PEALD cavity structure

Abstract

The utility model provides a PEALD cavity structure, and relates to the technical field of coating equipment. The structure comprises an outer cavity, an inner cavity, a lifting system, a heating platform deck, an air exhaust system and a pressure controller. The inner cavity is arranged in the outer cavity, an opening matched with the heating carrying table is formed in the bottom of the inner cavity, and the lifting system controls connection and separation of the heating carrying table and the inner cavity. And the inner cavity is internally provided with the separator to form a conical reaction space, so that plasma distribution is improved. And the annular exhaust hole uniformly exhausts redundant gas, so that the film thickness uniformity is improved. A pressure controller is arranged in the outer cavity to maintain fixed pressure difference between the inner cavity and the outer cavity and prevent diffusion of process gas. According to the design, the independence of the reaction area is realized, the utilization rate of the precursor is improved, the maintenance process is simplified, and the cleanliness of the cavity is enhanced.

Description

Technical Field

[0001] This utility model relates to the field of coating equipment technology, and more specifically, to a PEALD cavity structure and a method for controlling gas uniformity. Background Technology

[0002] Plasma-enhanced atomic layer deposition (PEALD) is a high-precision thin film fabrication technology that combines the self-limited reaction of atomic layer deposition (ALD) with plasma-assisted excitation. It deposits atomically uniform thin films layer by layer on a substrate surface by periodically alternating the introduction of precursors and plasma-activated reactive gases, and is widely used in semiconductors, optical coatings, and new energy devices. A typical traditional PEALD device usually includes the following core modules: Reaction chamber: a vacuum-sealed chamber with a built-in substrate tray to hold the substrate to be deposited; Substrate heating system: maintains the substrate temperature (typically 50-400℃) through resistance heating or radiation heating; Precursor delivery system: includes a gaseous / liquid precursor source, a mass flow controller (MFC), and a pulse injection valve to achieve precise timing control of the precursor; Plasma source: generates plasma using radio frequency (RF) or microwave excitation, common types include capacitively coupled plasma (CCP) or inductively coupled plasma (ICP); Vacuum system: maintains a high vacuum (10⁻⁶) in the chamber using a multi-stage pumping device including mechanical pumps and molecular pumps. -3 -10 -6 Torr); Control system: integrated PLC or industrial computer to regulate temperature, pressure, gas pulse timing and plasma parameters; Exhaust gas treatment system: treats unreacted precursors and byproducts through a scrubber or cold trap.

[0003] However, traditional PEALD devices have the following problems:

[0004] 1. Typically, a single reaction chamber structure is used. During deposition, in addition to the wafer being coated, all surfaces inside the chamber are coated. Therefore, the contamination area is large during coating, which can easily increase the number of wafer particles. Furthermore, the process chamber is inconvenient to maintain. When maintaining the equipment, all coated surfaces need to be removed, which is a very cumbersome process. There are many maintenance parts, and cleaning and replacement of parts are time-consuming.

[0005] 2. Insufficient plasma uniformity: Traditional CCP / ICP sources are easily constrained by cavity geometry, resulting in large differences in plasma density between the edge and the center, and uneven gas flow distribution, leading to poor film thickness uniformity.

[0006] 3. The large volume of the inner cavity results in a large amount of precursor adsorbed on the inner surface during the process, leading to low precursor utilization.

[0007] 4. The vacuum level inside the cavity is low and the impurity content of the membrane layer is high. Utility Model Content

[0008] This invention addresses the problems of large coating contamination areas, insufficient plasma uniformity, low precursor utilization, and low vacuum levels in existing PEALD equipment by proposing an improved technical solution. This solution significantly improves process performance and equipment maintenance efficiency through a unique internal and external cavity design, annular evacuation port layout, and the introduction of a pressure controller.

[0009] The present invention adopts the following solution:

[0010] A PEALD cavity structure includes a plasma source, a pumping system, and further includes an outer cavity, an inner cavity, a lifting system, and a heating stage. The plasma source is connected to the inner cavity to supply plasma to it. The inner cavity is disposed inside the outer cavity and is adapted to cooperate with the heating stage to form a reaction cavity. The pumping system includes a first negative pressure device and a second negative pressure device, the first negative pressure device being connected to the inner cavity and the second negative pressure device being connected to the outer cavity. The heating stage is disposed within the outer cavity, and the lifting system is connected to the heating stage to control its lifting and lowering.

[0011] Furthermore, a partition is provided inside the inner cavity, with the upper and lower ends of the partition connected to the output port of the plasma source and the heating stage, respectively, to divide the inner cavity into a reaction cavity and a non-reaction region. An exhaust channel is provided between the reaction cavity and the non-reaction region, and the first negative pressure device is connected to the non-reaction region.

[0012] Furthermore, the separator forms a conical reaction space within the reaction cavity, and the opening of the conical reaction space gradually increases along the direction of plasma propagation, so that the plasma is uniformly distributed on the surface of the heating stage.

[0013] Furthermore, multiple vent holes are arranged in a ring at the connection between the reaction cavity and the non-reaction area to form the vent channel.

[0014] Furthermore, the outer cavity is provided with a pressure controller suitable for controlling the entry of inert gas. The pressure controller is configured to automatically adjust the intake flow rate according to a preset value so as to form a stable pressure difference between the inner and outer cavities, and the pressure of the outer cavity is greater than the pressure of the inner cavity, so as to prevent the process gas in the inner cavity from diffusing outward to the outer cavity.

[0015] Furthermore, the heating stage is provided with an edge protrusion on its periphery, and the inner surface of the edge protrusion is connected to the inner cavity through a metal surface contact.

[0016] Furthermore, the inner cavity is detachably disposed on the outer cavity.

[0017] Furthermore, the outer cavity is provided with an upper cavity cover, the inner cavity is detachably disposed on the upper cavity cover, and the upper cavity cover is provided with an exhaust hole to communicate with the inner cavity.

[0018] Furthermore, the first negative pressure device is a dry pump, and the second negative pressure device is a molecular pump.

[0019] Beneficial effects:

[0020] This invention simplifies the maintenance process. The inner cavity can be disassembled separately, requiring only sandblasting maintenance; the outer cavity requires no maintenance, significantly reducing maintenance components and time. It improves film thickness uniformity; the annular evacuation port layout achieves laminar gas flow, improving the uniformity of plasma and reactant gases, thereby enhancing film thickness uniformity. It increases precursor utilization; the chemical reaction occurs only within the inner cavity, reducing the surface area for precursor adsorption, increasing precursor utilization, and lowering coating costs. It enhances cavity cleanliness; after the process, a molecular pump performs high-vacuum evacuation of the outer cavity, improving cavity cleanliness and providing a favorable environment for the next process. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of a PEALD cavity structure according to an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the inner cavity and heating stage of a PEALD cavity structure according to an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the outer cavity structure of a PEALD cavity structure according to an embodiment of this utility model;

[0024] Figure 4 This is a schematic diagram of the heating stage of a PEALD cavity structure according to an embodiment of the present invention;

[0025] Figure 5 This is a schematic diagram of the internal cavity structure of a PEALD cavity structure according to an embodiment of this utility model;

[0026] Figure 6 This is a schematic diagram of the internal cavity of a PEALD cavity structure according to an embodiment of the present invention from another perspective;

[0027] Figure 7 This is a schematic diagram of the coating process of a PEALD cavity structure according to an embodiment of the present invention.

[0028] Reference numerals: 1. First negative pressure device; 2. Plasma source; 3. Inlet; 4. Precursor inlet; 5. Inner cavity; 6. Upper cavity cover; 7. Gate valve; 8. Second negative pressure device; 9. Pressure controller; 10. Carrier plate; 11. Lifting system; 12. Heating platform; 13. Exhaust port; 14. Input port; 15. Installation port; 16. Outlet channel; 17. Edge protrusion; 18. Outlet hole; 19. Valve; 20. Outer cavity; 21. Separator; 22. Reaction cavity; 23. Non-reaction zone; 24. Inert gas input pipe. Detailed Implementation

[0029] Example 1

[0030] Combination Figures 1 to 6 As shown, this embodiment provides a PEALD cavity structure, including a plasma source 2, a pumping system, and further including: an outer cavity 20, an inner cavity 5, a lifting system 11, and a heating stage 12; wherein, the plasma source 2 is connected to the inner cavity 5 to supply plasma to the inner cavity 5; the inner cavity 5 is disposed inside the outer cavity 20, and its bottom has an opening suitable for matching the heating stage 12; the pumping system includes a first negative pressure device 1 and a second negative pressure device 8, the first negative pressure device 1 being connected to the inner cavity 5 to extract gas from the inner cavity 5; the second negative pressure device 8 being connected to the outer cavity 20 to create a vacuum environment in the outer cavity 20; the heating stage 12 is disposed inside the outer cavity 20, and is adapted to fit with the bottom opening of the inner cavity 5 to form a reaction cavity 22; the lifting system 11 is connected to the heating stage 12 to control the connection and separation of the heating stage 12 from the inner cavity 5.

[0031] Combination Figure 1 As shown, in this embodiment, the plasma source 2 generates plasma using radio frequency (RF) or microwave excitation, such as capacitively coupled plasma (CCP) or inductively coupled plasma (ICP). This embodiment uses ICP as an example. The plasma source 2 includes an inlet 3, through which process gases such as N2, O2, NH3, H2, and argon are introduced at a flow rate controlled by an MFC. After passing through the ICP, the gases dissociate to form N-containing plasma and active free radicals. A precursor inlet 4 is also provided at the output port of the plasma source 2, through which an MO source, such as TMA, can be introduced.

[0032] Combination Figures 1 to 4As shown, the outer cavity 20 and the inner cavity 5 form a manufacturing cavity; the inner cavity 5 is disposed within the outer cavity 20, and the entire process is carried out within the inner cavity 5. Specifically, the outer cavity 20 is provided with an upper cavity cover 6, which has an exhaust port 13 for connecting to the first negative pressure device 1, and an output port of the plasma source 2 for connecting to the plasma source 2. The side is provided with an installation port 15 for the second negative pressure device 8 and a connection port for the inert gas input pipe 24. The inner cavity 5 is detachably installed within the outer cavity 20, specifically, it can be installed below the upper cavity cover 6 by bolts. Sealing ring devices are provided at all connections of the outer cavity 20 to ensure that the outer cavity 20 is in a high vacuum state. In this embodiment, the first negative pressure device 1 is a dry pump, and the second negative pressure device 8 is a molecular pump. The dry pump is provided with a valve 19, and the molecular pump is provided with a gate valve 7 for controlling opening and closing.

[0033] Combination Figures 1 to 6 As shown, the inner cavity 5 is entirely enclosed within the outer cavity 20. A partition 21 is provided inside the inner cavity 5, with its upper and lower ends connected to the output port of the plasma source 2 and the heating platform 12, respectively, dividing the inner cavity 5 into a reaction cavity 22 and a non-reaction region 23. A gas outlet channel 16 is provided between the reaction cavity 22 and the non-reaction region 23, and the first negative pressure device 1 is connected within the non-reaction region 23. Specifically, the partition 21 forms a conical reaction space within the reaction cavity 22. The opening of the conical reaction space gradually increases along the direction of plasma propagation, ensuring uniform plasma distribution on the surface of the heating platform 12. The conical reaction space can be cone-shaped or funnel-shaped, allowing plasma entering from the plasma source 2 to gradually diffuse across the entire surface of the heating platform 12, resulting in uniform distribution of plasma and process gas across the entire heating platform 12 and improving reaction uniformity. The bottom of the separator 21 is provided with the gas outlet channel 16 at the connection between it and the shell. The gas outlet channel 16 is adapted to discharge the gas in the reaction chamber 22 to the non-reaction area 23.

[0034] Combination Figures 5 to 6 As shown, in a preferred embodiment, the gas outlet channel 16 is arranged in a ring with multiple gas outlet holes 18, and the multiple gas outlet holes 18 are evenly distributed around the circumference. It should be noted that the bottom of the separator 21 is open, used to cover the heating platform 12, and together with the heating platform 12, they form the reaction cavity 22. The ring-shaped arrangement of the gas outlet holes 18 allows airflow to flow in from above and be evenly discharged from the bottom of the cavity 5, which is beneficial for achieving stable laminar gas flow and improving film thickness uniformity.

[0035] Combination Figures 1 to 4As shown, the heating platform 12 is adapted to match the outer shell of the inner cavity 5. An edge protrusion 17 is provided on the periphery of the heating platform 12. The top surface of the edge protrusion 17 is connected to the outer shell of the inner cavity 5 via a metal-to-metal contact. It should be noted that this contact is not sealed with a sealing ring, but only through metal-to-metal contact. This prevents excessive gas pressure within the reaction cavity 22 from damaging the equipment and facilitates separation from the inner cavity 5. After the reaction cavity 22 is formed, the gas outlet channel 16 is located inside the edge protrusion 17, allowing gas within the reaction cavity 22 to exit from the non-reaction area 23. The heating platform 12 integrates a heating resistance wire and a thermocouple, with a heating range of RT-450℃, used to heat the carrier plate 10, which is placed inside the heating platform 12. A lifting system 11 is provided below the heating platform 12. The lifting system 11 can employ existing lifting mechanisms, such as a lifting motor. The lifting system 11 can control the heating tray 10 to move up and down. When it rises, it can cooperate with the inner cavity 5 to form a reaction cavity 22 to start the coating process. When it falls, the heating stage 12 is separated from the inner cavity 5, and the tray 10 inside the heating stage 12 can be taken out.

[0036] Combination Figure 1 As shown, a pressure controller 9 suitable for controlling the entry of inert gas is provided in the outer cavity 20. The pressure controller 9 is located on the inert gas input pipe 24 and is configured to automatically adjust the inert gas inlet flow rate of the inert gas input pipe 24 according to a preset value to form a stable pressure difference between the inner and outer cavities. The pressure in the outer cavity 20 is greater than the pressure in the inner cavity 5 to prevent process gas in the inner cavity 5 from diffusing outwards into the outer cavity 20. The pressure controller 9 can input inert gas to control the pressure in the outer cavity 20, thus maintaining a stable pressure difference between the inner and outer cavities. Throughout the process, the pressure in the outer cavity 20 is always greater than the pressure in the inner cavity 5. For example, if the pressure in the outer cavity 20 is 2 torr and the pressure in the inner cavity 5 is 0.5-0.8 torr, this prevents process gas from diffusing outwards into the outer cavity 20 and contaminating the coating. Only a small amount of inert gas permeates into the inner cavity 5, which will not negatively affect the reaction. In this embodiment, the inert gas used can be argon.

[0037] This embodiment employs a unique internal and external cavity design. During the ALD process, the chemical reaction occurs only within the internal cavity 5. The internal cavity 5 and the external cavity 20 operate relatively independently. Furthermore, since the internal cavity 5 can be disassembled separately, maintenance only requires disassembling and sandblasting the internal cavity 5; the external cavity 20 requires no maintenance. Compared to traditional open single-cavity structures, this simplifies the equipment maintenance process and reduces the number of components requiring maintenance. Simultaneously, this design reduces the surface area for adsorbing precursors, improving precursor utilization and lowering coating costs.

[0038] Example 2

[0039] Combination Figures 1 to 7 As shown, this embodiment also provides a coating process for a PEALD cavity structure, including the following steps:

[0040] S1. First, turn on the second negative pressure device 8 to evacuate the outer cavity 20. Then, the robotic arm will transfer the wafer-carrying tray 10 from the sample injection cavity into the sample preparation cavity and place it on the heating stage 12 for heating.

[0041] S2. After heating is completed, the lifting system 11 drives the heating platform 12 to rise until it contacts and presses against the inner cavity 5, so that the reaction inner cavity 22 is formed between the inner cavity 5 and the heating platform 12.

[0042] S3. Close the second negative pressure device 8 and open the first negative pressure device 1, thereby switching from the high vacuum state of the second negative pressure device 8 to the process gas state of the first negative pressure device 1.

[0043] S4. The process includes:

[0044] At the start of the process, after a given pressure setpoint, inert gas enters the outer cavity 20 through the pressure controller 9. The pressure controller 9 automatically adjusts the inlet flow rate according to the setpoint, so that the inert gas in the outer cavity 20 is always in a steady flow state. When the pressure in the outer cavity 20 reaches the set pressure, a stable pressure difference is formed between the inner cavity 5 and the outer cavity 20, and the pressure in the outer cavity 20 is always greater than the pressure in the inner cavity 5 throughout the entire process.

[0045] Process gas enters from precursor inlet 4, and gas source such as NH3 is introduced from plasma source 2 inlet 3. After ICP dissociation, plasma and active free radicals are formed. Inert gas (such as argon) is used as carrier gas and purge gas for process gas throughout the entire ALD process, so that the entire ALD cycle is carried out in reaction chamber 22. During the reaction, excess process gas, purge gas and reaction by-products are dispersed and evenly removed through outlet channel 16, and then extracted through the first negative pressure device 1.

[0046] S5. After the process is completed, the lifting system 11 descends, driving the heating platform 12 to descend and keeping it in the descending position. At this time, the inner cavity 5 and the outer cavity 20 are in a connected state. The second negative pressure device 8 is turned on and the first negative pressure device 1 is turned off. Under the suction of the second negative pressure device 8, the outer cavity 20 is in a high vacuum state, and the carrier plate 10 is taken out by the robotic arm.

[0047] The process scheme of this embodiment can reduce the surface area of ​​the adsorbed precursor, improve the utilization rate of the precursor, reduce the coating cost, and improve the coating efficiency.

[0048] It should be understood that the above are only preferred embodiments of the present utility model, and the protection scope of the present utility model is not limited to the above embodiments. All technical solutions that fall within the scope of the present utility model are protected by the present utility model.

[0049] The accompanying drawings used in the above description of the embodiments only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

Claims

1. A PEALD chamber structure comprising a plasma source, a pumping system, characterized in that, Also included are: An outer cavity, an inner cavity, a lifting system and a heating platform; wherein, The plasma source is connected to the inner cavity to supply plasma to the inner cavity; The inner cavity is arranged inside the outer cavity and is adapted to cooperate with the heating platform to form a reaction inner cavity; The pumping system includes a first negative pressure device and a second negative pressure device, the first negative pressure device is connected to the inner cavity, and the second negative pressure device is connected to the outer cavity; The heating platform is arranged in the outer cavity, and the lifting system is connected to the heating platform to control the lifting of the heating platform.

2. The PEALD chamber structure of claim 1, wherein, The inner cavity is provided with a partition body, the upper and lower ends of the partition body are respectively connected to the output port of the plasma source and the heating platform, so as to divide the inner cavity into a reaction inner cavity and a non-reaction area, an exhaust passage is arranged between the reaction inner cavity and the non-reaction area, and the first negative pressure device is connected in the non-reaction area.

3. The PEALD chamber structure of claim 2, wherein, The partition body makes the reaction inner cavity form a conical reaction space, the opening of the conical reaction space gradually increases along the advancing direction of the plasma, so that the plasma is uniformly distributed on the surface of the heating platform.

4. The PEALD chamber structure of claim 2, wherein, A plurality of exhaust holes are arranged annularly at the connection between the reaction inner cavity and the non-reaction area to form the exhaust passage.

5. The PEALD chamber structure of claim 1, wherein, The outer cavity is provided with a pressure controller adapted to control the entry of inert gas, the pressure controller is configured to automatically adjust the gas flow according to the preset value, so as to form a stable pressure difference between the inner and outer cavities, and the pressure of the outer cavity is greater than that of the inner cavity, so as to prevent the process gas in the inner cavity from diffusing to the outer cavity.

6. The PEALD chamber structure of claim 1, wherein, The heating platform is provided with an edge boss on the side, and the edge boss is connected by metal surface contact with the shell of the inner cavity.

7. The PEALD chamber structure of claim 1, wherein, The inner cavity is detachably arranged on the outer cavity.

8. The PEALD chamber structure of claim 7, wherein, The outer cavity is provided with an upper cavity cover, the inner cavity is detachably arranged on the upper cavity cover, and the upper cavity cover is provided with an exhaust hole to communicate with the inner cavity.

9. The PEALD chamber structure of claim 1, wherein, The first negative pressure device is a dry pump, and the second negative pressure device is a molecular pump.

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