Method and apparatus for removing contaminants from an etch chamber

Abstract

This invention discloses a method and apparatus for removing contaminants from an etching chamber. The method includes, in response to a contaminant removal command within the etching chamber, removing a substrate fixed to a chuck inside the etching chamber; feeding a clean wafer into the etching chamber and placing it on the chuck; pressing the clean wafer down onto the chuck and holding it for a predetermined time, allowing an adhesive functional layer to adsorb contaminants from the chuck surface; removing the contaminant-adsorbed clean wafer from the etching chamber; performing plasma purging on the interior of the etching chamber; and resetting the substrate back into the etching chamber and fixing it to the chuck to resume the etching process. The apparatus includes an etching chamber, a clean wafer, a wafer transfer arm, a plasma purging assembly, a control unit, and a sealed contaminant collection box. This invention maintains a vacuum state within the chamber throughout the cleaning process, eliminating the need for re-vacuuming after cleaning and allowing direct resumption of the etching process, thereby significantly reducing equipment downtime and improving production efficiency.

Description

Technical Field

[0001] This invention belongs to the field of wafer processing technology, specifically relating to a method and apparatus for removing contaminants from an etching cavity. Background Technology

[0002] In semiconductor dry etching processes, particulate contaminants easily deposit on the inner walls of the etching chamber and the surface of the chuck, affecting process stability. Traditional cleaning methods require opening the chamber cover for cleaning, but this disrupts the vacuum environment of the chamber. After cleaning, it is necessary to evacuate the vacuum for a long time to restore the process conditions, resulting in low production efficiency. At the same time, repeated opening of the chamber can damage the chamber seals, increasing the risk of leakage and equipment maintenance costs.

[0003] To address the drawbacks of cavity cleaning, related technologies, such as the Chinese patent application with publication number CN120878529A, disclose a semiconductor etching device and an online particulate matter cleaning method. This method utilizes a simulated wafer made of electret material, applies high voltage to charge it, and then uses electrostatic force to adsorb particulate matter inside the cavity, thereby achieving cavity cleaning without disrupting the vacuum.

[0004] However, in the above-mentioned online cleaning method based on electrostatic force, the electrostatic force is not effective in adsorbing the non-polar or weakly polar polymer byproducts that are commonly present in the cavity, resulting in incomplete cleaning. Secondly, this solution requires additional high-voltage charging and discharging modules and auxiliary processing cavities, which increases the complexity and cost of the equipment. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for removing contaminants from an etching cavity, in order to solve the problems in the prior art.

[0006] Therefore, the present invention provides a method for removing contaminants from an etching cavity, comprising: In response to a contaminant removal command within the etching chamber, the etching process is paused, and the substrate fixed on the chuck inside the etching chamber is removed from the etching chamber. A clean wafer with an adhesive functional layer is fed into the etching cavity and placed on the chuck; A downward pressure is applied to the clean wafer, pressing it down onto the chuck and holding it therefore for a predetermined time, during which the adhesive functional layer adsorbs contaminants from the surface of the chuck. The clean wafer that has adsorbed the contaminants is removed from the etching cavity and sent to the collection device; The interior of the etching cavity is purged with plasma; The substrate is reset into the etching cavity and fixed on the chuck to resume the etching process.

[0007] In one possible implementation, the clean wafer includes an inert material layer and the adhesive functional layer disposed on one side of the inert material layer.

[0008] In one possible implementation, the material of the inert layer includes silicon, silicon dioxide, or aluminum oxide.

[0009] In one possible implementation, the material of the adhesive functional layer includes photoresist or PDMS pressure-sensitive adhesive.

[0010] In one possible implementation, the plasma purging uses oxygen as the purging gas; preferably, the oxygen flow rate is 150-250 sccm, the upper electrode power is 600-1000 W, and the purging duration is 45-90 seconds.

[0011] In one possible implementation, the step of feeding the clean wafer with the adhesive functional layer into the etching cavity includes: The cleaned wafer is placed inside the sample transfer chamber; The sample transfer chamber is evacuated to the same vacuum level as the etching chamber. Open the valve between the sample transfer chamber and the etching chamber, and transfer the clean wafer from the sample transfer chamber to the etching chamber through the wafer transfer arm.

[0012] In one possible implementation, placing the clean wafer on the chuck includes: Align the center of the cleaned wafer with the center of the chuck, and ensure that the radial deviation between the cleaned wafer and the chuck is no greater than 0.01 mm.

[0013] In one possible implementation, the substrate is removed from the etching cavity and placed in a temporary storage location, the temporary storage location having the same inert gas atmosphere as the etching cavity.

[0014] In one possible implementation, the contaminant removal command is triggered based on a back helium anomaly alarm signal.

[0015] On the other hand, an etching cavity contaminant removal device is also provided, comprising: An etching cavity, wherein a chuck for supporting a substrate is provided inside the etching cavity; A clean wafer, the back side of which is coated with an adhesive functional layer; A wafer transfer arm for transferring the substrate and the clean wafer; A plasma purging assembly is used to perform plasma purging on the interior of the etching cavity; The control unit is used to control the start and stop of the wafer transfer arm, the plasma purging assembly, and the etching process; In one possible implementation, a sealed contaminant collection box is also included for storing the disposable clean wafer after use.

[0016] In one possible implementation, a sample transfer chamber is also included, with a gate valve provided between the sample transfer chamber and the etching chamber. The sample transfer chamber is used to feed in and remove the clean wafer while maintaining the vacuum of the etching chamber.

[0017] Beneficial effects: 1. This invention maintains a vacuum state in the cavity throughout the entire cleaning process. After cleaning, there is no need to re-vacuum, and the etching process can be resumed directly, significantly reducing equipment downtime and improving production efficiency. Simultaneously, this invention avoids mechanical damage to the cavity seals caused by repeated cavity opening, reducing the risk of increased cavity leakage and lowering equipment maintenance costs.

[0018] 2. This invention employs a viscous functional layer to adsorb contaminants, exhibiting excellent adsorption effects on non-polar or weakly polar polymer byproducts commonly found within the etching chamber, resulting in more thorough cleaning. This invention eliminates the need for additional high-voltage charging / discharging modules and auxiliary processing chambers; it can be implemented using only the existing wafer transport mechanism and sample transfer chamber of the etching equipment, resulting in low equipment complexity and minimal modification costs.

[0019] 3. This invention uses disposable clean wafers, which are directly placed into a sealed collection box after use and are not reused. This completely avoids the risk of cross-contamination and eliminates the need for discharging, cleaning, and recharging the simulated wafers as required by existing technologies, simplifying the cleaning process and reducing the burden on operators.

[0020] 4. This invention cleans wafers by first using an adhesive functional layer to adsorb large particles and stubborn contaminants on the chuck surface and inner wall of the cavity, followed by plasma purging to remove residual micro-contaminants. This method leverages the advantages of adhesive adsorption in capturing large particles while utilizing plasma purging to compensate for any potential omissions of nanoscale particles by adhesive adsorption, effectively improving the cleaning effect.

[0021] 5. The contaminant removal command of the present invention is automatically triggered by the back helium abnormality alarm signal. When contaminants are deposited on the chuck surface, causing abnormal substrate adsorption, the system can automatically start the cleaning process without manual judgment and intervention, realizing the automation of the cleaning process, and can deal with contamination problems in a timely manner, avoiding the expansion of process abnormalities and causing greater production capacity loss. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 The flowchart illustrates the method for removing contaminants from an etching cavity provided by this invention.

[0024] Figure 2 This is a schematic diagram of the sample transfer chamber and the etching chamber in the etching chamber contaminant removal device provided by the present invention.

[0025] Figure 3 This is a schematic diagram of the connection between the wafer transfer arm and the clean wafer in this invention.

[0026] Figure 4 This is a schematic diagram of cleaning the wafer in this invention.

[0027] In the diagram: 1. Etching cavity; 2. Cleaning wafer; 201. Inert material layer; 202. Adhesive functional layer; 3. Wafer transfer arm; 4. Sample transfer cavity; 5. Chuck. Detailed Implementation

[0028] The invention will be more readily understood by referring to the following detailed description of preferred embodiments and included examples. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In case of conflict, the definitions in this specification shall prevail.

[0029] This invention provides a method and apparatus for removing contaminants from an etching cavity. The technical concept of this invention is to use a one-time cleaning wafer with an adhesive functional layer to adsorb contaminants in the etching cavity without disrupting the vacuum environment of the cavity, and to achieve thorough cleaning by combining plasma purging. Compared with the existing technology of removing contaminants by electrostatic removal, this invention can effectively remove non-polar or weakly polar polymer byproducts.

[0030] like Figures 1-3 As shown, a method and apparatus for removing contaminants from an etching cavity include: In response to a contaminant removal command within the etching chamber, the etching process is paused, and the substrate fixed to the chuck inside the etching chamber is removed from the etching chamber. Specifically, when cleaning is required inside the etching chamber, the system issues a contaminant cleaning command. In one embodiment, this command can be manually triggered; in another embodiment, it can be automatically triggered by the equipment based on process parameters. Based on this command, the system pauses the current etching process, for example, by stopping the supply of RF power and gas. The wafer transfer arm moves above the chuck, removing the substrate originally fixed to the chuck from the etching chamber. In one embodiment, the substrate is placed in a dedicated temporary storage location.

[0031] A clean wafer with an adhesive functional layer is fed into the etching chamber and placed on the chuck. Preferably, the clean wafer is a single-use item, used only for the current cleaning cycle; a new clean wafer is used for the next cleaning cycle. Specifically, the wafer transfer arm moves to the wafer storage position and picks up a clean wafer. The back side of the clean wafer is coated with an adhesive functional layer. The wafer transfer arm feeds the clean wafer into the etching chamber and accurately places it on the empty chuck. In some embodiments, the size of the clean wafer matches the size of the chuck and the substrate, such as 6 inches, 8 inches, or 12 inches.

[0032] A downward pressure is applied to the clean wafer, pressing it onto the chuck and holding it therefore for a predetermined time. The adhesive functional layer then adsorbs contaminants from the chuck surface. Specifically, the clean wafer is pressed down at a certain speed by a wafer transfer arm, ensuring it is completely adhered to the chuck surface. The clean wafer is held on the chuck for the predetermined time. During this time, the adhesive functional layer on the back of the clean wafer comes into full contact with contaminant particles on the chuck surface and the inner wall of the cavity, utilizing its adhesiveness to adsorb the contaminants.

[0033] The clean wafer, having adsorbed the contaminants, is removed from the etching chamber and fed into a collection device. Specifically, after a predetermined holding time, the wafer transfer arm lifts the clean wafer and removes it from the etching chamber. The clean wafer with adsorbed contaminants is then placed into a sealed contaminant collection box. This clean wafer is a single-use consumable and is not reused after use.

[0034] The interior of the etching chamber is purged with plasma; specifically, the plasma purging procedure is initiated. The control unit activates the gas purging assembly, introduces a cleaning gas, such as oxygen, into the etching chamber, and applies radio frequency power to generate plasma. Plasma purging can remove residual micro-contaminants on the chuck surface and the inner wall of the chamber. In one embodiment, the micro-contaminants are nanoscale particles that the adhesive functional layer failed to fully adsorb.

[0035] Finally, the substrate is returned to the etching chamber and fixed on the chuck, resuming the etching process. Specifically, the wafer transfer arm picks up the previously removed substrate from the temporary storage position, puts it back into the etching chamber, and precisely fixes it on the chuck. Since the vacuum level and atmosphere inside the etching chamber are not disrupted during the entire cleaning process, there is no need to re-evacuate the vacuum; the RF power supply and gas supply for the etching process can be directly restored, and production can continue.

[0036] In summary, the method provided by this invention does not damage the vacuum level and atmosphere inside the etching chamber, while effectively removing contaminants inside the etching chamber. This avoids the problems of long-term vacuum recovery and damage to seals caused by traditional open-chamber cleaning, thus effectively improving production efficiency.

[0037] In this embodiment, the cleaning wafer includes an inert material layer and an adhesive functional layer disposed on one side of the inert material layer. The inert material layer is located on the front side of the cleaning wafer, i.e., the side that contacts the wafer transfer arm. The adhesive functional layer is coated on the back side of the cleaning wafer, i.e., the side that directly contacts the chuck. The function of the inert material layer is to prevent the cleaning wafer from generating particulate matter during transfer and pressing, and also to prevent the adhesive functional layer from contaminating the wafer transfer arm. The adhesive functional layer is specifically designed to adsorb contaminants.

[0038] In this embodiment, the inert material layer is made of silicon, silicon dioxide, or aluminum oxide. These are commonly used inert materials in semiconductor processes, which do not release contaminants or react with the process gases in the etching chamber. This allows the clean wafer front side to safely contact the wafer transfer arm without introducing additional sources of contamination.

[0039] In the embodiments of this application, the material of the adhesive functional layer includes photoresist or PDMS pressure-sensitive adhesive. Photoresist is a common polymer material that has a certain degree of viscosity in its uncured state and can be used to adsorb particulate matter. PDMS pressure-sensitive adhesive is a polydimethylsiloxane pressure-sensitive adhesive with moderate adhesion and can effectively adsorb pollutants.

[0040] Meanwhile, photoresist or PDMS pressure-sensitive adhesive can prevent adhesion to common materials inside the etching chamber, such as aluminum alloy, quartz, and ceramics, thus avoiding secondary damage to the chamber during wafer removal for cleaning. Furthermore, photoresist or PDMS pressure-sensitive adhesive maintains stable viscosity within the etching chamber's process temperature range, typically -20°C to 150°C, and does not produce volatile impurities, thus avoiding contamination of the chamber environment.

[0041] In this embodiment, the wafer transfer arm presses the clean wafer onto the chuck at a speed of 2 mm per second. Using a slower pressing speed avoids violent collisions between the clean wafer and the chuck, and also facilitates full contact between the adhesive functional layer and the chuck surface. The lifting speed of the clean wafer is also 2 mm per second to avoid pulling between the adhesive functional layer and the chuck, preventing adhesive layer residue or damage to the chuck.

[0042] In this embodiment, the cleaned wafer is held on the chuck for a predetermined time. In some preferred embodiments, the predetermined time can be from 30 seconds to 120 seconds, such as 30 seconds, 40 seconds, 50 seconds, 60 seconds, 70 seconds, 80 seconds, 90 seconds, 100 seconds, and 120 seconds. It is understood that the holding time can be adjusted according to the degree of contaminant accumulation in the cavity. If the contaminants are light, a shorter holding time can be set, such as 30 seconds. If the contaminants are heavy, a longer holding time can be set, such as 90 seconds or 120 seconds. The holding time should not exceed 120 seconds to avoid affecting overall production efficiency. In actual use, the control unit can automatically select the holding time according to a preset program.

[0043] In the embodiments of this application, oxygen is used as the purging gas for plasma purging. In some preferred embodiments, the oxygen flow rate is 150 to 250 standard milliliters per minute (sccm), the upper electrode power is 600 to 1000 watts, and the purging duration is 45 to 90 seconds. Oxygen plasma can effectively decompose organic pollutants into carbon dioxide and water vapor, which are then discharged from the cavity through a vacuum system. Plasma purging ensures both effective cleaning and avoids excessive bombardment damage to internal components.

[0044] In this embodiment of the application, the step of feeding a disposable clean wafer with an adhesive functional layer into the etching cavity specifically includes: The clean wafer is placed inside the sample transfer chamber. At this time, the valve of the sample transfer chamber is closed, and the sample transfer chamber is exposed to atmospheric conditions.

[0045] The sample transfer chamber is evacuated to ensure that its internal vacuum level matches that of the etching chamber. This prevents particulate matter from being blown into the etching chamber due to airflow impact caused by pressure difference when the valve is opened, and also prevents the vacuum level and atmosphere within the etching chamber from being disrupted.

[0046] The valve between the sample transfer chamber and the etching chamber is opened, and the clean wafer is transferred from the sample transfer chamber to the etching chamber via the wafer transfer arm and placed on the chuck. Thanks to the buffering effect of the sample transfer chamber, the etching chamber remains under vacuum throughout the process, preventing exposure to the atmosphere. This avoids frequent vacuuming within the etching chamber, which would affect production efficiency, and also effectively reduces the risk of damage to the seals within the etching chamber caused by frequent vacuuming.

[0047] In this embodiment, when placing the cleaning wafer on the chuck, the center of the cleaning wafer must be aligned with the center of the chuck, and the radial deviation between the cleaning wafer and the chuck must not exceed 0.01 mm. This high-precision alignment ensures that the cleaning wafer completely covers the chuck surface, allowing the adhesive functional layer to fully contact the contaminants on the chuck. Excessive deviation prevents contaminants at the chuck edges from being adsorbed, thus affecting the cleaning effect.

[0048] In this embodiment, after the substrate is removed from the etching chamber, it is placed in a temporary storage location. This temporary storage location has the same inert gas atmosphere as the etching chamber, such as nitrogen or argon. This prevents the substrate from being oxidized or contaminated by oxygen or moisture in the air while awaiting re-entry, thereby ensuring substrate quality. In one embodiment, the temporary storage location may be located in a separate buffer chamber.

[0049] In this embodiment, the contaminant removal command is triggered based on a back helium anomaly alarm signal. In the dry etching process, the substrate is fixed to the chuck by electrostatic adsorption, while helium gas is introduced through the back of the chuck to aid heat dissipation. When particulate matter is deposited on the chuck surface, the substrate cannot adhere tightly to the chuck, leading to back helium leakage, and the system will issue a back helium anomaly alarm. At this time, the control system can automatically determine that cavity cleaning is required and trigger the removal method of this invention, thereby achieving timely handling of contamination problems without manual intervention and preventing the escalation of process anomalies.

[0050] In this embodiment, when the substrate is removed from the etching cavity, the vacuum adsorption groove at the end of the transfer arm adsorbs onto the edge region of the substrate, rather than the effective processing area. This avoids contamination or mechanical damage to the effective area of ​​the substrate.

[0051] like Figures 2-4 As shown, the present invention also provides an etching cavity contaminant removal device, comprising: The etching cavity contains a chuck that holds the substrate to be processed. In one embodiment, the chuck is an electrostatic chuck, which holds the substrate in place by electrostatic attraction.

[0052] The cleaning wafer has an adhesive functional layer coated on its back side, and its structure and materials are as described in the previous embodiments. The cleaning wafer is a single-use consumable that can be discarded after use to avoid cross-contamination.

[0053] A wafer transfer arm is used to transfer substrates and clean wafers. In one embodiment, the end of the transfer arm has a vacuum adsorption groove or mechanical gripper that can safely grip the wafer without damaging its surface.

[0054] The plasma purging assembly includes a gas supply line, a mass flow controller, an RF power supply, and electrodes. This assembly is used to perform plasma purging of the interior of the etching chamber after the clean wafer has been removed, to remove residual minute contaminants.

[0055] The control unit communicates with the wafer transfer arm, plasma purging assembly, and the main control system for the etching process. The control unit is responsible for receiving contaminant removal commands and coordinating the timing of actions of various components, such as controlling the movement of the transfer arm, pausing the etching process, and initiating plasma purging.

[0056] In some embodiments, the cleaning device further includes a sealed contaminant collection box, disposed inside or outside the etching equipment, for storing the cleaned wafers after use. The collection box has good sealing properties to prevent contaminants adsorbed on the cleaned wafers from re-escapeing into the environment.

[0057] In this embodiment, the device further includes a sample transfer chamber. A valve is provided between the sample transfer chamber and the etching chamber. The function of the sample transfer chamber is to allow the clean wafer to be fed in and removed while maintaining a vacuum in the etching chamber. Specifically, during use, the clean wafer is placed in the sample transfer chamber. At this time, the valve of the sample transfer chamber is closed, and the sample transfer chamber is in an atmospheric environment. A vacuum operation is performed on the sample transfer chamber to make its internal vacuum level consistent with that of the etching chamber. Then, the valve is opened, and the wafer is transferred to the etching chamber through the wafer transfer arm.

[0058] In this embodiment, the interior of the sealed contaminant collection box is coated with an anti-stick coating or uses a disposable liner structure. Once the collection box is full of used clean wafers, it can be removed entirely and disposed of harmlessly, preventing the spread of contaminants.

[0059] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for removing contaminants from an etching cavity, characterized in that, include: In response to a contaminant removal command within the etching chamber, the etching process is paused, and the substrate fixed on the chuck inside the etching chamber is removed from the etching chamber. A clean wafer with an adhesive functional layer is fed into the etching cavity and placed on the chuck; A downward pressure is applied to the clean wafer, pressing it down onto the chuck and holding it therefore for a predetermined time, during which the adhesive functional layer adsorbs contaminants from the surface of the chuck. The clean wafer that has adsorbed the contaminants is removed from the etching cavity; The interior of the etching cavity is purged with plasma; The substrate is reset into the etching cavity and fixed on the chuck to resume the etching process.

2. The method for removing contaminants from an etching cavity according to claim 1, characterized in that, The clean wafer includes an inert material layer and an adhesive functional layer disposed on one side of the inert material layer.

3. The method for removing contaminants from an etching cavity according to claim 2, characterized in that, The material of the inert layer includes silicon, silicon dioxide, or aluminum oxide.

4. The method for removing contaminants from an etching cavity according to claim 1, characterized in that, The material of the adhesive functional layer includes photoresist or PDMS pressure-sensitive adhesive.

5. The method for removing contaminants from an etching cavity according to claim 1, characterized in that, The plasma purging uses oxygen as the purging gas.

6. The method for removing contaminants from an etching cavity according to claim 1, characterized in that, The step of feeding the clean wafer with the adhesive functional layer into the etching cavity includes: The cleaned wafer is placed inside the sample transfer chamber; The sample transfer chamber is evacuated to the same vacuum level as the etching chamber. Open the valve between the sample transfer chamber and the etching chamber, and transfer the clean wafer from the sample transfer chamber to the etching chamber through the wafer transfer arm.

7. The method for removing contaminants from an etching cavity according to claim 1, characterized in that, Placing the cleaned wafer onto the chuck includes: Align the center of the cleaned wafer with the center of the chuck, and ensure that the radial deviation between the cleaned wafer and the chuck is no greater than 0.01 mm.

8. The method for removing contaminants from an etching cavity according to claim 1, characterized in that, The substrate is removed from the etching cavity and placed in a temporary storage location, which has the same inert gas atmosphere as the etching cavity.

9. The method for removing contaminants from an etching cavity according to claim 1, characterized in that, The contaminant removal command is triggered based on a back helium anomaly alarm signal.

10. A device for removing contaminants from an etching cavity, characterized in that, include: An etching cavity, wherein a chuck for supporting a substrate is provided inside the etching cavity; A clean wafer, the back side of which is coated with an adhesive functional layer; A wafer transfer arm for transferring the substrate and the clean wafer; A plasma purging assembly is used to perform plasma purging on the interior of the etching cavity; The control unit is used to control the start and stop of the wafer transfer arm, the plasma purging assembly, and the etching process.

11. The etching cavity contaminant removal device according to claim 10, characterized in that, It also includes a sample transfer chamber, and a gate valve is provided between the sample transfer chamber and the etching chamber. The sample transfer chamber is used to deliver and remove the clean wafer while maintaining the vacuum of the etching chamber.

Images