Summary of the invention
The present invention completes in view of the foregoing, its object is to provide power module substrate that a kind of certain bonding metal plates is high with ceramic substrate and cycle reliability, carries the power module substrate of radiator, possesses the power model of this power module substrate and the manufacture method of this power module substrate.
In order to solve this problem and realize described purpose, the power module substrate of the present invention, surface laminated at ceramic substrate is bonded to aluminum metal sheets, it is characterized in that, in described metallic plate, in addition to si, also solid solution has the one kind or two or more addition element in Zn, Ge, Ag, Mg, Ca, Ga and Li, in described metallic plate, amount in the scope being set in below more than 0.05 mass % 5 mass % with the concentration of the Si of the near interface of described ceramic substrate and described addition element.
In the power module substrate of this structure, owing to, in described metallic plate, in addition to si, also solid solution has the one kind or two or more addition element in Zn, Ge, Ag, Mg, Ca, Ga and Li, therefore makes the joint interface side part solution strengthening of metallic plate.This prevents rupturing of sheet metal part office, it is possible to increase joint reliability.
Here, owing to, in described metallic plate, adding up to more than 0.05 mass % with the concentration of the Si of the near interface of described ceramic substrate and described addition element, so can the joint interface side part of positively solution strengthening metallic plate.And, in described metallic plate, below 5 mass % are added up to the concentration of the Si of the near interface of described ceramic substrate and described addition element, so can prevent the intensity of the joint interface of metallic plate from excessively uprising, on this power module substrate during load cold cycling, thermal stress can be absorbed by metallic plate, and rupturing of ceramic substrate can be prevented.
Here, described ceramic substrate is by AlN or Al2O3Constitute, at the joint interface of described metallic plate Yu described ceramic substrate, it is possible to be formed with the Si high concentration portion of more than 5 times that Si concentration is Si concentration in described metallic plate.
Now, owing to being formed with the Si high concentration portion of more than 5 times that Si concentration is Si concentration in described metallic plate at the joint interface of described metallic plate Yu described ceramic substrate, so improving by AlN or Al by being present in the Si atom of joint interface2O3The ceramic substrate constituted and the bond strength of aluminum metal sheets.It addition, here, the Si concentration in metallic plate refers to, from joint interface away from the Si concentration of the part of certain distance (such as, more than 50nm) in metallic plate.
And, it is also possible to for as follows: described ceramic substrate is by AlN or Si3N4Constituting, the joint interface at described metallic plate Yu described ceramic substrate is formed with oxygen concentration and is higher than the oxygen high concentration portion of the oxygen concentration in described metallic plate and in described ceramic substrate, and the thickness in this oxygen high concentration portion is below 4nm.
Now, due to by AlN or Si3N4The ceramic substrate constituted is formed with the oxygen concentration oxygen high concentration portion higher than the oxygen concentration in described metallic plate and in described ceramic substrate with the joint interface of aluminum metal sheets, so improving by AlN or Si by being present in the oxygen of joint interface3N4The ceramic substrate constituted and the bond strength of aluminum metal sheets.Further, since the thickness in this oxygen high concentration portion is below 4nm, therefore can suppress to produce the crackle in oxygen high concentration portion by stress during load thermal cycle.
It addition, here, the oxygen concentration in metallic plate and in ceramic substrate refers to, from joint interface away from the oxygen concentration of the part of certain distance (such as, more than 50nm) in metallic plate and ceramic substrate.
The power module substrate carrying radiator of the present invention is characterised by, possesses described power module substrate and cools down the radiator of this power module substrate.
According to the power module substrate carrying radiator of this structure, owing to possessing the radiator having cooling power module substrate, it is possible to effectively cooled down the heat produced in power module substrate by radiator.
The power model of the present invention is characterised by, possesses described power module substrate and the electronic component being equipped on this power module substrate.
According to the power model of this structure, ceramic substrate is high with the bond strength of metallic plate, even if under severe use environment, it is possible to leap improves its reliability.
The manufacture method of the power module substrate of the present invention, it for being bonded to the manufacture method of the power module substrate of aluminum metal sheets in the surface laminated of ceramic substrate, it is characterized in that, have: set operation, at least one party in the composition surface of the composition surface of described ceramic substrate and described metallic plate, in addition to si, also set is selected from the one kind or two or more addition element of Zn, Ge, Ag, Mg, Ca, Ga and Li kind, is formed containing Si and the fixation layer of described addition element；Lamination, by described fixation layer, is laminated described ceramic substrate and described metallic plate；Heating process, heats the described ceramic substrate being laminated and described metallic plate while laminating direction pressurizes, forms motlten metal region at the interface of described ceramic substrate with described metallic plate；And solidification operation, engage described ceramic substrate and described metallic plate by solidifying this motlten metal region, wherein in described set operation, make Si and described addition element at 0.1mg/cm2Above 10mg/cm2Get involved at the interface of described ceramic substrate Yu described metallic plate in following scope, in described heating process, spread to described metallic plate side by the Si and described addition element making described fixation layer, form described motlten metal region at the interface of described ceramic substrate Yu described metallic plate.
The manufacture method of the power module substrate according to this structure, have owing to possessing: at least one party in the composition surface of the composition surface of described ceramic substrate and described metallic plate, in addition to si, the also set one kind or two or more addition element in Zn, Ge, Ag, Mg, Ca, Ga and Li, formed containing Si and the set operation of the fixation layer of described addition element, so at the joint interface of described metallic plate Yu described ceramic substrate, in addition to si, also intervention has the one kind or two or more addition element in Zn, Ge, Ag, Mg, Ca, Ga and Li.Here, due to the element that the element of Si and Zn, Ge, Ag, Mg, Ca, Ga and Li etc is the fusing point reducing aluminum, therefore under relatively cryogenic conditions, motlten metal region can be formed at the interface of metallic plate with ceramic substrate.
Thus, even if engaging under relatively low temperature, the engaging condition of short time, also can secure engagement ceramic substrate and metallic plate.
And, in heating process, by making the Si of fixation layer and the one kind or two or more addition element in Zn, Ge, Ag, Mg, Ca, Ga and Li spread to described metallic plate side, described motlten metal region is formed at the interface of described ceramic substrate Yu described metallic plate, and solidify this motlten metal region, thus become the structure engaging described metallic plate with described ceramic substrate, so without using solder paper tinsel etc. just can manufacture, with low cost, the power module substrate that metallic plate engages really with ceramic substrate.
So, do not use solder paper tinsel just can engage described ceramic substrate and described metallic plate, therefore without carrying out the para-position operation etc. of solder paper tinsel, such as, when the sheet metal being pre-formed into circuit pattern shape is engaged in ceramic substrate, it is possible to the trouble caused by dislocation etc. is prevented trouble before it happens.
Further, in described set operation, it is set to 0.1mg/cm in described ceramic substrate with the Si at the interface of described metallic plate and the fixed amount of described addition element by getting involved2Above, therefore at the interface of ceramic substrate Yu metallic plate, can positively form motlten metal region, and can securely bonding ceramic substrate and metallic plate.
It addition, be set to 10mg/cm in described ceramic substrate with the Si at the interface of described metallic plate and the fixed amount of described addition element by getting involved2Hereinafter, therefore can prevent from cracking in fixation layer, and can positively form motlten metal region at the interface of ceramic substrate Yu metallic plate.It addition, be prevented from Si and described addition element, excessively to the diffusion of metallic plate side, the intensity of the metallic plate of near interface excessively uprises.Thus, when power module substrate load cold cycling, thermal stress can be absorbed by metallic plate, and rupturing of ceramic substrate can be prevented.
It addition, in described set operation, make Si and described addition element at 0.1mg/cm2Above 10mg/cm2Get involved in following scope in the interface of described ceramic substrate Yu described metallic plate, therefore can manufacture following power module substrate: in described metallic plate, amount to more than 0.05 mass % in the scope below 5 mass % with the concentration of the Si of the near interface of described ceramic substrate and described addition element.
Being additionally, since and directly form fixation layer on metallic plate and ceramic substrate, therefore oxide film is only formed in the surface of metallic plate.Then, compared with employing when two sides forms the solder paper tinsel of oxide film, it is present in the total lower thickness of the oxide film at the interface of metallic plate and ceramic substrate, therefore, it is possible to improve the yield rate of initial engagement.
It addition, become following structure: at least one party direct set Si in the composition surface of the composition surface of described ceramic substrate and described metallic plate and described addition element, but from the viewpoint of productivity, preferably at composition surface set Si and the described addition element of metallic plate.
And it is possible at least one party in the composition surface of the composition surface of described ceramic substrate and described metallic plate, individually set Si and described addition element and form Si layer and addition element layer.Or, it is also possible at least one party in the composition surface of the composition surface of described ceramic substrate and described metallic plate, simultaneously set Si and described addition element and form Si and the fixation layer of described addition element.
Here, in described set operation, preferably become and Si and the structure of described addition element together set Al.
Now, due to Si and described addition element together set Al, the fixation layer therefore formed contains Al, and in heating process, this fixation layer can preferentially melt and really form motlten metal region, and can securely bonding ceramic substrate and metallic plate.Further, it is possible to prevent the oxidation of the oxidation activity elements such as Mg, Ca, Li.It addition, in order to Si and described addition element together set Al, Si and described addition element and Al can be deposited with, it is possible to sputtered as target by the alloy of Si and described addition element with Al simultaneously.Additionally, it is possible to lamination Si and addition element and Al.
And, described set operation is preferably by plating, evaporation, CVD, sputtering, cold spraying or paste and the ink etc. being dispersed with powder by coating, at least one party set Si in the composition surface of the composition surface of described ceramic substrate and described metallic plate and described addition element.
Now, due to by plating, evaporation, CVD, sputtering, cold spraying or paste and the ink etc. being dispersed with powder by coating, Si and described addition element are by least one party in the composition surface being really bonded to the composition surface of described ceramic substrate and described metallic plate, therefore, it is possible to make Si and described addition element really get involved in the joint interface of ceramic substrate Yu metallic plate.Further, Si and the fixed amount of described addition element can be regulated in high precision, it is possible to really form motlten metal region and securely bonding ceramic substrate and metallic plate.
In accordance with the invention it is possible to provide metallic plate really to engage with ceramic substrate and power module substrate that cycle reliability is high, carry the power module substrate of radiator, possess the power model of this power module substrate and the manufacture method of this power module substrate.
Detailed description of the invention
Hereinafter, referring to the drawings embodiments of the present invention are illustrated.Fig. 1 represents the power module substrate of the 1st embodiment of the present invention, the power module substrate carrying radiator and power model.
This power model 1 possesses and has: power module substrate 10, is equipped with circuit layer 12；Semiconductor chip 3, is engaged in the surface of circuit layer 12 by layer 2；And radiator 4.Here, layer 2 for example, Sn-Ag system, Sn-In system or the solder of Sn-Ag-Cu system.It addition, in the present embodiment, Ni coating (not shown) it is provided with between circuit layer 12 and layer 2.
Power module substrate 10 possesses and has: ceramic substrate 11；Circuit layer 12, is disposed in the one side (in FIG for top) of this ceramic substrate 11；And metal level 13, it is disposed in the another side (in FIG for bottom) of ceramic substrate 11.
Ceramic substrate 11 prevents the electrical connection between circuit layer 12 and metal level 13, and the AlN (aluminium nitride) high by insulating properties is constituted.Further, the thickness of ceramic substrate 11 is set in the range of 0.2～1.5mm, is set as 0.635mm in the present embodiment.It addition, as it is shown in figure 1, in the present embodiment, the width setup of ceramic substrate 11 is to be wider than circuit layer 12 and the width of metal level 13.
As it is shown in figure 5, circuit layer 12 is formed by having the metallic plate 22 of electric conductivity at the one side of ceramic substrate 11 joint.In the present embodiment, the metallic plate 22 that circuit layer 12 is constituted by being rolled plate by the aluminum (so-called 4N aluminum) that purity is more than 99.99% is engaged in ceramic substrate 11 and is formed.
As it is shown in figure 5, metal level 13 is formed by the another side bonding metal plates 23 at ceramic substrate 11.In the present embodiment, metal level 13 and circuit layer 12 are engaged in ceramic substrate 11 again by the metallic plate 23 being made up of aluminum (so-called 4N aluminum) the calendering plate that purity is more than 99.99% and are formed.
Radiator 4 is used for cooling down described power module substrate 10, possesses and has: top plate portion 5, engages with power module substrate 10；And stream 6, it is used for making cooling medium (such as cooling down water) circulate.Radiator 4 (top plate portion 5) is preferably made up of the material that heat conductivity is good, in the present embodiment, is made up of A6063 (aluminium alloy).
Further, in the present embodiment, the cushion 15 being made up of aluminum or aluminum alloy or the composite (such as AlSiC etc.) containing aluminum it is provided with between top plate portion 5 and the metal level 13 of radiator 4.
And, as shown in Figure 2, in the width central part of ceramic substrate 11 and the joint interface 30 of circuit layer 12 (metallic plate 22) and metal level 13 (metallic plate 23), in circuit layer 12 (metallic plate 22) and metal level 13 (metallic plate 23), in addition to si, also solid solution has the one kind or two or more addition element in Zn, Ge, Ag, Mg, Ca, Ga and Li.The concentration dipping bed 33 that the concentration of Si concentration and described addition element reduces along with leaving to laminating direction it is formed with from joint interface 30 in the vicinity of the joint interface 30 of circuit layer 12 and metal level 13.Here, the concentration of the Si of joint interface 30 side of this concentration dipping bed 33 (vicinity of the joint interface 30 of circuit layer 12 and metal level 13) and described addition element amounts in the scope being set in below more than 0.05 mass % 5 mass %.
It addition, the concentration of Si near the joint interface 30 of circuit layer 12 and metal level 13 and described addition element is to analyze (spot diameter 30 μm) by EPMA to carry out 5 meansigma methodss measured in 50 μm positions of distance joint interface 30.Further, the chart of Fig. 2 is to carry out linear analysis, and the chart concentration of described 50 μm positions obtained as benchmark at the middle body of circuit layer 12 (metallic plate 22) and metal level 13 (metallic plate 23) to laminating direction.
At this, in present embodiment, being used as addition element by Ge, and the Ge concentration near the joint interface 30 of circuit layer 12 and metal level 13 is set in the scope of below more than 0.05 mass % 1 mass %, Si concentration is set in the scope of below more than 0.05 mass % 0.5 mass %.
Further, when transmission electron microscope is observed the joint interface 30 of ceramic substrate 11 and circuit layer 12 (metallic plate 22) and metal level 13 (metallic plate 23), as it is shown on figure 3, be formed with the Si high concentration portion 32 concentrating Si at joint interface 30.In this Si high concentration portion 32, Si concentration exceeds more than 5 times than the Si concentration in circuit layer 12 (metallic plate 22) and metal level 13 (metallic plate 23).It addition, the thickness H in this Si high concentration portion 32 is below 4nm.
At this, as it is shown on figure 3, the central authorities between the interface side end of circuit layer 12 (metallic plate 22) and the lattice image of the interface side end of the lattice image of metal level 13 (metallic plate 23) and ceramic substrate 11 are set to datum level S by observed joint interface 30.
Hereinafter, with reference to Fig. 4 to Fig. 6, the manufacture method of the power module substrate 10 of described structure is illustrated.
(set operation S1)
First, as shown in Figures 5 and 6, by sputtering at each composition surface set Si of metallic plate 22,23 and the one kind or two or more addition element in Zn, Ge, Ag, Mg, Ca, Ga and Li, fixation layer 24,25 is formed.
Here, in the present embodiment, being used as addition element by Ge, the Si amount in fixation layer 24,25 is set in 0.002mg/cm2Above 1.2mg/cm2Hereinafter, Ge amount is set in 0.002mg/cm2Above 2.5mg/cm2Below.
(lamination S2)
Then, as it is shown in figure 5, metallic plate 22 to be laminated to the one side side of ceramic substrate 11, and metallic plate 23 is laminated to the another side side of ceramic substrate 11.Now, as shown in Figures 5 and 6, in metallic plate 22,23, being laminated in the way of ceramic substrate 11 of fixation layer 24,25 it is formed with.That is, between metallic plate 22,23 and ceramic substrate 11, intervention has fixation layer 24,25 (Si and described addition element) respectively.It is thusly-formed layered product 20.
(heating process S3)
Then, by the layered product 20 formed in lamination S2, to pressurize to its laminating direction, (pressure is 1～35kgf/cm2) state load in vacuum furnace and heat, as shown in Figure 6, form motlten metal region 26,27 respectively at the interface of metallic plate 22,23 with ceramic substrate 11.As shown in Figure 6, this motlten metal region 26,27 is by being formed as follows: Si and the described addition element of fixation layer 24,25 spread to metallic plate 22,23 side, thus the Si concentration near the fixation layer 24,25 of metallic plate 22,23 and concentration (the being Ge concentration in the present embodiment) rising of described addition element, fusing point reduces.It addition, above-mentioned pressure is less than 1kgf/cm2Time, it is possible to the joint of ceramic substrate 11 and metallic plate 22,23 cannot be carried out well.Further, above-mentioned pressure is more than 35kgf/cm2Time, metallic plate 22,23 likely deforms.Thus, above-mentioned moulding pressure is preferably located at 1～35kgf/cm2In the range of.
Here, in present embodiment, the pressure in vacuum furnace is set in 10-3～10-6In the range of Pa, heating-up temperature is set in the scope of more than 550 DEG C less than 650 DEG C.
(solidification operation S4)
Then, when being formed with motlten metal region 26,27, temperature is remained constant.So, the Si in motlten metal region 26,27 and addition element (being Ge in the present embodiment) spread to metallic plate 22,23 side further.Thus, once the Si concentration of part and the concentration (in the present embodiment for Ge concentration) of described addition element for motlten metal region 26,27 were gradually lowered, and fusing point rises, and solidifies when remaining constant by temperature.That is, ceramic substrate 11 and metallic plate 22,23 engages (TransientLiquidPhaseDiffusionBonding) by so-called diffusion and engages.So, room temperature it is cooled to after solidifying.
So, the metallic plate 22,23 becoming circuit layer 12 and metal level 13 engages with ceramic substrate 11, produces the power module substrate 10 of present embodiment.
In the power module substrate 10 becoming the present embodiment such as above structure and power model 1, having in the composition surface set Si of metallic plate 22,23 and set operation S1 of described addition element (in the present embodiment for Ge) owing to possessing, having Si and described addition element so getting involved on the composition surface 30 of metallic plate 22,23 with ceramic substrate 11.Here, due to the element that the element of Si and Zn, Ge, Ag, Mg, Ca, Ga and Li etc is the fusing point reducing aluminum, therefore under conditions of relatively low temperature, it is also possible to form motlten metal region at the interface of metallic plate with ceramic substrate.
Additionally, ceramic substrate 11 passes through to make to be formed at metallic plate 22 with circuit layer 12 (metallic plate 22) and metal level 13 (metallic plate 23), the fixation layer 24 containing Si and described addition element on the composition surface of 23, the Si of 25 and described addition element are to metallic plate 22, 23 side diffusions form motlten metal region 26, 27, and by making this motlten metal region 26, Si in 27 and described addition element are to metallic plate 22, 23 spread and solidify and engage, therefore at relatively low temperature, engage under the engaging condition of short time, it also is able to secure engagement ceramic substrate 11 and metallic plate 22, 23.
nullAnd，In the width central part of ceramic substrate 11 and the joint interface 30 of circuit layer 12 (metallic plate 22) and metal level 13 (metallic plate 23)，Si and described addition element is had at circuit layer 12 (metallic plate 22) and metal level 13 (metallic plate 23) solid solution，The Si of each joint interface 30 side of circuit layer 12 and metal level 13 and the concentration of described addition element amount in the scope being set in below more than 0.05 mass % 5 mass %，In the present embodiment，Ge is used as addition element，Ge concentration near the joint interface 30 of circuit layer 12 and metal level 13 is set in the scope of below more than 0.05 mass % 1 mass %，Si concentration is set in the scope of below more than 0.05 mass % 0.5 mass %，So the part solution strengthening of joint interface 30 side of circuit layer 12 (metallic plate 22) and metal level 13 (metallic plate 23)，The generation of the be full of cracks being prevented from circuit layer 12 (metallic plate 22) and metal level 13 (metallic plate 23).
Further, in heating process S3, Si and described addition element fully spread to metallic plate 22,23 side, and secure engagement metallic plate 22,23 and ceramic substrate 11.
Additionally, in the present embodiment, ceramic substrate 11 is made up of AlN, joint interface 30 at metallic plate 22,23 with ceramic substrate 11 is formed with the Si high concentration portion 32 that Si concentration becomes more than 5 times of Si concentration in circuit layer 12 (metallic plate 22) and metal level 13 (metallic plate 23), therefore, it is possible to by being present in the raising that the Si of joint interface 30 seeks the bond strength of ceramic substrate 11 and metallic plate 22,23.
And, possess to have and form set operation S1 of fixation layer 24,25 at composition surface set Si and the described addition element of metallic plate, and it is configured to as follows: in heating process S3, spread to metallic plate 22,23 side by the Si and described addition element making fixation layer 24,25, thus form motlten metal region 26,27 at the interface of ceramic substrate 11 with metallic plate 22,23, therefore, without using the solder paper tinsel of the Al-Si system manufacturing difficulty, it becomes possible to the power module substrate 10 really engaged with low cost manufacture metallic plate 22,23 and ceramic substrate 11.
It addition, in the present embodiment, in set operation S1, get involved Si amount and Ge amount in ceramic substrate 11 with the interface of metallic plate 22,23 and be set as Si:0.002mg/cm2Above, Ge:0.002mg/cm2Above, therefore, it is possible to positively form motlten metal region 26,27 at the interface of ceramic substrate 11 with metallic plate 22,23, and can secure engagement ceramic substrate 11 and metallic plate 22,23.
Further, since be set as Si:1.2mg/cm by getting involved Si amount and the Ge amount in ceramic substrate 11 with the interface of metallic plate 22,232Below, Ge:2.5mg/cm2Hereinafter, therefore, it is possible to prevent from, at fixation layer 24,25, crackle occurs, and motlten metal region 26,27 can really be formed at the interface of ceramic substrate 11 with metallic plate 22,23.It addition, be prevented from Si and described addition element, excessively to the diffusion of metallic plate 22,23 side, the intensity of the metallic plate 22,23 of near interface becomes too high.Thus, when power module substrate 10 load cold cycling, thermal stress can be absorbed by circuit layer 12, metal level 13 (metallic plate 22,23), and be prevented from rupturing of ceramic substrate 11.
Further, owing to not using solder paper tinsel, fixation layer 24,25 is directly formed on the composition surface of metallic plate 22,23, therefore without carrying out the para-position operation etc. of solder paper tinsel, it becomes possible to bonding ceramic substrate 11 and metallic plate 22,23 really.Thus, it is possible to effectively produce this power module substrate 10.
It is additionally, since and is formed with fixation layer 24,25 on the composition surface of metallic plate 22,23, thus get involved the oxide film in metallic plate 22,23 with the interface of ceramic substrate 11 and exist only in the surface of metallic plate 22,23, therefore, it is possible to improve the yield rate of initial engagement.
Then, with reference to Fig. 7 to Figure 10, the 2nd embodiment of the present invention is illustrated.
In the power module substrate of the 2nd embodiment, ceramic substrate 111 is by Si3N4Constitute.
In the width central part of ceramic substrate 111 and the joint interface 130 of circuit layer 112 (metallic plate 122) and metal level 113 (metallic plate 123), as shown in Figure 7, in circuit layer 112 (metallic plate 122) and metal level 113 (metallic plate 123), in addition to si, also solid solution has the addition element more than in a kind or 2 in Zn, Ge, Ag, Mg, Ca, Ga and Li.Here, the concentration of Si near the joint interface 130 of circuit layer 112 and metal level 113 and described addition element amounts in the scope being set in below more than 0.05 mass % 5 mass %.
It addition, the concentration of Si near the joint interface 130 of circuit layer 112 and metal level 113 and described addition element is to analyze (spot diameter 30 μm) by EPMA to carry out 5 meansigma methodss measured in 50 μm positions of distance joint interface 130.Further, the chart of Fig. 7 is to carry out linear analysis, and the chart concentration of described 50 μm positions obtained as benchmark at the middle body of circuit layer 112 (metallic plate 122) and metal level 113 (metallic plate 123) to laminating direction.
At this, in present embodiment, being used as addition element by Ag, the Ag concentration near the joint interface 130 of circuit layer 112 and metal level 113 is set in the scope of below more than 0.05 mass % 1.5 mass %, and Si concentration is set in the scope of below more than 0.05 mass % 0.5 mass %.
And, when observing the joint interface 130 of ceramic substrate 111 and circuit layer 112 (metallic plate 122) and metal level 113 (metallic plate 123) in transmission electron microscope, as shown in Figure 8, the oxygen high concentration portion 132 of concentrate oxygen it is formed with at joint interface 130.In this oxygen high concentration portion 132, oxygen concentration is higher than the oxygen concentration in circuit layer 112 (metallic plate 122) and metal level 113 (metallic plate 123).It addition, the thickness H in this oxygen high concentration portion 132 is below 4nm.
Additionally, as shown in Figure 8, the central authorities between the joint interface side end of circuit layer 112 (metallic plate 122) and the lattice image of the interface side end of the lattice image of metal level 113 (metallic plate 123) and ceramic substrate 111 are set to datum level S by the joint interface 130 observed at this.
Hereinafter, with reference to Fig. 9 and Figure 10, the manufacture method of the power module substrate of described structure is illustrated.It addition, in the present embodiment, set operation is divided into Si set operation S10 and addition element set operation S11.
(Si set operation S10)
First, as shown in Figure 10, by sputtering at each composition surface set Si of metallic plate 122,123, Si layer 124A, 125A are formed.Here, the Si amount of Si layer 124A, 125A is set in 0.002mg/cm2Above 1.2mg/cm2Below.Further, in the thickness of Si layer 124A, 125A is preferably set to the scope of below more than 0.01 μm 5 μm.
(addition element set operation S11)
Then, by sputtering at the described Si upper set of layer 124A, 125A one kind or two or more addition element in Zn, Ge, Ag, Mg, Ca, Ga and Li, addition element layer 124B, 125B are formed.Here, in the present embodiment, Ag is used to be set in 0.08mg/cm as addition element, the Ag amount in addition element layer 124B, 125B2Above 5.4mg/cm2Below.Further, in the thickness of addition element layer 124B, 125B is preferably set to the scope of below more than 0.01 μm 5 μm.
(lamination S12)
Then, metallic plate 122 is laminated to the one side side of ceramic substrate 111, and metallic plate 123 is laminated to the another side side of ceramic substrate 111.Now, as shown in Figure 10, in metallic plate 122,123, it is formed with being laminated in the way of ceramic substrate 111 of Si layer 124A, 125A and addition element layer 124B, 125B.That is, between metallic plate 122,123 and ceramic substrate 111, intervention has Si layer 124A, 125A and addition element layer 124B, 125B respectively.It is thusly-formed layered product.
(heating process S13)
Then, by the layered product formed in lamination S12, to pressurize to its laminating direction, (pressure is 1～35kgf/cm2) state load in vacuum furnace and heat, as shown in Figure 10, form motlten metal region 126,127 respectively at the interface of metallic plate 122,123 with ceramic substrate 111.As shown in Figure 10, this motlten metal region 126,127 is by being formed as follows: Si layer 124A, 125A and the Si of addition element layer 124B, 125B and addition element (in the present embodiment for Ag) spread to metallic plate 122,123 side, thus the concentration of Si concentration near Si layer 124A, 125A of metallic plate 122,123 and addition element layer 124B, 125B and addition element rises, fusing point reduces.
Here, in present embodiment, the pressure in vacuum furnace is set in 10-3～10-6In the range of Pa, heating-up temperature is set in the scope of more than 550 DEG C less than 650 DEG C.
(solidification operation S15)
Then, when being formed with motlten metal region 126,127, temperature is remained constant.So, the Si in motlten metal region 126,127 and addition element spread to metallic plate 122,123 side further.Thus, once the Si concentration of part and the concentration of addition element for motlten metal region 126,127 were gradually lowered, and fusing point rises, and solidifies when temperature remains constant.That is, ceramic substrate 111 engages (TransientLiquidPhaseDiffusionBonding) with metallic plate 122,123 by so-called diffusion and engages.So, room temperature it is cooled to after solidifying.
So, the metallic plate 122,123 becoming circuit layer 112 and metal level 113 engages with ceramic substrate 111, produces the power module substrate of present embodiment.
In becoming such as the power module substrate of the present embodiment of above structure, having in addition element set operation S11 of addition element (in the present embodiment for Ag) described in Si set operation S10 of composition surface set Si of metallic plate 122,123 and set owing to possessing, having Si and described addition element so getting involved in the metallic plate 122,123 joint interface 130 with ceramic substrate 111.Here, the element of Si and Zn, Ge, Ag, Mg, Ca, Ga and Li etc reduces the fusing point of aluminum, it is possible to engage under cryogenic.
Additionally, ceramic substrate 111 passes through to make to be formed at metallic plate 122 with circuit layer 112 (metallic plate 122) and metal level 113 (metallic plate 123), the Si layer 124A on the composition surface of 123, 125A and addition element layer 124B, the Si of 125B and addition element are to metallic plate 122, 123 side diffusions form motlten metal region 126, 127, and by making this motlten metal region 126, Si in 127 and addition element are to metallic plate 122, 123 spread and solidify and engage, therefore at relatively low temperature, under the engaging condition of short time, it also is able to secure engagement ceramic substrate 111 and metallic plate 122, 123.
Further, in present embodiment, owing to ceramic substrate 111 is by Si3N4Constitute, joint interface 130 at the metallic plate 122,123 with ceramic substrate 111 that become circuit layer 112 and metal level 113 generates the oxygen high concentration portion 132 of the oxygen concentration having oxygen concentration to be higher than in the metallic plate 122,123 constituting circuit layer 112 and metal level 113, therefore can be sought the raising of ceramic substrate 111 and the bond strength of metallic plate 122,123 by this oxygen.Further, owing to the thickness in this oxygen high concentration portion 132 is below 4nm, the crackle produced in oxygen high concentration portion 132 by stress during load thermal cycle is therefore suppressed.
Above, being illustrated embodiments of the present invention, but the invention is not limited in this, the scope at the technological thought invented without departing from it can suitably change.
Such as, be illustrated during for the metallic plate constituting circuit layer and metal level is rolled plate as the fine aluminium of purity 99.99%, but be not limited thereto, it is also possible to be purity be the aluminum (2N aluminum) of 99%.
And, in set operation, for being illustrated at the composition surface set Si of metallic plate and the structure of described addition element, but it is not limited thereto, can be at the composition surface set Si of ceramic substrate and described addition element, it is also possible at the composition surface of the composition surface of ceramic substrate and metallic plate difference set Si and described addition element.
Further, in set operation, can be with Si and described addition element together set Al.
Additionally, in set operation, it is illustrated by the situation of sputtering set Si and described addition element, but is not limited thereto, also can be by plating, evaporation, CVD, cold spraying or paste and the ink etc. being dispersed with powder by coating, set Si and described addition element.
Further, in the 2nd embodiment, the situation being added element set operation S11 in making set operation after Si set operation S10 is illustrated, but is not limited thereto, and can carry out Si set operation after addition element set operation.
It addition, the alloy of addition element and Si etc. can be used to form the alloy-layer of Si and addition element.
Further, the situation using vacuum furnace to carry out ceramic substrate and the joint of metallic plate is illustrated, but is not limited thereto, it is also possible at N2The joint of ceramic substrate and metallic plate is carried out under the conditions of atmosphere, Ar atmosphere and He atmosphere etc..
Further it is illustrated in the case of, for arranging the cushion being made up of aluminum or aluminum alloy or the composite (such as AlSiC etc.) containing aluminum between the top plate portion of radiator and metal level but it also may not this cushion.
It addition, the situation being made up of radiator aluminum is illustrated but it also may be made up of aluminium alloy or the composite etc. containing aluminum.It addition, be illustrated having the stream of the cooling medium situation as radiator, but the structure of radiator is not particularly limited, and can use the radiator of various structure.
Further, to by AlN, Si3N4The situation constituting ceramic substrate is illustrated, but is not limited to this, it is also possible to by Al2O3Constitute on other potteries.