JPS6355229B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a planar semiconductor integrated circuit device in which a semiconductor laser and an electronic circuit having functions such as amplification, modulation, stabilization, and switching are monolithically formed.

[Background of the invention]

When fabricating a semiconductor laser and an electronic circuit monolithically, a two-story structure using an n-type substrate (H.Matsueda: Japan JAP20 ('81))
S20-1p.193) and the method using semi-insulating (SI) substrates (A. Yariv: IE ³ Spectrum, May ('82)
p.38) is proposed. In order to increase the degree of integration, the latter is more advantageous because a larger area can be used. However, conventionally, this has been difficult to realize because it creates a step difference on the element surface.

[Purpose of the invention]

The present invention relates to a planar semiconductor laser integrated circuit device in which a semiconductor laser diode and an electronic circuit are formed on the same substrate without forming a step. The electronic circuit section has functions such as modulation, amplification, stabilization, and switching, making the semiconductor laser multifunctional.

[Summary of the invention]

A stepped recess is previously formed in a semi-insulating substrate, and a conductive semiconductor layer and a double heterostructure are deposited in the recess using selective epitaxial crystal growth techniques. Built-in semiconductor laser. Especially MOCVD method (Metalorganic Chemical Vapor Deposition)
crystal growth is advantageous. Thereafter, electronic circuits are formed on the surface of the fresh semi-insulating substrate in areas other than the recesses, and the whole becomes a planar opto-electronic integrated circuit with no steps.

[Embodiments of the invention]

A layer of SiO ₂ , SiN ₄ , PSG (phosphorus glass), Al ₂ O ₃ , etc. with a thickness of 1000 Å to 5000 Å formed on a semi-insulating GaAs substrate 1 by CVD or sputtering.
Using the film as a mask 3, a wide recess is formed by etching as shown in FIG. The depth of this part is 0.5 μm to 3 μm. Next, using the MOCVD method with the above-mentioned mask attached, the recessed portions are made of n ⁺ type conductive GaAs2 doped with Se (or Te, Sn, etc.) as shown in Figure 1. Please embed it. This embedding can be done using LPE (liquid phase epitaxial growth) method,
It is also possible to use the MBE (molecular beam epitaxial) method. The higher the carrier concentration of this n ⁺ conductive layer 2, the better because the series resistance will be lower, but it is practical if it is on the order of 10 ¹⁹ cm ^-3 . Next, as shown in FIG. 1, a deeper recess 15 is formed in a portion of the recess by etching. The depth is 2 μm to 10 μm.
After that, by using the selective growth technique again, Fig. 1 4
As shown in the figure, a double heterostructure laser element is built so that it fits exactly into the deeper recess. The structure of the double heterostructure itself may be similar to that of a normal semiconductor laser. i.e.
n-type with Se-doped carrier concentration 1×10 ¹⁸ cm ^-3
Cladding layer 4 with a thickness of 0.5 μm to 2.0 μm of Ga _0.6 Al _0.4 As and a thickness of Ga _0.96 Al _0.04 As with a carrier concentration of 10 ¹⁶ cm ^-3
Active layer 5 of 0.1 μm, P-type Ga _0.72 Al _0.28 As with carrier concentration 3-5×10 ¹⁷ cm ^-3 doped with Zn.
A cladding layer 6 of 0.5 μm to 2.0 μm and a P-type GaAs with a carrier concentration of 1×10 ¹⁷ cm ⁻³ and a thickness of 0.1 μm to 1.0 μm.
This is the cap layer 7 of.

Next, in order to form the P-side current path of the laser, Zn is diffused into the impurity region 8 as shown in FIG.
form. The depth is preferably 2 μm to 5.0 μm closer to the deep recess from the boundary between the deep recess and the shallow recess. Further, it is desirable to prevent current leakage by implanting protons or oxygen ions into the portions where the laser layers come close to each other and mix at both ends of the deep recess, as shown at 9 in FIG. 1.

Thereafter, an electronic circuit is formed on the surface of the fresh semi-insulating substrate other than the recessed portions by a well-known method. First of all,
By implanting Si ions, the ohmic electrode layer 11
, and further, an active layer 10 is formed. The ohmic electrode 13 of the electronic circuit section is first made of AuGeNi/Au.
After the laminated film was deposited and lifted off, it was formed by alloying at 400°C for 3 minutes. The shot key electrode 14 and the P-side electrode 12 of the laser are Ti/
It was formed by depositing a Pt/Au laminated film and lifting it off. In addition, for the tangent lines and wiring inside the electronic circuit and between the electronic circuit section and the laser section, a Mo/Au laminated film was deposited and a pattern was formed by ion milling.

FIG. 2 shows another embodiment. Stepped recesses 16 and 17 are provided in the semi-insulating semiconductor substrate from the beginning (FIG. 2, 1). An n ⁺ conductive layer 2 is formed in this recess in the same manner as in the previous example (FIG. 2). A portion of this n ⁺ conductive layer is then left in the deeper recess, as shown in FIG. This amount is the thickness of the conductive layer shown at 15 in FIG. 2, and a thinner layer of 30 μm or less is desirable for reducing series resistance. Everything else is first
This is the same as the embodiment. That is, FIG. 2 shows a state in which double heterostructures are stacked in the recess, and FIG. 2 shows a state in which an electronic circuit has been manufactured and wiring has been performed. In FIG. 2, the same symbols as in FIG. 1 indicate the same parts.

In any of the examples, similar structures could be made using other semiconductor materials such as InP/InGaAsP.

〔Effect of the invention〕

(1) It was possible to fabricate a double-heterostructured laser element together with an electronic circuit having a fine pattern on a semi-insulating substrate without creating a step.

(2) High-speed operation of 2GHz or higher was achieved by integrating the laser and drive circuit.

[Brief explanation of drawings]

1 and 2 are cross-sectional views showing the manufacturing process of a planar semiconductor laser integrated circuit device according to the present invention. 1: Semi-insulating (SI) substrate, 2: n ⁺ type conductive layer,
3: Mask for selective growth, 4: Laser n-side cladding layer (GaAlAs), 5: Laser active layer (GaAlAs), 6: Laser P-side cladding layer (GaAlAs), 7: Laser cap layer (GaAs),
8: Laser P-side diffusion region, 9: Ion implantation region for current leak prevention, 10: Active layer in electronic circuit section, 11: Ohmic electrode layer of electronic circuit section and laser n-side electrode section, 12: Laser p-side metal Electrode, 13: Laser n-side metal electrode and electronic circuit ohmic metal electrode, 14: Electronic circuit section shot key metal electrode.

Claims (1)

[Scope of Claims] 1. A semi-insulating semiconductor substrate has a shallow first recess and a deep second recess, a conductive semiconductor layer is buried in the shallow first recess, and a conductive semiconductor layer is embedded in the deep second recess. A double heterostructure is formed in which an active layer is sandwiched between cladding layers, and an electronic circuit is formed in a region other than a portion of the semi-insulating semiconductor substrate that constitutes a laser, and is formed in the first recess. A planar semiconductor laser integrated circuit device, characterized in that the laser section and the electronic circuit section are connected through a conductive semiconductor layer. 2. The planar semiconductor laser integrated circuit device according to claim 1, wherein the conductive semiconductor layer is also provided on a wall surface of the second recess that is in contact with the first recess.