JP3982111B2 - Semiconductor device member using ceramic and method for manufacturing the same - Google Patents

Description

（注）表中の＊を付した試料は比較例である。
【００３６】
試料１と試料２の結果を比較すると、高融点金属層を介してＡｌＮ基材とＡｌ導体層を接合した本発明の試料１の方が、高融点金属層の応力緩和効果によって基板にかかる応力が小さくなり、ヒートサイクル試験による熱衝撃に耐え、良品率が大幅に高くなることが分かる。
【００３７】
尚、上記コファイアメタライズ法によるメタライズ基板に代えて、上記のポストメタライズ法で得たメタライズ基板を用い、上記試料１と同一条件で半導体装置を作製したところ、試料１とほぼ同様の接合率並びにヒートサイクル特性が得られた。この結果から、高融点金属層の形成方法が異なっても、ほぼ同様の効果が得られることが分かる。
【００３８】
また、上記高融点金属層をＷからＴａ、Ｍｏ又はＭｎに代え、あるいはセラミック基材をＡｌＮ系からＡｌ₂Ｏ₃系又はＳｉ₃Ｎ₄系に代えて、上記と同一条件で半導体装置を作製したが、いずれも試料１とほぼ同様の接合率並びにヒートサイクル特性が得られた。この結果から、セラミック基材及び高融点金属層の材質が異なっても、ほぼ同様の効果が得られることが分かる。
【００３９】
実施例２
上記実施例１と同様にして、同じ形状で高融点金属層を形成していないＡｌＮ焼結体を製造した。このＡｌＮ焼結体を大気雰囲気中にて１２００℃で加熱処理することにより、その表面に厚み０.２〜２０μｍの表面酸化層を形成した。このＡｌＮ基材上に、長さ及び幅ともに基材と同じで厚みが０.０４ｍｍのＡｌ−Ｓｉロウ材を載せ、更にその上に導体層として長さ及び幅ともに基材と同じで厚みが０.３ｍｍのＪＩＳ １０８０のアルミニウム素材を載せ、これを黒鉛製のセッター上に並べ、６００℃の窒素気流中において３０分間の無負荷での炉中接合を行って、Ａｌ−ＡｌＮ接合基板（試料３）を得た。
【００４０】
上記と同じく高融点金属層を形成せず且つ表面酸化層を形成したＡｌＮ基材上に、厚み２μｍのＮｉ層をメッキにより形成し、その上に長さ及び幅ともに基板と同じで厚みが０.０４ｍｍのＡｌ−Ｓｉロウ材を載せ、更にその上に長さ及び幅ともに基板と同じで厚みが０.３ｍｍのＪＩＳ １０８０のアルミニウム素材を載せて、上記と同様に６００℃の窒素気流中において３０分間の無負荷での炉中接合を行い、Ａｌ−ＡｌＮ接合基板（試料４）を得た。
【００４１】
次に、上記実施例１と同様にコファイアメタライズ法により、上記と同じ形状でＷ高融点金属層を有するＡｌＮメタライズ基板を作製した。この基板のＷ高融点金属層上に長さ及び幅ともに基板と同じで厚みが０.０４ｍｍのＡｌ−Ｓｉロウ材を載せ、更にその上に長さ及び幅ともに基板と同じで厚みが０.３ｍｍのＪＩＳ １０８０のアルミニウム素材を載せて、上記と同様に６００℃の窒素気流中において３０分間の無負荷での炉中接合を行い、Ａｌ−ＡｌＮ接合基板（試料５）を得た。
【００４２】
また、同じくコファイアメタライズ法で得たＷ高融点金属層を有するＡｌＮメタライズ基板を準備し、この基板のＷ高融点金属層上に厚み２μｍのＮｉ層をメッキにより形成した後、その上に長さ及び幅ともに基板と同じで厚みが０.０４ｍｍのＡｌ−Ｓｉロウ材を載せ、更にその上に長さ及び幅ともに基板と同じで厚みが０.３ｍｍのＪＩＳ １０８０のアルミニウム素材を載せて、上記と同様に６００℃の窒素気流中において３０分間の無負荷での炉中接合を行い、Ａｌ−ＡｌＮ接合基板（試料６）を得た。
【００４３】
上記と同じくコファイアメタライズ法で得たＷ高融点金属層を有するＡｌＮメタライズ基板を準備し、この基板のＷ高融点金属層上に厚み２μｍのＮｉ層をメッキにより形成した。更に、この基板上のＮｉ層の中央に、長さ及び幅ともに基板より０.６ｍｍ小さく、厚みが０.０４ｍｍのＡｌ−Ｓｉロウ材を載せ、その上の中央に長さ及び幅ともに基板より０.６ｍｍ小さく、厚みが０.３ｍｍのＪＩＳ１０８０のアルミニウム素材を載せて、上記と同様に６００℃の窒素気流中において３０分間の無負荷での炉中接合を行い、Ａｌ−ＡｌＮ接合基板（試料７）を得た。
【００４４】
更に、上記と同じくコファイアメタライズ法で得たＷ高融点金属層を有するＡｌＮメタライズ基板を準備し、この基板のＷ高融点金属層上に厚み２μｍのＮｉ層をメッキにより形成した。一方、この基板より長さ及び幅ともに０.６ｍｍ小さく、厚みが０.３ｍｍのＪＩＳ １０８０のアルミニウム素材を準備し、その接合面にＳｉのイオン注入により厚み２μｍのＳｉリッチ層を形成した。次に、上記ＡｌＮメタライズ基板のＮｉ層とアルミニウム素材のＳｉリッチ層とを中央位置合わせで密着させ、上記と同様に６００℃の窒素気流中において３０分間の無負荷での炉中接合を行って、Ａｌ−ＡｌＮ接合基板（試料８）を得た。
【００４５】
上記のごとく作製した各試料３〜８について、超音波探傷面分析をした結果、異常な欠陥は認められなかった。また、接合後の試料断面を１０００倍のＳＥＭ（走査型電気顕微鏡）で観察をしたところ、各試料の界面にクラック、ピンホール等は見られなかった。尚、各試料について実施例１と同様に接合率を求め、下記表２に示した。
【００４６】
また、上記各試料３〜８の部材を、実施例１と同様に、共晶半田を用いてＣｕ−Ｗ合金製の放熱板に接合し、半導体装置をそれぞれ１００個ずつ製造した。これらの各半導体装置を、−５０℃×１５分→＋１４０℃×１５分の条件で１０００サイクルのヒートサイクル試験にかけた後、超音波探傷面分析による欠陥部の評価を行うと共に２０倍の実体顕微鏡で各接合端面部の欠陥の有無を調査して、半導体装置１００個に対するヒートサイクル試験後の良品率を求め、その結果を下記表２に示した。
【００４７】
【表２】

（注）表中の＊を付した試料は比較例である。
【００４８】
上記表２から、応力緩和層としてＷ高融点金属層を備えた本発明の試料５〜８は、Ｗ高融点金属層を有しない比較例の試料３〜４に比べ、セラミック基板にかかる応力が小さくなるため、ヒートサイクル試験による熱衝撃に耐え、最終的な良品率が大幅に高くなることが分かる。また、試料３と試料４、試料５と試料６を比較すると、Ｎｉ層を介在させた方がＷ高融点金属層とＡｉ−Ｓｉロウ材との濡れ性がよく、接合率が高くなることが分かる。
【００４９】
更に、試料６と試料７を比較したとき、基材と同じ大きさのＡｌ導体層を接合するよりも、基板よりも小さいＡｌ導体層を接合した場合の方が、接合時の応力を緩和でき、ヒートサイクル試験による熱衝撃に耐え、良品率が高くなることが分かる。また、試料７と試料８の比較から、Ｗ高融点金属層の上にＡｌ−Ｓｉ等の金属介在層が存在しない方が、応力緩和効果がより大きいことが分かる。
【００５０】
尚、上記コファイアメタライズ法によるメタライズ基板に代えて、上記のポストメタライズ法で得たメタライズ基板を用い、上記本発明の試料５〜８と同一条件で半導体装置を作製したところ、それぞれほぼ同様の接合率並びにヒートサイクル特性が得られた。この結果から、高融点金属層の形成方法が異なっても、ほぼ同様の効果が得られることが分かる。
【００５１】
また、上記高融点金属層をＷからＴａ、Ｍｏ又はＭｎに代え、あるいはセラミック基材をＡｌＮ系からＡｌ₂Ｏ₃系又はＳｉ₃Ｎ₄系に代えて、上記本発明の試料５〜８と同一条件でそれぞれ半導体装置を作製したが、いずれもほぼ同様の接合率並びにヒートサイクル特性が得られた。この結果から、セラミック基材及び高融点金属層の材質が異なっても、ほぼ同様の効果が得られることが分かる。
【００５２】
更に、上記金属介在層としてのＡｌ−Ｓｉロウ材を、Ｚｎ−Ａｌ合金半田材、Ｚｎ−Ｓｎ合金半田材、及びＰｂ−Ｓｎ合金半田材に置き換えて、上記本発明の試料５〜７と同一条件でそれぞれ半導体装置を作製したが、いずれもほぼ同様の接合率並びにヒートサイクル特性が得られた。この結果から、金属介在層の材質が異なっても、ほぼ同様の効果が得られることが分かる。
【００５３】
【発明の効果】
本発明によれば、アルミニウムからなるリードフレームのような金属部材をセラミック基材に実装する際に、高融点金属層の応力緩和作用によりセラミック基材の破損変形をなくし、しかも高い接合強度で接合でき、過酷な熱サイクルにおいても高い信頼性を有する半導体装置用部材を提供することができる。
【図面の簡単な説明】
【図１】本発明の半導体装置用部材の一具体例を示す概略の断面図である。
【図２】本発明の半導体装置用部材における剥離強度の測定方法を説明するための概略の断面図である。
【図３】本発明の半導体装置用部材を用いた半導体装置の一具体例を示す概略の断面図である。
【符号の説明】
１ セラミック基材 ２ 高融点金属層 ３ 導体層
４ 金属介在層 ５ 共晶半田 ６ 放熱板[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a member for a semiconductor device for mounting a semiconductor element, in which a conductor layer mainly composed of aluminum is provided on a ceramic substrate.
[0002]
[Prior art]
Conventionally, as a method of bonding a conductor circuit formed of aluminum to a ceramic substrate, a method of directly bonding the ceramic substrate and the conductor circuit is known. As this direct bonding method, for example, a ceramic base material is directly contacted with an aluminum melt, and the contact portion is successively made below the solidification temperature of aluminum to form an aluminum conductor circuit, Al-Si brazing material or Al-Ge. There are a method of bonding the two using a brazing material, a method of bonding an aluminum plate to the vicinity of the melting point, and then applying pressure to the ceramic substrate.
[0003]
However, with the direct bonding method described above, the conductor circuit can be bonded to the ceramic substrate, but the thermal expansion coefficient of the ceramic substrate and the aluminum conductor circuit are different, so that the substrate is warped or cracked due to thermal cycling. There was a problem to do. In particular, if an attempt was made to increase the cross-sectional area of the conductor circuit in order to increase the current density, the thermal stress generated in the conductor circuit exceeded the strength of the ceramic substrate, and the ceramic substrate could be damaged. Increasing the thickness of the ceramic substrate in order to eliminate this causes an increase in weight and an increase in shape, and a heat dissipation characteristic decreases due to an increase in thermal resistance.
[0004]
[Problems to be solved by the invention]
As a method for solving the above problem, Japanese Patent Laid-Open No. 9-36277 discloses a porous sintered body of Cu, Al or Ag having a porosity of 20 to 50% between a ceramic substrate and a metal conductor circuit. There has been proposed a method in which a plastic porous metal layer is provided and thermal deformation is absorbed by the plastic porous metal layer and bonded.
[0005]
However, the bonding between the plastic porous metal layer and the ceramic substrate, like the direct bonding method, because the thermal expansion coefficient of the ceramic substrate and the plastic porous metal layer is different, warping the ceramic substrate, There are disadvantages such as cracking in the ceramic substrate due to thermal cycles during mounting and use.
[0006]
In view of such conventional circumstances, the present invention eliminates damage and deformation of the ceramic base material when joining the ceramic base material and the aluminum conductor circuit, and both are joined with high joint strength, even in severe thermal cycles. Provided is a semiconductor device member having high reliability.
[0007]
[Means for Solving the Problems]
  In order to achieve the above object, a member for a semiconductor device provided by the present invention includes a ceramic base material and a refractory metal layer mainly composed of a refractory metal provided on the ceramic base material.A metal intervening layer made of at least one selected from an Al-Si alloy, a Zn-Al alloy, and a Zn-Sn alloy provided on the refractory metal layer, and the metal intervening layer is made of aluminum. And the length and width in the planar direction at the bonding interface of the conductor layer are less than that of the refractory metal layer. . 05mm or shorterIt is characterized by this.
[0008]
  Moreover, the member for semiconductor devices of this inventionInThe length and width in the plane direction at the bonding interface of the conductor layer mainly composed of aluminum is 0.05 mm or more shorter than that of the refractory metal layer.Is necessary,In this case, it is more preferable that these dimensions of the conductor layer are the same as those of the metal intervening layer.
[0009]
  One of the methods for producing a member for a semiconductor device of the present invention is a step of applying a paste containing a refractory metal on a ceramic substrate made of a sintered body and firing to form a refractory metal layer;Forming a metal intervening layer made of at least one selected from an Al—Si based alloy, a Zn—Al based alloy, and a Zn—Sn based alloy on the refractory metal layer; and aluminum on the metal intervening layer. A step of bonding a main conductor layer, and a length and a width in a plane direction at a bonding interface of the conductor layer are set to be less than that of the refractory metal layer. . 05mm or shorterIt is characterized by that.
[0010]
  Another method for manufacturing a member for a semiconductor device according to the present invention is to apply a paste containing a refractory metal on a ceramic base material powder compact and fire it to obtain a ceramic base from the compact. And simultaneously forming a refractory metal layer thereon,Forming a metal intervening layer made of at least one selected from an Al—Si based alloy, a Zn—Al based alloy, and a Zn—Sn based alloy on the refractory metal layer; and aluminum on the metal intervening layer. A step of bonding a main conductor layer, and a length and a width in a plane direction at a bonding interface of the conductor layer are set to be less than that of the refractory metal layer. . 05mm or shorterIt is characterized by that.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, as shown in FIG. 1, a refractory metal layer 2 is formed on a ceramic substrate 1, and a conductor layer 3 mainly composed of aluminum is formed on the ceramic substrate 1 via the refractory metal layer 2. Join. The refractory metal layer 2 relieves thermal stress due to a difference in thermal expansion coefficient between the ceramic substrate 1 and the conductor layer 3, and prevents cracking and deformation of the ceramic substrate 1 due to a thermal cycle during bonding or use.
[0012]
The ceramic substrate used in the present invention is made of aluminum nitride (AlN), silicon nitride (Si_ThreeN_Four) System, alumina (Al₂O_Three) Series ceramics. These ceramics are used as sintering aids, for example Y₂O_ThreeIt is possible to add a rare earth element compound such as CaO, an alkaline earth element compound such as CaO, or the like, and, if necessary, another transition element compound such as TiN. These ceramics have a relative density of 95% or more, preferably 98% or more. When the relative density is less than 95%, the strength of the substrate is lowered, and when used as a product, the reliability against thermal shock may be lowered. Note that a thin layer containing oxygen may be formed in advance on the surface of the ceramic base material where the refractory metal layer is formed, and further, Al, Si, rare earth elements, alkaline earth elements, etc. may be included in the surface portion. it can.
[0013]
The main component of the refractory metal layer is a refractory metal such as W, Mo, Ta, or Mn. This refractory metal layer is a glass frit containing rare earth elements, alkaline earth elements, Si, Al and other transition elements usually added to the sintered body in order to improve the bondability with the ceramic substrate. May be included. The composition of the refractory metal layer after baking is preferably 80% by volume or more of the refractory metal and 20% by volume or less of the glass frit described above. This is because if the refractory metal is less than 80% by volume or the glass frit exceeds 20% by volume, the thermal conductivity of the refractory metal layer is likely to decrease. Further, if the thickness of the refractory metal layer after baking is less than 3 μm, sufficient bonding strength cannot be obtained between the refractory metal layer and the ceramic substrate, and if it exceeds 50 μm, warping after the formation of the refractory metal layer is achieved. Since the amount tends to increase, the range of 3 to 50 μm is preferable.
[0014]
As the conductor layer mainly composed of aluminum joined to the ceramic substrate through the refractory metal layer, it is preferable to use aluminum having a purity exceeding 99.9%, for example, an aluminum material of JIS 1080. This is because, when the purity is lowered, the electrical conductivity is lowered, so that the temperature may be increased during energization.
[0015]
A metal intervening layer may be provided on the refractory metal layer, and the conductor layer may be joined via the metal intervening layer. The metal intervening layer has a lower melting point than the conductor layer mainly composed of aluminum, for example, a brazing material made of an Al—Si based alloy having a relatively high melting point, a Zn—Al based, a Zn—Sn based, and a Pb having a lower melting point. It is preferable to be made of a material having a melting point of 660 ° C. or lower, which is mainly composed of at least one eutectic solder material made of an Sn-based alloy. This is to maintain the shape of the circuit pattern of the conductor layer mainly composed of aluminum. Moreover, you may laminate | stack two or more metal intervening layers. The thickness of the metal intervening layer is preferably in the range of 2 to 200 μm, more preferably 5 to 50 μm. If the thickness of the metal intervening layer is less than 2 μm, a sufficient liquid phase cannot be obtained at the time of joining, thereby increasing the thermal resistance or concentrating the stress due to the thermal shrinkage difference between the conductor layer and the ceramic substrate. This is because breakage and deformation are likely to occur, and conversely, if the thickness exceeds 200 μm, the thermal resistance increases.
[0016]
Further, a nickel layer can be formed on the refractory metal layer, and the metal intervening layer can be disposed on the nickel layer. By joining the ceramic substrate and the conductor layer via the nickel layer and the metal intervening layer on the refractory metal layer, the wettability at the time of joining is improved, and the joining rate can be increased.
[0017]
Furthermore, in the present invention, the length and width of the conductor layer mainly composed of aluminum is made 0.05 mm or more shorter than that of the refractory metal layer, so that the outer peripheral edge of the conductor layer is the outer peripheral edge of the refractory metal layer. Thermal stress applied from the outer peripheral end of the conductor layer to the outer peripheral end of the refractory metal layer can be dispersed inside the edge, and the ceramic substrate can be prevented from cracking at this portion. Similarly, in the relationship between the conductor layer and the metal intervening layer, it is preferable that the length and width of the conductor layer are the same as those of the metal intervening layer or are shortened by 0.05 mm or more.
[0018]
Next, the manufacturing method of the member for semiconductor devices of this invention is demonstrated. First, a refractory metal layer is formed on the surface of the ceramic substrate. One of the methods is a so-called post-fire metallization method in which a sintered body to be a ceramic substrate is prepared in advance, and a refractory metal paste is baked on the ceramic substrate to form a refractory metal layer. Another method is a so-called cofire metallization method in which a high-melting point metal paste is applied onto a ceramic raw material powder compact and fired to obtain a ceramic substrate and at the same time a high-melting point metal layer is formed.
[0019]
Specifically, in the post-fire metallization method, the surface of the ceramic substrate is subjected to surface treatment such as formation of the above-described oxygen-containing thin layer as necessary, and then a refractory metal paste is preferably printed to a thickness of 5 to 60 μm. Apply it. The refractory metal paste is prepared by mixing an organic binder and an organic solvent (for adjusting the binder viscosity) by adding a glass frit or the like to the metal alone or a mixture thereof containing a refractory metal as a main component. Thereafter, the refractory metal paste is baked to form a refractory metal layer on the ceramic substrate.
[0020]
On the other hand, in the cofire metallization method, an organic binder is added to a ceramic raw material powder blended in a predetermined composition, and a refractory metal paste is applied to a molded body obtained by molding the ceramic binder by the same procedure as described above. Thereafter, the compact is sintered to obtain a ceramic base material, and at the same time, a refractory metal layer is formed on the ceramic base material. In the case of this cofire metallization method, the refractory metal particles in the paste should be as fine as possible, and the additive for promoting the sintering of the ceramic can be selected by selecting one that can form a liquid phase at a low temperature. It is important to devise so that the sintering can be performed simultaneously at a low temperature and the shrinkage ratios of the both are approximately the same, thereby preventing deformation of the base material during sintering. In addition, by sintering at a low temperature, the crystal particles of the ceramic substrate become finer, and the strength of the substrate is expected to increase.
[0021]
On the refractory metal layer thus formed, the metal intervening layer and / or the nickel layer may be formed or both may be formed before joining the conductor layer. As a method for forming the metal intervening layer, a plating method or a method using a brazing foil is preferable, but other methods such as a printing method and a vapor deposition method can also be adopted. The Ni layer can also be formed by a plating method, a printing method, a vapor deposition method, or the like. The metal intervening layer and the Ni layer thus formed are preferably fired in a non-oxidizing atmosphere before joining the conductor layers.
[0022]
A refractory metal layer is formed as described above, and a conductor layer mainly composed of aluminum is bonded onto the ceramic substrate on which a nickel layer and / or a metal intervening layer is further formed as necessary. In the case of joining conductor layers mainly composed of aluminum, in general, a material mainly composed of aluminum is brought into close contact with a refractory metal layer, nickel layer or metal intervening layer of a ceramic substrate, and in a non-oxidizing atmosphere or in a vacuum. And bonding by firing at a temperature lower than the melting point of the conductor layer material. In addition, when joining a conductor layer on a refractory metal layer, after making molten aluminum contact a refractory metal layer, it may cool and it may be made to solidify sequentially.
[0023]
In addition, when joining the conductor layer material to the above ceramic substrate, if necessary, for example, using a jig made of a refractory material such as carbonaceous, alumina, aluminum nitride, and the like, Further, if necessary, an appropriate load may be applied to the set in which both are laminated.
[0024]
As described above, the semiconductor device member of the present invention in which an aluminum conductor layer is bonded to a ceramic substrate via a refractory metal layer or a nickel layer or a metal intervening layer thereon is mainly composed of aluminum at the time of bonding. In addition to the low and low melting point of the conductor layer, the stress relieving effect of the refractory metal layer makes it possible to obtain a stable bond without breakage or deformation of the ceramic substrate. In addition, the bonding strength of the bonding portion is 0.5 kg / mm or more in terms of peel strength, which is a high level that does not cause practical problems, and is stable with little variation in bonding strength.
[0025]
For example, as shown in FIG. 2, this peel strength is measured by a thickness of 0.1 mm through a refractory metal layer 2 provided on a ceramic substrate 1 and a metal intervening layer 4 provided as necessary. The conductor layer 3 having a width of 4.0 mm is joined so as to have a length L = 3 mm, and the conductor layer 3 is included by pulling upward the grip portion 3 a that protrudes perpendicularly upward from one end of the conductor layer 3. The tensile load at which a part of the joining layer or the joining interface begins to peel off is obtained, and the value obtained by converting the tensile load per 1 mm of the length L is defined as the peel strength value.
[0026]
【Example】
Example 1
AlN powder with an average particle size of 1.2 μm as the main component ceramic powder, Si_ThreeN_FourPowder or Al₂O_Three97% by weight of the powder and Y having an average particle size of 0.6 μm as a sintering aid₂O_ThreeThe powder and CaO powder with an average particle size of 0.3 μm were both weighed to 1.5% by weight and mixed uniformly in a ball mill in an ethanol solvent for 24 hours.₂O_Three-AlO based on CaO, Si_ThreeN_FourSystem and Al₂O_ThreeThree raw material mixed powders of the system were obtained. Furthermore, 10 parts by weight of PVB as an organic binder was added to 100 parts by weight of these raw material mixed powders and kneaded to obtain a slurry. This slurry was spray-dried, and the obtained powder was press-molded to obtain a molded body.
[0027]
About half of the obtained molded bodies, AlN and Si_ThreeN_FourEach molded body mainly composed of Al is 5 hours at 1700 ° C. in a nitrogen atmosphere, and Al.₂O_ThreeThe green compacts were sintered at 1600 ° C. for 5 hours in air. The relative density of each of the sintered bodies thus obtained (the ratio of the measured density when measured by the underwater method when the theoretical density is 100%) is 99%, and there is a practical problem on the surface. There were no defects such as vacancies. The thermal conductivity measured by the laser flash method is 150 to 160 W / m · K for the AlN sintered body, Si._ThreeN_FourSintered body is 50-60W / m · K, and Al₂O_ThreeThe sintered body was 30 to 40 W / m · K.
[0028]
A high melting point metal paste is applied to one main surface of each sintered body by screen printing, debindered in a nitrogen atmosphere, and then fired at 1650 ° C. for 1 hour in a nitrogen atmosphere furnace. A metal layer was formed (post-fire metallization method). The high melting point metal paste used was 80% by weight of W powder with an average particle size of 1 μm, 10% by weight of organic solvent with a ball mill, SiO 2₂-CaO-B₂O_ThreeIt was prepared by mixing with 5% by weight of a glass base and 5% by weight of an organic binder.
[0029]
For the remaining half of the molded body, the same refractory metal paste as described above was applied on one main surface by screen printing, debindered at 600 ° C. in a nitrogen atmosphere, and then 1700 in a nitrogen atmosphere. By baking at 5 ° C. for 5 hours, the molded body was sintered and the paste was baked at the same time to form a refractory metal layer on the ceramic substrate (cofire metallization method).
[0030]
Each metallized substrate having a W refractory metal layer formed on a ceramic substrate by the above two methods has a width of 50 mm, a length of 50 mm, and a thickness of 0.8 mm, and the W refractory metal layer has a thickness of 20 mm. It was in the range of ± 10 μm.
[0031]
After using the AlN-based metallized substrate obtained by the cofire metallization method, the W refractory metal layer was brought into contact with 99.9% purity aluminum melted in a 660 ° C. crucible, and then the refractory metal layer By sequentially solidifying the aluminum bonded on top, an aluminum conductor layer having a thickness of 0.3 mm was formed on the entire main surface to obtain an Al—AlN bonded substrate (Sample 1).
[0032]
For comparison, an AlN substrate having no W refractory metal layer obtained by the post-fire metallization method was used, and this substrate was brought into contact with 99.9% purity aluminum melted in a 660 ° C. crucible. Thereafter, the aluminum bonded on the substrate was sequentially solidified to form an aluminum conductor layer having a thickness of 0.3 mm on the entire main surface to obtain an Al—AlN bonded substrate (sample 2).
[0033]
As a result of ultrasonic flaw detection surface analysis of the sample 1 and the sample 2 after joining, no abnormal defect was found. Moreover, when the cross-section of the sample after bonding was observed with a 1000 times SEM (scanning electron microscope), no cracks, pinballs, or the like were found at the interfaces of all the samples. Table 1 below shows the bonding rate of the obtained samples. The joining rate is defined as follows. A region where the average reflection intensity when the actual bonding interface of each sample is measured is larger than 2a with respect to the ultrasonic average reflection intensity a of the minimum measurement area when an ultrasonic flaw detection surface analysis is performed on the center of a sample having no defect Is the number of unjoined parts. Further, the number of measurement parts is obtained by dividing the total measurement area of the sample by the minimum measurement area. At this time, 100 times the value calculated by 1- (number of unjoined parts / number of measured parts) is defined as the joining rate (%).
[0034]
As shown in FIG. 3, the members of Sample 1 and Sample 2 produced as described above are bonded onto a heat sink 6 made of Cu—W alloy using eutectic solder 5, and a semiconductor device is mounted for each sample. 100 pieces of each were produced. Each of these semiconductor devices is subjected to a heat cycle test of 1000 cycles under the condition of −50 ° C. × 15 minutes → + 140 ° C. × 15 minutes, and a defect portion is evaluated by ultrasonic flaw detection surface analysis, and each bonding is performed with a 20 × stereo microscope. The presence / absence of defects in the end face portion was investigated, and the yield rate after the heat cycle test for 100 manufactured semiconductor devices was shown in Table 1 below.
[0035]
[Table 1]

(Note) Samples marked with * in the table are comparative examples.
[0036]
Comparing the results of sample 1 and sample 2, the stress applied to the substrate by the stress relaxation effect of the refractory metal layer is greater in the sample 1 of the present invention in which the AlN substrate and the Al conductor layer are joined via the refractory metal layer. It can be seen that the product has a smaller size, can withstand the thermal shock of the heat cycle test, and the yield rate is significantly increased.
[0037]
When a semiconductor device was fabricated under the same conditions as the sample 1 using the metallized substrate obtained by the post metallization method instead of the metallized substrate by the cofire metallization method, the bonding rate and the same as the sample 1 were obtained. Heat cycle characteristics were obtained. From this result, it is understood that substantially the same effect can be obtained even if the method of forming the refractory metal layer is different.
[0038]
Further, the refractory metal layer is changed from W to Ta, Mo or Mn, or the ceramic substrate is changed from AlN to Al.₂O_ThreeSystem or Si_ThreeN_FourInstead of the system, a semiconductor device was manufactured under the same conditions as described above, but in both cases, substantially the same joining rate and heat cycle characteristics as those of Sample 1 were obtained. From this result, it can be seen that the same effect can be obtained even if the materials of the ceramic substrate and the refractory metal layer are different.
[0039]
Example 2
In the same manner as in Example 1, an AlN sintered body having the same shape and no refractory metal layer was produced. The AlN sintered body was heat-treated at 1200 ° C. in an air atmosphere to form a surface oxide layer having a thickness of 0.2 to 20 μm on the surface. On this AlN base material, an Al—Si brazing material having the same length and width as the base material and a thickness of 0.04 mm is placed, and a conductor layer having the same length and width as the base material is further formed thereon. An aluminum material of 0.3 mm JIS 1080 was placed, placed on a graphite setter, and bonded in a furnace for 30 minutes in a nitrogen stream at 600 ° C. with no load, and an Al—AlN bonded substrate (sample) 3) was obtained.
[0040]
A Ni layer having a thickness of 2 μm is formed by plating on an AlN substrate on which a refractory metal layer is not formed and a surface oxide layer is formed as described above, and the length and width are the same as the substrate and the thickness is 0. A .04 mm Al-Si brazing material is placed thereon, and a JIS 1080 aluminum material having the same length and width as the substrate and a thickness of 0.3 mm is placed thereon, and in a nitrogen stream at 600 ° C. in the same manner as described above. In-furnace bonding with no load for 30 minutes was performed to obtain an Al—AlN bonded substrate (sample 4).
[0041]
Next, an AlN metallized substrate having the same shape as described above and having a W refractory metal layer was produced by the cofire metallization method in the same manner as in Example 1. An Al—Si brazing material having the same length and width as the substrate and a thickness of 0.04 mm is placed on the W refractory metal layer of the substrate, and the length and width are both the same as the substrate and the thickness is 0.0. A 3 mm JIS 1080 aluminum material was placed, and in-furnace bonding was performed in a nitrogen stream at 600 ° C. for 30 minutes in the same manner as above to obtain an Al—AlN bonded substrate (Sample 5).
[0042]
Also, an AlN metallized substrate having a W refractory metal layer obtained by the cofire metallization method was prepared, and a Ni layer having a thickness of 2 μm was formed on the W refractory metal layer of the substrate by plating, and then a long layer was formed thereon. An Al-Si brazing material having the same thickness and width as the substrate and a thickness of 0.04 mm is placed thereon, and an aluminum material of JIS 1080 having the same length and width as the substrate and a thickness of 0.3 mm is placed thereon. In the same manner as above, in-furnace bonding was performed in a nitrogen stream at 600 ° C. for 30 minutes to obtain an Al—AlN bonded substrate (sample 6).
[0043]
An AlN metallized substrate having a W refractory metal layer obtained by the cofire metallization method as described above was prepared, and a Ni layer having a thickness of 2 μm was formed on the W refractory metal layer of the substrate by plating. Further, an Al-Si brazing material having a length and width of 0.6 mm smaller than the substrate and a thickness of 0.04 mm is placed in the center of the Ni layer on the substrate, and both the length and width are larger than the substrate in the center. A 0.6 mm smaller and 0.3 mm thick JIS 1080 aluminum material was placed, and in the same manner as above, in-furnace bonding was performed in a nitrogen stream at 600 ° C. for 30 minutes, and an Al—AlN bonded substrate (sample) 7) was obtained.
[0044]
Further, an AlN metallized substrate having a W refractory metal layer obtained by the cofire metallization method as described above was prepared, and a Ni layer having a thickness of 2 μm was formed on the W refractory metal layer of the substrate by plating. On the other hand, a JIS 1080 aluminum material having a length and width of 0.6 mm smaller than this substrate and a thickness of 0.3 mm was prepared, and a Si-rich layer having a thickness of 2 μm was formed on the bonding surface by Si ion implantation. Next, the Ni layer of the AlN metallized substrate and the Si-rich layer of the aluminum material are brought into close contact with each other at the center position, and in the same manner as described above, in-furnace bonding is performed in a nitrogen stream at 600 ° C. for 30 minutes. An Al—AlN bonded substrate (Sample 8) was obtained.
[0045]
As a result of analyzing the ultrasonic flaw detection surface for each of the samples 3 to 8 produced as described above, no abnormal defect was observed. Further, when the cross section of the sample after bonding was observed with a 1000 times SEM (scanning electric microscope), no cracks, pinholes, or the like were found at the interface of each sample. In addition, the joining rate was calculated | required similarly to Example 1 about each sample, and it showed in following Table 2.
[0046]
Further, in the same manner as in Example 1, the members of Samples 3 to 8 were joined to a heat sink made of Cu—W alloy using eutectic solder, and 100 semiconductor devices were manufactured. Each of these semiconductor devices was subjected to a heat cycle test of 1000 cycles under the condition of −50 ° C. × 15 minutes → + 140 ° C. × 15 minutes, and then the defect portion was evaluated by ultrasonic flaw detection surface analysis and a 20 × stereo microscope. Then, the presence / absence of defects in each joint end face portion was investigated, and the yield rate after heat cycle test for 100 semiconductor devices was determined. The results are shown in Table 2 below.
[0047]
[Table 2]

(Note) Samples marked with * in the table are comparative examples.
[0048]
From Table 2 above, the samples 5 to 8 of the present invention having the W refractory metal layer as the stress relaxation layer have a stress applied to the ceramic substrate as compared with the samples 3 to 4 of the comparative examples having no W refractory metal layer. Since it becomes small, it can withstand the thermal shock by the heat cycle test, and it can be seen that the final yield rate is greatly increased. In addition, when Sample 3 and Sample 4 and Sample 5 and Sample 6 are compared, the interposition of the Ni layer may improve the wettability between the W refractory metal layer and the Ai-Si brazing material and increase the bonding rate. I understand.
[0049]
Furthermore, when comparing the sample 6 and the sample 7, it is possible to relieve stress at the time of bonding when the Al conductor layer smaller than the substrate is bonded, rather than when the Al conductor layer having the same size as the base material is bonded. It can be seen that the product can withstand thermal shock by heat cycle test and the yield rate is high. Moreover, it can be seen from the comparison between the sample 7 and the sample 8 that the stress relaxation effect is larger when the metal intervening layer such as Al—Si does not exist on the W refractory metal layer.
[0050]
In addition, it replaces with the metallization board | substrate by the said cofire metallization method, and when the semiconductor device was produced on the same conditions as the samples 5-8 of the said invention using the metallization board | substrate obtained by said post metallization method, respectively, it is substantially the same. Bonding rate and heat cycle characteristics were obtained. From this result, it is understood that substantially the same effect can be obtained even if the method of forming the refractory metal layer is different.
[0051]
Further, the refractory metal layer is changed from W to Ta, Mo or Mn, or the ceramic substrate is changed from AlN to Al.₂O_ThreeSystem or Si_ThreeN_FourIn place of the system, semiconductor devices were respectively produced under the same conditions as those of Samples 5 to 8 of the present invention, and almost the same joining rate and heat cycle characteristics were obtained in all cases. From this result, it can be seen that the same effect can be obtained even if the materials of the ceramic substrate and the refractory metal layer are different.
[0052]
Further, the Al—Si brazing material as the metal intervening layer is replaced with a Zn—Al alloy solder material, a Zn—Sn alloy solder material, and a Pb—Sn alloy solder material, and is the same as the samples 5 to 7 of the present invention. Each semiconductor device was fabricated under the same conditions, but almost the same bonding rate and heat cycle characteristics were obtained in all cases. From this result, it can be seen that substantially the same effect can be obtained even if the material of the metal intervening layer is different.
[0053]
【The invention's effect】
According to the present invention, when a metal member such as an aluminum lead frame is mounted on a ceramic substrate, the ceramic substrate is prevented from being damaged and deformed by the stress relaxation action of the refractory metal layer, and bonded with high bonding strength. It is possible to provide a semiconductor device member having high reliability even in a severe thermal cycle.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a specific example of a member for a semiconductor device of the present invention.
FIG. 2 is a schematic cross-sectional view for explaining a method for measuring peel strength in a semiconductor device member of the present invention.
FIG. 3 is a schematic cross-sectional view showing a specific example of a semiconductor device using the semiconductor device member of the present invention.
[Explanation of symbols]
1 Ceramic substrate 2 High melting point metal layer 3 Conductor layer
4 Metal intervening layer 5 Eutectic solder 6 Heat sink

Claims (7)

A ceramic substrate, a refractory metal layer mainly made of a refractory metal provided on the ceramic substrate, an Al-Si alloy, a Zn-Al alloy, Zn-Sn provided on the refractory metal layer A metal intervening layer made of at least one selected from a system alloy, a conductor layer mainly composed of aluminum being joined to the metal intervening layer, and the length and width in the planar direction at the joining interface of the conductor layer member for a semiconductor device but which is characterized in that from 0. it 05mm or less of the high-melting-point metal layer. 2. The member for a semiconductor device according to claim 1, wherein the refractory metal layer is made of at least one selected from W, Ta, Mo, and Mn . 3. The semiconductor device member according to claim 1 , wherein a length and a width in a planar direction at a bonding interface of the conductor layer are the same as those of the metal intervening layer . The ceramic base material is AlN system, characterized in that either _Al 2 _{O 3} system and _Si 3 _{N 4} based ceramic, the member for a semiconductor device according to claim 1. A method for manufacturing a member for a semiconductor device in which a conductor layer mainly composed of aluminum is bonded to a ceramic base material, wherein a paste containing a refractory metal is applied on a ceramic base material made of a sintered body and fired to obtain a high melting point. A step of forming a metal layer, a step of forming a metal intervening layer made of at least one selected from an Al-Si alloy, a Zn-Al alloy, and a Zn-Sn alloy on the refractory metal layer, And a step of bonding a conductor layer mainly composed of aluminum on the metal intervening layer, wherein the length and width in the plane direction at the bonding interface of the conductor layer are shorter than that of the refractory metal layer by 0.05 mm or more . A method for manufacturing a member for a semiconductor device . A method for manufacturing a member for a semiconductor device in which a conductor layer mainly composed of aluminum is bonded to a ceramic base material, wherein a paste containing a refractory metal is applied onto a molded body of ceramic raw material powder and fired to form a ceramic from the molded body The step of forming a refractory metal layer on the ceramic substrate at the same time as obtaining the substrate, and an Al-Si alloy, a Zn-Al alloy, or a Zn-Sn alloy was selected on the refractory metal layer. A step of forming at least one metal intervening layer; and a step of bonding a conductor layer mainly composed of aluminum on the metal intervening layer, the length and width in the planar direction at the bonding interface of the conductor layer method for producing it from 0. member for a semiconductor device characterized by shorter than 05mm of the refractory metal layer. A semiconductor device obtained by die-bonding a semiconductor element to the semiconductor device member according to claim 1 .

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