Method for forming wet oxidation aperture of vertical resonator type surface emitting laser device

Abstract

To form a wet oxidation aperture shape of an epitaxial layer of a vertical resonator type surface emitting laser device to be substantially circular.SOLUTION: A method for forming a wet oxidation aperture shape of a vertical resonator type surface emitting laser device includes the steps of: placing a vertical resonator type surface emitting laser wafer having a circular vertical resonator type surface emitting laser mesa with a diameter of 25-30 μm into a wet oxidation furnace; vacuumizing the wet oxidation furnace; ramping up the temperature of the wet oxidation furnace to 250-350°C, maintaining the temperature, and introducing N2 gas and H2O gas; ramping up the temperature to 350-450°C while introducing N2 gas and H2O gas into the wet oxidation furnace, and maintaining the temperature; ramping up the temperature to 400-450°C while introducing N2 gas and H2O gas, and maintaining the temperature; maintaining the temperature at 400-450°C to initiate oxidation of the vertical resonator type surface emitting laser wafer; introducing N2 gas to cool the temperature down to 150°C; and taking out the vertical resonator type surface emitting laser wafer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a vertical cavity surface emitting laser element, and more particularly to a method for forming wet oxidation holes (holes formed by wet oxidation treatment) in a vertical cavity surface emitting laser element. [Background technology]

[0002] In recent years, vertical cavity surface emitting laser (VCSEL) elements have been widely used as light sources in electronic devices (e.g., virtual reality (VR) sensing devices).

[0003] The wet oxidation holes in the epitaxial layer of the conventional 650 nm vertical cavity surface emitting laser element are diamond-shaped or shield-shaped, and there are almost no circular holes. In the conventional technology, only the wet oxidation holes in the epitaxial layer of the 940 nm vertical cavity surface emitting laser element are approximately circular. However, since the structures and growth characteristics of the epitaxial layers of the 650 nm vertical cavity surface emitting laser element and the 940 nm vertical cavity surface emitting laser element are essentially different, the epitaxial layer of the 650 nm vertical cavity surface emitting laser element cannot have the wet oxidation holes formed approximately circular like the epitaxial layer of the 940 nm vertical cavity surface emitting laser element.

[0004] In view of the above circumstances, how to form circular wet oxidation holes in the epitaxial layer of a 650 nm vertical cavity surface emitting laser element has become an urgent issue in the industry. Summary of the Invention

[0005] The objective of the present invention is to improve the stability, reliability and durability of 650 nm vertical cavity surface emitting laser devices. By adjusting the operating parameters of a wet oxidation furnace, the wet oxidation holes in the epitaxial layers of 650 nm vertical cavity surface emitting laser devices are formed in a substantially circular shape.

[0006] In order to achieve the above object, the present invention discloses a method for forming wet oxidation holes in a vertical cavity surface emitting laser device, the method includes the steps of: placing a vertical cavity surface emitting laser wafer having a circular vertical cavity surface emitting laser mesa with a diameter of 25 um to 30 um in a wet oxidation furnace; evacuating the wet oxidation furnace; increasing the temperature of the wet oxidation furnace to 250 to 350°C and maintaining the temperature during a first period, and introducing N2 gas and H2O gas into the wet oxidation furnace during the first period; and increasing the temperature of the wet oxidation furnace to 350 to 450°C while introducing N2 gas and H2O gas into the wet oxidation furnace and maintaining the temperature during a second period. a step of increasing the temperature of the wet oxidation furnace to 400-450°C while introducing N2 gas and H2O gas into the wet oxidation furnace and maintaining the temperature during a third period; a step of maintaining the temperature of the wet oxidation furnace at 400-450°C to oxidize the vertical cavity surface emitting laser wafer; a step of introducing N2 gas into the wet oxidation furnace and decreasing the temperature to 150°C after the oxidation of the vertical cavity surface emitting laser wafer is completed; and a step of removing the vertical cavity surface emitting laser wafer from the wet oxidation furnace after cooling to 150°C.

[0007] In an embodiment of the present invention, the method further includes the steps of: before placing the vertical cavity surface emitting laser wafer in the wet oxidation furnace, in a standby state of a wet oxidation treatment device, introducing N2 gas and H2O gas into the wet oxidation furnace and checking whether the flow rates of N2 gas and H2O gas are normal; and after checking that the flow rates of N2 gas and H2O gas are normal, placing the vertical cavity surface emitting laser wafer in the wet oxidation furnace.

[0008] In an embodiment of the present invention, the N2 gas is introduced into the wet oxidation furnace at 10 liters / minute (L / min).

[0009] In an embodiment of the present invention, H2O gas is introduced into the wet oxidation furnace at 2 grams per hour (g / h).

[0010] In an embodiment of the present invention, the temperature of the wet oxidation furnace is increased to 250-350° C. at a rate of 10-40° C. / min.

[0011] In an embodiment of the invention, the first period of time is 6 to 8 minutes.

[0012] In an embodiment of the present invention, the temperature of the wet oxidation furnace is increased to 350-450° C. at a rate of 10-30° C. / min.

[0013] In an embodiment of the invention, the second period of time is 1 to 2 minutes.

[0014] In an embodiment of the present invention, the temperature of the wet oxidation furnace is increased to 400-450° C. at a rate of 10-25° C. / min.

[0015] In an embodiment of the present invention, the third period is 1 to 2 minutes.

[0016] In an embodiment of the present invention, the method further includes removing the vertical cavity surface emitting laser wafer from the wet oxidation furnace and allowing the vertical cavity surface emitting laser wafer to cool naturally at room temperature.

[0017] Those skilled in the art can understand other objects of the present invention, as well as the technical means and embodiments of the present invention, by referring to the drawings and the embodiments described below. [Brief description of the drawings]

[0018] [Figure 1] A flow chart showing a method for forming a wet oxidation hole in a vertical cavity surface emitting laser element according to the present invention. [Diagram 2] A top view of a vertical cavity surface emitting laser wafer of the present invention having a circular vertical cavity surface emitting laser mesa with a diameter of 25 um to 30 um. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The contents of the present invention will be described below through examples. The examples of the present invention are examples of embodiments, and are not intended to limit the present invention to the environments, applications, or specific aspects described in the examples. Therefore, the explanation of the examples is for explaining the present invention, but does not limit the present invention. In the embodiments and drawings, components that are not directly related to the present invention are omitted and not shown. The dimensional relationship between the components in the drawings is for ease of understanding, and does not limit the actual dimensions.

[0020] In an embodiment of the present invention, FIG. 1 is a flow chart illustrating a method 100 for forming wet oxidation holes in a vertical cavity surface emitting laser device.

[0021] First, in step S101, a vertical cavity surface emitting laser (VCSEL) wafer is placed in a wet oxidation furnace. The vertical cavity surface emitting laser wafer has a circular vertical cavity surface emitting laser mesa with a diameter of 25 um to 30 um. In this embodiment, the vertical cavity surface emitting laser wafer is a 4-inch wafer. For example, FIG. 2 is a top view showing a VCSEL wafer 200 of the present invention. The vertical cavity surface emitting laser wafer 200 shown in FIG. 2 has a circular vertical cavity surface emitting laser mesa with a diameter D of 25 um to 30 um. The vertical cavity surface emitting laser mesa is a structure formed by epitaxial layer growth, masking, exposure development, and etching in the manufacturing process of a 650 nm VCSEL, which can be understood by anyone with ordinary knowledge in the technical field to which the present invention belongs, and therefore a description thereof will be omitted.

[0022] Next, in step S103, the wet oxidation furnace is evacuated. In step S105, the temperature of the wet oxidation furnace is increased to 250-350°C, and the temperature is maintained during the first period. N2 gas and H2O gas are introduced into the wet oxidation furnace during the first period. In step S107, while introducing N2 gas and H2O gas into the wet oxidation furnace, the temperature of the wet oxidation furnace is increased to 350-450°C, and the temperature is maintained during the second period. In step S109, while introducing N2 gas and H2O gas into the wet oxygen furnace, the temperature of the wet oxygen furnace is increased to 400-450°C, and the temperature is maintained during the third period. In step S105, introducing N2 gas and H2O gas during the first period means introducing N2 gas and H2O gas under constant temperature conditions. In steps S107 and S109, introducing N2 gas and H2O gas means introducing N2 gas and H2O gas under elevated temperature and constant temperature conditions.

[0023] Next, in step S111, the temperature of the wet oxidation furnace is maintained at 400-450°C to oxidize the vertical cavity surface emitting laser wafer. Specifically, when the temperature of the wet oxidation furnace reaches 400-450°C, which is a temperature required for oxidation, oxidation begins. Then, in step S113, after the oxidation of the vertical cavity surface emitting laser wafer is completed, N2 gas is introduced into the wet oxidation furnace to lower the temperature to 150°C. Specifically, when the vertical cavity surface emitting laser wafer is oxidized and the wet oxidation hole reaches a predetermined shape, N2 gas for cooling is introduced to terminate the oxidation. In practice, it takes about one hour to cool to 150°C in step S113. In step S115, after cooling to 150°C, the vertical cavity surface emitting laser wafer is taken out of the wet oxidation furnace.

[0024] In an embodiment of the present invention, before step S101, the method 100 further includes the steps of: introducing N2 gas and H2O gas into the wet oxidation furnace in a standby state of the wet oxidation treatment device, and checking whether the flow rates of N2 gas and H2O gas are normal; and after checking that the flow rates of N2 gas and H2O gas are normal, putting the VCSEL wafer into the wet oxidation furnace. In this way, the wet oxidation process can achieve a desired result. The wet oxidation treatment device is an apparatus including a wet oxidation furnace for the wet oxidation process.

[0025] In an embodiment of the present invention, N2 gas is preferably introduced into the wet oxidation furnace at 10 liters per minute (L / min).

[0026] In an embodiment of the present invention, H2O gas is preferably introduced into the wet oxidation furnace at 2 grams per hour (g / h).

[0027] In the embodiment of the present invention, the temperature increase in the wet oxidation furnace to 250-350° C. is preferably carried out at a rate of 10-40° C. / min.

[0028] In an embodiment of the present invention, the first period is preferably 6 to 8 minutes.

[0029] In the embodiment of the present invention, the temperature increase in the wet oxidation furnace to 350-450° C. is preferably carried out at a rate of 10-30° C. / min.

[0030] In an embodiment of the present invention, the second period is preferably 1 to 2 minutes.

[0031] In the embodiment of the present invention, the temperature increase in the wet oxidation furnace to 400-450° C. is preferably carried out at a rate of 10-25° C. / min.

[0032] In an embodiment of the present invention, the third period is preferably 1 to 2 minutes.

[0033] In order to form substantially circular wet oxidation holes in the epitaxial layer of the 650 nm vertical cavity surface emitting laser device, the above parameters such as the period and the heating rate are exemplified as preferred parameters, however, adjustments to these parameters made by a person skilled in the art to which the present invention pertains based on the steps of the method of the present invention are within the scope of protection of the present invention.

[0034] In an embodiment of the present invention, after step S115, the method 100 further includes removing the vertical cavity surface emitting laser wafer from the wet oxidation furnace and allowing the vertical cavity surface emitting laser wafer to cool naturally at room temperature. In another embodiment of the present invention, after removing the vertical cavity surface emitting laser wafer from the wet oxidation furnace, the vertical cavity surface emitting laser wafer can be cooled in a non-room temperature environment to increase the cooling rate.

[0035] As mentioned above, the present invention provides a method for forming wet oxidation pits in a vertical cavity surface emitting laser device. The present invention forms a substantially circular wet oxidation pit in the epitaxial layer of a 650 nm vertical cavity surface emitting laser device by adjusting the operating parameters of a wet oxidation furnace. Therefore, the present invention can effectively improve the stability, reliability and durability of the 650 nm vertical cavity surface emitting laser device.

[0036] The above examples are for explaining the embodiments of the present invention and for explaining the characteristic configuration of the present invention. The present invention is not limited to the above examples. Modifications or equivalent arrangements that can be easily made by those skilled in the art are also within the scope of the present invention. The scope of protection of the rights of the present invention is based on the claims. [Explanation of symbols]

[0037] 100 ways 200 Vertical Cavity Surface Emitting Laser Wafer D diameter S101~S115 Steps

Claims

1. A method for forming wet oxidation holes in a vertical cavity surface emitting laser device, comprising the steps of: placing a vertical cavity surface emitting laser wafer having a circular vertical cavity surface emitting laser mesa with a diameter of 25 um to 30 um into a wet oxidation furnace; applying a vacuum to the wet oxidation furnace; The temperature of the wet oxidation furnace is increased to 250-350° C. and maintained at that temperature for a first period of time, and N ２ Gas and H ２ introducing O gas into the wet oxidation furnace; The wet oxidation furnace is filled with N ２ Gas and H ２ increasing the temperature of the wet oxidation furnace to 350-450° C. while introducing O gas, and maintaining the temperature during a second period; The wet oxidation furnace is filled with N ２ Gas and H ２ increasing the temperature of the wet oxidation furnace to 400-450° C. while introducing O gas, and maintaining the temperature during a third period; maintaining the temperature of the wet oxidation furnace at 400-450° C. to oxidize the vertical cavity surface emitting laser wafer; After the oxidation of the vertical cavity surface emitting laser wafer is completed, the wet oxygen furnace is charged with N ２ introducing gas and reducing the temperature to 150°C; and removing the vertical cavity surface emitting laser wafer from the wet oxidation furnace after cooling to 150° C.

2. before placing the vertical cavity surface emitting laser wafer in the wet oxidation furnace; In the standby state of the wet oxidation treatment device, N ２ Gas and H ２ O gas was introduced, and N ２ Gas flow rate and H ２ Checking whether the flow rate of O gas is normal; N ２ Gas flow rate and H ２ 2. The method of claim 1, further comprising: after confirming that the flow rate of O gas is normal, placing the vertical cavity surface emitting laser wafer in the wet oxidation furnace.

3. The N ２ 2. The method of claim 1, wherein gas is introduced into the wet oxidation furnace at 10 liters per minute (L / min).

4. The H ２ 2. The method of claim 1, wherein O gas is introduced into the wet oxidation furnace at 2 grams per hour (g / h).

5. 2. The method of claim 1, wherein the temperature increase in the wet oxidation furnace to 250-350° C. is performed at 10-40° C. / min.

6. 2. The method of claim 1, wherein the first period of time is between 6 and 8 minutes.

7. 2. The method of claim 1, wherein the temperature increase in the wet oxidation furnace to 350-450° C. is performed at 10-30° C. / min.

8. 2. The method of claim 1, wherein the second period of time is between 1 and 2 minutes.

9. 2. The method of claim 1, wherein the temperature increase in the wet oxidation furnace to 400-450° C. is performed at 10-25° C. / min.

10. 2. The method of claim 1, wherein the third period of time is between 1 and 2 minutes.

11. 10. The method of claim 1, further comprising removing the vertical cavity surface emitting laser wafer from the wet oxidation furnace and allowing the vertical cavity surface emitting laser wafer to cool naturally at room temperature.

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