In-situ monitoring system and method for chamber cleaning process of thin film deposition equipment
By introducing a plasma generation chamber and a spectrometer system into the thin film deposition equipment, the intensity of plasma spectral lines can be monitored and corrected in real time. This solves the problem of difficulty in controlling the degree of cleanliness in the chamber cleaning technology of thin film deposition equipment, and enables accurate determination of the cleaning endpoint and extension of equipment life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI IDEAOPTICS CORP LTD
- Filing Date
- 2023-03-07
- Publication Date
- 2026-07-31
AI Technical Summary
Existing chamber cleaning technologies for thin film deposition equipment rely on experience to determine the cleaning time, making it difficult to control the degree of cleaning. This can result in insufficient or excessive cleaning, affecting the repeatability of the coating process and the lifespan of the equipment, while also increasing costs.
The system combines a plasma generation chamber and a spectrometer. By monitoring the plasma emission spectrum and using a controller to correct the intensity of ion characteristic spectral lines in real time, the cleaning endpoint can be accurately determined, avoiding interference from external factors.
It enables precise determination of the cleaning endpoint, ensures the repeatability of the coating process, extends equipment life, and saves on cleaning gas costs.
Smart Images
Figure CN116607124B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of thin film deposition technology, and specifically to an in-situ monitoring system and method for chamber cleaning process in thin film deposition equipment. Background Technology
[0002] Thin film deposition technology is widely used in semiconductor manufacturing processes and can generally be divided into physical vapor deposition (PVD) and chemical vapor deposition (CVD) technologies. PVD deposition technology includes sputtering, electron beam deposition, and thermal evaporation techniques. CVD technology mainly includes atmospheric pressure chemical vapor deposition (APCVD), low pressure chemical vapor deposition (LPCVD), sub-atmospheric pressure chemical vapor deposition (SACVD), atomic layer deposition (ALD), and plasma-enhanced chemical vapor deposition (PECVD). Thin film deposition technology uses sputtering, evaporation, radio frequency, and other methods to transfer source material injected into the chamber of a thin film deposition equipment to the substrate surface of the chamber through a series of physical and chemical reactions to form a solid film. During the entire thin film deposition process, in addition to the substrate surface, thin films are also deposited on the inner walls of the thin film deposition equipment chamber and the spray head. This may lead to abnormal reactions of subsequent source materials or defects in the thin film deposition, so the thin film deposition equipment chamber must be cleaned regularly. The following two methods are commonly used for cleaning the chamber.
[0003] One method is in-situ cleaning, which involves injecting fluorine-based cleaning gases such as NF3 or SF6 into the chamber. The gas is then dissociated using radio frequency or other methods to generate plasma, which reacts with and removes deposits inside the chamber. This method may cause some damage to the equipment and shorten the lifespan of internal components.
[0004] Another method for chamber cleaning is remote cleaning. This method differs from in-situ cleaning in that it doesn't generate plasma within the chamber. Instead, near the gas injection point, radio frequency or microwaves are used to dissociate cleaning gas molecules and generate plasma. Active free radicals are then injected into the chamber, reacting with and removing internal deposits. Compared to in-situ cleaning, this method reduces damage to the equipment while maintaining good cleaning efficiency.
[0005] During the cleaning process, it is necessary to prevent insufficient cleaning to avoid the impact of unremoved deposits in the thin film deposition equipment chamber on subsequent deposition reactions. At the same time, over-cleaning must be avoided to prevent damage to the chamber wall components caused by highly reactive fluorine-containing groups over prolonged periods. Therefore, it is essential to accurately determine the cleaning endpoint and stop the cleaning process promptly.
[0006] Current chamber cleaning technologies for thin film deposition equipment rely on experience-based, fixed-duration cleaning. Therefore, when there is a significant amount of deposit in the chamber, this method results in incomplete removal of impurities, which can negatively impact subsequent thin film deposition reactions. Conversely, when there is a small amount of deposit, this method leads to over-cleaning. The inner walls of the thin film deposition equipment chamber are damaged and have a reduced lifespan due to prolonged exposure to highly reactive fluorine-containing groups. Furthermore, over-cleaning consumes large quantities of expensive cleaning gases, such as NF3, significantly increasing costs.
[0007] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention
[0008] To overcome the shortcomings of existing technologies, an in-situ monitoring system and method for chamber cleaning in thin film deposition equipment is provided to address the problem that existing chamber cleaning in thin film deposition equipment is based on experience and fixed cleaning time, which cannot effectively control the degree of cleaning.
[0009] To achieve the above objectives, an in-situ monitoring system for the chamber cleaning process of a thin film deposition apparatus is provided, comprising:
[0010] A plasma generating chamber is connected to the exhaust gas output pipe of the chamber of the thin film deposition equipment, and an observation window is provided on the side wall of the plasma generating chamber;
[0011] A plasma generator is installed in the plasma generating chamber;
[0012] A spectrometer for collecting plasma emission spectra, the spectrometer being connected to the observation window via a light guide;
[0013] The controller includes a control module connected to the thin film deposition equipment and the spectrometer; an extraction module for obtaining the first ion characteristic spectral line of the cleaning gas and the second ion characteristic spectral line of the impurities to be cleaned from the plasma emission spectrum; a calculation module for calculating a correction coefficient based on the actual and theoretical intensities of the first ion characteristic spectral line; a correction module for correcting the second ion characteristic spectral line based on the correction coefficient; and a determination module for generating a cleaning endpoint signal based on the inflection point of the corrected second ion characteristic spectral line. The extraction module is connected to the control module, the calculation module is connected to the extraction module, the correction module is connected to the calculation module, and the determination module is connected to the correction module and the control module. The control module acquires the cleaning endpoint signal and sends it externally, and the thin film deposition equipment receives the cleaning endpoint signal and responds based on the cleaning endpoint signal.
[0014] Furthermore, the plasma generating device is a radio frequency plasma source, a microwave plasma source, an electron beam plasma source, a laser plasma source, or other plasma sources.
[0015] Furthermore, the light guide is an optical fiber.
[0016] Furthermore, the cleaning gas is NF3 or SF6, and the first ion characteristic spectral line is the ion characteristic spectrum of F ions.
[0017] This invention provides a method for in-situ monitoring of the chamber cleaning process in a thin film deposition equipment using a chamber cleaning process in-situ monitoring system, comprising the following steps:
[0018] The plasma generating chamber is connected to the exhaust gas output pipe of the chamber of the thin film deposition equipment, so that the reaction exhaust gas in the exhaust gas output pipe is input into the plasma generating chamber;
[0019] The plasma generator ionizes all components such as gas molecules, atoms, and free radicals in the reaction tail gas in the plasma generation chamber into ions to obtain a plasma with stable energy and density.
[0020] The spectrometer collects the plasma emission spectrum in the plasma generation chamber through a light guide.
[0021] The controller's control module acquires the plasma emission spectrum;
[0022] The extraction module of the controller obtains the first ion characteristic spectral line of the cleaning gas and the second ion characteristic spectral line of the impurities to be cleaned from the plasma emission spectrum of the thin film deposition equipment.
[0023] The controller's calculation module calculates a correction coefficient based on the actual intensity of the first ion characteristic spectral line and the theoretical intensity of the clean gas.
[0024] Furthermore, by using model prediction and deep learning methods, a mapping relationship between the intensity of the first ion characteristic spectral line and the gas flow rate and RF power supply voltage drift can be established using a dataset, thereby obtaining the correction coefficient of the second ion characteristic spectral line.
[0025] Furthermore, in actual operation, the intensity of the second ion characteristic spectral line used for the endpoint detection of chamber cleaning in thin film deposition equipment is corrected in real time using a library search method;
[0026] The controller's correction module corrects the second ion characteristic spectral line based on the correction coefficient;
[0027] The controller's determination module generates a clean endpoint signal based on the inflection point of the corrected second ion characteristic spectral line;
[0028] The control module acquires the cleaning endpoint signal and sends it externally.
[0029] The thin film deposition apparatus receives the cleaning endpoint signal and responds based on the cleaning endpoint signal.
[0030] The beneficial effects of this invention are that the in-situ monitoring system for the chamber cleaning process of the thin film deposition equipment of this invention can perform endpoint detection of chamber cleaning for any cleaning gas without being limited by the type of gas. During the monitoring process, the intensity of the target spectral line is corrected in real time by using the correction coefficient obtained by the change of the intensity of the reference spectral line over time. It is not affected by external factors such as the drift of the bias voltage of the radio frequency power supply or the fluctuation of the gas flow rate, thereby accurately determining the cleaning endpoint, ensuring the repeatability of the coating process, extending the life of the chamber components, and saving user costs. Attached Figure Description
[0031] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:
[0032] Figure 1 This is a schematic diagram of the in-situ monitoring system for the chamber cleaning process of a thin film deposition apparatus according to an embodiment of the present invention.
[0033] Figure 2 This is a plasma emission spectrum of the clean gas in the chamber according to an embodiment of the present invention.
[0034] Figure 3 This is a measured inflection point diagram of the characteristic spectrum of silicon ions according to an embodiment of the present invention.
[0035] Figure 4 This is a second ion characteristic spectrum of the impurity to be cleaned according to an embodiment of the present invention.
[0036] Figure 5 This is a schematic diagram showing the actual intensity and theoretical intensity of the first ion characteristic spectral line of the clean gas in an embodiment of the present invention.
[0037] Figure 6 This is a corrected second ion characteristic spectrum diagram according to an embodiment of the present invention. Detailed Implementation
[0038] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.
[0039] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.
[0040] Reference Figures 1 to 6 As shown, the present invention provides an in-situ monitoring system for the chamber cleaning process of a thin film deposition equipment, comprising: a plasma generation chamber 1, a plasma generation device 2, a spectrometer 3, and a controller 4.
[0041] The plasma generating chamber 1 is connected to the exhaust gas output pipe 56 of the chamber 51 of the thin film deposition equipment 5. The side wall of the plasma generating chamber 1 has an observation window.
[0042] The plasma generator 2 is installed in the plasma generation chamber 1.
[0043] The spectrometer 3 is connected to the observation window via a light guide 31. The spectrometer 3 is used to collect the plasma emission spectra of gases such as exhaust gas in the plasma generation chamber.
[0044] The controller 4 includes a control module, an extraction module, a calculation module, a correction module, and a judgment module.
[0045] The control module is connected to the thin film deposition equipment 5 and the spectrometer 3. The extraction module is connected to the control module. The calculation module is connected to the extraction module. The correction module is connected to the calculation module. The decision module is connected to both the correction module and the control module.
[0046] Specifically, the extraction module is used to obtain the first ion characteristic spectral line of the cleaning gas of the thin film deposition device 5 and the second ion characteristic spectral line of the impurities to be cleaned from the plasma emission spectrum.
[0047] The calculation module is used to calculate the correction coefficient based on the actual intensity and theoretical intensity of the first ion characteristic spectral line.
[0048] The correction module is used to correct the characteristic spectral lines of the second ion based on the correction coefficient.
[0049] The determination module is used to generate a clean endpoint signal based on the inflection point of the corrected second ion characteristic spectral line.
[0050] The control module acquires the cleaning endpoint signal and transmits it externally. The thin film deposition equipment 5 receives the cleaning endpoint signal and responds based on it.
[0051] The plasma generating device 2 is a radio frequency plasma source, microwave plasma source, electron beam plasma source, laser plasma source or other plasma source.
[0052] The light guide 31 is an optical fiber.
[0053] The thin film deposition apparatus 5 includes a main unit, a chamber 51, a gas injection pipe 52, a remote plasma generator 53, a radio frequency source 54, and a tail gas output pipe 56.
[0054] In a preferred embodiment, the cleaning gas is NF3 or SF6.
[0055] In this embodiment, the cleaning gas is NF3. The following detailed description uses NF3 as an example.
[0056] Clean gas is injected into the chamber via a gas injection tube to react with the SiO2 deposits in the chamber. As the clean gas passes through the gas injection tube, a remote plasma generator dissociates the clean gas and generates fluorine-containing active groups. This glow discharge reaction is as follows:
[0057]
[0058] Next, active fluorine groups are injected into the chamber of the thin film deposition equipment, where they react chemically with the deposits (such as silicon dioxide, SiO2) deposited on the inner wall of the chamber to generate gaseous SiF4. This gas is then drawn away by a vacuum pump through the exhaust pipe, thus completing the cleaning of the chamber. Some incompletely dissociated NF3 may also enter the chamber and react with SiO2, as shown in the following reaction:
[0059] 4F * +SiO2→SiF4+O2
[0060] 4NF3 + 3SiO2 → 2NO + 2NO2 + 3SiF4
[0061] In cases where no plasma is generated in the main chamber during the chamber cleaning process, making it impossible to directly observe the plasma emission spectrum signal,...
[0062] This invention adds a plasma generation chamber to the exhaust gas outlet pipe, diverting the exhaust gas within the chamber and adding a plasma generation device inside. The plasma generation device is stably maintained at high power to ionize all gas molecules, atoms, free radicals, and other components in the plasma generation chamber into ions, resulting in plasma with stable energy and density. Since a large number of ions in the plasma are in excited states, they spontaneously transition to the ground state, emitting photons. Therefore, by using an observation window on the side wall of the plasma generation chamber, combined with a light guide, spectrometer, and controller, the plasma emission spectral signal is collected, analyzed, and processed. This allows for the extraction of effective signals from complex plasma signals, providing a cleaning endpoint signal to the thin film deposition equipment to promptly stop the chamber cleaning process.
[0063] In an ideal situation, Figure 2 For example, multiple characteristic spectral lines can be observed in the 200nm–850nm wavelength range. By monitoring the change of the characteristic spectral line from Si ions at 288.2nm over time, it can be seen that since there is no longer any Si element in the chamber after the cleaning endpoint is reached, such as... Figure 3 As shown, the intensity of this spectral line suddenly decreases after a certain period of cleaning, thus indicating the arrival of the cleaning endpoint.
[0064] However, in actual practice, such as Figure 4 As shown, taking the change in the intensity of the spectral line at 288.2 nm from Si ions during the cleaning of SiO2 with NF3 as an example, it can be seen that there are multiple points where the spectral line intensity decreases. However, this change is caused by the drift of the RF power supply voltage or the fluctuation of the gas flow rate, which theoretically should not exist. The use of plasma emission spectroscopy signal methods to determine the endpoint of chamber cleaning is usually based on threshold or slope algorithms, that is, when the change in the intensity of the spectral line at a specific wavelength reaches a certain level, the endpoint is output. Therefore, Figure 4 The decrease in spectral line intensity at multiple points may be incorrectly identified as the cleaning endpoint, rather than the actual chamber cleaning endpoint.
[0065] In this invention, since the plasma generating device in the plasma generating chamber is kept at high power, all gas molecules in the exhaust gas can be dissociated to generate ions. For this reaction, nitrogen ions, silicon ions, fluoride ions and oxygen ions will eventually be generated.
[0066] Considering that fluoride ions are introduced by the cleaning gas, and that the flow rate at the injected gas end is constant under ideal conditions throughout the cleaning process, the number of fluoride ions in the entire plasma generation chamber should theoretically remain in dynamic equilibrium, assuming the plasma generator is stable. Correspondingly, the intensity of the characteristic spectral lines emitted by fluoride ions in the measured plasma emission spectrum should also be a constant value, not changing over time. However, in actual cleaning processes, due to drift in the RF power supply voltage or fluctuations in gas flow, the actual characteristic spectral lines emitted by fluoride ions may differ. Figure 5 As shown by the dashed line A.
[0067] Therefore, a correction coefficient for the intensity is obtained by real-time calculation based on the measured characteristic spectral line intensity of fluoride ions and the theoretical intensity. That is, the controller's calculation module establishes a mapping relationship between the characteristic spectral line intensity of fluoride ions and gas flow rate and RF power supply voltage drift through the dataset using model prediction and deep learning methods, thereby obtaining the correction coefficient of Si ion spectral lines. In actual operation, the intensity of Si ions used for the end-point detection of chamber cleaning in thin film deposition equipment is corrected in real time by library search.
[0068] like Figure 6 As shown, the change in Si ion intensity over time after correction is no longer affected by external factors such as the drift of the RF power supply voltage or the fluctuation of the gas flow rate, and can be effectively used for the endpoint detection of chamber cleaning.
[0069] The in-situ monitoring system for chamber cleaning in the thin film deposition equipment of this invention can perform endpoint detection for any cleaning gas, without being limited by the type of gas. During the monitoring process, the intensity of the target spectral line is corrected in real time by using a correction coefficient obtained by the change of reference spectral line intensity over time. Therefore, it is not affected by external factors such as the drift of radio frequency power supply voltage or the fluctuation of gas flow, thus accurately determining the cleaning endpoint. This ensures the repeatability of the coating process, extends the life of chamber components, saves a large amount of expensive cleaning gas, and reduces user costs.
[0070] This invention provides a method for in-situ monitoring of the chamber cleaning process in a thin film deposition equipment using a chamber cleaning process in-situ monitoring system, comprising the following steps:
[0071] S1: Connect the plasma generating chamber 1 to the tail gas output pipe 56 of the chamber 51 of the thin film deposition equipment 5, so that the reaction tail gas in the tail gas output pipe 56 is input into the plasma generating chamber 1.
[0072] S3: The plasma generator 2 ionizes all components such as gas molecules, atoms, and free radicals in the reaction tail gas of the plasma generation chamber 1 into ions to obtain a plasma with stable energy and density.
[0073] S4: Spectrometer 3 collects the plasma emission spectrum in plasma generation chamber 1 through light guide 31.
[0074] S5: The control module of controller 4 acquires the plasma emission spectrum.
[0075] S6: The extraction module of controller 4 obtains the first ion characteristic spectral line of the cleaning gas and the second ion characteristic spectral line of the impurities to be cleaned from the plasma emission spectrum of the thin film deposition equipment 5.
[0076] S7: The calculation module of controller 4 calculates the correction coefficient based on the actual intensity and theoretical intensity of the first ion characteristic spectral line.
[0077] See Figure 5 The diagram shows a schematic of the first ion characteristic spectral line A and the theoretical characteristic spectral line B of a clean gas.
[0078] S8: The correction module of controller 4 corrects the second ion characteristic spectral line based on the correction coefficient.
[0079] S9: The determination module of controller 4 generates a clean endpoint signal based on the inflection point of the corrected second ion characteristic spectral line.
[0080] S10: The control module acquires the cleaning endpoint signal and sends it out.
[0081] S11: Thin film deposition equipment 5 receives the cleaning endpoint signal and responds based on the cleaning endpoint signal.
[0082] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.
Claims
1. A chamber cleaning process in-situ monitoring system for a thin film deposition apparatus, characterized by, include: A plasma generating chamber is connected to the exhaust gas output pipe of the chamber of the thin film deposition equipment, and an observation window is provided on the side wall of the plasma generating chamber; A plasma generator is installed in the plasma generating chamber; A spectrometer for collecting plasma emission spectra, the spectrometer being connected to the observation window via a light guide; The controller includes a control module connected to the thin film deposition equipment and the spectrometer; an extraction module for obtaining the first ion characteristic spectral line of the cleaning gas and the second ion characteristic spectral line of the impurities to be cleaned from the plasma emission spectrum; a calculation module for calculating a correction coefficient based on the actual and theoretical intensities of the first ion characteristic spectral line; a correction module for correcting the second ion characteristic spectral line based on the correction coefficient; and a determination module for generating a cleaning endpoint signal based on the inflection point of the corrected second ion characteristic spectral line. The extraction module is connected to the control module, the calculation module is connected to the extraction module, the correction module is connected to the calculation module, and the determination module is connected to the correction module and the control module. The control module acquires the cleaning endpoint signal and sends it externally, and the thin film deposition equipment receives the cleaning endpoint signal and responds based on the cleaning endpoint signal.
2. The in-situ monitoring system for chamber cleaning process of thin film deposition equipment according to claim 1, characterized in that, The plasma generating device includes a radio frequency plasma source, a microwave plasma source, an electron beam plasma source, or a laser plasma source.
3. The in-situ monitoring system for chamber cleaning process of thin film deposition equipment according to claim 1, characterized in that, The light guide is an optical fiber.
4. The in-situ monitoring system for chamber cleaning process of thin film deposition equipment according to claim 1, characterized in that, The cleaning gas is NF3 or SF6, and the first ion characteristic spectral line is the ion characteristic spectrum of F ions.
5. A method for in-situ monitoring of chamber cleaning processes in a thin film deposition apparatus using the chamber cleaning process in-situ monitoring system of any one of claims 1 to 4, characterized in that, Includes the following steps: The plasma generating chamber is connected to the exhaust gas output pipe of the chamber of the thin film deposition equipment, so that the reaction exhaust gas in the exhaust gas output pipe is input into the plasma generating chamber; The plasma generator ionizes components such as gas molecules, atoms, and free radicals in the reaction tail gas in the plasma generation chamber into ions to obtain a plasma with stable energy and density. The spectrometer collects the plasma emission spectrum in the plasma generation chamber through a light guide. The controller's control module acquires the plasma emission spectrum; The extraction module of the controller obtains the first ion characteristic spectral line of the cleaning gas and the second ion characteristic spectral line of the impurities to be cleaned from the plasma emission spectrum of the thin film deposition equipment. The controller's calculation module calculates the correction coefficient based on the actual intensity and theoretical intensity of the first ion's characteristic spectral line; The controller's correction module corrects the second ion characteristic spectral line based on the correction coefficient; The controller's determination module generates a clean endpoint signal based on the inflection point of the corrected second ion characteristic spectral line; The control module acquires the cleaning endpoint signal and sends it out. The thin film deposition apparatus receives the cleaning endpoint signal and responds based on the cleaning endpoint signal.