Thermal plasma etching system and thermal plasma etching method

Abstract

To provide a thermal plasma etching system that improves an etching speed, reduces a surface roughness, and has a good anisotropic etching property, and provide a method.SOLUTION: A thermal plasma etching system 100 is suitable for etching a material comprises: a gas source 110; a plasma source 120; a heating module 130; a vacuum chamber 140; a diffusion disk 150; and an electrode plate 160. The gas source is suitable for providing gas, and the plasma source is connected to the gas source and generates plasma by dissociating the gas. The heating module is connected to the plasma source, heats the plasma to thermal plasma, is provided between the plasma source and the vacuum chamber, and introduces the thermal plasma into the vacuum chamber. The diffusion disk is provided in the vacuum chamber, and the electrode plate is provided in the vacuum chamber and is separated from the diffusion disk by a constant distance. A material is mounted on the electrode plate, and the thermal plasma is diffused to the electrode plate by the diffusion disk and etches the material positioned on the electrode plate.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a thermal plasma etching system and a thermal plasma etching method, and more particularly to a thermal plasma etching system and a thermal plasma etching method that can improve the etching rate, reduce the surface roughness after etching, and have better anisotropic etching characteristics.

Background Art

[0002] When etching a silicon carbide substrate with a conventional plasma etching system, since the chemical reaction of the silicon carbide substrate is relatively slow, the etching rate of the silicon carbide substrate by the conventional plasma etching system is relatively slow, and the surface of the silicon carbide substrate after etching is rough and inferior in anisotropic characteristics. Therefore, how to increase the etching rate of the plasma etching system, reduce the surface roughness after etching, and provide better anisotropic characteristics is an issue that the present field is working on.

Summary of the Invention

Problems to be Solved by the Invention

[0003] The present invention provides a thermal plasma etching system and a thermal plasma etching method that can improve the etching rate, reduce the surface roughness after etching, and have better anisotropic etching characteristics.

Means for Solving the Problems

[0004] The thermal plasma etching system of the present invention is suitable for etching an object and includes a gas source, a plasma source, a heating module, a vacuum chamber, a diffusion disk, and an electrode plate. The gas source is suitable for providing a gas. The plasma source is connected to the gas source and dissociates the gas to generate plasma. The heating module is connected to the plasma source and is used to heat the plasma into thermal plasma. The heating module is provided between the plasma source and the vacuum chamber, and the thermal plasma is suitable for being introduced into the vacuum chamber. The diffusion disk is provided in the vacuum chamber. The electrode plate is provided in the vacuum chamber, is separated from the diffusion disk by a certain distance, and is suitable for placing the object on the electrode plate. The thermal plasma is diffused to the electrode plate by the diffusion disk, and etches the object located on the electrode plate.

[0005] The thermal plasma etching method of the present invention provides plasma. The plasma is heated into thermal plasma. Further, the thermal plasma is introduced into the diffusion disk in the vacuum chamber, the thermal plasma is diffused to the electrode plate, and the object located on the electrode plate is etched.

[0006] In one embodiment of the present invention, the above-mentioned diffusion disk and the electrode plate are provided in parallel, and the distance is between 15 mm and 40 mm.

[0007] In one embodiment of the present invention, the above-mentioned heating module includes a heating tube, and a porous honeycomb structure and / or fins are provided in the heating tube.

[0008] In one embodiment of the present invention, the above-mentioned heating module includes a heating tube, the length of the heating tube is between 5 cm and 30 cm, and the temperature of the thermal plasma is between 100 °C and 500 °C.

[0009] In one embodiment of the present invention, in the above-mentioned step of heating the plasma, the time for which the plasma is heated is less than 10 seconds.

Advantages of the Invention

[0010] Based on the above, the thermal plasma etching system and the thermal plasma etching method of the present invention heat the plasma generated by the plasma source by a heating module into thermal plasma, and etch an object located on the electrode plate with the thermal plasma. With such a design, the etching speed can be improved, the surface roughness after etching can be reduced, and better anisotropic etching characteristics can be achieved.

Brief Description of the Drawings

[0011]

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DETAILED DESCRIPTION OF THE INVENTION

[0012] FIG. 1 is a schematic diagram of a thermal plasma etching system according to an embodiment of the present invention. Referring to FIG. 1, the thermal plasma etching system 100 of the present invention is suitable for etching an object 10. The thermal plasma etching system 100 includes a gas source 110, a plasma source 120, a heating module 130, a vacuum chamber 140, a diffusion disk 150, and an electrode plate 160. The gas source 110 is suitable for providing a gas. The plasma source 120 is connected to the gas source 110 and dissociates the gas to generate plasma. The heating module 130 is connected to the plasma source 120 and is used to heat the plasma into thermal plasma. The heating module 130 is provided between the plasma source 120 and the vacuum chamber 140, and the thermal plasma is suitable for being introduced into the vacuum chamber 140. The diffusion disk 150 is provided in the vacuum chamber 140. The electrode plate 160 is provided in the vacuum chamber 140, is connected to a power supply 170, and the electrode plate 160 and the diffusion disk 150 are separated by a distance D1, and the object 10 is suitable for being placed on the electrode plate 160. The thermal plasma is diffused to the electrode plate 160 by the diffusion disk 150 to etch the object 10 located on the electrode plate 160.

[0013] In this embodiment, the gas provided by the gas source 110 is nitrogen trifluoride (NF 3 ) and argon (Ar), and the ratio of nitrogen trifluoride (NF 3 ) to argon (Ar) is 1:1, and the gas flow rates are each 2 SLM. The process pressure is between 0.1 and 50 Torr. However, the present invention does not limit the type of gas, the gas flow rate, and the process pressure.

[0014] In this embodiment, the plasma source 120 is a Remote Plasma Source (RPS). However, the type of the plasma source 120 is not limited to this. In other embodiments, the plasma source 120 may be an Inductively Coupled Plasma (ICP).

[0015] In this embodiment, the frequency of the plasma source 120 is 400 KHz, and the high-frequency power is 1000 W. The frequency of the electrode plate 160 is 40.68 MHz, and the high-frequency power is 400 W. In other embodiments, the frequency of the plasma source 120 may be, for example, 13.56 MHz, 40.68 MHz, or any frequency between 100 KHz and 40 MHz. The frequency of the electrode plate 160 may be any frequency between 100 KHz and 40 MHz. The present invention does not limit the frequencies and high-frequency powers of the plasma source 120 and the electrode plate 160.

[0016] The material of the object 10 in the present invention may include, but is not limited to, silicon carbide (SiC), other compound semiconductor materials, or any combination of the foregoing materials. It can be understood that the object 10 of the present invention may also be other objects that form a desired surface topography using plasma etching.

[0017] FIG. 2 is a schematic diagram of a thermal plasma etching method according to an embodiment of the present invention. The thermal plasma etching method 200 of the present invention includes the following steps. First, in step 210, the thermal plasma etching system 100 provides a gas through the gas source 110. The plasma source 120 is connected to the gas source 110 to dissociate the gas and provide plasma. Next, in step 220, the thermal plasma etching system 100 heats the plasma by the heating module 130 to turn the plasma into thermal plasma. Finally, in step 230, the thermal plasma etching system 100 introduces the thermal plasma into the diffusion disk 150 in the vacuum chamber 140, diffuses the thermal plasma to the electrode plate 160, and etches the object 10 located on the electrode plate 160.

[0018] The thermal plasma etching system 100 and the thermal plasma etching method 200 of the present invention heat the plasma generated by the plasma source 120 by the heating module 130 to form a thermal plasma, improve the ion energy of the thermal plasma, and make the ions of the thermal plasma have higher impact energy. With such a design, the etching rate of the thermal plasma etching object 10 can be improved, the surface roughness after etching can be reduced, and the characteristics of anisotropic etching can be improved, thereby improving the performance of the object 10.

[0019] Continuing to refer to FIG. 1, in this embodiment, in the Y-axis direction, the diffusion disk 150 is located above the electrode plate 160, and the diffusion disk 150 and the electrode plate 160 are provided in parallel, that is, the normal directions of the diffusion disk 150 and the electrode plate 160 are both parallel to the Y-axis. Also, the distance D1 between the diffusion disk 150 and the electrode plate 160 is between 15 mm and 40 mm, but the distance D1 between the diffusion disk 150 and the electrode plate 160 is not limited thereto. In some examples, when the aforementioned distance D1 is between 15 mm and 40 mm, the thermal plasma passing through the diffusion disk 150 can be more effectively guided to etch the object 10 and improve the characteristics of anisotropic etching.

[0020] Also, the heating module 130 includes a heating tube 131. The length L1 of the heating tube 131 is between 5 cm and 30 cm, and the time for the plasma to be heated by the heating tube 131 is less than 10 seconds, and the temperature of the thermal plasma is between 100°C and 500°C. Thereby, the etching rate can be effectively improved, the surface roughness after etching can be reduced, and the characteristics of anisotropic etching can be improved.

[0021] As a point worth mentioning, in the thermal plasma etching system 100, the length L1 of the heating tube 131 is between 5 cm and 30 cm, and the time for which the plasma is heated is less than 10 seconds, so that the possibility of the thermal plasma returning to a stable state due to an overly long heating time can be more effectively reduced.

[0022] It should be noted that the thermal plasma etching system 100 can control the time for which the plasma is heated by other methods. For example, a pressurizer (not shown) can be added to the plasma source 1202 to increase the speed at which the plasma passes through the heating tube 131, so that the plasma can be heated to the target temperature without returning to a stable state due to an overly long heating time. The present invention does not limit the method for controlling the time for which the plasma is heated.

[0023] On the other hand, it should be noted that the position of the heating module 130 is not limited to the position shown in FIG. 1, and the heating module 130 can be provided at any position between the plasma source 120 and the vacuum chamber 140. The temperature of the thermal plasma when introduced into the vacuum chamber 140 is preferably between 100°C and 500°C.

[0024] FIG. 3A is a schematic cross-sectional view of the heating tube along the A-A cross-sectional line of the thermal plasma etching system of FIG. 1. FIG. 3B is a schematic cross-sectional view of the heating tube according to another embodiment of the present invention. It should be noted that in FIGS. 3A and 3B, the heating device around the heating tube 131 is not shown. First, referring to FIG. 3A, in this embodiment, a porous honeycomb structure is provided in the heating tube 131 of the heating module 130. However, the structure inside the heating tube 131 is not limited to this, and in other embodiments, fins shown in FIG. 3B may be provided inside the heating tube 131, or any other structure capable of improving the heat exchange rate of the plasma, or any combination of the foregoing structures may be used. The present invention does not limit the structure inside the heating tube 131.

[0025] As a point worthy of mention, in the thermal plasma etching system 100, by providing a porous honeycomb structure and / or fins in the heating tube 131, the heat exchange rate between the plasma generated by the plasma source 120 and the heating tube 131 can be improved, and the heating time of the plasma can be reduced. With such a design, it is possible to reduce the possibility that the thermal plasma returns to a stable state due to an overly long heating time.

[0026] Figure 4A shows the intensity-time relationship of the spectral analysis of a conventional plasma. Figure 4B shows the intensity-time relationship of the spectral analysis of the thermal plasma in Figure 2. It should be noted that Figure 4A and Figure 4B are schematic intensity-time diagrams after observing the conventional plasma and the thermal plasma in Figure 2 with an optical emission spectroscopy (OES), respectively. Referring to Figure 4A and Figure 4B, compared with the conventional plasma, the intensity of the fluorine plasma of the thermal plasma of the present invention is significantly improved in the emission spectra of 703.9 nm and 685.8 nm, and the enhancement rates are 8.3% and 12% respectively, indicating that both the total gas dissociation amount and the energy of the thermal plasma increase.

[0027] Figure 5 shows the intensity-time relationship of the spectral analysis of argon plasma and fluorine plasma at different temperatures. Referring to Figure 5, when the fluorine plasma and the argon plasma are heated to 100 °C or 300 °C, their intensities are higher than those of the fluorine plasma and the argon plasma at 25 °C, indicating that the higher the temperature of the display plasma, the more both the total gas dissociation amount and the energy of the plasma increase.

[0028] FIG. 6 is a schematic diagram of the etching depth of an object in a conventional plasma etching system and the thermal plasma etching system of FIG. 1. It should be noted that after etching the object 10, the depth of its surface can be confirmed using a surface profiler, and the etching rate can be calculated from the depth and the total etching time. Referring to FIG. 6, the surface etching depth of the object 10 after etching for 5 minutes by the conventional plasma etching system is 21,650 angstroms, and the calculated etching rate is 0.43 microns / minute. Also, the surface etching depth of the object 10 after etching for 5 minutes by the thermal plasma etching system 100 of the present invention is 37,150 angstroms, and the calculated etching rate is 0.74 microns / minute. That is, the thermal plasma etching system 100 of the present invention has a faster etching rate.

[0029] FIG. 7A is a surface etching topography diagram of an object etched by a conventional plasma etching system. FIG. 7B is a surface etching topography diagram of an object etched at a thermal plasma temperature of 100° C. by the thermal plasma etching system of FIG. 1. FIG. 7C is a surface etching topography diagram of an object etched at a thermal plasma temperature of 300° C. by the thermal plasma etching system of FIG. 1. Referring to FIGS. 7A to 7C, the thermal plasma etching system 100 of the present invention can adjust the surface topography and characteristics of the object 10 by adjusting the temperature of the heating module 130 so that the thermal plasma has different temperatures. Also, in other embodiments, the thermal plasma etching system 100 can also adjust the surface topography and characteristics of the object 10 by adjusting the gas ratio.

[0030] Summarizing the above, the thermal plasma etching system and the thermal plasma etching method of the present invention heat the plasma generated by the plasma source by the heating module to thermal plasma, and etch the object located on the electrode plate with the thermal plasma. With such a design, the etching speed can be improved, the surface roughness after etching can be reduced, and better anisotropic etching characteristics can be achieved. Further, in the thermal plasma etching system and the thermal plasma etching method, by providing a porous honeycomb structure or fins in the heating tube of the heating module, the heat exchange rate between the plasma and the heating tube can be improved. On the other hand, in the thermal plasma etching system and the thermal plasma etching method, by further setting the length of the heating tube to 5 cm to 30 cm and setting the time for which the plasma is heated to less than 10 seconds, the possibility of the thermal plasma returning to a stable state can be reduced.

Industrial Applicability

[0031] The present invention relates to a thermal plasma etching system and a thermal plasma etching method, and particularly to a thermal plasma etching system and a thermal plasma etching method capable of improving the etching speed, reducing the surface roughness after etching, and having better anisotropic etching characteristics.

Explanation of Reference Numerals

[0032] 10: Object 100: Thermal plasma etching system 110: Gas source 120: Plasma source 130: Heating module 131: Heating tube 140: Vacuum chamber 150: Diffusion disk 160: Electrode plate 170: Power supply 200: Thermal plasma etching method 210~230: Steps D1: Distance L1: Length X, Y: Axial directions

Claims

1. A thermal plasma etching system suitable for etching an object, a gas source suitable for providing a gas, a plasma source connected to the gas source and used to dissociate the gas to generate plasma, a heating module connected to the plasma source and used to heat the plasma into thermal plasma, a vacuum chamber suitable for introducing the thermal plasma, a diffusion disk provided in the vacuum chamber, an electrode plate provided in the vacuum chamber, provided at a predetermined distance from the diffusion disk and suitable for placing the object, comprising: the heating module is provided between the plasma source and the vacuum chamber, the thermal plasma is diffused to the electrode plate by the diffusion disk, and the object on the electrode plate is etched, a thermal plasma etching system.

2. The diffusion disk and the electrode plate are provided in parallel, and the distance is between 15 mm and 40 mm. The thermal plasma etching system according to claim 1.

3. The heating module includes a heating tube, and a porous honeycomb structure and / or fins are provided in the heating tube. The thermal plasma etching system according to claim 1.

4. When the thermal plasma is introduced into the vacuum chamber, the temperature of the thermal plasma is between 100°C and 500°C. The thermal plasma etching system according to claim 1.

5. The heating module includes a heating tube, and the length of the heating tube is between 5 cm and 30 cm. The thermal plasma etching system according to claim 4.

6. A step of providing plasma, a step of heating the plasma into thermal plasma, a step of introducing the thermal plasma into a diffusion disk in a vacuum chamber, diffusing the thermal plasma to an electrode plate, and etching an object located on the electrode plate, a plasma etching method.

7. In the step of introducing the thermal plasma into the vacuum chamber, the temperature of the thermal plasma is between 100°C and 500°C. The thermal plasma etching method according to claim 6.

8. In the step of heating the plasma, the time for which the plasma is heated is less than 10 seconds. The thermal plasma etching method according to claim 7.

9. In the step of heating the plasma, the plasma passes through a heating tube to become the hot plasma, and a porous honeycomb structure and / or fins are provided in the heating tube. The hot plasma etching method according to claim 6.

10. The diffusion disk and the electrode plate are provided in parallel, and the distance between the diffusion disk and the electrode plate is between 15 mm and 40 mm. The hot plasma etching method according to claim 6.

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