JPH05160520A - Package for optical semiconductor element - Google Patents

Abstract

PURPOSE:To miniaturize a package for an optical semiconductor element, and facilitate alignment at the time of building-in or the like as an optical pick-up. CONSTITUTION:The entitled package which contains an optical semi-conductor element chip 4 and cut it off from the external atmosphere has a stem 1 composed of ceramic material wherein a wiring electrode is formed by metallization. A metal plate 2 turning to a reference plane of the package is fixed to the rear of the stem 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a package for an optical semiconductor device such as a semiconductor laser device, and is particularly useful as an optical pickup for an optical disk player and the like.

[0002]

2. Description of the Related Art As a conventional optical semiconductor device package, for example, there is a semiconductor laser package as shown in the plan view and side view of FIGS. The package of the semiconductor laser element 51 is such that the semiconductor laser chip 5 is mounted on a metal block (heat sink) 52 in the package.
3 is die-bonded, and a metal cap 55 having a window glass 54 for laser irradiation so as to cover them is electrically welded to a metal stem 57 provided with a reference surface 56 to shut off the outside atmosphere from the inside of the cap 55. is doing. The semiconductor laser chip 53 is electrically connected by wire bonding to the electrode pins 58, 58 that are pulled out of the package through the stem 57 while maintaining airtightness with the cap 55 by a hermetic seal.

Generally, a semiconductor laser device is not used alone, but is used in combination with an optical component such as a lens. For example, when used in a pickup for an optical disk as shown in the schematic view of FIG. 6, the emission point position of the semiconductor laser element 51, which is a light source, is determined by the design value such as the f value of the lens 59. As described above, the position of the semiconductor laser chip 53 in the package cannot be directly measured. Therefore, in order to guarantee the positional relationship between a certain position on the outer surface of the package and the semiconductor laser chip 53, the package is provided with the reference surface 56 as described above.

That is, although FIG. 5 shows an example using a TO-18 package, a reference surface 56 is attached to a metal stem 57.
And the semiconductor laser chip 5 from above the reference plane 56 is provided.
The light emitting point position of No. 3 and the center of the outer diameter of the reference surface 56 and the light emitting point position are guaranteed with a certain tolerance. Therefore, as shown in FIG. 6, by attaching the semiconductor laser element 51 to the housing 60 of the optical pickup, the optical position with respect to the lens 59 and the like can be easily determined.

[0005]

However, since the conventional semiconductor laser package uses the metal stem 57, it is necessary to electrically insulate the electrode pins 58 from each other by a hermetic seal. This insulating portion is an obstacle to miniaturization of the package. In particular, not only a light emitting element such as a semiconductor laser chip, but also a package incorporating an OEIC in which an optical element and an integrated circuit (IC) are combined, or a hologram laser incorporating a semiconductor laser chip and a photodiode for reading a signal of an optical disc in one package In the unit, the number of electrode pins increases, the package becomes large, and it becomes an obstacle to making the optical pickup thin and lightweight.

The present invention has been made in view of the above points, and by using ceramics as a stem material, a package for an optical semiconductor device can be miniaturized, an optical pickup can be made thin and lightweight, and a metal plate can be attached as a reference surface of the package. Accordingly, it is an object of the present invention to provide an optical semiconductor device package that can easily align the optical elements.

[0007]

SUMMARY OF THE INVENTION The present invention is a package for an optical semiconductor element that incorporates an optical semiconductor element chip and is shielded from the external atmosphere, and has a stem made of a ceramic material in which wiring electrodes are formed by metallization. A metal plate serving as a reference surface of the package is attached to the back surface of the stem.

[0008]

As described above, according to the package of the present invention, in the stem portion for fixing an optical semiconductor chip such as a semiconductor laser chip by die bonding, the stem itself is made of a ceramic electrically insulating material having a good heat dissipation property, and a metal surface is applied to the ceramic surface. Since fine plated wiring can be performed and the insulating portion in the conventional metal package is not required, the package can be downsized. Further, the ceramic shrinks due to the firing process, and the tolerance becomes larger than that of the metal stem, so that the ceramic is not suitable as the reference surface forming portion. For this reason, in the present invention, a metal plate is attached as a reference surface, which makes it possible to improve the positional accuracy of the semiconductor laser chip and easily perform alignment with other optical elements.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a hologram laser unit using the optical semiconductor device package of the present invention. FIG. 1 (a) is a perspective view from above and FIG. 1 (b) is a perspective view from below. Is. FIG. 2 is a sectional view showing the internal structure.

The package comprises a ceramic stem 1 and a reference surface metal plate 2. The metal plate 2 for the reference surface is fixed to the back surface of the ceramic stem 1 with a brazing material or the like.

A metal block (heat sink) 3 is fixed on the ceramic stem 1 with a brazing material such as AuSi, and a semiconductor laser chip 4, a laser emitting light monitor PIN diode 5, and an optical disk are attached to the block 3. The signal reading photodiodes 6 that receive the return light are die-bonded. The optical semiconductor chips 4, 5 and 6 are electrically connected to the surface electrodes 8 formed on the ceramic stem 1 by wire bonds 7, respectively. The surface electrode 8 is provided by metallization, and electrodes with a fine pitch can be formed. Further, the ceramic stem 1 has a through hole 9 connected to the front surface electrode 8 and a lead frame 10 which is brazed on the back surface at each through hole 9 portion. , 6 are led out of the package by these.

The ceramic cap 11 is provided with a window glass 12 for emitting a laser, and is adhered to the ceramic stem 1 with an epoxy resin material so that each optical semiconductor chip 4,
5 and 6 are covered to shut off the outside atmosphere from the inside of the cap 11. The hologram element 13 for optical diffraction is adjusted and fixed on the cap 11, and thereby a hologram laser unit is configured.

FIG. 3 shows a case where an optical pickup is assembled using the hologram laser unit. A metal plate 2 fixed to a ceramic stem 1 by a brazing material or the like is used as a semiconductor laser chip 4 (FIG. 1, FIG. (See 2)
Of the semiconductor laser chip 4 in the unit 14, that is, the unit 14 or the semiconductor laser chip 4 in the unit.
The positioning of the optical components such as the collimator lens 16 and the like can be easily performed. Also, as clearly shown in FIG.
Since the semiconductor laser chip 4 is die-bonded so that the outer diameter center “0” of the metal plate 2 and the light emitting point position of the semiconductor laser chip 4 coincide with each other, the hologram laser unit 14
The rotation adjustment can be easily performed when the is mounted on the optical pickup.

In the optical pickup of FIG. 3, after the laser light passes through the hologram element 13 and the collimator lens 16,
The mirror 17 guides the light toward the disk 18 and the objective lens 19 narrows the spot. The return light from the disk 18 passes through the reverse path described above, and the signal reading photodiode 6 in the hologram laser unit 14 (see FIGS. 1 and 2).
Signal) and the signal is read.

FIG. 4 is a perspective view of an essential part showing another embodiment. In this example, instead of the metal block 3 fixed on the ceramic stem 1 of FIGS. 1 and 2, a block 20 made of an electrically insulating material having excellent thermal conductivity such as AlN is used.

A surface wiring 20 is provided on an electrically insulating block 20 such as AlN, and a semiconductor laser chip 4 and a signal reading photodiode 6 are die-bonded or wire-bonded to the surface for electrical connection. Further, the block 20 is fixed to the ceramic stem 1 by a brazing material, and the electrode terminals of each optical semiconductor element are connected to the outside of the unit through the surface electrode 8, the through hole 9 and the lead frame 10 (see FIG. 2) as in the previous embodiment. Be derived to. This example has an advantage that the wiring inside the unit can be performed by an insulating block and the steps such as wire bonding can be simplified.

[0017]

As described above, according to the present invention, in a package for an optical semiconductor device containing a semiconductor laser chip or the like, a conventional metal stem portion is made of a ceramic material, and fine pitch electrodes are formed by metallization. It is possible to make a compact design for a package that requires a large number of electrode pins, and the metal plate attached to the back surface acts as a reference surface, so that the optical semiconductor element chip such as a semiconductor laser chip in the package and the optical It is possible to easily enhance the positional accuracy with respect to the housing that houses the package such as the pickup and other optical components.

[Brief description of drawings]

FIG. 1 is a perspective view from above and a perspective view from below showing a package of an embodiment of the present invention.

FIG. 2 is a sectional view of the same.

FIG. 3 is a sectional view showing a case where the optical pickup is incorporated as an optical pickup.

FIG. 4 is a perspective view of an essential part showing another embodiment.

FIG. 5 is a plan view (a) and a side view (b) showing a conventional example.

FIG. 6 is a cross-sectional view showing a case where the optical pickup is incorporated as a conventional optical pickup.

[Explanation of symbols]

 1 Ceramic Stem 2 Metal Plate for Reference Surface 4 Semiconductor Laser Chip 6 Photodiode for Signal Reading 8 Surface Electrode 9 Through Hole 10 Lead Frame

Claims (1)

[Claims] 1. A package for an optical semiconductor device, which includes an optical semiconductor device chip and is shielded from an external atmosphere, has a stem made of a ceramic material on which wiring electrodes are formed by metallization, and a reference surface of the package is provided on a back surface of the stem. A package for an optical semiconductor element, comprising a metal plate to be attached.