阅读说明：本技术 电吸收调制激光器各功能区电隔离的实现方法 (Method for realizing electric isolation of functional areas of electric absorption modulation laser ) 是由 周代兵 梁松 赵玲娟 王圩 于 2020-12-23 设计创作，主要内容包括：本发明公开了一种电吸收调制激光器各功能区电隔离的实现方法,包括：在衬底表面上依次生长缓冲层和有源层,其中,有源层包括第一有源层和作为激光器区有源层的第二有源层；刻蚀掉第一有源层,并对接生长调制器区有源层；在作为激光器区有源层的第二有源层上制作光栅；在调制器区有源层上和作为激光器区有源层的第二有源层上依次生长包层和接触层,并利用包层和接触层制作脊型波导；刻蚀掉脊型波导两侧的调制器区有源层,得到刻蚀后剩余的调制器区有源层；刻蚀掉调制器区和激光器区之间的接触层,并进行氦离子注入,形成电隔离沟；制作调制器区和激光器区的P型电极,以及对衬底背面进行减薄后制作N型电极。(The invention discloses a method for realizing electric isolation of each functional area of an electric absorption modulation laser, which comprises the following steps: sequentially growing a buffer layer and an active layer on the surface of the substrate, wherein the active layer comprises a first active layer and a second active layer serving as an active layer of a laser region; etching the first active layer, and butt-growing the modulator region active layer; manufacturing a grating on a second active layer serving as an active layer of the laser region; sequentially growing a cladding layer and a contact layer on the modulator region active layer and a second active layer serving as a laser region active layer, and manufacturing a ridge waveguide by using the cladding layer and the contact layer; etching the modulator region active layers on two sides of the ridge waveguide to obtain the remaining modulator region active layers after etching; etching off a contact layer between the modulator area and the laser area, and performing helium ion implantation to form an electrical isolation trench; and manufacturing P-type electrodes of the modulator area and the laser area, and manufacturing an N-type electrode after thinning the back surface of the substrate.)

1. A method for realizing electric isolation of functional areas of an electric absorption modulation laser comprises the following steps:

sequentially growing a buffer layer and an active layer on the surface of a substrate, wherein the active layer comprises a first active layer and a second active layer serving as an active layer of a laser region;

etching the first active layer, and butt-growing the modulator region active layer;

manufacturing a grating on the second active layer serving as the laser region active layer;

growing a cladding layer and a contact layer on the modulator region active layer and the second active layer serving as the laser region active layer in sequence, and manufacturing a ridge waveguide by using the cladding layer and the contact layer;

etching the modulator region active layers on two sides of the ridge waveguide to obtain the remaining modulator region active layers after etching;

etching the contact layer between the modulator region and the laser region, and performing helium ion implantation to form an electrical isolation trench;

and manufacturing P-type electrodes of the modulator area and the laser area, and manufacturing an N-type electrode after thinning the back of the substrate.

2. A method as claimed in claim 1 wherein the modulator region active layer has a bandgap wavelength less than the bandgap wavelength of the second active layer which is the laser region active layer.

3. The method of claim 1 wherein the functional regions of the electroabsorption modulated laser are electrically isolated from each other,

the modulator region active layers which are remained after etching are respectively positioned at two sides of the ridge waveguide;

the width of the modulator region active layer left after etching on each side is larger than that of the ridge waveguide.

4. The method of claim 1 wherein the functional regions of the electroabsorption modulated laser are electrically isolated from each other,

the active layer comprises a grating layer and a multi-quantum well;

the uppermost part of the active layer is a grating layer used for manufacturing grating materials; the multiple quantum wells are arranged below the grating layer.

5. The method of claim 4 wherein the functional regions of the electro-absorption modulated laser are electrically isolated from each other,

the grating layer is InGaAsP; the multiple quantum wells are made of the same material and are InGaAsP or InGaAlAs.

6. The method of claim 5 wherein the functional regions of the electroabsorption modulated laser are electrically isolated from each other,

the multiple quantum well includes a first respective confinement layer, a second respective confinement layer, and a multiple quantum well layer between the first respective confinement layer and the second respective confinement layer.

7. The method of claim 1 wherein the functional regions of the electroabsorption modulated laser are electrically isolated from each other,

the modulator region active layer comprises a plurality of quantum wells which are arranged in a stacked mode, wherein the quantum wells are made of the same material and are InGaAsP or InGaAlAs.

8. The method of claim 7 wherein the functional regions of the electroabsorption modulated laser are electrically isolated from each other,

the quantum well comprises a third confinement layer, a fourth confinement layer, and a multi-quantum well layer between the third confinement layer and the fourth confinement layer.

9. The method of claim 1, wherein the cladding layer is a P-doped InP layer with a thickness of 1.5-1.8 μm; the contact layer is a P-type doped InGaAs layer, and the thickness of the contact layer is 180-220 nm.

10. The method of claim 1, wherein the etching comprises inductively coupled plasma etching or dry etching.

Technical Field

The invention relates to the field of optoelectronic devices, in particular to a method for realizing electrical isolation of each functional area of an electroabsorption modulated laser.

Background

With the wide application of the electro-absorption modulated laser (EML) in the optical communication system and the increasing requirements of people on data transmission and processing in the optical communication system, higher requirements are put on the performance of the EML laser chip, especially the electrical isolation between the modulator and the laser, which directly affects the spectral line width of the EML laser chip and the thermal crosstalk between the EML laser chips. In general electrical isolation, a contact layer between a laser and a modulator is removed by etching, helium ion implantation is performed, electrical isolation between two functional devices is realized, and isolation resistance of the device can reach dozens of kilo-ohm magnitude. Isolation of several tens of kilo-ohms is not effective in preventing thermal and electrical crosstalk between the laser and modulator, and only line widths greater than 100MHz can be achieved.

Disclosure of Invention

In view of this, in order to avoid adverse effects caused by thermal crosstalk and electrical crosstalk between the laser and the modulator, the present invention provides a method for implementing electrical isolation of each functional region of the electroabsorption modulated laser, so as to implement an isolation resistance greater than 200 kilo ohms, effectively implement thermal isolation and electrical isolation, and improve the performance of the spectral line width of the electroabsorption modulated laser chip.

In order to achieve the above object, the present invention provides a method for electrically isolating functional regions of an electroabsorption modulated laser, including: sequentially growing a buffer layer and an active layer on the surface of the substrate, wherein the active layer comprises a first active layer and a second active layer serving as an active layer of a laser region; etching the first active layer, and butt-growing the modulator region active layer; manufacturing a grating on a second active layer serving as an active layer of the laser region; sequentially growing a cladding layer and a contact layer on the modulator region active layer and a second active layer serving as a laser region active layer, and manufacturing a ridge waveguide by using the cladding layer and the contact layer; etching the modulator region active layers on two sides of the ridge waveguide to obtain the remaining modulator region active layers after etching; etching off a contact layer between the modulator area and the laser area, and performing helium ion implantation to form an electrical isolation trench; and manufacturing P-type electrodes of the modulator area and the laser area, and manufacturing an N-type electrode after thinning the back surface of the substrate.

According to an embodiment of the invention, wherein the band gap wavelength of the modulator region active layer is smaller than the band gap wavelength of the second active layer being the laser region active layer.

According to the embodiment of the invention, the active layers of the modulator region which are left after etching are respectively positioned at two sides of the ridge waveguide; the width of the modulator region active layer remaining after each side is etched is greater than the width of the ridge waveguide.

According to an embodiment of the present invention, wherein the active layer includes a grating layer and a multiple quantum well; the uppermost part of the active layer is a grating layer used for manufacturing grating materials; multiple quantum wells are under the grating layer.

According to the embodiment of the invention, the grating layer is InGaAsP; the multiple quantum wells are of the same material and are InGaAsP or InGaAlAs.

According to an embodiment of the present invention, wherein the multiple quantum well includes a first separate confinement layer, a second separate confinement layer, and a multiple quantum well layer between the first separate confinement layer and the second separate confinement layer.

According to an embodiment of the invention, the modulator region active layer comprises a plurality of quantum wells arranged in a stack, the quantum wells being of the same material and being InGaAsP or InGaAlAs.

According to an embodiment of the present invention, wherein the quantum well comprises a third confinement layer, a fourth confinement layer and a multi-quantum well layer between the third confinement layer and the fourth confinement layer.

According to the embodiment of the invention, the cladding layer is a P-type doped InP layer with the thickness of 1.5-1.8 μm; the contact layer is a P-type doped InGaAs layer with a thickness of 180-220 nm.

According to the embodiment of the invention, the etching comprises inductively coupled plasma etching and dry etching.

According to the method for realizing the electrical isolation of each functional area of the electro-absorption modulated laser, provided by the invention, the active layers on the two sides of the ridge waveguide in the modulator area are removed by etching, then the contact layer between the modulator area and the laser area is etched, and helium ion injection is carried out, so that the electrical isolation degree of more than 200 kilo-ohm can be realized, the adverse effects caused by thermal crosstalk and electrical crosstalk between the modulator and the laser are avoided, the thermal isolation and the electrical isolation are effectively realized, the line width of less than 9MHz is obtained, and the performance of the spectral line width of an electro-absorption modulated laser chip is improved.

Drawings

FIG. 1 is a schematic flow chart of a method for electrically isolating functional regions of an electroabsorption modulated laser according to an embodiment of the present invention;

fig. 2 schematically shows a structural diagram for realizing electrical isolation of functional regions of the electroabsorption modulated laser according to the embodiment of the invention.

Detailed Description

In order that the objects, technical solutions and advantages of the present invention will become more apparent, the present invention will be further described in detail with reference to the accompanying drawings in conjunction with the following specific embodiments.

In order to avoid adverse effects of electric crosstalk and thermal crosstalk between functional areas of the electric absorption modulation laser on the electric absorption modulation laser, the electric isolation degree of more than 200 kilo ohms is realized, and the performance of the spectral line width of an electric absorption modulation laser chip is improved. The structure of the electroabsorption modulated laser realizing the electrical isolation and the specific implementation method flow thereof can refer to fig. 1 and fig. 2.

FIG. 1 is a schematic flow chart of a method for electrically isolating functional regions of an electroabsorption modulated laser according to an embodiment of the present invention; fig. 2 schematically shows a structural diagram for realizing electrical isolation of functional regions of the electroabsorption modulated laser according to the embodiment of the invention. The implementation method is specifically described with reference to fig. 1 and 2.

As shown in fig. 1 and 2, the implementation method includes operations S101 to S107.

In operation S101, a buffer layer and an active layer are sequentially grown on a surface of a substrate, wherein the active layer includes a first active layer and a second active layer that is an active layer of a laser region.

In an embodiment of the present invention, an electroabsorption modulated laser includes a laser portion (LD) and an electroabsorption modulator portion (EAM), and mask patterns of the laser portion and the electroabsorption modulator portion are respectively engraved on a substrate 10.

According to an embodiment of the present invention, after mask patterns of the laser portion and the electro-absorption modulator portion are etched, the buffer layer 20 and the active layer are epitaxially grown at the same time. The substrate 10 and the buffer layer 20 may be an InP-based material system, among others.

According to an embodiment of the present invention, the active layer includes a first active layer and a second active layer 30 as an active layer of the laser region, wherein the first active layer is an active layer outside the laser region, including a modulator portion and a portion between the modulator and the laser.

According to the embodiment of the present invention, the first active layer and the second active layer 30 as the active layer of the laser region are the same active layer, including the grating layer and the quantum well, and the uppermost part is the grating layer for making the grating; and a multi-quantum well is arranged below the grating layer and comprises a first respective limiting layer, a second respective limiting layer and a multi-quantum well layer between the first respective limiting layer and the second respective limiting layer. The first respective confinement layer is an upper respective confinement layer in the quantum well, and the second respective confinement layer is a lower respective confinement layer in the quantum well.

According to the embodiment of the invention, the grating layer is InGaAsP; the quantum wells are of the same material, InGaAsP or InGaAlAs. The quantum well active layer comprises at least one quantum well active layer and a barrier layer.

In operation S102, the first active layer is etched away and the modulator region active layer is grown in an abutting manner.

According to an embodiment of the invention, after the active layer outside the laser region, i.e. the first active layer, has been removed by selective etching through a silicon dioxide mask, the modulator region is epitaxially grown using a butting technique, with the modulator region active layer 40 being grown butting the laser region.

According to an embodiment of the present invention, the modulator active layer 40 is a multiple quantum well active layer composed of a plurality of quantum wells arranged in a stack, including a third confinement layer, a fourth confinement layer, and a multiple quantum well layer between the third confinement layer and the fourth confinement layer. The third respective confinement layer is an upper respective confinement layer in the quantum well, and the fourth respective confinement layer is a lower respective confinement layer in the quantum well. The multiple quantum well active layers are made of the same material and are InGaAsP or InGaAlAs. The multiple quantum well active layer comprises at least one quantum well active layer and a barrier layer.

According to an embodiment of the present invention, the band gap wavelength of the modulator active layer 40 is smaller than that of the second active layer 30 as the laser region active layer

In operation S103, a grating is fabricated on the second active layer, which is the laser region active layer.

In the embodiment of the present invention, the grating 50 may be formed by etching the second active layer 30, which is the active layer of the laser region, by using electron beam etching, focused ion beam etching, or the like.

In operation S104, a cladding layer and a contact layer are sequentially grown on the modulator region active layer and the second active layer as the laser region active layer, and a ridge waveguide is fabricated using the cladding layer and the contact layer.

According to an embodiment of the present invention, the cladding layer 60 and the contact layer 70 are epitaxially grown simultaneously in sequence on the modulator region active layer 40 and on the second active layer 30 as the laser region active layer. Wherein the cladding layer 60 is a P-type doped InP layer with the thickness of 1.5-1.8 μm; the contact layer 70 is a P-type doped InGaAs layer with a thickness of 180-220 nm.

According to the embodiment of the invention, the cladding layer 60 and the contact layer 70 are subjected to photoetching through a traditional photoetching process, part of the cladding layer and the contact layer are removed, and the cladding layer and the contact layer with the width of 3-5 mu m are remained, so that the ridge waveguide with the width of 3-5 mu m is formed.

In operation S105, the modulator region active layers on both sides of the ridge waveguide are etched away, resulting in the modulator region active layers remaining after etching.

According to the embodiment of the invention, after the ridge waveguide is manufactured by photoetching the cladding layer and the contact layer through the traditional photoetching process, the active layers on two sides of the ridge waveguide are the modulator region active layer 40 and the second active layer 30 serving as the laser region active layer respectively.

According to the embodiment of the invention, the modulator region active layers 40 on both sides of the ridge waveguide are etched by adopting a silicon dioxide mask inductively coupled plasma etching technology, the modulator region active layers 40 on both sides of the ridge waveguide are removed, and a part of modulator region active layers close to both sides of the ridge waveguide, namely the modulator region active layer 80 left after etching, is reserved. Wherein the etching may further include dry etching.

According to an embodiment of the present invention, the width of the modulator region active layer 80 remaining after the etching on each side is greater than the width of the ridge waveguide.

In operation S106, the contact layer between the modulator region and the laser region is etched away, and helium ion implantation is performed to form an electrical isolation trench.

According to an embodiment of the present invention, the contact layer between the laser region and the device region is etched away by using an inductively coupled plasma etcher.

According to an embodiment of the present invention, helium ion implantation is performed where the contact layer between the modulator region and the laser region is etched away, such that a helium ion beam passes through the cladding layer 60 through each growth layer below the cladding layer until the speed is slowly reduced by being resisted by each growth layer and finally stays in a certain growth layer, forming an electrical isolation trench 90.

According to the embodiment of the invention, when helium ion beams pass through the growth layers below the cladding layer through the cladding layer, the active layer 40 of the modulator region is partially etched away, so that the electric crosstalk caused by the P-type doping diffusing into the laser region and the active layer part of the modulator region is avoided, and the adverse effects caused by the thermal crosstalk and the electric crosstalk between the modulator and the laser are further eliminated.

In operation S107, P-type electrodes of the modulator region and the laser region are fabricated, and an N-type electrode is fabricated after thinning the back surface of the substrate.

According to the embodiment of the invention, the P-type electrodes are manufactured in the modulator area and the laser area by utilizing a photoetching and electroplating method; and then sealing the front side of the laser with the device, mechanically grinding the back side of the substrate to thin the substrate, and forming a large-area back N-type electrode by utilizing a photoetching and electroplating mode. And finishing the manufacture of the electric absorption modulation laser and realizing the electric isolation of each functional area of the electric absorption modulation laser, wherein the electric isolation is more than 200 kilo ohms.

According to the embodiment of the invention, the active layers on two sides of the ridge waveguide in the modulator area are removed by etching, then the contact layer between the modulator area and the laser area is etched, and He ion implantation is carried out, so that the electrical isolation degree of more than 200 kilo-ohm can be realized, the adverse effects caused by thermal crosstalk and electrical crosstalk between the modulator and the laser are avoided, the thermal isolation and the electrical isolation are effectively realized, the line width of less than 9MHz is obtained, and the performance of the spectral line width of the chip of the electro-absorption modulated laser is improved.

It will be appreciated by a person skilled in the art that various combinations and/or combinations of features recited in the various embodiments and/or claims of the present invention are possible, even if such combinations or combinations are not explicitly recited in the present invention. In particular, various combinations and/or combinations of the features recited in the various embodiments and/or claims of the present invention may be made without departing from the spirit or teaching of the invention. All such combinations and/or associations fall within the scope of the present invention.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.