A plasma-assisted oxidation device with stable airflow

Abstract

The present invention discloses a plasma-assisted oxidation device with a stable gas flow, which includes a plasma processing chamber, a conveying device for conveying gas through the interior of the plasma processing chamber, and a carrier plate located on the conveying device for carrying a substrate. A gas introduction system, a cathode plate, and a vacuum system are sequentially arranged above the conveying device in the plasma processing chamber along the conveying direction. An anode plate opposite to the cathode plate is formed below the conveying device in the plasma processing chamber. The cathode plate is electrically connected to a high-frequency power supply through a wire. The gas introduction system cooperates with the vacuum system to form an airflow field with an arc-shaped trajectory in the space above the conveying device. The anode plate cooperates with the cathode plate to form an electric field from bottom to top in the space between the two. The present invention solves the problem of disturbance of the electric field and the flow field caused by the parallel transmission of the substrate, thereby improving the overall uniformity of the oxidized film.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor manufacturing, and in particular relates to a plasma-assisted oxidation device with a stable gas flow. Background Art

[0002] Since the 1960s and 1970s, due to the development and production needs of semiconductor and integrated circuit technology, chemical vapor deposition technology CVD has been rapidly and widely developed. At present, in the manufacture of silicon-based semiconductor devices, PECVD technology has great application potential in the field of thin film preparation due to its low-temperature preparation, high deposition rate and good step coverage.

[0003] The core device in the PECVD equipment is the plasma processing device, which usually has a pair of cathode electrodes and anode electrodes and a gas supply device for supplying the reaction gas used to generate plasma. The PECVD technology based on the glow discharge method can ionize the reaction gas to form plasma under the stimulation of the external electromagnetic field. The presence of plasma can decompose or ionize the oxygen-containing reaction gas and diffuse it to the surface of the substrate being processed, causing the substrate surface to oxidize.

[0004] In PECVD technology, during high-power deposition, unstable gas pressure can cause abnormal discharge of the power supply electrode, resulting in increased non-uniformity of the film on the surface of the processed substrate. The reaction gas is usually supplied between the cathode electrode and the anode electrode using a shower plate set on the surface of the cathode electrode to achieve uniform diffusion of the gas in the entire plasma generation space. In the process of preparing oxide films on the PECVD production line, considering the expansion of the area of ​​the processed substrate and the beat problem, the transmission mode of the substrate is changed from traditional rotation to parallel transmission.

[0005] Patent publication number CN206774570U in the prior art discloses a solar cell coating device and a solar cell chain production device, which adopts a continuous conveying device to realize automatic horizontal conveying of the substrate, and then passes through a preheating chamber, an oxidation chamber and a coating chamber in sequence; wherein in the oxidation chamber, a plasma generator is arranged near the input side and below the conveying device, and a guide plate is arranged above the plasma generator, and the guide plate is used to blow air obliquely downward and backward, and cooperate with the negative pressure of the vacuum port located below the conveying device on the output side of the oxidation chamber to form an airflow field, and the airflow field is located inside the oxidation chamber, and there is no specific pipeline to limit the direction of the airflow field, and the position of the vacuum exhaust port is arranged at the oxygen chamber. At the bottom of the output side of the oxidation chamber, when the vacuum pumping port is evacuated, the gas in the oxidation chamber will rush in from all directions of the vacuum pumping port, including the space below the conveying device. Therefore, the gas blown out by the guide plate will form two airflows, one of which flows through the space between the conveying device and the heating device above, and the other flows through the space below the conveying device. The reaction gas flowing through the space above the conveying device is effective, and the gas flowing through the space below the conveying device is wasted; in the above structure, there is no electric field in the oxidation reaction section corresponding to the conveying device and the heating device. The reaction gas is first ionized into plasma, and then diffused to the section where the substrate is located under the action of the airflow field to oxidize the substrate surface. In this mode, the ion concentration of the plasma continues to decrease as it reacts with the substrate during its movement, and the airflow is difficult to disperse evenly, resulting in uneven oxidation reaction.

[0006] Parallel transmission of substrates can cause many problems, including changes in electric field strength during substrate transmission and disturbances to reactive gases and plasma caused by parallel transmission. These problems can further increase the surface non-uniformity of the processed substrates, leading to a decrease in the performance of the final semiconductor device.

[0007] Therefore, it is urgent to further improve the existing plasma reaction chamber structure to solve the disturbance problem of the electric field and flow field caused by the parallel transmission of the substrate. Summary of the invention

[0008] The main purpose of the present invention is to provide a plasma-assisted oxidation device with a stable airflow, so as to solve the disturbance problem of the electric field and the flow field caused by the parallel transmission of the substrate, thereby improving the overall uniformity of the oxidized film.

[0009] The present invention achieves the above-mentioned purpose through the following technical scheme: a plasma-assisted oxidation device with stable airflow, which includes a plasma processing chamber, a conveying device for conveying and passing through the interior of the plasma processing chamber, and a carrier plate located on the conveying device for carrying a substrate, wherein a gas introduction system, a cathode plate and a vacuum system are sequentially arranged above the conveying device in the plasma processing chamber along the conveying direction, an anode plate is formed below the conveying device in the plasma processing chamber and is opposite to the cathode plate in the upper and lower directions, the cathode plate is electrically connected to a high-frequency power supply through a wire, the gas introduction system cooperates with the vacuum system to form an airflow field with an arc-shaped trajectory in the space above the conveying device, and the anode plate and the cathode plate cooperate to form an electric field from bottom to top in the space between the two.

[0010] Furthermore, the exhaust speed of the vacuum pumping system is consistent with the intake flow rate of the gas introduction system.

[0011] Furthermore, the conveying device is in a continuous conveying state during the process of depositing the oxide film on the surface of the substrate.

[0012] Furthermore, a heating component is arranged in the carrier plate.

[0013] Furthermore, the gas introduction system includes a gas introduction plate located beside the cathode plate, a gas source connected to the gas introduction plate, and an MFC controller arranged on a pipeline connecting the gas source and the gas introduction plate.

[0014] Furthermore, the gas inlet plate includes a top plate, a panel, a baffle plate connecting the top plate and the panel and surrounding the panel to form a hollow cavity, and a baffle plate that separates the hollow cavity into a first cavity and a second cavity. An air inlet is provided in the middle of the top plate, a plurality of air uniforming ports are provided on the baffle plate, and a plurality of air outlets are provided in an array on the panel.

[0015] Furthermore, the uniform air vents are strip-shaped groove structures and are arranged in parallel and spaced apart from the center of the baffle plate to the left and right sides or to the front and rear sides; the flow cross-sectional area of ​​the uniform air vents gradually increases from the center of the baffle plate to the outside.

[0016] Furthermore, the uniform air vent is a strip-shaped groove structure with a uniform length, and the length direction of the uniform air vent is arranged to be consistent with or perpendicular to the conveying direction of the conveying device.

[0017] Furthermore, the vacuum pumping system includes a vacuum plate located next to the cathode plate, a vacuum pump connected to the vacuum plate, a front-stage pump connected to the vacuum pump, a front-stage valve and a pressure controller arranged on the pipeline connecting the vacuum pump and the front-stage pump; a plurality of vacuum adsorption holes are arranged on the lower surface of the vacuum plate.

[0018] Furthermore, the gas introduction system and the vacuum system are arranged on the left and right sides of the cathode plate; and the lower surfaces of the gas introduction plate, the cathode plate and the vacuum plate are flush and adjacent to each other.

[0019] The plasma-assisted oxidation device with stable airflow of the present invention serves as the core device of large-scale PECVD coating equipment of a large production line. It can stabilize the airflow and electric field during the large-area coating process, and utilizes plasma to oxidize the surface of the processed substrate on the carrier plate, thereby forming a large-area uniform oxide film.

[0020] Compared with the prior art, the plasma-assisted oxidation device with a stable airflow of the present invention has the beneficial effect of effectively solving the disturbance problem of the electric field and the flow field caused by the parallel transmission of the substrate, thereby improving the overall uniformity of the oxidized film. Specifically:

[0021] (1) The gas flow field in the plasma reaction chamber is stable. In the plasma reaction chamber of the present invention, the gas introduction system for intake and the vacuum pumping system for exhaust are respectively placed on both sides of the cathode plate electrode. Under low vacuum, in order to ensure the stability of the vacuum, the intake gas velocity and the exhaust gas velocity are basically consistent. The reaction gas introduced by the gas introduction plate in the gas introduction system passes through the plasma reaction zone (i.e., the space area between the cathode plate and the anode plate) and can be stably discharged by the vacuum pumping system, thereby forming a stable flow field; in addition, the size and strength of the flow field can be controlled by the MFC controller and the pressure controller; because the parallel movement direction of the carrier plate is basically consistent with the direction of the flow field, the disturbance of the carrier plate movement to the flow field is minimized to the greatest extent, thereby creating a stable environment for oxidation, and finally forming a uniform oxide film on the surface of the processed substrate of the carrier plate;

[0022] (2) The electric field in the plasma reaction chamber is stable. Traditional PECVD often uses the carrier as the anode electrode. On the production line PECVD equipment, if the parallel moving carrier is set as the anode electrode, the electric field strength will change with the movement of the carrier, thereby affecting the effect of film growth. The present invention grounds the chamber to ensure the stability of the electric field strength, which does not change with the movement of the carrier, thus avoiding the uneven oxidation of the surface of the processed substrate caused by the change of the electric field strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the main structure of an embodiment of the present invention;

[0024] Figure 2 It is a structural schematic diagram showing the direction of flow field and electric field in an embodiment of the present invention;

[0025] Figure 3 Schematic diagram of the cross-sectional structure of the gas introduction plate in an embodiment of the present invention;

[0026] Figure 4 Schematic diagram of the top view of the gas introduction plate in an embodiment of the present invention;

[0027] The numbers in the figure represent:

[0028] 100- plasma assisted oxidation device with stable gas flow; 200- substrate;

[0029] 1-plasma treatment chamber; 2-conveying device; 3-carrier plate; 4-gas introduction system, 41-gas introduction plate, 411-top plate, 412-panel, 413-enclosing plate, 414-first chamber, 415-second chamber, 416-baffle, 417-air inlet, 418-gas uniformity port, 419-gas outlet, 4110-gas uniformity slot, 42-gas source, 43-MFC controller; 5-cathode plate; 6-vacuum extraction system, 61-vacuum plate, 62-vacuum pump, 63-fore stage pump, 64-fore stage valve, 65-pressure controller; 7-anode plate; 8-high frequency power supply; 9-heating component. DETAILED DESCRIPTION Example

[0030] Please refer to Figure 1-Figure 4 The present embodiment is a plasma-assisted oxidation device 100 with a stable gas flow, which includes a plasma processing chamber 1, a conveying device 2 for conveying gas from left to right through the plasma processing chamber 1, and a carrier plate 3 located on the conveying device 2. A gas introduction system 4 for blowing in reaction gas, a cathode plate 5 and a vacuum system 6 are sequentially arranged above the conveying device 2 in the plasma processing chamber 1 along the conveying direction. An anode plate 7 is formed below the conveying device 2 in the plasma processing chamber 1. The cathode plate 5 is electrically connected to a high-frequency power supply 8 through a wire. An input port is formed on the left side of the plasma processing chamber 1 and an output port is formed on the right side, and gate valves (not shown in the figure) are arranged at both the input port and the output port.

[0031] The vacuum system 6 forms a low vacuum environment in the plasma processing chamber 1 by vacuuming, and cooperates with the gas introduction system 4 to form an arc-shaped trajectory airflow field from left to right in the space between the cathode plate 5 and the conveying device 2; the high-frequency power supply 8 applies high-frequency power to the cathode plate 5 to generate glow discharge, and cooperates with the anode plate 7 to form an electric field from bottom to top, so that the reaction gas introduced into the low vacuum environment plasma processing chamber 1 by the gas introduction system 4 generates plasma, wherein oxygen ions are deposited on the surface of the substrate 200 placed on the carrier 3 under the action of the electric field and the airflow field.

[0032] The exhaust speed of the vacuum system 6 is consistent with the intake flow rate of the gas introduction system 4, so that the airflow field speed in the plasma processing chamber 1 is stable, the reaction gas forms a stable arc-shaped airflow, and only flows through the space above the conveying device 2, which is consistent with the conveying direction of the conveying device 2. Therefore, when the conveying device 2 conveys the substrate 200 for horizontal movement, the disturbance to the airflow field is very small and can basically be ignored. In addition, since the positions of the two electrodes, the anode plate 7 and the cathode plate 5, are relatively fixed, the size and direction of the electric field will not be disturbed as the substrate 200 moves. Therefore, the uniformity of the oxide film generated on the substrate 200 is greatly improved.

[0033] This embodiment is described by taking the preparation of a silicon oxide film as an example, wherein the substrate 200 is a silicon substrate, and oxygen ions are deposited on the surface of the silicon substrate to form a silicon oxide film.

[0034] In this embodiment, the conveying device 2 is in a continuous conveying state during the process of depositing an oxide film on the substrate surface to improve the rhythm of the overall streamline, while meeting the conveying requirements of large-area substrates and meeting the requirements of assembly-line production processes.

[0035] A heating component 9 is provided in the carrier 3, and the heating component 9 can heat the carrier 3 to 800°C or above. The process temperature of preparing the silicon oxide film is generally controlled at 200-400°C.

[0036] The gas introduction system 4 and the vacuum system 6 are arranged on the left and right sides of the cathode plate 5. The gas introduction system 4 includes a gas introduction plate 41 located beside the cathode plate 5, a gas source 42 connected to the gas introduction plate 41, and an MFC controller 43 (the MFC controller 43 is a gas mass flow controller) arranged on a pipeline connecting the gas source 42 and the gas introduction plate 41. In order to improve the uniformity and stability of the reaction gas entering the plasma processing chamber 1, and further improve the uniformity and stability of the gas flow field, the structure of the gas introduction plate 41 is improved in this embodiment. Specifically, the gas introduction plate 41 includes a top plate 411, a panel 412, a baffle plate 413 connecting the top plate 411 and the panel 412 and surrounding the hollow cavity together, and a baffle plate 416 that divides the hollow cavity into a first cavity 414 and a second cavity 415. An air inlet 417 is provided in the middle of the top plate 411, a plurality of uniform gas ports 418 are provided on the baffle plate 416, and a plurality of air outlet holes 419 are arranged in an array on the panel 412. The MFC controller 43 controls the air flow rate of the reaction gas entering the gas introduction plate 41. In this embodiment, the gas source 42 is one of NO and O2.

[0037] In order to ensure the uniformity of the air pressure blown out on the panel 412, it is prevented that the air near the air inlet 417 that enters the hollow cavity is directly blown out from the air outlet 419 in a certain area below the air inlet 417, resulting in a faster air flow speed in this area, causing the problem of air pressure fluctuation. In order to solve this technical problem, on the one hand, the present embodiment sets a baffle plate 416, and on the other hand, improves the structure of the air uniformity vent 418 on the baffle plate 416. Specifically, the air uniformity vent 418 is a strip groove structure and is arranged in parallel and spaced from the center of the baffle plate 416 to the left and right sides or to the front and rear sides. The flow cross-sectional area of ​​the air uniformity vent 418 gradually increases from the center of the baffle plate 416 to the outside, that is, the flow cross-sectional area of ​​the air uniformity vent 418 close to the center of the baffle plate 416 is the smallest, and the farther away from the baffle plate 416, the larger the flow cross-sectional area of ​​the air uniformity vent 418. In this embodiment, the middle gas uniformity vent 418 is a strip groove structure, and the gas uniformity vents 418 on both sides are configured so that every two strip groove structures form a group to form a gas uniformity vent 4110, and each group of gas uniformity vents 4110 is arranged at equal intervals. The width of the gas uniformity vents 418 in all gas uniformity vents 4110 gradually increases from the center of the baffle plate 416 to the outside. The design that the flow cross-sectional area of ​​the gas uniformity vents 418 gradually increases from the center of the baffle plate 416 to the outside can effectively solve the problem that the gas outlet velocity of the gas outlet 419 near the gas inlet 417 and the gas outlet velocity of the gas outlet 419 far from the gas inlet 417 are large, thereby causing the problem of pressure fluctuation in the plasma processing chamber 1; in addition, through the design of the baffle plate 416, the gas entering through the gas inlet 417 is divided into two stages for uniform treatment to ensure that it can eventually flow out from the entire panel area of ​​the panel 412 at a nearly identical flow rate and flow rate and enter the plasma processing chamber 1.

[0038] The air-uniform opening 418 is a strip-shaped groove structure with a uniform length, and the length direction of the air-uniform opening 418 is consistent with the conveying direction of the conveying device 2 or is arranged perpendicularly.

[0039] The vacuum pumping system 6 includes a vacuum plate 61 located beside the cathode plate 5, a vacuum pump 62 connected to the vacuum plate 61, a front stage pump 63 connected to the vacuum pump 62, a front stage valve 64 arranged on the pipeline connecting the vacuum pump 62 and the front stage pump 63, and a pressure controller 65. A plurality of vacuum adsorption holes are arranged on the lower surface of the vacuum plate 61. The pressure controller 65 is electrically connected to the vacuum pump 62. The vacuum pumping system 6 also includes a vacuum gauge for monitoring the vacuum degree in the plasma processing chamber 1. The pressure controller 65 is electrically connected to the vacuum gauge, and the vacuum degree is obtained in real time through the vacuum gauge, thereby controlling the working power of the vacuum pump 62, so that the vacuum degree in the plasma processing chamber 1 meets the process setting conditions.

[0040] In this embodiment, the vacuum degree in the plasma processing chamber 1 is 10 2 ~10 -1Pa.

[0041] In this embodiment, the lower surfaces of the gas inlet plate 41, the cathode plate 5 and the vacuum plate 61 are flush and adjacent to each other, so that the lower surfaces of the three together form a seamless plate surface, ensuring the stability of the airflow field and the flow in the set flow path.

[0042] In this embodiment, the bottom of the plasma processing chamber 1 is grounded to form an anode plate 7. In other embodiments, a separate anode plate may also be provided. The anode plate 7 and the cathode plate 5 are arranged opposite to each other up and down to ensure the stability of the electric field. The power density of the RF bias voltage is 0.015~5W / cm 2 .

[0043] The working process of this embodiment is as follows: start the vacuum pump 62 and the front stage pump 63, control the vacuum degree of the plasma processing chamber 1 to be in a low vacuum state (10 2 ~10 -1 Pa); start the heating component 9 in the carrier 3 to stabilize the temperature of the carrier 3 at 200~400℃; start the high-frequency power supply 8 and the gas introduction system 4, and the reaction gas is decomposed into electrons, ions and active groups under the action of the electric field excited by the high-frequency power supply 8; the power density of the RF bias is 0.015~5W / cm 2 ; Since the gas introduction system 4 and the vacuum system 6 are distributed on the left and right sides of the cathode plate 5 electrode, the lower part of the plasma processing chamber 1 is grounded as the anode electrode, the electric field is stable, and the reaction gas forms a ring airflow, which is consistent with the parallel transmission direction of the carrier plate 3. Under the action of the electric field and the gas flow field, the oxygen ions quickly migrate to the surface of the processed substrate, so that the surface of the parallel-transmitted substrate is effectively oxidized, and finally a uniform solid oxide film is formed on the surface of the processed substrate with uniform parallel transmission; during the film growth process, various reaction by-products gradually detach from the surface of the film or the plasma reaction zone, and are discharged from the exhaust pipe under the action of the vacuum system 6.

[0044] In the plasma-assisted oxidation device with stable airflow of the present embodiment, the electric field and the flow field are stable, and oxygen ions quickly migrate to the surface of the processed substrate under the action of the electric field and the flow field, so that the surface of the parallel-driven substrate is effectively oxidized, and finally a uniform solid silicon oxide film is formed on the surface of the silicon wafer driven in parallel at a uniform speed, and the thickness of the silicon oxide film is 0.8~1.6nm.

[0045] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A plasma-assisted oxidation device with a stable airflow, characterized in that: It includes a plasma processing chamber, a conveying device for conveying through the inside of the plasma processing chamber, and a carrier plate located on the conveying device for carrying a substrate. A gas introduction system, a cathode plate and a vacuum system are sequentially arranged above the conveying device in the plasma processing chamber along the conveying direction. An anode plate opposite to the cathode plate is formed below the conveying device in the plasma processing chamber. The cathode plate is electrically connected to a high-frequency power supply through a wire. The gas introduction system cooperates with the vacuum system to form an airflow field with an arc trajectory in the space above the conveying device. The anode plate and the cathode plate cooperate to form an electric field from bottom to top in the space between the two.

2. The plasma-assisted oxidation device with a stable gas flow as claimed in claim 1, characterized in that: The exhaust speed of the vacuum pumping system is consistent with the intake flow rate of the gas introduction system.

3. The plasma-assisted oxidation device with stable airflow as claimed in claim 1, characterized in that: The conveying device is in a continuous conveying state during the process of depositing an oxide film on the substrate surface.

4. The plasma-assisted oxidation device with a stable gas flow as claimed in claim 1, characterized in that: A heating component is arranged in the carrier plate.

5. The plasma-assisted oxidation device with stable airflow according to any one of claims 1 to 4, characterized in that: The gas introduction system comprises a gas introduction plate located beside the cathode plate, a gas source connected to the gas introduction plate, and an MFC controller arranged on a pipeline connecting the gas source and the gas introduction plate.

6. The plasma-assisted oxidation device with a stable gas flow as claimed in claim 5, characterized in that: The gas inlet plate includes a top plate, a panel, a baffle plate connecting the top plate and the panel and surrounding the panel to form a hollow cavity, and a baffle plate that divides the hollow cavity into a first cavity and a second cavity. An air inlet is provided in the middle of the top plate, a plurality of air uniforming ports are provided on the baffle plate, and a plurality of air outlets are provided in an array on the panel.

7. The plasma-assisted oxidation device with a stable gas flow as claimed in claim 6, characterized in that: The uniform air vents are strip-shaped groove structures and are arranged in parallel and spaced apart from the center of the baffle plate to the left and right sides or to the front and rear sides; the flow cross-sectional area of ​​the uniform air vents gradually increases from the center of the baffle plate to the outside.

8. The plasma-assisted oxidation device with a stable gas flow as claimed in claim 7, characterized in that: The uniform air vent is a strip-shaped groove structure with a consistent length, and the length direction of the uniform air vent is arranged consistent with or perpendicular to the conveying direction of the conveying device.

9. The plasma-assisted oxidation device with a stable gas flow as claimed in claim 5, characterized in that: The vacuum pumping system includes a vacuum plate located next to the cathode plate, a vacuum pump connected to the vacuum plate, a front-stage pump connected to the vacuum pump, a front-stage valve arranged on the pipeline connecting the vacuum pump and the front-stage pump, and a pressure controller; a plurality of vacuum adsorption holes are arranged on the lower surface of the vacuum plate.

10. The plasma-assisted oxidation device with a stable gas flow as claimed in claim 9, characterized in that: The gas introduction system and the vacuum system are arranged on the left and right sides of the cathode plate; and the lower surfaces of the gas introduction plate, the cathode plate and the vacuum plate are flush and adjacently arranged.

Images