JPH0727086B2 - Optoelectronic integrated circuit device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optoelectronic integrated circuit element used in an optical communication system or an electronic computer system, and more particularly to improvement of an integrated structure of an optical waveguide layer and a photodetection layer. .

[Prior Art] An optoelectronic integrated circuit device formed by integrating an optical device and an electronic device has great advantages in terms of high performance and low cost of the device in an optical communication system or an electronic computer system. , Active research is currently being conducted.

An optoelectronic integrated circuit element used in an optical communication system includes a light emitting element that serves as a light source, an optical waveguide layer (optical waveguide) that transmits light, and a photodetector element (light receiving element) that detects light and converts it into an electrical signal. Are formed in a single chip on one substrate. The light emitting element uses a III-V group compound semiconductor such as GaAs, AlGaAs, and InP, and the optical waveguide includes SiO ₂ , SiN, Si ₃ N ₄ , LiNbO ₃
Using a translucent insulator such as
They are manufactured using semiconductors such as Si, Ge and InGaAs.

Regarding the structure and material of the optoelectronic integrated circuit element, for example, JP-A-61-32804, JP-A-61-121014, and JP-A-61-133911.
No. etc.

Japanese Patent Laid-Open No. 61-32804 has an optical waveguide layer and a light receiving layer on a substrate, and an end portion for totally reflecting guided light to the substrate side at a terminal end portion of a portion of the optical waveguide layer to be an optical waveguide, Alternatively, a metal layer is provided on the back surface of the substrate, the guided light propagating through the optical waveguide is totally reflected at the end portion for totally reflecting the light on the back surface of the substrate, and the light receiving portion is irradiated with the metal layer. It is described that the light receiving portion is Pn-junctioned by impurity diffusion.

Japanese Laid-Open Patent Publication No. 61-121014 discloses an optical wiring board (Si) in which an optical waveguide and a V-shaped groove are formed for optical coupling between a light emitting element and a light receiving element.
O ₂ ).

In Japanese Patent Laid-Open No. 61-133911, a light emitting element, a light receiving element, and an optical waveguide are coupled on a substrate near the end of the optical waveguide with a micro-reflecting mirror that makes an angle of 45 ° with the substrate surface. And that a Si avalanche photodiode is used for the light receiving element.

[Problems to be solved by the invention]

In the above-mentioned conventional technique, the optical waveguide layer and the photodetection layer are integrated in separate layers, and in order to accurately guide the light propagating through the optical waveguide layer to the photodetection layer, a new method is required. It is necessary to adjust the light path with an optical waveguide or a reflector. Therefore, there is a limit in improving the light receiving efficiency of the photodetection layer and the integration of elements. In addition, since the optical waveguide layer and the photodetection layer are made of different materials, and the photodetection layer Si diffuses impurities to form a Pn junction, the manufacturing process becomes complicated and the cost becomes high.

An object of the present invention is to provide an optoelectronic integrated circuit device which has a good light receiving efficiency of the photodetection layer, enables high-density integration of the device, and is inexpensive.

[Means for solving problems]

Before describing the means for solving the problem, the background of the completion of the present invention will be described.

The present invention uses silicon carbide (SiC) as a target and Si _1-X C _X obtained by sputtering in argon has an optical index of 3.2 to 3.4 and an extinction coefficient of 0.1 or less at a wavelength of 0.83 μm. Since it exhibits high refractive index and low light absorption characteristics, it is effective as an optical waveguide layer. Electrically, the specific resistance before dielectric breakdown is about 10 ³ to 10 ¹⁰ Ωcm,
After breaking the insulator, it drops to 10 ⁴ to 10 ⁶ Ω · cm, and since it has photoconductivity only at the location where the dielectric breakdown occurs, it is also used for the photodetection layer.

By utilizing this phenomenon, the photodetection layer can be formed in the optical waveguide layer, and the present invention has been made on the basis of such knowledge, and the contents thereof are one chip and the optical waveguide and the photodetection element. An optoelectronic integrated circuit element to be formed, wherein the optical waveguide layer and the photodetecting element are integrally formed in a single layer.

In an optical communication system or a computer system, since the wavelength of a light source used is in a wide range from the visible region to the infrared region, it is necessary to adjust the optical characteristics of the optical waveguide layer. Therefore, the Si _1-X C _X film contains oxygen, nitrogen,
By adding fluorine, etc., Si _1-X C _X O _Y , Si _1-X C _X N _Y , Si
_1-X C _X F _Y (provided that X> Y, and X is 0.05 to 0.9 in atomic ratio)
(5, Y is 0.05 to 0.5) to form a film, which increases translucency and lowers the refractive index. Therefore, it is possible to adjust the optical characteristics of the optical waveguide by appropriately using these films.

The Si _1-X C _X O _Y , Si _1-X C _X N _Y , Si _1-X C _X F _Y film and the like are the Si _1-X
Obtained by the same formation method as the C _X film, and argon and oxygen (1 to 5% by weight), argon and nitrogen (1 to 5%) in the sputtering gas.
%), And a mixed gas of argon and fluorine (1 to 5% by weight).

If the concentrations of oxygen, nitrogen, and fluorine in these sputter rings are further increased, Si _1-X O _X C _Y , Si _1-X N _X C _Y , Si _1-X F _X C _Y (where X> Y , Atomic ratio X is 0.05 to 0.95, Y is 0.05
A film is formed, and the refractive index can be reduced.
Therefore, the Si _1-X O _X C _Y , Si _1-X N _X C _Y , and Si _1-X F _X C _Y films are used for the cladding layer surrounding the optical waveguide layer.

[Action]

By integrating the optical waveguide layer and the photodetection layer of the optoelectronic integrated circuit element in the same layer, the light propagating in the optical waveguide layer can be efficiently coupled to the photodetection layer. Moreover, it is not necessary to separately provide a layer serving as a photodetection portion, and the integration density is increased accordingly. As a result, optical signals can be efficiently converted into electrical signals, and high density integration of elements and cost reduction can be achieved.

〔Example〕

 Next, examples of the present invention will be described.

FIG. 1 is a sectional view of an optoelectronic integrated circuit device in which an optical waveguide layer and a photodetection layer according to an embodiment of the present invention are integrated. In FIG. 1, a cladding / electrode layer 2 and an optical waveguide layer 3 are sequentially laminated on a transparent insulating substrate 1, and then a mask is applied to a portion to be an electrode layer to form a cladding layer 4. afterwards,
The mask is removed, and the electrode layer 5 is laminated on the optical waveguide layer 3.

The transparent insulating substrate 1 is made of glass, quartz, or plastic.

The cladding / electrode layer 2 has translucency and conductivity
In ₂ O _3, SnO ₂ or In ₂ O ₃ + SnO ₂ film is used, In ₂ O _3, S
It can be obtained by using a material such as nO ₂ or In ₂ O ₃ + SnO ₂ as a target and performing sputtering in a mixed gas of argon and oxygen. The thickness is about 5 to 30 μm and the refractive index is smaller than that of the optical wave layer 3.

The optical waveguide layer 3 is made of silicon carbide (SiC) as a target, and Si obtained in argon gas by sputtering.
_1-X C _X film obtained in a mixed gas of argon and oxygen (1 to 5 wt%) Si _1-X C _X O _Y film obtained in a mixed gas of argon and nitrogen (1 to 5 wt%) Si _1-X C _X N _Y film obtained, Si obtained in a mixed gas of argon and fluorine (1 to 5% by weight)
Either _1-X C _X F _Y film is used. At this time, the optical waveguide layer 3
The film thickness of is adjusted within the range of about 1 to 30 μm.

Kuratsudo layer 4, the refractive index than the optical waveguide layer 3 is less Si _1-X O
_{An X} C _Y , Si _1-X N _X C _Y , Si _1-X F _X C _Y film is formed to a film thickness of about 5 to 30 μm by the same method as that of the optical waveguide layer 3. At this time, the sputtering gas is argon and oxygen (5 to 20% by weight) in the case of the Si _1-X O _X C _Y film, and argon and nitrogen (in the case of the Si _1-X N _X C _Y film). 5 to 20% by weight), and in the case of the Si _1-X F _X C _Y film, a mixed gas of argon and fluorine (5 to 20% by weight) is used, respectively. The optical waveguide layer 3 and the cladding layer 4 can be continuously formed by using silicon carbide (SiC) as a target and changing the composition ratio in the sputtering gas.

The electrode layer 5 uses a metal film of Al, Ag, Au, W, Mo, etc., and has a film thickness of 10
It is formed to about 70 μm. The manufacturing method is a sputtering method or a vacuum evaporation method.

The light detection layer 3A is obtained by applying a voltage of several tens to several hundreds of volts between the cladding / electrode layer 2 and the electrode layer 5 to cause dielectric breakdown of the optical waveguide layer 3.

FIG. 2 shows the relationship between the composition ratio of C and O, the refractive index, and the specific resistance in Si _X C _Y O _Z before dielectric breakdown. As SiC changes to SiO ₂ , the refractive index decreases from 3.4 to 1.4, while the specific resistance
It becomes as high as 10 ³ to 10 ¹² Ω · cm. However, after the dielectric breakdown, as shown in FIG. 3, the refractive index does not change and the specific resistance decreases by about 4 digits. In SiC, it drops to about 10 ⁵ Ω · cm, the semiconductor-like properties become remarkable, and photosensitivity appears.
Therefore, it can be seen that the dielectric breakdown portion is used as the photodetection layer.

In the optoelectronic integrated circuit element according to the present embodiment described above, the light propagating in the optical waveguide layer is detected in the same layer and can be efficiently converted into an electric signal.

FIG. 4 shows a second embodiment of the present invention and is a sectional view of an optoelectronic integrated circuit device in which a light emitting layer, an optical waveguide layer and a photodetecting layer are integrated.

In FIG. 4, an insulating layer 7 is provided on one side of a semiconductor substrate 6, and a cladding / electrode layer 2, an optical waveguide layer 3, and a cladding layer are provided on the insulating layer 7.
4, the electrode layer 5 is sequentially laminated, and on one side of the semiconductor substrate 6,
The device structure has an n-type semiconductor layer 8 and a p-type semiconductor layer 9. A single crystal of Si or GaAs is used for the semiconductor substrate 6. As the insulating layer 7, a film of SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ , AlN, CaF ₂ or the like is used, and the thickness is 5 to 30 by a sputtering method or a vacuum deposition method.
It is formed with a film thickness of about μm. The insulating layer 7 is provided because
This is for the purpose of insulating the semiconductor substrate 6 and preventing light in the optical waveguide layer 3 from leaking to the side of the semiconductor substrate 6 having a high refractive index (refractive index: semiconductor substrate 6> insulating layer 7). Cladding source electrode layer 2, optical waveguide layer 3, cladding layer 4, electrode layer 5, photodetection layer
3A is formed by the material and method described in FIG. n
The p-type semiconductor layer 8 and the p-type semiconductor layer 9 are made of GaAs, AlGaAs, In
III-V group compounds such as GaAsP and Inp are used, and the composition ratio is changed to n-type and p-type. The fabrication method is molecular beam epitaxy (Mo
lecular Beam Epitaxy (MBE) method or Metal Organics Chemical Vapor Deposition: M
OCVD) to obtain a single crystal growth film. Since the light emitting portion is the interface between the n-type semiconductor layer 8 and the p-type semiconductor layer 9, the film thickness is controlled so that the interface comes to the end of the optical waveguide layer 3. The optoelectronic integrated circuit device manufactured as described above emits light by applying a forward voltage to the n-type semiconductor layer and the p-type semiconductor layer, which are light emitting layers, and is totally reflected at the interface between the optical waveguide layer and the cladding layer. Light is propagated in the optical waveguide layer. The propagated light is efficiently converted into an electric signal in the photodetection layer of the optical waveguide layer.

As described above, according to this embodiment, the optical waveguide layer is made of Si.
_1-X C _X , Si _1-X C _X O _Y , Si _1-X C _X N _Y , Si _1-X C _X F _Y By using a film, it is possible to detect light in the same layer as the optical waveguide layer. The layers can be easily formed. Further, the optical waveguide layer, the photodetection layer and the cladding layer can be continuously manufactured by changing the composition ratio of the sputtering gas by the same sputtering target.

Next, a third embodiment of the present invention will be described. The first and second embodiments described above are two-dimensionally integrated optoelectronic integrated circuit devices. On the other hand, in the third embodiment, a plurality of optoelectronic integrated circuit elements are three-dimensionally integrated.

FIG. 5 is an enlarged perspective view of a part of the optoelectronic integrated circuit device according to the third embodiment.

In FIG. 5, a first optoelectronic integrated circuit element layer 10 and a second optoelectronic integrated circuit element layer 1 are provided on a transparent low refractive index substrate 1.
The first and third optoelectronic integrated circuit element layers 12 are sequentially provided. Each layer is formed in a step shape in order to take out the external electrodes of the electrode layer 5 and the cladding / electrode layer 2 on the photodetection layer 3A, and to insulate the electrodes from each other. FIG. 6 shows the fifth
It is sectional drawing of the optoelectronic integrated circuit element of a figure. In FIG. 6, the first, second and third optoelectronic integrated circuit element layers 10, 11, 12 on the transparent low refractive index substrate 1 are the cladding / electrode layer 2,
The optical waveguide layer 3, the photodetection layer 3A, the cladding layer 4, and the electrode layer 5 are produced by the materials and methods described in the above invention. The step shape between each layer and the electrode layer 5 are formed by masking by a photoresist technique. The thickness of each layer is about 5 to 30 μm for the cladding / electrode layer 2 and 1 to 30 μm for the optical waveguide layer 3.
m, the electrode layer 5 is about 1 to 100 μm, and the Kratz layer 4 is 10
Approximately 100 μm.

The optoelectronic integrated circuit device according to this embodiment can simultaneously propagate and receive a plurality of optical signals in each device layer. Furthermore, since the photodetection layer is integrated in the optical waveguide layer, the device can be manufactured with a simple structure and process even with a three-dimensional circuit configuration. Furthermore, by integrating optoelectronic integrated circuit elements three-dimensionally, ultra-high density integration becomes possible, and by optical communication, superelectric density integration becomes possible, enabling large-capacity information processing in optical communication and electronic computers. it can.

〔The invention's effect〕

As described above, according to the present invention, since the photodetection layer (photodetection element) can be formed in the same layer as the optical waveguide layer, the light propagating in the optical waveguide layer can be efficiently detected. The optical signal can be efficiently converted into an electrical signal by improving the light receiving efficiency of the optical ticket seed layer.

In addition, a separate optical waveguide or a reflector for coupling the light propagating in the optical waveguide layer to the photodetection layer is not required, which enables high-density integration and inexpensive manufacturing.

[Brief description of drawings]

FIG. 1 is a sectional view of an optoelectronic integrated circuit device in which an optical waveguide layer and a photodetection layer according to an embodiment of the present invention are integrated, and FIG.
A graph showing the relationship between the composition ratio of C and O and the refractive index in Si _X C _Y O _Z , and Fig. 3 shows C in Si _X C _Y O _Z after dielectric breakdown.
And FIG. 4 is a graph showing the relationship between the composition ratio of O and O and the refractive index, and FIG. 4 is a sectional view of an optoelectronic integrated circuit device in which a light emitting layer, an optical waveguide layer and a photodetecting layer according to a second embodiment of the present invention are integrated. 5 is a partially exploded perspective view of a stack of a plurality of optoelectronic integrated circuit elements according to a third embodiment of the present invention, and FIG. 6 is a sectional view of FIG. 1 ... Transparent insulating substrate, 2 ... Cladding and electrode layer, 3 ...
Optical waveguide layer, 3A ... Photodetection layer, 4 ... Cladding layer, 5 ...
Electrode layer, 6 ... Semiconductor substrate, 7 ... Insulating layer, 8 ... N-type semiconductor layer, 9 ... P-type semiconductor layer.

Claims (1)

[Claims] 1. An optoelectronic integrated circuit device comprising an optical waveguide and a photo-detecting element formed in one chip, wherein the optical waveguide is Si _1-X C _X , Si _1-X C _X O _Y , Si _1-X C _X N _Y or Si _1-X C _X F
_Y (provided that X> Y, and X is 0.05 to 0.95 in atomic ratio,
Y is 0.05 to 0.5), and the photodetector element is composed of a layer in which a part of the optical waveguide is dielectrically broken down, and the optical waveguide and the photodetector element are integrally formed in a single layer. An optoelectronic integrated circuit device characterized by: