JPS6338272A - Photosemiconductor device - Google Patents

Abstract

PURPOSE:To improve the directivity of a photosemiconductor device with relatively high intensity thereby to provide a high sensitivity with good condensing efficiency by providing a micro Fresnel lens in a window formed at a light passing position. CONSTITUTION:An element chip 4 is mounted on a heat sink 3, and the chip 4 is LD, LED, PD or APD, and covered with a cap 5. The cap 5 is secured to a mount 1 by normal method, such as can sealing, bonding or fusion-bonding. A window 5a is opened at the top (upper surface) of the cap 5, i.e., at a position of passing the emitted light of the chip 4 or the incident light to the chip 4, a micro Fresnel lens 6 made of transparent resin is mounted thereat, and the lens 6 is secured by bonding to the inner periphery of the window 6a at the peripheral edge. The finely formed surface formed with an uneven part of the lens 6 is so disposed as to direct the inside of the cap 5.

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION This invention relates to optical semiconductor devices. What is an optical semiconductor device?1
Refers to a semiconductor device that has a single function of emitting or receiving light, or a semiconductor device that has both functions of emitting and receiving light.

This concept includes a light emitting device, a light receiving device, a light emitting device, and the like.

Laser diode (LD), light emitting diode (LED)
) Light emitted from a light-emitting element such as a light-emitting element is a wide, diverging light, so in order to utilize this light, a separate collimating lens is generally provided in front of the light-emitting element to convert it into parallel light. There are many things. However, if a collimating lens is provided, a device using this light emitting element will inevitably become larger, and optical axis adjustment, focal length adjustment, etc. will be required. Furthermore, the light emitted from the LD has anisotropic spread angle, so it diverges into an elliptical cone shape. Therefore, it is not possible to completely collimate the light with a single ordinary lens, and in order to obtain sufficiently collimated light, a set of lenses or an aspherical lens must be used, which is expensive.

On the other hand, in light-receiving elements such as photodiodes (PDs) and avalanche photodiodes (APDs), it has conventionally been necessary to provide an external lens in order to efficiently focus incident light onto the light-receiving surface. Ta.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems by providing a new type of compact optical system near an optical semiconductor element chip.

The present invention is an optical semiconductor device of a type in which an optical semiconductor chip is mounted by a cap with a window, and is characterized in that a micro Fresnel lens is provided in the window formed at a light passage position.

When the optical conductor chip is a light emitting element chip.

It is preferable that the light emitted from the light emitting element be substantially collimated by the micro Fresnel lens, and when the optical semiconductor chip is a light receiving element chip, the focus of the micro Fresnel lens is set to be parallel to the light receiving element. It is preferable that the light-receiving surface be located approximately at the second light-receiving surface.

In the case where the optical semiconductor chip is a light emitting/receiving element chip having both light emitting and light receiving functions, the micro Fresnel lens (1) is placed in a position and shape suitable for this purpose. For example, in a device that has a light emitting part in the center and a light receiving part around it,
The light emitted from the center becomes parallel light and is output to the outside.
It is preferable to fabricate a Fresnel lens with two focal points so that most of the incident light from the outside is focused on the surrounding light-receiving areas.

Furthermore, if the optical semiconductor chip is an LD and the divergence angle of the emitted light differs depending on the direction, almost perfect collimation can be achieved by making the pattern of the Fresnel lens such that the focal length differs depending on the direction. It can also be made to receive light.

According to this invention, the emitted light from the 7 light-emitting element chip is almost parallelized, resulting in relatively high intensity (high brightness) and good directivity, and the incident light is received by the light-receiving element chip. Since the light is focused on the surface, the light collection efficiency is good and the sensitivity is high.

In addition, regardless of whether it is a single light-emitting or light-receiving element chip, the micro Fresnel lens can be molded in plastic, so it is highly productive and can be provided at low cost. Because of this, the optical axis does not shift, resulting in excellent environmental resistance, and further downsizing and weight reduction can be expected.

DESCRIPTION OF THE EMBODIMENTS Referring to FIGS. 1 and 2, a submount or heat sink 3 is provided on a stem or mount 1 having several terminals 2. In FIG.

An element chip 4 is attached to this heat sink 3. As mentioned above, the element chip 4 includes LD, LED, P
D, APD, etc. chips.

The element chip 4 is covered with a cap 5.

The cap 5 is fixed to the mount 1 by can sealing, welding, welding, or other conventional methods.

There is a window 5 at the top (two sides) of the cap 5, that is, at the position where the light emitted from the element chip 4 or the light incident on the element chip 4 passes.
A is opened, and a transparent resin micro or Fresnel lens 6 is attached thereto. This Fresnel
The lens 6 is fixed at its peripheral edge to the inner peripheral surface of the window 5a by adhesive. Preferably, as shown in FIG. 2, the Fresnel lens 6 is arranged so that the micro-machined surface on which the concavo-convex portion is formed faces the inside of the cap 5. This protects the microfabricated surface from external forces and prevents deterioration of lens characteristics. It is even better to provide a protective glass outside the window 5a of the cap 5.

When the element chip 4 is a light emitting element (LD, LED, etc.), the position and focus of the micro Fresnel lens 6 are determined so that the light emitted from the element 4 is substantially collimated by the micro Fresnel lens 6. Further, when the element chip 4 is a light receiving element (PD, APD, etc.), the position, focus, etc. of the micro Fresnel lens 6 are determined so that the incident light is almost focused on the light receiving surface of the element 4. Ru.

In particular, when the element chip 4 is an LD, the spread angle of the emitted light exhibits anisotropy, and as shown in FIG.
The divergence angle differs depending on the direction. Therefore, the cross section of the emitted light is elliptical. In order to almost completely collimate such emitted light, it is preferable to use a Fresnel lens having an elliptical pattern as shown in FIG.

In FIG. 1, the electrodes of the element chip 4 are connected to the corresponding terminals 2.
Needless to say, it is wire bonded to the

Micro Fresnel like this. The lens 6 can be integrally molded from transparent resin by injection molding or other methods.

The female mold of the micro Fresnel lens for resin molding can be made in various ways, for example, as follows.

An electron beam resist is applied onto a predetermined substrate, a micro Fresnel lens pattern is drawn on the resist by electron beam lithography, and then this resist is developed. Then, the remaining resist pattern on the substrate is transferred to the substrate by dry etching. This substrate becomes a female mold (see Japanese Patent Application No. 61-3419).

Alternatively, a female mold is formed by electroforming using the above residual film resist pattern as a male mold. That is, the remaining resist pattern is plated with metal.

After that, by dissolving the remaining film pattern and the substrate with an organic solvent, only the metal plating part is left (patent application No. 61
-3420).

[Brief explanation of the drawing]

Figure 1 is a partially cutaway perspective view showing an embodiment of the present invention, Figure 2 is a sectional view of the cap and micro Fresnel lens in Figure 1, and Figure 3 is light emitted from a semiconductor laser. Figure 4 is a diagram showing the state of divergence of light, and Figure 4 shows a micro-meter suitable for collimating light with such a divergence angle.
It shows a Fresnel lens pattern. 4... Light emitting or light receiving element chip. 5... Cap. 5a...window. 6...Micro Fresnel fist lens. that's all

Claims (5)

[Claims] (1) An optical semiconductor device of the type in which an optical semiconductor chip is mounted using a cap with a window, characterized in that a micro Fresnel lens is provided in the window opened at a light passage position. (2) The optical semiconductor device according to claim (1), wherein the optical semiconductor chip is a light emitting element chip, and the light emitted from the light emitting element is substantially collimated by the micro Fresnel lens. (3) The optical semiconductor device according to claim (1), wherein the optical semiconductor chip is a light receiving element chip, and the focal point of the micro Fresnel lens is located substantially on the light receiving surface of the light receiving element. . (4) The optical semiconductor device according to claim (1), wherein the optical semiconductor chip is a light emitting light receiving element. (5) the optical semiconductor chip is a semiconductor laser chip,
The optical semiconductor device according to claim 1, wherein the micro Fresnel lens converts light emitted from a semiconductor laser chip and anisotropically diffused into parallel light.