JPS62264661A - Optical-electronic integrated circuit and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain optical-electronic IC of high performance by a method wherein an nnnn<+> multilayer epitaxial film of AlX Ga1-xAs is provided with a composition ratio (x) varied on a semi-insulative GaAs substrate, further npnn<+> multilayer epitaxial film of AlzGal-zAs is superposed thereon with a composition ratio (z) varied, and a p+ layer is provided selectively. CONSTITUTION:n-AlxGa1-xAs 2, n-CaAs 3 and n-A$1xGa1-xAs 4 are superposed on semi-insulative GaAs 1 to construct a horizontal fringe laser, and n+-GaAs 5 is superposed thereon. Moreover, n-GaAs 6, p-AlzGa1-zAs 7, n-AlzGa1-zAs 8 and n<+>-GaAs 9 are superposed. A p<+> layer 10 is diffused to prepare a hetero junction element of an n<+> collector 5, a p<+> base 10 and an n<+> emitter 9. Next, a p<+> ion implanted layer 11 extending from the n<+> layer 5 to the substrate 1 is prepared, diffusion is conducted again to provide a p layer 12, electrodes P and N to form a laser diode, and H ions are implanted for element isolation 13 and 13 '. According to this construction, the concentration of a laser active layer and the concentration of a base layer of a transistor can be set separately, and the horizontal laser of a low threshold current and the trsnsiator of a cut-off frequency of 1 GHz or above are obtained on the same substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a high-speed and highly reliable optical/electronic integrated circuit used in an advanced reliable transmitter and a method for manufacturing the same.

(Prior Art and Problems to be Solved by the Invention) A conventional optical transmitter consists of a semiconductor laser (hereinafter referred to as an LD, a clamp, and an electronic circuit that drives and modulates the light source), each of which is made up of individual components. However, in this Ld) method, operation is slow due to propagation delay and stray capacitance caused by wiring between components, and problems caused by connections. Deterioration in reliability due to this is also a problem. Therefore, in order to construct a high-speed and highly reliable optical transmitter, an optical/electronic integrated circuit that integrates optical elements and seven electronic elements is required. In particular, heterojunction bipolar transistors (Heter.

5structure Bipolar Transi
Since the stor (hereinafter referred to as HBT and stor) has high current drive capability and high-speed operation, an integrated circuit combining the HBT and LD' is promising as a continuous optical transmitter.

As an attempt to construct an integrated circuit using HBT and LD,
Report by J. Katz et al. (Appl.
, Ph7s, Lett, +37(2), 198
0).

FIG. 3 shows the configuration shown in the above report, and this device is made of an n''-GaAs substrate 20, a first layer of n-AlGaAs 21 on the substrate side, and a second layer of p-GaAs 2.
2. The 31st mn-AlGaAs 23 epitaxial I[- was grown to fabricate an HBT with an npn structure, and Be ions were added to the p-GaAs 2 from the 31st edict.
By implanting up to 2, the 3rd/11123rd n-Al
It has been devised that it can also be operated as an LD with an npp structure in place of the t-pW24 part of GaAs. However, this strange structure has the following drawbacks.

That is, the p of the second layer n used as the active layer of the LD
-GaAs s Since it is necessary to prevent the laser oscillation threshold from being raised due to light absorption by visible carriers, it is not desirable to increase the total doping concentration (≧5 Xl01't-rn-'). On the other hand, this p-GaAs layer
It is also used as the base part of BT, but in HBT, it is possible to increase the base concentration and reduce the base resistance, as can be seen from the cut Cc: Collector capacity, which is a guideline for operating speed. Operationally advantageous.

It is clear from the above that in order to improve the performance of LD and HBT at the same time, compositions suitable for each must be selected.

It is necessary to choose the film thickness and doping density, and a method using only an epitaxial film consisting of a primary npn structure, such as Kaatsu et al.'s method, is insufficient.To solve this problem, it is necessary to An epitaxial multilayer film having an nnp (or npps) structure with an undoped active layer and a 7'Cnpn structure suitable for HBT is successively formed, and LD is applied to each epitaxial film.

HBTfr can be fabricated separately, but in such a multilayer structure, it is necessary to perform deep etching when removing the lower electrode of the LD or HBT, resulting in large surface steps, making it unsuitable for multilayer stacking. It becomes a structure. 1ft% LD
, selective growth in which the epitaxial film for HBT is grown separately over the entire plane is also technically difficult, and there are many problems in its application to integrated circuits.

(Detailed means for solving the problem) An object of the present invention is to enable the growth of epitaxial films that are advantageous in terms of device characteristics for both HBTs and LDs, and to avoid problems such as overpassing of steps that arise due to this. Another object of the present invention is to provide a high-performance, easy-to-integrate optical/electronic integrated circuit and a method for manufacturing the same.

To achieve the above object, the present invention provides a first semiconductor layer of M1 conductivity type, and a second semiconductor layer of first conductivity type, which has a narrow gap compared to the first semiconductor layer, on a semi-insulating substrate. layer,
A second semiconductor layer is attached to the first multilayer epitaxial film in which a third half body of the first conductivity type, which has a wider gap than the second semiconductor layer, is layered with a foil layer. Fake, first and third semiconductor layers? A lateral junction stripe laser having a Clarado layer is configured, a fourth semiconductor layer having a 14th turtle-type high concentration impurity on the first multilayer epitaxial layer, and a fifth semiconductor layer of a first conductivity type; 6th conductivity type
, a seventh semiconductor layer of the first conductivity type which has a wider gap than the sixth semiconductor layer, and a high v! of the first conductivity type.
An eighth semiconductor layer containing impurities is sequentially stacked 7'.
A fifth semiconductor layer collector, a sixth . 7th. As soon as the eighth semiconductor layer is formed, a high concentration impurity region having a conductivity of 2 is formed in a base contact region;
An opto-electronic integrated circuit characterized in that a Peter junction bipolar transistor is constructed in which a portion other than the base contact region in the sixth semiconductor layer is a base, and a portion other than the base contact region in the seventh semiconductor layer is a vine. This is the gist of the invention.

Further, the present invention provides a first semiconductor layer of the first conductivity type, a second semiconductor layer of the first conductivity type, which has a narrower gap than the first four-layer structure, on the semi-insulating substrate. A first multilayer epitaxial film is formed by sequentially stacking third semiconductor layers of the first conductivity type, which have a wider gap than the semiconductor j-, and a second semiconductor layer is formed in the first multilayer epitaxial film. A fourth semiconductor which constitutes a horizontal junction stripe V-ZA in which the layer is an active layer and the first and third semiconductor layers are cladding layers, and has a first conductivity type high concentration impurity on the first multilayer epitaxial film. a fifth semiconductor layer of the first conductivity type, a sixth semiconductor layer of the second conductivity type, a seventh semiconductor layer of the first conductivity type having a wider gap than the sixth semiconductor layer; A second semiconductor layer is formed by sequentially stacking an eighth semiconductor layer having a high concentration impurity of a conductivity type.
6. Form a multilayer epitaxial @. 7th. The second semiconductor layer is formed using ion implantation or vapor phase diffusion into the eighth semiconductor layer.
selectively forming conductor-type high concentration impurity regions, forming the fifth semiconductor layer t-collector, W, 6. 7th. The high concentration impurity region of constant temperature 2 conductivity type formed in the eighth semiconductor layer is used as a base contact region, and the base contact 9A in the sixth semiconductor layer is used as a base contact region.
The gist of the invention is a method for manufacturing an opto-electronic integrated circuit, which is characterized in that a heterojunction bipolar transistor is constructed in which a base other than the base contact region in a seventh semiconductor layer is used as an emitter.

However, the characteristics of the present invention are as follows. First, the film thickness is 1 composition through HBT and LDK.

In order to realize the impurity concentration, the substrate side is etched as an epitaxial film corresponding to each element structure.
n n” n p n n+niji naru multi 7m exchange k,
MOVPE.

It is formed using a crystal growth technique such as MBE or LPE, and a valley element is manufactured in this epitaxial film.

The LD uses the lower nnnn+ layer, and a lateral junction stripe laser (Transverse Junction) is inserted here.
nStripe (hereafter referred to as TJS and Hashi) will be fully manufactured. T.J.S.
As a result of the structure, the LD electrode can be suspended from the fourth n+ layer, so deep etching is not required.
A flat surface structure suitable for integration can be realized.

Since the base layer of the HBT is independent of the LD, high concentration doping is possible.Furthermore, by having a graded bandgap structure, the transit time of electrons within the pace is shortened, which increases current amplification. An increase in the rate is measured.

Such an epitaxial film structure is completely different from the film structure of conventional opto-electronic integrated circuits.

Next, embodiments of the present invention will be described with reference to the accompanying drawings.0 It should be noted that the embodiments are merely illustrative, and it goes without saying that individual changes or improvements can be made without departing from the spirit of the present invention.

FIG. 1 shows an embodiment of the present invention, and its configuration is as follows. In the figure, 1 is a semi-insulating substrate made of GaAa. On this semi-insulating substrate, a 144th type @10
n-At3:Ga1- of semiconductor layer 2;

As% n-GaAs (or A
tyGal-yAs) (Engineering>y), the third semiconductor layer of the first conductivity type has a wide gap compared to the second semiconductor layer 3.
The n -kL□Ga□- and As of the semiconductor layer 4 are layered one after another, and the first multilayer epitaxial lUk is formed on the semiconductor +1112.3.4. A horizontal reception stripe/-the active layer and semiconductor layers 2 and 4 are used as cladding layers. Next, n + -GaAs of the stripped semiconductor layer 5 having a first conductivity type high concentration impurity on the first multilayer epitaxial film, then n -GaAs of the first thinly molded fifth semiconductor layer 6,
p -Atz'Ga1 of the second cage-shaped sixth semiconductor layer 7
-1' Aa s sixth semiconductor;
Next, a second multilayer epitaxial film is formed by sequentially stacking the 14th cage-type n''-GaAs of the eighth semiconductor layer 9 having impurity concentration. .9 is formed in the 254th straight pot strength impurity area 10.Therefore, the fifth semiconductor noso 6 is formed.
Let be the collector, the high concentration impurity filling area lOt of the second conductivity, the base contact area of the 7 gates of the sixth semiconductor layer, the base outside the base contact area of the seventh semiconductor layer 11g8, and all the emitters outside the base contact area of the seventh semiconductor 11g8. All heterojunction bipolar transistors are formed.

To add further explanation, the semiconductor layer 2 directly above the semi-active GaAs substrate 1 is made of n-At:, Ga1-, As.
(0x<1), and this becomes the cladding layer of a laser diode (hereinafter referred to as LD). The semiconductor layer 3 is a portion that becomes the active layer of the LD and is made of n -GaAs or n -At.
yGa ty-y As (However, z>y) becomes 1. (An appropriate impurity@(Si) concentration is 5×10×3.) The semiconductor layer 4 is n-AtzGa 1-2 As and becomes the cladding layer of the LD. Since the M composition 'jez>y,
The refractive index of the semiconductor N3 is as large as that of the semi-integrated body M2.
The optical confinement effect works to reduce the laser threshold. The semiconductor WI5 has an n”- layer provided as a contact layer.
This layer is a GaAs layer, and in addition to the LD electrode, the HBT collector electrode is also formed from this layer. The semiconductor layer 6 is n-G
aAs serves as the collector portion of the HBT. semiconductor/
#7 is a p region consisting of a tilted bandgap structure, and HB
This is the part that becomes the 6th layer of T. Appropriate impurity (Be)
The concentration is 5 xlO"/cW1'. The semiconductor layer 8 has n
-AAGa 1-z As is the part that becomes the emitter of the HBT.

The semiconductor layer 9 is a contact layer made of n''-GaAs and serves as the emitter and space electrode of the HBT. Impurity region 10
A p-type impurity such as Zn + Be + Mg is ion-implanted or vapor-phase diffused to form a p+ region, and is provided in a manner to make contact with the base layer.

Thus, the semiconductor/fi 7' is made into a graded bandgap pace. In this case, p-At2Ga1 layer-2'
In As, the value of z' is continuously changed from zero to 2, so the band structure is LP in Figure 2(b).
/! /c becomes. Therefore, it is injected into the base region 7'
The C electrons are accelerated by the internal electric field, and when electrons are diffused in the conventional base region (see Figure A), they travel with a faster drifting speed.

This effect is related to the base transit time τ, where (K: Bolsomann constant I T 11 absolute temperature of diffusion, q: electron charge amount, band gap difference △Eg at both ends of the base)
If it is set to t-0.2 eV, the travel time will be shortened to about 1/4. As a result, in addition to increasing the current gain β, it is also possible to use p-GaAs for the semiconductor layer 7, which is expected to improve the characteristics of the HBT, such as reducing the recombination of electrons and holes.

E, B, and Ci indicate emitter, pace, and collector electrodes, respectively.

For the LD, a p-type impurity such as Zn + Be + Mg is ion-implanted or vapor-phase diffused into the semiconductor layers 2 to 5 to form a p+ region 11, and then the p-type impurity is re-diffused by heat treatment to form a p-type impurity region 12. A p region shown in is formed. 13
．． Reference numeral 13' indicates an insulating region formed by ion implantation of B, H, or the like. P and N indicate electrodes, respectively.

When an electrode is provided on the contact layer 5 and a current is applied, the current flows through the same pn junction in the semiconductor layer 2.3.4. In the pn junction formed in 4, the internal barrier to carriers is lower in the semiconducting layer 3, so the current mainly flows through the pn junction in the semiconductor layer 3, which becomes the active layer of the LD.Next, regarding the manufacturing order. explain.

A first semiconductor layer 2 (n-At, Gat, Ast) is formed on a pinned semi-insulating GaAs substrate l, and then a second semiconductor layer 30n-GaAl1 or n-GaAl1 having a narrow gap compared to the first semiconductor layer is formed. n-AtyGa 1-y
As (where x > y) Ir is formed, and then n-At, Ga1-air, and Asi of the 30th semiconductor layer 4, which has a wider gap than the semiconductor layer 3, are formed to form the first multilayer epitaxial film. The semiconductor layer 3 is formed as an active layer, and the semiconductor layers 2 and 4 are formed in this first multilayer epitaxial film.
■Type compatible stripe laser with cladding layer? Configure.

Next, a fourth semiconductor layer 5 of n''-GaAs having a high concentration of impurities is formed on the first poly-epitaxial layer, and a fifth n-GaAs layer of a fifth semi-quadram layer 6 is formed thereon. In addition, n -AL, /Ga1- of the sixth semi-quaternary layer 7
2'As 1 n -At2Ga1-2A of the seventh semiconductor layer 8 which has a wide gap compared to the sixth semiconductor layer 7
s s Next, a second multilayer epitaxial film is formed by laminating the eighth semiconductor layer 9 of n-GaAs having a high concentration of impurities. 7th. After selectively forming a p-type high a degree impurity region 10 in a part of the eighth semiconductor layer 7° 8.9 using ion implantation or vapor phase diffusion, the semiconductor layer 6
A high-a-grade impurity region 10, a base contact region, a sixth semiconductor layer 7, and a seventh semiconductor layer 8 are placed on the T collector.
A heterojunction bipolar transistor is constructed with the emitter.

(c) Next, an ion-implanted insulating region 13 is formed, and the LD
Complete configuration.

Note that the above-mentioned inclined band structure can be realized by changing the ratio of the raw materials during crystal growth. For example, the tilted band structure of AlGaAs can be fabricated using metalorganic vapor phase epitaxial method (Metalorganic V epitaxial method).
apor Phase Epitaxy), the flow rate of hydrogen gas containing trimethylaluminum (TMA) is kept constant while the flow rate of hydrogen gas containing trimethylgallium (TMG) and arsine (AsHs) gas is constant. This method uses a method of continuously changing l.

First of all. Third. The seventh semiconductor layer has InPx second and fourth layers.
Fifth. InGaAs or InGaA is used as the eighth semiconductor layer.
sP s InP or InGaAs for the sixth semiconductor layer
Alternatively, InGaAsP f can also be used.

Furthermore, in the above description, nfi can be made p-type instead of p-type tn-type.

(Effects of the Invention) As explained above, according to the present invention, an LD and an HBT can be integrated on the same substrate without impairing their characteristics, and as a result, high-speed and highly reliable optical/electronic integration can be achieved. It becomes possible to manufacture circuits.

This L-connected optical/electronic integrated circuit has the advantage that it can be used as an optical transmitter suitable for increasing the capacity of optical communication.

Furthermore, in the present invention, since the active layer concentration of the lateral junction stripe laser and the base concentration of the heterojunction bipolar transistor can be set separately, the threshold current of the laser is low (about 10 mA), and the lateral junction stripe laser has a low threshold current (about 10 mA). A laser and a heterojunction bipolar transistor with a high cutoff frequency (IGHz or higher) can be formed on the same substrate.

Since a Mayu horizontal injection type junction stripe laser is used, there is no need to form a deep etching groove to take out the electrode from the bottom of the laser as in the conventional case, and the surface level difference can be reduced. .

Since the transistor has a sloped bandgap base structure, the current amplification factor can be increased.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the opto-electronic integrated circuit of the present invention, FIG. 2 shows the bandgap configuration of the present invention and the conventional example, and FIG. 3 shows the configuration of the conventional example. 1...Semi-insulating substrate GaAs 2...First semiconductor layer n-AL:l:Ga
1-, A33... Second semiconductor layer n-GaAs
or AtyGa 1-yAs (x>-4...
Third semiconductor/#n-At engineering Ga□-□As5...
...Fourth semiconductor Mn"-GaAs6...
・Fifth semiconductor) ili n -GaAs7...
・M6 semiconductor layer p-At2Ga1-2'As8...
...Seventh semiconductor node n -At2Ga1-, As
9...Eighth semiconductor layer n"-GaAs10...
...High @ degree impurity region 11 ... P+ region 2 ... Rediffusion region 13, 13' ... Ion implantation insulation region 1st cell Fig. 2 (a) Base I 1,000 (b) ``''''Spicy 1 + Portable 1''N!

Claims (12)

[Claims] (1) A first semiconductor layer of a first conductivity type, a second semiconductor layer of a first conductivity type having a narrow gap compared to the first semiconductor layer, and a second semiconductor layer on a semi-insulating substrate. A first multilayer epitaxial film in which a third semiconductor layer of a first conductivity type with a wide gap is sequentially laminated, the second semiconductor layer is an active layer, and the first and third semiconductor layers are cladding layers. A lateral junction stripe laser is configured, in which a fourth semiconductor layer having a first conductivity type and a high concentration impurity is formed on the first multilayer epitaxial film, a fifth semiconductor layer having a first conductivity amount, and a second semiconductor layer having a first conductivity type and a high concentration impurity. a sixth semiconductor layer of a conductivity type; a seventh semiconductor layer of a first conductivity type having a wider gap than the sixth semiconductor layer;
A second multilayer epitaxial film in which an eighth semiconductor layer having a high concentration of impurity of the first conductivity type is laminated in sequence, a fifth semiconductor layer is placed in the collector, and a fifth semiconductor layer is placed in the sixth, seventh, and eighth semiconductor layers. A heterojunction bipolar transistor in which the formed high concentration impurity region of the second conductivity type is used as a base contact region, a portion other than the base contact region in the sixth semiconductor layer is used as a base, and a portion other than the base contact region in the seventh semiconductor layer is used as an emitter. An optical/electronic integrated circuit characterized by comprising: (2) The opto-electronic integrated circuit according to claim 1, wherein the first conductivity type is n type and the second conductivity type is p type. (3) The first, third, and seventh semiconductor layers are AlGaAs, the second, fourth, fifth, and eighth semiconductor layers are GaAs, and the sixth semiconductor layer is GaAs or AlGaAs. An optical/electronic integrated circuit according to claim 1. (4) The first, third, and seventh semiconductor layers are InP, and the second, fourth, fifth, and eighth semiconductor layers are InGaAs or InGa.
2. The opto-electronic integrated circuit according to claim 1, wherein the sixth semiconductor layer is InP, InGaAs, or InGaAsP. (5) The sixth semiconductor layer has an Al composition of 0 at the connection part with the fifth semiconductor layer and an Al composition of A at the connection part with the seventh semiconductor layer.
4. The opto-electronic integrated circuit according to claim 3, wherein the optical/electronic integrated circuit is made of AlGaAs in which the Al composition changes sequentially so that the l composition is equal to the Al composition of the seventh semiconductor layer. (6) The opto-electronic integrated circuit according to claim 1, wherein the semi-insulating substrate is GaAs or InP. (7) A first semiconductor layer of a first conductivity type, a second semiconductor layer of a first conductivity type having a narrow gap compared to the first semiconductor layer, and a second semiconductor layer on a semi-insulating substrate. A first multilayer epitaxial film is formed by sequentially stacking a third semiconductor layer of a first conductivity type with a wide gap compared to the first multilayer epitaxial film. 1st
and a lateral junction stripe laser having a third semiconductor layer as a cladding layer, a fourth semiconductor layer having a high concentration impurity of the first conductivity type on the first multilayer epitaxial film, and a fifth semiconductor layer of the first conductivity type. a semiconductor layer of the second conductivity type, a sixth semiconductor layer of the second conductivity type, and a first semiconductor layer having a wider gap than the sixth semiconductor layer.
A second multilayer epitaxial film is formed by sequentially stacking a seventh semiconductor layer of a conductivity type and an eighth semiconductor layer having a high concentration of impurities of a first conductivity type, and a sixth, seventh, and eighth semiconductor layer are formed. A second conductivity type high concentration impurity region is selectively formed within the collector, sixth, seventh, and eighth semiconductor layers using ion implantation or vapor phase diffusion, and a fifth semiconductor layer is formed within the collector, sixth, seventh, and eighth semiconductor layers. The second
The high concentration impurity region of the conductivity type is a base contact region, the area other than the base contact region in the sixth semiconductor layer is a base,
A method for manufacturing an opto-electronic integrated circuit, comprising configuring a heterojunction bipolar transistor having an emitter in a region other than the base contact region in the seventh semiconductor layer. (8) The method for manufacturing an optoelectronic integrated circuit according to claim 7, wherein the first conductivity type is n type and the second conductivity type is p type. (9) The first, third, and seventh semiconductor layers are AlGaAs, the second, fourth, fifth, and eighth semiconductor layers are GaAs, and the sixth semiconductor layer is GaAs or AlGaAs. A method for manufacturing an opto-electronic integrated circuit according to claim 7. (10) The first, third, and seventh semiconductor layers are InP;
The fourth, fifth, and eighth semiconductor layers are InGaAs or InG.
8. The method of manufacturing an opto-electronic integrated circuit according to claim 7, wherein the aAsP and the sixth semiconductor layer are InP, InGaAs, or InGaAsP. (11) The Al composition of the sixth semiconductor layer is 0 at the connection part with the fifth semiconductor layer, and the Al composition of the sixth semiconductor layer is equal to the Al composition of the seventh semiconductor layer. 10. The method of manufacturing an opto-electronic integrated circuit according to claim 9, wherein the Al GaAs is used in which the Al composition changes sequentially so that the Al composition changes sequentially. (12) The method for manufacturing an opto-electronic integrated circuit according to claim 7, wherein the semi-insulating substrate is GaAs or InP.