JPS596587A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To make electrical connection between both sufficient in case of integration of a laser diode with an electrical circuit in a lateral direction, and reduce the floating capacity, further offer an integration structure whereby the pattern formation of a complicated and precise electrical circuit can be attained. CONSTITUTION:The titled device is an example applied for an integrated circuit wherein GaAs/GaAlAs is used, and composed of a semi-insulating GaAs substrate 1, an N-GaAs conductive layer 2, an N-GaAlAs clad layer 3, a P-GaAs cap layer 6, bonding pads (Cr/Au) 8, 13, 14, a laser stripe electrode (Cr/Au)G, ohmic electrodes (AuGe/Ni/Au) 10, 12, a Schottky electrode (Ti/Tt/Au) 11 and an SiO2 film 15. A thickened active layer oscillates laser at the active region of a TS laser.

Description

[Detailed description of the invention] The present invention relates to the integration of a semiconductor laser and an electric circuit section.

On top of the semi-insulating substrate, T S (Terrased S
To provide a structure in which a (ubstrate) type laser diode and an electric circuit are arranged side by side in a plane.

An example of integrating a laser diode with an electric circuit is
Laser diode and FET (FieldEffe
ct Transistor, field effect transistor) and are vertically combined in a two-story shape (H6Ma
Tsueda, To Fukzawy, T, '1 (
uroda.

M, Nakamura; Japan J, App
l, Phys, 'yo1゜20 (1981) 8
upp1.20-1 1) p, 193-197 and an example of horizontal combination (S, Margal
It, N., Bar-Chaim, J.

KatZ, 1. Ury, D., P., Wilt.
, M., Yustand A., Yariv H.I., a.
ser pocus, 3ept.

(1980) I) p, 76-80). The method of vertically combining devices has advantages such as high-speed response and compactness, but depending on the type of electrical circuit, it may be necessary to combine devices horizontally. However, in the horizontal planar combinations that have been reported so far, the electrical connection between the electric circuit and the laser diode is not sufficiently practical, and high-speed response and low-power driving cannot be expected at all.

Moreover, the difference in level between the laser diode section and the electric circuit section was large, making it impossible to create a highly accurate electric circuit pattern by photolithography.

When a laser diode and an electric circuit are integrated horizontally, the present invention provides a sufficient electrical connection between the two,
To provide an integrated structure which can reduce stray capacitance and achieve complex and precise pattern formation of electric circuits.

When integrating a laser diode and an electric circuit, they are fabricated horizontally in parallel on a semi-insulating substrate, especially in order to enable precise patterning of complex circuits using ion implantation technology or the like. The n-side electrode of the laser diode was formed by forming an n-type semiconductor layer with a high carrier concentration on a semi-insulating substrate. The overall structure is the first
As shown in the figure. As shown in the figure, the structure of the laser section is a T8 structure, so there is no large step between it and the electric circuit section, and it is easy to form a notch by photolithography.

Furthermore, if a high resistivity layer is grown on the LD using, for example, the liquid phase epitaxial crystal growth (LPE) method, an electric circuit can be created on the upper side of the LD, that is, on the p side, using technology such as ion implantation. I can do it.

The present invention
An example of application to an integrated circuit using s is shown below. The overall structure is shown in FIG. That is, 1: semi-insulating Q a
As substrate < (100) plane), 2: n-GaA
s conductive layer (0.5 pm thickness) #3: ” GaAlA
s cladding layer (0.5 μm thick) * 4: GaAs active layer (0.1 μm thick).

5: p-GaAlAs cladding layer (1 μm thick).

6: p-GaAs cap layer (0.5 pm thickness), 8
゜13.14: Bonding pad (Cr/Au) s9
: Laser stripe electrode (Cr/Au) ((011> direction) tio, 12 niomic electron-fFM (Au
Ge/N i/Au ), 11: Shit key electrode (T i/P t/AU ), 7.15: S
in, an insulating film. The part 16 is the active region of the TS laser, and the thick active layer oscillates the laser. FIG. 2 is an enlarged view of this active region. The thicker part is the area that emits light. In this embodiment, the level difference between the laser section and the electric circuit section is only 3 μm.

By using the reduction projection exposure method, it was possible to form a fine pattern with a minimum dimension of 1 μm in the electric circuit section. Although the electrical circuit of FIG. 1 shows an example of one FET, in reality, a laser modulation/drive circuit consisting of several F'ETs could be integrated. The connection between the laser section and the electric circuit section is shown in 2. in FIG. The distance from the stepped part of the TS laser to the end of the metal electrode closest to the laser in the electric circuit (d in Figure 1) is 15 μm or less. This resulted in particularly high-frequency characteristics and low-power operation.

The manufacturing method is outlined below. Since conventional manufacturing methods can be applied to each of the semiconductor laser section and the electric circuit section, their descriptions will be kept brief.

A recess of approximately 2 μm is formed in a predetermined portion of the (100) plane of the semiconductor Q a , A s substrate 1 . Its slope is 70″
~45°. Including this recess, the above-mentioned recess is usually about 1.0 to 3.0 μm. Thickness 0.
5 μm n-type Q a As conductive layer 2. Thickness 0.5μm
n Ml! Ga, 7A t,,, A s layer 3.
Q a A with a thickness of 0.1 prn! i active layer 4. thickness i
μmop type Ga.

A t, , A s layer5. Thickness 0.5 tt m p
A GaAs type cap layer is formed using a well-known liquid phase epitaxial growth layer.

Next, the layer 2 of n-type GaAs 4 is exposed by partially etching the upper part of the step of the semi-insulating substrate. Next, a part of this conductive layer is left and the rest is etched to expose the surface of the semi-insulating substrate 1. The total height difference caused by these two etchings does not exceed 3 μm.

Next, apply a voltage of 100 to 150 KeV on the exposed semi-insulating substrate.
By implanting Si ions at an acceleration voltage of , the active region, electrode region, electrical resistance, etc. of an electric circuit are formed. After ion implantation, annealing is performed at a temperature of 850 C in an arsenic atmosphere to promote proper ionization of the implanted elements. Thereafter, Zn is diffused into the stepped portion of the substrate from the second surface of the epitaxial growth layer to form a current path leading to the active region.

Next, return to the exposed semi-insulating substrate, and first 810. After forming an insulating film to a thickness of about 0.5 μm, ohmic electrodes, Schottky electrodes, and inter-electrode wiring are formed by vacuum metal deposition and lift-off. Ohmic electrode is AuQe/Ni/A”
, Schottky electrodes and inter-electrode wiring were formed by sequential Cr/Au deposition. Note that prior to wiring between electrodes, a PSG film (phosphorus glass) is deposited by CVD to insulate necessary portions.

The inter-electrode wiring could also be created by depositing metal and then processing it into a desired pattern by ion milling.

After forming the laser part and the electric circuit part in the above-described manner, each chip was cut out from the wafer by crevices and scribing, attached to the stem, and the required external wiring kAu wire was bonded by thermocompression.

The structure according to the present invention makes it possible to reduce the step difference between the laser section and the electric circuit section to 3 μm or less. Therefore, it was possible to form a fine pattern with a minimum dimension of 1 μm on the electric circuit portion by photolithography. The operating threshold of the laser in the device of the invention can be as low as 10-30 mAKi.

Although the above example has been explained with respect to GaAs-GaAtAs-based materials, the present invention can also be realized in the same way with materials such as ■-V group compound semi-quadratures that can realize laser oscillation, and Tatoe's InP-InGaAsP-based materials. It is possible.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an example in which double heterostructure laser diodes and FETs are integrated horizontally in parallel on a semi-insulating GaAs substrate, and Fig. 2 shows an example of the active layer of a semiconductor laser. It is a sectional view showing a shape. 1...Semi-insulating ()a As substrate, 2...n-Ga
As conductive layer, 3.n-QaAtAs cladding layer, 4
"・Q a A 8 active layer, 5"'p GaA4As cladding layer, 6 ・I) -GaAs cap layer, 7.1
5...5iOt insulating film, 8°13.14...Cr/
Au Pumpings (Rad, 9...Cr/A u
Laser stripe electrode, 10.12・AuGe/N
i/Au, t-mic electrode, 11...Ti/Pt/A
``U Schottky electrode. Patent applicant: Ya111 Fujin Le Mizu6-

Claims (1)

[Claims] 1. A recess is formed in a desired region of a semi-insulating semiconductor substrate, and a plurality of semiconductor layers including a conductive layer and an active layer for laser oscillation are formed on the semi-insulating semiconductor substrate so as to cover at least the stepped region of the recess. , the active layer has a thicker region in the stepped region than the remaining portion, and an electronic circuit is integrated in the remaining portion of the semi-insulating semiconductor substrate. A semiconductor laser device characterized by: