Method for improving defects of silicon carbide epitaxial wafer by using electroplating machine

Abstract

The application discloses a method for improving defects of silicon carbide epitaxial wafers by using an electroplating machine, which can improve the B-grade silicon carbide epitaxial wafers into A-grade silicon carbide epitaxial wafers, effectively improves production efficiency and reduces production cost. The method comprises the following steps: S101, selecting pre-processed epitaxial wafers; B-grade silicon carbide epitaxial wafers are selected; S102, preparing porous silicon carbide; defects of the silicon carbide epitaxial wafers are converted into porous silicon carbide by applying a specific voltage in an electroplating machine; the operation voltage of the electroplating machine is 10-50V, 0.1-1A and 5-30 minutes; S103, conversion treatment; the porous silicon carbide is sent into a high-temperature furnace tube for conversion treatment, and is converted into an epitaxial silicon dioxide wafer; the operation condition is that the temperature of the high-temperature furnace tube is 1150 DEG C-1200 DEG C, and the heating time is 1-2 hours; S104, hydrofluoric acid surface treatment; the epitaxial silicon dioxide wafer obtained in S103 is etched and removed in a hydrofluoric acid tank, and A-grade silicon carbide epitaxial wafers are obtained.

Description

Technical Field

[0001] This invention relates to the field of silicon carbide epitaxial wafer technology, specifically to a method for improving defects in silicon carbide epitaxial wafers using an electroplating machine. Background Technology

[0002] Silicon carbide power devices differ from traditional silicon power devices in their fabrication process. They cannot be directly fabricated on a silicon carbide single-crystal substrate. Instead, high-quality epitaxial materials must be grown on the single-crystal substrate, and various devices must be manufactured on the epitaxial layer.

[0003] There are many types of defects in silicon carbide epitaxial wafers. Due to the different crystals, their defects are not quite the same as those of other crystals. The main defects include micropipes, triangular defects, carrot defects on the surface, and some unique ones such as step aggregation. Many defects on silicon carbide epitaxial wafers are directly replicated from the silicon carbide substrate. Therefore, the quality and processing level of the silicon carbide substrate are very important for controlling the growth defects of the silicon carbide epitaxial layer. During the processing of silicon carbide epitaxial wafers, the stack fault of the crystal itself causes defects during epitaxial manufacturing. Therefore, it is difficult to flatten the epitaxial silicon wafer and achieve Grade A specifications. Most silicon carbide epitaxial wafers can only meet the Grade B silicon carbide quality.

[0004] Currently, the industry uses grinding and polishing to improve surface defects in silicon carbide epitaxial wafers. However, this process is time-consuming and the cost of manufacturing silicon carbide epitaxial wafers is high. Therefore, this application provides a method for improving defects in silicon carbide epitaxial wafers using an electroplating machine, offering a new direction and possibility for the production of high-quality silicon carbide epitaxial wafers. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a method for improving defects in silicon carbide epitaxial wafers using an electroplating machine. This method can improve B-grade silicon carbide epitaxial wafers to A-grade specifications, effectively increasing production efficiency and reducing production costs.

[0006] A method for improving defects in silicon carbide epitaxial wafers using an electroplating machine includes the following steps: S101, Selecting a pre-processed epitaxial wafer: Selecting a B-grade silicon carbide epitaxial wafer;

[0007] S102. Preparation of porous silicon carbide: Apply a specific voltage in an electroplating machine to transform defects in silicon carbide epitaxial wafers into porous silicon carbide; the operating voltage of the electroplating machine is 10-50V, 0.1-1A, for 5-30 minutes.

[0008] S103. Conversion treatment: The porous silicon carbide is fed into a high-temperature furnace tube for conversion treatment and converted into epitaxial silicon dioxide wafers. The operating conditions are that the temperature of the high-temperature furnace tube is 1150℃-1200℃ and the heating time is 1-2 hours.

[0009] S104, Hydrofluoric Acid Surface Treatment: The epitaxial silicon dioxide wafer obtained in S103 is etched away in a hydrofluoric acid bath to obtain a silicon carbide epitaxial wafer conforming to specification A.

[0010] Preferably, the electroplating machine includes a power supply, a cathode, an electrolyte, and an anode. Inside the electroplating machine, there is a cavity for accommodating a silicon carbide epitaxial wafer. The cavity contains an electrolyte. A cathode capable of contacting the upper surface of the silicon carbide epitaxial wafer is located at the top of the cavity, and an anode capable of contacting the lower surface of the silicon carbide epitaxial wafer is located at the bottom of the cavity. Both the cathode and the anode are connected to the power supply.

[0011] Preferably, the porous silicon carbide is converted into silicon dioxide using a high-temperature furnace tube.

[0012] Preferably, the epitaxial silicon dioxide wafer heated in S103 undergoes a tempering treatment in a high-temperature furnace tube for 1 hour, with the tempering temperature being 800°C.

[0013] Preferably, the epitaxial silicon dioxide wafer is allowed to cool naturally for 24 hours after tempering before entering step S104.

[0014] Compared with the prior art, the present invention provides a method for improving defects in silicon carbide epitaxial wafers using an electroplating machine, which has the following beneficial effects:

[0015] 1. The method for improving defects in silicon carbide epitaxial wafers involves applying a voltage to create porous silicon carbide on the surface of the silicon carbide epitaxial wafer, and then sending the porous silicon carbide into a high-temperature furnace tube for conversion treatment to convert the porous silicon carbide into silicon dioxide. This silicon dioxide is easily removed by hydrofluoric acid surface treatment.

[0016] 2. The method for improving defects in silicon carbide epitaxial wafers has a short processing time and high yield. The process is easy to control and can transform the defects in silicon carbide epitaxial wafers. First, the epitaxial defects are transformed into porous silicon carbide. Then, the porous silicon carbide is transformed into silicon dioxide at high temperature. Finally, the silicon dioxide is removed by hydrofluoric acid, which greatly improves production efficiency and reduces costs. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the electroplating machine structure of the present invention.

[0018] Figure 2 This is a schematic diagram of the silicon carbide wafer structure in this invention.

[0019] Figure descriptions: 1. Silicon carbide epitaxial wafer, 2. Power supply, 3. Cathode, 4. Electrolyte, 5. Anode. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see Figure 1 A method for improving defects in silicon carbide epitaxial wafers using an electroplating machine includes the following steps:

[0022] S101. Select pre-processed epitaxial wafers: Select B-grade silicon carbide epitaxial wafers;

[0023] S102. Preparation of porous silicon carbide: Apply a specific voltage in an electroplating machine to transform the defects in silicon carbide epitaxial wafer 1 into porous silicon carbide; the operating voltage of the electroplating machine is 10-50V, 0.1-1A, for 5-30 minutes.

[0024] S103. Conversion treatment: The porous silicon carbide is fed into a high-temperature furnace tube for conversion treatment and converted into epitaxial silicon dioxide wafers. The operating conditions are that the temperature of the high-temperature furnace tube is 1150℃-1200℃ and the heating time is 1-2 hours.

[0025] S104, Hydrofluoric Acid Surface Treatment: The epitaxial silicon dioxide wafer obtained in S103 is etched away in a hydrofluoric acid bath to obtain a silicon carbide epitaxial wafer conforming to specification A.

[0026] In this embodiment, the electroplating machine includes a power supply 2, a cathode 3, an electrolyte 4, and an anode 5. Inside the electroplating machine, there is a cavity for accommodating a silicon carbide epitaxial wafer 1. The cavity contains an electrolyte 4. The top of the cavity is provided with a cathode 3 that can contact the upper surface of the silicon carbide epitaxial wafer 1, and the bottom of the cavity is provided with an anode 5 that can contact the lower surface of the silicon carbide epitaxial wafer 1. Both the cathode 3 and the anode 5 are connected to the power supply 2.

[0027] In this embodiment, the porous silicon carbide is converted into silicon dioxide using a high-temperature furnace tube.

[0028] In this embodiment, the epitaxial silicon dioxide wafer heated in S103 undergoes a tempering treatment in a high-temperature furnace tube for 1 hour, and the tempering temperature is 800°C.

[0029] In this embodiment, the epitaxial silicon dioxide wafer is allowed to cool naturally for 24 hours after tempering before proceeding to step S104.

[0030] Working principle: The method for improving defects in silicon carbide epitaxial wafer 1 involves the following steps: First, selecting silicon carbide epitaxial wafer 1: Selecting a B-grade silicon carbide epitaxial wafer 1. Second, preparing porous silicon carbide: Applying voltage in an electroplating machine transforms the defects in the silicon carbide epitaxial wafer 1 into porous silicon carbide. Then, performing a conversion treatment: The porous silicon carbide is sent to a high-temperature furnace tube for conversion treatment, transforming the porous silicon carbide into silicon dioxide. Finally, performing hydrofluoric acid surface treatment: The converted silicon carbide epitaxial wafer 1 is placed in a hydrofluoric acid bath, where hydrofluoric acid reacts with the silicon dioxide on the surface of the silicon carbide epitaxial wafer 1 to etch away most of the silicon dioxide, thus achieving an A-grade silicon carbide epitaxial wafer.

[0031] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for improving defects in silicon carbide epitaxial wafers using an electroplating machine, characterized in that: Includes the following steps: S101. Select pre-processed epitaxial wafers: Select B-grade silicon carbide epitaxial wafers; S102. Preparation of porous silicon carbide: Apply a voltage of 10-50V, 0.1-1A, for 5-30 minutes in an electroplating machine to transform the defects of the silicon carbide epitaxial wafer (1) into porous silicon carbide. S103, Conversion Treatment: The porous silicon carbide is fed into a high-temperature furnace tube for conversion treatment and converted into epitaxial silicon dioxide wafers. The working conditions are that the temperature of the high-temperature furnace tube is 1150℃-1200℃ and the heating time is 1-2 hours. After heating, the epitaxial silicon dioxide wafers are tempered in the high-temperature furnace tube for another hour at a temperature of 800℃. After tempering, the epitaxial silicon dioxide wafers are allowed to cool naturally for 24 hours before proceeding to step S104. S104, Hydrofluoric Acid Surface Treatment: The epitaxial silicon dioxide wafer obtained in S103 is etched and removed in a hydrofluoric acid bath to obtain a silicon carbide epitaxial wafer conforming to specification A.

2. The method for improving defects in silicon carbide epitaxial wafers using an electroplating machine according to claim 1, characterized in that: The electroplating machine includes a power supply (2), a cathode (3), an electrolyte (4), and an anode (5). Inside the electroplating machine, there is a cavity for accommodating a silicon carbide epitaxial wafer (1). The cavity contains an electrolyte (4). The top of the cavity is provided with a cathode (3) that can contact the upper surface of the silicon carbide epitaxial wafer (1), and the bottom of the cavity is provided with an anode (5) that can contact the lower surface of the silicon carbide epitaxial wafer (1). Both the cathode (3) and the anode (5) are connected to the power supply (2).

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