co., Ltd.)₂O₄Peak strength of crystalline phase relative to Al₂O₃Peak strength ratio of crystal phase (spinel fraction before heat aging). The spinel phase ratios before heat aging are summarized in table 1.

(flexural Strength)

The flexural strength (mechanical strength) of each 10 pieces was measured by a 3-point bending strength test of a sample size (15 × 45 × 0.32mm in thickness) and a span of 30mm for each sintered ceramic body 3 after sintering, and the arithmetic average of the measured values of the 10 pieces (flexural strength before heat aging) was calculated. The flexural strength before heat aging is summarized in Table 1.

Next, each of the sintered ceramic bodies 3 was subjected to a heat aging treatment at 180 ℃ for 100 hours.

Next, the flexural strength (mechanical strength) of each 10 pieces was measured by a 3-point bending strength test of a sample size (15 × 45 × 0.32mm in thickness) and a span of 30mm for each ceramic sintered body 3 after heat aging, and an arithmetic average of the measured values of the 10 pieces (flexural strength after heat aging) was calculated. The flexural strength after heat aging is summarized in table 1.

(preparation of substrate sample for semiconductor device 10)

The outer surfaces of the 1 st and 2 nd copper plates 4 and 4 'are oxidized by heating the 1 st and 2 nd copper plates 4 and 4' (each having a thickness of 0.40 mm) made of oxygen-free copper conforming to JIS C1020 to 300 ℃ in the atmosphere.

Next, the laminate in which the ceramic sintered bodies 3 according to examples 1 to 9 and comparative examples 1 to 8 were sandwiched between the 1 st and 2 nd copper plates 4 and 4' was placed on the mesh material 11 made of Mo (molybdenum), and nitrogen (N) was added thereto₂) Heated in an atmosphere at 1070 c for 10 minutes.

Next, the 1 st and 2 nd copper plates 4 and 4 'are bonded to the ceramic sintered body 3, and the mesh material 11 is bonded to the 2 nd copper plate 4' by cooling the laminate.

(crack Generation Rate)

For each semiconductor device substrate sample 10, at N₂(Nitrogen) and H₂(Hydrogen) Mixed gas (N)₂：H₂7: 3) until cracks were generated in the ceramic sintered body 3, the thermal cycle of "room temperature → 310 ℃ C.. times.5 minutes" was repeated in the atmosphere of (1).

In table 1, the number of thermal cycles in which cracks were generated in any of the 10 pieces of the ceramic sintered body 3 is described as the number of thermal cycles in which cracks were generated. In table 1, a sample having a crack generation heat cycle number of 20 or more was evaluated as "excellent", a sample having a crack generation heat cycle number of 7 or more and 19 or less was evaluated as "o", and a sample having a crack generation heat cycle number of 6 or less was evaluated as "x".

[ Table 1]

As shown in Table 1, the specific surface area of the resin composition was 5m²More than 10 m/g²ZrO of/g or less₂The content of the constituent elements in the ceramic sintered body 3 of the powder was optimized as follows, and in examples 1 to 9 in which the M-phase ratio was 15% or less after the heat aging treatment, the mechanical strength maintenance after the heat aging treatment and the crack suppression due to the heat cycle were compatible. Specifically, in examples 1 to 9, the flexural strength after heat aging was 500MPa or more, and the number of thermal cycles for crack generation was 7 or more.

With ZrO₂Converted into not less than 7.5% by mass and 23.5% by mass or less of ZrO₂

With Al₂O₃Al in terms of 74.9 to 91.8 mass%₂O₃

With Y₂O₃Converted into Y of 0.41 to 1.58 mass%₂O₃

MgO in an amount of 0.10 to 0.80 mass% in terms of MgO

On the other hand, in comparative examples 1 to 6, the content of the constituent elements was not optimized, and in comparative examples 7 and 8, the M-phase ratio after heat aging exceeded 15%, and therefore, both the maintenance of mechanical strength and the suppression of cracks were not achieved.

Industrial applicability

According to the present invention, a decrease in mechanical strength and the occurrence of cracks in the ceramic sintered body can be suppressed, and therefore the ceramic sintered body according to the present invention can be used for a substrate for a semiconductor device used in various electronic devices.

Description of the symbols

1 … semiconductor device

2 … substrate for semiconductor device

3 … ceramic sintered body

4. 4' … copper plate

5. 5' … bonding material

6 … semiconductor chip

7 … bonding wire

8 … radiator

10 … substrate sample for semiconductor device

11 … a web material.