阅读说明：本技术 激光辅助加热mocvd装置及其工作方法 (Laser-assisted heating MOCVD device and working method thereof ) 是由 齐通通 罗海林 钟琪 李海洪 于 2021-08-18 设计创作，主要内容包括：本发明提出一种激光辅助加热MOCVD装置及其工作方法,其特征在于：使用激光加热系统联合MOCVD自有的原位监测系统EPI-TT,在MOCVD设备自身热系统到达设定温度后,使用激光加热系统生成光斑对腔体内的晶圆进行辅助加热,用于辅助MOCVD进行外延薄膜的生长。其能够在光通信掩埋异质结DFB激光器Block生长阶段使用激光辅助加热,能够形成良好的PNP结构及形貌,改善了在连续生长时温度不能及时调节导致的晶体缺陷,优化了生长过程存在速度差导致的无法制备出形貌良好的PNP结构外延层。(The invention provides a laser-assisted heating MOCVD device and a working method thereof, which are characterized in that: and (3) combining the laser heating system with an MOCVD (metal organic chemical vapor deposition) own in-situ monitoring system EPI-TT, and generating light spots by using the laser heating system to perform auxiliary heating on the wafer in the cavity after the MOCVD equipment self thermal system reaches a set temperature, so as to assist the MOCVD in growing the epitaxial film. The laser auxiliary heating device can be used for laser auxiliary heating in the growth stage of the optical communication buried heterojunction DFB laser Block, a good PNP structure and a good appearance can be formed, the crystal defect caused by the fact that the temperature cannot be timely adjusted during continuous growth is overcome, and the situation that the PNP structure epitaxial layer with a good appearance cannot be prepared due to the fact that the growth process is poor in speed is optimized.)

1. A laser-assisted heating MOCVD device is characterized in that: and (3) combining the laser heating system with an MOCVD (metal organic chemical vapor deposition) own in-situ monitoring system EPI-TT, and generating light spots by using the laser heating system to perform auxiliary heating on the wafer in the cavity after the MOCVD equipment self thermal system reaches a set temperature, so as to assist the MOCVD in growing the epitaxial film.

2. The laser-assisted heating MOCVD apparatus according to claim 1, wherein the laser heating system comprises: nd is YAG laser and diffraction beam shaper; the sum-diffraction beam shaper is used to transform a laser beam having a near-gaussian profile into a sharp shape having a uniform flat-top intensity distribution.

3. The laser-assisted heating MOCVD apparatus according to claim 2, wherein: the Nd is that a YAG laser is arranged outside the glove box; the diffraction beam shaper suite is fixed above an Argus hole of the LID, converts laser beams of the laser into rectangular beams with the same size as the Argus hole, irradiates a wafer to be grown through the LID and is used for auxiliary heating during epitaxial growth.

4. The method of any of claims 1-3 for operating a laser assisted heating MOCVD apparatus, wherein: when a Block PNP electronic barrier layer grows, a laser auxiliary heating system is used for increasing the surface temperature of a wafer on a first P-type layer, so that the P-type layer starts to grow the PNP electronic barrier layer with a BH structure when reaching a certain growth temperature.

5. The method of claim 4 for operating a laser-assisted heating MOCVD apparatus, wherein: the method is used for improving the preparation of the epitaxial film of the optical communication buried heterojunction DFB laser and the device.

6. The method of claim 5 for operating a laser-assisted heating MOCVD apparatus, wherein: the preparation of the epitaxial thin film specifically comprises the following steps: firstly growing a P-type InP buffer layer, an electronic barrier layer, a waveguide structure, a strain InGaAsP multiple quantum well, a grating layer and a cap layer on a 2-inch N-type InP substrate, then preparing a grating and carrying out subsequent buried growth, preparing and forming a ridge-type structure by adopting a single-layer SiO2 as a mask layer, then carrying out ridge-type structure corrosion by adopting a hydrobromic acid solution until reaching the substrate layer, forming a SiO2 on a ridge waveguide of the ridge waveguide structure to form a cantilever, placing a sample in a BOE solution for corrosion, removing oxides on two sides of the ridge waveguide structure by utilizing the difference of corrosion rates of different materials, then placing the sample in an MOCVD cavity for growth, then growing a Block and plug PNP electronic barrier layer, removing the SiO2 on the surface of the sample by adopting the BOE solution, carrying out a final P-InP space layer, a P-InGaAsP transition layer, a P-InGaAs ohmic contact layer and a P-InP cap layer by adopting MOCVD equipment, and finishing epitaxial growth.

7. The method of claim 6 for operating a laser-assisted heating MOCVD apparatus, wherein: after the epitaxial growth is completed, laser electrodes are prepared, holes are opened, and P-surface and N-surface electrodes are prepared to form the structure of the N-surface and P-surface electrodes.

Technical Field

The invention relates to the technical field of semiconductor laser device preparation and photoelectron information for optical communication, in particular to a laser-assisted heating MOCVD device and a working method thereof, which can be at least used for improving the epitaxial film quality and chip performance of a buried heterostructure DFB laser for optical communication.

Background

With the advent of optical communication and photoelectron industrialization, various types of substrates, semiconductor devices and photoelectronic devices with different structures come out in succession, and the device performance thereof is gradually improved, wherein an InP-based semiconductor material is an important substrate material of an optical communication semiconductor chip and a device, the MOCVD technology not only becomes a main means for preparing low-dimensional structures such as compound semiconductor heterojunctions, superlattices, quantum wells, quantum dots and the like, but also is an important method for producing compound semiconductor photoelectrons and microelectronic devices, has already formed an industry, and is still under continuous development and is an important component of modern epitaxial technology. As an important component of an optical communication system, as a signal emission source, when parameters of various types of devices meet standards, an optoelectronic device with stable working state can be obtained by firstly ensuring the epitaxial quality of the device. With the development and optimization of the epitaxial process, the buried heterojunction structure (BH) burying process cost is reduced, the yield is higher, and the buried heterojunction structure (BH) burying process is superior to a ridge waveguide structure device in terms of electric field and optical field limiting effects, so people are more inclined to research a BH structure laser with better electric field and optical field limiting effects, but limited to MOCVD growth process in which the material growth rule is growth along the crystal direction, when the base material structure is poor or the growth temperature cannot be changed in real time, the corresponding material growth is affected by the temperature, the growth effect cannot be expected, and the growth quality is poor.

In the above-mentioned process for manufacturing the buried heterojunction DFB laser chip for optical communication, the preliminary epitaxial structure thereof is, from bottom to top: the structure comprises a 2-inch N-type InP substrate, an N-InP buffer, an InGaAsP lower waveguide layer, an InGaAsP strain multi-quantum well and barrier structure layer, an InGaAsP upper waveguide layer, a P-InP spacing layer, a P-InGaAsP grating layer, a P-InP Cap layer, a P-InGaAs layer and a P-InP layer; an SiO2 dielectric layer is arranged on the P-InP layer, and a ridge waveguide structure is formed from the upper part of the N-InP buffer layer to the P-InP layer; the SiO2 dielectric layer forms a cantilever structure on the ridge waveguide. The structure before the forming of the manufacturing process of the semiconductor heterojunction laser chip for optical communication comprises a primary structure, a subsequent PNP epitaxial layer and a third epitaxial growth, wherein a P-InP current blocking layer and an N-InP current blocking layer are sequentially grown from bottom to top beside a ridge waveguide structure, a SiO2 dielectric layer is removed, then a P-InP space layer, an InGaAsP transition layer, a P-InGaAs ohmic contact layer and a P-InGaAs cap layer are sequentially grown on the P-InP current blocking layer, a mesa structure is formed on the P-InGaAs ohmic contact layer, holes are formed in the mesa, and a P-type electrode is formed on the mesa and the left side of the mesa; and an N-type electrode is formed by opening a hole in the region on the right side of the mesa.

Compared with a RWG structure, a BH structure of the semiconductor DFB laser for optical communication is an NPnp thyristor which is a bidirectional controllable switch, and has double limiting effects on current carriers (electricity) and photons (optics) and extremely strong constraint force on the current carriers. But the defects are that multiple times of epitaxial growth are needed in the preparation process, the process is complex and difficult to control, the yield is low, the device performance does not reach the theoretical standard, and the repeatability is poor.

The MOCVD growth has very strict requirements on the surface quality and geometric morphology of a substrate material, for a ridge waveguide structure with a cantilever and a PNP structure for the third epitaxial growth, the epitaxial growth is only carried out on groove structures at two sides of a ridge structure platform, the growth is slow even the PNP structure does not grow in a short time due to a certain angle of the platform, so that the top of the ridge platform is lack of P due to different growth rates, and the PNP structure MOCVD system can not realize real-time temperature change control, if the early growth temperature is high, the later epitaxial layer needs to grow at a low temperature, the temperature change and continuous growth can not be carried out, the quality of the PNP epitaxial layer is influenced by the substrate morphology and the angle, the preparation quality of the PNP epitaxial layer directly influences the threshold current, the output power, the spectral characteristics, the service life and the like of a device, so the research and improvement of the preparation method of the subsequent PNP epitaxial layer are needed, and preparing an epitaxial layer with complete structure and appearance.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention provides a laser-assisted heating MOCVD device and a working method thereof. The design starting point is used for improving the preparation of the epitaxial film and the device of the optical communication buried heterojunction DFB laser, but the design starting point can also be further suitable for other scenes with secondary temperature control requirements on the growth of the epitaxial layer.

The invention specifically adopts the following technical scheme:

a laser-assisted heating MOCVD device is characterized in that: and (3) combining the laser heating system with an MOCVD (metal organic chemical vapor deposition) own in-situ monitoring system EPI-TT, and generating light spots by using the laser heating system to perform auxiliary heating on the wafer in the cavity after the MOCVD equipment self thermal system reaches a set temperature, so as to assist the MOCVD in growing the epitaxial film.

Further, the laser heating system includes: nd is YAG laser and diffraction beam shaper; the sum-diffraction beam shaper is used to transform a laser beam having a near-gaussian profile into a sharp shape having a uniform flat-top intensity distribution.

Further, the Nd-YAG laser is placed outside the glove box; the diffraction beam shaper suite is fixed above an Argus hole of the LID, converts laser beams of the laser into rectangular beams with the same size as the Argus hole, irradiates a wafer to be grown through the LID and is used for auxiliary heating during epitaxial growth.

Further, when a Block PNP electronic barrier layer grows, a laser auxiliary heating system is used for increasing the surface temperature of the wafer on the first P-type layer, and the P-type layer starts to grow the PNP electronic barrier layer with a BH structure when reaching a certain growth temperature.

Further, the method is used for improving the preparation of the epitaxial film of the optical communication buried heterojunction DFB laser and the device.

Further, the preparation of the epitaxial thin film specifically comprises the following processes: firstly growing a P-type InP buffer layer, an electronic barrier layer, a waveguide structure, a strain InGaAsP multiple quantum well, a grating layer and a cap layer on a 2-inch N-type InP substrate, then preparing a grating and carrying out subsequent buried growth, preparing and forming a ridge-type structure by adopting a single-layer SiO2 as a mask layer, then carrying out ridge-type structure corrosion by adopting a hydrobromic acid solution until reaching the substrate layer, forming a SiO2 on a ridge waveguide of the ridge waveguide structure to form a cantilever, placing a sample in a BOE solution for corrosion, removing oxides on two sides of the ridge waveguide structure by utilizing the difference of corrosion rates of different materials, then placing the sample in an MOCVD cavity for growth, then growing a Block and plug PNP electronic barrier layer, removing the SiO2 on the surface of the sample by adopting the BOE solution, carrying out a final P-InP space layer, a P-InGaAsP transition layer, a P-InGaAs ohmic contact layer and a P-InP cap layer by adopting MOCVD equipment, and finishing epitaxial growth.

Further, after the epitaxial growth is completed, laser electrodes are prepared, holes are opened, and P-surface and N-surface electrodes are prepared, so that the structure of the N-surface and P-surface electrodes is formed.

The principle of the MOCVD equipment is that an organic compound of a III group element and a hydride of V are mixed and then are introduced into a reaction cavity, when mixed gas flows through the surface of a heated substrate, thermal decomposition reaction is generated on the surface of the substrate, and a compound single crystal film is epitaxially grown, the MOCVD process growth process comprises a series of complex dynamic processes of transportation, diffusion, adsorption, reaction, decomposition, migration, desorption and combination with the surface material of the substrate of a spraying source material on the surface of the substrate, and is influenced by the surface chemistry and surface reaction control dynamic processes, when the PNP epitaxial electronic barrier layer structure is grown by using the MOCVD equipment in the prior art, a gaseous precursor reactant is utilized to produce the film through chemical reaction among atomic molecules, almost all reactions are endothermic reactions, the MOCVD heat source is heated by utilizing a heating wire, a graphite plate is heated to a certain temperature, and the heat is transmitted to Wafer, finally, thin film deposition is realized, if the early heating temperature is high, equipment heating can be limited by high temperature, ultra-high temperature growth cannot be realized, the substrate temperature cannot be adjusted in time in the preparation process, the quality, the appearance and the angle of the buried heterojunction PNP electronic barrier layer epitaxial film can be influenced by the substrate temperature, selected area deposition film forming can be carried out at high temperature, the migration rate can be improved, the quality of the buried heterojunction PNP electronic barrier layer epitaxial film directly influences the threshold current, the output power, the spectral characteristics, the service life of a device and the like, and therefore the preparation method needs to be improved. The design of the invention can master the temperature change at any time, the Wafer temperature can be accurately adjusted by the auxiliary heating of the laser heating system, the temperature of the upper surface of the Wafer can be improved, the Wafer surface can be ensured to realize high-temperature growth by the auxiliary heating system of the laser and the MOCVD heating system, the atom transfer rate can be improved, the invention is more suitable for the growth of the epitaxial film of the buried heterojunction PNP electronic barrier layer, the epitaxial quality can be stably improved, and the performance of the device can be improved.

Compared with the prior art, the laser auxiliary heating method and the laser auxiliary heating device can use laser auxiliary heating in the growth stage of the optical communication buried heterojunction DFB laser Block, can form a good PNP structure and a good appearance, improve the crystal defect caused by the fact that the temperature cannot be adjusted timely during continuous growth, and optimize the situation that the good PNP structure epitaxial layer cannot be prepared due to the fact that the growth process has a poor speed.

Drawings

The invention is described in further detail below with reference to the following figures and detailed description:

fig. 1 is a schematic view of the auxiliary heating system of the Nd: YAG laser according to an embodiment of the present invention, which includes a Nd: YAG laser, a cooling system, and the like.

Fig. 2 is a schematic diagram of a laser light path direction and a beam shaper according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of an MOCVD glove box and a reaction chamber LID according to an embodiment of the present invention.

Fig. 4 is a schematic perspective view of fig. 3.

Detailed Description

In order to make the features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail as follows:

the preparation process of the epitaxial film and the device of the buried heterojunction DFB laser for improving the optical communication of the improved object of the embodiment is as follows:

firstly, growing a P-type InP Buffer, an electronic barrier layer, a waveguide structure, a strain InGaAsP multiple quantum well, a grating layer and a cap layer on a 2-inch N-type InP substrate, then preparing a grating and carrying out subsequent buried growth, preparing and forming a ridge structure by adopting a single-layer SiO2 as a mask layer, then carrying out ridge structure corrosion by adopting a hydrobromic acid solution, corroding to the substrate layer to form a SiO2 on the ridge waveguide of the ridge waveguide structure to form a cantilever, placing a sample in a BOE solution for corrosion, removing oxides on two sides of the MOCVD waveguide structure by utilizing the difference of corrosion rates of different materials, then rapidly placing the sample into an MOCVD cavity for growth, then growing a Block PNP InP electronic barrier layer, removing the SiO2 on the surface of the sample by adopting the BOE solution, carrying out the final P-InP space layer, the P-InGaAsP transition layer, the P-InGaAs ohmic contact layer and the P-InP cap layer by adopting MOCVD equipment, and finishing epitaxial growth. Preparing laser electrode, perforating, preparing P-surface and N-surface electrodes, and forming N-surface and P-surface electrode structures

As shown in fig. 1 to 4, the present embodiment provides a laser-assisted heating MOCVD apparatus and a working method thereof, which are used for optimizing the above preparation process.

The laser-assisted heating metal vapor chemical deposition system provided by the embodiment comprises a laser heating system, a light source cooling system and a laser heating system communication information conduction feedback device.

YAG laser instrument and diffraction beam shaper are including Nd: the latter is used to transform a laser beam with a near-Gaussian profile into a clear shape with a uniform flat-top intensity distribution, and the Nd: YAG crystal is composed of Al₂O₃YAG is the solid laser which is the most widely used at present, and based on the design principle, the Nd-YAG can be equally replaced by other similar existing lasers.

In the aspect of a communication information conduction feedback device of a laser heating system, the laser heating system is directly combined with an MOCVD (metal organic chemical vapor deposition) own in-situ monitoring system EPI-TT, and after the MOCVD equipment self thermal system reaches a set temperature, a laser heating system is used for generating light spots to carry out auxiliary heating on wafers in a cavity, so that the MOCVD is assisted to carry out the growth of an epitaxial film. The method is easy to control, the Wafer growth temperature can be accurately adjusted, the PNP electronic barrier layer of the BH structure can be favorably grown, and the epitaxial film quality can be improved.

YAG laser is placed outside a glove box, a beam shaper suite is fixed above an Argus hole of LID by screws, laser beams of the laser are converted into rectangular beams with the same size as the Argus hole by the beam shaper suite, and the rectangular beams are irradiated onto Wafer to be grown through LID and used for auxiliary heating during epitaxial growth. When a Block PNP electronic barrier layer grows, a laser auxiliary heating system is used for increasing the Wafer surface temperature of the first P-type layer, so that the P-type layer can start the growth of the PNP electronic barrier layer with a BH structure when reaching a certain growth temperature.

The present invention is not limited to the preferred embodiments, and other laser-assisted MOCVD apparatus and methods of operation can be devised without departing from the spirit and scope of the present invention.