JPH07335792A - Package for mounting semiconductor element - Google Patents

Abstract

PURPOSE:To prevent warps and the like in a crack package with a ceramic frame by bonding a copper plate to one side of the ceramic frame to form a cavity, and forming at the bottom of the cavity a stress absorbing region to absorb part of thermal stress. CONSTITUTION:A copper plate 1 is bonded to one side of a ceramic frame 2 to form a cavity 7. A stress absorbing region G is formed on the periphery of the copper plate 1 that constitutes the bottom of the cavity 7; the stress absorbing region G absorbs thermal stress on the ceramic frame 2 and the copper plate 1 through deformation in the copper plate 1. A stress fixing member 4 that prevents the copper plate 1 from being deformed is placed at the central portion of the copper plate 1 to form a semiconductor mounting region D. The thickness of the copper plate 1 is set to 0.05-1.1mm in the stress absorbing region G. The thickness of the stress fixing region E, the width d of the stress absorbing region G, and so on are properly selected according to the thickness of the copper plate 1 and the area of the bottom of the cavity. Part or all of the height h of the projection in the copper plate 1, forming the stress absorbing region G, may be ground for higher flatness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel semiconductor element mounting package. More specifically, it is a semiconductor element mounting package in which a bottom surface of a ceramic frame is formed of a copper plate having a high heat dissipation property to form a heat sink having an excellent heat dissipation property.

[0002]

2. Description of the Related Art As the performance and speed of information processing devices have increased, the density and integration of the semiconductor elements forming them have been rapidly increasing. Semiconductor devices such as microprocessors and gate arrays have 3 to 5 million transistors integrated, and the amount of heat generated per unit area and unit volume is increasing year by year.

Conventionally, in order to dissipate heat generated by a semiconductor element, as shown in FIG. 2, a heat sink made of a metal plate 6 made of copper or the like having good thermal conductivity is attached to a ceramic frame body 2 made of a ceramic insulating material. A package in which a cavity is formed by bonding is mainly used.

In the above package, the heat generated from the semiconductor element is transferred to and absorbed by the heat sink, and the absorbed heat is released to the atmosphere.

However, the thermal conductivity is about 400 W / m · K.
Copper, which is known as a good heat conductive material, has the following problems when it is used as a heat sink that constitutes the semiconductor element mounting package.

That is, the coefficient of thermal expansion of copper is 18.8 × 10.
^-6 / ° C. is very large when compared to that of the ceramic (4~7 × 10 ^-6 / ℃) and semiconductor element (4.8 × 10 ^-6 / ℃) at.

Therefore, when the above metal plate is used as a heat dissipation member, the stress caused by the difference in the thermal expansion coefficient between the ceramic frame and the harmful metal plate (hereinafter also referred to as thermal stress) causes Cracks and chips, warpage of the entire package, and warpage of a semiconductor element mounting portion (die attach) occur, which adversely affects adhesion at the time of mounting a semiconductor element and reliability of the package.

Therefore, in such a semiconductor element mounting package, a technique for matching the thermal expansion coefficient among the ceramic frame, the metal plate and the materials forming the semiconductor element has been studied and proposed.

For example, in order to eliminate the difference in the coefficient of thermal expansion between the ceramic frame and the metal plate as the heat sink, the thermal expansion of the copper and other ceramics, such as copper-tungsten alloy, which is bonded by compounding it It has been proposed to construct a heat sink with a heat conductive material having an approximate coefficient.

[0010]

However, conventionally proposed thermal conductive materials such as copper-tungsten alloys do not have sufficient thermal conductivity, and there is still room for improvement in heat dissipation performance. That is, in the copper-tungsten alloy, Cu and W must be complexed or alloyed in order to match the coefficient of thermal expansion with that of the ceramic frame. Therefore, copper itself has high thermal conductivity, low cost, and low cost. It is nothing but the sacrifice of the feature of workability.

[0011]

DISCLOSURE OF THE INVENTION In the package for mounting a semiconductor element having a heat sink, the present inventors have substantially independently used copper having good thermal conductivity with respect to the copper alloy used as the heat sink. However, for semiconductor element mounting that suppresses the occurrence of cracks and chips in the ceramic frame due to thermal stress, warpage of the entire package, and warpage during die attachment in the cavity, which are problems when using the copper. We have earnestly researched to develop a package.

As a result, in a package in which a copper plate is bonded to one surface of a ceramic frame to form a cavity,
By forming a stress absorption region that absorbs at least a part of thermal stress applied to the copper plate and the ceramic frame by the deformation of a part of the copper plate in the copper plate forming the peripheral portion of the bottom surface of the cavity, The inventors have found that the above can be achieved and completed the present invention.

In order to explain the present invention in more detail,
Although the present invention will be described with reference to the accompanying drawings, the present invention is not limited to these accompanying drawings.

FIG. 1 is a cross-sectional view schematically showing a typical embodiment of a semiconductor device package of the present invention, a plan view and a cross-sectional view schematically showing a deformed state of a stress absorption region. FIG. 5 is a cross-sectional view (including a cross-sectional view showing dimensions of each part of the copper plate) schematically showing another aspect of the semiconductor element package of the present invention.

In the semiconductor element package of the present invention, the copper plate 1 is joined to one surface of the ceramic frame 2 to form the cavity 7.
And a stress absorption region G that absorbs thermal stress between the ceramic frame 2 and the copper plate 1 due to the deformation of the copper plate 1 is formed in the peripheral portion of the copper plate 1 forming the bottom surface of the cavity 7. It is characterized by having done.

In the semiconductor element mounting package of the present invention, known ceramic materials are used without limitation as the ceramic having the ceramic frame. Of these, particularly preferable ceramic components for further improving the heat dissipation of the semiconductor element mounting package are glass ceramic, mullite, partially stabilized zirconia, silicon nitride, alumina, aluminum nitride, silicon carbide, boron nitride, beryllia, etc. Is raised. Of these, the most preferable are alumina, aluminum nitride, and mullite, which also have sufficient mechanical strength.

Further, as the structure of the ceramic frame body 2, a structure having a cutout portion for forming the cavity 7 by being joined to the copper plate 1 is adopted without particular limitation. For example, as a structure, as shown in FIG. 1, a structure formed by integral sintering of ceramics, having a step on the inner wall of one step to several steps and having a central portion penetrating, as shown in FIG. A typical example is a structure in which a ceramic flat frame whose inner diameter is gradually reduced downward is joined with an adhesive such as an active metal via a copper foil (for electric circuit).

In the ceramic frame body, the area of the notch portion present in the center is not particularly limited as long as it has a size capable of ensuring a space in which a target chip can be mounted.
Further, other dimensions of the ceramic frame body may be appropriately determined according to the area of the cutout portion so that the function of the package can be satisfied.

Further, in the embodiment of the ceramic frame body of FIG. 1, not only the single structure of ceramic but also W, Mo, C
A structure in which a metallized metal such as u or Ag is simultaneously fired to form a conductive layer inside or on the surface of the ceramic frame can be used without any problem. For example, pin grid array
Structures such as a package (PGA package), a sardep package, and a ceramic QFP can also be applied to the ceramic frame body as appropriate.

In the present invention, as the material of the copper plate, copper alone or a material containing other metal is used without particular limitation as long as the thermal conductivity of copper is not significantly reduced.

For example, oxygen-free copper, tough pitch copper, phosphorous deoxidized copper, etc., called copper rolled products, or Cu-Fe-Zn-P alloy (C-194), Cu-, which is a wrought copper alloy. Z
r-based alloys (C-151 etc.), Cu-Sn-based alloys (EFT
EC-3S etc.), Cu-Ni (white copper), etc. are mentioned.

The copper alloy has a thermal conductivity of about 300.
Those having a composition of W / m · K or more (higher than those of copper-tungsten alloys) are preferable. Further, the present invention is effective for a material having a coefficient of thermal expansion higher than 10 × 10 ⁻⁶ / ° C.

The tensile strength of these copper or copper alloys is generally about 200 to 400 MPa.

In the present invention, the ceramic frame 2 and the copper plate 1, or the stress fixing member and the copper plate, which will be described later, are generally joined by the joining layers 3-1 and 3-2 using a known joining material. Is. For example, when joining a ceramic frame and a copper plate, a brazing material or a polymer adhesive containing an active metal is generally used. Specifically, Ti, Zr,
Ag-C containing 0.1 to 20% by weight of active metal such as Hf
A u-based brazing material or a polymer adhesive such as polyimide-based, epoxy-based, or fluororesin-based adhesive can be used.

Further, the copper plate 1 and the stress fixing member 4 are joined, or the copper plate and the pin grid array package (PGA).
Package), sardep package, ceramic QF
For the joining of the ceramic frame such as P, a brazing material containing the above-mentioned active metal or a brazing material generally known as an organic adhesive (for example, silver brazing shown in JIS Z 3261-1985) can be used without any problem. Among them, BAg-8, BAg-
18, BAg-29 is most preferred. In this case, the coefficient of thermal expansion between the copper plate and the ceramic frame is between the copper plate and the ceramic frame, and Cu-Mo (30 to 70% Cu-remaining Mo: thermal expansion coefficient, 8.0 to 13.0x). 10 ^-6 / ° C)
Etc., a clad material such as Cu-Mo-Cu (weight ratio 1: 1: 1, coefficient of thermal expansion, 6.0 to 10.0 × 10 ^-6 / ° C.), and a soft material such as silver. It is also a preferred embodiment to sandwich and join the layers to absorb thermal stress due to the difference in thermal expansion coefficient between the copper plate and the ceramic frame.

Further, the copper plate 1 and a stress fixing member 4 described later are provided.
Also in the case of the above joining, in addition to the joining by the brazing material, an adhesive such as a thermally conductive organic material such as silver epoxy or direct joining such as welding or pressure bonding is possible.

Furthermore, according to the present invention, a ceramic frame body in which a ceramic and a copper foil are once joined together in advance with the active metal brazing material, a refractory metal such as W or Mo, or Au or A.
It is also possible to join a copper plate to the copper foil or the metallization with a normal brazing filler metal such as Ag—Cu containing no active metal, to a ceramic frame body having a metallization containing g, Cu or the like as a main component. .

An important requirement in the present invention is that the stress absorption region G for absorbing the thermal stress between the ceramic frame 2 and the copper plate 1 by the deformation of the copper plate 1 is the peripheral portion of the copper plate 1 forming the bottom surface of the cavity. It was formed in.

That is, the copper plate 1 forming the bottom surface of the cavity, that is, the peripheral edge of the copper plate 1 exposed from the cutout portion of the ceramic frame 1 is provided with a stress absorption region G for absorbing the thermal stress by the deformation of the copper plate 1. By forming it, plastic deformation corresponding to stress occurs preferentially in other parts, and as a result, thermal stress in other parts is relieved and the ceramic frame is cracked, the package is warped or die-attached. It is presumed that the problems such as the warp will be solved.

In the present invention, the means for forming the stress absorbing area G is not particularly limited as long as it has a structure having such a function, but the peripheral portion of the copper plate forming the bottom surface of the cavity is thinned to cause plastic deformation to another portion. With respect to the above, it is preferable to preferentially occur.

However, when the entire copper plate forming the bottom surface of the cavity is thinned to enable plastic deformation, the thermal stress applied to the package causes the copper plate to be deformed in the entire F portion as shown in FIG. The flatness of the touch part may not be maintained in some cases.

Therefore, in this embodiment, the stress fixing member 4 for suppressing the deformation of the copper plate is provided at the central portion of the copper plate 1 forming the bottom surface of the cavity so that the copper plate is not deformed. Moreover, a structure in which a stress absorption region G is formed in a copper plate located between the ceramic frame and the stress fixing member is recommended.

The stress fixing member 4 may be formed of a member different from the copper plate 1 as shown in FIGS. 1 and 4, or as shown in FIG. 5, the thickness of the copper plate at the portion is increased. It can also be formed by

The stress fixing member 4 is required to have a function of suppressing the deformation of the copper plate at the place where it is provided by means such as joining or integral molding.

Therefore, when the stress fixing member 4 is formed of another member, the copper plate forming the stress absorption region G has a large mechanical strength, for example, a member having high tensile strength or bending strength, and high hardness. It is possible to satisfy the above function by selecting and using a member having the above or by increasing the thickness of the copper plate of the stress fixing member 4.

A concrete example of the material of the above-mentioned stress fixing member 4 is Mo (tensile strength: 480MP).
a), metals such as W (tensile strength: 600 MPa), Cu-
W (tensile strength: 500 to 600 MPa), Cu-Cr,
Cu alloy such as Cu-Mo (450 to 800 MPa), Cu
-Mo-Cu, Cu-Inver-Cu, Cu-Kov
Clad materials such as ar-Cu, AlN, SiC, Si2N
3, BeO, alumina, etc. (Bending strength: 200-1000
(MPa) ceramic sintered bodies, semiconductors such as Si and GaAs are listed. Further, the stress fixing member 4 itself can be a material for forming a die attach. Incidentally, in the above aspect, it is possible to bond another material capable of achieving thermal expansion matching with the semiconductor element on the stress fixing member 4 and mount the semiconductor element on it, but there is no problem. Fixing member 4
It is more preferable that the material itself has a coefficient of thermal expansion matching with that of the semiconductor element. Further, when considering the thermal resistance of the package, for example, the thermal conductivity is about 100 to 300 W / m.
· K following materials in the range of, namely, Mo (thermal expansion coefficient: 5.1 × 10 ^-6 /℃),W(4.5×10 ^-6 /
C), Cu-W (eg 10% Cu-90% W or 20%
Cu-80% W, coefficient of thermal expansion: 6.0-7.0 × 10 ^-6
/ C), Cu-Mo (30-70% Cu-remaining Mo:
8.0-13.0 × 10 ⁻⁶ / ° C.) metals, alloys, Cu, etc.
-A for clad materials such as Mo-Cu or ceramics
In, BeO, SiC (coefficient of thermal expansion: 3.5 to 8.0 x
10 ⁻⁶ / ° C.) and Si are the most preferable examples of the stress fixing member 4.

The thickness of the copper plate 1 in the stress absorption region G formed as described above is set to a thickness that can be deformed by the thermal stress applied to the obtained package. In general,
The thickness of the copper plate 1 in the stress absorption region G is 0.05
It is preferable to set to 1.1 mm. That is, when the thickness exceeds 1.1 mm, the amount of deformation of the stress absorption region G becomes small, but the entire package is warped, and the ceramic frame is likely to be cracked or chipped. Also,
When the thickness is less than 0.05 mm, the function of the stress absorption region G is sufficiently exerted, and the warp of the package and the cracks and chips of the ceramic frame body are eliminated, but as shown in FIG. The height h of the unevenness caused by the deformation of the copper plate in the region G may be 30 to 50 μm, which is larger than the plate thickness, which is a problem when the copper plate is required to have flatness, and the sealing property of the package It has an adverse effect on long-term reliability. More preferably, the thickness of the copper plate in the stress absorption region G is 0.1 mm to 0.8 mm.

The width of the stress absorbing region G formed in the copper plate 1 may be determined as appropriate depending on the thickness of the copper plate in that portion, the area of the bottom surface of the cavity, and the like so that the stress in the package can be absorbed.

Further, as described above, in the mode in which the stress absorbing region G is formed by providing the stress fixing member 4 for suppressing the deformation of the copper plate in the central portion of the copper plate 1 forming the bottom surface of the cavity, the stress fixing member is formed. When the coefficient of thermal expansion of 4 is the same as or smaller than the coefficient of expansion of the ceramic frame body 2, the stress fixing member 4 and the ceramic frame body 2 are brought close to each other until almost contact with each other, and a stress absorption region G is formed between the members. However, when the coefficient of thermal expansion of the stress fixing member 4 is larger than that of the ceramic frame body 2, the above stress is applied so that at least an interval corresponding to the difference in thermal expansion of the stress fixing member can be secured. It is desirable to determine the width d of the absorption area.

However, in order to most effectively form the stress absorption region G, the distance d is 0.05 to
It is preferable to adjust to 4 mm, preferably 0.1 to 2.5 mm. That is, when the width d is smaller than 0.05 mm, it becomes difficult to sufficiently deform the copper plate, and when it is larger than 4 mm, the height h of the unevenness generated on the copper plate due to the absorption of thermal stress becomes large, and It may affect the accuracy.

In the embodiment in which the stress fixing member 4 is provided, its thickness may be determined by the thermal and mechanical characteristics of the member used and the thickness of the copper plate in the stress absorbing region G. That is, in addition to suppressing the uneven deformation of the copper plate as shown in F of FIG. 3 at the time of joining, when a material different from the copper plate is used as the stress fixing member, it is possible to prevent warpage due to a difference in coefficient of thermal expansion (warping of die attach) It is desirable to have a thickness of. For example, when the stress fixing member 4 is formed of a member different from the copper plate, when the thickness of the copper plate is 0.3 to 0.5 mm, if Mo is used for the stress fixing member 4, the deformation of the copper plate is suppressed,
Mo is 0.3m to reduce the warp of the die attach.
A thickness of m or more is preferable. The upper limit thickness may be determined within a range having a function as a semiconductor element mounting package, that is, at least less than or equal to the total thickness of the package minus the thickness of the semiconductor element and the height of wire bonds.

When the stress fixing member 4 is made of the same material as the copper plate, the thickness (t2-t1) of the stress fixing region E is the thickness of the copper plate of the stress absorbing region G, as shown in FIG. 5 (C). It may be decided depending on the size. Specifically, the thickness is preferably twice or more the thickness (t1) of the copper plate in the stress absorption region G. The upper limit of the thickness is as described above.

As described above, when the same copper is used as the stress fixing member, the semiconductor element mounted on the die attach has a difference in thermal expansion coefficient between copper and the semiconductor element of several meters.
It is possible to mount an object with a size of m square to 10 mm square without any problem. In addition, when mounting a large-area semiconductor element,
As shown in (B), another material capable of matching the coefficient of thermal expansion with the semiconductor element, such as Mo or W plate, can be bonded and the semiconductor element can be mounted thereon.

Further, the stress absorption region G shown in FIG.
In the above-mentioned formation mode, the thickness of the copper plate at the portion where the ceramic frame 2 and the copper plate are joined can be made equal to that of the stress fixing member 4. In this case, a groove is formed only in the portion to be the stress absorption region G of the thick copper plate.

Further, in the present invention, if necessary, the height h of the unevenness of the copper plate (hereinafter referred to as the unevenness h of the copper plate) generated in the stress absorption region G is reduced by grinding or polishing to form the convex portion. It is also possible to remove some or all of them to improve the flatness of the copper plate.

Further, in order to enhance the heat radiation effect of the package, although not shown in the figure, it is also possible to attach a fin-shaped radiator or the like to the copper plate via an adhesive such as silver epoxy or a heat conductive organic substance. is there.

In the above aspect, it is desirable that the radiator is provided so as not to interfere with the action of the stress absorption region G.

As a typical method of manufacturing the semiconductor element mounting package of the present invention, for example, P having a frame structure is used.
In the case of a ceramic package such as GA, a brazing material (for example, BAg-8 or Cu of JIS standard of 20 to 70% by weight, Ag of 30 to 70% by weight, Ti of 30% to 70% by weight) is provided between the ceramic frame and the copper plate and between the stress fixing member 4 and the copper plate. 5-20% by weight
The active metal brazing material containing) is arranged as shown in FIG. At this time, in order to enhance the bondability with the brazing material, the bonding surface of the ceramic frame body of the PGA package should have W, Mo, A
Metallization containing u, Ag or Cu as a main component may be applied. The form of the brazing material is not particularly limited, and a foil form, a paste form, a powder form or the like can be used without any problem. Further, the amount of brazing material (thickness, area, etc.) may be appropriately determined depending on the joint area between the copper plate and the ceramic frame and the size of the stress fixing member 4. Next, 1 for the ceramic frame part and the stress fixing member 4.
Apply a load of 0 to 100 g / cm ² in vacuum (10 ^-1 P
a or less) or in an inert atmosphere such as nitrogen gas or argon gas at 750 to 950 ° C. for 10 to 60 minutes. The brazing material forms a liquid phase at a high temperature and spreads on the joint surface.
Then, the brazing material is solidified with cooling, and the ceramic frame and the copper plate are joined, and during this joining and cooling process, thermal stress is absorbed by the deformation of the stress absorbing region G formed on the peripheral edge of the copper plate forming the bottom surface of the cavity. It The deformation of the stress absorbing region absorbs the thermal stress even in the subsequent thermal shock, and effectively prevents the warp of the package and the cracking of the ceramic frame.

The brazing of the lead pins for inputting and outputting the electric signals is carried out at the same time as the joining of the copper plate and the stress fixing member 4 and the copper plate,
It can be performed after joining the stress fixing member 4. After that, fix the semiconductor element in the package cavity by die attachment, wire bond the semiconductor element and the electrode of the signal pattern formed on the inner and outer layers of the package, and then attach the cap if necessary to mount the semiconductor element. Package is manufactured.

The cap has the same structure as that of a known mounting package for semiconductor elements without particular limitation.
Pre-apply a Sn-based eutectic brazing material preform or an organic sealing material such as epoxy resin on the joint surface of the cap,
The encapsulant is cured by light irradiation or heating to join.
Examples of the main component of the cap include metals such as Kovar and 42 alloy, and ceramics such as alumina, aluminum nitride, mullite, and silicon carbide.

[0051]

According to the semiconductor element mounting package of the present invention, due to the stress caused by the difference in thermal expansion coefficient between the ceramic frame and the heat sink, the ceramic frame is cracked or chipped, the entire package is warped, and the die attachment is warped. The copper plate can be used as a heat sink while avoiding problems such as adhesion when mounting semiconductor elements and adversely affecting the reliability of the package. Therefore, the high thermal conductivity of such copper can be directly used. As a result, the heat generated by the mounted semiconductor element can be dissipated very efficiently.

This sufficiently satisfies the requirement of heat dissipation in the ceramic packages such as alumina, which is widely used at present, accompanying the high integration of semiconductor elements to be mounted, and the degree of contribution in such a field. It can be said that it is remarkable.

Further, it can be said that the economical effect of the present invention is also very large in terms of the use of copper, which is a material having a relatively low cost and high workability.

[0054]

EXAMPLES Examples will be shown below for specifically explaining the present invention, but the present invention is not limited to the examples.

Example 1 A semiconductor element mounting package having the structure shown in FIG. 1A was manufactured as follows.

External dimensions 40.2 mm square, thickness 2.6 m
m is a co-fired multilayer package made of W metallized alumina having a 208-pin PGA type via hole, and is a ceramic frame body having a 20.5 mm square hole in the center. One surface of this ceramic frame, that is, the surface to which the copper plate is joined is metallized with nickel-plated W.

Separately, as the copper plate 1 (oxygen-free copper), the thicknesses of 0.1 mm, 0.3 mm, 0.6 mm, and 0.8 mm were used.
The types (all sizes are 35.0 mm square), and the stress fixing member 4 was prepared as a nickel-plated Mo plate having a thickness of 1.0 mm and a size of 19.5 mm square. The ceramic frame, the copper plate and the Mo plate were arranged as shown in FIG. 1, and eutectic silver brazing (BAg-8) was used to heat them in nitrogen at 800 ° C. for 10 minutes to bond the copper plates with various thicknesses to Mo. Got the package. The surface of the Mo stress fixing member that is not joined to the copper plate is used as a die attach. The gap d is 0.5
mm. Also, one side of this package has 20
Eight lead pins were brazed. The brazing of the pins can be carried out either at the same time as the copper plate-Mo plate bonding or after the copper plate-Mo plate bonding. Next, Ni is used for the W metallized portion, copper, Mo and lead pins of this package.
(Thickness 3 μm) Base-Au (1.5 μm) was plated to obtain a semiconductor element mounting package. Table 1 shows the relationship between the thickness of the copper plate, the warp of the die attachment, and the unevenness h of the copper plate. In addition, the warp of the die attach and the unevenness h of the copper plate in Table 1 are measured values in the package before brazing the lead pin and before applying Ni—Au plating (only the ceramic frame and the copper plate and the Mo plate are joined). is there.

[0058]

[Table 1]

When the thickness of the copper plate in the stress absorption region is too thin, the unevenness h of the copper plate tends to increase,
Further, it was confirmed that when the thickness of the copper plate is increased, the unevenness h of the copper plate can be suppressed to be small, but the warp of the die attach tends to be increased. This is because as the copper plate becomes thicker, the thermal stress due to the difference in thermal expansion coefficient between the copper plate and the Mo plate increases, and deformation due to thermal stress cannot be prevented by the Mo-made stress fixing member 4, resulting in warping of the die attach. It can be inferred that it was done.

Further, in the visual observation immediately after the production, in the package in which the stress fixing region of the present invention was formed, the generation of cracks in the ceramic frame did not exist.
When the copper plate became too thick, cracks occurred in the ceramic frame.

Table 2 shows the results of measuring the thermal resistance of the product of the present invention and the conventionally used package. The thermal resistance was evaluated by bonding a 18.5 mm square heater chip made of AlN with an Au-Si brazing material on the stress fixing member 4 and setting the power consumption to 3 W. The numerical value of the thermal resistance is expressed as a value (θj-a) obtained by dividing the temperature difference between the temperature on the heater chip and the ambient atmosphere by the power consumption.

[0062]

[Table 2]

It can be seen that the product of the present invention has excellent heat dissipation characteristics because the copper plate itself is directly used as compared with the conventionally used package with Cu-W heat sink. In addition,
The sizes of the alumina PGA package and the alumina package with the Cu—W heat sink used for comparison are 40.2 mm square and 2.6 mm thick as in the case of the product of the present invention.

Further, the above-mentioned package of the present invention (excluding samples 1 and 6) was subjected to thermal shock under the conditions of holding time at -65 ° C. and 150 ° C. for 10 minutes and moving time from −65 ° C. to 150 ° C. for 10 seconds. After carrying out the test for 1000 cycles, the sealing property was tested. As a result, there was no occurrence of fine leak due to warpage. In addition, no cracks occurred in the ceramic frame.

Example 2 In Example 1, the thickness of the copper plate was fixed to 0.5 mm, and only the thickness of the Mo stress fixing member 4 was 0.5 to 1.2.
The semiconductor element mounting package was obtained in the same manner as in Example 1 except that the thickness was varied within the range of mm. Table 3 shows the results of evaluating the relationship between the thickness of the copper plate, the warp of the diamond plate, and the unevenness h on the back surface of the copper plate, as in Example 1.

The measured values in Table 3 are the same as those in Table 1 before the lead pin brazing and before the Ni-Au plating.

[0067]

[Table 3]

When the stress fixing member 4 is not provided, the copper plate (0.5
It can be understood that the thermal deformation of (mm) cannot be suppressed, the stress absorption region G is not formed on the peripheral edge of the copper plate forming the bottom surface of the cavity, and as a result, the warp of the die attach becomes large.

In addition, the warp of die attachment and the unevenness h of the copper plate
Does not change when the thickness of the stress fixing member is 2 mm or more.

Further, the package of the present invention is -6
A thermal shock test was conducted under the conditions of holding time at 5 ° C and 150 ° C for 10 minutes and moving time from -65 ° C to 150 ° C for 10 seconds.
After carrying out 000 cycles, as a result of testing the sealing property, no fine leak was generated due to warpage. In addition, no cracks occurred in the ceramic frame.

Example 3 In Example 1, the size of the gap d between the stress fixing member 4 and the ceramic frame was changed by changing the size of the stress fixing member 4, and the other conditions were the same as those in Example 1. Similarly, a semiconductor element mounting package was obtained. Table 4 shows the results of evaluating the relationship between the gap d and the unevenness h on the back surface of the copper plate.
When the gap d becomes too large, the unevenness h on the back surface of the copper plate increases,
The function of the stress absorption region G is sufficiently exerted, but the unevenness h
Becomes larger and the flatness of the back surface of the heat sink tends to decrease. The warp of the die attach was 10 to 20 μm in this example.

[0072]

[Table 4]

Further, the package of the present invention is -6
A thermal shock test was conducted under the conditions of holding time at 5 ° C and 150 ° C for 10 minutes and moving time from -65 ° C to 150 ° C for 10 seconds.
After carrying out 000 cycles, as a result of testing the sealing property, no fine leak was generated due to warpage. In addition, no cracks occurred in the ceramic frame.

As described above, the material and size of the stress fixing member 4, the thickness of the copper plate, etc. are not limited to those in the above embodiment, but can be set appropriately according to the thermal design of the package and the like.

Example 4 A semiconductor element mounting package having the structure shown in FIG. 4 was manufactured as follows.

The ceramic frame is made of black 90% alumina, and has an outer diameter of 39.2 mm and a thickness of 0.635 mm.
Alumina-based ceramic frame 2-1 with no through-hole of 2.3 mm square, with the same external dimensions and thickness of 1.5
An alumina ceramic frame 2-2 having a diameter of 2 mm and a hole of 20.5 mm square was prepared in the center. 40% by weight of Ag, 55% by weight of Cu, and 5% by weight of Ti of active metal brazing material paste were applied in a thickness of 40 μm on both surfaces of the ceramic frame 2-1 and one surface of 2-2. Separately, the outer shape is 38.8 mm
A copper foil having a corner, a thickness of 150 μm, a hole in the center, and external leads on the outer periphery was prepared. Regarding the size of the hole in the center of the copper foil, one is 23.3 mm square and the other is 21.5 mm.
It is a horn. The external lead had a width of 0.3 mm, and the number of external leads was 32 on each of the four sides.

Separately, as in Example 1, the thickness of the copper plate (oxygen-free copper) was 0.04 mm, 0.1 mm, 0.3.
6 types of mm, 0.6 mm, 0.8 mm and 1.2 mm (all sizes are 38.0 mm square), and the stress fixing member 4 is a Mo plate having a thickness of 1.0 mm and a size of 19.5 mm. I prepared. One surface of the copper plate is joined to the stress fixing member 4,
Further, the same active metal brazing material as described above was applied for joining the alumina frame. The alumina frame, the copper foil, the copper plate, and the stress fixing member 4 were stacked as shown in FIG. 4, and then heated in vacuum at 860 ° C. for 20 minutes to obtain a semiconductor element mounting package.

Thereafter, as in Example 1, warpage of die attach, unevenness h of the copper plate, thermal resistance of the package, sealing property, etc. were evaluated.

Also, as in Example 1, it was confirmed that the warp of the die attach and the unevenness of the copper plate were small, cracks were hardly generated in the ceramic frame due to the thermal cycle during and after the production, and the sealing property was good. Was done. Also, the thermal resistance
Similar to Example 1, extremely good results due to copper were shown.

Example 5 In Example 1, the stress fixing member 4 was made of W, Mo, Cu--.
W (10% Cu-90% W and 20% Cu-80%
W), Cu-Mo (30 to 70% Cu-remaining Mo), C
u-Mo-Cu clad material (weight ratio 1: 1: 1), A
1N, BeO, SiC and for mounting semiconductor elements in which different stress fixing members are joined in the same manner as in Example 1 with respect to the thickness and size of the stress fixing member 4, the thickness range of the copper plate, etc. Got the package. Thereafter, in the same manner as in Example 1, the unevenness h of the copper plate, the sealing property, the thermal resistance of the package, and the like were evaluated.

Also, as in Example 1, it was confirmed that the warp of the die attach and the unevenness of the copper plate were small, almost no cracks were generated in the ceramic frame due to the heat cycle during and after the production, and the sealing property was also good. Was done. Also, the thermal resistance
Similar to Example 1, extremely good results due to copper were shown.

Example 6 The stress fixing member 4 has a thickness of 1.5 mm and a size of 19.5 mm.
A package was obtained in the same manner as in Example 1 except that the corner was changed to AlN (thermal conductivity 180 W / K · m). Thereafter, similarly to Example 1, the warp of the die attach, the unevenness h of the copper plate and the sealing property were evaluated. Results similar to those of Sample 4 of Example 1 were obtained. Table 5 shows the thermal resistance evaluation results of the package. It can be seen that the thermal resistance is lowered by using the stress fixing member 4 having high thermal conductivity.

[0083]

[Table 5]

Example 7 A ceramic frame similar to that of Example 1 was used as a stress fixing member 4 as shown in FIG. 5 (C). They were joined together to produce the package shown in FIG. Where t1 = 1.5m
m, t2 = 0.4 mm, a = 19.5 mm square, b = 35
The mm square and the gap d are 0.5 mm. t1 is the thickness of the stress fixing region E, and t2 is the thickness of the stress absorbing region G.

Therefore, in this example, the stress fixing member in the stress fixing region E is made of copper.

Then, with respect to the above-mentioned package, the warp of die attachment, the unevenness h of the copper plate and the thermal resistance of the package were evaluated in the same manner as in Example 1. Table 6 shows the evaluation results.

[0087]

[Table 6]

Further, in order to match the thermal expansion with the semiconductor element, Ni is plated on the copper in the stress fixing region as shown in FIG. 5B to have a thickness of 0.2 mm and a size of 19.5 m.
Table 6 also shows the results of the brazing of m square Mo plates with silver brazing.
It was shown to.

In this case, even if Mo was brazed onto the stress fixing member, no problem occurred in the performance of the package.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing a typical aspect of a semiconductor device package of the present invention, a plan view and a sectional view schematically showing a deformed state of a stress absorption region.

FIG. 2 is a schematic sectional view of an example of a conventional ceramic package using Cu-W as a heat sink.

FIG. 3 is a schematic sectional view showing a comparative example in which only a copper plate is joined to a ceramic frame body.

FIG. 4 is a schematic sectional view of an example of a semiconductor element mounting package of the present invention.

FIG. 5 is a cross-sectional view schematically showing another aspect of the semiconductor element package of the present invention (including a cross-sectional view showing dimensions of each part of the copper plate).

[Explanation of symbols]

 1 Copper Plate 2 Ceramic Frame 2-1 Ceramic Frame (Flat Frame) 2-2 Ceramic Frame (Flat Frame) 3-1 Adhesive 3-2 Adhesive 4 Stress Fixing Member 5 Semiconductor Element 6 Metal Plate (Heat Sink) 7 Cavity 8 Power supply lead 9 Grounding lead 10 Signal lead 11 Lead fixing glass G Stress absorption area d Gap between ceramic frame and stress fixing member h Concavity and convexity of copper plate in stress absorption area D Semiconductor mounting part (die attach)

Claims (3)

[Claims] 1. A package in which a copper plate is bonded to one surface of a ceramic frame body to form a cavity, and stress caused by a difference in thermal expansion coefficient between the ceramic frame body and the copper plate is absorbed by deformation of the copper plate. A semiconductor element mounting package, wherein the stress absorbing region is formed on the peripheral edge of a copper plate forming the bottom surface of the cavity. 2. A stress fixing member is joined to the central portion of a copper plate forming the bottom surface of the cavity with a gap between the inner wall of the ceramic frame and the inner wall of the ceramic frame, so that the stress fixing member and the ceramic frame are positioned in the gap. The semiconductor element mounting package according to claim 1, wherein the stress absorbing region is formed in the copper plate portion. 3. The thickness of the copper plate in the stress absorbing region is 50 to 50.
The semiconductor element mounting package according to claim 1, which has a thickness of 1100 μm.