A CVD-SiC surface thermal oxidation method and system

Abstract

This invention relates to a CVD-SiC surface thermal oxidation method and system, relating to the field of advanced semiconductor etching processes (within 28nm). The method includes the following steps: placing a CVD-SiC workpiece in a reaction chamber, the reaction chamber consisting of a quartz base and a silicon carbide outer cover placed above the quartz base; introducing ultrapure water vapor into a vaporization chamber filled with high-purity quartz beads, simultaneously introducing oxygen and adjusting its flow rate to obtain saturated oxygen-carrying water vapor; introducing the saturated oxygen-carrying water vapor into the reaction chamber to cause an oxidation reaction on the surface of the CVD-SiC workpiece, obtaining a silicon dioxide layer with an oxidation depth of 0.8–1.5 μm. Defects on the CVD-SiC workpiece surface caused by machining, such as microcracks and scratches, are oxidized, thereby eliminating these defects. This improves the interface state consistency and integrity of the CVD-SiC workpiece surface, significantly extends the particle generation time of the etching ring, focusing ring, and spray head components, thereby improving the quality, stability, and PM time of the advanced process etching process, and significantly reducing the overall cost.

Description

Technical Field

[0001] This invention relates to the field of advanced semiconductor etching processes, and in particular to a CVD-SiC surface thermal oxidation method and system. Background Technology

[0002] Raw materials prepared by the CVD-SiC method are processed into spray heads and etching rings (focusing rings) through various methods. In the field of semiconductor etching, these products are key consumables. They are directly exposed to saturated oxygen-carrying water vapor to undergo a thermal oxidation reaction, which is used to oxidize microcracks and scratches on the surface of CVD-SiC workpieces caused by machining.

[0003] However, this method has the following limitations: First, the existing silicon carbide thermal oxidation reaction field is made entirely of quartz. During long-term use at 1200℃, quartz will precipitate alkali metal impurities such as sodium and potassium ions, which will contaminate the silicon carbide surface and result in poor interface consistency and integrity. Second, there is no active oxygen partial pressure control mechanism: it only relies on a fixed O2 flow rate and cannot dynamically match the actual oxygen carrying capacity under water vapor saturation. Third, the edge effect of large-sized workpieces has not been solved, and the uneven radiation of the quartz cavity leads to a difference of >10% in the oxidation rate between the center and the edge. Fourth, the oxidation depth control is coarse, focusing on oxide layers >2μm thick, and lacking process window optimization for precision oxidation at the 1μm level. Summary of the Invention

[0004] This invention provides a CVD-SiC surface thermal oxidation method and system to overcome the defects in the prior art that result in poor interface state consistency and integrity of CVD-SiC workpieces. It can significantly extend the particle generation time of etching rings, focusing rings, and spray head components, thereby improving the quality, stability, and PM time of advanced process etching, and significantly reducing the overall cost.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a CVD-SiC surface thermal oxidation method, comprising the following steps: The CVD-SiC workpiece is placed in the reaction chamber, which consists of a quartz base and a silicon carbide outer cover placed above the quartz base. Ultrapure water is introduced into a vaporization chamber filled with fused silica beads, and oxygen is introduced at the same time with the flow rate adjusted to obtain saturated oxygen-carrying water vapor. Saturated oxygen-carrying water vapor is introduced into the reaction chamber to cause an oxidation reaction on the surface of the CVD-SiC workpiece, resulting in a silicon dioxide layer with an oxidation depth of 0.8–1.5 μm.

[0006] Preferably, the flow rate of the ultrapure water into the vaporization chamber is 0.5–2.0 mL / min, and the temperature in the vaporization chamber is 595–605℃.

[0007] Preferably, the resistivity of the ultrapure water is ≥18.2 MΩ·cm, and the vaporization chamber is made of quartz.

[0008] Preferably, the fused silica beads are spherical with a diameter of 2.5-3.5 mm and a bulk density of 0.4-0.7 g / cm³.

[0009] Preferably, the oxygen flow rate is automatically adjusted according to the real-time water vapor molar flow rate, and the oxygen molar flow rate is 1.0–1.2 times the water vapor molar flow rate.

[0010] Preferably, the oxidation reaction is carried out at a temperature of 1150-1250°C for 10–14 h.

[0011] Preferably, during the oxidation reaction, a self-passivating SiO2 layer with a thickness ≤50nm is formed on the surface of the silicon carbide outer cover.

[0012] Preferably, after the oxidation reaction, the temperature is cooled to 700-850°C at a rate of ≤5°C / min under an Ar atmosphere, and then allowed to cool naturally.

[0013] A CVD-SiC surface thermal oxidation system includes: a reaction chamber, a vaporization chamber, a metering pump, and a dynamic gas ratio controller. The reaction chamber consists of a quartz base and a silicon carbide outer cover placed above the quartz base. The metering pump is used to introduce ultrapure water into the vaporization chamber filled with molten quartz beads. The dynamic gas ratio controller is used to introduce oxygen and adjust its flow rate to obtain saturated oxygen-carrying water vapor. The saturated oxygen-carrying water vapor is introduced into the reaction chamber to cause an oxidation reaction on the surface of the CVD-SiC workpiece, obtaining a silicon dioxide layer with an oxidation depth of 0.8–1.5 μm.

[0014] Preferably, it also includes a zoned temperature control unit, which is disposed on the silicon carbide outer cover and is used to control the temperature inside the reaction chamber.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The reaction chamber consists of a quartz base and a silicon carbide outer cover. Under controlled conditions, it achieves "self-passivation stabilization," providing superior thermal uniformity compared to all-quartz. The quartz base is resistant to droplet impact, while the silicon carbide outer cover provides uniform radiation, balancing reliability and uniformity. The oxygen flow rate is automatically adjusted based on the real-time water vapor molar flow rate in the vaporization chamber, ensuring that the oxygen molar flow rate is 1.0-1.2 times that of the water vapor molar flow rate. This yields saturated oxygen-carrying water vapor, which is then introduced into the reaction chamber, ensuring that the water vapor is always in a critical state of saturated oxygen carrying capacity. An oxidation reaction occurs on the surface of the CVD-SiC workpiece, eliminating defects such as microcracks and scratches caused by machining. This improves the interface consistency and integrity of the CVD-SiC workpiece surface, significantly extending the particle generation time of the etching ring, focusing ring, and spray head components. Consequently, it improves the quality, stability, and PM time of advanced etching processes, resulting in a significant reduction in overall cost. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a flowchart of the CVD-SiC surface thermal oxidation method provided in the embodiments of the present invention; Figure 2 This is a schematic diagram of the CVD-SiC surface before thermal oxidation, provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of the CVD-SiC surface thermal oxidation process provided in an embodiment of the present invention. Detailed Implementation

[0018] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0019] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] Please read carefully. Figures 1-3 This invention provides a CVD-SiC surface thermal oxidation method, comprising the following steps: The CVD-SiC workpiece is placed in the reaction chamber, which consists of a quartz base and a silicon carbide outer cover placed on top of the quartz base. Ultrapure water is introduced into a vaporization chamber filled with fused silica beads, and oxygen is introduced at the same time with the flow rate adjusted to obtain saturated oxygen-carrying water vapor. Saturated oxygen-carrying water vapor is introduced into the reaction chamber to cause an oxidation reaction on the surface of the CVD-SiC workpiece, resulting in a silicon dioxide layer with an oxidation depth of 0.8–1.5 μm.

[0022] Since the reaction chamber consists of a quartz base and a silicon carbide outer cover covering the quartz base, the amount of alkali metal impurities such as sodium ions and potassium ions precipitated by the quartz base is reduced compared with a reaction chamber composed entirely of quartz during the high-temperature oxidation reaction. In addition, a self-passivating SiO2 layer is formed on the surface of the silicon carbide outer cover, providing better thermal uniformity than quartz. Furthermore, the quartz base is resistant to droplet impact, and the silicon carbide outer cover provides uniform radiation, thus balancing reliability and uniformity. The oxygen flow rate is automatically adjusted based on the real-time water vapor molar flow rate in the vaporization chamber, and is kept 1.0-1.2 times the water vapor molar flow rate to obtain saturated oxygen-carrying water vapor, which is then introduced into the reaction chamber. This ensures that the water vapor is always in a critical state of saturated oxygen carrying capacity. An oxidation reaction occurs on the surface of the CVD-SiC workpiece, resulting in a silicon dioxide layer with an oxidation depth of 0.8–1.5 μm. This eliminates defects such as microcracks and scratches caused by machining, thereby improving the interface consistency and integrity of the CVD-SiC workpiece surface. It also significantly extends the particle generation time of the etching ring, focusing ring, and spray head components, thereby improving the quality, stability, and PM time of advanced etching processes, and significantly reducing overall costs.

[0023] In a preferred embodiment, the flow rate of ultrapure water into the vaporization chamber is 0.5–2.0 mL / min, and the temperature inside the vaporization chamber is 595–605°C. The method of this application requires real-time adjustment of the ratio of water vapor to oxygen. The water vapor content is difficult to measure. Therefore, the water vapor content is controlled by adjusting the flow rate of ultrapure water. The high temperature condition is to ensure that the ultrapure water entering the vaporization chamber can be vaporized into water vapor instantly.

[0024] As a preferred embodiment, the resistivity of the ultrapure water is ≥18.2 MΩ·cm, and the vaporization chamber is made of quartz. The main purpose is to achieve deionization and depolarization. The resistivity of ultrapure water reaching this value means that there are almost no ionic impurities in the water, preventing harmful ions and metal impurities from entering the oxide layer and interface.

[0025] As a preferred embodiment, the oxygen flow rate is automatically adjusted according to the real-time water vapor molar flow rate, and the oxygen molar flow rate is 1.0–1.2 times the water vapor molar flow rate; the ratio of oxygen to water vapor and the time of thermal oxidation reaction are precisely controlled, so that the silicon carbide outer cover can work stably and provide better thermal uniformity.

[0026] The CVD-SiC surface thermal oxidation method provided by the present invention will be described in detail below with reference to specific embodiments.

[0027] Example 1

[0028] The CVD-SiC workpiece is placed in the reaction chamber, which consists of a quartz base and a silicon carbide outer cover placed on top of the quartz base. Ultrapure water was introduced into a vaporization chamber filled with fused silica beads with a diameter of 2.5 mm and a bulk density of 0.4 g / cm³. The flow rate of the ultrapure water was 0.5 mL / min, and the temperature in the vaporization chamber was 595 °C. At the same time, oxygen was introduced and its flow rate was adjusted to obtain saturated oxygen-carrying water vapor. The molar flow rate of oxygen was 1.0 times that of water vapor. Saturated oxygen-carrying water vapor is introduced into the reaction chamber to cause an oxidation reaction on the surface of the CVD-SiC workpiece. The oxidation reaction temperature is 1150℃ and the reaction time is 10h, resulting in a silicon dioxide layer with an oxidation depth of 0.8μm. After the oxidation reaction, the mixture was cooled to 700°C at a rate of 3°C / min under an Ar atmosphere, and then allowed to cool naturally to room temperature.

[0029] Example 2

[0030] The CVD-SiC workpiece is placed in the reaction chamber, which consists of a quartz base and a silicon carbide outer cover placed on top of the quartz base. Ultrapure water was introduced into a vaporization chamber filled with fused silica beads with a diameter of 3 mm and a bulk density of 0.55 g / cm³. The flow rate of the ultrapure water was 0.5 mL / min, and the temperature in the vaporization chamber was 595 °C. At the same time, oxygen was introduced and its flow rate was adjusted to obtain saturated oxygen-carrying water vapor. The molar flow rate of oxygen was 1.0 times that of water vapor. Saturated oxygen-carrying water vapor is introduced into the reaction chamber to cause an oxidation reaction on the surface of the CVD-SiC workpiece. The oxidation reaction temperature is 1150℃ and the reaction time is 10h, resulting in a silicon dioxide layer with an oxidation depth of 0.8μm. After the oxidation reaction, the mixture was cooled to 700°C at a rate of 3°C / min under an Ar atmosphere, and then allowed to cool naturally to room temperature.

[0031] Example 3

[0032] The CVD-SiC workpiece is placed in the reaction chamber, which consists of a quartz base and a silicon carbide outer cover placed on top of the quartz base. Ultrapure water was introduced into a vaporization chamber filled with fused silica beads with a diameter of 3.5 mm and a bulk density of 0.7 g / cm³. The flow rate of the ultrapure water was 0.5 mL / min, and the temperature in the vaporization chamber was 595 °C. At the same time, oxygen was introduced and its flow rate was adjusted to obtain saturated oxygen-carrying water vapor. The molar flow rate of oxygen was 1.0 times that of water vapor. Saturated oxygen-carrying water vapor is introduced into the reaction chamber to cause an oxidation reaction on the surface of the CVD-SiC workpiece. The oxidation reaction temperature is 1150℃ and the reaction time is 10h, resulting in a silicon dioxide layer with an oxidation depth of 0.8μm. After the oxidation reaction, the mixture was cooled to 700°C at a rate of 3°C / min under an Ar atmosphere, and then allowed to cool naturally to room temperature.

[0033] Example 4

[0034] The CVD-SiC workpiece is placed in the reaction chamber, which consists of a quartz base and a silicon carbide outer cover placed on top of the quartz base. Ultrapure water was introduced into a vaporization chamber filled with fused silica beads with a diameter of 2.5 mm and a bulk density of 0.4 g / cm³. The flow rate of the ultrapure water was 1.25 mL / min, and the temperature in the vaporization chamber was 600 °C. At the same time, oxygen was introduced and its flow rate was adjusted to obtain saturated oxygen-carrying water vapor, and the molar flow rate of oxygen was 1.1 times that of water vapor. Saturated oxygen-carrying water vapor is introduced into the reaction chamber to cause an oxidation reaction on the surface of the CVD-SiC workpiece. The oxidation reaction temperature is 1150℃ and the reaction time is 10h, resulting in a silicon dioxide layer with an oxidation depth of 1.2μm. After the oxidation reaction, the mixture was cooled to 700°C at a rate of 3°C / min under an Ar atmosphere, and then allowed to cool naturally to room temperature.

[0035] Example 5

[0036] The CVD-SiC workpiece is placed in the reaction chamber, which consists of a quartz base and a silicon carbide outer cover placed on top of the quartz base. Ultrapure water was introduced into a vaporization chamber filled with fused silica beads with a diameter of 2.5 mm and a bulk density of 0.4 g / cm³. The flow rate of the ultrapure water was 2.0 mL / min, and the temperature in the vaporization chamber was 605 °C. At the same time, oxygen was introduced and its flow rate was adjusted to obtain saturated oxygen-carrying water vapor, and the molar flow rate of oxygen was 1.2 times that of water vapor. Saturated oxygen-carrying water vapor is introduced into the reaction chamber to cause an oxidation reaction on the surface of the CVD-SiC workpiece. The oxidation reaction temperature is 1150℃ and the reaction time is 10h, resulting in a silicon dioxide layer with an oxidation depth of 1.4μm. After the oxidation reaction, the mixture was cooled to 700°C at a rate of 3°C / min under an Ar atmosphere, and then allowed to cool naturally to room temperature.

[0037] Example 6

[0038] The CVD-SiC workpiece is placed in the reaction chamber, which consists of a quartz base and a silicon carbide outer cover placed on top of the quartz base. Ultrapure water was introduced into a vaporization chamber filled with fused silica beads with a diameter of 2.5 mm and a bulk density of 0.4 g / cm³. The flow rate of the ultrapure water was 0.5 mL / min, and the temperature in the vaporization chamber was 595 °C. At the same time, oxygen was introduced and its flow rate was adjusted to obtain saturated oxygen-carrying water vapor. The molar flow rate of oxygen was 1.0 times that of water vapor. Saturated oxygen-carrying water vapor is introduced into the reaction chamber to cause an oxidation reaction on the surface of the CVD-SiC workpiece. The oxidation reaction temperature is 1200℃ and the reaction time is 12h, resulting in a silicon dioxide layer with an oxidation depth of 1.45μm. After the oxidation reaction, the mixture was cooled to 700°C at a rate of 3°C / min under an Ar atmosphere, and then allowed to cool naturally to room temperature.

[0039] Example 7

[0040] The CVD-SiC workpiece is placed in the reaction chamber, which consists of a quartz base and a silicon carbide outer cover placed on top of the quartz base. Ultrapure water was introduced into a vaporization chamber filled with fused silica beads with a diameter of 2.5 mm and a bulk density of 0.4 g / cm³. The flow rate of the ultrapure water was 0.5 mL / min, and the temperature in the vaporization chamber was 595 °C. At the same time, oxygen was introduced and its flow rate was adjusted to obtain saturated oxygen-carrying water vapor. The molar flow rate of oxygen was 1.0 times that of water vapor. Saturated oxygen-carrying water vapor is introduced into the reaction chamber to cause an oxidation reaction on the surface of the CVD-SiC workpiece. The oxidation reaction temperature is 1250℃ and the reaction time is 14h, resulting in a silicon dioxide layer with an oxidation depth of 1.5μm. After the oxidation reaction, the mixture was cooled to 700°C at a rate of 3°C / min under an Ar atmosphere, and then allowed to cool naturally to room temperature.

[0041] Example 8

[0042] The CVD-SiC workpiece is placed in the reaction chamber, which consists of a quartz base and a silicon carbide outer cover placed on top of the quartz base. Ultrapure water was introduced into a vaporization chamber filled with fused silica beads with a diameter of 2.5 mm and a bulk density of 0.4 g / cm³. The flow rate of the ultrapure water was 0.5 mL / min, and the temperature in the vaporization chamber was 595 °C. At the same time, oxygen was introduced and its flow rate was adjusted to obtain saturated oxygen-carrying water vapor. The molar flow rate of oxygen was 1.0 times that of water vapor. Saturated oxygen-carrying water vapor is introduced into the reaction chamber to cause an oxidation reaction on the surface of the CVD-SiC workpiece. The oxidation reaction temperature is 1150℃ and the reaction time is 10h, resulting in a silicon dioxide layer with an oxidation depth of 0.8μm. After the oxidation reaction, the mixture was cooled to 775°C at a rate of 4°C / min under an Ar atmosphere, and then allowed to cool naturally to room temperature.

[0043] Example 9

[0044] The CVD-SiC workpiece is placed in the reaction chamber, which consists of a quartz base and a silicon carbide outer cover placed on top of the quartz base. Ultrapure water was introduced into a vaporization chamber filled with fused silica beads with a diameter of 2.5 mm and a bulk density of 0.4 g / cm³. The flow rate of the ultrapure water was 0.5 mL / min, and the temperature in the vaporization chamber was 595 °C. At the same time, oxygen was introduced and its flow rate was adjusted to obtain saturated oxygen-carrying water vapor. The molar flow rate of oxygen was 1.0 times that of water vapor. Saturated oxygen-carrying water vapor is introduced into the reaction chamber to cause an oxidation reaction on the surface of the CVD-SiC workpiece. The oxidation reaction temperature is 1150℃ and the reaction time is 10h, resulting in a silicon dioxide layer with an oxidation depth of 0.8μm. After the oxidation reaction, the mixture was cooled to 850°C at a rate of 5°C / min under an Ar atmosphere, and then allowed to cool naturally to room temperature.

[0045]

[0046] Table 1 As shown in Table 1, the CVD-SiC surface thermal oxidation method provided in this application, after measurement, can obtain a silica layer with an oxidation depth of 0.8–1.5 μm, and can oxidize microcracks and scratches on the CVD-SiC surface. Examples 1-3 sequentially changed the diameter and packing density of fused silica beads to study their effects on the silica layer thickness and microcracks and scratches on the CVD-SiC surface. Examples 1, 4, and 5 sequentially increased the flow rate of ultrapure water, the temperature in the vaporization chamber, and the ratio of oxygen molar flow rate to water vapor molar flow rate, resulting in a sequential increase in silica layer thickness and a decrease in microcracks and scratches on the CVD-SiC surface. Examples 1, 6, and 7 sequentially increased the oxidation reaction temperature and reaction time, resulting in a sequential increase in silica layer thickness and a decrease in microcracks and scratches on the CVD-SiC surface. Examples 1, 8, and 9 sequentially increased the cooling temperature per minute to study its effects on the silica layer thickness and microcracks and scratches on the CVD-SiC surface.

[0047] Comparative Example 1 The CVD-SiC workpiece is placed in the reaction chamber, which is composed of only high-purity quartz. Ultrapure water was introduced into a vaporization chamber filled with quartz wool. The saturated water vapor generation temperature was 90℃. The total flow rate of the fixed humid oxygen gas was 0.5L / min, and saturated oxygen-carrying water vapor was obtained. Saturated oxygen-carrying water vapor is introduced into the reaction chamber to cause an oxidation reaction on the surface of the CVD-SiC workpiece. The oxidation reaction temperature is 1200℃ and the reaction time is 12h, resulting in a silicon dioxide layer with an oxidation depth of 2.1μm. After the oxidation reaction, the mixture is cooled to a predetermined temperature at a predetermined rate under a cooling atmosphere, and then naturally cooled to room temperature.

[0048] Comparative Example 2 The CVD-SiC workpiece is placed in the reaction chamber, which is composed of only high-purity quartz. Ultrapure water was introduced into a vaporization chamber filled with quartz wool. The saturated water vapor generation temperature was 90℃. The total flow rate of the fixed humid oxygen gas was 2.5L / min, and saturated oxygen-carrying water vapor was obtained. Saturated oxygen-carrying water vapor is introduced into the reaction chamber to cause an oxidation reaction on the surface of the CVD-SiC workpiece. The oxidation reaction temperature is 1200℃ and the reaction time is 12h, resulting in a silicon dioxide layer with an oxidation depth of 2.2μm. After the oxidation reaction, the mixture is cooled to a predetermined temperature at a predetermined rate under a cooling atmosphere, and then naturally cooled to room temperature.

[0049] Comparative Example 3 The CVD-SiC workpiece is placed in the reaction chamber, which is composed of only high-purity quartz. Ultrapure water was introduced into a vaporization chamber filled with quartz wool. The saturated water vapor generation temperature was 90℃. The total flow rate of the fixed humid oxygen gas was 5.0 L / min, and saturated oxygen-carrying water vapor was obtained. Saturated oxygen-carrying water vapor is introduced into the reaction chamber to cause an oxidation reaction on the surface of the CVD-SiC workpiece. The oxidation reaction temperature is 1200℃ and the reaction time is 12h, resulting in a silicon dioxide layer with an oxidation depth of 2.5μm. After the oxidation reaction, the mixture is cooled to a predetermined temperature at a predetermined rate under a cooling atmosphere, and then naturally cooled to room temperature.

[0050]

[0051] Table 2 As shown in Table 2, when the total flow rate of humidified oxygen gas is increased sequentially in Comparative Examples 1-3, the thickness of the silica layer increases sequentially, and the thickness of the silica layer is >2μm.

[0052] The embodiments in this application differ from the comparative examples in four key aspects: First, the reaction chamber in the embodiments consists of a quartz base and a silicon carbide outer cover placed above the quartz base, while the reaction chamber in the comparative examples consists only of high-purity quartz. Second, in the embodiments, the oxygen flow rate is adjusted so that the molar flow rate of oxygen is 1.0-1.2 times that of water vapor, while in the comparative examples, the total flow rate of humidified oxygen gas is fixed. Third, in the embodiments, the silicon carbide outer cover provides uniform radiation, while in the comparative examples, the radiation is uneven in the all-quartz chamber. Fourth, the silica layer depth in the embodiments is 0.8–1.5 μm, while in the comparative examples, the silica layer depth is >2 μm. Comparing Example 6 with Comparative Examples 1-3, under the conditions of an oxidation reaction temperature of 1200℃ and a reaction time of 12 h, using different thermal oxidation methods, the silica layer thickness generated in Example 6 is 1.45 μm, while the silica layer thickness generated in Comparative Examples 1-3 is >2 μm. The oxide layer generated in Example 6 is more refined. Please read carefully. Figure 2 and Figure 3 It can be seen that microcracks and scratches on the surface of CVD-SiC workpieces are at least partially oxidized, thereby improving the consistency and integrity of the interface state on the surface of CVD-SiC workpieces, significantly extending the time for particle generation in etching rings, focusing rings, and spray head components, thereby improving the quality, stability, and PM time of advanced process etching, and significantly reducing the overall cost.

[0053] This invention also provides a CVD-SiC surface thermal oxidation system, including a reaction chamber, a vaporization chamber, a metering pump, a zoned temperature control unit, and a dynamic gas ratio controller. The reaction chamber consists of a quartz base and a silicon carbide outer cover placed above the quartz base. High-purity silicon carbide is used as the thermal field component of the oxidation furnace. During the oxidation reaction, a self-passivating SiO2 layer with a thickness ≤50nm is formed on the surface of the silicon carbide outer cover, providing better thermal uniformity than quartz. Self-passivation refers to the phenomenon that metal automatically forms a passivation film due to the reduction reaction of the oxidant in the corrosive medium under conditions without external polarization. The zoned temperature control unit is located on the silicon carbide outer cover and is used to control the temperature inside the reaction chamber. A metering pump is used to introduce ultrapure water into the vaporization chamber filled with fused silica beads. A dynamic gas ratio controller is used to introduce oxygen and adjust its flow rate to obtain saturated oxygen-carrying water vapor, ensuring that the water vapor is always in the critical state of saturated oxygen carrying. The saturated oxygen-carrying water vapor is introduced into the reaction chamber to cause an oxidation reaction on the surface of the CVD-SiC workpiece, resulting in a silicon dioxide layer with an oxidation depth of 0.8–1.5 μm.

[0054] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for thermal oxidation of a CVD-SiC surface, characterized by, Includes the following steps: The CVD-SiC workpiece is placed in the reaction chamber, which consists of a quartz base and a silicon carbide outer cover placed above the quartz base. Ultrapure water is introduced into a vaporization chamber filled with fused silica beads, and oxygen is introduced at the same time with the flow rate adjusted to obtain saturated oxygen-carrying water vapor. Saturated oxygen-carrying water vapor is introduced into the reaction chamber to cause an oxidation reaction on the surface of the CVD-SiC workpiece, resulting in a silicon dioxide layer with an oxidation depth of 0.8–1.5 μm.

2. The CVD-SiC surface thermal oxidation method according to claim 1, characterized by, The flow rate of ultrapure water into the vaporization chamber is 0.5–2.0 mL / min, and the temperature inside the vaporization chamber is 595–605℃.

3. The CVD-SiC surface thermal oxidation method according to claim 1, characterized in that, The resistivity of the ultrapure water is ≥18.2 MΩ·cm, and the vaporization chamber is made of quartz.

4. The CVD-SiC surface thermal oxidation method according to claim 1, characterized in that, The fused silica beads are spherical with a diameter of 2.5-3.5 mm and a bulk density of 0.4-0.7 g / cm³.

5. The CVD-SiC surface thermal oxidation method according to claim 1, characterized in that, The oxygen flow rate is automatically adjusted based on the real-time water vapor molar flow rate, and the oxygen molar flow rate is set to 1.0–1.2 times the water vapor molar flow rate.

6. The CVD-SiC surface thermal oxidation method according to claim 1, characterized in that, The oxidation reaction is carried out at a temperature of 1150-1250℃ for a time of 10–14 h.

7. The CVD-SiC surface thermal oxidation method according to claim 1, characterized in that, During the oxidation reaction, a self-passivated SiO2 layer with a thickness ≤50nm is formed on the surface of the silicon carbide outer cover.

8. The CVD-SiC surface thermal oxidation method according to claim 1, characterized in that, After the oxidation reaction, the mixture is cooled to 700-850°C at a rate of ≤5°C / min under an Ar atmosphere, and then allowed to cool naturally.

9. A CVD-SiC surface thermal oxidation system, characterized in that, include: The system includes a reaction chamber, a vaporization chamber, a metering pump, and a dynamic gas ratio controller. The reaction chamber consists of a quartz base and a silicon carbide outer cover. The metering pump is used to introduce ultrapure water into the vaporization chamber filled with molten quartz beads. The dynamic gas ratio controller is used to introduce oxygen and adjust its flow rate to obtain saturated oxygen-carrying water vapor. The saturated oxygen-carrying water vapor is introduced into the reaction chamber to cause an oxidation reaction on the surface of the CVD-SiC workpiece, resulting in a silicon dioxide layer with an oxidation depth of 0.8–1.5 μm.

10. The CVD-SiC surface thermal oxidation system according to claim 9, characterized in that, It also includes a zoned temperature control unit, which is mounted on the silicon carbide outer casing and is used to control the temperature inside the reaction chamber.

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