CN112636162A

CN112636162A - Packaging structure and packaging method of semiconductor laser

Info

Publication number: CN112636162A
Application number: CN202011511301.2A
Authority: CN
Inventors: 毛虎; 邱智贤; 毛森; 焦英豪
Original assignee: Lewei Semiconductor Technology Jiaxing Co ltd
Current assignee: Lewei Semiconductor Technology Jiaxing Co ltd
Priority date: 2020-12-18
Filing date: 2020-12-18
Publication date: 2021-04-09

Abstract

The invention provides a packaging structure of a semiconductor laser and a packaging method thereof, wherein the packaging structure of the semiconductor laser comprises the semiconductor laser, a semiconductor refrigerator and a metal layer arranged between the semiconductor laser and the semiconductor refrigerator, the semiconductor refrigerator comprises a silicon substrate, a metal electrode arranged on the silicon substrate, a semiconductor thermoelectric material deposited on the metal electrode and a P-N structure etched on the semiconductor thermoelectric material, and the semiconductor laser comprises a first electrode, a second electrode, a substrate arranged between the first electrode and the second electrode and sequentially arranged from the first electrode to the second electrode, a first limiting layer, a first waveguide layer, an active region, a second waveguide layer, a second limiting layer, an ohmic contact layer and a transmission grating layer contacted with the second limiting layer. The invention reduces the volume of the packaged semiconductor laser and improves the performance of the laser.

Description

Packaging structure and packaging method of semiconductor laser

Technical Field

The invention relates to the technical field of semiconductor photoelectricity, in particular to a packaging structure of a semiconductor laser and a packaging method thereof.

Background

With the development of laser technology, a new application subject, namely laser medicine, is gradually formed, and the unique advantages of laser are achieved, so that many problems which cannot be solved in basic research and clinical application of traditional medicine are solved, and the attention of medical circles at home and abroad is aroused. Semiconductor lasers (DL) are particularly suitable for the manufacture of medical devices due to their small size, light weight, long lifetime, low power consumption, wide wavelength coverage, and the like. In addition, semiconductor lasers are widely used in important fields such as optical fiber communication, optical disc access, spectral analysis, and optical information processing.

For a traditional single-mode laser, especially for high power, a separate refrigerator is required for cooling and radiating heat for the laser during normal operation. While the most common heat sinks are currently of three types: cooling with circulating cooling water, cooling with air, and cooling with semiconductor refrigerator. The laser manufactured by the existing method has huge volume, and the performance and the characteristics of the semiconductor laser cannot be well exerted and embodied in many occasions.

The X-ray self-supporting blazed transmission grating has the advantages of high efficiency and high resolution of broadband, and has great application requirements in the fields of inertial confinement fusion plasma diagnosis, astronomical physics, X-ray phase contrast imaging and the like. It is expected that if the X-ray self-supporting blazed transmission grating is used in combination with the semiconductor laser, reliability in medical diagnosis can be certainly improved, and a doctor can find out a treatment means in a targeted manner.

Moreover, the power and the service life of the DL are important indexes for measuring the performance of the DL, and the current cavity surface optical disaster phenomenon is a key factor for limiting the power and the service life of the high-power DL. In order to prevent the occurrence of cavity surface optical catastrophe, the techniques mainly used for resisting cavity surface optical catastrophe at present include the following types:

firstly, a cavity surface passivation treatment technology.

Secondly, a cavity surface passivation film technology.

And thirdly, non-radiation absorption window technology. The technology is to prepare a layer of wide-bandgap semiconductor material by secondary epitaxial growth or doping diffusion on the cavity surface of the laser, and aims to reduce the radiation absorption of photons in the region and reduce the temperature of the cavity surface.

However, the cleaning step is required before the passivation film is prepared, which may cause some damage to the cavity surface; non-radiation absorbing window technology may additionally produce semiconductor materials.

Disclosure of Invention

In view of the above, an object of the present invention is to provide a package structure of a semiconductor laser and a packaging method thereof, which are capable of facilitating packaging of a high resolution semiconductor laser and facilitating heat dissipation.

In view of the above, the present invention provides a package structure of a semiconductor laser, including a semiconductor laser, a semiconductor refrigerator, and a metal layer disposed between the semiconductor laser and the semiconductor refrigerator, where the semiconductor refrigerator includes a silicon substrate, a metal electrode disposed on the silicon substrate, a semiconductor thermoelectric material deposited on the metal electrode, and a P-N structure etched on the semiconductor thermoelectric material, and the semiconductor laser includes a first electrode, a second electrode, a substrate disposed between the first electrode and the second electrode and sequentially arranged from the first electrode toward the second electrode, a first confinement layer, a first waveguide layer, an active region, a second waveguide layer, a second confinement layer, an ohmic contact layer, and a transmission grating layer in contact with the second confinement layer.

The transmission grating layer is an X-ray self-supporting blazed transmission grating layer.

The first electrode and the second electrode are both led out through the metal layer and connected to a power supply.

The P-N structure comprises a P-type electrode and an N-type electrode; and the P-type electrodes and the N-type electrodes in the P-N structure are alternately arranged.

And the P-type electrode or the N-type electrode on the outermost layer of the P-N structure extends outwards through the metal lead to be used as a contact electrode.

And adjacent P-N structures are connected with each other through a top metal material or a bottom metal material.

The first electrode is an N-type electrode, the first limiting layer is an N-type limiting layer, the first waveguide layer is an N-type waveguide layer, the second electrode is a P-type electrode, the second limiting layer is a P-type limiting layer, and the second waveguide layer is a P-type waveguide layer.

The N-type waveguide layer and the P-type waveguide layer are made of Al_xGa_1-xAs material, the thickness ratio of the N-type waveguide layer to the P-type waveguide layer is 4: 1.

the P-type limiting layer adopts Al_xGa_1-xAs material.

The active region is a quantum well active region or a quantum dot active region.

And two opposite side surfaces of the semiconductor laser are respectively provided with an antireflection film and a high-reflection film.

The invention also provides a packaging method of the packaging structure of the semiconductor laser, which comprises the following steps:

step one, stacking a semiconductor laser on a metal layer above a semiconductor refrigerator;

connecting the pins of the semiconductor laser to the metal layer, and leading out electrodes from the metal layer;

connecting a contact electrode in a P-N structure on the semiconductor refrigerator with a metal layer;

and step four, integrally packaging the semiconductor laser and the semiconductor refrigerator in the chip through the metal layer.

The semiconductor laser and the semiconductor refrigerator are attached through a heat-conducting insulating material.

And two opposite side surfaces of the packaging structure of the semiconductor laser are respectively provided with an antireflection film and a high-reflection film.

The preparation method of the semiconductor laser comprises the following steps:

the method comprises the following steps that firstly, an N-type limiting layer, an N-type waveguide layer, an active region, a P-type waveguide layer, a P-type limiting layer and an ohmic contact layer are epitaxially prepared on a substrate in sequence;

etching the middle part of the ohmic contact layer to form a P-type limiting layer so as to form a grating groove;

step three, preparing a transmission grating according to the size of the grating groove;

step four, installing the transmission grating into the grating groove;

preparing a P-type electrode on the epitaxial wafer;

and step seven, thinning and polishing the substrate to prepare the N-type electrode.

The preparation method of the transmission grating comprises the following steps:

s1, taking an SOI silicon chip as a substrate, plating a Cr film on the upper surface of the substrate, and plating a silicon nitride film on the lower surface of the substrate;

s2, respectively coating photoresist on the upper surface and the lower surface of the substrate, manufacturing a grating supporting structure mask on the upper surface by utilizing ultraviolet lithography, and manufacturing a grating outer frame mask on the lower surface;

s3, etching the silicon nitride film on the lower surface through reactive ions, and etching the Cr film on the upper surface through a wet method;

s4, removing the photoresist on the upper surface and the lower surface;

s5, coating an anti-reflection film and a photoresist on the upper surface of the substrate in sequence;

s6, holographic photoetching is carried out to manufacture a grating mask, and the extending direction of the grating mask is vertical to the extending direction of the grating support structure mask;

s7, transferring the photoresist grating mask pattern into the antireflection film by reactive ion etching;

s8, depositing catalytic metal downwards by the upper surface vertical to the substrate, wherein the catalytic metal is gold, silver or platinum;

s9, removing the photoresist, the antireflective film, the Cr film and the catalytic metal attached to the photoresist and the Cr film;

s10, coating alkali-resistant protective glue on the upper surface of the substrate;

s11, etching the monocrystalline silicon on the lower surface until the etching is stopped to the middle SiO₂A layer;

s12, removing the alkali-resistant protective glue;

s13, removing the silicon nitride and the middle SiO2 layer in the window;

s14, putting the substrate into etching liquid consisting of hydrofluoric acid and oxidant for metal catalytic etching;

and S15, removing the catalytic metal, rinsing and drying to obtain the X-ray self-supporting blazed transmission grating.

The preparation method further comprises the steps of after edge lines of the epitaxial wafer with the electrodes are cleaved, depositing a highly compact passivation layer on the front cavity surface and the rear cavity surface of the semiconductor laser through an atomic layer deposition method, then depositing an antireflection film on the passivation layer on the front cavity surface, and depositing a high reflection film on the passivation layer on the rear cavity surface.

And the inside is cleaved in ultra-high vacuum. And depositing a passivation film on the laser cavity surface in vacuum, and then depositing a highly compact passivation layer. The first layer of passivation film plays a role in protecting the cavity surface of the laser from contacting air when the cavity surface of the laser is taken out of the vacuum cleaving machine and enters the atmospheric environment, and the cavity surface is prevented from being oxidized. The combination of this technique with the facet passivation film technique further improves the facet anti-facet optical catastrophic ability. The semiconductor laser chip is cleaved in ultrahigh vacuum and then the passivation film is deposited in situ, so that the oxygen in the air can be prevented from oxidizing and damaging the cavity surface, and the cleaning step before the preparation of the passivation film can be omitted, so that the damage of the cleaning step to the cavity surface is prevented, and the integrity of the cavity surface structure is protected to the maximum extent.

The invention has the beneficial effects that:

1. in the process of packaging the semiconductor laser, the semiconductor refrigerators are packaged together, heat generated by the semiconductor laser is transferred to the cold end of the semiconductor refrigerator, which absorbs heat to the outside, through the metal layer, and compared with the prior art in which the semiconductor refrigerator is separately arranged for the semiconductor laser, the semiconductor laser packaged in the invention has the advantages that the volume of the semiconductor laser is reduced, the performance of the laser is improved, the semiconductor laser is packaged above the semiconductor refrigerator, and compared with the method of manufacturing the semiconductor refrigerator above or below the semiconductor laser and then packaging, the process difficulty is small.

2. The P-type electrodes and the N-type electrodes in the P-N structure are alternately arranged. And doping pentavalent impurity elements and trivalent impurity elements to form a P-type electrode and an N-type electrode so as to form a semiconductor structure with the Peltier effect.

3. The adjacent P-N structures are connected with each other through a top metal material or a bottom metal material. The P-type electrode and the N-type electrode in the P-N structure form an interactive connection structure, so that the direct current in the whole P-N structure is ensured to be in the same direction, the heat absorption phenomenon is generated at the top node of the P-N structure, and the heat release phenomenon is generated at the bottom node.

4. The electrode of the semiconductor refrigerator extends outwards through the metal lead, and the external power supply supplies power to the semiconductor refrigerator, so that the semiconductor refrigerator and the semiconductor laser can work simultaneously.

5. According to the invention, the transmission grating layer is arranged between the P-surface electrode and the P-type limiting layer, so that the high resolution of the semiconductor laser is improved, and the semiconductor laser has the advantage of high beam quality. The requirements of large effective area and smooth side wall of the X-ray self-supporting blazed transmission grating can be met simultaneously. The semiconductor laser with the transmission grating layer can improve the reliability in medical diagnosis and is more beneficial for doctors to find out treatment means in a targeted manner.

6. The arrangement of the high-reflection film and the antireflection film gives consideration to both the surface light-emitting efficiency and the cavity surface light-emitting efficiency. The antireflection film is evaporated on the front cavity surface, and the high-reflection film is evaporated on the rear cavity surface, so that the light emitting efficiency of the cavity surface is improved, and the loss threshold of the cavity surface is reduced.

7. According to the invention, the atomic layer deposition method is adopted to deposit a layer of highly-compact passivation layer on the front cavity surface and the back cavity surface, and the passivation layer is highly-compact, so that the highly-compact passivation layer can more effectively prevent other atoms from entering the cavity surface material through the passivation layer compared with the existing passivation method, thereby preventing optical catastrophe of the cavity surface, improving the damage threshold value of the cavity surface, improving the power of the semiconductor laser and prolonging the service life of the semiconductor laser.

Drawings

In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only one or more embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic side cross-sectional view of a semiconductor laser of the present invention;

FIG. 3 is a cross-sectional view of a substrate coated with a Cr film on the upper surface and a silicon nitride film on the lower surface according to an embodiment of the present invention;

FIG. 4 is a cross-sectional view of a mask with a support structure formed on the top surface and a mask with a grating outer frame formed on the bottom surface according to an embodiment of the present invention;

FIG. 5 is a cross-sectional view of a structure in which a silicon nitride film is etched on a lower surface and a Cr film is etched on an upper surface according to an embodiment of the present invention;

FIG. 6 is a cross-sectional view of a structure after photoresist removal according to an embodiment of the present invention;

FIG. 7 is a cross-sectional view of a structure in which an antireflective film and a photoresist are sequentially coated on an upper surface according to an embodiment of the present invention;

FIG. 8 is a cross-sectional view of a photoresist grating mask according to an embodiment of the present invention;

FIG. 9 is a cross-sectional view of a photoresist grating mask transferred to an antireflective film according to an embodiment of the invention;

FIG. 10 is a cross-sectional view of a structure after plating with a catalytic metal according to an embodiment of the present invention;

FIG. 11 is a cross-sectional view of a structure for removing an antireflective film, a photoresist, a Cr film, and a catalytic metal attached to the photoresist and the Cr film according to an embodiment of the present invention;

FIG. 12 is a cross-sectional view of a structure coated with an alkali-resistant protective adhesive according to an embodiment of the present invention;

FIG. 13 is a cross-sectional view of the structure after etching of the lower surface of the single crystal silicon provided by an embodiment of the present invention;

FIG. 14 is a cross-sectional view of the structure after removing the alkali-resistant protective glue according to the embodiment of the present invention;

FIG. 15 shows the removal of silicon nitride and intermediate SiO layers provided by an embodiment of the present invention₂Cross-sectional view of the structure behind the layer;

FIG. 16 is a cross-sectional view of a metal catalyzed etch process provided in accordance with an embodiment of the present invention;

fig. 17 is a cross-sectional view of an X-ray self-supporting blazed transmission grating provided by an embodiment of the invention.

Labeled as:

1. a first electrode; 2. a second electrode; 3. a substrate; 4. a first confinement layer; 5. a first waveguide layer; 6. an active region; 7. a second waveguide layer; 8. a second confinement layer; 9. an ohmic contact layer; 10. a transmission grating layer; 11. top layer monocrystalline silicon; 12. intermediate layer of SiO₂(ii) a 13. Bottom layer monocrystalline silicon; 14. a Cr film; 15. a silicon nitride film; 16. photoresist is coated; 17. a lower photoresist; 18. a antireflection film; 19. photoresist; 20. a catalytic metal film; 21. alkali-resistant protective glue; 100. a semiconductor laser; 101. a semiconductor refrigerator; 102. a metal layer; 103. a silicon substrate; 104. a metal electrode; 105. a semiconductor thermoelectric material; 106. a P-N structure; 107. a metal material; 108. contacting the electrode.

Detailed Description

To make the objects, technical solutions and advantages of the present disclosure more apparent, the present disclosure is further described in detail below with reference to specific embodiments.

It should be noted that technical terms or scientific terms used in the embodiments of the present specification should have a general meaning as understood by those having ordinary skill in the art to which the present disclosure belongs, unless otherwise defined. The use of "first," "second," and similar terms in the embodiments of the specification is not intended to indicate any order, quantity, or importance, but rather is used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.

As shown in fig. 1, a package structure of a semiconductor laser 100 includes a semiconductor laser 100, a semiconductor refrigerator 101, and a metal layer 102 disposed between the semiconductor laser 100 and the semiconductor refrigerator 101, where the semiconductor refrigerator 101 includes a silicon substrate 103, a metal electrode 104 disposed on the silicon substrate 103, a semiconductor thermoelectric material 105 deposited on the metal electrode 104, and a P-N structure 106 etched on the semiconductor thermoelectric material 105, and the semiconductor laser 100 includes a first electrode, a second electrode, a substrate disposed between the first electrode and the second electrode and arranged in sequence from the first electrode to the second electrode, a first confinement layer, a first waveguide layer, an active region, a second waveguide layer, a second confinement layer, an ohmic contact layer, and a transmission grating layer 10 in contact with the second confinement layer. The transmission grating layer 10 is preferably an X-ray self-supporting blazed transmission grating layer 10.

In this embodiment, the metal used for the metal layer 102 is copper. The preparation process of the semiconductor refrigerator comprises the following steps: firstly, a layer of metal electrode is evaporated on a silicon substrate through a thermal evaporation or electron beam evaporation process, the metal electrode can select one of copper, aluminum or nickel as a contact electrode, a semiconductor thermoelectric material, such as bismuth telluride, is deposited through a magnetron sputtering coating process, and then a P-N structure is manufactured through a photoetching and corrosion process to form the structure shown in figure 1. The semiconductor cooler 101 is added in the process of packaging the semiconductor laser 100 to actively realize the cooling and heat dissipation functions of the semiconductor laser. The semiconductor refrigerator is arranged above the semiconductor laser stack and connected with the semiconductor laser stack through a metal layer. In the process of packaging the semiconductor laser 100, the semiconductor refrigerator 101 is packaged together, and the heat generated by the semiconductor laser 100 is transferred to the cold end of the semiconductor refrigerator 101, which absorbs heat to the outside, through the metal layer 102, compared with the prior art in which the semiconductor refrigerator 101 is separately provided for the semiconductor laser 100, the volume of the packaged semiconductor laser 100 is finally reduced, and the performance of the laser is improved. Compared with the method of manufacturing the semiconductor refrigerator above or below the semiconductor laser and then packaging, the semiconductor laser is packaged above the semiconductor refrigerator, and the process difficulty is small.

As an alternative embodiment, the electrodes of the semiconductor laser 100 are led out through the metal layer 102 and connected to a power supply. In the embodiment, the leads of the semiconductor laser 100 are connected to the metal layer 102, and the metal layer 102 leads out the electrodes and is externally connected to the power supply. The heat generated when the power supply is powered is also transferred from metal layer 102 to semiconductor cooler 101.

As an alternative embodiment, each set of P-N structures 106 includes one P-type electrode and one N-type electrode; the P-type electrodes and N-type electrodes in P-N structure 106 are alternately arranged. In a specific embodiment, as shown in fig. 1, after the photolithography and etching process of the semiconductor thermoelectric material, the semiconductor thermoelectric material is doped with a pentavalent impurity element and a trivalent impurity element to form alternating P-type electrodes and N-type electrodes. And doping pentavalent impurity elements and trivalent impurity elements to form a P-type electrode and an N-type electrode so as to form a semiconductor structure with the Peltier effect.

As an alternative embodiment, adjacent P-N structures 106 are connected to each other by a top or bottom metal material 107. In a specific embodiment, as shown in fig. 1, assuming that the metal electrode 104 is at the bottom, the metal material 107 is at the top, and a metal copper sheet may be used to connect the two P-type electrodes and the N-type electrode, and the metal electrode 104 and the metal material 107 are not connected to the same group of P-N structures 14 at the same time, so that the P-type electrode and the N-type electrode form an interactive connection structure, and it is ensured that the direct current in the whole P-N structure is in the same direction, so that the top junction of the P-N structure generates an endothermic phenomenon, and the bottom junction generates an exothermic phenomenon.

As an alternative embodiment, the P-type electrode or the N-type electrode at the outermost layer of the P-N structure 106 is extended outward through a metal lead as the contact electrode 108. In a specific embodiment, the N-type electrode or the P-type electrode bottom metal electrode 104 in the outermost P-N structure 106 is extended outward through a metal lead as a contact electrode 108 for connecting to a power supply. The contact electrode 108 is connected to the metal layer 102, and the external power supply simultaneously supplies power to the semiconductor laser 100 and the semiconductor refrigerator 101, so that the semiconductor laser and the semiconductor refrigerator can operate simultaneously. The electrodes of the semiconductor refrigerator 100 extend outward through the metal leads, and the semiconductor refrigerator 101 is supplied with power from an external power source, so that the semiconductor refrigerator 101 and the semiconductor laser 100 can operate simultaneously.

As an alternative embodiment, semiconductor laser 100 and semiconductor cooler 101 are bonded by a thermally conductive material. As shown in fig. 1, a silicon substrate 103 is further disposed on the top of the semiconductor cooler 100 above the metal material 107 as a heat conducting material to bond the semiconductor cooler 101 and the semiconductor laser 100. In particular, the heat conducting material can also adopt a ceramic plate. The thermally conductive material is an insulator. The semiconductor laser 100 and the semiconductor refrigerator 101 are separated by the insulating heat conduction material, so that interference and mutual influence can be effectively prevented.

In this embodiment, the first electrode 1 is an N-type electrode, the first confinement layer 4 is an N-type confinement layer, the first waveguide layer 5 is an N-type waveguide layer, the second electrode 2 is a P-type electrode, the second confinement layer 8 is a P-type confinement layer, and the second waveguide layer 7 is a P-type waveguide layer. A transmission grating layer is arranged between the P-face electrode and the P-type limiting layer, so that the high resolution of the semiconductor laser is improved, and the semiconductor laser has the advantage of high beam quality. The requirements of large effective area and smooth side wall of the X-ray self-supporting blazed transmission grating can be met simultaneously.

Wherein, the active region 6 is a quantum well active region or a quantum dot active region. This embodiment is illustrated with a quantum well active region. The quantum well active region is manufactured in the N-type waveguide layer and the P-type waveguide layer and is made of indium gallium arsenide materials.

In this embodiment, the substrate is an N-type gaas material with a thickness of about 300-.

The N-type waveguide layer and the P-type waveguide layer are made of AlxGa1-xAs materials, and the thickness ratio of the N-type waveguide layer to the P-type waveguide layer is 4: 1. the N-type waveguide layer and the P-type waveguide layer are different in thickness, so that the optical field distribution is changed, and the interaction probability of photons and the transmission grating is effectively improved.

The N-type limiting layer is manufactured on the substrate and is made of an N-type AlGaAs material, so that an optical field can be effectively limited. The P-type limiting layer is made of AlxGa 1-xAs. The P-type confinement layer is formed on the P-type waveguide layer.

Furthermore, two opposite side surfaces of the packaging structure of the semiconductor laser are respectively provided with an antireflection film and a high-reflection film. The arrangement of the high-reflection film and the antireflection film gives consideration to both the surface light-emitting efficiency and the cavity surface light-emitting efficiency. The antireflection film is evaporated on the front cavity surface, and the high-reflection film is evaporated on the rear cavity surface, so that the light emitting efficiency of the cavity surface is improved, and the loss threshold of the cavity surface is reduced.

the method comprises the following steps that firstly, an N-type limiting layer, an N-type waveguide layer, an active region 6, a P-type waveguide layer, a P-type limiting layer and an ohmic contact layer 9 are epitaxially prepared on a substrate 3 in sequence; the N-type substrate is a gallium arsenic substrate with a (100) plane deviated from a <111> direction by 15 degrees of an N-type deviation angle. On one hand, the formation of a metastable state ordered structure in the growth process can be inhibited by selecting a (100) plane 15-degree N-type deflection angle gallium arsenic substrate deviating from the <111> direction; on the other hand, the doping concentration of P-type impurities in the limiting layer can be improved, the effective potential barrier of electrons is improved, the electron leakage of the active region is inhibited, and the preparation of a high-power semiconductor laser is facilitated.

Etching the middle part of the ohmic contact layer 9 to form a P-type limiting layer so as to form a grating groove;

step four, installing the transmission grating into the grating groove;

preparing a P-type electrode on the epitaxial wafer;

and seventhly, thinning and polishing the substrate 3 to prepare the N-type electrode. And preparing a P-type electrode and an N-type electrode on the epitaxial wafer, wherein the electrodes are electrode materials capable of forming good ohmic contact with gallium arsenic materials, the P-type electrode is prepared by adopting a sputtering method, and the N-type electrode is prepared by adopting an evaporation method.

s1, taking an SOI silicon chip as a substrate, plating a Cr film 14 on the upper surface of the substrate, and plating a silicon nitride film 15 on the lower surface of the substrate; the structural parameters of the SOI silicon wafer adopted in the embodiment of the invention are as follows: the top layer of monocrystalline silicon is<100>Crystal orientation, thickness (2-10) micron; intermediate layer of SiO₂The thickness of (1-2) microns; the bottom layer of monocrystalline silicon is<100>Crystal orientation and thickness (300-500) microns, wherein the top layer of monocrystalline silicon and the middle layer of SiO₂And the thickness of the underlying single crystal silicon is designed based on the requirements of the product. Fig. 2 is a structural cross-sectional view of a substrate with a Cr-plated upper surface and a silicon nitride-plated lower surface according to an embodiment of the present invention, in which the Cr film is easily peeled off from the SOI wafer by a Cr-removing solution, and thus the Cr film is used as an intermediate layer of a transfer grating support structure, the Cr film is plated by an electron beam evaporation or ion beam sputtering method, the thickness of the Cr film must be greater than that of a catalytic metal, so that the Cr film can be removed by the Cr-removing solution, and experiments prove that a thickness greater than 100nm can meet requirements; the silicon nitride film and the monocrystalline silicon have similar structures, so that the silicon nitride film and the monocrystalline silicon have strong adhesive force, the silicon nitride film and the monocrystalline silicon do not fall off in the later ultrasonic cleaning process, and the silicon nitride does not react with the potassium hydroxide etching solution for windowing the lower surface of the silicon wafer, so that the silicon nitride film is used as a protective layer for manufacturing the grating outer frame structure, and can be plated by adopting a PECVD (plasma enhanced chemical vapor deposition) method, and the thickness is more than 40 nm.

S2, respectively coating photoresist 19 on the upper surface and the lower surface of the substrate, manufacturing a grating supporting structure mask on the upper surface by utilizing ultraviolet lithography, and manufacturing a grating outer frame mask on the lower surface; FIG. 3 is a structural cross-sectional view of a grating support structure mask made on the upper surface and a grating outer frame mask made on the lower surface, wherein the grating support structure mask is a line array, the period is preferably 10-20 micrometers, the line width is 2-3 micrometers, the grating outer frame mask image is an orthogonal grid, the width of the grid bars is 1-2 millimeters, and the interval of the grid bars is 4-6 millimeters. The photoresist is a positive photoresist, such as AZ MIR-701, the coating thickness (500-1000) nm is preferred, the photoresist is coated by using a rotary coating method, and the thickness can be adjusted by adjusting the rotating speed and the proportion of a solvent in the photoresist according to the use instruction of the photoresist. The gluing process is as follows: coating the surface, and baking; then coating the lower surface, and then baking the glue. The baking condition can refer to the photoresist application instruction, and for the AZ MIR-701 photoresist, the single baking parameter is baking for 2 minutes at 90 ℃ of a hot table. The ultraviolet lithography uses a URE-2000/35 type ultraviolet lithography machine of photoelectric technology research institute of Chinese academy of sciences, and the specific process conditions can refer to the photoresist use instruction and the lithography machine use instruction. Because the selected positive photoresist is adopted, the pattern of the photoetching mask is consistent with the target pattern. The process of ultraviolet photoetching comprises the following steps: exposing the upper surface in a contact manner; lower surface contact exposure; and (6) developing.

S3, etching the silicon nitride film 15 on the lower surface through reactive ions, and etching the Cr film 14 on the upper surface through a wet method; FIG. 4 is a cross-sectional view of a structure in which a silicon nitride film is etched on a lower surface and a Cr film is etched on an upper surface according to an embodiment of the present invention; for the etching of the silicon nitride film, an ICP-98A type induction coupling plasma etching machine developed by microelectronics of Chinese academy of sciences is used, the etching depth of the silicon nitride film is controlled by controlling the flow rate of reaction gas, the power of an excitation power supply, the power of a bias power supply and the etching time, and a large number of experiments prove that for the silicon nitride film with the thickness of 40nm, the adopted etching conditions are as follows: reaction gas CF₄(ii) a The flow rate is 20sccm, the excitation power supply power is 300W, the bias power supply power is 75W, and the time is 90 s. And (3) etching the Cr film by using a Cr removing liquid wet method, wherein the Cr removing liquid is prepared by mixing cerium ammonium nitrate: glacial acetic acid: water is mixed according to the mass ratio of 20:3: 100. Since the etching is isotropic, the etching time cannot be too long, otherwise the lateral undercutting effect will cause the Cr mask lines to disappear. The specific etching time can be obtained by experiment.

S4, removing the photoresist 19 on the upper surface and the lower surface; the photoresist on the upper surface and the lower surface is removed by acetone ultrasonic, and the structural cross-sectional view after the photoresist is removed is shown in fig. 5.

S5, coating an antireflective film 18 and a photoresist 19 on the upper surface of the substrate in sequence; fig. 6 is a cross-sectional view of a structure in which an antireflective film and a photoresist are sequentially coated on an upper surface according to an embodiment of the present invention, in order to reduce a standing wave effect in holographic exposure, before the photoresist is coated, a layer of antireflective film is coated on a prepared substrate, the antireflective film is selected from a series of Brewer Science, and the positive photoresist is selected from AZ MIR-701. The thickness of the antireflective film is about 150nm, and the thickness of the photoresist is about 300 nm.

S6, holographic photoetching is carried out to manufacture a grating mask, and the extending direction of the grating mask is vertical to the extending direction of the grating support structure mask; fig. 7 is a cross-sectional view of the photoresist grating mask according to the embodiment of the present invention, in which a holographic exposure is performed on a laemoscope exposure light path, and the photoresist grating mask is obtained after development, and when exposure is performed, the extending direction of the support structure mask is parallel to the optical platform, and the extending direction of the interference fringes that generate the photoresist grating mask pattern is perpendicular to the optical platform, so that the photoresist grating mask obtained by development is naturally perpendicular to the support structure.

S7, transferring the grating mask pattern of the photoresist 19 into the antireflection film 18 by reactive ion etching; fig. 8 is a structural cross-sectional view of transferring a photoresist grating mask to an antireflective film according to an embodiment of the present invention, where an etching depth of the antireflective film is controlled by controlling a reaction gas flow rate, an excitation power supply power, a bias power supply power, and an etching time, and finally, a photoresist grating mask pattern is transferred to the antireflective film to form the antireflective film of the grating structure.

S8, depositing catalytic metal on the upper surface of the substrate vertically downwards, where fig. 9 is a cross-sectional view of the structure after plating the catalytic metal according to the embodiment of the present invention, where the catalytic metal is gold, silver, or platinum; and depositing by adopting an ion beam sputtering or electron beam evaporation coating method to obtain the grating structure of the catalytic metal film.

S9, removing the photoresist 19, the antireflective film 18, the Cr film 14 and the catalytic metal attached to the photoresist 19 and the Cr film 14; the anti-reflective coating (ARC), the photoresist and the catalytic metal on the photoresist are removed by using acetone ultrasound, the Cr and the catalytic metal on the Cr are removed by using Cr-removing liquid ultrasound, and fig. 10 is a cross-sectional view of a structure for removing the anti-reflective coating, the photoresist, the Cr film and the catalytic metal attached to the photoresist and the Cr film according to an embodiment of the present invention.

S10, coating alkali-resistant protective glue 21 on the upper surface of the substrate; as shown in fig. 11.

S11, corroding the monocrystalline silicon on the lower surface until the corrosion is stopped to reach the middle SiO2 layer; fig. 12 is a cross-sectional view of the structure after etching the lower surface single crystal silicon according to the embodiment of the present invention, in which a KOH aqueous solution with a mass fraction of 30% is used as an etching solution, the etching temperature is 80 ℃, and the etching time is longer than 6 hours. Etching to intermediate SiO₂In the case of the layer, a smooth bottom surface is visible, at which point the etching can be stopped.

S12, removing the alkali-resistant protective glue 21; the alkali-resistant protective glue is removed by using a Piranha solution, and the alkali-resistant protective glue can be removed by using a water bath for 30 minutes at the water bath temperature of 80 ℃, and the structural cross-sectional view after the alkali-resistant protective glue is removed is shown in fig. 13.

S13, removing the silicon nitride and the middle SiO in the window₂A layer; soaking in 48% hydrofluoric acid for 8 min to remove silicon nitride and SiO in the window₂A cross-sectional view of the structure after removal of the silicon nitride and intermediate SiO2 layers is shown in fig. 14.

S14, putting the substrate into etching liquid consisting of hydrofluoric acid and oxidant for metal catalytic etching; the oxidant can be hydrogen peroxide, potassium permanganate or silver nitrate, the concentration of each component of the specific etching solution and the etching temperature can be obtained through a contrast experiment, the optimal target is to etch a grating structure with a smooth and steep side wall, the hydrogen peroxide is taken as the oxidant, the concentration of hydrofluoric acid in the etching solution is (4-6) mol/L, the concentration of hydrogen peroxide is (0.2-0.3) mol/L, and when the temperature of the etching solution is (5-15) DEG C, the obtained grating structure is steep and the side wall is smooth.

In addition, as a further improvement, the preparation method further comprises cleaving the edge line of the epitaxial wafer with the electrode, and then placing the edge line on the front cavity surface and the back cavity surface of the semiconductor laserAnd depositing a highly compact passivation layer by an atomic layer deposition method, then depositing an antireflection film on the passivation layer on the front cavity surface, and depositing a high-reflection film on the passivation layer on the rear cavity surface. The highly dense passivation layer has a thickness of 10nm and is made of Si₃N₄. The passivation layer is highly dense, so that the highly dense passivation layer can more effectively prevent other atoms from entering the cavity surface material through the passivation layer compared with the conventional passivation method, thereby preventing optical catastrophe of the cavity surface, improving the damage threshold of the cavity surface, improving the power of the semiconductor laser and prolonging the service life of the semiconductor laser. The method can prevent oxygen in the air from oxidizing and damaging the cavity surface, and can omit the cleaning step before preparing the passivation film, thereby preventing the cleaning step from damaging the cavity surface, and protecting the integrity of the cavity surface structure to the maximum extent.

Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, is limited to these examples; within the idea of the present disclosure, also technical features in the above embodiments or in different embodiments may be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present description as described above, which are not provided in detail for the sake of brevity.

The embodiments of the present description are intended to embrace all such alternatives, modifications and variances that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalents, improvements, and the like that may be made within the spirit and principles of the embodiments described herein are intended to be included within the scope of the disclosure.

Claims

1. The utility model provides a packaging structure of semiconductor laser, its characterized in that includes semiconductor laser, semiconductor refrigerator and locates the metal level between semiconductor laser and the semiconductor refrigerator, the semiconductor refrigerator includes the silicon substrate, locates the metal electrode on the silicon substrate, deposits the semiconductor thermoelectric material on the metal electrode and etches the P-N structure on the semiconductor thermoelectric material, the semiconductor laser includes first electrode, second electrode, locate between first electrode and the second electrode and from the substrate, first restriction layer, first waveguide layer, active area, second waveguide layer, second restriction layer, ohmic contact layer and the transmission grating layer that ohmic contact layer and second restriction layer contacted that first electrode set gradually towards the second electrode direction.

2. The package structure of a semiconductor laser as claimed in claim 1 wherein the first and second electrodes are each led out through a metal layer to a power supply.

3. The package structure of a semiconductor laser as claimed in claim 1 wherein the P-N structure comprises one P-type electrode and one N-type electrode; and the P-type electrodes and the N-type electrodes in the P-N structure are alternately arranged.

4. The package structure of a semiconductor laser as claimed in claim 1, wherein the P-type electrode or the N-type electrode at the outermost layer of the P-N structure is extended outward through a metal wire as a contact electrode.

5. The package structure of a semiconductor laser as claimed in claim 1 wherein adjacent P-N structures are interconnected by a top or bottom metal material.

6. The package structure of a semiconductor laser as claimed in claim 1, wherein the first electrode is an N-type electrode, the first confinement layer is an N-type confinement layer, the first waveguide layer is an N-type waveguide layer, the second electrode is a P-type electrode, the second confinement layer is a P-type confinement layer, and the second waveguide layer is a P-type waveguide layer.

7. The package structure of a semiconductor laser as claimed in claim 6 wherein the N-type waveguide layer and the P-type waveguide layer are Al-based_xGa_1-xAs material, the thickness ratio of the N-type waveguide layer to the P-type waveguide layer is 4: 1.

8. the package structure of a semiconductor laser as claimed in claim 1, wherein two opposite sides of the semiconductor laser are respectively provided with an anti-reflection film and a high-reflection film.

9. A packaging method for a packaging structure of a semiconductor laser as claimed in claim 1, characterized by comprising the steps of:

10. The method of claim 9 wherein the semiconductor laser and the semiconductor cooler are bonded together by a thermally conductive and insulating material.