JPH0758743B2 - Method for manufacturing hermetically sealed metal package for semiconductor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hermetically sealed metal package for semiconductors, and more specifically, it has excellent heat dissipation and airtightness for mounting electronic parts such as semiconductor elements or various circuit elements. The present invention relates to a hermetically sealed metal package for semiconductors.

2. Description of the Related Art A semiconductor device is packaged and put into actual use after being given a predetermined function. The form of this packaging is generally classified into ceramics, metal, glass, plastic packages, etc. according to its structure, but recently, more diverse structures can be obtained by appropriately combining these, semiconductor elements, It has emerged along with the trend toward larger devices and higher integration.

From the viewpoint of its reliability, this package protects the mounted semiconductor elements and other passive elements from the surrounding environment, and sets predetermined internal conditions that enable them to perform their functions normally. Plays a crucial role above. Therefore, even if the circuit design and the manufacturing process of the chip and the like are perfect, if the package is incomplete or inappropriate, the element may be destroyed, the quality may be deteriorated, and a failure mode unrelated to the semiconductor device may occur. It will be.

That is, the desired characteristic values of the semiconductor device are sufficiently maintained, thermal, electrical derivation, securing of an insulation distance between electrodes, packaging for transportation and handling convenience are performed,
As described above, in achieving high integration and high performance of the semiconductor device, the semiconductor device plays an important role especially for ensuring consistency between the device and external conditions. Improving the related technology is an important issue that must be solved in parallel with the performance improvement of the semiconductor device itself.

By the way, the conventional metal package uses Kovar (Fe-Ni-Co alloy), Fe-Ni alloy, Fe, stainless alloy, etc. for the metal base portion, and the hermetic sealing considers the thermal expansion coefficient of the metal base material and glass. The most suitable combination is selected, and it is roughly classified into a matching method in which the thermal expansion coefficients of the metal base material and the glass are almost the same, and a compression method in which a compressive stress is applied to the glass.

In this case, an appropriate oxide film is formed on the metal surface, whereby the wettability with respect to glass at the time of sealing is improved and good adhesion is obtained by diffusion of oxide.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, the metal base material as described above has a small thermal conductivity, and high density mounting, high speed operation, and high output of semiconductor devices including high frequency devices and optical devices are realized. Since it does not have a heat dissipation property that can sufficiently cope with the increase in the amount of heat generated due to the requirement for operability, the performance is deteriorated. Also, copper, which has good thermal conductivity, is used as the metal base,
Metal packages in which glass-sealing metals such as Fe, Kovar rings, and eyelets are joined by brazing have also been developed, but when subjected to a thermal cycle during brazing, the glass cracks due to the difference in the coefficient of thermal expansion between the metals. In some cases, the metal and glass may be peeled off and the airtight sealing may not be maintained, and even when the element or the substrate is mounted, thermal stress may cause breakage.

As described above, in the production technology of semiconductor devices, in order to improve the performance of semiconductor elements / devices, it is necessary to improve the semiconductor elements / devices themselves and the packaging method accordingly.

From the above, a Cu-W alloy whose thermal conductivity is larger than that of a conventional metal material for sealing in order to improve heat dissipation and is close to that of copper, and the thermal expansion coefficient is similar to that of a GaAs or alumina substrate,
By selecting Cu-Mo alloy or Cu-W-Mo alloy as the metal base material, it is considered possible to obtain a metal package for a semiconductor excellent in heat dissipation. However, the above-mentioned Cu-W alloy, Cu-Mo alloy, or Cu
The -W-Mo alloy cannot be used for metal packages that require high airtightness because the conventional glass sealing technology has poor wettability and familiarity with glass, and the surface oxidation treatment that is commonly performed is applied. However, high airtightness that can sufficiently withstand the thermal cycle during manufacture or use was not obtained.

Therefore, it is extremely significant for the future development of semiconductor technology to solve various drawbacks of the hermetically sealed metal package as described above and to develop a package structure that meets the recent trends of semiconductor devices. is there.

Therefore, it is an object of the present invention to provide a method for manufacturing a hermetically sealed metal package for a semiconductor, which has excellent heat dissipation and glass sealing properties, and thus has high hermeticity.

Means for Solving the Problems In view of the above-mentioned current state of the hermetically sealed metal package for semiconductors, the present inventors have made various studies, and as a result, in order to ensure the heat dissipation of the metal package, the conventional Cu- W alloy, Cu-
Mo alloys or Cu-W-Mo alloys are advantageous, in which case it is necessary to improve the wettability and conformability of these alloys with glass, but this problem is specific to the glass sealing part of the alloy. The present invention has been completed by finding that it can be advantageously solved by plating.

That is, the hermetically sealed metal package for a semiconductor of the present invention has a semiconductor element, a circuit element mounted thereon, a metal base having a lead wire through hole, and a lead which is passed through the through hole and hermetically fixed by glass sealing, A hermetically sealed metal package for a semiconductor, comprising a cap sealed at the peripheral edge of the metal base, wherein the metal base is made of Cu-W alloy, Cu-Mo alloy or Cu-W-Mo alloy, and Fe-Ni with a Fe content of 5 to 60 wt% is present on at least the surface of the glass sealing portion.
The method is characterized by including a step of providing an alloy plating layer.

In the metal base material useful in the hermetically sealed metal package of the present invention, the Cu content is in the range of 5 to 30% by weight, and it is preferable that the Cu content be uniformly contained in the alloy.

The structure of the hermetically sealed metal package for semiconductor of the present invention can be better understood with reference to the attached FIG. That is, as is clear from FIG. 1, its main part is composed of a metal base material 1, an electric signal input / output lead 2, and a cap seal portion 3. Where the lead wire 2
Is passed through the through-hole 4 provided in the metal base 1, and is hermetically fixed to the metal base 1 by the glass 6 as an insulating material through, for example, the Fe-Ni alloy layer 5 formed on the inner surface of the through-hole 4. ing. Further, a cap (not shown) sealing member 7 provided on the peripheral portion of the upper surface of the metal base 1 is made of Kovar or stainless steel, which is brazed to the metal base 1 with BAg8 or the like. .

The cap seal portion 7 and the cap can be joined by various conventionally known means, for example, electric resistance welding, arc welding, brazing, soldering, etc., as well as seam welding, which has been attracting attention recently.

A plating layer is used as the alloy layer provided on the glass sealing portion or the like. Examples of the method of forming the plating layer include electroplating, electroless plating, vapor phase plating and the like, and any of them gives a preferable result.

Function In the conventional hermetically sealed metal package for a semiconductor, a particular problem has been that the material used as the metal base material has too low a thermal conductivity. Further, as a material capable of improving this thermal conductivity, Cu-W, Cu-Mo or Cu-W is used.
Even if -Mo or the like was adopted, conversely, the wettability with the glass for hermetic sealing and the familiarity were poor, and good hermetic sealing could not be obtained.

Therefore, in the present invention, the above-mentioned Cu-Mo, Cu-W, Cu-W-Mo alloy, which is advantageous in terms of thermal conductivity, is selected as the metal base material,
An intervening layer of Fe—Ni alloy was provided between these in order to improve the wettability and familiarity with the glass. This Fe
The wettability and conformability between the -Ni alloy and the metal base material alloy and between the Fe-Ni alloy and the glass are extremely good.
When the Fe content is less than 5%, a sufficient oxide film cannot be obtained for the formation and diffusion of the oxide film effective for the wettability and conformability.
On the other hand, if it exceeds 60%, the oxide film becomes thick and brittle,
In order to achieve the above-mentioned desired effect, it is advantageous to set it in the range of 5 to 60 wt%. Further, the coefficient of thermal expansion of the above metal base alloy is in the range of 5.5 to 8.0 × 10 ^-6 / ° C. Therefore, by selecting the glass according to the coefficient of thermal expansion of the metal base alloy to be used, both matching and compression methods can be achieved. Can be used.

Therefore, by providing such an intervening layer, each of the above alloys having good heat dissipation can be advantageously used as a metal base material, and as a result, cracks and peeling of glass, which have been conventionally observed, and even elements and There is no risk of breakage even when subjected to thermal stress during mounting of the substrate.

For this reason, the Fe content in the Fe-Ni alloy is 5-60.
It is advantageous to set the content within the range of wt%, and outside this range, the coefficient of thermal expansion, the wettability with the metal base material or the glass, and the conformability are insufficient, and the intended purpose cannot be achieved. For the same reason, Cu in the metal base material alloy
It is preferable that the content rate of is also in the range of 5 to 30 wt%.

EXAMPLES Hereinafter, the hermetically sealed metal package for semiconductor of the present invention will be described more specifically according to examples. However, the scope of the present invention is not limited by the following examples.

Example 1 The main part of a semiconductor hermetically sealed metal package according to the present invention is as shown in FIG. To provide a hole 4 for penetrating the lead wire 2 in the metal base 1, apply plating 5 as an alloy layer on the surface of the hole 4, hermetically seal using glass as the insulating material 6, and cap-seal after mounting the element. A Kovar or stainless steel ring 7 is brazed with BAg8 on the outer peripheral portion 3 of the upper surface of the metal base 1.

The metal base 1 uses a Cu-W alloy, and the plating 5 is deposited.
Fe-Ni alloy plating is applied under the condition that the Fe content is 40 wt%, the lead wire 2 is sealed with Kovar, the insulating material 6 is sealed with Kovar sealing glass, and the Kovar ring is covered with a metal base upper surface outer peripheral portion 3
It was brazed with silver.

Next, considering the mounting of elements, circuit boards, etc.,
The heat cycle was carried out 3 times, in which it was moored at 5 ° C for 5 minutes and then left at room temperature. Conventionally, it was said that the Cu-W alloy could not be hermetically sealed with glass, but even when inspecting helium leakate with a He leak detector, it was possible to achieve a high hermeticity of 1 × 10 ^-10 atm cc / sec or less. It was

In addition, Cu-W alloy metal base is Cu-Mo alloy, Cu-W-Mo
It was also confirmed that similar results could be obtained by changing the alloy.

Example 2 Plating was performed as in Example 1, and the outer peripheral portion 3 of the upper surface of the metal base was used.
The stainless steel ring 7 was brazed with silver braze 8, the lead wire 2 was Fe—Ni alloy, and the insulating material 6 was glass sealed with Fe—Ni sealing glass. After the heat cycle, in the same test as in Example 1, there was a significant difference in the hermetic sealing property between the plated product and the unplated product, and the plated product was good.

EFFECTS OF THE INVENTION As is clear from the above description, according to the present invention, based on the unique feature that the metal base and the lead are hermetically sealed through a specific alloy layer, (1) Cu-W It is possible to manufacture a hermetically sealed metal package for semiconductor using an alloy, Cu-Mo alloy, Cu-W-Mo alloy as a metal base material; (2) Cu-W alloy, Cu-Mo alloy, Cu-W- By using Mo alloy, these thermal conductivities are large, so high-density mounting is possible compared to when using conventional sealing metal,
It is possible to provide a hermetically sealed metal package for semiconductors which is excellent in heat dissipation and can be used with a large output power.

It should be noted that the present invention is not limited to the shape of the package shown in the embodiment, and a mount for mounting various optical-related elements such as a laser diode, an emitting diode, and a photodiode, and a mount for mounting a high-frequency related element. It can be advantageously applied to a metal base that requires high heat dissipation.

[Brief description of drawings]

FIG. 1 attached herewith is a partially cutaway schematic front view for explaining the constitution of the main part of a metal package manufactured by the method of the present invention. (Main reference numbers) 1 ... metal base, 2 ... electrical signal input / output lead, 3 ...
… Cap seal part, 4 …… Through hole, glass seal part, 5
...... Plating, 6 ... Insulation material, 7 ... Kovar or stainless steel ring, 8 ... Silver solder

Claims (2)

[Claims] 1. A metal base having a through hole and loaded with a semiconductor element and / or a circuit element, a lead wire inserted through the through hole and hermetically fixed by glass sealing, and a metal base of the metal base. In a manufacturing process of a hermetically sealed package for a semiconductor, which is sealed at a peripheral portion of an upper surface and has a cap that covers the semiconductor element and / or the circuit element, a Cu-W alloy, prior to the step of performing the glass sealing, Cu-
5 to at least the surface of the glass sealing portion with respect to the metal base formed of Mo alloy or Cu-W-Mo alloy.
A method for manufacturing a hermetically sealed metal package for a semiconductor, comprising the step of forming a plated layer of an Fe-Ni alloy containing 60 wt% Fe. 2. The manufacturing method according to claim 1, wherein the metal base contains 5 to 30 wt% of Cu.