TWI854669B - Method of manufacturing laser elements - Google Patents

Abstract

A method for manufacturing laser elements including: providing a substrate; growing a protection layer on the upper surface of the substrate; implementing an etching process on the protection layer to form an element area; growing an element layer in the element area; and implementing a cutting process to form the laser elements.

Description

Laser element manufacturing method

The present disclosure relates to a method for manufacturing a laser device.

When manufacturing Fabry-Perot (FP) laser, distributed feedback (DFB) laser or electroluminescent modulator (EML) components, especially when using ternary or quaternary materials containing aluminum (Al) (e.g., aluminum gallium indium arsenide, InGaAlAs) as the component layer material, in order to improve the reliability of the component, after the component layer of the luminescent area is epitaxially grown, the epitaxial wafer is usually removed from the epitaxial machine (e.g., metal organic vapor phase epitaxy equipment, MOCVD), and then an etching process is performed to etch both ends of the component layer. Then, epitaxy is performed again at both ends of the etched component layer to form end face protection layers at both ends of the component layer to protect the component layer.

However, if a ternary or quaternary compound containing aluminum (Al) is used as the material of the device layer, after the device layer is etched, the surface of the device layer in this light-emitting area will be exposed to the etching solution and the atmosphere, and aluminum oxide or aluminum oxide will be easily generated, resulting in poor crystal quality of the device layer in the light-emitting area, affecting the quality and reliability of subsequent products.

At present, the industry's solution to the problem of aluminum oxide or aluminum oxide generation is mostly to further remove it with chemical agents. However, the use of chemical agents will more or less cause the component layer to be corroded and damaged, and will also lead to poor quality of the final product.

In order to solve the problem that the above-mentioned device layer is easily generated with aluminum oxide or aluminum oxide due to contact with etching liquid and atmosphere after etching, the present disclosure provides a method for manufacturing a laser device, including: providing a substrate; growing a protective layer on the upper surface of the substrate; performing an etching process on the protective layer to form a device region; growing a device layer in the device region; and performing a cutting process to form a laser device.

In one embodiment of the present disclosure, the substrate material provided above is indium phosphide (InP) or gallium arsenide (GaAs).

In one embodiment of the present disclosure, the material of the protective layer grown above is indium phosphide (InP) or indium gallium arsenide phosphide (InGaAsP).

In one embodiment of the present disclosure, the material of the device layer is indium aluminum gallium arsenide (InGaAlAs), indium gallium arsenide phosphide (InGaAsP), indium gallium arsenide (InGaAs) or indium phosphide (InP).

The following will refer to the relevant drawings to illustrate an embodiment of the manufacturing method of the laser element disclosed in the present invention. For the sake of clarity and convenience of the diagram description, the components in the diagram may be exaggerated or reduced in size and proportion. For ease of understanding, the same elements in the following embodiments are indicated by the same symbols.

Please refer to Figure 1, which is a flow chart of a generally known laser device manufacturing method. As shown in the figure, the process flow of the known laser device manufacturing method first places the substrate 100 in an epitaxial machine (e.g., metal organic vapor phase epitaxy equipment, i.e., MOCVD) to grow an epitaxial structure of a device layer 200 on the substrate 100. After the device layer 200 is grown, the chip is first taken out of the epitaxial machine, and an etching process is further performed on the device layer 200 so as to etch both ends of the device layer 200 in the light-emitting area. The etching process is a process generally known in the industry. The process flow generally includes: coating a photoresist on the device layer 200, then performing yellow light development to pattern the photoresist layer, and then performing etching to remove the two end portions of the device layer not protected by the photoresist layer, and finally removing the photoresist layer.

After the etching process is completed, the wafer is placed in an epitaxial machine, and a protective layer 300 is epitaxially grown at both ends of the device layer 200 to protect the device layer 200 in the middle. After the general epitaxial wafer process, the epitaxial wafer is cut (the cutting position is shown by the dotted line in Figure 1) to obtain the laser device.

The generally known epitaxial wafer process includes the following steps: S1: forming a ridge buried (BH) structure; S2: etching to form a trench; S3: covering the insulating layer; S4: opening the P-side metal contact area; S5: P-side metal deposition; S6: substrate grinding; and S7: N-side metal deposition. This epitaxial wafer process is common knowledge in the art, and operators or manufacturers can adjust, modify, replace or omit it according to product requirements. It is not limited or detailed here, and is not drawn in Figures 1 and 2.

However, according to the above-mentioned laser device manufacturing process, the device layer 200 of the light-emitting area must leave the epitaxial machine after epitaxy and then undergo an etching process. Therefore, if the device layer 200 uses a material containing aluminum elements, after being exposed to etching liquid and air, aluminum oxide or aluminum oxide is easily generated on the surface of the device layer 200, which leads to poor crystal quality of the device layer 200 in the light-emitting area, further affecting the product quality and reliability of the subsequent laser device 10.

In order to prevent the device layer 200 from generating aluminum oxide or aluminum oxide due to contact with etching liquid and atmosphere, the present disclosure proposes a method for manufacturing a laser device 10, please refer to FIG. 2. FIG. 2 is a flow chart of a method for manufacturing a laser device 10 of the present disclosure. As shown in the figure, in the present embodiment, first, a substrate 100 is provided and the substrate 100 is placed in an epitaxial machine. Then, different from the known method for manufacturing a laser device (FIG. 1), in the present embodiment, a protective layer 300 is first grown on the surface of the substrate 100, instead of first growing the device layer 200. After the growth of the protective layer 300 is completed, the chip is first taken out of the epitaxial machine, and an etching process is further performed on the protective layer 300. Different from the manufacturing method of the laser device 10 shown in FIG. 1, the object to be etched in this etching process is the protective layer 300, not the device layer 200. The purpose of this etching process is to etch a device region 301 from the protective layer 300. After the device region 301 is formed, the chip is placed in the epitaxial machine, and then the device layer 200 is grown in the device region 301. It is worth mentioning that in the entire process of the manufacturing method of the laser device 10 proposed in the present disclosure, the device layer 200 does not need to undergo an etching process at all, so it will not be exposed to the etching liquid. Therefore, when using a material containing aluminum as the device layer 200, there will be no problem of aluminum oxide or aluminum oxide being formed, so it will not affect the crystal quality of the light-emitting device layer 200. After the device layer 200 is grown and a general epitaxial wafer process is performed, a cutting process can be performed (the cutting position is shown by the dotted line in FIG. 2 ) to cut out the laser device 10 to be produced.

It is worth noting that in the process of the manufacturing method of the laser device 10 proposed in the present disclosure, the device layer 200 does not need to undergo an etching process at all, so there will be no problem of the generation of aluminum oxide or aluminum oxide. Therefore, when the protective layer 300 is etched to form the device area 301, it is not necessary to further use chemicals to remove the aluminum oxide or aluminum oxide, so the protective layer 300 or the device layer 200 will not be damaged by chemical corrosion and affect the quality of subsequent products.

It should be understood that the etching process mentioned in the present embodiment is an etching process that is widely known and used in the general industry, and therefore, no further description is required here. A person skilled in the art of the present disclosure should be able to select a suitable etching process or perform equivalent modifications according to the size and material of the laser element 10 to be produced, and neither should be regarded as departing from the conceptual scope of the present disclosure and no further limitation is imposed here.

In one embodiment of the present disclosure, the substrate 100 used can be selected according to product requirements, such as an indium phosphide (InP) substrate or a gallium arsenide (GaAs) substrate. In one embodiment, when the laser device 10 to be produced is used for a wavelength greater than 1000nm, an indium phosphide (InP) substrate is selected. In another embodiment, when the laser device 10 to be produced is used for a wavelength less than 1000nm, a gallium arsenide (GaAs) substrate is selected.

In one embodiment of the present disclosure, the material of the device layer 200 grown on the surface of the substrate 100 can also be selected from different epitaxial materials according to the type of product to be produced, for example, it can be selected from ternary or quaternary compounds of the III-V group (III-V) such as indium aluminum gallium arsenide (InGaAlAs), indium gallium arsenide phosphide (InGaAsP), indium gallium arsenide (InGaAs) or indium phosphide (InP).

In one embodiment of the present disclosure, the etching process mentioned is to remove the approximately middle area of the protective layer 300 by etching to form the device area 301. It should be understood that the size of the device area 301 can be changed according to the design parameters of the product to be produced, and is not limited here. In one embodiment, the etching process is etched at a position approximately in the middle area of the protective layer 300, so that there is still a protective layer 300 of approximately equal length at both ends of the device area 301 formed after etching, so as to protect the device layer 200 grown by the subsequent epitaxial process.

In one embodiment of the present disclosure, the cutting process mentioned is to wait for the device layer 200 to grow in the device area 301 and perform the generally known epitaxial wafer process, and then cut from the top to the bottom from the approximately middle position of the protective layer 300 at both ends of the device layer 200 (as shown by the dotted line in Figure 2) to form the desired laser device 10.

It should be understood that after cutting, the width of the protective layer 300 located on both sides of the device layer 200 is determined according to the product specifications to be produced, so the cutting position is not necessarily located in the middle of the protective layer 300. In one embodiment, the cutting position may be closer to one side of the device layer 200; and in another embodiment, the cutting position may be in the protective layer 300 and away from the device layer 200, which is not further limited here.

A person skilled in the art should be able to make equivalent modifications without departing from the design concept of this disclosure.

Of course, this embodiment is only used for illustration and is not intended to limit the scope of the present disclosure. Equivalent modifications or changes made to the method for manufacturing the laser element of this embodiment should still be included in the patent scope of the present disclosure.

It is worth mentioning that the conventional manufacturing method of the laser device 10 is to first epitaxially grow the device layer 200 on the surface of the substrate 100, then remove the two ends of the device layer 200 by etching, and then grow the protective layer 300. Such a process flow will not only expose the device layer 200 to the subsequent process, so that the crystal quality of the device layer 200 in the light-emitting area is affected by the process environment, but also the device layer 200 needs to be exposed to the atmosphere for a long time, which increases the chance of oxide formation on the surface of the device layer 200. Therefore, the manufacturing method of the laser device 10 proposed in the present disclosure places the growth step of the device layer 200 at the end of the entire manufacturing process. Not only does the device layer 200 not need to be exposed to the etching liquid through the etching process, but also the process time of the device layer 200 being exposed to the atmosphere after the growth is completed is greatly shortened to avoid the formation of oxides. The manufacturing method of the laser device 10 according to the embodiment of the present disclosure not only prevents the formation of aluminum oxide or aluminum oxide in the process flow, but also shortens the time that the device layer 200 is exposed to the process or the atmosphere. Therefore, the laser device 10 produced by the manufacturing method of the laser device 10 disclosed in the present disclosure has better crystal quality, and the reliability of product quality also has obvious advantages.

Although the steps of the methods described in the present disclosure are shown and described in a specific order, the operation order of each method can be modified without departing from the principles and spirit of the present disclosure, and some steps can be performed in the opposite order, or some steps can be performed simultaneously with other steps. In another embodiment, different steps can be implemented in an intermittent and/or alternating manner.

It can be seen that the present disclosure has indeed achieved the desired improved effect by breaking through the previous technology, and it is not easy for people familiar with the technology to think of. Its progress and practicality obviously meet the patent application requirements. Therefore, a patent application is filed in accordance with the law. I sincerely request that your office approve this invention patent application to encourage creativity. I am truly grateful for your kindness.

The above description is for illustrative purposes only and is not intended to be limiting. Any other equivalent modifications or changes that do not depart from the spirit and scope of this disclosure should be included in the scope of the attached patent application.

10: Laser element 100: Substrate 200: Component layer 300: Protective layer 301: Component area

Figure 1 is a flow chart of a known laser device manufacturing method. Figure 2 is a flow chart of a laser device manufacturing method according to an embodiment of the present disclosure.

10: Laser element

100: Substrate

200: Component layer

300: Protective layer

301: Component area

Claims (7)

A method for manufacturing a laser element, comprising: providing a substrate; growing a protective layer on the upper surface of the substrate; performing an etching process on the protective layer to form a device region; growing a device layer in the device region; and performing a cutting process to form a laser element; wherein, when the laser element is used for a wavelength less than 1000nm, the substrate material is gallium arsenide (GaAs); and when the laser element is used for a wavelength greater than 1000nm, the substrate material is indium phosphide (InP). The manufacturing method of the laser element as claimed in claim 1, wherein the material of the protective layer is indium phosphide (InP) or indium gallium arsenide phosphide (InGaAsP). The manufacturing method of the laser device of claim 1, wherein the device layer material is indium aluminum gallium arsenide (InGaAlAs), indium gallium arsenide phosphide (InGaAsP), indium gallium arsenide (InGaAs) or indium phosphide (InP). A method for manufacturing a laser device as claimed in claim 1, wherein the etching process removes the middle area of the protective layer to form the device area. A method for manufacturing a laser device as claimed in claim 7, wherein the etching process places the device region approximately in the middle of the protective layer. A method for manufacturing a laser device as claimed in claim 1, wherein both ends of the device region are the protective layer. A method for manufacturing a laser element as claimed in claim 1, wherein the cutting process is to cut from the approximately middle position of the protective layer at both ends of the element layer from top to bottom to form the laser element.