JPH08213501A - Ceramic package base, method for manufacturing the same, and method for manufacturing ceramic package - Google Patents

Abstract

(57) [Summary] [Structure] In a ceramic package base 11 provided with a cavity 13 for housing a semiconductor element and a rectangular metallization layer for solder sealing around the cavity 13, one side of the metallization layer is provided. Regarding the vertical cross-sectional shape including
The laminated portion near the cavity 13 is warped in a concave shape,
A package substrate in which the other outer peripheral laminated portions are warped in an inverted concave shape. [Effect] Package base 1 with ceramic lid
A through hole for removing gas inside the cavity is surely formed between the fluidized solder layer and the package base when sealing the liquid crystal layer 1, and the gas pressure inside the cavity is increased during sealing by the fluidized solder layer. It is possible to prevent the occurrence of splatter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic package base, a method of manufacturing the same, and a method of manufacturing the ceramic package. More specifically, the present invention relates to a ceramic package capable of mounting semiconductor elements such as IC chips and LSI chips. TECHNICAL FIELD The present invention relates to a package base, a manufacturing method thereof, and a manufacturing method of a ceramic package.

[0002]

2. Description of the Related Art In a semiconductor device, a semiconductor element such as an integrated circuit is housed in a semiconductor element mounting portion provided on a package base, and the semiconductor element mounting portion is hermetically sealed with a lid for practical use. There is. Since ceramics such as alumina are excellent in heat resistance, durability, reliability, etc., they are suitable as materials for the package base and lid, and IC packages made of ceramics are now actively used.

FIG. 8 is a sectional view schematically showing a semiconductor device in which a ceramic package base housing a semiconductor element and a ceramic lid are joined via a solder layer.

A cavity portion 36 is formed in the center of a package base 31 constituting the semiconductor device, and a metallization layer (seal ring) 40 used for sealing the lid 32 is formed around the cavity portion 36, and further metallized. External connection pins 41 for connecting to a mother board (not shown) are set up around the layer 40. Further, the cavity portion 36 is usually formed in a stepped shape in its peripheral portion, a pad portion 39 for wire bonding is formed in the middle stepped portion, and a semiconductor element mounting device for mounting an LSI or the like is mounted on the bottom surface portion. The part 37 is formed. On the other hand, the lid 32 constituting the semiconductor device is a ceramic substrate 3
3, a metallization layer 34 formed on the peripheral portion (outer peripheral portion of the lower surface and side surfaces), and a solder layer 35 covering the metallization layer 34. Then, the package base 31 and the lid 32 are joined by the solder layer 35 via the metallized layer 40 formed on the package base 31 and the metallized layer 34 formed on the lid 32, and the semiconductor element 38 is hermetically sealed. ing.

The ceramic package base 31 constituting this semiconductor device is manufactured by stacking and firing green sheets on which conductive paste is printed at predetermined positions. It is difficult to make the package base 31 manufactured by the above method into a perfect flat plate shape, and some warpage is usually observed.

FIG. 9 is a cross-sectional view schematically showing a ceramic package base in which green sheets printed with a conductive paste are stacked and fired as they are using a normal paste, and a cavity 53 is formed in the center. Has been done. As shown in FIG. 9, the package base body 51 warps in a concave shape, and the vicinity of the end where the external connection pin 52 is erected greatly warps to a warpage of about 100 μm, which does not conform to the standard as a package base body.

Therefore, normally, appropriate weights are placed at the four corners of the green sheet laminate and firing is performed. FIG. 10 is a cross-sectional view schematically showing a package base manufactured using a weight. In this case, although the warping of both ends of the package base body 61 is suppressed, the central portion in which the cavity portion 63 is formed warps in an inverted concave shape, so that the solder sealing formed around the cavity portion 63 is not possible. Each side of the metallized layer (seal ring) 64 also warps in an inverted concave shape. Also, the warpage of the entire package base 61 is 50 μm.
It is quite large, about m.

[0008]

FIG. 11 (a) is a bottom view schematically showing a ceramic lid for sealing a package base, and FIG. 11 (b) shows the lid I shown in FIG. 11 (a). It is a -I line sectional view.

As shown in FIG. 11, the solder layer 35 formed on the metallized layer 34 of the ceramic lid 32 has a concave shape with a thin central portion. Therefore, when the package base on which the flat or concave metallization layer is formed is sealed using this lid 32,
The sealing by the solder layer 35 does not proceed at once, and a through hole for degassing remains in the central portion between the metallization layer and the solder layer 35 until just before the sealing is completed, and the cavity passes through this through hole. Internal gas escapes. Therefore, the splatter (the gas pressure inside the cavity becomes higher even after sealing and the gas blows through the solder layer than when using a lid on which the solder layer of the same thickness is formed, and therefore the molten solder is (Phenomenon of adhering to external pins) is unlikely to occur. However, when the metallized layer (seal ring) formed around the cavity of the package substrate has an inverted concave shape as shown in FIG. 10, the solder layer 35 formed on the lid 32 has a concave shape. However, since the gap between the metallized layer and the metallized layer becomes small, the through hole for degassing at the time of sealing is immediately closed, and it is difficult to completely degas, so that splatter is likely to occur.

In view of the above problems, the present inventors have conducted an examination for the purpose of manufacturing a package base body in which splatter is less likely to occur when a ceramic package base body is sealed with a ceramic lid. It was found that the warp of a ceramic package substrate manufactured can be adjusted by applying a conductive paste containing conductive metal particles having different particle diameters to a predetermined place of a predetermined green sheet, stacking and firing the paste. The present invention has been completed.

[0011]

In order to achieve the above object, a ceramic package base according to the present invention comprises a cavity for accommodating a semiconductor element and a rectangular metallized layer for solder sealing around the cavity. In a ceramic package base having:
Regarding the vertical cross-sectional shape including the sides, the laminated portion near the cavity is warped in a concave shape, and the other laminated portions in the outer peripheral portion are warped in an inverted concave shape (1).

Further, a method for manufacturing a ceramic package base according to the present invention is the same as the method for manufacturing a ceramic package base described in (1) above, in which a paste for forming a conductor pattern containing conductor metal particles is printed on a green sheet. In the method for manufacturing a ceramic package base body having a cavity for accommodating a semiconductor element by firing the laminated body, the conductive metal in the paste applied to at least one layer on the front surface side of the frame surrounding the cavity. As the particles, it is characterized that coarse conductor metal particles are used as compared with the conductor metal particles in the paste applied to the other lower layer (2).

The method for manufacturing a ceramic package base according to the present invention is the same as the method for manufacturing a ceramic package base described in (2) above, wherein at least one layer on the front surface side is the uppermost layer, and the metallization of the lower layer portion is performed. It is characterized in that the conductor metal particles in the paste used for forming the layer are fine particles, and the average particle diameter of the conductor metal particles is smaller in the outer peripheral portion than in the inner portion (3).

Further, in the method for manufacturing a ceramic package base according to the present invention, the metallization layer formed on the package base described in (1) above and the solder layer formed on the outer peripheral edge of the ceramic lid are superposed. It is characterized by heating together to melt the solder layer to hermetically seal the cavity (4).

[0015]

The warpage of the package substrate after firing is affected by the difference in shrinkage rate during firing between the green sheet and the paste containing the conductive metal particles printed on the green sheet.
The shrinkage rate of the paste during firing depends on the particle size of the conductive metal particles, and the shrinkage rate increases as the particle size decreases.

The warp of the package substrate can be adjusted by utilizing the fact that the shrinkage rate that occurs depends on the difference in the particle size of the conductive metal particles contained in the paste.

That is, at the time of stacking the green sheets in the manufacture of the package substrate, the particle size of the conductive metal particles in the paste to be printed on a predetermined green sheet forming the green sheet laminate is the same for each layer of the green sheet or the same. By changing the location of application of the green sheet, not only the warpage of the entire package substrate but also the warpage of each laminated portion of the package substrate can be adjusted.

The ceramic package substrate (1) according to the present invention is a ceramic package substrate provided with a cavity for accommodating a semiconductor element and a rectangular metallization layer for solder sealing around the cavity. Regarding the vertical cross-sectional shape including one side of the metallized layer, since the laminated portion near the cavity portion is warped in a concave shape and the other laminated portions in the outer peripheral portion are warped in an inverted concave shape, the package base is formed by a ceramic lid. At the time of sealing, a through hole for removing gas inside the cavity is easily formed between the fluidized solder layer and the package base, and the gas pressure inside the cavity is unlikely to be high at the time of sealing by the fluidized solder layer. Does not occur.

Further, according to the method (2) for manufacturing a ceramic package base according to the present invention, as the conductive metal particles in the paste applied to at least one layer on the front surface side of the frame part surrounding the cavity part, Since the coarse conductive metal particles are used as compared with the conductive metal particles in the paste applied to the lower layer, the package base according to the above (1) can be reliably manufactured, and the package base is formed by the ceramic lid. When sealing, the through-hole for venting the gas inside the cavity is surely formed between the fluidized solder layer and the package base, and the gas pressure inside the cavity becomes high during the sealing by the fluidized solder layer. Difficult and splatter does not occur.

Further, according to the method (3) for manufacturing a ceramic package base according to the present invention, at least one layer on the surface side is the uppermost layer, and the conductive metal particles in the paste used for forming the lower metallized layer. Are fine particles, and the average particle diameter of the conductive metal particles is smaller in the outer peripheral portion than in the inner portion, so that the warpage of the concave shape of the laminated portion including the metallized layer becomes more remarkable, and the package lid is formed by the ceramic lid. When sealing, the gas inside the cavity is more likely to escape, and the splatter generation rate is further reduced.

Further, according to the method (4) for manufacturing a ceramic package according to the present invention, the metallization layer formed on the package base according to the above (1) and the solder layer provided on the outer peripheral edge of the ceramic lid. And are superposed and heated, and the cavity is hermetically sealed by melting the solder layer, so that a ceramic package is manufactured without generating splatter.

In addition, the ceramic package substrate (1) according to the present invention or the ceramic package substrates (2) and (3) produced by the method of the present invention are metallized layers for semiconductor encapsulation around the cavity. Since the vicinity has a concave shape and the outer peripheral portion has a reverse concave shape, the warpage of the entire ceramic package substrate is reduced.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A ceramic package base and a method of manufacturing the same according to the present invention, a ceramic package using the package base and a method of manufacturing the same will be described below with reference to the drawings.

FIG. 1 is a sectional view schematically showing a ceramic substrate according to an embodiment. In this ceramic substrate 11, the central cavity portion 13 and the vicinity of the cavity portion 13 are warped in a concave shape, and conversely the external The portion of the surface where the connection pin 12 is erected is warped in an inverted concave shape (convex shape). The metallized layer (26 b in FIG. 4) is formed on the surface of the package base 11 and around the cavity 13. Therefore, the metallized layer also has a concave shape. As the ceramic lid, one having a thin solder layer 35 formed in the center as shown in FIG. 11 is used. When sealing is performed using this lid 32, the concave portion of the metallized layer and the solder layer are used. The concave portion of 35 will face in the opposite direction,
The sealing does not proceed at once, and a through hole for degassing remains in the central portion until just before the sealing is completed, and the gas in the cavity portion 13 can escape through the through hole. Therefore, compared to the case of using a lid on which a solder layer of the same thickness is formed, splatter, that is, gas escapes through the solder layer after sealing, and as a result, molten solder adheres to external pins, etc. Hard to occur. Next, a method of manufacturing the package base according to the embodiment will be described.

FIG. 2 is a cross-sectional view schematically showing a green sheet laminated body before firing which is used for manufacturing the package substrate according to the embodiment.

The green sheet laminate 20 is constructed by laminating six layers. These six layers are arranged from the bottom in order of the green sheet first layer 21 and the green sheet second layer.
The layers 22, the green sheet third layer 23, the green sheet fourth layer 24, the green sheet fifth layer 25, and the green sheet sixth layer 26 will be called. In the present embodiment, the green sheet second layer 22 in this green sheet laminate 20.
Unlike the conventional case (comparative example), the diameter of the particles in the paste printed on the green sheet sixth layer 26 is changed in various ways to change the warped state of the package substrate 11.

FIG. 3 is a plan view showing a print pattern of the paste formed on the second layer 22 of the green sheet. In this case, the outer print pattern 22a and the inner print pattern 22b are particles of W particles in the paste. Change the diameter.

Here, the definitions of coarse particles and fine particles are as follows. As the W particles, five kinds having different average particle diameters were used in Examples, and three kinds were similarly used in Comparative Examples. By determining the arithmetic mean from the average particle diameters of these 5 kinds of W particles or 3 kinds of W particles, the average particle diameter of the whole W particles to be used is determined, and those larger than the average particle diameter of the whole are coarse particles and small particles. Was defined as a fine grain. The average particle size of all W particles is
In Examples 1 and 2, 3.3 μm, and in Comparative Example, 3.4 μm
Is.

FIG. 4 is a plan view showing a print pattern of the paste formed on the green sheet sixth layer 26. In this case, the print pattern 26a of the pad for external connection pin on the outside and the solder seal on the inside are attached. With respect to the print pattern 26b for the metallized layer (seal ring) used, all W particles in the paste were coarse particles. The particle size of the W particles in the paste printed on the other green sheets 21, 23 ... Is the same as in the conventional case (comparative example).

Table 1 below shows the green sheet first layer 21.
~ The average particle size of W particles in the W paste to be printed on the green sheet sixth layer 26 is described.

[0031]

[Table 1]

As shown in Table 1, in Example 1, in the green sheet second layer 22, a paste containing W particles having a small average particle diameter of 2.5 μm was used for the outer print pattern 22a, and 2.7 in the print pattern 22b
μm and a paste containing W particles having an average particle diameter larger than that of the outside is used, while in the green sheet sixth layer 26,
Outer print pattern 26a, inner print pattern 22b
In both cases, a paste containing W particles having a large average particle diameter of 3.4 μm (coarse particles larger than the average particle diameter of the entire W particles used) is used.

In the second embodiment, the green sheet second
The layer 22 is printed with a paste containing fine W particles having a small average particle size of 2.5 μm, and the green sheet sixth layer 26 contains coarse W particles having a large average particle size of 3.4 μm. You are printing the paste.

After forming the green sheet laminate 20 according to Examples 1 and 2 and Comparative Example 1 as described above,
The package substrate 11 was manufactured by firing at 1560 ° C. for 2 hours in an N ₂ —H ₂ reducing gas atmosphere.
In addition, in the comparative example, 3.
Firing was performed by placing a weight composed of a 2 g Mo plate.

FIGS. 5, 6 and 7 show package bases 11 according to Example 1, Example 2 and Comparative Example 1, respectively.
6 is a graph showing the results of measuring the unevenness on the two sides of the metallization layer (seal ring) of the cavity portions 13 and 63 of 61.

As is apparent from FIGS. 5 to 7, the package base 11 of the embodiment has a concave metallization layer, while the package base 61 of the comparative example has a reverse metallization of the metallization layer. Alternatively, the package base 11 according to the embodiment has a corrugated shape, and splatter is less likely to occur during sealing with the lid.

In order to confirm this, the package substrate 1 according to the first embodiment, the second embodiment, and the first comparative example is actually used.
The lids 32 having the structure shown in FIG. 11 were used to seal Nos. 1 and 61, and the splatter generation rate was measured. The results are also shown in Table 1 above.

As is clear from Table 1 above, no splatter is generated when the package substrate 11 according to the embodiment is used, whereas splatter is generated when the package substrate 61 according to the comparative example is used. The rate was as high as 2%.

Further, the package substrate 11 obtained in each of Examples 1 and 2 has a small total warpage amount of 50 μm or less, which is 1/2 or less as compared with the conventional method using no weight. The warpage amount was equal to or less than that of Comparative Example 1 using

In the examples, W is used as the conductive metal particles.
Although particles are used, Mo particles or a mixture of Mo particles and W particles can also be used.

[0041]

As described above in detail, in the package substrate (1) according to the present invention, the cavity portion for housing the semiconductor element and the rectangular metallization layer for solder sealing are provided around the cavity portion. In the provided ceramic package base, with respect to the vertical cross-sectional shape including one side of the metallized layer, the cavity portion laminated portion is warped in a concave shape, and the other outer peripheral laminated portion is warped in an inverted concave shape. When sealing the package base with the ceramic lid, a through hole for removing gas inside the cavity is easily formed between the fluidized solder layer and the package base, and the inside of the cavity is sealed at the time of sealing with the fluidized solder layer. It is possible to prevent the gas pressure from rising and prevent the occurrence of splatter.

Further, in the method (2) for manufacturing a ceramic package base according to the present invention, the conductive metal particles in the paste to be applied to at least one layer on the front surface side of the frame portion surrounding the cavity, Since the conductor metal particles that are coarser than the conductor metal particles in the paste applied to the other lower layer are used, the package base according to the above (1) can be reliably manufactured, and the ceramic lid can be manufactured. When the package base is sealed by means of the above, a through hole for venting gas inside the cavity is surely formed between the solder layer and the package base, and the gas pressure inside the cavity is sealed at the time of sealing by the fluidized solder layer. It is possible to prevent the rise of splatter and to prevent the occurrence of splatter.

Further, in the method (3) for manufacturing a ceramic package base according to the present invention, at least one layer on the surface side is the uppermost layer, and the conductive metal in the paste used for forming the lower metallized layer. Since the particles are fine and the average particle diameter of the conductive metal particles is smaller in the outer peripheral portion than in the inner portion, the warpage of the concave shape of the laminated portion including the metallized layer becomes more remarkable, and the package made of the ceramic lid is used. When the substrate is sealed, the gas inside the cavity is more likely to escape, and the splatter generation rate can be further reduced.

Further, according to the method (4) for manufacturing a ceramic package according to the present invention, the metallization layer formed on the package base according to the above (1) and the solder layer provided on the outer peripheral edge of the ceramic lid. And are superposed and heated, and the cavity is hermetically sealed by melting the solder layer, so that a ceramic package can be manufactured without generating splatter.

In addition to the above, the ceramic package substrate (1) according to the present invention, the ceramic package substrates (2), (3) obtained by the method for producing a ceramic package substrate according to the present invention, and the ceramic according to the present invention. The ceramic package obtained by the method for manufacturing a package made of metal has a concave shape in the vicinity of the metallization layer for solder sealing around the cavity, and its outer periphery is warped in an inverted concave shape.
Even if a weight for preventing warpage is not used during firing, there is an advantage that the warpage of the ceramic package base and the entire ceramic package can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing a ceramic substrate according to an example.

FIG. 2 is a cross-sectional view schematically showing a green sheet laminate used for manufacturing a package base according to an example.

FIG. 3 is a plan view showing a print pattern of a paste formed on a second layer of a green sheet.

FIG. 4 is a plan view showing a print pattern of a paste formed on a sixth layer of a green sheet.

FIG. 5 is a graph showing the results of measuring the unevenness on the two sides of the metallized layer of the package base according to Example 1.

FIG. 6 is a graph showing a result of measuring unevenness on two sides of a metallized layer of a package base according to Example 2.

FIG. 7 is a graph showing a result of measuring unevenness on two sides of a metallization layer of a package base according to Comparative Example 1.

FIG. 8 is a cross-sectional view schematically showing a semiconductor device in which a ceramic package base housing a semiconductor element and a ceramic lid are joined via a solder layer.

FIG. 9 is a cross-sectional view schematically showing a ceramic package base body in which a green sheet on which a conductive pattern is printed using an ordinary paste is laminated and fired as it is.

FIG. 10 is a cross-sectional view that schematically shows a package substrate that is manufactured when appropriate weights are placed at the four corners of the green sheet laminate and firing is performed.

FIG. 11A is a plan view schematically showing a ceramic lid for sealing a package base,
(B) is a sectional view of the lid shown in (a) taken along line I-I.

[Explanation of symbols]

 11 Package Base 13 Cavity

Claims (4)

[Claims] 1. A ceramic package base comprising a cavity for accommodating a semiconductor element and a rectangular metallization layer for solder sealing around the cavity,
Regarding a vertical cross-sectional shape including one side of the metallized layer, the laminated portion near the cavity portion is warped in a concave shape, and the other outer peripheral laminated portions are warped in an inverted concave shape. . 2. A method for producing a ceramic package base body having a cavity for accommodating semiconductor elements by firing a laminate of green sheets on which a conductor pattern forming paste containing conductor metal particles is printed. As the conductive metal particles in the paste applied to at least one layer on the surface side of the frame portion surrounding the cavity, the conductive metal particles are coarser than the conductive metal particles in the paste applied to the other lower layer. 2. The method for manufacturing a ceramic package substrate according to claim 1, wherein: 3. At least one layer on the surface side is the uppermost layer, the conductive metal particles in the paste used for forming the lower metallized layer are fine particles, and the average particle diameter of the conductive metal particles is in the outer peripheral portion. 3. The method for manufacturing a ceramic package base according to claim 2, wherein the inner side is smaller than the inner side. 4. The metallized layer formed on the package base according to claim 1 and the solder layer formed on the outer peripheral edge of the ceramic lid are superposed and heated to melt the solder layer to form a cavity portion. A method for manufacturing a ceramic package, which comprises hermetically sealing a package.