JP4144826B2 - Seal ring for semiconductor device and method of manufacturing semiconductor device using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a seal ring for a semiconductor device for enabling a cap that covers a cavity upper surface of a semiconductor package made of ceramic containing a semiconductor chip to be accurately and airtightly brazed to a seal layer at a peripheral edge of an opening end of the cavity; The present invention relates to a method for manufacturing a semiconductor device formed using the seal ring.
[0002]
[Prior art]
A seal ring having a structure as shown in FIG. 7 is generally used as the seal ring.
In this seal ring, Ni strike plating (not shown) is applied to the base surface of the seal ring body 10 made of iron-nickel-cobalt alloy (Kovar) or iron-nickel alloy (42 alloy), and the Ni strike plating. A Cu plating 12 and an Ag plating 14 are sequentially applied to the seal ring body 10 subjected to the above. Ni strike plating is performed in order to improve the wettability with respect to the plating of the seal ring body 10 made of Kovar or 42 alloy. The Cu ring 12 can be reliably adhered to the seal ring body 10 on which the Ni strike plating has been applied without swelling.
[0003]
In this seal ring, when the seal ring is placed in a heating furnace and heated, the Cu plating 12 and the Ag plating 14 applied to the seal ring body 10 can be melted to form the silver braze 16. Then, using the silver brazing 16, as shown in FIG. 6, the seal ring body 10 can be brazed to the sealing layer 50 formed on the peripheral edge of the opening end of the cavity 44 of the semiconductor package 40 made of ceramic.
[0004]
Conventionally, a plate-like silver solder is interposed between the seal ring body 10 and the semiconductor package seal layer 50, or a silver solder paste is applied to the lower surface of the seal ring body 10 or the upper surface of the semiconductor package seal layer 50. For example, the seal ring body 10 is brazed to the seal layer 50 of the semiconductor package using the plate-like silver solder or silver solder paste.
[0005]
However, in such a case, the plate shape of the seal ring body 10 is more plate-like than the case of obtaining the silver brazing 16 for brazing the seal ring body 10 by applying the Cu plating 12 and the Ag plating 14 to the seal ring body 10 as described above. An operation of forming a silver braze, an operation of interposing the plate-like silver braze between the seal ring body 10 and the seal layer 50, an operation of applying a silver braze paste on the lower surface of the seal ring body 10, It took a lot of work and time to apply the silver solder paste on the upper surface of the seal layer 50.
[0006]
Therefore, in recent years, a method is often used in which the Cu-plating 12 and the Ag-plating 14 are sequentially applied to the seal ring main body 10 as described above, which is not troublesome, and the silver brazing 16 for brazing the seal ring main body 10 is obtained. ing.
A method of sequentially applying the Cu plating 12 and the Ag plating 14 to obtain the brazing silver 16 for brazing the seal ring main body 10 to the seal ring main body 10 is a seal ring for forming a recent ultra-small semiconductor device. It is particularly effective and widely used.
[0007]
[Problems to be solved by the invention]
However, in the above-described method of sequentially applying the Cu plating 12 and the Ag plating 14 to obtain the silver brazing 16 for brazing the seal ring body 10 to the seal ring body 10, the seal ring is heated in a heating furnace, When the silver plating 16 is formed by melting the Cu plating 12 and the Ag plating 14 applied to the seal ring main body 10, the silver brazing 16 is between the lower surface of the seal ring main body 10 and the upper surface of the seal layer 50. As shown in FIG. 8, many of the silver brazes 16 do not accurately penetrate or adhere to the side surface of the seal ring body 10 and the seal layer 50 so as to draw a meniscus. The cap 60 was attached to the top surface of the seal ring body 10 on which resistance welding was performed. A leak path (fine air flow passage) has been formed between the seal ring body 10 and the seal layer 50 to which the seal ring body 10 is brazed. And the airtightness of the cavity 44 of the semiconductor package inside the seal ring body 10 has been impaired.
[0008]
At the same time, as shown in FIG. 6, when a cap 60 made of Kovar or 42 alloy is resistance-welded to the upper surface of the seal ring body 10 by the seam weld method, a large amount attached to the upper surface of the seal ring body 10 is attached. Under the influence of the silver solder 16, the spark was not sufficiently generated between the cap 60 and the seal ring main body 10, and the cap 60 could not be accurately and airtightly joined to the upper surface of the seal ring main body 10.
Here, as described above, the reason why the cap 60 cannot be accurately resistance-welded to the upper surface of the seal ring body 10 is that the upper surface of the seal ring 10 is covered with the silver solder 16 having a low resistance value.
[0009]
The present invention is capable of solving such a problem. A seal ring for a semiconductor device (hereinafter referred to as a seal ring), a method for manufacturing a semiconductor device using the seal ring (hereinafter referred to as a method for manufacturing a semiconductor device), and The purpose is to provide.
[0010]
[Means for Solving the Problems]
To achieve the above object, shea Ruringu of the present invention, an iron - nickel - cobalt alloy or an iron - the underlying surface of the seal ring body made of nickel alloy, three or more layers alternately and Ag plating and Cu plating The plating is performed in order, and the innermost and outermost layers are subjected to Ag plating, and the thicknesses of the Ag plating and Cu plating are each formed to be 7 μm or less.
[0011]
A method of manufacturing a semiconductor device of the present invention using the sheet Ruringu of the present invention is characterized in that it comprises the following steps.
a. Shea Ruringu of the present invention, there is provided a seal layer comprising a metallized formed at the open end peripheral portion of the semiconductor package of the cavity, the step of placing the Ni plating decorated with sealing layer on its surface.
b. The semiconductor package on which the seal ring is mounted is heated in a reducing atmosphere to melt Ag plating and Cu plating applied to the seal ring body of the seal ring, and the seal ring body is sealed to the semiconductor package. The process of brazing the layer in an airtight manner.
c. A step of housing a semiconductor chip in a cavity of a semiconductor package to which a seal ring body is brazed, and electrically connecting an electrode of the semiconductor chip and a connection line of the semiconductor package.
d. Covering the upper surface of the cavity containing the semiconductor chip with a cap made of iron-nickel-cobalt alloy or iron-nickel alloy, and sealingly sealing the cap to the seal ring body by a seam weld method.
[0012]
In the method of manufacturing a semiconductor device using this shea Ruringu, Ag plating for silver solder formed which has been subjected to the seal ring main body and a Cu plating is thinner layer thickness of less 7 [mu] m.
Therefore, in the step b, when the seal ring is heated in a reducing atmosphere to melt the Ag plating and the Cu plating applied to the seal ring body, the Ag plating formed thinly to 7 μm or less It is possible to prevent the occurrence of a non-uniform portion in a molten state in the Cu plating. Then, the Ag plating and the Cu plating can be uniformly melted without generating unmelted portions. And when the seal ring body is brazed to the sealing layer of the semiconductor package using the silver brazing obtained by melting the Ag plating and the Cu plating, the silver brazing has a hole or a portion where the silver brazing is insufficiently adhered. Can be prevented from occurring. Then, it is possible to adhere the silver solder accurately and sufficiently so as to draw a meniscus over the side surface of the seal ring body and the seal layer. And it can prevent that a leak path (fine air flow passage) occurs between the seal ring body and the seal layer to which it is brazed.
[0013]
Further, Ni strike plating for improving the wettability of the seal ring body to the silver brazing is not performed on the base surface of the seal ring body.
Therefore, the wettability to the silver brazing on the upper surface of the seal ring body is reduced, and when the silver brazing is formed by melting Ag plating and Cu plating applied to the seal ring main body in the step b, It is possible to prevent most of the silver solder from crawling on the upper surface of the seal ring body and adhering to the upper surface of the seal ring body.
As a result, in the step d, the cap can be accurately resistance-welded by the seam weld method on the upper surface of the seal ring main body to which the silver solder is not adhered or the upper surface of the seal ring main body with a small amount of silver brazing.
[0014]
Further, in the method of manufacturing a semiconductor device using this seal ring, the adhesion between the seal ring body made of iron-nickel-cobalt alloy or iron-nickel alloy on the innermost base surface of the seal ring body Good Ag plating is applied.
Therefore, when Ag plating and Cu plating are sequentially applied to the base surface of the seal ring main body, the Ag plating and Cu plating adhere to the seal ring main body without causing blistering in the Ag plating or Cu plating. Can adhere well.
Further, the outermost side of the seal ring main body is subjected to Ag plating having good adhesion with Ni plating or the like.
Therefore, when Ni plating for exterior is applied to the seal ring body, the Ni plating for exterior is caused to bulge in the seal ring body through the Ag plating remaining on the outermost side of the seal ring body. It can be made to adhere with good adhesiveness.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a preferred embodiment of a seal ring different from the seal ring of the present invention, and FIG. 1 is a partially enlarged front sectional view thereof. The following is a description of this death Ruringu.
[0016]
In the illustrated seal ring, the seal ring body 10 is made of Kovar or 42 alloy. The seal ring body 10 has a rectangular frame shape.
The seal ring main body 10 is not subjected to Ni strike plating, and a Cu plating 12 and an Ag plating 14 are sequentially applied to the base surface of the seal ring main body 10 made of Kovar or 42 alloy.
[0017]
The Ag plating 14 and the Cu plating 12 are thinly formed with a layer thickness of 7 μm or less.
Specifically, the Cu plating 12 having a specific gravity of 8.96 is formed in a layer thickness of 3 μm, and the Ag plating 14 having a specific gravity of 10.49 is formed in a layer thickness of 6 μm.
When the silver plating 16 is formed by melting the Cu plating 12 and the Ag plating 14 applied to the seal ring body 10, the silver brazing 16 contains 28 wt% Cu and 72 wt% Ag. Including a low melting point eutectic silver solder.
Here, the reason why the Ag plating 14 and the Cu plating 12 are thinly formed to a layer thickness of 7 μm or less is based on the data obtained by the present inventors from the experimental results, and the Ag plating 14 and the Cu plating. 12 is thinly formed to a layer thickness of 7 μm or less, and when the seal ring body 10 to which the Ag plating 14 and the Cu plating 12 are applied is placed in a heating furnace and heated, the thin Ag plating 14 and This is because the Cu plating 12 can be uniformly melted so as not to generate unmelted portions.
[0018]
In this sheet Ruringu, convenience it is necessary to form the Ag plating 14 and the Cu plating 12 on the layer thickness of 7 [mu] m, small amount the amount of silver solder 16 be formed by melting the Ag plating 14 and the Cu plating 12 It will be limited.
Accordingly, sheet Ruringu This can be said to be suitable for small seal ring requires less amount of silver solder 16 of the seal ring main body 10 for brazing.
[0019]
Sheet Ruringu shown in FIG. 1 is configured as described above.
[0020]
Figure 2 shows a preferred embodiment of sheet Ruringu of the present invention, FIG. 2 is its is a partially enlarged front sectional view. The following is a description of this death Ruringu.
[0021]
In the figure sheet Ruringu, similarly to the seal ring shown in FIG. 1, the seal ring main body 10 is formed of Kovar or 42 alloy. The seal ring body 10 has a rectangular frame shape.
The seal ring body 10 is not subjected to Ni strike plating, and three or more layers of Ag plating 14 and Cu plating 12 are alternately formed on the base surface of the seal ring body 10 made of Kovar or 42 alloy (see FIG. Then, the three layers are applied in order. Of the Ag plating 14 and the Cu plating 12 that are alternately applied to the seal ring main body 10 in three or more layers, the Ag plating 14 is applied to the innermost side and the outermost side.
[0022]
The Ag plating 14 and the Cu plating 12 are thinly formed with a layer thickness of 7 μm or less.
Specifically, decorated with in such Resid Ruringu sequentially in three layers alternately and Ag plating 14 and the Cu plating 12 in FIG, Ag plating of the innermost and specific gravity applied to the outermost side 8.96 14 are formed in a layer thickness of 5.5 μm, respectively, and a Cu plating 12 having a specific gravity of 10.49 applied in the middle is formed in a layer thickness of 6 μm.
When the silver plating 16 is formed by melting the Cu plating 12 and the Ag plating 14 applied to the seal ring body 10, the silver brazing 16 contains 28 wt% Cu and 72 wt% Ag. Including a low melting point eutectic silver solder.
Here, the reason for the formed thin Ag plating 14 and the Cu plating 12 on the layer thickness of less 7μm is the same as the reason described in the explanation of the sheet Ruringu shown in FIG.
[0023]
Sheet Ruringu shown in Figure 2, is constructed as described above.
[0024]
Next, a preferred embodiment of the semiconductor device manufacturing method using the seal ring shown in FIG. 2 according to the present invention will be described with reference to the drawings.
[0025]
As shown in FIG. 3, the seal ring 100 shown in FIG. 2 is a wide rectangular ring-shaped seal layer 50 made of metallization formed at the peripheral edge of the opening end of the cavity 44 of the semiconductor package 40 made of ceramic. Then, it is placed on the seal layer 50 whose surface is plated with Ni. As the semiconductor package 40, for example, a package called a ceramic leadless chip carrier in which external leads are not extended to the periphery as shown in FIG. 3 is used.
Then, step a of the semiconductor device manufacturing method of the present invention is performed.
[0026]
Next, as shown in FIG. 4, the semiconductor package 40 on which the seal ring 100 is placed is placed in a heating furnace (not shown) held in a reducing atmosphere filled with N ₂ and H ₂ , and about Heated to 820 ° C. A silver brazing 16 is formed by melting the Ag plating 14 and the Cu plating 12 applied to the seal ring body 10 of the seal ring 100.
Then, the seal ring body 10 is air-tightly brazed to the seal layer 50 of the semiconductor package using the silver braze 16.
And b process of the manufacturing method of the semiconductor device of this invention is performed.
[0027]
Next, as shown in FIG. 5, the semiconductor chip 42 is accommodated in the cavity 44 of the semiconductor package to which the seal ring body 10 is brazed. Then, the electrode of the semiconductor chip 42 and the inner end of the connection line 46 exposed around the cavity 44 connected to the external connection terminal 47 formed on the peripheral side surface of the semiconductor package 40 are electrically connected via a wire 48 or the like. Connected.
And c process of the manufacturing method of the semiconductor device of this invention is performed.
[0028]
Thereafter, as shown in FIG. 5, the upper surface of the cavity 44 accommodating the semiconductor chip 42 is covered with a cap 60 made of iron-nickel-cobalt alloy (Kovar) or iron-nickel alloy (42 alloy). The cap 60 is hermetically resistance-welded to the seal ring body 10 by a seam weld method using a roller electrode.
And d process of the manufacturing method of the semiconductor device of this invention is performed.
[0029]
The method for manufacturing a semiconductor device according to the present invention includes the steps described above. According to the method for manufacturing a semiconductor device, a cavity 44, a seal layer 50, a seal ring body 10, and a cap 60 of the semiconductor package are formed around the semiconductor chip 42. And can be covered more airtight. A semiconductor device in which the semiconductor chip 42 is hermetically sealed in the cavity 44 of the semiconductor package can be manufactured.
[0030]
In the method of manufacturing a semiconductor device using this shea Ruringu, melted in the step b is heated to put the seal ring 100 in a heating furnace, and Ag plating 14 and the Cu plating 12 applied to the seal ring main body 10 In this case, it is possible to prevent the occurrence of non-uniform portions in the molten state in the Ag plating 14 and the Cu plating 12 that are thinly formed to 7 μm or less. And the Ag plating 14 and the Cu plating 12 can be uniformly melted without generating unmelted portions. Then, when the seal ring body 10 is brazed to the seal layer 50 of the semiconductor package using the silver brazing 16 obtained by melting the Ag plating 14 and the Cu plating 12, the silver brazing 16 has holes or silver spots. Generation | occurrence | production of the adhesion | attachment insufficient location of the wax 16 can be prevented. Then, the silver solder 16 can be accurately and sufficiently attached to the side surface of the seal ring body 10 and the seal layer 50 so as to draw a meniscus.
[0031]
Further, since the Ni strike plating is not performed on the base surface of the seal ring main body 10, the Ag plating 14 and the Cu plating 12 applied to the seal ring main body 10 are melted in the step b, and the silver brazing 16 is performed. It is possible to prevent most of the silver solder 16 from creeping up to the upper surface of the seal ring body 10 and adhering to the upper surface of the seal ring body 10.
As a result, in step d, the cap 60 can be accurately resistance-welded by the seam weld method to the upper surface of the seal ring body 10 to which the silver braze 16 is not adhered or the upper surface of the seal ring body 10 having a small amount of silver braze 16 adhered. .
[0032]
In the method of manufacturing a semiconductor device using this seal ring, the seal ring body 10 made of iron-nickel-cobalt alloy or iron-nickel alloy is formed on the innermost base surface of the seal ring body 10. Since the Ag plating with good adhesion is applied, when the Ag plating 14 and the Cu plating 12 are sequentially applied to the seal ring body 10, the occurrence of blistering on the Ag plating 14 and the Cu plating 12 is prevented. be able to. Then, the Ag plating 14 and the Cu plating 12 can be attached to the seal ring body 10 with good adhesion.
Further, since the outermost side of the seal ring body 10 is subjected to Ag plating having good adhesion to Ni plating or the like, the semiconductor package 40 in the state shown in FIG. 4 before the semiconductor chip 42 is accommodated. When the outer ring Ni plating or the like is applied to the seal ring main body 10, the outer Ni plating or the like is transferred to the seal ring main body 10 through the Ag plating 14 remaining on the outermost side of the seal ring main body 10. It can be attached with good adhesion without causing blistering.
[0033]
【The invention's effect】
As described above, it was used sheet Ruringu of the present invention, according to the manufacturing method of the semiconductor device of the present invention, uniform and Ag plating and Cu plating applied to the seal ring body such unmelted portions does not occur Can be melted. And when the seal ring body is brazed to the seal layer of the semiconductor package using the silver brazing obtained by uniformly melting the Ag plating and Cu plating, over the seal ring body and the seal layer, The silver solder can be sufficiently adhered as if drawing a meniscus without generating a holed portion or an insufficiently adhered portion. Further, it is possible to prevent the leak path from being generated between the seal ring body and the seal layer, and to braze the seal ring body to the seal layer accurately and in an airtight manner.
[0034]
In addition, when Ag plating and Cu plating applied to the seal ring body are melted to form a silver solder, most of the silver solder crawls up to the upper surface of the seal ring body and adheres to the upper surface of the seal ring body. Can be prevented. When the cap is resistance welded to the top surface of the seal ring body by the seam weld method, the cap is accurately resisted to the top surface of the seal ring body by the seam weld method due to the influence of the silver solder adhering to the top surface of the seal ring body. It is possible to prevent the welding from becoming impossible.
[Brief description of the drawings]
FIG. 1 is a partially omitted cross-sectional view of a seal ring different from the seal ring of the present invention.
2 is a fragmentary sectional view of a sheet Ruringu of the present invention.
FIG. 3 is a process explanatory diagram of the semiconductor device manufacturing method of the present invention;
FIG. 4 is a process explanatory diagram of a method for manufacturing a semiconductor device of the present invention.
FIG. 5 is a process explanatory diagram of the method for manufacturing a semiconductor device of the present invention.
FIG. 6 is an explanatory diagram of a structure of a semiconductor device.
FIG. 7 is a partially omitted cross-sectional view of a conventional seal ring.
FIG. 8 is a process explanatory diagram of a conventional method for manufacturing a semiconductor device.
[Explanation of symbols]
10 the seal ring main body 12 Cu plating 14 Ag plating 16 silver solder 40 semiconductor package 42 connect the semiconductor chip 44 cavity 46 semiconductor package line 50 sealing layer 60 cap 100 Ruringu

Claims (2)

  Ag plating and Cu plating are alternately applied to three or more layers in turn on the base surface of the seal ring body made of iron-nickel-cobalt alloy or iron-nickel alloy. A seal ring for a semiconductor device, which is plated and has a thickness of 7 μm or less for each of Ag plating and Cu plating. A method for manufacturing a semiconductor device, comprising the following steps.
a. The claim 1 Symbol placement of the seal ring, a seal layer comprising a metallized formed at the open end peripheral portion of the semiconductor package of the cavity, the step of placing the Ni plating decorated with sealing layer on its surface.
b. The semiconductor package on which the seal ring is mounted is heated in a reducing atmosphere to melt Ag plating and Cu plating applied to the seal ring body of the seal ring, and the seal ring body is sealed to the semiconductor package. The process of brazing the layer in an airtight manner.
c. A step of housing a semiconductor chip in a cavity of a semiconductor package to which a seal ring body is brazed, and electrically connecting an electrode of the semiconductor chip and a connection line of the semiconductor package.
d. Covering the upper surface of the cavity containing the semiconductor chip with a cap made of iron-nickel-cobalt alloy or iron-nickel alloy, and sealingly sealing the cap to the seal ring body by a seam weld method.

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