JP3763785B2 - Cap for semiconductor device, semiconductor device and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cap for a semiconductor device, a semiconductor device, and a manufacturing method thereof, and more particularly to a cap for a semiconductor device that prevents stray light in a cap body, a semiconductor device, and a manufacturing method thereof.
[0002]
[Prior art]
In an optical device using laser light, a semiconductor device on which a laser diode is mounted is used for receiving and emitting laser light. FIG. 6 is an explanatory diagram showing a configuration of a semiconductor device in which the laser element 10 for light emission and the monitor element 12 are mounted. 14 is a stem, and 16 is a cap for a semiconductor device joined to the stem body 14a so as to accommodate the laser element 10 and the monitor element 12. In such a semiconductor device, the laser light incident on the inside of the semiconductor device cap 16 from the light transmission window 18 or the laser light emitted from the light emitting laser element 10 toward the light transmission window 18 is applied. There is a problem that stray light reflected inside the semiconductor device causes noise and malfunction of the semiconductor device.
[0003]
As a method of preventing such problems such as noise due to stray light, a method of suppressing irregular reflection of light by making the inner surface of the cap 16 for a semiconductor device and the surface of the stem 14 black has been conventionally performed. For example, a method in which cobalt or cobalt alloy plating is applied to the cap body and the plating film is blackened by heating in an oxidizing atmosphere (Japanese Patent Laid-Open No. 6-252281), and a black nickel plating film is formed on the cap body. A method of blackening by heating in the atmosphere (Japanese Patent Laid-Open No. 7-7098).
[0004]
[Problems to be solved by the invention]
However, since the method of plating and heating in order to make the inner surface of the semiconductor device cap 16 or the like black is complicated, as a method of simply blackening, electrolytic Sn-Ni as a black plating is applied to the cap body. A method of performing plating is performed. However, in the conventional black electrolytic Sn—Ni plating, the density of black is not always sufficient, the laser element has a high output, and the laser beam is likely to be irregularly reflected on the inner surface of the cap 16 for semiconductor device. There is a problem that is likely to occur.
[0005]
Also, since the black film formed by electrolytic Sn-Ni plating has low blackness, if the plating film deposited on the surface of the cap body has unevenness, the appearance of the product tends to appear as shading unevenness, and the appearance of the product deteriorates. There is a problem.
Moreover, if the thickness of the plating film varies, there is a problem that the adhesion at the joint between the cap and the stem body is lowered.
In addition, in the case of a product provided with a light transmission window attached to the cap in advance, when the cap is immersed in a plating bath of electrolytic Sn-Ni plating, the light transmission window is joined. There has also been a problem that metal impurities such as lead are dissolved in the plating solution from the melting point glass, thereby shortening the life of the plating solution.
[0006]
Therefore, the present invention has been made to solve these problems. The object of the present invention is to provide a cap for a semiconductor device in which Sn-Ni plating is applied to a cap body as a black film for preventing stray light. Caps for semiconductor devices and semiconductors that can effectively suppress the stray light of the laser beam due to the surface, can improve the adhesion between the cap and the stem, can prolong the life of the plating solution, and can provide a good product It is in providing an apparatus and its suitable manufacturing method.
[0007]
[Means for Solving the Problems]
The present invention has the following configuration in order to achieve the above object.
That is, a cap for a semiconductor device in which a light transmission hole is formed in an upper portion of the cap body, and a black film is formed on the cap body to prevent stray light by plating, and a base plating film is formed on the cap body, A first black film made of Sn—Ni plating is provided on the base plating film, and Zn—Ni formed on the first black film on a rough surface having irregularities larger than those of the first black film. A second black film made of plating is provided.
Further, the base plating film is made of nickel plating.
[0008]
Further, in a semiconductor device in which a semiconductor device cap having a light transmission hole covering a light semiconductor element mounted on the stem is joined to the stem body, a base plating is applied to the cap body of the semiconductor device cap and the stem body. A film is formed, and a first black film made of Sn—Ni plating is provided on the base plating film. On the first black film , a rough surface having larger irregularities than the first black film is formed. A second black film made of the formed Zn—Ni plating is provided.
[0009]
Further, in a method for manufacturing a cap for a semiconductor device in which a black film is formed on the surface of a cap body having a light transmitting hole, after forming a base plating film on the cap body, the cap body is made of low melting glass using the low melting point glass. A light transmission window is welded so as to cover the light transmission hole, Sn-Ni plating is performed on the cap main body to which the light transmission window is welded, and a first black film is formed on the surface of the base plating film, and then And applying a Zn-Ni plating to the cap body and overlaying the first black film to form a second black film formed on a rough surface having a larger unevenness than the first black film. And
Further, as the base plating, nickel plating is performed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.
FIG. 1A is an explanatory diagram showing the configuration of a cap for a semiconductor device according to the present invention, and FIG. 1B is an explanatory diagram showing the configuration of a conventional cap for a semiconductor device. In FIG. 1, reference numeral 20 denotes a cap body of a cap for a semiconductor device. The cap body 20 is formed by press-molding a metal material into a cap shape, and a light transmitting hole 22 through which laser light passes is formed in the upper part of the cap body 20. As the material of the cap body 20, iron, iron-nickel alloy, iron-nickel-cobalt alloy, or the like is used.
[0011]
A characteristic configuration of the cap for a semiconductor device according to the present invention is a configuration of a black film for preventing stray light formed on the surface of the cap body 20. FIG. 2 is an enlarged view of the plating layer formed on the surface of the cap body 20 in order to explain the configuration of these plating layers.
As a pre-process for forming a black film on the cap body 20, first, base plating for improving the corrosion resistance of the cap body 20 is applied to the cap body 20. In this embodiment, nickel plating is applied as the base plating. The nickel plating is formed to a thickness of about 3 μm by electroless plating or electrolytic plating. In FIG. 2, 24 is a base plating film. The base plating of the cap body 20 by nickel plating or the like is performed similarly in the conventional cap for a semiconductor device as shown in FIG.
[0012]
Next, electrolytic Sn—Ni plating is performed on the surface of the base plating film 24 to form a first black film 26. Applying electrolytic Sn—Ni plating as a black film on the surface of the base plating film 24 is also performed as a means for manufacturing a conventional cap for a semiconductor device as shown in FIG. The thickness of the first black film 26 formed by electrolytic Sn—Ni plating is about 0.3 μm in both the conventional example and the present embodiment.
[0013]
In the semiconductor device cap according to the present invention, the surface of the first black film 26 is further subjected to electrolytic Zn-Ni plating to form the second black film 28. FIG. 2A shows that the second black film 28 is formed on the surface of the first black film 26. The second black film 28 was provided at a thickness (about 0.15 μm) that was about one half of the thickness of the first black film 26.
In the cap for a semiconductor device according to the present invention, the second black film 28 is formed on the surface of the first black film 26 by forming the black film to prevent stray light into a plurality of layers. By utilizing the light-absorbing action of the black film 26 and the light-absorbing action of the second black film 28, the laser light is prevented from being irregularly reflected and the stray light is more effectively prevented than the conventional cap for a semiconductor device. This is so that it can be suppressed.
[0014]
In the conventional cap for a semiconductor device, it is possible to suitably suppress the reflection of the laser light in the vicinity of 780 nm by forming the first black film 26 by Sn-Ni plating on the surface of the base plating film 24. In addition to this, the cap for a semiconductor device according to the present embodiment is characterized in that it effectively acts on irregular reflection of laser light in a low wavelength band of 650 nm or less by providing the second black film 28 by Zn-Ni plating. There is.
[0015]
FIG. 3 is an electron micrograph (20,000 times) observing the surface state of the cap body 20 in the cap for a semiconductor device of the present embodiment in which the second black coating 28 is further formed on the first black coating 26. FIG. Shows an electron micrograph (20,000 times) observing the surface state of a cap body of a conventional cap for a semiconductor device provided with only the first black film 26. Comparing the electron micrographs shown in FIGS. 3 and 4, in the case of the conventional cap for a semiconductor device shown in FIG. 4, the surface of the cap body 20 is formed to be smooth and flat, whereas FIG. In the case of the semiconductor device cap of the present embodiment shown, it can be seen that relatively large crystal grains are formed on the surface of the cap body, and the surface of the cap body is formed on a rough surface with many irregularities. The surface of the cap body of the semiconductor semiconductor device cap 16 is formed in a rough surface having relatively large irregularities as shown in FIG. 3, so that the blackness of the black film can be increased and incident on the cap body 20. The laser light has improved light absorbency on the surface of the cap body 20, and stray light can be suppressed by reducing the reflectance.
[0016]
Thus, in the semiconductor device cap of the present embodiment, only the first black coating 26 is formed by forming the first black coating 26 and the second black coating 28 on the surface of the cap body 20. Stray light can be effectively suppressed as compared with the provided conventional cap for a semiconductor device. The action of suppressing the stray light is not only the action of adding the light absorption action of the first black film 26 and the second black film 28 but also the action that the surface of the cap body 20 is formed into a rough surface. This is the action obtained.
[0017]
When forming the second black film 28, the workpiece is transferred from a plating tank for electrolytic Sn-Ni plating to a plating tank for electrolytic Zn-Ni plating and electrolyzed using an electrolytic Zn-Ni plating bath. Zn-Ni plating is applied. In this electrolytic Zn—Ni plating, it is important to stabilize and uniformly deposit the plating film on the surface of the cap body 20 to eliminate the variation in appearance and to improve the adhesion of the plating film. When the electrolytic Zn—Ni plating is actually performed, if the plating is performed while simply applying a DC voltage between the plating electrodes, the voltage between the electrodes gradually increases, and a product having a good appearance cannot be obtained. For this reason, in the present embodiment, suitable electrolysis is performed by controlling the voltage between the plating electrodes to be maintained at a constant voltage, or by applying the voltage in a pulse manner so that the voltage between the plating electrodes is constant. Zn-Ni plating was applied.
[0018]
By forming the second black film 28 on the surface of the cap body 20 in this manner, the surface of the cap body 20 can be covered with the second black film 28 having a high concentration, and the first black film in the lower layer is formed. Even if the coating 26 has irregularities in appearance, these irregularities can be prevented from appearing in the appearance of the product, and the appearance and appearance of the final product can be improved.
[0019]
As shown in FIG. 1A, the semiconductor device cap described above is a product in which a light transmission hole 22 is provided in the upper part of the cap body 20, and this product is provided with a base plating film 24 and a first plating film on the cap body 20. After the black film 26 and the second black film 28 are formed, the light transmission window 18 and the like are joined and used so as to cover the light transmission hole 22.
On the other hand, some semiconductor device caps are provided with the light transmitting window 18 bonded to the cap body 20 in advance. In the case of this product, after the base plating film 24 is formed on the cap body 10, the light transmission window 18 is welded using low melting point glass to form the first black film 26 and the second black film 28. Product. In the case of a product provided by bonding the light transmission window 18 to the cap body 20, as a manufacturing problem, components such as lead contained in the low-melting glass are eluted into the plating bath to deteriorate the plating solution. There is a problem.
[0020]
That is, in the case of a product in which the light transmission window 18 is provided by welding to the cap body 20 using low-melting glass, after the base plating film 24 is formed on the cap body 20, the light transmission window 18 is formed using low-melting glass. Next, electrolytic Sn—Ni plating and electrolytic Zn—Ni plating are applied. In this electrolytic Sn-Ni plating and electrolytic Zn-Ni plating, the cap body 20 is sequentially immersed in a plating bath for electrolytic Sn-Ni plating and a plating bath for electrolytic Zn-Ni plating. However, during the plating, metal impurities such as lead contained in the low-melting glass are eluted into the plating bath, thereby deteriorating the plating solution and shortening the life of the solution.
[0021]
In order to extend the life of the plating solution, it is necessary to prevent the metal impurities contained in the low melting point glass from eluting into the plating solution. However, the cap for a semiconductor device according to the present invention prevents stray light. For this reason, the thickness of the first black film 26 is used in the conventional cap for a semiconductor device by forming the black film for the purpose of a two-layer structure of the first black film 26 and the second black film 28. Even if it is thinner than the black film, a sufficient stray light preventing effect can be obtained.
Since the first black film 26 is formed by electrolytic Sn-Ni plating, the time during which the workpiece is immersed in the electrolytic Sn-Ni plating bath can be reduced by reducing the thickness of the first black film 26. Accordingly, it is possible to prevent the metal impurities from eluting into the plating solution, and to increase the life of the plating solution used for electrolytic Sn-Ni plating.
[0022]
Further, when electrolytic Sn-Ni plating is applied to the cap body 20 to which the light transmission window 18 is joined, the surface of the cap body 20 is covered with the first black film 26 and the light transmission window 18 is welded. The surface of the melting point glass is also covered with the first black film 26. The first black film 26 covering the surface of the low-melting glass prevents the metal impurities contained in the low-melting glass from eluting into the plating solution when the electrolytic Zn-Ni plating is performed next. Acts as a barrier.
That is, when the electrolytic Zn—Ni plating for forming the second black film 28 is applied to the surface of the cap body 20, the surface of the low melting glass is covered with the first black film 26. Is prevented from eluting into the plating bath, the deterioration of the plating solution for electrolytic Zn-Ni plating forming the second black film 28 is also suppressed, and the plating solution is made to have a long life. be able to.
[0023]
FIG. 5 shows a state in which the semiconductor device cap 16 is joined to the stem 14 to assemble the semiconductor device. The cap 16 for a semiconductor device has a light transmission window 18 welded to a cap body 20 by a low melting point glass 17, and is joined to the stem body 14a so as to cover the laser element mounted on the stem 14 by laser welding or resistance welding. ing.
The stem body 14a is made of iron, iron-nickel alloy, iron-nickel-cobalt alloy or the like. The stem 14 inserts the lead pin 30 into a through hole 32 penetrating the stem body 14a in the thickness direction, and the lead pin 30 is made of glass. 34 is formed by sealing. The lead pins 30 can be sealed with resin instead of the glass 34. A heat radiator 36 is formed integrally with the stem body 14a on the upper surface of the stem body 14a. The laser element 10, which is an optical semiconductor element, is mounted on the side surface of the radiator 36, and the laser element 10 and the lead pin 30 are electrically connected.
[0024]
Similar to the semiconductor device cap 16 described above, the semiconductor device on which the optical semiconductor element according to the present embodiment is mounted is first plated by nickel plating as the base plating on the stem body 14a and then subjected to electrolytic Sn-Ni plating. The black film 26 is formed, and then electrolytic Zn-Ni plating is applied to form the second black film 28.
As a result, the semiconductor device formed by joining the semiconductor device cap 16 to the stem body 14a has the entire inner surface of the semiconductor device housing the optical semiconductor element by the semiconductor device cap 16 and the stem body 14a. The black film formed by superposing the first black film 26 and the second black film 28 is formed, and reflection of laser light can be prevented over the entire inner surface of the semiconductor device, and stray light can be effectively suppressed.
[0025]
Further, according to the present invention, since the black film is uniformly formed on the surface of the cap body 20 and the surface of the stem body 14a, the semiconductor device cap 16 and the stem 14 are joined by laser welding, resistance welding, or the like. In addition, these can be reliably bonded, the adhesion between the cap 16 for the semiconductor device and the stem 14 can be improved, and the sealing degree of the semiconductor device can be improved.
[0026]
【The invention's effect】
According to the semiconductor device cap and the semiconductor device according to the present invention, as described above, it is possible to effectively suppress the reflection of the laser light on the cap body and the inner surface of the semiconductor device, and to reduce the noise of the semiconductor device caused by stray light. It becomes possible to suppress the occurrence of malfunction. In addition, according to the method for manufacturing a cap for a semiconductor device according to the present invention, the first black film and the second black film can be suitably formed on the cap body, and the life of the plating solution can be extended. It is effective such as being able to.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a configuration of a cap for a semiconductor device.
FIG. 2 is an explanatory view showing a configuration of a black film formed on the surface of the cap body.
FIG. 3 is an electron micrograph showing the surface properties of the cap body of the cap for a semiconductor device according to the present invention.
FIG. 4 is an electron micrograph showing the surface properties of a cap body of a conventional cap for a semiconductor device.
FIG. 5 is an explanatory diagram showing a configuration of a semiconductor device according to the invention.
FIG. 6 is an explanatory diagram showing a general configuration of a semiconductor device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Laser element 12 Monitor element 14 Stem 14a Stem main body 16 Semiconductor device cap 18 Light transmission window 20 Cap main body 22 Light transmission hole 24 Base plating film 26 First black film 28 Second black film 30 Lead pin

Claims (5)

A cap for a semiconductor device in which a light transmission hole is formed in an upper portion of the cap body, and a black film that prevents stray light by plating is formed on the cap body,
A base plating film is formed on the cap body,
A first black film made of Sn-Ni plating is provided on the base plating film,
A semiconductor device characterized in that a second black film made of Zn-Ni plating formed on a rough surface having larger irregularities than the first black film is provided on the first black film. Cap.   2. The cap for a semiconductor device according to claim 1, wherein the base plating film is made of nickel plating. In a semiconductor device in which a cap for a semiconductor device having a light transmission hole covering a light semiconductor element mounted on a stem is joined to a stem body ,
A base plating film is formed on the cap body and the stem body of the semiconductor device cap,
A first black film made of Sn-Ni plating is provided on the base plating film,
A semiconductor device characterized in that a second black film made of Zn-Ni plating formed on a rough surface having larger irregularities than the first black film is provided on the first black film. . In the method for manufacturing a cap for a semiconductor device in which a black film is formed on the surface of the cap body having a light transmission hole,
After forming a base plating film on the cap body, a light transmission window is welded to cover the light transmission hole using a low melting point glass on the cap body,
Applying Sn-Ni plating to the cap body to which the light transmission window is welded to form a first black film on the surface of the base plating film,
Next, Zn-Ni plating is performed on the cap body, and the second black film is formed on the rough surface having a larger unevenness than the first black film by overlapping the first black film. A method for manufacturing a cap for a semiconductor device.   5. The method for manufacturing a cap for a semiconductor device according to claim 4, wherein nickel plating is applied as the base plating.

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