JPH06275733A - Ceramic lid for semiconductor package - Google Patents

Abstract

PURPOSE:To prevent scattering of melted solder, generation of void in the step of soldering a lid. CONSTITUTION:A groove 5 for holding flow of gas between an interior and an exterior of a package is provided on a solder layer 4 of a lid 1 when a package body 11 is covered with the lid 1. The sectional area of the groove 5 is gradually increased from inside to outside of the lead 1 in the case of W1>W2 of its width. Since gas in the package to be expanded in a soldering step is externally discharged from the groove 5, an increase in an inner pressure is prevented, and scattering of the solder is eliminated. Since the groove 5 is fill with the melted solder from narrow inside of the width W2 to a wide outside of the width W2, gas is not enclosed in the step, and hence no void is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic lid for a semiconductor package, and more specifically, after a semiconductor element is housed inside a package body, the package body is covered with the semiconductor element by soldering, and then housed inside. The present invention relates to a ceramic lid (lid) for sealing a semiconductor element.

[Prior art]

A ceramic lid of this type (hereinafter, also simply referred to as "lid") is disclosed in JP-A-57-1601.
Techniques disclosed in Japanese Patent No. 47 and Japanese Patent Publication No. 3-76784 are known. In these techniques, FIG.
As shown in FIG. 0 (A), the lid 51 has a solder layer 54 formed flat on the periphery of the surface facing the package body 52 with a metallization layer 53 interposed therebetween. As shown, the solder layer 54 is covered so as to be in close contact with the metallized layer 55 of the package main body 52, and is then heated to a predetermined temperature to be melted and soldered (sealed). is there. By the way, when the solder is heated, it begins to melt at the solidus temperature and becomes a semi-molten state, and when it exceeds the liquidus temperature, it is completely melted. Therefore, the sealing in the above-mentioned conventional technique is performed at a temperature set a little higher than the liquidus temperature (hereinafter, "soldering temperature").
Alternatively, it is also referred to as “sealing temperature”).

[0003]

In this case, when the solder 54 of the lid 51 set in the package body 52 begins to melt above the solidus temperature, the solder simultaneously acts as a seal (sealing material). At that stage, the inside of the package becomes almost airtight. The package is then further heated under that condition to the sealing temperature.

Therefore, at the sealing temperature, the inside of the package has a relatively high pressure due to the thermal expansion of the gas, and the solder in the semi-molten or molten state is pushed outward (outside the package) to reduce the amount of the solder. Although there is some, it scatters to the outside and, as shown in FIG.
However, there is a problem in that they adhere to the outer leads 57 and the like. That is, when the above-mentioned conventional lid 51 is used, in the soldering process, a defective product having a serious defect such as a defective appearance or a failure in insulation and a function required for the package not being satisfied is likely to occur. As a result, there was a problem that the unit price of manufacturing was increased.

As a solution to this problem, as shown in FIGS. 11 and 12, the concave groove 6 is formed in the solder layer 64 on the periphery of the lid surface.
It is possible to propose a technique in which, when the lid 61 is covered with the package body (not shown), gas circulation is maintained inside and outside the lid body 5 and 65 when the lid body 61 is covered. By doing this, even when the solder begins to melt and becomes a semi-molten state, the inside of the package is not immediately closed, so expanded gas can be released to the outside,
Effective in preventing solder from scattering.

However, simply providing such a groove 65 does not completely fill the groove 65 with solder in the process of melting and sealing, so that it is likely to remain as a void and the package is sealed (sealed). ) There was a problem of poor sex. The cause is as follows. That is, FIG.
As shown in Nos. 0 and 11, meniscuses are formed on the outer (peripheral) side and the inner (peripheral) side of the metallized portion of the lid, and the amount of solder is relatively larger in that portion than in the flat portion. Therefore, when the solder begins to melt, the solder flows into the groove 65.
As shown in FIG. 5, the solder flows so that the outer side of the groove 65 starts to be filled and then closed, and then the inner side is filled and closed, so that the gas is surrounded by the solder at the intermediate portion of the groove 65 and the escape path is formed. Lost and remains.
For this reason, the solder does not flow and remains as a void V. Since the portion having the void V has a relatively small amount of solder with respect to the inside and outside of the package, the airtightness holding force is low, which causes the performance of the semiconductor device to be impaired.

Therefore, in this type of lid,
It is important to prevent the generation of voids as well as the prevention of solder scattering. By the way, in a large package, such a large influence on the yield, a ceramic lid is rarely used. Generally, a Kovar plate is plated with gold, and Au-
The reality is that an expensive one made by welding Sn preforms must be used. The present invention is
It is an object of the present invention to provide a lid capable of preventing the molten solder from scattering and generating voids in the lid soldering process.

[0008]

[Means for Solving the Problems] A first means for achieving the above object is a ceramic lid for sealing a package body containing a semiconductor by soldering and facing the package body. In which the solder layer is integrally provided on the periphery of the surface on the side where the lid is covered with the package body, the solder layer is provided with a groove for keeping the flow of gas inside and outside the package. The groove is provided so that the groove cross-sectional area gradually increases toward one of the inside and outside of the lid. In this case, as a mode of gradually increasing the groove cross-sectional area, the groove width or groove depth of the concave groove is changed, or
The groove width and the groove depth may be changed. Further, in these, the groove cross-sectional area can be large either inside or outside the lid.

Further, as a second means, there is provided a ceramic lid for sealing a package body containing a semiconductor by soldering, and a solder layer is integrally formed on the peripheral edge of the surface facing the package body. A groove for retaining gas flow inside and outside the package when the lid is covered on the package body, and the groove is cut off. The area is gradually increased from the central portion of the solder layer toward the inside and outside of the lid. Also,
Also in this case, as a mode in which the groove cross-sectional area is gradually increased, a method in which the groove width or the groove depth of the concave groove is changed, or both the groove width and the groove depth are changed can be mentioned.

[0010]

With the above structure, when the lid according to the present invention is used, the lid is covered on the package body,
Even when heating progresses to the solidus temperature in the reflow furnace, and even when the solder begins to melt and becomes a semi-molten state, the groove inside the solder layer immediately seals the inside of the package Never. Therefore, at this stage, the gas is in a state of circulating inside and outside, and the gas expanded inside is discharged outside. That is,
Unlike the conventional method, the inside of the package will not be sealed at the same time as the solidus temperature of the solder,
The temperature at which the internal and external gases are in a circulating state can be brought closer to the liquidus temperature of the solder. Therefore,
The internal high pressure is alleviated or prevented.

On the other hand, when the heating further progresses and the solder is completely melted in the vicinity of the sealing temperature, it flows into the groove. When flowing into the concave groove to fill the area evenly, first, the area of the concave groove having a small groove cross-sectional area, that is,
In the first means, the solder layer is filled from the inside or outside of the lid, and in the second means, it is filled from the central portion. Then, when the inside is placed in an airtight state, thereafter, the solder flows along the recessed groove so as to squeeze toward the side with a larger groove cross-sectional area and fills the whole. That is, the molten solder fills the concave groove with a flow property that does not easily surround the gas. Therefore, it is sealed without leaving a void. Thus, in the present invention, since the gas inside the package does not have a high pressure relative to the outside as in the conventional case, since there is no scattering of the solder in the soldering process and the occurrence of voids is prevented, Occurrence of the above-mentioned defects due to them is prevented.

[0012]

EXAMPLES Examples of the present invention will be described in detail below. First, an embodiment in which the first means is embodied will be described in detail with reference to FIGS. 1 to 3. In this example, the lid 1 is a ceramic substrate 2 (one side; about 20 mm, thickness; about 1 m) formed in a substantially square shape.
m) along the outer peripheral edge surface and side surface (finding) on one side,
A predetermined metallization layer 3 is provided in an annular shape, and a solder layer 4 is formed thereon. Four grooves 5 having a substantially rectangular cross section are formed in a notch shape so as to traverse the solder layer 4 inward and outward with respect to the approximate center of the solder layer 4 along each side of the lid 1. However, in this example, the groove cross-sectional area is the lid 1
The concave groove 5 is formed so that it gradually increases from the inner side U to the outer side S.
The groove widths W1 and W2 are linearly changed to have a trapezoidal shape in which the outer side W1 is widened in a plan view. On the other hand, the recessed groove 5 needs to have a size that does not fill up at least in the semi-molten state near the solidus temperature of the solder 4,
In addition, it is necessary to fill the void at the sealing temperature without leaving any void. In this example, the solder layer 4 has a thickness of 15
0 μm, the groove depth D is 50 to 75 μm, and the groove width is 5 mm on the outer side W1 and 1 mm on the inner side W2.
The width of the solder layer 4 is about 1.5 mm. By the way, the lid 1 of this example is formed by press molding by a known means.
A metallized layer 3 obtained by firing 0% alumina.
Screen prints the Ag-Pd paste, then
It is formed by firing.

The solder layer 4 is formed by immersing the substrate 2 in molten solder, selectively forming a base layer of the solder only on the metallized layer 3, and providing concave grooves 5 and 5 on the base layer. Then, the solder paste was screen-printed several times (twice) excluding the portion, passed through a reflow oven controlled to a predetermined temperature, and reflowed while maintaining the groove shape.
By solidifying (solidifying) as it is, the solder layer 4 having the concave grooves 5 and 5 is formed. The reflow temperature is in the range of the liquidus temperature or higher and the same temperature plus 10 ° C. or lower.
However, the composition of the solder used in this example is 85 Pb.
wt%, Sn 5 wt%, Bi 7 wt%, balance A
The solidus temperature is 240 ° C and the liquidus temperature is 280 ° C.

Incidentally, as a technique for providing the concave groove 5 in the solder layer 4 of the lid 1, various techniques other than the above-mentioned techniques can be cited. For example, a part of the flattened solder layer can be provided by cutting (grooving) or pressing in the next step into a desired groove shape. It is also possible to place a rod of stainless steel or ceramic on the solder layer that has been flattened by dipping or printing and reflow it, and let the rod bite into the solder, or reverse this (top and bottom). You can also reflow in the state. It can also be provided by melting a part of the solder layer with a hot knife, or by masking the portion where the groove is to be provided and dipping it in the molten solder. Further, by forming a groove on the surface of the lid substrate and providing a metallization layer and a solder layer having a constant thickness, the groove can be formed in the solder layer as a result.

Next, the operation and the like of the lid 1 of the present embodiment having the above-mentioned structure will be described. The solder layer 4 is the package body 11
It is heated to a predetermined temperature (300 ° C. in this example) in a reflow furnace (not shown) while being positioned and closely aligned so as to match the metallized layer 12 formed on the package body 11. , The solder layer 4 and the metallization layer 1 of the package body 11
A groove (escape) through which the gas inside and outside the package flows is formed between the groove 2 and the groove 2 (joint surface portion). As a result, the gas expanding in the package is
As shown by an arrow in the inside, it goes out through this groove 5. In this state, although the groove cross-sectional area (gas flow passage area) of the concave groove 5 is narrowed until the liquidus temperature is reached, the internal pressure rise can be suppressed to a low level. At the same time, when the solder is completely melted in the vicinity of the sealing temperature, as shown in FIGS. 3A to 3D, the groove width W1 is wide on the outer side so that it is not filled immediately and the inner side of the narrow groove width W2 is closed. Buried first. When the inner side is closed, the inner side is sealed, but after that, the waves flow toward the outside of the concave groove 5 in such a manner that waves wave, and the molten solder 4 does not surround the gas, Fill in.

Thus, when the liquidus temperature is exceeded, the solder is completely melted and the concave grooves 5 and 5 are closed, but the abnormal increase in internal pressure and the scattering of the solder as in the case of the conventional lid are prevented. Moreover, there is no void left. After that,
After cooling and solidifying the solder, a desired semiconductor package can be obtained. The specific effect of the lid 1 of this example will be described in more detail with reference to the test results of Table 1 in comparison with the comparative example. However, since solder scattering is not seen in any of the samples, the effect of reducing the occurrence rate (state) of voids will be mainly described below. Further, since the composition of the solder and the solder layer (thickness, width) are the same as those in this example, the description thereof will be omitted hereinafter, and the groove width and groove depth related to the groove cross-sectional area of the concave groove will be described. I will explain mainly. Table 1 shows a comparative example which is different from the lid 1 of the present example only in the groove width, and the result of the residual state of the voids confirmed by X-ray photography. However, the groove depth D of the concave groove is 50
˜75 μm. As shown in the results shown in Table 1, in the comparative example in which the groove width was constant (W1 = W2), 40 to 50% of voids were observed, whereas in this example, W1 (outer groove width)>
In the case of W2 (inner groove width), it was 0%. These facts at all prove the effect of the present invention.

[Table 1]

Also, the groove width, W1 based on the above embodiment is used.
In the case of> W2, in order to confirm the difference in the effect in more detail, W2 was set to 1 mm (constant) and W1 was changed in the range of 2 to 10 mm, and an experiment was conducted. However, the groove depth D of the concave groove is 50 to 75 μm. The results are shown in Table 2. From this result, W2 is 1
It is understood that when W is mm, W1 is preferably in the range of 3 to 7 mm. When W1 was 10 mm, it was found that the meniscus was small and the appearance was poor. Probably due to lack of solder volume.

[Table 2]

Further, in the groove width W1> W2 based on such an embodiment, in order to confirm the difference in the effect in more detail, the outer groove width W1 is set to 5 mm.
(Constant) and W2 was changed within a range of 0.5 to 4 mm, and an experiment was performed. The results are shown in Table 3. From this result, when W1 is 5 mm, W2 is 0.
It is understood that the range of 5 to 2 mm is preferable.

[Table 3] In the above embodiment in which W1> W2, the case where the groove width is linearly changed and the groove cross-sectional area is gradually increased has been described. However, as shown in FIGS. You can also let it.

Now, as another embodiment in which the first means is embodied, in the above embodiment, as shown by the two-dot chain line in FIG. 2, the groove width is W1 (outer side) <W2 (inner side). The case where the groove cross-sectional area of the concave groove is gradually increased from the outside to the inside of the lid will be described. However, it is basically the same as the above embodiment except that the groove widths inside and outside are reversed and the groove is filled from the outside, and therefore the case of sealing with this one is the same. ,
Only the results will be described with reference to Table 4. However, Table 4 shows that the outer groove width W1 is 1 mm (constant), the inner groove width W2 is in the range of 2 to 5 mm, and the groove width (groove cross-sectional area) is linear from the outer side to the inner side of the lid. It is when changing. However, the groove depth D of the concave groove is 50 to 75 μm. As shown in the results shown in Table 4, the occurrence rate of voids is inferior to that of the above-described embodiment in which the outer side is wide, but is smaller than that in Table 1 where the groove width is constant (W1 = W2).

[Table 4]

In each of the above-mentioned embodiments, the groove width of the concave groove is changed to gradually increase the groove cross-sectional area toward one of the inside and outside of the lid. With the width kept constant, as shown in FIGS. 5A and 5B, the groove depth of the concave groove is set to the outer groove depth D1 and the inner groove depth D2.
And D can be embodied by setting D1> D2 or vice versa, and although not shown, the groove width and the groove depth of the concave groove are, for example, groove width, W1> W2. , D1> D2, or vice versa, the groove cross-sectional area can be gradually increased.

Table 5 shows that, in FIG. 5A, the groove width of the concave groove formed in the solder layer of the lid is 1 mm (constant) and the inner groove depth D2 is 50 μm (constant). When the groove depth D1 is changed to 75 to 125 μm (D
1 shows the occurrence rate of voids of 1> D2). As shown in the table, the occurrence of voids is 0 to 20%, which is significantly lower than that of the comparative example, and its effect is proved. In this example, the process of filling the concave groove with the solder is substantially the same as the case of the above-described embodiment by changing the groove width.

[Table 5]

Further, Table 6 shows that the groove width of the concave groove provided in the solder layer of the lid is 1 mm (constant), and the outer groove depth D1.
Of 50 μm (constant), the inner groove depth D2
Is changed to 75 to 125 μm (D1 <D2)
5B shows the occurrence rate of voids, which is a concrete example of that in FIG. 5B. The occurrence rate of voids is larger than the result of Table 5, but is significantly lower than that of the comparative example.

[Table 6] As can be understood from this result, when gradually increasing the groove cross-sectional area toward one of the inner side and the outer side of the lid, it is effective to set it so that it is larger on the outer side.

Now, an embodiment in which the second means is embodied will be described in detail with reference to FIGS. 6 to 9.
However, the same parts as those of the above-mentioned first means are designated by the same reference numerals and the description thereof will be appropriately omitted. In this example,
When the solder layer 4 is viewed two-dimensionally, the groove width is set to W1 (outer side)> Wa (center) so that the recessed grooves 5 and 5 have a so-called hourglass shape.
<W2 (inside), and the melted solder fills the recessed groove 5 from the center toward the inside and outside of the lid 1 at the same time. That is, this is a case where a technique in which the groove cross-sectional area of the concave groove 5 is gradually increased from the central portion 5a of the concave groove 5 toward the inside and the outside is embodied. Then, when the package body is sealed with this example, when the solder 4 is completely melted, as shown in FIG.
As shown in D to D, the central portion Wa having a narrow groove width is first filled so as to be closed. As a result, the inside is sealed, but after that, it flows toward the inside and outside of the concave groove 5 and fills almost the whole. Thus, while preventing the solder from scattering due to the abnormal increase in the internal pressure, the groove 5 is closed without leaving a void. Wa, which is the narrowest part
Is preferably set in the center of the solder layer.

Regarding the lid of this example, W1, Wa, W2
The value (rate of occurrence of voids) was confirmed by appropriately changing the numerical value of. The results are shown in Table 7. However, the groove depth D of the concave groove is 50 to 75 μm. In this example, the occurrence rate of voids is 0 to 20%, and it has been proved that the effect is large.

[Table 7] Moreover, in these cases, as is clear from the relationship of the specific numerical values of W1> Wa <W2, when the groove depth is the same, the concave groove is more increased than in the case where the groove is gradually increased to one side at the same increasing rate. The space of 5 can be significantly reduced. Therefore, the volume of the solder that fills the groove 5 is less likely to be insufficient, and the occurrence of unfilled portions of the groove 5 is reduced accordingly, so that high sealing performance is expected.

FIG. 9 shows means for gradually increasing the groove cross-sectional area of the concave groove 5 from the central portion 5a of the concave groove 5 toward the inside and the outside.
The groove depth of the concave groove 5 is D1 (outside)> Da (center) <D2
(Inside), which can be called a modification of the technique shown in FIGS. Also in this case, the molten solder simultaneously fills the groove 5 from the center to the inside and outside. Table 8 shows that the groove width of the concave groove is set to 1 mm (constant) and the groove depth Da of the central portion 5a is set to 50 μm (constant), and the outer and inner groove depths D1 and D2 are changed to 75 to 125 μm. It shows the occurrence rate of voids in the case of making it. As shown in the table, the occurrence of voids is 0 to 25%, which is significantly lower than that of the comparative example, and the effect can be seen.

[Table 8] When the groove depth is D1> Da <D2, the groove width is W
1> Wa <W2, it is also effective to gradually increase the groove cross-sectional area from the center to the inside and outside. Even in these cases, the groove width or the groove depth can be changed stepwise or curvilinearly.

In each of the above embodiments, the groove cross section of the concave groove is rectangular, but the present invention is not limited to this. For example, an appropriate groove shape such as an arc shape or a V-shaped cross section can be used. Can be Any groove may be used as long as it keeps gas flow inside and outside the package when the lid is covered with the package body. That is, in the sealing process, it is sufficient that the gas passes through and is released to the outside, effectively preventing the internal high pressure. For the size of the groove width and the groove depth of the concave groove, that is, the groove cross-sectional area or the degree (proportion) of the gradual increase thereof, refer to the above-mentioned embodiment, and the type and size of the lid (package body). Alternatively, it is appropriately designed according to the composition of the solder and the like. Furthermore, in each case, the concave groove is illustrated as being provided so as to traverse it at the center of the side (solder layer) of the lid, but the location may be the corner portion of the lid, or the number thereof. May be set appropriately.

In the present invention, it can be said that the groove width and groove depth of the concave groove should be increased as much as possible in order to prevent the high pressure inside the package, but this is also the kind of the lid and the composition of the solder. It is a matter that should be appropriately designed according to the above. In the case of a solder having a composition with a large difference between the solidus temperature and the liquidus temperature, making the groove as large as possible is effective in preventing internal high pressure, while the solder with a composition with a smaller temperature difference has a concave shape. The height and width of the groove can be set small. In any case, set them as close as possible to the liquidus temperature and seal without leaving any voids. As the solder layer, in addition to the above Pb-Sn-based solder, Au
Depending on the type of the lid (package body), an appropriate Sn-based gold solder (gold low temperature brazing material) or the like can be used.

[0028]

As is apparent from the above description, the lid according to the present invention releases the gas inside the package from the groove when the package body is sealed, so that the internal pressure is increased and molten solder is melted. Not only is it effective in preventing the occurrence of scattering, but it is also very effective in preventing the occurrence of voids because the molten solder flows into the area in a manner that it is difficult to surround the gas in the process of filling the groove. That is, according to the lid of the present invention, not only the appearance defects and electrical insulation defects of the package are reduced, but also the high sealing performance is maintained because the number of voids is small, and the quality is improved and manufactured. The cost can be reduced.

Due to these effects, the ceramic cost is suitable for the lid of a large package which has been conventionally unsuitable.
A significant reduction is expected. In particular, in the technique in which the groove cross-sectional area of the groove is gradually increased from the center of the solder layer toward the inside and the outside of the lid, and the groove is filled from the center toward the inside and outside of the lid, the groove is directed toward one of the inside and outside of the lid. The space of the groove can be greatly reduced compared to the case of gradually increasing,
Insufficient solder volume is less likely to occur, and accordingly, it is expected that the unfilled portion of the concave groove can be reduced and high sealing performance can be obtained.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing the first means of a ceramic lid for a semiconductor package according to the present invention.

FIG. 2 is a plan view of the lid shown in FIG. 1 viewed from the solder layer side.

FIG. 3 is a partial plan view illustrating a process of filling a recessed groove when the lid of FIG. 1 is sealed.

FIG. 4 is a plan view of a groove portion for explaining another embodiment.

FIG. 5 is a vertical cross-sectional view of a concave groove portion for explaining an embodiment in which the groove depth of the concave groove is changed, in which A is D1> D2.
B is a diagram in which D1 <D2.

FIG. 6 is a partially cutaway front view showing a second embodiment of the ceramic lid for a semiconductor package according to the present invention.

FIG. 7 is a plan view of the lid shown in FIG. 6 viewed from the solder layer side.

FIG. 8 is a partial plan view illustrating a process of filling the concave groove when the lid of FIG. 6 is sealed.

FIG. 9 is an enlarged vertical cross-sectional view of a groove portion illustrating an embodiment in which the depth of the groove is changed to D1> Da <D2.

10A and 10B are views for explaining a conventional lid, in which A is a partial cross-sectional view showing a state in which the lid is put on the package body, and B is a scattered state of solder after the package is sealed by soldering. It is a fragmentary sectional view explaining.

FIG. 11 is a partially cutaway front view illustrating a technique of improving the conventional lid to prevent solder from scattering.

12 is a plan view of the lid shown in FIG. 11 viewed from the solder layer side.

FIG. 13 is a partial plan view illustrating a process of filling the concave groove and a process of generating a void when the lid is sealed by the lid shown in FIG.

[Explanation of symbols]

 1 lid 2 lid ceramic substrate 3 metallization layer 4 solder layer 5 solder layer groove 11 package body W1 outer groove width Wa central groove width W2 inner groove width D1 outer groove depth Da central groove Depth D2 Inner groove depth

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukihiro Aoyama 14-18 Takatsuji-cho, Mizuho-ku, Nagoya City Nippon Special Ceramics Co., Ltd.

Claims (10)

[Claims] 1. A ceramic lid for sealing a package body containing a semiconductor by soldering, wherein a solder layer is integrally provided on a peripheral edge of a surface facing the package body. , When the lid is covered on the package body, the solder layer is provided with a concave groove for keeping the gas flow inside and outside the package, and the concave groove has a groove cross-sectional area of the inside and outside of the lid. A ceramic lid for a semiconductor package, which is gradually increased toward one side. 2. The ceramic lid for a semiconductor package according to claim 1, wherein the groove width of the concave groove is changed to gradually increase the groove cross-sectional area. 3. The ceramic lid for a semiconductor package according to claim 1, wherein the groove depth of the groove is changed to gradually increase the groove cross-sectional area. 4. The ceramic lid for a semiconductor package according to claim 1, wherein the groove width and the groove depth of the concave groove are changed to gradually increase the groove cross-sectional area. 5. The ceramic lid for a semiconductor package according to claim 1, 2, 3 or 4, wherein the groove cross-sectional area is larger on the outer side than on the inner side of the lid. 6. The ceramic lid for a semiconductor package according to claim 1, 2, 3 or 4, wherein the groove cross-sectional area is larger on the inside than on the outside of the lid. 7. A ceramic lid for sealing a package body containing a semiconductor by soldering, wherein a solder layer is integrally provided on a peripheral edge of a surface facing the package body. , When the lid is covered on the package body, a groove is provided in the solder layer inside and outside of the package for keeping gas flow, and the groove has a groove cross-sectional area of the solder layer. A ceramic lid for a semiconductor package, which gradually increases from the center to the inside and outside of the lid. 8. The ceramic lid for a semiconductor package according to claim 7, wherein the groove width of the concave groove is changed to gradually increase the groove cross-sectional area. 9. The ceramic lid for a semiconductor package according to claim 7, wherein the groove depth of the groove is changed to gradually increase the groove cross-sectional area. 10. The ceramic lid for a semiconductor package according to claim 7, wherein the groove width and the groove depth of the concave groove are changed to gradually increase the groove cross-sectional area.