Epitaxial process
By forming gas reflux between the transmission chamber and the process chamber and using a pump, the problem of particulate matter accumulation in the silicon carbide epitaxial furnace is solved, and the high yield production of the epitaxial sheet is achieved.
Patent Information
- Application Number
- CN202510548480.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-28
- Publication Date
- 2025-08-15
AI Technical Summary
In a single-chip horizontal silicon carbide epitaxial furnace, gas reflux in the transmission chamber and process chamber causes particulate matter to accumulate on the substrate, forming drop defects and triangular defects, affecting product yields.
By passing the first gas into the transmission chamber and the second gas into the process chamber, it forms a return flow, bringing up the exhaust particles generated in the previous process, and blowing them into the exhaust port, reducing particulate matter falling on the surface of the substrate, using a pump to extract excess gas, adjusting the position of the substrate in the chamber to reduce particulate matter contamination.
It effectively reduces the number of drop defects and triangular defects on the epitaxial sheet and improves the yield of the epitaxial sheet.
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Figure CN120485945A_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the field of semiconductor technology, and in particular to an epitaxial process. Background Art
[0002] The chambers of a single-wafer horizontal SiC epitaxial growth furnace are divided into a vacuum lock chamber, a transfer chamber, and a process chamber. Each chamber has its own specific function and role, working together to complete the wafer transfer and production process. The vacuum lock chamber is primarily used for manual wafer placement. The transfer chamber is the core area for wafer transfer. It houses a four-axis, three-coordinate robotic arm for precise wafer control and movement. The chamber also features an argon purge port to remove particles or contaminants that may adhere to the wafer during wafer transfer. The robotic arm removes the substrate from the vacuum lock chamber, passes through the transfer chamber, and accurately places it into the process chamber. After the process is completed, the robotic arm removes the epitaxial wafer from the process chamber and returns it to the vacuum lock chamber. The process chamber is the primary area for the High-Temperature Metal Organic Chemical Vapor Deposition (HT-MO-CVD) process, where a specific chemical reaction grows an epitaxial thin film on the wafer. The chamber also features a hydrogen purge port.
[0003] The transfer chamber and process chamber share a common exhaust port located at the junction of the two. During the exhaust process, the gases inside the two chambers flow in opposite directions, causing gas backflow at the junction. During the epitaxial growth process, a large number of particles accumulate at the junction. These particles are blown away by the backflow of gas. Just as the robotic arm is delivering the substrate into the process chamber, the particles land on the substrate, causing a large number of drop defects and triangular defects after the epitaxial growth process, impacting product yield. Summary of the Invention
[0004] The present application provides an epitaxial growth process for reducing the number of drop defects and triangle defects on epitaxial wafers and increasing the yield of epitaxial wafers.
[0005] To achieve the above objectives, an embodiment of the present application provides an epitaxial growth process, including providing an epitaxial growth furnace, wherein the epitaxial growth furnace includes a transfer chamber, a process chamber, a first valve, and an exhaust port. The transfer chamber is connected to the process chamber via the first valve, and the exhaust port is connected to the transfer chamber and the process chamber. The exhaust port is opened to transfer a substrate into the transfer chamber. A first gas is introduced into the transfer chamber, a second gas is introduced into the process chamber, and the first valve is opened. The introduction of the second gas into the process chamber is stopped, and the substrate is transferred from the transfer chamber to the process chamber.
[0006] In some embodiments, the epitaxial furnace further includes an exhaust pump disposed at the exhaust port, and the exhaust pump is turned on during the process of opening the exhaust port. In some embodiments, the epitaxial furnace further includes a vacuum lock chamber and a second valve, and the vacuum lock chamber is connected to the transfer chamber through the second valve. The second valve is disposed on a side of the transfer chamber away from the first valve. Transferring the substrate into the transfer chamber includes opening the second valve and transferring the substrate from the vacuum lock chamber to the transfer chamber. In the transfer chamber, the substrate is closer to the second valve than to the first valve. In some embodiments, the first valve is opened when the pressure difference between the transfer chamber and the process chamber is less than or equal to 30 mbar.
[0007] In some embodiments, transferring the substrate from the transfer chamber to the process chamber includes transferring the substrate within the transfer chamber so that the substrate is closer to the first valve than the second valve, and transferring the substrate from the transfer chamber to the process chamber via the first valve.
[0008] In some embodiments, transferring the substrate within the transfer chamber includes flipping the substrate 180 degrees to transfer the substrate from a position close to the second valve to a position close to the first valve.
[0009] In some embodiments, after the substrate is transferred from the transfer chamber to the process chamber, the epitaxial process further includes introducing a second gas into the process chamber and closing the first valve to form an epitaxial layer on the substrate.
[0010] In some embodiments, the material of the substrate includes silicon carbide, and the material of the epitaxial layer includes silicon carbide.
[0011] In some embodiments, the first gas is an inert gas and the second gas is a reducing gas.
[0012] In some embodiments, the first gas is argon and the second gas is hydrogen.
[0013] In an embodiment of the present application, the exhaust port is opened, the substrate is transferred to the transfer chamber, the first gas is introduced into the transfer chamber, the second gas is introduced into the process chamber, and the first valve is opened. The first gas and the second gas form a backflow, which carries away the tail gas particles generated in the previous process. In this case, the second gas is stopped from being introduced into the process chamber, and the first gas blows the particles brought up by the backflow into the exhaust port. After a period of time, there are no particles near the first valve. Thereafter, the substrate is transferred from the transfer chamber to the process chamber. This can reduce the number of particles brought up by the backflow and falling on the substrate surface, reduce the number of drop defects and triangle defects on subsequent epitaxial wafers, and increase the yield of epitaxial wafers. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:
[0015] Figure 1 A flow chart of an epitaxial process provided in an embodiment of the present application;
[0016] Figures 2 to 6 A diagram of the steps of an epitaxial process provided in an embodiment of the present application. DETAILED DESCRIPTION
[0017] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present application. Obviously, the embodiments described are only some embodiments of the present application, not all embodiments. Based on the embodiments provided in this application, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of this application.
[0018] Unless the context requires otherwise, throughout the specification and claims, the term "comprising" is to be construed in an open, inclusive sense, that is, meaning "including, but not limited to."
[0019] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of this application, unless otherwise specified, "plurality" means two or more.
[0020] When describing some embodiments, the word "connected" and its derivatives may be used. The term "connected" should be understood broadly. For example, "connected" can mean fixed connection, detachable connection, or integration; it can be directly connected or indirectly connected through an intermediate medium. For example, when describing some embodiments, the term "connected" may be used to indicate that two or more components are in direct physical or electrical contact with each other.
[0021] Additionally, the use of “based on” is meant to be open and inclusive, as a process, step, calculation, or other action “based on” one or more stated conditions or values may, in practice, be based on additional conditions or values beyond those stated.
[0022] It will be understood that when a layer or element is referred to as being on another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may be present therebetween.
[0023] Example embodiments are described herein with reference to cross-sectional illustrations that are idealized example drawings. In the drawings, the thickness of layers and the area of regions are exaggerated for clarity. Therefore, variations in shape relative to the drawings due to, for example, manufacturing techniques and / or tolerances are contemplated. Therefore, the example embodiments should not be construed as limited to the shapes of the regions shown herein, but rather include deviations in shape due to, for example, manufacturing. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to illustrate the actual shape of regions of the device and are not intended to limit the scope of the example embodiments.
[0024] Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application.
[0025] A single-wafer horizontal SiC epitaxial furnace is an essential piece of equipment for growing epitaxial layers on semiconductor materials, playing a key role in the production of high-temperature semiconductor materials such as SiC (silicon carbide). The chamber structure of a single-wafer horizontal SiC epitaxial furnace consists of a vacuum lock chamber, a transfer chamber, and a process chamber. Each chamber has a specific function and role, working together to complete the substrate transfer and production process. The vacuum lock chamber is primarily used for manually placing SiC substrates. This chamber is typically connected to the external environment, but requires evacuation or filling with inert gas before operation to protect the substrates from contamination. Within this chamber, workers place SiC substrates on specialized trays for subsequent transfer and processing. The transfer chamber is the core area for substrate transfer. It houses a four-axis, three-coordinate robotic arm for precise control and movement of wafers. It also features an argon purge port to remove particles or contaminants that may adhere to the wafers during substrate transfer. The robotic arm removes substrates from the vacuum lock chamber and, after passing through the transfer chamber, accurately places them into the process chamber. After the process is complete, the robotic arm removes the epitaxial wafer from the process chamber and returns it to the vacuum lock chamber for subsequent processing or testing. The process chamber is the main area where the HT-MO-CVD process is carried out. A layer of epitaxial film is grown on the SiC wafer through a specific chemical reaction. The chamber is also equipped with a hydrogen purge port.
[0026] The transfer chamber and process chamber share a common exhaust port located at the junction of the two. Argon gas in the transfer chamber and hydrogen gas in the process chamber flow in opposite directions, creating a gas backflow at the exhaust port. During the epitaxial growth process, a large number of particles accumulate at the exhaust port. These particles are blown up by the backflow of gas. Just as the robotic arm is delivering the substrate wafer into the process chamber, the particles land on the wafer, leading to numerous surface morphological defects such as drop defects and triangle defects after the epitaxial growth process.
[0027] In order to solve the above problems, the present invention provides an epitaxial process. Figure 1 Flowchart of the epitaxial process provided in the embodiment of the present application; Figures 2 to 6 A diagram of the various steps of the epitaxial process provided in an embodiment of the present application.
[0028] See also Figure 1 The epitaxial process includes the following steps S10 to S50:
[0029] S10: See Figure 2 , an epitaxial furnace 10 is provided, which includes a transmission chamber 102, a process chamber 103, a first valve 105 and an exhaust port 106. The transmission chamber 102 is connected to the process chamber 103 through the first valve 105, and the exhaust port 106 is connected to the transmission chamber 102 and the process chamber 103.
[0030] S20: See Figure 2 , open the exhaust port 106 and transfer the substrate 2 into the transfer chamber 102 .
[0031] Illustratively, the transfer chamber 102 has a built-in four-axis three-coordinate robotic arm, through which the substrate 2 can be transferred into the transfer chamber 102 .
[0032] S30: See Figure 2 , the first gas is introduced into the transmission chamber 102 , the second gas is introduced into the process chamber 103 , and the first valve 105 is opened.
[0033] For example, the first gas can be an inert gas, and the second gas can be a reducing gas. The inert gas can prevent oxidation and other chemical contamination of the material during high-temperature processing, maintaining a stable, oxygen-free environment within process chamber 103 and facilitating precise control of process conditions. By adjusting the flow rate and concentration of the reducing gas, the reducing atmosphere within process chamber 103 can be precisely controlled, thereby influencing the microstructure and properties of the epitaxial layer.
[0034] For example, the first gas is argon and the second gas is hydrogen. Argon is an inert gas with stable chemical properties that does not readily react with other substances. During epitaxial growth, argon provides an inert protective atmosphere, preventing oxidation of the substrate 2. Hydrogen can be used as one of the reaction gases during the epitaxial growth process, contributing to the formation of the desired epitaxial layer.
[0035] Illustratively, the first gas is argon, and an argon purge port is further provided in the transmission cavity 102 , through which argon is introduced into the transmission cavity 102 .
[0036] S40: See Figure 3 , stop introducing the second gas into the process chamber 103.
[0037] S50: See Figure 4 and Figure 5 , transferring the substrate 2 from the transfer chamber 102 to the process chamber 103 .
[0038] In the embodiment of the present application, the exhaust port is opened, the substrate 2 is transferred to the transfer chamber 102, the first gas is introduced into the transfer chamber 102, the second gas is introduced into the process chamber 103, and the first valve 105 is opened. The first gas and the second gas form a backflow, carrying away the exhaust particles generated in the previous process. In this case, the second gas is stopped from being introduced into the process chamber 103, and the first gas blows the particles carried away by the backflow into the exhaust port 106. After a period of time, there are no particles near the first valve 105. Thereafter, the substrate 2 is transferred from the transfer chamber 102 to the process chamber 103. This can reduce the number of particles carried away by the backflow and fall on the surface of the substrate 2, reduce the number of drop defects and triangle defects on subsequent epitaxial wafers, and increase the yield of the epitaxial wafers.
[0039] In some embodiments, as Figure 3 As shown, the epitaxial furnace 10 further includes an exhaust pump 107 disposed at the exhaust port 106 . In the above step S20 , the exhaust pump 107 is turned on during the process of opening the exhaust port 106 .
[0040] It is understandable that after the second gas is stopped from entering the process chamber 103, the process chamber 103 lacks the second gas to maintain the gas pressure, and the first gas entering the transfer chamber 102 is likely to bring a small amount of particulate matter into the process chamber 103. The gas is pumped out of the exhaust port 106 by the air pump 107, which facilitates the discharge of particulate matter, reduces the phenomenon of particulate matter entering the process chamber 103, and prevents particulate matter from contaminating the process chamber 103, thereby ensuring the normal operation of the process chamber 103.
[0041] In some embodiments, as Figure 2 As shown, the epitaxial furnace 10 further includes a vacuum lock chamber 101 and a second valve 104 , wherein the vacuum lock chamber 101 is connected to the transmission chamber 102 via the second valve 104 . The second valve 104 is disposed on a side of the transmission chamber 102 away from the first valve 105 .
[0042] Based on this, the above step S20: transferring the substrate 2 into the transfer chamber 102 includes the following steps S201:
[0043] S201 : Open the second valve 104 to transfer the substrate 2 from the vacuum lock chamber 101 to the transfer chamber 102 . In the transfer chamber 102 , the substrate 2 is closer to the second valve 104 than to the first valve 105 .
[0044] Exemplarily, the substrate 2 is transferred from the vacuum lock chamber 101 to the transfer chamber 102 by a robot arm in the transfer chamber 102 .
[0045] The vacuum lock chamber 101 is a high vacuum or ultra-low vacuum environment. A tray is provided in the vacuum lock chamber 101 for placing the substrate 2, providing a clean space for the substrate 2. The presence of the vacuum lock chamber 101 helps reduce the impact of external contaminants on the substrate 2, thereby improving the purity of the epitaxial layer.
[0046] As previously described, due to the pressure balance between transfer chamber 102 and process chamber 103, gas backflow occurs near first valve 105, which can carry away particles. Within transfer chamber 102, by placing substrate 2 closer to second valve 104 relative to first valve 105, there are fewer particles near second valve 104 than near first valve 105, thus reducing the number of particles that land on the surface of substrate 2.
[0047] In some embodiments, see Figure 2 In the above step S30, the first gas is introduced into the transmission chamber 102 while the second valve 104 is closed. By means of pressure relief and ventilation, the pressure in the transmission chamber 102 can be adjusted to a predetermined level.
[0048] In some embodiments, see Figure 2 In the above step S30, the first gas is introduced into the transmission chamber 102 and the second gas is introduced into the process chamber 103 until the pressure difference between the transmission chamber 102 and the process chamber 103 is less than or equal to 30 mbar, so that the pressure of the transmission chamber 102 and the process chamber 103 is balanced, which facilitates opening the first valve 105. The first valve 105 is a one-way sealed valve.
[0049] In some embodiments, see Figure 4 and Figure 5 The above step S50: transferring the substrate 2 from the transfer chamber 102 to the process chamber 103 includes the following steps S501-S502:
[0050] S501: See Figure 4 , the substrate 2 is transferred in the transfer chamber 102 so that the substrate 2 is closer to the first valve 105 than to the second valve 104 .
[0051] For example, in the transfer chamber 102 , the robotic arm drives the substrate 2 to rotate 180°, transferring the substrate 2 from a position close to the second valve 104 to a position close to the first valve 105 . At the same time, the robotic arm can shake off dust on the substrate 2 while driving the substrate 2 to rotate 180°.
[0052] S502: See Figure 5 , the substrate 2 is transferred from the transfer chamber 102 to the process chamber 103 through the first valve 105 .
[0053] Exemplarily, the substrate 2 is transferred from the transfer chamber 102 to the process chamber 103 by a robot arm in the transfer chamber 102 .
[0054] In some embodiments, see Figure 6 After the substrate 2 is transferred from the transfer chamber 102 to the process chamber 103 in step S50 , the epitaxial process further includes the following steps S60 - S61 :
[0055] S60 : introducing the second gas into the process chamber 103 and closing the first valve 105 .
[0056] S61: forming an epitaxial layer on the substrate 2. After the second gas is introduced, the first valve 105 is closed to prevent external gas from interfering with the atmosphere in the process chamber 193.
[0057] The composition and flow rate of the second gas are adjusted based on the desired epitaxial layer type and characteristics. For example, if the substrate 2 material includes silicon carbide, the epitaxial layer material also includes silicon carbide, and the second gas can be hydrogen, which serves as a reducing gas. Silicon carbide substrates are based on silicon carbide crystals and have high thermal conductivity and high temperature resistance, forming the foundation for the fabrication of silicon carbide devices. Epitaxial growth techniques enable the creation of a new, defect-free silicon carbide layer on the substrate, significantly improving material quality.
[0058] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that a person skilled in the art can conceive within the technical scope disclosed in this application should be included within the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.
Claims
1. An epitaxial process, characterized in that: include: An epitaxial furnace is provided, the epitaxial furnace comprising a transmission chamber, a process chamber, a first valve, and an exhaust port, the transmission chamber being connected to the process chamber via the first valve, and the exhaust port being connected to the transmission chamber and the process chamber; Opening the exhaust port and transferring the substrate into the transfer chamber; Introducing a first gas into the transmission chamber, introducing a second gas into the process chamber, and opening the first valve; stopping the introduction of the second gas into the process chamber; The substrate is transferred from the transfer chamber to the process chamber.
2. The epitaxial process according to claim 1, characterized in that: The epitaxial furnace further includes an exhaust pump disposed at the exhaust port; During the process of opening the exhaust port, the air pump is turned on.
3. The epitaxial process according to claim 1, characterized in that: The epitaxial furnace further includes a vacuum lock chamber and a second valve, wherein the vacuum lock chamber is connected to the transmission chamber through the second valve; the second valve is arranged on a side of the transmission chamber away from the first valve; Transferring the substrate into the transfer chamber comprises: Opening the second valve to transfer the substrate from the vacuum lock chamber to the transfer chamber; Wherein, in the transmission chamber, the substrate is closer to the second valve than to the first valve.
4. The epitaxial process according to claim 1, characterized in that: When the pressure difference between the transmission chamber and the process chamber is less than or equal to 30 mbar, the first valve is opened.
5. The epitaxial process according to claim 3, characterized in that: Transferring the substrate from the transfer chamber to the process chamber comprises: transferring the substrate within the transfer chamber so that the substrate is closer to the first valve than to the second valve; The substrate is transferred from the transfer chamber to the process chamber via the first valve.
6. The epitaxial process according to claim 5, characterized in that: Transferring the substrate within the transfer cavity comprises: The substrate is turned over 180 degrees, and the substrate is transferred from a position close to the second valve to a position close to the first valve.
7. The epitaxial process according to claim 1, characterized in that: After transferring the substrate from the transfer chamber to the process chamber, the epitaxial process further includes: introducing the second gas into the process chamber and closing the first valve; An epitaxial layer is formed on the substrate.
8. The epitaxial process according to claim 7, characterized in that: The material of the substrate includes silicon carbide, and the material of the epitaxial layer includes silicon carbide.
9. The epitaxial process according to claim 1, characterized in that: The first gas is an inert gas, and the second gas is a reducing gas.
10. The epitaxial process according to claim 9, characterized in that: The first gas is argon, and the second gas is hydrogen.